SEPA
United States
Environmental Protection
Agency
Industrial Environmental Research EPA-600/7-79-098b
Laboratory April 1979
Research Triangle Park NC 27711
Proceedings: Symposium
on Coal Cleaning to
Achieve Energy and
Environmental Goals
(September 1978,
Hollywood, FL) -
Volume II
Interagency
Energy/Environment
R&D Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-79-098b
April 1979
Proceedings: Symposium on Coal
Cleaning to Achieve Energy
and Environmental Goals
(September 1978, Hollywood, FL) -
Volume II
by
S.E. Rogers and A.W. Lemmon, Jr. (Editors)
Battelle Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Contract No. 68-02-2163
Task No. 861
Program Element No. EHE624A
EPA Project Officer: James D. Kilgroe
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
The Symposium on Coal Cleaning to Achieve Energy and Environmental Goals
was sponsored by the U.S. EPA's Industrial Environmental Research Laboratory
under Contract No. 68-02-2163, Task No. 861. The Symposium was held September
11-15, 1978, in Hollywood, Florida. The program provided an opportunity
for mutual review and discussion of the physical and chemical coal cleaning
programs of EPA, DoE, the Electric Power Research Institute, those of
numerous industrial organizations, and European and Soviet plans for the
future, as well as the problems of ongoing operations.
The Proceedings contain the contributions of the participating speakers
and include the following topics:
(a) Coal Characteristics
(b) Coal Cleaning Overview
(c) Physical Coal Cleaning Technology
(d) Environmental Assessment and Pollution Control Technology
(e) Chemical Coal Cleaning Technology.
ii
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FOREWORD
Man and his environment must be protected from the adverse effects of
pesticides, radiation, noise, industrial effluents, and other forms of
pollution, as well as the unwise management of solid waste. Efforts to
protect the environment require a focus that recognizes the interplay among
the components of our physical and biological environment—air, water, land,
plants, and animals. The Industrial Environmental Research Laboratory (IERL/
RTF) of the U.S. Environmental Protection Agency (EPA) located at Research
Triangle Park, North Carolina, contributes to this multidisciplinary focus
through programs engaged in:
• studies on the effects of environmental contaminants on
the biosphere, and
• a search for ways to prevent contamination and to recycle
valuable resources.
This Symposium Proceedings deals with the subject matter of concern to
an IERL/RTP program designed to focus on the effectiveness and efficiency of
coal cleaning processes as a means of reducing the total environmental impact
of energy production through coal utilization. The Symposium itself provided
a most vital communication link between the researcher and engineer on the
one hand and the user community on the other. To enhance future communica-
tion processes and encourage future applications of coal cleaning technology,
this Symposium Proceedings documents the results of the meeting held.
iii
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ACKNOWLEDGMENT
No symposium can be a success without the support and participation of
the attendees. For those participants listed elsewhere in this document,
then, we are grateful for their contributions. Thanks in full measure is
due also to the Session Chairmen and Cochairmen who patiently labored to
formulate an informative and timely program. And, of course, none of this
would have been possible without the long hours spent by the authors indivi-
dually and collectively, in the preparation of their papers.
Thanks are also due for the handling of the mechanical details of the
Symposium. These necessary functions were performed ably by a number of
people. Mr. Jack H. Greene (IERL/RTP) was responsible for the overall
arrangements with the hotel, and Ms. Susan R. Armstrong, Conference Coor-
dinator at Battelle's Columbus Laboratories (BCL), managed the day-to-day
activities. She was assisted in the many details of the necessary operations
by Ms. Joyce B. Fowler (IERL/RTP), Mrs. Rebecca S. Miller (BCL), and Mrs. Lucy
G. Pierson (BCL).
Special thanks are expressed to Mrs. Alexis W. Lemmon, Jr., and
Mrs. L. David Tamny for their efforts in making the week more pleasant
for the distaff accompaniers of the Symposium participants.
In the preparation of the printed Symposium Proceedings, Ms. Sharron
E. Rogers performed excellently as Technical Editor. Mrs. Miller and
Mrs. Pierson organized, formatted, and provided the necessary typing. We
are grateful for their assistance.
iv
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TABLE OF CONTENTS
Page
Abstract ±±
Foreword iii
Acknowledgment iv
Final Program 1
Conference Report and Activities 5
Session 0; Coal Characteristics
PETROGRAPHY OF COAL 9
Ronald W. Stanton and Robert B. Finkelman
U.S. Geological Survey
MINERALOGIC.. AFFINITIES OF TRACE ELEMENTS IN COAL 29
F. L. Fiene , J. K. Kuhn , and H. J. Gluskoter
Illinois State Geological Survey
2
Exxon Production Research Company
EFFECTS OF COAL CLEANING ON ELEMENTAL DISTRIBUTIONS 59
Charles T. Ford and James F. Boyer
Bituminous Coal Research, Inc.
PARTICLE SIZE DISTRIBUTION IN THE LIBERATION OF PYRITE IN COAL ... 91
Harold L. Lovell
The Pennsylvania State University
GEOLOGIC CONTROLS ON MINERAL MATTER IN THE
UPPER FREEPORT COAL BED HO
C. B. Cecil, R. W. Stanton, S. D. Allshouse, and R. B. Finkelman
U.S. Geological Survey
INTERPRETING STATISTICAL VARIABILITY 126
Ralph E. Thomas
Battelle's Columbus Laboratories
Session 1; Coal Cleaning Overview
AN OVERVIEW OF EPA COAL CLEANING PROGRAMS 149
J. D. Kilgroe and D. A. Kirchgessner
U.S. EPA, IERL-RTP
OVERVIEW OF DOE COAL CLEANING PROGRAM 171
Cyril W. Draffin
U.S. Department of Energy
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TABLE OF CONTENTS
(Continued)
Page
OVERVIEW OF EPRI COAL CLEANING PROGRAMS , 194
Kenneth Clifford and Shelton Ehrlich
Electric Power Research Institute
AN INTEGRATED ASSESSMENT OF GOAL TECHNOLOGIES !95
Richard S. Davidson
Battelle's Columbus Laboratories
THE MAIN TRENDS OF WORKS ON ENVIRONMENTAL PROTECTION
AGAINST THE INFLUENCE OF COAL-PREPARATION PLANTS IN THE USSR .... 207
I. S. Blagov, G. G. Vosnyuk, V. V, Kochetov,
I. Ch. Nekhoroshy, and I. E. Cherevko
USSR Ministry of Coal Industry
THE CLEAN FUEL SUPPLY: FACTORS AFFECTING U.S. AND EUROPEAN
SO, EMISSIONS IN THE MID-19801 s 228
Anthony Bromley and Gary J. Foley
Organization of Economic Cooperation and Development
A TECHNICAL AND ECONOMIC OVERVIEW OF CDAL CLEANING 256
Horst Huettenhain, Jackson Yu, and Samuel Wong
Bechtel National, Inc. and Argonne National Laboratory
OVERCOMING THE BARRIERS TO INVESTMENT IN PHYSICAL COAL
CLEANING WITH REVISED NSPS FOR UTILITY BOILERS 298
Karel Fisher and Peter Cukor
Teknekron, Inc.
ECONOMICS OF COAL CLEANING AND FLUE GAS DESULFURIZATION FOR
COMPLIANCE WITH REVISED NSPS FOR UTILITY BOILERS 324
Randy M. Cole
Energy Research-Combustion Systems
Tennessee Valley Authority
THE ECONOMICS OF BENEFICIATING AND MARKETING
HIGH-SULFUR IOWA COAL 360
C. Phillip Baumel, John J. Miller and Thomas P. Drinka
Department of Economics, Iowa State University
Session 2; Physical Coal Cleaning Technology
AN EVALUATION OF THE DESULFURIZATION POTENTIAL OF U.S. COALS 387
Jane H. McCreery and Frederick K. Goodman
Battelle's Columbus Laboratories
THE USE OF COAL CLEANING FOR COMPLYING WITH SO.
EMISSION REGULATIONS 7 416
Elton H. Hall and Gilbert E. Raines
Battelle's Columbus Laboratories and
Raines Consulting, Incorporated
vi
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TABLE OF CONTENTS
(Continued)
Page
STATISTICAL CORRELATIONS ON COAL DESULFURIZATION BY
CRUSHING AND SPECIFIC GRAVITY SEPARATION .............. 448
Ralph E. Thomas
Battelle's Columbus Laboratories
DEWATERING AND DRYING OF FINE COAL: EQUIPMENT
PERFORMANCE AND COSTS .......................
Donald H. Sargent, Bill H. Cheng, and G. Yeghyazarian Contos
Versar, Inc.
HOMER CITY COAL CLEANING DEMONSTRATION, TEST, AND
TECHNOLOGY EVALUATION PROGRAM ................... 488
James H. Tice
Pennsylvania Electric Company
COMPUTER CONTROL OF COAL PREPARATION PLANTS .......... • • 503
Gerry Norton, George Hambleton, and Clive Longden
Norton-Ramble ton Associates, Inc.
PHYSICAL AND PHYSIOCHEMICAL REMOVAL OF SULFUR FROM COAL ...... 519
David H. Birlingmair and Ray W. Fisher
Ames Laboratory, Iowa State University
CLEANING OF EASTERN BITUMINOUS COALS BY FINE GRINDING,
FROTH FLOTATION AND HIGH-GRADIENT MAGNETIC SEPARATION ....... 534
W. L. Freyberger, J. W. Keck, D. W. Spottiswood,
N. D. Solem and Virginia L. Doane
Michigan Technological University
THE POTENTIAL OF MAGNETIC SEPARATION ll» COAL CLEANING ....... 568
Frederick V. Karlson, Kenneth L. Clifford, William W. Slaughter,
and Horst Huettenhain
Bechtel Corporation, Electric Power Research Institute,
and Bechtel National, Inc.
TESTING OF COMMERCIAL COAL PREPARATION PLANTS
WITH A MOBILE LABORATORY ...................... 599
William Higgins and Thomas Plouf
Joy Manufacturing Company
CHEMICAL COMMINUTION— AN IMPROVED ROUTE TO CLEAN COAL ....... 600
Victor C. Quackenbush, Robert R. Haddocks, and George W. Higginson
Catalytic, Inc.
COAL CLEANING BY THE OTISCA PROCESS ................ 623
C. D. Smith
Otisca Industries, Ltd.
vii
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TABLE OF CONTENTS
(Continued;
Session 3; Environmental Assessment and
Pollution Control Technology
Page
THE COAL CLEANING PROGRAM OF THE FUEL
PROCESS BRANCH OF EPA*8 IERL-RTP 637
T. K. Janes
U.S. Environmental Protection Agency
ENVIRONMENTAL ASSESSMENT METHODOLOGIES FOR FOSSIL
ENERGY PROCESSES: AN UPDATE . 646
Robert P. Hangebrauck
U.S. Environmental Protection Agency
REVIEW OF REGULATIONS AND STANDARDS INFLUENCING COAL CLEANING ... 683
P. Van Voris, R. A. Ewing, and J. W. Harrison
Battelle's Columbus Laboratories and Research Triangle Institute
DEVELOPMENT OF ENVIRONMENTAL ASSESSMENT CRITERIA FOR COAL
CLEANING PROCESSES 711
R. A. Ewing, P. Van Voris, B. Cornaby, and G. E. Raines
Battelle's Columbus Laboratories and Raines Consulting, Incorporated
APPLICATION OF ENVIRONMENTAL ASSESSMENT METHODOLOGY TO HOMER
CITY POWER COMPLEX BACKGROUND DATA: COMPARISON WITH MEG VALUES . . 753
D. A. Tolle, D. P. Brown, R. Clark, D. Sharp,
J. M. Stilwell, and B. W. Vlgon
Battelle's Columbus Laboratories
AN OVERVIEW OF CONTROL TECHNOLOGY 793
A. W. Lemmon, Jr., G. L. Robinson, and D. A. Sharp
Battelle's Columbus Laboratories
CHARACTERIZATION OF PREPARATION PLANT WASTEWATERS 824
K. B. Randolph, L. B. Kay, and R. C. Smith, Jr.
Versar, Inc.
CONTROL OF TRACE ELEMENT LEACHING FROM COAL PREPARATION WASTES ... 856
E. M. Wewerka, J. M. Williams, P. Wagner,
L. E. Wangen, and J. P. Bertino
Los Alamos Scientific Laboratory
STABILIZATION OF COAL PREPARATION PLANT SLUDGES 875
David C. Hoffman
Dravo Lime Company
viii
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TABLE OF CONTENTS
(Continued)
Page
CHEMICAL AND BIOLOGICAL CHARACTERIZATION OP LEACHATE
FROM COAL CLEANING WASTES . ...... .... .......... 898
R. M. Schuller, R. A. Griffin, and J. J. Suloway
Illinois State Geological Survey and Illinois State
Natural History Survey
Session 4; Chemical Coal Cleaning
INTRODUCTION TO CHEMICAL COAL CLEANING .............. 923
R. A. Meyers
TRW, Inc.
CURRENT STATUS OF CHEMICAL COAL CLEANING PROCESSES -
AN OVERVIEW ............................ 934
L. C. McCandless and Mrs. G. Y. Contos
Versar, Inc.
STATUS OF THE REACTOR TEST PROJECT FOR CHEMICAL
REMOVAL OF PYRITIC SULFUR FROM COAL ................ 960
M. J. Santy and L. J. Van Nice
TRW, Inc.
STATUS OF HYDROTHERMAL PROCESSING FOR CHEMICAL
DESULFURIZATION OF COAL .................. .... 991
E. P. Stambaugh, H. N. Conkle, J. F. Miller, E. J. Mezey and B. C. Kin
Battelle's Columbus Laboratories
SURVEY OF COALS TREATED BY OXYEESULFURIZATION .... ....... 1016
R. P. Warzinski, J. A. Ruether, S. Friedman, and F. W. Staffgen
U.S. Department of Energy, Pittsburgh Energy Technology Center
COAL DESULFURIZATION BY LEACHING WITH ALKALINE SOLUTIONS
CONTAINING OXYGEN ......................... 1039
R. Markuszewski, K. C. Chuang, and T. D. Wheelock
Ames Laboratory, Iowa State University
THE POTENTIAL FOR CHEMICAL COAL CLEANING: RESERVES,
TECHNOLOGY, AND ECONOMICS ..................... 1064
R. A. Giberti, R. S. Opalanko, and J. R. Sinek
Kennecott Copper Corporation and Resource Engineering, Inc.
JPL COAL DESULFURIZATION PROCESS BY
LOW TEMPERATURE CHLORINOLYSIS ................... !096
John J. Kalvinskas and George C. Hsu
California Institute of Technology
OXIDATIVE COAL DESULFURIZATION USING NITROGEN
OXIDES - THE KVB PROCESS
E. D. Guth
KVB, Inc.
ix
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TABLE OF CONTENTS
(Continued)
Page
THE DRY REMOVAL OF PYRITE AND ASH FROM GOAL BY THE
MAGNEX PROCESS COAL PROPERTIES AND PROCESS VARIABLES 1165
James K. Kindig and Duane N. Goens
Hazen Research, Inc.
PANEL DISCUSSION ON PROSPECTS FOR CHARACTERIZATION
AND REMOVAL OR ORGANIC SULFUR FROM COAL 1197
Chairman: Robin R. Oder; Panelists: Sidney Freidman,
Amir Attar, Douglas M. Jewell, and Thomas G. Squires
Gulf Research and Development Co.; Pittsburgh Energy Research
Center - DOE; University of Houston; Gulf Research and
Development Co.; and Iowa State University
List of Participants 1208
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The Coal Cleaning Program
of the Fuel Process Branch
OF EPA's IERL-RTP
T. Kelly Janes
Chief, Fuel Process Branch
Industrial Environmental Research
Laboratory-RTP
U.S. Environmental Protection Agency
Research Triangle Park, N. C.
EPA's Industrial Environmental Research Laboratory at Research
Triangle Park, N.C., conducts a contractual and In-house research,
development, and demonstration program dealing with the control of
emissions/discharges from energy related technologies and industrial
processes.
The Laboratory is divided into three technical divisions:
1. Utilities and Industrial Power Division which primarily
addresses the emissions controls for the combustion
of fossil fuels to generate steam and electrical power.
2. Energy Assessment and Control Division which develops
improved combustion techniques for nitrogen oxide con-
trol, advanced combustion systems, and the environmental
effects and control techniques for coal processing and
conversion of coal to synthetic liquids and gases.
3. Industrial Processes Division which addresses the emission
and controls from industrial operations. Additionally,
in this Division, analytical and sampling techniques are
developed.
The Fuel Process Branch in the Energy Assessment and Control Division
conducts programs addressing two major areas:
1. Coal Cleaning. Development of physical and chemical tech-
niques to remove contaminants from coal; assessment of
the environmental consequences from the utilization of
coal cleaning processes; and the development of control
technology to avoid adverse discharge effects.
2. Synthetic Fuels. The assessment of the multimedia
discharges and control technique evaluation for tech-
nologies converting coal to gaseous, liquid, and refined
solid fuels.
Both programs deal with the multimedia (air, water, and solid)
discharge effects. However, the coal cleaning program has the additional
responsibility to develop the basic processing technology. In 1965,
638
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EPA (and Its prior organizations) Initiated studies to determine the
applicability of physical coal cleaning to reduce emissions from the
combustion of coal. Early 1n this program 1t was apparent that
additional information would be required before the assessment of
this technology could be made. Thus, numerous projects ware Initiated
to:
1. Evaluate the degree of pyrlte removal which could
be obtained from cleaning of U.S. coals.
2. Determine the effectiveness of comnerdal coal pre-
paration techniques to maximize pyrlte separation.
3. Evaluate processes that could utilize the coal reject
mineral matter to aid in offsetting the increased cost
of coal cleaning.
Since then, the coal cleaning program has passed through three
major phases.
Phase I. The development of data and information which would
provide a data base to assess the applicability of coal cleaning to
maximize sulfur reduction. Technical areas addressed during this
phase were:
- Laboratory evaluation of potential pyrlte ash removal
as affected by size reduction and specific gravity.
- Mineral constituents of U.S. coals.
- Applicability and effectiveness of existing coal cleaning
techniques to maximize pyrite separation and removal.
- Available technology for recovery of economic values from
coal cleaning refuse.
- Quality and quantity of U.S. coal reserves.
- Investigation and development of new or modified physical
cleaning techniques for removal of pyrite and other con-
taminants from coal.
- Design of a coal cleaning pilot plant to evaluate cleana-
bility of coals and performance of cleaning equipment.
Phase II. In the late 1960s, it became quite apparent that
improved cleaning techniques would be necessary to increase sulfur
removal to meet future requirements. These methods would need to be
basically unaffected by pyrite size variations which have a marked
effect on physical separation methods. Thus, a broad evaluation of
various chemical cleaning techniques was conducted. Some 24 chemical
reagents ware evaluated for sulfur removal potential. The results
showed that organic sulfur removal was extremely difficult and that
639
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the inorganic sulfur removal potential was much closer to realization.
Thus, the ferrous sulfate leaching process development was initiated
and carried through reactor pilot evaluation. Additionally, evaluations
of other techniques, using hydrogen and microwave energy, were supported.
The potential effectiveness of organic sulfur removal may well depend
on prior removal of pyrite and other inorganic material.
Phase III. In the early 1970s, natural gas and oil shortages
became a public concern and the need to fully utilize the nation's
vast coal reserves became a federal goal. This concern with energy
and increased use of "coal was accompanied by a parallel concern with
the potential impact that increased coal utilization would have on
the health and ecological systems of the nation. This phase of the
EPA coal cleaning program is concentrating on the Identification of
environmental impacts of discharges by using both chemical and
biological evaluations.
The ongoing program covers a wide spectrum of activities from
coal contaminant variability through evaluation of effects that clean
coal will have on existing controls for combustion waste gas.
During this symposium, details of these ongoing efforts will be
dealt with.
The reports listed on the following pages were prepared under
the sponsorship and direction of IERL-RTP. For convenience these
reports are listed under the following categories: coal characterization,
evaluation of coal cleaning techniques, coal reject treatments, coal
cleaning prototype plant, chemical coal cleaning, and applicability
studies.
640
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EPA/IERL-RTP REPORTS
Contractor
(Contract No,)
NTIS No.
(EPA No.)
Coal Characterization
Illinois State
Geological Survey
(PH 86-67-206)
U.S. Bureau of
Mines
U.S. Bureau of
Mines
Exxon
(68-02-0629)
Illinois State
Geological Survey
(68-02-0246)
U.S. Bureau of
Mines
(IAG-P5-0685)
Los Alamos Scien.
Lab (IAG-D5-E681)
Illinois State
Geological Survey
(68-02-1472)
Los Alamos Scien.
Lab (IAG-D5-E681)
U.S. Dept. of
Energy
(IAG DXE685-W)
PB 206-464
(APTD 0915)
PB 205-952
(APTD 0841)
RI 7633
(APTD 1365)
RI 7608
PB 225-039/7AS
EPA-R2-73-249
PB 238-091/AS
EPA-650/2-74-
054
PB 252-965/AS
EPA-600/2-76-
091
PB 267-339/AS
EPA-600/7-75-
007
PB 270-922/AS
EPA-600/7-77-
064
LA-6835-PR
EPA-600/7-78-
028
PB 280-759/AS
EPA-600/7-78-
038
Report Title -- Date Pufa1ished(No. of Pages)
Sulfur varieties in Illinois coals float
sink tests (final phase I) -- 8/69
(98 pp)
Sulfur reduction of Illinois coal washa-
bility studies (final phase II) — 8/69
(98 pp)
Sulfur reduction potential of the coals
of the U.S. - 1972 (304 pp)
Washability examinations of core samples
of San Juan Basin coals, New Mexico and
Colorado -- 1972 (30 pp)
Potential pollutants in fossil fuels --
6/73 (293 pp)
Occurrence and distribution of potentially
volatile trace elements in coal -- 7/74
(106 pp)
Sulfur reduction potential of U.S. coals:
a revised report of investigations — 4/76
(329 pp)
Environmental contamination from trace
elements in coal preparation wastes —
8/76 (69 pp)
Trace Elements in Coal: occurrence and
distribution -- 6/77 (165 pp)
Trace element characterization of coal
wastes - first annual report -- 3/78
(58 pp)
Washability and analytical evaluation of
potential pollution from trace elements in
coal -- 3/78 (41 pp)
641
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EPA/IERL-RTP REPORTS (cont)
Contractor
(Contract No.)
NTIS No.
(EPA No.)
Evaluation of Coal Cleaning Techniques
Bituminous Coal
Research
(PH 86-67-139)
U.S. Bureau of
Mines
U.S. Bureau of
Mines
Bituminous Coal
Research
(CPA 70-26)
U.S. Bureau of
Mines
U.S. Bureau
Mines
Bituminous Coal
Research
(68-02-0024)
J.J. Davis
(68-02-1834)
Mitre
(68-02-1352)
PB 193-486
(APT1C 23423)
PB 193-484/
193-532
(APTD 0579)
RI 7440
(APTIC 31443)
RI 7518
PB 205-185/
199-484
(APTD 0842)
RI 7623
TPR 51
PB 210-821
(APTD 1160)
PB 262-716/AS
EPA-600/2-76-
138
PB 232-011/AS
EPA-650/2-74-
030
Coal Reject Treatments
Bechtel
(PH 86-67-224)
A. D. Little
(PH 86-67-258)
PB 182-358
(APTD 1266)
PB 182-303
(APTD 1274)
Report Title— Date PubllshedfNo. of Pages}
An evaluation of coal cleaning processes
and techniques for removing pyrltlc sulfur
from fine coal (Interim report) — 9/69
(285 pp)
Same. Final report — 2/70 (146 pp)
Electrophoretlc - specific gravity
separation of pyrlte from coal, laboratory
study - 10/70 (15 pp)
Hydrolyzed metal Ions as pyrlte depressants
1n coal flotation: a laboratory study —
5/71 (26 pp)
An evaluation of coal cleaning processes
and techniques for removing pyrltlc sulfur
from fine coal — Final report - 4/71
(173 pp)
Photoelectric concentrator for the wet
concentrating table — 1972 (10 pp)
Flotation of pyrlte from coal -- 2/72
(9 PP)
An evaluation of coal cleaning processes
and techniques for removing pyrltlc sulfur
from fine coal (final report) -- 4/72
(174 pp)
Coal preparation environmental engineering
manual -- 5/76 (729 pp)
An Interpretative compilation of EPA
studies related to coal quality and
cleanabmty -- 5/74 (276 pp)
Process costs and economics of pyrtte-
coal utilization (final report, Phases
142)-- 12/68 (187 pp)
A study of process costs and economics of
pyrlte-coal utilization (final report) --
3/68 (265 pp)
$42
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Contractor
(Contract No.)
EPA/IERL-RTP REPORTS (cont)
Report Title -- Date Published(No. of Pages)
NTIS No.
(EPA No.)
Coal Reject Treatments (cont)
Chemical Constr.
(CPA 22-69-151)
PB 203-958
(APTD 0768)
PB 203-959
(APTD 0769)
Coal Cleaning Prototype Plant
McNally Pittsburgh PB 196-631
(PH 22-68-59) (APTD 0606)
PB 196-632
(APTD 0607)
PB 196-633
(APTD 0608)
PB 196-634
(APTD 0609)
Roberts/Schaefer
(PH 22-68-62)
Roberts/Schaefer
(CPA 70-157)
PB 220-700
(APTD 0605)
PB 220-701
(APTD 0605)
(Not in NTIS)
EPA-R2-73-154
Chemical Coal Cleaning
TRW
(CPA 71-7)
PB 204-863
{APTD 0845)
PB 221-405
EPA-R2-73-173a
PB 221-406
EPA-R2-73-173B
High sulfur combustor study (Final report)
Vol. I, narrative summary — 2/71 (226 pp)
Same. Vol. II, descriptive detail -- 2/71
(450 pp)
A study on design and cost analysis of a
prototype coal cleaning plant, Parts 1-6 --
7/69 (147 pp)
Coal cleaning plant prototype plant
specifications, Part 7 -- 7/69 (200 pp)
Coal cleaning plant prototype plant
design drawings, Part 8 - 7/69 (20 pp)
Design and cost analysis of a prototype
coal cleaning plant. Supplement -- 7/69
(13 pp)
Design and cost analysis study for a
prototype coal cleaning plant, Vol. I —
8/69 (109 pp)
Same. Vol. II -- 8/69 (211 pp)
Research program for the prototype coal
cleaning plant - 1/73 (133 pp)
Chemical removal of nitrogen and organic
sulfur from coal (final report) -- 5/71
(60 pp)
Chemical desulfurization of coal: report
of bench scale developments. Vol. I —
2/73 (184 pp)
Same. Vol. II -- 2/73 (85 pp)
643
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Contractor
(Contract No.)
EPA/IERL-RTP REPORTS (cont.)
Report Title -- Date Published(No. of Pages!
NTIS No.
(EPA No.)
Chemical Coal Cleaning (cont)
TRW
(68-02-0647)
Dow Chemical
(68-02-1329)
Exxon
(68-02-0629)
TRW
(68-02-1336)
TRW
(68-02-1335)
PB 232-083/AS
EPA-650/2-74-
025
PB 254-461/AS
EPA-650/2-74-
025a
PB 241-927/AS
EPA-650/2-75-032a
PB 246-311/AS
EPA-650/2-74-009k
PB 261-128/AS
EPA-600/2-76-143a
PB 261-129/AS
EPA-600/2-76-143b
PB 270-111/AS
EPA-600/2-77-
080
Applicability Studies
Mitre PB 210-373
(F-192628-68C-0365) (APTD 0844)
PB 197-386
(APTD 0627)
PB 197-387
(APTD 0628)
Hittman Associates PB 209-266
(EHSD 71-43)
Mitre
(USAF 723)
M. W. Kellogg
(68-02-1308)
(APTD 1079)
PB 211-505
EPA-R2-72-022
PB 239-496/AS
EPA-650/2-74-127
Applicability of the Meyers process for
chemical desulfurizatlon of coal: Initial
survey of fifteen coals -- 4/74 (200 pp)
Same: survey of thirty-five coals -- 9/75
(212 pp)
Energy consumption: the chemical industry
(task 5) -- 4/75 (71 pp)
Evaluation of pollution control in
fossil fuel conversion processes -- coal
treatment; section 1: Meyers process --
9/75 (46 pp)
Meyers process development for chemical
desulfurization of coal, Vol. I -- 5/76
(309 pp)
Same, Vol. II -- appendices -- 5/76 (124
PP)
Pilot plant design for chemical desul-
furization of coal -- 4/77 (162 pp)
The physical desulfurization of coal --
major considerations for S09 emission
control - 11/70 (340 pp) *
A survey of fuel and energy information
sources, Vol. I -- 11/70 (307 pp)
Same. Vol. II - 11/70 (632 pp)
Electric power supply and demand forecasts
for the United States through 2050 -
2/72 (54 pp)
Survey of coal availabilities by sulfur
content -- 5/72 (168 pp)
Evaluation of sulfur dioxide emission
options for Iowa power boilers (task 3) --
12/74 (331 pp)
-------
Contractor
(Contract No.)
EPA/IERL-RTP REPORTS (cont.)
Report Title -- Date Publ1shed(No. of Pages)
NTIS No.
(EPA No.)
Applicability Studies (cont)
Battelle
(68-02-2112)
Battelle
(68-02-2163)
PB 256-020/AS
EPA-600/2-76/177a
PB 260-475/AS
EPA-600/2-76-177b
PB 277-408/AS
EPA-600/7-78-034
Fuel contaminants: Vol. 1, Chemistry —
7/76 (177 pp)
Same; Vol. 2, removal technology evalu-
ation -- 9/76 (318 pp)
Physical coal cleaning for utility boiler
SO, emission control (task 851) -- 2/78
(1T2 pp)
645
-------
ENVIRONMENTAL ASSESSMENT METHODOLOGIES
FOR FOSSIL ENERGY PROCESSES: AN UPDATE
Robert P. Hangebrauck
Energy Assessment and Control Division
Industrial Environmental Research Laboratory
Office of Energy, Minerals and Industry
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
ABSTRACT
Industrial Environmental Research Laboratory, Research Triangle Park,
(IERL/RTP) is conducting a number of programs involving environmental assess-
ment and control technology for both energy and industrial processes. This
presentation focuses on some aspects of the environmental assessment (EA)
methodology being developed and used as it relates to the Federal Interagency
Environmental R&D program.
A satisfactory environmental assessment methodology needs to address all
program aspects such as air, water, solid waste, toxic substances, radiation,
and noise. Essentially all pollutants and environmental factors should be
addressed including chemical substances; heat; noise; microorganisms; radiation;
and air-, water-, and land-related physical factors. Energy technologies
selected for Investigation should be those with high commercial usage/applica-
tion potential. The methodology must be practical and therefore has to be
based on utilization of available or readily obtainable information. Since
absolute answers are not usually achievable, emphasis must be placed on compar-
ative evaluations; e.g., definition of the relative best ways of controlling
and relative comparison of waste streams and sources.
The methodology is evolving out of necessity and should employ cost-
effective approaches to effect broad-coverage screening initially followed by
detailed screening to focus on areas of concern. The approaches must be
subject to continued refinement and improvement based on data and experience
gained in doing EA studies. Long lead times must be dealt with in development
and implementation of the methodology.
Several aspects of the developing environmental assessment methodology
are discussed Including the areas of current process technology background,
environmental data acquisition, current environmental background, environ-
mental objectives development, control technology assessment, and environ-
mental alternatives analysis. Some of the barriers to Implementation are
noted also.
646
-------
ACKNOWLEDGEMENTS
The author acknowledges the direct Input and/or availability of Informa-
tion developed by IERL/RTP personnel and their contractors, and personnel of
other laboratories In EPA1s Office of Research and Development.
647
-------
ENVIRONMENTAL ASSESSMENT AND CONTROL TECHNOLOGY
DEVELOPMENT PROGRAM
ENVIRONMENTAL ASSESSMENT
CONTROL TECHNOLOGY DEVELOPMENT
00
TECHNOLOGY AREAS
CONVENTIONAL COMBUSTION
NITROGEN OXIDE/COMBUSTION
MODIFICATIONS
FLUID BED COMBUSTION
ADVANCED OIL PROCESSING
COAL CLEANING
SYNTHETIC FUELS
-------
CURRENT
PROCESS
TECHNOLOGY
BACKGROUND
ENVIRONMENTAL
DATA
ACQUISITION
CONTROL
TECHNOLOGY
DEVELOPMENT
IS
BETTER
CONTROL
NEEDED?
CONTROL
TECHNOLOGY
ASSESSMENT
REGULATORY
REQUIREMENTS
CURRENT
ENVIRON-
MENTAL
BACKGROUND
ENVIRONMENTAL
OBJECTIVES
DEVELOPMENT
ENVIRONMENTAL
ALTERNATIVES
ANALYSES
TECH TRANSFER
cravinuNMtraiAL crauiraccrtiNu i
FNVIRnMMFNTAI SRIFNTFft
I
TECH TRANSFER
ENVIRONMENTAL
SCIENCES
R&D
1
MEDIA
AND
HEALTH/
ECO
IMPACTS
ANALYSES
ENVIRONMENTAL ASSESSMENT/CONTROL TECHNOLOGY DEVELOPMENT DIAGRAM
-------
IERL/RTP STANDARDS DEVELOPMENT SUPPORT R&D
IEHIENVIRONMENTAL
ASSESSKEOTyCONTROL
TECHNOLOGY
DEVELOPMENT
Oi
o
IERL DEVELOPS
STANDARDS
SUPPORT PLAN (SSP)
FOR EACH
TECIMOL06YAREA
i
EPA PROGRAM OFFICE
PRIORITIZATION STUDIES FOR
STANDARDS SETTIHG
IERL DEVELOPS:
• EWVIROKMEMTAL ASSESSMENT REPORT
• CONTROL GUIDANCE DOCUMENT
DEVELOPED FOR EACH UNIQUELY
DIFFERENT BASIC ENERGY
TECHNOLOGY (AT THE COMMERCIAL
OR DEMONSTRATION STAGE)
EPA PROGRAM OFFICES
DEVELOP PLAN FOR DETAILED
STANDARDS DEVELOPMENT FOR
SPECIFIC ENERGY
TECHNOLOGIES/SOURCES
AND ORGANIZE SPECIFIC
MEDIA WORKING GROUP
EPA PROGRAM OFFICES
CONDUCT ENGINEERING
STUDY TO DEVELOP
•ACK6ROUND DOCUMENT
EPA PROGRAM OFFICES
CONDUCT DETAILED INTERNAL
AND EXTERNAL REVIEWS,
PROPOSE IN FEDERAL
REGISTER, CONDUCT
FURTHER REVIEWS. AND
PROMULGATE STANDARD
-------
BREADTH OF OBJECTIVES
•COMPREHENSIVE CONTROL GUIDANCE IS NEEDED ON REAL-TIME
BASIS IN DEVELOPING, EVALUATING, AND DESIGNING CONTROL
TECHNOLOGY.
• ALL MEDIA/PROGRAM OFFICES NEED TO BE ADDRESSED (AIR,
WATER, SOLID WASTE, TOXIC SUBSTANCES, RADIATION,
NOISE).
t
ALL IMPORTANT POLLUTANTS AND ENVIRONMENTAL FACTORS SHOULD
BE ADDRESSED (CHEMICAL SUBSTANCES; HEAT; NOISE; MICRO-
ORGANISMS; RADIATION; AND AIR-, WATER-, AND LAND-RELATED
PHYSICAL FACTORS).
TECHNOLOGIES INVESTIGATED SHOULD HAVE HIGH COMMERCIAL
USAGE/APPLICATION POTENTIAL-
SUMMARY OF NEEDS FOR ADDITIONAL DATA TO SUPPORT
STANDARDS DEVELOPMENT, ENFORCEMENT, HEALTH AND ECOLOGICAL
EFFECTS RESEARCH, AND CONTROL TECHNOLOGY R&D.
651
-------
EFFECT8 OF SCALE ON EA APPROACH AND OUTPUTS
Scale of Technol-
ogy Facility
Practical Environ-
mental Measurements
Practical Uss of Information from
Environmental Measurements
Bench-Scale
Facility
Effluent/Product
Analyse*
• Identify Potential Pollutants
for EA Measurements
Scatsabls Pilot or
Demo Plant with
Nonscsleable
Control Tech-
nology
Effluent/Product
Analyses
Control Assays
• Good identification of
Pollutants
• Projected Hazard of Untrested
Streams Including Relation-
ship to Fugitive Emissions
and Spills
• Estimates of Ambient
Loedings Using Estimstes of
Add-On Control Effectiveness
• Basic Data for Deaign
of Controls
Full-Scale Facility
with Applicable
Controls
Effluent/Product
Analyaes
Ambfent Measurements
and Field Surveys
• Accurate Control Technol-
ogy Evaluations
• Good Projections of Ambient
Loedings and Effects
• Actuel Ambient Loedings and
Effeeta
652
-------
ENVIRONMENTAL DATA ACQUISITION
Level 1 Sampling and Analysis
EFFLUENT SAMPLES:
GASES
LIQUIDS
SOLIDS
EVALUATED FOR DISCHARGE TO MEDIA:
AIR
WATER
LAND
ANALYSES:
PHYSICAL
CHEMICAL
BIOLOGICAL
KEY ENVIRONMENTAL PARAMETERS:
HEALTH
ECOLOGICAL
- FRESHWATER
- MARINE
-TERRESTRIAL
653
-------
STATUS OF PHASED APPROACH TO
CHEMICAL AND BIOLOGICAL ANALYSES
LEVEL 1
- PROCEDURES AVAILABLE
- ADDITIONS AND REVISIONS UNDER STUDY
- EVALUATION OF LEVEL 1 CHEMICAL AND BIOLOGICAL
PILOT STUDIES NEAR COMPLETION FOR FLUID BED
COMBUSTION, GAS1FIER, AND TEXTILE PLANTS;
RESULTS LOOK GOOD-
• LEVEL 2
- GENERALIZED INTERIM PROCEDURES AVAILABLE FOR
ORGANICS
- GENERALIZED PROCEDURES FOR INORGANICS WILL BE
AVAILABLE SOON
- BASIC OUTLINE FOR LEVEL 2 BIOASSAY PROTOCOL
WILL BE AVAILABLE LATER THIS YEAR
LEVEL 3
- GUIDELINES ARE NOT YET DEVELOPED"* ILL BE SITE
(PROCESS) SPECIFIC
654
-------
ENVIRONMENTAL ASSESSMENT METHODOLOGY
- A PHASED APPROACH -
PHASE I
RAPID SCREENING
POTENTIAL PROBLEM
PHASE II (CONFIRMATION)
DIRECTED DETAILED
SCREENING AND
COMPLIANCE TESTS
1
CONFIRMED PROBLEM
PHASE III
SELECTED
POLLUTANT/EFFLUENT
MONITORING AND
EVALUATION
WASTE STREAMS.
RESIDUALS, AND
POLLUTANTS
WHICH ARE
NOT PROBLEMS
QUANTIFIED PROBLEMS
WASTE STREAMS,
RESIDUALS, AND
POLLUTANTS WHICH
ARE PROBLEMS
655
-------
PARALLEL ANALYSIS APPROACH
CHEMICAL
ANALYSIS
DOES OR
COULD THE
SAMPLE CONTAIN
A CONCENTRATION
OF A SUBSTANCE
EXCEEDING A MEG
VALUE?
Ui
SAMPLE
SAMPLE
FRACTION
BIOLOGICAL
ANALYSIS
DOES
THE SAMPLE
GIVE A
POSITIVE
BIOLOGICAL RESPONSE
AND TO WHAT
DEGREE?
-------
REGULATORY APPROACHES AND POTENTIAL REQUIREMENTS
AIR (CAA)
NSPS
Guidelines/Documents
PSD (BACT)
Nonattalnment (LAER)
NESHAP
A1r Quality Criteria (Inputs on sources and control technology documents)
WATER (FWPCA, SOWA)
* Effluent Guidelines
- BPT (1977)
- BAT (toxic pollutants - 1984)
- BCCT (conventional pollutants - 1984)
- BAT (all other pollutants • 1987)
• NSPS
' Toxic and Pretreatment Effluent Standards
• Permits
- Ocean Discharge
• SDUA (underground Injection groundwater protection)
- National Pollution Discharge Elimination System
• Area-Wide Waste Treatment Management (State/208 agencies)
• Hazardous Materials (spills, etc.)
• Hater Quality Standards and Criteria
SOLID WASTES (RCRA)
' Criteria, Identification Methods, and Listing of Hazardous Wastes
• Standards Application to Owners and Operators of Hazardous Waste
Treatment, Storage and Disposal Facilities
- Media Protection Strategies (groundwater, surface water, air)
• Guidelines
TOXIC SUBSTANCES (TOSCA)
* Implementation/Development
- Listing
- PMorltlzatlon
* Reporting Requirements
* Premature Notification
• Testing
• Control
RADIATION
• Guidance for Control (CAA, FWPCA. RCRA, TOSCA)
NOISE
* Data Base, 1f Regulated 1n Future
* Guidance
LAND USE
• Data Base, if Regulated In Future
657
-------
CURRENT ENVIRONMENTAL
BACKGROUND
• Summary of Key Federal Regulations
• Noncriteria Ambient Baseline Data
• Environmental Siting Scale
Models for Technologies
-------
ENVIRONMENTAL OBJECTIVES DEVELOPMENT
MULTIMEDIA ENVIRONMENTAL GOALS (NEGs)
PROVIDE ASSESSMENT ALTERNATIVES
• MINIMUM ACUTE TOXICITY EFFLUENT (MATE)
• EXISTING AMBIENT STANDARDS (ES)
• ESTIMATED PERMISSIBLE CONCENTRATIONS (EPC)
• NATURAL BACKGROUND/ELIMINATION OF DISCHARGE (NB)
' BEST TECHNOLOGY (BT)
659
-------
ENVIRONMENTAL OBJECTIVES DEVELOPMENT
. >'~ '
-••.•*••
CHEMICAL
-2. BASEDON
#*'. AMBIENT n
COMPLEX-EFFLUENT
BIOLOGICAL
RESPONSE
LEVELS
(BIOASSAY CRITERIA)
BASED ON
TECHNOLOGY*
MOST ACTIVE AREAS ARE SHADED.
•INCLUDES EXISTING STANDARDS
PHYSICAL"
FACTORS
(HEAT; NOISE; MICRO-
ORGANISMS; RADIO-
NUCLIDES; NONIONIZING
RADIATION; WATER- OR
LAND-RELATED PHYSI-
CAL FACTORS)
-------
EXAMPLE: SUMMARY OF AIR-HEALTH MATE VALUES
MEG* CATEGORY
MATE VALUES, »g/m3
100 103
10*
ID*
15. BENZENE; SUBSTITUTED
BENZENE HYDROCARBONS
A. Dwuene; Mumnuuuiuino
DtSUDStltUtM, rtHySUUSinuTBO
16. HALOGENATED AROMATICS
A. Ring Substitutad
B. llaMeiMteJ Afcyl Skfc Chain
17. AROMATIC NITRO COMPOUNDS
A. Simple
B. With AdditionM i muJWitti
Groups
1& PHENOLS
A mm a •— a^-^
A. ivionoiiyuiiu
B. Diiydrics; rwynvdrics
C. Fined Rinf Hydroxy Compounds
••••••••
1HMM
—
-------
APPLICATION OF MEG'S CATEGORIES:
FOR CHEMICAL COMPOUND IDENTIFIED BUT NOT INCLUDED IN
MEG'S LIST OR WITHOUT ESTABLISHED MEG VALUES:
1. DETERMINE CATEGORY-
2- DETERMINE SUBCATEGORY.
3- FROM MEG'S SUMMARIES, FIND LOWEST MEG
VALUE FOR COMPOUNDS IN THE SUBCATEGORY.
4- ASSUME THAT MEG VALUE WILL BE NO LOWER
THAN THE MOST STRINGENT VALUE INDICATED
FOR COMPOUNDS IN THE SUBCATEGORY.
5- SEND RTI A POSTCARD CONCERNING THE
COMPOUNDS SO THAT IT MAY BE INCLUDED IN
A CANDIDATE LIST FOR FUTURE MEG'S CON-
SIDERATION.
662
-------
EXAMPLE OF NUMBERING
SYSTEM FOR ORGANIC
COMPOUNDS
CATEGORY
18
18 A-
PHENOLS
MONOHYDRICS
18A020 PHENOL
18A040 CRESOLS
18A060 2-METHOXYPHENOL
18A080 ETHYLPHENOLS
18A100 PHENYLPHENOLS
18A120 2,2'-DIHYDROXYDIPHENYL
18A140 XYLENOLS
663
-------
MULTIMEDIA ENVIRONMENTAL GOALS
• VOLUM.ES 1 & 2 AVAILABLE NOVEMBER 1977 (EPA-600/7-77-136A, B)
- INITIAL METHODOLOGY ESTABLISHED
- MASTER LIST OF 650 POLLUTANTS PRESENTED
- 216 CHEMICALS ADDRESSED
* VOLUMES 1A, 3, 4 TO BE AVAILABLE EARLY 1979
- MINOR REVISIONS IN METHODOLOGY INTRODUCED
- MEGs POLLUTANT IDENTIFICATION NUMBERS ASSIGNED
- > 500 ORGANIC COMPOUNDS ADDRESSED
• EXPANDED INORGANICS MEGs AVAILABLE IN 1979
- COMPUTER-GENERATED
664
-------
CONTROL TECHNOLOGY
ASSESSMENT
* GAS TREATMENT
• LIQUIDS TREATMENT
0 SOLIDS TREATMENT
• FINAL DISPOSAL
* PROCESS MODIFICATION
• COMBUSTION MODIFICATIONS
' FUEL CLEANING.
' FUGITIVE EMISSIONS CONTROL
' ACCIDENTAL RELEASE TECHNOLOGY
665
-------
CONTROL TECHNOLOGY ASSESSMENT
* CONTROL ASSAY DEVELOPMENT
- FOR USE WITH LEVEL 1
- PROCEDURES FOR WATER EFFLUENTS ARE DEFINED
AND WILL REQUIRE FURTHER DEVELOPMENT AND
EVALUATION THROUGH APPLICATION
- CONCEPT FOR GASEOUS EMISSIONS DEFINED
- NO WORK YET ON SOLID WASTE/LAND DISPOSAL
ASPECTS
f MULTIMEDIA ENVIRONMENTAL CONTROL ENGINEERING HANDBOOK
- FIRST DRAFT BEING REVIEWED INCLUDES EXTENSIVE
ORGANIZED CONTROL DEVICE LISTINGS
- INITIALLY WILL CONTAIN ONLY ABOUT 100 SPECIFIC
DEVICE DATA SHEETS
666
-------
CONTROL ASSAY DEVELOPMENT TEST SEQUENCE
FOR WASTEWATER
SOURCE A
1
SOURCE B
BYPRODUCT
REMOVAL
i
FOR
LEVEL 1
ASSAY
COMPOSITE SAMPLE
SOLIDS SEPARATION
CARBON ADSORPTION
BIO-OXIDATION
___ ^^^^ M
_-»-_^^^ ^
ION EXCHANGE
CARBON ADSORPTION
ION EXCHANGE
667
-------
ENVIRONMENTAL ASSESSMENT
DATA SYSTEMS
Fine Particle Emissions Information
System (FPEIS)
— Operational
».
Gaseous Emissions
Data System
Liquid Effluents
Data System
Solid Discharges
Data System
Under Development
668
-------
SCOPE OF SOURCE ANALYSIS MODELS
SAM/IA
(RAPID SCREENING)
NO TRANSPORT/
TRANSFORMATION
•MEG*: MATE ONLY
NO
EFFLUENT
STREAM
CONCENTRATION
SAM/I
(SCREENING)
CRUDE TRANSPORT/
TRANSFORMATION
ANALYSIS
MEGs: ADD OTHER
ASSESSMENT
ALTERNATIVES
SAM/11
(REGIONAL SITE EVALUATION)
AMBIENT POLLUTANT
CONCENTRATION
- SITE-SPECIFIC
TRANSPORT/
TRANSFORMATION
- CROSS-MEDIA IMPACTS
MEGs: ALL ALTERNATIVES
POPULATION EXPOSURE
OTHER SITE-SPECIFIC
FACTORS
I
f
SAM OUTPUT
LEVEL 2 OR 3 SAMPLING NEEDS
DEGREE OF HAZARD
TOXIC UNIT DISCHARGE RATE
IMPACT FACTORS
-------
SOURCE ANALYSIS MODEL
DEVELOPMENT STATUS
* SAM IA: RAPID SCREENING
- REPORT IN WORKBOOK FORMAT AVAILABLE (EPA-600/7-78-015)
- WORK STARTED TO INCORPORATE BIOASSAY
RESULTS (WILL BE CALLED SAM IB)
• SAM It INTERMEDIATE SCREENING
- DRAFT REPORT IN WORKBOOK FORMAT
BEING REVIEWED
• SAM Hi REGIONAL SITE EVALUATION
- NO WORK DONE ON THIS YET
- SOURCE ASSESSMENT MODEL AVAILABLE
670
-------
APPROACH FOR APPLICATION OF SAM'S TO PHASED CHEMICAL ANALYSIS
LeveM
Sampling &
Analyst
Level 1 Results
•*
SAMIA
, I
SAMI
1
• Recommended Level 2 Analyses
• Potential Problem Discharges
Level 2
Sampling A
Analysis
Level 2 Results
I
SAMIA
• Screened Pollutants
• Screened Problem Discharges
I
SAMI
I
Levels
Sampling
Analysis
J • Recommended Level 3 Analyses
• Confirmed Problem Discharges
Levels r
Results
SAM II
'Optional
• Quantified Problem
Pollutants
• Quantified Problem
-------
SAM I POLLUTANT DISCHARGE OVERVIEW
.Discharge
Waste Stream
-Gas, Liquid, SoRd)
Control
Device
O On
D ON
Residual
I
Liquid
Residual
I
Solid
Residual
a) S. water Surface water,
b) A: Air, W: Water, L: Land
e) H: Health, E: Ecological
I
I
Ground water
Deceiving
Medium
XAir
r
~Wrter
^^
"^tand-
. Final ,
L, Receiving J Receptor 1
I BodX Medium 1
i
I
I
1
I_
1^^
-r*
I
J — — """'
Mr * |
River S. water
Lake a water
Pcean & water |
DeepWeU
Sump
i t •! • a • ^ n 1 1 j
jrngaieu rieio^
1
•a water |
1
| fRiver a water I
tMbAAa*
, _._J_^J
Lake S. water I
^wwer-r Ipcean & water j
^
Land<
•MvNIWI
1 tS ••*«•• -J
1- '•"fllrlT^^
ft
S '
1 "H
WastepUe
Plowed Reid
Sump
fCavWy 1
iFUSite
G. water J
'Land 1
1
G. water, 1
'Land i
MEGj
A
W
W
W
W
W
W
W
w
1
Receptor
c)
H.E
H.E
H.E
E
f
H.
H,E
H,E
E
H
E
WIN
L ! E
-------
OUTPUT OBJECTIVES FOR
ENVIRONMENTAL ASSESSMENT
- DEFINED RESEARCH DATA BASE FOR STANDARDS
• QUANTIFIED CONTROL R&D NEEDS
• QUANTIFIED CONTROL ALTERNATIVES
' QUANTIFIED MEDIA DEGRADATION ALTERNATIVES
• QUANTIFIED NONPOLLUTANT EFFECTS AND SITING
CRITERIA ALTERNATIVES
673
-------
KEY E.A--RELATED REPORTS
* STANDARDS SUPPORT PLAN
' POLLUTION CONTROL GUIDANCE DOCUMENT
• SOURCE TEST AND EVALUATION REPORT
• ENVIRONMENTAL ASSESSMENT REPORT
674
-------
STANDARDS SUPPORT PLAN (SSP)
INTRODUCTION
DEFINITION OF TECHNOLOGIES
THE STANDARDS SUPPORT SCHEDULE
DISCUSSION OF THE STANDARDS SUPPORT SCHEDULE
- PROJECTED DEVELOPMENT OF TECHNOLOGIES
- REQUIREMENTS OF THE EPA ACTS
- EPA PLANS FOR REGULATORY ACTIVITIES
- EPA RESEARCH AND DEVELOPMENT ACTIVITIES
- PROGRAM OFFICE VIEWS OF R&D DATA NEEDS
675
-------
POLLUTION CONTROL GUIDANCE DOCUMENT (CGD)
• POLLUTANTS AND PROCESS SOURCES
• ENVIRONMENTAL EFFECTS OF KNOWN POLLUTANTS
• POLLUTION CONTROL TECHNOLOGY
' POLLUTANT DISCHARGE LIMITS
• FUTURE DEVELOPMENT OF EFFLUENT AND EMISSION
STANDARDS
• EFFLUENT AND EMISSION MONITORING
676
-------
ENVIRONMENTAL ASSESSMENT
SOURCE TEST AND EVALUATION REPORT (LEVEL 1)
PRESSURIZED FBC MINI PLANT (EXAMPLE)
• SUMMARY
• PLANT DESCRIPTION
- SAMPLING METHODOLOGY
f ANALYTICAL PROCEDURES
• TEST RESULTS
• CONCLUSIONS AND RECOMMENDATIONS
677
-------
ENVIRONMENTAL ASSESSMENT REPORT (EAR)
• PROCESS DESCRIPTION OF THE SYSTEMS MAKING UP THE
TECHNOLOGY
• CHARACTERIZATION OF INPUT MATERIALS, PRODUCTS, AND
WASTE STREAMS
• PERFORMANCE AND COST OF CONTROL ALTERNATIVES
* ANALYSIS OF REGULATORY REQUIREMENTS AND ENVIRONMENTAL
IMPACTS BY MEDIA WITH REGIONAL CONSIDERATIONS
• SUMMARY OF THE NEEDS FOR ADDITIONAL DATA TO SUPPORT
STANDARDS DEVELOPMENT, ENFORCEMENT, HEALTH AND
ECOLOGICAL EFFECTS RESEARCH, AND CONTROL TECHNOLOGY
R&D
678
-------
BARRIERS TO
EA METHODOLOGY IMPLEMENTATION
• COMPLEXITY OF POTENTIAL PROBLEMS
* DIFFICULTIES IN CROSSING DISCIPLINARY AND
ORGANIZATION LINES
* BRIDGING THE GAP BETWEEN THE SCIENCES AND
ENGINEERING
• DIFFICULTIES IN CHANGING FROM SET PATTERNS AND
TRADITIONAL APPROACHES
' RELUCTANCE TO USE AVAILABLE EFFECTS DATA
* LACK OF REALIZATION OF THE IMPORTANCE OF COMMON
BASES TO PROMOTE COMMUNICATION AND EVOLUTIONARY
IMPROVEMENT OF METHODOLOGIES
* AREAS NEEDING FURTHER RESEARCH
679
-------
EMPHASIS ON PRACTICAL GOALS
* ENVIRONMENTAL ASSESSMENT (EA) STUDIES NEED TO
DO SOMETHING MORE THAN EMPHASIZE TRADITIONAL
PROBLEMS THAT HAVE BEEN THE SUBJECT OF YEARS
OF INVESTIGATION.
• APPROACH MUST BE DESIGNED TO UTILIZE AVAILABLE
OR READILY OBTAINABLE INFORMATION; I.E.,
APPROACHES MUST BE PRACTICAL-
• ABSOLUTE ANSWERS NOT POSSIBLE; THEREFORE,
RELATIVE OR COMPARATIVE ANSWERS DEFINING THE
RELATIVE BEST WAYS OF CONTROLLING OR RELATIVE
COMPARISONS OF WASTE STREAMS AND SOURCES
ARE NECESSARY.
-------
STATE OF KNOWLEDGE/GAPS
• AN EA METHODOLOGY IS EVOLVING OUT OF NECESSITY.
f NEED TO EMPLOY COST-EFFECTIVE APPROACHES TO EFFECT
BROAD-COVERAGE SCREENING INITIALLY AND DETAILED
SCREENING SUBSEQUENTLY TO FOCUS ON AREAS OF CONCERN-
• APPROACHES MUST BE SUBJECT TO CONTINUED REFINEMENT
AND IMPROVEMENT BASED ON EXPERIENCE IN PERFORMING
EA STUDIES.
* LONG LEAD TIMES MUST BE DEALT WITH IN DEVELOPING AND
IMPLEMENTING METHODOLOGY.
• METHODOLOGY MUST TAKE INTO ACCOUNT PRESENT EA PROGRAM
OFFICE AREAS OF CONCERN; E.G., POLLUTANT LISTS, STANDARDS-
681
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ULTIMATE ANSWERS
• ACCEPT THAT THE ONE-POLLUTANT-AT-A-TIME APPROACH TAKES DECADES
OF TIME TO BUILD POSSIBLE PROOF OF CHRONIC EFFECTS FOR AN
EXTREMELY LIMITED SET OF POLLUTANTS AND THEREFORE HAS SEVERE
LIMITATIONS FOR CONTROL DEVELOPMENT GUIDANCE-
• PROVIDE REAL-TIME GUIDANCE AND FILL IN EFFECTS-DATA GAPS FOR
CONTROL TECHNOLOGY DEVELOPMENT, EVALUATION, AND DESIGN BY
EMPHASIZING USE OF SHORT-TERM EXPOSURE TOXICITY DATA IN
EVALUATING EFFLUENTS DIRECTLY-
POSSIBLE TOXICITY DATA SOURCES ARE:
- COMPLEX EFFLUENT BIOASSAYS,
- SIMILAR DATA AVAILABLE IN THE LITERATURE,
- EXPERIMENTS FOR SPECIFIC CHEMICAL SUBSTANCES
OR CLASSES OF SUBSTANCES.
• TAKE BEST ADVANTAGE OF EXISTING EA METHODOLOGY BY MAXIMIZING
COMMUNICATION OF PROCEDURES, REFINEMENT IN PROCEDURES, AND
RESULTS OF INDIVIDUAL STUDIES-
• MAXIMIZE SUPPORT FROM THE ENVIRONMENTAL SCIENCES LABS IN
DEVELOPING EA METHODOLOGY.
• INTEGRATE KEY EPA PROGRAM OFFICE ASPECTS AND METHODOLOGIES-
• DEVOTE RESOURCES TO DEVELOPMENT, STANDARDIZATION, AND
COORDINATION OF EA METHODOLOGY.
682
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REVIEW OF REGULATIONS AND STANDARDS
INFLUENCING COAL CLEANING
P. Van Voris1, R. A. Ewing , and J. W. Harrison
Battelle's Columbus Laboratories
Columbus, Ohio
o
Research Triangle Institute
Research Triangle Park, North Carolina
ABSTRACT
With the growing public concern over health and ecological effects of
man-generated wastes has come increased legislation which places strict regu-
lations and standards for the release of potentially hazardous materials.
Although some of this environmental legislation may not be directed specifically
toward the coal cleaning industry itself, the Federal acts nevertheless
encompass and embrace the industry completely. Thus, these regulations and
standards that have been adopted by the United States, as well as Canada,
France, Norway, and Sweden, have required the industry to invest a great deal
of time and money in the development and installation of pollution control
devices or technologies for the proper disposal of wastes.
In this review the following Federal acts, which constitute the primary
regulatory authority governing pollution from activities associated with coal
cleaning processes, are examined.
Air Pollution
Clean Air Act of 1970 (P.L. 91-604)
Energy Supply and Environmental
Coordination Act of 1974 (P.L. 93-319)
Clean Air Act Amendments of 1977 (P.L. 95-95)
Water Pollution
Federal Water Pollution Control
Act Amendments of 1972 (P.L. 92-500)
Clean Water Act of 1977 (P.L. 95-217)
Solid Waste
Solid Waste Disposal Act of 1965 (P.L. 89-272)
Resource Recovery Act of 1970 (P.L. 91-512)
Resource Conservation and
Recovery Act of 1976 (P.L. 94-580)
683
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All of the above acts are administered and enforced by the U.S. Environ-
mental Protection Agency and are embodied in Title 40 of the Code of Federal
Regulations.
The applicability of the provisions of these acts to the coal cleaning
Industry, as well as some specific state regulations, are examined. This,
along with a critique of Federal acts which at this time only have potential
applicability, constitute the body of this report.
INTRODUCTION
During the past half century, increased industrialization,
product demand, additional leisure time, and population growth
have given rise to an increased use of energy. Both the U.S. En-
vironmental Protection Agency and the Department of Energy have
developed a series of energy scenarios showing that energy needs
may grow from our current annual consumption of approximately 75
15
Quads (1 Quad « 1 x 10 Btu) of energy to a conservative esti-
mate of nearly 110 Quads by the year 2000. Coal is currently
supplying 24 percent of the total Quads and is predicted to sup-
ply 33 percent by the turn of the century. The overall projected
increase in United States energy usage is approximately 46 per-
cent, in relation to only a 21 percent expected increase in the
U.S. population size (U.S. Department of Commerce, 1977). Other,
more pessimistic projections (Ehrlich et al., 1973; Hardin, 1973;
and Garvey, 1972) have painted even more startling scenarios
showing energy consumption doubling in the next quarter century.
684
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With this increased demand for energy came man's understand-
ing that the earth is a finite structure that must support a
broad diversity of life for an infinite amount of time. This re-
alization, along with the recognition of the environmental blight
that man had previously caused, gave birth to environemtnal con-
cerns which, in turn, spawned governmental regulations and their
subsequent promulgation designed to help ensure the preservation
of the ecosystems and their inhabitants.
Because of the projected increase in our reliance on coal as
one of the primary energy sources for our country, as well as the
potential role of coal cleaning in reducing environmental risks
associated with coal, it was felt that a review of the major fed-
eral regulations affecting the coal preparation industry was
necessary. This review is divided into the key areas of regula-
tory control—air, water and solids—and each is examined both
at the federal and state levels.
REGULATIONS AFFECTING COAL CLEANING
In order to evaluate the existing and pending environmental
regulations that will affect coal cleaning, several reviews of
Federal and State regulations governing pollution resulting from
activities associated with coal cleaning, transportation, stor-
age, and handling have been prepared (Ewing et al., 1977; Cle-
land and Kingsbury, 1977; Energy and Environmental Analysis, Inc.,
1976; Harrison, 1978; and Ewing et al., 1978). The scope of
these reviews included the regulations influencing the combustion
685
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of coal as a fuel but excluded those for the conversion of coal
to coke or to liquid or gaseous fuels. The results of the most
recent review (Ewing et al., 1978) are the basis for this paper
and, unfortunately, will be outdated by the time this has been
published. Therefore, repeated updates of this report are planned
as a portion of the U.S. EPA Technological and Environmental
Assessment of Coal Cleaning Processes program.
The following Federal acts constitute the primary regulatory
authority governing pollution resulting from activities associ-
ated with coal cleaning processes.
Primary Regulatory Authority
Governing Pollution Resulting
From Coal Cleaning Processes
Air Pollution
Clean Air Act of 1970 (P.L. 91-604)
Energy Supply and Environmental (P.L. 93-319)
Coordination Act of 1974
Clean Air Act Amendments (P.L. 95-95)
of 1977
Water Pollution
Federal Water Pollution Control (P.L. 92-500)
Act Amendments of 1972
Clean Water Act of 1977 (p.L. 95-217)
Solid Waste
Solid Waste Disposal Act (P.L. 89-272)
of 1965
Resource Recovery Act of 1970 (P.L. 91-512)
Resource Conservation and (P.L. 94-580)
Recovery Act of 1976
U.S. Geological Survey - Title 30 CFR,
Department of Interior Part 211
Potentially applicable for Chemical Coal Cleaning - Toxic
Substances Control Act of 1976 (P.L. 94-469).
686
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These acts are embodied in Title 40 of the Code of Federal
Regulations and their applicability to coal cleaning is discussed
in the following sections.
State regulations are generally written or amended to incor-
porate, as a minimum, the provisions of the Federal laws.. In
some instances, state regulations are more stringent than Federal
regulations. The states are usually required to submit implemen-
tation plans for U.S. EPA approval outlining how Federal standards
will be met and specifying a reasonable time frame for implement-
ing those standards. This state certification procedure is es-
sentially complete for air pollution, well underway for water pol-
lution, and just beginning for solid wastes.
Air Pollution Regulations
Federal
The development and implementation of air pollution controls
have been approached in two different ways by the U.S. Environ-
mental Protection Agency in accordance with the provisions of the
Clean Air Act of 1970. Source emission standards are designed to
regulate the quantities of pollutants emitted from point sources,
whereas ambient air quality standards are designed to regulate
the concentrations of pollutants in the .atmosphere.
Ambient Air Quality Standards. The U.S. EPA, under Section
109 of the Clean Air Act of 1970, has established national pri-
mary and secondary ambient air quality standards (NAAQS) that
regulate pollutant levels in order to protect, respectively, human
687
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health and public welfare (property and plant and animal life)
(U.S. Environmental Protection Agency, 1977a).
Implementation is the responsibility of the individual
states, under a State Implementation Plan (SIP), which must be
approved by the U.S. EPA. Also, the permissible levels for cer-
tain named pollutants (criteria pollutants), which the SIP must
provide Will not be exceeded, are established by the U.S. EPA.
Some of these "criteria pollutants" arise mainly from motor ve-
hicles; however, pollutants such as total suspended particulates,
sulfur oxides, and nitrogen oxides, arise from stationary sources
and are released mainly through coal combustion. Current national
ambient air quality standards for the criteria pollutants are
summarized in Table 1 (U.S. Environmental Protection Agency,
1977a).
Table 1. National ambient air quality standards
PartlcuTates
Sulfur dioxide
Averaging Period
Annual geometric mean
Max. 24-hr concentration, not to
be exceeded more than once
per year
Annual arithmetic mean
Max. 24-hr concentration, not to
be exceeded more than once
per year
Max. 3-hr concentration, not to
be exceeded more than once
oar vaar
Primary
75 Mg/m
260 Mg/m3
80MQ/m3
(0.03 ppm)
365 pg/nr
(0.14 ppm)
«
Secondary
60 /^g/m3
150 Mg/m3
60 /ug/m3
(O.Oz ppm)
260 /ug/m3
(0.1 ppm)
1300 Mg/m3
(0.5 ppm)
688
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Table 1. (Continued)
Carbon monoxide
Hydrocarbons
Averaging Period
Wax. TT-1W5 IjoTfESfitFitTbn, not to
be exceeded more than once
per year
Max. 1-hr, concentration, not to
be exceeded more than once
per year
Max. 3-hr (6-9 A.M.) concentra-
tion, not to be exceeded more
than once a year
Primary
10 mg/m3
(9 ppm}
40 mg/3
(35 ppm)
160 Mg/m
(0.24 ppm)
Secondary
10 mg/m3
Oppm)
40 mg/m3
(35 ppm)
160 Mg/m
(0.24 ppm)
Photochemical oxldants. Annual arithmetic mean
Max. 4-hr concentration
Max. 1-hr concentration, not to 160 Mg/m3 160 Mg/m3
be exceeded more than once (0.08 ppm) (0.08 ppm)
per year
Mltrooen dioxide . Annual arithmetic means 100 Mg/m3 100 Mg/m3
(0.05 ppm) (0.05 ppm)
New Source Performance Standards. In accordance with Section
111 of the 1970 Clean Air Act, the U.S. EPA is required (1) to
compile a list of categories of emission sources that may con-
tribute significantly to air pollution and (2) to establish Fede-
ral standards of performance for new and modified stationary
sources in such categories. Unlike the ambient air quality stand-
ards, these standards of performance are not based on the effects
of pollutants on public health and welfare but on "the degree of
emission limitation achievable through the application of the best
system of emission reduction which (taking into account the cost
of achieving such reduction) the Administrator determines has been
689
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adequately demonstrated".* Agency terminology for this is BACT
(Best Available Control Technology).
Standards have now been promulgated for over 25 types of
sources. The foremost category on the list is fossil-fuel-fired
stationary sources; many provision of the Clean Air Act Amend-
ments of 1977 are aimed specifically at such sources, and the re-
strictions applied are much more rigorous than in the past. Where
the original New Source Performance Standard (NSPS) for large
[>250 million Btu/hr (73 MW)] coal-fired boilers permitted the
emission of 1.2 Ib SO2/million Btu, the amended Act specifies, in
addition, that the revised NSPS "...shall reflect the degree of
emission limitation and the percentage reduction achievable
through application of the best technological system of continu-
ous emission reduction ...", i.e., a percentage reduction will be
required rather than maintenance of emissions below an upper
limit. A comparison of the newly-released revised NSPS and ex-
isting NSPS is presented in Table 2. The criteria are tempered
by the usual energy, cost, and environematnal impact considera-
tions. Also, credit may be taken for any cleaning of the fuel or
reduction in the pollution characteristics of the fuel after ex-
traction (i.e., mining) and before combustion.
Since NSPS's for fossil-fuel-fired boilers apply only to
units above 250 million Btu/hr (73 MW), very few boilers employed
*However, it should be noted that the setting of NAAQS provides
the justification for setting emissions standards for these pol-
lutants.
690
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Table 2. Comparisons of existing NSPS
and revised NSPS
Existing NSPS Revised NSPS*
S02 1.2 Ib/million Btu 0.2 Ib/million Btu**
85% reduction
Participates 0.1 Ib/million Btu 0.03 Ib/million Btu
99% reduction from
uncontrolled sources
N0x 0.7 Ib/million Btu 0.6 Ib/million Btu
65% reduction from
uncontrolled sources
Currently no NSPS for Industrial Boilers
*U.S. Environmental Protection Agency, 1978a.
**Limits for no more than 1.2 lb/106 Btu with 0.2 lb/106 as
the floor.
in coal cleaning activities (thermal dryers) will be affected by
these new standards. On the other hand, many, if not most, of
the potential utility users of coal employ boilers of this size
or larger. Thus, depending somewhat on the S02 regulations final-
ly promulgated, the revisions to the NSPS for fossil-fuel-fired
boilers will have a significant, but direct, impact upon coal
cleaning. The role of coal cleaning in the utilization of coal
undoubtedly will be influenced materially, although 'the way in
which this will be manifested is as yet unclear. The percentage
reductions required are unlikely to be achieved by coal cleaning
alone, so some supplemental form of S02 removal will probably be
required.. On the other hand, the converse may also be true,
691
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especially on high sulfur coal, so coal cleaning may be technical-
ly desirable (and probably also economically and environmentally
advantageous) to supplement flue gas desulfurization.
New source performance standards that are directly applica-
ble to coal cleaning processes are those for new and modified
coal preparation plants and handling facilities which include:
thermal dryers, pneumatic coal cleaning equipment (air tables),
coal processing and conveying equipment (including breakers and
crushers), coal storage systems (except for open coal storage
piles), and coal transfer and loading systems (including barge
loading facilities). Although the regulations in 40 CPR Part 60
(U.S. Environmental Protection Agency, 1977b) do not specify
their application elsewhere, the explanatory discussion in the
promulgation announcement (41 FR 2232, January 15, 1976) also in-
cluded other sources that handle large amounts of coal, such as
power plants, coke ovens, etc.
These NSPS, which are applicable to all coal preparation or
handling facilities processing more than 200 tons/day, include
(U.S. Environmental Protection Agency, 1977b)i
• emissions from thermal dryers—may not exceed 0.070
gr/dscm (0.031 gr/dscf) and 20 percent opacity
• emissions from pneumatic coal cleaning equipment—
may not exceed 0.040 gr/dscm (0.018 gr/dscf) and 10
percent opacity
• emissions from any coal processing and conveying
equipment, coal storage system, or coal trarisfer
692
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and loading system processing coal (nonbituminous as
well as bituminous) — may not exceed 20 percent opacity.
Hazardous Pollutant Emission Standards. The atmospheric
emission of several hazardous pollutants is already regulated un-
der Section 112 of the Clean Air Act of 1970. Two of these (be-
ryllium and mercury) are found in coal but not at levels such
that their emission is expected to violate standards. The estab-
lishment of regulations governing arsenic, polycyclic organic
matter (POM), and cadmium emissions is now under consideration. A
national ambient air quality standard for lead has just been pro-
posed (U.S. Environmental Protection Agency, 1977c). Except for
POM's, emissions of the other hazardous pollutants mentioned
above (in concentrations likely to be governed by the standards)
are expected to be emitted only from sources such as those found
in the nonferrous metal industry or from the combustion of leaded
gasoline and the standards should have little effect upon coal
cleaning processes.
Prevention of Significant Deterioration of Air Quality. A
new Part C (Sections 160-169) was incorporated into the Clean Air
Act Amendments of 1977 for the prevention of significant deteri-
orations (PSD) of the present ambient air quality. Three land-
use classes are established which are interpreted by the U.S. EPA
to have the following types of development:
• Class I - little or no development
• Class II - scattered development
• Class III - concentrated or large-scale development.
693
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Classification in Class I is mandatory for national parks exceed-
ing 6,000 acres in size and wilderness areas. The verbiage is
complex and involved, but the significant fact, with respect to
coal cleaning processes, is that any new source in an area sub-
ject to the provisions of this section is to employ the Best
Available Control Technology for each pollutant subject to regu-
lation. Cost considerations for achieving such emission reduc-
tion is not invoked as a factor. Thus, the best available con-
trol technology required for PSD must be better than those of the
NSPS. It is obvious that these are site-specific problems and
that a uniform national standard will not be utilized. Each pro-
posed new source will be considered by the"affected state on a
case-by-case basis under the state implementation plan. The Act
provides for maximum allowable increases in S02 and particulates
for each land-use class, with the provision that the NAAQS will
not be exceeded. Allowable pollutant increases are shown for all
three land-use classes in Table 3, along with national primary
and secondary ambient air quality standards.
Table 3. Allowable pollutant increases above
baseline concentrations
Particulate Matter
Annual geometric mean
24-hr maximum
Concentration, yg/m3
Land
Class Area
I II III
5 19 37
10 37 75
NAAQS
Primary Secondary
75 60
260 150
694
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Table 3. (Continued)
Concentration.
Land
Class Area NAAQS
I II III Primary Secondary
Sulfur Dioxide
Annual arithmetic mean 2 20 40 80 60
24-hr maximum 5 91 182 365 260
3-hr maximum 25 512 700 — 1300
Visibility Protection for Federal Class I Areas. Section
169 of Part C specifically addresses the national goal set by the
Congress for the prevention of any future (and the remedying of
any existing) impairment of visibility in mandatory Federal Class
I areas from man-made air pollution. Within 24 months, the Ad-
ministrator will promulgate regulations to assure reasonable pro-
gress toward meeting the national goal. The requirements include
existing sources and may require use of the best available retro-
fit technology.
Nonattainment Areas. A new Part D (Sections 171-178) was
also incorporated into the Clean Air Act Amendments of 1977 to
address alleviation of air pollution problems in areas where one
or more air pollutants exceed any national ambient air standard.
Theoretically, no new emission source could be constructed in a
nonattainment area. Since this was judged to be an impractical
answer, the compromise solution was to require the "lowest
achievable emission rate" (LAER). This is an even more restric-
tive standard than the BACT specified for prevention of
695
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significant deterioration and includes either the most stringent
emission limitation for such source category in any state imple-
mentation plan or the most stringent emission limitation actually
achieved in practice, whichever is more stringent, and in no
event will it be less restrictive than the NSPS is for that source
category. Like the PSD, this is to be implemented by the indi-
vidual states through the state implementation plans on a case-
by-case basis. A key provision is that the states are to con-
tinue "reasonable further progress" in order to achieve annual
incremental reductions of the applicable air pollutant, including
such reduction in emissions from existing sources as may be ob-
tained through the adoption, at a minimum, of "reasonably avail-
able control technology" (RACT).
The above is part of the so-called "offset" approach wherein
reductions are made in existing emissions to permit addition of a
new source, with the additional constraint that an overall de-
crease should be shown.
In general, designation as a nonattainment area means that
an applicable SIP must be revised to provide for the attainment
of the NAAQS as expeditiously as possible. The -revised SIP must
require permits for the construction and operation of major new
and modified stationary sources and must prohibit potential new
source construction where emissions would contribute to an in-
crease in pollutants for which a NAAQS was already being exceeded.
696
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The U.S. EPA has just published a list of the NAAQS attain-
ment status of all areas within each state (U.S. Environmental
Protection Agency, 1978b).
State
Although the U.S. EPA promulgates national ambient air qual-f
ity standards, states have the privilege of establishing more
stringent standards. Thirty-three states and the District of Co-
lumbia have ambient air quality standards (AAQS) that are more
stringent than those of the Federal Government.
Since the concentrations of nitrogen oxides and other pol-
lutants other than sulfur oxides and particulates, for which .
there are AAQS, are only marginally related to the quality of
coal prepared or burned, emphasis has been placed on the standards
for sulfur dioxide and particulate matter (total suspended par-
ticulates) . Those states with more stringent AAQS are Alaska,
Arizona, California, Connecticut, Colorado, Delaware, Florida,,
Georgia, Hawaii, Indiana, Kentucky, Louisiana, Maine, Maryland/
Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire,
New Mexico, New York, North Carolina, North Dakota, Ohio, Oregon,
South Dakota, Tennessee, Vermont, Washington, West Virginia, Wis-
consin, and Wyoming (Figure 1).
Water Pollution Regulations
i i
Federal
. There are no national ambient water quality regulations
analgous to those for air; water pollution is regulated
697
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Figure 1. Map showing states with more stringent AAQS than NAAQS,
-------
nationally on the basis of emissions (termed effluents in the
case of water).
Effluent Guideline Limitations. The enabling Act providing
the authority to establish effluent limitations was the Federal
Water Pollution Control Act (FWPCA) amendments of 1972 (P.L. 92-
500). Basic effluent limitations have now been promulgated for
numerous industries; others have been challenged by the affected
industries and are still in abeyance pending further development.
The FWPCA was further amended in 1977 (P.L. 95-217). Effluent
guidelines are presently based on the best practicable control
technology currently available (BPCTCA), which was to have been
achieved by July 1, 1977. By July 1, 1983, effluent guideline
limitations were to have required the application of the best
available technology economically achievable (BATEA). The 1977
amendments have extended this date a year to July 1, 1984.
Effluent guidelines are also being promulgated for new
sources. These new source performance standards for wastewater
effluents are intended to be the most stringent standards applied.
Federal control of water pollution sources associated with
coal preparation and handling is achieved through the issuance to
each discharger of NPDES (National Pollutant Discharge Elimina-
tion System) permits which contain limits on specific pollutants
in the effluents. Effluents from coal cleaning are regulated as
a part of the coal mining point source category (40 CFR, Part
434). This category includes "associated areas" such as the
plant yards, immediate access roads, slurry ponds, drainage
699
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ponds, coal refuse piles, and coal storage piles and facilities.
Regulations have been divided into two groups—one for acidic
and one for alkaline wastes. Regulations for existing plants
(U.S. Environmental Protection Agency, 1977d) and proposed new
source performance standards (U.S. Environmental Protection' Agen-
cy, 1977e) are summarized in Table 4. Final regulations for
BATEA effluent limitations have not yet been promulgated.
Table 4. Effluent limitations for coal preparation plants
Effluent
Characteristic
Acidic Wastes
(a,b)
Alkaline Wastes
(a)
Daily
Maximum
30-Day
Average
Daily
Maximum
30-Day
Average
TSS, ing/1
Iron, toal, mg/1
Manganese, total, mg/1
PH
TSS, mg/1
Iron, total, mg/1
Manganese, total, mg/1
PH
Existing Sources
70.0 35.0
7.0 3.5
4.0 2.0
6.0-9.0
70.0
7.0
35.0
3.5
6.0-9.0
(c)
Proposed New Source Performance Standards
70.0 35.0
3.5 3.0s
4.0 2.0
6.0-9.0
70.0
3.5
35.0
3.0
6.0-9.0
(a) Excess water effluent from a facility designed to contain or treat the
volume of water from the 10-year, 24-hour precipitation event is not
subject to limitations.
(b) pH may be slightly exceeded to achieve manganese limitation, up to
9.5.
(c) No discharge of pollutants permitted from facilities which do not re-
cycle wastewater for use in processing.
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Toxic Pollutants. The Clean Water Act of 1977 introduced a
new requirement for the control of toxic pollutants that are re-
quired to be limited by the application of the best available
technology economically achievable. The initial list of toxic
subatances and families of substances contained those identified
in the consent decree between the U.S. EPA and the National Re-
sources Defense Council (NRDC). This list, shown in Table 5 (U.S.
Environmental Protection Agency, 1978c), comprises principally
organic compounds thought to have no connection with coal clean-
ing. This li.st has now grown into the current 129 "priority pol-
lutants" of which 24 have been tentatively identified as existing
in wastewater from some coal cleaning plants (Randolph, 1978).
However, the listing in Table 5 of a few inorganic compounds
(arsenic, beryllium, lead, etc.) would seem, by definition, to
place them in the category of pollutants of concern to the coal
cleaning industry. No regulations or proposed regulations have
yet been published and the potential effects of such limitations
of the "priority pollutants" on coal cleaning operations would be
speculative at this time.
Water Quality Criteria. While ambient air quality standards
are set at the Federal level, water quality standards are pri-
marily a state responsibility. The only existing Federal water,
quality standards are those for drinking water, applicable to
public (community) water supplies. Maximum contaminant levels in
public water supplies have been set for contaminants associated
701
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Table 5. Pollutants being considered for
effluent limitations
1. Aoenaphthene
2. Aorolein
3. Aorylonitrile
4. Aldrin/Dieldrln
5. Antlnony and compounds
6. Arsenic and compounds
7. Asbestos
8. Benzene
9. Benzidene
10. Beryllium and compounds
11.' Cadmium and compounds
12. Carbon tetraohloride
13. Chlordane
14. Chlorinated benzenes
15. Chlorinated ethanes
16. Chloroaltcyl ethera
17. Chlorinated napthalene
18. Chlorinated phenols
19. Chloroform
20. 2-ohlorophenol
21. Chromium and compounds
22. Copper and compounds
23. Cyanides
24. DDt and metabolites
25. Dlohlorobenzenes
26. Dlohlorobenzidlne
27. Dlchloroethylenes
28. 2,4-dlohlorophenol
29. Diohloropropane and dichloropropene
30. 2,4-dimethylphenol
31. Dinitrotoluene
32. Diphenylhydrazine
33. Endoaulfan and metabolites
34. Endrin and metabolites
35. Ethylbenzene
36. Fluoranthene
37. Raloethers
38. Malomethanes
39. Heptachlor and metabolites
40. Hexachlorobutadiene
41. Hexachlorocyclohexane
42. Hexachlorocyclopentadlene
43. Isophorone
44. Lead and compounds
45. Mercury and compounds
46. Naphthalene
47. Niokel and compounds
48. Nitrobenzene
49. Kitrophenols
50. Nltrosamines
51. Pentaohlorophenol
52. Phenol
53. Phthalate esters
54. Polychlorinated biphenyla (PCB's)
55. Polynuclear aromatic hydrocarbons
56. Selenium and compounds
57. Silver and compounds
58. 2,3,7,8-Tetrachlorodibenzo-p-dioxin
59. Tetrachloroethylene
60. Thallium and compounds
61. Toluene
62. Toxaphene
63• Trichloroethylene
64. Vinyl chloride
65. Zinc and compounds
with coal and coal cleaning activities: arsenic, barium, cadmium,
chromium, fluoride, lead, mercury, nitrate, selenium, and silver.
Federal water quality criteria (guidelines) have recently
been revised and expanded and published by the U.S. EPA (U.S.
Environmental Protection Agency, 1976); while these criteria do
not have direct regulatory application, the states are expected
to adopt these when implementing state water quality regulations.
702
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Criteria are presented for water quality which will provide for
the protection and propagation of fish and other aquatic life and
for recreation in and on the water. Criteria are also presented
for domestic water supply quality to protect human health.
State
The situation on control of water pollution by the states is
analogous to that for air pollution. Emission standards (efflu-
ent guidelines) are established on a national level by the U.S.
EPA, but their implementation is regarded as a state responsi-
bility. The FWPCA (P.L. 92-500} provides for the reduction of
duplicate laws by delegating permit issuance authority to the
states. Delegation of authority takes place when a state demon-
strates that it has legal capability and resources to operate the
program as envisioned by that Federal law. The states of Colo-
rado, Indiana, Kansas, Maryland, Missouri, Montana, North Dakota,
Ohio, Virginia, Washington, and Wyoming are delegated NPDES-
issuing states. The effluent limitations vary among the dele-
gated and nondelegated states.
Water pollution control enforcement is based on effluent
standards rather than stream quality, and plant discharges must
be within certain limits prescribed for each industry. The ob-
jective of such control systems is to achieve or maintain ambient
water quality standards that are primarily a state responsibility.
If these are not achieved by compliance with effluent standards,
more stringent limits may be applied.
703
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Solid Waste Regulations
Federal
Prior to October 21, 1976, protection of the environment
from pollution originating from the land disposal of solid wastes
was provided by the Solid Waste Disposal Act of 1965 (P.L. 89-
272), as amended by the Resource Recovery Act of 1970 (P.L. 91-
512). Federal guidelines for the land disposal of solid wastes
are given in Title 40 CFR, Part 241 (U.S. Environmental Protec-
tion Agency, 1977f).
Pursuant to Section 211 of the amended Solid Waste Disposal
Act, the guidelines are mandatory for Federal agencies and are
recommended for state, interstate, regional, and local govern-
ment agencies for use in their solid waste disposal activities.
However, these are only guidelines and do not establish new stand-
ards but set forth requirements and recommended procedures to en-
sure that the design, construction, and operation of the land dis-
posal site is environmentally acceptable. The thrust of Part 241
is directed toward regulation of sanitary and municipal wastes;
mining wastes are esentially ignored.
The management of solid and hazardous wastes entered a new
era on October 21, 1976, upon passage of the comprehensive Re-
source Conservation and Recovery Act (RCRA) of 1976 (P.L. 94-
580). Although the actual implementation of this Act has not yet
occurred, it is already clear that management of such wastes will
be revolutionized by the specific regulations currently being
drafted by the U.S. EPA.
704
-------
The introductory section of the Act describes the Federal
role as one of providing financial and technical assistance and
leadership in the development, demonstration, and application of
new and improved methods of waste management. In practice, it
appears that guidelines and regulations will be developed by the
U.S. EPA for adoption and promulgation by the states, possibly in
a fashion similar to the SIP's used for air pollution control.
The individual states would enforce their adopted regulations.
Some of the general provisions of the Act are:
• The U.S. Environmental Protection Agency is to issue
guidelines within 1 year for defining sanitary land-
fills as the only acceptable land disposal alterna-
tive that can be implemented; open dumps are to be
prohibited.
• Within 1 year, the U.S. EPA will develop and publish
suggested guidelines for solid waste management.
• Within 18 months, the U.S. EPA will promulgate cri-
teria for identifying hazardous waste, standards for
generators, transporters, and for treatment, storage,
and disposal of hazardous wastes.
• Permit programs are to be managed by the states but
under minimum guidelines to be provided by the U.S.
EPA.
• Each regulation promulgated will be reviewed and,
where necessary, revised not less than every 3 years.
705
-------
The development of specific solid waste regulations is ap-
preciably behind schedule and discussion of possible requirements
for coal cleaning refuse is, accordingly, unavoidably specula-
tive. However, the indications are that coal cleaning refuse may
be classified as hazardous waste, a case which would then involve
the most restrictive provisions of the Act, including permit ap-
plication, monitoring, record-keeping, and reporting.
The Geological Survey of the U.S. Department of the Interior
has established regulations for the disposal of wastes from coal
preparation plants located on land associated with mining (U.S.
Department of the Interior, 1977). Preparation is defined as any
crushing, sizing, cleaning, drying, mixing, or other processing
of coal to prepare it for market. The operator is required to:
"dispose of all waste resulting from the mining and
preparation of coal in a manner designed to minimize,
control, or prevent air and water pollution and the
hazards of ignition and combustion".
Additionally, more specific requirements are given for waste pile
construction, covering and revegetation, and settling ponds.
State
A few states have solid waste disposal regulations directly
applicable to coal preparation or consumption. The various states
have general regulations covering solid waste management, solid
waste disposal, and solid waste disposal areas (landfills, sani-
tary landfills, etc.). Solid wastes are not to be disposed of in
such a manner as to or in those areas where they could endanger
706
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human health and plant or animal life or contribute to air pollu-
tion. Locations of these disposal areas are also to be such that
they pose the least possibility of surface or groundwater con-
tamination. The provisions of the Resource Conservation and Re-
covery Act of 1976 will allow definitive guidelines to be estab-
lished by each state for the storage and disposal of solid wastes,
including those generated from coal preparation and consumption.
707
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REFERENCES
Cleland, J. G., and G. L. Kingsbury. 1977. Summary of key fede-
ral regulations and criteria for multimedia environmental
control. Draft report to U.S. Environmental Protection
Agency, Research Triangle Institute, Research Triangle Park,
North Carolina. 132 pp. + appendix.
Ehrlich, p. R., A. H. Ehrlich, and J. P. Holdren. 1973. Human
ecology: problems and solutions. W. H. Freeman and Com-
pany, San Francisco, California. 304 pp.
Energy and Environmental Analysis, Inc. 1976. Laws and regula-
tions affecting coal with summaries of federal, state, and
local laws and regulations pertaining to air and water pol-
lution control, reclamation, diligence, and health and
safety. DOI/OMPRA/CL-76-01, report to U.S. Department of
the Interior, Office of Mineral Policy and Research Analy-
sis. 200+ pp.
Ewing, R. A., D. A. Tolle, S. Min, G. E. Raines, and V. L. Holo-
man. 1977. Development of environmental assessment cri-
teria. Draft report to U.S. Environmental Protection Agen-
cy. Battelle's Columbus Laboratories, Columbus, Ohio (April
8, 1977). 46 pp.
Ewing, R. A., G. Raines, P. Van Voris, and B. Cornaby. 1978.
Development of environmental assessment crite'ria. Final
draft report to the U.S. Environmental Protection Agency.
Battelle's Columbus Laboratories, Columbus, Ohio (October
1978).
Garvey, G. 1972. Energy, ecology, economy. W. W. Norton and
Company, Inc., New York. 235. pp.
Hardin, G. 1969. Population, evolution, and birth control, 2nd
edition. W. H. Freeman and Company, San Francisco, Cali-
fornia. 386 pp.
Harrison, J. W. 1978. Standard support plan for technologies
for coal cleaning. Draft report to Research Triangle Inst-
tute. 39 pp.
Randolph, K. B., L. B. Kay, and R. C. Smith, Jr. 1978. Charac-
terization of preparation plant wastewaters. Paper pre-
sented at symposium on Coal Cleaning To Achieve Energy En-
vironmental Goals (September 11-15, 1978), Hollywood,
Florida.
708
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U.S. Department of Commerce. 1977. Projections of the popula-
tion of the United States: 1977 to 2050. Series P-25, No.
704 (July 1977). Bureau of the Census.
U.S. Environmental Protection Agency. 1976. Quality criteria
for water. EPA 440/9-76-023. U.S. Environmental Protection
Agency, Washington, D.C. 501 pp.
U.S. Environmental Protection Agency. 1977a. Code of federal
regulations, 40 protection of environment. Revised as of
July 1, 1977, Office of the Federal Register, National Ar-
chives and Records Service, General Services Administration,
Washington, D.C., Part 50, National Primary and Secondary
Ambient Air Quality Standards, pp. 3-13.
U.S. Environmental Protection Agency. 1977b. Code of federal
regulations, 40 protection of environment. Revised as of
July 1, 1977, Office of the Federal Register, National Ar-
chives and Records Service, General Services Administra-
tion, Washington, D.C., Part 60, Subpart Y, Standards of
Performance for Coal Preparation Plants, pp. 57-58.
U.S. Environmental Protection Agency. 1977c. Lead: proposed
national ambient air quality standard. 42 FR 63076-63094
(December 14, 1977).
U.S. Environmental Protection Agency. 1977d. Code of federal
regulations, 40 protection of environment. Revised as of
July 1, 1977, Office of the Federal Register, National Ar-
chives and Records Service, General Services Administration,
Washington, D.C., Part 434, Coal Mining Point Source Cate-
gory, pp. 685-689.
U.S. Environmental Protection Agency. 1977e. Coal mining point
source category. 41 FR 21380 (April 26, 1977).
U.S. Environmental Protection Agency. 1977f. Code of federal
regulations, 40 protection of environment. Revised as of
July 1, 1977, Office of the Federal Register, National Ar-
chives and Records Service, General Services Administration,
Washington, D.C., Part 241, Guidelines for the Land Disposal
of Solid Wastes, pp. 529-538.
U.S. Environmental Protection Agency. 1978a. Part V. electric
utility steam generating units, proposed standards of per-
formance and announcement of public hearing on proposed
standards. FR 43(182):42154-42184.
U.S. Environmental Protection Agency. 1978b. National ambient
air quality standards, states attainment status. 43 FR
8962-9059 (March 3, 1978).
709
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U.S. Environmental Protection Agency. 1978c. Publication of
toxic pollutant list. 43 FR 4108 (January 31, 1978).
710
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DEVELOPMENT OF ENVIRONMENTAL ASSESSMENT
CRITERIA FOR COAL CLEANING PROCESSES
R. A. Swing1, P. Van Voris1, B. Cornaby1, and G. E. Raines2
^attelle's Columbus Laboratories
Columbus, Ohio
2Raines Consulting, Inc.
Columbus, Ohio
ABSTRACT
There are four interrelated activities associated with the environmental
impact assessment of coal cleaning facilities. The first step is documentation
of chemical characteristics of the waste stream, with the physical transport
and distribution characteristics of the pollutants of concern in air, water,
and land being the next step. This is then followed by estimations of the
biological transport of those pollutants within the ecosystem where the
pollutants may reach any number of receptor organisms, including man. The
fourth and final activity estimates health and ecological effects relative to
the dosages predicted by the above interactions.
• Overall Methodology
The pollutants most needing control need to be identified, either
because of the quantities emitted or their toxicities, or both.
Decision criteria are needed to determine the relative priorities
to be assigned to controlling specific pollutants.
The environmental assessments to be performed will require quanti-
tative emission and distribution data for specific coal cleaning
plant configurations, coal types, geographic locations, etc. In
developing and illustrating assessment criteria and methodologies,
this study utilizes approximations of emissions and dilutions such
as might be associated with a hypothetical coal cleaning plant.
• Physical Transport and Partition Functions
Estimates of environmental concentrations of pollutants in all
three media - air, water, and land - are needed. This estimation
initially involves physical transport and dispersion; the approaches
to modeling physical distribution are discussed.
• Biological Transport Within Ecological Systems
Ecological transport and distribution has not been adequately
investigated; there are large gaps in the data for many elements
and many species. Qualitatively, the pathways and mechanisms for
dispersion, accumulation, and magnification have been identified;
711
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the problems arise in attempts to quantify the rates of
movement based on these mechanisms. The approach to these
problems and several illustrative examples are described.
• Establishing Goals Based on Estimated Permissible Concentrations (EPC's)
One of the most critical information needs is dose-response data
on the health and ecological effects of individual pollutants and
their mixtures. Then, estimated permissible concentrations (EPC's)
can be derived. Also needed are improved methods for converting
toxicological data to the threshold effects levels represented by
EPC's, and biologically supported safety factors for incorporation
into the formulae. The complexities of deriving EPC's on the basis
of available toxicological data are discussed.
INTRODUCTION
As increasing reliance is placed upon coal as an energy
source, the need to minimize the environmental impacts resulting
from pollutant emissions will become more and more important.
Recognizing this need, the U.S. EPA has initiated a number of
programs to (1) assess the environmental impacts of fossil fuel
energy processes and (2) identify problem areas requiring further
research and development. Battelle-Columbus has been investiga-
ting the environmental assessment of coal cleaning processes
since the fall of 1976. The following describe some of the acti-
vities in the area of development of assessment methodology and
assessment criteria, including decision criteria to determine the
relative priorities to be assigned to controlling specific pollu-
tants so that attention can be focused on those most needing it.
A fundamental criterion for assessing the environmental
impacts of pollutants associated with coal cleaning is the
712
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relationship of the permissible environmental concentrations of
pollutants to those which can or do occur. Elucidating this rela-
tionship involves four interrelated activities illustrated by
Figure 1. The first step is documentation of chemical character-
istics of the waste streams with the physical transport and dis-
tribution characteristics of the pollutants of concern in air,
water, and on land being the next step. This is then followed by
estimations of the biological transport of those pollutants within
the ecosystem where the pollutants may reach any number of recep-
tor organisms, including man. The fourth activity estimates
health and ecological effects relative to the dosages predicted
by the above interactions. All four activities provide input for
a prioritization of pollutants.
WASTE STREAM CHARACTERIZATION
The pollutants which most need control, either because of the
quantities emitted or their toxicities, or both, need to be iden-
tified. The pollutants directly resulting from coal cleaning are
primarily inorganic compounds associated with the ash fraction;
water will be the major receptor of these pollutants. Operations
producing major emissions of air pollutants are infrequent in
coal cleaning. The largest air emissions will arise as particu-
lates from thermal dryers and as fugitive dust from coal storage
and refuse piles and from coal handling.
Data from the U.S. Bureau of Mines, the U.S. Geological Sur-
vey, and other sources were utilized to develop lists of potential
713
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WASTE STREAM CHARACTERIZATION
Update and refine existing lists of
pollutants
Estimate pollutant quants, and cones.
PHYSICAL TRANSPORT
Determine partition functions
Estimate environmental cones.—
air, water, land
BIOLOGICAL TRANSPORT
Determine pathways and mechanisms
Quantify
POLLUTANT PRIORITIZATION
Establish decision criteria
for prioritising pollutants,
sources, and problems
ESTABLISH GOALS
Convert toxicological data to
est. permissible cones. (EPC's)
Existing BCL Lilts
OSBM Data
USGS Data
Coal Cleaning
Technol. Asset*.
Plant configuration
Coal type
Fraetionation factors
Process conditions
Existing dispersion
models
Published literature
Existing transfer models
Toxicological data
Multimedia env. goals
(MEG'S)
Mini acute toxicity
•ffluents (MATE'S)
Figure 1. Environmental assessment scheme.
714
-------
pollutants of concern. Such lists tend to become inordinately
long, if large doses of judgment are not used. Thus, a selected
"Priority 1" list of 51 elements and 23 substances or groups of
substances was selected judgmentally from larger lists for inves-
tigation (Battelle, 1977). The need for further pruning and pri-
oritization of pollutants will be discussed later. The waste
streams need also to be characterized as to pollutant quantities
and concentrations to provide the data needed to estimate environ-
mental concentrations. Pollutant emissions are dependent on a
number of governing factors, including coal types, fractionation
factors, process conditions, and geographic location. Ultimately,
these data will come from specific measurements; but in the inter-
im, these have to be estimated.
The various lists of potential pollutants identify those
pollutants which may be of concern in coal cleaning, provided
that they are present and emitted above some yet undefined rate
of release and/or concentration. By virtue of its origin, coal
has been found to contain nearly every naturally-occurring element,
The concentrations of these elements in coal vary widely. Many of
these elements, e.g., arsenic, beryllium, cadmium, lead, and mer-
cury are recognized as toxic substances. The ranges of pollutant
concentrations characteristic of coals provide some information on
their presence, but none on their possible emissions. Input data
required to estimate emissions include, first, information on the
process steps embodied in the cleaning flowsheet. Many alterna-
tives and combinations of alternatives are possible in crushing,
715
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sizing, and washing coal, and in separating coal from refuse. The
actual combination of process elements will influence the degree
of pollutant emissions, but not the kind. Thus, for purposes of
developing assessment criteria and methodology, reasonable approx-
imations of a generic process flowsheet will suffice, and are
used in this discussion.
The second item needed for the estimation of emissions is
information on partitioning of the pollutants or "fractionation
factors", i.e., the distribution of substances in raw coal to
another fraction or phase as the coal passes each process step.
Generally, data are needed for each pollutant which give the frac-
tion of the pollutant in the raw coal which distributes to the
refuse, clean coal, bottom ash, fly ash, and the atmosphere.
Estimates of the distribution of elements between clean coal
and refuse can be developed using float-sink or "washability"
data, which have been determined experimentally for many coals.
Gluskoter et al. (1977) have intensively examined this aspect of
coal cleaning, concentrating on Illinois Basin coals, but also
including other eastern coals.
If it is desired to base the calculations on a specific coal,
for which washability data are available, fractionation factors
calculated for that coal can be used. A simple computer program
has been developed and tested which permits estimation of frac-
tionation factors for elements as a function of specific gravity
cutoff points and/or percentage yield.
716
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"Fractionation factors" are also available from Klein, et al.
(1975) and others for the partitioning of elements upon combus-
tion in a boiler. These can be used to estimate losses to the
atmosphere from the thermal drying of cleaned coal. For parti-
tioning of elements between coal and the atmosphere during trans-
porting, handling, and storage, "fractionation factors".would
correspond to emission factors, such as have been estimated by
the U.S. EPA (1973) and others, for example (Blackwood and
Wachter, 1977). Analogous "emission factors" have yet to be
developed for losses of pollutants leached out from coal storage
piles, ash ponds, etc.
Values of emission concentrations are required as input to
dispersion models to permit the calculation of ground level con-
centrations (GLC) for air pollutants and surface water concentra-
tions (SWC) for water pollutants. A simplified preliminary mater-
ial balance model has been developed covering the direct process
steps from raw coal to combusted ash, illustrated by Figure 2.
The incidental losses to air and water arising from transporta-
tion, handling, and storage are not included in this preliminary
model, but can readily be included when data become available.
The model, which is normalized to a combustion output of 10 Btu,
can provide estimates of absolute emissions and average concentra-
tions of any number of trace constituents in (1) refuse, (2) ther-
mal dryer atmospheric discharge, (3) stack discharge from combus-
tion, and (4) ash flow based on composite flows, given an analysis
for the starting raw coal.
717
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165 Ibs
Water
I
0.65 MSCF
Thermal Dryer
Stack Discharge
11.44 MSCF
Flue Gas
t
oo
93.27 Ibs
Raw Coal
Physical
Cleaning
73.93 Ibs
Cleaned
Coal
Combustion
t
10° Btu
Output
{ 120 kwhr
Electricity)
165 Ibs
Contaminated
Water
_184 Ibs
Wet Refuse
11.06 MSCF
Air
9.39 Ibs
Ash
1
18.7 Ibs
Dry Refuse
Figure 2. Flow quantities for coal cleaning/power plant complex
-------
The model has been derived, programmed, and run with example
cases, using a composite fuel analysis of 68 percent coal from the
Helvetia mine and 32 percent from the Helen mine, approximating
one possible coal feed, to the Homer City advanced coal cleaning
facility.
PHYSICAL TRANSPORT
Pollutants emitted in the course of coal cleaning, handling,
transportation, storage, and combustion can both accumulate and
disperse, in both a physical and biological sense, depending upon
the characteristics of the pollutant and the compartment. Bio-
logical transport and fate are discussed in the following section.
In this section, modeling of the preceding physical transport and
dispersion are discussed. The general need for modeling is to
make estimates of the concentrations of trace pollutants in envi-
ronmental media as a result of operation of a coal cleaning plant.
No regulations or design criteria are available yet for most of
these, although regulations will be proposed and promulgated by
EPA within the next year or two for a number of toxic pollutants
which may affect coal cleaning plants.
In succeeding paragraphs, modeling approaches are discussed
relative to surface water, groundwater, air, and porous media.
Generally, the air pollution model should account for deposition,
both wet and dry, providing one input to surface water and soils.
Surface water run-off will pick up material in the upper soil
layer. The coal pile will be leached from precipitation and also
generally carried into surface water. Leaching and leakage
719
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through sedimentation pond bottoms will generally contribute to
groundwater pollution, although the movement of some pollutants
through the subsoil and into the groundwater requires years be-
cause of adsorption of materials on soils. The refuse area,
usually some kind of a fill, will be leached by the downflow of
water from precipitation and surface flow, contributing to both
stream pollution and groundwater pollution. The rationale that
should be incorporated in the modeling approach is to build a
capability of evaluating individual coal cleaning complexes,
either existing or under design. This approach is recommended
because the many different characteristics, e.g., meteorology,
topography, stream geometry, soil, and groundwater characteristics
required to characterize a given complex, vary widely from one
plant to another, making generalizations risky at this time.
On the other hand, the objective of the present investigation
is to develop criteria and associated methodologies for their
application rather than to estimate site-specific environmental
impacts for a given complex, The solution would seem to be to
include the necessary provisions in the models for the multipli-
city of detailed parameters which will ultimately be required, but
to use nominal values, or ranges, or even possibly "worst-case"
estimates, for a hypothetical site in the developmental phase.
Validation is an important aspect of model development, and
should be planned for, utilizing one of the coal cleaning sites
chosen for field data acquisition. Field data will permit valida-
tion and calibration of the models and suggest their application
720
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for future sites. However, it is not possible within the time
frame of the present program to wait until field data are avail-
able to initiate model development. For that matter, it is not
desirable to wait because modeling will illustrate the required
data which need to be gathered and will give preliminary evalua-
tions, using data that are available in the literature from other
area.
Air Dispersion of Pollutants
The concentration of key pollutants in the thermal dryer
atmospheric discharge and in the flue gases from combustion of the
cleaned coal will provide input for calculations of atmospheric
dispersion to yield ground level concentrations. The basic pur-
pose of the dispersion calculation is to provide an estimate of
the dilution factor which, when divided into the stack emission
concentrations, will yield ground level concentrations.
Two basic models are required, depending on whether the pol-
lutant is associated with large or small particles, where 100 mi-
crons is a typical dividing point. Large particles tend to
deposit on surfaces close-in such that the air concentration is
depleted as distance from the stack increases. The concentration
of smaller particles is reduced only by dispersion.
Simplified dispersion models, as typified by that presented
by Turner (1970), are availabe to consider stack heights and diam-
eter, stack gas temperature and exit velocity, and ambient air
temperature and wind speed. Calculations would be performed for
different weather categories. Multiple sources can be considered
721
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to include the effects of more than one stack if distance between
stacks is large enough to merit this refinement.
The large particle deposition model requires only the depo-
sition factor, wind speed, and effective stack height. Deposition
factors are available in the literature for various wind speeds
of interest.
A fugitive dust emission model, based on the EPA Multiple
Point Source Model (PTMTP), has been used by Battelle to help in
selecting sampling sites at the Homer City coal cleaning plant,
and to project mass atmospheric concentrations. It is a Gaussian
plume, multiple source model, with a generation function for fugi-
tive emissions dependent on wind speed squared. Deposition is
accounted for (but not plume depletion). The model has been cali-
brated based on field data acquired at Homer City (Ambrose et al.,
1977) .
Water Dispersion of Pollutants
Two types of effects may need consideration for discharges of
pollutants to water: dispersion and sedimentation of particulate
solids, and dispersion and dilution of soluble pollutants.
For the estimation of surface water concentrations, the con-
centrations of pollutants and the flows of waste water discharges
are required as input. Emission sources to be considered include
the waste water discharge from coal cleaning and runoff and per-
colation from coal and refuse storage piles, as well as from ash
ponds at coal cleaning plants and from coal storage piles at user
plants.
722
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Sedimentation in settling basins can be modeled by the use
of deposition coefficients. Since sedimentation requires only a
portion of the pollutant from a water column, a residual concen-
tration remains which is then further diluted by dispersion and
additional sedimentation in streams, etc. Simplified dispersion
models using point sources of pollutants can be used. These
models provide a correlation of dispersion coefficient with flow
velocity and stream configuration so that reasonable approxima-
tions for surface water concentrations associated either with a
specific facility or with a generalized case can be calculated
for average flows, low flows, and high flows. Sedimentation is
incorporated by the use of deposition factors relating sedimenta-
tion rate to concentration of the pollutant in the water body.
Output will consist of sedimentation rate and concentration in
water as a function of position (normally distance downstream)
for each case. Pseudo-steady state models are believed to be ade-
quate. With these models, when a change of conditions is encoun-
tered such as a change of release rates or an increase in flow of
the stream, concentrations make a step change from one steady
state to another. Sediment accumulates on the stream bottom line-
arly with time until such a change in conditions occurs. Fully
mixed (with stream across section and depth) models are more
appropriate for small narrow streams which are likely to be
around a coal cleaning plant. These solutions to the transport
equation have been known for years, and they are reasonably appli-
cable for continuously flowing freshwater streams.
723
-------
The need for a sedimentation model is not certain. The U.S.
Environmental Protection Agency has promulgated effluent guide-
lines for existing coal preparation plants and associated areas
(U.S. EPA, 1977a), and also has proposed new source performance
standards (U.S. EPA, 1977b), both of which establish upper limits
of total suspended solids (TSS) of 70 mg/1 (maximum for any one
day) and 35 mg/1 (average of daily values for 30 consecutive days).
For new sources these values apply to facilities which recycle
waste water for use in processing (nearly all new facilities should
fall into this category). A no discharge of process waste water
limitation is proposed for new facilities which do not recycle
waste water.
The definition of "coal preparation plant associated areas"
is broad, including plant yards, immediate access roads, slurry
ponds, drainage ponds, coal refuse piles, and coal storage piles
and facilities (U.S. EPA, 1977a). Thus, in order to be in compli-
ance, effluent from all areas of a coal preparation plant, includ-
ing coal and refuse piles, will have to be controlled so that the
total aqueous TSS discharge does not exceed an average of 35 mg/1.
At this concentration, sedimentation probably can be neglected.
Dispersion Through Porous Media
Although emission of pollutants to the atmosphere and to sur-
face waters is regulated by the U.S. EPA, heretofore the invisible
and difficult-to-measure escape of aqueous pollutants downward
through the soil has essentially avoided regulation. This situ-
ation is beginning to change, and this pollutant transport path
should be considered in regard to environmental criteria for coal
724
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cleaning plants. As mentioned in the introduction to this sec-
tion, this pollutant release pathway can come into play beneath
storage piles of raw and cleaned coal or refuse, as well as under
refuse ponds.
Simplified approaches to the adsorption and leaching of pol-
lutants in porous media are available. Simplified one-dimensional
models are described by Raines (1966) along with comparisons with
sophisticated results such as computerized finite difference
models with Langmuir adsorption-desorption. In many cases the
simplified models are quite adequate. It is recommended that ini-
tial emphasis can be directed toward correlation of data and esti-
mation with these models.
Groundwater modeling for accurate estimation of flows and
resulting trace contamination is sophisticated and complicated.
A sophisticated approach is not deemed within the scope of this
program at the present time. Socme experimental data are avail-
able for various trace elements and various soils.
ECOLOGICAL TRANSPORT
Coal cleaning facilities have a number of potential sources
of pollutants which include leachate and runoff from coal storage
and refuse disposal piles/ process wastewater or blowdown from
closed water circuits, and dust and gases emitted from coal piles,
refuse piles and thermal dryers. The more apparent environmental
effects from these potential contaminants might be seen in direct
contact toxicity resulting from changes in pH in the surrounding
725
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media, increasing levels of sulfate sulfur, sulfur dioxide,
nitrate nitrogen and nitrogen oxides, or resultant chemical
changes in abiotic components. These types of effects are usua-
ally short-term and easily identified. But, what happens to
those trace elements (e.g., arsenic, cadmium, and mercury) whose
release into both terrestrial and aquatic ecosystems is not quite
so apparent?
This portion of the environmental assessment criteria study
has focused on a short list of potentially hazardous trace con-
taminants that might be released as a result of coal cleaning.
These include elemental, inorganic, and organic forms of: ar-
senic, beryllium, cadmium, iron, lead, manganese, mercury, and
selenium. It is well known and documented that these contami-
nants are absorbed, retained, released, and cycled among the
biotic (i.e., producers, herbivores, omnivores, carnivores, and
decomposers) and the abiotic (i.e., soil, groundwater, surface
water, and sediment) compartments (see Jackson and Watson, 1977;
Jackson et al., 1978; Huckabee and Blaylock, 1974; Friberg et al.,
1974; D'ltri, 1972; and Van Hook et al., 1974). The structure and
complexity of transfer pathways and the matrix notation of the
typical ecosystems in question are depicted in Figure 2. For the
purpose of this paper, cadmium and mercury are used as examples of
the types of information that are available in Ewing et al., 1978.
s
The toxicity of these contaminants to living systems under
certain conditions has been established by other researchers
(Luckey et al., 1975). In addition, biotransformation of some
726
-------
[Fj (having components
Fjii and Fi*2) = air-
borne atmospheric forc-
ing function, and F2 =
aquatic input forcing
function.]
TERRESTRIAL
AQUATIC
Biological Transport
Physical
Transport
Biological
Transport
X'MAN
(a) Indirect ingaatkm resulting from faading habha.
(b) Irrigation, nominal in araa* of groundwatar irrigation.
(c) Surfaca watar intaka.
(d)Drinkingwatarintaka.
• Dominant tyststn transfar.
(The matrix is de-
fined so that the
column element is
the donor compart-
ment and the row
element is the re-
cipient. »
(Man is shown, but no data are reported.)
Figure 3. Compartmental model of generic ecosystem and dominant
pathways of pollutant transport and matrix configuration of im-
portant rate transfer coefficients within the generic ecosystem.
727
-------
contaminants (i.e., mercury)/ as shown in Figure 4, can drastically
change both the availability and toxicity of that pollutant. So,
the ultimate goal of transport and fate studies is to determine
whether or not toxic concentrations could be reached through nor-
mal environmental exposure pathways. That is, even if the source
release rates for a specific pollutant from a coal cleaning facility
were below the current Federal regulations, would the concentra-
tion of the contaminant ecologically magnify to a point at or be-
yond the toxic threshold values?
Mercuric ion,
cheloted cation! and onieni,
limple complex**,
oxide*, lulpnidei
Bacterial oxidation
Plankton
Plant*
Inorganic
reaction^
Inorganic reaction!
'Sunlight
Hg(ll)
ial reduction
Elemental mercury
a* vapour, liquid
or dinolute
Hg(0)
Bacteria
"Sunlit"
^Bacterial reduction
.Fungi
Bacterial oxidatior
Plant!
Inorganic reaction*
Bacterial lyntheiii
Chelotion
Bacteria,
convention by
organic pxidant!
Organo • mercury
compound*
R,R'salkyl,oryl,
mereopto,
protein, etc.
X » monovalent anion
eg. halide, acetate,
etc.
Bacterial lyntheiii
Chelotlon
Organic oxidanti
Diiproportionation and
electron exchange
Mercuroui Ion,
cheloted eationi and anioni,
limple complexes
Figure 4. Cycling of mercury interconversions in nature (with
permission from I. R. Jonasson and R. W. Boyle, 1971).
728
-------
When magnified by an organism, concentration of a contaminant
on a per gram basis is greater than that of its source or donor
compartments. The term describing this is ecomagnification which
is non-source specific and includes all potential exposure path-
ways (ingestion, inhalation, adsorption and immersion) within the
ecosystem. Ecomagnification is frequently misunderstood as a sim-
plistic biological phenomenon when, in fact, it is quite complex.
Ecomagnification is all inclusive, whereas the classic term bio-
magnification only considers food ingestion as the mode of expos-
ure. Thus, the ability of an organism to accumulate or magnify
contaminants depends on a number of ecological, chemical, physio-
logical, and physico-chemical factors, such as:
• chemical form of contaminant
• concentration of contaminant in soil or water
• interaction with other trace elements
• biotransformation of original elemental form
• soil characteristics and properties
• physiological makeup of target organism
• complexity of food sources.
In this study, the concentration factors (i.e., percent up-
take or retention) for the pollutants investigated have been ex-
tracted from the available literature for the major ecosystem com-
partments shown in Figure 3 (see page 16). Tables 1 and 2 present
typical data entries for cadmium in the terrestrial ecosystem and
mercury in the aquatic ecosystem. Data on cadmium and mercury were
selected because they are the most complete of all the pollutants
729
-------
Table 1. Cadmium uptake
Sample
Source Form
Percent Uptake/Retention
(concentration basis)
Reference
•vl
OJ
o
Soil
Vegetable Crop
Oak Trees
Rabbit
Cow
Grasshopper
Chipping Sparrow
Field Cricket
Dog
Wolfe Spider
Predatory Arthropod
Earthworm
Woodlouse
Arthropod litter
consumer
109CdCl2 in simulated rain
115CdCl2 in simulated rain
CdClj in simulated rain
Cd in soil
Cd in litter-soil
Cd iron dust
CdCl2 in feed
Cd in vegetation
Wild bird seed soaked in
103Cd solution
Vegetation grown in
I09Cd solution
in gaseous form
Crickets fed on 109Cd-
grown vegetation
Cd in prey
Cd in soil
Cd in litter-soil
Cd in litter
Abiotic Components
98.9 ± 1.2
85.5
88.4 ± 2.7
Terrestrial Producers
141.26 ± 24.0
34.9 ± 0.5
Terrestrial Herbivores
-30
8
-130
Terrestrial Omnivores
8
60.9
Terrestrial Carnivores
-40
71.4
124.0 ± 93.5
Terrestrial Decomposers
1.74 x 103 ± 0.42 x 103
1.03 x 103 ± 0.03 x 103
4.96 x 102 ± 1.90 x 102
36.8 ± 18.4
Van Hook et al., 1974
Huckabee and Blaylock, 1974
Van Voris et al., 1978
Ratsch, 1974
Jackson and Watson, 1977
Friberg, 1950
Miller et al., 1967
Munshower, 19 72
Anderson and Van Hook, 1973
Van Hook and Yates, 1975
Harrison et al., 1947
Van Hook and Yates, 1975
Watson et al., 1976
Van Hook et al., 1974
Gish and Christensen, 1973
Martin et al., 1976
Watson et al., 1976
-------
Table 2. Mercury uptake
Sample
Source Form
Percent Uptake/Retention
(concentration basis)
Reference
OJ
Rooted Plant
(Elodea densa)
Water milfoil
(Myfiophyllum speoattat
specatian L .)
Goldfish
(Carassius auratus)
Snail
Fish
(Cambusia affinis)
and
solution
organic and inorganic Hg
in solution
HgCl2 in solution
^Hg-tagged fly ash
^Hg-tagged fly ash
Hg° and HgCl2 in solution
Aquatic Producers
5.19 x 106 ± 3.35 x 106
2.21 x 10" ± 1.76 x 10"
Aquatic Omnivores
1.14 x 101* i 1.03 x 10*
0.13
Aquatic Carnivores
0.02
2.1 x 10"
Mortimer and Kudo, 1975
Dolar et al., 1971
McKone et al., 1971
Huckabee and Blaylock, 1974
Huckabee and Blaylock, 1974
Schindler et al., 1977
-------
investigated. However, similar though less complete, data
entries are available for each of the other six pollutants inves-
tigated for both terrestrial and aquatic ecosystem compartments
(Ewing et al., 1978).
The ultimate goal was to identify likely distribution fac-
tors and supply much needed input data for simulation models
describing the transport and fate of these pollutants. The com-
puter simulation of transport and fate would enable scientists to
compare the computer-predicted, long-term body burdens with
reported toxic concentrations for each of the pollutants. As is
evidenced in Tables 1 and 2 (pages 19 and 20) there are some indi-
cations that both cadmium and mercury have the propensity to eco-
magnify. However, the data are extremely variable and depend on
the above listed (see page 18) influencing factors. Unfortunately,
the need to use computer simulations and then compare the results
to reported toxic effects values is currently ahead of the data
base. The data required to accurately calculate the rate trans-
fer coefficients currently are not available in the literature.
Investigators, in general, fail to consider or report: (1) the
measurement of major parameters affecting transport and fate,
(2) partitioning data into specific exposure sources (i.e., food
source, inhalation, direct absorption), (3) chemical form of the
pollutant, and/or (4) time duration of the experiment. Therefore,
the use of computer modeling to accurately predict ecological
transport and fate of pollutants is currently beyond the state-of-
the-art.
732
-------
The resulting recommendations for future research fall into
three major categories. First, there is an immediate need to con-
duct research designed to determine the relative importance of
each exposure pathway for a series of populations within each
compartment. A series of closely controlled experiments could be
designed to estimate these values. This would enable concentrated
effort to be focused on the second major category which is the
determination of the rate transfer coefficients for chemical forms
for each dominant pathway. The third category of recommended re-
search is simulation model development and field test validation
of the forecasts obtained from such models. An orderly timing of
these research recommendations could produce an accurate, short-
term index of anticipated impact from released trace contaminants
from a coal cleaning facility for the environmental assessment
program.
ESTIMATION AND RATIONALIZATION OF BIOLOGICAL EFFECTS
Many species of plants, animals (including man), and micro-
organisms will be found living near coal cleaning facilities.
Many individuals will be exposed to pollutants from the facili-
ties' emission streams. If pollutants are discharged to the at-
mosphere, toxic materials may be transported, as indicated earlier,
and be breathed by animals and plants. Waterborne chemicals can
be transported and later affect aquatic plants, animals, and mi-
croorganisms. Nondegradable pollutants can be leached from land-
filled materials and be taken up by crop species to man as well
733
-------
as other receptor organisms and enter food chains. Previous sec-
tions have dealt with our knowledge of such transfers for the
short list of priority pollutants. However, exposure alone does
not Assure an effect. Thus, the problem becomes one of determin-
ing if a specified concentration of pollutants can harm living
organisms in a measurable and significant way once transferred to
the organisms.
Documenting and evaluating biological effects ideally should
precede setting of environmental goals and development of control
technology for coal cleaning facilities. The burden of proof for
establishing environmental goals rests with health and ecological
effects data; i.e., if no problem exists, there is no need for a
solution. Data need to be sound, complete, rigorous, and they
must be interpreted correctly to support environmental goals and
recommendations for further development of control devices for
coal cleaning facilities. More details on this point and the
types of biological effects are found in Cornaby et al., 1978.
Unfortunately, biological effects data are not only relatively
sparse compared to those needed for adequate assessments but
also are typically laboratory results rather than real results
from practice. Thus, the following material was developed as
another step in providing the necessary feedback for prioritiz-
ing pollutants for purposes of control strategies, i.e., which
substances need how much control in order to protect human health,
non-human populations, and ecological systems.
734
-------
Most biological effects data are obtained in the laboratory
and need to be extrapolated to "real world" situations. Extrapo-
lation is the process of inferring or extending a known toxico-
logical response into an unknown area. Conjectural knowledge of
the unknown area is developed based on assumed continuity, cor-
respondence, or other parallelism between it and what is known.
Often/ biological effects need to be extrapolated from (1) labo-
ratory to field—many differences, including lack of transfer co-
efficients, make this difficult, (2) one species to another—no
two species are alike, (3) one medium to another—drinking is not
the same as breathing, and (4) one life stage to another—ranges
of sensitivity may differ by four orders of magnitude. In prac-
tice, biological effects data are collected from a few life stages
of a few species for a few routes of entry in a few controlled
conditions. On the other hand, the real world situation around a
coal cleaning facility contains thousands of species in many
stages of growth, all of which may be continuously exposed to
various types of doses. Extrapolation is almost as much an art
as a science; almost everyone is aware of this. Clearly, ex*-
trapolation must be done with caution.
Despite the technical difficulties involved in estimating
permissible concentrations of toxicants to organisms, approaches
are available for dealing with the problem. There are formulae—
some of them developed by or for the U.S. EPA (Handy and Schindler,
1975) . The formulae have two basic parts: a dose/response part
and an adjustments part. The dose/response generally consists of
735
-------
one of the typical laboratory effects measurements: LD50, LDLQ,
and TL -96 hr*. Each effects measurement is adjusted by several
m
factors—the argument being that the adjusted dose/response data
better conform to the "real world" situation. Adjustments include
the following media conversion (e.g., airborne to waterborne toxi-
cants), safety factors (e.g., 0.01), various types of exposure
(e.g., workday to full week), and elimination rate (e.g., biologi-
cal half-life).
The Multimedia Environmental Goals (MEG) chart is the prin-
cipal tool for displaying goals developed with the use of formulae.
The chart was developed at EPA's Industrial Environmental Research
Laboratory (IERL) and has been refined by Research Triangle In-
stitute (RTI) (Cleland and Kingsbury, 1977) with some assistance
from Battelle's Columbus Laboratories. The chart consists of two
interrelated tables: (1) a control engineering part including
columns for best technology and minimum acute toxicity effluents
(MATE'S) and (2) a health/ecological part including columns for
*LD50: Lethal dose 50, i.e., the dose of a pollutant required to
kill 50 percent of a particular animal species by methods
other than inhalation.
LDLQ: Lethal dose low, i.e., the lowest dose of a substance in-
troduced in one or more portions by any route other than
inhalation over any period of time and reported to have
caused death in a particular animal species.
TLm: Median tolerance limit value, i.e., the concentration in
water of a pollutant required to kill 50 percent of a
particular aquatic species.
736
-------
standards/criteria for both human health and ecological systems.
The chart has rows for the three media—air, water, and land.
The MEG chart is considered an indispensible part of the Environ-
mental Assessment programs at IERL. Any work on the development
of environmental goals needs to be applicable, eventually, to MEG
chart activities. Applications of currently available values are
presented in the paper by Tolle et al. (1978, conference proceed-
ings). In the present section, the thrust of the research is to
expand and improve the quality of the current environmental goals.
The major strengths and limitations of some 20 formulae cur-
rently in use were identified. Extrapolation formulae were re-
viewed from three viewpoints: media, dose/response data, and ad-
justment factors. This evaluation led to improvements in the
state-of-the-art for estimating biological effects.
Ten major strengths of the formulae were identified. Some
of the most powerful were embodied in the formulae used to estimate
permissible concentrations for airborne pollutants. These formu-
lae use a variety of the most rigorous dose/response data which
include a variety of measurements, e.g., threshold limit values
(TLV's) and other large data sets. The ability to incorporate
simple adjustment factors is seen as a strength; generally, the
prediction is assumed to improve as more adjustment factors are
incorporated. Particularly useful adjustment factors are tho,se
for exposure time, elimination rates, and safety factors.
Seventeen major limitations of the formulae were identified.
Prom the media viewpoint, the formulae for land- or food-borne
737
-------
pollutants exhibit the most limitations; the crop uptake model is
too simplistic, among other deficiencies. Many available toxico-
logical response data, e.g., LDT 's, have not been used in the
J_iU
available formulae. Responses are limited to a few species of
animals; few or no responses are provided for plants and micro-
organisms. The bulk of the effects data is based on acute or
short-term exposure when chronic or long-term exposure effects
data are needed. The effects data are for single chemicals when
responses to mixtures of chemicals are needed. So, from the dose/
response viewpoint, there are several limitations. From the ad-
justment factor viewpoint, there is a need for validation of the
reasonableness of the factors. Safety factors need a biological
basis. And, for every limitation in the effects data, there
should be an attempt at a compensatory factor. Thus, if the
chronic effects data are available, a chronic adjustment factor
could help extend the acute effects data. In summary, there are
many limitations.
Research concentrated on the reduction/removal of five of
the limitations: identification of alternative state-of-the-art
formulae, correlation of nonoral with or LD50's, use of chronic
effects data, extrapolation of data from one species to another,
and development of a biological basis for safety factors. The
following material summarizes some of the major points and recom-
mendations achieved in the research.
738
-------
Alternative Formulae
Other formulae could be incorporated into the present system.
Some formulae handle exposure and biological half-lifes more rig-
orously than any one of the 20 formulae. Typical state-of-the-
art formulae are those for (1) maximum permissible concentration
for radioisotopes (International Commission on Radiological Pro-
tection, 1959) and (2) CUMEX (cumulative exposure) index (Walsh
et al., 1977). Inclusion of the former could provide a more rig-
orous estimation of waterborne radionuclides and related pol-
lutants. The latter could provide estimates for air and water
separately and simultaneously. Multiple exposures are the reality
and more formulae, capable of handling such exposures, need to be
developed for future estimations of potential dangers to living
organisms.
Correlate Nonoral with Oral LD50's
One of the more quantitative formulae (Handy and Schindler,
1975) in use requires that dose/response data be in the form of
oral LD50 for rats. However, there are many nonoral toxicologi-
cal response data which could be used, if a conversion method
were available. To overcome this limitation, specially designed
equations were developed by Battelle's Columbus Laboratories to
permit conversion of toxicological data for nonoral routes of
administration to the oral route. Conversions were developed for
intravenous, intraperitoneal, and subcutaneous LDso's and inhala-
tion LC50 to the oral LD50. For example, the relationship for
intravenous LD50 to oral LD50 is:
739
-------
In(oral LD50) = -0.57 + 1.59 In(intravenous LD50)
This research expands the access to other readily available toxi-
cological effects data and is immediately applicable. This type
of research needs to be extended to better utilize the wealth of
toxicological data for other routes of administration, e.g., LDLQ,
TD , LCT~, etc., and for other species (e.g., mice, hamsters and
LO LO
dogs).
Introduce Chronic Effects Data
Limitations inherent to biological effects data for short-
term (acute) exposure can be removed only by use of effects data
for long-term (chronic) exposure. Chronic exposure (low levels
of chemicals for long periods of time) can depress reproductive
capacity, increase the number of malignant tumors, and generally
shorten the life span of males, females, or both. Chronic effects
for life-term (1000+ days) and multigeneration (three-generation)
studies for rodents were examined; Table 3 provides such data.
It is assumed that concentrations lower than those used in acute
exposure (high levels of chemicals for short periods of time)
cause effects that could not have been known on the basis of acute
tests only. Concentrations of 5 ppm for some elements in drink-
ing water seem to show increasingly harmful effects the longer
the study and the greater the number of generations studied. At
present, there seems to be no quantitative way to predict chronic
effects based on effects data only from acute experiments. When
chronic effects data are available, they should be used in the
740
-------
Table 3. Selected chronic effects on multigenerations
of rodents of selected pollutants
Element
Control
As
Cd
Ni
Se
Water
Dosage
(ppm)
—
3
10
5
3
Effects
Death and runts rare; bred
for 4 years
Mice survived well thru F3;
tion in litter size
Toxic to breeders by F2» 13
runts
Litter size decreased; few
Strain began to die by F3;
cent runts
normally
reduc-
percent
males in
24 per- .
Source: Schroeder and Mitchener, 1971.
F2 = second filial generation.
F3 = third filial generation.
741
-------
dose/response part of the formulae if the effects are greater than
those indicated by acute exposure data.
Extrapolation of Response from One Sjaecies to Another
Animal toxicity data can be extrapolated from one species to
another in at least two ways. In one approach, the equation deals
with only one toxicant at a time, but this single equation can be
used to predict the responses of animals of many sizes (including
man) to that particular toxicant. In another approach, the equa-
tion deals with responses to many different toxicants, but it can
only be used to extrapolate from the response of one particular
species to the response of another species (say, from rat to hu-
man) . Both methods are related to the basic relationship of Y -
aWb (Kleiber, 1947; Anderson and Weber, 1975) where Y = the re-
sponse, W = body weight (or area), and a and b are constants rela-
tive to the particular Y. Unfortunately, the basic data are not
readily available. Continued work in extrapolation of one species
to another, especially man, is of such paramount importance.
Biological Bases for Safiety Factors
The range of sensitivity for certain organisms to given toxi-
cants provides a biological basis for safety factors. Toxic levels
and effects of a substance vary greatly. For example, toxicity
ratios for young of a species versus adults can vary from 0.002
to 16—a variation of nearly four orders of magnitude (Casarett
and Doull, 1975). Green algae species differ in their response
to cadmium by a factor of 100 (Buehler and Hirshfield, 1974).
Frog embryos and larvae are more sensitive than adults to
742
-------
mercury by factors of 100 and 1000, respectively (Porter and Hakan-
son, 1976}. Bird embryos and fetal and newborn mammals are more
susceptible to metals than their adult counterparts (National Re-
search Council, 1976). Baby mammals appear to be four to five
times more sensitive than adults to some chemicals (Goldenthal,
1971). In aquatic situations, safety factors of 100 and 1000 seem
reasonable if effects data are available from the most resistant
species; if test data are for the most sensitive species, such
high safety factors are unwarranted. In terrestrial situations,
smaller safety factors seem biologically reasonable. For example,
10 to 100 would be reasonable when the available dose/response
data are for resistant species.
All of these improvements still fall short of the needed ad-
vancements in this important research to protect human health and
the environment from adverse effects. True, the formulae provide
quantitative values and increasingly higher quality effects data
and adjustment factors are being used in such formulae. The state-
of-the-art predictions are not absolute; they are relative. Fur-
thermore, the relative relationships of one prediction to another
may not be correct. Caution is warranted. Validation and future
monitoring are needed to confirm the reliability ,of the predic-
tions. Another major step forward involves the issue of mixtures
as compared to single chemical species. The approach of predicting
permissible concentrations for single chemical species will need
to be replaced by approaches addressing synergistic/antagonistic
effects associated with the release and dispersion of actual
743
-------
emission streams. Then, establishing environmental goals and feed-
back to control technology development will be based, increasingly,
on sound, complete, rigorous effects data.
Pollutant Prioritization
It is not difficult to generate a list containing 100 or
more possible or potential pollutants which can result from coal
cleaning; if coal utilization is included, the list can increase
several-fold. Obviously, these are not all of equal importance.
Thus, one of the goals of the coal cleaning environmental assess-
ment program is to establish decision criteria to determine the
relative priorities to be assigned to controlling specific pol-
lutants.
As indicated in Figure 1 (see page 3) all of the environ-
mental assessment subtasks shown provide input for a prioritiza-
tion. Also, as noted earlier, a fundamental criterion for rank-
ing the importance of any pollutant is the relationship between
its expected environmental concentration and the maximum concen-
tration which presents no hazard to man or biota on a continuous,
long-term basis. The estimated environmental concentrations (EEC)
of pollutants can be projected on the basis of coal feedstock,
process configuration, control devices applied/ environmental
dilution and dispersion, etc.
The other half of the relationship, the estimated permissible
concentration (EPC), is quite another matter. As indicated above,
the toxicological and epidemiological data needed to characterize
the relative health and ecological risks of the pollutants to be
744
-------
expected from coal cleaning processes are woefully inadequate.
(The information base is in far better shape for many of the
chemical compounds encountered in the chemical and similar indus-
tries, but almost none of these are of any concern to coal clean-
ing.) Additionally, the exact chemical form of many coal clean-
ing pollutants is unknown more often than not. There appears
very little likelihood that the EPC data base for coal cleaning
pollutants will improve dramatically in the near future.
Thus, in spite of its undeniable theorectical soundness and
anticipated ultimate success, the EEC/EPC relationships will prob-
ably be unable to provide substantial prioritization guidance
over the near term.
Looking toward the longer term, another of the U.S. EPA's
contractors, the Research Triangle Institute, is developing the
concept of multimedia environmental goals (MEG's) of which health-
related and ecology-related estimated permissible concentrations
of air, water, and land are key parameters. Current status of
this ongoing effort has been described by Cleland and Kingsbury
(1977). Because of the data insufficiencies mentioned above, the
MEG tabulations for pollutants from coal cleaning processes are
incomplete, which limits their present application.
Another approach to the estimation of acceptable concen-
trations utilizes Minimum Acute Toxicity Effluents (MATE's).
These are considered to represent the very approximate concentra-
tions of pollutants in air, water, and land effluents, below
which only minimal harmful responses are evoked by short-term
745
-------
exposure. As reported by Cleland and Kingsbury (1977), six MATE
concentrations may be described for a single compound with two
MATE'S based on health and ecology for each medium. While there
are also large gaps in the toxicological data needed to estimate
MATE'S, the types of data from which MATE'S can be derived are
also of the short-term, acute category and are thus more amen-
able to empirical treatment.
Source Analysis Models (SAM'S) have been developed by Acurex,
another of U.S. EPA's contractors, to assist in comparing elements
of an environmental assessment. The simplest SAM, designated
SAM/IA, is designed for rapid screening of effluent streams and
assumes no effluent transformation. As described by Schalit and
Wolfe (1978), rapid screening of the degree of hazard and the rate
of discharge of toxic pollutants may occur at any level of depth
of chemical and physical analysis. In SAM/IA, effluent concen-
trations are compared to the appropriate MATE's; the comparison
may also evaluate the difference between an uncontrolled process
and one with pollution controls.
In the long run, a rigorous approach to the ranking of rela-
tive importance of pollutants will probably be possible. However,
for the near term, utilizing the assumption that the relative im-
portance of a pollutant can be based generally on its toxicity and
its abundance and that those substances for which criteria have
been established or which have been designated as pollutants are
important. The preliminary "Priority 1" list of 74 pollutants
mentioned earlier had its origin in these considerations. The
746
-------
relative importance of the 13 elements included in the "List of
65 Toxic Pollutants," recently published by EPA (43 FR 4108,
January 31, 1978), has undoubtedly increased as a result of that
listing.
Preliminary working prioritization lists can be derived by
comparing the emission concentrations (uncontrolled and controlled)
in each stream (air or water) with the concentrations established
by air or water quality criteria or by regulation. These concen-
tration levels may be health- or ecology-based, or both; or they
may reflect available technology, e.g., "best available control
technology" (BACT). Such lists will provide a working basis for
prioritization of R & D efforts while the more precise and so-
phisticated MATE'S and MEG's are being perfected. This is the
direction of the current studies, and it is planned to develop a
provisional pollutant rating within the next 6 months. This first
generation prioritization will necessarily be based on less-than-
rigorous criteria, including, where insufficient information is
available, estimations based on scientific judgments. As more
information is developed, refined lists will be generated.
747
-------
REFERENCES
Anderson, P. D., and L. J. Weber. 1975. Toxic response as a
quantitative function of body size. Toxicology and Applied
Pharmacology 33:471-475.
Anderson, S. H., and R. I. Van Hook, Jr. 1973. Uptake and bio-
logical turnover of 109Cd in chipping sparrows (Spizella
Pasaevina). Environ. Physiol. Biochem. 3:243-247.
Ambrose, D., D. Brown, and R. Clark. 1977. Fugitive monitoring
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APPLICATION OF ENVIRONMENTAL ASSESSMENT METHODOLOGY TO HOMER CITY
POWER COMPLEX BACKGROUND DATA: COMPARISON WITH MEG VALUES
D. A. Tolle, D. P. Brown, R. Clark, D. Sharp,
J. M. Stllwell, and B. W. Vigon
Battelle's Columbus Laboratories
Columbus, Ohio
ABSTRACT
During the period from December 1976 through April 1977, a series of multi-
media, grab-sampling campaigns were conducted by Battelle's Columbus Laboratories
at the Homer City Generating Station near Homer City, Pennsylvania. The intent
of this pre-operational monitoring was to document the abundance or concen-
trations of selected key parameters in order to evaluate the air, water, and
biological quality in the vicinity of an advanced coal cleaning plant. These
environmental studies, while not sufficiently long term to be a true baseline
analysis, were conducted prior to operation of the cleaning plant as a reference
point for future, and more comprehensive, environmental testing planned during
operation of the plant.
The multimedia studies involved sampling, laboratory analysis, and eval-
uation of the following components of the environment In and around the Homer
City Generating Station.
• Fugitive dust monitoring using high-volume samplers
• Water and stream sediment quality monitoring from grab samples
• Aquatic biota sampling of attached algae, bottom-dwelling
invertebrates, and fish in streams
• Terrestrial biota reconnaissance of wildlife and vegetation
within a two-mile radius
• Cleaning plant refuse disposal facility evaluation.
The objective of this paper is to present some of the fugitive dust,
water, and sediment sample analysis data from the studies at Homer City and
compare this data with the values listed in the Multimedia Environmental Goals
(MEG) document prepared for the U.S. EPA by Research Triangle Institute. The
MEG values considered in this paper are the maximum levels of significant
contaminants that are Judged to be appropriate for preventing certain negative
effects in the surrounding populations or ecosystems. The MEG methodology
753
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was developed to meet the need for a workable system of evaluating and ranking
pollutants for the purpose of environmental assessment. The values considered
in this paper include the following.
• Minimum Actue Toxicity Effluents (MATE's) - concentrations of
pollutants in undiluted emission streams that are acceptable
for short-term exposure.
• Estimated Permissible Concentrations (EPC's) - the maximum
concentration of a pollutant which presents no hazard to man
or biota on a continuous long-term basis.
The utility of the MEG approach to environmental assessment is explored
in relation to the Homer City data.
INTRODUCTION
Battelle's Columbus Laboratories has contracted with the
U.S. Environmental Protection Agency (U.S. EPA) to perform a com-
prehensive environmental assessment of physical and chemical coal
cleaning processes. The broad goal of this program (Contract No.
68-02-2163) is to establish a strong base of engineering, ecologi-
cal, pollution control, and cost data which-can be used to deter-
mine those coal cleaning processes that are most acceptable from
the technological, environmental, and economic viewpoints. The
data base also will be used for pollution control trade-off
studies that will compare the various individual and combination
techniques for reduction of the pollution potential of coal-fired
power plants. In addition, these data will be used to identify
any areas where development of pollution control equipment may be
needed.
Since one of the program goals involves an analysis of
methods for reducing overall environmental pollution through the
use of cleaned coal, mathematical and modeling techniques will be
used for identification of optimum coal cleaning process
754
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configurations, pollution control equipment, and waste management
techniques. These optimization studies will require an assessment
of the pollution potential of coal cleaning processes, associated
facilities, and—in certain cases—the end uses of coal.
In order to obtain the field data necessary for the overall
program, Battelle is undertaking a sampling and analysis program
designed to identify the combinations of coal cleaning processes
and environmental conditions which are most effective in reducing
the total impact of coal use on the environment. This will be
accomplished through the characterization of process and effluent
streams from a variety of coal cleaning facilities and their
associated coal transportation, storage, and refuse disposal areas.
Objectives of Homer City
Pre-Operational Monitoring
The recent construction of an advanced coal cleaning facility
at the Homer City Power Complex near Homer City, Pennsylvania,
provided a unique opportunity to obtain environmental data both
before and after operation of the plant. Thus, in order to docu-
ment the abundance or concentrations of selected key parameters
Battelle conducted a series of pre-operational, multimedia, grab-
sampling campaigns in a study area that included this facility.
These data were used to evaluate the air, water, and biological
quality in the study area. The pre-operational environmental
studies, while not sufficiently long-term to constitute a true
baseline analysis, were conducted prior to operation of the
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cleaning plant as a reference point for future, more comprehen-
sive, environmental testing planned during operation of the plant.
Specific Objectives of This Paper
The objective of this paper is to present some of the pre-
operational monitoring data from Battalia's study area near Homer
City, Pennsylvania, and to compare these data with the values
listed in the Multimedia Environmental Goals (MEG) documents pre-
pared for the U.S. EPA by Research Triangle Institute (Cleland
and Kingsbury, 1977a and b). The MEG values considered in this
paper represent the maximum levels of significant contaminants
which are not considered to be hazardous to man or the environment.
The MEG methodology was developed to facilitate the evaluation and
ranking of pollutants for the purpose of environmental assessment
of energy-related processes.
MEG values have been estimated for 216 pollutants by extrapo-
lating various toxicity data by means of simple models. For most
of these pollutants, maximum values have been estimated for each
of the three media (air, water, and land). For each of the three
media/ separate maximum values have been estimated which are not
considered to be hazardous to (1) human health and (2) entire eco-
systems.
The MEG values that are particularly appropriate for compari-
son with the environmental monitoring data from Battelle's study
area are those designated as estimated permissible concentrations
(EPC's). EPC's are the maximum concentration of a pollutant
756
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which presents no hazard to man or biota on a continuous long-term
basis. These EPC values are considered acceptable in the ambient
air, water, or soil, and do not apply to undiluted effluent
streams. The ambient application of EPC's corresponds to the ambi-
ent type of sampling conducted by Battelle prior to operation of
the Homer City Coal Cleaning Plant.
A second type of MEG values considered in this paper is one
comprised of minimum acute toxicity effluent (MATE) values.
MATE'S are concentrations of pollutants in undiluted effluent
streams which will not adversely affect those persons or ecologi-
cal systems exposed for short time periods. Very little of the
pre-operational monitoring conducted by Battelle near Homer City
involved undiluted effluents, but in the case of a few pollutants,
this value was the only MEG value determined.
Description of the Study Area
Nearly all of Battelle'a environmental monitoring was con-
ducted within a study area that can be approximately bounded by a
circle 4 miles (6.4 km) in diameter. The advanced coal cleaning
plant in the center of the study area is about 2 miles (3.2 km)
southwest of Homer City, Pennsylvania. Only two of the aquatic
biota sampling stations were slightly outside of the circular
study area.
The six major habitat types within the study area are hard-
wood forest, coniferous forest, cropland, grassland, water bodies,
and areas of industrial development. The forested areas are
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primarily hardwoods, dominated by oak and hickory. Isolated
pockets of pine are present as plantations rather than naturally
occurring species. Cropland is extensive in the study area, in-
cluding contour and strip-cropped fields of corn, wheat, and hay.
Grasslands include those areas that are presently grazed and
those areas that were previously grazed or farmed and are now in
a transition stage toward becoming a forest.
Stream water quality evaluated within the study area is
affected by a number of land uses which are either included in the
immediate study area or take place at locations farther upstream.
The five major land uses affecting stream water are: agriculture,
mining, urban, construction, and power generation. Agricultural
runoff is a problem because of the hilly terrain and includes run-
off from both farmland and pastures. Almost the entire study
area is on top of deep mines, while much of the upstream water-
sheds add acid mine drainage from abandoned or active strip mines.
As indicated earlier, Homer City/ Pennsylvania, is immediately
adjacent to the study area on the northeast, and Indiana, Pennsyl-
vania is only 5 miles (8.0 km) north of Homer City. Both towns
directly or indirectly add effluents from industrial and sewage
treatment facilities to Two Lick Creek before it flows through
the study area. During Battelle's sampling campaigns, both the
coal cleaning plant and the refuse disposal area for that facility
were under construction in the study area. Finally, the study
area includes the Homer City Power Station, with its associated
coal storage, water treatment, and waste disposal facilities.
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The Homer City Station is one part of an integrated power
complex which includes two deep coal mines; coal cleaning, stor-
age, and transport facilities; power generation facilities; and
waste disposal and treatment facilities (Figure 1}. Coal used at
the Homer City Station comes from the two dedicated deep mines in
the power complex, as well as that hauled by truck from other
mines. Solid refuse from power complex activities is deposited
in three different types of disposal areas, including an ash dis-
posal area, mine waste or "boney" piles, and the cleaning plant
refuse disposal area. Liquid waste treatment facilities in the
power complex include: mine and boney pile leachate water treat-
ment facilities, an emergency holding pond constructed near the
coal cleaning plant, coal storage pile runoff desilting ponds, an
industrial waste treatment plant, power plant storm runoff desilt-
ing ponds, bottom ash sluice water desilting ponds, sewage treat-
ment facilities, and ash disposal area leachate treatment ponds.
SAMPLING AND ANALYSIS TECHNIQUES
During the period from December 1976 through April 1977, a
series of three pre-operational, grab-sampling campaigns were con-
ducted by Battelle in the ambient media of the study area which
included the Homer City Power Complex. These environmental moni-
toring studies involved sampling, laboratory analysis, and/or
evaluation of the following components of the environment.
• Fugitive dust
• Stream water and sediments
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A - Aih Diipoul Area
B — Mine Drainage Treatment Pond
C - Helvetia Boney Pile
O — Coal Cleaning Plant
E - Coal Storage Pita
F - Power Plant
G - Induitrial Wait* Treatment Plant
H - Helen Boney Pill
Figure 1. Map of the Homer City Power Complex
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• Aquatic biota
• Terrestrial biota
• Raw coal and fly ash
• Cleaning plant refuse disposal area
• Groundwater.
Only the first three were analyzed in sufficient detail to warrant
comparison with MEG values. Samples of fugitive dust, water, and
stream sediments were collected during three campaigns and
analyzed for physical and chemical parameters. Aquatic biota were
sampled during two campaigns for determination of indicator spe-
cies, standing crop, species diversity, and chemical analysis of
fish.
Fugitive Dust
Fugitive dust monitoring was conducted using high-volume (hi-
vol) ambient air samplers during the following three 48-hour sam-
pling periods:
• Campaign I: 8 p.m. December 17 to 8 p.m. December 19, 1976
• Campaign II: 8 p.m. January 5 to 8 p.m. January 7, 1977
• Campaign III: 8 p.m. April 5 to 8 p.m. April 7, 1977.
The first of these three campaigns was conducted over a weekend
when both coal transfer and construction activities were low.
A multiple-source . fugitive-dust dispersion model was used to
select and verify locations for hi-vol samplers (Figure 2). This
model takes into account such factors as wind speed, emission
rate, particle size, and distance from selected potential dust
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Coal Cleaning
Refuse Disposal
Existing Ash
Disposal Area
Coal Cleaning Plant
Coal Storage Pile
Substation
(1)
Power Plant
Cooling Towers
Wind Speed and Direction
Recorder
5 ) Hi Vol. Sampler
Figure 2. Location of fugitive dust sources and
monitoring sites.
762
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sources located within the Homer City Power Complex. No dust
sources outside of the power complex were incorporated in the
model. On the basis of the computer-generated diffusion-modeling
results, ten monitoring sites were established at distances of
175 to 2200 m downwind from various local dust sources. One of
the ten sites was on private property downwind of the power com-
plex, while another was on private property upwind of the complex.
Several potential dust sources, both local and regional,
were not incorporated into the diffusion model for sampling site
selection. Dust generated by vehicular traffic, parking lots,
construction activities, several storage silos, and especially
that originating from the surface of the plant grounds were not
included in the model because of their erratic and nonpoint-
source nature. Data for the Homer City Power Plant stack emis-
sions were not available in time to include them in the model.
In addition, four other major power stations (Keystone, Conemaugh,
Seward, and Shawville) are located in the same Chestnut Ridge sec-
tor of the Allegheny Mountains as Homer City. These utilities
are fed from coal mines located either directly under or near the
station sites. The model did not include fugitive emission data
from any of these facilities.
Potential fugitive dust sources at the Homer City Power Com-
plex were investigated during a pre-sampling site evaluation.
Some of the dust sources included an ash disposal area, boney
piles at both deep mines, a coal storage pile, road dust, three
power plant stacks, and construction-generated dust. The coal
763
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cleaning plant with its thermal dryers and the cleaning plant
refuse disposal area were under construction during Battelle's
sampling campaigns. Since these two areas were considered to be
future potential sources of fugitive dust, they were considered
in the selection of sampling sites.
In order to identify the type and quantity of pollutants
being emitted from fugitive dust sources, a variety of analytical
techniques were employed. Particulate mass was determined by
weighing the 8 x 10-inch fiberglass filters used in the hi-vol
samplers before and after each of the 12- or 24-hour sampling per-
iods. A microscopic analysis was made of particulates to provide
a distinction between components such as coal dust, fly ash,
pollen, or construction dust. An Andersen sampling head was used
on one hi-vol sampler to obtain data on the distribution of par-
ticles in five size fractions.
Particulates on the filters from the hi-vol samplers were
analyzed for up to 22 elements. The analytical technique used for
most elements was atomic absorption, but neutron activation, col-
orimetry, a specific ion meter, a total organic carbon analyzer,
an LDC mercury monitor, and potentiometric titration were also
used. Since large amounts of four of these 22 elements (Na, K,
Ca, and Mg) were found in the blank filters, the values for these
four elements were not reported. Four of•the remaining 18 ele-
ments (Sb, Ti, V, Se) were analyzed only in the second or third
campaign. in general, the filter exhibiting the highest
764
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percentage of coal or ash from each site was used for analysis.
Data for 15 of the elements are compared in this paper.
Stream Water and Sediments
A wide variety of water and sediment quality parameters were
selected for analysis in the streams and tributaries in the study
area (Figure 3). The selection of water and sediment quality
parameters was based on the diversity of land use in the general
area, including farming, mining, urban, construction, and power
generation activities. The analytical techniques for water and
sediment samples were numerous and involved the techniques
suggested in the following seven references: American Society of
Agronomy and ASTM (1965), Hem (1970), Stumm (1970), Stumm and Lee
(I960), Stumm and Morgan (1970), U.S. Department of the Interior
(1974), and U.S. Environmental Protection Agency (1969). in this
paper, analytical results for 30 water quality and 9 sediment
quality parameters are used for comparison with MEG values.
The sampling locations for surface water and stream sediments
were selected in advance of field monitoring (Figures 4 and 5).
The order of sampling was always from downstream to upstream. All
sites within a given watershed were sampled on the same day or on
two consecutive days.
All samples were collected in prewashed polyethylene bottles
or glass jars by one of the two following methods: (1) grab sam-
pling, and (2) use of an automatic sampler. Grab sampling con-
sisted of submerging each container while keeping it as close to
765
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Figure 3. Streams and tributaries surveyed in the
Homer City area.
766
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Figure 4. Surface water quality sampling locations,
767
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Figure 5. Stream sediment sampling locations.
768
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the surface as possible to prevent disturbing the bottom sediment.
The automatic composite sampler (Instrumentation Specialties Com-
pany, Model 1580) was used at two sites where the water quality
was more variable.
Additional data were recorded at each site while collecting
the sample. A Yellow Springs Instrument Company polarographic
D.O. meter was used to measure the dissolved oxygen content and
temperature, while a Beckman Solu-Bridge was used for specific
conductance determinations. Current measurements were taken with
a Price-type current meter (Pygmy meter). Flow was estimated us-
ing the velocity-area method.
Sediment samples were obtained from several streambeds.
Sediment was defined as any material that would pass through a
10-mesh screen. There was difficulty in obtaining an adequate
sample at some sites where the streambed was composed largely of
gravel.
Aquatic Biota
Fourteen aquatic biota sampling sites were selected in seven
streams in the study area, as well as in an additional control
stream, Ramsey Run, which is about 6 miles (9.6 km) north-northeast
of the study area and about 1 mile (1.6 km) east of Indiana, Penn-
sylvania (Figure 6). Sites were chosen which would provide the
best data for evaluating the impact of the existing facilities in
the complex on the aquatic biota of the receiving streams. Sam-
pling was conducted both upstream and downstream from potential
769
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Kilometer
0 0.5 1.0
0 1/2
Mile
Ramsey Run
Figure 6. Aquatic biota sampling locations,
770
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sources of pollution. Thus, the prior effect of upstream sources
of pollution on aquatic biota was included in the assessment of
the study area. Only a minimal sampling effort was carried out
in Two Lick Creek because a survey by Environmental Sciences, Inc.,
{1972} reported that this stream had poor water and aquatic biota
quality due primarily to acid mine drainage from abandoned strip-
mines located upstream.
Three groups of aquatic organisms were selected for study:
(1) periphyton (attached algae, especially diatoms), (2) benthic
macroinvertebrates (bottom-dwelling invertebrates visible to the
naked eye), and (3) fish. These three groups of organisms were
chosen because of their relative ease of collection, usefulness
as water quality indicators, and importance in aquatic food webs.
Attached algae were sampled in triplicate by scraping cobble-
size rocks from the stream bottom. The preserved diatoms were
prepared for viewing on a microscope slide and identified to spe-
cies. Standing crop was expressed for each species in terms of
number of organisms/cm2. Finally, total periphyton standing crop
and total number of species identified were calculated for each
sampling site.
Bottom-dwelling macroinvertebrates were collected from riffle
areas using a Surbur sampler. Five replicate samples were taken
at all stations and were preserved with formalin and returned to
Battelle for sorting, identification, and enumeration. All organ-
isms were identified to the lowest practical taxon, and the
771
-------
resulting data were used to calculate species diversities accord-
ing to the Shannon-Weaver formula (Shannon and Weaver, 1963).
Fish were collected by using a 4 x 6-ft, 1/4-in-mesh seine
and/or a backpack shocker. Both devices were used during the
spring survey, but only the seine was used during the winter sur-
vey. Fishing was conducted with approximately equal effort
(1/2 hour) at each station. Fish were identified, recorded, and
released. Specimens not positively identified in the field were
placed in sample bottles, preserved, and returned to the labora-
tory for identification.
Biological quality was determined for each of eight portions
of streams or tributaries surveyed in the study area. Quality of
the biota in the control stream (Ramsey Run) was evaluated as good
and provided a basis for comparing the other streams. The subjec-
tive evaluation of aquatic biota quality in each stream was deter-
mined by initially evaluating each of the three groups of organ-
isms surveyed. The evaluations were based on the presence of indi-
cator species, standing crop of diatoms, species diversity of
bottom-dwelling macroinvertebrates, and number of individuals per
fish species. Finally, overall biological quality ratings of
good, fair, or poor were based on the individual ratings for the
three aquatic biota groups.
COMPARISON OF ANALYTICAL DATA WITH MEG VALUES •
Analytical data for fugitive dust, fly ash, raw coal, surface
water, and stream sediments sampled in the study area have been
772
-------
converted to the units used in the multimedia environmental goals
(MEG) study (Cleland and Kingsbury, 1977a and b). These data are
compared with the estimated permissible concentrations (EPC's}
and/or the minimum acute toxicity effluent (MATE) values defined
in the Introduction to this paper. In addition, the observed and
recommended values for stream water and sediments are compared
with the biological quality evaluations made at sampling locations
in the same portion of a given stream.
Fugitive Dust Analysis
Average concentrations of 15 elements analyzed in the fugi-
tive dust from the study area are compared with the EPC's for air in
Table 1. Since most of the fugitive dust appeared to emanate from
the coal storage pile and decline in concentration within 200 to
300 m downwind (Figure 7), the data have been averaged for the
sampling sites located between 150 to 175 m and 400 to 1,800 m
downwind from the coal pile. The fugitive dust concentrations fo]
the upwind "control" sampling location are also provided. These
field data are followed by the appropriate maximum EPC's for air
which are recommended for each element to prevent negative effects
to humans or the surrounding environment during continuous long-
term (chronic) exposure. A difficulty in making comparisons be-
tween observed and recommended levels of the 15 elements shown in
Table 1 is that three EPC's for human health and 10 EPC's for the
environment are not available.
Average concentrations for three of the elements (As, Cr, and
Pb) analyzed in fugitive dust exceeded the EPC's for human health.
773
-------
Table 1. Fugitive dust comparisons
versus Homer City data
)s EPC values for air
Trace Eleneat Concentration*, ug/m
Distance from
Coal Pile
Downwind 150-175 n^
Dowwind 400-1.800 »(c)
Unwind Control'**
EPC Category
Health
Ecology
As Cd
Average
Cr Cu
Concentration in
0.014 0.008 .026 0.292
0.010 0.014 .015 0.119
0.009 0.005 .014 0.223
0.005 0.12
— 0.04
0.0020.5
_ _
Fe
Pb
Fugitive Dust
Mn
During 3
3.45 0.586 0.076
1.87 0.334 0.093
1.6S 0.258 0.041
Estimated Feradsaible
—
* 0.36
!<«>
12
HR
Canmaigns
Hi n
Zn a F T Se
•t Boner City (24-hr Sanpllng Periods) M
O.OOOM 0.015 O.U
0.00009 0.013 0.32
0.00003 0.009 0.17(i)
Concentrations (EPC's)(c).
»-
0.04«>14
0.35*4) 1.97W) 5.47 TO^' 0.0049
0.22 0.82 2.03 HD 0.0026(1>
0.13 1.05 1.40 0.02(1) O.W»(i*
W/n3
9
.5 — — 1.2 0.5
(a) All (Uta uere collected between December 1976 and April 1977.
O>) Average for saapllng aites 1 and 3; dovmrlnd of coal pile.
(c) Average for saspllng sites 4. 8, and 9; doumrlnd of coal pile.
(d) Sampling site 6; upwind of coal pile about 1600 • and off of the power stitloo property.
(e) From Cleland and Klngabury (1977).
(f) Based oo a Toxic Unilt Value (TLT) vhich recognlsea the eleneat's carclno-cenic potential
(g) Based on teratogenlc potential.
(h) H>t available.
(1) Concentrations vere not available for some sanpling sites daring all three campaigns.
(J) •> - not detectable.
-------
- 1300
-2 I2OO
o
Park
7
Future
Coal Refuse
Site
500 1000
Meters From Coal Storage Pile
1500
Figure 7. Fugitive dust concentrations compared to a transect
of the area's topographical relief.
300
250
t
200o.
ISO.g.
100 £
50 **
2000
-------
These values have been underlined in Table 1. It is noteworthy
that two of these elements (As and Cr) had concentrations above
the health-based EPC, even at the upwind "control" location.
Maximum and minimum concentrations of 15 elements analyzed
in fugitive dust are compared with the appropriate EPC's for soil
in Table 2. Again, the data are grouped to include sampling sites
located less than 200 m (i.e., 150 to 175 m) and greater than 200 m
(i.e., 400 to 1,800 m) downwind of the coal pile. Concentrations
of the same elements in the raw coal are also shown. EPC's for
protection of human health and the environment are given for 12
elements; no EPC values for iron, chlorine, and fluorine have
been determined.
The majority of the elements analyzed showed maximum, and fre-
quently minimum, concentrations in the fugitive dust which were
far greater than the EPC levels suggested for the soil. Ten ele-
ments exceeded the EPC's for human health and 11 elements exceeded
the EPC's for the environment. Both the maximum and minimum con-
centrations of 8 elements (As, Cd, Cr, Cu, Pb, Mn, Ni, and Se) in
the fugitive dust exceeded the EPC's for both human health and the
environment.
Obviously, the detected concentrations of toxic trace ele-
ments in fugitive coal dust that has settled to the ground sur-
face do not indicate that these same concentrations occur in the
soil. However, studies involving soil contamination by other
types of particulate deposition have shown that toxic trace ele-
ments in these partioulates can cause ecosystem disruption
776
-------
Table 2. Fugitive dust comparisons (yg/g): EPC values for soil
versus Homer City data
Maximum
Minimum
As Cd Cr
154 26« 471
11 18 18
Cu
Concent rat Ions
3,678 28
336 6
Fe
Trace den
Pb
in Psrticulate at
.736
.223
Concentrations in Participate at
Haximua
Minimum
238 619 667
3«_ ND 46
6.061 57
220 11
.576
.477
17,241
501
ent Concentration, ui/g
Ha Hg
Sampling Sites
632 3
65 0.2
Ni
Tl
within 200 • of
264
23
Sampling Sites Between 200 and 2 000
12.857
566
5.603 2
6 ND
545
H>
Estimated Permissible Concentrations
Health
Ecology
Kaxicua
Minimum
10 0.06
1 a(d)
10 50(C>
i 1H)
Concentrations Determined by Individual Analysis
.31 48
20 18
.750
.000
17.3
H
2* 1.1
35 0.34
0.1 ) for Soil
1,000
i
27,278 45.600
S.806 1,818
00
-» ->>
-.<«) _<«>
V
3)(.)
ND
ND
«J 9)ta)
ND
m
1.4
12-
Se
33
4.
122.
1
2
SLJL<«
Homer City Coal Sources ***
1,329
1.125
66
46
0.26 108
0.23 91
65
»
ND
ND
(a) Data from three sampling campaigns conducted by tattelle In the study area.
(b) From Cleland and Klngsbury (1977): all values «ere multiplied by 100 based om perseaal commuilcacloa with ttngsbury (August. 1978).
(c) Baied on carcinogenic potential.
(d) Based on teratogenlc potential.
(e) Value noc available.
(f) KD - not detectable.
(C) Coal sources Include: Helen Mining Company and Helvetia Coal Company (from Upper rreemo.t Sean); and Trucked-ln Coal (from Lower Mttannin* Sean).
-------
resulting in the loss of essential nutrients and can also result
in increased concentrations of these toxic elements in both plants
and animals. These types of effects have been demonstrated for
lead smelter emissions (Jackson and Watson, 1977; Kerin, 1975) and
for fly ash emissions from coal-fired power plants (Furr et al.,
1977). Dvorak et al. (1978) have speculated that long-term expo-
sure to uncombusted coal dust may cause changes in vegetation com-
munity structure similar to those caused by particulates from coal
combustion.
Mechanisms for the movement of toxic trace elements from par-
ticulate emissions deposited on the ground to the root zone of the
soil are complex (Vaughan et al., 1975; Dvorak et al., 1978). A
partial list of the factors that influence leaching of trace ele-
ments from deposited particulates into the soil solution include:
(1) the size and type of particulates, (2) the amount and acidity
of precipitation, (3) the concentrations and physicochemical pro-
perties of the trace elements, (4) the texture, organic content,
pH, and other characteristics of the soil, (5) the solubility of
elements into the soil solution, and (6) the temperature of the
air and soil.
The fugitive dust quantity and composition found during moni-
toring has probably been accumulating on the ground in a reason-
ably similar fashion since the power plant (including the coal
storage pile) began operation in 1969. Thus, mobile elements in
the settled dust may have leached into the soil. The quantity of
toxic trace elements available to vegetation, however, needs to
778
-------
be determined by chemical analysis of the soil. In spite of any
leaching of trace elements which may have increased soil concen-
trations, vegetation growing within a broad band around the coal pile
has not yet experienced any apparent adverse effects. An analysis
of soil biota and plant diversity, however, was not conducted.
Stream Water, Sediments, and Biota Analysis
Stream Water Concentrations Versus MEG Values
Maximum and minimum concentrations of 15 elements that were
analyzed in surface water are compared with the appropriate MATE
and EPC values for the environment in Table 3. These data were
organized to correspond to the biological sampling locations for
additional comparisons. Although data were obtained in the study
area near Homer City for 30 different parameters used to define
water quality in stream water, MEG values are only available for
the parameters listed in Table 3.
EPC and MATE values suggested for the environment were
exceeded by many of the maximum and minimum values determined for
the 15 water quality parameters listed in Table 3. Maximum values
for nine parameters measured in surface water throughout the study
area exceeded the corresponding MATE values, and maximum values
for 11 parameters exceeded the corresponding EPC values. Maximum
and minimum values of measured parameters exceeded EPC's in the
following 10 cases: beryllium, lead, ammonia, nitrogen, arsenic,
manganese, nickel, copper, zinc, and cadmium.
779
-------
Table 3. Surface water quality comparisons (yg/1):
(a)
Homer City data
MEG values versus
Stnan in the Tlclnltr of ROOT City Station
KK Category
and Subctun.
IB Phenolic*
31 taryllloB
34 Calcine?
46 Uad
47 Amoala
S MtrC|"
O *' Arienlc
63 vanadliai
68 Chrralixi
~4£
68 Chromlu.
71 Kanianeae
76 Slclol
70 Copper
81 Hoc
81 Cadclua
83' Mercury
Mtnlsus)
Acute
Toxlclty
Effluent
(MATE) for
Ecology
300
33
1ft. OOP
30
30
SO
130
230
130
100
10
30
100
1
130
Cherry Hortb South Trll
loni Tributary to to Cherry
Kalo Steai Cherry Ron Upatreaa
tat tatted
rermdealble
CooceatratloB
(ETC)
for Eulogy Ku. Kin. Kax. Kin. Max. Mln.
fjjjjW) _(c) _____
JJ.(d) RD<() HD HD ID BD TO
— 13.600 16.300 10.300 17.400 JLSffil M.2BO
Jfl(b) .BD BD BD BD BD BD
Jfl.W> fil <30 iff. «SO M «SO
JA( HD HD HD HD BD HD
Ji(d> HD BD KD HD JQQ, KD
Jfl(d> BD BD BD BD BD BD
ja ' — — — — — —
'J&. Afifl IP ^AO, 20 no %a
I BD RD KD HD HD BO
J0.(d) FD ID BD BD HD ID
ittw) 23. m 20 20 30 30
JIAM> KD KD HD HD BD BD
ifl(dj BD KD BD BD BD BO
^nrary
tan
- Vler a Kun Tributary
telov Aab to
Dovnatream mapoaa] Area Vler'a Ron
Water Ouallty
Max. Kin.
_
RD HD
37.200 7.200
BD BD
Data from.
(c) Data not i
W) Baaed no •
> en fives IB
r r r
r e a
r c a
r c e
VB/ll ETC ead HATE valoea an froa Oeland ead Ungabuiy (1977).
r
r
?
r
Cvaluatlof
Max.
10
RD
«ntsno
BD
jua
8
BD
BD
—
i.lOO
US.
m
120
KD
BD
,«"
Kin Ku. Din. '
KD 7 6
HD — —
86.000 — —
BD KD BD
Iffi - -
HD RD HD
KD — —
KD BD BD
_ _ _
1.400 — —
70 HD HP
KD RD RD
JO, 40 BD
BD BD BD
KD BD KD
tater'a
rood Com
Trlbntary
Max.
Jifl
20
IQr.OOO
KD
OiatQ
29
RD
BD
_
43.20O
640
1.730
i
BD
SinT"
e
iO
113.000
HD
JM
BD
HD
HD
_
1.110
SO
HD
159.
BD
HD
tarlna
Max. Mln.
yto ^
BD Hft
UQjsaa 102.300
3O 2Q
iViiXl 1.600
ifl J31
KD KD
40 20
~™ •.
jjsa «a
no a
ifl X.
122 221
± _l_
BD BD
Teo Uck
Ku.
a
BD
43. »00
RD
1.280
•KD
RD
BD
HD
RD
• HD
iia
BD
BD
KJn.
BD
BD
11.000
RD
ISO
RD
BD
HD
aa.
HD
RD
a.
BD
HO
teferace
Streaa
Dec-Apr
_
3.300
1
__
,j
10
J9
0
0
0
«o.s
E*alutlo«(l>
r e
r c
r c
r c-
V
r
r
r
r
r
r
t.
r
r
r
t
three sassllng csapalgn* contacted by lattelle la the a tody area
nrallable.
mat etrlagent
exlatloK or propoaed Federal etandard for water quality.
(e) Cnt«lc«l aoalrsle Atria* water year 1973 of Young Vaaan's Creek near sanovo. fa.
•(I) ID - not detectable.
(g) The aquatic biota evaloi
C - Good: f » rain and
itlona an baaed
-------
Streams considered to have good biological quality also had
levels of pollutants which exceeded EPC or MATE values for the
environment. Maximum and minimum levels of manganese and zinc in
streams with good aquatic biota quality exceeded the EPC values
for the environment. Maximum levels, alone, of two additional
parameters (ammonia and vanadium) in streams with good aquatic
biota quality also exceeded the EPC values for the environment.
Similarly, maximum and minimum levels of calcium and manganese in
streams with a good biological quality rating exceeded the MATE
values for the environment.
Stream Water Concentrations Versus Recommended Values
MEG values have not yet been determined for 14 of the 30
water quality parameters measured in Battelle's study area.
Therefore, comparisons have been made between these 14 parameters
and 8 values recommended by the EPA (1976) or suggested by McKee
and Wolfe (1963) (Table 4). A biological quality evaluation of
the same stream stretches that were analyzed for water quality is
presented for comparison with the chemical data.
All eight of the water quality criteria concentrations recom-
mended by EPA (1976) or McKee and Wolf (1963) were exceeded by
one or more concentrations of the same parameters measured in sam-
ples from streams in the study area (Table 4). The maximum and
minimum values for alkalinity, sulfate, and total solids observed
in one of the streams with a good biological quality rating were
greater than the recommended criteria concentrations.
781
-------
Table 4. S.urface water quality comparisons (yg/1) :
versus Homer City Data
Recommended criteria
oo
N>
' ' ttecoa.«««.M Crttarlfloi
*S5, rr........ ft., v
rSZmun 4Ta(k) felaa 4 Half1
. Ckanr Imi
Kala, (tail
i
if
•» kai Kla
Itruoa ID tba VlclolIT of Booar City Station
fcrth aotth TrttaMIT "I!'\I!r Tt"S"T "T^l" TO. lick
Tributary •» °-"T •— . •"-• aak To Fooo Too Uck
To Coarrr *-* f
^^^*^^^*^^~~°~~^^^^^^^~
OBI Bla KM
Ultcr Quality Evaloatloo
Hma Ua ama IB
(era.
a Hta mm Ka. HU Haa Ho avataoi
acUltf . a* CoODj — '*' —
alaalUltf. ao Can, > 20.000 —
OB «.0-4.1 f.0-4.1
Total to 1.000 204)
•Iiaolaod l» — —
r."
Tot..! FfcaajhonM 10Q —
**l*tll* tell* — —
•Ur*t* - • 10.000 —
TotU U«l«.*l - • — —
Tut*l OvftOBlc CkctaB H ~*
Total aolUa — 101.000*4*
7,100 1.400
44,100 11.200
I.XO 140
740 <20
740 <100
11.400 17.100
40 «10
14.000 1.000
34.000 2.000
2,000 740
140 140
4,000 1.700
143.000 124.000
7.200 1.400 1.400
44.200 21.100 l>.tOO
1,710 140 110
10 40 to
420 «100 HO
17.300 27.300 247.000
100 10 10
10.000 1,200 10,400
41,000 7.000 30.000
1,420 140 1.000
140 <30 270
2,000 1,200 1,300
m.ooo 124.000 442.000
1.400 4.100 1.400
12.600 U.700 7.100
40 440 200
IQoalltw Crltarla for Batar* (IT1, H74).
(c) ^tatar Qullly Crlt.rU' QUoa aa* Volt. 1*4]).
M) Oioalcal aaaljrala «aTU| aatar yoar 1171 of To«a Vbaao'o
((a) lot avallakla.
(S> UtUato* Vy aoaalai tka ^loaa ri an
00 Taa aaaatlc aloca •valattloat ara tmt
C- Oao4i r - Falri oo< t - roor taomtu
(1) D - aot oatactaklo.
lot for aaaxaooat
llota Qaalltr. 1
r
e
e
e
Croak oaar tamo. ro.
M tka atadj «roa
aad 41aaol»ad aolUa.
aractM dlvaraltj. aa4 an
r r
c r
c r
e r
oaac* of tnalcator aoaclaa or
r o
r o
r o
r e
faolliaa!
lo u tka ataay ataa.
T r r
• t » r
» » i
» ft
-------
A comparison of the data for each of the 30 surface water
quality parameters with the biological quality evaluation for the
same stream segment suggests that values for four parameters agree
closely with the biological quality rating (Tables 3 and 4). The
maximum and minimum values for these four parameters (pH, sus-
pended solids, dissolved iron, and total organic carbon) have
been compared with recommended or suggested water quality cri-
teria in Table 5. It can be seen that streams with good biologi-
cal quality did not have any levels of these four parameters
which were above the recommended criteria. Maximum, and fre-
quently minimum, values of these four parameters, however,
exceeded the recommended criteria in streams with poor biological
quality. The significance of these four "master" parameters to
aquatic biota is probably great because they affect the presence
of toxicity of other potential water pollutants.
Several studies have described the effects of water pollu-
tants in acid mine drainage on aquatic biota. These studies
found that the master chemical factors involved one or more of
the parameters listed in Table 5. Weed and Rutschky (1972), for
example, found that pH, alkalinity, and ionic concentrations of
iron and sulfate were primarily responsible for altering the com-
munity structure and diversity of benthic macroinvertebrates.
Similarly, Warner (1971) found that pH measurements in streams
seemed to provide the most reliable, as well as unique, index of
the effects of acid mine drainage on aquatic life. A report by
the Federal Water Pollution Control Administration (1969)
783
-------
Table 5. Water quality parameters in close agreement
with biota quality rating
Sampling Sites
Water Quality
Parameter
pH (6.5-9.0)
Suspended Solids
(20,000 yg/1) (c>
Dissolved Fe '
(1,000 yg/1)
Total Organic Carbon
(4,000 yg/1) specif ied
1
1
0
0
1
2
F
2
0
0
0
0
0
G
3
0
0
0
0
0
G
4
1
1
0
1
3
P
5
1
1
1
1
4
P
6
2
2
2 .
1
7
P
value
7
2
2
1
2
7
P
(a) j
8
2
1
2
1
6
P
(a) Maximum and minimum units or concentrationsspecified value = 1; maximum and
minimum units or concentrations>specified value = 2.
(b) Criteria recommended by EPA (1976).
(c) Criteria suggested on the basis of the chemical and biological data
presented in this paper.
(d) G - good; F = fair; P - poor quality.
concluded that acid mine drainage damages aquatic biota primarily
because of the high concentrations of mineral acids, the ions of
iron, sulfate, and the deposition of a smothering blanket of pre-
cipitated iron salts on the stream bed.
Sediment Concentrations Versus MEG Values
EPC values for nine trace elements (Pb, As, Cr, Mn, Ni, Cu,
Zn, Cd, and Hg) which were measured in stream sediments were
exceeded by both the maximum and minimum stream concentrations for
eight of these elements (Table 6). Comparisons of concentrations
784
-------
Table 6. Sediment quality comparisons (ug/g):
soil versus Homer City data
MEG values for
Ln
Streams in the Vicinity of Homer City
MEG Category
and Substance
46 Lead
49 Arsenic
68 Chromium
71 .Manganese
76 Nickel
78 Copper
81 Zinc
82 Cadmium
83 Mercury
MATE
for
Ecology
10
10
50
20
2
10
20
0.2
50
KPC
for
Ecology
_2
10
4
0.4
20
0.01(d>
3(d)
Cherry
Run:
Main Stem
Upstream
On South
Tributary
To
i Cherry Run
Station
Hiet's Run
Below Ash
Disposal Area
Concentrations in Stream
Max. Min
50 19
15 4
346 84
2,830 248
207 71
440 23
387 _75
1.0 0
Max.
63
.8 9.
225
1.430
130
310
677
.5 1.
Min.
36
6 6.6
157
612 1,
115
120
244
0 0.5
Max.
29
19
197
,000
117
270
210
0.4
0.25 0.010 0.016 0.016 0.15
Biological Quality Evaluation
Two Lick
Creek
Sediments ^
Min.
2
7.6
102
349
71
Max.
85
21.5
132.5
251.5
79
25 230
65 207
0.2 0.55
0.024 0.53
(g)
Min.
48.
10
90
210
33
i*
108
0.55
0.42
Analysis (e)
Max.
14
5.4
144
75
126
12
0.6
0.14
Min.
12
3.8
112
sr
71
90
40
0.6
<0.005
Analysis
of Three ...
Raw Coals1'
Max.
17.8
49
36
76
17.5
32
ii
0.27
1.1
Min.
12.3
23
31
36
13.2
21
0.1
0.35
Attached Algae
Bottom-Dwelling
Invertebrates
Fish
Overall
P
F
F
G
C
G
P
P
P
P
r
p
(a) MEG - Multimedia Environmental Goals from Cleland and Klngsbury (1977); all values were multiplied by 100 based on
personal communication with Klngsbury (August, 1978); all values in ug/g dry weight.
(b) MATE - Minimum Acute Toxicity Effluent; EPC - Estimated Permissible Concentrations.
(c) Based on three sampling campaigns conducted by Battelle in the stud; area.
(d) Based on potential teratogenic effects.
(e) Sampled in ash disposal area.
(f) Raw coals sampled at Homer City include those from: Helen Mining Co. and Helvetia Coal Co. (from Upper Freeport Seam) and
Trucked-in Coal (from Lower Klttanning Seam).
(g) The aquatic biota evaluations are based on standing crop, species diversity? and presence of indicator species or families;
G - Good; F - Fair; and P • Poor Aquatic Biota Quality.
(h) Ho data available.
-------
for the same nine elements in fly ash from the ash disposal area
revealed that maximum and minimum ash concentrations of six ele-
ments exceeded their associated MATE and EPC values. Maximum and
minimum concentrations of all of these elements, except chromium,
mercury, and cadmium, were higher in separate grab sample analyses
of the three raw coals used in the Homer City Power Complex than
they were in the associated MATE or EPC values. Therefore, coal
and fly ash from a variety of sources may be contributing to the
trace element content in the sediments of the study area streams.
In spite of the toxic trace elements in its sediments, one
stream in the study area still had a good biological rating
(Table 6). The upstream portion of the south tributary to Cherry
Run had good biological quality. This stream, however, had maxi-
mum and minimum concentrations of seven elements (Pb, Cr, Mn, Ni,
Cu, Zn, and cd) that exceeded the associated MATE and EPC values.
Conclusions and Recommendations
Pollutant Toxicity Considerations
Several factors confounding pollutant toxicity evaluations
need to be considered when comparisons are made between EPC
values and field data on pollutant concentrations and biological
quality. First, the EPC values have not incorporated interactive
effects of pollutant combinations, such as synergism or antagon-
ism. (Antagonistic effects between pollutants measured in stream
water and sediments may explain how some EPC's for ecology were
exceeded in streams that had a good biological quality rating.)
786
-------
Second, EPC's and field chemical data frequently involve only
total elemental concentrations. Biota in the ambient environment,
however, may be adversely affected only by specific compounds or
ions of an element that are relatively stable in the ambient
media and not by other compounds that are included in the total
elemental concentration. To date, EPC values for inorganics have
been determined primarily for groups of compounds which have a
common parent element; comparatively few of the individual,
highly toxic compounds within these groups that are also relatively
stable in the environment have been evaluated for an EPC. Third,
some of the water quality parameters which are extremely important
in making an environmental assessment of coal-related effluents on
aquatic biota do not presently have EPC's. These master parame-
ters, including suspended solids, pH, alkalinity, etc., are
planned for future EPC evaluation.
Fugitive Dust
Elemental concentrations in fugitive dust which were measured
in the study area exceeded both EPC and MATE values for air and
soil quality. For example, three out of 15 elements analyzed in
fugitive dust had concentrations above the health-based EPC's for
air quality. Comparisons with ecology-based EPC's for air
quality, however, were very difficult because of the absence of
ten EPC values.
Although no soil concentrations were determined, comparisons
of elemental concentrations in fugitive dust were made with ecology-
787
-------
based EPC's for soil because of the potential problem of toxic ele-
ments leaching into the soil from fugitive dust laying on the
ground. Eleven of the 15 elements studied had concentrations in
the fugitive dust which were above the ecology-based EPC's for
soil. Thus, additional research needs to be conducted to deter-
mine if leaching is a problem. The existence of this type of
problem, however, seems to be inconsistent with the condition of
the vegetation in the area. In spite of the dust (particularly
coal dust) present on the ground for some distance around the coal
pile, the vegetation has not yet begun to show any obvious ad-
verse effects.
Stream Water, Sediments, and Biota
Of the 30 water quality parameters measured in streams, only
15 parameters have associated MEG values. Thus, some of the sur-
face water quality data were compared with the MEG's and some were
compared with other available criteria. The maximum and minimum
of 10 parameters exceeded the corresponding EPC's for the environ-
ment. In fact, maximum, and some minimum levels, of four pollu-
tants (ammonia, vanadium, manganese, and zinc) exceeded the appro-
priate EPC values, even in streams considered to have good biolog-
ical quality. This apparent discrepancy needs to be further eval-
uated both in terms of the validity of the proposed EPC values
used, and in terms of the interactions and uniqueness of the chem-
ical and biological conditions encountered in the study area
streams.
788
-------
Fifteen water quality parameters evaluated in Battelle's
study do not have corresponding MEG values; these parameters were
compared with criteria from the EPA (1976) and McKee and Wolf
(1963). Values for four of these parameters (pH, suspended solids,
dissolved iron, and total organic carbon) were in close agreement
with the biota quality evaluation.
Elemental concentrations in stream sediments were consider-
ably higher than the corresponding MEG values. Maximum and mini-
mum concentrations of eight elements in sediments exceeded the
associated EPC's and MATE'S for ecology. This situation occurred
for seven elements, even in a stream with good biological quality.
Again, the field situation and proposed EPC values need to be
evaluated in more detail to determine if a discrepancy exists.
Future Studies Recommended
Additional research needs to be conducted on EPC and MATE
values before they can be used to evaluate and rank pollutants
for the purpose of environmental assessment. Much of this work
was recommended in the initial MEG document (Cleland and Kings-
bury, 1977a) and is now or will soon be in progress. For example,
MEG's need to be related to the specific compounds or ionic forms
of an element which are most toxic, rather than having a single
value represent all compounds and ions which have a common "par-
ent" element. Synergistic and antagonistic effects need to be
considered because the may drastically change the hazard ranking
of a pollutant in a specific situation. MEG's are also'needed
789
-------
for many of the master parameters, such as the "totals" identi-
fied by Cleland and Kingsbury (1977a: 155} (e.g., total particu-
lates) or the water quality parameters identified in this study
(e.g., pH, suspended solids, dissovled iron, and total organic
carbon).
In another vein, the comparison of trace element concentra-
tions in fugitive dust to MEG values points out the need for lab-
oratory and field research, particularly in relation to fugitive
dust that consists predominantly of coal particles. First, the
rates at which toxic elements leach from coal dust into a variety
of soil types need to be explored. Second, the concentrations of
toxic elements present in the soil around a large, open coal pile
need to be determined when this pile has been in existence for a
long period of time. Third, laboratory bioassay and long-term
field studies need to be conducted on the effects of coal dust on
plants and animals.
It is important that the type of research necessary to improve
and expand the initial MEG approach to environmental assessment be
completed soon. Once the MEG methodology has been refined it will
become an essential part of any assessment of environmental pollu-
tion.
790
-------
REFERENCES
American Society of Agronomy and ASTM. 1965. Methods of soil
analysis. C. A. Black (Ed.), Madison, Wisconsin.
Cleland, J. G., and G. L. Kingsbury. 1977a. Multimedia environ-
mental goals for environmental assessment, Vol. 1. Prepared
for U.S. Environmental Protection Agency, Industrial Environ-
mental Research Laboratory, Research Triangle Park, North
Carolina, EPA-600/7-77-136a.
Cleland, J. G., and G. L, Kingsbury. 1977b. Multimedia environ-
mental goals for environmental assessment, Vol. II: MEG
charts and background information. Prepared for U.S. Envi-
ronmental Protection Agency, Industrial Environmental Research
Laboratory, Research Triangle Park, North Carolina, EPA-600/
7-77-136b.
Dvorak, A. J., B. G. Lewis, P. C. Chee, E. H. Dettmann, R. F.
Freeman III, R. M. Goldstein, R. R. Hinchman, J. D. Jastrow,
F. C. Kornegay, D. L. Mabes, P. A. Merry, E. D. Pentecost,
J. C. Prioleau, L. F. Soholt, W. S. Vinikour, and E. W. Wai-
bridge. 1978. Impacts of coal-fired power plants on fish,
wildlife, and their habitats. Prepared for Fish and Wildlife
Service, U.S. Department of the Interior, Washington, D.C.,
FWS/OBS-78/29.
Environmental Sciences, Inc. 1972. The environmental status of
operations at the Homer City Generating Station. Environ-
mental Sciences, Inc., Pittsburgh, Pennsylvania.
Federal Water Pollution Control Administration. 1969. Stream
pollution by coal mine drainage in Appalachia. Federal Water
Pollution Control Administration, U.S. Department of the
Interior, Cincinnati, Ohio.
Furr, A. K., T. F. Parkinson, R. A. Hinrichs, D. R. Van Campen,
C. A. Bache, W. H. Gutenmann, L. E. St. John, Jr., I. S.
Pakkala, and D. J. Lisk. 1977. National survey of elements
and radioactivity in fly ashes: absorption of elements by
cabbage grown in fly ash-soil mixtures. Environmental
Science and Technology, 11(13):1194-1201.
Hem, J. D. 1970. Study and interpretation of the chemical char-
acteristics of natural water. Water Supply Paper 1473,
U.S. Geological Survey, 363 pp.
Jackson, D. R., and A. P. Watson. 1977. Disruption of nutrient
pools and transport of heavy metals in a forested watershed
near a lead smelter. Journal of Environmental Quality
6(4) :331-338.
791
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Kerin, Z. 1975. Relationship between lead content in the soil
and in the plants contaminated by industrial emissions of
lead aerosols. Pages 487-502. In T. C. Hutchinson (Chief
Ed.), International conference on heavy metals in the environ-
ment. Vol. II, Part 2. Symposium was held in Toronto,
Ontario, Canada, October 27-31, 1975.
McKee, J. E., and H. W. Wolf. 1963. Water quality criteria, 2nd
edition. State Water Resources Control Board, Sacramento,
California.
Shannon, C. E., and W. Weaver. 1963. The mathematical theory of
communication. University of Illinois Press, Urbana, Illinois.
Stumm, W., and Morgan, J. J. 1970. Aquatic chemistry—an intro-
duction emphasizing chemical equilibria in natural waters,
John Wiley and Sons, New York, 583 pp.
Stumm, W. The chemistry of natural waters in relation to water
quality. Unpublished, 26 pp.
Stumm, W., and G. F. Lee. 1960. The chemistry of aqueous iron.
Sonderabdruck aus schweizerische zeitschrift fur hydrologie,
Birkhauser Verlag Basel, Vo. 21, Fasc. I.
U.S. Department of the Interior. 1974. Water resources data for
Pennsylvania, Part 2. Water quality records, Geological
Survey.
U.S. Environmental Protection Agency. 1976. Quality criteria for
water. U.S. Environmental Protection Agency, Washington, D.c.
U.S. Environmental Protection Agency. 1969. Chemistry laboratory
manual bottom sediments. Compiled by the Great Lakes Region
Committee on Analytical Methods.
Vaughan, B. E., K. H. Abel, D. A. Cataldo, J. M Hales, C. E. Hane,
L. A. Rancitelli, R. C. Routson, R. E. Wildung, and E. G.
Wolf. 1975. Review of potential impact on health and envi-
ronmental quality from metals entering the environment as a
result of coal utilization. Battelle Energy Program Report,
Battelle Pacific Northwest Laboratories, Richland, Washington.
Warner, R. W. 1971. Distribution of biota in a stream polluted
by acid mine drainage. Ohio J. Sci. 71(4):202-215.
Weed, C. E., and C. W. Rutschky, III. 1972. Benthic macroinver-
tebrate community structure in a stream receiving acid mine
drainage. Proc. Penn. Acad. Sci. 46:41-47.
792
-------
AN OVERVIEW OF CONTROL TECHNOLOGY
A. W. Lemraon, Jr., G. L. Robinson, and D. A; Sharp
Battelle's Columbus Laboratories
Columbus, Ohio
ABSTRACT
An important objective of coal cleaning processes is to reduce the con-
centrations of pollutants in coal prior to its utilization so that the emissions
from utilizing the coal may be reduced. Coal cleaning is an environmental
trade-off; that is, the potential pollutants are being transferred from one
segment of the environment to another. Through coal cleaning, highly mobile
air pollutants which may be discharged by the burning of raw coal may be
removed from the cycle as, for example, a solid refuse. But this solid
refuse and other wastes generated by cleaning can be important sources of
environmental contamination.
As a means of evaluating the full implications of coal cleaning tech-
niques as, for example, a combustion emission control measure, the extent
of environmental contamination resulting from coal cleaning technology appli-
cations and the control technology for this potential source of contamination
needs to be adequately assessed. This paper is a report of progress in
quantifying the potential emissions from physical coal cleaning facilities,
in evaluating the applicable pollution control technologies for minimizing
adverse effects of discharges from these facilities, and in defining and
costing these technologies. Needs for and plans for gathering further
information are also discussed.
793
-------
INTRODUCTION
An important objective of coal cleaning is to reduce the concen-
trations of pollutants in coal prior to its utilization so that the emissions
from utilizing the coal may be reduced. Coal cleaning is an environmental
trade-off; i.e., the potential pollutants are transferred from one segment
of the environment to another. Through coal cleaning, highly mobile air
pollutants which may be discharged by the burning of raw coal may be removed
from the cycle as, for example, a solid refuse. But this solid refuse and
other wastes generated by cleaning can be important sources of environmental
contamination.
As a means of evaluating the full implications of coal cleaning
techniques as, for example, a conbustion emission control measure, the
extent of environmental contamination resulting from coal cleaning technology
applications and the control technology for this potential source of contami-
nation needs to be adequately assessed. This paper is a report of progress
in quantifying the potential emissions from physical coal cleaning facilities,
in evaluating the applicable pollution control technologies for minimizing
adverse effects of discharges from these facilities, and in defining and costing
these technologies.
TYPES OF PROCESSING
AND SOURCES OF POLLUTANTS
Coal preparation plants in general include the functions of (1)
size reduction and screening (which may include some separation of impurities
794
-------
from coal), (2) separation of coal from its impurities (in a more sophisticated
manner), and (3) dewatering and drying. Table 1 shows the various unit
processes that may be employed for coal cleaning while Figure 1 depicts a
typical arrangement of unit processes that could be used in a 1000-ton/hour
cleaning plant. This figure should provide a common basis and understanding
for use in the following discussions.
Size Reduction and Screening
Size reduction and screening are basic and common to all types of
coal preparation plants. Some coal preparation plants involve only size
reduction and screening functions. A variety of comminution units, primarily
crushers and breakers, are employed for size reduction. Screens usually are
employed in conjunction with crushers to provide additional sizing of coal.
Solid waste produced from crushing nad sizing operations consists of coarse
rock and tramp iron. Typically, the amount is less than one percent of the
raw coal feed, so that, because of this >small amount, it is not a significant
disposal problem in comparison with more sophisticated processing operations.
Because crushing and sizing is usually a dry process, water pollution potential
is limited basically to surface run-off near the plant.
Crushing and sizing of dry coal can be a major source of dust
generation. As an air pollutant, coal dust can be classified into two
categories based on the particle sizes. The first category consists of
relatively large particles (plus 10-micron size range) and is primarily
responsible for the environmental hazards of impaired visibility and explosions.
These particles tend to settle quickly and thus move out of the air environ-
ment much faster than particles of smaller sizes. Furthermore, these particles
are readily suppressed by simple water spraying techniques. " Consequently,
coal dust in the plus 10-micron size range is not normally considered as a
serious environmental hazard.
The second category of coal dust consists of minus 10-micron
particles and often is defined as respirable dust. Generally, these
particles do not impair visibility, but they can be inhaled and affect human
respiratory systems. In particular, minus one-micron particles from coal
795
-------
TABLE 1. UNIT PROCESSES EMPLOYED IN
COAL CLEANING OPERATIONS
Size Reduction and Screening
Crushing
Screening
Separation of Impurities
Jigs
Dense Medium Vessels
Air Tables
Wet Concentrating Tables
Dense Medium Cyclones
Hydrocyclones
Froth Flotation
Dewatering and Drying
Mechanical Dewatering
Thermal Drying
796
-------
ROM coal
1000 tph
crushing and sizing
circuit
refuse
*• (1U tph)
VO
water
3000 gi
recycle
water
>n
wet sc
at 3/1
i
wet sc
at 28
,
hydroc>
id
water
3450 gpa
:reen *
5 In.
water
2800 gpm
.reen f
M ^
-* " i 1
* 1 1
coarse-size coal
t
refuse
(170 tph)
concentrating table mechanical
*
refuse
(50 tph)
-^
clean coal
••*• product
740 tph
thermal
drying
thickener underflow (30 tph)
FIGURE 1. FLOW DIAGRAM OF A TYPICAL CONCENTRATING TABLE AND HYDROCTCLONE
PLANT HANDLING 1000 TPH OF RAW COAL
-------
are critical with respect to human health (e.g., the inhalation of these small
particles is responsible for the occupational lung disease pneumoconiosis).
Moreover, these small particles are much more difficult to control than
larger particles. Therefore, respirable dust is the main concern in air
pollution control. Figure 2 shows the large number of respirable dust
particles which is created by coal crushing, giving an indication of the
potential for effects which may occur as a result.
Separation of Impurities
Solid Waste
Solid waste resulting from separation processes includes coarse
refuse from Jigs and dense-medium vessels; fine refuse from air tables, dense-
medium cyclones, wet concentrating tables and hydrocyclones; sludge from
water clarification circuits; magnetite from dense-medium processes (0.5 Ib/ton
of feed coal); and chemical reagents from froth flotation processes. These
processes, applied to medium and fine-sized feed coal streams, generate on
the order of 25 percent of their coal feed as waste.
Water Pollution
The consequence of wet separation of coal is the generation of
contaminated water. The characteristics of process water are highly dependent
upon the characteristics of coal being processed and the particular process
or recovery technique utilized in the operation. The principal pollutant
present in process water is suspended solids. Some minerals also are present
as dissolved solids. Among the major pollutant constituents or parameters
identified in effluents from coal preparation plants are:
Acidity or Alkalinity Total Suspended Solids
Total Iron Total Dissolved Solids
Dissolved Iron Sulfates
Ammonia.
798
-------
28,000 r—
Ji
to
M
•4-1
O
m
9)
&
u
0>
•8
M
•H
P.
CO
24,000
20,000
16,000
12,000
8,000
4,000
Particle
Size (pro)
O 0.50-1.50
1.50-2.50
-3.50
50
0.12
0.16
0.20
0.24
Size Reduction Ratio
FIGURE 2. AIRBORNE RESPIRABLE DUST GENERATION FROM COAL CRUSHING(1)
799"
-------
Process water from dense media processes may contain magnetite;
water from froth flotation operations may contain potentially toxic or noxious
chemical reagents. The quantities of water used in processing range from
180 to 1800 gallons per ton of coal processed. A major portion of the water
used in coal cleaning is recirculated.
Air Pollution
Of the separation processes, only air tables may contribute to air .
pollution. Emissions from pneumatic coal cleaning consist of particulates
only, because ambient air is used to separate coal from refuse. The quantity
and pressure of the air used depends on the size and kind of coal to be
cleaned. For pneumatic cleaning of minus 3/8-r-inch coal, an average volume
of exhaust air is about 14,100 cu ft per ton of feed coal. The exhaust
air usually picks up about 65 to 70 percent of the minus 48 mesh material
in the feed coal, and about 20 percent of minus 3/8-inch coal is smaller than
48 mesh. Therefore, the uncontrolled exhaust air contains abr at 260 to 280
pounds of dust per ton of feed coal treated or 128 to 138 grains of dust per
cubic foot.
Drying and Dewatering
Solid waste from drying and dewatering includes sludges from the
air pollution control equipment (usually scrubbers) on the thermal dryers.
These scrubbers also generate considerable amounts of contaminated water
(lesser amounts, of course, when the usual practice of recirculation is used).
Air emissions from thermal dryers include particulates from the
coal being dried and particulates in the form of fly ash from the coal-fired
furnace that supplies the drying gases. Gaseous emissions from thermal
dryers include carbon monoxide, carbon dioxide, hydrocarbons, sulfur dioxide,
and oxides of nitrogen—all furnace combustion products. Table 2 shows typical
emission ranges of some of the gaseous emissions. These are the uncontrolled
levels and no case is known in which control of S02, for example, is exercised.
Regardless, the contribution, per ton of coal, to pollutant emissions caused
800
-------
TABLE 2. GASEOUS EMISSIONS FROM THERMAL DRYERS
(2,3)
Emission Rate,
Ib/ton of Concentration,
Pollutant coal dried ppm
N02 0.2 40 to 70
S02 0.38 x (%S) 0 to 11.2
CO 0.03 50
Hydrocarbons 0.01 20 to 100
as methane
801
-------
by coal drying Is very small In comparison to the total emissions produced
subsequently during the burning of the clean coal product.
Coal Storage. Handling, and
Transportation Operations
Storage of coal is an economic necessity in coal preparation. It
provides a reserve against production interruptions and also facilitates
intermittent shipment. Coal is stored in open piles or enclosed bins and
silos. Transportation of coal from mines or preparation plants to the
point of consumption is one of the most important factors affecting coal
utilization. Transportation modes are rail, waterway, truck, pipeline,
and belt conveyor. In conjunction with the transportation and storage of
coal, a wide variety of material handling operations is needed. This includes
loading and unloading, stacking and reclaiming, and transferring coal in a
plant.
Water Pollution
Outdoor coal piles have very large surface areas, and coal residence
times in them are relatively long so that rainwater has a chance to react,
form acids, and extract sulfur compounds as well as soluble metal ions. Coal
pile leachate is generally similar to acid mine drainage. The quantity of
coal pile leachate is highly variable, both in an absolute sense and with
time. It depends upon the topography and drainage area of the coal pile
site, the configuration and the volume of the stock pile, and the type and
intensity of precipitation. Table 3 shows a typical composition of coal pile
drainage. Its composition is not much different than acid mine drainage.
Obviously, then, control and treatment of this drainage must be exercised
for proper protection of the environment to be achieved.
In addition to the coal pile leachate, accidental spills from
barge transport and coal slurry pipelines may produce serious water pollution
problems; however, no relevant quantitative data covering these situations
have been found in the literature.
802
-------
TABLE 3. TYPICAL COMPOSITION OF DRAINAGE
FROM COAL PILES<4)
Concentration, mg/1
Alkalinity (as CaCO-) 15 - 80
BOD 3-10
COD 100 - 1,000
Total solids 1,500 - 45,000
Total suspended solids 20 - 3,300
Total dissolved solids 700 - 44,000
Nitrate 0.3 - 2.3
Phosphorus 0.2 - 1.2
Total hardness (as CaC03) 130 - 1,850
Sulfate 130 - 20,000
Iron 0.4 - 2.0
PH 2.2 - 8.0
*Except pH
803
-------
Air Pollution
The principal air pollutant from storage, transportation, and
handling of coal is fugitive coal dust. This dust has the particle size
distribution characteristics shown in Table 4. The amount of dust generated
varies widely, depending on such factors as climate, topography, and
characteristics of coal, including moisture content. Thus, for example,
the handling of thermally dried coal would result in the generation of
more dust than would be generated with undried coal. It is estimated that as
much as about 80 pounds of coal per ton hauled are lost as fugitive dust
during the transport and handling operations. A dust emission factor from
coal storage piles has been estimated to be equal to approximately 0.00118
lb/ton-year (0.59 mg/kg-yr).
Coal Waste Disposal Areas
Coal refuse consists of waste coal, slate, carbonaceous and pyritic
shales, and clay associated with a coal seam. It varies considerably in
physical and chemical characteristics, depending on both its source and
the nature of the preparation process. It is estimated that about 25 percent
of raw coal mined is disposed of as waste. Over 3 billion tons of solid
waste have accumulated in the United States, and the total number of active
and abandoned coal waste dumps is estimated to be between 3000 and 5000.
About one-half of these pose some type of health, environmental, or safety
problem.
Water Pollution
The weathering and leaching of coal refuse dumps produces several
types of water pollution. These include silt, acids, and other dissolved
mineral matter. Pollution from coal waste dumps is similar to that from
surface mines; i.e., waste water from a refuse disposal area can continue
indefinitely to pollute after the disposal has ceased, and volumes of waste
water are highly dependent on precipitation and surface water flow patterns.
804
-------
TABLE 4. PARTICLE SIZE DISTRIBUTION OF
AIRBORNE COAL
Particle Mean Rate of
Radius Ratige, Particle Radius, Settling,
(pm) (ym) Weight Percent fm/sec)
< 3 2 2 0.0005
3_6 43 0.002
6-15 9 21 0.012
15-30 20 30 0.047
> 30 30 44 0.247
805
-------
Siltation from coal refuse dumps is caused by finely divided coal,
minerals, and discarded soil. Acid drainage is produced when iron sulfides
are exposed to air and water. Acid drainage is one of the most serious
water pollution problems in many parts of the U.S. In Appalachla alone,
more than 10,000 miles of streams are affected by acids from coal mines and
refuse dumps.
Air Pollution
Burning refuse piles present a difficult air pollution problem.
The oxidation of residual coal or other mineral matter in coal refuse piles
can produce sufficient heat to ignite the interior of the pile. These
burning wastes emit fumes including carbon monoxide, sulfur oxides, and
hydrocarbons. Some waste piles have been burning continuously for over
20 years, and approximately 300 coal waste piles are still burning.
CHANGES IN DISTRIBUTION OF POLLUTANTS
Recently, the fate of potentially toxic elements in coal during
coal cleaning has received special attention. Coal has been found to contain
nearly every naturally occurring element. Coal cleaning affects the distri-
bution of these elements between clean coal and refuse portions. Table 5
shows the concentrations of a few selected elements in raw coal, clean coal
at 75 percent weight recovery, and in the resulting refuse. The enrichment
factor is defined as the concentration of an element in the clean coal (or
in the refuse) divided by the concentration of the same element in raw coal.
Of 29 elements measured in this way by the Illinois State Geological Survey,
all but boron and germanium had higher concentrations in the refuse than in
the raw coal. Beryllium is distributed approximately evenly between the clean
coal and the refuse.
Reduction of trace elements is an added benefit of coal cleaning
for reducing the environmental pollution from burning coal; hwoever, the
concentration of trace elements in the solid waste may increase the potential
for environmental contamination from this source. These materials can be
806
-------
TABLE 5. ENRICHMENT FACTORS IN FLOAT-SINK SEPARATION
OF ILLINOIS COALS(6)
Element
S
As
Be
Ge
Se
Concentration
ppm (unless otherwise
Raw Coal
4.4 %
11.5
3.0
6.7
2.8
Clean Coal
1.6 %
1.5
2.9
8.1
1.3
»
stated)
Refuse
12.9 %
41.0
3.3
2.3
7.3
Enrichment Factor
Clean Coal
0.36
0.13
0.97
1.21
0.46
Refuse
2.93
3.57
1.10
0.34
2.61
807
-------
subjected to leaching by rainwater or surface flows that could produce water
pollution problems. In addition, under certain conditions, burning refuse
piles could discharge some of these elements into the atmosphere. Hence, the
environmental consequences of solid refuse disposal should be carefully
assessed.
AIR POLLUTION CONTROL TECHNIQUES
Several types of air pollution control devices are available for
application to coal cleaning operations. In choosing a particular technique
for application, the factors listed in Table 6 must be considered. The
choice of the control device depends also on the type of pollutant (particulate
or gaseous); the properties of the pollutant (such as size, density, and shape
for particulates, and equilibrium solubility, reactivity, and adsorptivity
for gases); and the properties of the conveying medium (such as density,
temperature, and velocity). Particulate control devices may be broadly classi-
fied as dry inertial collectors (gravity settling chambers and cyclones),
filters, wet scrubbers, and electrostatic precipitators. Electrostatic
precipitators are not used at coal cleaning plants because of the explosive
nature of coal-dust-air mixtures and the charged field in the precipitator.
Control devices for the removal of gases or vapors involve" adsorption or
absorption in a variety of contacting devices. Table 7 lists the mechanisms
and types of equipment in common use today for the removal of the two basic
air pollutant types.
Particulate Control Devices
Dry Inertial Collectors
Dry inertial collection systems utilize either gravitational or
inertial forces to separate the particulates from the gas stream. The collection
systems are characterized by moderate removal efficiencies, low energy require-
ments, low capital and operating costs, and an ability to accommodate high
inlet dust loadings and operate at high temperatures. For applications at
808
-------
TABLE 6. FACTORS FOR EVALUATION OF AIR POLLUTION
CONTROL TECHNIQUES
(1) Characteristics of air emissions and
operational constraints
(2) Control technology removal efficiency
(3) Capital and operating costs
(4) Disposal of wastes
TABLE 7. LISTING OF AIR POLLUTION CONTROL EQUIPMENT
Control of Particulates
Control of.
Gases and Odors
Dry Inertial Collectors
Gravity Settling Chambers
Cyclones
Fabric Filters
Electrostatic Precipitators
Wet Inertial Scrubbers
Impingement
Centrifugal
Venturi
Self-Induced
Dry Adsorbers
Wet Absorbers
809
-------
coal cleaning plants, the inertial collectors are used primarily as scalping
units or precleaners to remove the major volume of particulates from
pneumatic cleaner and thermal dryer off-gases. To meet the particulate
emission standards, the collectors are generally followed by more efficient
removal devices, such as high-energy scrubbers or filters.
Fabric Filters
Fabric or bag filters are regarded as one of the simplest and most
reliable high-efficiency dry collector devices, being capable of 99.9 percent
removal of submicron size particles. They are suitable for a wide variety
of dry particulate removal applications and, depending on the type of fabric
selected, are resistant to chemical and mechanical rigors and are operable
at moderately high temperatures.
Wet Inertial Scrubbers
Wet scrubbers or collectors utilize a liquid, generally water, to
assist in removing the dust particles from the gas stream. The major features
that make wet collectors popular dust control devices are their high removal
efficiencies, ability to remove gaseous pollutants, tolerance of moisture in
the gas, and relatively low capital costs. Disadvantages inherent with wet
collectors in general include the following: (1) the captured particulate
is in the liquid state and sometimes presents a water or waste disposal
problem, (2) the scrubber internals are subject to plugging and corrosion,
(3) the scrubbed gas is saturated with the liquid vapor, and (4) the energy
requirements for some units are high, which results in higher operating costs
than for some dry collectors. Four types of the more common types of wet
collectors used for particulate control are the impingement, centrifugal,
venturi, and self-induced spray scrubbers.
Evaluation of Particulate Collection Devices
On the basis of the characteristics outlined for the three major
emissions from coal cleaning unit operations and the performance evaluation
810
-------
of the control equipment, those equipment types most appropriate as control
equipment for each major emission may be selected. The appropriate control
selections are presented in Table 8.
Gaseous Removal and/or Collection Devices
Gaseous removal and/or collection devices are designed to extract
specific gaseous compounds from a carrier gas stream. Although not practiced
to date, the major potential application of gaseous removal devices in coal
cleaning operations is for the removal of S02 from thermal dryer off-gases.
To this end, two major types of gaseous removal processes, dry adsorption
and wet absorption, can be considered for controlling sulfur dioxide emissions.
Both processes have achieved commercial status in flue gas desulfurization
for utility and industrial boilers. They are not, however, efficient dust
removal devices, and, to meet particulate control regulations, they must be
used in conjunction with or preceded by a high-efficiency wet scrubber.
Dry Adsorbers
Removal of sulfur dioxide from flue gas or drier off-gas may be
accomplished by either molecular sieves or carbon adsorption. Unfortunately,
molecular sieves have a greater affinity for water than for S0», and since
water in flue gas or drier off-gas is present in considerably greater concen-
trations than SCL, the sieve is rendered essentially ineffective unless
preceded by a drying device, i.e., another sieve.
Wet Absorbers
Absorption is regarded as the most developed method for removing SO-
from flue gases, and, to date, several hundred various commercial-size installa-
tions have been applied worldwide to utility and industrial boilers.
Several different types of absorption equipment are utilized to
effect contact of the gas with the scrubbing slurry; some of the more common
types are spray towers, venturi scrubbers, and marble bed scrubbers. A
variety of different aqueous solutions are also utilized to capture the SO^.
811
-------
TABLE 8. SUMMARY OF APPLICATIONS FOR PARTICULATE
CONTROL EQUIPMENT
Emission Source
Typical
Characteristics of Dust
Appropriate
Control
Crushing and Sizing
Operations
Pneumatic Cleaners
Thermal Dryer
Dry, submicron up to about
6 microns In size; light
dust load, ambient temperature
Dry, submicron up to 48 mesh
in size, heavy dust load
(>100 gr/dscf), ambient
temperature
High humidity, submicron up
to about 100 microns in size,
heavy loadings up to 200 gr/
dscf, temperature 200 to 250 F.
Cloth filters or
high-energy
wet scrubbers
Primary cyclone-
cloth filter or
primary cyclone-
high-energy
wet scrubber
Primary cyclone-
high efficiency
wet scrubber
812
-------
They may be classified into four different categories: slurry solutions,
clear solutions, weak acid solutions, and organic liquids. The most developed
systems to date are those utilizing slurry solutions in spray towers or
venturi scrubbers.
WATER POLLUTION CONTROL TECHNOLOGY
Process and scrubbing water effluents from coal cleaning operations
contain two types of pollutants: suspended materials (solid or liquid) and
dissolved substances. The technology available for removing suspended
materials from the water includes mechanical dewatering, sedimentation, and
flotation. Dissolved substances can be removed from water or converted to
less objectionable forms by neutralization, adsorption, ion exchange, reverse
osmosis, freezing, or biological treatment. Table 9 lists the methodologies
currently in use or contemplated for use in treating coal cleaning wastewaters.
While all of the techniques for control of suspended materials have found
application, there is no known evidence of attempts at application of tech-
niques such as ion exchange, reverse osmosis, or freezing for control of
dissolved materials.
Control of Suspended Materials
Suspended solids may be removed from liquid streams by mechanical
dewatering methods, sedimentation, or flbtation. Each of these methods
produces a solid material which may be processed further in the coal cleaning
plant, in the case of a coal-rich material, or disposed of.as solid waste.
Mechanical Dewatering
Mechanical dewatering devices applicable for removing solid materials
from water include centrifuges and various kinds of filters. A centrifuge is
a device which rapidly rotates a solids-containing stream in order that
centrifugal force can separate the solid and liquid fractions. Vacuum filters
are used in the dewatering of fine coal products and fine refuse from wastewater.
813
-------
TABLE 9. CLASSIFICATION OF WATER TREATMENT
TECHNOLOGIES
Control of Control of
Suspended Materials Dissolved Materials
Mechanical Dewatering Neutralization
Centrifuges Adsorption
Cyclones Ion Exchange
Screens Reverse Osmosis
Filters Freezing
Sedimentation Biological Oxidation
Settling Ponds
Sedimentation Tanks (Thickeners)
Inclined Plate Settlers
Flocculation
Flotation
814
-------
Although a drum type of vacuum filter is available, the disk type has been
the traditional choice in coal cleaning plants.
Sedimentation
Sedimentation processes allow suspended materials to settle to the
bottom of a vessel and incorporate means for continually removing settled
solids and supernatant liquor separately. Systems classified under sedimen-
tation include settling ponds or lagoons and various configurations of
sedimentation tanks.
Filtration and sedimentation can be improved by the addition of
flocculants. Among commonly used additives are alum, lime, iron salts,
sulfuric acid, starches, and polymers. Although polymers are the most
expensive, on a per unit basis, they are used in very small concentrations
and work very well.
Control of Dissolved Materials
The most common pollution problem with dissolved substances in
wastewater is pH control. For coal cleaning wastewater and drainage from
coal and refuse piles, the problem is usually acidity, so an alkaline additive
is needed; lime is the preferred reagent for this purpose.
SOLID WASTE CONTROL TECHNOLOGY
Primary Problems with Refuse Disposal Areas
The major problem areas associated with land disposal of coal
cleaning refuse are fugitive dust, fire potential, erosion, and leachate
generation. Aesthetics and the ultimate use of the disposal area are generally
less difficult problems to solve.
The refuse generated by a coal preparation plant contains considerable
quantities of fine particles, leading to potentially serious fugitive dust
problems. Proper disposal site selection can be a partial solution to this
815
-------
problem. The orientation of the valley with respect to prevailing winds
should be considered. A crusting agent may be employed to prevent water
infiltration and fugitive dust from refuse piles.
Because of the considerable amount of organic matter in coal
" preparation refuse, fire resulting from spontaneous combustion in the refuse
banks is a matter of concern. Compacting the refuse piles will minimize
air circulation and reduce the likelihood of fire. In addition, sealing
the pile, either with an occasional soil covering or with a crusting agent,
also may reduce the fire potential.
Particle sizes are such that the refuse is particularly susceptible
to erosion. Diversion ditches to minimize flow of water over the refuse
surface, as well as siltation basins to capture eroded material, are essential.
The supernatant liquid (leachate) from the siltation basin should be monitored
for high pH, sulfate, calcium, total dissolved solids, and heavy metals before
being discharged to the environment. Treatment of this liquid may be necessary.
Because of the heavy metals concentrated in coal refuse, the
leachate from the refuse can be expected to be high in metal ions. This is
especially true if the leachate is acidic, as most of the metallic minerals
are quite soluble in acid.
It is possible to minimize leachate production from a disposal
facility by (1) diverting all surface drainage, (2) applying a cover material
to prevent infiltration of rainfall, (3) grading to promote rapid runoff (but
not so rapid as to create excessive erosion), (4) minimizing the open
(working) area, and (5) applying a vegetative cover upon completion of an
area. In mos.t cases, a naturally impermeable soil, or in some cases a
synthetic liner, is used to prevent infiltration of the leachate into the
ground and eventually into the groundwater.
An underdrain system is needed to gather the leachate and carry it
to a leachate treatment system. Leachate treatment will probably consist of
lime neutralization and settling. As well as improving pH, lime treatment
will remove large quantities of metal ions, which are relatively much less
soluble at higher pH levels. However, additional physical or chemical treat-
ment may be required.
816
-------
Fine Refuse Disposal
Fine refuse is considered to be refuse smaller than 28 mesh. It
occurs as the thickener underflow and may contain 75 percent moisture. There-
fore, handling of fine refuse is genera-Lly done hydraulically, by pumping
the slurry from the preparation plant to a disposal area. Direct disposal
of the fine slurry into streams is no longer practiced. Disposal of fine
refuse is now accomplished by slurry impoundment or dewatering, allowing
the resulting fine solids to be disposed of together with the coarse refuse.
POLLUTION CONTROL COSTS
ASSOCIATED WITH COAL CLEANING
With the use of proper control methods and "good housekeeping",
environmental control is technically feasible for most waste streams emanating
from coal preparation plants. However, the question is: "What is practical
and to what extent does one have to go to provide an acceptable discharge to
the environment?" Moreover, the costs of pollution control for coal preparation
(including recovery and reclamation) are frequently so great that only a
minimal effort is made to control pollution.
In the following discussion, the costs for various types of
pollution control equipment and techniques have been summarized from Battelle
cost estimates and from other sources.
Air Pollution Control Equipment
Table 10 shows the installed capital costs and operating costs
for air pollution control equipment for a hypothetical 1000 tons/hr coal
cleaning plant with the following levels of treatment.
(1) Crushing and Sizing
(2) Medium Size Coal Beneficiation With Air Tables
(3) Fine Size Coal Beneficiation With Thermal Drying
For the first two types of treatment, more than one particulate
control device is applicable; in this case, cost estimates are shown for
817
-------
TABLE 10. ESTIMATED COSTS OF AIR POLLUTION CONTROL EQUIPMENT FOR TWO TYPES
OF 1000 TPH COAL CLEANING PLANTS(7,8,9)
Plant
Type(a
Emission
Applicable
Control Equipment
Installed Cost of
Control Equipment,
Dollars (1977)/ton/hr
Annual Operating
Cost of Control
Equipment(b),
cents/ton
1,2
Dust from
crushing and
sizing operation
oo
(->
oo
Dust from air
tables operating
on medium-size
coal
Thermal dryer
off-gas
Dust enclosures
with dry bag
collectors
Dust enclosures with
high-efficiency wet
scrubbers
Primary cyclones
followed by dry
bag collectors
Primary cyclones
followed by high-
efficiency wet
scrubbers
Primary cyclones with
high-efficiency wet
scrubbers
Primary cyclones with
high-efficiency wet
scrubbers followed by
limestone scrubbing
36
20
360
200
250
9250
0.1
0.2
2.8
9.7
12.2
93.8
(a) Both plant types 1 and 2 include crushing and sizing operations and coarse (3 x 3/8 inch) coal
beneficiation by jigs or dense medium vessels. Plant type 1 includes pneumatic tables for
medium (3/8 inch x 28 M) and fine (28 M x 0) coal beneficiation. Plant type 2 includes wet
concentrating tables or dense medium cyclones for medium size coal beneficiation and hydrocyclones
or froth flotation for fine coal beneficiation.
(b) Excludes capitalization, depreciation, and interest. Based on 180 (2-shift) days.
-------
each type of treatment. For the third type, an additional cost was included
to account for flue gas desulfurization on the thermal dryer. Limestone
scrubbing was selected as the basis for the cost estimate because of its
more developed state.
To more effectively assess the environmental problems associated
with disposing of the collected particulate wastes generated from the
crushing and sizing operations, information should be obtained on the
characteristics of the wastes. Knowledge of the composition, leachability
and chemical activity of the wastes would be helpful in determining any
potential environmental complications with their disposal as well as alter-
native handling or disposal procedures.
The capital and operating cost information should be better
quantified to determine more accurately pollution control costs for different
types of plants. In addition to more accurate modular costs, information
is also needed on instrumentation and control, installation, power, and
maintenance costs.
Water Pollution Control Equipment
Table 11 shows the estimated costs of water pollution control
equipment for a hypothetical 1000 tons/hr coal cleaning plant with the
following specified processing configurations:
(1) Crushing and sizing with dry screening and wet beneficiation
(2) Medium size coal beneficiation with wet screening and wet
beneficiation.
In generating the treatment costs, it has been assumed that all
water treatment is performed to satisfy environmental constraints. Actually,
much of the treatment, particularly the dewatering treatment, is necessary
for operation of the coal cleaning processes. Thus, a portion of the costs
cited may be attributed to process requirements rather than environmental
requirements. Furthermore, since the use of closed water circuitry is a
viable alternative to treatment and release of wastewater, the water most
likely to be treated for release to the. environment is runoff and leachate
from coal storage and coal refuse piles.
819
-------
TABLE 11. ESTIMATED COSTS OF WATER POLLUTION CONTROL EQUIPMENT FOR
SELECTED 1000 TPH COAL CLEANING PLANTS <10>
Annual Operating
Installed Cost of ~~Cost of
Quantity, Applicable Control Control Equipment, Control Equipment^
Plant Type Effluent gpm Equipment 1977 dollars 1977 cents/ton'
Crushing and Process Water 3,450
Sizing with Flow-
Dry Screening Suspended Solids Radial flow thickener 345,000 0.8
and Wet lagoon, or 108,000 0.6
Beneficiation froth flotation 33,000 0.7-1.4
Dissolved Absorption-activated l,700,000^a^ 2.0
Solids carbon treatment
00
K)
Crushing and Process Water 7,650
Sizing with Flow-
Wet Screening
and Wet
Beneficiation
Fine Size Coal
Beneficiation
with Hydroclones
and Thermal
Drying
Suspended Solids
Process Water
Flow-
Suspended Solids
Mechanical dewatering-
hydroclones ,
micros creens, or
pressure filters
Thickener or
lagoon
9,250
Radial flow thickener
or lagoon
150,000
230,000
310,000
510,000
160,000
560,000
180,000
1.4
1.0
1.8
1.2
0.8
1.3
0.9
(a) Adsorption is not presently used to treat coal cleaning process water, and would not be necessary for
treating the recirculating process water for any plant with a closed water circuit.
(b) Including depreciation and Interest on capital.
-------
Much of the information presented is based on preliminary infor-
mation and estimates. Contact with plant operators and vendors can aid
in acquisition of much more detailed capital and operating costs of control
equipment, especially as applied to the specific plant types. More infor-
mation should be acquired on disposal of waste streams produced by ion
exchange and reverse osmosis treatments. The data acquisition task even-
tually will provide detailed information on performance of control equipment
and actual pollutant concentrations in raw and treated water streams. In
addition, the proportions of treated and untreated process water will be
discovered, making it possible to estimate real pollution control costs more
accurately.
Solid Waste Disposal and Reclamation
The U.S. Bureau of Mines has studied the costs to the coal industry
of refuse disposal and reclamation for nine coal waste disposal projects.
These cost estimates are the basis for the costs shown in Table 12. Waste
disposal costs are divided into those for transportation of the waste to the
disposal plant, spreading and compacting the wastes, soil covering and
planting of the disposal area, and capital costs for land, site preparation,
and operating equipment. These costs did not include the cost of installing
or operating leachate collection or surface drainage collection and treatment
facilities, which will increase the total costs.
TABLE 12. ESTIMATED COSTS OF SOLID WASTE DISPOSAL FOR TYPICAL
1000 TPH COAL CLEANING PLANT (H)
Transportation of refuse to disposal site $0.36/ton refuse
Spreading and compaction of refuse 0.17/ton refuse
Soil covering and planting 0.05/ton refuse
Capital cost 0.04/ton refuse
$0.62/ton refuse
821
-------
The costs are presented here in terns of dollars per ton of refuse.
This total compares with results of a study done by the University of Kentucky
showing coal refuse disposal costs in the range of $0.50 to $1.00 per ton.
Based on a typical coal cleaning plant, such as the concentrating table and
hydrocyclone plant shown earlier, with a rejection of 26 percent of raw coal
input, the total cost shown here amounts to $0.22 per ton of clean coal or
$0.16 per ton of raw coal input.
ACKNOWLEDGMENT
The authors wish to acknowledge the contributions made by other
Battelle staff members to this paper through their studies in these and
related areas. These staff members include S. Min, W. E. Ballantyne, and
D. W. Neuendorf. Acknowledgment also is made of the support provided by the
U.S. Environmental Protection Agency under Contract No. 68-02-2163 which made
this work possible. The Project Officer is Mr. James D. Kilgroe, Industrial
Environmental Research Laboratory, Research Triangle Park, North Carolina 27711,
822
-------
REFERENCES
(1) Kurth, D. I., Sundae, L. S., and Schultz, C. W., "Dust Generation and
Comminution of Coal", U.S. Bureau of Mines, RI 8068 (1975).
(2) Handbook of Environmental Control, Volume I, Air Pollution, Chemical
Rubber Company, Cleveland (1972), p 295.
(3) U.S. EPA, "Background Information for Standards of Performance: Coal
Preparation Plants, Volume 1, Proposed Standards", EPA 450/2-74-02/a
(October 1974).
(4) Nichols, C. R., "Development Document for Effluent Limitations
Guidelines and New Source Performance Standards for the Steam Electric
Power Generating Point Source Category", U.S. Environmental Protection
Agency, Washington, D.C. (1974).
(5) Vekris, S. L., "Dispersion of Coal Particles from Storage. Piles",
Ontario Hydro Research Quarterly, 23^ (2), pp 11-16 (1971).
(6) Gluskoter, H. J., Ruch, R. R., Miller, W. G., Cahill, R. A., Dreher,
G. B., and Kuhn, J. K., "Trace Elements in Coal", EPA-600/7-77-064,
Industrial Environmental Research Laboratory, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina (1977),
163 pp.
(7) Lund, Herbert F., Industrial Pollution Control Handbook, McGraw-Hill,
New York, New York (1971).
(8) Air Pollution Manual. Part II, American Industrial Hygiene Association,
Detroit, Michigan (1968).
(9) Zimmerman, 0. T., "Dust Collectors", Cost Engineering, January 1972,
pp 4-5.
(10) Coal Preparation, edited by J. W. Leonard, et al., Third Edition, AIME,
New York, New York (1968).
(11) U.S. Bureau of Mines, "Methods and Costs of Coal Refuse Disposal and
Reclamation", 1C 8576 (1973).
(12) Rose, J. G., et al., "Composition and Properties of Refuse from
Kentucky Coal Preparation Plants", Proceedings of the Fifth Mineral
Waste Utilization Symposium, Chicago, Illinois, U.S. Bureau of Mines
(April 1976).
823
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CHARACTERIZATION OF PREPARATION PLANT WASTEWATERS
K. B. Randolph, L. B. Kay, and R. C. Smith, Jr.
Versar, Inc.
Springfield, Virginia
ABSTRACT
During the Environmental Protection Agency's review of guidelines for
the coal mining industry, eighteen preparation plants and ancillary areas
were screened for priority pollutants as well as the classical ones. Of
these eighteen, four were examined more extensively in the "verification"
phase of the review. This paper discusses the findings of those studies.
The compositions found in the screening phase are compared with those from
the verification phase. Differences in composition among preparation plants
are compared on the basis of region, rank of coal, type of mining, cleaning
process, and plant age. By way of presenting these results, sampling and
analysis procedures are discussed.
824
-------
INTRODUCTION
In December of 1976, the Effluent Guidelines Division of the Environ-
mental Protection Agency ccranissioned a study by Versar to provide technical
assistance in reviewing the best available technology (BAT) for wastewater
pollutants from the coal mining point source category. This review resulted
from a federal court decision of June 1, 1976, which required the Agency to
perform sampling and analysis of wastewaters from 21 industries for certain
pollutants as well as classical water quality parameters. The above pollu-
tants represent 65 compounds and classes of compounds which the EPA had
failed to take into consideration in previous effluent guidelines studies.
The process of delineating specific compounds frcm these classes resulted
in a list of 129 organic compounds and metals which are tabulated in
Appendix A and have become known as the priority pollutants.
The screening sampling phase of this study was conducted during April,
May and June of 1977. Eighteen preparation plants, associated with coal
mines were visited and wastewater samples were obtained from 7 of these
facilities. In addition, wastewater samples were obtained frcm such ancillary
areas as refuse piles from 5 of these facilities.
Four coal preparation facilities currently are being examined more
.extensively during the verification phase of this review. Verification
sampling was to have been conducted this past spring. Hawever, the recent
strike by the United Mine Wbrkers of America delayed the scheduling of this
phase of the program*
In the interim, Versar has been conducting a mine drainage treat-ability
study at the Environmental Protection Agency Crown Mine Drainage Control
Field Site facility, located near Morgantown, West Virginia. The study is
designed to identify and assess control technologies to remove organic
priority pollutants found in coal mine drainage and preparation plant waste-
waters. Preliminary findings from this study are also discussed in this
paper.
825
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DISCUSSIONS CF METHODOLOGY
Site Selection
Twenty-three coal mining facilities were selected for screening sampling
by Versar in conjunction with the. Environmental Protection Agency and the
Vfeter Quality Conmittee of the National Coal Association. Facilities were
selected on the basis of region, rank of coal, type of mining and cleaning
process. Versar conducted the sampling at 22 mines. The remaining facility
was sampled by the Calspan Corporation, tail Goldberg was the first project
officer on this program, succeeded by Al Galli, who, in turn, was followed by
the current project officer, Ron Kirby. This work was under the direction of
Bill Telliard, Chief, Energy and Mining Branch, Effluent Guidelines Division,
EPA, under contracts 68-01-3273, Task 15 and 68-01-4762.
Outfall Identification
Raw wastewater and treated effluents were sampled at each facility,
where mining or preparation process design permitted. Continuous discharges
were sampled by time proportional composite. Where discharges or flows were
intermittent, because of the dry weather conditions of the spring of 1977,
grab samples were taken and composited, where possible.
Sampling Methods
Continuous discharges were composite sampled for 24 hours using an "Isco"
sampler.* Intermittent discharges were grab composited. Composite samples
were divided into 1 liter aliquots for analyses for metals, organics, pesticides,
solids, asbestos, phenols, TOC and COD. Separate samples were collected for
volatile organics and cyanide analyses. All samples were stored, preserved
and shipped according to "Satpling and Analysis Procedures for Screening of
industrial Effluents for Priority Pollutants," USEPA, EMSL, Cincinnati, Ohio
45268, April 1977. The pH was measured using an Orion or Cole Palmer pH
meter. Flow rates were determined by methods appropriate to the specific
situation.
Analytical Methods
Analyses were conducted by Versar, the EPA Region V Analytical laboratory
and two EPA analytical contractors. Versar conducted the analyses for the
* TSCO - instrumentation Specialties Company, Uncoln, Nebraska
-o2-b
-------
classical water quality parameters as well as for phenols, cyanides,
pesticides, PCBs and four priority metals: antimony, arsenic, selenium and
thallium. The remaining metals were analyzed by the EPA Region V Analytical
laboratory in Chicago. The Carborundum Corporation and Gulf South Research,
Inc., analyzed the samples for organics.
All analyses were conducted according to EPA analytical protocols.
Metals were analyzed by plasma source atonic absorption spectrophotcmetry.
Organic compounds were identified using gas chromatography/mass spectroscopy
(GC/MS).
RESULTS AND DISCUSSION
The results of the screening phase of this program are presented in
two parts: metals and organics. These parts are further broken down into
waters from preparation plants and water fron associated areas, i.e., refuse
and storage piles. These results are further subdivided and regrouped by
the mine type (surface or deep), the mine water (acid or alkaline), type of
processing (water only, heavy media and flotation), geographical location
and water treatment process. These results are discussed as they are pre-
sented.
Since these are the results of the screening phase, they are somewhat
preliminary in nature in that they have not been verified by more extensive
sampling. Furthermore, the coal mining industry was the first to be sampled
under the BAT review, and thus was the first industry to be sampled for many
of these parameters. This is especially important in considering the organic
priority pollutants.
In the following, the terms acid preparation plant and alkaline prepara-
tion plant are used. These refer to the type of drainage associated with
the mine that supplies the coal to the plant and not necessarily to the
water frcm the plant itself. However, preparation plants in the acid group
do have generally lower pH waters than those in the alkaline group - 3.8 vs.
7.0.
827
-------
Priority Metals
Table 1 shows that virtually all priority metals (except silver) were
found in the wastewaters from acid plants. This nay be contrasted with the
results for alkaline plants shown in Table 2. In the acid case, three
metals were found in all streams, and four metals were found in eight of the
nine streams. However, in the alkaline case, no metal was found in all
streams, and only the "ubiquitous" iron was found in all but one stream.
Only for one metal, chronium, was the highest concentration found in an
alkaline plant. Clearly then, the waters associated with preparation plants
processing coal from alkaline mines are "cleaner" than waters from those
plants cleaning coal from acid mines.
The kind of stream that produces the highest concentration of these
metals is shown in Table 3 for each priority metal. Note that the high
concentrations occur in three streams out of the nine satpled. These are:
(1) A refuse slurry from an anthracite breaker,
(2) A grab sample taken fron a drag tank,
(3) A very acid, old, strip pit used for a recycle pond.
In two of these cases samples were taken of the same waters after treat-
ment. These treated values are shown in Table 4 along with the percent
reduction in concentration.
In the first case, the anthracite breaker, the treatment consisted of a
series of three settling ponds. The first two were divided by a baffle dan
constructed of refuse. The second of these emptied, by means of an asbestos
pipe, into a third pond.
The second case, the drag tank water, occnbines with other circuits in
the prep plant and flows to a slurry pond from where it is recycle to the
process.
The third case, the very acid pond, is unique. This was a non-
discharging pond which was an old acid strip pit. This water was so acid,
pH 2.9, that it had to be neutralized before reuse. This was accomplished
by injecting anhydrous arnnonia in the recycle line. This line could not be
sampled readily to assess the effectiveness of the treatment, however, the
treatment may account for the high levels of nickel and zinc as the ammonium
828
-------
TABLE 1
ACID PREPARATION PLANTS, PRIORITY METALS FREQUENCY AND RANGE
Metal
Antimony
Arsenic
Beryllium
Cadmium
Chronium
Copper
Iron*
Lead
Manganese*
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Cyanides
Phenols
Frequency
(9 Streams)
8
9
2
1
5
8
9
4
9
6
3
8
0
6
8
0
1
Range,
Low
0.001
0.002
0.007
0.036
0.03
0.098
0.067
0.025
0.0003
0.095
0.005
0.001
0.039
___
(mg/1)
High
0.021
1.23
0.02
0.032
0.44
0.72
3,000
0.76
39
0.0075
0.92
0.41
0.070
1.37
0.025
Detectability
Limit, (mg/1)
0.001
0.001
0.002
0.02
0.024
0.004
0.02
0.06
0.01
0.0001
0.05
0.006
0.025
0.001
0.025
0.005
0.02
* Not on the priority pollutant list but one on which the industry
is regulated
829
-------
TABLE 2
ALKALINE PREPARATION PLANTS, PRIORITY METALS FREQUENCY AND RANGE
Metal
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Iron*
Lead
Manganese*
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Cyanides
Phenols
Frequency
(10 Streams
5
7
0
0
5
3
9
0
8
6
1
4
0
4
8
0
1
Range, (mg/1)
low High.
0.002
0.002
0.001
0.026
0.007
0.045
0.033 2.0
0.005 0.27
0.161 200
0.024 2.0
0.0004 0.002
0.53
0.002 0.05
0.004
1.0
0.035
Detectability
Limits, (mg/1)
0.001
0.001
0.002
0.02
0.024
0.004
0.02
0.06
0.01
0.0001
0.05
0.001
0.025
0.001
0.025
0.005
0.02
* Not on the priority pollutant list, but one on which the industry
is regulated
830
-------
TABLE 3
SOURCE OF ACID PREPARATION PLANT MAXIMUM CCNCENTRATIONS
Maximum
Metai uoncenrra'cion
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Cyanides
Phenols
0.02
1.23
0.02
0.032
0.44
0.72
3,000
0.76
39
0.0075
0.92
0.41
0.07
1.37
0.025
Stream Description
Prep plant drag tank, grab sample, total metal
Anthracite refuse slurry, total metal
Slurry to thickener grab sample
Very acid recycle pond (pH 2.9), actually
an old strip pit
Drag tank, grab sample
Anthracite refuse slurry
Drag tank
Anthracite refuse slurry
Very acid recycle pond (pH 2.9)
Anthracite refuse slurry
Very acid recycle pond
Anthracite refuse slurry
None detected
Drag tank grab sample
Very acid recycle pond
None detected
Anthracite refuse slurry
831
-------
TABLE 4
Metal
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
Iron
lead
Manganese
Mercury
Nickel
Selenium
Thallium
Zinc
iar.CMflt.-r CP ISEMMENT ON HIQ
Concentration, (mg/1)
Raw
0.021
1.23
0.02
0.032
0.44
0.72
3,000
0.76
39
0.0075
0.92
0.41
0.070
1.37
Treated
0.001
0.004
(a)
(b)
0.036
0.044
0.183
<0.06
(b)
0.0016
(b)
<0.006
<0.001
(b)
Reduction
(percent)
95.4
99.7
91.8
93.9
99.994
>99.9
78.7
>98.5
>98.6
(a) Treated water not sampled
(b) Closed circuit, pond does not discharge
832
-------
complexes. (The latter has not been verified by any analyses and is offered
only as a possible explanation.)
The extraordinary effectiveness of settling in these two cases leads to
the conclusion that the priority metals are associated primarily with the
solid phase in these slurries. Since the analyses performed were for total
metals, as is called for in the protocol, this is not surprising. This also
explains why most of the high values for metals were found in slurry streams.
Further breakdowns of these results by type of process, geographical
location, and type of mining are shown in Tables 5, 6 and 7. The upshot
of these tabulations is that the single most iitportant difference is whether
the coal comes from an acid or alkaline region. The greater frequency of
priority metals and the higher concentrations in Iforthem Appalachia is
because this is an acid area.
Organic Compounds in Preparation Plant Waters
The organic priority pollutants found in waters from preparation plants
and associated areas are shown in Table 8. Fourteen compounds on the
priority pollutant list were found above detectable limits. Some of these
were found frequently and some only once.
These results should be viewed skeptically since the coal mining industry
was the first industry to be screened for the priority pollutants. Many
lessons were learned in the process, and these are being applied to the
treatability studies and the verification sampling underway at present.
They have been a most useful guide.
The prevalence of organic pollutants was examined from the standpoint
of industry characteristics. These were: type of mine drainage (acid or
alkaline), type of mining (surface or deep), type of process (water only,
heavy media and flotation), and geographical location (Central, Northern
Appalachia, Southern Appalachia). The data base was not sufficient to
categorize the industry by ooal seam or coal rank.
No clear pattern was discernible in these classifications except,
perhaps, that preparation plants and associated areas in the Central Region
have a more frequent occurrence of organic pollutants.
833
-------
TABLE 5
COMPARISON OF PREPARATION PLANT WASTEJ&TERS BY PROCESS TYPE
HEAVY MEDIA AM)
FROTH FLOTATION
WATER ONLY
Metal
Antimony
Arsenic
Beryllium
Cadmium
Chronium
'Copper
Iron*
Lead
Manganese*
Mercury
Nickel
Selenium
Silver
thallium
Zinc
Cyanides
Phenols
Frequency Range ftng/1) Frequency Range
(10 Streams) Lew High (8 Streams) Low
4
7
0
0
3
5
10
1
10
6
2
2
0
3
7
0
2
0.001
0.002
—
0.024
0.004
0.098
0.01
0.0001
0.05
0.001
0.001
0.025
0.02
0.003
1.23
.
2.0
0.72
210.0
0.76
20.0
0.0075
0.53
0.41
0.009
1.0
0.035
5
8
1
1
7
6
7
3
8
5
2
4
0
4
8
0
0
0.001
0.005
0.033
0.044
0.02
0.06
0.025
0.0001
0.05
0.003
0.001
0.031
___
___
tog/1)
High
0.021
0.17
0.007
0.032
0.44
0.21
3,000
0.167
39.0
0.0008
0.921
0.16
0.070
1.37
—
-,-.„
* Nat on the priority pollutant list, but one on which the industry
is regulated
834
-------
TABLE 6
COMPARISON OF PREPARATION PLANTS AND ASSOCIATED AREAS BY REGION
Metal
Antimony
Arsenic
Beryllium
Cadmium
Chromium
Copper
oo Iron*
" Lead
Manganese*
Mercury
Nickel
Selenium
Silver
thallium
Zinc
Cyanide
Phenols
N. Appalachian and
Ohio Region
Frequency
(10 Streams)
6
10
1
0
6
9
10
4
10
7
4
8
0
5
9
0
1
Range
Low High
0.001 0.028
0.003 1.34
0.22
-
0.024 0.98
0.004 1.0
0.098 9000.
0.06 1.0
0.025 80.0
0.001 0.0075
0.05 10.0
0.005 0.45
_
0.001 0.07
0.025 30.0
_ _
0.025
S. Appalachian Region
Range
Frequency
(8 Streams)
8
0
0
1
2
8
0
7
7
1
6
0
2
3
0
3
Low
0.001
0.002
-
-
-
0.004
0.103
-
0.024
0.001
-
0.001
-
0.002
0.037
-
0.030
High
0.003
0.045
-
-
2.0
0.006
9.0
-
2.09
0.0048
0.53
0.004
-
0.003
0.168
-
0.035
Central Region
Range
Frequency Low
(5 Streams)
5 0.002
5 0.005
1
1
3
2
4
1
4
4
1
3 0.003
0
1
5 0.029
0
0
High
0.007
0.028
0.007
0.032
0.115
0.056
7.63
0.167
39.0
0.0007
0.921
0.005
—
0.004
1.37
—
* Not on the priority pollutant list, but one on which the industry is regulated
-------
TABLE 7
CQMPARISCN OF PREPARATION PLANTS BY TXPE OF MINING
Surface Mines
Deep Mines
Metal
Antimony
Arsenic
Eery Ilium
Cadmium
Chranium
Copper
Iron*
Lead
Manganese*
Mercury
Nickel
Selenium
Silver
Thallium
Zinc
Cyanides
Phenols
Frequency Range (mg/1)
(9 stream*! Low ^4"
7
9
1
1
6
6
8
3
9
7
4
3
0
3
8
0
1
0.001
0.002
—
0.024
0.004
0.02
0.06
0.046
0.0001
0.05
0.001
—
0.001
0.029
-_
___
0.021
1.23
0.007
0.032
2.0
0.72
3,000
0.76
39.0
0.0075
0.921
0.41
—
0.070
1.37
___
0.025
Frequency Range (mg/1)
(11 Streams) Low Hiqh
4
11
1
0
5
5
11
1
10
6
2
3
0
4
8
0
1
0.001
0.002
0.024
0.004
0.098
0.01
0.0001
0.05
0.001
0.001
0.025
___
0.008
0.17
0.02
2.0
0.27
200
0.067
6.32
0.0009
0.095
0.16
—
0.039
1.0
—
0.035
* Ifot on the priority pollutant list, but one on which the industry
is regulated
836
-------
TABLE 8
OCCURRENCE OF ORGANIC PRIORITY POLLUTANTS IN COAL
PREPARATION PLANTS AND ASSOCIATED AREAS
vxii^Uunu rZaCjU
itethylene chloride
chloroform
1 , 1 , 1 ,- trichloroethane
trana-dichloroethene
tetrachloroethene
trichlorofluoromethane
chlorobenzene
2,6-dinitrotoluene
benzene
toluene
ethylbenzene
anthraoane/phenanthrene*
diethyl phthalate
di-n-butyl. phthalate
bis(2-ethylhexyl) phthala.te
sncy UJ. streams;
21
17
5
7
7
2
1
1
9
11
1
1
2
4
11
Conoentraticn Range (yg/1)
Low High
2.6 66,000
1.6 476
1.4 2
1.4 10
1.4 20
14 22
12
30
0.3 48
0.3 30
>0.2
20
110 790
210 630
10 6,100
* Analytical method (GC/MS) cannot distinguish between these two compounds.
837
-------
TABLE 9
FREQUENCY & RANGE OF ORGANIC PRIORITY POLLUTANTS IN
PREP. PLANTS AND ASSOCIATED AREAS
COMPOUND
methylene chloride
chloroform
1,1,1-trichloroethane
trans -dichloroethene
tetrachloroethene
trichloroflinrcmsthane
chlorobenzene
2,6-dLnitrotoluene
benzene
toluene
ethylbenzene
anthracene/phenanthrenei
diethyl phthalate
di-n-butyl phthalate
bis (2-ethylhexyl)
phthalate
FREQUENCY
Prep Plants
nt ft OTJ-L . mn \
114 streams;
14
13
4
5
6
1
1
5
6
1
1
2
3
9
Asaoc. Areas
CJ Streams)
7
4
1
2
1
1
1
0
4
5
0
0
0
1
2
CONCENTRATIGN RANC£ (UQ/D
Prep Plants.
Lew High
2.6 20,000
1.6 152
1.4 2
1.4 10
1.4 20
14
30
0.3 12
0.3 5.1
>0.2
20
110 790
270 630
13 1,200
Asaoc. Areas
Low High
348 66 ,000
19 476
1.7
1.7 1.0
1.2
22
12
- -
6.3 48
2.0 30
-
-
_
210
10 6,100
*The analytical method (GC/toS)cannot distinguish between these two compounds.
838
-------
TABLE 10
FREQUENCE OF OEGANICS BY SUBCATEGOFY
oo
w
\o
Compound
methylene chloride
chloroform
1,1,1-txichloroethane
trans-dichloroethene
tetrachloroethene
benzene
toluene
di-ethyl phthalate
di-n-butyl phthalate
bis(2-ethylhexyl) phthalate
Octal Number
Nm±ier per Stream
TKPE CF MINING
Deep
(7 Streams)
7
7
3
4
2
2
2
2*
2*
5*
36
5.14
Surface
(7 Streams)
7
6
1
1
4
3
4
0
1
4
31
4.43
Central
(4)
4
4
2
2
3
3
3
1
2
4
28
7.00
GEOGRAPHICAL REGION
No. Appal.
(7)
7
6
1
2
2
1
2
1*
0*
3*
25
3.57
So. Appal.
(3)
3
3
1
1
1
1
1
0
1
2
14
4.67
TYPE DRAINAGE;
Acid
(8)
8
7
1
2
3
2
3
1*
1*
4*
32
4.00
Alka-
line
(6)
6
6
3
3
3
3
3
1
2
5
35
5.83
* Cnly six streams available because of loss of sample in shipment
-------
Treatability Studies
The prevalence of organic priority pollutants in coal mine drainage
and preparation plant wastewaters formed the impetus for the treatability
studies currently underway at the Environmental Protection Agency's Crown
Mine Drainage Control Site near Morgantown, West Virginia. The objectives
of this study are to:
1. demonstrate the effectiveness of the treatment currently in use
(HPT) for removal of certain organic priority pollutants, and
2. determine the effectiveness of, including costs, additional
treatments to further reduce organic pollutant concentrations.
Objective one has been virtually attained, and objective two should be
achieved by the end of September. Sane preliminary results concerned with
the effectiveness of HPT will be presented here.
Without going into the details or the rationale for selecting the
compounds to study, the selected priority pollutants are shown in Table 11.
In the studies of acid mine drainage, water was obtained from the mine
that had been the source of water for other studies at Crown Field Site.
However, this mine had been closed for sane six to seven months prior to this
study. During that time some changes in composition of the water had
occurred, but the water remained acid and ferruginous. On. pumping the mine
no organic pollutants were found. Consequently the selected pollutants
were spiked into the water at the approximate concentrations shown in Table
11.
The spiked acid water was then treated by lime neutralization followed
by aeration, flocculation, and settling in that order. The effect of this
treatment on the volatiles is shown in Table 12. As can be seen, the
removal of volatiles is quite complete. This reduction could be accounted
for primarily by the aeration step.
To determine if aeration was causing an air pollution problem or a
hazard to personnel in the plant, the air over the aerator (~6 ft. above
the water's surface) was monitored using a "Sipin"* pump. Analyses of the
* Sipin - Anatole J. Sipin Company, 425 Park Avenue, South, New York,
New York 10016
840
-------
TABLE 11
SPIKEN3 CONCENTRATIONS OF SELECTED OK3ANIC POLLUTANTS
IN ACID MINE DRAINAGE
Conpound Concentration (yg/1)
benzene 55
toluene 35
methylene chloride 250
chlorofbm 250
trans-^chloroethene 10
l,lfl-trichloroethane 10
tetrachloroethene 30
bis(2-ethylhexyl) phthalate 10,000
di-n-butyl phthalate 1,400
-------
TABLE 12
EFFECTIVENESS OF VOLATILE ORGANIC REMOVAL
""^^^-^^..^StaMam
Parameter ^"'^'^^-'^^^..^^^
methylene chloride
trana-dichloroethene
chloroform
1,1, 1-trichloroethane
benzene
tetrachloroethene
toluene
Feed
(rag)
87,24
3.48
87.24
3.48
19.53
10.48
12.23
Average
Effluent
-------
samples thus obtained revealed very little in the way of pollutants in the
air, as is seen in Table 13. At no time did any concentration even approach
the eight hour TLV.
The effect of BPT on the two phthalate esters has not been assessed as
yet. A conplication developed in reducing the data when a discrepancy in
solubilities became evident, i.e., the solubilities found in OIMTADS for these
compounds are three orders of magnitude too high.
In addition to acid drainage, alkaline drainage is under study too.
The source of water for this is a creek that runs through Crown Field Site,
Indian Creek. This creek has a pH of about 7.5 to 7.8, and the total sus-
pended solids varies fron about 10 mg/1 to 300 mg/1 depending on rainfall.
This water is pumped to the plant and spiked with the organics. However,
in the light of the new solubility data, the composition was changed so that
the phthalate concentrations were reduced to 450 yg/1 each.
This alkaline water received BPT treatment consisting of settling in the
clarifier. In addition, several runs were made where the spiked creek water
received aeration before going to the clarifier.
Preliminary work-ups of the data show that aeration was as effective
at removing volatiles as in the case of acid water. The results so far on
settling only in a clarifier indicate that about 65 to 75 percent of the
volatiles are removed.
Analyses of the phthalates are not complete enough at this time to
assess any effect of BPT.
At this writing, experiments are going on with reduction of priority
metals in alkaline water, on ozonation to remove organics, and on carbon
adsorption to remove organics. Once these studies are completed, a more
exhaustive discussion of the treatability of coal mine drainage and prepa-
ration plant wastewater will be published. Furthermore, this will have
the back-up of the verification phase of the sampling study. At that stage
an assessment of loads to the environment can be made with some certainty,
and the economic impact of any treatment can be determined.
843
-------
TABLE 13
AIR SM4PLES (Sipin Pimp)
Average Daily Ctganic Ooncsentrations (PPM) Period 5/23 - 6/5/78
Sample
location
Plant Aerator
Plant Clarifier
Chemistry
Laboratory
(Jim Kennedy)
Office -
Receptionist Desk
Control -
Bathroom in
Back Office
Threshold Limit1
Values Time-
Weighted Average
(S^iour workday)
1,2-trans
dichloro- chloroform
ethene
It) 0.126
ND 0.016
ND 0.021
0.071 0.024
0.067 ND
200 25
1 these TLV's represent the time-weighted average
workweek, to which normal Iv all workers mav be i
1,1,1-
txichloro-
ethane
0.007
0.021
0.010
0.012
0.009
10
Teneatedlv en
tetra-
benzene chloro—
ethylene
0.021 0.031
0.013 0.066
0.024 0.038
0.009 0.054
0.010 0.023
1.0 100
i for a normal 8-hour workday
aosed, day after day. without
toluene
0.073
0.053
0.018
0.045
0.021
100
or 40-hour
adverse effect.
ND = Not Detectable
-------
APPENDIX A
LIST OF PRIORITY POLLUTANTS
845
-------
Prioritv Pollutants
acer.apthene
acrolein
acrylonitrile
benzene
bensidene
carbon tetrachloride (tetrachloro-
raethane)
chlorobenzene
1,2,4-trichlorobenzene
hexachlorobenzene
1,2-dichloroethane
1,lf1-trichloroethane
hexachlorocthane
1,1-dichloroethane
1,1,2-trichloroethane
1,1,2,2-tetrachloroethane
chloroethane
bis(chloronethyl)ether
bis(2-chloroethyl) ether
2-chloroethyl vin^l ether (nixed)
2-chloronapthalenb
2,4,6-trichlorophenol
parachlorometa cresol
chloroform (trichlormethane)
2-chlorophenol
If 2-dichloroben2ene
1, 3-dichlorobenzene
1,4-rtichlorobenzene
3,3l -fiichlorobenzidir.e
1,1-dichloroethylene
2,4-dichlorophenol
1,2-dichloronropane
1,2-dichloropronylene (1,3-cl.tchloro-
propene)
2,4-dineth«lphenol
2,4-dinitrotoluene
2,6-dinitrotoluene
1, S-cliphejiylhyrirasine
ethylbenzene
fluoranthene
4-chloroohenyl phen^'l ether
4-brcnoohenyl phenyl ether
bis ( 2-chloroiaor5ropyl ) ether
bis ( 2-chloroetho::") " methane
nethylenc chloride (dichloro-
nethane)
nethyl chloride (chlorcne thane)
methyl bronide (brononethane)
br onofom ( tr .D^r ononethane )
clichlorobrmonethnne
tr5.chlorof luoronethane
dichloroclifluoronethane
chlorodibrononethane
hexachlorocyclor>entadiene
isophorone
2 -n i tr or>heno 1
4 -n i tr onhenol
4 , 6-dinitro-o-crascl
7 J-n i trosocline thylaninc
N-n i tro sodiphenyl anine
>7-nitrosocli-n-iron«lanire
pentachlorophenol
phenol
bis (2-eth"lh«cyl) phthalate
but^'l bensyl phthalnte
di-n-hutyl nhthalate
di-n-oct-'l phthal«te
cl iethy 1 nhtfinl n to
dineth^l* phth?».late
Ixsnzo (a) anthracene ( 1 , 2-N».n
benrto (n) pyrene ( 3 , A-
pyrene)
3 , "^-benr.
benno (!') f lnoranthenn
(11 ,12-benso*
chrvsene
acena^hth^l ere
846
-------
anthracene
benzo (ghi) perylene (1 , 3.2-ben-
zoperylone)
fluorenc
phenantl irene
dibenso (a r h) anthracene (1 , 2 , £ , f
dibensantliraceiie)
indano ( 1 , 2 , 3-c«l) pyreno
(2 , 3-o-plienylenepi»rene)
pyrene
tetrachloroethylene
toluene
trichloroethylene
vinyl chloride (chloroethylene)
ale* r in
dieltirin
chlordane
4 , 4l -DT?
a-enclosulfan-Alpha
L-endosulfan-Beta
enuosulfan sulfnte
endrin
enurin aldehyde
heptaclilor
heptachlor epo::ide
a-DHC-Aloha
b-BIIC-Beta
r-BHC- (lindane) -r.anma
g-DHC-Delta
PCB-1242 (Arochlor 1242)
PCB-1254 (Arochlor 1254)
(Arochlor
PCB-1232 (ArocMor
?*cr,-12/in (Arochlor
PCB-1260 (Arochlor
rcn-niG (Aroohlor
to::aphone
antir^ony (total)
arsenic (total)
asbestos (fibrous)
beryllinn (total)
cadfdun (total)
cluroniun (total)
copper (total)
cyanide (total)
leatl (tct.-\l)
nercur»' (total)
nickel (total)
neleniun (total)
iiilver (total)
tlialliun (tot».l)
zinc (total)
122?.)
1232)
847
-------
APPENDIX B
ANALYTICAL RESULTS
CLASSICS AND METALS
848
-------
Prep Plant
Drag TS/Jc
few Water
1bt*1 . 7,800
total Sk-^*tod Solids ^
total volatile Solids
Volatile Suspended Solids — j-^j
cm
-== — 1.130
(Slurry Fond
JEfflumt
I 1,100
7.4
j 150
Prep. Plant
Raw Kal/?r
38,000
37,000
28,000
3.6 j 28,000
20.6 14,700
j 3.2 1.100
— : - 6.78 I 8.20 4.2
_J= i
MOMS (HA) ~~300T» L 0 099
Ucsrim — r """.'
' 0.021
Antiacny
— ~* - 0.065
Arsenic .._
Baziui
< 0.02
Berylliw
< O.ObO
CMfcdUB * Q"*°
• 268
— — — — — 0.44
,^J1(" < 0.10
, 6.21
Cbpper
iron J000-"
Lead 'O-60
HUT*-*— *"**
t| a |IU ' 0.12
0.03 Q
0.183 ,
0.067 j
55.9
210
0
.72
.76
8.0
Sot?- -Q
JVyid
240
11.8
220
2.4
27.2
9.2
4.4
1.76
<0.001 J
0.004 j
0.149 J
<0.002
0.014
<0.02
26.5
<0.024 '
0.1 Id
0.044
0.803
<0.06
10.3
°-025 20JO 3.870
<0.0001 . 0
0.03
< 0.05
0.012
< 0.025
44.5
0
<0
0075J 0.0016
16 1 <0.01
1.5
0.41
<0.25
13.
< 0.001 0
< 0.099 , <0
< 0.01 j o
< 0.099 , <0.
< 0.01 <0.
0.039 ' 0.
0
009
99
12
99
1
48
< 0.005 ,
-------
CLASSICAL PARAtOEBS ta/1)
Ibfcal Solids
\ Total Suspended Solids
total Volatile Solids
Volatile Suspended Solids
ODD
. TOC\
CB '
M2rALS tug/1)
Ali-4num
Antuccny
Arsenic \
Barium .v
BexvUiin A
Boron '
Cadnium '
, Calciua Y
\ji Chrcnium \
f"' -Cobalt . \
Dapper \
..Iron '
Lead ''•
Magnesium
Manganese
Mercury
fblybderan
Nickel
SeleniiD
Silver
Sodium
Uiallim'
Tin
Titanium
Vonadiun
Yttrium
Zinc
Cyanide
Phenol
PRH> PLANT
RECYCLE
POD
2200
8.0
220
1.6
11.6
<1.0
6.4
<0.099
0.004
0.005
<0.005
"Q.002
o.2n
40.02
336
0.033
<0.01
0.007
<0.02
<0.06
V54.4
0.147
-fc.oooi :
•fl.Ol
<0.05
0.004
<0.025
134
<0.001
<0.099
<0.01
<0.099
0.013
0.031 .
0.005
<0.02
f/C-S
'Slurry 1
Pond
Etnuent
3700
11.8"
420
4.8
37.1
16.2
7.0
<0.099
0.001
0.030
0.025
<0.002
0.085
<0.02
175
0.036
<0.10
0.030
0.188
0.067
55.9
0.025
<0.0001
0.030
<0.05
0.019
<0.025
44.5
0.002
<0.099
<0.010
<0.099
<0.010
0.039
<0.005
<0.02
J.I X XU
73r
.
Slinry
Pond
Effluent
1200 >
5.4
100
1.8
<2.0
<1.0
9.0
<0.099
0.002
0.014
0.035
<0.002
0.261
<0.02
64.1
<0.024
<0.01
<0.004
0.271
' <0.06
29.1
0,064
0.0006 -
0.041
<0.05
<0.001
<0.025
226
^ 0.001
<0.099
0.011
<0.099
<0.01
0.029
<0.005
<0.02
*-T
,
|
Prep.Plant
Recycle
Pond •*
2750
2.2
460
<1.0
4.0
<1.0
2.9
10.0 i
0.005
0.008
<0.005
• 0.007
0.072
0.032
0.254
0.115
0.356
0.056 !
7.63
0.167
0.140
39.6 '
0.0007 :
0.028 !
0.921
0.005
<0.025
43.3
0.001
<0.099 '
<0.01
<0.099
0.140
1.37
<0.005
<0.02
+ 1
Recycle Pone
850
4.0"
38
1.6
4.0
2.0
8.1
-
, <0.099
0.002 !
0.008
0.025
<0.002
0.055
<0.02
55.3
<0.024
<0.01
<0.004
0.181
<0.06
15.8
, <0.01
0.0004
0:029
<0.05
<0.001
<0.025
163
<0.001
<0.099
0.016
<0.099
<0.01
0.093
<0.005
<0.02
Prep.Plant
Recycle
Pond
680
50
100
5.6
23.3
<1.0
7.2
<0.99
<0.001
0.002
0.11
<0.02
0.09
<0.2
35.0
2.0
<0.1
<0.04
9.0
<0.6
16.0
0.37
0.0009
<0.1
0.53
<0.-001
<0.25
67.0
•cO.OOl
<0.99 .
<0.1
<0.99 .
-------
OASSICM. PARMdHB faq/1)
Total Solids _ '
•total asperated Solids
•total Volatile Solids
Suspended Solids
ODD
TOC
(mg/l)
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
OO
U1
I-"
f^ilrrliwn
Cbbalt
Copper
Iron
Lead
Magnesium
tenganese
Mercury
tfalybdenum
Nickel
Selenium
Silver
Sodtin
Thallium
Tin
Titanium'
Vanadium
Yttrium
Zinc
Cyanide
Phenols
Asbestos (fibers/1)
Refuse
Pile Raw
Hater
410
11.4
34
2.2
15.5
3.6
4.0
1.47
0.002
0.003
0.127
<0.002
0.024
<0.02
1
Rafuse'
Pile
Treated
Effluent
260 '
62
36
19.6
29.1
5.5
9.7
<0.99
0.002
0.004
0.17
<0.02
0.11
<0.2
26.5 8.0
<0.024
0.038
0.006
0.509
<0.06
15.5
2.09
0.0048
<0.01
<0.05
0.003
<0.025
38.8
<0.001
<0.099
0.014
<0.099
<0.01
0.168
<0.005
<0.02 j
<0.24
<0.1
<0.04
1.0
<0.6
3.0
<0.2
0.0043
<0.1
<0.5
0.004
<0.250
65.0'.
<0.001
!<0.99
<0.1
-------
APPENDIX C
ANALYTICAL RESULTS
OBGANICS
852
-------
oo
01
u>
Priority Pollutants, pq/1
benzene
chlorcbenzene
1 , 2-dichloroethane
1,1, 1-trichloroethane
1,1,2,2-tetxachloroethene
chlcrofom (trichloranethane)
1 , 2-trans-dichloroethylene
2 ,6-dinitrotoluene
ethylbenzene
netnylene chloride
tridilcxofluoronethane
toluene
bis(2-ethylhexyl) phthalate
di-n-butyl phthalate
dietnyl phthalate
anthracene
ohenanthrene
DRAG TANK
RAH HVRR
1
ND
ND
ND
ND
ID
10
ND
30
ND
- 930
ND
ND
ND
ND
ND
20*
20*
/V
SLURRY
POND
EFFLUENT
ND
ND
ND
ND
ND
ND
ND
ND
ND
1800
ND
ND
ND
ND
ND
ND
ND
Prep
Plant
Slurry
ND
ND
ND
ND
ND
29
ND
ND
ND
199
ND
ND
ND
ND
ND
ND
ND
Settling
Pond
Effluent
ND
ND
ND
ND
>11
>10
ND
ND
>0.2
1,700
ID
>4.2
330
ND
ND
ND
ND
Prep
Plant
Slurry*
Slurry
Pond
Effluent*
Clear Lake
Prep
Plant
Recycle*
--M, V/ MC.~3
•Method does not distinguish between these oaqpounds
-------
oo
Ul
*eW7ZH/ ftLftfFS
Priority Pollutants, pg/1
benzene
Peep
Plant
Recycle
Pond
0.3
chlordbenzene MD
1,2-dichloroethane
l,lfl-trichlocoethane
ND
ND
1,1,2,2-tetrachlOToethene l-*
chloroform (tricfaXorcrethaiie)
1,2-trans-dichloroetiiylene
2 6— dinitrotoluene
5.0
ND
ND
ethylbenzene
nethylene chloride
hr 1 r+ilorof luarcnetha*>e **
toluene
bia(2-ethylhexYl) phthalate 200
di-n-butyl phthalate ND
diethyl rfithalate ND
.henanthrene
j ND
ND
Slurry
Pond
Effluent
0.7
ND
to
2.0
13.6
18
1.9
HD
HU
20,000
14
0.3
860
ND
ND
ND
HD
Slurry
Paid
Effluent
12
ND
ND
1.6
5.2
18
1.4
ND
ND
>2.300
ND
5.1
420
ND
790
ND
ND
Acid
Prep
Plant
Recycle
Pond
6.2
ND
ND
ND
4.5
7.3
HD
ND
ND
>4,20cl
ND
l.B
280
Prep
Plant
Recycle
Pond
ND
ND
ND
1.4
ND
12.
1.5
ND
ND
14.000
ND
ND
380
630 i 560
ND
ND
ND
* : .r" —
110
H>
ND
Prep
Plant
Recycle
Pond
ND
ND
HD
ND
ND
152
ND
HD
ND
1,500
ND
ND
ND
ND
ND
ND
ND
Prep
Plant
Hater
Circuit
M>
MD
ND
ND
1.6
ND
MD
ND
7,100
ND
ND
1,200
ND
ND
ND
ND
Slurry
Pond
Effluent
1.2
ND
ND
1.8
20
21
'2.6
ND
ND
20,000
ND
0.3
510
270
ND
ND
ND
A/* I*
SUJRRY
IA3XN
to
ND
NO
ND
ND
78
10
ND
1220
ND
ND
SUJRRY
UOXN
ID
ND
ND
ND
ND
20
ND
ND
ND
450
HO
(0
13
ND
ND
ND
to
*/# IO
-------
oo
Oi
Ul
Priority Pollutants, pq/1
benzene
chlorobenzene
1 , 2-diehloroethane
1 ,1 ,1-trichloroethane
1,1,2 ,2-tetrachloroethene
chloroform (trichlorcnethane)
1, 2-trans-dLchloroethylene
2 , 6-dinitrotoluene
ethylJbenzene
•etnylene chloride
trichlorofluocaiethane
toluene
bia(2-ethvlhexYl) phthalate
di-n-butyl phthalate
diethyl phthalate
anthracene
phoianthrene
Refuse
Pile
Raw
Water
4B
ND
ND
ND
ND
45
ND
ND
ND
480
ND
14
ND
ND
ND
ND
ND
Refuse
Treated
Effluent
6.3
ND
ND
1.7
1.2
19
1.7
ND
ND
66,000
22
2.0
6,100
210
ND
ND
ND
Refuse
Pile
Raw
Hater
44
12
ND
ND
ND
ND
Refuse Pile
Runoff Non-
Discharging
Pond
ND
ND
ND
ND
ND
26
i
ND ND
ND
ND 1
1,440
ND
27
ND
ND
ND
ND
ND
ND
ND
654
ND
ND
ND
Refuse
Pile
Non-Dis-
charging
Pond
10
ND
HD
ND
ND
ND
10
ND
ND
967
ND
30
ND
ND *°
ND
ND
ND
ND
ND
ND
REFUSE
PILE
RMfNKtER
ND
ND
ND
ND
i
ND
ND
ND
ND
ND
348
ND
10
ND
ND
ND
ND
ND
Storage
Pile
Runoff
Untreated
ND
ND
ND
ND
ND
476
ND
ND
1,100
ND
ND
10
ND
ND
ND
ND
MC-/S
-------
CONTROL OF TRACE ELEMENT LEACHING FROM
COAL PREPARATION WASTES
E. M. Wewerka, J. M. Williams, P. Wagner,
L. E. Wangen, and J. P. Bertino
Los Alamos Scientific Laboratory
Los Alamos, New Mexico
ABSTRACT
The aqueous drainage from coal refuse dumps often is contaminated with
acids and a variety of potentially toxic trace and inorganic constituents.
The Los Alamos Scientific Laboratory is involved in a research program, which
is jointly supported by EPA and DOE, to identify suitable methods to control
or abate this form of environmental pollution. Control methods that are
currently under investigation include techniques to immobilize or remove the
contaminating substances from coal cleaning wastes prior to disposal, treat-
ment of refuse dumps to prevent the release of pollutants from them, and
treatment of contaminated waters as they emerge from refuse disposal sites.
The emphasis of this paper is to review experimental results that have been
obtained in this program to date, and to discuss the various environmental
control options available to the coal cleaning industry.
856
-------
INTRODUCTION
The mineral wastes from coal preparation and mine development constitute
a major environmental problem. Over 3-billion tons of these materials have
accumulated in the U.S., and the current annual rate of waste production of
100-million tons per year is expected to double within a decade (National
Academy of Sciences, 1975). The total number of coal waste dumps is estimated
to be between 3000 and 5000 of which one-half pose some type of health, en-
vironmental or safety problem (National Academy of Sciences, 1975). Struc-
tural weaknesses in coal refuse banks have led to tragic landslides such as
those at Buffalo Creek, WV and Aberfan, Wales, and the 300 or so burning
waste banks are a major source of air pollution. In addition to these prob-
lems, there is growing concern about environmental effects from the trace
elements that are present in the highly mineralized, acid drainage from coal
refuse dumps that affects many thousands of miles of streams and waterways.
857
-------
Although it has been established that the drainage from coal refuse dumps
is often highly contaminated with trace or inorganic elements, little is known
about the quantities of undesirable elements that are released into the envi-
ronment from this source (Wewerka, et al., 1976). Development of the neces-
sary control technologies for human and environmental protection requires
quantitative evaluation of the extent and severity of the problem. LASL has
been directed by DOE and EPA to assess the nature and magnitude of the trace
elements in the drainage from coal preparation wastes, to identify the trace
elements of greatest environmental concern in these materials, and to evaluate
required pollution control technology for this form of environmental contami-
nation.
This program is divided into several research activities. The initial
efforts included studies of the structure and weathering and leaching behav-
iors of the trace elements in selected samples of high sulfur refuse and
coal (Wewerka, et al., 1978a and b). These investigations established the
overall potential of these materials to cause trar.e element contamination,
and revealed the identities of the specific trace elements of concern in the
«*
refuse and coal pile effluents. The information gathered on refuse and coal
structure and environmental behavior provided the basis for the present stage
of the program, which involves assessment or development of control technology
to lessen the environmental impact of trace element pollution of coal or refuse
associated waters.
Investigations are now underway to identify the options for preventing
•or controlling trace element contamination of the. drainages from high sulfur
858
-------
coal preparation wastes. Two basic approaches to effect trace element control
are being considered in this work. The first involves methods to treat newly
produced coal refuse either at the preparation plant or during disposal to pre-
vent the eventual release of trace elements from the disposal site. These
techniques include refuse calcining, treatment of the refuse to remove acid
forming constituents and labile trace elements, and the application of adsorb-
ents or attenuating agents to refuse disposal sites. The second approach con-
cerns techniques to reduce or abate the trace-element composition of already
contaminated waters emerging from refuse dumps or disposal areas. Under con-
sideration here are such methods as alkaline neutralization, ion exchange,
reverse osmosis, chelation and application of selected adsorbents. Some of
the experimental results from these researches are reviewed and discussed in
the following sections of this paper.
EXPERIMENTAL
The coal preparation wastes used in this work were collected from three
coal cleaning plants (designated Plants A, B and C) in the Illinois Basin.
These samples of high sulfur coal refuse are typical of the wastes produced
by cleaning of the major coal types currently mined in the region (Wewerka,
et al., 1978a).
The mineral and elemental compositions of the raw refuse samples, cal-
cined refuse materials and mixtures of refuse with other materials were an-
alyzed by x-ray diffraction, neutron activation analysis, atomic absorption
spectrophotometry, optical emission spectroscopy and wet chemical methods.
Both static and dynamic leaching experiments were conducted to evaluate
the behavior of the trace elements in the Illinois Basin coal wastes under
simulated environmental conditions and to test the effectiveness of potential
environmental control methods. The static experiments were carried out by
859
-------
agitating a known quantity of crushed rafuse or composite (50 g) in the pres-
ence of a constant volume of distilled water (250 ml) for varying periods of
time. In the dynamic or column leaching tests, a crushed sample (~ 1500 g) was
packed into a 70-cm-long by 4.6 cm-diam glass column and distilled water waa
continuously monitored through the column at a rate of 0.5 ml/min. The ele-.
mental compositions of the experimental leachates were determined by the tech-
niques mentioned above.
The details of the experimental set ups and analytical procedures used
in this study appear in two recently published reports (Wewerka, et al.,
1978a and b).
RESULTS AND DISCUSSION
The Illinois Basin coal refuse samples used in this study were composed
of clay minerals (illite, kaolinite and other more complex clays), quartz,
pyrlte, and marcasite. Interspersed throughout the mineral network were a
variety of minor minerals and residual coal. The relative magnitudes of the
major minerals constituting these refuse materials did not vary greatly from
sample to sample.
Elementally, these refuse materials were found to be very complex. Some
55 elements were identified in most of the refuse samples and undoubtedly
there are more (Wewerka, et al., 1978b). The most abundant of these elements,
Fe, Al and Si, comprise the structures of the major mineral systems. The
.*
minor elements are present as constituents of minor minerals, components of
the residual coal or substituents in the major mineral lattices.
Static and dynamic leaching experiments were performed to evaluate the
trace element behavior of Illinois Basin coal wastes under simulated weather-
Ing conditions. These experiments were done to provide information needed
to predict quantitatively the trace element levels in the drainage from coal
860
-------
refuse dumps or disposal areas and to identify those elements of environ-
mental concern.
Perhaps the single most important characteristic of the high sulfur ref-
use materials during aqueous leaching is their pronounced tendency to rapidly
produce acidic leachates. This is due to the oxidative degradation of the
pyrite and marcasite present in the refuse. Acid formation is partially atten-
uated by calcite or other neutralizing species in the refuse, but the leachates
from the Illinois Basin refuse samples that we studied nearly always had pH
values in the range of 2 to 4. These acid leachates are very efficient in
dissolving or degrading many of the mineral components of the refuse, and
thus releasing the trace or minor elements associated with them. Figure 1 de-
picts the relationship between leachate pH and the dissolved solids contents
of the leachates in contact with the various refuse samples.
Two types of trace elementleachabilities were observed for all of the
Illinois Basin retuse samples. Because ot their abundances in the reruse
some elements (such as Fe, Al, Ca, Mg) are released in relatively high absolute
quantities (Table 1). Other, less abundant elements (for example, Ni, Co, Zn,
Cu) are leached in a high proportion to the total of each present, although
this may not be a large amount in the absolute sense (Table 2). The first
group is highly concentrated in the leachates, the second is highly leachable
from the refuse. A similar trace element release behavior wae also observed
during the dynamic leaching of these refuse materials.
Multimedia Environmental Goals (MEGs) were used to identify the hazardous
trace elements in the leachates from the refuse materials studied (Cleland
and Kingsbury, 1977).MEGs are defined as levels of potentially hazardous ef-
fluents that are appropriate for preventing negative effects in exposed eco-
systems or represent control limits achievable through current technology.
861
-------
O
V)
Q
LJ
1
.<
• PLANT A
• PLANT B
A PLANT C
Figure 1. The rclaricnshlp between pTT and total dissolved solids for lc-ac'i-
aues Iioiu static ieaciiing experimencs wich Illinois aaain coal refuse.
862
-------
Leachate concentration Leachate concentration
Element yg/mil Element u yg/m&
Fe 16400 Co 18
Ca 680 As 7
Al 570 Cu 3.7
Mg 216 Ti < 2
K 90 V < 2
Na 74 Cr 1.1
Zn 48 Be 0.2
Mn 40 Cd 0.2
Ni 31 Pb < 0.2
Table 1. Trace elements released from Illinois Basin coal refuse during
static leaching. Results from experiment with Plant B refuse.
Conditions: 50 g of -20 mesh refuse agitated with 250 m£ water, 1 day,
room temperature, open vessel.
Percent of Percent of
Element total leached Element total leached
Ca 79 Cu 7
Co 60 Be 6
Ni 46 Na 5
Zn 42 V < 2.5
Cd 35 Cr 1.2
Mn 28 Al 1.2
Fe 14 Pb < 1.2
As 9 K 0.8
Mg 9 Ti < 0.1
Table 2. Percent of trace elements released from Illinois Basin Plant B
coal refuse during static leaching. Conditions: 50 g of -20 mesh refuse
agitated with 250 m£ water, 1 day, room temperature, open vessel.
863
-------
The utility of the MEG system Is that it provides a means for directly deter-
mining which of the contaminants in waste water solutions, such as those of
interest here, exceed concentrations that are safely assimilated by the en-
vironment. Application of the MEG routine to data on the composition of ref-
use leachates obtained in this work, and from available information in the
literature, has revealed that nine elements, Fe, Al, Ma, Co, Ni, Zn, As and
Cd are frequently present in potentially hazardous amounts. Although these
elements are not necessarily the only ones in the refuse leachates that could
conceivably be troublesome under all circumstances, they are, however, the
priority elements that are receiving the greatest emphasis in the current
work on environmental control technology.
Research has now been started to identify suitable means to control
trace element contamination of the drainages from high sulfur coal prepara-
tion wastes. These control techniques can roughly be divided into three
categories: (1) immobilization or removal of contaminants prior to disposal
of the refuse materials; (2) waste dump treatment to prevent the release of
undesirable substance from it; and (3) treatment of already contaminated
water discharged from existing refuse disposal sites. Encouraging results
have been obtained from current research on each of these three types of en-
vironmental control techniques.
One of the more promising techniques under consideration to immobilize
the hazardous elements in high sulfur coal refuse materials is calcining of
the refuse to high temperatures to produce an inert glass-like slag. Present
work in this area is directed both at identifying the chemical and physical
* These studies are directed at environmental control of both surface and
groundwater contamination that may result from the disposal of coal prepa-
ration wastes either on or near the surface or the deep burial of them in
strip or underground mines.
864
-------
changes brought about in the refuse structure as a result of the heat treat-
ment, and at defining the consequent decreases in trace element mobilities.
Several calcining experiments have been performed to determine the opti-
mum heat treatment conditions necessary to chemically immobilize the poten-
tially toxic trace elements in the refuse matrix. These experiments were
performed using high sulfur coal preparation wastes from Plants B and C
(Illinois Basin). The wastes were ground to -20 mesh and calcined in air at
600, 800, 1000, and 1200°C for a 2 h period. The success of the calcining
treatment at reducing the trace element mobilities of the refuse samples is
illustrated by the data from a comparison leaching experiment incorporating
the refuse sample that had been calcined at 1000°C (Table 3). The calcined
and uncalcined refuse samples listed in the table had been subjected to static
leaching for 48 h. It is seen from the information in the table that calcin-
ing has essentially eliminated the acid generating potential of the refuse
samples ar* thst the TDS ccr.tectc of the resulting lcschat£3 was substantially
reduced. More important is the fact that the concentrations of the abrevi-
ated group of toxic elements listed have been reduced in the calcined refuse
leachates by about two orders of magnitude over the concentrations in the
leachates produced from the raw refuse materials.
Physically, the samples calcined at 1000 and 1200°C began to sinter.
X-ray diffraction analyses of the calcined materials suggests that at these
*
temperatures considerable breakdown of the clay mineral structures has begun
to occur. This apparently results in significant encapsulation of the
leachable refuse components. The acid forming constituents of the refuse
samples (pyrite and marcasite) are transformed at lower temperatures to vol-
atile sulfur compounds. This is evidenced by the reduction of the sulfur
content of the Plant B refuse material from 13.4 wt % to 0.7 wt % after
865
-------
Uncalcined Calcined
Refuse Refuse
PH 2.3 C.C
TDS(%) 0.6 0.2
Al 40 0.3
Fe 240 < 0.02
Mn 2.3 0.02
Co 1.1 0.01
Ni 1.9 0.01
Zn 1.1 0.05
Table 3. Trace element leachability of a coal refuse sample calcined at
1000°C for 2 h. Elemental compositions of leachates are reported as ppm,
866
-------
calcining to 800°C. This undoubtedly accounts for the marked reduction of
the acid generating potential of the calcined refuse samples.
In addition to the research just described on refuse clacining, studies
are also being conducted on the effectiveness of preleaching the refuse ma-
terials to remove both the acid forming constituents and the mobile trace
elements prior to disposal. This work involves the application of water in
conjunction with a variety of oxidizing agents to effect contaminant removal.
Several methods are being considered to treat coal refuse during dispos-
al to prevent the release of trace contaminants during subsequent waste dump
weathering or leaching by surface or ground water. These include codisposal
of the refuse material with neutralizing agents or trace element adsorbents
and the application of water tight sealants to all or parts of the waste
dump mass.
Especially promising among these techniques is the codisposal of the
acid refuse materials with alkaline agents such as lime. In one set of ex-
periments, for example, powdered lime in varying amounts (3 to 50 g) was
slurried in 150 ml of distilled water with -3/8 in. high sulfur coal refuse
(530 g, from Illinois Basin Plant B). The resultant mixture was subsequent-
ly filtered, dried in air at 50°C, and repulverized to -3/8 in. particles.
Four different lime concentrations were employed; 0.5, 1.5, 3 and 10 wt %.
In addition, a control refuse sample that had not been lime treated was al-
so incorporated into this study for comparison purposes.
Column leaching experiments were conducted with about 500 g of each of
the above samples to determine the effects of the lime additions. The ref-
use mixtures were packed into pyrex columns 25 cm long by 5 cm diameter and
subsequently leached with distilled water at a flow rate of p.5 ml/min
until more than 4 £ of water had been passed through the refuse beds. The
867
-------
composition of the leachates after about-300 ml of water had passed through
the columns containing the refuse mixed with 3 and 10 wt % lime and also
through a control column containing untreated refuse are given in Table 4.
Although the data are not listed in Table 4, the leaching experiments
showed that the addition of 0,5 and 1.5 wt % line to the acid refuse had
only a small influence on leachate pH and trace element concentration because
the acid neutralization provided by these amounts of lime was overwhelmed
by the acid generating capability of the refuse. The additions of 3 and 10
wt % of lime, on the other hand (Table 4), did indeed effectively counteract
the acid properties of the refuse; the pH of the leachates for these two
systems are elevated to acceptable levels and the trace element compositions
of the leachates from the treated refuse samples are significantly reduced
in all instances,
The system containing 3 wt % lime is especially interesting because a
leachate pH of 7 was maintained for nearly the entire duration of the leach-
ing experiment (until 4.2 £ had been passed through the column). TDS values
for this refuse-lime combination were also very respectable (ranging down-
ward from about 0.6 wt %) especially considering that the dissolution of
the lime itself adds substantially to the dissolved solids content of the
solution.
As a result of experiments like these, the addition of alkaline agents
*
to refuse disposal sites is viewed to be a very promising means to control
acid generation and trace element releases from high sulfur coal refuse, and
the research effort in this area is being continued.
Another potentially fruitful way to retain the leachable contaminants
within a refuse disposal site is to intermix the acid coal wastes with suit-
able amounts of trace element attenuating agents. An example of one of the
868
-------
Untreated refuse
Control
PH
TDS(%)
Al
Fe
Mn
Co
Ni
Zn
2
4
720
7800
22
12
18
29
Refuse + 3% Lime
7
0.4
< 0.6
40
1
0.3
0.5
0.1
Refuse + 10% Liyie
12
0.5
< 0.5
< 0.1
< 0.02
0.1
0.1
0.02
Table 4. A few results from a column leaching study of Illinois Basin coal
refuse that had been lime treated. Elemental compositions of leachates are
given as ppm. Leachate volume 300 m£.
869
-------
preliminary studies conducted in this area will illustrate the potential
utility of the method.
In this experiment, acidic coal refuse leachates were equilibrated with
several solid sorbent materials to evaluate their trace element attenuation
capabilities, prior to using these agents in codisposal experiments. The
solids used were illite, montmorillonite, and kaolinite clays; a sample of
scrubber sludge, precipitator ash and two samples of bottom ash, each from
different power plants; an acid drainage treatment sludge; and a clay rich
soil. The experimental procedure consisted of shaking the solid (50 g) with
the coal refuse leachate (150 ml) for 15 h, measuring the resulting pH and
analyzing the filtrate for trace elements.
Several of these agents proved to be quite effective in attenuating the
acid and trace element contents of the refuse leachates. Among these were
the fly ash, scrubber sludge and AMD sludge and the illite and montmorillonite
clays (Table 5). (An important point to distinguish here is that the fly ash
and sludges are themselves alkaline agents, so the effectiveness of these two
materials may at least in part be due to pH control of the solutions rather
than direct trace element adsorption.) The bottom ash samples, not unexpect-
edly proved to be too chemically intractable to interact with the contamin-
ated leachates and the one soil studied did not exhibit sufficient exchange
capacity to be of use. Other experiments are being conducted, however, to
test the trace element and acid absorbtivities of a wide variety a calcareous
and noncalcareous soils, and weathered and nonweathered soils from the Illinois
Basin.
Studies are also underway to evaluate several techniques for treating
refuse drainage water that is contaminated with acids and toxic trace elements.
870
-------
Untreated leachate
Control Scrubber Sludge Fly Ash Illite
PH 2.6 7.3
Al 10 < 0.2
Fe 107 < 0.1
Mn 4 2.2
Co 1.9 0.7
Ni 2.6 0.8
Zn 1.0 0.6
Table 5. The attenuation of contaminated coal refuse leachates by various
agents. Elemental concentrations in leachates reported as ppm.
9.6
0.6
0.2
0.04
0.1
< 0.05
0.02
9.1
0.6
0.3
0.3
0.1
0.07
0.35
871
-------
Included among these are alkaline neutralization, ion exchange, reverse osmo-
sis, chelation and biological treatment.
These techniques have proven fruitful in attenuating contaminants in
many types of industrial or mining waste waters, and may be effective in treat-
ing coal refuse drainage.
One of the most promising of these control techniques, alkaline neutral-
ization, is currently used extensively to treat acid drainage from coal mines.
While it is well known that alkaline neutralization is very effective in con-
trolling the acid and overall salt compositions of mine waste waters, the de-
gree of control that this method exerts over some of the more highly leach-
able toxic trace elements remains to be established (Wewerka, et al., 1976).
Elaboration of this latter point is the basis for one of the studies now being
conducted in this area.
In this work, the degree to which the solubilities of the various trace
elements in the drainage from high sulfur coal refuse are effected by neutral-
ization with such agents as limestone and lime is being investigated. The
experiments are basically titrations in which limestone, lime or lye (the
standard base) were added to one liter of contamined refuse drainage until
a predetermined value of the pH was reached. The solutions (or slurries)
were allowed to sit overnight, filtered, and the pH, dissolved solids and
trace element contents of them were measured. The results of these experi-
ments are summarized in Table 6.
Examination of Table 6 shows that neutralization is an effective tech-
nique for decreasing trace element concentrations in refuse waste water.
The pH and Fe contents of the treated solutions are within acceptable limits,
based on the 1977 EPA effluent limitation guidelines for coal preparation
plants (Fe ^3.5 ug/ml averaged for 30 days, pH 6-9). Mn, however, exceeds
872
-------
Untreated Leachate
_ Control
PH 1.1
TDS(%) 0.5
Al 18
Fe 820
Mn 3.6
Co 2.0
Ni 3.2
Zn. 3.9
Lye
6
3.4
< 0.2
0.06
0.07
0.05
0.05
0.02
Limestone
7.1
3.2
< 0.2
0.3
6.4
1.0
1.0
0.1
Lime
6.6
3.2
< 0.2
0.3
1.0
0.6
0.7
0.1
Table 6. Alkaline neutralization of contaminated refuse drainage. Drainage
compositions reported as ppm.
873
-------
the acceptable level of 2.5-3 yg/ml (averaged for 30 days) in the limestone
case. Further work in the area of alkaline neutralization of refuse drainage
involves its application to more highly contaminated drainage to investigate
coprecipitation phenomenon, and the scale up of the process to more life-like
circumstances.
SUMMARY
The purpose of this paper was to present an overview of research under-
way at Los Alamos Scientific Laboratory to identify the various options for
controlling trace element contamination of coal refuse drainages. The control
methods under consideration include chemical and physical methods to immobilize
or remove undesirable contaminants prior to refuse disposal, the treatment of
refuse disposal sites with attenuating agents or sealants to prevent the dis-
charge of contaminated water, and the direct treatment of refuse drainage
as it emerges from the refuse disposal site. The initial results from these
studies suggest that many of the techniques being considered are technically
feasible for controlling trace element contamination of refuse dump drainage.
REFERENCES
Cleland, J. G., and Kingsbury, G. L. 1977. Multimedia environmental goals
for environmental assessment. Vol. I and II. EPA-600/7-77-136a, b.
National Academy of Sciences. 1975. Underground disposal of coal mine wastes.
National Science Foundation, Washington, DC.
Wewerka, E. M., Williams, J. M., Wanek, P. L., and Olsen, J. D. 1976.
Environmental contamination from trace elements in coal preparation
wastes: a literature review and assessment. EPA-600/7-76-007.
Wewerka, E. M. and Williams, J. M. 1978a. Trace element characterization of
coal wastes — first annual report. EPA-600/7-78-028.
Wewerka, E. M., Williams, J. M., Vanderborgh, N. E. , Harmon, A. W., Wagner, P.,
Wanek, P. L. and Olsen, J. D. 1978b. Trace element characterization of
coal wastes — second annual progress report. EPA-600/7-78-028a.
874
-------
STABILIZATION OF COAL PREPARATION PLANT SLUDGES
David C. Hoffman
Dravo Lime Company
Pittsburgh, Pennsylvania
ABSTRACT
As operating costs continue to increase, coal producers search for new
processes to reduce costs. One major area for improvement is fine coal
refuse handling and disposal. Current disposal practices for this material
utilize large permanent settling ponds, temporary settling ponds, large
permanent impoundments, or mechanically dewatered solids for landfill disposal.
This discussion will briefly review Calcilox* additive stabilization tech-
niques, present the latest technical developments, and illustrate Calcilox
additive disposal alternatives that can technically and economically improve
fine coal refuse disposal.
* Calcilox (trademark) additive is a registered trademark of Dravo Corporation.
875
-------
Introduction
Today, the major energy reserve in the United States is
coal, which accounts for nearly 80% of the known recoverable
resources. Reasonably priced energy, in all forms, is needed
to maintain our industrial productivity and high standard of
living. Coal must provide a significant portion of our
present and future energy requirements. 1976 production of
mined bituminous and lignite coals was nearly 679 million
tons. Energy planners believe this production level must be
raised to 1.2 billion tons by 1985 to attain our national/
energy goals. This will require more numerous and more
efficient coal mining, preparation, and transportation
operations.
There are many difficult operations in coal mining; one
of the most troublesome being the disposal of coal preparation
wastes, in particular, the fines portion. Research by Dravo
Lime Company has led to the application of an additive, Calcilox,
that when added to waste solids, produces a stable material
with the consistency of compacted soil. With these greatly
improved characteristics, recognized disposal means can then
be utilized for the fines.
Discussion
Generally, a coal preparation plant produces two types
of refuse; a coarse fraction (plus 28 mesh), and a fine fraction
(minus 28 mesh). These two wastes can be handled separately or
876
-------
mixed together based on the preparation plant circuitry and/or
disposal criteria. Figure 1, Alternate Refuse Handling Modes,
illustrates some typical disposal methods. Based on our
experience, the coarse refuse, alone, does present serious
disposal problems because of the size consist, low moisture,
compactibility, and cohesive strength. These properties can
be utilized in designing safe and environmentally acceptable
landfill disposal sites.
However, the fine refuse is quite different and its
disposal may hot be straightforward. Typically, the fine
refuse solids are in a slurry form ranging from 15% to 45%
solids, by dry weight, or exist as a 55% to 75% thixotropic
solids cake produced by a vacuum disc filter, solid bowl
centrifuge, or a plate and frame filter press. In either a
cake or slurry form, the solids are not readily dewatered
further; will easily reslurry; and do not possess significant
cohesive strength for permanent landfill disposal. The
latest statistics indicate that the 1976 mined bituminous
and lignite coal tonnage was 679 million tons with 269 million
tons mechanically cleaned. It is estimated that the amount of
refuse produced was 89 million tons consisting of 16 million
tons as fines and 73 million tons as coarse refuse. An
important underlying fact in dealing with the disposal of
these quantities is that over 80% of the coal cleaning plants
are located in the states of West Virginia, Kentucky,
877
-------
II .
1
L-n
1
j OlmiWHM B¥ TRUCK Ct
L_
1
1
I—
1
| HMIt WO D1ITRIDUH
1 ' H TMCI M CCUPU
| 1 UMIWB
— ' 1
1
1
1
1
r
i
I
i_
l— O*U W7ILT&ITI
~l
1
IICQMUAM TBMMf AND DC
MD/OM KMTU LOMM
in_
n
"•I
i
Figure - 1
ALTERNATE REFUSE HANDLING MODES
878
-------
Pennsylvania, Virginia, Illinois and Ohio. In the coal
producing regions of these states, the topography ranges from
gently sloping to steeply mountainous; not conducive for
landfill disposal of a fluid mass such as the fine coal refuse.
A common fines disposal method is to pump the thickener
underflow to a lagoon and allow the solids to settle. When
topography is favorable for the lagooning approach, several
lagoons may be excavated to provide a long filling lifetime.
After these ponds are full, they may be abandoned and new ones
excavated. In the major Appalachian coal fields, topography
usually does not favor extensive pond systems. Generally,
a pond or two are excavated, filled, and the settled solids
reexcavated and disposed of. The pond or ponds are then
refilled, and the cycle repeated. The major problem with
handling the settled fines is the fluidity of the material
at normal settled solids concentration between 45% and 60%
(Figure 2, Fluid Settled Solids). Due to the clayish nature
of most fine refuse, the solids will easily reslurry even
after the solids have been air dried.
As an alternate for ponds or impoundments, the thickener
underflow may be mechanically dewatered to (1) close the plant
water circuit, (2) save disposal space, and (3) attempt to
improve the handling characteristics of the slurry. Assuming
ideal success in all handling stages, the dewatered material
879
-------
Figure -• 2
FLUID SETTLED SOLIDS
880
-------
could be mixed with the coarse refuse and compacted into a
stable landfill. Unfortunately, this is a huge, seldom
realized assumption. In actual practice, the cakes are
extremely difficult to homogeneously mix into the coarse
refuse. They remain in large, sticky masses which gum up
conveyors, bins, and trucks. In summary, the dewatered fines,
whether intact or partially mixed with the coarse material,
present a troublesome handling and disposal task.
We believe that the disposal of these fine refuse solids
can be dramatically improved. One viable solution is the
addition of a chemical, Calcilox additive, to the refuse
slurry or dewatered cake. Calcilox additive (Figure 3) is
a dry, free-flowing light grey powder of inorganic origin
and it is chemically activated with water. Calcilox additive
is mixed into the refuse on a weight percentage of the dry
refuse solids. The net result of this addition will be the
development of definitive engineering properties in the refuse;
such as compressive strength, cohesion, shear resistance, and
reduced water permeability.
The most recent technical study has just been com-
pleted for the Pittsburgh Branch of the Department of Energy
Management of Coal Preparation Fine Wastes Without Disposal
Ponds, D. C. Hoffman, R. W. Briaas. S. R. Michalski. Dravo
Lime Company, June 15, 1978, Contract No. J0177050, Depart-
ment of Energy, Branch of Procurement, Washington, D.C.
881
-------
Figure - 3
"CALCILOX, A DRY FREE FLOWING POWDER
-------
(formerly the United States Bureau of Mines) investigating
the general effects of chemical stabilization on fine coal
refuse. Fine refuse samples were collected from various
preparation plants representative of "typical" operations
in the Eastern bituminous coal fields. One of the prime
objectives of study was to investigate the untreated, as-
received properties of these fine solids. Table I, Untreated
Fine Coal Refuse, tabulates the important physical properties
of permeability and direct shear results for the samples
tested as a settled slurry and as a filter cake. In reviewing
the data, it must be pointed out that the solids content of
the slurries and cakes is quite high due to the laboratory
conditions. Field investigations indicate that settled solids
usually run between 45% and 60% solids while mechanically
dewatered cakes may range from 55% to 75% solids. The major
points illustrated here are the overall lack of any cohesive
strength (less than 1 psi) and low permeabilities (10~6) on
both the settled solids and filter cakes. These two factors
contribute quite heavily to the fluidity of large masses of
fine coal refuse.
The chemical additives tested in this study were hydrated
lime, Portland Type 1 cement, and Calcilox additive. Lime and
Portland cement have been known to impart some stabilizing
effects to fine refuse but no quantitative results have been
reported. Secondly, all three additives are commercially
883
-------
TABLE I
UNTREATED PINE COAL REFUSE
Sample
Mo.
11 04
1105
1106
1107
1110
1111
1112
1113
Hill
PermeabU ity
Settled Slurry
cm/sec .
f..0x!0~b
l.Oxlo"5
7.4xlO~b
2.6x10 6
-£
4.4x10 b
,f
-------
available and are competitively priced. Based on Dravo's
experience, the most economic use of chemical stabilization
techniques occurs with additive dosages ranging from 5% to
15%, on a dry solid basis, high solids cakes to thickener
underflows, respectively. With this in mind, stabilization
tests were conducted covering the range of typical thickener
underflows (25% to 35% solids) and high solids filter cakes
(70% to 82% solids).
The procedure used to evaluate the effectiveness of each
additive was the development of unconfined compressive strength
after 40 days of curing. Table II, 40-day Unconfined Com-
pression Strength, lists the results obtained for ambient
temperature stabilization. Using the criterion of highest
possible strength, this figure illustrates that Calcilox
additive is the best for treating thickener underflows in
the 25% to 35% solids range. In seven out of the nine filter
cake samples, Calcilox is also superior to Portland cement and in
all cases, vastly superior to lime additions. In actual
applications, the dosage level and strength desired will vary
and is dependent on each specific disposal mode and can be
verified by laboratory testing.
Recommended Stabilization Methods
Thus far, we have attempted to define fine coal refuse
disposal and to present the latest laboratory results. The
885
-------
TABLE II
40-DAY UNCONFINED COMPRESSION STRENGTH
(PSD
Treatment
Additive
Untreated
5t Portland
Type I
5% Lime
5% Calcilox A
5% Calcilox B
10% Portland
Type I
10% Lime
10% Calcilox A
10% Calcilox B
15% Portland
Type I
151 Lime
15% Calcilox A
15% Calcilox B
Mixed
Solids
%
25
35(3)
FCVJ/
35
FC
35
FC
35
FC
35
25
35
FC
25
35
FC
25
35
FC
35
25
35
25
35
25
35
35
Sample Number
1104
72o(l)
JJ)
*
*
*
95.9
*
37.2
*
78.6
*
*
1.6
141.3
*
*
39. B
6.1
15.1
368.6
10.3
*
4.5
*
*
15.4
24.4
35.9
1105
72°
*
*
6.6
*
85.0
*
23.1
8.8
124.9
7.2
*
0.8
165.3
*
*
12.6
39.4
27.0
188.5
37.5
*
2.2
*
*
31.0
30.2
86.1
1106
72°
*
*
*
*
73.9
*
20.0
8.5
80.3
4.9
*
2.8
141.0
*
*
22.2
19.7
33.9
494.4
36.1
1.9
3.6
*
*
80.6
59.4
80.3
1107
72°
*
*
*
*
123.2
*
23.2
10.0
218.2
7.5
*
*
76.1
*
*
15.2
20.6
38.9
233.7
32.8
*
*
*
*
47.7
35.7
87.9
1110
72°
*
*
*
*
18.7
*
7.6
0.8
81.3
1.4
*
*
115.5
*
16.4
5.4
10.8
120.0
19.5
*
1.9
*
*
12.1
17.1
34.4
1111
72°
*
*
*
*
67.6
*
*
1.6
50.7
2.6
*
141.5
*
*
13.6
9.0
14.1
116.6
12.2
*
*
*
15.5
21.0
26.4
1112
72°
*
*
5.1
50.5
8.5
4.8
98.5
10.2
*
159.4
*
13.3
7.7
4.5
69.9
33.7
*
*
*
*
6.6
13.3
39.3
1113
72°
*
*
*
*
60.4
*
9.6
1.4
106.9
1.5
0.9
160.9
*
*
14.6
3.7
8.4
231.2
16.4
*
1.9
*
*
10.3
24.2
39.5
1114
72°
*
*
*
*
67.1
*
15.6
2.0
89.1
2.0
*
145.4
*
*
16.1
4.7
4.4
224.5
6.8
*
*
*
11.6
15.0
24.0
00
00
curing temperature measured in degrees Fahrenheit.
* Indicates specimen did not have a measurable strength at 40 days.
FC - Filter cake solids level - 70%-82% Solids
-------
following represents disposal modes that can be utilized for
full-scale operations.
1. Interim Stabilization (Figure 4)
Fine refuse thickener underflow is treated with
Calcilox additive and deposited into temporary curing ponds.
The duration of the curing period will vary from days to
several weeks depending upon the nature of the refuse, the
Calcilox additive dosage, the slurry solids etc. When the
handling characteristics of the slurry are sufficiently
improved, it is excavated by dragline or other methods and
is transported to a permanent landfill disposal site. By
using the correct amount of Calcilox additive and excavating
the material before the reaction has produced a very rigid
mass, it is possible to continue the hardening after the
material is placed in its final disposal location. This
alternate requires some space and due to multiple handling,
does represent a relatively higher operating cost than the
following methods 2, 3, or 4. Operating costs are compen-
sated for by increased operational flexibility and control.
In addition, supernatant can be easily reclaimed for reuse in
the preparation plant.
2. High Solids Cake - Separate Disposal (Figure 5)
For those companies which already own mechanical
dewatering equipment, it is possible to treat the resulting
887
-------
Figure - 4
INTERIM STABILIZATION
Figure - 5
HIGH SOLIDS CAKE - SEPARATE DISPOSAL
888
-------
cakes at a somewhat lower additive cost than would be the
cost for stabilizing thickener underflow. It is possible to
excavate small pockets or lagoons within the coarse refuse
deposit. Treated cake is retained in these pockets until the
Calcilox additive has hardened the material sufficiently to
support earthmoving equipment. The pocket can then be graded,
compacted, and covered with coarse refuse. Stabilization
rates for cakes are rapid so that these pockets can be covered
quickly if required for the management of the landfill. Again,
this method offers some flexibility, and lower operating costs
when compared to interim ponding. This "pocket" method does
not appear to be suitable for thickener underflows unless the
coal company can construct large enough pockets to meet the
longer stabilization periods. In addition, the costs of a
mobile and flexible piping system may be prohibitive.
3. High Solids Cake-Coarse and Fine Refuse Disposal
(Figure 6)
The third disposal mode, mixing coarse and Calcilox
additive treated fines, may be the most easily adapted to an
existing plant that currently combines a dewatered fine refuse
with the coarse reject. In most plants the amount of coarse
refuse (by weight and volume) is several times the amount of
fine refuse. However, the combination of the two generally
creates a nearly unmanageable situation in terms of immediate
handling and long-term stability. After laboratory testing
of the fine refuse cake with Calcilox additive, an optimum
889
-------
Figure - 6
HIGH SOLIDS CAKE - COARSE AND FINE REFUSE DISPOSAL
890
-------
dosage is determined. Subsequent laboratory testing of
mixtures of coarse refuse and treated fine refuse cake can
determine the proper ratio of coarse to fine refuse for
immediate handling properties. The addition of Calcilox
additive to the fine refuse cake and mixing with the selected
coarse fraction will give satisfactory, immediate handling
characteristics plus long-term stability. The primary
disadvantage of this approach is the extra cost of sizing
and blending equipment to handle the whole plant reject while
only the fines are the problem.
4. Permanent Impoundment Stabilization (Figure 7)
Fine refuse slurry is treated with Calcilox additive
and pumped behind an impoundment where it settles and hardens,
For those companies that already own, or are convinced that
they should construct, lagoons or impoundments for thickener
underflows, we believe that the superior properties of
Calcilox additive stabilized slurries might afford savings
in impoundment construction, and could greatly reduce
abandonment procedures. Several advantages, tangible and
intangible, for this type of operation could be:
A. Reduced initial capital outlay for dam construction.
B. Construction costs of the dam might be lower if
retaining wall structural considerations are used.
C. Impoundment would not be holding a fluid, but a
rigid mass.
891
-------
Figure - 7
PERMANENT IMPOUNDMENT STABILIZATION
892
-------
D. No devastating fluid mass movements could occur.
E. The impoundment offers an emergency reservoir to
which wastes can be dumped conveniently in the
event of an operating emergency in the preparation
plant.
Full-Scale Systems
In employing Calcilox stabilization of fine coal refuse,
the overall justification finally becomes one of economics.
It is very important to emphasize that many costs associated
with current disposal practices are obscure, since they are
included in other mine operations. Secondly, some factors
that readily affect a disposal operation are very intangible
and hard to equate to dollars and cents. Important consider-
ations are (1) the cost of maintaining private and public
roads due to slopping of fine refuse; (2) the time involved
in pulling equipment out of the muck; (3) low morale due to
bad working conditions - long hours in a messy environment
and (4) the constant threat of complete facility shutdown due
to regulatory spot checks. In a complete economic evaluation
of disposal costs, the above items plus others must be con-
sidered whether Calcilox is being evaluated or not.
Currently, Calcilox additive stabilization techniques are
in various stages of investigation by numerous companies
representing nearly 60,000 tons per day of cleaning capacity.
Refuse disposal modes under investigation will utilize vacuum
893
-------
disc filter cakes, solid bowl centrifuge cakes, and thickener
underflows to meet the specific objectives of the client com-
panies. At this time, three Calcilox additive stabilization
systems are in various stages of final construction, start-up,
and/or operation. All three are treating slurries ranging from
15% to 45% solids and are employing the interim pond stabilization
method with subsequent dry landfill disposal with the remaining
plant refuse. The following is an example of one of these
systems now in operation (the dollars shown are 1977 dollars).
Example 1: Disposal Mode - Interim pond disposal with subsequent
excavation and combination with remaining plant refuse.
Coal Use - Steam
Cleaning Capacity - 1300 TPH
Clean Coal - 1000 TPH
Fines Disposal Mode - 40 TPH (400 gpm @ 30% solids) as
thickener underflow and 40 TPH as filter cake combined
with coarse.
Current Overall Fines Disposal Costs per Ton Clean Coal. . $1.52
Approximate Calcilox System Capital Installed Cost . . . $80,000
Approximate Calcilox Additive Ddsage - 10%
Estimated Overall Fines Disposal Costs with Calcilox
Stabilization per ton Clean Coal $1.13
Estimated Net Disposal Savings with Calcilox
Stabilization per ton Clean Coal $0.39
(25%)
Estimated Calcilox Additive Cost per ton Clean Coal. . . . $0.32
thickener underflow only
$0.46
for all fines
894
-------
Figure 8, Calcilox Additive System, depicts the actual
installed treatment system. Briefly, the thickener underflow
enters the mix tank installed below a 100 ton Calcilox storage
silo. The Calcilox is metered into a waste slurry slipstream
via a prewetting cone with a variable speed rotary valve. The
mix tank is equipped with a twin-blade turbine agitator to
quickly disperse the Calcilox throughout the mix tank and to
maintain a uniform solids suspension. The mix tank is sized
to allow for a 10 to 20 minute retention time for all the
anticipated thickener underflow rates. The treated slurry is
then pumped to the interim settling ponds for 30 days curing
before excavation and dry landfill disposal with the remaining
plant refuse. The system is also equipped with various
ancillary devices to maintain uniform tank levels, bulk
Calcilox feed densities, and to assure safe and environmentally
acceptable operation of the system.
In this brief discussion, Calcilox additive stabilization
technology has been reviewed, stabilization methods presented,
and an actual Calcilox treatment system shown with its
associated costs. In stating these particular costs and for
estimating others, it should be reemphasized that the justifi-
cation for a Calcilox system involves costs that are tangible
and, to a great extent, intangible. A valid economic justifi-
cation for Calcilox stabilization should start with a thorough
investigation of your current fine coal refuse disposal costs.
895
-------
Figure - 8
CALCILOX ADDITIVE SYSTEM
896
-------
Important items that should not be overlooked in evaluating
these disposal costs are: (1) lost or reduced production due
to disposal problems; (2) possible reduction of flocculents
used for additional dewatering in settling ponds/ filters,
or centrifuges; (3) elimination of additional and/or special
equipment needed to maintain the disposal operation; and
(4) possible resale or reclamation of the Calcilox additive
stabilized fine coal refuse. This last point may be quite
applicable to refuses that possess a net BTU content in
excess of 5000 BTU/lb. Thus, with all these cost factors
evaluated, a sound economic decision can be made on the
application of Calcilox additive stabilization techniques
for fine coal refuse disposal.
897
-------
CHEMICAL AND BIOLOGICAL CHARACTERIZATION
OF LEACHATE FROM COAL CLEANING WASTES
R. M. Schuller1, R. A. Griffin1, and J. J. Suloway2
-'-Illinois State Geological Survey
2Illinois State Natural History Survey
Urbana, Illinois
ABSTRACT
Two coal-cleaning solid wastes—a low sulfur residue (LSR) and a high
sulfur residue (HSR)—from the Illinois Herrin (No. 6) coal member were
characterized mineralogically and chemically. The chemical solubility,
attenuation by soil, and toxicity of soluble constituents in a series of
aqueous leachate solutions at several pHs were determined.
The major chemical constituents of the solid residues were Al, Ca, Fe,
K, S, and Si (>1%). Ba, Cl, F, Mg, Mn, Na, Sr, Ti, and Zn were present at
concentrations between 100 and 10,000 ppm. Trace metals present in the
residues at concentrations between 10 and 100 ppm included As, Co, Cr, Cu,
Pb, and Ni; 20 additional elements were found at concentrations less than
10 ppm. Mineralogically the coal-cleaning wastes were similar; both included
illite, kaolinite, quartz, calcite, and Na-Ca feldspars. The notable
exception was the large pyrite concentration in the HSR.
Of the 60 chemical constituents determined in the solid wastes, 17 from
HSR and 20 from LSR were found to be soluble enough to exceed recommended
water quality levels within the pH range studied (2.5 - 9.2) and under these
laboratory test conditions. Most of these were soluble only when the pH was
quite acid. Three constituents in the HSR leachates (K, NH4, and 804)
exceeded recommended water quality levels in leachates of all pHs, while no
constituents in the LSR exceeded recommended levels at all pH values.
The attenuation study employed the dispersed soil methodology using three
widespread Illinois soils of varying character. Results showed a high degree
of attenuation of the major constituents; however, elution of Mg from the
soils themselves could possibly present the greatest potential for pollution
from land disposal.
Ninety-six-hour static bioassays were conducted with young fathead
minnows (Pimephales promelas) to determine the toxicity of these wastes
leachate solutions. Full-strength acidic leachates were acutely toxic and
neutral leachates were relatively nontoxic. However, acidic solutions of HSR
that were neutralized by dilution were still found to cause mortality. This
suggests a source of toxicity other than acidity.
898
-------
INTRODUCTION
In the United States almost 3 billion tons of carbonaceous
mineral wastes have accumulated as a result of coal mining
(National Academy of Sciences, 1975). With the projected increase
in coal as an energy source, the wastes are also projected to
increase. Of primary concern is the pollution potential of these
accumulations of coal waste. Regardless of how these wastes are
disposed of, they will eventually be exposed to leaching processes
that may make the soluble constituents available to the environ-
ment. In the case of pyritic wastes, the pollution potential
increases due to the production of sulfuric acid and its subse-
quent solubilization of metals. This increased acidity may affect
both the productivity of streams and lakes (Kemmel and Sharpe,
1976) and the fertility of the land around waste disposal sites
(National Academy of Sciences, 1975).
In order to ascertain the pollution potential of coal refuse,
it is desirable to determine: (1) the chemical and mineralogical
t
character of the solid waste, (2) the soluble phase of the solid
waste, (3) the attenuation characteristics in the environment of
the soluble constituents, and (4) the toxicity to biota of these
soluble constituents.
Characterization of the Coal Cleaning Wastes
Current Studies
This project is part of ongoing research by the Illinois
State Geological Survey to characterize coal and coal residues
(Ruch, Gluskoter, and Kennedy, 1971; Ruch, Gluskoter, and Shimp,
1973; Ruch, Gluskoter, and Shimp, 1974; Gluskoter, 1975; and
899
-------
Gluskoter et al., 1977). Included in this work is an analysls of
the pollution potential of coal solid wastes (Griffin et al., 1977)
The wastes being studied include liquefaction residues (SRC and
H-coal), Lurgi gasification ashes, fly ash, water quenched slag,
high and low temperature chars, and high and low sulfur cleaning
wastes (gobs). This report deals with the results from the coal
cleaning wastes and represents a small portion of the overall pro-
ject. The authors reserve the right to revise interpretation of
data upon completion of the project.
Chemical and Mineralogical Characterization
Two coal cleaning solid wastes—a low sulfur (LSR) and a high
sulfur residue (HSR)—from the Illinois Herrin (No. 6) coal member
were characterized chemically and mineralogically. The chemical
composition of the two wastes has been determined for approximately
60 constituents (Table 1). The major chemical constituents of the
solid residues were Al, Ca, Fe, K, S, and Si (>I%). Barium, Cl,
F, Mg, Mn, Na, Sr, Ti, and Zn were present in the residues at con-
centrations between 100 and 1000 ppm. Trace metals present in the
residues at concentrations between 10 and 100 ppm include AS, Co,
Cr, Cu, Pb, and Ni.
Mineralogically the coal cleaning wastes are similar; both
included illite, kaolinite, quartz, calcite, and Na-Ca feldspars.
The notable exception was the large pyrite concentration in the
HSR. The mineralogy was determined by X-ray diffraction, scanning
electron microscope, optical techniques, and chemical methods.
Aqueous Solubility
The solubility of constituents in the residues was determined
900
-------
Table 1: Chemical Characterization
of the Coal Cleaning Waste
Constituent
Ag
Al
As
B
Ba
Be
Br
Ca
Cd
Ce
Cl
Cr
Co
Cu
Cs
Eu
P-
Pe
total
Ga
Ge
Ef
K
La
Lu
Mg
Mn
Mo
Na
Ni
Pb
Solid ash
LSR
0.03
97,008
68
200
400
3
3.2
21,227
<1.8
100
700
78
13
36
15.2
1.5
900
24,813
19
4.1
7.9
17,102
50
0.43
3,859
310
<1
3,635
55
55
content (mg/kg)
HSR
0.20
56,572
13
9.3
300
2
1.2
28,159
<1.4
92
300
45.3
10.3
29
9.6
1.2
1,105
86,157
11
1.2
3.2
9,962
43
0.42
1,869
310
3.2
2,419
48
55
901
-------
Table 1: (cont'd)
Constituent
P
Rb
Stotal
0
pyritic
Sulfate
Sb
Sc
Si
Sm
Sn
Sr
Ta
Te
Th
Ti
Tl
U
V
W
Yb
Zn
Zr
Solid ash content (me/kc")
LSR
1,397
200
5,100
4,600
400
2.7
15.2
261,380
8
7.2
79
1.2
2.2
20
8,298
8.0
3.1
39.3
2.9
4.3
500
200
HSR
829
100
108,800
76,100
13,500
0.2
9.1
145,490
6.9
3.3
100
0.8
0.6
13
4,668
8.2
2.9
35.3
2.5
2.1
300
100
902
-------
by making 10% aqueous slurries. Duplicate sets of four slurries
each were adjusted to four individual pH values over the range of
2.5 to 9.2. Glass carboys (2.5 gal) were employed as reaction
vessels. One of the duplicate sets was equilibrated under an
argon (oxygen- and C02-free) atmosphere and the other set was equil-
ibrated under an air (oxidizing) atmosphere. The pH values were
monitored and readjusted to the specified values when necessary.
The slurries were monitored for 3 to 6 months or until the solu-
tion pH remained constant, at which time chemical equilibrium was
assumed.
Tables 2 and 3 list the elements from the solid residues that
were soluble enough to exceed recommended water quality levels
under the laboratory test conditions. The analyses were performed
by atomic absorption and colorimetric techniques (EPA Methods,
197*0. Table 2 compares the waste leachates at their natural pHs
and under both types of atmospheres. Table 3 compares the leachates
at their adjusted acidic pHs. Only K, NH^, and S04 exceed the
recommended levels in the HSR leachates at all pHs, while no con-
stituents of the LSR leachates exceeded recommended levels at all
pH values. The values listed in Table 3 represent what might be
expected under acid mine drainage (AMD) conditions. It is unlikely
that AMD would develop for the LSR waste due to its relatively low
sulfur content (0.51) compared to the HSR waste (10.8%). However,
AMD did not develop for the HSR waste under the experimental con-
ditions described above, and Table 3 represents only the result
of adjusting the leachate pH with nitric acid. The concentrations
in solution obtained by this adjustment fall well within the range
of values others have reported for typical AMD affected streams
903
-------
Table 2: Constituents Exceeding Recommended Water Quality Levels
in the Natural pH Supernatents under the Laboratory
Conditions (concentration in mg/1) y
Low Sulfur Residue High Sulfur Residue
Air Argon Air Argon
Constituent pH 8.6 8.5 7.5 7.4
Al 4.4 0.62 —
B 1.0 1.0
Ca — — 480 590
F 1.7 1-7 1.4 1.4
K — -- 11.9 15.5
Mn — 0.07
NH4 — — 0.3 1.5
Pb 0.15 ~ 0.2 0.15
POjj 0.08 0.06
SOjj — — 1600 1500
• . — . —
Recommended
Water Quality
Levels
0.1
0.75
50
1.0
5.0
0.05
0.02
0.03
0.05
250
904
-------
Table 3: Constituents Exceeding Recommended Water Quality Levels
in the Most Acid pH Supernatents under the Laboratory
Test Conditions (concentration in mg/1)
Low Sulfur Residue
Constituent
Al
Ba
Ca
Cd
Cr
Co
Cu
Fetotal
K
Mg
Mn
NH4
Ni
Pb
P04
SOj,
Zn
Air
pH 2.5
29.0
1.9
2595
0.09
0.06
0.64
1.68
130
38
119-7
24.4
4.5
1.06
0.50
3.0
—
1.55
Argon
pH 2.4
57.0
2.5
2784
0.09
0.13
0.48
1.34
360
40
138.9
30.7
4.9
—
0.70
44.0
—
1.40
High Sulfur Residue
Air
pH 2.6
27-6
—
2310
—
0.09
0.90
—
205
19
68.7
17.4
3.8
1.45
0.40
2.0
1300
3-7
Argon V
PH 2.5
35.3
—
2305
--
0.07
0.82
—
275
20
70.4
18.0
4.2
1.57
0.50
13.5
1400
3.1
Recommended
tfater Quality
Levels
0.1
1.0
50
0.01
0.05
0.05
0.2
0.3
5
50
.05
.02
1.0
0.03
0.05
250
0.2
905
-------
(Wllmoth, 1972; Hanson, 1972; and Gang and Langmuir, 197/1). The
most probable explanation is inadequate oxidation due to the slow
diffusion rate of air through water in the 2% gallon carboys
employed. Other possible explanations are the lack of ferric iron
in solution as a pyrite oxidizer and insufficient development of
bacterial activity.
It is difficult to explain the aqueous chemistry of a complex
system such as the coal refuse leachates. Possible complexation,
ion pair formation, and the effects of organic components on the
formation of organometallic complexes hinders the description of
these systems. However, it is still of Interest to examine them
in an effort to account for their soluble components, and of most
interest is the iron and sulfate chemistry.
Figure 1 is a plot of the Ca2* and SO^ ion activities for
the two aerated leachate systems. The plot indicates that while
the LSR leachates are undersaturated with respect to gypsum/ann-
hydrite, the HSR leachates are slightly supersaturated in all but
the most alkaline case. However, because of the range of error
in sulfate analyses and the use of solubility products calculated
for pure CaSOi, systems, it is quite possible that the HSR leachates
are within the range of saturation and are indeed in chemical
equilibrium with annhydrite. Further calculations show that Ba
and Sr in the LSRvleachates are undersaturated with respect to
their sulfate compounds with approximately 100? of the Ba and Sr
in the solid waste being in solution. The HSR solutions are also
undersaturated with respect to SrSOi+j where approximately 50?f of
the available Sr in the refuse is in solution.
Figure 2 is an Eh vs. pH diagram displaying the stability
relations of iron oxides and sulfides in water (Garrels and Christ,
906
-------
-0
Supersaturated
Undersaturated
-loga SO4=
Figure 1: Plot of calcium sulfate solubilities for aerated HSR
and LSR.
907
-------
+1.2-
O HSR Air
A HSR Argon
• LSR Air
A LSR Argon
-0.8
Figure 2: Stability relations of iron oxides and sulfides in
water at 25°C when ES=10~3 molar (native sulfur field
excluded).
908
-------
1965). There is a strong agreement between the Eh-pH values
plotted for the leachates and the Fe2 concentrations that were
measured experimentally. However, it is of interest to note that
the leachate systems (under both air and argon) are in the Fe2+-
hematite stability range. This indicates that the leachate sys-
tems are not in equilibrium with pyrite. The reason for the lack
of equilibrium is the slow rate of pyrite dissolution (oxidation)
as discussed above.
Attenuation Study
The traditional approach to studying earth material attenua-
tion of leachates or waste effluents has been experimentation using
soil column leaching. Rovers, Mooij, and Farquhar (1976) have
shown that a dispersed soil methodology or batch reactor technique
was suitable to approximate the behavior of contaminants of liquid
industrial wastes in soils at a considerable savings in time and
expense over soil column leaching studies.
The dispersed soil method has been shown to produce similar
results to both remoulded and undisturbed column leaching studies
(Rovers, MooiJ, and Parquhar, 1976). The technique involves mix-
ing a known volume of leachate with a known weight of soil brought
to field moisture capacity. This is repeated five times in series
with portions of leachate being drawn off and filtered for analy-
sis. Figure 3 is a schematic diagram of the methodology.
Three Illinois soils, Ava slcl., Catlin sil., and Bloomfield
Is., having a range of physical and chemical characteristics were
collected and characterized for use in this study. Table 4 gives
some of the pertinent characteristics of these soils.
909
-------
Addition of waste effluent followed
slugs of desorption water
VO
t->
O
R
e
a
c
t
o
r
R
e
a
c
t
o
r
R
e
a
c
t
o
r
R
e
a
c
t
o
r
R
e
a
c
t
o
r
soil
allquots for chemical analysis
Figure 3: Schematic diagram of dispersed soil methodology,
-------
Table 4: Soil Characteristics
Soil
Catlin
silt loam
Ava
silty clay
Bloomfield
loamy sand
pH
7.1
4.5
loam
5.7
CEC
(meq/lOOg)
18.1
13-1
0.8
Surface
Area, N~
(m2/gr
10.1
28.3
1.7
Organic
Carbon
(*)
4.73
1.18
0.21
Sand
(*)
11.6
2
82
Silt
(*)
60.9
69-6
10
Clay
(*)
27.2
28.4
8
-------
Only the natural pH supernatents are reported (LSR, pH 8.64
and HSR, pH 7-46). The filtrates from the attenuation study were
analyzed for Al, B, Ca, Fe, K, Mg, Mn, Na, SO^, and Zn. These ten
constituents were determined because they were present in the
leachates In sufficient concentration to present a potential pol-
lution hazard due to leaching through soil.
Mechanisms of attenuation for the leachate constituents
include adsorption, ion exhcange, complexatlon, precipitation,
oxidation-reduction and many physical and biological mechanisms
such as filtering and degradation. Usually attenuation in a com-
plex system is a result of not just one but several of these pos-
sible mechanisms (Phillips and Nathwani, 1976). In general adsorp-
tion and precipitation are the principal mechanisms for removal of
organic constituents. Also, the higher the clay and/or organic
content of a soil the more effective the material is as an atten-
uating medium.
Tables 5 and 6 list the results of the attenuation analyses.
The LSR leachate-soll mistures resulted in elution of Ca, K, and
Mg from the three soils and Mn from the Ava soil. Only Na was
consistently removed from solution. The HSR leachate-soil mixtures
(Table 6) also resulted in elution of Mg but to a lesser extent
and again elution of Mn from the Ava soil. All other constituents
were attenuated.
The overall attenuation and elution of potential contaminants
for the mixtures follows the same trend as the cation exchange
capacity of the soils: Catlin >_ Ava > Bloomfield. However, it
is doubtful that exchange is the only mechanism responsible for
rt
removal. In the HSR leachate-soil mixtures, Ca * and SO4* are in
912
-------
Table 5: Results of Attenuation Analysis for LSR Including
Original Leachate Concentrations81
Constituent
pH
ECb
Ca
K
Mg
Mn
Na
so4
Waste
leachate
8.6
0.74
1.8
3.8
4.6
<.03
200
112
Ava
4.2
0.36
5-5
5-6
113-0
0.33
36
44
Bloomfield
6.7
0.62
20.7
9.9
70.4
<.03
104
102
Catlin
6.9
0.73
47.5
6.6
231.0
<.03
17
139
Concentrations in mg/1
millimhos/cm
913
-------
Table 6: Results of Attenuation Analysis for HSR Including
Original Leachate Concentrations+a
Constituent
pH
ECb
Ca
K
Mg
Mn
Na
S04
Waste
leachate
7.5
2.40
612
1.5
31.8
<.03
192
2254
Ava
4.0
0.87
69
0.9
56.8
1.2
65
305
Bloomfield
7.3
1.87
392
1.6
42.9
<.03
106
1203
Catlin
6.8
1.38
282
1.0
58.9
• <.03
27
644
o
Concentrations in mg/1
millimhos/cm
914
-------
solution In saturation with respect to CaSOit'2H20 (gypsum), which
would indicate that their steady decrease in concentration through
the reactor series is due to precipitation of gypsum. Due to the
high ratio of leachate employed to soil moisture content, dilution
is not considered to be a significant mechanism of removal.
Toxicity Studies
Ninety-six hour static bioassays were conducted with young
fathead minnows (Plmephales promelas) to determine the toxicity of
these waste leachate solutions. The toxicity tests were divided
into two phases: the screening procedure and the LC-50 determina-
tion. During the screening procedure, the young fathead minnows
were exposed to the full-strength leachates; in the LC-50 determin-
ations, the minnows were exposed to full-strength leachates diluted
with soft reconstituted water prepared as suggested in "Methods
for Acute Toxicity Tests with Pish, Macroinvertebrates, and Amphib-
ians" (The Committee on Methods for Toxicity Test with Aquatic
Organisms, 1975). Procedures outlined in Litchfield and Wilcoxon
(1949) were used for LC-50 determinations.
Ten young fathead minnows were placed Into glass fingerbowls
(115 x 45 mm) containing 200 ml of full-strength or diluted lea-
chate. Each bioassay was replicated. Fish mortality data were
collected at 24, 48, 72, and 96 hours after the bioassays were
begun. The test organisms were not fed and the solutions were not
aerated during the bioassays. Since one-half of the leachates
were equilibrated under anaerobic conditions, all solutions were
aerated before the fish were added. The bioassays were conducted
at a constant temperature (21° + 1°C) and with a constant photo-
915
-------
period (16L-8D) in an environmental chamber. At the beginning and
end of all bioassays, pH and dissolved oxygen readings, were taken.
Specific conductance was measured at the beginning of each bio-
assay.
The results of the screening procedure are depicted in Figure
4. Leachates of neutral pH (6.8 - 8.0) are relatively nontoxic.
Total mortality occurs in acidic (pH <6.2) solutions.
The LC-50 values, their 95 percent confidence intervals, and
dilutions necessary to eliminate mortality are listed in Table 7-
The pH values listed are the pHs of full-strength leachates after
they were aerated and before they were diluted with reconstituted
water. There is an inverse relationship between toxicity and the
LC-50 value. For example, the LC-50 values for HSR3 and HSR^ are
41.00 and 3.00, respectively (Table 7). Forty-one milliliters of
HSRs diluted with 59 ml of reconstituted water is as toxic as 3.00
of HSRi+ diluted with 97 ml of reconstituted water. Thus, leachates
exhibiting greater toxicity have lower LC-50 values than less toxic
leachates. If, in full-strength solutions, less than 50$ mortality
occurred, the LC-50 is reported as greater than 100 ml/100 ml.
Generally, all leachates are acutely toxic when acidic (pH
«6.2) and with increasing acidity there is an increase in toxicity
and a decrease in the LC-50 value. The natural pH leachates (LSRj,
LSR5, HSR2, and HSR6) are not acutely toxic and do not require a
dilution to eliminate mortality (Table 7). The LC-50 values for
anaerobic leachates are not significantly different from sililar
aerobic solutions (p <.05, paired t-test).
Many factors probably contribute to the acute toxicity of
the acidic leachates. It has been shown (Griffin et al., 1977)
916
-------
100-1
on*
80-
>.60-
o
40-
20-
• HSR Argon
O HSR Air
• LSR Argon
D LSR Air
T
3
"T
4
T
5
T
7
8
pH
T
9
-I
10
Figure 4: Plot of percent mortality vs. pH for HSR and LSR leachates
-------
Table 7: LC-50 Values for LSR and HSR Leachates
Sample
*LSR1
LSR2
LSR3
LSR4
*LSR5
LSR6
LSR?
LSRg
HSR1
*HSR2
HSR3
HSR4'
HSR5
*HSR6
HSR?
HSRg
u
Atmosphere
aerobic
aerobic
aerobic
aerobic
anaerobic
anaerobic
anaerobic
anaerobic
aerobic
aerobic
aerobic
aerobic
anaerobic
anaerobic
anaerobic
anaerobic
pH
8.8
7.9
5.4
3.8
8.9
7-7
6.6
4.0
8.1
7.7
3.5
2.7
8.0
8.0
3.9
2.6
LC-50
ml/100 ml
>100
>100
57-00 + 2.28
3.80 +_ 0.41
>100
>100
96.00 + 0.83
2.15 + 0.16
>100
>100
41.00 +_ 2.87
3.00 + 0.62
>100
>100
56.00 + 2.52
2.30 + 0.14
Dilution for
zero mortality
1:1
1:1
1:3
1:50
1:1
1:1
1:1
1:100
1:1
1:1
1:4
1:67
1:1
1:1
1:2
1:67
Natural pH
918
-------
that reconstituted water of low pHs (pH <5.9) will cause total
mortality. Since the young fathead minnows were propagated and
held at pH 7.4 and experienced a rapid change in pH, the mortality
was partially due to "ionic shock." However, some acidic solutions
of HSR that were neutralized by dilution were toxic. Upon neutral-
ization, a ferric hydroxide precipitate was formed; this precipi-
tate adhered to the mucus of the gills and resulted in suffocation.
Mortality, reduced fry survival, slower growth, and reduced hatch-
ability have been observed in other investigations of the effects
of ferric hydroxide precipitates on fish (Sanborn, 19^5; Sykora
et al., 1972; and Smith et al., 1973).
The effects of other constituents are more difficult to assess.
Although the concentrations of most of the constituents are far
below LC-50 values established in previous studies for single con-
stituents (Eaton, 1973; Pickering, 1974; and Pickering and Gast,
1973)> these constituents could act synergistically and thus would
contribute to the acute toxicity of the acidic leachates. The natu-
ral pH leachates are not acutely toxic; however, the chronic toxic-
ity of these leachates has not been examined. Single constituents
such as Ca, K, Pb, and Mn, which are found in relatively high but
not acutely toxic concentrations in the natural pH leachates,
could be chronically toxic when acting synergistically.
SUMMARY
The pollution potential from the disposal of coal cleaning
wastes is of concern, if not because of the nature of the waste
then because of the enormous quantity of the waste generated. In
order to evaluate this pollution potential it is necessary to char-
acterize both the solid waste and the leachate that it is capable
919
-------
of generating. It Is then necessary to determine how the constit-
uents can be removed from the leachate and how these constituents
will effect the biota If they are not removed.
The study of two Illinois coal cleaning wastes has shown that:
1. Contamination from the wastes Is most severe under acid condi-
tion.
2. Land disposal of the wastes may result in pollution by elution
of contaminants from the soils themselves.
3. Toxiclty to biota is not a function of acidity alone, but may
also be due to the formation of precipitates during neutrali-
zation.
ACKNOWLEDGEMENTS
We gratefully acknowledge the U.S. Environmental Protection
Agency, Energy Assessment and Control Division, Fuel Process Branch
Research Triangle Park, North Carolina, for partial support of this
work under Contract 68-02-2130, Characterization of Coal and Coal
Residue.
The authors wish to thank S. J. Russell, A. A. Debus, and the
Analytical Chemistry Section of the Illinois State Geological Sur-
vey, under the direction of Dr. R. R. Ruch, for assistance in por-
tions of this research.
920
-------
REFERENCES
Eaton, J. G. 1975- Chronic toxiclty of a copper, cadmium, and
zinc mixture to the fathead minnow (Pimephales promelas) .
Wat. Res. 7:1723-1726.
Gang, M. W. , and D. Langmuir. 1970. Controls of heavy metals in
surface and ground waters affected by coal mine drainage.
Clarion River - Red Bank Creek Watershed, Pennsylvania, Fifth
Symposium on Coal Mine Drainage Research, Louisville, Kentucky,
pp. 3-70.
Garrels, R. M. , and C. Christ. 1965. Minerals, solutions and
equilibria. Harper and Row, New York.
Gluskoter, H. J. 1975. Mineral matter and trace elements in coal,
in Babu, ed., Trace Elements in Fuel, Advances in Chemistry
Series 1^1, American .Chem. Soc. p. 1-22.
Gluskoter, H. J. , R. R. Ruch, W. G. Miller, R. A. Cahill, G. B.
Dreher, and J. K. Kuhn. 1977. Trace elements in coal: Occur-
rence and distribution. Illinois State Geological Survey Cir-
cular
Griffin, R. A., R, M. Schuller, J. J. Suloway, S. J. Russell, W.
F. Childers, and N. F. Shimp. 1978. Solubility and toxicity
of potential pollutants in solid coal wastes. EPA-6QO/7-78-
063, April (1978). Environmental Protection Technology Series
Hanson, P. J. 1972. Foam separation of metals from acid mine
drainage. Fourth Symposium on Coal Mine Drainage Research,
Pittsburgh, Pennsylvania, pp. 157-179.
Kimmel, W. G., and W. E. Sharpe . 1976. Acid drainage and the
stream environment. Trout 17(1): 21-5.
Litchfield, J. T., Jr., and F. Wilcoxon. 19^9. Simplified method
of evaluating dose-effect experiments. J. Pharm. Exp. Thes.
96:99-113.
Methods for acute toxicity tests with fish, macroinvertebrates, and
amphibians. 1975. Committee on Methods for Toxicity Tests
with Aquatic Organisms, National Water Quality Labs., EPA,
Duluth, MM, EPA-660-3-75-009, P. B. 0 242-105/AS.
National Acadamey erf Sciences. 1975. Underground disposal of coal
mine wastes. Report to the National Science Foundation,
Washington, D.C.
Phillips, C. R., and J. Nathwanl. 1976. Soil waste interactions:
A state of the art review, report EPS 3-EC-76-14, Environment
Canada, October (1976)
Pickering, Q. H. 1971*. Chronic toxicity of nickel to the fathead
minnow. J. Wat. Poll. Cont . Fed. 46:760-766.
921
-------
Pickering, Q. H., and M. H. Gast. 1972. Acute and chronic tox-
icity of cadmium to the fathead minnow (Plmephales promelas).
J. Fish. Res. Bd. Can. 29-1099-1106.
Rovers, F. A., H. Mooij, and G. J. Farquhar. 1976. Contaminant
attenuation - Dispersed soil studies. EPA-600/9-76-015,
July (1976). pp. 224-234.
Ruch, R. R., H. J. Gluskoter, and E. J. Kennedy. 1971. Mercury
content of Illinois coals. Illinois State Geological Survey
Environmental Geology Note 43, 15 p.
Ruch, R. R. , H. J. Gluskoter, and N. F. Shimp. 1973. Occurrence
and distribution of potentially volatile trace elements in
coal: An interim report. Illinois State Geological Survey
Environmental Geology Note 6l, 43 p.
Ruch, R. R., H. J. Gluskoter, and N. F. Shimp. 1974. Occurrence
and distribution of potentially volatile trace elements in
coal: A final report. Illinois State Geological Survey
Environmental Geology Note 72, 96 p.
Sanborn, N. H. 1945. The Lethal effect of certain chemicals on
freshwater fish. Canning Trade 67, (49): 10-12 and 26.
Smith, E. J., J. L. Sykora, and M. A. Shapiro. 1973. Effect of
lime neutralized iron hydroxide suspensions on survival,
growth and reproduction of the fathead minnow. J. Fish. Res
Bd. Can. 30:1147-1153.
Sykora, J. E., J. Smith, M. A. Shapiro, M. Synab. 1972. Chronic
effect of ferric hydroxide on certain species of aquatic
animals. Fourth Symposium on Coal Mine Drainage Research,
Pittsburgh, Pennsylvania, pp. 347-370.
U.S. Environmental Protection Agency. 1974. Methods for Chemical
Analyses of Water and Wastes, EPA-625/5-74-003.
Wilmoth, R. C., D. G. Mason, M. Gupta. 1972. Treatment of fer-
rous iron acid mine drainage by reverse osmosis. Fourth
symposium on Coal Mine Drainage Research, Pittsburgh, Penn-
sylvania, pp. 115-157.
922
-------
INTRODUCTION TO CHEMICAL COAL CLEANING
R. A. Meyers
TRW Systems and Energy
Redondo Beach, California
INTRODUCTION
Some specific methods for the chemical removal of sulfur from coal are
going to be presented in this symposium. I will attempt to present a statement
of the problem associated with finding effective and economic routes to the
desulfurization of coal, indicate some of the pitfalls of experimentally
investigating sulfur removal in coal and present a very recent example of
removal of both inorganic and organic sulfur from the same coal. I plan to
emphasize the removal of organic sulfur from coal as there are now several
methods for removal of pyritic sulfur, but, in my opinion, no certain method
for the removal of organic sulfur has been published to date other than
hydrogenation under coal liquefaction conditions.
Many of the figures will be taken from my book Coal Desulfurization,
'-^
which was recently published by Marcel Dekker, Inc.- and the experimental
examples are from our laboratories.
This presentation will consist of four sections: coal molecular structure
and reactivity, sulfur removal mechanisms, criteria for economic success and
an example of chemical removal of both pyritic and organic sulfur to potentially
meet the revised NSPS requirements.
923
-------
COAL MOLECULAR STRUCTURE
A model of the organic coal matrix, proposed by G1venv ' 1s shown 1n
Figure 1. Given later assessed the available knowledge on the structure
of the organic sulfur units present 1n coal, concluding that mercaptans,
sulfldes, dlsulfldes and thlophenes were the major organic sulfur containing
(3)
functional groupsx '. The Inorganic portion of coal consists of a vast
number of minerals 1n discrete agglomerations and often Intimately associated
with the organic coal matrix. The Inorganic sulfur 1n coal occurs mainly
as the mineral pyrlte with small amount of Inorganic sulfate minerals such
as melanterUe, jaroslte and gypsum.
These Inorganic forms can be removed either partially or totally by a
number of published methods, some of which will be presented at this sym-
posium. The removal of the organic sulfur has proved to be very difficult,
as the compounds are not just Intimately associated with the organic coal
matrix, they are chemically bonded Into the core of the carbon structure.
Removal of these compounds necessarily requires a partial breakdown of the
organic coal matrix.
SULFUR REMOVAL MECHANISMS
Potential methods for the removal of organic sulfur from coal have
been classified Into six groups as shown 1n Figure 2.a-c. These are:
solvent partition, thermal decomposition, add base reaction, reduction,
oxidation and displacement. These mechanisms all have the common feature
of being potentially capable of removing the organic sulfur content of
coal as small soluble or volatile molecules, containing a prepondance of
sulfur. Of these mechanisms, only reduction (with hydrogen) has been
clearly shown to be effective up to the present ^ '
924
-------
vC
fO
Ul
H2
H2
SH
CH, H2
FIGURE 1. MODEL OF ORGANIC COAL MATRIX
-------
1. SOLVENT PARTITION
1 X 7"*" ^ ~"*
R1
R2
SX X
(Eq. 6)
VO
10
2. THERMAL DECOMPOSITION
i Sv Ro A
RCH2 CH2 SH RCH = CH + H
(Eq. 81
FIGURE 2.a. ORGANIC SULFUR REMOVAL MECHANISMS
-------
VO
to
3. ACID-BASE NEUTRALIZATION
RSH + OH" - RS" + H20
4. REDUCTION
R,SXR2 + 4H - R,H + R2H
R,SXR2
H2 - R,H
(Eq. 9)
(Eq. 10)
(Eq. II)
FIGURE 2.b. ORGANIC SULFUR REMOVAL MECHANISMS (Continued)
-------
vo
K3
OO
5. OXIDATION H 0
RISXR2 ~" R| S03H + R2 S03 H - R, OH + R2 OH + 2H2 S04 (Eq. 12)
6. NUCLEOPHILIC DISPLACEMENT
R|SXR2 + Nu" - R,SX Nu + R2~ (Eq. 13)
R|SXR2 + Nu" - R,SX_, Nu + R2S" (Eq. 14)
R,SXR2 4 Nu" - R,SX" + R2 Nu (Eg. 15)
R2S" + R,SX_, Nu - R|SX-|R2 + Nu S"
TAKEN FROM: R. A. MEYERS, COAL DESULPJRtZATION, MARCEL DEKKER, INC. (1977)
FIGURE 2.c. ORGANIC SULFUR REMOVAL MECHANISMS (Continued)
-------
Potential pyrlte removal reactions have also been categorized. These
Include: displacement, add base neutralization, oxidation and reduction^1).
Of these, only the displacement mechanism has not been demonstrated.
CRITERIA FOR SUCCESSFUL CHEMICAL DESULFURIZATION PROCESSES
The major criteria for economic removal of either Inorganic or organic
sulfur from coal are shown 1n Figure 3. The desulfurlzatlon reagent must
be selective and not significantly react with other coal components. The
reagent should be regenerable and be either soluble or volatile so 1t can
be recovered from the coal matrix. Finally, the reagent should be Inexpensive
since a portion of 1t will certainly be lost to either Irreversible sorptlon
on the coal matrix or by reaction.
AN EXAMPLE OF REMOVAL OF BOTH PYRITIC AND ORGANIC SULFUR FROM THE SAME COAL
One of the methods discussed 1n Coal Desulfurlzatlon^ was examined
experimentally In our laboratories for removal of both pyrltic and organic
sulfur from a high sulfur coal. A well characterized sample of Kentucky
No. 9 seam coal was selected for the substrate as 1t contained a total of
6.8 Ib of S02/106 Btu of which half was Inorganic and half organic (Figure
4 - Example 1). Treatment of this coal for 30 minutes results 1n removal
of 38+15% of the organic sulfur and a large part of the pyrltic sulfur
(Example 2). However, these results were actually not particularly
encouraging as the organic sulfur removal, even at "38X", Is only barely
significant 1n view of error associated with analysis. Further, the re-
maining total sulfur level of 2.3 Ib S02/106 Btu 1s not close to meeting
federal standards.
929
-------
to
REAGENT SELECTIVITY TOWARD SULFUR COMPOUNDS IN COAL
REGENERATION TO THE INITIAL FORM
SOLUBLE; VOLATILE OR OTHERWISE RECOVERABLE REAGENTS
AND PRODUCTS
INEXPENSIVE - SOME LOSS INEVITABLE
FIGURE 3. CRITERIA FOR SUCCESSFUL CHEMICAL DESULFURIZATION PROCESSES
-------
Example
1
2
3
4
Coal
Run-of-Mlne
Run-of-Mlne
Gravl -Float
Grav 1- Float
Treatment
None
Yes
None
Yes
st
6.8 +0.4
2.3 + 0.3
3.2 +0.3
0.8 + 0.4
Sulfur Content, lb/106 Btu
SP Ss
3.1 +0.2 0.6 +0.2
0.3 + 0.2 0.1 + 0.2
0.2+0.2 0.3+0.2
0.2 + 0.2 0.0 + 0.2
So
3.1 +0.3
1.9 + 0.3
2.8+0.3
0.6 +0.3
Organic
Sul fur
Removal
38X +15%
77% + 17%
30-mln extraction time
FIGURE 4. ORGANIC SULFUR REMOVAL FROM KENTUCKY NO. 9 COAL*
-------
Analysis of the coal ash Indicated that there was significant reaction
of the selected reagent with the mineral component of the coal. Therefore,
1t was decided to Investigate the desulfurlzatlon reaction on "gravl-float"
coal which Is extremely low In ash. Gravl-float coal Is obtained by float-
sink separation of coal In Iron sulfate leach solution at specific gravity
1.3-1.4, followed by washing with water to remove residual sulfate and
additional ash. The resulting coal (Example 3) has an ash content of only
3-4X, whereas the run-of-mlne Kentucky No. 9 coal has an ash content of
about 125L Further, there Is essentially no pyrlte 1n the coal. Thus, the
chances for consumption of the reagent by reaction with the mineral matter
Is greatly reduced.
*
Indeed, treatment of gravl-float coal under conditions Identical to
those of the run-of-m1ne coal (Example 4) resulted 1n removal of 77+17X of
the organic sulfur and a total sulfur content of 0.8 Ib S02/10 Btu. This
corresponds to an overall 85* reduction In sulfur content starting with run-
of-mlne coal. There are a number of parameters which must be evaluated to
allow economic assessment. These Include: reagent loss, coal recovery,
energy balance, etc. Thus, a good deal of bench-scale experimentation and
engineering and economic evaluation Is needed before this method can be
considered for meeting New Source Performance Standards. However, the
results obtained to date Indicate that It may be possible to meet standards
by pretreatment of coal.
932
-------
REFERENCES
1, Meyers, R, A, Coal DesulfuHzatlon, Marcel Dekker, Inc., New York,
1977.
2. Given, P. H, Fuel. 39:147, 1960.
3. Given, P. H. and W. F. Wyss. Brit. Coal Utilization Research Association
Monthly Bulletin. 25:165, 1961.
4. Meyers, R, A,, J. W. Hamersma, R. M. Baldwin, J. G. Handwerk, J. H. Gary
and 0. 0. Golden. Energy Sources. 3(1):13, 1976.
933
-------
CURRENT STATUS OF CHEMICAL COAL
CLEANING PROCESSES - AN OVERVIEW
L. C. McCandless and Mrs. G. Y. Contoa
Veraar, Inc.
Springfield, Virginia
ABSTRACT
A variety of chemical coal cleaning processes are under development which
will remove a ma.loritv of pyritic sulfur from coal with acceptable heating
value recovery, i.e., 95 percent Btu recovery. Some of these processes are
also capable of removing organic sulfur from the coal, which is not possible
with physical coal cleaning methods. Chemical coal cleaning processes at the
bench scale level have demonstrated removal of as much as 95 to 99 percent
of pyritic sulfur and up to about 40 percent of the organic sulfur from the
run-of-mine coal. It is projected that this removal efficiency could result
in total sulfur reductions in U.S. coals in the range of 53 to 77 percent.
This paper presents available technical and economic information on major
U.S. chemical coal cleaning processes identified during an eight-month study,
conducted for the Industrial Environmental Research Laboratory of EPA at
Research Triangle Park, North Carolina.
934
-------
1.0 INTRODUCTION
What role should Chemical Coal Cleaning Processes play in
the scenario of maximizing coal utilization without environmental
deterioration? The National Energy Policy and the 1977 Clean
Air Act Amendments require that more coal be burned, but with
reduced sulfur emissions.
The current options for decreasing sulfur emissions from
the combustion of coal are:
• pretreatment fuel processing including physical and
chemical coal cleaning;
• synthetic fuels production;
• fluidized bed combustion; or
• post-combustion control technology, namely flue gas
desulfurization.
Only flue gas desulfurization and physical coal cleaning are
commercially available.
935
-------
Physical coal cleaning can remove 60 to 90 percent of the
pyritic sulfur or some- 40 to 70 percent of the total sulfur in
the raw coal, but cannot remove the organic sulfur„ However,
one problem with mechanical "deep" coal cleaning is that carbon
values (BTU's) are removed with the sulfur and ash, which can
result in rejecting as much as 40 percent of the total energy
value of the coal.
Chemical coal cleaning processes, now being developed,
remove as much as 95 percent of the mineral sulfur and up to
about 40 percent of the organic sulfur. This results in
removal of some 50 to 80 percent of the total sulfur in the
raw coal.
Twenty-nine chemical coal cleaning processes were identified
during an eight month technology overview study conducted for
the Industrial Environmental Research Laboratory of EPA at
Research Triangle Park, North Carolina. Eleven U.S. developed
processes were classified as major processes during this study,,
This paper presents a summary of available technical and
economic information on these processes'based upon Versar's
assessment, conceptual designs and costing.
2oO SUMMARY OF TECHNICAL AND COST INFORMATION FOR MAJOR
CHEMICAL COAL CLEANING PROCESSES
Table 1 shows a listing of the major processes- The first
four processes listed (Magnex, Syracuse, TRW, and Ledgemont)
will remove pyritic sulfur only; the remaining seven processes
936
-------
TABLE 1. SUTIARY OF MAJOR CHEMICAL COAL CLEANING PROCESSES
PROCESS S
SPONSOR
"MAGNEX",®
HAZEN RESEARCH
INC,, GOLDEN
COLORADO
"SYRACUSE"
SYRACUSE
RESEARCH CORP,,
SYRACUSE, N.Y,
"MEYERS", TRW,
INC, REDONDO
BEACH, CAL,
"LOU' KENNECOTT
COPPER CO,
LEDGEMONT, MASS,
METHOD
DRY PULVERIZED COAL
TREATED WITH FE
(C0>5 CAUSES PYRITE
TO BECOME MAGNETIC.
MAGNETIC MATERIALS
REMOVED MAGNETICALLY
COAL IS COMMINUTED
BY EXPOSURE TO NH3
VAPOR; CONVENTIONAL
PHYSICAL CLEANING
SEPARATES COAL/ASH
OXIDATIVE LEACHING
USING FE2(S04)3 +
OXYGEN IN WATER
OXIDATIVE LEACHING
USING Oj AND WATER
8 MODERATE TEMP.
AND PRESSURE
TYPE SULFUR
REMOVED
UP TO 90%
PYRITIC
50-705
PYRITIC
90-95%
PYRITIC
90-95%
PYRITIC
STAGE OF
DEVELOPMENT
-l
BENCH & 91 KG/DAY
(200 LB/DAY) PILOT
PLANT OPERATED
BENCH SCALE
8 METRIC TON/DAY
PDU FOR REACTION
SYSTEM. LAB OR
BENCH SCALE FOR
OTHER PROCESS
STEPS.
BENCH SCALE
PROBLEMS
DISPOSAL OF S-CONTAIN-
ING SOLID RESIDUES.
CONTINUOUS RECYCLE OF
CO TO PRODUCE FE
(C0)5 REQUIRES
DEMONSTRATION
DISPOSAL OF SULFUR
CONTAINING
RESIDUES.
DISPOSAL OF ACIDIC
FES04& CAS04, SULFUR
EXTRACTION STEP
REQUIRES DEMONSTRA-
TION
DISPOSAL OF GYPSUM
SLUDGE. ACID
CORROSION OF
REACTORS
ANNUAL OPERATING
COST $/TON CLEAN
COAL INCLUDING
COST OF COAL
40.7
37.0
43.4
4R q
HO. j
RAW COAL COST IS INCLUDED AT $25/TON.
-------
(ERDA, GE, Battelle, JPL, IGT, KVB, and ARCO) claim to remove
most of the pyritic sulfur and varying amounts of organic
sulfur. Also, the first two processes are unique in that
the coal is chemically pretreated, then sulfur separation is
subsequently achieved by mechanical or magnetic means. The
remaining nine processes are more typical in that sulfur
compounds in the coal are chemically attacked and converted.
A capsule summary of each major process follows.
MAGNEX PROCESS
Pulverized (minus 14 mesh) coal is pretreated with iron
pentacarbonyl, in this process to render the mineral components
of- the coal magnetic. Separation of coal from pyrite and
other mineral elements is then accomplished magnetically. The
process has been proven on a two hundred pound/day pilot plant
scale using the carbonyl on a once-through basis. The cost
of the Magnex process critically depends on the recycle of
iron carbonyl. It is claimed that iron carbonyl can be
produced on-site from carbon monoxide released in the process.
However, the continuous recycle of carbon monoxide to produce
low cost iron carbonyl requires demonstration. The use of
iron carbonyl presents some difficulties from a health and
safety standpoint. Approximately 40 coals, mostly of Appalachian
origin, have been evaluated on a laboratory scale. For
the most part, the process will produce coals which meet
938
-------
TABLE i. suwnr OF mxR OBWCAL OWL CLEWING PROCESSES
PROCESS &
SPONSOR
"ERDA" (PERC)
BRUCETON, PA.
"GE* GENERAL
ELECTRIC CO.,
VALLEY FORGE,
PA.
2 "SATTELLE*
* LABORATORIES
coumjs, OHIO
"JPL* JET
PROPULSION
LABORATORY
PASADENA/ CAL.
*IGT* INSTITUTE
OF GAS
TECHNOLOGY
CHICAGO, ILL.
METHOD
AIR OXIDATION &
WTER LEACHING 8
HIGH TEMPERATURE
AND PRESSURE
MICROWAVE TREATMENT
OF COAL PERMEATED
WITH HAOH SOLUTION
CONVERTS SULFUR
FORMS TO SOLUBLE
SULFIDES
MIXED ALKALI
LEACHING
CHLORINOLYSIS IN
ORGANIC SOLVENT
OXIDATIVE PRETREAT-
MENT FOLLOHED BY
HYDRpDESULFURIZATION
TYPE SULFUR
REMOVED
'X9BZ PYRITIC;
UPTOtjQZ
ORGANIC
^755 TOTAL S
MEE PYRITIC;
^25-5QZ ORGANIC
•^SKfYRITIC; UP
TO 701 ORGANIC
''SSLPYRITIC; UP
TO 8St ORGANIC
STAGE OF
DEVELOPMENT
BENCH SCALE H KG/
DAY (25 LB/DAY)
CONTINUOUS UNIT
UNDER CONSTRUCTION
BENCH SCALE
9KG/HR (20 LB/
HR) MINI PILOT
PLANT AND BENCH
SCALE
LAB SCALE BUT
PROCEEDING TO
BENCH AND MINI
PILOT PLANT
LAB AND BENCH
PROBLEMS
GYPSUM SLUDGE DISPOSAL
ACID CORRROSION AT
HIGH TEMPERATURES
PROCESS CONDITIONS
NOT ESTABLISHED
CAUSTIC REGENERATION
PROCESS NOT
ESTABLISHED.
CLOSED LOOP REGENERA-
TION PROCESS UNPROVEN.
RESIDUAL SODIUM IN
COAL
ENVIRONMENTAL
PROBLEMS. CONVER-
SION OF HCL TO 0_2
NOT ESTABLISHED
LOHBTU YIELD (<55Z).
CHANGE OF COAL MATRIX
ANNUAL OPERATING
COST $/TON CLEAN
COAL INCLUDING
COST OF COAL
51.6
41.8
55.9
46.0
55.3
*RAW COAL COST IS INCLUDED AT $25/TON.
-------
TABLE 1. SUTORY OF MftJOR OB1ICAL COAL CLEftNING PROCESSES
PROCESS 8
SPONSOR
HAZEN RESEARCH
INC.; GOLDEN
pbLORADO
£ v "SYRACUSE" -
SYRACUSE
RESEARCH CORP.,
SYRACUSE, N.Y.
v_
1-\ ."MEYERS", TRW,
' " INC. REDONDO
BEACH, CAL.
VJSB^
^Wil^^'i
METHOD
DRY PULVERIZED COAL
TREATED WITH FE
(C0)5 CAUSES PYRITE
TO BECOME MAGNETIC.
MAGNETIC MATERIALS
REMOVED MAGNETICALLY
COAL IS COMMINUTED
BY EXPOSURE TO N^
VAPOR; CONVENTIONAL
PHYSICAL CLEANING
SEPARATES COAL/ASH
OXIDATIVE LEACHING
USING FE2(S04;3 +
OXYGEN IN WATER
OXIDATIVE LEACHING
USING 02 AND HATER
- 8 MODERATE TEMP.
AND PRESSURE
TYPE SULFUR
REMOVED
UPt69(K
PYRITIC
PYRITIC
90-96%
PYRITIC
\
PYRITIC
STAGE OF
DEVELOPMENT
BENCH ft 91 K6/HR
(200LB/HR) PILOT
PLANT OPERATED
BENCH SCALE
8 METRIC TON/DAY
PDU FOR REACTION
SYSTEM. LABOR
BENCH SCALE FOR
OTHER PROCESS
STEPS.
BENCH SCALE
PROBLEMS
DISPOSAL OF S-CONTAIN-
ING SOLID RESIDUES.
CONTINUOUS RECYCLE OF
CO TO PRODUCE FE
(C0)5 REQUIRES
DEMDNSTRATiON
DISPOSAL OF SULFUR
CONTAINING
RESIDUES.
DISPOSAL OF ACIDIC
FESO4& CASO^o SULFUR
EXTRACTION STEP
REQUIRES DEMONSTRAT
TION
DISPOSAL OF GYPSUM
SLUDGE, ACID
CORROSION OF
--mcnK^ --:••; --: ;
ANNUAL OPERATING
COST */TON CLEAN
COAL INCLUDING
CO
•
.;
,
i
!
- 1
'.
^^AJSKl^ ^ , -__ ' \ „ ^ *RAW COAL COST 1$ INCLUDED AT IS/TON. > ^Y:/- . V v'i V'"^'W- "• ; ^C?"
fcl W OML
37.0
i - "• - -" . :
i . .
•-1- . • ' • .• '-
**^K-
|;^«?
-------
State regulations for sulfur dioxide emissions of 4.3 kg
S02/106 kg cal (2.4 Ib S02/106 BTU).
SYRACUSE PROCESS
Coal of about 3.8 cm (IV) top size is chemically
comminuted by exposure to moist ammonia vapor at intermediate
pressure. After removing the ammonia, conventional physical
coal cleaning then effects a separation of coal from pyrite
and ash. Generally, 50-70% of pyritic sulfur can be removed
from Appalachian and Eastern Interior coals, producing coals
which meet State regulation for sulfur dioxide emission.
Construction of a 36 metric ton (40 tons per day) pilot plant
is contemplated. No major technical problems are foreseen
for this process other than potential problems involving
scale-up to pilot plant size.
MEYERS PROCESS
The Meyers' Process, developed at TRW, is a chemical
leaching process using ferric sulfate and sulfuric acid solution
to remove pyritic sulfur from crushed coal. The leaching takes
place at temperatures ranging from 50° to 130°C (120°-270°F);
pressures from 1 to 10 atmospheres (15-150 psia) with a
residence time of 1 to 16 hours. The final separation stages
use an organic solvent for removal of elemental sulfur from
the filtered clean coal.
941
-------
The TRW Process is the only chemical coal cleaning
process developed to the eight ton per day pilot scale level.
The current mode of operation is a pilot scale Reactor Test
Unit (RTU). Only one part of the overall system, namely the
leaching-regeneration operation, has received intensive
laboratory study and this is also the only process component
incorporated in the RTU. The RTU came onstream in late 1977
after encountering and solving many mechanical shakedown
problems. Chemical reaction data for a few 24 hour runs using
minus 14 mesh coal indicate faster pyrite removal than with
the bench scale reactors. Thirty-two different coals have
been tested on a bench scale: twenty-three from the Appalachian
Basin; six from the Interior Basin; one from Western Interior
Basin and two western coals. The Meyers' Process is more
applicable to coals rich in pyritic sulfur, thus it is
estimated about one-third of Appalachian coal could be treated
to sulfur contents of 0.6 to 0.9 percent to meet the sulfur
dioxide emission requirements of current EPA NSPS. Process
by-products are elemental sulfur, gypsum from waste water
treatment, and a mixture of ferric and ferrous sulfate, with
the latter presenting a disposal problem.
LEDGEMONT PROCESS
The Ledgemont oxygen leaching process is based on the
aqueous oxidation of pyritic sulfur in coal at moderately high
temperatures and pressures. The process has been shown to
942
-------
remove more than 90% of the pyritic sulfur in coals of widely
differing ranks, including lignite, bituminous coals, and
anthracite, in bench-scale tests. However, little, if any,
organic sulfur is removed by the process. The process became
inactive in 1975 during divestiture of Peabody Coal Company
by Kennecott Copper Co. Although not as well developed as the
Meyers' Process, the Ledgemont Process is judged to be competi-
tive in cost and sulfur removal effectiveness. The principal
engineering problem in this process is the presence of corrosive
dilute sulfuric acid, which may pose difficulties in construction
material selection and in choosing means for pressure letdown.
The process also has a potential environmental problem associated
with the disposal of lime-gypsum-ferric hydroxide sludge which
may contain leachable heavy metals.
ERDA (PERC) PROCESS
The ERDA air and steam leaching process is similar to the
Ledgemont oxygen/water process except that the process employs
higher temperature and pressure to effect the removal of organic
sulfur and uses air instead of oxygen. This process can remove
more than 90% of the pyritic sulfur and up to 40% of the organic
sulfur. The process uses minus 200 mesh coal. Coals tested
on a laboratory scale include Appalachian, Eastern Interior and
Western. The developer's claim is that using this process,
an estimated 45 percent of the mines in the Eastern United States
could produce environmentally acceptable boiler fuel in accord-
ance with current EPA new source standards. Effort to date
943
-------
is on a bench scale, but a mini-pilot plant is expected to
start up soon. The problems associated with this process are
engineering in nature. The major one is associated with the
selection of materials for the unit construction. Severe
corrosion problems can be expected in this process as the
process generates dilute sulfuric acid which is highly corrosive
at the operating temperatures and pressures.
G.E. PROCESS
Ground coal (40 to 100 mesh) is wetted with sodium hydroxide
solution and subjected to brief (^30 sec.) irradiation with
microwave energy in an inert atmosphere. After two such treat-
ments, as much as 75-90% of the total sulfur is converted to
sodium sulfide or polysulfide, which can be removed by washing.
No significant coal degradation occurs. That portion of the
process which recovers the sulfur values and regenerates the
NaOH is conceptual. Work to date is in 100 gram quantities,
but scale-up to 1 kg quantities is presently in progress. The
process attacks both pyritic and organic sulfur, possibly at
about the same rate. Appalachian and Eastern Interior coals
having wide ranges of organic and pyritic sulfur contents have
been tested with about equivalent success.
BATTELLE PROCESS
In this process, 70 percent minus 200 mesh coal is treated
with aqueous sodium and calcium hydroxides at elevated tempera-
tures and pressures, which removes nearly all pyritic sulfur
944
-------
and 25-50% of the organic sulfur. Test work on a bench and
pre-pilot scale on Appalachian and Eastern Interior coals has
resulted in products which meet current EPA NSPS for sulfur
dioxide emissions. The conceptualized process, using lime-
carbon dioxide regeneration of the spent leachant, removes
sulfur as hydrogen sulfides which is converted to elemental
sulfur using a Stretford process. In addition to being a
costly process, there are two major technical problems:
• The feasibility of the closed-loop caustic regeneration
feature in a continuous process is as yet undemonstrated;
and
• The products may contain excessive sodium residues,
causing low melting slags and making the coal unusable
in conventional dry-bottom furnaces.
JPL PROCESS
This process uses chlorine gas as an oxidizing agent in a
solution containing trichlorethane to convert both pyritic and
organic forms of sulfur in coal to sulfuric acid. Since removal
of sulfur can approach the 75% level, without significant loss
of coal or energy content, products should generally meet
current EPA NSPS for sulfur dioxide emissions. To date the
process has been tested on a laboratory scale only, on several
Eastern Interior coals. However, the effort will progress to
bench-scale and pre-pilot plant scale in the near future. The
project is currently supported by the Bureau of Mines. There are
some potential environmental problems with the process. The
945
-------
trichloroethane solvent is listed by EPA as a priority pollutant
in terms of environmental effects. A major cost factor is in
the need to recycle by-product hydrochloric acid for conversion
to chlorine. At a chlorine consumption rate of 250 kg per
metric ton of coal, the incorporation of a Kel-Chlor or
similar unit in the JPL system will add approximately $10/metric
ton of coal.
IGT PROCESS
This process uses atmospheric pressure and high temperatures
to accomplish desulfurization of coal. These high temperatures
[about 400°C (750°F) for pretreatment and 815°C (1,500°F)
for hydrodesulfurization] cause considerable coal loss due to
oxidation, hydrocarbon volatilization and coal gasification,
with subsequent loss of heating value. Experimental results
have indicated an average energy recovery potential of 60%
for this process. The treated product is essentially a carbon
char with 80-90% of the total sulfur removed. Most of the
experimental work to date has been accomplished with four
selected bituminous coals with a size of plus 40 mesh. Present
effort is on a bench-scale level. The net energy recovery
potential of the system and the change in the coal matrix
by the process have been identified as possible severe problems
for the IGT Process. The process must be developed to a
stage where the process off-gas can be satisfactorily utilized
for its energy and hydrogen content. If this cannot be
946
-------
technically and economically accomplished, the process will
prove to be inefficient and too costly for commercialization.
KVB PROCESS
This process is based upon selective oxidation of the
sulfur constituents of the coal. Dry coarsely ground coal
(plus 20 mesh) is heated in the presence of nitrogen oxide
gases for the removal of a portion of the coal sulfur as
gaseous sulfur dioxide. The remaining reacted, non-gaseous
sulfur compounds in coal are removed by water or caustic washing.
The process has progressed through laboratory scale, but is
currently inactive due to lack of support. Laboratory experi-
ments with five different bituminous coals indicate that the
process has desulfurization potential of up to 63 percent of
sulfur with basic dry oxidation and water washing treatment
and up to 89 percent with dry oxidation followed by caustic
and water washing. The washing steps also reduce the ash
content of the coal.
In cases where dry oxidation alone could remove sufficient
sulfur to meet the sulfur dioxide emission standards, this
technology may provide a very simple and inexpensive system.
Potential problem areas for this system are:
• oxygen concentration requirements in the treat gas
exceed the explosion limits for coal dust, and thus
the operation of this process may be hazardous.
947
-------
• Nitrogen uptake by the coal structure will increase
NO emission from combustion of the clean coal product.
J^
ARCO PROCESS
Little information is available on this process. It is
presently in the pre-pilot plant stage of development and is
alleged to remove both pyritic and organic sulfur. The process
was wholly funded internally until recently, when EPRI financed
a study on six coals in which there was a wide distribution of
pyrite particle size. Energy yield for the process is alleged
to be 90-95%, and ash content can be reduced by as much as 50%.
3.0 PROCESS PERFORMANCE COMPARISONS OF SULFUR REMOVAL, HEATING
VALUE RECOVERY AND COST
A comparison of process performance and costs can best be
accomplished by looking at each process on a common coal feed
basis. This basis allows the comparison of the following
parameters process by process:
• Weight yield of clean coal product based upon a feed
coal rate (moisture free basis) of 7,110 metric tons
(7,840 tons) per day [7,200 metric tons (8,000 tons)
per day of 2 percent moisture coal];
• Weight percent sulfur in the clean coal product based
upon the sulfur removal efficiency of the process;
• Heating value yield of the process based upon a feed
948
-------
coal value of 6,800 kg cal/kg (12,300 BTU/lb); and
• Costs -
total capital costs for the process
total annual processing costs,
annual costs per metric ton of clean coal, including
coal costs and excluding coal costs, and
annual costs per heating value unit, including
coal costs and excluding coal costs.
This comparison data is shown in Tables 2 and 3, arranged
according to categories of processes.
The common coal feed selected is a bituminous coal from
the Pittsburgh seam, which cannot readily be cleaned by
conventional physical washing techniques to meet the current
new source performance standards for sulfur dioxide emission. .
However, this coal does have an organic sulfur content low
enough (0.7 weight percent) so that complete removal of pyritic
sulfur would result in a product which will meet current NSPS
for sulfur dioxide emission.
The percent removal of pyritic and organic sulfur assigned
to each process is based on data supplied by individual develop-
ers. The tables indicate a range of S02 emission levels for
the clean coal products of 1.5 to 3.8 kg/106 kg cal (0.8 to
2.1 lb/106 BTU). The calculated sulfur levels for processes
which remove both types of sulfur are lower than the 2.2 kg/106
949
-------
TABLE 2. Performance and Cost Comparison for Major Chemical
Coal Cleaning Processes Which Remove Pyritic Sulfur Only.
Net coal yield, tons/day*
Vfeight % sulfur in the product
Heating value, (BTU/lb)
(Ib SO2/*M BTU)
Percent net BTU yield
Costs
Capital ($M1)
Annual processing ($i"M)
$/annual ton. of clean
coal, excluding coal cost
$/annual ton of clean
coal, including coal cost
§/*W BTU , excluding
coal cost
$/MM BTU ,Aincluding
coal cost
Feed*
7,840
1.93
12,300
3.1
—
—
—
—
—
—
—
TOT
7,056
0.83
12,835
1.3
94
109
37.2
15.6
43.4
0.61
1.69
IOL
7,056
0.83
12,835
1.3
94
114.0
45.3
19.1
46.9
0.74
1.82
Magnex
6,225
0.97
12,400
1.6
80
37.8
19.2
9.2
40.7
0.37
1.64
Syracuse plus
physical
cleaning
6,225
1.50
14,600
2.1
95
49.0
12.2
5.8
37.0
0.20
1.27
VO
Ln
O
|A11 values reported are on a moisture free basis.
The coal selected is a Pittsburgh seam coal from Pennsylvania which contains 1.22 weight percent pyritic,
* ""1 that this o«l has a heatd^ val«
Assumes coal feed @ $25/ton.
"""1C
«
-------
Table 3. Performance and Cost Comparison for Major Chemical
Coal Cleaning Processes Which Remove Pyritic and
Organic Sulfur.
Net coal yield, tons/day*
Weight % sulfur in the product
Heating value, BTO/lb
Ib SQi/VM. BTU
Percent net BTU yield
Costs
Capital ($Mfl
Annual processing ($M4)
$/annual ton of clean
coal, excluding coal cost
$/annual ton of clean coal,
including coal coet^
$/HM BTU, excluding
coal cost
$/tei BTU, including
coal costA
Feedt
7,840
1.93
12,300
3.1
—
—
—
__
—
—
EREft
7,056
0.65
12,835
0.9
94
166.8
56.6
23.8
51.6
0.92
2.00
GE
7,526
0.50
12,300
0.8
96
102.0
39.8
15.7
41.8
0.64
1.69
Battelle
7,448
0.65
11,350
1.2
88
168.6
74.2
29.6
55.9
1.30
2.45
JPL
7,135
0.6
12,300
1.0
91
103.2
44.4
18.5
46.0
0.75
1.86
IGT
4,704
0.55
11,685
0.9
57
134.6
38.3
24.2
65.8
1.03
2.81
KVB
6,690
0.61
13,120
0.9
91
65.9
41.0
18.2
47.5
0.69
1.81
AFCO
7,056
0.69
12,400
1.1
91
—
58.7
25
—
—
vo
Ul.
All values reported are on a moisture free basis.
The coal selected is a Pittsburgh seam coal from Pennsylvania which contains 1.22 weight percent pyritic,
0.01 percent sulfate and 0.70 percent organic sulfur. It is assured that this coal has a heating value
of 6,800 kgcal/kg (12,300 BTU/lb).
Assures coal feed § $25/ton.
-------
kg cal (1.2 lb/106 BTU) current NSPS for sulfur dioxide emission,
Of the four processes which remove pyritic sulfur only, two
(TRW and Ledgemont) will produce slightly higher sulfur levels
than that required to meet the current NSPS; however, within
the levels of accuracies involved they also might be considered
to be in compliance. The remaining two processes [Magnex^ and
Syracuse] would produce coal which would be in compliance only
with a standard of 4.3 kg/106 kg cal (2.4 lb/106 BTU) for
sulfur dioxide emission.
The heating value yields estimated for these processes
are generally greater than 90 percent, with a range from a low
57 percent for the IGT Process to a high of 96 percent for the
GE Process. All heating value yields reflect both the coal
loss due to processing and the coal used to provide in-process
heating needs. However, with the exception of the IGT Process,
the actual coal loss due to processing is claimed to be small.
For most processes, the major heating value loss is due to the
use of clean coal for in-process heating.
It is believed that the high yield estimated for the GE
Process may not adequately reflect the heat requirements that
may be needed to regenerate the caustic reagent used in
the process. This process is in its early stage of development
and as such, the energy requirements for the process cannot
be properly assessed at this time. It is possible, that in
the final analysis, the heating value recovery from this
process will be more in line with other chemical coal cleaning
processes.
952
-------
COST COMPARISON
Estimates of capital and annual operating costs for each
major chemical coal cleaning process are presented in Tables
2 and 3. These estimates are based on an assumed plant through-
put capacity of 7,200 metric tons (8,000 tons) per day,
equivalent to a 750 M.W. utility boiler. The total annual
operating costs for each process, including and excluding
cost of the raw coal, have been expressed also in terms of
dollars per ton and dollars per million BTU heat content in
the coal.
The capital cost estimate prepared by each process develop-
er was used as the basis of the cost estimates in this report.
In some cases, these costs were modified to allow the evaluation
of the various processes on a comparable basis. The estimate
capital costs assume a grass roots operation including costs
for coal crushing, grinding, product compacting and feed and
product handling. The capital costs also include land acquisi-
tion and site development, off-site facilities, and engineering
and design costs. A contingency allowance of 20 percent has
been included in all estimates, with the exception of TRW's.
A lower contingency allowance (10 percent) was used for the
TRW process since it is at a more advanced stage of develop-
ment and adequate process data is available to develop the
economics of this process with a greater degree of confidence.
953
-------
Annual operating costs are based on a 24-hour workday,
90.4 percent service factor (330 days per year) basis. The
capital cost is amortized over a period of 20 years at 10
percent interest per year. Where adequate information was
available, the utilities and chemical consumptions are based
upon actual process demand. The operating labor costs reflect
wage rates for the Pittsburgh, Pennsylvania, area. The
estimates for the maintenance and supplies, general and
administrative, taxes and insurance are taken as 5, 1.5, 2
and 1 percent on total installed plant capital cost (TPC),
respectively.
CAPITAL COST COMPARISONS
In general, pyritic sulfur removal processes require the
least amount of capital investment. However, these processes
have limited sulfur removal efficiencies.
Among processes that remove both organic and pyritic
sulfur, the KVB Process appears to have the lowest capital
investment, since it is a partially dry process requiring lower
investment for the dry reaction section. The high capital
cost of the Battelle Process is due to the processing steps
associated with reagent regeneration.
The high capital cost of the ERDA Process is due to
costly equipment associated with the handling of dilute sulfuric
954
-------
acid at elevated temperatures and pressures. At the process
operating conditions the dilute acid is highly corrosive and
it poses problems in terms of selection of construction
material for equipment and devices which are exposed to the
corrosive atmosphere.
Very little is known about the ARCO Process details and
process chemistry. Therefore, a capital cost estimate was
not developed for that process.
OPERATING COST COMPARISONS
The ranges of annual operating costs, including raw coal
cost, in terms of $/ton and $/106 BTU are $37.00 to $65.00 and
$1.27 to $2.81, respectively. Pyritic sulfur removal processes
using chemical pretreatment are the least expensive of all
processes studied. Operating cost for the Magnex process
depends primarily on the cost of iron pentacarbonyl manufacturing,
In the estimate presented in Table 2, an operating cost of
$0.22/kg for the iron carbonyl manufacturing was used, as
projected by the developer. At a consumption rate of 10 kg/
metric ton of coal, each $0.20 cost increase per kilogram of
iron carbonyl manufactured would increase the annual operating
cost of this process by about 27 percent.
Between the two processes which remove pyritic sulfur by
leaching, the TRW Process appears to be slightly less costly.
In the Ledgemont Process the fixed charges associated with the
955
-------
higher capital investment have an adverse impact on the annual
operating costs. Additionally, the TRW Process has a
higher probability of technical success, since it is currently
active at a PDU stage. The Ledgemont Process, tested only
at a mini-pilot plant level, is currently inactive.
The most expensive processes, in terms of energy output,
are the IGT process followed closely by the Battelle Process.
Laboratory data available at this time, indicate a very low
BTU recovery for the IGT Process. The Battelle Process is
adversely impacted by the fixed charges associated with the
high capital investment and by the costs associated with
chemicals consumption and reagent regeneration operations.
The least expensive process capable of removing pyritic
and organic sulfur is the GE Process followed closely by the
JPL and KVB Processes. The GE estimate is based, however, on
early laboratory data and it is quite possible that the project-
ed costs will prove somewhat inaccurate in the long run. The
basic process utilizes a caustic reagent in coal pretreatment
and the costs associated with caustic consumption and caustic
regeneration are questionable at this time. The JPL Process
estimates are also preliminary since investigations on this
process are at an early stage. The annual costs reported for
the KVB Process are also preliminary since the process is at
its early stages of development and accurate conceptualization
956
-------
of the process for purposes of economic evaluation is difficult.
The main advantage of the KVB Process is the simplicity of
the first stage dry oxidation process. If the dry oxidation
process can be successfully demonstrated using coarse coals,
this process would be an inexpensive technology for beneficiation
of coals where partial removal of sulfur would substantially
upgrade the coal.
Among the processes capable of removing pyritic and organic
sulfur the ERDA Process has one of the highest probabilities
of technical success. The process is currently active and
most technologies employed in this system have been already
tested in other systems such as Ledgemont and TRW. The process
is attractive because it is claimed to remove both types of
sulfur and uses air as a major reagent. Furthermore, the
sulfur by-product from this process is a dilute sulfuric acid,
rather than iron sulfate, which greatly simplifies the coal
washing operations. The process is somewhat expensive due
to high operating temperature and pressure requirements and
the corrosive nature of dilute acid present in this system.
The dilute sulfuric acid at the operating conditions of the
ERDA Process will require the use of expensive construction
material and consequently a higher capital investment cost.
Table 4 presents a cost effectiveness summary derived from
information presented in Tables 2 and 3. Costs are presented
in terms of dollars per percent of sulfur removed from coal
957
-------
3AOE 4. COST H-VHUTIVENESS COMPARISON OF CHEMICAL COM. CLEANING PROCESSES*
Process
fife
Magnex ^?
Syracuse S
Kiysical
flmnina
TRW
LCL
HOA
GB
Battelle
JPL
XGT
KVB
AHOD
Type of
Sulfur
Removed
P*
P
P
P
(PSD)*
(P»)
(PCO)
(PSO)
(PSO)
(PSD)
(PSO)
Sulfur
Raooved
(Wt.%)*
0.96
0.43 P
1.10
1.10
1.28
1.43
1.28
1.33
1.38
1.25
1.24
Process
COSt <$/
metric ten
incl. cost
of coal)
44.8
40.8
47.9
51.6
56.9
46.0
61.6
50.7
72.6
52.4
Jl
Cost Effect-
iveness of
5 removal,
$/% S removed
46.6
94.9
43.5
46.9
44.5
32.2
48.1
38.1
52.6
41.9
_A
Cost
Effect-
iveness
Rarfe-
ing
2
4
1
3
4
1
5
2
6
3
-
Meets
EPA
NSPS*
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Probability
of Success
(based on
available
info.)
85%
70%
90%
50%3
70%
60%
35%
55%
20%3
20%'
_A
Time Frame
for OonrotfrcJL'"
al Avail-
ability
(Years) «
2-3
2-3
<3
4-5
5
5
4-5
5
5
5
_A
in
00
MOOES: * Based on Pittsburgh seam coal from Pennsylvania ^hich contains 1.22 weicfrit percent pyritic,
. 0.01 percent sulfate and 0.70 percent organic sulfur.
. P = pyritic sulfur.
^ (PSO) = pyritic and organic sulfur.
. Tine frame assunes continuing effort or renewed effort starting immediately.
" Infoniaticn available is insufficient to mate educated guesses.
Process not currently active, partially accounting for low probability of success.
£80 percent, yield of product assumed in cleaning plant.
-------
regardless of the quality of the treated product. The processes
are then rated based upon the cost effectiveness of sulfur
removal. The subjective probability of success assigned to
each process is based on integration of several factors such
as:
• available experimental data;
• our understanding of the status of the process;
• known product quality deficiencies;
• known process problems; and
• the degree and quality of effort assigned to the
individual program.
In conclusion, all chemical coal cleaning processes
discussed in this section offer a possibility of converting
coal into clean fuel. Each process has an area of application.
However, processes that remove both pyritic and organic
sulfur are judged to have a greater impact in future coal
utilization.
959
-------
STATUS OF THE REACTOR TEST PROJECT FOR CHEMICAL
REMOVAL OF PYRITIC SULFUR FROM COAL
M. J. Santy and L. J. Van Nice
TRW, Inc.
Redondo Beach, California
ABSTRACT
Plant checkout and shakedown was completed at the end of September and
initial plant process performance was evaluated on an Appalachian coal.
Operation of the plant through January of 1978 demonstrated that the Reactor
Test Unit (RTU) could be run continuously in three-shift operation to reduce
the coal from 2.4 Ibs S02/106 Btu to a level of 1.0 to 1.2 Ibs S02/106 Btu,
after rinsing and extraction of generated elemental sulfur. There was no
measurable coal oxidation during processing and leach rates in the plant were
greatly improved over bench-scale values. The leach solution/coal/oxygen
environment was found to be corrosive to the installed stainless steel
reactor, necessitating future upgrading to support additional cesting. Bench-
scale experimentation showed that the leach solution can be used as a homo-
geneous dense-media tp efficiently gravity-separate coal prior to processing.
Beneficial engineering cost improvements are obtained based on using this
approach, resulting in capital cost estimates of $68-$69/KW and with $0.44-
$0.50/106 Btu processing costs, including amortization of capital, for input
coal costing $0.78-$0.81/106 Btu. Overall energy efficiency was 93 to 96
percent.
960
-------
INTRODUCTION
The Meyers Process 1s a technology for chemically removing essentially
all of the pyrltlc sulfur from coal through a mild oxldatlve treatment.
Important pollutant trace elements, lead, cadmium and arsenic, are removed
at the same time. It can be used to provide compliance coal for Industrial
boilers and smaller electric utilities, and for recovery and desulfurlzlng
waste fine coal rejected from mining and washing operations. The develop-
ment of the process 1s sponsored by the U.S. Government's Environmental
Control Technology Program administered by the Environmental Protection
Agency.
A process schematic 1s shown 1n Figure 1. Coal 1s mixed with an aqueous
solution of ferric sulfate (Step 1), previously derived from the coal, to
form a slurry. The slurry 1s raised 1n temperature to 100-130eC (Step 2)
where the ferric sulfate oxidizes the pyrltlc sulfur content of the coal to
form elemental sulfur and additional Iron sulfate. At the same time oxygen
or air Is Introduced to the wet slurry mix to regenerate the reacted ferric
961
-------
H2S04
NO
Ov
10
vJQAL
(F. S2 + F*2 (S04)
H*°4+°2lS
F. S0
GnO-
FILTER
1
NEUTRAlH
IZATION
COAL
Figure 1. Meyers Process
-------
sulfate. Iron sulfate dissolves into the leach solution while the elemental
sulfur is solvent-removed in a second extraction (Step 3). The coal is
dried and solvent recovered (Step 4). The products of the process are iron
sulfate, which may be limed to give a dry gypsum and iron oxide material,
and elemental sulfur. Trace elements from the coal are bound in with the
stabilized gypsum/iron oxide solid.
Elemental sulfur is the most desirable product which car, be obtained
in the process of controlling sulfur oxide pollution, and be easily stored
without secondary pollution or may be marketed. The gypsum/iron oxide is
a safe and storable solid.
Very recent operating experience has demonstrated that the iron sulfate/
sulfuric acid leach solution can be used as a homogeneous dense media to
efficiently gravity-separate fine coal at specific gravities of 1.2-1.35.
Beneficial engineering cost improvements are obtained using this gravity-
separation technology. A significant portion of the input coal, which char-
acteristically floats in the leach solution and is almost pyrite free, may
bypass the reactor, elemental sulfur extraction and dryer portions of the
Meyers Process (Figure 2). This revised technology is termed the Gravichem
Process. For example, when applied at bench-scale to a Tennessee Valley
Authority (Interior Basin) coal containing 12% ash and 7 Ib SOj/lO6 Btu,
two products are obtained in roughly equal amounts, a 4% ash float coal
containing 3 Ib S02/106 Btu, and an 11-12% ash sink coal containing 4 Ib
S02/10 Btu after treatment by the Meyers Process. Both of these products
meet state SOX emission standards for utility systems using this coal.
Because of these promising results, TVA has shipped 300 tons of coal to TRW
963
-------
F.2(S04)3
GRAVITY
SEPARATOR
(FeS2)
FILTER
WASH
FILTER
G
REACTOR
I MEYERS PROCESS
L.
SULFUR
J
Figure 2. Gravichem Process
-------
for future processing and evaluation. A description of the test plant,
operational results and process sulfur emissions reduction potential is
presented in the sections to follow.
THE TEST PLANT
After testing the process at bench-scale on some 40 U.S. coals (Meyers,
1977; Hamersma and Kraft, 1975; Hamersma, et al., 1973) and performing 200
fully material-balanced bench-scale extractions (Hamersma, et al., 1973;
Koutsoukos et al., 1976), the value of the process for controlling the
sulfur content of coal was firmly established. Additionally, the data
necessary for the design of a test plant was then available. Engineering
design criteria obtained through extensive studies at TRW (Hamersma et al.,
1973; Koutsoukos et al., 1976; Van Nice and Santy, 1977) and various other
engineering organizations (Nekervis and Hensley, 1975; McGee, 1975) provided
confidence that the process was economically attractive and identified
important engineering data which could only be obtained by operation of a
pilot-plant test facility.
It was determined that the initial test facility process evaluation
should concentrate on the key process steps of coal/Ieach solution slurry
formation, leaching, regeneration and filtration. A test plant, termed the
Reactor Test Unit (RTU), was constructed at TRW's San Juan Capistrano site
for the purpose of testing these portions of the process (Figure 3). The
plant, sized to process from 1/8 to 1/3 ton/hour of coal, was dedicated in
April 1977.
965
-------
Figure 3. Reactor Test Unit
-------
The facility was designed to demonstrate those unit operations com-
prising the front end of the Meyers Process, namely, coal/reagent mixing,
primary pyrite reaction and reagent regeneration, secondary (finishing)
pyrite reaction and slurry filtration. Designed for high flexibility, the
RTU has the capability of processing a range of suspendable coals up to
approximately 8 mesh top-size and coarse coals up to approximately 3/8-inch
top-size. Spent reagent may be regenerated either exclusive of, or simul-
taneously with, coal leaching. The primary reactor may be used as either
a five-stage or a three-stage reaction unit to increase the available range
of coal processing times.
A process flow diagram of the RTU is shown schematically in Figure 4.
Fine coal ground to the desired size is loaded in feed tank T-l. Dry coal
is fed continuously by live bottom feeder A-2 to weigh belt A-3 which
discharges through rotary valve A-4 to three-stage mixer T-2 (stream 1).
Aqueous Iron sulfate leach solution (stream 2) enters T-2 after preheating
1n heat exchanger E-2 and passing through foam scrubber T-3. Steam is
added (stream 3) to raise the slurry to Its boiling point. Foaming, which
may occur during the early stages of mixing, ceases when coal particle
wetting 1s complete. The heated slurry (stream 4) is then pumped to five-
stage pressure vessel R-l 1n which most of the pyrite is removed. R-l
slurry heating is achieved by direct Injection of steam into any or all
reaction stages. Reagent regeneration may be carried out simultaneously
with pyrite leaching by means of oxygen Injection into any or all reaction
stages (stream 5). Unused oxygen saturated with steam (stream 6) 1s con-
tacted 1n foam knockout drum V-l with the feed reagent (stream 7) to pre-
heat the reagent and cool vent gases. Slurry 1n any stage of R-l may be
967
-------
11 COAL
W MECHANICAL
ATMOC.
WATtt
TO TIUCK FO« mSPOSAL
p-n
P-12
P-U
Figure 4. RTU schematic
968
-------
cooled by means of cooling water heat exchanger E-l which may be applied
to slurry recirculation loops for removal of excess heat of reaction. Vent
gas from both T-3 and V-l are water scrubbed in T-4 to remove any traces
of acid mist.
Reacted coal slurry (stream 8), at elevated temperature and pressure,
is flashed into flash drum T-5 for gas/liquid separation. Generated steam
(stream 9) is condensed in T-4, and the condensate plus any entrained acid
mist is removed with scrubber water. Reacted slurry (stream 10) is fed to
belt filter S-l. The filtrate, which is regenerated leach solution, is
removed from the coal slurry through evacuated filtrate receiver V-2 and
pumped (stream 12) to leach solution storage tank T-7. Coal on the filter
belt (Figure 5) is washed with water (stream 11) and discharged to coal
storage. Wash water 1s removed through evacuated wash water receiver V-3
and pumped (stream 13) to liquid waste holding tank T-9 for subsequent
disposal.
As a processing alternate, partially processed slurry from T-5 may be
loaded into secondary reactor R-2 for final depyritlzation 1n a batch mode.
Slurry may be retained, heated and agitated for extended periods of time
1n R-2 prior to being pumped to S-l.
Coarse coal contacting vessel T-6 1s a steam heated Insulated tank in
which hot reagent may flow through a bed of retained coarse coal. This
unit 1s used principally to convert regenerated leach solution 1n storage
tank T-7 or T-8 to a more depleted solution simulating recycle reagent after
secondary reaction. T-6 1s basically a coarse coal reactor and, 1f
969
-------
appropriate sampling ports and possibly some flow distribution internals
were added, could be used to obtain design data for coarse coal processing.
PLANT OPERATION AND PROJECT RESULTS
Plant checkout and shakedown was completed at the end of September
1977 and initial plant process performance was evaluated on coal donated
by the American Electric Power Service Corporation (AEP) from its Martinka
mine in West Virginia (Hart et a!., 1978). Operation of the plant, through
January of 1978, demonstrated that the RTU could be run continuously in
three-shift operation to reduce the AEP coal from 2.8 Ib S02/10 Btu to a
level of 1.0-1.2 Ib S02/10 Btu, following rinsing and extraction of
generated elemental sulfur (Table 1). Thus, the process coal meets New
Source Performance Standards of 1.2 Ib S02/10 Btu. The coal product is
shown as a cake on the plant filter belt in Figure 5. There was no measur-
able coal oxidation; in fact, heat content increases averaged 350 Btu/lb
due to pyrite and ash removal. Leach rates in the RTU were greatly improved
over bench-scale values, thus enabling bypass of the secondary reactor.
To fully appreciate the apparent leach reaction rate increase, data
obtained from the RTU acidified Iron reagent operations is correlated with
the previously established (at bench-scale) pyrite leaching rate expression,
namely:
-dW.
where
r. 1s the pyrite leaching rate, expressed 1n weight of
pyrite removed per 100 weights of coal per hour (rate
of coal pyrite concentration reduction),
970
-------
Run Reactor Temp.
°F
Starting Coal
1 222
2 232
3 234
Coal
Ash
% w/w
16.11
±0.261
12.97
±0.0894
12.02
±0.636
12.51
+0.953
Analysis
Heat Content,
Btu/lb
12508
± 77
13258
± 162
13388
+ 91
13265
+ 155
Sulfur lb S02
% w/w 1Q6 Btu
1.73 2.8
±0.045
0.68 1.03
±0.044
0.78 1.17
±0.065
0.75 1.13
±0.033
Table 1. Test plant data taken over 5-day period
-------
Figure 5. Desulfurlzed coal on filter belt
W 1s the pyrite concentration in coal at time t 1n
wt. percent,
t 1s the reaction (leaching) time in hours,
KL 1s the pyrite leaching rate constant (a function of
temperature and coal particle size) expressed in
(hours)" (wt. percent pyrite in coal) ,
Y is the ferric-Iron-to-total-iron ratio in the leacher
at time t, dimension!ess, and
972
-------
with
KL = AL exp (-EL/RT) (2)
where
A, is the Arrhenlus frequency factor in the units of K^,
E, is the apparent activation energy in calories /mole,
R is the gas constant in calories/mole °K, and
T is the absolute temperature, in °K.
This rate expression was used in conjunction with a model of the
reaction system as a series of continuous-flow stirred-tank reactors.
Measured slurry temperatures and reagent Y values for each reaction stage
were input for each experimental condition and the value of K^ was deter-
mined at the various reaction temperatures tested.
Equation (2) indicates that a plot of In 1^ vs. 1/T should yield a
straight line having a slope of -EL/R and an intercept of In AL- An
Arrhenius plot of the data from several experiments is presented in Figure
6. A very good linear correlation was obtained. The apparent activation
energy and frequency factor Indicated by these data are:
EL = 26.9 x 103 calories/mole, and
AL = 9.2 x 1014 Wp1 hr"1
These values may be compared with bench-scale coal processing results
which yielded an EL (bench) of 11.1 x 103 calories/mole and AL (bench) of
2.95 x 105 W"1 hr"1. Hence, KL (RTU) was measured to be 3 to 8 times
greater than K, (bench) for 14 mesh top-size coal at temperatures between
973
-------
3.
1.0
.9
X
.0. .8
1 .7
.6
§ .5
o
.3
o
*f
270°F
250°F
230°F
2.4
2.5
1/T, -
2.6 x 10
Figure 6. Arrhenius plot of data obtained
during RTU processing
974
-------
230°F and 270°F. The deviations of AL and EL from the values obtained
during batch reactor (bench scale) operation were only partially antici-
pated. The apparent value of AL was expected to increase during stagewise
operation as the mixing in reaction stages deviated from ideal and the
average particle residence time per stage increased. Also, under non-ideal
mixing, pyrite rich particles might be expected to have longer residence
times than pyrite lean particles which have a lower density. Thus, coal
processing in a continuous flow stirred tank reactor is expected to result
in a higher apparent AL value than would identical coal processing in a
batch reactor. However, the apparent doubling of the activation energy EL
above E, (bench) was not anticipated. To effect such an increase in EL
requires that deviations from ideal mixing or segregation of pyrite rich
coal particles increase with increasing temperature. A decrease in reagent
density could increase coal segregation despite mechanical mixing and,
perhaps, selectively cause the pyrite rich coal particles to remain longer
1n each reaction stage. While density changes due to temperature alone are
small, this effect coupled with reagent dilution (due to direct steam heat-
ing in the RTU) can be significant. The combined temperature and steam
dilution effects are estimated to have resulted in mean reagent densities
of 1.15 g/cc during 230°F tests, 1.08 g/cc during 250°F tests and 1.06 g/cc
during 270°F tests. Thus, significant reagent density differences occurred
between the 230°F and 270°F experimentation which may have resulted in the
apparent increase in the pyrite leaching activation energy. Whether or not
this density difference 1s 1n Itself sufficient to cause the observed factor
of 2 Increase 1n activation energy cannot be determined from available data.
However, 1f part of the observed Increase 1s the result of a density effect
975
-------
then reagent density would become an Important reaction design parameter
for systems utilizing stirred tank reactors. Changes 1n viscosity and
slurry concentration may also be important.
As is the case with most new process pilot-plant-scale startups,
numerous equipment and materials problems were encountered during operation.
The more severe problems resulted in significant plant downtime. These
problems included: filter belt (S-l) misalignment and hangup, errors in
weigh belt (A-3) calibration,, slurry feed pump (P-l) malfunctions and
corrosion in primary reactor (R-1) and its associated pump-around loops.
All of these equipment problems were identified and solved during the
operational phase of the project. It is important to note that, in general,
none of the problem areas encountered during RTU operation were process
oriented but rather pilot-scale equipment related.
During the first 2 months of operations, RTU vacuum filter belt (S-l)
experienced numerous shear pin failures. These failures usually occurred
several hours into experimental runs and resulted in premature run termina-
tion. The problem was originally believed to be one of improper belt
alignment resulting in excessive power train exertion. However„ following
several belt alignments and power train adjustments„ which did not solve
the shear pin failure problem, it was further determined that excessive
frictional forces were being experienced at the rubber-drive-belt/vacuum-
pan interface. These forces were sufficiently strong to result in one
instance of drive belt separation (Figure 7). The problem was resolved by
attaching Teflon skids to the vacuum pans at the rybber belt interface.
976
-------
\o
Rubber Belt
Drive
Cloth Filter
Belt Roller
Figure 7. Ripped S-l filter belt (cloth belt removed)
-------
The belt was repaired, reassembled and placed back Into service with no
further shear pin failures or belt tears experienced.
During the Initial phases of shakedown operations, RTU weigh belt
coal feeder (A-3) was found to be overly temperature sensitive and unable
to operate to the specified calibration limits. Most of the belt internals,
including mechanical and electric components, were modified and/or replaced
by the manufacturer during several cycles of rework at both the Capistrano
Test Site and the manufacturer's facility. The modified unit which is
currently installed in the RTU has repeatedly demonstrated its ability to
achieve the desired accuracy range of ±1 percent over the approximate 100
to .1000 pound per hour delivery range.
Another recurring problem experienced during RTU operations was that
of slurry feed pump (P-l) failure. Feed pump (P-l) and its replacement
spare are six-stage progressive cavity type pumps. The pump failures were
manifested as gradual losses of pumping capability at constant head pressures,
It was determined upon inspection of pump internals that the chrome plated
316 stainless steel rotors were experiencing rapid corrosion and/or erosion
(Figure 8). Subsequent material evaluations and discussions with the pump
supplier Indicated that the pumps were Inadvertently Incorrectly specified
and that the units should have been supplied with Hastelloy-C rotors. Due
to the relatively long delivery time (several months) for obtaining re-
placement Hastelloy-C rotors, efforts were made to resurface and rechrome
the existing rotors and to operate the RTU while awaiting delivery of the
•
replacement rotors. The reworked 316 stainless steel rotors were found to
operate successfully for times ranging from 1/2 hour to 100 hours depending
978
-------
Figure 8. Corroded/eroded P-l rotor
-------
on the run conditions and the degree of previous chrome plating required on
the specific rotor. Recently, the new Hastelloy-C rotor for P-l was received
and installed.
The last of the major problems encountered during RTU operation was
that of reactor section corrosion. The 316L stainless steel primary reactor
(R-l) and its attendant slurry circulating loops experienced pitting type
corrosion. The severity of the pitting corrosion was found to be directly
related to the affected area operating temperature. It is important to note
that while the reactor section, which operated between 230°F and 270°F did
corrode significantly, there was virtually no sign of pitting corrosion
elsewhere in the RTU where slurry temperatures were generally maintained
below 215°F.
The observed reactor section corrosion resulted in several instances
of leach solution seepage from circulating loop piping during operation at
temperature and pressure and resulted in unscheduled unit shutdown. A
photograph of a typical seepage point is presented as Figure 9. Both an
external view and a sectioned internal view of the seepage point are shown.
As a result of the observed corrosion, all reactor associated piping was
replaced with new 316L materials midway through the operational phase of
the project and 1s currently scheduled for replacement with titanium
materials prior to unit reactivation. Titanium 1s being utilized at RTU
scale since pipe diameter dictates piping materials of solid metallic
construction. It has been determined, however, that at larger scales of
operation plastic lined carbon steel pipe would be most applicable.
980
-------
Figure 9. Flush port fitting
-------
Primary reactor (R-l) was thoroughly Inspected midway through and at
the conclusion of the operational phase of the project. The Internals of
the unit were found to have experienced significant pitting corrosion. A
photograph of the Internals of the third stage of R-l, taken during the
final Inspection, 1s presented as Figure 10. Due to the extent of the
observed corrosion, 1t 1s currently planned to Install a replacement reactor
of titanium construction prior to reinitiation of RTU operations. It is
important to note that the choice of titanium is based on the relatively
small size of the RTU reactor. A larger scale unit would no doubt be
constructed of acid resistant rubber-lined brick over a carbon steel shell.
Overall RTU project conclusions are summarized below.
Operation Results
1. The Reactor Test Unit can be operated continuously for testing of the
Meyers Process units for coal/leach solution mixing, simultaneous coal
leaching and leach solution regeneration, filtration of leach solution from
treated coal and water washing of coal on the filter.
2. The Input coal from American Electric Power Service Corporation's
Martlnka mine 1n Fairmont, West Virginia, containing 1* Inorganic sulfur
can be reliably and continuously reduced, 1n the RTU, to a pyritic sulfur
level of 0.16% without any measurable coal loss and with coal heat content
Increases averaging 350 Btu/lb.
3. RTU coal product, after bench-scale extraction of residual sulfate and
elemental sulfur, was continuously and reliably reduced to a total sulfur
-------
1C
DC
ill
R-l Cel
Surface
Pitting
(reworked area)
R-l Cel
Weir
Corrosion
Figure 10. Primary reactor internal corrosion
-------
content of 0.68-0.75* w/w and projected SOX emissions levels of 1.0-1.2
Ib S02/106 Btu.
4. Leach rates 1n the RTU were Improved over bench-scale values by an
average factor of 5, due mainly to favorable coal segregation 1n the
primary reactor.
5. Plant Teacher/regenerator operation at temperatures ranging 230° to
270°F (110° to 132°C), pressures of 30-80 pslg and residence times of 5-8
hours was successfully demonstrated.
6. The use of a single reactor/regenerator was found to be sufficient to
meet design basis pyrlte removal and provide regenerated leach solution for
the Martlnka coal tested. It 1s not known whether the use of a secondary
reactor to complete the reaction of pyrlte with leach solution will be
needed for processing of coals with higher pyrltlc sulfur content.
7. The leach solution/coal/oxygen environment caused corrosion 1n the
primary reactor/regenerator system Indicating that upgrading of the 316L
material of construction Is needed to support further testing.
8. The following materials were found to be suitable for leach solution/
coal service at temperatures up to 90°C: fiber reinforced plastics,
elastomers and 316L stainless steel. The following materials were deter-
mined to be suitable for service at reactor/regenerator temperatures up to
130°C: titanium, Hastalloy, and rubber-lined brick over mild steel
984
-------
9. No significant corrosion was observed in the leach solution/coal mix
tank, flash-down tank, or storage tanks. Mild corrosion was observed in
the reactor/regenerator pumps.
Supporting Experimentation Results
1. The iron sulfate/sulfuric acid leach solution can be used as a homo-
genous liquid to efficiently gravity-separate fine coal at specific
gravities of 1.2 to 1.35.
2. Beneficial engineering cost improvements are obtained by using this
gravity-separation technology to bypass a significant portion of the input
coal around the reactor, elemental sulfur extraction and dryer units of
the Meyers Process. This revised process is termed the Gravichem Process.
3. The Gravichem Process provides two products with no coal reject, a
float coal containing 2-4% ash with almost no pyritic sulfur and a sink
coal generally lower 1n ash than the input coal and also nearly pyrite-
free. The two products can be used separately or combined.
4. Bench-scale testing of the Gravichem Process on the American Electric
Power Service Corporation (Appalachian) coal gave two products: a float
coal containing 1.0 Ib S02/106 Btu and a sink coal containing 1.1 Ib S02/
106 Btu after treatment by the Meyers Process. Both products met present
New Source Performance Standards.
5. Bench-scale testing of the Gravichem Process on a Tennessee Valley
Authority (Eastern Interior Basin) coal containing 12% ash and 7 Ib
985
-------
S02/10 Btu gave two products: a 4% ash float coal containing 3 lb SO /106
Btu and a sink coal containing 4 Ib S02/106 Btu and 11-12% ash after treat-
ment by the Meyers Process.
6. The solvent system, acetone and water, is the most economically
attractive method thus far investigated for removal of generated elemental
sulfur from treated coal. This solvent also dissolves and removes residual
Iron sulfate.
Engineering Design Results
1. Process cost forecasts for the Gravichem Process are $68-69/KW capital
cost with $0.44-0.50/1O6 Btu processing costs (including utility financed
capital amortization for input coal costing $0.78-0.81/106 Btu).
2. Coal energy efficiency is 94-97% for the Gravichem Process including
coal used for process heating.
3. Overall energy efficiency including both coal use and electric energy
for plant operation is 93-96%.
PROJECT STATUS
In early 1978, the RTU coal desulfurization unit was secured for an
extended shutdown period at the direction of the EPA. The extent of the
shutdown period 1s currently unknown. Other aspects of the coal desulfuri-
zation project at TRW are continuing, however. Currently, work 1s focused
on the further development of the Gravichem Process. The current efforts
Involve the accomplishment of additional bench-scale experimentation full
986
-------
scale process engineering analyses, user specific applications studies, RTU
equipment redesign and specification, RTU tail-end unit design, and RTU
equipment preservation and maintenance.
In anticipation of restart of the RTU at a future date, the unit is
being preserved and maintained in a standby condition to prevent corrosion
and to limit system deterioration. The plant has been cleaned of residual
leach solution and coal by flushing with water. Where appropriate, preser-
vatives were added to protect against corrosion. All electrical equipment
was shutoff and tagged; Instrumentation was sealed and dessleant added.
Liquid and solid wastes were hauled away. A detailed plant inspection will
be performed to assess the degree of corrosion that has occurred. Preven-
tive maintenance of the RTU is being carried out on a weekly basis. Engi-
neering studies are to be performed which will, 1) establish specifications
for a new reactor vessel R-l and obtain cost estimates and time of delivery
and installation, 2) result in a preliminary conceptual design for an RTU
tail-end unit elemental sulfur extraction system, and 3) evaluate applica-
tion of the Gravichem Process, based on data obtained from bench-scale tests,
for use as a stand-alone plant or as integrated Into a physical coal clean-
Ing complex. A respecfflcation of the R-l reactor vessel will be developed
for a replacement vessel to be constructed of material which will give
long-term service. Designs for a tall-end elemental sulfur extraction
system will Include the use of acetone or methyl ethyl ketone and other
solutions for removal of elemental sulfur at the RTU scale. Based on an
early tall-end unit conceptual design effort, the RTU tall-end unit expan-
sion 1s envisioned to appear as presented In Figure 11.
987
-------
Figure 11. RTU tail-end unit expansion
988
-------
References
Hamersma, J.W. and M.L. Kraft (TRW Inc.), Applicability of the Meyers Process
for chemical desulfurization of coal: Survey of thirty-five coals,
EPA-650/2-74-025a, NTIS No. PB 254461 (1975).
Hamersma, J.W. et al., Chemical removal of pyritic sulfur from coal, Advances
in Chemistry, Series No. 127, American Chemical Society, Washington,
D.C. (1973).
Hamersma, J.W. et al. (TRW Inc.), Chemical desulfurization of coal: Report
of bench-scale developments, Volumes I and II, EPA-R2-73-173a and
-173b, NTIS No. PB 221405 and 406 (1973).
Hart, W.D. et al. (TRW Inc.), Reactor test project for chemical removal of
pyritic sulfur from coal, Draft Final Report, EPA Contract No. 68-02-
1880 (1978).
Koutsoukos, E.P. et al. (TRW Inc.), Meyers process development for chemical
desulfurization of coal, Volume I, EPA-600/2-76-143a, NTIS No. PB
261128 (1976).
McGee, E.M. (Exxon Research and Engineering Co.), Evaluation of pollution
control in fossil fuel conversion processes, coal treatment: Section
1, Meyers Process, EPA-650/2-74-009K, NTIS No. PB 246311 (1975).
Meyers, R.A. (TRW Inc.), Coal desulfurization, Marcel Dekker, Inc., New
York (1977) pp 59-164.
Nekervis, W.F. and E.F. Hensley (Dow Chemical Corporation), Conceptual
design of a commercial scale plant for chemical desulfurization of
coal, EPA-600/2-75-051, NTIS No. PB 238199 (1975).
Van Nice, L.J. and M.J. Santy (TRW Inc.), Pilot plant design for chemical
desulfurization of coal, EPA-600/2-77-080, NTIS No. PB 270111 (1977).
989
-------
Metric Conversion Factors
In compliance with EPA policy, metric units have been used extensively
in this paper. However, in some cases, British units have been used for
ease of comprehension. For these cases, the following conversion table is
provided:
British
1 Btu
1 Btu
1 KW
1 hp (electric)
1 psi
5/9 (°F-32)
1 inch
1 ft
1ft2
1 ft3
1 gallon
1 pound
1 ton (short)
Metric
252 calories
2.93 x 10"4 kilowatt-hours
1,000 joules/sec
746 joules/sec
o
0.07 kilograms/cm
°C
2.54 centimeters
0.3048 meter
0.0929 meters2
0.0283 meters3 or 28.3 liters
3.79 liters
0.4536 kilograms
0.9072 metric tons
990
-------
STATUS OF HYDRO-THERMAL PROCESSING FOR
CHEMICAL DESULFURIZATION OF COAL
E. P. Stambaugh, H. N. Conkle, J. F. Miller,
E. J. Mezey, and B. C. Kim
Battelle's Columbus Laboratories
Columbus, Ohio
ABSTRACT
Chemical desulfurization of coal is achieved by heating an aqueous slurry
of coal, sodium hydroxide, and calcium hydroxide in a closed vessel at elevated
temperatures and corresponding steam pressure. Later, the cleaned coal pro-
duct is separated from the spent leachant by a series of liquid/solid separ-
ations and utilized as a source of fuel. The spent leachant is regenerated
for recycle.
This paper presents the current status of this technology and the results
of a current study to improve the economic viability of hydrothermal cleaning
by reducing the costs associated with liquid/solid separation and leachant
regeneration.
991
-------
INTRODUCTION
Results from a previous study for the U.S. Environmental Protection
Agency - "Combustion of Hydrothermally Treated (HTT) Coals", Contract No.
68-02-2119 - indicated that HTT coals prepared by the Hydrothermal Coal
Process from selected coals are clean solid fuels that in many instances
can be burned with little or no sulfur emissions. Also, the HTT coals burn
as well or better than raw coal and trace metal emissions should be signifi-
cantly reduced because of the low concentrations in HTT coals.
This work is being continued under the program entitled "Process
Improvement Studies on Battelle Hydrothermal Coal Process" (EPA Contract No.
68-02-2187). Under this program, emphasis has been on development of process
improvements in the liquid/solid separation and leachant regeneration segments
of the process. In the liquid/solid separation, laboratory and miniplant
tests were performed to evaluate improvements which can be achieved by
the use of larger coal particle sizes in combination with vacuum and
centrifugal filtration and oil agglomeration. In leachant regeneration, a
number of potential methods have been screened. Primary emphasis has been
on the use of metallic compounds containing zinc and iron.
Technical progress during this contract are discussed in this
paper.
Process Description
The Battelle Hydrothermal Coal Process (BHCP) is a method for pro-
ducing environmentally acceptable solid fuels (clean coal) from high sulfur
coals.
Basically, hydrotheraal coal processing involves heating an aqueous
slurry of coal and a chemical leachant, in this case, a mixture of sodium
hydroxide and lime at moderate temperatures and corresponding steam pressures
to extract the sulfur and 'some of the ash from the coal and subsequent re-
992
-------
generation of the leachant for recycle. The process entails five major
processing steps as shown in Figure 1:
• Coal preparation
• Hydrothermal treatment (desulfurization)
• Fuel separation (separation of spent leachant from clean coal)
• Fuel drying
• Leachant regeneration.
Coal preparation entails crushing or grinding of the raw coal, as-
received from the mine or after washing.
The coal is then mixed with the leachant, or, alternatively, the
coal may be physically beneficiated to remove some of the ash and pyritic
sulfur before mixing with the aqueous leachant.
After mixing with the leachant, the coal slurry is pumped contin-
uously through the hydrothermal treatment (desulfurization) segment where it
is heated to a temperature and corresponding steam pressure necessary to
extract the sulfur.
The resulting coal-product slurry is then cooled and the cleaned
coal is separated from the spent leachant by a series of washing - filtration
operations.
Next, the desulfurized product is dried to reduce the residual
moisture to the desired level.
In the basic process, the spent leachant is regenerated for recycle
by the C02-CaO process. This entails sparging the spent leachant with
carbon dioxide to liberate the sulfur as hydrogen sulfide, which is sub-
sequently converted to elemental sulfur by the Claus or Stretford process.
The carbonated liquor is then causticized with lime and filtered to remove
the calcium carbonate which is calcined to produce lime and carbon dioxide
for recycle. The regenerated leachant is concentrated and recycled to the
process.
Process Chemistry
Sulfur Extraction
Sulfur is contained in coal in primarily two forms — inorganic
sulfur as FeS (pyrites) which is associated with the mineral matter and
993
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VO
VO
Coal-
r
Water
Steam
Co*
Preparation
— »»
Hydrotharmal
Treatmant
(OMulfurization)
i
COj
Lime
-~
Racy da
Laachant
Separation
and Washing
Solid
Spent Leachant 1
dean Coal
Sulfur
Removal
»
Laachant
Recovery
— fc-HjS
— •». CaCO3
•*• Water
Vanor
FIGURE 1. FLOW DIAGRAM OF THE BASIC HYDROTHERMAL COAL PROCESS
-------
organic sulfur which is part of the coal molecule. During treatment of the
coal by hydrothermal leaching, up to about 95 percent of the inorganic
sulfur is extracted from most coals and up to 50 percent of the organic
sulfur is extracted from some coals.
The dissolution or extraction of the inorganic sulfur from coal
using alkaline leaching may involve several chemical reactions including the
following:
(1) FeS2 + OH~ -» Fe(OH)2 + S2~2
(2) 2FeS2 + 60H~ J Fe^ + S2~ + 2S
(3) 3FeS2 + 80H~ £ Fe^ + S2~2 + 2S
~2
~2
However, experimental studies on leaching of coal at Battelle have
demonstrated that sulfur species found in the spent leachant is sodium
sulfide, Na2S, if the leaching is carried out to eliminate oxygen from the
system. This data would indicate that the sulfur extraction mechanism may
be as follows:
(A) FeS2 +2NaOH -»• Fe(OH>2 + Na S_
(5) Na2S2 + Fe(OH)2 ->• Fe^ + Na2S
or (6) Na2S2 + coal ->- C02 + Na2S.
In Reaction (4j, the pyritic sulfur is extracted as the disulfide. The
disulfide is then chemically reduced to form the sodium sulfide (Na.S) by
the ferrous hydroxide [Fe(OH)2] (Reaction 5) or by the carbon in the coal
(Reaction 6) .
Mechanism for extraction of organic sulfur from coal has yet to
be resolved. This could occur by cleavage of carbon to carbon or carbon
to sulfur bonds. A simple organic sulfur compound (CH3 - S - CIO has been
identified in the gases evolved during desulfurization of the coal.
995
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Leachant Regeneration
As discussed above under desulfurization mechanism, the spent
leachant contains sulfide sulfur as Na.S which must be removed in order to
recycle the leachant. One approach for achieving this is by the CO.-CaO
prpcess. This involves
(1) Liberation of the sulfide sulfur as H2S by carbonation
according to the following reactions
NaOH -I- Na2S + C02 ^2> H2St + NaHCOj
NaHCO_ + A -»• Na_CO_ + C0«.
(2) Regeneration of NaOH by treatment of solution from
(1) above with lime.
Na2C03 + CaO •* CaC03 + NaOH.
(3) Regeneration of CaC03 for recycle by thermal
decomposition
CaC03 + A -»• CaO + C02t.
Other potential approaches will be discussed later.
Process Improvements
Leachant Regeneration
The sodium sulfide (Na2S) must be removed prior to recycle of
the leachant. If not, the build-up of Na2S will result in successively
lower sulfur extraction as the leachant is recycled.
Under this program, a number of potential regenerates for regenera-
tion of the spent leachant have been screened:
(a) Zinc Oxide (ZnO)
(b) Sodium Zincate (Na2Zn02>
(c) Metallic Zinc (Zn)
996
-------
(4) Metallic Iron (Fe)
(5) Ferrous Oxide (FeO)
(6) Ferrous Hydroxide [Fe(OH>2]
(7) Ferroso-ferric oxide (Fe30.)
(8) Ferric Oxide
(9) Ferric hydroxide [Fe(OH>3]
(10) Hydrogen reduced/Oxidized Iron Oxide
(11) Sodium ferrite (Na2Fe02)
(12) Ferrous Carbonate (FeCO,)
(13) Activated Carbon .
Effectiveness of Regenerates. A number of regenerates were found
to be effective in removing greater than about 85 percent of the total sulfide
sulfur from the spent leachant.
Zinc-Containing Materials. The addition of zinc oxide, sodium
zincate and metallic zinc to the spent leachant results in the formation of
an insoluble zinc sulfide. As noted in Figure 2, zinc oxide at ZnO/S
ratios of 1.25 to 1.75 resulted in the removal of greater than 85 percent
of the sulfide sulfur in approximately 20 minutes at 80 C. At a ZnO/S
ratio of 3, 100 percent of the sulfide sulfur was precipitated in less than
10 minutes. At 40 C, ZnO was still effective, but longer time was required
to achieve a high degree of sulfide removal. Zinc metal was also effective.
However, larger Zn/S ratios were required because of the lower surface area.
Iron-Containing Compounds. A number of iron-containing compounds
have been investigated for Regeneration of the spent leachant. Of these,
iron hydroxides, reduced/oxidized iron oxide, and ferrous carbonate
are the -most effective as noted in Figure 3.
Ferrous carbonate (FeCO,) is the leading candidate. As shown in
Figure 4, 80 to 99 percent of the sulfide sulfur is precipitated in less than
15 minutes depending on the Fe/S ratio and source of FeCO..
The use of the carbonate makes use of known chemistry. The
sulfide sulfur is precipitated from the spent leachant by the following
reaction:
997
-------
Temperature 80 C
O Zn 0/S « I , Zincate
V ZnO/S * I , ZnO
D ZnO/S= 1.25, ZnO
O ZnO/S- 1.75, ZnO
X Zn 0/S * 3, ZnOe
Temperature 40 C
ZnO/S= I, ZnO
ZnO/S= 3, ZnO
30
Time , minutes
FIGURE 2 . LEACHANT REGENERATION WITH ZnO (BATCH REACTION) AND ZINCATE
998
-------
100
90
80
S 70
"o
1 60
o 50
»_
i^>
-------
100
90
80
70
. 60
50
2 40
30
20
10
Synthetic Fe 0)3
Natural Fe €03 {Ball milled)
FelS RATIO
+ 3
• 10
A 10
O 3
a i.s
10 20 30 40
Time, minufes
50 60
70
FIGURE 4. SULFIDE SULFUR REMOVAL WITH FERROUS CARBONATE
1000
-------
+ (Na2S - NaOH) -»- FeS4- + (Na_CO - NaOH) .
The regenerated leachant will contain some Na.CCL. This can be removed by
the addition of lime (CaO) which results in the precipitation of an insoluble
calcium carbonate.
The iron values may be regenerated for recycle accordingly:
V
FeS + 20 - *• FeS0
FeSO, + Na«CO_ •*• FeCO. I + Na.SO.
4 23 j Z 4
FeS + 20. + Na CO H2 FeCO, + + Na.SO,
f. i J J t H
Reduced/oxidized ferric oxide, i.e., a ferric oxide which is
first reduced with hydrogen to a pyrophoric state and then partially oxidized
effectively removes the sulfide sulfur from the spent leachant. As shown
in Figure 5, 80 to 90 percent of the sulfide sulfur was removed by contacting
the spent leachant with the reduced oxide for a period of 60 minutes.
Preliminary results indicate that the spent reduced oxide can be
regenerated for recycle. As shown in Figure 6, first regenerated iron oxide
was as efficient as the original reduced/oxidized iron oxide. The material
regenerated the second time showed a slightly lower activity after the re-
duction/oxidation treatment. However, this may be due to a lower Fe/S ratio—
11 compared to 8.
Freshly prepared iron hydroxides also separate the sulfide sulfur
from the spent leachant. At room temperature, 98 percent of the sulfur
(Figure 7) was removed in 1 hour at an Fe/S ratio of 3 with ferric hydroxide
When the reaction temperature was reduced to 0 C, 90 percent of the sulfur
was removed. At 80 C, reversal of sulfide removal was suggested. Ferrous
hydroxide appears to be less effective than ferric hydroxide as shown in
Figure 3. The primary disadvantage of these materials is that the spent
hydroxides are not readily regenerated for recycle.
Liquid/Solid Separation
The coal product slurry from the desulfurization segment of the
BHCP contains (1) desulfurized coal and (2) spent leachant. This slurry is
1001
-------
too
90
5
60
o.
. 70
I 60
£
c 50
§ 40
o
0>
•o
30
20
10
O
Exposure to
air, mln
1
O
A
X
D
0
.o
5
5
3
0
[
15
0 30 60 90 130
Reaction Time , minutes
FIGURE 5. EFFECT OF THE PERIODS OF EXPOSURE TO AIR OF REDUCED
IRON OXIDE ON REDUCTION IN SULFIDE CONCENTRATION
1002
-------
100
90
•£
o 80
Q>
a
u
i
70
60
o
so
40
30
20
10
I I
O First regeneration
X Fresh iron-oxide
A Second regeneration
I I
I I
I I
0 30 60 90
Reaction Time, minutes
FIGURE 6. EFFECT OF REGENERATION OF SPENT IRON OXIDE
120
1003
-------
100
90
80
70
60
0)
Q.
o>
| 50
(/>
.5
c 40
30
20
10
20 30 40
Time, minutes
50
60
FIGURE 7. THE EFFECT OF TEMPERATURE ON LEACHANT REGENERATION WITH Fe(OH}3
1004
-------
first filtered to remove the primary filtrate from the cleaned coal product.
This material is then washed to separate the residual spent leachant from the
clean (HTT) coal.
In the initial development of the BHCP, 70 percent minus 200 mesh
coal was used. This resulted in a HTT coal containing equal to or greater
than 50 percent moisture and large quantities of water were required to
separate the residual spent leachant from the HTT coal. Also, the liquid/
solid separations proceeded slowly.
Analysis of this segment of the process indicated that process
improvements — reduced water consumption and lower water content of the coal
product — might be realized by the use of larger particle size coal. There-
fore, a study was conducted to
• Increase liquid/solid separation rate
• Reduce moisture content of HTT coal product
• Minimize wash water consumption and
• Maximize sodium removal and
thus determine a near-optimizing separation and washing circuit. Two sizes
of coal were examined — 100 percent minus 20 percent and 100 percent minus
50 mesh.
Approach. Because of the large scale nature of the planned appli-
cation and the slow to moderate separation rate, separation by large, com-
mercially available equipment was selected for intensive study. The use of
filtration aids, surfactants, and oil agglomeration to improve separation
rates and final cake moisture were also studied.
Because of the complex nature of the separation and washing
circuit and its interactions with other cost sensitive sections of the BHCP,
a computer program was prepared to investigate the relationships between
the total separation and washing costs and the following processing variables:
(1) Separation equipment (vacuum and belt
filter, plus centrifuge)
(2) Separation rates
(3) Cake solids content
(4) Wash water-to-coal ratio
(5) Number of washing stages
1005
-------
(6) Residual unbound sodium.
Sensitivity studies allowed rapid investigation of the different separation
techniques and showed where the most significant cost saving could be obtained.
Technical Achievements. Through the use of coarser coals (-20 and
-50 mesh coal as compared to -200 mesh) and other process modifications,
significant process improvements were realized.
Separation Rate. When the original -20 mesh solution was tested,
a rate of only 0,008 ton/hr/ft2 was obtained. Pretreatment testing was
first conducted to improve the rate. The use of flocculants resulted in
floating of the fines, allowing the coarser material to settle. Consequently,
the fines settled on the surface of the cake, resulting in an effective
barrier to further dewatering. Dispersants (sodium lauryl sulfate was found
most effective) were found to solve this problem by dispersing the fines
throughout the cake. Separation rates were increased by a factor of 10 to
0.08 ton/hr/ft2 at an addition level of 0.5 Ib/ton.
After the initial dispersant addition, separation rate was found
to be primarily dependent on the degree of washing, increasing after each
O
wash until it leveled off at >0.6 ton/hr/ft . Results with -20 and -50
mesh HTT coal are summarized in Table 1, As noted in the table, the degree
of washing also has a strong effect on the final moisture content of the coal
product.
Moisture Removal. The original separation tests with -20 mesh
coal produced a cake with * 59 percent moisture. The use of dispersants for
separation rate improvement also improved the moisture removal efficiency
during separation. The cake showed lower moisture retention with the smaller
-50 mesh coal. However, this trend to less moisture retention with smaller
particle sizes did not extend downward to the -200 mesh coal where * 60 per-
cent moisture cakes were produced . Since the separation rates with the -50
mesh were not significantly less than with the -20 mesh coal, this size
range seemed near optimal for further development work.
Other measures to further reduce the moisture content included
oil agglomeration prior to separation, solvent displacement, and centrifu-
gation. The oil agglomeration tests showed that increased separation rates
1006
-------
TABLE 1.
VACUUM FILTRATION RATE AS A FUNCTION OF
PARTICLE SIZE AND WASHING STAGED
Ground
Rate,
kkg/hr/m2
(ton/hr/ft2)
0.78
(0.08)
0.88
(0.09)
2.93
(0.3)
5.86
(0.6)
>5.9
-20 Mesh
Moisture Level,
percent
53
53
54
54
55
Washing Stage
Initial separation
First wash
Second wash
Third wash
Fourth wash
(a) Vacuum filtration employing 28 in. Hg vacuum. Slurry initially treated with a
sodium lauryl sulfate dispersant to improve water removal.
Ground
Rate,
kkg/hr/m2
(ton/hr/ft2)
0.78
(0.08)
1.95
(0.2)
2.93
(0.3)
5.86
(0.5)
5.86
(0.6)
-50 Mesh
Moisture Level
percent
48
49
50
51
52
1007
-------
2
of 1.9 tons/hr/fc could be obtained; however, the moisture content of the
clean coal was reduced by only 1 to 3 percent. A washing test with a
mixture of toluene and ethyl alcohol was conducted on a high moisture
extensively washed cake. The solvents effectively displaced the water
from the cake but did not reduce the moisture content of the coal product.
Drying tests with the solvent washed coal showed that drying energy require-
ments were reduced in half as compared to the water washed coal.
For centrifuge testing, HIT coal was prepared in the continuous
30 Ib/hr miniplant. A 6-14 bird screen bowl centrifuge was continuously fed
with the miniplant output. While the centrifuge equipment was considered
too small to generate accurate separation rate data, the test program did
establish that the final moisture content could be lowered to ^ 40 to 42
percent.
Sodium Removal. The residual sodium remaining in the treated coal
must be reduced for economic reasons (for sodium recycle and reuse) as well
as combustion (corrosion) considerations. The sodium can be removed by dis-
placement or repulp washing. Displacement washing occurs by the wash liquor
pushing the filtrate ahead of it through the void channels with practically
no filtrate dilution. In experimental testing, it was established that the
HTT coal cake, due to its compressive nature resulting in low sodium removal
and low separation rates, and thus, was not amenable to this washing technique.
Therefore, emphasis was placed on repulp washing.
Repulp washing consists of mixing the separated filter cake with
wash liquor and refiltering. The process eliminates stratified regions in
the cake that are washed at different levels, assures close contact of the
wash liquor and the soluble materials, increases the rate of diffusional
extraction and, with proper media selection, can allow selective removal of
slow filtering fines. This method of washing can be incorporated into a
washing circuit employing almost any type of separation equipment. It is
especially suited for counter-current "extraction" washing. Counter-current
extraction offers the most economical use of wash liquor, permitting high
sodium concentrations in the final extract sent to the evaporator and re-
1008
-------
generation, and high solute recovery from the treated coal with a minimal
amount of fresh wash water. Stepwise counter-current extraction is com-
mercially employed for leaching of solids and washing of precipitates.
The washing scheme developed for HIT coal consists of a number
of separation stages in series. Fresh wash water is mixed with the treated
coal which has been most nearly exhausted of residual sodium. The fil-
trate from that operation is advanced progressively from one separation
stage to the next until the most concentrated solution discharges from the
separation stage where the fresh HTT coal slurry enters. Simultaneously
the separated solids are transferred from one stage to the next in the
opposite direction finally exiting from the fresh water washing stage. Be-
cause of the difficulty of simulating a multistage counter-current washing
circuit, washing tests were conducted by repulp washing of the separated
solids with fresh wash water rather than washing with filtrate from con-
secutive washing.
The first variable studied was coal particle size. It was
theorized that the smaller particles could be washed easier because more
of the sodium would be on the surface with less inside the coal particle.
As noted in Figure 8, the smaller -100 mesh particles were more readily
washed than the larger particles. The difference while significant was
not sufficiently large to stop work on alternate methods of washing the
larger, more rapidly filtering coal particles. A series of tests with
the -50 mesh coal were conducted using a 2 to 1 water-to-coal ratio
employing (1) extended (1 hr) mixing time to allow a longer time for dif-
fusional controlled removal of the sodium, (2) a saturated CO, water wash
to react with the sodium, and (3) a saturate lime water wash to promote
greater ion exchange between the calcium and sodium.
The results are displayed in Figure 9. Clearly the saturated lime
water wash was superior to the standard washing results. Apparently the
dissolved calcium in the lime water promoted effective exchange with the
sodium. In fact, the bound sodium (sodium not removable by extensive wash)
was lowered from ~ 0.5 to ^ 0.1 percent. This result was especially signifi-
1009
-------
- 20 Mesh
-50 Mesh
-100 Mesh
0 2 4 6 8 10 12
No. of Fresh Wbter Washing Stages
FIGURE e. SODIUM REMOVAL VERSUS NUMBER OF WASHING
STAGES AS A FUNCTION OF STARTING COAL
PARTICLE SIZE
1010
-------
Standard wash
Extended repulp (1-hr)
Sat. C02-wa1er wash
Sat lime's
water wash
0 2 4 6 8 10 12
No. of Fresh Water Washing Stages
FIGURE 9. SODIUM REMOVAL VERSUS NUMBER OF WASHING
STAGES FOR -50 MESH HIT COAL AS A FUNCTION
OF SPECIAL WASHING METHODS
1011
-------
cant since it allows removal to the desired 0.5 percent total sodium level
with a reasonable number of washing stages and impregnates the coal with a
sulfur getter.
Wash Water Usage. The final variable needed to complete the L/S
separation circuit design was the wash water-to-coal ratio. This is a com-
plex variable because of its many interactions with the rest of the BHCP.
The ratio chosen will effect the size of the separation equipment, number of
stages, size and number of pumps and piping, downstream storage requirement
as well as evaporation and regeneration requirements. Therefore, the wash
water-to-coal ratio was selected by computer simulation. However, before
the simulation could be conducted, a correlation between theoretical and
actual sodium removal in a counter-current extraction* circuit was required.
Because multistage counter-current extractions are difficult and time con-
suming to conduct washing tests were conducted with fresh water. It was
found that approximately 2.5 actual stages were necessary to obtain the same
sodium removal as predicted by one theoretical stage. This stage efficiency
was found to be a constant even up to 10 repulp washes (i.e., 10 repulp
washes removed as much sodium as predicted after four theoretical washes).
With this information the "optimum" separation and washing circuit was
designed.
Washing Circuit Design. A computerized cost model was designed to
simulate the separation, washing, and evaporation (prior to regeneration)
section of the BHCP. The model was based on counter-current extraction
washing of the solution produced in the desulfurization autoclaves. For the
initial slow filtering -stages disc filters were selected and for the more
rapid filtering stages (fifth and higher), belt filters were chosen, A final
stage screen bowl centrifuge was Included for dewatering to 42 percent
moisture. Theoretical counter-current extraction equations were adjusted
to allow for the experimentally determined 40 percent stage efficiency.
1012
-------
The optimum circuit design depends on the bound sodium level. A
relatively conservative level of 0.27 percent was specified. Based on the
experimental data generated, the filter and centrifuge cake moisture content
levels were set at 52 and 42 percent, respectively. The optimum design,
displayed schematically in Figure 10 consists of a counter-current washing
circuit composed of the following separation elements:
(1) Four disc filter stages
(2) Six belt filter stages
(3) One centrifuge stage.
A wash water-to-coal ratio of 1.75 was required to produce a final product
with 0.47 percent (moisture free basis) total sodium.
Sodium, Ash, and Sulfur Levels. Chemical analyses of the raw and
a typical product cake are summarized in Table 2. Three components are of
special Importance. First, the total sodium is below the desired 0.5 percent
required for satisfactory boiler operation. Second, the ash content is
slightly lower than that of the raw coal. Since both calcium and sodium
levels are higher than in the starting coal, the reductions in ash are due
to removal during the desulfurization step and subsequent downstream proces-
sing. Finally, and of great importance is the MAF sulfur level. Since the
process goal is desulfurization, the product coals sulfur content must be
below the NSPS level. At 0.86 percent MAF sulfur, the coal does meet this
criterion. In addition, the high residual calcium level has been shown to
lead to in-situ sulfur capture making the combustion off-gas even lower in
SO- than that anticipated from the coal's sulfur content.
1013
-------
Row Story
Solids nitrate
Enclosed Rotary Vocuum Disc Filters
Fresh IflfcisJi Water
175 b/t> coal
Enclosed Honzond Vacuum Bdl FUer
Screen Bowl Centrifuge
FIGURE 10. HTT COAL WASHING AND SEPARATION CIRCUIT
-------
TABLE 2.
CHEMICAL ANALYSIS OF RAW AND HYDROTHERMALLY
DESULFURIZED PITTSBURGH SEAM (WESTLAND) COAL
HgO Ash, MF
-------
SURVEY OF COALS TREATED BY OXYDESULFURIZATION
R. P. Warzinskl, J. A. Ruether, S. Friedman, and F. W. Steffgen
U.S. Department of Energy
Pittsburgh Energy Technology Center
Pittsburgh, Pennsylvania
ABSTRACT
The feasibility of using only compressed air and water at elevated
temperature to reduce the sulfur content of coal has been demonstrated in
autoclave experimentation at the Pittsburgh Energy Technology Center for
various coals from most of the major coal basins in the United States. This
air/water oxydesulfurization consistently removes in excess of 90 percent
of the pyritic sulfur and has the potential for reducing the organic sulfur
content by up to 40 percent. The sulfur liberated from coal by this reaction
is present in the aqueous effluent as dilute sulfuric acid which can be
neutralized with limestone. Under certain reaction conditions pyrite forms
a jarosite intermediate which reports as organic sulfur in chemical analysis.
Extent of organic sulfur removal and loss of heating value increase with
temperature in the range 170°-200°C.
1016
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INTRODUCTION
Precombustion removal of sulfur and minerals from coal by
physical/chemical cleaning is a developing technology that will
provide alternate approaches to the electric utility industry
and industrial boiler installations for complying with EPA
New Source Performance Standards (NSPS) and future revisions
without relying totally on flue gas desulfurization (FGD)
(Friedman and Warzinski, 1977). These approaches could vary
from physical/chemical cleaning alone to combining it with FGD.
A combination approach could potentially reduce capital and
operating costs by increasing reliability, reducing duplication
of equipment needed to achieve present reliability, improving
feedstock uniformity, reducing trace elements and ash constituents
responsible for deposits and corrosion, and reducing sludge
disposal problems. (Engdahl and Rosenberg, 1978; Balzhiser, 1978).
The only methods of coal cleaning practiced commercially are
physical methods which utilize density differences and surface
properties to achieve separation of coal and associated minerals.
At an acceptable level of fuel value loss physical cleaning removes
only accessible pyritic sulfur, leaving behind that which is finely
1017
-------
divided throughout the coal matrix and sulfur chemically bound to
the organic coal matrix. Therefore, only a small percentage of
coals can be brought into compliance using only physical cleaning.
On the other hand the selective chemical removal of sulfur
from coal is capable of approaching complete pyritic sulfur
elimination and, depending on the process, removal of the reactive
organic forms of sulfur in coal.
A variety of chemical cleaning processes are under development
and have been reviewed in the literature. (Friedman and Warzinski,
1977; Oder, et.al., 1977; Versar, Inc., 1978; Meyers, 1977). This
report deals with the developmental research of one of these tech-
niques, air/water oxidative desulfurization (termed Oxydesulfurization).
Air/water oxidative desulfurization has been demonstrated in
autoclave experiments for various coals representative of the
major U.S. coal basins (Friedman and Warzinski, 1977). The reaction
proceeds most effectively at temperatures of 150 to 200 C
at a total system pressure of 3.5 to 10.4 MPa (500 to 1500 psig).
Above 200° C, coal and product heating value losses become sub-
stantial due to the oxidative loss of carbon and hydrogen. The
pyritic sulfur solubilization reactions are typically complete
(95 percent removal) within 15 to 40 minutes at temperature;
however, significant organic sulfur removal requires residence
times as long as 60 minutes at the higher temperatures. The
principal products of the reaction are sulfuric acid and iron
oxide. Several samples of coals treated by air/water oxidative
desulfurization were exhaustively extracted with toluene which was
1018
-------
then removed on a rotary evaporator. No elemental sulfur was
detected.
Although little is known of the organic sulfur reactions
(Friedman, LaCount and Warzinaki, 1977), the pyrite/air oxidation
reaction in aqueous media has been studied extensively by Vracar
and Vucurovic (1970, 1971, 1972) in relation to producing sulfuric
acid from pyrite for use in ore extraction. The following reactions
were proposed for finely ground pyrite based upon conditions
similar to those used for coal by Friedman and Warzinski (1977) .
2FeS2 + 702 + 2H20 •* 2FeS04 + 2H2S04 (1)
2FeS04 + 1/202 + H2S04 + Fe2(S04)3 + HgO (2)
)3 + nH20 •* Fe203- (n-3)H20 + 3H2S04 (3)
)3 + 14H20 + 2Fe3(S04)2(OH)5'2H20 + 5H2S04 (4)
Above 140° C no elemental sulfur was observed. Small amounts
of the basic jarosite salt (reaction 4) were formed at lower
pH and temperature. Vracar and Vucurovic (1972) observed that for
a 20 gm/1 pyrite slurry under the conditions 200° C, 0.61 to 1.02 MPa
(74-133 psi) oxygen partial pressure, and 3 hour residence
time, pyrite was completely converted to sulfuric acid and iron
oxide. At temperatures below 200° C small amounts of unreacted
pyrite, ferrous, and ferric sulfate were present. The pyrite
reaction rate was found to be first order in unreacted pyrite
with an activation energy of 51.0 kJ/mole (12.2 kcal/mole) . In
a more recent kinetic study, Slagle (1978), using an Upper Freeport
coal under similar conditions, also found the pyritic sulfur reaction
to be first order in unreacted pyrite with an activation energy
of 46.7 k J/mole (11.2 k cal/mole) . The organic sulfur data were
1019
-------
scattered, but were fitted to a zero order rate expression with an
activation energy of 78.7 k J/mole (18.8 k cal/mole). Broader
reviews of pyrite oxidation and coal sulfur oxidation have been
published by Meyers (1977) and Slagle (1978) covering reaction
temperatures and pressures outside the ranges utilized for air/
water oxydesulfurization.
EXPERIMENTAL
Air/water Oxydesulfurization coal screening experiments
consist of treating a slurry of 35 gm of 200 x 0 mesh coal in 100
ml distilled water contained in a glass, teflon, or stainless steel
liner inserted into a one liter, magnetically stirred, 316 stain-
less steel autoclave. The autoclave system can be operated in
batch or semibatch modes. In the batch mode the autoclave contain-
ing the slurry is pressurized with air at room temperature to the
desired oxygen partial pressure and subsequently heated by a
jacket type heater to reaction temperature at a rate of approximately
3° C/minute. The slurry is agitated at 900 to 1000 RPM with a
3.175 cm diameter gas dispersion turbine-type impeller. Reaction
temperature, once reached, is stabilized to within + 2° C by a
proportioning temperature controller and manually operated internal
water cooling coil. After the desired residence time at reaction
temperature, the cooling coil is used to quench the reaction by
lowering the temperature at a rate of approximately 50 to 60° C/
minute. When the autoclave reaches room temperature a gas sample
is taken and the product slurry removed.
The product slurry is filtered through Whatman 541 paper in
a Buchner funnel and washed with distilled water until the pH of
1020
-------
the filtrate tests 4 to 5 with litmus paper, normally requiring
about one liter of distilled water. The product coal is extracted
on a Soxhlet with distilled water until all soluble sulfates are
removed, as determined with barium chloride. Analyses of the
initial filtrate and Soxhlet washings indicate greater than 90
percent of the soluble sulfur compounds are removed from the
product coal in the first wash. The coal sample is finally
vacuum dried at 110° C for approximately 2 hours, weighed, and
sent for analysis.
In the semibatch mode of operation a constant air flow in
the range of 52 to 208 liters/hour (STP) is used to maintain con-
stant system pressure and essentially constant oxygen partial
pressure throughout the reaction. In order to minimize the
evaporation and loss of water from the slurry, approximately 70 ml
of distilled water is placed between the reactor wall and the
liner while charging the autoclave to help saturate the effluent
gas. The autoclave is purged with nitrogen at atmospheric pressure,
closed off, and heated to reaction temperature. When this temper-
ature is attained the autoclave is rapidly pressurized with air to
the desired operating pressure and the continuous air flow started.
The reaction is quenched by terminating the air flow and using the
internal cooling coil. Gas samples are normally taken during and
at completion of the reaction. The product workup is identical
to that of the batch mode.
1021
-------
RESULTS AND DISCUSSION
Twenty-four coals have been treated by air/water oxidative
desulfurization. Data for sulfur removal are given In Table
1, and the balance of the ultimate analyses are in Table 2.
All twenty-four coals, unless noted in Table 1, were treated
for one hour at the temperature indicated under either 5.6
MPa (800 psig) initial air pressure in the batch mode or 7.0
MPa (1000 psig) total system pressure in the semibatch mode.
An air flow of approximately 200 liters/hour (STP) was used
in the semibatch mode. The mode of operation is also indicated
in Table 1. The first ten coals in the two tables would
meet the current EPA NSPS of 1.2 Ib SO* per 10^ BTU. Due to
retention of sulfurous products in the ash during combustion,
coals containing somewhat greater than 0.6 Ib S per 106 BTU
can be expected to meet NSPS (EPA, 1977). Reflecting the
greater effectiveness of Oxydesulfurization for removing
more pyritic than organic sulfur, all ten of the untreated
coals had less than one percent organic sulfur.
Coals 11-17 in the two tables had moderate amounts of
organic sulfur, up to 1.5 percent. Depending on the sulfur-
retention properties of the ash, some of these coals might
meet NSPS. Relatively small improvements in Oxydesulfurization
processing could also bring these coals into compliance.
Coals 18-24 in the two tables had high organic sulfur
contents, greater than 1.5 percent. For these coals significant
improvement in organic sulfur removal would be necessary to
bring them into compliance. However, due to their high
organic sulfur contents, these coals have been used to
1022
-------
Weight Percent (Moisture Free)
*
1
3
4
5
6
7
8
9
10
11
1- "
0 "
K) 14
t»> 15
16
17
18
19
20
21
22
23
24
Coal Seam
Black Creek
Imboden
Lower Freeport
Lower Kit tanning
Middle Kittanning
Mammoth
Pittsburgh
Upper Freeport
Upper Freeport
Brookville
Lower Freeport
Pittsburgh
Pittsburgh
Pittsburgh
Whitebrest
Wyoming No. 9
Bevier
Illinois No. 5
Illinois No. 6
Indiana No. 5
4
Mlnshall
Pittsburgh
Mine
Natural Bridge Strip
Peacock
Paramount Elkhorn
No. 1 Strip
Luciusboro Strip
2
Congo Strip
Storm King
Bruceton
Baker
Coal Junction Strip
Humphrey
West Valley Strip
Pitkulski Strip
No. 43 Strip
No. 43 Strip
Lovilia No. 4
Reliance
Ho. 22 Strip
3
River King
Enos
Homestead
Chrisney No. 1
Ireland
State
AL
CO
VA
PA
FA
OH
MT
PA
MD
PA
PA
PA
PA
OH
OH
1A
WY
KS
IL
IL
IN
KY
IN
WV
ASTM
Rank
Mvb
HvBb
HvAb
HvAb
LvB
HvCb
SbA
HvAb
Mvb
Mvb
HvAb
HvAb
HvAb
HvAb
HvBb
HvCb
HvCb
HvAb
HvCb
HvBb
HvBb
HvAb
HvBb
HvAb
»
1.22
1.88
1.19
2.83
0.96
1.08
0.83
1.31
1.58
2.14
4.20
4.14
1.67
3.88
3.01
5.85
1.75
5.00
3.34
3.69
3.27
4.80
5.65
3.89
-Sulfur.
0.65
0.67
0.95
0.75
0.57
0.60
0.57
0.80
0.54
0.63
1.17
1.04
0.89
1.05
0.98
1.07
0.90
1.98
2.03
2.12
1.84
2.34
1.43
2.09
Pyritic
Untr
0.42
0.95
0.26
2.03
0.53
0.26
0.32
0.61
0.82
1.37
3.06
3.09
0.71
2.36
1.93
3.95
0.38
2.92
0.92
1.13
0.70
1.08
3.01
1.38
Sulfur
Tr
0.16
0.10
0.04
0.02
0.08
0.04
0.18
0.05
0.02
0.04
0.13
0.22
0.03
0.19
0.16
0.18
0.06
0.36
0.12
0.11
0.20
0.12
0.10
0.02
Organic
Untr
0.69
0.60
0.78
0.65
0.39
0.78
0.45
0.68
0.56
0.49
1.11
1.01
0.82
1.48
1.05
0.90
1.14
2.04
2.06
2.25
1.98
2.33
1.53
2.18
Sulfur
~~Tr
0.47
0.57
0.79
0.68
0.47
0.55
0.36
0.71
0.50
0.50
1.01
0 78
0.83
0.84
0.80
0.76
0.82
1.60
1.82
2.00
1.64
2.14
1.22
2.03
BTU/lb
Untr
13595
13123
14273
12775
14590
11184
11770
14170
12642
11256
13250
13112
11650
12657
12846
10870
12410
12203
12650
12190
12340
11380
11320
13390
&>
11694
11001
13977
11944
13630
9648
10910
13430
11117
10213
11346
11395
10890
10780
10787
9140
11480
12224
11600
10030
10095
11250
10230
12190
Recovery
94
92
100
99
98
89
92
100
99
95
96
98
100
98
98
81
101
93
90
89
91
93
85
99
IbsS/MM
Untr
0.90
1.45
0.83
2.22
0.66
0.96
0.70
0.92
1.25
1.90
3.17
3.15
1.43
3.06
2.34
5.38
1.41
4.10
2.64
3.03
2.65
4.22
4.99
2.90
BTU
Tr
0.56
0.61
0.61
0.63
0.42
0.62
0.52
0.60
0.48
0.62
1.03
0.91
0.81
0.97
0.90
1.17
0.78
1.62
1.75
2.11
1.82
2.08
1.40
1.71
Reaction
Temperature ( C)
ISO*
2003
150^
ISO3
150,
mo3
150
ISO*
200?
2003
180
180
160
180
180,
150°
150
150
150,
150'
250'
160
200
180
1. Uncorrelated Coal Seam 2. Obtained from Cambria Slope Preparation Plant 3. Information Not Available
4. Blend of Kentucky Seams No. 9, No. 11, No. 13 5. Modified Semicontinuous Mode (8-9 SCFH Air Flow) All others batchflow.
6. Four repressurizations in batch mode. 7. 1500 psig Initial Air in batch mode
Table I. -
8 Untreated 9.
Summary of Coals Treated By Air/Water Oxydesulfurization
Treated
-------
Moisture Free-Weight Percent
Carbon
Hydrogen
Nitrogen
Oxygen
Coal1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
/—
Untr^
3.7
6.5
3.7
15.1
7.1
16.9
9.5
5.5
16.2
22.4
9.3
11.7
21.4
12.7
11.2
17.4
3.2
14.8
8.7
11.6
9.1
14.1
15.9
7.8
" TrJ
2.6
5.2
3.4
13.3
7.0
15.3
7.5
4.6
14.6
21.4
6.6
8.8
20.1
10.4
9.3
16.4
2.1
12.0
6.6
11.0
11.5
11.4
11.1
6.8
Untr
76.9
73.7
80.2
72.5
83.5
64.6
68.4
79.4
72.3
65.0
73.3
73.5
65.4
70.7
72.1
63.0
72.4
68.6
70.8
68.4
69.4
63.8
62.8
73.4
Tr
71.6
68.0
79.6
70.2
79.8
59.6
66.4
76.5
67.7
62.0
68.2
68.2
63.0
66.1
66.1
56.3
69.2
69.3
68.2
61.0
63.4
65.4
63.2
71.0
Untr
5.2
5.3
5.1
4.5
4.4
4.4
4.5
5.3
4.3
3.6
5.2
4.9
4.4
4.8
4.8
4.2
4.7
4.8
5.0
4.6
4.9
4.6
4.6
5.1
Tr
3.8
3.6
4.9
3.9
4.1
3.4
4.0
4.8
3.3
3.0
3.9
3.7
3.9
3.8
3.6
3.3
4.2
4.7
4.3
3.4
3.1
4.2
3.3
4.5
Untr
1.6
1.6
1.5
1.3
1.4
1.2
1.2
1.5
1.3
1.1
1.7
1.3
1.3
1.6
1.8
1.2
1.6
1.1
1.4
1.2
1.6
1.3
1.2
1.3
Tr
1.6
1.9
1.4
1.3
1.4
1.1
1.2
1.5
1.2
1.2
1.4
1.2
1.3
1.4
1.3
1.1
1.5
1.2
1.4
1.1
1.5
1.4
1.3
1.2
Untr
11.4
10.9
8.4
3.7
2.6
11.8
15.6
7.0
4.3
5.9
6.3
4.5
5.9
6.4
7.0
8.3
16.4
5.7
10.7
10.6
11.8
11.3
9.8
8.5
Tr
19
20
9.
10.
7.
20.
20.
11.
12.
11.
18.
17.
10.
17.
18.
21.
22.
10.
17.
21.
18.
15.
19.
14.
.8
.5
9
6
2
0
4
7
7
8
7
0
7
2
7
9
0
8
6
2
7
3
7
4
LSee table 1. 2Untreated -"Treated
Table 2. - Summary of Coals Treated by Air/Water Oxydesulfurization
-------
investigate the removal of organic sulfur by air/water
oxidative desulfurization.
With increasing severity of operating conditions,
increasing amounts of organic sulfur can be removed. However,
the organic sulfur removal is accompanied by heating value
losses for the coal. This is not surprising, since one would
expect oxidation of organic structures to proceed at a rate
at least comparable to that for oxidation and cleavage of
some C-S bonds. An organic sulfur removal efficiency may be
defined as the ratio of the differential increase in organic
sulfur removal to the differential increase in heating value
loss. So defined, this efficiency is equal to the slope of
a line describing data as plotted in Figure 1. The data,
from Table 1, exhibit considerable scatter. It should be
remembered that, besides temperature variations, the data
also represent coals of six different ranks, ranging from
hvAb to sbA. Slagle and Shah (1978) prepared a similar plot
for a single coal with variable temperature and observed a
linear correlation superior to that shown in Figure 1.
The data in Figure 1 and those of Slagle and Shah
(1978) were both for a single top size of coal, 200 mesh.
Wheelock et. al. (1978) have presented data from which plots
such as Figure 1 may be constructed for top sizes of 200 and
400 mesh. Such plots reveal a higher organic sulfur removal
efficiency for the larger top size of coal. This finding
suggests a surface effect. In the absence of such an effect
the smaller particles would be expected to exhibit a higher
1025
-------
50
o
UJ
o
u
tr
13
O
o
tr
o
i-
z
Ul
o
tr
UJ
a.
40
30
20
10
I
Reaction
temperature
°C
• 150
A 160
• ISO
o 200
V 250
t
10 20 30 40
PERCENT HEATING VALUE LOSS
50
Figure I-Organic sulfur removal efficiency.
1026
8-24-78 L-16208
-------
organic sulfur removal efficiency, since the leachant would
have access to a larger fraction of all sulfur contained in
the coal (Medieros and Peterson, 1976).
The data in Table 2 show an increase in oxygen content
of coal due to processing. This effect is shown graphically
in Figure 2, where moles of oxygen taken up by the coal per
mole of carbon in the product coal is seen to increase with
loss of heating value. Hydrogen and carbon in the coal
decrease due to processing. The data in Table 2 are plotted
in Figure 3. It is seen, for the range of heating value
loss encountered, between zero and 30 percent, that hydrogen
is preferentially removed from the organic matrix. Apparently
heating value is lost both by consumption of the coal to
final oxidation products, carbon dioxide and water, and by
partial replacement of hydrogen by oxygen in the coal.
A beneficial side benefit of Oxydesulfurization treatment
is reduction in the ash content of the coal. Part of the
ash probably is dissolved in the sulfuric acid formed during
reaction. Inspection of Table 2 shows a maximum ash reduction
of 41 percent and an average reduction for all coals treated
of 20 percent.
An interesting effect that has been observed with some
coals is an apparent increase in organic sulfur with oxidative
desulfurization treatment. An example is shown in Figure 4.
The four experiments shown were made on a Lower Freeport
coal according to the standard procedure for the continuous
air feed mode, using the reaction conditions listed. Over 95
1027
-------
20
o
o
16
o
•
UJ
o
12
8
z
UJ
O
CD
'*
» / »
".i
.«/• '
I
I
I
10 20 30 40
PERCENT HEATING VALUE LOSS
Figure 2-Oxygen uptake by coal due to treat-
ment .
50
1028
8-29-78 L-16226
-------
LJ
UJ
o:
o
id
o
o
<
or
UJ
A Hydrogen
0 Carbon
10 20 30 40
PERCENT HEATING VALUE LOSS
Figure 3-Carbon and hydrogen loss due
to treatment .
1029
8-24-78 L-16209
-------
E
o»
•k
UJ
UJ
o:
o
UJ
o
cc
o
UJ
UJ
cr
o
i
o
UJ
• Total sulfur decrease
a Pyritic sulfur decrease
A Organic sulfur Increase
10 20 30 40 50
RESIDENCE TIME , minutes
Figure 4-Apporent increase in organic sulfur with treat-
ment. (Lower Freeport HVAb , I80°C , 1000 psig
air , 35 g coal charge).
1030
8-24-78 L-I62IO
-------
percent of the pyritic sulfur is removed in the first 15
minutes, resulting in a total sulfur decrease of 60 percent.
The organic sulfur registers an apparent increase, however,
with the peak value at 15 minutes being 55 percent larger
than the value for the untreated coal. With longer treat
time the apparent organic sulfur decreases again, the value
at one hour being close to the value for the untreated coal.
We do not believe that organic sulfur is created during
processing, but rather that the anomalous results are an
artifact arising from the analytical determination of organic
sulfur by difference. The formation of jarosite-like basic
salts is well known in hydrometallurgy. One such species is
shown in Equation (4), as suggested by Vracar and Vukurovic
(1970). Other solids can also be formed in our system,
containing as it does ferrous, ferric, and sulfate ions, and
smaller concentrations of other cations. Kwok and Robins
(1973) have reviewed the formation of so-called thermal
precipitates in aqueous solutions. Some of their data
showing the formation of thermal precipitates in aqueous
ferrous and ferric sulfate solutions are shown in Figure 5.
For solutions with ferrous or ferric concentrations as
indicated by a particular curve, a precipitate forms when
the temperature and pH at 25° C place the system to the
right of the curve. From calculated concentrations of
ferrous/ferric ions and measured values of pH, we determine
that the formation of thermal precipitates is possible in
our system.
1031
-------
250
225
UJ
a:
D
*-
<
tr
UJ
a.
2
ui
20O -
o
u>
N>
175 =
I5O
Symbol
Compound
FeS04
NoFe3(S04)2(OH)6
Fe203 - 2S03 • H20 or
3Fe203 • 4S03 • 9H20
NaFe3(S04)2(OH)6
• H20
1' 7z o
Molal cone of Fe or Fe
1.0
O.I
O.I
O.I
0.01
0.001
Figure 5— Thermal precipitation of iron compounds in H2S04 -H20
(Na2S04) system.
L-16225
-------
We believe an explanation for Figure 4 is that jarosite-
like compounds are formed in the early stages of reaction in
which the pyrite is nearly completely consumed. The jarosites
are not the most thermodynamically stable species at reaction
conditions, but may form due to localized fluctuations in
solution concentration in the vicinity of pyrite crystallites
at the time they go into solution. Kept in contact with the
leachant solution the jarosites digest to more stable forms,
ferric oxide and sulfuric acid, which do not contain sulfur
in the solid phase.
A thermal precipitate was formed in an experiment in
which a model sulfur compound was subjected to Oxydesulfurization
process conditions. X-ray diffraction analysis indicated
that the precipitate was jarosite-like. X-ray fluorescence
showed the major components of the precipitate to be iron
and sulfur. No sodium was detected by this method or by
atomic absorption. Therefore, the compound is not natrojarosite,
for which the equilibrium precipitation temperature/acidity
diagram is shown in Figure 5, but rather the basic sulfate
as proposed by Vracar and Vucurovic (1970) in Equation (4).
Analysis of precipitate by a Fisher sulfur analyzer indicated
a sulfur content of 13.4 percent, which is close to the
theoretical value of 13.34 percent for Fe3(S04)2(OH)5*2H20.
To test the possibility that jarosite-like compounds
are responsible for apparent organic sulfur increase, a
sample of an Upper Freeport seam coal was doped with the
collected jarosite-like precipitate and submitted for analysis.
1033
-------
All of the sulfur in the doped coal, including the jarosite
sulfur, was determined by the ASTM Eschka method, but only
86 percent of jarosite sulfur was reported as sulfate sulfur.
None was reported as pyrite; the 14 percent balance, therefore,
reported as organic sulfur. The organic sulfur in the doped
sample, as a result, was 37 percent higher than normal.
TOWARDS A COMMERCIAL OXYDESULFURIZATION PROCESS
Work is continuing at the Pittsburgh Energy Technology
Center to move chemical coal cleaning to a commercial reality.
To this end a continuous reactor has been built and operated
within the past months to conduct air/water oxidative desulfurization.
A slurry bubble column reactor is employed, consisting of a
vertical tube 2.22 cm inside diameter by 183 cm long.
Preheated air and aqueous coal slurry are fed to the reactor
cocurrently at the bottom. The treated coal slurry and exit
gas are removed at the top.
Operation of the continuous reactor to date has been
encouraging. Using an Upper Freeport coal (number 4 in
Tables 1 and 2) at conditions of temperature and pressure as
established in the autoclave work, some results were as
follows. For a slurry space time of 6 minutes, the weight
percent total sulfur was reduced from 1.82 in the feed coal
to 0.87 in the product coal. With a slurry space time of 69
minutes the weight percent total sulfur in the product was
0.70. Slurry space time is defined as reactor volume divided
by volumetric slurry feed rate.
1034
-------
A more complete account of operations with the continuous
reactor will be made at a later time. Our experience to
date however, has enabled us to develop a conceptual flow
sheet for an Oxydesulfurization process. It is shown in
Figure 6. The flow sheet can be considered in three sections:
coal preparation, reaction and coal recovery, and acid
neutralization.
In the coal preparation section run of mine coal is
subjected to a number of conventional physical coal cleaning
operations to remove white rock and some separable pyrite.
These cleaning operations employ a grizzly, rotary breaker,
and jig plant. The physically cleaned coal is stored in a
day bin before being sent to a ring mill and ball mills for
grinding. The ground coal is slurried, preheated, and fed
to a slurry bubble column reactor. Also fed to the reactor
is compressed air. Spent air/ steam from the reactor is
used in a turbine expander to supply some of the power
required for air compression. Product coal from the reactor
is filtered, dried, and is then ready for use.
Effluent water from the reactor, containing sulfuric
acid, is neutralized. Shown on the flowsheet are steps for
the grinding and storage of limestone. The acid water and
limestone are combined in the neutralization tank. By-
product gypsum is removed by filtration, and the treated
water is recycled to the slurry preparation tank.
The flow sheet illustrates the complementarity of
physical and chemical coal cleaning methods. Relatively
1035
-------
ROM
COAL
Slurry
OXYDESULFURIZED
CLEAN COAL
Bowl
mill
Neutralization
tank
„ f CaS04 _.,
jf f*—J To disposal
Figure 6-Oxydesulfurization process
6-27-78 L-I6I20
-------
more washable coals would have a higher fraction of sulfur
removed in the physical preparation section; those less
washable would have a more sulfur removed by chemical cleaning.
Also apparent is the simplicity of the process. Air, water,
and limestone are the only materials required to treat the
coal.
ACKNOWLEDGMENTS
The authors wish to thank Forrest Walker and the Pittsburgh
Coal Analysis Laboratory for performing the necessary analyses
and the Chemical and Instrumental Analysis Division at the
Pittsburgh Energy Technology Center for the various analyses
on the gas, liquid and residue samples. We would also like to
thank Harry Ritz, who is responsible for the construction of
the continuous slurry unit now in operation and for preparing
the process flow diagram, and Robert B. LaCount for his work
in the early part of the research program.
1037
-------
REFERENCES
Balzhiser, E. E. 1978. R & D Status Report, Fossil Fuel and
Advanced Systems Division. EPRI Journal. April. 41.
Engdahl, R. B. and H. S. Rosenberg. 1978. The Status of Flue Gas
Desulfurization. Chemtech. Feb. 118.
EPA. 1977. Coal Cleaning Review. 1(1):1.
Friedman, S. and R. P. Warzinski. 1977. Chemical Cleaning of Coal.
Journal of Engineering for Power. 99(3):361.
Friedman, S., R. B. LaCount, and R. P. Warzinski. 1977. Oxidative
Desulfurization of Coal. ACS Symposium Series. 64:164.
Kwok, 0. J. and R. G. Robins. 1973. Thermal Precipitation in
Aqueous Solutions. International Symposium on Hydrometallurgy.
1033.
Medieros, P. J. and E. E. Petersen. 1976. Changes in the Pore
Structure of Coal with Progressive Extraction. Lawrence Berkeley
Laboratory Report. LBL-4439.
Meyers, R. 1977. Coal Desulfurization. Marcel Dekker, Inc. New York.
Oder, R., L. Kulapadiharom, R. K. Lee, and E. L. Ekholm. 1977.
Technical and Cost Comparisons of Chemical Coal Cleaning
Processes. Mining Congress Journal. 63(8):42.
Slagle, P. and Y. T. Shah. 1978. Unpublished data.
Versar, Inc. 1978. Technical and Economic Evaluation of Chemical
Cleaning Processes for Reduction of Sulfur in Coal. Prepared
under EPA contract 68-02-2199.
Vracar, R. and D. Vucurovic. 1970. Oxidation of Pyrites by Gaseous
Oxygen from an Aqueous Suspension at Elevated Temperatures in
an Autoclave (I). Tehnika (Belgrade)-RTIM. 25(8):1490.
Vracar, R. and D. Vucurovic. 1971. Oxidation of Pyrites by Gaseous
Oxygen from an Aqueous Suspension at Elevated Temperatures in
an Autoclave (II). Tehnika (Belgrade)-RIM. 26(1):68.
Vracar, R. and D. Vucurovic. 1972. Oxidation of Pyrites by Gaseous
Oxygen from an Aqueous Suspension at Elevated Temperatures in
an Autoclave (III). Tehnika (Belgrade)-RIM. 27(7):1308.
Wheelock, T. D., R. T. Greer, R. Markuszewski, and R. W. Fisher.
1978. Advanced Development of Fine Coal Recovery Technology.
Annual Technical Progress Report to U. S. ERDA under contract
W-7405-eng-82.
1038
-------
COAL DESULFURIZATION BY LEACHING WITH ALKALINE
SOLUTIONS CONTAINING OXYGEN
R. Markuszewski, K. C. Chuang, and T. D. Wheelock
Ames Laboratory
Iowa State University
Ames, Iowa
ABSTRACT
Hot alkaline solutions containing dissolved oxygen under pressure were
used to leach sulfur from bituminous coals in a small, stirred autoclave.
The reduction of sulfur content in coal was studied as a function of the
stirring rate, leaching time, temperature, pressure, and concentration of
alkali. Under relatively mild conditions, almost all of the inorganic sulfur
and a significant portion of the organic sulfur were removed. Dilute
alkaline solutions were more effective than acidic solutions in the removal
of organic and inorganic sulfur, but the heating value recovery was somewhat
higher for acidic solutions. Also, oxygen was shown to be more effective
than air as the oxidizing medium. Under alkaline conditions, more organic
sulfur was removed when the oxygen partial pressure was increased. Optimum
values were determined for the concentration of alkali and for the temperature
of the leaching process, under given conditions.
1039
-------
INTRODUCTION
Chemical methods for the removal of sulfur from coal have
received wide attention (Friedman and Warzinski, 1977; Meyers,
1977; Wheelock, 1977; Wheelock, 1978). Among the more promising
are processes based on extraction of sulfur by leaching with
aqueous solutions containing dissolved oxygen ( Agarwal et al.,
1975; Friedman et al., 1977; Tai et al., 1977). The rate of
extraction can be increased by operating at elevated temperature
and pressure. Although generally the leaching solutions are
_r
acidic, either initially or as a result of the generation of
sulfuric acid during the oxidation of pyritic sulfur, basic
solutions containing ammonia have also been proposed (Agarwal
et al., 1976; Sareen, 1977). Apparently, the use of basic
solutions allows a significant extraction of the organic sulfur
as well as the pyritic sulfur from coal under milder conditions.
The leaching temperatures for basic solutions are relatively
low, generally less than 150CC. The advantages of using alkaline
conditions for leaching high-sulfur coals were also demonstrated
by Tai et al.(1977).
A unique chemical desulfurization (oxydesulfttrization)
process is being developed at the Ames Laboratory, Iowa State
1040
-------
University, which is based on leaching fine-size coal with a
hot, dilute sodium carbonate solution containing dissolved
oxygen under pressure (Wheelock et al. , 1978). In this process,
sulfur is extracted from coal by conversion into soluble
sulfates. For pyrite the overall conversion reaction appears
to be :
2 FeS2 + 7.5 02 + 4 H20 = Fe203 + 4 H2S04.
The pyritic iron remains as an insoluble iron oxide or hematite
(Chen, 1978) . The sulfuric acid generated in the process is
immediately neutralized by the alkali as follows:
The mechanism for the extraction of a portion of the organic
sulfur has not been established.
In this work, several high- sulfur bituminous coals were
leached under various conditions . The effects of important
parameters such as agitation, leaching ti ae , temperature,
oxygen partial pressure, and alkalinity on the process were
studied. The results will be used to optimize the oxydesulfuri-
zation process.
EXPERIMENTAL
Apparatus
The leaching experiments were conducted in a 1- liter
stirred autoclave reactor (Autoclave Engineers, Inc., Model
AFP 1005) made of Type 316 stainless .steel. The reactor was
furnished with a removable, protective liner made of stainless
steel, an electric heating jacket, a proportional temperature
controller, an internal cooling coil, and a pressure gauge.
1041
-------
The contents of the autoclave was stirred by a gas-dispersing
turbine agitator operated by a magnetic drive.
Procedure
For each experiment, the autoclave reactor was charged with
40 g. of coal plus 400 ml. of the leach solution and sealed.
The desired agitator speed was established,and the autoclave
was purged with nitrogen gas while being heated up to tempera-
ture. When the desired temperature was reached, the flow of
nitrogen was stopped, the autoclave was vented, and oxygen
was introduced into the autoclave. The oxygen partial pressure
(psia), the total pressure within the autoclave (psig), the
temperature, and the stirrring rate were kept constant for the
duration of the experiment. Some gas was bled continuously
from the reactor to prevent any build-up of gaseous reaction
products, while the system pressure was kept constant by sup-
plying oxygen on demand. At the end of a run, the flow of
oxygen was stopped, the system purged with nitrogen, and the
reactor cooled. The leached coal was then recovered by filtra-
tion, dried at 90°C for 1 day, weighed, and analyzed for the
various forms of sulfur, ash content, and heating value by
standard ASTM procedures.
Materials
Three of the coals used for leaching came from mines
located in southeastern Iowa (Lovilia mine , Big Ben mine , and
Scott coal from the Iowa State University demonstration mine).
Another was a Western Kentucky coal (No.9 seam) from the Fies
Mine in Hopkins Co., KY. The Iowa coals were high-volatile
bituminous coals, high in sulfur content, and very heterogeneous
1042
-------
in composition. The coals were dried at 90°C for 1 day, ground
and sieved to the desired mesh size, and analyzed prior to
leaching.
Calculations
The heating value recovery, in percent, was calculated by
the following equation:
Recovery (%) - (wt. coal recovered) x heating value x 100
(wt. coal started) x heating value
The specific sulfur content (lb.S/106 Btu), used in the
tabular data, was calculated as follows:
Specific sulfur content - percent sulfur x 106
100 x heating value (in Btu/lb.)
There is a slight difference in the two forms in which the
data are presented. In the tables, the percent of sulfur reduc-
tion is based on changes in the specific sulfur content
(lb.S/106 Btu); in the graphs, it is based on the change in the
weight percent of sulfur.
RESULTS AND DISCUSSION
Effect of stirring rate
In order to establish the effect of the stirring rate of
the turbine agitator on the amount of sulfur removed from coal
by leaching, Scott coal was leached for 1 hr. by 0.2M sodium
carbonate at 150 °C and 50 psia oxygen partial pressure. The
results are presented graphically in Figure 1. The amount of
1043
-------
pyritic and total sulfur extracted from coal increased steadily
as the rotation speed was increased from 200 to 1200 r.p.m.
Between 1200 and 1400 r.p.m., the amount of sulfur extracted
(both pyritic and total sulfur) increased sharply. For
agitator speeds above 1400 r.p.m., the amount of pyritic
and total sulfur removed began to level off and approached a
constant value between 1800 and 2100 r.p.m., being about 90 and
63% for pyritic and total sulfur, respectively. Within this
range, the amount of extracted sulfur was independent of the
agitator speed, indicating that the rate of extraction was no
longer limited by the mass transfer of oxygen through the
solution surrounding the individual particles.
A similar dependency on stirring rate was observed by
Kosikov et al.(1973) during their study of the oxidation of
pyrite by air in an autoclave. In their explanation, the
effect of stirring is due to the amount of oxygen dissolved in
the solution. With increased agitation, the amount of dis-
solved oxygen increases until it reaches a limiting value
determined by Henry's law.
The study of the effect of agitator speed on the amount
of sulfur extracted was repeated at a higher oxygen partial
pressure, i.e. 200 psia. The data shown in Figure 2 indicate
that above 800 r.p.m.the reduction in total sulfur content
increased more steeply and then leveled off sooner, at about
1200 r.p.m., and at a higher sulfur reduction value, approx-
imately 67%, than at the lower oxygen partial pressure of 50
psia. The reason for the steeper rise in sulfur removal may be
higher solubility of oxygen in the alkaline leach solution at
1044
-------
90
80
s"70
I 60
G! so
_i
3
W 40
O 30
o
o
LJ
CC
20
10
~ I ' I
0 TOTAL SULFUR
a PYRITIC SULFUR
50 psia 02
I
400 600 1200 1600
AGITATOR SPEED, r.p.m.
2000
Figure 1. Effect of agitator speed on the
removal of sulfur from coal for
50 psia oxygen partial pressure
70
5 60
8 50
tr
40
30
9 20
o
3 I0
tr
• 200 psia
o 50 psio
_L
_L
400 800 1200 1600
AGITATOR SPEED, rpm
_L
2000
Figure 2. The interaction of agitator speed
and oxygen partial pressure on
total sulfur removal.
1045
-------
higher pressure. Thus, with increased stirring rate the
mass transport is higher for the solution with the greater
oxygen concentration; as more oxygen is transported to the
particle surface, the reaction can proceed progressively faster.
At the plateau, some mechanism other than mass transport
through the external solution is rate-limiting, and further
increases in rotation speed do not increase the reaction rate.
To keep the leaching independent of the stirring rate, all
further experiments were conducted at 2000 r.p.m.
Effect of leach solution and oxidant
In the next set of experiments, the relative effective-
ness of alkaline versus acidic leaching conditions and of
pure oxygen versus air as the oxidant were compared. The four
run-of-mine coals, -200 mesh, were leached for 1 hr. at 1508C
and 50 psia oxygen partial pressure. Under alkaline conditions,
0.2M sodium carbonate was the leaching solution. For acidic
conditions, pure water was used; the sulfuric acid produced
during the oxidation of pyritic sulfur provided the acidity.
The oxygen partial pressure was the same (50 psia), regardless
of whether oxygen or air was supplied to the autoclave.
The results presented in Table 1 are averages for dupli-
cate runs. Although in each case the recovery in heating
value was high, it was slightly greater under acidic than under
alkaline conditions. However, it is apparent that the percent-
age sulfur reduction was higher for alkaline than for acidic
conditions. Since the relative merits of air versus oxygen
are more difficult to discern, the data were subjected to sta-
tistical analysis.
1046
-------
Table 1. Leaching of coals (-200 mesh) wifh water and with
alkali using air or pure oxygen.
Gas
Type
°2
Air
c
°2
Airc
°2
Air
°2C
Airc
°2
Air
°2C
Airc
°2
Air
°2°
Airc
H.
V.
Btu/lb.
10,
10,
10,
9,
9,
10,
H,
10,
10,
10,
10,
11,
11,
10,
10,
10,
10,
11,
10,
10,
050b
320
260
520
420
530b
003
860
260
140
270b
260
050
520
340
890b
930
180
240
730
Ash
wt.%
20.7
17.1
17.7
23.5
23.6
15.0
11.3
12.5
17.3
18.3
16.9
12.4
14.1
18.2
19.6
18.3
16.6
16.3
21.8
20.6
lb.S/106 Btu
Pyr.
3.08
0.92
1.66
0.56
1.11
3.50
1.18
2.58
0.72
0.81
6.24
1.42
4.15
1.93
2.78
0.89
0.10
0.13
0.08
0.09
Sulf.
1.07
0.51
0.64
0.22
0.22
1.52
0.38
0.34
0.34
0.32
1.86
0.34
0.20
0.22
0.30
0.86
0.37
0.33
0.09
0.10
Org.
0
1
0
0
0
1
1
1
0
1
2
3
2
1
1
1
1
1
1
1
.97
.15
.91
.71
.85
.67
.66
.41
.97
.02
.53
.21
.72
.94
.85
.43
.53
.63
.31
.37
Tot.
5.12
2.58
3.21
1.49
2.18
6.69
3.22
4.33
2.03
2.15
10.63
4.97
7.07
4.09
4.93
3.18
2.00
2.09
1.48
1.56
Tot. S tt.V.
ixeun . ixcco v .
7 7
la /o
(Lovilia
49.
37.
70.
57.
6
3
9
4
(Big Ben
51.
35.
69.
67.
9
3
7
9
Coal)
95.3
94.7
86.9
88.3
Coal)
97.1
92.8
88.2
86.3
(Scott Coal)
53.
33.
61.
53.
(West
37.
34.
53.
50.
2
5
5
6
. Ky.
1
3
5
9
93.9
95.6
93.2
91.7
Coal)
95.7
95.7
89.2
92.9
aLeached 1 hr. at 150°C and 50 psia 0, partial pressure.
Heating value, ash content, and sulfur distribution of unleached
coal.
Q
Leach solution was 0.2M sodium carbonate.
1047
-------
The general conclusion drawn from the statistical analysis
is that the nature of the leaching solution (alkaline or acidic)
has a greater effect on desulfurization than the nature of the
oxidant (air or oxygen). Specifically, desulfurization is more
effective, at the 99.570 confidence level, under alkaline than
under acidic conditions. Also, at a slightly lower confidence
level, namely 95%, oxygen can be said to be a better oxidant
than air.
Closer scrutiny of the data in Table 1 reveals also that
in almost every case both the pyritic and the organic sulfur
contents were significantly lower for alkaline than for acidic
leaching conditions. Use of air versus oxygen, however, produced
no discernible difference in the organic sulfur content. For
the pyritic sulfur content, use of oxygen tended to result in
lower values than use of air.
The relative effectiveness of alkaline, neutral, and acidic
conditions under various oxygen partial pressures will also be
discussed further below.
Effect of leaching time
The effect of leaching time on the desulfurization of Lo-
vilia coal is presented in Table 2 and in Figure 3. At 150°C
and 50 psia oxygen partial pressure, prolonged leaching with
0.2M sodium carbonate improved the extraction of sulfur at first.
But after about 1.5 hr., the reduction in total sulfur leveled
off at about 76-79%. The initial increase in extraction seemed
due to the removal of additional pyritic sulfur, since the
amount of organic sulfur removed appeared fairly constant
1048
-------
Table 2. Oxydesulfurization of coal as a function of
leaching time .
Time
hr.
0
0.5
1.0
1.5
2.0
2,5
3.0
H.V.
Btu/lb.
10,175b
9,686
9,601
9,674
9,706
9,414
9,651
Ash
18.6
22.5
23.2
22.6
22.4
24.7
22.8
lb.S/106
Pyr .
3.84
0.92
0.76
0.56
0.39
1.03
0.53
Sulf.
0.92
0.24
0.15
0.25
0.22
0.34
0.22
Btu
Org.
1.02
0.67
0.87
0.55
0.74
0.70
0.48
Tot. S
Redn
Tot. %
5.78
1.83 68.3
1.78 69.2
1.36 76.5
1.35 76.6
2.07 64.2
1.23 78.7
H.V.
Recov.
-
86.9
86.1
81.3
81.6
76.6
80.9
a
•Lovilia coal (-200/+250 mesh), leached with 0.2M Na2C03 at 150°C
and 50 psia 02-
bHeating value, ash content, and sulfur distribution of unleached
coal.
(from an initial 1.02 lb.S/106 Btu down to an average of 0.67
Ib. S/106 Btu). At the same time, the heating value recovery
decreased with increasing leaching time. Thus, the small
advantage in removal of some additional pyritic sulfur was offset
by a higher loss in heating value.
Effect of oxygen partial pressure
The beneficial effect of increased oxygen partial pressure
on the desulfurization of coal has already been observed in Fig-
ure 2. A set of experiments was then designed to study this ef-
fect over the range of 25-200 psia oxygen partial pressure by
leaching Lovilia and Western Kentucky coals with 0.2M sodium
carbonate at 150°C. From the results shown in Table 3 and in
1049
-------
Table 3.
Effect of oxygen partial pressure on alkaline
of Lovilia coal (-200/+250 mesh).
°2
Press. H.V.
psia Btu/lb.
-
25
50
75
100
125
150
175
200
10
9
9
9
9
9
9
9
9
,175b
,522
,600
,588
,619
,449
,716
,676
,618
Ash
18.6
23.9
23.2
23.3
23.1
24.4
22.3
22.6
23.1
lb.S/106 Btu
Pyr.
3.84
0.78
0.76
0.57
0.57
0.93
0.34
0.40
0.36
Sulf.
0.92
0.22
0.15
0.23
0.25
0.22
0.22
0.26
0.23
Org.
1.02
0.91
0.87
0.78
0.83
0.93
0.76
0.69
0.78
Tot.
5.
1.
1.
1.
1.
2.
1.
1.
1.
78
91
78
58
65
08
32
35
37
leaching
Tot. S
Redn.
67
69
72
71
64
77
76
76
-
.0
.2
.7
.5
.0
.2
.6
.3
H.V.
Recov.
-
86.6
86.1
86.2
86.3
86.2
86.9
87.0
84.1
aLeached 1 hr. with 0.2M Na-CO., at 150°C.
b ~
Heating value, ash content,and sulfur distribution of unleached
coal.
Figure 4, it is evident that the reduction in the total sulfur
of Lovilia coal increased from 67% up to 76-77% by increasing
the oxygen partial pressure. The slight improvement can be
attributed to additional removal of both pyritic and organic
sulfur. By contrast, the improved desulfurization of Western
Kentucky coal with increasing oxygen partial pressure was due
to the increased removal of organic sulfur and not pyritic sul-
fur (data shown in Table 4 and Figure 5). There is no ready
explanation for this difference in the behavior of the pyritic
sulfur of the two coals. Lovilia coal seems also unique in that
1050
-------
z
UJ
c
UJ
Q.
90
85
80
75
70
65
I I 1 1 1
Lovilia Coal -200/ + 250 mesh
50 psia Og press.
150° C.
0.2 M NagCOs
Heating
Value Recovery
J_
Total Sulfur Reduction
_L
0.5 1.0 1.5 2.0 2.5 3.0
REACTION TIME, hr.
Figure 3. Effect of leaching time on
oxydesulfurization of coal.
z
UJ
o
rr
90
80
70
60
I I I I I I I I
Lovilia Coal -200/+ 250 mesh
150° C , I hr.
0.2 M NaC0
Heating Value Recovery
Total Sulfur Reduction
25 75 125 175
PARTIAL PRESSURE OF OXYGEN
psia
Figure 4. Effect of oxygen partial pressure
on oxydesulfurization of coal.
1051
-------
Table 4. Leaching Western Kentucky Coal (-200 mesh; at
different oxygen pressures.
°2
Press
psia
50
100
150
200
« 17 AfTh lb.S/10* Btu
Btu/lb. wt.% Pyr. Sulf. Org.
10,
10,
10,
10,
10,
890b 18.3 0.89 0.86 1.43
237 21.8 0.08 0.09 1.32
370 21.9 0.16 0.08 1.22
375 21.9 0.17 0.09 1.15
383 21.8 0.13 0.14 1.12
Tot.
3.18
1.49
1.45
1.41
1.38
Tot. S
Redn.
%
--
53.
54.
55.
56.
3
6
9
5
H.V.
Recov
<
i
--
89
89
89
90
fo
.2
.4
.5
.2
Leached 1 hr. by 0.2M Na-CO., at 150°C. Data are averages of
duplicate runs.
Heating value, ash content, and sulfur distribution of unleached
coal.
the pyritic sulfur content was almost never reduced to a level
below about 0.4%,. In Western Kentucky coal, on the other hand,
the pyritic sulfur was decreased to as low as 0.13%. For both
coals, however, the heating value recovery was almost unaffected
by the increased oxygen partial pressure, remaining at about 86
and 90% for Lovilia and Western Kentucky coal, respectively.
The effect of oxygen partial pressure on the desulfuriza-
tion of coal was studied also under alkaline, neutral, and aci-
dic leaching conditions. The data in Table 5 and Figure 6 are
for Western Kentucky coal, leached for 1 hr. at 150°C by 0.2M
sodium carbonate, 0.2N sulfuric acid, or water at pressures from
50 to 200 psia oxygen.
1052
-------
Tjable 5. Effect of oxygen partial pressure on the leaching of
coal with alkaline,neutral or acidic solutionsa.
°2
Press
psia
H.V.
Btu/lb.
10,890b
0.2M N£
50
100
150
200
water0
50
100
150
200
0.2N H2
100
150
200
12CO
10,
10,
10,
10,
10,
10,
11,
11,
so4
3
322
368
344
230
885
090
138
148
11,212
11,204
11,185
Ash
18.3
21.7
21.9
22.1
22.9
16.8
16.4
16.1
16.0
15.5
15.6
15.7
lb.S/106
Pyr.
0.89
0.10
0.15
0.20
0.13
0.12
0.13
0.16
0.14
0.10
0.11
0.11
Sulf.
0.36
0.07
0.07
0.09
0.13
0.28
0.27
0.22
0.20
0.44
0.38
0.43
Btu
Org.
1.
1.
1.
1.
1.
1
1
1
1
1
1
1
43
32
21
13
,19
.49
.41
.29
.27
.41
.34
.31
Tot.
3.18
1.49
1.43
1.42
1.45
1.89
1.81
1.67
1.61
1.95
1.83
1.85
Tot. S
Redn.
-
53.
55.
55.
54.
40.
43.
47.
49.
--
1
0
3
4
6
1
5
4
36.7
42.4
41.8
H.V.
Recov.
90.0
87.8
86.9
90.2
97.2
95.0
96.7
96.2
98.5
95.9
96.8
Western Kentucky coal (-200 mesh), leached 1 hr. at 150°C.
bHeating value, ash content, and sulfur distribution of uncleachd
coal.
°Initial solution, becomes acidic as leaching proceeds.
1053
-------
o
Ul
oc.
UJ
ui
o
Q
Ul
tr
9O
80
o
UJ
-------
When water was used as the leachant, the initially neutral
solution became acidic during the leaching process because of
the production of sulfuric acid. Under these conditions, the
reduction of total sulfur increased almost linearly with increas-
ing oxygen pressure, from 40.67. at 50 psia to 49.47* at 200 psia
oxygen partial pressure. When the leachant was initially acidic
(0.2N sulfuric acid), the reduction of total sulfur was less
favorable, ranging from 36.77. at 100 psia, through 42.47. at 150
psia, to 41.8% at 200 psia oxygen partial pressure.
When 0.2M sodium carbonate was the leachant, the total sul-
fur reduction was much higher; however, it seemed to increase only
slightly with increasing oxygen partial pressure, from 53.1 to
55.37». The amount of organic sulfur in the leached residue was
less than that for the other leachants and appeared to decrease
with increasing pressure. The heating value recovery, on the
other hand, was lower under alkaline conditions (87-907e) than
under acidic conditions (96-99%).
It should be noted that none of the coal samples removed
from the autoclave were washed with water after the leaching
treatment. This obviously had an effect on the residual levels
of sulfate in the leached coal, amounting to about 0.2 lb.S/10
Btu. In the case of sulfuric acid as the leachant, this effect
was even more noticeable with residual sulfate levels of about
0.4 Ib. S/106 Btu. In addition to improving the total sulfur
reduction, a washing step would also decrease the ash content of
the leached coal. The benefits of washing leached coal by water
or by dilute acid were recognized by Tai et al. (1977).
1055
-------
Effect of alkali concentration
The data in Table 6 and Figure 7 show the effect of the
alkali concentration on the desulfurization of Lovilia coal at
150°C and 50 psia oxygen partial pressure for 1 hr. With no
sodium carbonate present in the leach solution, the reduction
of total sulfur was 58%. The presence of even a small amount
of alkali, i.e. 0.05M sodium carbonate, improved the total sul-
fur reduction significantly, to 66%. Further increases in
alkali concentration resulted in only slight improvement, while
at higher concentrations the reduction of total sulfur even
declined. The optimum concentration seemed to be 0.15-0.2M
sodium carbonate, resulting in approximately 71% reduction of
total sulfur. For this same concentration range, the residual
amounts of pyritic, sulfate, and organic sulfur appeared to be
minimum. Higher concentrations of alkali were also detrimental
to the heating value recovery, causing a decline from 92.7 to
78.9% in the recovery by increasing the sodium carbonate concen-
tration from 0.05 to 0.5M. Even worse heating value recoveries
were observed at higher alkali concentrations (Wheelock et al.,
1978).
Effect of temperature
The results of the effect of the leaching temperature on
the desulfurization of Lovilia coal are presented in Table 7 and
Figure 8. With increasing temperature, the total sulfur reduc-
tion increased at first, then passed through a broad maximum,
after which it decreased at an accelerating rate. The optimum
temperature range was approximately 120-150°C; up to 71.4%
1056
-------
Table 6. Effect of sodium carbonate concentration on leaching
of coal.
Cone.
Na2co3
_ _
oc
0.05
0.10d
1.15d
0.20d
0.25
0.30d
0.40d
0.50d
H.V.
Btu/lb.
10
10
10
10
10
9
9
9
9
9
,418b
,982
,833
,401
,156
,858
,680
,340
,246
,186
Ash
%
18.0
13.4
14.1
17.9
19.9
22.2
23.6
25.8
26.5
27.0
Ib.
Pyr .
3,24
1.08
0.68
0.73
0.62
0.82
1.14
0.82
0.74
0.70
S/106 Btu
Sulf .
0.90
0.29
0.36
0.24
0,20
0.21
0.22
0.28
0.21
0.46
Org.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
99
80
71
72
71
81
93
86
84
80
Tot.
5.13
2.17
1.75
1.69
1.53
1.84
2.29
1.96
1.99
1.96
Tot.S
Redn.
%
--
58
66
67
70
64
55
61
61
61
.0
.2
.4
.5
.4
.7
.7
.2
.9
H.V.
Recov .
%
—
91.7
92.7
89.2
88.2
86.7
86.2
84.4
80.2
78.9
aLovilia coal (-200/+250 mesh), leached 1 hr. at 150°C and 50
psia §2-
Heating value, ash content, and sulfur distribution of unleached
coal.
°Leach solution was initially water; became acidic as leaching
proceeded.
^Values are averages of duplicate runs.
1057
-------
Table 7. Effect of temperature on the leaching of coal with
alkali.
Temp.
°C
--
100
120
130
150°
170
180C
200
H.V.
Btu/lb.
10
9
9
9
9
9
9
8
,047b
,666
,634
,662
,268
,205
,016
,950
Ash
19.6
22 .6
22.9
22.7
25.9
26.3
27.8
28.4
lb.S/106 Btu
Pyr.
3.90
1.25
0.80
0.88
1.42
1.51
1.71
2.69
Sulf.
0.94
0.28
0.29
0.23
0.20
6.27
0.22
0.23
Org.
0.
0.
0.
0.
0.
0.
0.
0.
93
69
56
64
70
59
98
98
Tot.
5.77
2.22
1.65
1.75
2.32
2.37
2.91
3.90
Tot.S
Redn.
--
61
71
69
59
58
49
32
.5
.4
.7
.9
.9
.7
.4
H.V.
Recov.
--
89.7
88.2
89.2
83.6
80.2
75.9
78.2
10,390b 18.3 3.12 0..94 1.03 5.09 —
.110d __ 9,783 23.1 0.59 0.25 0.89 1.73 66.0 90.2
aLovilla coal (-200/+250 mesh), leached 1 hr. with 0.2M Na2C03
at 50 psia 02-
bHeating value, ash content, and sulfur distribution of unleached
coal.
cAverage of duplicate runs.
Control sample for this run was sample immediately above.
1058
-------
z
LU
O
£C
UJ
0.
1 -
Lovifio Coal -200/+ 250 mesh
50 psia ©2 pr«ss._
150° C
hr.
_Value Recovery
Total Sulfur Reduction
— Figure 7.
o.i 0.2 0.3 0.4 as
CONCENTRATION OF Na2COj,M.
Effect of sodium
carbonate concentration
on oxydesulfurizafcion
of coal.
I-
100
90
80
70
so
50
40
r i I r r r
Lovilia Coal -200/*250mesh
SOpsi Og pressur*-
1 hr.
0.2M No2C03 -
Heating
Value Recovery
Total o
Sulfur Reduction
I
J_
100 120 140 ISO 180 200
TEMPERATURE, °C
Figure 8. Oxydesulfurization of
coal as a function o£
temperature.
1059
-------
of the total sulfur was extracted in this region. At 200°C,
the total sulfur reduction had decreased to 32.4%. The relative
reductions in pyritic and organic sulfur seemed to parallel the
reduction curve for total sulfur. Only sulfate sulfur appeared
to have a constant residual value of about 0.2 Ib. S/10 Btu.
The heating value recovery declined steadily with increasing
temperature, from 90% down to 78%, probably because of partial
oxidation of coal.
At the present time, it is not certain what causes this
unusual temperature effect. It may be due to a decrease in the
solubility of oxygen in the sodium carbonate solution at higher
temperatures. Or perhaps it may be caused by a thermally in-
duced change in the structure of coal itself. Alternatively,
there may be a change in the reaction mechanism or kinetics,
possibly caused by the thermal decomposition of a reactive
intermediate.
CONCLUSIONS
It has been demonstrated with a small autoclave reactor
that leaching of high-sulfur bituminous coals with hot, dilute
solutions of sodium carbonate containing dissolved oxygen under
pressure can remove most of the inorganic sulfur and a portion
of the organic sulfur. Dilute alkaline leach solutions have
been shown to be more effective than neutral or acidic solutions.
More concentrated alkaline solutions are less beneficial and
even detrimental, causing lower reduction in sulfur and decreas-
ing the heating value recovery. The desulfurization reaction
becomes independent of the stirring rate at high stirring speeds.
1060
-------
Leaching longer than 1-1.5 hr. results only in a modest
increase in sulfur removal, but the advantage is offset by a de-
crease in heating value recovery. Increasing the oxygen partial
pressure improves the extraction of sulfur without a noticeable
decrease in the heating value recovery. The improvement is due
mainly to an increase in the removal of organic sulfur, amount-
ing to 30% in some cases. An optimum temperature range has been
observed at about 120-150°C for which the reduction of sulfur
is maximum. At higher temperatures, both the extraction of sul-
fur and the heating value recovery decline significantly.
The overall Ames oxydesulfurization process has been shown to
be effective in removing almost all of the inorganic sulfur and
a significant portion of the organic sulfur under relatively
mild conditions. The moderate temperatures and pressures do
not require extraordinary equipment, and the alkaline conditions
i'
provide a non-corrosive environment. With proper regeneration
of the leaching solution, the process should prove an econom-
ical method for the chemical cleaning of high-sulfur coal.
ACKNOWLEDGEMENT
This work was supported by the U. S. Department of Energy,
Division of Fossil Energy, and the Iowa Coal Project.
The statistical analysis, performed by Dr. Craig Van
Nostrand, is gratefully acknowledged.
1061
-------
REFERENCES
Agarwal, J. C., Giberti, R. A., Inninger, P. F., Petrovic, L. F.,
and S. S. Sareen. 1975. Chemical desulfurization of coal
Mining Congr. J. 61(3), 40-3.
Agarwal, J. C., Giberti, R. A., and L. J. Petrovic. 1976.
Method for removal of sulfur from coal. U. S. Patent
3,960,513.
Chen, M.-C. 1978. Desulfurization of coal-derived pyrite
using solutions containing dissolved oxygen. M. S. Thesis.
Iowa State University.
Friedman, S., LaCount, R. B., and R. P. Warzinski. 1977.
Oxidative desulfurization of coal. In T. D. Wheelock, ed.,
Coal desulfurization: chemical and physical methods. ACS
Symposium Series 64, Am. Chem. Soc., Washington, D. C.
Friedman, S., and R. P. Warzinski. 1977. Chemical cleaning
of coal. Trans. ASME 99(3), 361-4.
Kosikov, E. M., Kakovskii, I. A., and E. A. Vershinin. 1973.
Use of polarographic probes for measuring the concen-
tration of dissolved oxygen. Obogashchenie Rud 18(4),
39-41. •
Meyers, R. A. 1977. Coal desulfurization. Marcel Dekker,
Inc., New York.
Sareen, S. S. 1977. Sulfur removal from coals: ammonia/
oxygen system. In T. D. Wheelock, ed., Coal desulfuri-
zation: chemical and physical methods. ACS Symposium
Series 64, Am. Chem. Soc., Washington, D. C.
Tai, C. Y., Graves, G. V., and T. D. Wheelock. 1977. Desulfu-
rizing coal with solutions containing dissolved oxygen.
In T. D. Wheelock, ed., Coal desulfurization: chemical
and physical methods. ACS Symposium Series 64, Am. Chem.
Soc., Washington, D. C.
Wheelock, T. D., ed. 1977. Coal desulfurization: chemical
and physical methods. ACS Symposium Series 64, Am. Chem.
Soc., Washington, D. C.
Wheelock, T. D. ca. 1978. Chemical cleaning. In Leonard, J.W.
et al., eds., Coal preparation. 4th ed. Am. Inst. of
Mining, Metallurgical and Petroleum Engineers, Inc.
Wheelock, T. D., Greer, R. T., Markuszewski, R., and R. W.
Fisher. 1978. Advanced development of fine coal desulfu-
rization and recovery technology. Annual Technical Prog-
ress Report, Oct. 1, 1976 - Sept. 30, 1977, IS-4363,
Ames Laboratory DOE - Fossil Energy, Iowa State University,
Ames, IA.
1062
-------
CONVERSION TABLE TO INTERNATIONAL (SI) SYSTEM UNITS
1 Btu = 1,055 joules
1 Ib. = 453.6 g
1 Btu/lb. = 2.324 joules/g
1 psi - 6.89 kPa
1 r.p.m. = 0.105 rad/sec
1063
-------
THE POTENTIAL FOR CHEMICAL COAL CLEANING:
RESERVES, TECHNOLOGY, AND ECONOMICS
R. A. Glberti , R. S. Opalanko2, and J. R. Sinek1
Kennecott Copper Corporation
Lexington, Massachusetts
2
Resource Engineering, Inc.
Lexington, Massachusetts
ABSTRACT
Based on statistical data on U.S. bituminous coal reserves published by
the U.S. Bureau of Mines, an estimate is presented on the tonnage of coal,
by coal-producing region, which can potentially be made to conform to the
New Source Performance Standard (NSPS) of 1.2 Ib S0_ per million Btu by
chemically removing 90-95 percent of the pyritic sulfur and 0-40 percent of
the organic sulfur.
The additional tonnage of conforming coal potentially obtainable by
blending chemically cleaned coal with raw coal is estimated.
The impact of other criteria presently under discussion (0.2 Ib SO per
million Btu; removal of 80-90 percent of the original sulfur) is presenied
on the tonnage of coal potentially made conforming by chemical cleaning.
The state of the art of chemical cleaning is summarized. Kennecottfs
laboratory data on the removal of pyritic and organic sulfur are discussed,
and comparisons are made between: oxygen-water versus oxygen-ammonia leaching;
low-temperature (130°C) versus high-temperature (175-200°C) leaching.
Technical data resulting from these comparisons are used to project capital
and operating costs for grass-roots chemical coal cleaning plants. The ecbn-
omics of chemical coal cleaning are compared against the purchase of low-sulfur
washed coal or the installation of scrubbers.
1064
-------
Introduction
Chemical coal cleaning studies were begun in 1971 by
Kennecott Copper Corporation in an attempt to develop low
sulfur coals from its Peabody Coal Company divisionfs reserves.
Analyses reported in 1974 (Agarwal et al.,-1974) showed
significant economic, energy conservation, and environmental
advantages associated with chemical coal cleaning when compared
with other coal conversion/desulfurization alternatives. An
active coal desulfurization program was pursued by Kennecott
until May 1975, when all coal research and development for
Peabody Coal was terminated, because at that time the Supreme
Court upheld the Federal Trade Commission ruling ordering
Kennecott to divest itself of Peabody Coal. At termination,
the development program had progressed to a stage at which
batch testing was close to completion, and the main emphasis
was on planning an internally funded pilot plant program.
Results of the batch simulation of the leach reactors have
mostly been reported in the literature by Sareen et al. (1975),
and by Sareen (1977). In addition to leaching, every other
major unit operation on the flowsheet had been batch-tested:
separation and washing of clean coal from the leach reactor
effluent, solution neutralization and separatioa of the
gypsum thus formed, evaluation of materials of cpnstruction,
etc. A detailed process design had shown that only conventional
equipment would be required for a commercial plant, thus elim-
inating the need to develop new equipment for which there is
1065
-------
no reliable scale-up experience.
The process is covered by U.S. patent 3,960,513 (Agarwal,
Giberti, Petrovic, June 1976) assigned to Kennecott.
Since 1975 there have been, and will continue to be,
changes in the laws regulating the.sulfur content in coal, and
in the economics of coal desulfurization/conversion processes.
Kennecott has continued to update the economics of its chemical
coal cleaning process, and to identify the reserves where it
can be economically applied.
This paper will briefly summarize the experimental results
with particular emphasis on comparing some process alternatives*
in addition, it will present recent reserve estimates, and pro-
vide updated economics.
General Considerations of Chemical Coal Cleaning
The removal of sulfur from coals by chemical leaching de-
pends on the conversion of the various forms of sulfur to soluble
species. Chemical leaching has two significant advantages over
physical coal cleaning:
1. Fine, dispersed pyrite is removed from coals
without excessive grinding.
2. Organic sulfur may be removed as well as pyrite.
Because sulfur exists in coal in three general forms, the
separation of each form requires different chemistry:
1. Pyritic sulfur must be oxidized, either to sulfur
or, preferably, to soluble sulfate. A variety of
1066
-------
oxidants, including air, tonnage oxygen, chlorine,
etc., can achieve this.
2. Organic sulfur can be extracted by hydrogenation;
part o£ the organic sulfur can also be converted to
soluble sulfur species by oxidation.
3. Sulfates are generally soluble in aqueous solutions,
hence do not require chemistry other than leaching.
Experimental Results
It is virtually impossible to make a sound technical and
economic comparison of the various chemical leaching processes
from published data, because the processes have been tested
by different investigators with various coals and under varying
conditions. This paper compares three oxygen leaching alter-
natives tested by Kennecott:
Low-temperature (s!30°C) coal/water slurry
Low-temperature (si30 C) coal/aqueous ammonia slurry
High-temperature (>130°C) coal/water slurry
Data have been previously reported for the low-temperature
02/H20 system (Sareen et al., 1975) and for the low-temperature
02/NH3 system (Sareen, 1977). Data on the high-temperature
C^/H-jO have not been reported heretofore.
Figure 1 shows the removal of pyritic sulfur from coal.
At the identical temperature (130°C), the rate of pyrite leach-
ing for the 02/NH3 alternative is slightly lower than that for
07/H~0. It should be noted that no tests were run for short
& L
reaction times to establish the kinetics for the high tempera-
1067
-------
O
UJ
UJ
O
E
t
J I
20
O 02/H20, < 130°C, 300 psi O2
A 02/H20, 175°C. 200 psi O2~
02/NH3, 130°C. 300 psi O2
_J L_ t I >
40 60 80 100 120 140
REACTION TIME. MINUTES
160 180 200
Figure 1. Pyrlte Removal for Various Oxydesulfurization Conditions
1068
-------
ture (175°C) 02/H20 case. It should also be noted that the
high temperature Oj/f^O tests were run at 200 psi 02 partial
pressure rather than 300 psi, and that the rate of pyrite leach-
ing has been reported (Sareen et al., 1975) to vary directly
with the square root of the 02 partial pressure.
The data for the 02/NHj system are reported as a band for
the five ammonia molarities tested (0.5, 1.04, 1.94, 2.95, S.O)
to simplify the comparison. All data were obtained with. Illinois
#6 coal.
Figure 2 shows the previously reported data for organic
sulfur removal for the low temperature 02/H20 and 02/NH3 systems.
Also shown are previously unreported data demonstrating the
removal of organic sulfur at higher temperatures (175°C) in
the 02/H20 system. Organic sulfur removal at the higher tem-
perature is comparable to that in the 02/NH3 system. However,
as shown in Figure 3, this is achieved at the expense of greater
Btu losses. Figure 3 also shows the 02/NHj system to have
greater Btu losses than the 02/H20 system at the same tempera-
ture C130°C).
Data on the other process parameters, such as oxygen up-
take by coal, extent of coal converted to C02, CO, and hydro-
carbons, can mostly be found in the cited papers.
These data for Illinois #6 coal demonstrate the effect
of leaching chemistry on the removal of pyrite and organic
sulfur and the yield of heating value. Previously reported
data indicate that comparable pyrite leaching behavior can be
expected for other coal types. However, considerably different
1069
-------
40
Q
tu
|
UJ
cc
CO
o
<
u
cc
o
30
20
o
O O2/H2O, 130°C, 300 psi 02
A O2/H2O, 175°C, 200 psi O2
02/NH3, 130°C, 300 psi 02
20 40
60 80 " 100 120 140
REACTION TIME, MINUTES
180 200
Figure 2. Organic Sulfur Removal for Various OxydMuIfurfzstion Conditions
1070
-------
2
CO
a*
20
18
16
14
12
10
8
6
4
2
0
J L
...
^0.5 - 5.0M NH3\
"
0 20 40 60 80 100 120 140 160 180
REACTION TIME, MINUTES
O O2/H2O, 130°C, 300 psi O2
A O2/H20, 175°C. 200 psi O2
^ 02/NH3. 130°C, 300 psi O2
J I I I L » I I
200 220 240 260
Figure 3. Btu Losses for Various Oxydesulfurization Conditions
1071
-------
organic sulfur removal and Btu yield should be anticipated
with different coal types. Accordingly, the selection of the
optimum leaching chemistry will depend on the amount of sulfur
which must be removed from the coal, and on the organic sulfur
removal and Btu losses for the specific coal.
We now need to project the performance that this process,
when fully developed, is likely to achieve in a commercial
plant. Performance will vary according to coal type and to
the processing conditions chosen. However, there are enough
data to pinpoint the most likely range of desulfurization,
bracketed by three cases:
Case % pyritic S removal % organic S removal
90/0 90 0
90/20 90 20
95/40 95 40
Table 1 describes our best estimate of Btu yield and weight
yield for these three leaching alternatives, as well as for the
coarse wash which always precedes leaching.
Process Description
Based on the data just described, a commercial process
flowsheet can be developed as follows.
Run of mine coal is first given a coarse coal wash.
Since chemical coal cleaning will generally produce a
leached coal with a lower sulfur content than the standards
that must be met, some of the washed coal will by-pass the
1072
-------
Slurry liquid
Temperature, C
Sulfur removal, %
pyritic
organic
Leach Btu yield,*
Leach weight yield,?
Wash Btu yield,!
Wash weight yield,*
water
130
90
0
92
98
90
85
aq. NH3
130
90
20
89
98
90
85
water
175-200
95
40
86
98
90
85
Table 1. Assumptions for
various leaching conditions.
1073
-------
chemical cleaning plant as shown in Figure 4.
A simplified flowsheet of the chemical cleaning module of
Figure 4 is shown in Figure 5. The process description has beeii
reported earlier (Irrainger and Petrovic, 1974; Agarwal et al.,
1974; Sareen et al., 1975) but, for clarity, will be repeated here
briefly, assuming the low-temperature 02/H20 process is used.
The portion of the coal to be chemically cleaned is
crushed to -1/8" in an impact mill and then ball milled to
-100 mesh in a water slurry.
The slurry is diluted to 20% solids and preheated to 130°C
in Karbate heat exchangers and pumped into the reactors. For
an 8,000 TPD plant, the reactors are acid brick lined pressure
vessels, 33 in number, 9 ft diameter by 84 ft long, divided
into 11 compartments furnished with agitators, and provide the
coal with a residence time of 2 hrs. Vessels of this type
and dimension are presently in use at hydrometallurgical plants
in several countries.
An oxygen plant supplies oxygen at 300 psi pressure. The
discharge slurry is cooled by passing it back through the heat
exchangers. The clean coal is separated from the liquid phase
in a thickener and a rotary filter, where it is washed clean.
It is then balled on pelletizing disks and dried.
The overflow from the cleaned coal thickener is neutralized
with lime or limestone. The resulting gypsum sludge is thickened,
filtered, and discarded. The neutralized liquor is recycled
for use as process water in the desulfurization reactors.
1074
-------
o
«4
Ol
COARSE
WASH
CHEMICAL
CLEANING
CLEAN
COAL
Figure 4. Overall Coal Cleaning Process
-------
OXYGEN PLANT
WASHED
COAL
1 SHIFT/DAY HAMMER
7 HOURS/SHIFT
1700 HOURS/YR
240 DAYS/YR
GYP$UM TO
TA1UNOS POND
STORAGE RECYCLE
lUME
THICKENERffNEUTBALIZATION
NITROGEN
REACTORS
MAKE-UP WATER
AGGLOMERATION , ,.»
COAL TO
POWER PLANT
SLURRY
PUMP
Figure 5. Rowiheet for Oj/HjO Leaching of Pyritte Sulfur
-------
Process Capital and Operating Costs
The capital and operating costs shown in Tables 2 and 3
are based on a commercial process as described. For some
coals it may be desirable to perform the leaching at higher
temperatures or in aqueous ammonia to enhance organic sulfur
removal, as discussed; the costs for these process alterna-
tives have not been calculated in detail, but are believed
to be of the same order.
The capital cost for processing 8,000 TPD of coal totals
$123 million in mid-1977 dollars, equivalent to $46.3/annual
ton of coal feed. This estimate is based on a green-field
plant, and includes all the required off-sites as well as con-
tingency.
i
The operating cost, in Table 3, amounts to $23.5/ton
clean coal, based on utility financing. Using this method of
financing, an average annual capital charge of 15.91 results
from depreciation, interest on debt, return on equity, taxes,
and insurance.
This is the maximum cost of chemical coal cleaning, i.e.
the cost when no portion of the coal can by-pass the chemical
leaching section. Figure 6 shows the cost of clean coal as a
function of the percent of the coarse-washed coal that can
by-pass the chemical cleaning section so that the blend will
still meet the desired standard. These costs range from
$S.65/ton of product from coarse cleaning alone to $23.S/ton
of product for chemical cleaning alone.
1077
-------
Million $
Coal Handling and Washing 6.0
Crushing 8.4
Reactors 19.7
Oxygen Plant (1,000 TPD) 22.4
Liquid/Solid Separation 11.1
Neutralization 8.1
Agglomeration 14.3
Depreciable Investment 90.0
Land
Working Capital
Startup Costs
Interest during Construction
Total Investment 123.4
$/Annual Ton Leached - 46.3
Assumptions:
Mid 1977 dollars
Offsites and contingency factored into each process area
8,000 TPD coal feed to leaching
Table 2. Capital cost estimate for
Kennecott Oxygen Leaching process.
1078
-------
Million S/yr1
7
Process Losses 9.7
Chemicals
Lime 3.3
Flocculant 0.5
Binder 5.3
Utilities
Steam 3.9
Electricity 7.9
Labor, Supervision
Direct Costs
Average Capital Charge (15.9% total capital)
Maintenance, Labor $ Supplies
Plant Overhead (20% of labor § utilities)
Administrative Overhead (10% of labor)
Total Operating Cost 61.4
mill/KWH5 = 9.54
$/ton coal product = 23.5
1. Mid 1977 dollars; regulated utility financing
2. 17.2% overall Btu loss, including 10% Btu loss in
conventional coal cleaning. Cost figured at $18/ton ROM coal,
3. Includes depreciation, interest on debt, return on equity,
insurance, and taxes
4. 9% of depreciable capital, excluding contingency
5. 8,000 TPD plant produces 2.61 MM TPY product
containing 12,000 BTU/lb
Table 3. Operating cost estimate
for Kennecott Oxygen Leaching process
1079
-------
25
20
a
LU
o
a
o
cc
a.
O
u
1
15
10
I
I
I
I
I
f
Coarse
Wash
10 20 30 40 50 60 70 80
% OF PRODUCED COAL CHEMICALLY CLEANED
Figure 6. Cost of Coal Cleaning
J
90 100
Chemical
Cleaning
inso
-------
Definition of Compliance Coal
For the purpose of this study it is necessary to define
the standard to which the coal must be desulfurized in order
to be considered a suitable product of chemical cleaning.
There is considerable controversy at this time with
regard to New Source Performance Standards for fossil-fired
power plants. The selection of standards for this analysis
is difficult and subject to possible criticism. Nevertheless,
two levels of emissions were chosen and the technique can be
applied for any standards that are ultimately promulgated.
The selected levels are 1.2#S02/MMBtu, the present New Source
Performance Standard and a level required of some existing
plants, and 2.7#S02/MMBtu, a more liberal standard for exist-
ing plants.
Estimate of Production and Reserves of Coal Available to
Chemical Coal Cleaning
Based on coal seam data on pyritic sulfur content, organic
sulfur content, and calorific value, reported by Cavallaro,
Johnston, and Deurbrouck (1976) and by Wizzard (1978), pro-
jections have been made of the production and reserves which
can meet our postulated standards of 1.2, respectively 2.7,
Ib S02 per million Btu by chemical coal cleaning, but not by
coal washing alone. All three process variants, 90/0, 90/20,
and 95/40, were used in these projections.
Table 4 shows the results in terms of the annual tonnage
of low-sulfur coal thus produced. It shows that a 10-281
1081
-------
o
oo
ro
Region
1975 Production Ii
(MM net ton)
icremental Clean Coal Production, MM
Raw Washed
a) Clean coal specification: 1.2 Ib {
Northern Appalachian
Southern Appalachian
Alabama
Eastern Midwest
Western Midwest
Western
"Other"
TOTAL
t of U.S. Production
1B2
192
23
142
10
85
15
650
100
7 12
67 25
7 0
1 1
0 5
60 11
_-
140 54
22 8
b) Clean coal specification: 2.7 Ib J
Northern Appalachian
Southern Appalachian
Alabama
Eastern Midwest
Western Midwest
Western
"Other"
TOTAL
t of U.S. Production
182
192
23
142
10
85
15
650
100
46 36
173 16
17 1
4 8
1 1
30 -4
* * mm
321 66
49 10
net t/yr
Chemically Desulfurized
90/0
90/20
>02/MM Btu
26 37
29
7
4
1
0
--
67
So
54
10
7
1
0
--
109
17
502/MM Btu
59 68
0
4
43
2
•0
• »
108
17
0
4
62
3
•0
* *'
137
21
95/40
70
77
12
19
2
0
180
28
74
0
4
91
5
0
--
174
27
Cleaning
Cost
($/t)
17-20
10
20
19-22
16-20
...
16-17
...
11-12
17-18
18-20
...
...
Table 4. Incremental clean coal production:
Raw, washed and chemically desulfurized.
-------
increase, in U.S. coal production meeting a 1.2#SO~/MMBtu
A
standard can potentially be achieved by chemically cleaning
coal. The bulk of this production is from Appalachian coals.
For the 2.7#S02/MMBtu standard a 17-27% increase is projected
with most of the increase coming from Northern Appalachia
and Eastern Midwest.
Note that the cleaning costs in Table 4 are competitive
with recently announced purchase prices for low-sulfur coal.
Table 5 shows the results in terms of potential reserves
of low-sulfur coals created by the advent of chemical cleaning.
(To make this projection it was necessary to assume that the
coal seam data not only characterize U.S. production, but also
U.S. reserves.)
To illustrate with an example how these data were derived,
Figure 7 shows the case for coal from the Southern Appalachian
region complying with a standard of 1.2#S02/MMBtu. The dis-
tribution curves for raw coal and washed coal are taken from
the cited literature. Because these data indicate that up
to 50% of all coal from this region complies with the standard
if washed, only that portion of each curve is shown which
refers to the non-complying coal. The distribution curves for
leached coal are calculated from the raw coal data according
to the procedure described below, and are shown for the three
process alternatives: 90/0, 90/20, and 95/40.
It can be shown from Figure 7 that if, say, the 90/0
alternative is used, this will make available an additional 181
1083
-------
o
CD
Region
Reserves In
(billion t) R
cremental Clean
aw Washed
a) Clean coal specification:
Northern Appalachian
Southern Appalachian
Alabama
Eastern Midwest
Western Midwest
If es tern
TOTAL
t of U.S. Reserves
Northern Appalachian
Southern Appalachian
Alabama
Eastern Midwest
Western Midwest
Western
TOTAL
t of U.S. Reserves
68
SS
2
89
16
22
230
100
b) Clean coal
68
35
2
89
16
22
230
100
3 5
12 5
1 0
1 1
0 8
15 5
32 24
14 10
specification:
17 13
32 3
1 0
3 5
1 1
21 1
75 23
33 10
Coal Reserves, Billions Tons
Chemically Desulfurized
90/0 1 90/20
1.2 Ib S02/MM Btu •
10 14
5 10
1 1
2 4
2 2
0 0
20 31
9 13
2.7 Ib S02/(M Btu
22 25
0 0
0 0
27 39
3 5
0 0
52 69
23 30
95/40
26
14
1
12
3
0
56
24
28
0
0
57
8
0
93
40
* Assumes sulfur distribution in reserves is the sa»e as in 1975 production
Table S. Incremental clean coal reserves:
Raw, washed, and chemically desulfurized.*
-------
SOUTHERN APPALACHIAN REGION
o
00
GO
O
c/j
oo
3.5
3.0
2.5
2.0
1.5
1.2
1.0
0,5
I I \ I I I I I i I I I I
1
J
0.01 0.1 0.5 2 5 10 20 30 40 50 60 70 80 90 95 99
99.9 99.99
Figure 7. Coals in Southern Appalachian Region Capable of Meeting 1.2# SO/MM Btu
Standard after Various Treatments
-------
of all Southern Appalachian coal.
It also shows that the compliance blend of washed coal
and 90/0 leached coal averages 75% washed coal and 25% leach-
ed coal for the entire region. This value can be verified
by integrating both curves.
Sample Calculation
The results in Table 4 were generated from raw coal sulfur
analyses CCavallaro et al., 1976 and Wizzard, 1978) presented
as means and standard deviations (a) for each coal-producing
region. Using the Southern Appalachian region as an example,
the raw coal data are:
Pyritic Sulfur Organic Sulfur Total Sulfur
Mean a Mean o Mean a
0.46 0.72 0.62 0.22 1.08 0.88
The small amount of sulfate sulfur in the coal was added to the
pyritic sulfur so that
Pyritic S + Organic S • Total S
For any three variables x, y, and z related by
x + y = z
it can be shown that:
1) x + y = z
2 ? 9 2z(x.y.)
2) cz2 = ox2 + ay2 * N1/:L - 2Cx)Cy)
where xi = individual values of x
• x » mean of x.
a « standard deviation of x.
* . i
N * number of samples
1086
-------
Furthermore, if a variable w is defined by
w. = kx.
where
k is a constant,
then
w = kx
°w = kax
Using the above relations, and assuming given percentages
of pyritic and organic sulfur removal, one can find the jaean
and the standard deviation of total sulfur in desulfurized
coal. For pyritic/organic removals of 90/0, 90/20, and 95/40,
the Southern Appalachian region can be calculated to yield:
90/0 90/20 95/40
'Mean o Mean a Mean a
Total Sulfur Q>666 0.273 0.542 0.230 0.395 0.158
in Cleaned Coal
The calorific value of the chemically cleaned coal is
estimated using the weight yields and Btu yields shown in Table 1,
Again, for Southern Appalachian coal, these produce calorific
values of:
Raw Coal 90/0 90/20 95/40
Btu/lb 13,314 13,234 12,803 12,371
Therefore, the SO, emissions from Southern Appalachian coal
will be:
90/0 90/20 95/40
Mean a Mean a Mean a
Ib S02/MMBtu 1.006 0.412 0.846 0.359 0.638 0.255
1087
-------
These three distributions are plotted in Figure 7 and
indicate the following incremental amount of raw coal available
to chemical leaching, over and above the 50% that would comply
by washing only:
90/0 90/20 95/40
% of Non-Washable Coals
Meeting Standard 18 34 49
The average blend of washed and leached coal, obtained
by integration of the distribution curves over the region, is:
90/0 90/20 95/40
Clean Coal Blend
(washed: leached) 75:25 73:27 ™:24
These blend projections are conservative. Lower overall
costs could be achieved by using more washed-only coal for
blending, but this would lower the tonnage of coal available
from the region.
For 1975, total production from the Southern Appalachian
region was 192 million tons (Keystone, 1977). Assuming this
tonnage to be typical, and assuming a 90/0 sulfur removal, raw
coal suitable as feed to chemical coal cleaning plants is
(192) (0.18) • 35 million tons per year in this region. The
clean coal thus produced will be somewhat less, due to losses
in washing and leaching, and is calculated as follows:
(192) (0.18) [(0.75)(0.85)+(0.25)(0.83)(0.92)| - 29 million TPY
Explanation:
0.75 = fraction of blend which is coarse-washed only
0.85 = weight yield after coarse wash (Table 1)
0.25 = fraction of blend which is washed and leached
1088
-------
0.83 = weight yield after washing (851 yield) and
leaching (98% yield)
0.92 = adjustment for 81 parasitic consumption of
clean coal for power and steam consumed in
leach plant.
The cleaning cost of $10/ton, shown in Table 4, was
derived from Figure 6 for a 75:25 blend.
Chemical Coal Cleaning vs. Stack Gas Scrubbing:
Performance Comparison
As shown in the preceding projections, large tonnages
of high-sulfur coal can be made to conform to stringent sulfur
emission standards by chemical cleaning. These results can
generally also be achieved by stack gas scrubbing, and the
final decision must therefore be based on economics, which will
be discussed in the next section.
On the other hand, scrubbing is reported as able to remove
in excess of 85% of the sulfur dioxide in the flue gas. Chemical
coal cleaning, on the other hand, removes varying fractions of
sulfur, depending on the coal and on the leaching variant, but
seldom removes much more than 70% of the sulfur. This would
pose a problem in new plants requiring 85% sulfur removal.
Chemical Coal Cleaning vs. Stack Gas.Scrubbing: Economic
Comparison
Sulfur dioxide scrubbers must be sized for the full power
1089
-------
plant generating capacity. Because the fixed charges must be
distributed over the actual kWh generated, the cost of scrubbing
in mills per kWh is high for plants with low load factors.
Coal cleaning, on the other hand, is decoupled from boiler
operation, and the cost of coal cleaning in mills per kWh is
independent of load factor.
Figure 8 shows a cost comparison between chemical coal
cleaning and stack gas scrubbing. The coal cleaning costs
are the figures derived in the preceding calculations. The
scrubbing costs are escalated from a Tennessee Valley Authority
report (McGlamery et al., 1975), and are based on wet lime
and \*et limestone scrubbing because they account for 70% of
currently installed or planned scrubbing capacity. Both
scrubbing costs and coal cleaning costs are expressed in mid-
1977 dollars and assume regulated utility financing, i.e.,
15.9% of capital cost charged to annual operating cost. Neither
cost includes particulates collection.
Chemical coal cleaning costs, as well as scrubbing costs,
contain site-specific cost components which cannot be reflected
with precision in a generalized comparison such as Figure 8.
Coal cleaning costs depend significantly on local environmental
standards and on the quality of the coal. Scrubbing costs vary
greatly with site-specific factors, as reflected in the high
variance of actual plant cost experience. Nevertheless, Figure 8
shows that within the most common load factor range, coal clean-
ing costs should clearly be comparable to scrubbing costs.
1090
-------
S »:
g
§ ?:
"
1. W.t Unman* SO, Sowbbinfl
1000 MW
Euy Ritrofil
No Pmculin RMmmi
2. Wn Urn* SO. Soubt-ng
200 MW
Mo&na flttrofit Difficulty
No Pirriculn* Rwravil
//x/ / //v / / / / / /T7"\£:
J J .4 J .1 .7
renM PIANT tCAO fACTOH
a
a
1 "
ii
11
14
II
10
I
I
1. Wn Urnmon* SO, Scnjbbin,
1000 MW
E«y Ritreflt
No Pimculra Rimenl
2. Wit Urn* SO, Smibbing
200 MW
Mo
-------
(Approximately 74% o£ all 1976 U.S. coal-fired utility capacity
fell within the 35-65% load factor range; approximately 56% of
U.S. capacity fell within the 40-60% load factor range.) Figure
9 shows that the capital costs of chemical coal cleaning is
comparable to that of scrubbers.
Conclusions
1. Chemical coal cleaning has the potential of constituting,
in many cases, an economically viable alternative to stack
gas scrubbing and to the purchase of low-sulfur coal.
2. Assuming a clean coal specification in the range of 1.2-2.7
Ib S02 per million Btu, chemical coal cleaning has the
potential of increasing the production of compliance coal
by 180 million tons per year. Reserves of compliance coal
would be increased by 60-90 billion tons.
3. Chemical coal cleaning has potential application chiefly
in Eastern coal states and in the .Eastern Midwest..
4. Effective coal cleaning requires not only the removal of
pyrite but also the removal of at least 20% of the organic
sulfur in the coal.
5. Chemical coal desulfurization has a high probability of
technical feasibility because it can be implemented entirely
in state-of-the-art industrial equipment, and is similar
in many respects to existing hydrometallurgical process
plants.
1092
-------
to
cc
2
2
I
I
•3
80 i-
75
70
65
60
55
50
45
40
35
30
15
i
O 20
15
10
5
1. Wet Limestone SO, Scrubbing
1000 MW
Easy Retrofit
No Particulate Removal
2. Wet Lime SO, Scrubbing - $109.8/kW
200 MW
Moderate Retrofit Difficulty
No Particulate Removal
I I
J L
.4 .5 .6
LOAD FACTOR
.7
Blend of Coals
Washed : Leached
25%: 75%
75%: 25%
1.0
Figure 9. Capital Cost of SO2 Scrubbing and Chemical Coal Cleaning
1093
-------
Referenes
Agarwal, J.C., R.A. Giberti, and L.J. Petrovic. June 1, 1976.
Method for sulfur from coal, U.S. Patent 3, 960, 513.
Agarwal, J.C., R.A. Giberti, P.P. Irminger, L.J. Petrovic,
and S.S. Sareen. April 1974. Coal desulfuriztion:
costs/processes and recommendations, paper presented
at the 167th ACS National Meeting, Division of Fuel
Chemistry, Los Angeles, California.
Cavallaro, J.A., M.T. Johnston, and A.W. Deurbrouck. 1976.
Sulfur reduction potential of the coals of the United
States; a revision of report of investigations 7633,
RI 8118, U.S. Bureau of Mines.
Hamilton, P.A., D.H. White, and T.K. Matson. 1975. The
reserve case of U.S. coals by sulfur content: 2. The
western states. 1C 8693, U.S. Bureau of Mines.
Irminger, P.P., and L.J. Petrovic. June 1974. Design con-
siderations and status of some coal conversion pilot
plants, paper presented at the 77th AIChE National
Meeting.
McGlamery, G.G., R.L. Torstrick, W.J. Broadfoot, J.P. Simpson,
L.J. Henson, S.V. Tomlinson, and J.F. Young. January 1975.
Detailed cost estimates for advanced effluent desulfuriza-
tion processes, report for Office of Research and Develop-
ment, U.S. EPA, EPA-600/2-75-006.
Sareen, S..S. March 1977. Sulfur removal from coals: Ammonia/
oxygen system, paper presented at the 173rd National ACS
Meeting, New Orleans, Louisiana.
Sareen, S.S., R.A. Giberti, P.P. Irminger, and L.J. Petrovic.
September 1975. The use of oxygen/water .for removal of
sulfur from coals, paper presented at the 80th AIChE
National Meeting, Boston, Massachusetts.
Thompson, R.D., and H.F. York. 1975. The reserve base of
U.S. coals by sulfur content: 1. The eastern states.
1C 8680, U.S. Bureau of Mines.
Wizzard, J. August 1978. Personal communication. Pittsburgh
Energy Technology Center, Department of Energy.
1977 Keystone coal industry manual. 1977. McGraw-Hill Inc.
1094
-------
to convert from
Btu
kWh
pounds
tons (short)
tons (metric)
minutes
hours
days
to (SI units)
joule
joule
kilogram
kilogram
kilogram
seconds
seconds
seconds
multiply by
1,055.87
3.60 x 106
0.4536
907.18
1,000.00
60.00
3,600.00
86,400.00
Table 6: Conversion factors*
1095
-------
JPL COAL DESULFURIZATION PROCESS BY
LOW TEMPERATURE CHLORINOLYSIS
John J. Kalvinskas and George C. Hsu
California Institute of Technology
Pasadena, California
ABSTRACT
The Jet Propulsion Laboratory of the California Institute of Technology
has conducted an extensive laboratory scale investigation under a U.S. Bureau
of Mines contract of 12 coals including bituminous, sub-bituminous and lignite
coals for desulfurization by a three-stage process that includes chlorination,
hydrolysis and dechlorination. Results are represented for organic, pyritic,
and total sulfur removal. A parametric study of operating conditions was
conducted. A unique feature of the process is that high organic sulfur removal
is demonstrated in conjunction with high-pyritic sulfur removal for total
sulfur removal under favorable operating conditions of greater than 70 percent.
Preliminary costing of the desulfurization process indicates competitive costs
relative to other coal desulfurization processes and flue gas desulfurization.
Further development work on the process is continuing under U.S. Department of
Energy auspices. The future development activity includes a bench-scale
continuous flow mini-pilot plant operation at 2 kilograms coal feed per hour
and a bench-scale batch operation at 2 kilograms of coal per batch. A
preliminary equipment design is presented for the continuous flow mini-plant
coal desulfurization operation.
1096
-------
INTRODUCTION
The Jet Propulsion Laboratory (JPL) of the California Institute
of Technology has investigated the use of chlorination for the oxidation
of both pyritic and organic sulfur contained in bituminous coals for
accomplishing coal desulfurization to meet Environmental Protection
Agency stack emission standards of 1.2 pounds SO per million thermal
B.t.u.'s. For coals with a heating value of 12,000 B.t.u. per pound
acceptance standards translate to 0.7 weight percent sulfur in the coal.
The early research activity was carried out by JPL under internal
funding to devise the basic elements of the process. Preliminary findings
indicated that coal desulfurization on Illinois No. 6 bituminous coal
having a total sulfur content of 4.77% sulfur with approximately equal
distribution of organic and pyritic sulfur demonstrated approximately 70%
organic sulfur reduction, up to 90% pyritic sulfur reduction and 76% total
sulfur reduction (Hsu, et al., 1977). The laboratory scale research
reported here and under sponsorship of the U.S. Bureau of Mines represents
additional data obtained on 12 high sulfur coals including 9 bituminous,
2 sub-bituminous, and 1 lignite coals, Table 1. The coals have been
treated under the conditions of chlorination, hydrolysis and dechlorina-
tion constituting the JPL coal desulfurization process. The research
work is continuing under the U.S. Department of Energy sponsorship. The
follow-on activity will include bench-scale, batch tests at 2 kg of coal
per batch and construction and operation of an integrated continuous flow,
mini-pilot plant to demonstrate the process at a coal feed rate of 2 kg/hr.
1097
-------
Ash
o
VO
oc
Number
108
219
190
276
026
342
240A1
097
086
213
PHS-398
(BOM)*
PHS-513
(BOM)*
Seam, County & State
Pittsburgh, Washington, Pennsylvania
Kentucky #4, Hopkins, Kentucky
Illinois, #6, Knox, Illinois
Ohio #8, Harrison, Ohio
Illinois #6, Saline, Illinois
Clarion, Jefferson, Pennsylvania
Big 0, Lewis, Washington
Seam 80, Carbon, Wyoming
Zap, Mercer, N. Dakota
Kentucky #9
Raw Head, 3A, Upper Freeport Seam,
Somerset, Pennsylvania
Mine 513, Upper Clarion, Butler,
Pennsylvania
Rank (Wt.%)
HVA (Bit.) 9.50
HVA (Bit.) 8.06
HVA (Bit.) 8.49
HVA (Bit.)11.19
HVC (Bit.) 10. 84
HVA (Bit.) 9.19
Sub-bit B 29.40
Sub-bit A 9.80
Lignite 11.49
HVB (Bit.) 9.36
19.7
Organic
1.07
1.08
1.90
2.24
2.08
1.39
1.75
0.84
0.63
1.86
0.46
Pyritic
2.06
1.40
1.05
2.07
4.23
5.01
- 1.60
0.38
0.56
1.89
2.26
1.76 <0.2
(Physically cleaned,
high organic coal)
Total
3.13
2.56
3.05
5.15
6.66
6.55
3.36
1.23
1.22
3.32
3.01
1.76
Samples received from Dr. Scott R. Taylor, Department of Energy, Pittsburgh, Pennsylvania.
Table 1. Selected Coals for Chlorinolysis Experiments
Under Bureau of Mines-Sponsored Program
-------
LABORATORY SCALE PROCESS STUDIES
The laboratory coal processing for coal desulfurization by the JPL
low temperature chlorinolysis process is depicted in Figure 1.
Apparatus
Laboratory apparatus for chlorination of the coal is depicted in
Figure 2. Laboratory apparatus for hydrolysis of chlorinated coal is
depicted in Figure 3. Dechlorination apparatus for the chlorinated and
hydrolyzed coal is depicted in Figure 4.
Laboratory Data
Laboratory data on the coal desulfurization process is summarized in
Table 2 for coal PSOC-219 (HVA Bit, Ky #4, Hopkins, Ky) and in Table 3
for 11 other eastern, midwestern and western coals. A total of 9 bituminous,
2 sub-bituminous and 1 lignite coals has been tested that represents a total
sulfur content in the raw coal from 1.22 to 6.66 weight percent. Organic
sulfur content ranges from 0.46 to 2.24 weight percent and pyritic sulfur
from <0.2 to 5.01 weight percent. Sulfate sulfur constitutes the remaining
sulfur in the coal samples and averaged less than 0.2 weight percent for 9
coals, 0.29 to 0.35 weight percent for 2 coals and 0.84 weight percent for
1 coal.
Coal samples were analyzed by Galbraith Laboratories, Knoxville,
Tennessee for sulfur composition and chlorine in both the raw and treated
coal samples. Ultimate analyses were conducted on several treated coal
samples. Water wash, water scrubber solutions and gas samples were also
analyzed for given tests to obtain material balances.
1099
-------
POWDERED COAL
(-100 TO+200 MESH)
WATER
(30-70% OF COAL)
ORGANIC SOLVENT
(e.g., METHYL CHLOROFORM)
SOLVENT
RECOVERY/
RECYCLE
CHLORINOLYSIS*
50 • 100°C, 1 atm
< 1 TO 2 HOURS
STIRRED REACTOR
SOLVENT
REFLUX
WASTE WATER
INCLUDING HCI, H2SO4
AND OTHER WATER
SOLUBLE SULFATES **
AND CHLORIDES
HCI (g) -*-
H20 (g)
CHLORINE GAS
•*• HCI
CHLORINATED
COAL SLURRY
HYDROLYSISVEVAPORATION
50- 100°C
< 2 HOURS, 1 atm
STIRRED REACTOR
• WATER
COAL SLURRY
FILTRATION
WATER
(FOR DISPLACEMENT
WASH)
COAL (FILTER CAKE)
OECHLORINATION *
350 - 550°C
STEAM
5 min. TO 60 min.
ROTARY DRYER, 2 rpm
STEAM
DESULFURIZEDCOAL
(WITH <0.1% CHLORINE)
LABORATORY GLASSWARE EQUIPMENT FOR THESE
PROCESSES IS SHOWN IN FIGURES 2, 3 AND 4.
Figure 1. Process flow diagram for laboratory
scale coal desulfurization
1100
-------
WATER OR
SODIUM
HYDROXIDE
SOLUTION
WATER
GAS
HOLDER
TITRATION
SLURRY
SAMPLING
LINE
CHLORINE
TANK
SLURRY OF
POWDERED MOIST
COAL IN
METHYL CHLOROFORM
CONSTANX
TEMPERATURE
BATH
Figure 2. Laboratory glassware apparatus
for chlorination of coal
-------
o
10
THERMOCOUPLE
TEMPERATURE
CONTKOUER
REFLUX
CONDENSER
WATER
SCRUBBER
HYDROLYZER
nooo mi)
SIURRY OF
CHLORINATED
COAL AND
WATER
HEATING
MANTLE
FIGURE 3. LABORATORY GLASSWARE APPARATUS FOR
HYDROLYSIS OF CHLORINATED COAL
-------
QUARTZ TUBE
_^J
DECHLORINATION
REACTOR
, , \
[T \_
' MOTOR AND
CHAIN DRIVE
ROTOR (1 RPM)
ii / i
SPLIT TUBE /
FURNACES
WATER
ICE
BATH
\^
WATER
GAS
COLLECTOR
STEAM
GENERATOR
Figure 4. Laboratory equipment for dechIon'nation of coal
-------
CHLORINATION: 500 ml stirred flask; 100 gram sample of -100 to +200 mesh coal; atm pressure;
74°C, Cl2(g) at 0.75 g/min; methyl chloroform/coal at 2- water/coal at 0.5.
HYDROLYSIS: 1000 ml stirred flash; 60-100°C: water/coal at 2-4 per wash; 5-60 minutes
per wash; filtration water wash/coal at 1-2; 1 to ; washes.
DECHLORINATION : 1-inch diameter quartz rotary tube at 1-2 RPM in split tube furnace; coal at
2 to 4 grams/batch; steam atm. an 0.4 to 110 grams/hour; temp of 350 to
550°C; 15 to 75 minutes.
Ave
No . of
Runs
RAW COAL
1
1
6
9
Chlorination
Time
(Hin.)
10
20
30
60
120
Residual Sulfur Analysis
(Wt. %)
Organic
Pyritic
Sulfate
Total
Sulfur Removal
tt)
Organic
Pyritic
Total
Dechlorination
Residual Cl (wt . 7.)
Before
After
COAL PSOC-219, HVA BIT. KY . NO. 4, HOPKINS, KY .
1.08
0. 78
0.69
0.82
0.59
0.45
1.40
0.79
0.73
0.41
0.31
0.48
0.08
0.04
0.11
0.07
0.05
0.14
2.56
1.61
1.50
1. 39
0.95
1.07
28
36
27
45
58
44
48
71
78
65
37
41
46
63
58
4.8
4.9
5.4
10.4
14.6
0.12
0. 37
0.42
0.36
WATER/ COAL - 0.3
1
T
30
60
120
0.57
0.56
0.70
0.75
0.40
0.28
0.04
0.06
0.06
1.37
1.00
1.04
47
48
45
46
71
79
46
61
. 59
4.74
8.86
18.9
0.95
0.21
0.26
WATER/COAL -0.7
•,
T
?
30
60
120
0. 78
0.63
0. 71
0.45
0.47
0.41
0.01
0.02 •
O.Q3
1.24
1.15
1.14
28
41
34
68
66
71
51
55
55
5.1
9.2
11.4
TEMP. - 50 °C
2
0
0
30
60
120
0.78
0.69
0.54
1
1
1
30
60
120
0.71
0.72
0.74
1
60
1
120
0.65
0.30
0.35
0.13
0.25
0.02
0.01
0.05
1.15
0.83
0.84
28
36
50
75
91
82
55
67
67
18,6
0.17
0. 53
1.16
0.45
0, 52
0.50
TEMP. -60°C
0. 16
0.18
0.08
0.01
0.07
0.03
0,87
0.96
0.74
34
40
46
59
87
94
66
62
71
8.6
22.3
0.47
0.50
TEMP. - 85°C
0.35
0.12
1.12
40
75
56
11.3
0.86
Cl2(g) - 0.375 g/min
0.63
0.38
1.31
72
55 ] 49
11.3
0.31
Cl2(g) - 1.5C g/min
2
1
1
30
60
120
1
o
2
1
1
1
3
1
1
1
1
30
60
120
15
20
30
60
120
0.48
0. 33
Q..70
0.72
0. 74
0.64
0.99
0. 77
0.66
0.55
0.66
0.56
0.19
0.04
0,25
0.40
0.18
1.30
0.9fc
0.92
56
69
35
60
86
97
49
62
64
6.3
13.1
19.8
0.57
1.00
SOLVENT - CARBON TETRACHLORIDE
0.31
0.43
0.50
• 0.01
0.08
0.05
1.03
1.20
1.19
33
37
40
78
69
64
60
53
53
8.8
9.0
0.21
0.15
0.96
SOLVENT - TETRACHLOROETHYLEME AT 74°C
0. 34
0.30
0.57
0.53
0.46
0.02
0.13
0.07
0.05
0.05
1.35
1.20
1.30
1.13
1.18
8
29
39
49
37
76
79
59
62
67
47
53
49
56
54
24, 4
11 ,2
15.3
17,1
1.29
1 , 14
0.41
1.01
0.64
SOLVENT - TETRACHLOROIiTHYLENE AT 10P°i:
15
30
60
0.66
1,00
0.73
0,77
0.14
0.42
0.01
•0,01
0,05
1.44
1.14
1.21
39
7
32
45
90
70
44
56
53
23.1
0 ,44
0.31
0. 39
TABLE 2
Laboratory Coal Desulfurization Daca
Chlorination Reaction Parameters. Coal PSOC-219
1104
-------
CHLORINATION: 500 ml stirred flask; 100 gram sample of -100 to +200 mesh coal; atm.
pressure; 74°C; Cl2
-------
Ave
No. of
Runs
Chlorination
Time
(Min.)
Residual Sulfur Analysis
(Wt. •/„)
Organic
Pyritit
Sulfate
local
Sulfur Removal
Organic
Pyricic
Total
Dechlorination
Residual Cl (Wt . 7.)
Before
After
PSOC-213, HVB BITUMINOUS, KY, NO. 9 (CL2(g) - 0.187 g/min.)
RAW COAL
120 •
1.86
0.53
1.89
1.65
0.07
0.01
3.82
2.19
-
72
-
13
-
43 .
0.05
4.6
0.57
PSOC-276, HVA BITUMINOl'S, OHIO NO. 8, HARRISON, OHIO
KAW COAL
1
3
60
120
2.24
0. 74
0.99
2.07
0.40
0.17
0.84
0.20
0.24
5.15
1.35
1.39
67
56
81
94
74
73
10.7
16.6
0.54
0.22
PSOC-026, HVC BITUMINOUS, ILL NO. 6, SALINE, ILL.
.-tAW COAL
: i 30
faO
2.08
1.30
1.25
4.23
0.89
0.55
0.35
0.02
0.06
6.66
2.21
1.87
38
40
79
87
67
72
-
8.46
0.20
0.42
WESTERN COALS
PSOC-086, LIGNITE, ZAP, MERCER, NORTH DAKOTA
SAW COAL
i . 30
1 60
'
0.63
0.35
0. 32
0.52
0.23
0.35
0.03
0.17
0.06
1.22
0.75
0.73
44
50
59
37
39
39
0.00
-
8.00
0.33
-
PSOC-097, SUB- BITUMINOUS A, SEAM 80, CARBOX, WYOMING
KAW COAL
1
1
1
30
60
120
0.84
0. 70
0. 74
0. 79
0.38
0.31
0.05
0.19
0.01 '
0.05
0.02
£.06
1.22
1.06
0.81
1.05
17
12
5
18
87
50
14
31
15
-
-
-
0.28
0.13
0.22
PSOC-240, SUB-BITUMINOUS B, BIG D, LEWIS, WA .
KAW COAL
1
123
1.75
0.49
1.60
0.68
0.01
0.05
3.36
1.22
72
58
64
0.02
-
0.26
TABLE 3 (Cont'd)
Laboratory Coal Desulfurization Data
Eastern, Midwestern, Western Coals
1106
-------
Chlorination
Chlorination was carried out by bubbling chlorine at injection rates
of 0.187 to 1.5 grams per minute through a slurry of 100 grams of -100 to
+ 200 mesh coals with 200 grams of solvent (methyl chloroform, carbon
tetrachloride, tetrachloroethylene) and 20-70 grams of water contained in
a 500 ml. stirred flask equipped with a reflux condenser, cold trap and gas
holder, Figure 2. The Chlorination was conducted at 50-100°C, atmospheric
pressure and reaction times of 10, 20, 30, 60, and 120 minutes.
Observations indicated that chlorine injection rates of 0.187 grams
per minutes were probably too low for obtaining maximum reaction rates.
Chlorine injection at 1.5 grams per minute was excessive with chlorine
being carried over from the coal slurry into the cold trap. At injection
rates of 0.75 grams per minute, the injected chlorine was readily absorbed
by the coal slurry with no penetration of the slurry surface until an
apparent saturation limit for chlorine was reached at approximately 45
minutes. At this point, chlorine carryover into the vapor phase and cold
trap suddenly becomes significant.
Sulfur analyses are reported for organic, pyritic, sulfate and total
sulfur as obtained from Galbraith Laboratories. The attendant processing
conditions for coal PSOC-219 are summarized in Table 2 for each product coal
analyses. For the coal PSOC-219 Chlorination data represented, retention
time, chlorine injection rate, temperature, water content and solvent were
variables with coal mesh size, and the solvent-to-coal ratio was kept invariant
as noted in Table 2. Principal observations were that extended Chlorination
times above 60 minutes did not result generally in increased desulfurization.
1107
-------
Also, lower temperatures of 50 and 60°C and increased water/coal ratios
of 0.7 resulted in decreased organic sulfur removal. Pyritic sulfur
reduction may be favored by the lower temperatures of 50 to 60 C and
reduced by the water to coal ratio of 0.7. The other 11 high sulfur
eastern, midwestern and western coals were chlorinated with only retention
time as a variable (30, 60, 120 minutes) and chlorine injection rate
(0.75 gram/min.),temperature (74°C), solvent (methyl chloroform), solvent/
coal (2), water/coal (0.5) and mesh size (-100 to +200) kept invariant.
Hydrolysis
Hydrolysis conditions were at water/coal ratios of 2, 3 and 4, with
1 and 2 washes and including a water/coal displacement wash of 1 and 2
in the 2 filtration steps for a total water/coal consumption between 4
and 10. Water temperatures were at 60°C, 80°C and 100°C as noted, Table 2.
Hydrolysis times were generally 60 to 120 minutes and as low as 5-20
minutes for given tests. Tests with PSOC-219 indicated that a single
water/coal wash at 2 at a wash time of 20 minutes and water temperature of
80°C reduced the sulfate concentration in the treated coal to less than 0.1
weight percent.
Dechlorination
Dechlorination conditions were at temperatures of 350 to 550 C in the
presence of a steam atmosphere. Initial steam rates were high at 75-110
grams/hour with treated coal charged at 2-4 grams per batch. Reduction
of steam values to 0.4 gram per hour have indicated no apparent reduction
1108
-------
in the rate of HCl evolution in the dechlorination. At 450 C, the
dechlorinatior\ appeared to be complete in under 20 minutes, Figure 5.
The chlorine levels before dechlorination of the treated coal ranged
from 4.6 to 24 weight percent and after dechlorination ranged from
<0.01 to 1.29 weight percent.
COAL DESULFURIZATION CHARACTERIZATION
Twelve Eastern, Midwestern, Western Coals
A summary of organic, pyritic and total sulfur removal for 4 bituminous
eastern coals, 5 bituminous midwestern coals, and 2 sub-bituminous and 1 lignite
western coals is presented in Tables 2 and 3 (Kalvinskas, et. al. 1977). The
data is representative of coal chlorination at a Cl2(g) feed rate of 0.75
gram/min -100 grams coal for 60 minutes. No specific correlations for sulfur
removal exist with geographical region. Seven of the twelve coals show organic
sulfur removal greater than 45 percent with a peak removal of 72 percent.
Two coals show no or little organic sulfur removal. Nine of the twelve
coals show pyritic sulfur removal between 58 and 92 percent. Total sulfur
removals are between 34 and 74 percent for the 12 coals. The values
represent averaged data. Individual runs and given sample analyses indicate
peak removals at 83 percent organic sulfur, 99 percent pyritic sulfur and .83
percent total sulfur.
Total, organic and pyritic sulfur removals and residual sulfur
concentrations after treatment by the desulfurization process are plotted
against chlorination time for each of the twelve coals tested, Figures 6 to
11.
1109
-------
9.C
8.0
DECHLORINATION CONDITION
— TEMPERATURE, 45CTC
— STEAM RATE , 75 GRAMS/HOUR
— COAL SAMPLE , 2-10 GRAMS
TIME
0
5
10
20
30
50
60
HCI EVOLVED
(GRAMS)
0.0
5.29
6.66
B.46
8.49
' 8.49
8.49
2C 25 30 35 40
DECHLORINATION TIME (MINUTES*
45
55
6r
FIGURE 5.
STEAM DECHLORINATION OF TREATED
COAL WITH TIME
1110
-------
Total Sulfur
Total sulfur removal and residual total sulfur is depicted with
chlorination time for 12 coals in Figures 6 and 7, respectively. Peak
removals and minimum residual values are at 60 minutes chlorination time,
which exceed sulfur removals at 30 and 120 minutes.
Organic Sulfur
Organic sulfur removals and residual organic sulfur for 12 coals is
depicted with chlorination time, Figures 8 to 9. Residual organic sulfur
values are grouped relatively high for coals PSOC-190, 342, 026, and 513,
and represent an initially high organic sulfur in the raw coal that appears
somewhat resistant to chlorination. Remaining coals have substantially
reduced levels of organic sulfur with treatment for 60 minutes. Continual
chlorination beyond 60 minutes to 120 minutes appears to increase organic
sulfur values in 4 of the coals/ and decrease organic sulfur in only
2 of the coals.
Pyritic Sulfur
Pyritic sulfur reductions and residual values with chlorination time
are depicted, Figures 10 and 11, respectively. Pyritic sulfur shows a sharp
reduction (44 to 48%, PSOC-219) at short reaction times of 10 to 20 minutes.
Two of the coals, PSOC-219 and 097 have peak pyritic sulfur reduction of
78 and 87 percent at sixty minutes chlorination time and drop off to- 65
and 50 percent at 120 minutes respectively. Four of the coals, PSOC-190,
276, 108, and 342, provide increasing pyritic sulfur removals beyond 60 minutes
1111
-------
CHLORINATION:
74"C; ATM. PRESS.; Cl
METHYL CHLOROFORM^?OAL AT 2;
WATER/COAL AT 0.5
HYDROLYSIS:
60-8
-------
6.8
6.4
74°C; ATM. PRESS.; C\2M 0.75g/min;
METHYL CHLOROFORM/COAL AT 2; WATER/COAL
AT 0.5 '
60-80°C; WATER/COAL AT 4/WASH; 60 min/WASH;
FILTRATION WATER WASH/COAL AT 1; 1-2 WASHES
DECHLORINATION: 400-500°C; STEAM ATM; 30-60 min.
REF, TABLES J/2,_3 . COALS IDENTIFIED BY ERDA PSOC NUMBER.
CHLORINATION
0.4 -
60
TIME (MINUTES)
Figure 7, Residual Total Sulfur with Chlorination Time
(Eastern,Midwestern, Western Coals).
1113
-------
80
70
V~l
u
z
o
o
60
0
t—
u
a 50
40
10
I
CHLORINATION:
HYDROLYSIS:
I
I
74°C; ATM. PRESS.; CI2/a) 0.75 g/min;
METHYL CHLOROFORM/COAL AT 2; WATER/COAL
AT 0.5
60-80°C; WATER/COAL AT 4/WASH; 60 min/WASH;
FILTRATION WATER WASH/COAL AT 1; 1-2 WASHES
DECHLORINATION: 400-500 C; STEAM ATM; 30-60 min.
REF. TABLES -LI'*.. COALS IDENTIFIED BY ERDA PSOC NUMBER.
TIME (MINUTESI
Figure 8, Organic Sulfur Reduction with Chlorination Time
(Eastern, Midwestern, Western Coals).
1114
-------
CHLORINATION:
HYDROLYSIS:
2.4
2.2
74°C; ATM. PRESS.; Clo/glO.75 g/min;
METHYL CHLOROFORM/COAL AT 2; WATER/COAL
AT 0.5
60-80°C; WATER/COAL AT 4/V/ASH; 60 mtn/WASH;
OU™OV ^ff VT f^ I ti\/ ^*W^U ^ I t/ »» «JiT; uw riiiii/ wvr^ji i;
FILTRATION WATER WASH/COAL AT 1; 1-2 WASHES
DECHLORINATION: 400-500°C; STEAM ATM; 30-60 mln.
REF. TABLES Jf?,3... COALS IDENTIFIED BY ERDA PSOC NUMBER..
0.2 -
20
40
60
TIME (MINUTES)
BO
100
120
Figure 9, Residual Organic Sulfur With Chlorination Time
(Eastern, Midwestern, Western Coals).
1115
-------
CHLORINATION:
74"C; ATM. PRESS.; CI2 ra) °-75 9/min;
METHYL CHLOROFORM/COAL AT 2; WATER/COAL
AT 0.5
60-80 C; WATER/COAL AT 4/WASH; 60 min/WASH;
FILTRATION WATER WASH/COAL AT 1; 1-2 WASHES
DECHLORINATION: 400-500"C; STEAM ATM; 30-60 m!n.
REF. TABLES J »?»?... COALS IDENTIFIED BY ERDA PSOC NUMBER.
20
60
TIME (MINUTES)
120
Figure 10, Pyrytic Sulfur Reduction With Chlorination Time
(Eastern, Midwestern, Western Coal).
1116
-------
CHLORINATION: 74°C; ATM. PRESS.; ClofM °-75 9/min''
5.2
4.8
0.4
HYDROLYSIS:
METHYL CHLOROFORM/COAL AT 2; WATER/COAL
AT 0.5
60-80°C; WATER/COAL AT 4/WASH; 60 min/WASH;
FILTRATION WATER WASH/COAL AT 1; 1-2 WASHES
DECHLORINATION: 400-500°C; STEAM ATM; 30-60 min.
REF. TABLES_IA3_.COALS IDENTIFIED BY ERDA PSOC NUMBER.
60
TIME (MINUTES)
Figure 11, Residual Pyritic Sulfur with Chlorination Time
(Eastern, Midwestern, Western Coals).
1117
-------
and up to 120 minutes. Analyses of given samples have shown up to 100% pyritic
sulfur removal. Residual pyritic sulfur values for PSOC-342 and 240 remain
relatively high compared to the other coals. Other coals have residual
pyritic sulfur values of 0.1 to 0.4 weight percent.
PARAMETRIC DESULFURIZATION DATA, PSOC-219
Thirty coal desulfurization test runs were conducted with coal
PSOC-219, HVA Bituminous Ky. No. 4, Table 2. Chlorination parameters
investigated with respect to coal desulfurization with time are solvents
(methyl chloroform, carbon tetrachloride, tetrachloroethylene), temperatures
(50, 60, 74, 85 C), water/coal of 0.3, 0.5 and 0.7 and chlorine feed rates
of 0.187, 0.375, 0.75 and 1.5 grains per minute per 100 grains of coal.
Chlorination parameters kept invariant were: coal size at -100 to +200 mesh,
solvent to coal ratio at 2, and atmospheric pressure.
Solvents
Pyritic and organic sulfur removals with solvents methyl chloroform,
carbon tetrachloride, and tetrachloroethylene are depicted in Figures 12
and 13 respectively. The average pyritic sulfur removal data provide some
distinct differences with respect to the three solvents for any given
Chlorination time. However, the overall data patterns with Chlorination
time represented do not suggest consistent differences between the three
solvents in providing either pyritic or organic sulfur removal.
1118
-------
COAL PSOC-219, HVA, bit., KY. NO. 4
74°C, ATM. PRESS; C\2 la] 0.75 g/min;
SOLVENT/COAL AT 2; WATER/COAL AT 0.5
CHLORI NATION:
60-100°C; WATER/COAL AT 2-4/WASH; 5-60 min/
WASH; FILTRATION WATER WASH/COAL AT
1-2; 1-2 WASHES
350-550°C; STEAM ATM: 15-75 min.
HYDROLYSIS:
DECHLORI NATION
REF. TABLE
20 -
10
20
40
60
TIME (MINUTES)
Figure 12, Pyritic Sulfur Reduction, Coal PSOC-Z19 with Chlorination Time
(Parametric data with solvents - methyl chloroform, carbon
tetr a chloride, tetrachloroethylene).
1119
-------
2
O
g
LU
Ct
Of.
u.
y
1
CARBONTETRACHLOR1DE
20 -
COAL PSOC-219, HVA, bit., KY. NO. 4
10 -
DECHLORINATION
REF. TABLE _2_
74°C, ATM. PRESS; Cl2 (q) 0.75 g/min;
SOLVENT/COAL AT 2; WATER/COAL AT 0. 5
60-100°C; WATER/COAL AT 2-4/WASH; 5-60 min/
WASH; FILTRATION WATER WASH/COAL AT
1-2; 1-2 WASHES
350-550°C; STEAM ATM; 15-75 min.
20
40 60
TIME (MINUTES)
80
100
120
Figure 13, Organic Sulfur Reduction, Coal PSOC-219 with Chlorination Time
(Parametric data with solvents - methyl chloroform, carbon
tetrachloride, tetrachloroethylene).
1120
-------
Temperature
Pyritic and organic sulfur removal with chlorination time for
chlorination temperatures of 50, 60, 74, and 85°C are depicted, Figures
14 and 15, respectively.
Pyritic sulfur removal appears aided by the temperatures of 50 and
60 C relative to 74°C and 85°C. Organic sulfur removal appears to be
assisted by a temperature of 74°C relative to 50 and 60°C.
Water/Coal
Pyritic and organic sulfur removal with chlorination time is depicted
for parameters of water/coal at 0.3, 0.5 and 0.7, Figures 16 and 17,
respectively.
Although the overall patterns of data for water/coal with respect
to chlorination time are not totally consistent, water/coal of 0.3 and
0.5 appear to favor greater pyritic and organic sulfur removal relative to
a water/coal of 0.7.
i
Chlorine Feed Rates
Desulfurization data at low chlorine feed rates of 0.187 and 0.375
grams per minute per 100 grams of coal are available for comparision with
the higher feed rates of 0.75 'and 1.5 grains per minute per 100 grams of
coal at long reaction times of 120 minutes, Table 2. There appear to
be no significant differences in desulfurization data within the existing
data variance between the different chlorine feed rates. At 30 and 60
minutes, there appears to be no advantage in desulfurization by increasing
the chlorine feed rate from 0.75 to 1.5 grams/minutes - 100 grains coal.
1121
-------
90 -
z
o
u.
i/)
-------
COAL PSOC-219. HVA, bit., KY. NO. 4
74°C, ATM. PRESS; C\2 (q) 0.75 g/min;
SOLVENT/COAL AT 2; WATER/COAL AT 0.5
60-100°Q WATER/COAL AT 2-4/WASH; 5-60 min/
WASH; FILTRATION WATER WASH/COAL AT
1-2; 1-2 WASHES
350-550°C; STEAM ATM; 15-75 min.
CHLORI NATION
HYDROLYSIS
DECHLORINATION:
REF. TABLE 2
60
TIME (MINUTES)
Figure 15, Organic Sulfur Reduction, Coal PSOC-219 with Chlorination Time
(Parametric values of temperature at 50, 60, 74, 85 C)
1123
-------
z
o
ae
Of
U
COAL PSOC-219, HVA, bit., KY. NO. 4
74-C, ATM. PRESS; C\2 la)0.75 g/min;
SOLVENT/COAL AT 2; WATER/COAL AT 0.5
60-100° Q WATER/COAL AT 2-4/WASH; 5-60 min/
WASH; FILTRATION WATER WASH/COAL AT
1-2; 1-2 WASHES
350-550°C; STEAM ATM; 15-75 min.
HYDROLYSIS:
DECHLORINATION
REF. TABLE 2
60
TIME (MINUTES)
Figure 16, Pyritic Sulfur Reduction, Coal PSOC-219 with Chlorination Time
(Parametric values of water/coal at 0. 3, 0. 5, 0. 7).
1124
-------
H-O/COAL-0.3
COAL PSOC-219, HVA, bit., KY. NO. 4
74"C, ATM PRESS; C\2 (g) 0.75 g/min;
CHLORINATION:
SOLVENT/COAL AT 2; WATER/COAL AT 0.5
60-100°C; WATER/COAL AT 2-4/WASH;
5-60 min/WASH; FILTRATION WATER WASH/
COAL AT 1-2; 1-2 WASHES
DECHLORINATION: 350-550°C; STEAM ATM; 15-75 rmn.
HYDROLYSIS:
60
TIME (MINUTES)
Figure 17, Organic Sulfur Reduction,. Coal PSOC-219 with Chlorination Time
(Parametric values of water/coal at 0. 3, 0. 5, 0. 7)
1125
-------
A calculation of stoichdometrie chlorine requirements for
conversion of organic sulfur to sulfonates is 3 moles Cl_ per mole of
organic sulfur and conversion to sulfate requires 3.5 moles Cl? per mole of
organic sulfur. Chlorine requirements to convert pyritic sulfur to sulfate
are 3.5 moles of Cl_ per mole of sulfur. On the basis of 3.5 moles of
chlorine per mole of total sulfur less the sulfate sulfur, chlorine
requirements are from a low of 9.2 grams Cl_ per 100 grams of coal for
PSOC-086 (1.19% organic and pyritic sulfur) to 19.2 grams Cl_ per 100
grams of coal for PSOC-219 (2.48% organic and pyritic sulfur) to a high
of 49.5 grams of C12 per 100 grams of coal for PSOC-342 (6.4% organic and
pyritic sulfur). The efficiency of chlorine usage for sulfur oxidation
to sulfate for coal PSOC-219 appears to be as follows:
Chlorination Time Chlorine Usage Eff.
(minutes) (%)
10 95
20 54
30 40
60 26
120 12
Thus, the addition of surplus chlorine at long Chlorination times at
0.75 g/min of C12 per 100 grams of coal makes relatively inefficient use of chlo-
rine. A reduction in chlorine addition after a short Chlorination period may be
desirable to conserve chlorine while still maintaining desulfurization rates.
Sulfate
The Chlorination oxidizes the pyritic and organic sulfur to water
soluble sulfates. Residual values of sulfate in the processed coal are
primarily an indication of the effectiveness of the water wash in the
1126
-------
hydrolysis stage and the displacement water wash in the filtration.
Residual sulfate values for PSOC-219 are included in Table 2 and for
the other 11 coals tested in Table 3. Sulfate values after washing
are generally under 0.1 weight percent and only occasionally at higher
values,up to 0.4 weight percent.
Generally excessive water wash conditions to extract the sulfate from
the coal have been used. Preliminary data indicate that a single water wash
at a water/coal of 2 in the hydrolysis stage at 80°C and 20 minutes followed
by a water/coal filtration wash at 2/1 is adequate to reduce the sulfate
content to less than 0.1 weight percent.
Residual Chlorine
Chlorine values in the treated coals before dechlorination range
between 4.8 and 23.1 weight percent, Tables 2 and 3. The lower chlorine
values are for the shorter chlorination times, 10 to 30 minutes, and the
highest values are present at higher times of 60 to 120 minutes.
Dechlorination of the treated coal at temperatures of 350 to 550 C
in a steam atmosphere for 15 to 75 minutes provides residual chlorine
values from <0.01 to 1.29 weight percent with-average values of less than
0.5 weight percent.
The bulk of the residual chlorine (95%) appears to be readily removed
at even low temperatures of 350°C, low steam rates (steam to coal of 0.1)
and 20 minutes. A number of dechlorination tests have shown reduced
residual chlorine values of less than 0.1 weight percent.
Additional dechlorination experiments are required to obtain consistent
dechlorination to 0.1 weight percent chlorine.
1127
-------
Ultimate Analyses
Ultimate analyses of raw and treated coals PSOC-219 and PSOC-190
are given in Table 4. Coal PSOC-219 exhibits a significant reduction
in hydrogen, approximately 2 weight percent, whereas PSOC-190 exhibits
less than 1 weight percent reduction in hydrogen. The nitrogen content
in the PSOC-219 raw coal appears in error at 0.1 weight percent. The carbon
content of PSOC-190 rises sharply after treatment, apparently as a. result
in part of the combined decrease (5.2 percent) of sulfur, oxygen and
hydrogen.
Trace Metal
Trace metal analysis in raw/treated PSOC-219 and PHS-398 coals indicate
sharp reductions for titanium, phosphorous, arsenic, lead vanadium, lithium
and beryllium (Table 5). Reductions are from 48 to 91 percent in treated
PSOC-219 coal.
Material Balance
Material balances were obtained for coal, methyl chloroform, chlorine
and sulfur. Water solutions, cold traps and gas holders were sampled and
analyzed to obtain total material balances. A material balance for run
118-9/9/77 on coal PSOC-219 is represented, Table 6. Solvent and chlorine
balances are 98.6% and 94.1% respectively. Improvements in seals and handling
should lead to a better recovery of solvent and chlorine. Coal losses are more
substantial and reflect the fact that dechlorination was carried out with 2-4
gram samples. Relatively small handling losses of the coal-in dechlorination
of several tenths of a gram reflect sizeable percentage losses. Additionally,
dechlorination in the run was carried out at 500 C which also provided a
significant loss of volatile material. Restriction of dechlorination
1128
-------
10
VO
Component
C
H
N
S
Cl
Ash
0 (by difference)
Moisture
Heating Value (Btu/lb)
PSOC-219
(HVA Bit. KY No. 4)
Raw Coal
(Wt.%)
74.16
5.30
0.10
2.56
0.03
8.06
9.79
0.00
13,398
Treated Coal
Run 138-10/17/77
(Wt.%)
75.53
3.46
1.84
0.88
0.45
7.78
10.06
-
12,412
Run 138-10/17/77
(Wt.%)
74.83
2.38
1.65
1.02
0.75
7.40
11.97
-
12.780
Run 120-9/16/77
(Wt. %)
77.30
3.16
1.26
1.00
1.40
6.23
9.65
0.00
. -
PSOC-190
(HVA Bit. ILL. No. 6, Knox. III.)
Raw Coal
(Wt.%)
69.15
4.89
1.00
3.05
0.06
8.49
13.42
0.00
-
Treated Coal
Run 109-8/8/77
(Wt.%)
74.15
3.99
1.36
1.36
0.06
8.29
10.80
-
-
Table 4. Ultimate analyses of treated coals PSOC-219 and PSOC-190
-------
(jj
o
Analyses
Titanium
Phosphorous
Arsenic
Lead
Vanadium
Lithium
Barium
Beryllium
Cadmium
Mercury
Selenium
PSOC-219"
Raw Coal
PPM
1086
131
73
46
46
<10
5
8
1
<1
<1
PSOC-219 Treated Coal
Run 107 - 7/27/77
DDU
rrWI
510
68/130
25
4
12
5
5
4
<1
<1
<1
Percent
Reduction (Wt. %)
53.0
48.1/0.8
65.8
91.3
81.0
~50.0
0.0
50.0
Run 120 -9/1 6/77
PPM
680
68
49
5
48
-
-
13
-
—
— •
Percent
Reduction (Wt. %)
37.4
48.1
32.3
89.1
0.0
-
-
0.0
-
-
—
PHS-398b
Raw Coal
PPM
1400
1040
85
0.5
<25
20
<10
5
-
<0.5
<1
PHS-398 Treated Coal
Run 140 -10/20/77
PPM
700
700
9
3
<25
21
92
4
—
<0.5
<1
Percent
Reduction (Wt. %)
50.0
32.7
89.4
-
~0.0
0.0
20.0
-
~0.0
-0.0
"HVABit KyNo.4.
bRaw Head. 3A. Freidens (Somenet), Pa. Received from Dr. Scott R. Taylor, Bureau of Mines, Pittsburgh, Pa.
Table 5. Trace metal analyses of raw/treated PSOC-219 and PHS-398
-------
u>
Process Unit
Chlorinator (Feed)
Chlorinator Cold Trap
Chlorinator Gas Scrubber
Chlorinator Gas Collector
Solvent Evaporator
Hydrolyzer
Dechlorinator Gas Scrubber
Dechlorinator Gas Collector
Product Coal Storage
Total Accounting
Unaccounted
Process Stream
Coal. C£, Solvent, S
CH3 cc£3. c£
Cf, SO4. TOC
CH3 CC£3
Cf. SO4. TOC,
Trace Metals
C£. SO4. TOC
Product Coal, C£. S
Coal
(Ind. Sulfur)
Grams
97.07
0.045C
0.0029
1.1C
1.125e
2.Wf
2.31
74.09
(87.86)d
83.30
13.77
Wt.%
0.046C
0.003
1.1C
1.16*
2.97C
2.38
76.33
(90J5&
85.81
14.19
Methyl
Chloroform
Grains
200
1.3
195.8
197.1
2.9
Wt.%
0.7
97.9
98.6
1.4
Chlorine
Grams
45
12.69
1.5
18.1b
9.72b
0.34
42.34
2.66
Wt.%
28.2
3.3
40.2b
21.6b
0.8
94.1
5.9
Sulfur
Grams
2.56
<0.01a
1.30a
0.44a
0.71
2.45
0.11
Wt.%
50.8a
17.2a
27.7
95.7
4.3
3SO4 as Sulfur
bChloride
cCarbon
Product Storage Including Unaccounted Coal
eTrace Metals
Table 6. Material balance for run 138-10/7/77, coal PSOC-219
-------
temperatures to 400°C will bring losses on PSOC-219 to less than 1 weight
percent. Losses of coal found prior to the dechlorination stage were
^1.1 percent. The major handling loss and loss of volatile matter appeared
to be in the dechlorination stage.
MINI-PILOT PLANT
Parallel with laboratory and bench-scale coal desulfurization studies,
a continuous flow mini-pilot plant will be constructed for an integrated
equipment operation. Coal will be fed at a nominal rate of 2000 grams per
hour from a pulverized coal feed hopper through chlorination, hydrolysis and
dechlorination stages. The coal desulfurization mini-pilot plant is repre-
sented as an integrated equipment unit, Figure 18.
Major equipment units include a ground coal hopper and blender,
chlorinator, hydrolyzer, rotary vacuum filter, flash dryer, dechlorinator and
product coal storage hopper.
The chlorinator and hydrolyzer will be constructed of acid-resistant
brick in lieu of more expensive metal claddings. An immersion testing program
has been conducted with the assistance of Pennwalt Corporation and Stebbins
Engineering and Manufacturing Co. to choose acceptable brick and mortar samples
for the highly corrosive and abrasive conditions to be found in the chlorinator
and hydrolyzer.
ECONOMICS
Capital Costs
Preliminary cost estimates have been made (JPL, 1976) for a 12,500 ton
per day coal processing plant, Table 7. The capital costs for the coal
preparation and desulfurization plant are estimated at $23-46 million. On the
basis of capital costs provided (L.E. Bostwick, 1977) a grass roots Kel-chlor
plant for conversion of HCL to Cl2is $62 million. The total capital investment
is estimated at $84-108 million.
1132
-------
GIOUND COAL MOPPt«
AND ILENOEI
2\ CONDENSH
3\ IEFIIIOUATED COLO TIAf
GAS COLLECTOK
CMLOdlNAIOH
HYMOLYZFH
SOLVENT STORAGE TANK
VACUUM FILTH
FLASH 0»VE«
OECHLOIINATOI
CLEAN COAL STOHAOE
HOT GAS/AIK MIXEI
NEUTtALIZINO COLUMN
DtCHLOHINATC* OFF-GAS VtNT
DCCHLOIINATOI STACK GAS
LINE
DISPEISION MILL
INSULATED STEAM LINE
IOTMY AIRLOCK
DIRECTION OF COAL FLOW
DRAWING NO. M5-800-*
NOTE: SCALE FOR ORIGINAL IS X ?l DRAWING SCALE I/'}?' • 1'
Figure IB. JPL .coal desulfurization mini-pilot plant --
side elevation
1133
-------
I. Capital Investment (12,500 Tons of Coal Per Day)
$ 106
Coal Handling, Preparation and Desulfurization $23-46
Kel-Chlor Plant (Grass Roots Basis) $62
Total Capital Investment $85-108
($/ton)«
II. Operating Cost
Utilities 1.05
Materials
Chlorine (3.5 Moles Cl2/Mole Sulfur for PSOC-219, 3.26-6.71
384 Ibs/ton of coal 9$17-35/ton of Cl.)
HCL (5% makeup, 19.2 Ibs/ton of coal 9 3$/Ib.) 0.58
Methyl Chloroform (Makeup at 0.5%, 20
-------
Operating Costs
The largest portion of the operating costs are raw material costs.
Chlorine costs have been included on the basis of the stoichiometric amount
of Cl, required to oxidize the organic and pyritic sulfur contained in
PSOC-219 coal to sulfate. The Cl_ requirement is 384 Ibs. per ton of
PSOC-219 coal. A cost of $17 to $35/ton of C12 includes all operating
costs and capital charges. The $17 per ton of Cl_ represents an early
published cost (Van Dijk and Schreiner, 1973) based on a battery limits plant
and the $35 per ton of Cl_ represents a recent estimated cost for a grass
roots plant (Bostwick, 1977). Methyl chloroform solvent costs are based on
a 0.5% process loss. The cost of methyl chloroform is estimated on the
basis of cost projections for large scale production. A reduced solvent usage
requirement or improved solvent recovery will have a significant impact in
cost reduction. Capital and maintenance charges are called out only for the
coal processing plant since Kel-Chlor charges have been included in the
chlorine cost.
Fixed Charges
Capital recovery of the coal processing plant has been estimated on the
basis of 15 years at 10% interest charges. Taxes and insurance are 3% of the
fixed capital investment. Total fixed charges amount to $2.70-4.68 per ton
of coal.
Waste Stream
Earlier cost estimates have assumed that sulfuric acid recovery as a
by-product would -defray the waste steam processing costs. Until this is
substantiated, an additional charge of $0.92 per ton of coal has been included
for waste treatment and sludge processing. It's based on a sludge processing
1135
-------
cost with no by-product recovery and is in line with sludge disposal
costs incurred in flue gas desulfurization (Jimeson and Maddocks 1976)
Overall Process Costs
The overall process costs for coal PSOC-219 are estimated at $13 34
to $19.05 per ton of coal feed. Coals with higher or lower sulfur conte
will have & proportionately higher or lower processing cost based on the
chlorine requirement of 3.5 moles per mole of organic and pyritic sulfur
The chlorine cost amounts to $1.55-2.94 for each 1 weight percent of sulf
in the coal. Any inefficiencies in the chlorine usage in the process will
be reflected in proportionately higher chlorine costs.
RESULTS AND CONCLUSIONS
Coal desulfurization data for twelve eastern, midwestern and western
coals that include bituminous,sub-bituminous and lignite coals show
substantial organic and pyritic sulfur removal for the majority of coals
Table 8. Five coals show greater than 50% organic sulfur removal, 5 coals
show better than 80% pyritic sulfur removal and 6 coals show better than
60% total sulfur removal. No correlation appears between sulfur removal
and geographical origin of the coal. The desulfurization process appears
applicable to a wide variety of coals. Optimization of the coal
desulfurization process operating conditions is expected to achieve
desulfurization levels required to meet environmental sulfur compliance
levels for a substantial number of coals. Costs of the desulfurization
process are competitive with existing flue gas desulfurization processes and
other chemical coal cleaning processes for dasulfurization.
1136
-------
SULFUR REMOVAL (%)
COAL DESCRIPTION ORGANIC PYRITIC TOTAL
EASTERN COALS
PSOC-108, HVA Bit. 53 79 &Q
Pittsburgh, Wash., PA.
PSOC-342, HVA, Bit. 3 63 50
Clarion, Jefferson, PA.
PHS-398, Raw Head, 3A - 42 92 71
Upper Preeport, Somerset, PA.
(BOM-High Pyr., Low Org.)
PHS-513, Mine 513, 34 _ 34
Upper Clarion, Butler, PA.
(BOM-Phys. Cleaned, High Org.)
MIDWESTERN COALS
PSOC-219, HVA Bit. 45 78 63
Ky #4, Hopkins, Ky.
PSOC-276, HVA Bit. 67 81 74
Ohio #8, Harrison, Ohio
PSOC-026, HVC Bit. 40 87 72
111. #6, Saline, 111.
PSOC-213, HVB Bit. 72 13 43
Ky. #9 (120 min., C12(0.182 g/min)
PSOC-190, HVA Bit. 19 90 4?
111. #6, Knox, 111.
WESTERN COALS
PSOC-240A1, Sub-bit. B 72 53 '54
Big D, Lewis, Wash. (120 Min.)
PSOC-097, Sub-bit. A 12 87 34
Seam 80, Carbon, Wyo.
PSOC-086,Lignite 50 37 39
Zap. Mercer, N. Dak.
*(Chlorination - 60 minutes, C12 @ 0.75 g/min. - 100 grains)
Table 8. Summary of Coal Desulfurlzation Data*
Eastern, Midwestern, Western Coals
1137
-------
REFERENCES
Bostwick, L., Private communication. 1977.
Hsu, G., J. Kalvinskas, P. Ganguli, G. Gavalas. 1977. Coal desulfurization
by low temperature chlorinolysis. ACS Symposium Series, No. 64, coal
desulfurization.
Jet Propulsion Laboratory. 1976. Coal desulfurization by low temperature
chlorinolysis. Proposal No. 76-763.
Jimeson, R., and R. Maddocks. 1976. Trade-offs in selecting SO emission
controls. Chemical Engineering Progress. 72:8 X
Kalvinskas, J., et al. 1977. Final report for phase 1 - coal desulfurization
by low temperature chlorinolysis. Jet Propulsion Laboratory Publication
78-8.
Van Dijk, C., and W.C. Schreiner. 1973. Hydrogen chloride to chlorine via
the Kel-chlor process. Chemical Engineering Progress. 69:4.
1138
-------
ACKNOWLEDGEMENT
The research described in this paper was carried out at the
Jet Propulsion Laboratory, California Institute of Technology, and
was sponsored by the United States Bureau of Mines through an interagency
agreement, Contract No. J0177103, with NASA.
1139
-------
Conversion factors from English units to the
International System of Units (ISU)
To convert from
English units
atmosphere
British thermal unit
(mean)
inch
pound (Ibm avoirdupois)
ton (short, 2000 pound)
ton (metric)
to ISU
newton/meter
joule
meter
kilogram
kilogram
kilogram
multiply by
1.01325 x 10"
1.05587 x 10'
2.54
x 10
-2
4.5359237 x 10
9.0718474 x 10
-1
1.00
x 10"
1140
-------
OXIDATIVE COAL DESULFURIZATION USING NITROGEN OXIDES
THE KVB PROCESS
E. D. Guth
KVB, Inc.
Tustin, California
ABSTRACT
The ecologically acceptable utilization of coal energy sources is vital
to the nation's technological progress and economic well being. Methods and
processes to control coal combustion emissions particularly sulfur oxides
are being evaluated to determine their relative merits. KVB's coal desul-
furization process offers a low cost means to remove pyritic and up to 40
percent of the organic sulfur from coal.
The KVB coal desulfurization process is based upon selective oxidation of
the sulfur constituents of the coal. In this-process, dry coarsely ground
coal (+28 mesh) is heated at one atmosphere pressure in the presence of
nitrogen oxide and oxygen gases for the removal of a portion of the coal sulfur
as gaseous sulfur dioxide (S02>. The remaining reacted sulfur in the coal is
in the form of inorganic sulfates, sulfites or is included in an organic
radical. The non-gaseous sulfur compounds derived from pyrites are removed
from the pretreated coal by subsequent washing with water. Additional washing
with heated caustic solution followed by water removes up to 40 percent of the
organic sulfur.
The active oxidizing agent is believed to be NO.. The process, however,
uses a gas mixture containing oxygen (0.5 to 20 percent 0? by volume), nitrogen
monoxide (0.25 to 10 percent NO by volume), nitrogen dioxide (0.25 to 10
percent N02 by volume) and nitrogen (N«) the remainder.
The mechanism of oxidation is not known; however, it is postulated that
NO is oxidized by oxygen to N02 which is reduced back to NO in the reaction
to form oxidized sulfur compounds.
The process is in its early stages of development. Laboratory experi-
ments conducted on 50 gram samples in a batch reactor, with five different
coals, indicate that the process has desulfurization potential of up to 63
percent of sulfur with basic dry oxidation plus water washing treatment and
up to 89 percent with dry oxidation followed by water washing, caustic
treatment and final water washing. However, depending on the amount of desul-
furization required, the extraction and washing steps may or may not be
1141
-------
required. Where dry oxidation only could remove sufficient sulfur to meet
the sulfur dioxide emission standards, this technology provides a very simple
and inexpensive system.
The washing step removes iron and loosely bound inorganic material which
reduces the ash content of the coal.
In the KVB process all the pyritlc sulfur is converted to either sulfur
oxides or sulfates.
Economic estimates indicate that coal could be desulfurized on a
commercial scale for $6.00 to $10.00/ton using KVB's process.
INTRODUCTION
Chemical coal cleaning is the treatment of coal with chemical
reactants to produce a product with improved more uniform fuel
properties. The purpose of chemical coal cleaning is sulfur
removal. Also minerals and trace elements are removed in the
processing steps. Precombustion desulfurization can decrease
the need for flue gas scrubbers as well as reduce corrosion in
power generating units using coal as the fuel. Off-line coal
desulfurization increases the reliability of power unit operation
by reducing boiler dependence on scrubber operation. The decrease
in ash and trace elements has the added advantages of decreased
mill wear, less fuel and ash to transport and more uniform combus-
tion properties. In evaluating coal cleaning the overall power
plant fuel scenario should be examined considering the advantage
of R.O.M. and processed fuels. Lower corrosion will lead to lower
capital and operating costs. Ash and trace element contaminants
are removed from the flue gas by physical methods (e.g.,
precipitators).
1142
-------
KVB's chemical coal cleaning method is part of an overall
fuel cleaning technology. Since 1973 KVB has developed fuel
cleaning technology to remove sulfur from oils and coal. This
presentation is a report on the technical development of KVB's
coal desulfurization method. Some aspects of the oil desulfuriza-
tion technology are discussed as they relate to the removal of
organic sulfur from coal.
The selective oxidation of the sulfur compounds in coal is
the primary step of KVB's patented (U.S. 3,902,211) coal
desulfurization process. The oxidation uses gas phase nitrogen
dioxide as a carrier for oxygen with nitrogen as a diluent and
removes sulfur in three ways (Figure 1):
Gas Phase - oxidizing about one half of the pyritic
sulfur to S02
Water Phase - washing the oxidized pyritic sulfur
from the coal as water soluble iron sulfites and
sulfates
Caustic Phase - treating the water washed coal with
caustic to remove about one half of the organic
sulfur as inorganic sulfites and sulfates
The three sulfur removal steps can be employed singly or in
combination with or in conjunction with other methods for
physical removal of pyritic sulfur.
1143
-------
Coal
Oxidation
SO,
from Pyritic
Sulfur
Water
wash
SO,
from Organic
Sulfur
Caustic
treatment
Clean Coal
Figure 1. Process description.
P-213
1144
-------
The oxidation of organic sulfur compounds to sulfides and
sulfones using N02 and oxygen is reported in the patent litera-
ture. The N02 oxidation can be carried out to oxidize the
sulfur atoms selectively. Further, reactant N02 is regenerated
from the reduced form, NO, by reaction with gaseous oxygen at
ambient conditions. KVB has applied N02 oxidation to the complex
mixtures of inorganic and organic chemical forms of sulfur in
oil and coal for sulfur removal.
The high oxidation potential of N02 and its selectivity of
reaction to oxidize sulfur compounds make possible the use of
mild oxidation conditions. The oxidation operation in KVB's coal
desulfurization process is carried out at atmospheric pressure
and temperatures up to 100 °C. Coarse ground coal can be used
(-14 +28 mesh) as the oxidizing gas penetrates the coal structure,
KVB's coal desulfurization technology is in the early stage
of development and has the potential for a low cost chemical
coal cleaning method; however, there are still questions to be
answered. This presentation covers the reaction conditions and
laboratory test results for the three types of sulfur removal,
oxidation, water wash, caustic wash, the chemistry of the sulfur
reactions, including a discussion of organic sulfur reactions
and preliminary process economic estimates.
1145
-------
Reaction Conditions
Ideally a chemical coal cleaning process would have the
following characteristics:
Coal size - coarse (+ 28 mesh)
Temperature - low (ambient to 100 °C)
Pressure - atmospheric
Efficiency - pyritic sulfur (90-100% removal)
- organic sulfur (90-100% removal)
Chemical usage - small quantity, low cost
Selectivity - no adverse changes in the coal
Process time - short (1-15 minutes)
KVB's chemical coal cleaning method has the following
characteristics:
Coal size - 14 +28 mesh
Temperature - ambient to 100 °C
Pressure - atmospheric
Efficiency - pyritic sulfur up to 100%
- organic sulfur up to 40%
Chemical usage - oxygen, some N02 and water are consumed
Selectivity - no adverse changes in the coal
Process time - 1 to 2 hours total
The selective oxidation is carried out on -14 +28 mesh coal
at one atmosphere pressure and 100 to 200 °F. The reaction time
is 0.5 to 1.0 hours. The water wash takes only a few minutes
at atmospheric pressure and at 25 to 100 °C. The caustic treatment
1146
-------
takes place from 0.5 to 1.0 hours at atmospheric pressure and
at 25 - 100 °C. The total processing time is about 2 hours.
KVB's coal cleaning method differs from the ideal coal
cleaning process only in the time of treatment and the degree
of organic sulfur removed; however further development work
could reduce these limitations.
Background information on coal cleaning methods has been
reviewed by Wheelock (1977) and by Mezey, Singh and Hissong
(1976) and by Meyers (1977). Because of the porous structure
of coal, coarse grinding (-14 +28 mesh) is sufficient to expose
the sulfur containing compounds for reaction with an oxidizing
gas and subsequent washing.
Nitrogen dioxide (N02) has a high enough oxidation potential
to oxidize inorganic and organic sulfur compounds. In the
presence of oxygen, the NO formed from the N02 is reoxidized
by oxygen. The oxidation by N02 and the reformation of NO, both
take place at atmospheric pressure and low temperatures.
Oxidation Sulfur Removal
Consider the chemical reactions:
Fe S2 + 02 ^2? Fe so^ (or Fe SQ^J + SQ (1)
N02
Fe S2 + 02 -*• FeO (Fe203) + 2S02 (2)
1147
-------
These chemical reactions describe the removal of sulfur from
pyrites. Table 1 shows test results for four coal samples which
were oxidized with oxygen, diluted with nitrogen in the presence
of N02. All four coals showed a significant reduction in sulfur
content after oxidation. No extraction or washing was employed.
The oxidations were run in a one-inch tubular reactor with
a 12-inch high static coal bed. No vibration or movement of the
bed of coal occurred. It is possible that under the test conditions
some chanelling of gas through the bed occurred and this may account
for some of the scatter of results.
In these tests total sulfur reductions of about 20 to 50 per-
cent were observed. The reductions were about 30 to 90 percent of
the pyritic sulfur content.
In these tests the oxidizing gas contained 5 to 10 percent
N02- The total quantity of NO, contacting the coal at one
atmospheric pressure varied from 1.0 to 2.5 moles N02/mole of
total sulfur. The direct sulfur removal was carried out at 93 °C
with about 1000 volumes of dry gas containing one volume of coal.
At the present time, it is not known for certain if the
oxidation reaction with N02 takes place directly with the pyritic
and organic sulfur or through the intermediate formation of nitric
acid; for example,
Pe S2 + 6N02 -* 6NO + Fe S04 + S02 (3)
NO + 1/202 -*• N02 (4)
1148
-------
Table 1. Oxidized Coal Samples.
Particle Size -14 +28 Mesh
N02/S Mole Ratio - 1 to 2.5 - Contacting the Coal
Final % Removal
Pyritic Total Sulfur of Total of Initial
Coal Sample Total and Sulfate Organic After Oxidation Initial S Pyritic S
Lower Kitan- 4.3 3.6 0.7 3.3 23 28
ning
Kansas 6,7 5.1 1.6 4.1 24 31
Crawford Co. 29
Kansas 5.3 3.8 1.5 4.3 19 26
Crawford Co. 2.7 49 68
Oklahoma 3.2 1.3 1.9 2.5 22 54
Craig Co. 2.0 38 92
1149
-------
Possible reactions
H20 + 2N02 + 1/202 5*; 2HN03 (5a)
Fe S, + 6HNO- —*> Fe S04 + S02 + 3H20 + 3NO + 3N02 (5b)
Water is required for the formation of nitric acid. The coal was
not predried and initially may have contained 1-5 percent water.
The dry gas passing over the coal would remove any water not
chemically bound. The thermodynamic data for Reaction 5a
(Forsythe, 1942) show that for a gas mixture of:
5% by volume N02
5% by volume H20
15% by volume 02
Balance N2
at atmospheric pressure and 102 °C, the equilibrium concentration
of nitric acid is 0.7% by volume. It is likely that this equilibrium
is not achieved at the KVB process conditions. The contact of N02
with the coal results in selective oxidation and the formation of
NO. The tests were run feeding NO and air which reacted to form
N02. The concentration of N02 will be considerably less than five
percent when five percent NO is fed. This would decrease the nitric
acid downstream at equilibrium. The water vapor concentration
assumes that for coal containing five percent water all the water
is vaporized during the test. This means that no aqueous phase
remains to form liquid nitric acid nor should any nitric acid
formed condense as liquid nitric acid.
1150
-------
Any nitric acid formed which oxidized the pyrites results in
the same net reaction as Reaction 3. That is, the nitric acid is
generated in situ and reacts. The N02 would then function as
indirect oxygen carrier.
Post Oxidation Water Washing to Remove Sulfur
The reaction of pyrites to sulfites or sulfates produces
water soluble iron sulfur compounds. These compounds can be
washed from the coal. Table 2 shows test results for coals which
were oxidized and subsequently washed with water.
Table 2. Oxidized and Water Washed Coal Samples.
Coal Sample
Lower Kentucky
Illinois 5
Kansas
Crawford Co.
Mounds vi lie
(W. VA)
Initial
Total
4.3
3.0
5.3
5.3
5.3
Sulfur Content % Of
Pyritic &
Sulfate
3.6
1.1
3.8
3.8
2.6
Final Total
% Removal
Sulfur After of Total
Organic
0.7
1.9
1.5
1.5
2.7
Water Wash
1.6
2.0
1.9
3.0
2.5
3.2
Initial S
63
33
37
43
53
40
of Initial
Pyritic S
75
91
100
61
74
81
P-213
Organic Sulfur Removal
Sequential oxidation and water washing reduces the sulfur con-
tent of the coal and also the iron content and the content of other
trace element species. Ash removal is likely since washing coal
generally reduces ash; however test verifications have not been made.
1151
-------
The caustic treatment is done on the partially cleaned coal to
minimize the amount of caustic used up forming iron hydroxide,
etc. It is also desirable to remove the iron salts before treating
with caustic to avoid forming gelatinous iron hydroxides in the
pores and free spaces in the coal structure as this would impede
the contact of caustic with the oxidized organic sulfur compounds.
Table 3 shows the results of tests which after oxidation and
water washing the coal was treated with a caustic wash for one
hour at 93 °C. The final sulfur content was below the initial
organic sulfur content for these samples.
To eliminate the possibility that sampling errors might have
resulted in these low organic sulfur analysis results, additional
tests were run using coal which was made pyrite-free by treatment
with nitric acid. This treatment applied the pyritic coal analysis
procedure, ASTM D2492, (i.e., the coal was boiled in 12% HN03 for
thirty minutes, filtered and washed six times with 12% HN03) to a
large sample of coal to prepare the sample for N02 oxidation. In
these tests (Table 3) the sulfur content was reduced indicating
that the organic sulfur was indeed being removed from the coal.
Organic Sulfur Removal Chemistry
Using N02 as an oxygen carrier for the selective oxidation of
sulfur compounds in coal provides a strong oxidant and permits the
reactions to be carried out at ambient conditions. It is possible
to oxidize the sulfur compounds selectively. It is also possible
1152
-------
Table 3. Oxidized Water Washed and Caustic Washed Coal Samples.
Coal Sample
Initial Sulfur Content
& Pyrite
Total Sulfate Organic
% Removal
of Total of Organic
Final Sulfur Sulfur Sulfur
Lower Kittaning
Illinois 5
4.3
3.0
3.0
3.6
1.1
1.1
0.7
1.9
1.9
0.5
1.0
1.2
8B
67
60
29
47
37
Moundsville
(W. VA)*
2.8
2.8
1.6'
43
43
* Sample was pretreated to remove pyrites. Initially this sample analyzed 5.3%
total sulfur, 2.6% pyritic (and sulfates) 3.2% organic
After oxidation and caustic treatment
P-213
to cause non-selective reactions to occur. Depending on the
temperature, pressure and concentration, NO, can:
. react selectively to oxidize sulfur compounds
react with coal to form easily decomposed nitrogen-
containing compounds
. react with coal to form stable nitrogen-containing
compounds
react to oxidize coal
The pyrite oxidation reactions were discussed above. Suffice it
to say that if inorganic nitrates are formed along with inorganic
sulfates, they are water soluble. The selective oxidation of
organic sulfur compounds is widely in the literature. KVB has
patented a process using oxygen containing gases containing low
quantities of nitrogen oxides to oxidize the sulfur compounds in
petroleum fractions and subsequently separate the oxidized sulfur
1153
-------
compounds by methanol extraction (Guth, 1974). Typical results
for desulfurizing fuel oils are given in Table 4. In these tests
the oil was oxidized at atmospheric pressure and 25 to 65 °C. The
oxidized oil was allowed to degas for one hour. The oil insoluble
fraction separated and was further degased after 10 minutes at
150 °C. The oxidized degassed oil was extracted with methanol to
separate to low sulfur fraction as the raffinate and the high
sulfur oil as the extract.
These data are presented to indicate that the various types
of organic sulfur compounds in oil fractions can be oxidized with
NO- in the presence of oxygen without forming stable nitrogen
containing compounds. Nitrogen compounds along with sulfur com-
pounds are oxidized and extracted. Methanol extraction of unoxidized
oil does not separate any significant fractions of the sulfur and
nitrogen.
Model sulfur compounds have been oxidized to sulfones and
sulfoxides by N02 in the presence of air. Typical of the compounds
are dihexyldisulfide, benzylphenylsulfide and dibenzyldisulfide
by KVB and dibenzothiophene by the Bureau of Mines (Friedman, 1977} .
Both aliphatic and aromatic sulfur compounds are oxidized without
nitration.
Coal oxidation may be accompanied by nitrogen dioxide absorp-
tion under some conditions. It may be necessary to predry the
coal to eliminate a water phase or to post heat the coal to decompose
unstable nitrogen compounds to reduce the abosrbed NO, content.
1154
-------
Table 4. Organic Sulfur Compound Oxidation in Petroleum Fractions,
Low Sulfur High Sulfur Oil Insoluble
Initial % Of % Of % Of
Feed %S %N Feed %S %N* Feed %S %N* Feed %S %N
Turbine fuel 0.15 0.03 85 0.06 0.01 14.5 0.66 0.26 0.5 0.3 0.5
API6
Diesel oil 1.1 0.19 85 0.1 0.08 14 7.0 0.8 1.0 5.0 0.5
APIG 34
Atmospheric 1.7 0.25 80 0.3 0.12 19 7.5 0.'8 1.0 5.0 0,5
gas oil
APIG 28
Shale oil 0.6 1.6 85 0.4 0.3 14 1.7 9.0 1.0 0.8 1.5
APIG 30
* After degassing one hour at 30 °C
After degassing 10 minutes at 150 °C
P-213
1155
-------
In coal desulfurization to remove organic sulfur, it is not
possible selectively to dissolve and separate the oxidized sulfur
compounds; however, the oxidized sulfur compounds can be hydrolyzed.
The caustic treatment hydrolyzes the oxidized organic sulfur com-
pounds in coal converting the sulfur to inorganic forms thereby
allowing the sulfur to be spearated by extractions.
The question of NO, reacting nonselectively with coal has not
been answered. More laboratory work is required. If NO- reacts
with coal in a manner similar to the reactions with oils, any N02
reacting with the coal will be readily removed by heating and the
NO recovered for reuse. If N02 reacts with coal to form more stable
compounds, then reaction conditions must be used to minimize the
nonselective N02 reaction and thereby minimize any contribution
to flue gas NOx on combustion of the coal.
Process Cost Estimate
KVB's process has the following operations:
Preparation of the feed - white rock removed and coal
crushed to -14 +28 mesh size
Oxidation - the dry crushed coal is reacted at one
atmosphere and 100 °C with a gas stream containing
nitrogen dioxide and oxygen
Water washing - the oxidized pyritic sulfur is removed
fromthe coal by a water wash at one atmosphere pressure
and 100 °C
Caustic washing - about 40% of the organic sulfur is
removed by a caustic washing at one atmosphere pressure
and 100 CC
1156
-------
. Pelletizing - about 30% to 35% of the feed coal is less
than 28 mesh size and is balled on a disc and dried on
a traveling grate prior to shipment. The remainder of
the coal can be shipped as-is.
. Wash solvent treating - the process wastes, calcium
sulfate and sodium jerosite (sodium, iron, sulfate
compound) are chemically separated from the water
solvents
There are at this time uncertainties regarding the chemical
usage and process equipment requirements. However, KVB has made
a preliminary R.O.M. cost estimate.
KVB used the Bechtel study comparing chemical coal cleaning
processes (Oder, 1977) as a basis for an updated cost estimate.
The Bechtel study showed that KVB was comparable in cost to other
processes under consideration. Cost reduction in KVB's analysis
resulted mainly using a coarser grind coal. The KVB estimate was
made of the cost of operating an 8,000 ton/day coal treatment plant
based on the schematic shown in Figure 2. The major cost reductions
were in coal grinding, compaction and energy to dry coal in the pro-
cesses. The capital cost estimate was arrived at by estimating
equipment costs and applying a factor to obtain installed equipment
costs. The factor of 4 used by KVB is believed to be conservative.
A 30% contingency was added due to the uncertainty of the estimate.
The capital cost was estimated to be $29,000,000 as shown in Table
5, and the total cost per ton of feed was $8.50 as shown in Table 6.
Both the capital cost and the operating cost are R.O.M. estimates
based on the current understanding of the process.
1157
-------
Feed,
High Sulfur
Coal
Pulverizer
80 -F, 1 atm
Pulverized Coal
(-14 +28)
Reactor
200 »F
1 atmosphere
1/2 hour contact time
I
-------
Table 5. Capital Cost Estimate for KVB Coal
Desulfurization Process for 8,000 ton/day Feed
(Lump Coal)
Equipment MM$
1. Feed storage and handling, grinding and 1.30
product palletizing
2. Reactor and oxidizing gas loop 1.3
3. Water wash use and reclaiming 0.7
4. Caustic use and reclaiming 0.7
5. Dryer for coal 0.75
6. Solids preparation for disposal 0.10
Total Equipment 4.85
X Factor for Installed Equipment (X4) 19.4
Contractor's Fee 2.9
22.3
Contingency at 30% 6.7
Total Capital Cost 29.0
P-213
1159
-------
Table 6. Processing Cost Estimate for
KVB Coal Desulfurization Process
Feed Rate - 8,000 Tons/Day, 330 days, 2.6 MM Tons/Year
Capital Investment, Million $ 29 0
Operating Costs MM$/Yr
Direct Costs
NO2 at $200/ton ^ 6
Oxygen at $30/ton 2*i
Caustic at $300/ton ^' ~
Lime at $30/ton 0° ±
Utilities (energy, water) 7 Q
Labor (5 men/shift) 0"5
Maintenance, 5% of capital ^'.
Total Direct
Indirect Costs
Taxes and insurance (1.8% capital); supervision
(2.0% of labor); benefits (30% of labor plus
supervision); plant overhead (50% of labor plus
supervision)
Total Indirect
Corporate G&A (10% of direct cost plus indirect)
Total Operating Cost
Amortization, 0.17 x capital (15% ROI,
15-year life, 52% income tax rate)
Total Expense
TOTAL COST/TON OF FEED*
*Feed Coal: Product Coal:
Sulfur, 1.9% Sulfur, 0.5%
Pyritic, 1.2%
Organic, 0.7%
P-213
1160
-------
KVB feels that the estimated processing cost of $8 to $9/ton
is representative of the process as is known today.
The costs of the operations are roughly as follows:
Storage, grinding, pelletizing 1.50
Oxidation 3.00
Water wash 1.50
Caustic wash 2.50
8.50/ton
Operating with only one or two of the desulfurization modes
of KVB's process would result in lower costs.
Oxidation only of previously ground coal is estimated to
cost $3.00-$4.00/ton.
Oxidation and caustic washing for organic sulfur removal of
a low pyrite coal is estimated to cost about $6.00 to $7.00/ton.
REMARKS
The United States' largest energy resource is coal. The
ability efficiently to utilize this source of energy is vital to
the nation's technological progress, economic well-being, and,
perhaps, national defense. This is highlighted by our well-
publicized dependence on imported oil. Unfortunately, the use of
coal as a fuel is less desirable from an environmental standpoint
than gas or oil. Emissions of sulfur oxides, nitrogen oxides, and
particulate matter are more difficult to control.
1161
-------
The KVB process has the potential of an economic chemical
coal cleaning process. It is an atmospheric pressure, ambient
temperature process which results in low capital cost. The feed
does not have to be pulverized (+28 mesh has typically been used).
The chemicals used are oxygen and nitrogen dioxide which are
relatively low cost. Of particular importance is the removal of
a portion of the organic sulfur content in addition to essentially
all pyritic sulfur. Washing of coal to remove pyrites by physical
separation is feasible but requires pulverized coal (as fine as
200 mesh), results in incomplete separation, and removes no organic
sulfur. Substantial reductions in the cost of scrubbing can be
achieved by using cleaned coal.
KVB has demonstrated the technical feasibility of the process
for removal of sulfur from several coal samples. Preliminary
estimates have been made of the cost of treating coal and they
compared favorably with competing processes. Additional experi-
mental work must be done to further the process development and
provide a basis for a laboratory plant design (about 100 Ib/day
capacity). Questions regarding N02 uptake by the coal and the
application to coals previously physically cleaned to remove
pyrites must be answered.
1162
-------
This presentation described three sulfur removal modes
associated with KVB's chemical coal cleaning method:
gas phase - on oxidation
water phase - washing the oxidized coal
. caustic phase - treating the water washed oxidized coal
for organic sulfur removal
The test data are not extensive or complete; however, they do
indicate that the chemical basis of this technology is sound.
Further development will be aimed at expanding the data base,
refining the cost estimate and lowering the cost. Applications
to coals previously cleaned by physical methods will be investigated.
This method can be a practical means for low cost chemical
coal cleaning.
1163
-------
REFERENCES
Forsythe, W. R. and Gianque, W. F., J. Am. Chem. Soc. 64 (481
1942. — ^ ' '
Friedman, S., Lacount, R. B. and Warzinski, R. p., Coal
desulfurization chemical and physical methods. American
Chemical Society, Washington, D.C. page 166. 1977
Guth, E. D. and Diaz, A. F., U.S. Patent 3,847,800. 1974.
Meyers, R. A., Coal desulfurization. Marcel Dekher inc
New York, 1977.
Mezey, E. J., et al., Fuel Contaminants: Volume 2, removal
technology evaluation. EPA 600/2-76-1776. September 1976
Oder, R. R., et al. Technical and cost comparisons for chemical
coal cleaning. Paper presented at the Coal Convention
American Mining Congress. Pittsburgh, PA. May 1977. '
U.S. Patents on select sulfur oxidation with NO.,, 2 489 316-
2,489,318; 2,285,744; 2,825,745; 2,581,050? ' '
Wheelock, T. D., ed. Coal desulfurization chemical and physical
methods. American Chemical Society. Washington, D.c.
x y / / •
1164
-------
THE DRY REMOVAL OF PYRITE AND ASH FROM COAL
BY THE MAGNEX PROCESS COAL PROPERTIES AND PROCESS VARIABLES
James K. Kindig and Duane N. Goens
Hazen Research, Inc.
Golden, Colorado
ABSTRACT
The Magnex process is a dry method for removing pyrite and other ash-
forming minerals (ash) from coal. The process works because of the action
of a chemical vapor which increases the magnetic susceptibilities of pyrite
and ash but not the associated coal. As a result, pyrite and ash can be
removed from coal by conventional magnetic separators.
Conventional coal cleaning processes are limited (dependent upon) the
specific gravity distribution of the coal which, in turn, is dependent upon
the naturally occurring, sometimes intimate, mixtures of coal, ash, and
pyrite. In like manner, high gradient magnetic separators are limited by
fixed magnetic susceptibilities of the component assemblages. In contrast,
Magnex, an applied chemical process, permits the adjustment of the magnetic
susceptibility of refuse components independent of the coal and independent
of the way nature assembled them.
Recent detailed studies of the Magnex process variables and coal properties
are permitting us to take advantage of the selectivity of the process. In
this regard, six coals are discussed. The effects of pretreatment and carbonyl
treatment variables on pyrite and ash removal efficiencies illustrate the
range of control that is possible over the magnetic susceptibility enhancement
reactions. Also, examples are given of the "best path" approach which leads
to clean coal results equivalent to perfect gravity cleaning. Future plans for
Magnex are discussed.
1165
-------
INTRODUCTION
There exists today, a time of importance in achieving both energy and
environmental goals, a great need for an efficient and inexpensive process for
removing pyrite and ash from fine coal. The Magnex process, a novel method
for fine coal cleaning, is a candidate to fulfill that need. This paper reviews
the current status of the process and its commercialization. Also, it describes
current progress in a study undertaken with several coals to acquire a better
understanding of the interaction between properties of the feed coal and the
process, and the relationship between the process variables and effective
coal cleaning.
Nedlog Technology Group, Arvada, Colorado, holds the worldwide
licensing rights to the Magnex process, and they are sponsoring the research
and development work at Hazen Research, Inc. Grateful acknowledgment is
extended to them for their sponsorship and this opportunity to review some
aspects of the work.
PROCESS REVIEW
There are four main steps in the Magnex process;
1. CRUSHING: To achieve liberation of pyrite and ash form-
ing minerals (ash); it usually is necessary to comminute
to about 14-mesh.
1166
-------
2. HEATING: In this step the temperature of the feed coal is
elevated to about 170°C. In addition to being a heating
step, preconditioning takes place which makes the car-
bonyl treatment more selective.
3. CARBONYL TREATMENT: The iron carbonyl treatment pro-
vides the magnetic enhancement of the pyrite and the ash-
forming minerals.
4. MAGNETIC SEPARATION: Pyrite and ash-forming minerals
are removed by medium intensity magnets as a magnetic
refuse while the nonmagnetic portion is a clean dry coal.
The chemistry of the Magnex process is summarized with three equa-
tions:
Fe(CO)5
Iron
penta carbonyl
Fe°
Don
SCO
Carbon
monoxide
Fe(CO)s
Iron
penta carbonyl
+ Ash
minerals
Fe°-Ash
Crystallites of
Iron on ash.
minerals
+ SCO
Carbon
monoxide
-------
and release carbon monoxide. The third equation describes what happens to
the pyrite. It reacts with iron pentacarbonyl to form a pyrrhotite-like material
and carbon monoxide. The iron carbonyl does not react with the coal to form
a magnetic species under selected operating conditions. After treatment, there
are ferromagnetic iron crystallites on the ash, and on the surface of pyrite
a pyrrhotite-like conversion which has a quite large magnetic susceptibility.
Both can easily be removed by magnetic separators. In summary, the
process works because iron carbonyl selectively decomposes on the ash and
reacts with pyrite but will not produce any significant deposit of iron on the
surface of the coal.
Figure I is a photomicrograph of a piece of pyrite which was carbonyl
treated. This particle is about 65-mesh, and the formation of the pyrrhotite-
like material can be seen on periphery and in the cracks, the lighter, brighter
material being the original unconverted pyrite. Only a slight conversion of
pyrite to pyrrhotite-like material or only a slight deposition of iron on the ash
is required to permit the particles to be magnetically drawn into the refuse.
Photomicrographs of a feed coal, clean coal, and refuse from a typical Magnex
separation are shown in Figures 2,3, and 4.
1168
-------
Photomicrograph of pyrite after treatment with iron carbonyl 275X
Figure 1
Untreated feed coal. Minus 65-mesh 200X
Figure 2
1169
-------
Nonmagnetic clean coal. Minus 65-mesh 200X
Figure 3
Magnetic refuse. Minus 65-mesh 90X
Figure 4
1170
-------
The Magnex process was invented at Hazen Research in 1975. Since
that time there have been numerous bench scale studies of the process.
Magnex processing involves pretreatment and carbonyl treatment of crushed
coal. The pretreatment and carbonyl treatment are done in a rotating glass
reactor; the magnetic separations are made on a laboratory crossbelt separa-
tor. In addition to the supporting analytical work, other tests were performed
to determine the process mechanisms and to improve the selectivity.
Based upon the successful laboratory development program and a
favorable economic study, a 200 Ib/hr pilot plant was designed and con-
structed to test the process on a continuous basis. A feed coal for the pilot
plant was obtained from the Allegheny Group coals and crushed to 14-mesh.
The coal was pretreated, iron carbonyl treated, and magnetically separated;
crushing and magnetic separation were not continous with pretreatment and
carbonyl treatment. Crushing was accomplished with a jaw and impactor
crushers. Indirect heating, and pretreatment with steam at atmospheric pres-
sure were done while the coal passed through a screw conveyor. Carbonyl
treatment was accomplished in a shaft furnace with a very slow co-current
flow of iron carbonyl gas, also at atmospheric pressure. Magnetic separa-
tion was completed with a commercially available induced magnetic roll
separator. These pieces of equipment were a convenience for pilot plant
operation and are not necessarily the ones which would be used in a larger
installation.
The pilot plant was operated continuously during five campaigns; each
1171
-------
campaign lasted from four to six days. Coal processed continuously through
the pilot plant behaved as expected from laboratory tests on the same coal.
Samples from the pilot plant operation met the EPA limits for SO2 emissions from
new sources, 1.2 pounds/million Btu. Data showing the quality of clean coal
in comparison to feed coal are given in Table 1.
Table 1
Comparison of Feed and Clean Coal:
Pilot Plant Results
Clean coal
Feed coal
Pyritic Total
Yield Ash, Sulfur, Sulfur,
Weight % % % %
82.3 14.8 0.07 0.73
100.0 18.1 0.62 1.22
Calorific
Value ,
Btu/lb
12,520
11,981
Pounds of
Sulfur/
MM Btu
1.17
2.03
An economic study based upon data obtained from the pilot plant
showed that the operating cost was about equal to the cost of cleaning fine
coal in existing coal preparation circuits.
Current plans and activities include:
1. Intensive studies on iron carbonyl generation. This work
has been most successful and is now in the pilot plant
stage.
2. Intensive search for alternate magnetic separators to
separate large volumes of dry solids efficiently and
inexpensively. This work is just under way.
3. Operate the pilot plant again, but with the coal selected
for the demonstration plant. Provide support for the
design engineers.
4. Design a coal preparation flowsheet which employs the
best blend of the advantages of conventional coal pro-
cessing and the Magnex technology.
1172
-------
5. Improve the scope and efficiency of the process and reduce
the cost.
6. Proceed to a demonstration plant, about 60 TPH.
This completes the process review and status; following are two
studies or evaluations dealing with the effect of the coal properties on Magnex
beneficiation, and the relationship between process variables and Magnex
beneficiation.
EFFECT OF COAL PROPERTIES ON
MAGNEX BENEFICIATION OF COAL
When cleaning coal of a given size range with any gravity separator
(jig, table, heavy media, etc.), it is the specific gravity of the coal, ash, and
pyrite particles, whether free or locked, which determine the kind of separation
obtained. This specific gravity distribution is not subject to human control.
Likewise, a magnetic (HGMS) separation of raw coal (no Magnex treatment)
is dependent upon the relative naturally occurring magnetic susceptibility of
the various particles and also is not subject to human control. In contrast,
the Magnex process permits the controlled enhancement of the magnetic sus-
ceptibility of particles containing ash or pyrite while not affecting particles
of clean coal. This selectivity, the ability to enhance magnetic susceptibility
of refuse but not coal, is the great opportunity and challenge of the Magnex
process.
1173
-------
COAL CHARACTERISTICS
During the development of the Magnex process, numerous coals were
tested for their amenability to the process. These tests were done in the
laboratory on a batch basis; however, many results have shown the good agree-
ment between laboratory and pilot plant results. Coals from several localities
were tested. These coals differed considerably in their responsiveness to
carbonyl treatment and were included in this study for that reason. Of course,
differences should be expected because of the highly variable nature of coal
and associated minerals,
An intensive study was mounted on seven coals which varied in their
response to the process. The purpose of the study, which is still in progress,
is to learn which properties of coal influence the process and to determine how
process variables could be changed to bring about improved results. The coals
considered are listed in Table 2.
Table 2
HRI Number
11986-1
12683
11986-2
11089
7265
6776-1
6145
Identification of Coal Samples
Seam
Lower Freeport No. 6A
Pittsburgh No. 8
Pittsburgh No. 8
Allegheny Group Coals
Illinois No. 6
Lower Freeport
Lower Freeport
State
Ohio
West Virginia
Ohio
Pennsylvania
Illinois
Pennsylvania
Pennsylvania
1174
-------
Each of these coals was tested for those coal properties which were
thought might be related to its response to the process. A listing of these
coal properties is given in Table 3. The last five analyses included in the list
are tests which are not ordinarily determined in coal. They are included
because study and correlation of the previous test work has suggested a
relation between them and the process.
Table 3
Feed Coal Properties
Ash
Pyritic sulfur
Organic sulfur
Total sulfur
Calorific value
Sink float tests
Low temperature volatiles
Tendency to produce acid
Heavy metal analysis
Pyrite size
Elemental sulfur
BENEFICIATION TESTS BY THE MAGNEX PROCESS
Each of the seven coals was then beneficiated by the Magnex pro-
cess. This involved crushing, and magnetically separating the treated
material to produce a clean coal and refuse. The clean coal, refuse, and
feed were then analyzed for ash, forms of sulfur, and calorific value (Btu/lb)
These data and other analyses performed on the feed coal appear in Table 4.
1175
-------
Tablo4
Analyses of Food, Clean Coal, and Solatia lot Seven Minus 14-mooh
_£QalgBGnQflcIated bv tho Maflnon
Sample Identification
Lower Freepon No. 6A
Ohio
HRI 11986-1
Pittoburgh No. 6
West Virginia
HRI 12683
Pittsburgh No. 8
Ohio
HRI 11986-2
Allegheny Group Coals
Pennsylvania
HRI 11039
minols No. 6
nllnols
HRI 7265
Lower Prooport
Pennsylvania
HRI 6776-1
Lower Freeport
Pennsylvania
HRI 6145
^ Btu/SO2 Index (Bj)
£/ Percent theoretical
D. theoretical aooui
GT^aillC IDfltTTTlfll .
3/ Percent of Darfoct.g
Yield,
Weight
Clean coal 74.5
Refuse 25.5
Feed
Clean coal 83.7
Refuse 16.3
Feed
Clean coal 84.4
Refuse 15.6
Feed
Clean coal 66.6
Refuse 13.4
Feed
Clean coal 79.4
Refuse 20.6
Feed
Clean coal 89.2
Refuse 10.8
Feed
Clean coal 72.7
Refuse 27.3
Feed
Bfu recovery
Pyrttlc Organic
Sulfur, Sulfur*
18.4 0.69
76.8 7.08
34.3 2.32
21.0 1.24
60.7 9.46
27.5 2.38
26.0 1.52
61.0 10.8
33.3 2.76
16.3 0.07
38.5 4.32
19.7 0.64
12.9 0.94
59.6 S.4S
25.5 1.87
23.9 0.57
' 62.9 11.2
27.9 1.72
9.4 0.33
73.6 6.19
25.7 1.93
Sulfur-to-Btu ratio
claanln,, (PTC! «. B, feed - B, clcon coal
0.70
0.66
2.34
2.26
1.63
1.36
0.65
0.66
3.34
3.01
0.51
0.66
O.S5
O.S8
n 100
Total
Sulfur,
1.39
6.97
. 2.98
3.58
8.89
4.64
3.15
11.3
4.32
0.72
4.24
1.30
4.28
5.69
4.33
1.06
13.0
2.38
0.88
7.28
2.51
B. feed ~ B_ theoretical
DOS comploto pyrlto and aoh raaoval but no Btu loco from
ravlty cleaning, tha ratio of aoh or pvxltlo oulfur mmnvod by
Calorific
Value, Ash.
Btu/lb X
11.953
2.326 53.6
9.320
11.605
4.037 36.0
10.505
10,644
3,446 32.9
9,433
12,178
3,517 26.8
11.616
11,891
4.818 54.5
9.977
11,419
4.498 24.2
10,707
13,970
2.980 74.7
11.S04
Reloction
Pyrttlc Total Btu
Sulfur. Sulfur. Recovery.
XXX
95.5
77.8 63.2
92.5
59.8 32.6
95.2
56.9 39.9
90.6
90.5 47.7
94.6
60.0 25.6
95.1
70.3 59.3
88.3
67.6 75.7
Sulfur
OKldes.
Pounds/
1068tu
2.32
6.39
6.16
5.82
5.92
9.15
1.18
2.24
7.19
9.77
1.69
4.44
1.26
4.36
Btu/BO.
41.2
15.6
15.0
11.3
16.1
10.9
76.9
44.6
13.2
10.2
50.4
22.5
70.2
22.9
Ponont of
2/ Perfect
Percent Gravity '
Thoor. Cleaning,
Clean- PyrtUo
^ Ash Sulfur
47 68 221
27 52 272
22 49 157
75 -37 117
46 76 72
48 40 136
63 -
LowV ItetS/
Fompoxatuio Add
Arbitrary tlon Zinc. Copper.
Units X SO^" ppm ppm
92.0 0.63 100 5
303.6 0.194
116.5 0.330 53 17
12.7 0.182 140 13
86.0 O.S9 90 53
19.0 - 61 17
9.S - 46 17 •
Weight
Mean
Pyrtto
Micron
556
619
405
419
641
S13
4/ Low tamporaturd volatilos , quantity of gao given off by fronting tho coal to 200°C for ftvo
mlnutoo. Qouosocd In arbltfery units.
S/ Net add production, amount of add found by sparging' oxygon through a coal-cater oluny
at 7S°C for 24 hours loss tho amount of add resulting from oparglng with nltrogon.
Ejtulusoed in porcont 8Od°>
•Jie process to tho aoh or pyrttlc oulfur laiuuvcJ by olni-Ooat at the oame yield
times 100.
-------
To Judge the effectiveness of the separations , several criteria derived
from the analytical data are useful. For steam coals, it is desirable to maxi-
mize Btu recovery and minimize the sulfur- to-Btu ratio; for this reason "Btu
recovery" and "pounds of sulfur oxides per million Btu" are calculated.
Btu/SC>2 Index (B_) is a combination of Btu recovery and sulfur-to-Btu ratio;
it is defined as follows:
Btu/S02 Index 2 per million Btu contained in the feed. Clean coal has lower
Btu recovery but also lower SO2 values. High B, values are desirable,
reflecting good Btu recovery and low sulfur-to-Btu ratio.
For comparisons between coals, the B value is used to develop the
percent of theoretical cleaning (PTC). It is calculated as follows:
B feed - B clean coal
PTC = — - - l -
B feed - B theoretical
Bj theoretical is the calculated value for complete ash and pyrite removal
with no loss of Btu from loss of organic material.
In addition to the above, an efficiency measure is needed which con-
siders the cleaning achieved relative to that theoretically attainable by sink-
float methods. The ash error (difference in sink-float and clean coal ash at
the same yield) and the Frasier-Yancy or organic efficiency (relationship of
yield of clean coal relative to yield of sink-float coal at the same ash value)
1177
-------
are two such measures. A similar criterion used in this work is the "Percent
of Perfect Gravity Cleaning;" it is the ratio of ash or pyritic sulfur removed by
the process to the ash or pyritic sulfur which is removed by sink-float at the
same yield.
CORRELATION STUDY
Having described some of the criteria for judging the effectiveness of
the separation, the data of Table 4 can be reviewed for trends. A complete
correlation study was made on all of the data by developing the simple cor-
relation coefficients for each data pair. Selected correlations are shown in
Table 5. The significance and utility of the correlations for understanding
and controlling the process are now being evaluated. The correlation study
supports the following statement. A high quality Magnex separation is
associated with the following properties of the feed coal:
1. Small amount of low temperature volatiles.
2. A tendency to produce acid.
3. Lower levels of copper and perhaps higher levels of
zinc.
4. Lower pyrite and organic sulfur content.
This information, and other information expected when the correlation study
is completed can be used to improve the process, to characterize feed coals,
or to lead to an understanding of the process mechanism.
1178
-------
Correlation of Feed Coal Properties with the
Results of Magnex Cleaning
(Numbers are the simple correlation coefficients, r)
Low Temperature Volatlles In the Feed Coal (7 Coals Correlated, r >0.6
0.71+ Pyrltlo sulfur in the clean coal
0.67+ Total sulfur in the clean coal
0.69+ Pounds of SO2/MM Btu In the clean coal
0.65- Pyrite rejection
0 . 74- Percent theoretical cleaning £/
Net Acid Production of the Feed Coal (5 Coals Correlated, r >0.5
0.84+ Organic sulfur in the clean coal
0.75+ Total sulfur in the clean coal
0 . 74+ Pounds of SO2/MM Btu In the clean coal
0.5S- Pyrite rejection
0.82- Total sulfur rejection
Zinc in Feed Coal (6 Coals Correlated , r >0 . 5
0.54- Pyritic aulfur In the clean coal
0.75- Ash in the refuse
0,55- Pyritic sulfur in the refuse
O.S8- Total sulfur in the refuse
0 . 75+ Btu in the refuse
0.58+ Percent theoretical cleaning
Copper in Feed Coal (6 Coals Correlated, r >0.5)
0.91+ Organic sulfur in the clean coal
0.79+ Total sulfur in the clean coal
0.74+ Pounds of SO2/MM Btu in the clean coal
0.53- Pyritic sulfur rejection
0.71- Total sulfur rejection
Pvrltic Sulfur in the Feed Coal (7 Coals Correlated, r >0.6)
0.88+ Pyritic sulfur in the clean coal
0.74+ Ash in the refuse
0.65+ Pyritic sulfur in the refuse
0.82- Btu in the refuse
0.71- Btu rejection
0.91- Percent theoretical cleaning
Organic Sulfur in the Feed Coal (7 Coals Correlated, r >0.6
0.73- Pyritic sulfur re] ectlon
0.87- Total sulfur rejection
I/ Low temperature volatlles , quantity of gas driven off of the coal
at 200°C in five minutes.
2/ Net acid production, amount of acid formed by oxygen sparging a
coal-water slurry at 7S°C for 24 hours less the amount of acid
resulting from sparging with nitrogen.
3/ Percent of theoretical cleaning is the difference between the ratio
of Btu recovery to pounds of SOj per million Btu in the feed minus
that ratio in the clean coal, divided by the difference between
that ratio In the feed and that ratio in a theoretically perfectly
cleaned coal , complete recovery of organic Btu and complete
rejection of pyrite and ash. See text, page 13.
1179
-------
For the Magnex test on the Lower Freeport No. 6A coal (HRI 11986-1),
221% more pyritlc sulfur was removed than could have been removed by perfect
gravity cleaning at the same coal yield; however, only 68% as much ash was
removed as could have been removed by sink-float. This shows the extreme
selectivity of the Magnex process for removing pyrite. Greater than 100% of
perfect gravity cleaning is possible because the Magnex process cleans coal
on the basis of the magnetic susceptibility of the refuse rather than its specific
gravity. For example, a locked coal-pyrite grain which floats could be pulled
into the refuse by the Magnex process or a piece of bony coal which sinks
might be left in the Magnex clean coal.
THE RELATIONSHIP BETWEEN PROCESS
VARIABLES AND MAGNEX BENEFICIATION
In each of the four steps of the Magnex process there are several con-
trolling variables. A listing of some of these is given in Table 6. The study
of these variables Is by no means complete; in fact, for some of the steps
(crushing and magnetic separation) it has just begun,
PYRITE SIZE DISTRIBUTION
Most of the development work on this process used coal crushed to
14-mesh. This size was chosen because it gave substantial liberation of
pyrite as Judged from examination of polished sections. An objective measure
of pyrite size distribution was desired to determine if there was a correlation
between pyrite particle size and pyrite removal.
1180
-------
Table 6
Selected Process Variables
Crushing:
Top size
Size consist
Pre treatment:
Time
Temperature
Atmosphere (steam)
Iron carbonyl treatment:
Time
Temperature
Iron carbonyl concentration
Cotreatment with other gases
Magnetic separation:
Type of separator
Field strength
Gradient
The size determination was made by examining numerous polished
sections of coal. For each coal, 1,500 pyrite grains larger than 5 microns
were measured. The measurements were carried out by subjecting the high
optical quality polished sections to automatic image analysis. The analysis
used a television scanner connected to a microscope. Based on its reflec-
tivity/only pyrite grains were measured, and measurements, area and shape,
were processed by a Quantimet 720 image analysis computer. The weight dis-
tribution was calculated from an area measurement of each grain.
1181
-------
Table 7 shows the weight mean diameter of pyrite (50% by weight of
the pyrite has smaller, or larger, diameters) and the frequency mean diameter
of pyrite (50% of the grains have smaller, or larger diameters). Additionally,
the table shows the weight distribution of coal between 5, 25, 50 microns,
and greater. Considering the small percentages of pyrite in the ranges 5-25,
25-50, and 50-100 microns and the mean pyrite size, which ranges from
about 490 to 640 microns, removal of the coarse pyrite becomes extremely
important. Regarding the finest pyrite grains, even if none of these were
removed, they would make only a minor contribution to the sulfur content of
the clean coal.
CARBONYL TREATMENT
For the carbonyl treatment, the variables time, temperature, and
amount of iron carbonyl have to be fixed such that the desired result is
obtained. Also, the carbonyl treatment can be applied to a coal which either
has or has not been pretreated. A half-replicate 24 factorial experiment was
conducted with the Lower Freeport No. 6A, Ohio, HRI 11986-1, coal to test
the effect of pretreatment and the three named variables. (A portion of this
work was sponsored by the Ohio Department of Energy, Grant No. 77-10).
The amount and quality of the clean coal provided the bases for judg-
ing the effectiveness of the separation. Specifically, the responses evaluated
for the clean coal were:
Measured responses:
Yield
Ash
Pyritic sulfur
Calorific value
1182
-------
Table 7
oo
U>
Data on the Size Analysis of Pyrlte In Coal
(Coal crushed to minus 14-mesh)
Coal Identification
HRI Number
11986-1
12683
11966-2
11089
7265
6145
Seam
Lower Free port No. 6A
Pittsburgh No. 8
Pittsburgh No. 8
Allegheny Group coals
Illinois No. 6
Lower Free port
State
Ohio
West Virginia
Ohib
Pennsylvania
nilnols
Pennsylvania
Weight I/
Mean Diameter
of Pyrlte ,
Micron
556
619
505
491
641
513
Frequency 2/
Mean Diameter
of Pyrite,
Micron
21
16
22
24
20
26
Size Distribution in Percent
Weight Basis
5-2S
Micron
0.3
0.3
0.4
0.8
0.2
0.3
25-50
Micron
0.8
0.8
1.4
3.1
0.5
1.2
50-100
Micron
2.0
1.4
3.7
8.8
1.4
3.5
>100
Micron
96.9
97.5
94.5
87.3
97.9
95.0
I/ Fifty percent of the weight of pyrite Is smaller or larger than the diameter shown.
2/ Fifty percent of the pyrite grains have diameters smaller (or larger) than the diameter shown.
-------
Calculated responses:
Btu recovery
Sulfur-to-Btu ratio
Btu/SO2 index (Bj)
The range of the Btu/SO,, Index (BT) for the Lower Freeport No. 6A,
^ 1
Ohio, HRI 11986-1, coal is from 15.6, the value for the feed coal, to 69.2,
the theoretical maximum B value attained by 100% pyrite removal with no loss
of Btu from loss of any organic material. The results of the factorial experi-
ment appear in Table 8.
The effect of the carbonyl treatment variables within the ranges tested
on the amount and quality of the coal are given in Table' 9.
An analysis of the experimental data shows the direction of a "best
path" for further experimental study. The path followed, along which the Btu/
SC>2 Index is Increased, requires an additional 9.2 pounds of iron carbonyl/
ton feed for every five-degree decrease in process temperature. This
path was followed, starting at 170°C and 25 pounds Fe(CC»5/ton coal. This
starting point was the base level for temperature and dosage, which were the
most significant factors in the fractional factorial design experiment. Steam
treated coal was used as feed to the carbonyl reactor since steam pretreatment
improved the Btu/SO, Index. Treatment time was held at 60 minutes rather than
30 minutes since this longer time improved the index slightly. The experi-
mental conditions and analytical data for these "best path" tests are given in
Table 10, Figure 5 shows how the "best path" experiment leads the B value to
a maximum and pyritic sulfur to a minimOm.
1184
-------
Table 8
Clean Coal Analyses Resulting from Various Combinations of
Pretreatment and the Carbonyl Treatment
(Lower Freeport No. 6A
Pretreatment
£ No
Cn
No
No
No
Yes
Yes
Yes
Yes
Feed
I/ Duplicated
2/ Calculated
Ib Fe(CO)5/
Time , Temperature , ton
mln °c Feed Coal
30
30
60
60
30
30
60
60
150
190
150
190
150
190
150
190
"
10
40
40
10
40
10
10
40
"
to evaluate equipment change.
from Btu = 14961.8 - 162.3 (% ash)
3/ B - (% Btu recovery)/(lb SO,
/106 Btu).
' Yield oi
Clean C<
Weight
85.3
69.2
60.9
91.4
85. al/
88.3
86.2
93.2
65.1
100.0
- 32.2 (%
f
jal. Ash,
% %.
26.2
15.3
9.9
30.2
29.1
30.3
27.3
33.2
12.4
34.3
pyritic sulfur).
, Ohio, HRI 11986-1)
Clean Coal Analytical Values
Total Sulfur, Pyritic Sulfur,
2.39
2.22
1.69
3.02
1.54
1.50
2.72
2.12
1.94
2.98
1.66
1.42
0.88
2.41
0.89
0.88
2.05
1.42
1.10
2.32
Calculated
Btu/lb
10,656
12,433
13,327
9,983
10,211
10,016
10,465
9,528
12,914
9,321
IbSOz/
106
Btu
4.48
3.57
2.53
6.04
3.01
2.99
5.19
4.45
3.00
6.39
Btu
Recovery ,
97.5
92.3
87.1
97.9
94.0
94.9
96.8
95.3
90.2
• 100.0
Btu/SO2
Index (B...3/
21.8
25.9
34.4
16.2
31.2
31.7
18.7
21.4
30.1
15.6.
-------
Table 9
The Primary Effects Within the Range Tested of
Pretreatment and the Carbonyl Treatment Variables Temperature,
Time, and Amount of Iron Carbonyl on the Clean Coal
(Lower Freeport No. 6A, Ohio, HRI 11986-1)
. Desired Undesired
Increasing the Amount of Fe(CO)5 Affects
the Clean Coal
Yield, weight percent Decreases
Ash percent Decreases
Pyritic sulfur Decreases
Sulfur-to-Btu ratio Decreases
Btu recovery Decreases
Btu/SO- index Increases
Decreasing Temperature (Carbonyl Treatment)
Affects the Clean Coal
Pyritic sulfur Decreases
Sulfur-to-Btu ratio Decreases
Btu/SO2 index Increases
Increasing Time {Carbonyl Treatment) Affects
the Clean Coal
Btu recovery Decreases
Btu/SO2 index Increases
Pretreating the Coal Affects the
Clean Coal
Pyritic sulfur Decreases
Sulfur-to-Btu ratio Decreases
Btu/SC>2 index Increases
1186
-------
oo
Table 10
"Best Path* Experiment for Optimization of Magnex Response
{Lower Freeport No. 6A, Ohio, HRI 11986-1)
Temperature ,
°C
170
165
160
1S5
150
140
Feed
Ib Fe(CO)5/
ton
Feed Coal
25
34.2
43.4
52.6
61.8
80.2
-
Yield of
Clean Coal,
Weight %
80.0
80.4
86.1
82.9
86.8
89.5
100.0
Ash,
23.7
23.9
29.1
25.6
28.9
31.7
34.3
Clean
Total Sulfur,
2.08
1.92
1.50
1.46
1.40
1.41
2.98
Coal Analytical
Pyritlc Sulfur,
1.41
1.17
0.77
0.78
0.75
0.78
2.32
Values
Calculated _!/
Btu/lt>
11.070
11,045
10,214
10,782
10,248
9,792
9,321
IbSOz/
106
Btu
3.75
3.47
2.93
2.71
2.73
2.88
6.39
Btu Recovery.
95.0
95.3
94.3
95.9
95.4
94.0
100.0
Btu/SO2
Index (B , "^
25.3
27.5
32.2
35.4
34.9
32.6
15.6
I/ Calculated from Btu = 14951.8 - 162.3 (% ash) - 32.2 (% pyrltic sulfur).
2/ Bj = (% Btu recovery)/(lb SO2/106 Btu).
-------
36 r*"
-I 1.5
I 2345678
UNITS OF F«{CO)j , 9.2 Ibs/T AND TEMPERATURE, 5° C
0.6
CHANGE IN Btu/S02 INDEX (Bj) AND PYRITIC
SULFUR IN THE CLEAN COAL BY FOLLOWING
THE BEST PATH. (LOWER FREEPORT N0.6A,
OHIO, HRI 11986-1)(IRON CARBONYL INCREASED
9.2 lb*/TON FOR EACH 5*C TEMPERATURE RISE)
FIGURE 5
1188
-------
STEAM PKETREATMENT
For the pretreatment, the variables time, temperature, and the steam
atmosphere need to be fixed in order that the subsequent steps in the Magnex
process will yield the desired result. The effect of temperature and amount of
2
steam were tested in a partially replicated factorial design experiment, 3 .
Time of pretreatment was set at one hour, an arbitrary setting based upon pre-
vious work. The data generated by the experiment appear in Table 11. The
conditions employed for the carbonyl treatment were the same as those used
in the "best path" experiment which gave the best result. The responses
evaluated were the same as those considered in the carbonyl treatment evalua-
tion.
Within the limits tested, the effect of the steam pretreatment variables
on the amount and quality of the clean coal are summarized in Table 12. It is
speculated that the advantages brought about by steam pretreatment are due to
a reduction in the low temperature volatiles and, based on work not reported
in this paper, the small amount of elemental sulfur present in the feed coals.
A comparison between sink-float results and the beneficiation obtained
by Magnex is plotted in Figure 6. Three Magnex results are plotted. The first
is the preliminary amenability; the second is the result of studying the variables
affecting carbonyl treatment, the best path results; the third builds upon the
second but is enhanced by the results of studying the variables of pretreat-
ment.
1189
-------
Table II
vo
O
Clean Coal Analyses Resulting from Various Combinations
Temperature and Steam Durinn Pretreatment
(Lower Freeport No. 6A, Ohio, HRI
Temperature ,
°C
I/
I/
170
170
170
200
200
200
200
200
230
230
230
230
Feed
Steam,
Ib/ton
90
252
426
90
90
252
252
426
90
252
426
426
—
Yield of
Clean Coal
Product Weight %
Cleaned Coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
Cleaned coal
—
Calculated from Btu = 14961.8- 162.3
B = {* Btu reoovery)/ttb SO2 per 106
75.6
80.9
74.5
87.9
84.9
86.7
87.8
84.9
90.6
91.4
90.6
91.1
—
x * ash -
Btu).
11986-1)
of
Clean Coal Analytical Values
Ash,
22.4
24.5
18.4
29.5
27.6
30.3
31.0
27.5
34.8
29.9
32.2
33.5
34.3
32.2 x %
Total Sulfur, Pyritic Sulfur I/ Calculated
% % Btu/lb
1.36
1.39
1.39
1.44
1.29
1.27
1.31
1.35
1.33
1.33
1.31
1.32
2.98
pyritic sulfur.
0.74
0.76
0.69
0.82
0.69
0.68
0.77
0.71
0.75
0.76
0.75
0.79
2.32
11,303
10,961
11,953
10,148
10,460
10,023
9,906
10,476
9,290
10,085
9,712
9,500
9,321
IbSO,/
106B&
2.40
2.53
2.32
2.84
2.46
2.53
2.54
2.57
2.85
2.63
2.69
2.78
6.39
Btu Recovery
*
91.7
95.1
95.5
95.7
95.3
93.2
93.3
95. 4
90.3
98.9
94.4
92.8
100.0
Index, (Bx)
38.2
37.6
41.2
33.7
38.7
36.8
35.3
37.1
31.6
37.6
35. 1
33.4
IS. 6
-------
Table 12
The Primary Effects Within the Range Tested of
Temperature and Amount of Steam During Pretreatment
on the Clean Coal
(Lower Freeport No. 6A, Ohio, HRI 11986-1)
Desired
Unde sired
Decreasing the Temperature Affects
the Clean Coal
Yield, weight percent
Ash percent
Increasing the Amount of Steam
Affects the Clean Coal
Ash percent
Btu recovery
Decreases
Decreases
Appears to decrease
Appears to increase
1191
-------
1001-
2.20
95
o
UJ
oc
13
(-
CD
1.50
SINK FLOAT OF
MINUS 14-MESH
90
66
85
I.40O
L
. O
SINK FLOAT OF
8-INCH BY I00-MESH
1.40
JL
_L
12345
POUNDS OF SULFUR DIOXIDE PER MILLION BTU
JT) FIRST MA6NEX AMENABILITY TEST
g) CARBONYL TREATMENT VARIABLES OPTIMIZED
f?) STEAM PRETREATMENT VARIABLES OPTIMIZED
(NUMBERS BY POINTS ARE SPECIFIC GRAVITIES)
COMPARISON OF MAGNEX AND SINK FLOAT
FOR BTU RECOVERY AND SULFUR EMISSION
FIGURE 6
1192
-------
CONCLUSIONS
The Magnex process is a novel dry method for cleaning fine coal which
is projected to be cost competitive with existing processes. The Magnex
technology possesses a considerable advantage over most existing processes.
That advantage is the ability to make a coal-refuse separation by increasing
the magnetic character of the refuse components of the raw coal but not the
coal itself; this selectivity is contrasted to having to "live with" the existing
distribution of whatever property is used for making the separation. At the
present state of Magnex technology that advantage is best reflected in the
considerable selectivity of the process for pyrite, and it is likely that advan-
tage can best be exploited in conjunction with conventional coal preparation
technology.
This paper has discussed two aspects of the ongoing commercialization
effort — (1) the effect of feed properties and (2) the effect of process variables
on the Magnex process. An understanding of the interaction between feed
characteristics and the process can lead to selection of preferred feed coals,
to a better understanding of the process mechanism, and to process improve-
ments. Regarding the effect of process variables, pyrite size consist data
were given; for one (typical) coal the weight mean diameter was 556 microns.
Also shown for this same coal was the way pretreatment variables and car-
bonyl treatment variables could be adjusted to produce a clean coal with a
higher Btu recovery and lower sulfur-to-Btu ratio than could be achieved with
a perfect sink-float separation. This illustrates how an understanding of the
1193
-------
relationship between process variables and the effectiveness of the separa-
tion leads to process optimization.
A coal beneficiation process which is cost effective and produces a
sharp separation requires a thorough understanding of the interactions between
the coal characteristics and the process, and the relationship between process
variables and the cleaning efficiency. It is through the studies described in
this paper and the ongoing effort that this understanding is being won.
1194
-------
REFERENCES
Carlton, Herbert E., and Oxley, Joseph H. 1965.
Kinetics of the Heterogeneous Decomposition of
Iron Pentacarbonyl. AICHE J. 11(1), 79-84 (1&65)
1195
-------
PANEL DISCUSSION
1196
-------
PANEL DISCUSSION ON
PROPSECTS FOR CHARACTERIZATION AND REMOVAL
OF ORGANIC SULFUR FROM COAL
Preliminary Comments
by
Sidney Friedman
Pittsburgh Energy Technology Center
Pittsburgh, Pennsylvania
Until about 1970, little interest was shown in characterizing Che
organic sulfur in coal, and even less in removing it. In earlier work
done in numerous research laboratories throughout the world, sulfur
analyses were not routinely carried out or reported on products resulting
from reactions performed on coal. Coal liquefaction products seldom had
sulfur contents reported, and though someone must have determined the
sulfur content of coal acids obtained by air oxidation, I could not find
such data when I started looking for it." Here I must admit that this
data was not available even in our own laboratory. With such indifference
about coal sulfur content, it is no wonder that we know so little,about
it. We do not even have a satisfactory procedure for determining organic
sulfur in coal, although several methods are being explored. These
include such techniques as X-ray fluorescence and low-temperature ashing.
The lack of a reliable, direct determination of organic sulfur in coal
is particularly annoying in the case of treated coal, especially desulfurized
coal. In these samples, anomalous organic sulfur values are obtained
because of apparent errors in the determination of the other sulfur
forms. This may lead to erroneous conclusions. Hopefully, the aforementioned
1197
-------
new nethods for organic sulfur determinations will be developed to the
point where they can be applied satisfactorily to treated coals.
Characterization of the organic sulfur by functional group is an
equally challenging problem. Repeated attempts to determine thiol and
alkyl thioether group, in coal by classical methods have led to inconclusive
results and there is no good evidence to either accept or reject their
presence. Undoubtedly, both such groups exist in coal, but as yet ther
is no good procedure for their determination.
Current evidence from hydrogenation studies, oxldative desulfuri
and alkaline extraction does point to two types of organic sulfur in
coal. Roughly half the organic sulfur is amenable to removal by thes
methods, indicating its presence in some types of structures which
rather easily desulfurized, e.g., thiols, linear thioethers TH»
• me remainder
of the organic sulfur appears to resist these treatments, although it
can be removed by treatment that cleaves such sulfur compounds «* ^.u
H unas as dibenzothiopheno.
Hence, it is supposed that much of .the organosulfur in coal is in such
thiophenic structures. Though chemistry is known which can remove
sulfur from these structures, it tends to be drastic. Hydrogenation
for example, does accomplish this, but only by adding sufficient h d
to liquefy the coal. Oxidation, followed by basic hydrolysis at ele
temperacure, can effectively remove sulfur from dibenzothiophene witho
further change. In the laboratory, using alkali metals as reductants
it has been possible to bring total sulfur levels down to 0.1 percent
Two principle types of reaction have been used for removal of
organic sulfur - degradative extraction with base (NaOH) at elevated
temperature and oxidation with concurrent or subsequent hydrolysis
1198
-------
oxidants which we have heard about are air or oxygen, nitrogen oxides,
and chlorine. Peroxygen compounds have also been used. As yet, we know
little about the chemistry of some of these desulfurization reactions,
since little model compound work has been done on reactions of this
type. It is planned to carry out such studies in the immediate future.
All of the methods utilized so far have one thing in common. The
aaxinun aaounc of organic sulfur removed is between 40 and 60 percent,
depending on the coal and reaction conditions. This seems to be the
limit approached by the several methods. As I noted previously, this
could be the result of two types of organic sulfur, one of which behaves
chemically like dibenzothiophenic sulfur and resists most chemical
treatment. If this is true, it may not be possible to remove all of the
organic sulfur by simple chemical means.
The prospects for characterization of the organic sulfur in coal
appear good, at least in .enns of total organic sulfur and some functional
groups. Practical methods for removal of up to half of the organic
sulfur are at the stage where process development can be undertaken
provided environmental acceptance of the product can be guaranteed.
Consumer demand for such a product already exists. Even for those coals
where chemical desulfurization does not provide a product with totally
acceptable sulfur content, the partial reduction might allow the coal to
be nixed with a coal of lower sulfur content. In other situations, the
treated coal can be used to lessen the burden placed on the coal consumer
who operates sulfur reducing equipment, such as a flue gas desulfurization
facility. In summary, the prospects are good if there is encouragement
to proceed.
1199
-------
PANEL DISCUSSION ON
THE USE OF MODEL ORGANOSULFUR
COMPOUNDS TO INVESTIGATE THE EFFECTIVENESS
OF OXYDESULFURIZATION OF COAL
T. G. Squires, J. M. Harris, W. F. Goure,
S. K. Hoekman, B. A. Hodgson, and T. J. Barton
Ames Laboratory
Iowa State University
Ames, Iowa
Although some progress has been made in determining the nature of
organosulfur components in coal, there is still very little information
detailing the identity or even the functional group distribution of these
sulfur moieties. Specific organosulfur compounds such as thiophenes and
dibenzothiophenes have been isolated from coal and identified. Typically,
these materials were identified as an incidental consequence of investiga-
ting other types of compounds in coal. Efforts have also been made to de-
lineate the organosulfur functional group distribution through chemical
and physical properties. The chemical and physical bases for these studies
were, at best, obscure and the results were, in most cases, inconclu-
sive. Investigations are underway In this laboratory and at other locations
to detect organosulfur species directly by using such techniques as
3*S NMR and ESCA. However, none of these efforts have unambiguously
established the organosulfur functional group distribution in coal.
During the initial phases of this Investigation, it has been our
approach that a definitive knowledge of the organosulfur functional group
distribution is not a prerequisite for investigating the viability of
various desulfurl ration schemes. Thus to evaluate a specific desulfurl-
zation process, It is sufficient to measure the propensity of a repre-
sentative spectrum of organosulfur model compounds toward desulfurIzation
under the specific process conditions.
1200
-------
Although our conclusions necessarily extend to other oxydesulfur-
izatton processes, the basis for our initial investigations has been the
Ames version of the oxydesulfurization process. Conceptually, oxydesul-
furlzatfon is a two-step process and can be described by the following
chemical equations:
Step 1. Oxidation
Reaction Conditions: 150°C, 200 ps i 02> 0.2 M aq. Na2CO-, 1 hour.
Step 2. Desul fur ization
R1
NaHSO.
While there is some precedent in the literature for the oxidation
of sulfides by molecular oxygen, the basis for Step 2 occurring under
these reaction conditions is rather tenuous. Furthermore it is important
to realize that the sulfur is not extruded from the organosulfur moiety
until the second step. Thus, complete conversion of the organic sulfide
in Step 1 does not constitute desulfurization.
The following organosulfur compounds have been subjected to Ames
process conditions (150°C, 200 psi 02> 0.2 M aqueous Na.CO^, 1 hour) to
afford the results indicated.
1.
95% Recovery of
starting material
2.
98% (63%*) Recovery
of starting material
1201
-------
3.
89% Recovery of s
starting material
SCrL
90% (5^/o*) Recovery
of starting material
5.
CH2SCrL
6.
82% Recovery of
starting material
S—S
No other products detected.
* 25 grams raw coal added
In each of the first five cases, no oxidation products were detected.
While these are preliminary results and we are still refining our
experimental techniques, we are reasonably certain that the first five
compounds do not react under Ames conditions, even in the presence of
raw coal. We believe that the reduced recoveries of starting material in
the presence of raw coal (results 2 and 4) reflect adsorption of the or-
ganosulfur into the microporous surface of the coal and mechanical loss
associated with working up the reaction mixture. We are in the process
of modifying our experimental technique to obviate these analytical prob-
lems.
In the case of thiophenol (result 6), 70% of the starting material
can be accounted for as the simple disulfidic oxidative coupling product.
Although we have not accounted for the remaining 30% of the starting
material, the initial product of the reaction, diphenyl disulfide, appears
to be stable under Ames process conditions and is not efficiently oxidized
to benzene sulfonic acid. Therefore it is our preliminary conclusion
that, under oxvdesulfurIzatlon process conditions, most if not all organo-
sulfur compounds are unreactiveI
1202
-------
Another of our primary Initial objectives was to develop catalysts
and reaction conditions for the efficient conversion of organic sulfides
to the oxidized product (Step 1 of the Ames process) using moderate tem-
peratures and atmospheric pressure. Thus far, we have been able to ef-
ficiently oxidize dlbehzothlophene, phenyl sulfide, and diphenyl disulflde
under the following conditions.
1.
1.5 ml t-BuOOH
50 ml PhCH,
100°C *
2.
1.5 ml t-BuOOH .
50 ml PhCH, '
3 mg Mo(CO)6, 100°C
3.
02 stream, 75 C
10 ml cumene
kQ ml PhCH3
2.5 mg Mo(CO)6
11.6 min.
36 min.
5.
Reaction Conditions: 3.1 ml t-BuOOH, 50 ml PhCHj, 6 mg Mo(CO)6> 75°C
SS
23 min.'
75AC
SS
2
12.^ min.
100° C
SO H
Reaction Conditions: 13 ml t-BuOOH, 50 ml PhCH.,12 mg Mo(CO)6
1203
-------
On the basis of our experiments, we have reached the following con-
clusions.
1. Organic sulfides can be effectively oxidized to the sulfones by
alkyl hydroperoxides in organic solvents.
2. In the absence of added hydroperoxide, these same sulfides can
be oxidized just as effectively by bubbling a stream of oxygen
through the organic solvent provided a substance such as cumene
or tetralin is present. These substances are known to readily
form hydroperoxides in the presence of oxygen, and thus they
provide a method for the \jn situ generation of hydroperoxides.
3. The rates of both the molecular oxygen and hydroperoxide oxi-
dations can be increased by a factor of 10 to 15 by the addi-
tion of Mo(CO)^.
k. Mo(CO)6 is not an effective oxidation catalyst in aqueous media
and we are unable to oxidize organic sulfides under aqueous
conditions even at high temperatures and long reaction times.
We are presently expanding our initial studies of Mo(CO)x catalysis
to other types of organosulfur compounds. In addition we are evaluating
catalysts and techniques for achieving oxidation under aqueous conditions,
and we are investigating techniques for grafting these catalysts to a
polymer support.
Our initial investigations of desulfurization (Step 2 of the oxyde-
sulfurization process) have been much less encouraging. During these
studies we have generated results which can be outlined as follows:
DESULFONATION REACTIONS OF MODEL COMPOUNDS
0.2M Na2C03
80% V/V EG;H20
130°C
20_Hours
27 Hours
23 Hours.
No Reaction
No Reaction
No Reaction
1204
-------
0.2M NaOH
or KOH
EG, 190UC
21 Hours (NaOH)
No Reaction
17 Hours (KOH)
Hours (NaOH) No Reaction
22i Hours (KOH)
0.4M NaOH
H20
225°C, 20 Hours
->• No Reaction
8.
9.
5 Equivs NaOH
0.16 Eq Bu^NBr
1:1 Mesit-H20
98°C, 24 Hours
5 Equivs KOH
0.2 Eq l8-Crown-6
1.1 Mesit-H20
98°C, 21 Hours
5 Equivs KOH
0.25 Eq l8-Crown-6
Benzene
Reflux 20 Hours
-^ No Reaction
No Reaction
No Reaction
1205
-------
10.
11.
2M
150°C, 5 Hours
1 :1 H2SO^-H20
145 C, 19 Hours
No Reaction
No Reaction
12.
13.
Mesitylene
163°, 19 Hours
Mesitylene
0.25 Eq l8-Crown-6
163°C, 8 Hours
Unidentified Isomer
of Starting Material
60%
5 Equiv KOH, 163 C
Mesitylene
0.25 Equiv l8-Crown-6
82 Hours
40% Starting
Material
15.
O
5 Equiv KOH, 163 C
Mesitylene
0.25 Equiv 18-Crown-6
48 Hours
Mixture of
Compounds
1206
-------
Reactions 1-6 represent increasingly rigorous reaction conditions in an
attempt to achieve desulfurization while working within the scope of the
Ames process. Even at 225°C for 20 hours, no reaction had occurred. Re-
actions 7-9 represent attempts to facilitate the reaction through the use
of phase transfer reagents. This unsuccessful approach was based on the
premise that a homogeneous reaction will proceed more rapidly than a heter-
ogeneous reaction. On the basis of reactions 10 and 11, it appears that
the reaction cannot be effected in strong acid media either. Reactions
12-15 represent the only partially successful attempts at desulfonation.
It appears that the rate of the reaction can be substantially increased
by solublizing the KOH with crown ether. However, even under these re-
action conditions, the rates are very slow; and these conditions do not
represent a viable method for desulfonation. Presently we are studying
the effects of higher temperatures and catalysts on this reaction.
1207
-------
LIST OF PARTICIPANTS
David R. Alison
Arthur D. Little, Inc.
20 Acorn Park
Cambridge MA 02140
864-5770
Robert J. Alison
Mgr. Proj. Dev.
Dravo Corp.
Research Ctr.
Neville Island
Pittsburgh PA 15225
(412) 771-1200 X585
Gerald Anderson
Research Sup.
Inst. of Gas Tech.
3425 S. Stall St.
Chicago IL 60616
(312) 567-5832
Richard J. Anderson
Consultant
3820 Woodbridge Rd.
Columbus OH 43201
Susan Armstrong
Battelle
505 King Avenue
Columbus OH 43201
Dr. Richard Atkins
Mgr., Special Products
Research Cottrell
P.O. Box 750
Bound Brook NJ 08805
(201) 885-7135
Amir Attar, Prof.
University of Houston
Dept. of Chem. Eng.
Univ. of Houston
Houston TX 77004
(713) 749-4965
C. C. Bailie
Vice Pres., Engineering
Old Ben Coal Co.
500 N. DuQuoin St.
Benton IL 62812
(618) 435-8176
Dr. L. H. Beckberger
Mgr., Contract R&D
Atlantic Richfield Co.
400 E. Sibley Blvd.
Harvey IL 60426
(312) 333-3000
James E. Benson
Associate Chemist
Ames Lab
Iowa State Univ.
Ames IA 50010
(515) 292-3541
David H. Birlingmair
Head, Coal Prep. Engg.
Ames Laboratory
Iowa State Univ.
Ames IA 50010
(515) 294-2320
J. H. Blake
Mgr., Process Eqpt. Lab
FMC Corp.
1184 Coleman Ave.
Santa Clara CA 95052
(408) 289-2788
Lester E. Bohl
Special Proj. Eng.
PPG Ind.
New Martinsville WV 26155
(304) 455-2200
Charles M. Bonner
Prep. Eng.
C&K Coal Co.
P.O. Box 69
Clarion PA 16214
(814) 226-6911
Sidney Bourgeois
Lockheed
P.O. Box 1103
W. Station
Huntsville AL 35807
(205) 837-1800
Ray Bramhall
Asst. Dir., Prog. Dev.
SRI Int'l
1611 N. Kent St.
Arlington VA 22209
(703) 524-2053, X416
C. Thomas Breuer
Power Supply Staff Eng.
Georgia Power Co.
P.O. Box 4545
Atlanta GA 30302
(404) 522-6060, X3853
Donald R. Brockwehl
Norflor Const. Corp.
2510 E. Jackson St.
Orlando FL 32803
(305) 894-9731
J. Alfred Brothers
Mgr., Chemistry Div.
Nova Scotia Res.
Foundation Corp.
P.O. Box 790
Dartmouth, Nova Scotia
Canada B2Y 3Z7
(902) 424-8670, X131
Richard A. Brown
Res. Chemist
FMC Corp.
P.O. Box 8
Princeton NJ 07540
(609) 452-2300
Eugene Burns
Prog. Mgr.
Systems, Science &
Software
Box 1620
LaJolla CA 92037
(714) 453-0060
F. G. Campau
Sup., Mat. Prop. & App.
Detroit Edison Co.
200 Second Ave., H-9, WSC
Detroit MI 48226
(313) 897-1393
Peter Carney
Homer City Gen. Sta.
N.Y. State Elec. & Gas Co.
Homer City, PA 15748
(412) 479-9011
1208
-------
C. Blaine Cecil
Geologist
U.S. Geological Survey
M.S. 956 Geological Surv.
Nat'l Ctr.
Reston, VA 22092
(703) 860-7734
Chandrasekhar
Foster Miller Assoc.
Project Mgt.
135 2nd Avenue
Walthain MA 02154
(617) 890-3200
Christopher Cheh
Ontario Hydro
800 Kipling Avenue
Toronto, Ontario
Canada M8Z 534
Kang-Chun Chuang
Res. Asst.
Ames Lab.
Iowa State Univ.
305 Sweeney Hall
Ames IA 50010
(515) 294-3716
Or. William E. Clark
Proj. Mgr.
Conoco Coal Devi. Co.
Research Div.
Library PA 15129
835-6605
Kenneth L. Clifford
Mgr., Coal Cleaning
Electric Power Res. Inst.
3412 Hillview Avenue
Palo Alto CA 04303
(415) 855-2441
T.J. dough
Mgr., Major'Pro;).
Atlantic Richfield Co.
400 E. Sibley Blvd. ..
Harvey IL 60426
(312) 333-3000
Robert L. Cofer
Researcher
Battelle
505 King Avenue
Columbus OH 43201
(614) 424-4441
Dr. M. Cohen
Dir. New Bus. Devel.
Apollo Chem. Conf.
35 S. Jefferson Rd.
Whippany NJ 07981
Randy M. Cole
Proj. Mgr.
TVA
440 Commerce Union Bank Bldg.
Chattan-oga TN 37401
(615) 755-3571
Barney W. Cornaby
Ass. Mgr.
Battelle
505 King Avenue
Columbus OH 43201
(614) 424-7572
Martial P. Corriveau
Vice Pres.
Paul Weir Co.
20 N. Wacker Dr.
Chicago IL 60606
(312) 346-0275
Martial P. Corriveau
Vice Pres.
Paul Weir Co.
20 N. Wacker Dr.
Chicago, IL 60606
(312) 346-0275
Randy Craig
Sverdrup/Birtley Eng,
701 Deseret PI.
15 E. 1st St.
Salt Lake City, IT 84111
(801) 531-7172
Michael M. Crow
Prog. Dev. Coord.
Ames Laboratory
Iowa State Univ.
319 Speddlng Hall
Ames, IA 50010
(515) 294-3758
Peter Cukor
Teknekron, Inc.
2118 Milvia St.
Berkeley, CA 94704
(415) 548-4100
Dr. Rabinder S. Datta
Res. Eng.
Gulf Res. & Dev. Co.
P. 0. Box 2038
Pittsburgh, PA 15230
(412) 362-1600, X2503
R. S. Davidson
Mgr., Env. Ass. Prog.
Battelle
505 King Ave.
Columbus, OH 43201
(614) 424-7646
C. K. Dawson
Sup. Design Eng,
Ontario Hydro
700 Univ."Ave.
Toronto, Canada M5G1X6
(416) 592-5207
W. H. Delany, Jr.
Sales Mgr., Coal
Davy Powergas Corp.
P. 0. Drawer 5000
Lakeland, FL 33803
(813) 646-7459
John J. Detnchalk
Reclam. & Energy Adv.
Appalachian Reg. Comm.
1666 Connecticut Ave., NW
Washington, D.C. 20235
(202) 673-7861
1209
-------
Peter A. DeWitt
Vice Pres.
Reiss Viking Corp.
P. 0. Box 688
Sheboygan, WI 53081
(ALA) A57-AA11
Edward Dismukes
Southern Research Inst.
2005 Ninth Ave., S.
Birmingham, AL 35205
(205) 323-6592
Donald R. Dougan
Proj. Eng.
Babcock & Wilcox Co.
20 S. Van Buren Ave.
Barberton, OH AA203
(215) 753-A511
Cyril W. Draffin
Fossil Energy Planning
U.S. DOE
20 Massachusetts Ave., NW
Room 422A
Washington, D.C. 20003
(202) 376-A77A
Ronald Ellis
Chemist
Energy & Min. Res. Co.
P. 0. Box A09
517 Schoolhouse Rd. & U.S. 1
Kennett Square, PA 193A8
(215) AAA-0552
George Engelke
Asst. Mgr.
Comm. Test. & Eng. Co.
P. 0. Box 909
Rt. 50 East
Clarksburg, WV 26301
(304) 623-3329
Michael Epstein
Proj. Mgr.
Bechtel Corp.
P. 0. Box 3965
San Francisco, CA 9A119
(A15) 768-A16A
Nicholas T. F.sposito
Proj. Mgr.
Gen. Pub. Ut . Serv. Corp.
260 Cherry Hill Rd.
Parsippany, NJ 07054
(201) 263-4900
Glenn Eurick
Envir. Eng.
MN Power & Light Co.
30 W. Superior
Duluth, MN 55802
(218) 722-26A1
R. A. Ewing
Sen. Res. Eng.
Battelle
505 King Avenue
Columbus, OH 43201
(61A) A24-4720
Velmer A. Fassel
Deputy Director
Ames Laboratory
Iowa State University
Ames, IA 50011
(515) 294-3758
Bobby P. Faulkner, Mgr.
Allis-Chalmers Corp.
P. 0. Box 512
Milwaukee, WI 53202
(A14) 475-4624
Francis A. Ferraro
Engineer
American Electric Power
P. 0. Box 487
Canton, OH 44701
(216) 452-5721
Faith Fiene
Geologist
111. State Geol. Survey
221 Natural Res. Bldg.
Urbana, IL 61801
(217) 344-1481
Karel Fisher
Teknekron, Inc.
2118 Milvia St.
Berkeley, CA 94704
(415) 548-4100
Rav W. Fisher
Fossil Eng. Prog. Mr.
Ames Laboratory
Iowa State Univ.
Ames, IA 50010
(515) 294-3756
Carl Flegal
Applic. Mer.
TRW
01/1050 One Space Park
Redondo Beach, CA 90066
(213) 536-3542
Donald K. Fleming
Asso. Dir.
Institute of Gas Tech.
3424 S. State St.
Chicago, IL 60616
(312) 567-3739
Dr. Robert A. Florentine
Adv. Tech. Anal.
Energy & Min. Res. Co.
P. 0. Box 409
517 Schoolhouse Rd. & U.S.
Kennett Square, PA 19348
(215) 444-0552
Charles T. Ford
Sup., Anal. Serv.
Bituminous Coal Res. Inc.
350 Hochberg Rd.
Monroeville, PA 15146
(412) 327-1600
Ross Forney
Dir., Coal Serv. Div.
Ebasco Services, Inc.
P. 0. Box 986
Golden, CO 80401
(303) 279-8013
Joyce Fowler
FPA-IERL
MD-60
RTP, NC 27711
(919) 541-2903
Roger Frank
Fuel. Eng.
AMAX Coal Company
105 S. Meridian
Indianapolis, IN 46225
1210
-------
Dr. Wilfred L. Freyburger
Director
Institute of Mineral Res.
Michigan Tech. Univ.
Houghton, MI 49931
(906) 487-2600
Sidney Friedman
Branch Chief
Pittsburgh Env. Tech. Ctr.
4800 Forbes Ave.
Pittsburgh, PA 15213
(412) 892-2400
John Ganz
Service Rep.
McNally Pitts. Mfg. Corp.
E. Tenth St.
Wellston, OH 45692
(614) 384-2181
Thomas J. George
Mech. Eng., Proc. Env.
Dept. of Eng.
209 Prairie Ave.
P. 0. Box 863
Morgantown, WV 26505
(304) 599-7120
Richard A. Giberti
Kennecott Copper Corp.
128 Spring St.
Lexington, MA 02173
(617) 862-8268
Roland Glenn, Pres.
Combustion Processes
50 E. 41st St.
New York, NY 10017
(212) 889-0255
D. N. Goens
Proj. Mgr.
Hazen Res. Inc.
4601 Indiana St.
Golden, CO 80401
(303) 279-4501
Fred Goodman
Sen. Res. Sci.
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7711
Don Grabowski
Sen. Chem. Eng.
CM Corp., Mfg. Staff
GM Technical Ctr.
Warren, MI 48090
(313) 575-1022
James A. Gray
U.S. DOE - PETC
4800 Forbes Ave.
Pittsburgh, PA 15213
(412) 892-2400
Kenneth M. Grav
Homer City Gen. Sta.
PA Electric Co.
Homer City, PA 15748
(412) 479-9011
Jack Greene
Adra. Officer
EPA-IERL
MD-61
RTP, NC 27711
(919) 541-2903
Charles Grua
Div. of Env. Contr. Tech.
U.S. DOE
Washington, D.C. 20545
(301) 353-5516
Robert P. Guerre
Staff Eng.
Exxon Research
P. 0. Box 4255
Baytown, TX 77520
James B. Gulliford
Asst. Ecologist
Ames Laboratory
Iowa State Univ.
Ames, IA 5001]
(515) 294-3756
Edward U. Gunther
Oual. Cont . Spec.
So. Co. Services
P. 0. Box 2625
Birmingham, AL 35202
(205) 870-6625
Eugene D. Guth
Chief Chemist
KVB, Inc.
17332 Irvine Blvd.
Tustin, CA 92667
(714) 832-9020
Elton H. Hall
Sen. Chemist
Battelle
505 King Avenue
Columbus, OH 43201
424-4612
Robert P. Hangebrauck
Dir . , Energy Ass . &
Control Div.
EPA-IERL
MD-61
RTP, NC 27711
(919) 541-2825
H. Shafick Hanna
Asso. Res. Prof.
Mineral Resources Inst,
Univ. of Alabama
P. 0. Box AY
University, AL 354fi6
(205) 348-5453
Donald F. Hardesty
Research Engineer
Shell Development Co.
P. 0. Box 1380
Houston, TX 77001
(713) 493-7871
Warren Hardy
Project Manager
Davy Powergass , Inc.
P. 0. Box 36444
Houston, TX 77036
(713) 782-3440
1211
-------
Kenneth E. Harrison
Manager - Systems
Heyl & Patterson
Seven Parkway Center
Pittsburgh, PA 15220
(412) 941-5928
Andrew C. Harvey
Project Engineer
Foster-Miller Asso.
135 Second Ave.
Waltham, MA 02154
(617) 890-3200
Donald Haufknecht, Mgr.
Energy Env. Sys. Div.
Science Application, Inc.
1801 Avenue of the Stars
Los Angeles, CA 90067
(213) 553-2705
Roy J. Helfinstine
Mechanical Engineer
111. St. Geol. Survey
Natural Resources Bldg.
Urbana, IL 61801
(312) 344-1481 X 281
William A. Hills
Sr. Res. Chemist
FMC Corporation
P. 0. Box 8
Princeton, NY 08540
(609) 452-2300
Eugene C. Hise
Engineer
Oak Ridge Ntl. Lab.
Bldg. 9204-1
P. 0. Box Y
Oak Ridge, TN 37830
(615) 483-8611 X 3-5619
John A. Hoagland, Mgr.
So. Div.
Commercial Testing
& Eng. Co.
216 Oxmoor Circle
Birmingham, AL 35209
(205) 942-3120
David C. Hoffman
Supv.-Proc. Dev.
Dravo Lime Co.
650 Smithfield St.
Pittsburgh, PA 15222
(412) 566-4440
Lawrence Hoffman
President
Hoffman-Muntner Corp.
8750 Georgia Ave.
Suite E-134
Silver Spring, MD 20910
(301) 585-6080
Rudols A. Honkala
Physical Scientist
U.S. DOE
Rm. 3449 Fed. Bldg.
Washington, D.C. 20461
(202) 566-9033/9058
George C. Hsu
Group Leader
Jet Propulsion Lab.
4800 Oak Grove Drive
Pasadena, CA 91103
(213) 354-7428
Richard E. Hucko
Civil Engineer
U.S. DOE
4800 Forbes Ave.
Pittsburgh, PA 15213
(412) 892-2400/147
Horst Huettenhain
Mgr., Coal Res. Devel.
Bechtel National, Inc.
P. 0. Box 3965
San Francisco, CA 94119
(415) 768-8039
Robert D. Igou
Researcher
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-6574
Gerald A. Isaacs
Proj. Dtr.
PEDCo Environmental, Inc.
P. 0. Box 20337
Dallas, TX 75220
(214) 259-3577
Robert A. Jacobson
Prof, of Chemistry
Ames Laboratory - DOE
Iowa State Univ.
Ames, IA 50010
(515) 294-1144
T. Kelley Janes
Branch Chief
EPA-IERL
MD-60
RTP, NC 27711
(919) 541-2851
Norbert A. Jaworski
Deputy Dtr., IERL/RTP
EPA-IERL
MD-60
RTP, NC 27711
(919) 541-2821
D. M. Jewell
Sr. Res. Chemist
Gulf RM) Co.
P. 0. Drawer 2038
Pittsburgh, PA 15230
(412) 362-1600
Robert M. Jimeson
Energy & Env. Consultant
RMJ Associates
1501 Gingerwood Ctt.
Vienna, VA 22180
(703) 281-6555, 6333
John E. Jones, Jr.
Program Manager
Oak Ridge Ntl. Lab.
P. 0. Box Y
Oak Rigde, TN 37830
(615) 483-8611/37683
1212
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W. M. Kaas
President
Komiine-Snaderson Eng. Corp.
Holland Avenue
Peapack, NJ 07977
(201) 234-1000
John J. Kalvinskas
Proj. Mgr./Coal Desul.
Jet Propulsion Lab
4800 Oak Grove Dr.
Pasadena, CA 91103
(213) 354-2349
Frederick V. Karlson
Proj. Eng.
Bechtel Corp.
P. 0. Box 3965
San Francisco, CA 94119
(415) 768-5838
David R. Kelland
Co-Group Leader
MIT - Francis Bitter
Ntl. Maguet Lab
NW14-3113
Cambridge, MA 02139
(617) 253-5550
Douglas V. Kellee, Jr.
Otisca Industries, Ltd.
P. 0. Box 186
La Fayette, NY 13084
(315) 475-5543
Daniel W. Kestner
Sr. Supporting Devel. Eng.
AIME CIM
3600 Neville Rd.
Pittsburgh, PA 15225
(412) 771-1200-2251
James D. Kilgroe
Mgr., Coal Clng. Prog.
EPA-IERL
MD-60
RTP, NC 27711
(919) 541-2851
James K. Kindig, Mgr.
Coal Activities
Hazen Research, Inc.
4601 Indiana St.
Golden, CO 80401
(303) 279-4501
David Kirchgessner
Project Officer
EPA-IERL
MD-61
RTP, NC 27711
(919) 541-2851
Dan Kiser
Energy & Env, Anal.
1111 North 19th St.
Arlington, VA 22209
(703) 528-1900
Jeffrey Knight
Mgr. of Preparation
Rochester & Pitts-
burgh Coal Co.
Box 729
Indiana, PA 15701
(412) 465-5621
V. V. Kochetov
Operations Dtr.
Donetsk Coal Enrichmt.
Directorate
USSR Ministry of Coal
Moscow, U.S.S.R.
D. Carroll Laird, III
Dow Chemical U.S.A.
Resources Research
Texas Div.
A-2301 Bldg.
Freeport, TX 77541
(713) 238-0305
Alexis W. Letmnon, Jr.
Deputy Program Mgr.
Battelle
*)05 King Avenue
Columbus, OH 43201
(614) 424-4472
Richard Livingston
Asst. to Asst. Admin.
EPA
401 M Street, S.W.
MD-RD-672
Washington, D.D. 20460
(202) 755-0655
Gregory Lizak
Sen. Business Anal.
FMC Corp.
Central Eng. Labs
1185 Coleman Ave.
Box 580
Santa Clara, CA 95052
(408) 289-2067
Clive Longden
CONCOL, Inc.
Suite 2B
2311 E. Stadium Blvd.
Ann Arbor, MI 48104
Harold L. Lovell
Prof., Mineral Eng.
PA State Univ.
121 Mineral Sci. Bldg.
University Park, PA 16802
(814) 863-1641
Basil Lukianoff
Whiper Interpreting
15 Hillside St.
Danbury, CT 06810
(203) 743-4884
A. L. Luttrell, Mgr.
Adv. Ping. & Mktg.
Sverdrup/ARO, Inc.
101 W. Lincoln St.
P. 0. Box 884
Tullahoma, IN 37388
(615) 455-1186
F. Monty Lyon
Div. Prep. Eng.
Republic Steel Corp.
Fayette Bank Bldg.
Uniontown, PA 15401
(412) 438-2587
Richard Markuszewski
Research Asso.
Ames Laboratory
Iowa State Univ.
Ames, IA 50011
(515) 294-6374
1213
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Lee C. McCandless
Operations Mgr.
Versar, Inc.
6621 Electronic Dr.
Springfield, VA 22151
(703) 750-3000
William N. McCarthy, Jr.
Chemical Engineer
EPA
10813 Vista Road
Simpsonville, MD 21044
(301) 531-6256
Jane McCreery
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7992
Ray MeGraw
Staff Supv. Coal Prep.
Homer City Gen. Sta.
Homer City, PA 15748
(412) 479-9011
Edward T. McNally
Chairman
McNally Pittsburg Mgf. Co.
P. 0. Box 651
Pittsburg, KS 66762
(316) 231-3000
Aubrey F. Messing
Research Asso.
Empire St. Elec. Energy
Res. Corp., Suite 3950
1271 Avenue of the Americas
New York, NY 10020
(212) 246-4300
R. A. Meyers
Project Mgr.
TRW, Inc.
1 Space Park
Redondo Beach, CA 90278
(213) 536-2734
Eugene J. Mezey
Chemist
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-4995
Nick Milicia
Lab. Field Eng.
Joy Manufacturing
1755 Blake St.
Denver, CO 80202
(303) 892-0073
Rebecca Miller
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-4471
Michael Ray Miller
Asst. Eng.
Ames Laboratory
Iowa State Univ.
Ames, IA 50010
(515) 294-7508
Michael W. Miller
Sales Mgr.
Parkson Corp.
5601 NE 14 Ave.
Ft. Lauderdale, FL 33307
(305) 772-6860
Claude M. Moreland
Proj. Mgr.
Kaiser Engineers
P. 0. Box 23210
Oakland, CA 94623
(415) 271-5291
Michael P. Morrell
Engineer
GPU Service Corp.
260 Cherry Hill Rd.
Parsipanny, NJ 07054
(201) 263-4900/200
William F. Musiol, Jr.
Asso. Process Eng.
Dravo Corporation
17th Floor
One Oliver Plaza
Pittsburgh, PA 15222
(412) 566-3386
Kenneth R. Musolf
Plant Manager
Reiss Viking Corp.
2215 Breezeview
Bluefield, WV 24701
(304) 327-7639
I. K. Nekharoshy
Head of Laboratory
Inst. for Enrichmt.
of Solid Fuel
USSR Ministry of Coal
Moscow, U.S.S.R.
Gerry Norton
President
Norton-Hambleton Asso. Inc.
Suite 2B
2311 E. Stadium Blvd.
Ann Arbor, MI 48104
(313) 995-4044
Barry M. O'Brien
Product Manager
Exxon Chem. Co. USA
P. 0. Box 3272
Houston, TX 77001
(713) 656-0240
Robin R. Oder
Research Asso.
Gulf R&D Corp.
P. 0. Drawer 2038
Pittsburgh, PA 15230
(412) 362-1600/2953
Keith M. Parker
Env. Sci.
Wisconsin Power & Light
222 W. Washington Ave.
Madison, WI 53703
(608) 252-3084
R. C. Patyrak
Proj. Mgr.
Tennessee Valley Auth.
Water Oual. & Eco.
401 Chestnut
Chattanooga, TN 37401
(615) 755-3153
T. A. Pearce
Dow Chemical, USA
Texas Div.
A-2303 Bldg.
Freeport, TX 77541
Jaroslaw Pekar
Prog. Coor.
EPA-IERL
MD-62
RTP, NC 27711
(919) 541-2379
1214
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Lucy Pierson
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7816
Dan A. Poindexter
Mine Liaison Agent
Cols. & So. Elec. Co.
215 N. Front St.
Columbus, OH 43215
(614) 464-7296
Robert H. Poirier
Dept. Mgr.
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-4815
Neil W. Policow
Sales Eng.
Bird Machine Co.
155 Linden Ct.
Pittsburgh, PA 15237
(412) 367-4955
Clifford R. Porter
Proj. Mgr.
Nedlog Tech. Grp.
12191 Ralston Rd.
Arvada, CO 80004
(303) 425-5055
Frank Princiotta
Dtr., Energy Proc. Div.
EPA-OEMI
631 RD 681
Washington, D.C. 20460
(202) 755-0205
M. J. Prior
IEA Coal Research
14/15, Lower Grosvenor PI
London, S.W.I, England
London 828-4661
Mark Pritzker .
Phys. Sci.
Canmet
552 Booth St.
Ottawa, Ontario
Canada K1A OG 1
(613) 992-7782
James B. Proske
Design Eng.
Brown & Root, Inc.
P. 0. Box Three
Houston, TX 77001
(613) 678-9791
Steve Provol
Shell Devel. Co.
W. Hollow Res. Ctr.
TB-214
P. 0. Box 1380
Houston, TX 77001
(713) 493-7237
Leslie Mark Pruce
(No Address)
V. C. Ouackenbush
Mgr., Business Ping.
Catalytic, Inc.
Centre Square West
1500 Market Street
Philadelphia, PA 19102
(215) 864-8587
Gilbert E. Raines
Raines Consulting, Inc.
1016 Amberly Place
Columbus, OH 43220
(614) 451-5777
Kendall B. Randolph
Sr. Chem. Eng.
Versar, Inc.
6621 Electronic Dr.
Springfield, VA 22151
(703) 750-3000
Robert Reeves
Mining Engineer
Ebasco Services, Inc.
P. 0. Box 986
Golden, CO 80401
(303) 279-8013
David A. Rice
Engineer
Bethlehem Steel Corn.
Homer Res. Labs, Bldg. A
Bethlehem, PA 18016
(215) 694-2196
Gerald L. Robinson
Sr. Res. Sci.
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-4473
Sharron F. Rogers
Res. Ecologist
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7588
John M. Rosenbaum
Research Asst.
Univ. of CA, Berkeley
4576 Elmwood Rd.
El Sobrante, CA 94803
(415) 222-1928
E. S. Roth
Comm. Devel. Mgr.
FMC Corporation
2000 Market St.
Philadelphia, PA 19103
R. L. Rowell
Asso. Prof.
Dent, of Chemistry
Univ. of MA
Amherst, MA 01003
(413) 545-0247
Salomon M. Salomon
Sen. Sci.
Bird Machine Co.
Neponsset St.
N. Walpole, MA 12071
(617) 668-0400
Robert H. Salvesen
Res. Asso.
Exxon Research & Eng. Co.
P. 0. Box 8
Linden, NJ 07036
(201) 474-2220
Myrrl J. Santy, Head
Proc. Design Sec.,
Chem. Eng. Dept.
TRW Systems
One Space Park .
Redondo Beach, CA 90278
(213) 536-4076
1215
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Donald Sargent
Operations Mgr.
Versar, Inc.
6621 Electronic Dr.
Springfield, VA 22030
(703) 750-3000
K. I. Savage
Res. Dlr.
Commercial Testing & Eng. Co.
228 N. La Salle St.
Chicago, IL 60601
(312) 726-8434
James J.- Schaeffer, Jr.
Heyl & Patterson, Inc.
No. 7 Parkway Center
Pittsburgh, PA 15220
(412) 922-3300/263
Nell R. Schemehorn
Staff Geologist
Northern IN Pub. Serv. Co.
5265 Hohman Ave.
Hammond, IN 46325
(219) 853-5395
Rudy Schuller
Research Asso.
111. St. Geol. Survey
Univ. of Illinois
Natural Res. Center
Urbana, IL 61801
(217) 333-1197
Robert G. Shaver
Vice President
Versar, Inc.
6621 Electronic Dr.
Springfield, VA 22151
(703) 750-3000
J. R. Sinek
Mgr., Energy Systems
Kennecott Copper Corp.
128 Spring St.
Lexington, MA 02173
(617) 862-8268
Bill Slaughter
Proj. Mgr.
EPRI
3195 Kipling
Palo Alto, CA 04303
(415) 855-2441
Donald J. Smalter
Dir. - Development
Research-Cottrell
P. 0. Box 750
Bound Brook, NJ 08805
(201) 885-7826
Ben Smith
Research Chemist
EPA-IERL
MD-62
RTF, NC 27711
(919) 541-2557
Clay D. Smith
President
Otisca Industries, Ltd.
P. 0. Box 186
La Fayette, NY 13084
(315) 475-5543
G. Ray Smithson, Jr.
Mgr., Env. Control
Tech. Prog. Office
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7814
Robert Smock
Senior Editor
Elec. Light & Power Mag.
1301 S. Grove Ave.
Barrington, IL 60010
(312) 381-1840
Thomas C. Sorensen
Flotation Mgr.
The Galigher Co.
P. 0. Box 209
Salt Lake City, UT 84110
(801) 359-8731
Thomas G. Squires
Asso. Chemist
Ames Laboratory
Iowa State Univ.
Ames, IA 50010
(515) 294-1836
Edgel P. Stambaugh
Sr. Res. Sci.
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7827
Ronald W. Stanton
Geologist
U.S. Geological Survey
956 National Center
Reston, VA 22092
(703) 860-6104
C. W. Statler
Mgr., Generation Fuel Tech.
PA Electric Co.
1001 Broad St.
Johnstown, PA 15907
(814) 536-6611/513
Walter G. Steblez
Interpreter
Whisper Interpreting
15 Hillside St.
Danbury, CT 06810
(203) 743-4884
Richard D. Stern, Chief
Process Tech. Branch
EPA-IERL
MD-61
RTF, NC 27711
(919) 541-2915
John Suloway
Research Asst.
111. St. Geol. Survey
Univ. of IL
Natural Res. Ctr.
Urbana, IL 61801
(217) 333-1197
1216
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David Tamny
Project Officer
EPA-IERL
MD-60
RTF, NC 27711
(919) 541-2851
Terry W. Tarkington
Chemical Eng.
Tennessee Valley Auth.
OS WHA
Muscle Shoals, AL 35660
(205) 383-4631/2516
Richard R. Taylor
Mgr. Eng.
FMC Corporation
MHS Division
1801 Locust Ave.
Fairmont, WV 26554
(304) 366-6550
Scott R. Taylor
Res. Chemist
U.S. DOE
4800 Forbes Ave.
Pittsburgh, PA 15213
(412) 892-2400/177
Don Thomas
Mgr. Coal Prep.
Davy Powergas Corp.
P. 0. Drawer 5000
Lakeland, FL 33803
(813) 646-7459
Ralph E. Thomas
Res. Leader
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7236
S. J. Thomas
Marketing Spec.
Babcock & Wilcox
P. 0. Box 835
Alliance,.OH 44601
(216) 821-9110
James H. Tice
Eng. Coor.
Env. Qual. Cont. Sys.
PA Electric Co.
1001 Broad St.
Johnstown, PA 15907
(814) 536-6611
Duane A. Tolle
Research Ecologist
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7591
Ed Ungar
Director
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7369
Peter Van Voris
Task Manager
Coal Clng. Prog.
Battelle
505 King Avenue
Columbus, OH 43201
(614) 424-7579
G. G. Voznyuk
Head of Directorate
for Env. Control
USSR Ministry of Coal
Moscow, U.S.S.R.
Daman S. Walia
Res. Sci.
IIT Research Inst.
10 W. 35th St.
Chicago, IL 60616
(312) 567-4288
Robert P. Warzinski
Chemist
U.S. DOE - PETC
4800 Forbes Ave.
Pittsburgh, PA 15213
(412) 842-2400/321
Margaret A. Wechter
Sci. Admin./Fossil
Energy Program
Ames Laboratory
Iowa State Univ.
Ames, IA 50010
(515) 294-3758
Lawrence P. Weinberger
Member, Tech. Staff
The Aerospace Corp.
20030 Century Blvd.
Germantown, MD 20767
(301) 428-2748
Bernie Weiss, Supv.
Clean Energy Tech.
Catalytic, Inc.
1500 Market Street
Philadelphia, PA 19102
(215) 864-8591
Eugene M. Wewerka
Staff Member
Los Alamos Sci. Lab.
CMB-8, MS-734
P. 0. Box 1663
Los Alamos, NM 87545
(505) 667-5182
T. D. Wheelock
Professor
Iowa State Univ.
Ames, IA 50011
(515) 294-5226
Richard L. White
General Mgr.
Reiss Viking Corp.
P. 0. Box 3336
Bristol, TN 37620
(615) 878-2563
D. G. Williams
Vice President
N. Amer. Mining Cons., Inc,
1 Penn Plaza
250 W. 34th St.
New York, NY 10001
(212) 760-2500
1217
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W. M. Wills
Manager - Laurel Run
Laurel Run Mining Co.
P. 0. Box 26343
Richmond, VA 23260
(804) 644-4905
Jack Witz
Member of Tech. Staff
Aerospace Corp.
P. 0. Box 92957
Los Angeles, CA 90007
(213) 643-5372
Samuel Wong
Asst. Chem. Eng.
Argonne Natl. Lab.
Bldg. 205-Cen.
9700 S. Cass AVenue
Argonne, IL 60439
(312) 972-7565
Peter J. Woollam
Vice President
Bateman Coal Eng. Corp.
400 Morris Ave.
Denville, NJ 07834
(201) 625-5300
Harold Young
Asst. Mgr. Govt. Ops.
FMC Corporation
328 Brokaw Road
Santa Clara, CA 95126
(408) 289-2692
Jackson Yu
Project Mgr.
Bechtel Natl., Inc.
50 Beale Street
P. 0. Box 3965
San Francisco, CA 94119
(415) 768-3278
Peter Zavitsanos
Sr. Phys. Chem.
General Electric
3198 Chestnut St.
Philadelphia, PA 19101
(215) 962-3496
1218
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TECHNICAL REPORT PATA
(Please rtad liutructioni on tht
nvtm Mfort compltHni)
1.REPOBTNO.
EPA-600/7-79-098b
2.
3. RECIPIENT'S ACCESSION-NO,
4. TITLE AND SUBTITLE
Proceedings: Symposium on Coal Cleaning to Achieve
Energy and Environmental Goals (September 1978,
5. REPORT DATE
April 1979
6. PERFORMING ORGANIZATION CODE
S.E.Rogers and A.W.Lemmon, Jr. (Editors)
«. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Battelle Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
10. PROGRAM iLEMlNf NO.
EHE624A
11. CONTRACT/GRANT NO.
68-02-2163, Task 861
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
VERED
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTES T£RL.RTpprojectofficerJsJamesD
, MD-61, 919/541-
US. ABSf RACT : —— ——
The proceedings document presentations made at the Symposium on Coal Cleaning to
Achieve Energy and Environmental Goals, September 11-15, 1978, in Hollywood,
Florida, The symposium provided an opportunity for mutual review and discussion
of: the physical and chemical coal cleaning programs of EPA, DoE, the Electric
Power Research Institute, and numerous industrial organizations; European and
Soviet plans for the future; and problems of ongoing operations. The proceedings
include the following topics: coal characteristics, coal cleaning overview, physical
coal cleaning technology, environmental assessment and pollution control technology,
and chemical coal cleaning technology. The first three topics are covered in Volume
I; the last two, in Volume n.
n.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
Pollution
Coal
Physical Properties
Chemical Properties
Assessments
Pollution Control
Stationary Sources
Coal Cleaning
Environmental Assess-
ment
13B
21D,08G
14B
07D
IB. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (TMtRtport)
Unclassified
21. NO. OF PAGES
592
20. SECURITY CLASS (Tillspogt)
Unclassified
22. PBICE
•PA Perm 2220-1
1219
*U.S. GOVERNMENT PRINTING OFFICE: 19 79 -6UO-01* 39 02 REGION NO.*
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