&EPA
         United States
         Environmental Protection
         Agency
          Industrial Environmental Research  EPA-600/7-79-158c
          Laboratory          July 1979
          Research Triangle Park NC 27711
Chemically Active Fluid
Bed for SOX Control:
Volume 3.
Sorbent Disposal

Interagency
Energy/Environment
R&D Program Report

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                 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-600/7-79-158c

                                                        July 1979
Chemically Active Fluid Bed for SOX Control
           Volume 3.  Sorbent Disposal
                                by

                              C. C. Sun

                  Westinghouse Research and Development Center
                            1310 Beulah Road
                        Pittsburgh, Pennsylvania 15235


                          Contract No. 68-02-2142
                        Program Element No. EHB536
                      EPA Project Officer: Samuel L Rakes

                   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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                                 PREFACE

          The Westinghouse Research and Development Center is carrying
out a program under contract to the United States Environmental Protec-
tion Agency (EPA) to provide experimental and engineering support for
the development of the Chemically Active Fluid-Bed (CAFB) process.  The
process was originally conceived at the Esso Petroleum Company, Ltd.,
Abingdon, UK (ERCA), as a fluidized-bed gasification process to convert
heavy fuel oils to a clean, medium heating-value fuel gas for firing in
a conventional boiler.  Westinghouse, under contract to EPA, completed
an initial evaluation of the process in 1971.   Conceptual designs and
cost estimates were prepared for new and retrofit utility boiler appli-
cations using heavy fuel oil.  Westinghouse continued the process
evaluation from 1971 to 1973 and formulated an atmospheric pollution
control demonstration plant program for retrofit of a utility boiler
utilizing a high-sulfur, high-metals content fuel oil (for example,
                2
vacuum bottoms).   The CAFB process represented an attractive option for
use of these low-grade fuels, for which pollution control using hydro-
desulfurization or stack-gas cleaning was not economical.  Application
of a pressurized CAFB concept with combined-cycle power plants was also
assessed.^  Experimental support work was initiated between 1971 and 1973
to investigate two areas of concern - sorbent selection and spent sorbent
processing - to achieve an acceptable material for disposal or utiliza-
tion.  The preliminary design and cost estimate for a 50 MWe demonstration
plant at the New England Electric System (NEES) Manchester Street Station
                                         3
in Providence, RI were completed in 1975.   Commercial plant costs were
projected and development requirements identified.   Experimental support
of the sulfur removal system continued in order to  provide a basis for
                                   iii

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the detailed plant design.  A number of design and operating parameters
from the preliminary design study that required further development were
identified.  The environmental impact of the disposal of unprocessed and
processed spent sulfur sorbent has continued to be an area requiring
further study.  This report presents the results of a test program
carried out from 1976 to 1979 to obtain data for assessing the potential
environmental impact of disposal.
          Additional support work carried out under the present contract
(68-02-2142) includes:
               ,           .   4,5
            Sorbent selection
            Processing spent sorbent to minimize environmental
             impact
            Solids transport between adjacent CAFB fluidized beds
          e  Engineering evaluation of the CAFB process
                                    iv

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                                ABSTRACT

          The chemically active fluidized-bed (CAFE) process is being
developed to convert high-sulfur heavy oils and lowgrade coal to clean,
medium heatingvalue fuel gas in conventional boilers.  The disposal of
the spent sorbent, which consists of varying amounts of CaO, CaS, and CaSO,,
may cause environmental concerns associated with potential air, water, odor,
and heat pollution.  The spent sorbent can be further processed to reduce
its environmental impact by methods including dry sulfation, dead-burning,
room-temperature fly ash blending, high-temperature processing, and slurry
carbonation.  A laboratory experimental program has been carried out to
investigate three major areas:  residue characterization, leaching property,
and thermal activity.  The results from tests on solid residues from the
Esso Research Centre, Abingdom  UK (ERCA) pilot plant indicate that the
CAFB spent sorbent residue may be hazardous because of its sulfide content.
Test results indicate that nonhazardous disposal of the residue can be
achieved by processing the spent sorbent.  The environmental impact of CAFB
residue disposal is also compared with results of conventional power plant
residues:  flue gas desulfurization residues (FGD) and lignite ash.  Federal
regulations and guidelines on solid waste disposal, including the recently
enacted Resource Conservation and Recovery Act, have been reviewed to assess
their impact on CAFB solid residue disposal.

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                          TABLE OF CONTENTS

SUMMARY                                                            1

1.   INTRODUCTION                                                   4

2.   REGULATIONS/CRITERIA                                           6

3.   EXPERIMENTAL TESTING PROGRAM                                  13

    Samples                                                       13

       Unprocessed CAFB Residue                                   13
       Processed CAFB Residue                                     13
       Reference Material                                         15

    Experimental Program and Testing Method                       16

       Characterization                                           16
       Leaching Tests                                             16
       Activity Tests                                             18

    Results                                                       19

       Unprocessed Residue                                        19
       Processed Residue                                          50
       Reference Material                                         68
       Heat Release Property                                      85
       Total Dissolved Solids                                     87
       Total Organic Carbon                                       92
       Leaching Media                                             93

    Summary                                                       95

4.   ENVIRONMENTAL ASSESSMENT                                      98

5.   REFERENCES                                                   102
                                  vii

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                              LIST OF FIGURES
                                                                    Page

  1.   Photomicrographs  of (a)  CAFB-8 Gasifier Material
      (b)  Regenerator Material                                       25

  2.   SEM  Photomicrographs  of  CAFB-8 Stack  Fines  Showing
      Variation  of  Their  Physical  Characteristics                    27

  3.   SEM  and EDAX  of CAFB-8 Stack Fines                              28

  4.   SEM  and EDAX  of CAFB-10A Gasifier Bed Material                  33

5a.   Photomicrograph of  a  Cross-Section of a Spent CAFB-10A
      Gasifier Sorbent  Particle Blocking the  Area for  Electron
      Microprobe Analysis                                            34

  b-f. EMA  Area Scan for Ca, S,  Fe,  Si, and Al                        34

6a.   Photomicrographs  of a Cross-Section of  a Spent CAFB-10A
      Gasifier Sorbent Particle Blocking the  Area for  EMA Scan        35

  b-f.EMA  Area Scan for Ca, S,  Fe,  Si, and Al                        35

  7.   Leachate Characteristics  as  a  Function  of Total  Continuous
      Leach Time for the  CAFB  Samples Obtained via the Ralph
      Stone Co.                                                       38

  8.   Leachate Characteristics  as  a  Function  of Intermittent
      Leaching Time for the CAFB Samples.                             39

  9.   (a)  SEM Photomicrograph and  (b) EDAX Spectrum of the White
      Precipitate Formed  Readily in Air from  the  Leachate            40

10.  Electron Microprobe Analysis of Spent Regenerator Bed
     Material from CAFB  "Lignite" Run                               42

11.   SEM and EDAX of Stack Cyclone Fines from CAFB "Lignite"
     Run Material                                                   46

12.  SEM and EDAX of Stack Cyclone Fines from CAFB "Lignite"
     Run                                                            47
                                  viii

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LIST OF FIGURES (Cont)

                                                                   Paee
13.  Leachate Characteristics as Functions of Batch
     Mixing Time                                                    52

14.  Leachate Characteristics as a Function of Stone
     Loading                                                        53

15.  Comparison of Dissolved Sulfide in Leachates of Sulfated
     and Unsulfated CAFB-9 Spent Sorbent                            55

16.  Comparison of Specific Conductance of Leachates of Sulfated
     and Unsulfated CAFB-9 Spent Sorbent                            55

17.  Thermogravimetric Curve of Processed Spent Stones              59

18.  Typical SEM and EDAX of TUGCO Ash                              69

19.  Leachate Characteristics of TUGCO Ash                          72

20.  Valley Builder Supply Block                                    75

21.  SEM of Unprocessed FGD Sludge                                  80

22.  Leachate Characteristics of Dried FGD Sludge as a
     Function of Continuous Leach Time                              82

23.  Leachate Characteristics of Dried FGD Sludge as a Function
     of Intermittent Leaching                                       83

24.  Heat Release Property as a Function of Solid:Water Ratio       87

25.  Heat Release Property of Spent Solids from the CAFB Process    90

26.  Correlation between TDS and Specific Conductance in CAFB
     Leachate System                                                92

27.  Leachate Characteristics as a Function of Mixing Time          96
                                   IX

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                             LIST OF TABLES


                                                                   Page

  1.   Comparison of Environmental Impact of Processed and
      Unprocessed CAFB Spent Sorbents                                3

  2.   Hazardous Waste Criteria (RCRA Section 3001)                    8

  3.   Selected Water Quality Criteria                               11

  4.   CAFB Spent Sorbents Tested                                     14

  5.   Spent Sorbent Characterization by  X-Ray Diffraction           20

  6.   Chemical Analysis of CAFB Spent Sorbents from the
      Regenerator                                                   21

  7.   Leaching Results of Spent CAFB Regenerator  Sorbents           22

  8.   Trace Metal Elements in the Unprocessed CAFB  Regenerator
      Spent Sorbents and Their Leachates                             23

  9.   Leaching Results from the CAFB-8 Gasifier Spent  Sorbent        26

10.   Chemical Characteristics of CAFB-8  Stack Fines and
      Leachates                                                     30

11.   Comparison of  Trace Metal Elements  in  Regenerator Bed
      Material and  Stack Fines of CAFB-8                             31

12.   Chemical Characteristics of CAFB 10-A  Gasifier Material and
      Its  Leachates                                                  36

13.   Trace Metal Content  in  the  CAFB Spent  Sorbents Obtained
      through  Ralph  Stone  Co., and their  Leachates                   43

14.   CAFB-11  Operating  Conditions                                   44

15.   Solid  and  Leachate Characteristics  of  Spent Material from
      CAFB  "Lignite"  Run                                            48

16.   Chemical  Characteristics of  CAFB "Lignite" Run Residues and
      Leachates                                                      49

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LIST OF TABLES (Continued)

                                                                   Page

17.  Residual Activity of Spent CAFB "Lignite" Run Material by
     Heat-Release                                                   51

18.  Sulfur Contents in CAFB-9 Spent Sorbent and Dry-Sulfated
     CAFB-9 Spent Sorbent                                           51

19.  Comparison of Chemical Compositions of CAFB-9 Spent Sorbent
     before and after Dead-Burning                                  57

20.  Leachate Characteristics of Dead-Burned CAFB-9 Stones          58

21.  Environmental Impact of Sintered (Dead-Burned) Spent Sorbent   61

22.  Leachate Characteristics of Room-Temperature Processed Solid
     Compacts of CAFB-9 Regenerator Stone and Fly Ash               62

23.  Preparation and Compositions of High-Temperature Processed
     Solid Compacts                                                 65

24.  Leachate Characteristics of High-Temperature Solid Compacts
     of Sorbent/Ash Mixture                                         66

25.  Analysis of TUGCO Ash                                          68

26.  Chemical Characteristics of Leachate from TUGCO Ash by
     Continuous Shake Test                                          71

27.  Trace Metal Elements in TUGCO Ash and Its Leachate             73

28.  Chemical Compositions of Valley Builders Supply Samples        74

29.  Chemical Characteristics of Valley Builder Supply Block and
     Leachate                                                       76

30.  Heat-Release Properties of Valley Builder Supply Samples       77

31.  Summary of FGD Sludge Samples                                  79

32.  Chemical Characteristics of FGD Sludge, Liquor, and Leachate   84

33.  Activity Tests of Processed and Unprocessed CAFB Spent
     Sorbents by Their Heat-Release Properties                      88

34.  Chemical Characteristics of CAFB-10A Leachate Using
     Different Eluent                                               94

35.  Comparison of Leachate Characteristics from the CAFB and
     FGD Residues                                                   97

                                    xi

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LIST OF TABLES (Continued)

                                                                   Page

36.  Comparison of Environmental Impact of Processed and            99
     Unprocessed CAFB Spent Sorbents

37.  Preliminary Comparison of the Environmental Impact of the     101
     Disposal of CAFB and FGD Residues
                                  xii

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                             NOMENCLATURE







   ATV  = reactivity coefficient




   BOD  = biochemical oxygen demand




  CAFB  = chemically active fluidized bed




   COD  = chemical oxygen demand




   CSO  = Columbus Southern Ohio Company




   DLC  = Duquesne Light Company




   DWS  = drinking water standards




  EDAX  = energy dispersive analysis by X-ray




   EMA  = electron microprobe analysis




  ERCA  = Esso Research Centre, Abingdon, UK




   FBC  = fluidized-bed combustion




   FGD  = flue gas desulfurization




   LGE  = Louisville Gas and Electric Company




  MATE  = Minimum Acute Toxicity Effluent




   MEG  = Multimedia Environmental Goals




NIPDWR  = National Interim Primary Drinking Water Regulations




  RCRA  = Resource Conservation and Recovery Act




   SAM  = Source Analysis Model




   SEM  = scanning electron microscopy




   TDS  - total dissolved solids




   TEP  = toxicant extraction procedure
                                   xiii

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NOMENCLATURE (Cont)




   TGA = thermogravimetric analysis




   TOC = total organic carbon




 TUGCO = Texas Utility Generating Corporation




 USPHS = United States Public Health Service




   WHO = World Health Organization
                                   xiv

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                            ACKNOWLEDGEMENT

          This work was performed under Contract 68-02-2142 for IERL of
EPA.  We should like to acknowledge the contributions of Mr. Sam Rakes
as the contract officer.
          I should like to thank Messrs. G. L. Johnes of ERCA:  R. Stone
of Ralph Stone Co., and A. S. Werner of GCA for their cooperation in
supplying CAFB residues.  I should also like to acknowledge the kind
assistance of Mr. P. P. Leo of Aerospace Corporation, Mr. R. P. Van'Ness
of Louisville Gas and Electric Co., and Mr. D. Henzel of Dravo Lime Co.
in supplying FGD scrubber sludge samples for this study.
          I should also like to acknowledge the cooperative efforts and
contributions by many Westinghouse personnel, in particular, Dr. D. L.
Keairns, the project manager, for his guidance and consultation throughout
this investigation, Mr. C. H. Peterson for his work in residue processing
and in providing the processed samples for this study, and Messrs. J. T.
McAdams and R. Brinza for their technical assistance in carrying out the
laboratory experiments.  I should also like to express my appreciation
to many members of the Analytical Chemistry and Physical Metallurgy Depart-
ments within the Westinghouse R&D Center for their valuable contributions
in sample characterization.
                                    xv

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                                 SUMMARY

          Westinghouse has developed an experimental testing program to
determine the environmental impact of the disposal of CAFB residue,  con-
centrating its efforts on three major areas  residue characterization,
leaching property investigation, and potential thermal pollution.
          We have reviewed the environmental laws, including up-to-date
development of the regulations and guidelines under the authority  of the
                                       Q
Resource Conservation and Recovery Act.
          Actual CAFB residues from ERCA's gasifier, regenerator,  cyclone,
and stack were used in this study.  Materials processed by dry sulfation,
dead-burning, room-temperature ash blending, high-temperature compacting,
and slurry carbonation were also tested to evaluate the effect of  further
processing.
          On the basis of laboratory testing results, we judged that
unprocessed CAFB spent sorbent would be environmentally unacceptable for
direct land disposal.  Environmental acceptability, however, can be
achieved by further processing based on the available test data.  Table 1
summarizes the degree to which negative environmental impact can be re-
duced by use of four of the processing alternatives for spent sorbent from
the CAFB gasification process.  We believe the leaching tests performed
result in severer projections of environmental impact than will be encountered
in practice.  Since there are no guidelines for leachate qualities at the
present time, we have compared results with drinking water standards and
the leachate characteristics of natural gypsum.
          The drinking water standards in this investigation, however,
are used only in an effort to put data into perspective until EPA guide-
lines are established and should not be construed as suggesting that the
leachate must necessarily meet drinking water standards.  These standards

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 of course, are extremely conservative;  a leachate dilution/attenuation
 factor of 10 is currently being considered in the proposed  regulations
                                                                         0
 under Section 3001 of the Resource Conservation and  Recovery Act  of  1976
 (RCRA) by the Hazardous  Waste Management Division of the  Office of Solid
 Waste, EPA.
           The major environmental  concerns with direct  disposal are  heat
 release,  sulfide,  pH,  calcium,  SO.,  and IDS.   The major environmental
 concerns  with disposal after  processing are pH,  calcium,  SO ,  and IDS.
 On the basis  of these  results,  spent sorbent  processing will be required
 for nonhazardous disposal.  Four processing options  were  investigated.   A
 comparison of the  environmental impact  is summarized in Table  1.  On the
 basis  of  environmental impact,  the high-temperature  processing or dry
 sulfation options  are  the  recommended processes,  followed by dead-burning
 and low-temperature  fly  ash blending.   There  are  advantages and disadvantages
 to each method  of  processing,  and  the decision for each application  will
 be based  on  the balance  of technical, environmental,  and  economic factors.
 For example,  the high-temperature processing  option  requires a high  energy
 consumption  and may  only be selected if  it  can result in  utilization of
 the product material.  Of  course, site  selection,  design  and management
 of  the  disposal task based on  the site-specific hydrology,  geology,  climate,
 and soil  composition are critically  important  to  the success of solid waste
 disposal  practice.   Selection of the proper processing method  to reduce
 surface area  and permeability and to  improve  the heatrelease  and leaching
 properties can  greatly simplify the  disposal management task.
          Pending  implementation of  EPA criteria with which to assess the
 environmental acceptability of  the disposal of CAFE residues,  the chemical,
 physical, and leaching properties of  the spent CAFB material are compared
with the  residues  from conventional  coal-burning power plants with flue
 gas desulfurization processes (FGD).

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                                   Table 1

    COMPARISON  OF ENVIRONMENTAL IMPACT OF PROCESSED AND UNPROCESSED
                            CAFB SPENT SORBENTS
    Environmental
      arameters
 Processing
                 PH
 Total
Dissolved
 Solids
   (a)
Sulfide
Sulfate
Calcium
Trace
Metal
      (a)
   Heat
  Release
I3gm/Z0ml)
 Total
Organic
Carton
                                                        (a)
 Unprocessed CAFB
 Dry-Sulfation
                                      AT=ND<0.2C
 Dead-Burning
                                      AT=ND<0.2C
Rm-temp.Protessing
                                      AT=ND<0.2C
 HI 3emp. Processing
                                      AT=NO<0.2C
   Note:  u   Unprocessed CAFB Leachate Characteristics
        4-   Improved From u Value
        0   No Significant Change From u Value

        83  Do Not Meet Either The Drinking Water or Gypsum Leachate Criteria

        2  Pass Gypsum Leachate Criteria But Not Drinking Water Standards
        O  Pass Both Drinking Water and Gypsum Leachate Criteria

        (a)  No Drinking Water Standards Exist
A preliminary  comparison of  the environmental  impact  of the disposal of

unprocessed  CAFB solid wastes  and FGD  sludge residues from varying pro-

cessing systems suggests that  the disposal of  the CAFB solid waste may

cause comparable (due  to chemical properties), perhaps less negative (due

to physical  properties), environmental  effects than  the disposal of the

residue from currently commercialized  FGD processes.

           This assessment is based on  results  from a  continuing program

that  is, however, limited by  the investigation of spent CAFB materials

from  a pilot-scale  operation.   These  conclusions are  considered preliminary

and should be  reassessed as  more representative samples become available

from  a larger  scale plant.

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                             1.  INTRODUCTION

          The CAFB (Chemically Active Fluidized Bed) gasification process,
in which limestone or dolomite removes the sulfur from fuel gas during the
gasification process, was developed to permit the utilization of high-
sulfur residual fuel oil or refinery bottoms in conventional boilers by
producing a low-sulfur fuel gas.  Coal is also being investigated as a
fuel.   The process can be operated as a oncethrough limestone sorbent
system, a sorbent regeneration/sulfur recovery system, or a sorbent
regeneration system without sulfur recovery by capturing the sulfur-rich
gas from the regenerator with the spent stone.  The spent stone from each
system alternative can be processed to minimize the environmental impact
of the waste stone for disposal or to provide material for potential
                   3 9
market utilization. '
          Under contract to the U.  S. Environmental Protection Agency
(EPA), Westinghouse has carried out laboratory support work on sulfur
removal, solid transport, and the environmental impact of residue
         3 9
disposal. '    Esso Research Centre, Abingdon, England (ERCA) is carrying
out pilot-scale tests to investigate sulfur removal.    At San Benito,
Texas, a 10 MW demonstration plant  has been retrofitted by Foster Wheeler
Energy Corporation and Central Power and Light Co.,  and larger-scale
testing has begun.
          The CAFB gasification/desulfurization process produces a dry,
partially utilized limestone (or dolomite)  with particles up to 6000 pm
in size.  The composition of the sorbent for disposition will depend on
the characteristics of the original stone,  the fuel feed, the selection

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of the sorbent processing system, and the process operating conditions.
Spent sorbent compositions for the once-through and regenerative oper-
ating modes are:
                                    Solids Composition, wt %
                              Regenerative               Once-through
                          (regenerator solids)         (gasifler solids)
CaO                              85-95                      50-75
CaS                               2-5                       25-50
CaSO,                             2-4                         vl
Inerts                            1-10                       1-10
          The disposal of this solid may be accomplished by a variety of
methods.  Several processing alternatives have been developed to convert
calcium oxide (CaO) and calcium sulfide  (CaS) to an environmentally
acceptable form for disposal or further utilization.  Dry sulfation and
dead-burning are examples of dry processing systems; slurry carbonation
                                              3 9
is an example of the wet methods investigated. '
          Among the factors that will affect  the disposition of the
spent sorbent are the quantity of spent sorbent, its chemical charac-
teristics, regulations, geographical location, and the size of the
market for the respective applications.  The  environmental impact of any
disposed material is a function of its physical and chemical properties
and  the quantity involved.  Potential water pollution problems in many
cases can be predicted by chemical properties such as solubility, the
presence of toxic metals, and the pH of leachates.  The disposal of spent
stone from the CAFB gasification process may  create air pollution or
odor nuisance (e.g., hydrogen sulfide [H2S],  depending on the amount of
CaS  present.  Heat may be released on hydration of CaO.  Potential
water pollution may be introduced from the runoff leachates caused by
the  rainfall and naturally occurring subsurface flow through the land-
fill site.  An experimental testing program on stone analysis, leaching
properties, heat release properties, landfill properties, and air emis-
sion has been carried out to obtain this information.  The assessment
reported here is limited to the environmental impact from land disposal
of unprocessed and processed spent sorbent.   The processing work is
discussed elsewhere.

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                           2.  REGULATIONS/CRITERIA

          Under the authority of  the  Clean Air Act of 1970, the EPA
promulgated regulations on standards  of performance for new stationary
                         13
sources of air pollution.    Specifically, subpart B established standards
of performance for fossil-fuel-fired  steam generators of more than
263.75 GJ/hr  (250 million Btu/hr) and established the standards for
sulfur dioxide (S0?) emission.  The alternatives available for com-
pliance with  S0~ standards are:
          1.  To burn low-sulfur  fuels
          2.  To remove the SCL from  the exhaust gas with FGD systems
          3.  To use alternative  technologies.
          As  an example of the third  alternative, the chemically active
fluidized-bed gasification process employs calcium-based sorbent for
sulfur removal that results in the production of dry, partially utilized
sorbent and ash as solid residue  for  disposal.  The environmental
standards for solid residue disposal  from CAFB systems have not been
established.  Two environmental laws  that affect solid waste disposal
are the Resource Conservation and Recovery Act (RCRA) of 1976 (the
Solid Waste Disposal Act of 1965, as  amended by P.L. 94-580, 1976),
and the Federal Water Pollution Control Act of 1972 (Public Law 92-500,
1972, as amended by Clean Water Act, P.L. 95-217, 1977).14'15  Eventually,
disposal guidelines are to be promulgated by EPA under the authority
of the former.
          As a result of the Clean Air Act,  the Water Pollution Control
Act,  and other federal and state laws respecting public health and the
environment, greater amounts of solid waste have been created.  Similarly,

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inadequate and environmentally unsound practices for the disposal or
use of solid waste may create greater amounts of air and water pollution
and other problems for the environment and for health.   Among the
objectives of RCRA are the protection of health and the environment and
the conservation of valuable material and energy resources by:
       Providing technical and financial assistance to state and
        local governments and interstate agencies for the develop-
        ment of solid waste management plans
       Providing training grants in occupations involving the
        design, operation, and maintenance of solid waste disposal
        systems
       Prohibiting future open dumping on the land and requiring
        the conversion of existing open dumps to facilities that
        do not pose a danger to the environment or to health
       Regulating the treatment, storage, transportation, and
        disposal of hazardous wastes that have adverse effects
        on health and on the environment
       Providing for the promulgation of guidelines for solid
        waste collection, transport, separation, recovery, and
        disposal practices and systems
       Promoting a national research and development program for
        improved solid waste management and resource conservation
        techniques.
          The passage of RCRA closed the legislative loop of environmental
laws (air/water/solid) and created a new level of control over solid waste
disposal.  Of special concern are the regulations to be promulgated under
Subtitle C - Hazardous Waste Management.16-18  Table 2 summarizes the
currently proposed criteria for hazardous waste identification and those
that are being considered for future ruling.  Of the characteristics
currently proposed for  hazardous waste (ignitability, corrosivity,
reactivity and toxicity), toxicity and reactivity cause the most concern.

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                                 Table  2

               HAZARDOUS WASTE  CRITERIA (RCRA SECTION 3001)
  Characteristics
         Status
        Comment
 1.   Ignitability

 2.   Corrosivity
 3.  Reactivity
     Toxicity
 5.  Radioactivity

 6.  Generic
     Activity

 7.  Bioaccumulation

 8.  Additional
     Aspects of
     Toxicity
Proposed Dec. 18, 1978
in Fed. Reg.; scheduled
to be promulgated
Dec. 31, 1979.

Not intended to be
static; to be reviewed
periodically.
Advanced Notice for
Proposed Rulemaking,
Dec. 18, 1978.
Comments/information
invited.
To be proposed in Fed.
Reg. no sooner than
1 yr. from the Ad-
vance Notice date,
i.e., Dec.  18, 1979.
Current proposed regu-
lations apply only to
liquid waste pH >12 or
_<3, but proposed regu-
lations may change.

"Sulfide bearing waste
which can generate toxic
gases"...or, "reacts
violently with water"...
Some uncertainty may
arise from the interpre-
tation of this qualita-
tive statement, espe-
cially with regard to
regenerative, PFBC
residue.

A waste is hazardous if
its "EP" leachate
exceeds 10X primary DWS.
          A waste is considered toxic and, therefore, hazardous if its
eluent from the "extraction procedure" (EP, proposed in Federal Register,
Dec. 18, 1978) contains trace elements exceeding ten times the primary

drinking water standards.  Because of the low levels of trace elements

-------
exhibited by the CAFB leachates, we expect that the CAFB solids would
not be toxic.  The unprocessed CAFB residue, however, may be considered
"reactive" because of its sulfide content.  This is by no means conclusive.
Should the CAFB solids be determined to be hazardous waste under RCRA
3001, we would expect them to be classified under the "special waste"
category under the regulations of RCRA Sec. 3004 for "utility waste."
On the other hand, they could be processed (and we have shown that this
can be done) to render them nonhazardous and, therefore, subject to the
regulations and criteria under RCRA Sec. 4004 for nonhazardous waste
disposal^^ and proposed guidelines under RCRA Sec. 1008 for location,
design, construction, operation, and maintenance of solid waste land
disposal facilities.20
          The primary environmental concern with solid waste disposal is
the potential ground and surface water contamination caused by leachate
run-off or seepage.  The federal regulation that most nearly relates to
a limit on seepage water quality is the EPA's "Alternative Waste
Management Techniques for Best Practical Waste Treatment"2-'- under the
authority of the Federal Water Pollution Control Act of 1972 amended by
the Clean Water Act of 1977.  These criteria, which apply to publicly
owned treatment and land application of waste water, state that the
groundwater, resulting from land applications of waste water,  shall  be
limited to the maximum contaminant levels contained in the National
                                                   22
Interim Primary Drinking Water Regulations  (NIPDWR)   or  to the existing
concentration if the latter is greater.  If the groundwater is to be
used for other than a drinking water supply, "the ground  water  (sic)
criteria should be established by the Regional Administrator."  In
contrast to the United States Public Health Service  (USPHS) Drinking
                            21
Water Standards (DWS), 1962,   which limit  sulfate and chloride to
250 mg/ each (and many  others, e.g.,  copper,  iron,  manganese, nickel,
tin, and zinc), no limits are given in  the NIPDWR for these substances.
These and other substances, however, may be  included in secondary
standards, when issued.

-------
           In  anticipation  of  such  forthcoming criteria,  the  chemical
 characteristics  of leachates  from  leaching experiments are compared with
 the  drinking  water standards  set by  NIPDWR,22 USPHS  Drinking Water
 Standards,23  and the World Health  Organization (WHO) Potable Water
 Standards.     Of course, these  standards  are  extremely conservative;
 a  leachate  dilution/attenuation factor  of 10  is  currently being con-
 sidered  in  the regulation  draft under Section 3001 of RCRA by the
 Hazardous Waste  Management Division  of  the Office of Solid Waste, EPA.17
 Note that the drinking water  standards  are used  in this  investigation
 only in  an  effort  to put data into perspective in the absence of EPA
 guidelines  and should not  be  construed  as suggesting that the leachate
 must necessarily meet drinking  water standards.  Although the guidelines
 for  the  power plant effluents2-* are  not applicable to the disposal of
 dry spent sorbent  from the CAFB process,  they are used as additional
 references  in this investigation.  Table  3 lists the selected water
 quality  criteria for leachate comparison.
          Currently, EPA-IERL-RTP  is developing Multimedia Environmental
            26                                           27
 Goals (MEG)   and  Minimum  Acute Toxicity  Effluent (MATE)    for use in
 the environmental  assessment  of rapid effluent screening.  MATE values
 are being developed on the basis of health and ecology for land, water,
 and air.  EPA-IERL-RTP/EACD (Energy Assessment Control Division) is also
 developing  Source  Analysis Models  (SAM) based on comparison  with MEG
 and MATE values.   SAM/IA ranks  effluent by "degree of hazard" and "toxic
                     no
 unit discharge rate,"   and provides a  standardized methodology for
 environmental assessment.
          Existing air pollution control  regulations limit the S0?
 emission level discharged  by  fossil  fuel  power plants.   One  commercialized
 process  for SO  removal is flue gas  desulfurization  (FGD) , which gent-r-
 ates large  quantities of sludge and  has received considerable attention
 environmentally.   A recently  published  EPA report by SCS Engineers
 entitled "Data Base for Standards  and Regulations Development for Land
                                     29
Disposal of Flue Gas Cleaning Sludges   concluded that the characteris-
 tics of  FGD sludge set the need for  regulation and recommended that
                                    10

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           Table 3




SELECTED WATER QUALITY CRITERIA
                                 Effluent  Guidelines
Substance
Ag
As
Ba
Ca
Cd
Cr

Cu
Fe
Hg
Mg
Mn
Ni


Pb
Se
Sn

Zn

so4
Cl
N03
F

pH
(pH unit)
IDS
Drinking Water Standards, mg/
22
NIPDWR
0.05
0.05
1.0

0.01
0.05



0.002



23
USPHS
0.05
0.05
1.0

0.01
0.05
(Cr+6)
1.0
0.3


0.05
2.0
\
l
0.05 0.05
0.01 0.01

1.0
1
1 5.0
I
250
250
10 (as N)j 45
1.4 to 1.7
2.4


500
WHO 24
Highest
Desirable
Level

0.05

75
0.01


0.05
0.1
0.001
30
0.05



0.1
0.01


5.0

200
200
45
1.7

7.0 - 8.5

500
Maximum
Permissible
Level

0.05

200
0.01


1.5
1.0
0.001
150
0.5



0.1
0.01


15

400
600
45
1.7

6.5 - 9.2

1500
and Standards
for Steam
Electric Power
Generation, 25





0.2

1.0
1.0










1.0






6.0 - 9.0


               11

-------
regulations allow for site-specific factors as well as sludge character-
istics.  Important disposal site characteristics to be considered for
regulatory action are present and projected land use, topology, hydrology,
and meteorology.
          Because of the wide variation in the characteristics of solid
wastes in general, weather, soils, topography, groundwater from site to
site, and nearby stream guality and flow characteristics, permits are
currently being awarded on a site-specific basis.  Eventually, state
                                               g
regulations will apply as a result of the RCRA,  but these regulations
will not be enacted until federal standards are promulgated.  Depending
on the actual site selected for disposal, the leachates would have to
meet the water quality criteria for the specific water use.-'1-'  Further-
more, the success of a land disposal application depends, above all,
on the design, construction, and operation of a specific disposal site
based on the geology, hydrology, and meteorology of that particular site.
                                    12

-------
                      3.   EXPERIMENTAL TESTING PROGRAM

SAMPLES
          Samples  investigated  to  leach the environmental impact of
land disposal fall into  three categories.
Unprocessed CAFB Residue
          Residues from  the  CAFB pilot plant at ERCA were used.   These
included spent gasifier, regenerator,  cyclone, and stack fines.
Table A summarizes the unporcessed ERCA residues tested and the fuel and
sorbent used for each run.
Processed CAFB Residue3'9>12
          Various  techniques for further processing were used on the
spent sorbent.  Samples  tested  for their environmental impact included
those processed by the most  promising methods:  dry sulfation, dead-
burning, room-temperature fly ash  blending, and high-temperature com-
pacting.  They are listed below:
       DS-mix - CAFB-7 spent sorbent processed by dry sulfation in
        a 2.5-cm bench-scale fixed-bed reactor
       CAFB-903 - CAFB-9 spent sorbent processed by dry sulfation
        in a 10-cm fluidized-bed unit
       CAFB-904 - CAFB-9 spent sorbent processed by dry sulfation in
        a  10-cm fluidized-bed unit, then separated by particle size
        to two fractions which  achieved different degrees of sulfation
       DB163 to 171 - nine  CAFB-9 spent sorbents processed by dead-
        burning at three different temperatures for three different
        durations
                                    13

-------
                                  Table 4

                         CAFB SPENT SORBENTS TESTED
CAFB-Run
     Fuel
      Sorbent
CAFB-7
CAFB-8
CAFB-9
CAFB-10
CAFB-10A
High-S
residual oil

High-S
residual oil

High-S
residual oil

High-S residual oil
+ bitumen

High-S residual oil
+ coal and lignite
Denbighshire limestone
f BCR 1359 limestone

BCR 1359 limestone
BCR 1359 limestone
+ Aragonite

BCR 1359 limestone
BCR 1359 limestone
CAFB-11
Lignite
BCR 1359 limestone

-------
        DB44 ym ~ six CAFB-9  spent sorbents  of -44  ym size  processed
        by dead-burning at two different temperatures for three dif-
        ferent durations
        DB-66+88 ym - six CAFB-9  spent sorbents of  -66+88 ym size pro-
        cessed by dead-burning at two different temperatures for three
        different durations
        Room temperature 4A,  4B,  and 4C air  cured for 7,  14, and
        28 days - nine solid  compacts prepared from three mixtures
        of CAFB-9 spent sorbent and fly ash, and air cured in water
        for three lengths of  time
        Hi-temperature 75-CF-22,  75-CF-26, 65-CF-30 - three solid
        compacts prepared by  hot  pressing mixtures  of CaS,  CAFB-9
        spent sorbent, and CaSO,  with fly ash at 1050C and
        33,000 MPa (4800 psi).
Reference Material
          The following reference materials were tested:
        FGD residue.  Unprocessed and processed S02 scrubber
        sludges from conventional power plants with FGD systems
        provide a comparison of power plant residue with a
        currently commercialized process.
                    31
        Lignite Ash.    Lignite ash from (TUGCO) serves as a refer-
        ence for lignite ash for residues from CAFB gasification of
        lignite.
                                    31
        Valley Builder Supply Block.    Representative blocks and
        aggregates manufactured by Valley Builder Supply, a
        potential contractor to utilize the CAFB spent sorbent
        from the CAFB demonstration plant at San Benito, Texas,
        were tested to provide reference for processed CAFB spent
        sorbent.
        Gypsum.  Iowa ground gypsum No. 114 was used to provide a
        reference for CaSO, leachability because of the large
        amount of CaSO, present in the spent CAFB sorbents.
                                   15

-------
 EXPERIMENTAL PROGRAM AND  TEST METHODS
          The environmental  impact of  any  disposed material is a  function
 of its physical and chemical properties  as well  as of  the quantity
 involved.  Potential water pollution problems  can be predicted from the
 chemical characteristics of  leachates, such as pH, specific ion concen-
 trations, trace element dissolution, and total dissolved solids (IDS).
 Disposal of the CAFB solid wastes may  also create air  pollution,  odor
 nuisance, and heat-release problems.   To assess  the environmental impact
 of CAFB solid waste disposal and the suitability of waste material as
 landfill, physical and chemical characteristics of the residue, leaching,
 and heat-release properties  were investigated.
 Characterization
          Chemical, physical, and morphological characterization of the
 spent bed and carry-over material was  carried out by optical microscopy,
 scanning electron microscopy (SEM), energy dispersive analyses by X-ray
 (EDAX), electron microprobe  analysis (EMA), X-ray diffraction, thermo-
 gravimetric analysis (TGA),  emission and atomic absorption spectroscopy,
and wet chemical methods.
Leaching Tests
          At this time, there is no standard EPA leaching test with
which the potential environmental contamination from a solid waste can
be assessed.   A standard test has been proposed by EPA in the Federal
Register "Hazardous Waste  Guidelines and Regulations"-'-^ under the
authority of RCRA Sec.  3001 to identify hazardous waste.   We expect
 this test, entitled "extraction procedure"(EP), to be promulgated
 in December 1979.
                                   16

-------
          Parallel to the EPA effort, ASTM committee 19.12 (subcommittee
                                                    32
19.1203) is also developing a standard leaching test   for solid waste
materials.  A 48-hour shake method using either type IV reagent water
(ASTM D-1193 or pH = 4.5 sodium acetate-acetic acid buffer is proposed.
A shake test is proposed by both organizations.
          In this study leachates were induced by the shake test that
                                                         9 33 34
Westinghouse developed prior to the EPA and ASTM efforts, '  '    unless
otherwise specified.  Samples of waste stones were mixed with deionized
water in Erlenmeyer flasks at room temperature.  An automatic shaker
capable of 70 excursions per minute was used to agitate the mixtures.
Among the parameters investigated were sorbent/water  loading,  sample
mixing time, and pH of the leading medium.  The supernatants resulting
from this operation were filtered, and the filtrate was determined for
pH, specific conductance, TDS, calcium, magnesium, sulfide, sulfate,
trace metal ion and anion concentrations, and total organic carbon (TOG)
content.  The solid samples before and after the leaching operation were
also analyzed for their chemical and physical characteristics.   Since
CaSO^ is a major constituent of the waste stone, and leachates contained
high calcium and sulfate concentrations, a naturally occurring gypsum was
tested under similar leaching conditions for comparison.
          Two shake procedures have  been  employed.  These  are  described
below.
        Continuous  shake  test.   It establishes  equilibrium condi-
         tions between  the solid  and  its aqueous surrounding and
         provides  the worst possible  case  with  respect  to  contam-
         ination release.  This method  has been  used by Westinghouse
         since 1975  as  one of  the  screening  tests  for determining
         leaching properties of CAFB  spent solids.  Typically, a
         1:10 solid-to-water ratio is used.
                                    17

-------
        Intermittent shake test.   A series  of ten to fifteen
         cycles of a 72-hour  shake test  was adopted  as  part  of
         the  leachability study to provide leaching rate,  aging
         effect, and long-term leachability  of the worst case and
         to make possible the  calculation of "total fraction
         leached" for any specific ion or for TDS  as  a function
         of total leach time or total leachate passing the  sample.
         Leachates were analyzed at the end  of each interval,  and
         a fresh charge of ionized water  was added for each
         72-hour leach cycle.   Typically, a  1:3 solid-to-water
         ratio  was used.
          Both shake tests  are more severe  than conditions anticipated
under  actual land disposal; results from the shake tests are  expected
to project the worst.
Activity Tests
          No standard  EPA activity test  exists.   Under  Sec.  3001 of
RCRA,  EPA's Hazardous  Waste Management Office  is  currently developing
test methods for  reactivity criteria  as  an  effort  to  define hazardous
waste.    Their tests  concentrate  on  hazardous  properties  such as
explosiveness  and  chemical and mechanical instability but  do not apply
                  35
to residual lime.
          The  activity of residual  lime  in  spent  CAFB materials can be
determined by  its  heat release property on  contact with water, as the
hydration reaction of  CaO is extremely exothermic.    Literature on
lime reactivity and  slaking rate has  been reviewed, including the ASTM
    37
C110   for the  slaking rate of quicklime (CaO), Murray's study of lime
reactivity as  a function of porosity  and shrinkage characteristics
                   38
during calcination,   and American Water Works' standard on lime for
water treatment.
                                  18

-------
          The heat release activity of CAFB residue in this study was
measured calorimetrically.  The temperature rise of a solid/water system
containing free CaO is a function of the solid/water ratio.  In our
experimental effort to establish a screening test for the residual
activity in spent CAFB solids produced under varying processing con-
ditions, a solid/water proportion of 3 g to 20 ml (which is in the bulk
range specified by the ASTM-C110 test and by Murray's work) was found
empirically to provide much better repeatability than that from a higher
solid/water ratio that would give greater temperature rise but would
lack reproducibility, probably due to local heating.  Higher solid/water
ratios were also used, however, because they provide higher sensitivity
and simulate rainfall onto the disposed solid.
          Chromel-alumel thermocouples were used to monitor the tempera-
ture rise in the stone/water system with an Omega cold junction com-
pensator and a millivolt recorder.  The heat release tests were conducted
on the actual spent sorbent and on carry-over fines from the CAFB pilot
unit at ERCA.  Calcined and uncalcined limestone and dolomite samples
were also tested for comparison.
RESULTS
Unprocessed Residue
          The actual CAFB residues from ERCA pilot-scale runs were
tested in this work.  These can be further grouped as shown below.
Table 5 summarizes the typical compounds present as identified by
X-ray diffraction.
CAFB-7, 8, 9 Regenerator Material
          Three batches of actual regenerator spent sorbents using
residual oil as the fuel were tested.  Table 6 summarizes  the chemical
analyses.  Leaching tests were carried out under both aerobic and
anaerobic conditions - in other words, under air and nitrogen atmos-
pheres, respectively.  The oxidation and leachability of sulfide ions
                                  19

-------
                      Table 5




SPENT SORBENT  CHARACTERIZATION  BY  X-RAY DIFFRACTION
Dwg.l7(AB31
Sample
CAFB-8
Gasifier Bed
CAFB-8
Gasifier Bed
CAFB-8
Regular Bed
CAFB-8
Regular Bed
CAFB-8
Stack Fines
CAFB-10A
Gasifier Bed
CAFB-11
Regular Bed
CAFB-11
Cyclone
CAFB-11
Stack Fines
Fuel
Resid. oil
Resid. oil
Resid. oil
Resid. oil
Resid.oil
Resid. oil
+ coal
+ lignite
Lignite
Lignite
Lignite
Physical
Separation
White particles
Black particles
White
Black
No separation
No separation

Chemical Composition
CaO

Minor
Major
- -
Major
Major
Major
Major
Ca
-------
                                 Table 6
                     CHEMICAL ANALYSIS OF CAFB SPENT
                      SORBENTS FROM THE REGENERATOR

Ca
=
S
SI
CAFB- 7, %
66.5
1.25
2.98
CAFB-8, %
60.5
3.89
2.31
CAFB-9, %
64.3
2.24
3.07
were affected by the oxygen partial pressure in the system.   Table 7
summarizes the chemical characteristics of the leachates.   Table 8
summarizes the trace metal contents in the spent regenerator sorbents
and their leachates.  Results showed that:
       The leachability of trace metal ions is not expected to
        cause water pollution.
       The leachates are alkaline with pH = 12.8.
       Concentrations of calcium, sulfate, sulfide, and TDS as
        well as pH are major concerns.
       Total dissolved ions are higher for the anaerobic leaching,
        as indicated by the specific conductance of the leachates.
       Sulfide is higher in the anaerobic leachates and sulfate
        is higher in the aerobic case when all other conditions
        are identical.  This is reasonable because part of the
        dissolved sulfides may be oxidized to sulfate under aerobic
        mixing conditions.
     e  Gaseous H~S evolution from leachates over 240 hours con-
        stitutes less than 1 percent of the total sulfide in the
        stone.  Note, however, that these tests were conducted in
        deionized water at room temperature.  In the case of acid
        rainfall onto the disposed sulfide-containing stone, the
        H2S evolution would probably be higher.
       Further processing of the spent stone is deemed necessary
        in order to render it environmentally suitable for disposal.
                                    21

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                     Table 7




LEACHING  RESULTS OF SPENT CAFB  REGENERATOR SORBENTS
                                                             0<1. 257C927
Regenerator
Spent Sorbents

CAFB-9
CAFB- 7
CAFB-8
Experiment
Stone
loading
Mixing
time
Stone
loading
Mixing
time
Mixing
time
Conditions
4g/200 ml/24 hr, aerobic
20 g/200 ml/24 hr,
40 g/ 200 ml/ 24 hr,
80 q/ 200 ml/ 24 hr,
4 g/200 ml/24hr, anaerobic
20 g/200 ml/ 24 hr,
40g/200 ml/24 hr,
80 g/200 ml/24 hr,
20 g/200 ml/6hr, aerobic
20 g /200ml/ 24 hr, "
20 g/200 ml/ %hr, "
20 g/200 ml/ 150 hr, "
20 a /200ml/ 214 hr, "
20g/200 ml/6 hr, anaerobic
20 g/200 ml/ 24 hr, "
20 g/200 mil % hr, "
20 g/200 ml/ 150 hr, "
20 g/200 ml/ 214 hr^ "
1 g/250 ml/24hr, aerobic
25 g/250 ml/24 hr, "
10 g /250ml/ 24 hr, "
25 g/250 ml/ 24 hr, "
50 g/250 ml/ 24 hr, "
25 g/250 ml/ Ihr, "
25 g/250 ml/ 3 hr, "
25 g/250 ml/ 6 hr, "
25 g/250 ml/ 17 hr, "
25 g/250 ml/ 24 hr, "
25 g/250 ml/ 48 hr, "
10g/100 ml/48 hr, aerobic
lOg/100 ml/100 hr, "
10g/100 ml/240 hr, "
10 g/ 100 ml/432 hr, "
10 g/100 ml/48 hr, anaerobic
10 g/100 ml/100 hr, "
10 g/100 ml/240 hr, "
10 g/100 ml/432 hr, "
Chemical Characteristics of Leachates
pH
1Z6
12.7
12.6
12.5
12.64
12.64
12.5
115
12.5
12.7
12.6
12.8
12.9
12.6
12.7
lib
12.8
12.6
12.8
US
12.8
12.8
US
12.7
12.7
118
11 &
12.8
1Z8
12.3
lil
lil
12.4
12.3
12.1
12.1
11.7
Specific
Conductance.
M mhos-cm
6,300
7.390
8,900
1,340
6,900
8,380
9,580
14,200
6,790
7,890
8,920
9,180
9.330
7,060
8,380
9,840
10,490
10, 710
6,040
6,600
7,630
8,380
7,170
7,750
7,610
7,810
8,140
8,380
8,735
9,150
9,700
10,360
10,130
8,580
9,930
11,000
10,690
Ca.
mgtf
824
1,368
1,824
3,496
928
1,512
1.952
3,784
936
1.368
1,860
1,936
2,064
984
1,512
2,096
2,344
2,440
668
760
1,005
1,280
1,576
920
938
1,000
1,175
1,280
1,453
1,624
1,724
2,0%
2,176
1,352
1,752
2,064
2,232
S .
mg/t
106
435
576
2,560
166
659
928
5,080
230
435
627
1,062
883
214
659
1.338
1,734
1,888
6.4
214
73.5
185
485
US
31 0
54.3
191.5
185
329
432
264
744
784
936
1072
1376
SO.
mg/l
346
1,037
1,325
1,536
507
614
1,075
2,016
422
1,037
1,555
1,843
2.016
461
614
1,286
1,277
1,210
77
153
556
1,035
1,990
220
345
480
844
1,035
1,380
931
1,548
1,622
1,297
1,225
1,000
1,211
1,410
Gaseoys S.
*of S in
Solid
0.054%
0.054%
<0.3*
< 1%



<0. 01%
<0. 01%
<0. 01%
                        22

-------
                             Table  8
                                                     Dwg. 170*1833
TRACE METAL ELEMENTS IN  THE UNPROCESSED CAFB REGENERATOR
              SPENT  SORBENTS AND THEIR LEACHATES
\Samples
Elements\
Ag
Al
As
B
Ba
Be
Bi
Ca
Cd
Co
Cr
Cu
Fe
Hg
Li
Mg
Mn
Mo
Na
Ni
Pb
Se
Si
Sn
Sr
Ti
V
Zn
Zr
Sb
Spent Sorbent, wt%
CAFB-9
< 0.0002
0.3
<0.02
< 0.002

< 0.0001
< 0.0007
>10
< 0.007
< 0.002
0.002
< 0.002
0.2


0.8
0.02
0.007

0.1
< 0.007

1
< 0.002

0.01
1
< 0.007
< 0.001

CAFB-8
<0.01
0.07

ND<0.01


ND<0.01
>10
ND<0.03
ND<0.01
NO < 0.03
<0.01
0.1

<0.03
0.33
0.05
ND<0.01
<0.1
0.03
ND<0.01

0.3
NO < 0.03

0.02
0.3
NO < 0.03
ND<0.03
NO < 0.03
Leachates, mg/
CAFB-9
ND<0.02
1000
ND < 0. 3
ND < 0. 1
ND<0.05
ND<0.1
0.1

<0.1
0.4
ND<0.02
0.4
1
ND<0.02
NO < 0.05
ND1
0.4
ND<0.2
> 10
ND < 0. 2
ND<0.05
NO < 0.5
ND<0.2

CAFB-8
<0.03
<1
<0.05
0.03

0.1
<0.03
>1000
<0.03
<0.1
<0.03
0.08
0.03
< 0.001

<1
<0.03
0.08

<0.1
<0.1
<0.01
0.2
<0.1

<0.03
<0.03
<1
<1
<0.1
DWSe
0.05

0.05

1.0
1.0


0.01

0.05
1.0
0.3
0.002


0.05


2.0
0.05
0.01

1.0



5.0


       ND - Not Detectable
       " DWS - U.S. Public Health Service Drinking Water Standards
               (USPHS 1972)
               National Interim Primary Drinking Water Regulations
               (NIPDWR,  1976)
               World Health Organization Drinking Water Standards
               (WHO,  1971)
                               23

-------
           Leaching tests using the intermittent shake method and
 activity tests are discussed in later sections.
 CAFB-8 Gasifier Material
           Both the gasifier and the regenerator spent sorbents  are
 granular,  with varying color shades,  as  shown in Figure  1.   They grad-
 ually disintegrate into grayish powder on contact with moisture in
 the air.   The spent sorbent after leaching becomes a  white-to-gray  powder
 consisting primarily of calcium carbonate (CaCOo) and slaked lime
 (Ca(OH),,).   Although the spent sorbent from the  gasifier is  not  expected
 to  be disposed of directly, it is also tested for its  leaching behavior.
 Table 9 summarizes the results.   As expected,  results  indicated  less
 desirable  characteristics than those  from the leachate of the regener-
 ator stone,  which is also judged unsuitable for  direct disposal.
 CAFB-8 Stack Fines
           Effort was directed toward  characterizing the  stack fines
 since the  particulate emission from the  CAFB process  is  a potential
 concern.
           Scanning electron microscopy (SEM)  and energy  dispersion
 analysis by  X-ray (EDAX) were used for chemical  and physical characteri-
 zation.  Figure 2 is SEM photomicrographs of CAFB-8 stack fines  illus-
 trating variation in their physical characteristics.   Some spherical
 particles  were present that resembled cenospheres in  typical coal ash.
 Larger  particles  were often agglomerates  of finer particles.  Figure  3
 shows  EDAX spectra of particles  observed  on SEM.   An  area scan by EDAX
 for  the entire area shown on SEM in Figure 3(a)  showed that  the  CAFB-8
 stack  fines  consisted mostly of  calcium.   X-ray  diffraction  identified
 it to be CaO.   Figures  3(b)  and  (c) show  that  even the submicron particles
were high in  calcium with  minor  elements  such as  sulfur,  silicon, sodium,
potassium, chlorine,  iron,  and zinc.   Calcium oxide appeared to  be  the
major component in  all phases of the  CAFB-8 stack fines, with the
exception of  the  spherical  particle shown in  Figure 3(d), whose  EDAX
spectrum showed it  to be mostly  iron.
                                    24

-------
     (a)
    (b)
Figure 1 - Photomicrographs  of  (a)  CAFB-8 Gasifier Material
           (b) CAFB-8 Regenerator Material
                             25
                                                                      RM-70683

-------
                       Table  9




LEACHING RESULTS FROM THE CAFB-8 GASIFIER SPENT SORBENT
Leaching Conditions
10 g, 100 ml, 48 hr, aerobic
10 g, 100 ml, 48 hr, anaerobic
10 g, 100 ml, 100 hr, aerobic
10 g, 100 ml, 100 hr, anaerobic
10 g, 100 ml, 240 hr, aerobic
10 g, 100 ml, 240 hr, anaerobic
10 g, 100 ml, 432 hr, aerobic
10 g, 100 ml, 432 hr, anaerobic
Leachate Characteristics
PH
12.3
12.3
12.2
12.0
12.1
12.0
12.0
11.8
Sp. Cond.,
ymhos-cm~l
8740
8790
10000
13600
11400
14800
11250
15700
Ca,
mg/
1384
1256
1780
2400
2596
2880
2584
3440
Mg,
mg/Ji
9
31
31
31
12
19
5
5
s ,
mg/
-
1888
704
2664
448
3392
928
2592
S0~ 4
mg/9.
300
213
745
18
2145
25
1272
144
i

-------
Figure 2 - SEM Photomicrographs of CAFB-8  Stack Fines  Showing
           Variation of Their Physical Characteristics
                              27
                                                                      RM-71955

-------
                                    32SEC 28662 I NT
                             v s : seee  HS . SBEV/CH
                             ee         |es
                             	      EDRX
                       (b)

                       (d)
Figure 3 - SEM and EDAX of CAFB-8  Stack Fines
                      28
                                                                RM-71954

-------
          The amount of free carbon in the CAFB-8 stack fines was
determined by TGA to be in the range of 5 to 8 percent by weight.
Similar tests showed that the gasifier and regenerator bed materials
from the same run contained less than 2 percent free carbon.
          Standard leaching tests were conducted on CAFB-8 stack fines.
Solid and leachate characteristics are summarized in Table 10.   Note that
the stack fines contain lower sulfide and higher sulfate than does the
bed material, and the leachate of stack fines contains much less sulfide
than does that from the bed material.
          Trace metal element contents in the bed material and stack
fines are compared for CAFB run 8.  Results summarized in Table 11
indicate higher concentrations in the stack fines - for example,
chromium, copper, mercury, manganese, sodium, lead, and vanadium.
Table 11 also compares their leachates and indicates low dissolved trace
elements in both.
          The only element that did not meet the stringent DWS is
mercury, whose concentration in the leachate of stack fines was 0.03 ppm
as compared with the DWS for mercury of 0.002 ppm.  This is not neces-
sarily a problem because the amount of stack fines produced in a
typical plant is relatively small compared with the total amount of
spent solids from the bed.
CAFB-10, 10A Residue
          CAFB-10 and 10A were runs in which mixed fuels were used
(residual oil, bitumen, lignite, and coal).  CAFB-10A from ERCA was
run under the following conditions:
          Sorbent                - Limestone BCR 1359
          Average gasifier temp. - 950C
          Average regenerator    - 1100C
          Run length             - 50 hr:  45 hr fuel oil
                                    5 hr coal - 1.5 hr Texas lignite
                                                3.5 hr Illinois'No. 6
                                   29

-------
                                         Table 10
                CHEMICAL CHARACTERISTICS OF CAFB-8 STACK FINES AND LEACHATES
Sample
CAFB-8 Stack Fines
Leaching Conditions
Solid
Chemical Characteristics
Ca
46.7 wt %
Mg
0.62 wt %
S
0.18 wt %
SO4
7.19 wt %
Leachate
Leachate
Leachate
Leachate
10 g/100 ml/100 hr/aerobic
10 g/100 ml/100 hr/anaerobic
10 g/100 ml/196 hr/aerobic
10 g/100 ml/196 hr/anaerobic
1504 mg/1
1440 mg/1
1624 mg/1
1800 mg/1
7.2 mg/1
0
9.6 mg/1
9.6 mg/1
-
>100 mg/1
< 20 mg/1
370 mg/1
1339 mg/1
1116 mg/1
1094 mg/1
1094 mg/1

-------
                       Table  11
                                                      Dwg. 1689B48
COMPARISON  OF TRACE METAL  ELEMENTS IN REGENERATOR BED
         MATERIAL AND  STACK FINES OF CAFB-8

Substrate
Ag ^
Al
As
B
Ba
Be
Bi
Ca
Cd
Co
Cr
Cu
Fe
Hg
Mg
Mn
Mo
Na
Ni
Pb
Se
Si
Sn
Sb
Ti
V
Zn
Zr
Solid.
CAF8-8 Reg.
Bed Mat '1






<1

<1
<3
5
2

0.03

50
3
50
1000
10





1%


ppm
CAFB-8
Stack Fines






<1

<1
<3
10
5

4

100
3
>1000
1000
30





2%


Leachate
CAFB-8 Reg.
Bed Mat' 1
<0.03
<1.0
<0.003
0.03

0.1
<0.03
>1000
<0.03
<0. 1
<0.03
0.08
0.03
<0.001
<1.0
<0.03
0.08

<0.1
<0.1
<0.003
0.2
<0.1
<0.1
<0.03
<0.03
<1.0
<1.0
,mg/f
CAFB-8
Stack Fines
<0.01
0.02
< 0.003
0.5
<1.0
<0.01
<0.01
Major
<0.01
<0.05
<0.05
<0.05
<0. 1
0.03
<1.0
<0.05
0.2
>5.0
<0.05
<0.05
<0.003
0.3
<0.05
<0.05
<0.05
<0.05
<1.0
<0.05
U.S. Drinking
Water Standards."
mqlt
0.05

0.05

1.0
1.0


0.01

0.05
1.0
0.3
0.002

0.05


2.0
0.05
0.01

1.0



5.0

* DWS: NIPOWR 1976, USPHS 1962,and WHO. 1971
                           31

-------
 Figure  4  shows  typical  SEM photomicrographs  and  EDAX spectra of CAFB-10A
 gasifier  material  at  the  surface and  fractured surface  of a spent sorbent
 particle.   EDAX spectra scanning the  entire  SEM  area indicated the
 presence  of silicon,  aluminum, potassium,  iron,  and  vanadium in addition
 to  the  major species  calcium and sulfur.   Higher sulfur is observed on
 the particle surface.
          Electron microprobe analysis  (EMA) provides elemental profiles
 of  the  particle  cross-section.  Figures 5  and 6  illustrate two types of
 sulfur  profiles  found in  spent sorbent particles of  the CAFB-10A gasifier
 sorbent.  Figure 5(a) shows a photomicrograph of a cross-section of a
 partially sulfided limestone particle blocking the area scanned for
 calcium,  sulfur, iron,  silicon, and aluminum shown in Figures 5(b)  to (f).
 The concentration of an element is proportional  to the intensity of the
 X-ray counts.  Calcium  is evenly distributed, and sulfur concentrates on
 the particle periphery, as do iron and silicon in this case.   Figure 6
 shows an opposite sulfur gradient with sulfur depletion at the particle
 surface.  We suspect that this type of particle is formed during
 regeneration when a fully sulfided limestone particle is partially
regenerated to CaO, which is  more concentrated at the surface of the
particle.   A third type of sulfur configuration,  not shown in these
figures, has sulfur evenly distributed throughout the particle.
          Table 12  summarizes the leaching results and indicates the
following:
       Leachates are  high in pH and  TDS attributable to CaO  present
        as a major species in the solid.
       Sulfide  in  the leachate  is  lower  than the previously  tested
        CAFB spent  sorbents as  is  consistent  with the lower sulfide
        content  present  in the  CAFB-10A gasifier  solid.
       Sulfate  in  leachate is dominated by the CaSO,  present  in
        the  solid,  which is higher  in  CAFB-10A  spent  sorbent  than
        in the previously  tested  CAFB  spent stones.
                                  32

-------
               (a)
                                                                                                     (b)
U)
               (c)
                                                                           16SEC  33318INT
                                                                   v s . seee       _geEv/CH
                                                                                                     (d)
                                                                               EDRX
                              Figure 4 - SEM and EDAX of CAFB-10A Gasifier Bed Material
                                         (a) (b) particle surface
                                         (c) (d) fractured surface

-------
                 (a)
 (b)
                 (c)
(d)
Figure 5 - (a)  Photomicrograph of a Cross Section of a Spent
                CAFB-10A  Gasifier Sorbent Particle Blocking  the
                Area  for  Electron Microprobe Analysis
           (b)  EMA Area  Scan for Ca, (c) for S, (d) Fe,  (e) Si,
                (f) Al
                                34
                                                                        RM-70681

-------

               (a)
                                                (b)
               (c)
                                                 (d)
                                                 (f)
Figure 6 - (a)  Photomicrograph of a Cross Section of a Spent
                CAFB-10A Gasifier Spent Sorbent Particle Blocking
                the Area for  EMA Scan
           (b)  EMA Area Scan for Ca, (c) S, (d) Fe,  (e) Si,
                (f) Al
                                35
                                                                              -

-------
                                                   Table 12
                                CHEMICAL  CHARACTERISTICS  OF CAFB-10A GASIFIER
                                          MATERIAL AND  ITS LEACHATES
Dwq. 1704B32
OJ



Samples
CAFB-10A
Gasifier Stone.
urf OL



Leachates,
mg//



Leaching Conditions
Before leaching
After leaching
10/g/100 ml/100 hr/aerobic
10 g/100 ml/100 hr/aerobic
10 g/100 ml/100 hr/anaerobic
10 g/100 ml/196 hr/aerobic
10 g/100 ml/196 hr/anaerobic
Chemical Characteristics


PH
-
-

12.2
12.2
12.3
12.3
Specific
Conductance,
pmhos/cm



11130
11230
11740
8620


Ca
57.6
*

1708
1768
1572
1472


Mg
0.83
ft

<10
<10
<10
<10


s
0.78
*


150
91
374


SU4
9.62
<

1263
1311
1395
1139


CO,
0.8
21

*
ft
fr
*


OH
0.17
5,1

*
*
^
*
                    Not determined

-------
       The leached stones contain much more CaCOH)^ and CaCO,,
        than does the original stone due to the hydration and
        carbonation of CaO during the leaching process.
          In order to correlate the various EPA contractors'  efforts in
the area of CAFB spent sorbent disposal, samples were requested and
                                      39
received from the Ralph Stone Company.     These included five batches  of
                                                            33 34  40
Exxon and PER spent sorbent and fly ash from the FBC process   '   '   and
two CAFB spent solids from the ERCA pilot unit.
          Leaching studies were carried out on the CAFB spent materials.
Two methods were employed:  the continuous leach test reported previously
and an intermittent leach test.
          Figure 7 shows results from the continuous leaching.  Two
points are noted.  First, calcium and sulfide increase with mixing time,
indicating that CaS equilibrium between the solid and aqueous phase is
not achieved in 200 hours.  Secondly, the CAFB-10A bed and CAFB-10
gasifier fly ash display similar leachate characteristics except that
higher dissolved sulfide is found in the leachate of the bed material,
consistent with the solid analysis.
          Results from the intermittent shaker tests of several CAFB
residues are shown in Figure 8.  Several points can be noted:
       All leachates had similar pH and sulfate that improved
        only very slightly with total leachate volume and time.
       The repeatability of the two batches of CAFB-10A was good
        (CAFB-10A and RS-CAFB-10A).
       CAFB-8 regenerator material, which had higher sulfide
        content in the solid, produced  leachate with higher  S  ,
        Ca, and TDS, as would be expected from the greater CaS
        dissolution.
       Initial TDS was worst for CAFB-8 regenerator sorbent and
        best for CAFB-10 fly ash.  All  converge to a similar value
        after several 72-hour intervals.
                                   37

-------
                                          Curve 690793-B
         300
         200
         100
           0
        2000

        1000
        2000
        1000
      o_
      E
      o
      i/>
      o
      o
      O
14
12
10
 8
 6

 8
 6
 4
                       o RS-CAFB-lOAGasif.  Bed
                       a RS-CAFB-lOGasif. Fly Ash
                              100               200
                    Total Continuous Leach Time, hr
Figure  7  - Leachate  Characteristics as a  Function of Total
            Continuous Leach Time for the  CAFB Samples
            Obtained  via the Ralph Stone Co.
                               38

-------
                                                Curve 691326-i
            Normalized Leachate Quantity. m//g Starting Solid
                                     30     36     42
ouu
*, 600
01
i 400
"3
to
200
0
^,2000
f
1000
'o
(0
o
0
2000
en
15
"5
0
12
ft 10
8
6
1
 10
o
I 8
I 6
1 4
o
o 2
OJ
o.
l/l
1 1 1 1 1 1 1
N 	 PAFR 10A fiaiif Red
v ............ PC-P4FR-inA fiacH Rwi
- X. 	 , RS-CAFB-10 fiasif Ash
v.   CAFB-8 Reqenerator Bed


"^--. """^-^   __
i i i i i l i

i i i i i i i
i i i i i i i

i i i i i ii


- r.^i  . 	 ' 	 l ' ' ' ' -
-
2 4 6 8 10 12 14
n = Total No. of 72 hr Intermittent Leaching
i i i
360 720 1080
                      Total Leach Time= (72) (n)hr


Figure 8 - Leachate Characteristics as  a Function of
            Intermittent Leaching for  the CAFB  Samples
                            39

-------
                             (a)
                             (b)
Figure 9 - (a) SEM Photomicrograph  and  (b)  EDAX Spectrum of
               the White Precipitate  Formed Readily in Air
               from the Leachate
                             40
                                                                     RM-71557

-------
      e  CAFB spent solids tested so far contained high concen-
         trations of CaO,  and their leachate did not seem to
         improve considerably with time.
           White crystalline precipitate found on the leachate surface
 when the leachate was stored overnight has been identified by X-ray
 diffraction and by TGA to be CaCO- (calcite) that must have been formed
 by carbonation of dissolved calcium with carbon dioxide (CO,-,) in air.
 Figure 9 shows a SEM and  EDAX of such precipitate.  Trace metal elements
 were determined on these  solids and their leachates.  Results from the
 CAFB spent materials which are presented in Table 13 show that the trace
 metal element content in  these leachates is below the U. S. drinking
 water standards.  This is consistent with our previous report based on
 analyses of other batches of spent sorbent from the CAFB process.
 CAFB-11 Residue
 ,          CAFB-11 was a 100 hr run using Texas lignite, during which
*    / 1                                                 9A
' GCA   carried out the Level I environmental sampling.    The operating
x
 conditions are summarized in Table 14.  Four types of samples collected
 by GCA personnel during the run were tested for the environmental impact
 of disposal.
           The gasifier and regenerator bed materials were granular,
 similar to the previously tested spent sorbents from residual oil runs.
 Figure 10 shows microphotographs of a cross-section of a spent sorbent
 particle from the regenerator and elemental profiles (Ca, Mg, S, Si,
 Al, Fe, and C) on an area near  the surface.  Calcium is evenly distributed
 in the calcium-based sorbent particle.  Sulfur, silicon, aluminum, and
 iron are more concentrated on the particle periphery, suggesting an ash
 deposit at the particle surface of approximately 10 ym thickness.
 Carbon, however, is depleted at the particle surface where ash coating
 exists.  The gasifier and the regenerator residues appear to be very
 similar.
                                     41

-------
Opt
         ograph
  Figure 10 - Electron Microprobe Analysis of Spent  Regenerator
              Bed Material  from CAFB "Lignite" Run
                                 42
                                                                          RM-77934

-------
                       Table  13
                                                     Dxg. 1689647
TRACE METAL CONTENT  IN  THE  CAFB  SPENT SORBENTS OBTAINED
       THROUGH RALPH STONE  CO. AND THEIR LEACHATES
Substance
Ag
Al
As
B
Ba
Be
Bi
Ca
Cd
Co
Cr
Cu
Fe
Hg
Mg
Mn
Mo
Na
Ni
Pb
Sb
Se
Si
Sn
Sr
Ti
V
Zn
Zr
Solid (w%)
RS-
CAFB 10A
Gasif. Bed

>10
< 0.003
0.01

0.0001
<0.0003
10
<0.003
< 0.0005
0.003
0.005
>10

1.0
0.005
0.001 j
<0.03
0.01
< 0.001


>10
0.0003

0.02
0.03
<0.01
<0.01
RS-
CAFB-10
Gasif. Fly Ash

3
<0.003
0.001

<0.0001
<0.0003
10
<0.003
<0.0005
0.003
0.003
3

0.3
0.005
0.001
' <0. 03
0.03
0.001


>10
<0.0003

0.02
0.3
<0.01
<0.01
Leachate (mg/)
RS-
CAFB 10A
Gasif. Bed
<0.01
0.05
0.003
0.8
<1.0
<0.01
<0.01
Major
<0.01
<0.05
<0.05
<0.05
<0.1
<0.001
<1.0
<0.05
0.1
r~<5.o
<0.05
<0.05
<0.05
0.003
5.0
<0. 05
>5.0
<0.05
<0.05
<1.0
<0. 1
RS-
CAFB-10
Gasif. Fly Ash
<0.01
0.05
0.003
0.5
<1.0
<0.01
<0.01
Major
<0.01
<0.05
<0.05
<0.05
<0.1
<0.001
<1.0
<0.05
0.1
>5.0
<0.05
<0.05
<0.05
<0.003
5.0
<0.05
>5.0
<0.05
<0.05
<1.0
<0. 1

. j. unriKiny
Water Standards.
mg/f
0.05

0.05

1.0
1.0


0.01

0.05
1.0
0.3
0.002

0.05


2.0
0.05

0.01

1.0



5.0

                          A3

-------
                                Table 14
                        CAFB-11 OPERATING CONDITIONS
Average Coal Feed Rate
Average Line Feed Rate
Air to Gasifier
Air to Regenerator
Temp, in Regenerator
Regenerator Bed Depth
Gasifier Bed Depth
Regenerator Drain
211 kg (465 lb)/hr
10.4 kg  (23 lb)/hr              Measured
3682-4184 dm3  (130-170 df)/min
595-736 dm3 (21-26 cf)/min
Set at 1055C                      by
61-127 cm (24-50 in)
56-61 cm (22-24 in)
             3
Set at 113 dm  (4 cf)/hr          ERCA
Regenerator SO-
Regenerator C02
Regenerator 00
         0-1.2%
         5-17%
         0.2-5%
Measured
   by
  ERCA
Stack SO,
173 ppm - GCA
260 ppm - Avg. for day
          by ERCA
                                  44

-------
          The residue from the main cyclone consisted of finer
granular sorbent particles, ash, and carbon.   The ash content (Si, Al)
in the CAFB-11 cyclone carry-overs was much higher than the cyclone ash
from the oil gasification runs.  Figure 11 shows SEM and EDAX of the
main cyclone and stack cyclone fines.  Unlike the main cyclone ash, the
stack fines from the Texas lignite run consisted of mixtures of sorbent
fines and cenospheres.  The latter were not seen in the oil gasification
residues.  The SEM and EDAX of these are shown again in Figure 12, where
chemical and physical characteristics are correlated for various
particles.   In general,  the spent sorbent fines are of irregular shape
and are predominantly calcium.  The very bright, nonspherical particles
are SiCL (quartz).  The  cenospheres were high in silicon and aluminum.
          The chemical compositions and leaching properties of CAFB-11
residues were determined.  The results are shown in Tables 15 and 16.
The following points are worth noting:
       The gasifier and the regenerator materials appear to be
        similar not only in physical characteristics but also in
        chemical composition.   Therefore, leaching tests were
        carried out only on the regenerator material.
       The carry-over materials contained a much smaller amount
        of sorbent fines than did the carry-over from the oil
        gasification runs.  Thus, calcium and TDS were also lower
        in the leachate  of CAFB-11 carry-over.
       Sulfur content (both S  and SO, ) was low in the residues
        from the lignite run,  due to the low sulfur content in
        Texas lignite.
       Trace elements were more concentrated in the carry-over
        and were highest in the stack fines (B, Ba, Ci, Cu, Mu, Mo,
        Ni, Pb, Sr, Ti,  Zr).
     o  Leachate from CAFB-11 bed material was similar to the
        leachate from the oil gasification residues except for
        the lower S  and SO, concentrations in the former.
                           4
                                   45

-------
                                                               Main Cyclone
                                                               Stack Cyclone


                                         Figure  11 - SEM and EDAX of Stack  Cyclone Fines  from
                                                      CAFB "Lignite" Run Material
VJ
VJ

w

-------
                                  Al &  (4.    ft
    wv   c*
                                   Al Si  K (j T.
SEM and  EDAX of Stack  Cyclone Fines
from CAFB  "Lignite"  Run
                                                       RM-77933

-------
                                                     Table 15



                                    SOLID AND LEACHATE CHARACTERISTICS OF SPENT

                                         MATERIAL FROM CAFB "LIGNITE" RUN

Gasifier Bed
Regenerator Bed
Main Cyclone
Stack Cyclone
Solid, wt %
Ca
49.6
52.1
6.4
8.7
Mg
0.8
0.3
0.5
1.3
S
0.22
0.1
0.2
0.13
so4
0.1
0.97
0.2
2.7
Leachate, mg/S.
PH

11.7
11.7
11.1
11.4
10.3
10.9
^ * v> m 9
y mhos /cm

7690
8250
1330
2400
1150
1310
Ca

812
888
152
204
240
232
Mg

<10
<10
<10
<10
<10
<10
S

37
100
38
56

so4

206
200
77
38
544
343


Aerobic
Anaerobic
Aerobic
Anaerobic
Aerobic
Anaerobic
-p-
oo

-------
                                  Table  16
                                                                               Dwg. 2618C99
             CHEMICAL  CHARACTERISTICS  OF  CAFB  "LIGNITE"
                      RUN  RESIDUES AND LEACHATES
Substance
L Al
L Ag_
As
B
Ba
Be
Bi
Ca
Cd
Co
Cr
Cu
, 	 Fe
l~~ Hq
Mg
Mn
Mo
Na
Ni
Pb
Sb
Se
Si
Sn
Sr
Ti
V
Zn
Zr
so.
S =
so.
F
Cl
Br
NO,
N031000
>1000

100

0.1%
0.97%





"1000
300

1000

0.2%
0.13%





~T7%"


(3)
Major
<1

1000
1000
<1
<1
8.7%
<3
<10
100
10
Major

1.3%
1000
10
1000
30
50
<50

Major
<10
>1000
1000
1000

1000

0.13%
2.7%






-3%


(b)
Leachate, mg/t
IDAe
<1
<0.01
<0.05
2
<1
<0.01
<0.01
w/,mm.
<0.01
<0.04
<0.03
<1
<0.2
< 0.002
<10
<0.01
0.06
2
<0.03
<0.03
<0.1
<0.01
0.6
<0.1
>1
<0.1
<0.05
<4
<1
<10
37
206
1.6
11
<1
<1
<1
< 1

<20
% ii.7^
I7690!i
ID An
<1
<0.01
<0.05
2
<1
<0.01
<0.01
Y///.mm
<0.01
<0.04
<0.03
<1
<0.2
< 0.002
<10 j
<0.01
<0.06
2
<0.03
<0.03
<0.1
<0.01
1
<0.1
>1
<0.1
<0.05
<4
<1
<10
100
200
1.9
12
<1
<1
2
<1

<20 ,
'% 11.7^
^8250 %
(2) Ae
>1
<0.01
<0.05
1
 <1
<0.01
<0.01
'////Art*///.
<0.01
<0.04
<0.03
<1
^ \'%%
< 0.002
<10
<0.01
0.2
>1
<0.03
<0.03
<0.1
<0.01
>1
<0.1
>1
<0.1
<0.02
<4
<1
<10
38
77
2^7.9'^
11
<1
<1
a
<1 n

<20
^ 11.1^
i133f
(2)An
>1
<0.01
<0.05
1
<1
<0.01
<0.01
'//A 204 W.
<0.01
<0.04
<0.03
<1
<0.2
< 0.002
<10
<0.01
0.06
>1
<.0.03
<0.03
<0.1
<0.01
>1
<0.1
>1
<0.1
<0.05
<4
<1
<10
56
38
^8.4^
13
<1
<1
T75~
<1

<20
ifTi
2400P
(3IAe
<1
<0.01
<0.05
1
<1
<0.01
<0.01
Y///wW,
<0.01
<0.04
<0.03
<1
y/-,> \'tff/
< 0.002
<10
<0.01
0.3
>1
<0.03
<0.03
<0.1

>1
<0.1
>1
<0.1
<0.09
<4
<1
<10

'm.^m
2.4
23
1.8
20
7
<1

<20
^1U.3^
iliw^
(3)An
<1
<0.01
<0.05
1
<1
<0,01
<0.01
^232-^
<0.01
<0.04
<0.03
<1
<0.2
< 0.002
<10
<0.01
<0.05
1
<0.03
<0.03
<0.1
rm^m
>i
<0.1
>1
<0.1
<0.05
<4
<1
<10

WiVAW,
W/,i.r////
72
<1
22
12
<1

<20
^.'0.9/^
Si3ioi
let
DWS, mg//


0.05
0.05

1.0


200
0.01

0.05
IJO
0.3
0.002
150
0.05


2.0
0.05

0.01

1.0



5.0



250
2.4
250


10


5 to 9. 0
-750
(a)  (II   Regenerator Bed Material
    (2)   Main Cyclone Material
    (3)   Stack Cyclone Material

-------
         The  anaerobic  leachate  contained higher  Ca,  S  ,  and  TDS,
         in general, than did  the aerobic.
         DWS  were met by the bed leachate but  exceeded  (Fe, F,  Se)
         by the  leachate from  the carry-over.   Leachate  from  TUCCO
         ash  (a  Texas lignite  ash from  a conventional boiler) also
         exceeded the DWS for  Cr and  Se, as will  be discussed in a
         later section.
         Like the oil gasification residue, Ca, SO^,  pH,  and  TDS
         were major concerns for the  leachate.
          Note  that CAFB-11 was the  only residue from  the  Texas lignite
 test  at  the  time of this work.  The  residues,  thus,  may  not  be repre-
 sentative because of the unstable conditions  existing  during at least
 part  of  the  test duration.
          The heat-release property  of CAFB-11 summarized  in Table  17
 falls within the range found  for the residues  from the  oil run, which
 will  be  discussed in a later  section.
 Processed Residue
 Dry Sulfation
          The dry sulfation (DS) scheme is designed  to sulfate the  spent
 regenerator  material (CaO, CaS) with the S0?  from the regenerator
  ff      3,9,12
 off-gas. ' '
          Four  samples that were sulfated to various degrees were investi-
 gated in this category.  Table 18 summarizes the samples and their sul-
 fate and sulfide contents.   The leachate characteristics were  determined
as functions of stone load and mixing  time.  Figures 13 and 14 present
leaching results of the DS mix and compare them with CAFB-7 regenerator
stone before sulfation.  Since the sulfated product is largely CaSO,,
leaching results of a natural gypsum (Iowa Gypsum No. 114) are also
presented for comparison.   From Figures 13 and 14 one could make the
following points:
       Sulfide in  the  leachate was  drastically reduced by the dry-
        sulfation  processing of the  CAFB regenerator .stone.
                                   50

-------
                                    Table  17
                     RESIDUAL ACTIVITY  OF SPENT CAFB "LIGNITE"
                           RUN MATERIAL BY HEAT-RELEASE
Sample Source
Gasifier Bed
Regenerator Bed
Main Cyclone
Stack Cyclone
Max. Tern
3p/20 m
20C (10 min)
17.5C (10 min)
1.3C (3 min)
<0.2C
D. Rise
8g/2 m
163C (3 min)
133C (3 min)
16C (10 min)
<0.2C
                                Table 18

              SULFUR CONTENTS IN CAFB-9 SPENT SORBENT AND
                  DRY-SULFATED CAFB-9 SPENT SORBENT
Spent Sorbents
Processing History
Sulfate,
wt %
Sulfide,
wt %
CAFB-9
CAFB-903
CAFB-904
CAFB-904
(125-177 urn
fraction)
Actual spent sorbent from
the regenerator bed of
ERCA's pilot plant

^50 m % sulfated CAFB-9
in the 10-cm fluidized-
bed laboratory unit

79 m % sulfated CAFB-9
(44 to 420 um)

94 m % sulfated CAFB-9
(125 to 177 um)
 3.07
40.2
2.24
                                                                0.59
65.2
68.8
0.16
0.1
                                    51

-------
 e   1000
 oo
 en
 CL
 CD
 O
 c.
 rrj
     8000
   -!
-5 'E 6000
 V
o  400
5 1.2000
                  50       100       150
                       Mixing Time, hrs
                                            200
Figure 13  -  Leachate Characteristics as Functions of
             Batch Mixing Time for:
                o  CAFB Regenerator Stone No.  7
                A  76 m% CAFB-7 - DS mix
                Q  Iowa Gypsum No. 114
                          52

-------
                                     Curve 680706-B
 CD
 13
 oo
 00
 CJ

12
10
8
A
1 1 1 1

 
 
1 1 1 1
I
     8000

0    4000
   E 6000
o  V
   U-l
   o

g  12000
Q_
GO
                 50       100       150
                    Stone Loading, g/
                                            200
 Figure 14 - Leachate Characteristics as a Function
             of  Stone Loading for:
                 o   CAFB Regenerator No.  7
                 A   76 m% CAFB-7  -  DS mix
                 Q   Iowa Gypsum No.  114
                           53

-------
        Sulfate  concentrations  in  both  the  CAFB  regenerator  stone
         and  the  sulfated  DS mix exceeded the DWS  (25C mg/).
         Leachates  from a  natural gypsum, however,  contained
         similarly  high dissolved sulfate, which was consistent
         with the saturated CaSO, solution.
        Gypsum leachates  had lower pH,  calcium, and total
         dissolved  ions than did the 76  m %  CAFB spent stone.
           Spent  sorbent CAFB-9  was sulfated to various degrees  (CAFB-903,
CAFB-904).   The  sulfated  CAFB-904 was further sieved to separate the
fraction of  smaller particle size  (125-177  pm which achieved a  94 m %
           3  9 12
sulfation.  '  '     Leaching tests were conducted  separately on these
differently  sulfated spent sorbents.  A general trend was noted -
leachate calcium,  sulfide, IDS, and pH  decreased with an increasing
degree of  sulfation.  Figure 15 compares leachate  sulfide for aerobic
and anaerobic cases and shows that sulfide  concentration was much less
under aerobic conditions.  It also shows that the  sulfide in the leachate
was significantly  reduced by the degree of  sulfation.  Similar plots are
shown in Figure 16 for specific conductance which  are a good approximation
                     _i
for TDS:  1.5 ymhos-cm   is approximately equivalent to 1000 mg/.  IDS
are lower  under aerobic leaching and decrease with increasing sulfation.
Leachate pH  is high for unsulfated and partially sulfated spent sorbent
but falls within the water quality criteria range  for the 94 m % sulfated
sample.  Trace metal contents were also determined and indicated little of
concern.
           In summary, the leaching results of the  sulfated spent sorbent
demonstrated that the leachate quality is significantly improved by
"dry sulfation" processing of the spent sorbents from the CAFB gasifi-
cation process so that the potential water pollution would be greatly
reduced.
Dead-Burning
          Processing by dead-burning aims to deactivate the CaO activity
by high-temperature sintering.
                                  54

-------
                                                                                                                            Curve 682331-A
              2000
              1500
 CAFB-9, Unsulfaled. Anaerobic
o CAFB-9, Unsulfated, Aerobic
  50m%Sulfated, Anaer.
  50 m% Sulfated, Aer.
  79m%Sulfated. Anaer.
0 79m%Sulfated, Aer.
  94 m% Sulfated, Anaer.
           r  1000
           c
           o
Ln
                                100             200
                                  Mixing time, hour
         Figure  15 - Comparison of Dissolved buiride
                       in  Leachates of  Sulfated and
                       Unsulfated CAFB-9 Spent Sorbent
                 300
                 CAFB-9, Unsulfated, Anaerobic
               o  CAFB-9, Unsulfated, Aerobic
                 50m% Sulfated. Anaerobic
               n  50 m% Sulfated. Aerobic
               +  79m% Sulfated, Anaerobic
               0  79m% Sulfated. Aerobic
               *  94m% Sulfated, Anaerobic
               ^  94m% Sulfated, Aerobic
                       100                200
                         Mixing time, hour

Figure 16  - Comparison  of Specific Con-
              ductance  of Leachates of
              Sulfated  and Unsulfated
              CAFB-9 Spent Sorbent

-------
          Leaching studies were carried out on numerous dead-burned
                                                            3 9 12
CAFB-9 spent sorbent from the CAFB gasification pilot plant. ' '
Table 19 summarizes some of these dead-burned samples and compares their
chemical compositions, especially sulfide and sulfate contents, with
the original spent sorbent before dead-burning.  Two points should be
made:  the dead-burning process reduced the sulfide content to negligible
levels, and dead-burning at 1250C increased the sulfate content  in the
stone and at 1550C decreased the sulfate content.  These are clear in
the light of the CaS oxidation at 1250C and CaSO, decomposition at 1550C.
Table 20 summarizes the leachate characteristics of these samples.  The
stones sintered at temperatures equal to or above 1250C contained CaS
sufficiently low that no measurable sulfide was found in their leachates.
Leachates from stones sintered at 1550C contained no detectable  sulfide
and also had a sulfate level below the DWS.
          Although the leachate sulfide and sulfate were reduced  by
dead-burning processing, the pH, calcium,  and TDS were not  satisfactorily
improved because of the formation of Ca(OH)2.
          Another observation worth noting is that the dead-burned samples
before leaching were grey, lumpy solids whose darkness increased  with the
degree of sintering.  The solids after leaching, however, were signifi-
cantly swollen, ranging from an off-white  fluffy mass to a  pure white,
crystalline powder in the reverse order -  in other words, the whitest
powder was the leached sample sintered at  the highest temperature for
the longest time.  One possible explanation may be that the hydration
and carbonation rates are decelerated by the degree of sintering; there-
fore, the whiter, more crystalline products were formed by  the slower
reaction during leaching of the more dead-burned spent sorbents.
          The residual solids after leaching were determined by X-ray
diffraction, TGA, and wet-chemical methods to consist of Ca(OH)?  and
CaCO- as major species.   Figure 17 shows TG curves of some processed
CAFB-9 spent stones.   The top two curves show thermodecomposition of
the residual solid after 200-hr aerobic leaching of dry-sulfation
samples.   A small amount of CaCO~ is seen to decompose at point c for

                                  56

-------
                      Table 19

COMPARISON OF CHEMICAL COMPOSITIONS OF CAFB-9 SPENT
        SORBENT BEFORE AND AFTER DEAD-BURNING
Initial CAFB
Particle Size,
urn
Sintering
Temperature, C
Chemical Composition, wt %,
before Leaching
Sintering
Time, hr
S
S04
0 to 44
0 to 44
0 to 44
0 to 44
0 to 44
0 to 44
63 to 88
63 to 88
63 to 88
63 to 88
63 to 88
63 to 88
CAFB-9
0-3000
1250
1250
1250
1550
1550
1550
1250
1250
1250
1550
1550
1550
Spent sorbent
before dead-burni
2
5
24
2
5
24
2
5
24
2
5
24
ng
0.0006
0.0004
0.009
0
0
0
0.0428
0.0216
0
0.006
0.0186
0
2.24
7.08
8.64
8.52
0.48
0.6
0.48
7.296
7.368
6.552
0.96
1.032
0.984
3.07
                         57

-------
                                                    Table 20




                              LEACHATE CHARACTERISTICS OF DEAD-BURNED CAFB-9 STONES
Dead-Burning
Conditions
0 to 44 un, 1250C, 2 hr
0 to 44 urn, 1250C, 5 hr
0 to 44 pm, 1250C, 24 hr
0 to 44 pm, 1550C, 2 hr
9 to 44 um, 1550C, 5 hr
0 to 44 um, 1550C, 24 hr
63 to 83 um, 1250C, 2 hr
63 to 88 urn, 1250C, 5 hr
63 to 88 um, 1250C, 24 hr
63 to 88 ym, 1550C, 2 hr
63 to 88 urn, 1550C, 5 hr
63 to 83 um, 1550C, 24 hr

Leaching Conditions
2 g/100 ml/430 hr/aerobic
4 g/100 ml/430 hr/aerobic
4 g/100 ml/430 hr/aerobir
4 g/100 ml/430 hr/aerobic
2 g/100 ml/430 hr/aerobic
4 g/100 ml/430 hr, aerobic
4 g/100 ml/430 hr/aerobic
4 g/100 ml/430 hr/aerobic
4 g/100 ml/430 hr/aerobic
2 g/100 ml/430 hr/aerobic
2 g/100 ml/430 hr/aerobic
4 g/100 ml/430 hr/aerobic
Leachate Characteristics, mg/1)
pH
12.5
12.5
12.5
12.6
12.6
12.6
12.4
12.4
12.4
12.5
12.5
12.6
Sp. Cond.
(umhos/cm)
8010
7870
3290
8240
7590
7590
8520
8340
8340
7630
7940
7940
Ca
988
1362
1388
1274
360
840
1380
1322
1320
828
844
846
Mg
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
S
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
<5
so4=
1042
1481
1486
1214
134
163
1560
1229
1428
132
113
82
00

-------
                                           Curve 682724-A
20
18  -
16
14
12
                          **.     "*"*               Q
10
 8
           I     !    I
        Dry-sulfation sample 904, 125 to \77\im
        fraction after 200 hr aerobic  leaching
        Dry-sulfation sample 904 composite after
        200 hr aerobic leaching
        Dead-burned 171-1 after 200  hr aerobic
        leaching
-	Dead-burned 170-1 before leaching

 	Dead-burned 164-1 before leaching
                                j	L
                                             I    i
   0      200      400     600     800
                       Temperature, C
                                       1000    1200
Figure 17  - Thermogravimetric Curve of Processed Spent Stones
                           59

-------
 sample 904  composite,  and the major component,  CaSO,,  begins  to decom-
 pose at point  d.   Dead-burned sample 171-1 (1550C,  24 hr)  after
 200  hours of aerobic leaching is shown to consist  of a small  amount  of
 surface water  at  point  a, major CaCOH)^  at b, CaCO~  at c,  and some CaSO,
 starting to decompose  at  point d.   Dead-burned  sample  170-1 (1550C,
 5 hr)  before leaching  is  shown to  contain some  Ca(OH>2,  and dead-burned
 sample 164-1 (1070C,  5 hr)  before leaching contains both  Ca(OH)2 and
 CaCO_, indicating that  hydration and carbonation take  place in air
 even with dead-burned  spent  stone.   This finding illustrates  the point
 that the dead-burning  process up to 1550 C and  24  hours  does  not perma-
 nently deactivate the  stone  but merely slows down  the  hydration rate so
 that no immediate heat  release is  detected on contact  with  water.
          No gaseous H?S  was  detected  (<1  ppm)  during  leaching.  The
 aerobic leachate  contains slightly  less  calcium, sulfate, and  TDS than
 the  anaerobic  leachate.   Trace metal ions  in leachate  would be  no
 problem.
          ERCA conducted  "weathering"  tests of  the sintered spent
 stone  by exposing the residue to outdoor conditions.     Table 21 compares
 the  environmental impact  projected  by  Westinghouse and ERCA.
 Room-Temperature  Ash Blending
          Solid compacts  can  be  formed by  blending the spent  CAFB stone
                                                   3  9  12
with fly ash and  casting  them at room  temperature. ' '
          Nine solid compacts  prepared from three proportions of spent
sorbent  and fly ash  mixtures  and cured in water for  three lengths of
 time were investigated  for their leaching behavior.  Table 22 summarizes
            3  9 12
 the  results. ' '     Two methods  of  leaching were adopted.   In  the first,
the solid compact was ground to powder, and the standard shaking
was then applied.  In the second, a chunk of the compact was broken off
and then immersed in a flask of deionized water.  The mixture that had
the same solid-to-water ratio as the powder/water mixture was kept
                                   60

-------
                                            Table 21

                   ENVIRONMENTAL IMPACT OF SINTERED (DEAD-BURNED) SPENT SORBENT
                          WJ Laboratory-Scale Test
                                                  ERCA Weathering Test
Heat Release
Ca(OH)2/CaC03
Formation
Sintering Temp.
Trace Metal
Elements

Major Concern
Long-Term
Weathering
   Nonsintered stone,  T  /2Q  - = 18C

   Sintered stone  T0 /ori  , < 0.2C
                    3g/20 ml

   Hydration of sintered CaO followed by
   carbonation takes place during
   leaching (because sintered stone is
   not truly dead-burned)

   Sintering at 1250C converts CaS to
                      Sintering at 1550C decomposes
                      to CaO
                      Leachate of 1250C sintered stone
                      contains high 864
                      Leachate of 1550C sintered stone
                      contains little
  Meet drinking water standards
   High pH, TDS, Ca in leachate
  Environmentally stable CaCOo will
   eventually be formed
   Nonsintered  T = 30C (1st hr)

   Sintered  T = 5C (20 hr)

   All sintered CaO converts to
   Ca(OH)2 in 2 mos;  50% Ca(OH)2
   converts to CaCO- in 12 mos.
   weathering

   Sulfide/sulfate content unclear
                                               Sintering temp. 1350-1550C
                                               had no effect on weathering
                                               (804 in leachate not measured)
   Not monitored extensively
  High pH, Ca in leachate (TDS
   not determined)

  CaC03 increases with weathering;
   Ca(OH)2 decreases after peaking
   at 2 mos.

-------
                         Table  22
                                                                       Owg.  1704B3''
LEACHATE CHARACTERISTICS  OF ROOM-TEMPERATURE PROCESSED SOLID
       COMPACTS OF CAFB-9 REGENERATOR STONE AND FLY ASH
^^Du ration
Sample ^\
4A - 7 days
4A - 7 days
4A - 14 days
4A - 14 days
4A - 28 days
4A - 28 days
4B - 7 days
4B - 7 days
4B-14days
4B-14days
4B-28days
4B-28days
Leaching Conditions
Solid Form
Chunk
Crushed powder
Chunk
Powder
Chunk
Powder
Chunk
Powder
Chunk
Powder
Chunk
Powder
Shaking
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Solid/Water
10 g/lOOm 1/256 hr
aerobic
10 g/lOOm 1/256 hr
aerobic
10 g/100 m 1/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 m 1/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 m 1/256 hr
Leachate Characteristics, mg/1 ^
PH
12.5
12.6
12.4
12.4
12,3
12.4
12.5
12.5
12.4
12.4
12.3
12.4
Sp.Cond..
umhos/ctn
8090
8440
8440
8540
8000
8400
8770
8810
8730
8700
8290
8740
Ca
1360
1488
1380
1440
1296
1360
1600
1680
1456
1488
1336
1464
Mg
0
0
0
0
0
0
0
0
0
0
0
0
S
<0.1
<0.1
0
0
0
0
<0.1
0.1
0
0
0
0
54
1613
1987
1752
1920
1766
1814
2189
2438
1872
1968
1752
1944

-------
Table  22 (Cont)
                                       Dwg. 1704B35
^x^ Duration
Sample ^\
4C - 7 days
4C - 7 days
4C- 14 days
4C- 14 days
4C- 28 days
4C- 28 days
Leaching Conditions
Solid Form
Chunk
Powder
Chunk
Powder
Chunk
Powder
Shaking
No
Yes
NO
Yes
No
Yes
Solid/Water
10 g/100 ml/256 hr
aerobic
10 g/100 m 1/256 hr
aerobic
10 g/100 ml/256 hr
aerobic
10 g/100 m 1/256 hr
aerobic
10 g/100 m 1/256 hr
aerobic
10 g/100 m 1/256 hr
Leachate Characteristics, mg/1
PH
12.6
12.5
12 .3
12.4
12.4
12.4
Sp.Cond..
p mhos/cm
7970
8070
7770
8350
8320
8250
Ca
1328
1440
1208
1404
1328
1296
Mg
0
0
0
0
0
0
S
<0.1
<0.1
0
0
0
0
S4
1680
1877
1584
1920
1512
1632

-------
without shaking for the same leaching time and its filtrate analyzed
for leachate qualities.  Examination of the results summarized in
Table 22 reveals:
       Leaching for 256 hours using either one of the above methods
        produced leachates of similar quality, indicating that the
        solid compacts were permeable to water.  The equilibrium
        state was reached for both mixtures.
       All nine samples (of three mixtures and three curing times)
        produced similar leachates, further indicating that a
        leachate saturation had been reached.
       Sulfide was low in all the solid blends studied and was
        undetectable in their leachates.
       All leachates were high in pH, calcium, sulfate, and IDS.
       Trace metal leachability  is not expected to  cause water
        contamination.
           It appears  that  the  leachates produced from  these solid com-
pacts are  not as desirable as  the leachates from either  the sulfated
sorbents,  which had lower  pH,  calcium, and TDS, or the dead-burned
stones, which had  lower  calcium and sulfate dissolution.  It would be
premature, however, to judge the  potential usefulness of this utilization
processing method  based  on the above results, which were obtained at the
initial developmental  stage.
High-Temperature Compacting
           CAFB residue can also be processed by isostatic pressing at
                 3 9  12
high temperature.  ' '    Solid compacts of high-temperature processed
CaSO, and  CAFB spent sorbents with fly ash were studied  for their
permeability and leaching behavior.  Table 23 summarizes the sample
preparation and resultant compositions as determined by X-ray diffraction.
Obviously, the solid reaction took place during hot pressing; the major
species present in 75-CF-26 and 75-CF-30 were Ca2Al2Si07 and CaAl?Si?0R,
which are  the reaction products between the spent sorbent and fly ash.
                                   64

-------
                               Table 23.
            PREPARATION AND COMPOSITIONS OF HIGH-TEMPERATURE
                       PROCESSED SOLID COMPACTS
Samples
Sample Description
    X-Ray
Identification
75-CF-22     80% CaS + 20% coal fly ash, ball-
             milled for 2 hr, sieved to -120 mesh
             and hot pressed at 1050C, 33096 kPa
             (4800 psi) for 1 hr
             d = 2.550 g/cm3
             Dark, hard, dense cylinder
             Smells of HS

75-CF-26     50% CaSO^ + 50% coal fly ash, pre-
             pared under same conditions as above,
             d = 2.350 g/cm^
             Dark, hard dense cylinder
             No smell

75-CF-30     20% CAFB-9 spent sorbent + 80% coal
             ash, prepared under similar con-
             ditions as above.
             d = 2.460 g/cm3
             Dark, hard, dense cylinder
             No smell
                                 Major CaS
                                 Major Ca2Al2Si07

                                 Minor CaAl0SiO,
                                       sio22   6


                                 Major Ca2Al2Si07

                                       CaAl0Si00QFe
                                           2.  i. o
                                 Minor CaAl0SiO,Si00
                                           L   D   2.
          Preliminary testing indicated a very low permeability
                               8
coefficient, in the order of 10   cm/s.  Leachate characteristics are

presented in Table 24.  A significant difference was found between the

leachates induced by the two procedures:  static contact of water with

cylindrical samples versus shaking of crushed powder in water, with the

former resembling the more realistic landfill situation and the latter

representing the worst possible case.  This result further indicates low

sample permeability.  Of these three samples, the leachability of 75-CF-30

is of primary interest because it is made of CAFB spent sorbent.  The

leachate of this sample is low in TDS, calcium, sulfate, and sulfide,

passing the DWS even when induced by the shake (crushed sample) method.
                                   65

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                                                  Table  24

                           LEACHATE  CHARACTERISTICS OF  HIGH-TEMPERATURE SOLID
                                      COMPACTS OF SORBENT/ASH MIXTURE
Sample
Sample
Conditions
Leaching
Procedure*
Solid/HaO
Ratio
Leach ing
Time, hr
Leac.hate Characteristics
PH
Sp. Cond. ,
pmhos-cm
Ca,
mg/ 1.
Mg,
mg/ i
mg/;
*Procedure A:  Solid-water mixtures are agitated in Erlenmeyer flasks by an automatic shaker; mixtures are
              filtered for leachate analysis.
*Procedure B:  The cylindrical  sample is mounted at  the  bottom of a glass tube  with only the top surface
              in contact with  water.  No agitation  is applied.  As the samples are practically impermeable,
              leachates are poured out for analysis.
                                                                                                          111S/ v'
75-CF-22
"
75-CF-26
11
75-CF-30
"
Crushed powder
Cylindrical sample
Crushed powder
Cylindrical sample
Crushed powder
Cylindrical sample
A
B
A
B
A
B
1:10
1:10
1 :10
1 : 10
1:10
1:10
210
210
210
210
210
210
11.35
9.96
8.02
9.63
8 . 35
9.28
14700
410
950
290
520
90
4964
64
108
'10
72
<10
19
<10
0
<10
24
<10
1925
30
61
<20
34
< 5
6528
152
389
90
233
22

-------
         In summary, the high-temperature processed solid compacts of
spent sorbent and fly ash are more stable on contact with water  than  are
the spent sorbent and fly ash separately, due to the formation of the
insoluble cementlike calcium-aluminate-silicate compounds.  Leaching
results indicated satisfactory leachates with reduced pH, TDS, calcium,
sulfide, and sulfate concentration.  Trace elements also pass DWS. The
potential application of this processing method, however, would  also
depend on the results of economic analysis.
 Slurry Carbonation
         Slurry carbonation is a processing method whereby the spent
                                                                   3
sorbent is carbonated with CO to form practicably insoluble CaCO_.
On the basis of the results obtained, few environmental problems are
expected:
        Of the total spent sorbent, 96 to 97 percent can be
        converted to practically insoluble and environmentally
        stable CaCO~, whose leachate is expected not to cause
        water contamination.
        CaS in the spent sorbent is converted to H~S during the
        slurry carbonation reaction; it is recycled to the gasifier
        and sent to the S-recovery system.  No or low sulfide in
        the leachate is expected.
        Since the heat of hydration of CaO is released during the
        slurry carbonation reaction (which is utilized as a heat
        source), disposal of the carbonated sorbent will not
        cause heat pollution.
        Leachability of trace metal elements is expected to be
        similar to that of the unprocessed spent sorbent, which
        has been shown not to be of environmental concern.
                                   67

-------
Reference Material
TUGCO Ash
                                                      31
          Characterization of the coal ash from TUGCO,"* and tests on
the environmental impact of land disposal were carried out.  The objective
was to provide references to the leaching and activity properties of the
fly ash resulting from the CAFB process utilizing Texas lignite coal as
the solid fuel.
          X-ray diffraction showed that the ash consisted of major Si02
(quartz) and minor AJ^Oo^ SiO (mullite) .   Results by wet chemistry
analysis are shown in Table 25.  Morphological investigation reveals
that the TUGCO ash is composed of cenospheres ranging from 0.1 to 40 pm
in size.  Figure 18 shows typical SEM photomicrographs of the sample and
EDAX spectra of four cenospheres of different diameters.  Note that
silicon and aluminum are the major elements present in all four sites
scanned and that the minor elements (calcium, potassium, iron, magnesium,
and titanium) vary among particles.
                                Table 25
                          ANALYSIS OF TUGCO ASH
               Substance
                 s.o2
                 A123
                 CaO
                 MgO
                 so3
                 P
                 F
                 Cl
                 Others
Wt %
60.4
19.3
 2.54
 9.36
 2.27
 0.05
 0.029
 0.016
<0.001
 6.03
                                   68

-------
          (a)
                                                  (b)
          (c)
(d)
          (e)
Figure 18 - Typical SEM and EDAX of TUGCO Ash;  (a) and  (b),
            SEM;  (c),  (d), (e), and (f),  EDAX Spectra
            Scanned on Sites 1, 2, 3,  and 4,  Respectively
                              69
                                                                       RM-73t.

-------
          Leaching studies were carried out employing both the con-
tinuous and intermittent shake procedures.  Table 26 summarizes the
results of the continuous shake test.  Figure 19 shows the results of
the intermittent leaching test.  Both tests resulted in relatively pure
leachates with lower pH, calcium, SO,, and TDS than the typical leachate
of spent sorbent or ash from the CAFB process.  The higher pH, calcium,
SO,,  and TDS from the spent CAFB solid are caused by the CaO, CaS, and
CaSO,  present in the utilized sulfur removal sorbent.  The trace metal
elements present in the TUGCO ash and its leachate are summarized in
Table 27.  Two elements, chromium and selenium, are found to exceed the
drinking water standards.
          No detectable heat-release activity was found when TUGCO ash
came into contact with water.
Valley Builder Supply Samples
          Characterization of the samples obtained from Valley Builder
      31
Supply   has been completed and the environmental impact has been
investigated to provide a reference for the disposal of processed and
utilized CAFB residue.  Table 28 lists the samples obtained and sum-
marizes the chemical compositions as determined by X-ray diffraction
and wet chemical methods.  Figures 20a and b show typical optical and
SEM microphotographs of a piece broken from the Valley Builder block.
Figures 20c and d show, respectively, the porous area A and the less
porous area B identified on 20b.  EDAX analysis shows the porous area A
is rich in silicon and aluminum, plus potassium, iron, and calcium in
decreasing order; and the less porous area B is rich in calcium, with
silicon, aluminum, potassium, and iron in decreasing concentrations.
          Standard leaching tests were carried out on a piece of Valley
Builder block, both as it is and as crushed powder.   Table 29 summarizes
the chemical characteristics of the block and its leachates and compares
the leachates with the DWS.  The leachates exceed DWS for pH although
                                   70

-------
                      Table 26

CHEMICAL CHARACTERISTICS OF LEACHATE FROM TUGCO ASH
             BY CONTINUOUS SHAKE TEST
Leach Conditions
Leachate Characteristics, mg/
PH
Spec. Cond.
(ymhos/cm)
Ca
Mg
50 g/500 ml, 200 hr 10.7 810 144 <10
10 g/100 ml, 400 hr 8.2 760 148 10
S
S4
F
Cl
<10 263 <1 <1
1U ^ No
Br
o2
t Determine
o3
P04
TOC
<1 
-------
                                           Curve 692873-B
     300
^   200
 ^   100
00     o

^   300
I1   200
3   100
       0
       Normalized Leachate Quantity, mllq of Starting Material
               6       12     18      24      30      36
                                      oo
e
o
    2.0
i  1.0
o

CT>

600
400
200
n
1 1 1 1 1
V~
_
- o 	 1 	 o o o o - d>
12
10
8
6
i i i i I
_ ^ v ^---a^^^ ^
 o
1 1
                            5                   10
                          (360)                (720)
      Total No.of 72 hr Intermittent Leach (total leach time, hr)

 Figure  19  -  Leachate  Characteristics of  TUGCO Ash
                           72

-------
                              Table 27

        TRACE METAL ELEMENTS IN TUGCO ASH AND ITS LEACHATE
Substance
Al
Ag
As
B
Be
Bi
Ca
Cd
Co
Cr
Cu
Fe
Hg
Mg
Mh
Mo
Na
Ni
Pb
Sb
Se
Si
Sn
Sr
Ti
V
Zn
Zr
TUGCO Ash Solid,
ppm
Major
< 1
12.1
500
5
< 10
Major
< 3
20
80
200
Major
0.12
> 1000
660
30
> 1000
50
85
< 33
4.0
Major
< 10
1000
< 1000
250
100

TUGCO Leachate,
ppm
> 1
< 0.01
0.006
> 1
< 0.01
< 0.01
Major
< 0.01
< 0.01
0.7a
< 1
< 0.1
< 0.001
< 1
< 0.01
0.2
% 1
< 0.05
< 0.01
< 0.05
0.05a
< 1
o n c
^ \j  O_;
> i
< i
0.5
< 1
< 1
Exceed the U.S. Drinking Water Standards for Cr (0.05 ppm)
and Se (0.01 ppm).

-------
                                                Table 28
                          CHEMICAL COMPOSITIONS OF VALLEY BUILDER SUPPLY SAMPLES

Samples

X-Ray Diffraction
Wet Chemistry
Ca
Limestone Dust 37.28
Type I Cement (Major) 54 CaO  16 SiO~  MgO  A190~ 43.68
Mg
1.0
2.4
so4
0.02
3.4
, wt %
S=
0.03
0.04

co3=
58.39
0.82
Fine Aggregate

Coarse Aggregate
Block
and/or Ca^SiOo and others in trace
amounts (Si02, CaC03, Ca(OH)2, CaSO^,
CaSO^  2H20, Ca3Mg(Si04)2, CaO, and
(Mg, Fe)2Si04)
Major SiO~ quartz and an unidentified
trace phase
Major SiO? quartz, trace CaCO,, calcite
0.96    0.19    0.22    0.1     0.71

0.8     0.19    0.83    0.08    0.52
8.0     0.19    0.21    0.05    7.55

-------
 V
   ;n

              (a)
Figure 20 - Valley Builder Supply Block:   (a)  Optical photomicrograph
            at 3X; (b) SEM at  26X;  (c) porous  area A at  1300X,  rich
            in Si, Al, plus K, Fe and  Ca  in  decreasing concentrations
            shown by EDAX; (d) less porous area B at 1300X,  rich in
            Ca, also Si, Al, K, Fe  in  decreasing concentrations.
                                  75
                                                                           RM-75208

-------
                                   Table 29
Dwg. 1694B42
CHEMICAL CHARACTERISTICS OF VALLEY BUILDER SUPPLY BLOCK AND  LEACHATE
Substance
Ag
Al
As
B
Ba
Be
Bi
Ca
Cd
Cr
Cu
Fe
Hq
Mg
Mn
Mo
Ni
Pb
Sb
Se
Si
Sn
Sr
Ti
V
Zn
Zn
Cl
F
S =
S04
TOC
pH
Sp. Cond.
li mhos/cm
Solid ,ppm
<1
Major

350
500
2
1
8.0%
<1
20
30
>1%

0.19%
100
20
20
10
<10

Major
<3
>300
>1000
150
100
500


0.05%
0.21%



Leach ate. ppm
a
<0.01
<1
<0.01
<1
<1
<0.01
<0.01
52
<0.01
0.02
<1
<0.2
< 0.002
<10
<0.01
<0.05
<0.05
<0.01
<0.2
<0.01
<0.01
<0.2
<1
<0.2
0.05
<1
<1
2.6
<1
<10
35
<5
'/MV,
270
b
<0.01
<1
<0.01
<1
<1
<0.01
<0.01
114
<0.01
0.04
<1
<0.2
< 0.002
<10
<0.01
<0.05
<0.05
<0.01
<0.2
<0.01
<0.01
<0.2
<1
<0.2
0.2
<1
<1
4.2
<1
<10
194
<5
'/#.&/,
420
Drinking Water Standards,
ppm
0.05

0.05

1.0


200
0.01
0.05
1.0
0.3
0.002
150
0.05

2.0
0.05

0.01
0.01
1.0



5.0
5.0
250
2.4

250

5.0 to 9.0
-750
           "DWS	NIPDWR, USPHS. and WHO Drinking Water Standards
            a  	leachate from a piece of uncrushed block
            b  	leachate from crushed powder
           tm	exceeds the DWS
                                       76

-------
much less than does the CAFB leachate.  One may recall that a typical
CAFB leachate (processed and unprocessed) exceeds the DWS for pH,
calcium, S04, and IDS.
          Results from the heat-release tests are summarized in Table 30.
The limestone dust and fine and coarse aggregates did not show any
temperature rise; the cement powder gave off heat on contact with
water as expected.  The block (after being crushed to powder), however,
also showed a very slow temperature rise when exposed to water.
                                Table 30
               HEAT-RELEASE PROPERTIES OF VALLEY BUILDER
                             SUPPLY SAMPLES


Samples 3
Limestone Dust <0.2
Type
Fine
Heat-Release, AT, C
g/20 ml 16 g/4 ml
C <0.2C
I Cement 2C 6C in < 1.5 min
(immediate rise)
Aggregate <0.2
Coarse Aggregate <0.2
Block
Block
C <0.2C
C <0.2C
<0.2C <0.2C
(crushed powder) <0.2C 2C slow rise over
1.5 hr
 FGD Sludge
          In the absence of  leachate  criteria with which  to  assess  the
 environmental acceptability  of  land disposal of  CAFB residue,  the
 leaching property of residues from conventional  coal-burning power  plants
 with  flue gas desulfurization scrubber  systems has been  investigated  to
 provide a reference  for the  leachate  characteristics of  residue  from  a
 currently commercialized process.
                                   77

-------
          A typical untreated FGD sludge using lime or limestone sor-
 bent contains 30 to 70 percent solid matter after settling.  The major
 constituents of the solid are CaSO  -1/2 H20,  CaSO^-2 Kfl, CaCCy coal
 ash that consists of SiO,,, Al 0  , Fe23' and  trace elements.  The exact
 composition varies, depending on many factors, including the type of
 coal, the type of scrubber system, and boiler and scrubber operating
 conditions.
          Six samples of FGD sludge from pilot- and commercial-scale S02
 scrubbing systems, including untreated, ponded, oxidized, and stabilized
 lime or limestone scrubber sludges, were tested during the investigation.
 Table 31 summarizes the sample source, scrubber system, further treatment,
 and X-ray identification of the sludges.  All sludge samples except one
 (the stabilized) were wet with supernatant liquors as received.  The
 liquors were separated by vacuum filtration and analyzed chemically.
 The dewatered sludges were then dried (^95 to 105C), and the sludge
 powders underwent the standard leaching tests developed for CAFB
 residues.
          SEM of the unprocessed sludge (Figure 21) shows the small
 platelet crystallites of CaSO -1/2 H~0 that have been reported by the
                 39-41
 FGD investigators      to be responsible for the dewatering/settling
 difficulties and the thixotropic property of the sludge.  The ponded sludge
 often has mixtures of the flaky platelets and bulkier crystals due to
 partial oxidation of sulfite to sulfate.   On the other hand, the oxidized
 TVA sludge shows large crystals of gypsum (CaSO,-2 tUO).   The potential
 environmental hazard (due to sulfite oxygen demand) has been reduced,  and
 dewatering and settling difficulties are greatly improved.   In fact,
oxidation to gypsum has been recommended as one of the methods by which
                        46
 Lo stabilize FGD sludge.     Cenospheres from coal ash are also present
 in the sludge samples and may also cause settling problems  in ponding.
 EDAX spect-ra show that the platelet crystallites of the FGD solid  are
high in calcium and sulfur (presumably CaSO,,'1/2 H~0)  and that the
 cenospheres are rich in silicon,  aluminum,  and iron (coal ash).
                                   78

-------
                                                Table  31

                                       SUMMARY OF FGD  SLUDGE SAMPLES
           Sample
   Process Description
    X-Ray Identification
 Louisville Gas  and  Electric
 Company (LGE)42
Fresh, untreated, unponded;
lime sludge with small amount
of MgO added
Major:      CaS03'l/2 H20

Low minor:  (Fe,Mg) A1204 or
            (Mg,Fe) Si04 spinel
 Columbus  Southern  Ohio  Company
 (CSO)43
Untreated lime sludge; 98% fly
ash removal
Major:
            CaS03'l/2
 Duquesne Light  Company
Untreated lime sludge; con-
taining ^50% fly ash
Major:
Minor:

Low minor:
            Si02
            CaS03'l/2

            Fe23
TVA Shawnee, Pond
Untreated, ponded limestone
sludge bottled in pond liquor
for 2.5 yr
Major:

Major:
Trace:
            CaS03'l/2

            CaCO
            SiO,,
TVA Shawnee - Oxidized
Sludge44.45
Lime sludge followed by
forced air oxidation to gypsum
Major:
Duquesne Light Company43
Stabilized Sludge
"Calcilox" stabilized lime
sludge containing ^50% fly ash;
stabilized and ponded for 3 yr
Major:


Minor:
            SiO^, amorphous
            phase

            CaCO , CaSO '1/2

-------
       SEM Photomicrographs  of Itewatered FGD Sludge
(a)
                                                    FGD  sludge (LGE)
                                                    unponded, untreated
(b)
 FGD sludge (TVA)
 ponded, untreated
(c)
FGD sludge (TVA)
oxidized, gypsum
  Figure  21 -  SEM Photomicrographs of  Dewatered FGD Sludge
                                  80
                                                                                RM-
                                                                                   73896

-------
          SEM of the stabilized sludge shows a mixture of cenospheres
and a fluffy mass that appears frequently to be clustered and to  have
adhered to the cenospheres.   The platelet crystallites are no longer
observed.  It has been reported that the compressive strength of  the
stabilized sludge increases  as a function of stabilization (solid setting)
time.
          Leaching properties were investigated using both the con-
tinuous and the intermittent shake methods described in the previous
section.  Figure 22 shows the leachate characteristics of the dried
sludge as a function of continuing leaching time.  Note that the
leachate from the stabilized FGD sludge is very similar to gypsum
leachate.  On the average the untreated sludge leachate has higher
calcium, magnesium, SO,, pH, and TDS.
          Figure 23 shows the specific onductance and approximate TDS
in the leachate from the intermittent shake test.  The better leachate
quality is seen again in the case of the stabilized sludge.  The
leachate from the untreated, ponded, and oxidized sludge had much higher
TDS  and  improved with total leaching time  and total  leachate volume.
The  lower TDS in the CSO leachate after two 72-hr leach cycles was  due
to the low solubility of calcium sulfite  (CaSO), which was  the predom-
inant specimen  in the untreated fly-ash-free  CSO sludge.  It must be
kept in mind that the leachate characteristics presented  here were  from
the  vacuum-filtered and dried sludge.  The  superheated liquors of the
sludges had much higher TDS and specific ion  concentrations, as seen
in Table 32, which summarizes the chemical  characteristics of the solid,
liquor, and leachate of the untreated, ponded, oxidized,  and stabilized
sludge samples.  One can see that the trace element concentrations  are
Lue  lowest Lot  Liie leachate from the stabilized sludge auu ue^L luwcoL
in the untreated sludge following ponding.  Although  oxidation to gypsum
increased the crystal size and improved the sludge settling  property and
shear stress,   the trace element and anion concentrations in the
oxidized sludge liquor and leachate remained  high.
                                   81

-------
                                    Curve 693172-B
      2000
      1000
   to
   o
       200

       100

        0
      3000

      2000

      1000

        0
        "
til;
" I?,
        0
                100      200     300 1      400
                Total Continuous Leach Time, hr
A LGE Untreated
v CSO Untreated
o DLC Untreated
                              O TVA Ponded
                              o TVA Oxidized
                               Calcitox-Stabilized
                      	Natural Gypsum


Figure 22 - Leachate  Characteristics of Dried FGD  Sludge
             as  a Function of Continuous Leach Time
                               82

-------
                                   Curve 695695-B



Normalized Leachate Quantity,  m/g Starting Solid


6      9      12      15      18      21      24
                                                                                                  27
                                                               30
00
                          E
                          o

                          t/>
                          o
                          .c

                          E
                          o
                          c
                          ra
                          J
                                                                        4000
                                                                                                                  3000
                                                                                                                  2000
                                                                                                                  1000
                                                                                                                       CT>
                                                      I
                                                             I
                                  I
                                    I
                                                                                           I
                                                      345678

                                                       n = Total No. of 72-hr Intermittent Leach
                                                               10
       130               360

            Total Leach Time = 72 x (n), hr


LGE Untreated        o DLC Untreated

CSO Untreated       O TVA Ponded


                  	Natural Gypsum
                                                                                      540




                                                                                   o TVA Oxidized

                                                                                    Calcilox-Stabilized
                                                         720
                                  Figure  23  - Leachate Characteristics of  Dried FGD Sludge as  a

                                                 Function of Intermittent Leaching

-------
                                         Table 32
                                                                         MIK36
       CHEMICAL CHARACTERISTICS OF FGD SLUDGE,  LIQUOR,  AND  LEACHATE*
a   Based on analysis of 6 samples tested
  Exceed Drinking Water Standards I NIPDWR. USPHS. and WHO)
                                          84

-------
          The investigation of FGD residues presented in this section
has been limited to their chemical and leaching properties.  The
physical properties of the FGD sludge have been reported in the
           45-47
literature.
Gypsum
          Granular gypsum (Iowa No. 114) was tested in parallel with
many of the CAFB leaching tests to provide a reference for natural
leachability.  Results have been reported in the previous sections.
Heat Release Property
          The activity of residual lime in spent sorbents and fly ash
was determined by its heat release property on contact with water, as
                                                      O
the hydration reaction of CaO is extremely exothermic.    Literature on
                                                                    37
lime reactivity and slaking rate has been reviewed.  The ASTMC110-76
provides a test for the slaking rate of quicklime  (CaO).   In this  test
76 g of quicklime is  added to 380 ml of distilled  water in a modified
Dewar  flask  covered with a rubber gasket fitted with a mechanical
stirrer.   The temperature is read with  a thermometer at 30-second  to
5-minute intervals, depending on the reactivity of the quicklime,  until
a  constant temperature is reached.  The slaking rate is determined by
the following quantities:  temperature  rise at 30  seconds, total
temperature  rise, and active slaking time.
                38
           Murray   studied lime reactivity as a function of  porosity
and shrinkage characteristics during calcination and found that
calcitic quicklime of low shrinkage and high porosity had  high reactivity.
He used a  limerwater  ratio of 1:7 by weight.  Since preliminary slaking
tests  indicated a wide range in slaking rates, an  empirical  compromise
poiuL  was  selected as indicative of the rapidity of slaking.  Tue
temperature  rise  in  five seconds was selected, and the  reactivity
coefficient  was designated as  AT,.; yet  he  readily  acknowledges  that
                                    85

-------
 his  test was  inequitable  for  the  extremely  reactive  limes  in which slaking
 was  actually  completed  in three to  four  seconds,  so  that a reading at
 five seconds  made  them  appear to  be slower  than they actually were.
          American Water  Works' standard on lime  for water treatment
 employs a lime  slaking  test with  lime:water proportions 100 g:400 ml,
 following the test procedure  of ASTMC110.
          The temperature rise of a solid/water system containing free
 CaO  is a function  of solid:water  ratio.   In our experimental effort to
 establish a screening test for the  residual activity in spent CAFB
 solids produced under varying processing conditions,  a solid to water
 proportion of 3 g  to 20 ml (which is in  the bulk  range specified by the
 ASTMC110 test and  by Murray's work) was  found empirically  to provide
 much better repeatability than that  from a  higher solid:water ratio which
 would give greater temperature rise but  would lack reproducibility, most
 likely because of  local heating.  The former ratio was initially adopted
 as the screening test for heat-release property because of  its speed,
 small quantity of  stone required, and the good reproducibility of results.
 The  latter, however (small quantity of water added to larger quantity
 of solid), was also used  because  it provides higher  sensitivity and
 simulates rainfall onto the disposed solid.
          Figure 24 compares  the  temperature rise as a function of
 solidrwater ratio  for a CAFB  spent sorbent  and a  calcined limestone.
 Higher temperature rise and faster response  are observed for the higher
 solid:water ratio system,  as  expected.    Figure 25 shows the temperature
 rise profile when 4 ml of water are added to 16 g of six CAFB spent
materials.   A lower solidrwater ratio is used for the calcined limestone
 for comparison due to the  calcined limestone's extremely violent heat
 release characteristics.  A variation in residue activity among different
batches of CAFB spent sorbent was noted.   Spent bed material also
displays  greater heat release property than did fly ash or stack fines.
                                    86

-------
                                                              Curve 690480-A
                            	Calcined Limestone, 15 g/20 ml
                            	Calcined Limestone, 5g/20 ml
                            	CAFB-8 Reg. Bed,  16 g/4 ml
                            	CAFB-8 Reg. Bed,  3 g/20 ml
                                     J_
                   10
   20
Time, min
30
           Figure 24 - Heat-Release Property as a Function of
                       So lid-.Water  Ratio
The heat release properties  of all the CAFB residues, processed and
unprocessed, using  the  lower solid:water ratio (3 g:20 ml) are summarized
in Table 33.  Note  the  improvement by processing.
Total Dissolved Solids
          The total  dissolved solid (IDS) in a leachate  is a good index
of leachate quality.  TDS, which can be determined by  the time-consuming
evaporating procedure,  can be estimated by multiplying the easily
measured specific conductance by an empirical factor.  This  factor may
                                      87

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                     Table 33
ACTIVITY TESTS OF PROCESSED AND UNPROCESSED CAFB SPENT
       SORBENTS BY THEIR HEAT-RELEASE PROPERTIES
Samples
CAFB - 7 Reg; Bed
CAFB - 8 Reg. Bed
CAFB - 8 Gasif. Bed
CAFB - 8 Stack Fines
CAFB - 9 Reg. Bed
CAFB - 10 A Gasif. Bed
CAFB - 11 Reg. Bed
CAFB -11 Gasif. Bed
CAFB - 11 Main Cyclone
CAFB - 11 Stack Fines
DS - Mix
CAFB -903
CAFB - 904 Composite
CAFB -904 125 -177pm
DB163
DB164
DB165
DB166
DB167
DB168
DB169
DB170
DB171
Processing History
Unprocessed CAFB residue from ERCA
M
n
M
M
n
n
n
n
ii
76 m* sulfated CAFB - 7
50 m* sulfated CAFB - 9
79 m% sulfated CAFB - 9
CAFB -904 sieved to -f 125- 177Mm. 94 m%
Dead-burned CAFB -9. 1070C. 2hr
Dead-burned CAFB -9, 1070C. 5hr
Dead-burned CAFB- 9, 1070C. 24 hr
Dead-burned CAFB- 9. 1250C. 2hr
Dead-burned CAFB -9. 1250C. 5hr
Dead-burned CAFB -9. 1250C. 24 hr
Dead-burned CAFB -9. 1550C. 2hr
Dead-burned CAFB -9. 1550C. 5hr
Dead-burned CAFB -9. 1550C. 24 hr
Solid/Water
3g/20ml
II
II
n
II
II
M
n
II
II
II
II
tl
II
ti
II
II
H
II
II
M
II
11
ATmax.C -
18
10.3
6.7
3.1
15
2
18
20
1.3
<0.2
<0.2
0.7
<0.2
<0.2
17
19
0.9
7.2
<0.2
<0.2
<0.2
<0.2
<0.2
                        88

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Table  33  (Continued)
Dwg.1704B55
Samples
D8. 0-44um
DB, 0-44um
DB, 0-44um
DB. 0-44Mm
DB, 0-44um
DB. 0-44um
DB. 63-88um
DB, 63-88um
DB. 63-88um
DB, 63-88um
DB. 63-88um
DB, 63-88um
Room-Temp. Compacts
4A - 7. 14. 28
4B - 7, 14. 28
4C - 7. 14. 28
75 - CF - 22
75 - CF - 26
75-CF-30
TUGCO Ash
Valley Builder
FGD Sludge
Gypsum
Limestone 1359
500-lOOOum
Calcined Limestone 1359
500-lOOOum
Tymochtee Dolomite
1000-1200um
Processing History
Dead-burned CAFB -9. 1250C. 2hr
Dead-burnedCAFB-9. 1250C. 5hr
Dead-burnedCAFB-9. 1250C. 24hr
Dead-burnedCAFB-9. 1250C, 2hr
Dead-burnedCAFB-9. 1550C. 5hr
Dead-burnedCAFB-9, 1550C. 24 hr
Dead-burnedCAFB-9. 1250C. 2hr
Dead-burnedCAFB-9. 1250C.5hr
Dead-burnedCAFB-9. 1250C, 24 hr
Dead-burned CAFB- 9. 1550C. 2hr
Dead-burnedCAFB-9. 1550C. 5 hr
Dead-burned CAFB -9. 1550C. 24 hr
Room-temp, processed sorbent/ash mixtures
for 7, 14. and 28 days
M II
II II
High-temperature hot-pressed CaS/ash compacts
High-temperature hot-pressed CaSO./ash
compacts
High-temperature hot-pressed CAFB-sorbent/ash
compacts
Conventional lignite ash
Commercial aggregate
Untreated and treated
Natural, ground



Solid/Water
3g/20ml
M
ll
M
M
11
11
H
M
II
II
11
M
M
II
tl
M
II
II
II
II
ir
it
M
M
*vc
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
'0,2
<0,2
<0.2
<0.2
<0,2
<0.2
<002
<0.2
> 55
<0.2
                                         89

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                                                                                                                  Curve
vo
O
        E
        o>
	Calcined Limestone, 15 g/20 ml
	CAFB-8Reg. Bed, 16 g/4 ml
- CAFB-8Gasif. Bed, 16 g/4 ml
	CAFB-10A Gasif. Bed, 16 g/4 ml
	RS-CAFB-10A Gasif. Bed, 16 g/4 ml
	CAFB-8 Stack Fines, 16 g/4 ml
	RS-CAFB-10 Gasif. Fly Ash. 16 g/4 ml
                            10
       20
30
 40
Time, min
50
60
70
80
                            Figure  25 - Heat-Release Property of Spent Solids from  the CAFB Process

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vary, depending on the soluble components in the particular aqueous
system and the temperature of measurement.  A constant temperature, 25C,
has been selected for the latter throughout our leaching studies.  This
section summarizes our efforts in determining empirically the multiplying
factor for the CAFB leachates.
          Several spent CAFB materials (bed, ash, stack fines) were
investigated.  Leachate was induced by a 48-hr shake procedure.  A
portion of the original leachate from each sample was diluted to provide
diluted solutions of 1/2, 1/4, and 1/8 fractions of the original con-
centrations.  Specific conductance, pH, and IDS were determined  for all
16 leachate solutions.
          The procedure in determining TDS described in Standard Method
for Water and Wastewater   was used to obtain TDS at evaporation tempera-
ture, 103C.  This was not the true TDS because the residue at 103C
contained physically occluded water, hydration and carbonation products,
Ca(OH)2, CaSO,-1/2 H20, CaSO,-2 H20, and CaCO., among other dissolved
species.  To determine the true TDS - in other words, the total weight
of solid from the spent CAFB material that is dissolved - the residue at
103C was heated to 500C to convert Ca(OH)2, CaSO^-1/2 H20, and
CaSO,, and then to 900C to convert CaCO., to CaO.  As we will show that
the  TOC in the leachate of CAFB residue  is low, volatilization and
decomposition of organic species would not be of  concern when residue
is dried at  higher temperatures.   The TDS at 900C was used in this work
because it approximated more  closely the  weight of the actual solid com-
ponents - for example, CaO and CaSO, dissolved  from  the spent CAFB materials,
          The results  presented  in Figure 26 show the relationship
between TDS  and  specific  conductance.   There is a straight  line  with  a
slope of  0.37 mg-cm-ymho~  fc~  .   Thus,  TDS in a  CAFB  leachate  (mg/Jl) can
be  approximated  by multiplying  the easily measured  specific conductance
 (in pmhos/cm) with a conversion  factor  of 0.37.
                                   91

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                                               Curve 691639-H
                      4000
                      3000
                    _
                    3
                    5 2000
                      1000
                                        Slope =0.37 mg-cm-iimho-  I
Sample 1: CAFB-10 Gasif Bed      
Sample 2: RS-CAFG-10 Gasif Fly Ash  o
Sample 3: CAFB-8 Stack Fines     Q
Sample 4: CAFB-8 Reg Bed      a
                                         J	L
                         0 1  2  3 4 5 6 7 8  9 10 11 12
                                Specific Conductance, mi Hi mhos/cm
              Figure 26 - Correlation between TDS and  Specific
                          Conductance in  CAFB Leachate System

           Note that the results  presented here are  empirical and based
on typical CAFB leachates.  TDS  obtained in this manner  are only approxi-
mated values.   Note, also,  that  a  typical CAFB leachate  has a TDS of
approximately 4000 mg/ and that  the drinking water standard for TDS is
500 mg/Jl.
Total Organic Carbon (TOC)
           Conventionally, chemical oxygen demand (COD) and  biochemical
oxygen demand  (BOD) are determined on water  and waste water streams to
provide a  measure of the organic content in  the stream,  but since both
the COD and  BOD are time-consuming procedures, total  organic carbon (TOC)
is often measured to provide a speedy and convenient  way of estimating
the degree of  organic contamination.
          We used a Model 915 Beckman TOC analyzer.   Measurements of
TOC on the CAFB residues indicated that  the  organic content in leachates
of CAFB residue was insignificant  when compared with  gypsum leachate
as a control.
                                     92

-------
Leaching Media
          In the previous sections deionized water was based in the
majority of the leaching tests except where otherwise specified.  Leach-
ing property of the CAFB residue was also investigated as a function
of leaching media.  Three media of varying pH were used.  Leaching with
CCL-saturated deionized water was carried out to simulate surface
water where dissolved C0~ may be high.  Leaching tests were also con-
ducted using a sodium acetate/acetic acid buffer solution with a
pH = 4.4 and specific conductance 3.31 umhos/cm, as suggested by
                      32
the proposed ASTM test   to simulate inhomogeneous disposal sites where
codisposal of municipal and industrial waste often results  in
acidic leaching conditions.  Table 34 summarizes the continuous leaching
results of CAFB-10A gasifier bed material using three media under
aerobic and anaerobic conditions.  Definitive conclusions cannot be
drawn on the basis of such limited data, but preliminary results do
indicate the following:
       Specific  conductance  and  pH  were decreased slightly with
        C0~-saturated media because  of the  formation  of insoluble
        CaCO  .
       The effect of an acetate  medium  on  leachate concentrations
        was more  than additive, perhaps  due to  the higher ionic
        strength  and lower pH of  the leaching medium.   Increased
        calcium and  sulfide in the acetate  leachate were such
        examples.
        Anaerobic leachate had higher sulfide  in  all  cases.
        On the whole the  leaching medium did not  play as important
        a  role as one might have  expected,  due  to the large amount
        ol spent  CaO present  in the CAFB residue.
        The final leachates were  still highly alkaline in all
        cases  (pH ^12).
           Minor and  trace species were determined  in  these  leachates.
Preliminary results, based on single-test  data, suggested  a slight
                                    93

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                              Table 34




CHEMICAL CHARACTERISTICS OF CAFB-10A LEACHATE USING DIFFERENT ELUEHT
Eluent
Deionized Water
}eionized Water
Deionized Water
Deionized Water
CO^-Saturated
Deionized H.,0
(^-Saturated
Deionized H20
COj-Saturated
Deionized H~0
CC^-Saturated
Deionized H20
Acetate Buffer
SC = 3.1 millimhos/ciT.
Acetate Buffer
SC = 3.1 millimhos/cr
Acetate Buffer
SC = 3.1 mi llimhos/cn
Acetate Buffer
SC = 3.1 mi 1 limhos/rm
Eltient
pH
7.0
7.0
7.0
7.0
4.0
4.0
4.0
4,0
4.4
4.4
4.4
4.4
Solid sS
./Eluent
s Ratio
1:10
1:10
1:10
1:10
1:10
1:10
1:10
1:10
1:10
1:10
1:10
1:10
Continuous
Shake
Time
hr
100
100
196
196
200
200
400
400
200
200
400
400
Aerobic ^^
*S"^ Anaerobic
Aerobic
Anaerobic
Aerobic
Anaerobic
Aerobic
Anaerobic
Aerobic
Anaerobic
Aerobic
Anaerobic
Aerobic
Anaerobic
Leachate Chem. Characteristics
PH
12.2
12.2
12.3
12.3
11,9
11.9
12.0
12.0
12.1
12.0
12.2
12.1
Sp. Conductance
(millimhos/cra)
11.13
11.23
11.74
3.62
9.59
9.57
9.73
9.70
14.5
14.9
14. S
19.2
Ca,
mg/i
1703
1768
1572
1472
1520
1568
1600
1572
3276
3280
3400
4SGO
S ,
rag/t
-
150
91
374
255
369
344
552
329
397
363
656
S04,
mg/'
1263
1311
1395
1139
1225
1083
1460
1325
913
1248
1060
340

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increase in lead,  selenium,  mercury,  and chlorine.   Because of sample
inhomogeneity and  variations among CAFB residues  from different run
conditions, tests  on more samples  must  be repeated.
SUMMARY
          The leachate characteristics  of unprocessed and processed CAFB
spent sorbent are  summarized in Figure  27 and compared with natural
gypsum leachate.   Note the improvement  of leachate  quality by various
processing alternatives.   This investigation, in general, resulted in
the following findings:
       Trace elements are not expected to cause environmental
        problems (unprocessed and processed).
       Negligible organic contamination was found  in the leachate
        (unprocessed and processed).
       Leaching and heat release are improved significantly by
        processing the stone.
       The leachate quality of processed spent sorbent has been
        shown to be equal to or better than natural p,ypsum
        leachate.
       Potential concerns are for
           Unprocessed:  sulfide, heat-release, Ca, SO,, IDS, and pH
           Processed:  Ca, SO,, TDS,  and pH.
          The effect of the  leaching medium on leaching property should
be investigated further.  Although TOC is low in leachates, specific
organic species have not been determined.
          Because we lack specific disposal criteria, the leachate
characteristics of the CAFB  residue are compared with liquor  and leachate
of FGD residue, a currently  commercialized process  (Table  35).  The
untreated sludge has liquor  and leachate exceeding  many of  the  DWS for
trace elements.  With very  few exceptions (two batches of  stack fines),
the  leachate of the CAFB residues meet the stringent  DWS.
                                    95

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                                       Curve 686168-B
      1500
  ^
   i1  1000
  s  500
  ^  2000
   *  1500

  |  1000
  ^  500
  ITJ
  O
2000

1500
1000
 500
12
10
g
k

2.
-


1 1 1 1
 " ~

8^ 
1 1 1 1
c
42
o
 O
O r
 .
00
10000
8000
6000
4000
2000
_ 1 ' ' 1 _
^1 	 	 o 	
^  ^^ "~ ^
~^/ * *
A ^
1 IP 1 1
                 100      200      300
                       Mixing Time, hr
                                   400
500
            Lectcliate  Characteristics as a FuucLiuu
            of Mixing Time for:

             O CAFB-9,  unprocessed
             A CAFB-904, 94 m% dry-sulfated
              Dead-burned at 1550C, 5 hr
             V Room-temp, processed compacts
             0 75-CF-30, hi-temp. processed compact
             D Natural  gypsum
                        96

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                      Table 35
                                                     Dwg. 1693872
COMPARISON OF  LEACHATE CHARACTERISTICS  FROM  THE
             CAFB AND  FGD RESIDUES*
Substance
Al
Ag
As
B
Ba
Be
Bi
Ca
Cd
Co
Cr
Cu
Fe
Hq
Mq
Mn
Mo
Na
Ni
Pb
Sb
Se
Si
Sn
Sr
Ti
V
Zn
Zr
S =
S03
soa
Cl
f
NO^as N
TOC
PH
IDS
Specific
Conductance
umhos/cm
Liquor, mqlt
FGD
Oto20
<0.05
<0.05
>5
<1
<0.02
<0.04
/V500///X
/OtoO,2'//x
<0. 1
<0.05
<1
<0.3
< 0.002
/OtoXlOOOV/
/J0to20////
0. 1 to 7. 0
0 to > 100
<1
<0.05
<0.2
/.o.'oQito'o.'5'/
Oto30
<1.0
Oto40
<2
<2
<2
<2
<20
<10to40
/"lOOOtpTpOO/
/300.to.6000 /
/ 10 to ISO'//
/OtQ,109///
<30
6to9
/5QOO,toM4pOO/
5.0 to 17.0
Leachate. mg/
CAFB
<1
<0.05
<0.05
^2
<1.0
500
T^
a'^o:o3-^/;
<20
<0.05
<1
<10
 10
<2
<1
<1
<1
/ojd.xiooo^
<10
/J00p--20(r/
<30
ra;<2;4fgr.8^
<10
<30
/12'to'l3//
/3000;to,4000
6.0 to 10.0
FGD
<1
<0.05
/O.td.O.'!//
>1
<1
<0.02
<0.04
A5QQ"//
<0.01
<0.1
<0.05
<0. 1
<0.3
< 0.002
/t).to 500//
/fito0.1/y
<1
<10
<0. 1
<0.05

-------
                        4.  ENVIRONMENTAL ASSESSMENT

          Based on the laboratory  testing results, we judged that the
 unprocessed  CAFB  spent sorbent would not be environmentally acceptable
 for  direct land disposal.  Available test data, however, show that en-
 vironmental  acceptability can be achieved by further processing.  Table
 36 summarizes  the degree of reduction of the environmental impact
 achieved by  four  of  the processing alternatives for the spent sorbent
 from the CAFB  gasification process.  The leaching tests performed are
 considered to  result  in more severe projections of environmental impact
 than will be encountered in practice.   Since there are no guidelines for
 leachate qualities at the present  time, results are compared with drinking
 water standards and  leachate characteristics of natural gypsum.
          It must be  pointed out that the drinking water standards are
 used  in this investigation only in an effort to put data into perspective
 in the absence of EPA guidelines and should not be construed as suggesting
 that  the leachate must necessarily meet drinking water standards.  Of
 course, these standards are extremely conservative; a leachate dilution/
 attenuation  factor of 10 is currently being considered in the regulation
 draft unaer  Section 3001 of the RCRA by the Hazardous Waste Management
 Division of  the Office of Solid Waste,  EPA.17
          Although,  on the basis of its leachate quality (Table 36),  the
high-temperature processed compact appears to be environmentally
 superior to  other alternatives, the energy requirements would have to be
 evaluated in relation to the benefits.   On the basis of environmental
 impact, dry-sulfation would be the recommended process, followed by dead-
 burning and  low-temperature fly ash blending.
                                     98

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                                          Table 36
                                                                                              g. 1694B48
             COMPARISON OF ENVIRONMENTAL IMPACT OF  PROCESSED  AND
                           UNPROCESSED CAFB SPENT SORBENTS
     Environmental
     .Parameters
Processing
                    pH
 Total
Dissolved
 Solids
Sulfide
Sulfate
Calcium
Trace
Metal
 Heat
Release
3g/20ml
 Total  
Organic
Carbon
Unprocessed CAFB
                                                    ys
                                                    = 18C
                                                   Xxxxx>
Ory-Sulfation
                                               AT=ND<0.2C
Dead-Burning
                                               AT=ND<0.2C
Rm-temp.Processing
                                               AT=ND<0.2C
HRemp. Processing
                                               AT=ND<0.2C
   Note:   u   Unprocessed CAFB leachate characteristics
          +   Improved from u value
          0   No significant change from u value

         ^  Do not meet either the drinking water or gypsum leachate criteria
         ^  Pass gypsum  leachate criteria but not Drinking Water Standards
         Q  Pass both drinking water and gypsum leachate criteria
          a   No Drinking Water Standards exist

-------
          The major environmental concerns for direct disposal are heat
release, sulfide, pH, calcium, SO^, and IDS.   The major environmental
conerns for disposal after processing are pH, calcium, SO,, and IDS.
On the basis of these results, spent sorbent processing will be required.
There are advantages and disadvantages to each method of processing,
but the ultimate decision will be based on the careful balance of tech-
nical achievement and economic feasibility.  Of course, site selection,
design, and management of the disposal task based on the site-specific
hydrology, geology, climate, and soil composition are critically
important to the success of a solid waste disposal system.  Selection of
a proper processing method to reduce the residue surface area and
permeability and to improve the heat-release and leaching properties
can greatly simplify the disposal management task.
          In the absence of formal EPA criteria with which to assess the
environmental acceptability of the disposal of CAFB residues, the
chemical, physical, and leaching properties of the spent fluidized-bed
combustion (FBC) material are compared with those of the residues from
six FGD processes developed for conventional coal-burning power plants.
A preliminary comparison of the environmental impact of the disposal of
unprocessed CAFB solid wastes and untreated FGD sludge residues from
varying processing systems is presented in Table 36 on the basis of up-
to-date results from parallel environmental testing programs.  Since
the samples tested resulted from our use of different coal and sorbents,
an absolute comparison may not be possible, although one would hope that
the general trends indicated were meaningful.
          These results are encouraging and suggest that the disposal of
the CAFB solid waste may cause environmental effects comparable to (due
to its chemical properties) or perhaps less negative than (due to its
physical properties)  the disposal of the residue from the currently
commercialized FGD process.
          The assessment is based on the current results from an ongoing
program that is limited, however,  by the lack of spent CAFB materials
from commercial systems.  These conclusions are considered preliminary
and should be reassessed as more representative samples become available.
                                   100

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                                  Table 37
                                                                   OHf. 2*15CM
            PRELIMINARY COMPARISON OF THE ENVIRONMENTAL IMPACT
                   OF THE DISPOSAL OF CAFB AND  FGD RESIDUES*
CAFB
(T) Solubility of major compounds: Ca. SO. . and IDS
contributing to potential environmental concern
(D Sulfidfc environmental concern
(5) High alkalinity in leachate: pH = 10 to 13
(4) Trace elements: not expected to cause
environmental problem. Most leachates meet
Drinking Water Standards
(5) TOC in leachate: tow
(T) Residual activity : Heat - release due
to hydration ot CaO
(2) Spent sorbent in dry granular solid form
 More disposal and utilization options available
 Relative ease in transporting and disposal
(3) Further processing is recommended due to
presence of CaS and CaO
FGD
(T) High concentrations of Mg, Cl in addition
to Ca. SOj and IDS (plus Na in the case
of double-alkali system )
(D Sulfite: environmental concern
(D pH = 5 to 10 for lime or limestone
scrubbing systems
pH = 12 to 13 for double-alkali system
(J) Several elements in liquor and leachate,
e.g. As. Se, Cd. Mn and F, exceeding the
Drinking Water Standards including the
ponded and oxidized sludges
(|) TOC in leachate: low
TOC in liquors: low
(T) No heat- release problem
(D In sludge form
 Difficulty in dewatering and settling
of untreated sludge causing problems
in tend disposal
 Potential environmental problems
associated with transporting, ponding,
and land reclamation
(D Physical stabilization chemical
fixation or oxidation to high solids
content gypsum most likely required
Chemical
Property
Physical
Property
        ^Unprocessed CAP)  residue and untrsa:.ed FGD sludge
                                       101

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                              5.  REFERENCES

1.  Archer, D. H., D. L. Keairns, J. R. Hamm, R. A. Newby, W.-C. Yang,
    L. M. Handman, and L. Elikan, Evaluation of the Fluidized Bed
    Combustion Process, Vols. I, II, and III.  Report to EPA, Westing-
    house Research and Development Center, Pittsburgh, PA, November 1971,
    GAP Contract 70-9, NTIS PB 211-494, 212-916, and 213-152.

2.  Keairns, D. L., D. H. Archer, R. A. Newby, E. P. O'Neill, E. J. Vidt,
    Evaluation of the Fluidized-Bed Combustion Process, Vol. IV,
    Fluidized-Bed Oil Gasification/Desulfurization.  Report to EPA,
    Westinghouse Research and Development Center, Pittsburgh, PA,
    December 1973, EPA-650/2-73-048d, NTIS PB 233-101.

3.  Keairns, D. L., R. A. Newby, E. J. Vidt, E. P. O'Neill, C. H.
    Peterson, C. C. Sun, C. D. Buscaglia, and D. H.  Archer, Fluidized
    Bed Combustion Process Evaluation - Residual Oil Gasification/
    Desulfurization Demonstration at Atmospheric Pressure.  Report to
    EPA, Westinghouse Research and Development Center, Pittsburgh, PA,
    March 1975, EPA-650/2-75-027 a&b, NTIS PB 241-834 and PB 241-835.

4.  Chemically Active Fluid Bed for SO  Control: Volume 2, Processing
    of Spent Sorbent, Westinghouse report to EPA,  to be issued.

5.  O'Neill, E. P., D. L. Keairns, and M. A. Alvin,  Sorbent Selection
    for the CAFB Residual Oil Gasification Demonstration Plant.   Report
    to EPA, Westinghouse Research and Development Center, Pittsburgh,
    PA, March 1977, EPA-600/7-77-029, NTIS PB 266-827.

6.  Bachovchin, D.  M., P. R. Mulik, R. A. Newby, and D. L. Keairns,
    Solids Transport between Adjacent CAFB Fluidized Beds.  Report to
    EPA, Westinghouse Research and Development Center, Pittsburgh, PA,
    January 1979,  EPA-600/7-79-021.

7.  Chemically Active Fluid Bed for SO  Control: Volume 1, Engineering
    Evaluation and Sorbent Selection, Westinghouse report to EPA, to
    be issued.

8.  Resource Conservation and Recovery Act, Public Law 94-580; 1976.

9.  Keairns, D. L., C. H. Peterson, and C. C. Sun, Disposition of Spent
    Calcium-Based Sorbents Used for Sulfur Removal in Fossil Fuel
    Gasification,  Presented at the Solid Waste Management Session,
    69th Annual Meeting, AIChE,  November 28 - December 2, 1976,
    Westinghouse Scientific Paper 76-9E3-FBGAS-P1.
                                  102

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REFERENCES (Continued)

10.  Craig, J.  W.  T.,  et al.,  Chemically Active Fluid Bed Process for
     Sulfur Removal During Gasification of Heavy Fuel Oil - Second Phase.
     Report to EPA, Esso Research Centre, Abingdon, UK, November 1974,
     EPA-650/2-74-109,  NTIS PB240-632/AS.

11.  Chemically Active Fluid Bed Process (CAFB).  Monthly report to
     EPA, Foster Wheeler Energy Corporation, Livingston, N. J.  May 29 -
     June 25, 1978, Contract 68-02-2106.

12.  Peterson, C.  H.,  Processing of Spent Sorbent from the CAFB Process
     for Disposal/Utilization.  Report to EPA, Westinghouse Research
     and Development Center, Pittsburgh, PA.  To be issued.

13.  Federal Register (42 CFR Part 466), 36 (159); August 17, 1971.

14.  Federal Water Pollution Control At, Public Law 92-500; 1972.

15.  Clean Water Act,  Public Law 95-217; 1977.

16.  Corson, A., D. Friedman, and D. Viviani, Hazardous Waste Management
     Division, EPA-OSW, 1978.

17.  "Hazardous Waste Guidelines and Regulations-Criteria, Identification,
     and Listing of Hazardous Waste" EPA Draft, March  1978.

18.  "Hazardous Waste:  Proposed Guidelines and Regulations and Proposal
     on  Identification and Listing," Federal Register, December 18, 1978.

19.  "Solid Waste Disposal Facilities - Proposed Classification Criteria,"
     Federal Register, February 6, 1978.

20.  "Land Disposal of Solid Waste Proposed Guidelines."  Federal Register,
     March 26, 1979.  Part II.

21.  Federal  Register, 41 (29); February 11,  1976.

22.  Environmental  Protection  Agency National  Interim Primary Drinking
     Water Regulations, Federal Register,  40  FR  59565; December  24,  1975;
     Environmental  Reporter 81; February 13,  1976.

23.  U.  S. Drinking Water Standards 1962,  U.  S.  PUblic Health Service
     Publications  956;  1962.

24.  Interim Standards  for Drinking Water,  3rd Edition,  Geneva:   World
     Health  Organization; 1971.

25.  EPA Effluent  Guidelines  and  Standards for Steam Electric Power
     Generating, Federal  Register,  40-FR 23987;  June 4,  1975; Environ-
     mental  Reporter,  S-259;  July 11,  1975.
                                    103

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REFERENCES (Continued)

26.  Hangebrauck, R. P., Status of IERL-RTP Program to Develop Environ-
     mental Assessment Methodology for Fossil Fuel Processes, working
     document; February 1977.

27.  Cleland, J. G., and G. L. Kingsbury, Multimedia Environmental Goals
     for Environmental Assessment, Vol. I, November 1977, EPA-600/7-77-136a.

28.  Schalir, L. M., and K. J. Wolfe, SAM/1A:  A Rapid Screening Method
     for Environmental Assessment of Fossil Energy Process Effluents.
     Report to EPA,  Acurex Corporation, Mountainview, CA; January 1978.
     Aerotherm Report TR-77-50.

29.  Weaver, D. E.,  C. J. Schmidt, and J. P. Woodyard, Data Base for
     Standards/Regulations Development for Land Disposal of Flue Gas
     Cleaning Sludges.  Report to EPA, SCS Engineers, Long Beach, CA,
     December 1977,  EPA-600/7-77-118.

30.  Water Quality Criteria, Ecological Research Series; March 1973.

31.  Zoldak, F., and B. Halliday, Foster Wheeler Energy Corporation,
     Private Communications, 1977-78.

32.  Proposed Test Methods for Leaching of Waste Materials, ASTM D19-1203,
     June 1978.

33.  Sun, C. C., C.  H. Peterson, and D. L. Keairns, Disposal of Solid
     Residue from Fluidized-Bed Combustion:  Engineering and Laboratory
     Studies.  Report to EPA, Westinghouse Research and Development
     Center, Pittsburgh, PA, March 1978, EPA-600/7-78-049.

34.  Sun, C. C., C.  H. Peterson, and D. L. Keairns, Environmental Impact
     of the Disposal of Processed and Unprocessed FBC Bed Material and
     Carry-over, Proceedings of the Fifth International Conference on
     Fluidized-Bed Combustion, Washington, D. C., December 12-14, 1977,
     McLean, VA:  The Mitre Corporation; 1978.

35.  Friedman, D., and D. Viviani, EPA Office of Solid Waste-Hazardous
     Waste Management Division.  Private Communication; July 1978.

36.  Boynton, B. S., Chemistry and Technology of Lime and Limestone.
     New York:  Interscience Publishers; 1966.

37.  ^hysical Testing of Quick Lime, Hydrated Lime and Limestone, ASTM
     C110-76.  Annual Book of ASTM Standards, Part 13; 68-85; 1976.

38.  Murray, J. B.,  et al., Shrinkages of High-Calcium Limestone during
     burning, J. Am.  Ceram. Soc., 37 (7):  323-28; 1974.
                                   104

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REFERENCES (Continued)

39.  Stone, R., and R.  Kahle, Environmental Assessment of Solid Residues
     from Fluidized-Bed Fuel Processing.  Report to EPA, Ralph Stone
     and Co., Inc., Los Angeles, CA, December 1977, EPA 600/7-77-139.

40.  Keairns, D. L.,  et al.   Fluidized-Bed Combustion:  Environmental
     and Engineering Investigations.  Report to EPA, Westinghouse
     Research and Development Center, Pittsburgh, PA.  To be issued.

41.  Werner, A. S., et al.  Preliminary Environmental Assessment of
     the CAFB.  Report to EPA, GCA Corporation, Bedford, MA, October
     1976, EPA-650/7-76-017.

42.  Van'Ness, R. P., Louisville Gas and Electric Co., Private
     Communication, 1977.

43.  Henzel, D., Dravo Lime Co., Private Communication, March 1978.
    1 -
44. i Leo, P. P., Aerospace Corporation, Private Communication, 1977.
    i
45.  Disposal of By-Products from Non-Regenerable Flue Gas Desulfurization
     Systems.  Second Progress Report to EPA, Aerospace Corporation,
     May 1977, EPA-600/7-77-052.

46.  Sludge Oxidation in Limestone FGD  Scrubbers, EPA-IERL, Research
     Triangle Park, NC, June 1977, NTIS PB 268-525.

47.  Selmeczi, J. G., D. H. Marlin,  and D. W. Kestner,  Stabilization
     of Sludge Slurries, Dravo Corporation,  Pittsburgh, PA.  U.  S.
     Patent 3,920,795, November 18,  1975.

48.  Standard Methods for the Examination  of Water  and  Waste Water,
     13th  Edition.  Washington, D.C.:   American  Public  Health
     Association;  1974.
                                    105

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                               TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse before completing}
  REPORT NO. .
 EPA-600/7-79-158c
                           2.
                                                     3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
 Chemically Active Fluid Bed for SOx Control:
 Volume 3. Sorbent Disposal
           5. REPORT DATE
            July 1979
           6. PERFORMING ORGANIZATION CODE
i. AUTHOR(S)
C.C. Sun
                                                      8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Westinghouse Research and Development Center
1310 Beulah Road
Pittsburgh, Pennsylvania 15235
            10. PROGRAM ELEMENT NO.
            EHB536
            11. CONTRACT/GRANT NO.

            68-02-2142
12. SPONSORING AGENCY NAME AND ADDRESS
 EPA, Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC  27711
            13. TYPE OF REPORT AND PERIOD COVERED
            Final; 2/76 - 2/79
            14. SPONSORING AGENCY CODE
             EPA/600/13
15. SUPPLEMENTARY NOTES IERL-RTP project officer is Samuel L.  Rakes, Mail Drop 61,
919/541-2825.
16. ABSTRACT The rep0rt describes a laboratory investigation of three areas of the
 chemically active fluidized-bed (CAFB) process: residue characterization, leaching
 property, and thermal activity. Results indicate that further processing is required
 to meet environmental constraints. The environmental impact of CAFB residue dis-
 posal is also compared with results of conventional residues (flue gas desulfurization
 and lignite ash) from parallel tests.  The impact of the recently enacted Resource
 Conservation and Recovery Act is  assessed. The CAFB process was developed to
 convert high-sulfur heavy oils and low-grade coal to  clean, medium heating value
 fuel gas in conventional boilers. Disposal of the spent sorbent, which consists of
 varying amounts of CaO, CaS, and CaSO4, may cause environmental concerns asso-
 ciated with potential air, water, odor, and heat pollution. The spent sorbent can be
 further processed to reduce its environmental impact by methods  including dry sul-
 fation,  dead-burning, room-temperature fly-ash blending,  high-temperature pro-
 cessing,  and slurry carbonation.
17.
                             KEY WORDS AND DOCUMENT ANALYSIS
                DESCRIPTORS
 Pollution             Leaching
 Fluidized Bed Processing
 Coal Gasification     Heat of Hydration
 Fuel Oil              Sorbents
 Waste Disposal
 Residues
                                          b.IDENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
CAFB
Thermal Activity
                        c. COSATI Field/Group
13 B        07 D
13H,07A
           20M
2 ID        11G
18. DISTRIBUTION STATEMENT
 Release to Public
                                          19. SECURITY CLASS (This Report)
                                          Unclassified
                         21. NO. OF PAGES
                              119
20. SECURITY CLASS (Thispage)
Unclassified
                                                                   22. PRICE
EPA Form 2220-1 (9-73)

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