iesearch     EPA-600/7-78-049
Off ice of Research and Development Laboratory                  *o^o
               Research Triangle Park, North Carolina 27711 MdrCll 1978
      DISPOSAL OF SOLID RESIDUE
      FROM FLUIDIZED-BED
      COMBUSTION: ENGINEERING
      AND LABORATORY STUDIES
      Interagency
      Energy-Environment
      Research and Development
      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.
                           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-600/7-78-049
                                          March 1978
DISPOSAL OF SOLID RESIDUE FROM
    FLUIDIZED-BED COMBUSTION:
  ENGINEERING AND LABORATORY
                   STUDIES
                        by

              C. C. Sun, C. H. Peterson, R. A. Newby,
                 W. G. Vaux, and D. L. Keairns

            Westinghouse Research and Development Center
                    1310 Beulah Road
                Pittsburgh, Pennsylvania 15235
                  Contract No. 68-02-2132
                Program Element No. EHE623A
              EPA Project Officer: D. Bruce Henschel

             Industrial Environmental Research Laboratory
              Office of Energy, Minerals and Industry
               Research Triangle Park, N.C. 27711
                     Prepared for

            U.S. ENVIRONMENTAL PROTECTION AGENCY
               Office of Research and Development
                  Washington, D.C. 20460

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                                 PREFACE

     The Westinghouse R&D Center is carrying out a program to provide
experimental and engineering support for the development of fluidized-
bed combustion systems under contract to the Industrial Environmental
Research Laboratory, U. S. Environmental Protection Agency (EPA), at
Research Triangle Park, NC.  The contract scope includes atmospheric
and pressurized fluidized-bed combustion processes as they may be
applied for steam generation, electric power generation, or process
heat.  Specific tasks include work on calcium-based sulfur removal
system studies (e.g., sorption kinetics, regeneration, attrition,
modeling), alternative sulfur sorbents, nitrogen oxide emissions, par-
ticulate emissions and control, trace element emissions and control,
spent sorbent and ash disposal, and system evaluation (e.g., the impact
of new source performance standards on fluidized-bed combustion system
design and cost).
     This report contains the results of work defined and completed
under the task on environmental control using calcium-based sorbents.
The work was carried out from December 1975 to January 1977.  Results
from work carried out by Westinghouse or reported by other investigators
after January 1977 are not assimilated into this task report.  The
work reported represents an extension of prior work completed by
Westinghouse under contract to EPA.  Results from this prior work
on fluidized-bed combustion include:
     •  Assimilation of available data on fluidized-bed combustion,
        including sulfur dioxide removal, sorbent regeneration,
        sorbent attrition, nitrogen oxide minimization, combustion
        efficiency, heat transfer, particle carry-over, boiler tube
        corrosion/erosion fouling, and gas-turbine erosion/corrosion
        deposition
                                    iii

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•  Assessment of markets for industrial boilers and utility power
   systems
•  Development of designs for fluidized-bed industrial boilers
•  Development of designs for fluidized-bed combustion utility
   power systems:  atmospheric-pressure fluidized-bed combustion
   boiler-combined cycle power systems, adiabatic fluidized-bed
   combustion-combined cycle power systems—including first- and
   second-generation concepts
•  Preparation of a preliminary design and cost estimate for a
   30 MW (equivalent) pressurized fluidized-bed combustion
   boiler development plant
•  Assessment of the sensitivity of operating and design parameters
   selected for the base power plant design on plant economics
•  Collection of experimental data on sulfur removal and sorbent
   regeneration using limestone and dolomites
•  Preparation of cost and performance estimates for once—through
   and regenerative sulfur removal systems
•  Evaluation of alternative sulfur sorbents
•  Collection and analysis of data on spent sorbent disposal—
   utilization and environmental impact of disposal
•  Projection and analysis of trace emissions from fluidized-bed
   combustion systems
•  Analysis of particulate removal requirements and development
   of a particulate control system for high-temperature, high-
   pressure fluidized-bed combustion systems
•  Construction of a high-pressure/temperature particulate
   control test facility
•  Development of plant operation and control procedures
•  Construction of a corrosion/erosion test facility for the
   0.63 MW Exxon miniplant
•  Continued assessment of fluidized-bed combustion power plant
   cycles and component designs to evaluate environmental impact.

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     The results of these surveys, designs, evaluations, and exper-
imental programs provide the basis for the work being carried out under
the current contract.   Seven reports are available that document the prior
contract work (see references 3, 6, 36).  Other reports published under
the current contract include "Alternatives to Calcium-Based Sorbents
for Fluidized-Bed Combustion:  Conceptual Evaluation,"     "Calcium-Based
Sorbent Regeneration for Fluidized-Bed Combustion,"     and Evaluation
of Trace Element Release from Fluidized-Bed Combustion Systems."
                                    v

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                                ABSTRACT

     An understanding of the environmental impact of the disposal of
spent limestones and dolomites and of fuel ash is critical for the suc-
cess of fluidized-bed combustion (FBC) processes.  Land and ocean disposal
of unprocessed and processed effluent solids have been studied.  The
quantity and composition of spent sorbents produced from six reference
FBC processes are projected.  Effluent solids from atmospheric and pres-
surized fluidized-bed combustion processes, once-through and regenerated
spent sorbent, and bed material and carry-over solids were experimentally
investigated.  Laboratory testing procedures were developed to determine
spent sorbent characteristics, leaching behavior, and thermal activity.
Processing the spent sorbent and ash was experimentally investigated to
develop alternatives for reducing the environmental impact and to provide
alternatives for potential utilization.  The environmental impact from
the land disposal of unprocessed and processed effluent solids is estim-
ated on the basis of results from an experimental test program and compared
with the behavior of natural gypsum and the drinking water standards.  The
potential for ocean disposal is assessed.
                                    vii

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                               CONTENTS
1.  INTRODUCTION                                                  1
2.  CONCLUSIONS                                                   3
         Spent Sorbent Characteristics                             3
         Spent Sorbent/Ash Land Disposal                           4
         Spent Sorbent Utilization                                6
         Ocean Disposal/Utilization                                7
3.  RECOMMENDATIONS                                               8
         Spent Sorbent Characteristics                             8
         Spent Sorbent/Ash Disposal                                8
         Spent Sorbent/Ash Utilization                             9
         Ocean Disposal/Utilization                                9
4.  CHARACTERISTICS OF FBC ASH AND SPENT  SORBENT                  10
         Factors Influencing the Spent  Sorbent  Characteristics    10
              Fresh Sorbent, Coal and Coal Ash  Properties         12
              Plant Sulfur Balances                               17
         Projection of Spent Sorbent and  Coal Ash Production
         Rates                                                   25
              Sorbent Utilization for Once-through Operation      26
              Sorbent Regenerability                              29
              Sorbent Attrition and Elutriation                  38
         Assessment of Spent Sorbent Projections for
         Fluidized-Bed Combustion                                39
5.  LAND DISPOSAL                                    "           46
         Regulations/Criteria                                    46
              Related Literature on Disposal                      48
         Experimental Testing Program                             50
              Samples                                            50
              Spent Sorbent Characterization                      53
              Leaching Tests                                     63
                   Spent Sorbent                                 66
                   Fly Ash and Fines                              72
                   Spent Sorbent/Fly Ash  Mixtures                 72
                   Processed Spent Sorbent/Fly  Ash Compacts       75
              Trace Metal Elements                               78
         COD/BOD/TOC                                             81
              Activity Tests                                     82
         Conclusions and Assessment                               85
                                   ix

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                           CONTENTS (Cont'd)

                                                                  Page.

6.   OCEAN DISPOSAL                                                88
         Feasibility Study                                        88
         Survey of Current EPA Attitude toward Ocean Dumping      89
         Test Program                                             90
7.   UTILIZATION AND REDUCTION OF DISPOSAL IMPACT                  91
         Options                                                  91
         Market Data                                              92
              Primary Markets                                     92
              Special Markets                                     92
              Other Markets                                       95
         Overall Economics                                        95
         Technical Requirements                                   96
              Environmental Considerations                        96
              Characteristics of Aggregate                        99
              Characteristics of Cement and Concrete             101
              State of the Art - Disposition of Solid Wastes     102
              Sulfate Wastes                                     104
                   Effect of Water Content on Compressive
                   Strength                                      104
                   Effect of Lime Type                           105
                   Effect of Type of Calcium Compound            105
                   Effect of Lime/Sulfate Ratio                  105
                   Effect of Fly Ash Content                     106
                   Effect of Sulfate Content                     106
                   Effect of Portland Cement Content             107
                   Effect of Other Components                    107
                   X-Ray Examination                             107
              Tests on Industrial Sulfate Wastes                 108
                   Screening Tests for Compressive Strength      108
                   Engineering Evaluation                        109
                   Aggregate Properties                          110
              Fly Ash                                            111
                   Composition                                   111
                   Compressive Strength                          112
                   Linear Expansion                              112
         State-of-the-Art Specifications and Test Methods        113
              Freeze-Thaw Resistance                             113
              Standard Tests and Specifications                  115
         Experimental Program                                    116
              Identification of Spent Sorbents to Be Tested      116
                   Combustor Variables                           116
                   Composition Ranges                            118
                   Sources                                       120
                                   x

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                            CONTENTS (Cont'd)
               Feasibility Tests                                  123
                    Blending Tests                                123
                    Isostatic Pressing                            125
                    Screening Tests - Exxon Stone                 125
               Screening Tests - PER Stone                        127
          Assessment of Utilization                               138
               Preliminary Flow Sheets                            138
               Preliminary Economics                              138
               Analysis of Results                                142
 8.  REFERENCES                                                   144

APPENDICES

    A     THE FEASIBILITY OF OCEAN DUMPING AS AN INTERIM
          ALTERNATIVE TO DISPOSAL OF SPENT STONE FROM THE
          FLUIDIZED BED COMBUSTION PROCESS                        152
               Introduction                                       153
               Federal Regulations and Permit Procedures          154
               Approved Sites for Ocean Dumping                   161
               Ocean Dumping Mechanisms                           165
               Feasibility of Dumping Spent Stone at Sea          169
               References                                         176

    B     OCEAN DUMPING                                           177
               References                                         183

    C     PREDICTED PRODUCTION PROPORTIONS OF SPENT SORBENT
          AND FLY ASH FROM FLUIDIZED-BED COMBUSTION               184
                                    xi

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                                 FIGURES

Number                                                            "Page

  1        Fluidized-Bed Combustion General Sorbent Flow
           Diagram                                                   13

  2        Size Distribution of Coal Feed                            20

  3        Required Combustor Sulfur Removal Efficiency              21

  4A       General Once-through Operation Sulfur Balances            23

  4B       General Regenerative Operation Sulfur Balances            23

  5        Ratio of Ash to Sorbent for Once-through Operation        27

  6        Cumulative Distribution of Sorbent Utilization            30

  7        Sulfation of Calcined Tymochtee Dolomite                  31

  8        Basis for Regenerative Sorbent Utilization
           Projection                                                33

  9        Distribution of Cycle Number for Regenerative
           Spent Sorbent                                             35

 10        Particle Size Distribution for Different Gas
           Streams                                                   45

 11        Microphotographs of Exxon Run No. 27 (a) Bed Stone
           and (b) Fly Ash                                           59

 12        (a) SEM Photomicrograph of Exxon 27 Spent Sorbent
           (b) EDAX Spectrum of Spot 1 on SEM
           (c) EDAX Spectrum of Spot 2 on SEM                        60

 13        (a) SEM Photomicrograph of Exxon 19.6 Fly Ash
           (b) EDAX Spectrum of Spot 1 on SEM
           (c) EDAX Spectrum of Spot 2 on SEM      '                  61
                                   XII

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                            FIGURES (Cont'd)

Number                                                             Page

 14        SEM and Electron Microprobe Photomicrographs of a
           Spent Limestone Particle (Exxon 27)
           (a)(b) SEM and Sulfur Scan on a Cross-Sectional
                  Area Near the Surface
           (c)(d) SEM and Sulfur Scan on a Cross-Sectional
                  Area in the Interior                               62

 15        Area-Scan Electron Microprobe Photomicrographs on a
           Cross Section of a Spent Limestone Particle (Exxon
           19.6) Near Its Surface, (a) SEM, (b) Ca, (c) S,
           (d) Si, (e) Al, and (f) Fe                                64

 16        Area-Scan Electron Microprobe Photomicrographs on a
           Cross Section of a Completely Sulfated Spent Lime-
           stone Particle (Exxon 19.6) Near Its Surface,
           (a) SEM, (b) CA, (c) S, (d) Si, (e) Al and (f) Fe         65

 17        Leachate Characteristics as a Function of Mixing
           Time of Spent Sorbents                                    68

 18        Leachate Characteristics as a Function of Stone
           Loading                                                   70

 19        Leachate Characteristics of the Argonne Spent Stone
           Leachates Induced by the Run-off Tests                    71

 20        Leachate Characteristics as a Function of Mixing
           Time of Fly Ash                                           73

 21        Leachate Characteristics of Bed Material/Fly Ash
           Mixtures                                                  74

 22        Chemical Characteristics from Consecutive Leachates
           for Processed Exxon No. 27 Spent/Fly Ash Compacts         76

 23        Specific Conductance of Leachate as a Function of
           Total Leaching Time                                       79

 24        Projected Composition Range for Spent Sorbent from
           Fluidized-Bed Combustion at 850°C                        119

 25        Compressive Strength of 5-cm Cubes Cast from Spent
           Solids from Exxon Run 27 Using Mix I                     132
                                   xiii

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                            FIGURES (Cont'd)

Number                                                             Page

 26        Compressive Strength of 5-cm Cubes  Cast  from Spent
           Solids from Exxon Run 27 using Mix  II                     133

 27        Compressive Strength of 5-cm Cubes  Cast  from Spent
           Solids from Exxon Run 27 Using Mix  III                    134

 28        Effect of Water Content on  Compressive Strength
           of 5-cm Cubes Cast from Spent Solids from Exxon  27       135

 29        Spent Sorbent Disposal/Utilization  from  Atmospheric-
           Pressure Fluidized-Bed Combustion                         139
                                  xiv

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                                 TABLES

Number                                                             Page

  1        Chemical and Mineralogical Properties of Limestone        14

  2        Accessory Mineral Content of Limestones*                  15

  3        Analysis of Limestone No. 1359                            16

  4        SC>2 Sorbent Analysis Used for Preliminary Fluidized-
           Bed Boiler Analysis                                       16

  5        Mean Analytical Values for all 101 Coals*                 18

  6        Ohio Pittsburgh No. 8 Seam Coal                           19

  7        Plant Sulfur Balance Relationships                        24

  8        Projections of Once-through Sorbent Utilization           28

  9        Projected Regenerative Sorbent Utilizations               34

 10        Projected Sorbent Makeup Rates                            37

 11        Power Plant Basis for Spent Sorbent Projections           40

 12        Once-through Sorbent Operation Projections                41

 13        One-Step Regeneration Projections                         42

 14        Two-Step Regeneration Projections                         43

 15        Turndown Spent Sorbent Projects                           44

 16        Selected Water Quality Criteria                           49

 17        Process Conditions of Samples Studied for Their
           Environmental Impact on Disposal                          52

 18        Chemical Compositions of Spent Bed Materials and
           Fly Ash from Fluidized-Bed Coal Combustion Units          54
                                    xv

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                            TABLES (Cont'd)

Number

 19        Chemical Compositions of Spent Sorbents from
           Fluidized-Bed Coal Combustion

 20        Chemical Composition of Spent Sorbent and Fly Ash
           By X-ray Diffraction                                      56

 21        Comparison of Chemical Compositions of Actual Spent
           Sorbents from Fluidized-Bed Combustion Units with the
           Projected Values                                          58

 22        Comparison of Specific Conductance of Leachates  from
           Spent Bed Materials from Varying  FBC Processes            69

 23        Leachate Characteristics of Processed and Unprocessed
           Spent Sorbent and Fly Ash from Exxon Run 27                77

 24        Trace Metal Ion Concentrations in Spent Sorbents and
           Fly Ash from the Fluidized-Bed Combustion Process
           and Leachates                                             80

 25        Total Inorganic and Organic Carbon in Leachate
           from Unprocessed and Processed FBC Solid Waste            82

 26        Heat-Release Property of FBC Waste                        84

 27        Preliminary Indications of Environmental Impact  from
           the FBC Solid Waste Disposal                              88

 28        Market Data on Selected Construction Materials            93

 29        Definitions of Various Kinds of Cement                   103

 30        Spent Sorbent Test Compositions                          121

 31        Chemical Analyses of Pilot Plant  Spent Sorbents           122

 32        Compressive Strength of Sulfated  Dolomite/Fly Ash
           Blends                                                   123

 33        Compressive Strength on 5-cm Cubes Cast from
           Exxon Run 27 Spent Solids                                124

 34        Matrix for Screening Test Using 2-in Cubes Made
           from Spent Sorbent and Fly Ash from Exxon Run 27         128
                                   xvi

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                             TABLES (Cont'd)

Number                                                             Page

 35        Compressive Strength of PER Spent Sorbent Mixes          136

 36        Estimated Composition of PER Compacts                    136

 37        Comparison of Composition of PER Compacts with Normal
           Portland Cement                                          137

 38        Energy Consumption of the Cement Industry                140
                                    xvii

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                             ACKNOWLEDGEMENT

     We want to express our high regard for and acknowledge the contribu-
tion of Mr. D. B. Henschel who served as the EPA project officer.   Mr.  P.
P. Turner and Mr. R. P. Hangebrauck, Industrial Environmental Research
Laboratory, EPA, are acknowledged for their continuing contributions
through discussions and support of the program.
     We would like to thank Messrs. G. C. Vogel and W. Swift of Argonne
National Laboratories; Mr. Robert Reed of Pope, Evans and Robbins;
Mr. H. B. Lange of Babcock and Wilcox; Mr. H. Stoner of Combustion  Power;
and Messrs. J. S. Wilson and R. Rice of Morgantown Research Center  for
their cooperation in supplying FBC residues.
     The program consultation and continued support of Dr. D. H. Archer,
Manager, Chemical Engineering Research, at Westinghouse, are acknowledged.
                                   xix

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                                SECTION 1
                              INTRODUCTION

     Fluidized-bed combustion for electric power generation provides the
potential for improved thermal conversion efficiency, reduced costs, and
reduced environmental impact when compared with conventional technology.
The fluidized-bed combustion process, operated at atmospheric or ele-
vated pressure, typically results in the production of spent bed mate-
rial in the form of dry, partially utilized dolomite or limestone
particles from 0 to 6 mm in size.  This spent bed material is referred
to in this report as "spent sorbent."  In addition, fine particles of
sorbent and ash will be collected in the particulate-removal system.
This material collected in the flue gas particle control equipment is
referred to in this report as "carry-over" or "fly ash," although it
includes some sorbent as well as ash.  The spent sorbent bed material
may be either regenerated for recycling to the fluid-bed boiler for
repeated sulfur dioxide removal or disposed of in its partially sulfated
form in a once-through system.  The former process has the potential
advantage of producing less solid waste for disposal.  The properties
of these spent sorbents (size distribution, composition, etc.) are sen-
sitive to a number of operating and design factors.  The major compounds
in the waste stone to be disposed of are calcium sulfate, calcium oxide,
calcium carbonate, and magnesium oxide when dolomite is used; and cal-
cium sulfate and calcium oxide or calcium carbonate when limestone is
used.  Trace elements arising from impurities in the coal and sorbent
will also be present.
     The quantity of spent sorbent will depend upon the amount of fresh
sorbent fed - that is, upon the sulfur content of the fuel, the emission
standard, the operating conditions, the scrbent characteristics, and

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whether or not sorbent regeneration is employed.  The spent sorbent for
disposal will generally range from 0.01 to 0.5 kg sorbent/kg coal.  Dis-
posal of the fly ash must also be considered.
     An understanding of the environmental impact from the disposal or
use of the spent sorbent and fly ash is critical for the successful
implementation of fluidized-bed combustion processes.  The present pro-
gram is designed to provide a basis for:
     •  Projecting environmental impact from disposal
     •  Interpreting results from large-scale demonstration sites
     •  Developing optimal system and design and operating require-
        ments, and means for treatment of the residue,  to minimize
        the environmental impact from the spent sorbent and coal ash
     •  Screening utilization options in view of the environmental
        impact.
The scope of the program conceived to achieve these objectives includes:
identification of fluidized^-bed combustion spent sorbent and coal ash
characteristics and quantities; development of laboratory tests to quan-
tify the environmental impact for land and ocean disposal;  conducting
environmental impact tests on actual FBC  spent sorbent  and ash for land
and ocean disposal; studying methods for reducing the impact of the
material upon disposal; and performing investigations to identify poten-
tial land and ocean utilization options and the resulting potential
environmental impact.   The work reported  represents results from the
first 12 months of the current program (December 1975 to December 1976).

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                                       SECTION 2

                                      CONCLUSIONS


 SPENT SORBENT  CHARACTERISTICS

       The  nominal spent sorbent  compositions projected  for three basic

 fluidized-bed  combustion  concepts are  as follows:
Process
Sorbent
CaSOA
Spent Sorbent Composition,
mole "/, (weight %)
CaS CaO CaCO
Atnospheric Pressure Limestone 25 0 75 0
FBC (43.7) (0) (54) (0)
Once-through
100% load
MgO
oa
(0)
Balance
1.73C
(2.3)
Pressurized Boiler
   Once-through
   100% load
Adiabatic Conbustor
   Once-through
   100% load
Pressurized Boiler
   Once-through
   100% load
Atnospheric FBC
   One-step regenera-
   tion 100": load
Pressurized Boiler
   Once-through
   turndown to
   r.inimum load
                    Dolomite
Dolomite
Limestone
Limestone
Dolomite
80
(64.1)
50
(46.7)
40
(60.6)
24d/12.8e
(43.1/26.1)
60
(47.6)
0
(0)
0
(0)
0
(0)
Od/1.2e
(0/1.3)
0
(0)
20
(6.6)
50
(19.2)
60
(37.4)
76d/86e
(54.6/70.1)
0
(0)
0
(0)
0
(0)
0
(0)
0
(0)
40
(23.4)
1.19°
(28.1)
1.19b
(32.7)
Oa
(0)
oa
(0)
1.19b
(27.8)
2.111-
(1.2)
2.11°
(1.4)
1.73C
(2)
1.73C
(2.3/2.5)
2.11C
(1.2)
 MgO included vith balance of components

bnoles MgO/-ole Ca

 erar.s per ~vle calcium

 spent sorber.t from combustor

es3ent sorher.• from regenerator
       The  size  distribution of  spent  sorbent from the  bed will be similar
 to the sorbent feed  size  distribution.

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     The spent sorbent fines appearing in the fly ash will depend upon
sorbent attrition rate, bed elutriation rate, and fines recycle (if
applied).  The coal ash, in general, will all be elutriated from the
combustor.  The quantity of sorbent fines is estimated to range from
0.25 to 1 times the coal ash content of the fly ash for a nominal 10 per-
cent ash coal.
SPENT SORBENT/ASH LAND DISPOSAL
     Environmental impact criteria have not yet been established for
the land disposal of spent sorbent.  Leaching and activity tests were
developed to permit the projection of environmental impact from land
disposal.  Criteria for determining the environmental impact of the
residue, as well as standardized leaching tests, may be developed sepa-
rately by EPA in the near future under the Resource Conservation and
Recovery Act (PL 94-580).
     In the absence of other standards for comparison at the present
time, drinking water standards and leachate from a natural gypsum were
selected as reference standards for the leachate tests.
     Leaching and activity tests were performed on atmospheric and pres-
surized fluidized-bed combustion systems; once-through and regenerated
spent sorbent; bed and carry-over materials; and processed and unproc-
essed spent sorbent.
     Leaching and activity tests show that:
     •  No water pollution is expected from the leaching of
        those trace-metal ions for which drinking water stan-
        dards exist, since the leachate meets drinking water
        standards.
     •  An insignificant amount of magnesium is leached out, even
        for dolomite sorbent.
     •  Sulfide may not be a problem for the once-through sorbent,
        since the sulfide concentration in the leachate is below
        detection limits.

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     •   The total dissolved organics are below detection limits.
     •   Residual activity,  reflected by heat release upon expo-
        sure to water,  has  not been observed to be significant
        with spent sorbent  from once-through pressurized oper-
        ation.   The heat release property of spent sorbent,
        however, is a function of the FBC operating conditions -
        for example, temperature, stone residence time,  degree
        of sulfation and calcination, and degree of dead-burning.
     •   Heat release from the spent sorbent in the atmospheric
        FBC system is judged an environmental concern for direct
        disposal.  This is  due to the large amount of calcium
        oxide present in the spent sorbent.
     •   Moderate heat release has occurred with the spent sor-
        bent from the regenerative pressurized FBC system.
        This, also, may be an environmental concern.
     •   Potential concerns in the leachates are the high con-
        centrations of calcium, sulfate (SO,), pH, and total
        dissolved solids (TDS), which are above drinking
        water standards.
     •   The addition of ^20 wt % ash to the spent sorbent
        improves leachate quality.  Codisposal of spent  sor-
        bent and ash, thus, can reduce the adverse environ-
        mental impact.
     •   The environmental impact is reduced by room-temperature
        processing.
     A  preliminary comparison of environmental impacts is shown in the
following chart.

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   Sample
                        Sorbent Type
                                                   Environmental Farainet_ers_
                                  Heat Release*-
                                  Spontaneous Tenp.
                                  Rise (3g/20 ml)
                                    Trace
                                    Metal
                             Total
                            Dissolved
                             Solids
 Total
Organic
Carbon
                                                                pH
                                                                      Sulfide
Bed Material
           Pressurized FBC,
           once-through
                                     <0.2°C
Bed Material
           Pressurized FBC,
           once-through
                                     ed material/
fly ash
mixtures
Pressurized FBC,
once-through
Dolomite/
Limestone
                                     <0.2°C
Jypsum
                                     <0.2°C
*Based on results from limited samples available and subject to the procedures specified in the section on "Activity".
on
Pd Do not meet either the drinking water or gypsum leachate criteria
^j Pass gypsum leachate criteria but not drinking water standards
[_J Pass both drinking water and gypsum leachate criteria


SPENT  SORBENT  UTILIZATION

      The construction industry is considered  the  most  attractive market

area  for utilization because of  the need  to market  large quantities of

spent  sorbent  and the potential  demand for waste-based products in  con-

struction.   Utilization  options  include landfill,  road subbase, aggre-

gate,  concrete,  and cement.

       Integration of basic industries  (e.g., a cement plant)  with the

steam/power plant are potentially attractive  for  achieving resource and

energy conservation.

       Test  results show  that  stable,  solid compacts can be  produced  from

the  spent  sorbent and coal ash at ambient temperature  and  pressure.

Compressive strengths meet landfill  requirements  and may  permit sub-

stitution  for  concrete  in low-strength applications.

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     Tests results show pressing of spent sorbent and coal ash results
in an axial compressive strength of up to 90 MPa.  The compressive
strength of Portland cement is 103 to 172 kPa.
OCEAN DISPOSAL/UTILIZATION
     EPA policy is to phase out ocean disposal of industrial waste by
1981.  Permits for such disposal are unlikely, although research per-
mits may be issued.
     The spent sorbent/ash, however, could potentially be utilized as a
habitat for marine life.

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                                SECTION 3
                             RECOMMENDATIONS

SPENT SORBENT CHARACTERISTICS
     Obtain spent sorbent from operating test  units  and demonstration
plants to determine characteristics.   Compare  results with projections.
Revise models, as needed, to predict  spent sorbent characteristics.
SPENT SORBENT/ASH DISPOSAL
     Continue leaching and heat-release tests.   These tests should
include sorbents generated with the following  variations in process
parameters:
     •  Once-through/regenerative sorbent  system
     •  Atmospheric pressure/pressurized combustor
     •  Limestone/dolomite sorbent
     •  One-step/two-step regeneration
     •  Calcium-based sorbent/alternative  sorbent
     •  Wide range of operating conditions within each process
        variation.
Emphasis should be placed on the environmental impact from the disposal
of sorbent produced by a once-through system under atmospheric pressure,
since that is the process considered  for the first-generation plants.
     Extend leaching tests to include pH,  temperature, and salinity of
leachate-inducing liquid.  Extend leachate measurements to include other
potential pollutants, according to the EPA comprehensive analysis
concept.  '
     Perform column-leaching tests to investigate larger amounts of
spent sorbent, its permeability, its  possible use as landfill, rate of

-------
leachate generation, and soil attenuation.  A Lysimeter can be designed
to simulate actual disposal geometry, seasonal changes, average natural
precipitation, and soil composition.
     Continue investigation of processing spent sorbent to reduce the
residue's environmental impact.  Spent sorbent from atmospheric-pressure
operation is of particular interest since the heat release of this mate-
rial may prevent direct disposal.
     Perform field tests to monitor ground and surface water and to
generate information for commercial projection.  The success of a land
disposal operation depends greatly on the design, construction, and
operation based on the geology, hydrology, topography, and climate of a
particular site.
SPENT SORBENT/ASH UTILIZATION
     Perform tests to investigate spent sorbent/ash blending to form a
compact at ambient temperature/pressure.  Perform freeze-thaw and sul-
fate resistance tests on the fixed compact.
     Investigate the effect of spent sorbent composition (e.g., silica,
alumina, calcium sulfate) on the low-temperature processing option.
     Investigate alternative applications, such as agricultural use.
     Develop preliminary process design and economics based on screening
tests, for processing options that are attractive.
OCEAN DISPOSAL/UTILIZATION
     Implement the marine ecological assessment program to determine
deleterious effects of spent sorbent/ash and to conduct flow-through
tests with a spent sorbent habitat.

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                                SECTION 4
              CHARACTERISTICS OF FBC ASH AND SPENT SORBENT

     Fluidized-bed combustion power generation systems,  operated at
atmospheric pressure and elevated pressures, produce spent sorbent mate-
rials (limestone- or dolomite-based) that may require processing to
generate a material environmentally suitable for disposal, or to con-
vert them into useful by-products.  The properties of these spent sor-
bents (size distribution, composition,  etc.) are sensitive to a number
of combustor operating and design factors.   The purpose  of this study
is to project the most probable base characteristics for the spent sor-
bents that will permit sorbent processing and environmental impact
studies to proceed on a meaningful and  consistent basis.
     Spent sorbent characteristics are  projected; and fresh sorbent,
coal, and coal ash properties are also  discussed.  The assumptions and
data applied to project the spent sorbent properties are summarized to
permit future refinement as new information becomes available.   A per-
spective on the sensitivity of the spent sorbent characteristics to the
design and operating conditions and the applied assumptions is  also
provided.
FACTORS INFLUENCING THE SPENT SORBENT CHARACTERISTICS
     The following factors have a significant influence  on the char-
acteristics of the spent sorbent produced by the fluidized-bed  combus-
tion system:
     •  Coal properties - sulfur content, heating value, and ash
        content
     •  Fresh sorbent properties - type of sorbent (limestone or
        dolomite), composition, physical structure, and  attrition
        b ehavior
                                    10

-------
     •  Fluid-bed combustion system concept - power cycle
        (atmospheric-pressure boiler, pressurized boiler, adi-
        abatic combustor), once-through or regenerative operation,
        and sorbent pretreatment
     •  Fluid-bed combustor design and operating conditions -
        temperature, pressure, excess air, residence times of
        sorbent and gas, calcium-to-sulfur feed ratio, superficial
        velocity, coal and sorbent feed size, coal and sorbent
        feeding, internals design, distributor design, turndown
        operating conditions, and so forth.
     •  Regeneration process concept - once-step (high-temperature)
        process or two-step (low-temperature) process, point of
        fresh sorbent feeding, and point of spent sorbent
        withdrawal
     •  Regenerator design and operating conditions - temperature,
        pressure, reactant-gas (or solid reductant) composition,
        residence times of sorbent and gas, multiple stages or
        regions, internals design, distributor design, and super-
        ficial velocity, and the like
     •  Other system components design - particulate control, sor-
        bent circulation, and so forth.
     The list is not exhaustive, but the factors presented appear to be
the most significant.  The following spent sorbent characteristics are
considered:
     •  Composition (major components) - CaO, CaCO_, CaS, CaSO,,
        MgO, and other components present in fresh sorbent which
        are retained in the spent sorbent
     •  Size distribution of bed material and overhead fines.
     Projections of the relative amounts of coal ash and spent sorbent
are also considered because of their important processing implications.
Trace element content of the spent sorbent has not been projected.
                                    11

-------
     Figure 1 is a general sorbent flow diagram for fluidized-bed com-
bustion.  A fluid-bed combustor is shown with two stages of particulate
control equipment:  the first stage represents recycling of coarse
sorbent and ash (or carbon) to the combustor, and the second stage
represents removal of ash and sorbent fines from the combustor system
to be processed or regenerated.  The sorbent material to be processed
or regenerated then consists of the sorbent stream withdrawn from the
combustor, having the bulk bed characteristics,  and the sorbent-fines
stream withdrawn from the particulate control system.  If the operation
is once-through, these two streams would represent the spent sorbent.
     For the regenerative case another processing step with particulate
control is shown in Figure 1,  The regenerated sorbent is recycled to
the combustor.  The spent sorbent is represented by the fine material
withdrawn from the combustor and regenerator particulate control systems,
plus the sorbent withdrawn either from the combustor or the regenerator
bulk beds.  In the regenerative case fresh sorbent may be injected into
the process in either the combustor or the regenerator.  The nature of
the spent sorbent may also be sensitive to the exact location within
the bulk beds from which it is withdrawn (e.g.,  near the distributor in
an oxidizing region or near the top of the bed in a reducing region) .
     While all of the factors that can be identified cannot be entirely
accounted for, a reasonable projection of the spent sorbent properties
in terms of the major factors is possible.
Fresh Sorbent, Coal, and Coal-Ash Properties
     Sorbent (limestone and dolomite) compositions were studied in some
detail for both fluidized-bed combustion systems and limestone wet-
scrubber systems.  A summary of compositions for limestone and dolomite
is shown in Tables 1 and 2.  Limestone 1359 and dolomite 1337 were pre-
viously used as bases for fluidized-bed combustion process studies and
have the compositions shown in Tables 3 and 4.  ^
     Coal compositions were analyzed for a large number of coals from
the eastern U. S.  Mean values, standard deviations, and minimum and
maximum values are given for trace elements, minor and major elements,

                                   12

-------
Sorbent
Coal
                        V
                   Fluid-Bed
                   Combustor
                                                                   Curve 685696-A
Flue
Gas
                                  v
...     /To Regenerationx
fines,/       Qr

      I   Spent Sorbent
       v   Processing
                                   Utilized
                                  Sorbent
Regenerated
   Sorbent
                         v
                          General
                       Regeneration
                          Process
                                     Alternative Streams
                                       to Spent Sorbent
                                          Processing
                                                                               i
                                       Acid
                                       Gas
                                   V
                                               Fines,
                                               Sorbent
                                               (and ash)
                                                                                      To Spent
                                                                                 Sorbent Processing
          Figure  1.   Fluidized-Bed Combustion  General Sorbent  Flow Diagram

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       TABLE  1.   CHEMICAL  AND MINERALOGICAL  PROPERTIES OF LIMESTONES
Sorb.
Type
Ign.
loss
Composition wt %
CaO
MgO
Fe2°3
Na20
K20
Mn02

Gan gue
firain
Size,
coded(c)
Unit-cell
Length
a, A
Crystal-
lite
Size, u
                                            Calcites
1336
1343
1350
1355
1359
1363
1368
1369
1377
1379
1677
1679
1681
1685
1687
1691
1692
1693
43.2
42.5
43.6
33.1
43.6
36.1
40.1
43.4
27.3
41.3
26.5
42.7
37.7
43.9
43.2
38.6
42.9
42.7
53.4
54.1
54.7
41.5
54.7
42.2
49.1
54.3
28.4
48.7
31.2
52.1
44.9
48.2
53.4
47.3
54.8
53.3
1.5
0.5
0.5
1.2
0.7
0.9
1.3
0.8
2.8
2.2
1.1
1.4
2.2
4.6
1.2
1.7
0.3
0.6
0.2
0.4
0.2
1.6
0.1
1.6
0.9
0.1
5.1
0.4
0.7
0.3
0.6
0.4
0.1
0.6
0.1
0.2
0.0057
0.0115
0.0056
0.2542
0.0056
0.1406
0.0898
0.0396
0.2326
0.1526
0.0735
0.0917
0.0623
0.0505
0.0284
0.0860
0.0256
0.0573
0.0284
0.0575
0.0282
0.4349
0.0282
0.6518
0.2636
0.0736
3.9985
0.2818
0.2058
0.0802
0.2056
0.0280
0.0363
0.3438
0.0286
0.1031
0.0085
0.0345
0.0451
0.0268
0.0141
0.1278
0.9165
0.0085
0.0872
0.0411
0.0110
0.0086
0.0093
0.0617
0.0284
0.0430
0.0086
0.0086
1.6
0.7
2.6
24.6
0.9
18.0
8.8
0.8
43.8
6.6
45.0
3.6
13.8
3.0
1.5
12.4
0.6
2.8
3.0
1.0
2.0
1.0
1.0
1.0
2.6
1.0
1.0
3.0
1.0
1.0
1.0
2.8
2.6
1.0
3.0
1.0
4.978
4.989
4.986
4.982
4.985
4.989
4.978
4.987
4.975
4.930
4.987
4.975
4.985
4.986
4.986
4.984
4.985
4.985
0.149
0.167
0.177
0.024
0.124
0.124
0.097
0.127
0.162
0.097
0.177
0.048
0.115
0.145
0.177
0.107
0.186
0.160
Dolomites
1337
1340
1341
1367
1380
1678
1680
1686
1688
1690
1695
1701
1702
47.2
46.2
46.7
43.9
46.7
30.8
42.4
46.9
47.1
34.0
42.2
42.5
44.6
29.0
30.7
29.8
32.5
30.4
19.7
28.2
29.7
29.1
22.4
28.9
34.5
33.2
22.7
19.9
22.4
15.8
21.9
14.5
19.3
22.0
22.2
15.5
23.1
13.5
18.0
0.2
1.4
0.3
5.2
0.3
1.3
0.9
0.2
0.5
1.1
0.6
4.3
0.8
0.0053
0.0054
0.0053
0.0224
0.0266
0.0830
0.0346
0.0159
0.0159
0.0396
0.0289
0.0920
0.0277
0.0264
0.0269
0.0266
0.0280
0.0266
0.9826
0.2534
0.0266
0.0265
1.1286
0.0289
0.1553
0.2715
0.0079
0.6890
0.0080
0.5610
0.0080
0.0415
0.0691
0.0080
0.0159
0.0792
0.0087
0.4542
0.0083
1.0
2.0
0.7
7.0
0.6
35.0
9.2
1.0
0.5
24.2
4.8
8.6
4.6
2.0
1.5
3.0
1.0
2.5
1.5
1.0
3.0
1.5
3.0
3.0
1.3
1.3
4.811
4.808
4.806
4.816
4.805
4.808
4.806
4.806
4.807
4.809
4.808
4.822
4.810
0.119
0.141
0.211
0.085
0.189
0.141
0.171
0.189
0.182
0.098
0.189
0.090
0.070
Mixtures
1360
1694
44.5
38,0
45.0
37.2
7.2
12.4
0.7
0.6
0.0277
0.0310
0.0277
0.0310
0.0888
0.0093
3.4
12.6
2.5
3.0
4.910
4.886
0.135
0.159
Magnesites
1375
1376
46. 4
46.8
15.8
7.1
32.2
41.0
0.9
0.8
0.0322
0.0154
0.1340
0.0256
0.0080
0.0154
10.0
28.0
2.5
2.5
4.720
4.720
0.147
0.220
(a)  Calculated from composition of calcine.
(b)  Accessory minerals.
(c)  1 x fine, <63 u; 2 = medium, 63-250 u;  3 = coarse, >250 u.
*Reproduced  from "Investigation of the Reactivities  of Limestone to Remove Sulfur Dioxide from
 Flue r,as,"  TVA, 1971, PB 202-407.
                                              14

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             TABLE 2.   ACCESSORY  MINERAL CONTENT OF LIMESTONES*

Sorb.
Type


Total
Accessory minerals (wt %)

Quartz

Illite
Montmor-
illonite

Chert
Tremo-
lite
Limo-
nite
Feld-
spar
Musco-
vite
Glass
frit
                                           Calcites
1336
1343
1350
1355
1359
1363
1368
1369
1377
1379
1677
1679
1681
1685
1687
1691
1692
1693
1.6
0.7
2.6
24.6
0.9
18.0
8.8
0.8
43.8
6.6
45.0
3.6
13.8
3.0
1.5
12.4
0.6
2.8
0.0
0.3
1.6
16.0
0.4
6.0
4.2
0.4
13.1
4.6
14.0
1.7
4.6
1.0
0.5
3.8
0.3
1.0
0.0
0.1
0.9
8.6
0.0
6.0
4.2
0.4
13.1
0.0
0.0
1.7
4.6
1.0
0.5
8.0
0.2
- 1.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
14.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4.6
0.9
0.4
0.0
0.0
0.0
1.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.0
0.0
0.0
0.4
0.0
4.5
0.0
3.0
0.2
0.0
0.1
0.0
0.6
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
6.0
0.0
0.0
13.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.4
0.0
0.0
0.0
0.0
0.0
14.0
0.0
0.0
0.0
0.1
0.0
0.0
0.0
Dolomites
1337
1340
1341
1367
1380
1678
1680
1686
1688
1690
1695
1701
1702
1.0
2.0
0.7
7.0
0.6
35.0
9.2
1.0
0.5
24.2
4.8
8.6
4.6
0.7
2.0
0.0
0.3
0.1
15.7
3.1
0.3
0.2
20.6
1.4
3.0
2.3
0.0
0.0
0.0
0.0
0.1
15.7
0.0
0.3
0.2
3.6
0.5
0.0
2.3
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.3
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.5
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.4
0.0
0.0
0.1
0.0
0.0
6.7
o.o
1.8
0.0
0.0
0.0
0.0
0.0
5.6
0.0
0.0
0.0
0.1
0.0
0.1
1.8
3.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
1.4
0.0
0.0
0.0
0.0
0.0
0.0
0.3
0.0
3.0
0.0
0.1
0.0
0.0
0.0
0.0
Mixtures
1360
1694
3.4
12.6
0.0
4.0
0.4
0.0
0.0
0.0
1.3
0.0
0.0
4.0
1.3
0.0
0.0
0.0
0.0
0.6
0.4
0.0
Magnesites
1375
1376
10.0
28.0
1.0
0.7
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
*Reproduced from "Investigation of the Reactivities  of Limestone to Remove Sulfur Dioxide
 from Flue Gas," TVA, 1971, PB 202-407.
                                           15

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TABLE 3.  ANALYSIS OF LIMESTONE NO. 1359
                                     , (4)
Component            As-Received, wt %
S10,
2.
A12°3
Fe2°3
MgO
CaO
Ti02
SrO
Na 0
0.85

0.30
0.17
1.07
97.
<0.05
0.07
<0.02
                            <0.05
 TABLE 4.  S02 SORBENT ANALYSIS USED FOR

PRELIMINARY FLUIDIZED-BED BOILER ANALYSES

Component
Si°2
A12°3
MgO
CaO
Ti02
SrO
Na2°
As-Received (4)
Dolomite
1337, wt %
0.78
0.15
0.25
45.0
53.0
0.02
<0.03
<0.02
                                 <0.03
                   16

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total sulfur and ash in Table 5.  The variability of coal compositions
is very great for almost all components.  An Ohio-Pittsburgh No. 8 Seam
coal was previously used as the basis for fluidized-bed combustion
                (3)
process studies.     Its composition and the associated ash composition
are shown in Table 6.
     Expected coal and fresh sorbent size distributions are presented
            (3)
in Figure 2.     The size distribution is typical of that obtained from
commercial crushers.  Although finer sizes or narrower size distributions
may have possible process advantages, they require pulverization and/or
more extensive size classification.
Plant Sulfur Balances
     The required sulfur removal efficiency for the total fluidized-bed
combustion power plant is determined by the existing SO  emission stan-
                                                       X
dard for coal-fired power plants and is given by the following expression:

                                      SH
1
                           ~
                                  W0 2 x
                                   O
where e  is the plant sulfur removal efficiency, S is the SO  emission
       D                                                    «
standard in kg SO«/GJ, W  is the coal sulfur content (weight fraction) ,
                 Z      o
and H is the coal heating value.  This relationship is illustrated in
Figure 3 for an emission standard of 0.516 kg SO_/GJ which corresponds
to the present U.S. EPA standard for large coal-fired boilers.  Two
coal heating values, which span the range of typical values, are
considered.
     The sulfur removal efficiency required in the fluidized-bed com-
bustor is dependent upon the sulfur removal or recovery efficiencies of
the individual processing systems comprising the power plant sulfur
removal system (i.e., the regeneration system, the sulfur recovery sys-
tem and the spent sorbent processing system) and the process logic
applied to the sulfur removal system (i.e., once-through versus regen-
erative operation, recycle of tail-gases to the fluid-bed combustor or
the sulfur recovery process, withdrawal of spent sorbent before or
after the regeneration step, etc.).

                                   17

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 TABLE 5.   MEAN  ANALYTICAL VALUES FOR ALL  101 COALS*
Constituent
As
B
Be
Br
Cd
Co
Cr
Cu
F
Ga
Ge
Mg
Mn
Mo
Ni
P
Pb
Sb
Se
Sn
V
Zn
Zr
Al
Ca
Cl
Fe
K
Mg
Na
Si
Ti
ORS
PYS
SUS
TOS
SXRF
ADL
Mois.
Vol
FIXC
Ash
Btu/lb
C
H
N
0
HTA
LTA
Mean
14.02 ppm
102.21 ppm
1.61 ppm
15.42 ppm
2.52 ppm
9.57 ppm
13.75 ppm
15.16 ppm
60.94 ppm
3.12 ppm
6.59 ppm
0.20 ppm
49.40 ppm
7.54 ppm
21.07 ppm
71.10 ppm
34.78 ppm
1.26 ppm
2.08 ppm
4.79 ppm
32.71 ppm
272.29 ppm
72.46 ppm
1.29 7.
0.77 %
0.14 %
1.92 %
0.16 7,
0.05 %
0.05 %
2.49 %
0.07 %
1.41 %
1.76 %
0.10 %
3.27 %
2.91 7,
7.70 %
9.05 %
39.70 %
48.82 %
11.44 %
12748.91
70.28 '/.
4.95 %
1.30 7,
8.68 %
11.41 %
15.28 %
Std
17.70
54.65
0.82
5.92
7.60
7.26
7.26
8.12
20.99
1.06
6.71
0.20
40.15
5.96
12.35
72.81
43.69
1.32
1.10
6.15
12.03
694.23
57.78
0.45
0.55
0.14
0.79
0.06
0.04
0.04
0.80
0.02
0.65
0.86
0.19
1.35
1.24
3.47
5.05
4.27
4.95
2.89
464.50
3.87
0.31
0.22
2.44
2.95
4.04
Min.
0.50
5.00
0.20
4.00
0.10
1.00
4.00
5.00
25.00
1.10
1.00
0.02
6.00
1.00
3.00
5.00
4.00
0.20
0.45
1.00
11.00
6.00
8.00
0.43
0.05
0.01
0.34
0.02
0.01
0.00
0.58
0.02
0.31
0.06
0.01
0.42
0.54
1.40
0.01
18.90
34.60
2.20
11562.00
55.23
4.03
0.78
4.15
3.28
3.82
Max.
<>3.00
224.00
4.00
52.00
65.00
43.00
54.00
46.00
143.00
7.50
43.00
1.60
181.00
30.00
80.00
400.00
218.00
8.90
7.70
51.00
76.00
5350.00
133.00
3.04
2.67
0.54
4.32
0.43
0.25
0.20
6.09
0.15
3.09
3.78
1.06
6.47
5.40
16.70
20.70
52.70
65.40
25.80
14362.00
80.14
5.79
1.84
16.03
25.85
31.70
Note:  Abbreviations other than standard  chemical symbols:   organic  sulfur
       (ORS),  pyritic sulfur (PYS),  sulfate sulfur (SUS),  total  sulfur
       (TOS),  sulfur by X-ray fluorescence  (SXRF), air-dry loss  (ADI,),
       moisture  (Mois), volatile matter  (Vol), fixed carbon (FIXC),  high-
       temperature  ash (HTA), low-temperature ash (LTA).
*Reproduced from "Occurrence and Distribution of Potentially Volatile
 Trace Elements  in  Coal," R. R. Ruch,  H.  J. Gluskoter, N.  F. Shimp  1974
 EPA-650/2-74-054 (Reference 5).                                 '      '
                                  18

-------
               TABLE 6.  OHIO PITTSBURGH NO. 8 SEAM COAL*
SAMPLE:  Run of mine - as

PROXIMATE ANALYSIS  (wt %) :
ULTIMATE ANALYSIS  (wt %):
  (includes moisture)
GROSS HEATING VALUE:

NET HEATING VALUE:

ASH ANALYSIS (wt %):
FUSIBILITY OF ASH:



PARTICLE DENSITY:


GRINDABILITY (Hardgrove)

FREE SWELLING INDEX:
received

  Moisture
  Volatile matter
  Fixed carbon
  Ash
  C       71.2
  H        5.4
  0        9.3
  N        1.3
  S        4.3 (^60% organic  &  ^40%  pyritic)
  Ash      8.5
         100.0
30,238
29,075
Si02
M2°3
Fe2°3
Ti02
P2°5
CaO
MgO
Na2°
K2°
so3
J/g
J/g
45.3
21.2
27.3
1.0
0.11
1.9
0.6
0.2
1.8
0.7
100.1
  Initial deformation temperature  1138°C
  Softening temperature           1221°C
  Fluid temperature               1327°C

  Coal - ^1.4 g/cc
  Ash - ^2.8 g/cc

  50-60

  5-5.5
*(Source of data:  USBM, Pittsburgh, PA.)
                                    19

-------
                                                           4   Size Distribution for Elutriated
                                                           5   Solids from Primary Combustor
                                                               & Carbon Burn-up Cell
                                                               Range of Size Distribution
                                                           — Obtainable from Koppers
                                                               Reversible Hammermill
                                                                                              98.5
99
                                  100                 1000
                                    Particle Size Microns
10000
                    Figure 2.   Size Distribution of Coal  Feed

-------
                                                   Curve 684848-^
    0.9
    0.8
S  0.6
1
^

3
•o
0>
cr
O)
o:
    n c
    U.!?
    0.4
0.3
    0.2
    0.1
      0
                                  Standard =516 ng/J
                                     Coal Heating Value,

                                        MJ/kg(Btu/lb)

                                     	23.3 (10,000)

                                     	35.0 (15,000)
               0.01    0.02    0.03     0.04    0.05

                      Weight Fraction Sulfur in Coal
                                                   0.06
           Figure 3.  Required Combustor Sulfur Removal Efficiency
                                  21

-------
     Figure A shows general process flow diagrams used for sulfur bal-
ances for once-through and regenerative operations.  Sulfur recovery or
removal efficiencies are defined for each of the processing systems:
e  for the combustor, e  for the regenerator,  e  for the spent sorbent
 C                     R                       "
processing system, and e   for the sulfur recovery process.  Sulfur
                        bK
losses may occur because of gas, liquid,  or fines losses,  or intentional
tail-gas release.  The results of simple material balances for some
alternative process logics are shown in Table  7.  The possibility of
the introduction of additional sulfur into the process by  means of
reductant-gas generation from sulfur-bearing fuels or other sources has
been neglected, but in come cases it could be  a significant factor.  A
decrease in the sulfur removal efficiency of any processing step will
increase the required combustor sulfur removal efficiency  and also the
required rate of fresh sorbent consumption.  Recycling tail-gases to
the combustor also increases the "effective" sulfur content of the coal.
     From the relation shown in Table 7,  it  is evident that,  for the
cases with no tail-gas recycle, the sulfur removal efficiencies of the
separate processing steps must be greater than the required plant sul-
fur removal efficiency.  For the cases with  recycle to the combustor,
the sulfur removal efficiencies of the individual processing steps can
be less than the overall sulfur removal efficiency, but  the effective
coal sulfur content will increase greatly as the efficiencies decrease.
For example, the case of once-through operation, with the  tail-gas from
the spent sorbent process being recycled to  the combustor, is illustrated
below for a 5 wt % sulfur coal (85 percent overall sulfur  removal
required):
                                                   M/M (E_ - 1)

ep
0.9
0.8
0.7
Required
ec
0.863
0.876
0.890

Vws
1.094
1.21
1.36
                                                      1.111
                                                      1.247
                                                      0.424
                                    22

-------
Sorbent _

Coal
t Stack
| Gas
£c
Combustor

Spent
Sorbent
t Tail
Gas
£P
Spent
Sorbent
Processing
/' To Stack or \
^Recycle to Combustory

Processed
Sorbent

Figure 4A.  General Once-through Operation Sulfur Balances
t Stack
| Gas
Sorbent^
£c Sor
Coal *| Combustor CircL

l t Tail
! 1 ^
1 „
Spent
bent £R ^Sorbent
lation Regenerator

Acid
U - Sulfur Removal, Recovery,^ Gas
y Or Retention Efficiency )

t Tail
Gas
£SR
• Sulfur
Recovery
\ Tail
1 Gas
£P
t Spent
Sorbent
Processing
/ To Stack \
\or Recycle/
Sulfur
/'To Stack \
or Recyclej
	 *

Figure 4B.  General Regenerative Operation Sulfur Balances
                            23

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                                  TABLE 7.   PLANT  SULFUR BALANCE RELATION
S3
                                                  Required Conibustor
                                                Sulfur Removal Efficiency
Operation
On ce-through

  Tail-gas exhausted


  Tail-gas recycled
    to combustor

Regenerative

  Tail-gas exhausted;
    spent sorbent withdrawn
    after regeneration step
  Tail-gas exhausted;
    spent sorbent withdrawn
    before regeneration step
  Sulfur recovery tail-gas
    recycled to  combustor;
    spent sorbent after
    re genera tion

  Sorbent processing tail-gas
    recycled  to sulfur  recovery
    process;  spent sorbent
    after  regenerator
                                                                                   Effective Sulfur Content
                                                                                       of Combustor Coal
                                                                    -1
                                                                                   w., u-u-
                                                "^SR"" + ""W^-VsR*1'
                                                     SR
       e = Sulfur removal, recovery, or retention efficiency; subscript C = combustor, R = regenerator,
           P = spent sorbent processing, SR = sulfur recovery process.
       M = Sorbent makeup rate, moles calcium per mole of sulfur fed in combustor coal.
       U = Sorbent utilization; subscript R = after regeneration, subscript C = after combustor.
      W  = Wt. fraction of sulfur in coal.
       O       ___             .. _  .       . -

-------
       •p
where W  is the effective coal sulfur content.  If the sulfur removal
efficiency of  the spent sorbent processing system drops to 70 percent,
the coal has an effective sulfur content 36 percent greater than its
actual content, and  the sorhent consumption rate must increase by about
43 percent, compared to the case of 100 percent sulfur removal effi-
ciency for the spent sorbent processing system.
     The purpose of  this discussion is only to point out the complex
nature of  the  system.  Projections of sorbent consumption rates based
solely on  laboratory performance could easily differ from the ultimate
commercial performance by as much as a factor of two.
PROJECTION OF  SPENT  SORBENT AND COAL ASH PRODUCTION RATES
     A plant material balance shows in general that the mass of coal
ash per unit mass of spent sorbent calcium, A, is given by
where  a  is  the mass  fraction of ash in the coal, W  is the coal sulfur
                                                  o
mass fraction, and M is  the molar makeup rate of sorbent, moles of cal-
cium per mole  of sulfur  fed.
     For a  once-through  operation
                              M = ^  ,                          (3)

where  e_ is the required combustor sulfur removal efficiency and U  is
       C                                                         ^
the sorbent utilization  obtained in the combustor.  The sorbent utiliza-
tion is  a function of the sorbent properties, the combustor operating
conditions,  and the  combustor design.  If it is assumed that the spent
sorbent  processing scheme has a high sulfur efficiency, so that sulfur
losses from it can be neglected, then e  = e  as in equation 1, and
                   A =
i-    SAH   6rx.               w)
    W  2 x 10
     5
                                    25

-------
The quantity A/(aU ) is shown in Figure 5 as a function of the coal sul-
                  L*
fur content.  The value of a may range between 0.02 and 0.30 for eastern
coals.  For once-through operation U  is expected to range between 0.20
and 0.90.  Thus, the ratio A (mass ratio of ash to spent sorbent calcium)
may range between about 0.1 and 200 for once-through operation.
     For regenerative operation the sorbent makeup rate is a function
not only of the combustor design and operating conditions, but also of
the regenerator design and operating conditions.   It is a function of
the required combustor sulfur removal efficiency and the other process
variables that are not yet well understood.  The sorbent attrition
behavior may be the controlling factor in many cases where the rate of
sorbent deactivation is low.  For regenerative operation M may range
between 0.2 and 2.0, and the ash/sorbent ratio may range between about
0.15 and 150, a range not much different from the once-through case.
Sorbent Utilization for Once-through Operation
     The ranges of sorbent utilization (fraction of calcium as CaSO,  or
CaS) to be expected from a once-through fluidized-bed combustor can be
projected from the results of Thermogravimetric (TG)  experiments.   These
results have generally agreed with batch fluidized-bed and continuous
operation (Exxon miniplant) results.  Table 8 lists projections for
500 ym sorbent particle diameters and 90 percent sulfur removal effi-
ciency, based upon the TG results.  Three fluidized-bed combustion sys-
tems are considered:  the atmospheric-pressure boiler, the pressurized
boiler (at high and low excess air rates), and the adiabatic combustor.
In all three of these systems calcining conditions are expected to pre-
vail (except, possibly, with the pressurized boiler at turndown).   Both
limestones and dolomites are considered as general classes of sorbents
though performance will differ within these general classes.
     For continuous once-through operation a distribution of sorbent
utilization will exist in the spent sorbent.  If the kinetics of desul-
furization are first-order with respect to the S02 concentration and
                                   26

-------
                                              Curve 685679-A
     1000
 o
 CO
 O
CD
.0
O
CO

"c
CD
CL
CO
 .c
 GO
 o
 o
 co
 ct:
 oo
 uo
 na
      100
       10
                           Weight Fraction Ash in Coal
                           Average Sorbent Utilization,  Fractional
                        Coal Heating Value
                      = 35.0MJ/kg (15,000 Btu/lb)
                23.3MJ/kg
              (10,000 Btu/lb)
                                  1
                          2345
                         Weight percent sulfur in coal
Figure 5.   Ratio of Ash to  Spent Sorbent for Once-through  Operation
                                27

-------
                            TABLE  8.   PROJECTIONS OF ONCE-THROUGH SORBENT UTILIZATION*
                 System
                                        Conditions
                                                                               Percent of Available
                                                                                 Calcium Utilized
                                      Limestone
                  Dolomites
N)
oo
        Atmospheric-Pressure
        Boiler
Pressurized Boiler

  Low excess air (10%)


  High excess air (100%)


Adiabatic Combustor



  Boiler turndown
                               100 kPa, 815-870°C
                               10-25% excess air, 15-13%
                                       CO,
                                    calcining
1000 kPa, 900-1000°C
15% C02, calcining

1000 kPa, 900-1000°C,
8.5% C02, calcining

1000 kPa, 900-1000°C,
300% excess air, 4% CO ,
calcining

Temperature down to ^750°C,
carbonating condition in the
pressurized boiler case,
calcining conditions in the
other cases
                                       25-35
                   30-40
40-50


40-50


40-50
80-90


80-90


50-80
                                                                         Same utilization as at  full
                                                                         capacity for all cases  except
                                                                         pressurized boiler.   For  pres-
                                                                         surized boiler  limestone  will
                                                                         not react under carbonated
                                                                         conditions; dolomite  will be
                                                                         utilized 50-70% under carbonated
                                                                         conditions.
       *Basis:  500 \im particle diameter, 90% sulfur removal.

-------
the unreacted sorbent concentration, and if the fluidized-bed corabustor
is perfectly mixed, then it can be shown that the sorbent utilization
is distributed as follows:
                    F(U < X) = 1 -  (1 - X) U       ,                (5)
where F(U < X) is the fraction of the spent sorbent having a utilization
less than X, and U is the average spent sorbent utilization.  This
result is also independent of the distribution of sulfur releases within
the fluidized-bed combustor.  The once-through distribution of sorbent
utilization is plotted in Figure 6  for average utilizations ranging
from 0.1 to 0.9.  This distribution should be a reasonable approxima-
tion to be applied in cases where the processing or utilization of the
spent sorbent is sensitive to its composition distribution.
     The sorbent particle size also influences the degree to which it
can be utilized in a once-through operation.  Figure 7 illustrates this
influence.     The projections in Table 8 should be reasonable for
average particle diameters up to about 1000 urn; larger particle sizes
will require a reduction in the projection of the maximum sorbent
utilization.
Sorbent Re gener ability
     Two sorbent regeneration schemes have been considered for fluidized-
bed combustion:  the one-step, high- temperature regeneration and the
two-step, low-temperature regeneration.  Two factors of importance to
the characterization of the spent sorbents from these regenerative
processes are the required makeup rate of fresh sorbent for maintenance
of the combustor desulfurization efficiency, and the level of utiliza-
tion of the sorbent in the combustor and regenerator.
     The level of utilization of sorbent in the combustor would be less
than the maximum utilizations projected for once- through operation in
Table 8.  For the projection of the sorbent total sulfur content before
                                    29

-------
        1.0
 to
 M


§     0.8
|s
CD 
*^« ^r
o

c:


••§     0.4
       0.2
         0
                                   n        i        i        i        r


                                   U= Average Bed Sorbent Utilization
                  O.J     0.2     0.3     0.4     0.5      0.6    0.7


                                                       X


                     Figure 6.  Cumulative Distribution of Sorbent Utilization
                                                                                                o
                                                                                                c
                                                                                                -s
                                                                                                O1

                                                                                                CO
                                                                                                c_n

                                                                                                vT>

                                                                                                CD

                                                                                                o
                                                                                                I

                                                                                                .Cs
0.8     0.9    1.0

-------
                                                  Curve 695826-A
                                   -5 + 6]
                                           1013 kPa
                                           660 ppm SO,
                                           954°C
                                           11% 0
                                                 2
               10
100
                     Time/Minutes
1000
Figure 7.  Sulfation of Fully Calcined Tymochtee Dolomite

-------
and after regeneration, the following basis is applied and is illus-
trated in Figure 8:  The maximum sorbent utilization for a once-through
desulfurization operation and the maximum extent of regeneration of the
once-through sorbent are averaged to yield the assumed ultimate sorbent
utilization if the process were cycled an infinite number of times.  A
typical sorbent utilization differential as found in cyclic experiments
is then applied to project the sorbent utilization before and after
regeneration.
     Table 9 summarizes the results of the projections for the one-step
and two-step regeneration processes and lists the specific assumptions
applied.
     In a regenerative process the distribution of spent sorbent compo-
sition is expected to be much broader than in the once- through cases.
This statement follows from an examination of the distribution of the
number of spent sorbent cycles.  It can be shown that  the fraction of
particles in the spent sorbent residing in the system  for n cycles is

                       F(n) =
where M is the feed rate of fresh sorbent (moles calcium per mole sul-
fur fed) and S is the rate of sorbent circulation between the regenera-
tor and combustor (moles calcium per mole sulfur fed to combustor) .  The
cumulative distribution is given by
                          F(n>x)  =  MT-S    .                       (7)
and the average number of cycles  is
                                    + S\
                                                                    (8)
Equation 6 is represented in Figure 9 for four  average cycle numbers.
The distribution becomes very flat as the average cycle number is
increased or the ratio M/S is decreased.
                                    32

-------
                                                                             Curve 685692-A
                 Maximum
                 Utilization
               on First Cycle
         Sorbent
        Utilization
LO
               •  Maximum
               Regeneration
               on First Cycle
Cyclic
Sulfur fAverage -Assumed
Change)  Value for Infinite
       I Number of Cycles
Sulfur
Change
in
First
Cycle
                                                        Time
                         Figure 8.  Basis for Regenerative Sorbent Utilization Projection

-------
                              TABLE 9.  PROJECTED REGENERATIVE SORBENT UTILIZATIONS'
System
One-Step Regeneration
One-Step Regeneration
(at combustor pressure)
Limestone
uc(%)b
UR(%)C
Dolomite
nc(%)
UR(%)
Two-Step Regeneration
Limestone
uc(%) UR(%)
Dolomite
U_(%) R (%)
\j J\
        Atmospheric-Pressure

          Boiler
24
14
21.5
11.5
UJ
-e-
Pressurized Boiler
Adiabatic Combustor
35
35
25
25
49
32.5
39
22.5
3 9
39
29
29
73
48
63
38

         Based on values (lower)  given in Table 8.


        Assumes 50% regeneration  on first cycle for one-step process with limestone and 90% for dolomite

        and  30% for the two-step  process with limestone or dolomite.


        Assumed 10% sorbent utilization differential.



        U  =  utilization  of  the  sorbent in the combustor.
         \_»


        CU_ = utilization  of  the  sorbent in the regenerator.
         R
                                                                      (7)

-------
                                        Curve  685Snl-/'-
o>
                                 Average  _
                    Curve    No. Cycles (n)
      0   10  20  30  40  50   60  70  80  90  100
                        Number of cycles
    Figure 9.  Distribution of Cycle Number for Regenerative
              Spent Sorbent
                              35

-------
     A material balance around the combustor and regenerator results  in
the following relationship for the sorbent circulation rate S, moles  of
calcium circulated per mole of sulfur fed to the boiler:

                      s = (EC - MB) (uc - iy"1  ,                  (9)

where £  is the combustor sulfur removal efficiency, U  - U  is the sor-
       C                                              t-    K-
bent utilization differential, and U in the numerator is either UG or
TL, depending on whether the spent sorbent is withdrawn before (U ) or
after (U ) the regenerator.
        R
     For a regenerative system a specific value of the ratio M/S
(H l/(n-l)) is required in order to maintain the combustor sulfur
removal efficiency.  Although this ratio is a complex function of the
sulfur removal efficiency, the sorbent properties, the combustor, and
regenerator design and operating conditions, and so on, it is assumed
to have a representative value of 0.1 for the one-step and two-step
regeneration processes.
     Solving Equation 9 for the sorbent makeup rate M yields:
                                  Tr/e,
                             UC - UR +
Table 10 summarizes the projections for the sorbent makeup rate and the
quantity MU/EC> which corresponds to the fraction of the sulfur captured
in the combustor that is handled by the spent sorbent processing system.
The makeup rates range from 0.49 mole calcium per mole of sulfur fed to
0.75 mole of calcium per mole of sulfur fed to the combustor.
     There is considerable speculation involved in the projection of the
sorbent makeup rates in Table 10.  The assumption of constant value of
the parameters M/S and UC~UR for both regeneration schemes and for both
limestone and dolomite sorbents is certainly an oversimplification.  It
was also shown in Table 7 that the required combustor sulfur removal
                                    36

-------
                                       TABLE  10.    PROJECTED SORBENT MAKEUP  RATES'
System
One-step Regeneration
Limestone
«b „<:
A B
Md MU/e^'f'g M MU/E
C C
Dolomite
A
M
Atmospheric-Pressure 0.69 0.20 0.75 0.12 0.70
Boiler
Pressurized Boiler 0.63 0.26 0.68 0.20 0.57
Adiabatic Combustor 0.63 0.26 0.68 0.20 0.64
MU/EC
0.18
0.33
0.25
B
M
0.76
0.61
0.69
MU/EC
Two-Step Regeneration
Limestone Dolomite
A B A B
M MU/e_ M MU/e., M MtJ/e M MU/E
(j C (_• L.
0.10
0.28 0.61 0.28 0.66 0.23 0.49 0.42 0.52 0.39
0.18 0.61 0.28 0.66 0.23 0.57 0.32 0.62 0.28
aBasis: e = 0.85, M/S = 0.1 (equivalent to n = 11), V -lL = 0.1
O C K
M
sEc



                                       "„ -
 A - withdrawal of spent sorbent before regeneration  step (U-U )



 B - withdrawal of spent sorbent after regeneration step (U-U )
                                                          K


 M - sorbent make—up rate,  moles of calcium per mole  of sulfur



 U - sorbent utilization, subscript C = after combustor, R = after regenerator; no subscript

     means  either C or R depending on the point of spent sorbent withdrawal.



 £  - combustor sulfur removal  efficiency, fractional.



RMU/r  represents the fraction  of the captured sulfur handled by the spent  sorbent process.

-------
efficiency and the effective sulfur content of the coal may vary greatly,
depending upon the sulfur efficiency of the sulfur removal system sub-
systems and the choice of tail-gas recycle or tail-gas cleaning.
Sorbent Attrition and Elutriation
     The previous projections in this report have assumed that sorbent
attrition losses are negligible when compared to those of sorbent deac-
tivation.  This may not be a valid assumption in all cases, and in some
instances the sorbent makeup rate may be determined by the sorbent
attrition losses rather than by the sorbent activity losses.   When sor-
bent attrition is the controlling factor for the sorbent makeup, it is
expected that a substantial stream of spent sorbent will be generated
in the form of fines (probably <100 ym diameter)  having compositions
significantly different from those previously projected.
     The rate of particle attrition and elutriation in a commercial
fluidized-bed combustion power plant will be very sensitive to the oper-
ating conditions, the sorbent properties, and the hardware design:  sor-
bent feeders, distributor plates, bed internals,  cyclones, pneumatic
transport systems, and so on.  Experimental work conducted to address
attrition has not sufficiently characterized the phenomena to permit a
meaningful projection of the rate of sorbent fines generation, the coal
ash content of the sorbent fines, and the chemical composition of the
sorbent fines.
     In general, two stages of particulate control equipment  will col-
lect elutriated sorbent and coal ash.  Coarse material will be collected
in the first stage and recycled to the combustor.  The second-stage
equipment will trap the fine material.  This fine material would probably
not be recycled to the combustion because the fines content of the bed
and the resulting elutriation and/or fines recycle rate would increase
to extreme levels.  The sulfur content of the sorbent fines depends
upon their residence time in the desulfurizer and the rate of reaction
of the fine particles.
                                    38

-------
     While the rate of fines generation and the composition of these
fines cannot be projected with any confidence, it is almost certain that
some significant stream of sorbent fines will be produced and must be
accounted for in the spent sorbent characterization.  The following
assumptions are applied to determine the spent sorbent fines properties:
     •  Fines (<100 ym) are captured in the second-stage particu-
        late control equipment at a rate of 10 percent of the sor-
        bent makeup rate.
     •  Most (95 percent) of the coal ash is captured in the second-
        stage particulate control equipment.
     •  Negligible losses of fines occur in the regenerator and in
        the combustor due to the regenerated sorbent recycle stream
        (i.e., this stream is attrition resistant).
     •  The fines composition is equal to the bulk bed composition.
ASSESSMENT OF SPENT SORBENT PROJECTIONS FOR FLUIDIZED-BED COMBUSTION
     The basis for the fluidized-bed combustion power plant spent sor-
bent characterization is summarized in Table 11.  Tables 12 through 14
list the spent sorbent projections for once-through operation and for
the one-step and two-step regeneration processes.  Table 15 considers
the spent sorbent produced during plant turndown.  Fresh sorbent makeup
rates (calcium-to-sulfur mole ratio), rates of sorbent fines (<100 ym),
capture from the combustor particulate control equipment (calcium-to-
sulfur mole ratio), and the spent sorbent compositions are presented.
     The spent sorbent size distribution (coarse bed material) will be
similar to the sorbent feed size distribution given in Figure 2, with
the amount of modification dependent upon the sorbent attrition rate,
the fines recycle rate, and the bed elutriation rate.  The sorbent fines
size distribution will be similar to curve 4 in Figure 10, depending
upon the fines recycle rate, the bed attrition behavior, and the cyclone
particle capture performance.  Sorbent elutriation from the regenerator
vessel has been neglected.
     The projections will be updated as new information is developed.
                                    39

-------
       TABLE 11.  POWER PLANT BASIS FOR SPENT SORBENT PROJECTIONS
Plant Size = 600 MW
                   e

Plant Heat Rate - MJ/kWh (Btu/kWh) based on HHV
                                                                      (3)
     Atmospheric-pressure boiler           10.08               (9550) ,^\
     Pressurized boiler                     9.50               (8967)„,
     Adiabatic combustor                    9.60               (9096) ^


Coal (Ohio-Pittsburgh No. 8 Seam coal - Table 6)

     Sulfur - 4.3 wt %
     Ash - 8.5 wt %
     Heating value - 29.1 MJ/kg (12,500 Btu/lb)  LHV

Coal Rate - Mg/hr

     Atmospheric-pressure boiler          200.0                (220.4)
     Pressurized boiler                   187.7                (206.9)
     Adiabatic combustor                  190.4                (209.9)

Sulfur Removal Efficiency (%) - no recycle of tail-gases

     Power plant - 82.6
     Once-through combustor - 87          (assumes e  = 0.95 in Table 7)

     Regenerative combustor - 92          (assumes, e  = e  = 1.0,
                                                     P    R
                                          ecij = 0.90, Table 7)
Ash in Overhead Fines - 95%
Ash in Coarse Spent Sorbent - 5%
Sorbent Fines Rate - 10% of sorbent makeup rate

Limestone Type - 1359 (Table 3)

Dolomite Type - 1337 (Table 4)

-------
                        TABLE  12.  ONCE-THROUGH SORBENT OPERATION PROJECTIONS











Sorbent
Rate
(Ca/S)




Sorbent
Fines Rate
(Ca/S)
Composition of Spent Sorbent on a Molar-Calcium Basis,
Mole % (Total wt fractions in parentheses)




CaS04




CaS




CaO




CaC03


MgO
modes MgO
(per mole Ca)

Other
Components
(gm per
mole Ca
Ratio of
Wt of Ash
to Wt of
Spent Sorbent
Fines
Atmospheric-Pressure
  Boiler
Limestone 3.48
(1359)
Dolomite 2.9
(1337)
Pressurized Boiler
Limestone 2.18
(1359)
Dolomite 1.09
(1337)
Adiabatic Combustor
Limestone 2.18
(1359)
Dolomite 1.74
(1337)
0.35 25
(0.437)
0.29 30
(0.315)

0.22 40
(0.606)
0.11 80
(0.641)

0.22 40
(0.606)
0.17 50
(0.467)
0
(0)
0
(0)

0
(0)
0
(0)

0
(0)
0
(0)
75
(0.540)
70
(0.302)

60
(0.374)
20
(0.066)

60
(0.374)
50
(0.192)
0
(0)
0
(0)

0
(0)
0
(0)

0
(0)
0
(0)
oa
(0)
1.19
(0.367)

Oa
(0)
1.19
(0.281)

Oa
(0)
1.19
(0.327)
1.73
(0.023)
2.11
(0.016)

1.73
(0.020)
2.11
(0.012)

1.73
(0.020)
2.11
(0.014)

2.46

1.77


3.41

3.60


3.41

2.62
(a)
   MgO is included in other components in the limestone cases.

-------
                    TABLE 13.   ONE-STEP REGENERATION PROJECTIONS

So r bent
Rate
(Ca/S)
Sorbent
Fines Rate
(Ca/S)
Composition of Spent Sorbent, (Mole %)
CaSO^
cas
CaO
CaC03
MgO
(moles MgO
per mole Ca)
Other
Components
(g per mole
calcium)
Atmospheric
Pressure
• Limestone
Combustor
Regenerator
• Dolomite
Combustor
Regenerator
Pressurized
Boiler
• Limestone
Combustor
Regenerator
• Dolomite
Combustor
Regenerator
Adiabatic Combustor
• Limestone
Combustor
Regenerator
• Dolomite
Combustor
Regenerator


0.75
0.81

0.76
0.82



0.68
0.74

0.62
0.66


0.68
0.74

0.69
0.75


0.08
0.08

0.08
0.08



0.07
0.07

0.06
0.07


0.07
0.07

0.07
0.08


24
12.8

21.5
10.4



35
21.5

49
34.1


35
21.5

32.5
19.2


0
1.2

0
1.1



0
3.5

0
4.9


0
3.5

0
3.3


76
86

78.5
88.5



65
75

51
61


65
75

67.5
77.5


0 0
0

0 1.19
0



0 0
0

0 1.19
0


n o
0

0 1.19
0


1.73


2.11




1.73


2.11



1.73


2.11

(a) 5% of the CaSO^ converted to CaS  in atmospheric-pressure case, 107 conversion  to CaS in
   pressurized case.

-------
                                   TABLE  14.   TWO-STEP  REGENERATION  PROJECTIONS



Sorbent
Rate
(Ca/S)

Sorbent
Fines Rate
(Ca/S)
Composition of Spent Sorbent (Mole %)

CaS04(a)

CaS(b)

CaO

CaC03(c)

MgO
(moles MgO
per mole Ca)
Other
Components
(g per mole
calcium)
       Pressurized
         Boiler
         Limestone
.0
OJ
Combustor
Regenerator
• Dolomite
Combustor
Regenerator
Adiabatic
Combustor
• Limestone
Combustor
Regenerator
• Dolomite
Combustor
Regenerator
0.66
0.71

0.53
0.56



0.66
0.71

0.62
0.67
0.07
0.07

0.05
0.06



0.07
0.07

0.06
0.07
18.7
0

73
0



18.7
0

48
0
20.3
29

0
63



20.3
29

0
38
6.1
46.7

27
25.9



61
46.7

52
43.4
0 0
21.3

0 1.19
11.1



0 0
21.3

0 1.19
18.6
1.73


2.11




1.73


2.11

        (a) 30% of  limestone-based-sorbent CaS resulfated  in combustor; 100% of dolomite-based sorbent
           resulfated  in  combustor
        (b) 100% conversion  of CaSO^  to CaS in first  step
        (c) 100% calcination in  combustor; 30% conversion  of CaO to CaC03 in second step.

-------
                            TABLE 15.  TURNDOWN SPENT SORBENT PROJECTS

Sorbent
Rate
(Ca/S)
Composition of Spent Sorbent on a Molar-Calcium Basis
Mole % (Total Weight Fractions in Parentheses)
CaSO,
CaS
CaO
CaC03
MgO
(moles MgO
per mole Ca)
Other
Components
(g per mole
calcium)
Pressurized
Boiler
Dolomite
(1337)


1.45 60
(0.476)


0
(0)


0
(0)


40
(0.234)


1.19
(0.278)


2.11
(0.012)

Assumptions:

•   All processes operated once-through during turndown.

•   Dolomite-based processes operate at about 750°C during turndown for pressurized operation.

•   Limestone-based processes operate at turndown such that calcining conditions always occur
    in the combustor.

•   All other cases (other than the pressurized boiler with dolomite) result in compositions
    identical to those in Table 12 (i.e., the calcium-to-sulfur ratio is fixed during
    turndown and the sorbent performance is not affected by turndown conditions).

-------
                                                                            Curve 6958.17- /'
                           Type Screen No.
400  200    100  60 40    20
      10
Ul

              CD

              .£i
              CO

              o>
.1
1
5
15
25
35
45
55
65
75
85
93
96
98
99
1 1 1





-
-
-
-
-
x
X
_x
1 1 1 1
' '/
5/
X

S
f



j/
X/
"XX
X S

1 1 1
1 1 1 1


X
X



.^
>
X
s


i 1 1 1
i i |, |
X
^_y


/
/
sXx
xXx
r^X
X



i i i
^"


s
X
x
X
X
1 1 ' I1 M,
/.
XX
' X X
X /
' X
/

^MII
r^
X





1
X



-


X
Curves 1. 2. & 3 Represent Projected-
Particle Size Distribution
Leaving Fluid-Bed Boiler
System
Curve 4 Represents Projected
Particle Size Distribution -
Leaving Primary Collectors -
Curve 5 Represents Projected ~
Particle Size Distribution
Leaving Secondary Collectors"
1 1 1 1 i i i 1 i 1 1 il
.5
3
10
20
30
40
50
60
70
80
90
95
97
98.5
                                          10                ipo
                                              Particle Size-Microns
1000
                         Figure  10.   Particle Size Distribution  for Different Gas Streams

-------
                                SECTION 5
                              LAND DISPOSAL

REGULATIONS/CRITERIA
     The legislative developments and criteria governing spent sorbent
disposal have been reviewed.   The important laws,  regulations and cri-
teria are summarized in this  section.
     With the enactment of the National Environmental Policy Act of
1969 (NEPA), all of us are charged with a "responsibility to contribute
to the preservation and enhancement of the environment."  Since the dis-
posal of the solid wastes from the fluidized-bed combustion process must
satisfy the provisions of environmental regulations,  the federal legisla-
                                                                ( 8)
tive developments governing liquid discharges from power plants,    dis-
posal of dredged and fill materials,  *    water discharges from all
sources,   *    and landfill  practices   '    have been reviewed.
These include three of the most important environmental laws:  The Clean
Air Act Amendments of 1970; the Federal Water Pollution Control Act
                          (14)
(Public Law 92-500, 1972);v    and the Resource Conservation and Recovery
Act (The Solid Waste Disposal Act of 1965, Public Law 89-272, 1965, as
amended by Public Law 91-512, 1970 and by Public Law 94-580, 1976).
     Although environmental standards for solid residue disposal from
coal-fired boilers (including the fluidized-bed systems) have not yet
been promulgated, the Resource Conservation and Recovery Act (RCRA)
requires EPA to set criteria  by April 1978 for identifying whether a
solid waste is considered "hazardous," and to establish standards cover-
ing generation, handling, treatment, and disposal of such wastes.  If
the residue were not "hazardous" — and there is no indication that the
FBC residue would be at this  time — it would be subject to any
                                    46

-------
restrictions developed by the individual states under their respective
management plans within the guidelines established by EPA as required
by the RCRA.
     In anticipation of forthcoming criteria for solid waste disposal and
the quality of its leachate, the chemical characteristics of leachates
from leaching experiments are compared with the drinking water standards
given by the EPA National Interim Primary Drinking Water Regulations
(NIPDWR)/    The United States Public Health Service (USPHS)(17) Drink-
ing Water Standards, and the World Health Organization (WHO) Potable
                C\Q\
Water Standards.      This is, of course, extremely conservative; a
leachate dilution/attenuation factor of 10 is currently being considered
in the regulation draft under Section 3001 of the RCRA of 1976 by the
Hazardous Waste Management Division of the Office of Solid Waste, EPA.
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.
Although the guidelines for the power plant effluents are not applicable
to the disposal of dry spent sorbent from the fluidized-bed combustion
process, they are used as additional references in this investigation.
     Because of the wide variations in the characteristics of solid wastes,
in general, weather, soils, topography, groundwater from site to site,
and nearby stream quality and flow characteristics, permits are currently
being awarded on a site-specific basis.  Eventually, as a result of RCRA,
state regulations will apply, but these regulations will not be enacted
until federal standards are enacted.  Depending on the actual site
selected for the spent sorbent disposal, the leachates would have to meet
                                                      (19)
the water quality criteria for the specific water use.  '    The success
of a land disposal application depends, furthermore, above all, on the
design, construction, and operation for a specific disposal site based on
the geology, hydrology, and climate of that particular site.

-------
Related Literature on Disposal
     The solid waste research program, under the leadership of EPA, ini-
tially concentrated on programs associated with municipal solid wastes,
but recently has included studies on hazardous and industrial wastes in
anticipation of new regulations and standards for hazardous and non-
                            (20 21)
hazardous industrial wastes.   '     Ahundant literature is available
                                                                   (20-25)
on sanitary landfill and pollutant migration from municipal wastes.
Recent work includes studies on land disposal of solid wastes from flue
gas cleaning systems with emphasis on flue gas desulfurization
 .  .    (20,26-29)
sludges.   '
     Literature on disposition of spent sorbent from fluidized-hed coal
combustion is limited but includes BCURA^    and PER,     who conducted
bench-scale leaching on small numbers of sorbents x
-------
                                  TABLE  16.  SELECTED WATER QUALITY CRITERIA
Substance
Maximum Concentrations (npj £)
National Interim
Primary Drinking
Hater Regulations'-^)
PHS Regulations
on Drinking
Water(15)
World Health
Organization Potable
Water Standards^"'
Proposed
Guidelines
for Power
Plant
Effluent^
VO
    pH (pH unit)
Total dissolved  solids
          AR
          As
          Ba
          Ca
          Cd

          Cr

          Cu
          Fe
                         Mn
                         Ni
                         Pb
                         Se
                         Sn
                         SO^
                         7n
                                                                                 7 - 8.5
6.0 - 9.0

0.05
0.05
1.0

0.01

0.05


0.002



0.05
0.01



500
0.05
0.05
1.0

0.01
1.0(Cr+3)
0.05(Cr+6)
1.0
0.3


0.05
2.0
0.05
0.01
1.0
250
5.0
500

0.2

75


0.05
1.0
0.3

50
0.1

0.1
0.05

200
5.0







0.2
1.0
1.0








1.0

-------
EXPERIMENTAL TESTING PROGRAM
     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 concentrations,
trace element dissolution, and total dissolved solids.  Disposal of the
solid wastes from the fluidized-bed coal combustion process may also
create air pollution, odor nuisance, and heat-release problems.  To assess
the environmental impact of solid waste disposal and the suitability of
waste material as landfill, leaching and activity tests were performed on
actual spent sorbents and fly ash obtained from the fluidized-bed combus-
                                             (32)
tors operated by Argonne National Laboratory,     Exxon Research and
                                                            (31)
Engineering CCompany,     and Pope, Evans and Robbins (PER),     all of
whom are conducting studies on the fluidized-bed coal combustion process
under contracts to EPA or DOE.  The spent sorbents available for this
study include spent bed material and fly ash from both the pressurized
and atmospheric-pressure boilers operated with a once-through or regenera-
tive sorbent system.
Samples
     Batches of actual spent sorbent and fly ash from pilot-scale fluid-
ized-bed combustors tested for their environmental impact on disposal
are listed below:
     •  Argonne spent sorbent from run C2/C3 — from Argonne fs 15-cm
                                                 (32)
        pressurized fluidized-bed combustion unit
     •  Argonne once- through spent sorbent from run VAR-4
     •  Argonne once-through spent sorbent from run LST-1
     •  Argonne once-through spent sorbent from run LST-2
     •  Argonne once- thro ugh spent sorbent from run LST-3
     •  Argonne once-through spent sorbent from run LST-4
     •  Argonne regenerative spent sorbent from run REC-3 — third com-
        bustion experiment in 10-cycle combustion/regeneration series
        of experiments
                                    50

-------
     •  Argonne regenerative spent sorbent from run CCS-10 — tenth
        regeneration experiment in 10-cycle combustion/regeneration
        series of experiments
     •  Exxon spent sorbent from run 8.4 — from Exxon's 32-cm pressurized
        fluidized-bed combustion unit, i.e., Exxon miniplant in Linden,
        New Jersey^38^
     •  Exxon spent sorbent from run27
     •  Exxon fly ash from run 27
     •  Exxon spent sorbent from run 19.6
     •  Exxon fly ash from run 19.6
     •  Exxon spent sorbent from run 30.2
     •  Exxon fly ash from run 26
     •  Exxon fines from run 34
     •  PER sorbent — from Pope, Evans and Robbins's atmospheric-pressure
        fluidized-bed combustor of 0.46 x 1.83 m size
     •  Gypsum — ground Iowa gypsum 114 was used to represent a refer-
        ence for natural CaSO,  leachability.
     Processed compacts of Exxon No. 27 spent sorbent/fly ash mixture
by room-temperature blending (see Section 7 for Compact Preparation)
include the following:
     •  I1C and I1D — 35.8 wt % fly ash, 7 day air cure
     •  I2C and I2D — 35.8 wt % fly ash, 11 day air cure
     •  I3C and I3D — 35.8 wt % fly ash, 28 day air cure
     •  II1C and HID — 10 wt % fly ash, 7 day air cure
     •  II4C and II4D — 10 wt % fly ash, 52 day air cure.
     Table 17 summarizes the process conditions under which these sor-
bents are generated.  For the purpose of clarification, the term "spent
sorbent" refers to the bed material, "fly ash" to the carry-over material
collected in the primary particulate control device (cvclones), and
"fines" represents the very fine particulates that have passed the
cyclones and are collected on an additional filter or flue gas sampling
device.
                                    51

-------
       TABLE  17.   PROCESS  CONDITIONS OF SAMPLES  STUDIED  FOR
                THEIR ENVIRONMENTAL  IMPACT  ON  DISPOSAL
^"~~ — ,-^_^ Samples Argonne Argcnne Argonne Argom
Conditions^-— ^.^^ C2/C3 VAR-4 REC-3 CCS-
le Argonne Argonne Argonne Argonne
-10 LST-1 LST-2 LST-3 LST-4
Coal Arkwright Arkwright Arkwright Triangle Arkwright Arkwright Arkwright Arkwright
Sorbent Tymochtee Tymochtee Tymoehtee Tymochtee Limestone Dolomite Dolomite Limestone
dolomite dolomite dolomite dolomite 2203 1337 1351 1336
Run Length 23 11 80.6 2.6 34.7 25.5 18.4 17.5
(hr)
Pressure 810 810 810 152 810 810 810 810
(kPa)
Avg Bed Temp 900-955 900 900 1100 870 870 870 870
(°C)
Lower Bed Temp — — — — — — — —
(°C)
Gas Velocity 1.61-1.67 0.7 0.7 1.24 0.76 (1.76 0.76 0.76
Ms)
Expanded Bed Height — 0.91 0.91 0.46 0.91 0.91 0.91 0.91
(m)
Settled Bed Height — — — • — — — — —
(m)
Coal Feed Rate — 7.9 13.5
(kg/hr)
Sorbent Feed Rate — 2.6 2.9
(kg/hr)
Ca/S Molor Ratio 1.1-1.5 1.9 1.5
12.1 11.7 11.7 11.6
1.7 3.6 3.1 1.5
1.5 1.8 1.4 1.4
Excess Air — 17 17 Reducing 17 17 17 17
SO Emission (ppm) 80-375 122 450 67,000 900 160 270 990
NO (ppm) 135 185 120
CO (ppm) — 50 64
C02 (%) — 18 16
02 (%) 3.0 3.0 3.2
150 135 185 95
74 50 30 55
16 15 16 17
3-5 3.1 2.9 3.0
S Retention (%) 82-96 95 79 -.65;: 63 93 Kg 5e
Regeneration
Ib SO-/MBtu — 0.23 O.B5
Ib NO /MBtu — 0.25 0.16
1-5 0.2R 0.47 1.7
0.1R 0.17 0.23 0.12
(a)
(b)
Third combustion experiment in ten-cycle combustion/regeneration series of experiments
Tenth regeneration experiment in ten-cycle combustion/regeneration series of experiments
                                         52

-------
TABLE 17.  (Cont'd)
•— ~^_^Samples Exxon Exxon Exxon
Conditions 	 -~~_^ 8.4 27 19. 6
Coal Arkwright Champion Champion
Exxon Exxon Exxon
30.2 26 34 PER
Champion Champion Champion Sewicklev
Sorbent Grove limestone Pfizer Grove limestone Grove limestone Grove limestone Pfizer Grove
1359 dolomite 1337 1359 1359 1350 dolomite 1337 limestone
Run Length 11 240 7.5
(hr)
Pressure 906-907 930 930
(kPa)
Avg Bed Temp — 829-930 880-P88
(°C)
Lower Bed Temp 877-908 840-960 —
(°C)
Gas Velocity 1.77-1.83 1.7-2.2 2.01-:.oi
(m/s)
8.5 15.5 13.25
920 930 932 101.3
929 885-927 900 816°C
945 949 868
2.5 1.9-2.1 1.5 2.7-4.6
Expanded Bed Height — 3-7
(m)
Settled Bed Height 0.66-1.19 — 1.55
(m>
Coal Feed Rate 75-112 112-149 113-1-3
(kg/hr)
Sorbent Feed Rate 10.3-15.2
(kg/hr)
Ca/S Molar Ratio 1.67 0-2.5 2.5
Excess Air 18-72 8-23 15
S02Emission (pmm) — 20-1290 5nn
NO (ppn) 50-200 70-210 10i
CO (ppm) — 30-110
C02 <*) — 1.1-17 11. 7-12. 3
02 (%) — 1.5-3.9 2.5-3."
S Retention (%) 62 41-100 6'
Ib S02/MBtu 1.8 0.03-2.5 1.0
Ib SOj/MBtu — 0.12-0.30 0.14
1.12-2.28 2.29 0.3-0.9
137 130 90 272-363
0-182
3.7 3.7 0.75
17.2 9.5-11.5 20.9
137 140-300 100-300
180-185 52
45 50 61
15.1 13 15.5
3.1 l.B-2.15 3.5 3
80 81-»1
0.29-0.59
0.25-0.28
 Spent Sorbent Characterization
      Chemical and physical characterization of the spent sorbents and
 fly ash was carried out.  Methods employed include optical microscopy,
 scanning electron microscopy, energy dispersive analyses by X-ray, elec-
 tron microprobe analysis, X-ray diffraction, emission and atomic absorp-
 tion spectroscopy, and wet chemical methods.  Tables 18 and 19 summarize
 the chemical composition of the spent sorbent and fly ash as determined
 by wet chemical methods.  These are in agreement with the chemical
 species identified by X-ray diffraction that are listed in Table 20.
                                     53

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TABLE 18.  CHEMICAL COMPOSITIONS OF SPENT BED MATERIALS AND
     FLY ASH FROM FLUIDIZED-BED COAL COMBUSTION UNITS
Sample
Argonne C2/C3
Spent Sorbent
Argonne VAR 4
Spent Sorbent
Argonne REC-3
Spent Sorbent
Argonne LST-1
Spent Sorbent
Argonne LST-2
Spent Sorbent
Argonne LSI- 3
Spent Sorbent
Argonne LST-4
Spent Sorbent
Argonne CCS-10
Spent Sorbent
Exxon 8.4
Spent Sorbent
Exxon 27
Spent Sorbent
Exxon 30.2
Spent Sorbent
Exxon 19.6
Spent Sorbent
PER
Spent Sorbent
Exxon 27
Fly Ash
Exxon 19.6
Fly Ash
Exxon 26
Fly Ash
Exxon 34
Fines*
Process
Pressurized, once-through
Pressurized, once-through
Pressurized, regenerative
(3rd cycle combustor)
Pressurized, once-through
Pressurized, once-through
Pressurized, once-through
Pressurized, once-through
Pressurized, regenerative
(10th cycle regenerator)
Pressurized, once-through
Pressurized, once— through
Pressurized, once- through
Pressurized, once-through
Atmospheric, once-through
Pressurized, once- through
Pressurized, once- through
Pressurized, once-through
Pressurized, once-through
Sorbent
dolomite
dolomite
dolomite
limestone
dolomite
dolomite
limestone
dolomite
limestone
Dolomite/
limestone
Limestone
Limestone
Limestone
Dolomite/
limestone
Limestone
Limestone
Dolomite
Chemical Composition (w/o)
Ca Mg SC^
22.5 11.7 40.
20.6 12.0 27.
18.6 11.7 33.
31.7 1.25 26.
20.0 13.4 31.
21.8 9.1 29.
30.7 1.3 20.
24.5 16.1 9.
36.1 0.5 18.
21.8 6.6 24.
33.4 1.5 17.
40.0 0.5 10.
19.1 0.9 20.
7.9 4.6 14.
7.4 0.8 7.
11.8 1.9 in.
7.7 2.8 14.
s- co3=
0 <0.05 5.1
5 0.04 8.7
5 0.05 0.6
7 0.05
4 0.04
9 0.008 11.3
2 0.05 33.2
8 0.04 0.7 '
3 <0.05 34.8
8 0.002 13.9
3 0 30 . 0
0 0.001 44.0
1 0.04 0.6
fi 0
10
0 0.006
40
*Collected from flue gas sampling filter.
                             54

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         TABLE 19.   CHEMICAL COMPOSITIONS OF SPENT SORBENTS FROM
                      FLUIDIZED-BED COAT, COMBUSTION
Sample
Argonne C2/C3
Argonne VAR 4
Argonne REC-3
Argonne LST-1
Argonne LSI- 2
Argonne LSI- 3
Argonne LSI- 4
Argonne CCS-10
Exxon 8.4
Exxon 27
Exxon 30.2
Exxon 19,6
PER
Process
Pressurized, once-through
Pressurized, once-through
Pressurized, regenerative
(3rd cycle combustor material)
Pressurized, once-through
Pressurized, once-through
Pressurized, once- through
Pressurized, once- through
Pressurized, regenerative
(10th cycle regenerator)
Pressurized, once-through
Pressurized, once-through
Pressurized, once-through
Pressurized, once-through
Atmospheric, once-through
Sorbent
Dolomite
Dolomite
Dolomite
Limestone
Dolomite
Dolomite
Limestone
Dolomite
Limestone
Dolomite/
1 imes tone
Limestone
Limestone
Limestone
Molar Fraction (Ca based)
CaSO,
4
0.71
0.55
0.75
0.35
0.65
0.57
0.27
0.16
0.21
0.47
0.22
0.11
0.44
CaC03
0.15
0.28
0.02
0.65
0.35
0.35
0.72
0.02
0.64
0.42
0.60
0.73
0.02
CaO
0.14
0.17
0.23
0
0
0.08
0.01
0.82
0.15
0.1
n.iR
0.16
n.54
CaS
<0.003
<0.003
<0.003
<0.003
 CaSO^, and Fe^ but little unsulfated
CaCO  or CaO.  Exxon spent sorbent No. 27 was separated into dark and
light particles.  The light particles were found to contain sulfated and
unsulfated dolomite (CaCO^ CaSO^, and MgO), but the dark particles were
high in impurities consisting mostly of Fe.^ spinel, with some S
CaSO,, MgO, Fe203, and trace CaCOg, CaS, and Al^.
                                    55

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TABLE 20.  CHEMICAL COMPOSITION OF SPENT SORBENT AND
            FLY ASH BY X-RAY DIFFRACTION

Samples CaSO, CaCO CaO
Species Identified
Fe304
MgO SiO aFe-0, Spinel Others
Argonne C2/C3 Major High — Major
minor
Exxon 8.4 Major Major Major
Spent Sorhent
— — — CaS possible
Exxon 27 High Trace — Present High Minor Major CaS present
Spent Sorhent minor minor Al^O, present
(dark particles)
Exxon 27 Major Major — Major Trace
Spent Sorhent
(light particles)
Exxon 19.6 Major Major
Spent Sorbent
Exxon 30.2 Minor Major
Spent Sorbent
PER Major — Minor
Spent Sorbent
Exxon 27 Major
Fly Ash
Exxon 19.6 Major Trace
Fly Ash
Exxon 26 Major Minor
Fly Ash
Trace
Trace
Minor Trace — Ca SiO possible
Major Major
Major High
minor
Major High
minor
Exxon 34 Major — — Present Major High — Ca SiO possible
Fines minor

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     Table 21 compares the  compositions of the actual spent sorbents
with their projected values (Section 4).  The most significant differ-
ence exists in the  case of  the pressurized, once-through system where
the unsulfated sorbent exists as a mixture of CaCO  and CaO instead of
CaO alone, as projected.
     Spent sorbents from  the fluidized-bed combustion process are often
inhomogeneous.  Figure 11 shows photomicrographs of the spent sorbents
and fly ash from Exxon run  No. 27, showing variations in particle size,
color, shape, and texture.
     Trace metal element  distribution was investigated by scanning elec-
tron microscopy (SEM) in  conjunction with energy dispersive analysis by
X-ray  (EDAX) .  Figure 12  shows a typical SEM photomicrograph of a spent
sorbent (Exxon No.  27).   The EDAX spectra, which plot peak intensity
versus X-ray energy, are  shown on Figures 4(b) and (c) for two locations
on the spent sorbent particle as marked on Figure 12(a).  The presence
of calcium, silicon, aluminum, sulfur, iron, sodium, potassium, and
titanium is indicated.  A similar SEM photomicrograph and EDAX plots are
shown  for a fly ash sample  (Exxon 19.6) in Figure 13.  Much higher silicon
and aluminum and lower calcium peaks are observed for the fly ash sample.
     Electron microprobe  analysis provided the elemental profiles of
partially sulfated  limestone or dolomite particles when polished cross
sections were scanned.  One persistent phenomenon was that the partially
sulfated limestone  or dolomite always displayed a high concentration of
sulfur at the periphery of  the particle and that the sulfur extended into
the particle along  the grain boundaries or cracks.  Figure 14 shows photo-
micrographs of area scans for sulfur at two locations (edge and center)
on the cross section of a partially sulfated limestone particle illus-
trating this effect.  The sulfur concentration is proportional to the
intensity of the white dots on the area scan photos.  Another finding
revealed by the electron  microprobe was that the highly sulfated periphery
was not only rich in sulfur but also high in silicon, aluminum, and iron.
The high concentrations of  silicon, aluminum, and iron at the surface
                                    57

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                  TABLE 21.  COMPARISON OF CHEMICAL COMPOSITIONS OF ACTUAL  SPENT SORBENTS  FROM
                            FLUIDIZED-BED COMBUSTION UNITS WITH THE PROJECTED VALUES
oo
Process Conditions
Actual Spent Sorbent
(Molar Fraction Ca-Based)
CaSO,
CaO
CaCO
CaS
Projected Composition
(Molar Fraction Ca-Based)
CaS04
CaO
CaCO
CaS
        Atmospheric Pressure,*
        Limestone Sorbent,
        Once-through
0.44      0.54
0.02     <0.003     0.25   0.75
0      0
Pressurized,
Limestone Sorbent,
Once-through
Pressurized,
Dolomite Sorbent,
Once-through
Pressurized,
Dolomite Sorbent,
Regenerative
0.11-0.35 0-0.18 0.60-0.73 <0.003 0.40 0.60 0 0
0.47-0.71 0-0.23 0.15-0.42 <0.003 O.RO 0.20 0 0
0.16 0.82 0.02 <0.003 0.34 0.61 0 0.05

       *The only sample available is an unidentified PER sorbent  with unknown history and a typical sulfation
        level.

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                            (a)
Figure 11.  Microphotographs of Exxon Run No. 27 (a) Bed
            Stone  and (b)  Fly Ash.
                            59
                                                                     KM-67 07 7

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                                (a)
                                                                                energy,  KeV

                                                                                       (b)
Figure 12.   (a)  SEM Photomicrograph of Exxon 27 Spent Sorbent
             (b)  EDAX Spectrum of Spot 1 on SEM
             (c)  EDAX Spectrum of Spot 2 on SEM

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                            (a)
Figure 13.   (a)  SEM Photomicrograph of Exxon 19.6 Fly Ash
             (b)  EDAX Spectrum of Spot 1 on SEM
             (c)  EDAX Spectrum of Spot 2 on SEM
                                                                              energy, KeV

                                                                                    (c)

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                                                   particle
                                                   surface
                             (a)
(b)
                                                   particle
                                                   interior
                              (c)
(d)
Figure 14.    SEM and Electron Microprobe  Photomicrographs of a Spent Limestone Particle (Exxon  21}
              (a)(b)  SEM and Sulfur Scan on  a Cross-Sectional Area Near  the  Surface
              (c)(d)  SEM and Sulfur Scan on  a Cross-Sectional Area in the  Interior.

-------
were also observed  for particles that were totally sulfated.  TVA recently
reported that a 2 to 5pm  thick hematite deposition was found on the
                  (35)
sorbent particles.      Figures 15 and 16 show the photomicrographs of
electron microprobe analysis  for a partially and a completely sulfated
limestone particle.  The  surface coating is suspected to have significant
influence on the reaction mechanism and leaching behavior, but the implica-
tion is not yet fully understood.
     Trace metal ion concentrations on spent sorbent and fly ash were
determined by emission and atomic absorption spectroscopy.  Results are
summarized in a later section, together with trace elements found in their
leachates.
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.
Currently, EPA's Office of Solid Waste, Hazardous Waste Management Division
is developing a "standard" leach test method as part of its effort in the
development of national standards for hazardous waste definition to be
promulgated under RCRA Section 3001, planned for April, 1978.  Parallel to
the EPA effort, ASTM committee 19.12 (subcommittee 19.1203) is also develop-
ing standard leaching tests for solid waste in general.  A shake test is
proposed by both efforts.
     In this study  leachates  are induced by shake tests, except where
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 aerobic versus  anaerobic  leaching conditions, with the latter shake
under nitrogen atmosphere.  The supernatants resulting from this operation
were filtered, and  the filtrate was determined for pH, specific conductance,
calcium, magnesium, sulfide,  sulfate trace metal ion concentration, and
total organic carbon content.  The solid samples before and after the leach-
ing operation were  also analyzed for their chemical and physical
characteristics.

                                    63

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                                 particle
                                 surface
            (a)
                                                         (b)
                                  particle
                                  surface
             (c)
                                                          (d)
                                 particle
                                 surface
              (e)
                                                          (f)
Figure  15.   Area-Scan  Electron Microprobe Photomicrographs  on a Cross
             Section  of a Spent Limestone Particle (Exxon  19.6)  Near
             Its Surface, (a) SEM,  (b)  Ca, (c)  S,  (d) Si,  (e)  Al, and
             (f) Fe
                                    64
                                                                               RM- 68256

-------
                                 particle
                                 surface
               (a)
                                                          (b)
                                particle
                                surface
               (c)
                                             (d)
                (e)
                                 particle
                                 urface
                                                        (f)
Figure  16.
Area-Scan Electron Microprobe Photomicrographs on a  Cross
Section of a Completely Sulfated Spent Limestone Particle
(Exxon  19.6) Near Its  Surface, (a)  SEM, (b)  Ca, (c)  S,
(d) Si,  (e)  Al and (f)  Fe.
                                    65
                                                                              RM-68462

-------
     Two shake procedures have been employed.  These are described below.
     •  Continuous shake test.  It establishes equilibrium conditions
        between the solid and its aqueous surrounding and provides the
        worst possible case with respect to contamination release.  This
        method has been used by Westinghouse since 1975 as one of the
        screening tests for determining leaching properties of FBC spent
        solids.  Typically a 1:10 solid-to-water ratio is used.
     •  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 calcula-
        tion 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 are analyzed at the end of each interval
        and a fresh charge of deionized water is added for each 72-hour
        leach cycle.  Typically, a 1:3 solid-to-water ratio is used.
     Both shake tests are more severe than conditions anticipated under
actual land disposal; results from the shake tests are expected to pro-
ject the worst.
Spent Sorbent
     Leaching properties were investigated for 13 batches of  actual spent
bed materials (limestone and dolomite)  from a pilot-scale fluidized-bed
combustor and regenerator operated under atmospheric  and  elevated pres-
sures.  The operating conditions and chemical compositions of these
sorbents, which underwent standard shake tests,  are presented in
Tables 18 and 19.
     Since calcium sulfate is a major constituent of  the  waste stone
from the fluidized-bed combustion process and leachates contained high
calcium and sulfate concentrations,  a naturally occurring gypsum was
tested under similar leaching conditions for comparison.
                                    66

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     Figure 17 presents the chemical characteristics of leachates as a
function of continuous leaching time and compares them with gypsum leach-
ate.  It shows that leachates of the Exxon spent sorbents (all limestone
except Exxon No. 27, which was a mixture of limestone and Pfizer dolomite)
displayed similarly high calcium, sulfate, alkalinity, and total dissolved
solids, independent of operating conditions.  Leachates of Argonne's
once-through spent dolomite exhibited noticeably lower TDS and calcium,
approximately in the range of gypsum leachate.  Negligible magnesium ion
concentration was found in leachates of spent dolomite sorbent (<20 ppm).
It appears that dolomite sorbent, when generated under similar fluidized-
bed conditions, produces leachate of better quality.  Spent dolomite from
either the combustor or the regenerator of the regenerative mode, however,
produced leachate worse than the once-through spent dolomite sorbent.
Further testing employing the 15 x  72 hour intermittent shake method
indicated that the leachate quality of Exxon 19.6 spent limestone improved
much faster than did leachate from  Argonne C2/C3 spent dolomite, although
the initial leachate for the spent  dolomite was much better.
     Leachates or PER spent limestone from the atmospheric fluidized-
bed unit displayed similar chemical properties as did those of Exxon
spent limestones which were generated under elevated pressure.  Since
the PER sorbent was the only atmospheric sample tested and it was not
representative due to an unidentified origin, operating conditions, and
storage age, the leaching behavior  of spent sorbent generated under
atmospheric pressure should be investigated further.
     Specific conductance has been  shown to be a good index for leachate
quality, since it represents the total dissolved solids in the system.
Table 22, which compares the specific conductance of various sorbent
systems, shows clearly the results  observed in Figure 17 as described
above.
     Figure 18 shows leachate characteristics as a function of stone
loading.  Again, it shows that the  leachate from Argonne's spent dolomite
was of better quality than that of  Exxon's spent limestone.
                                    67

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                                            Curve 686360-3

t
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2000
1500

1000

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i i i i
-
~° C"^70 ^i - — \
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D

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i i i i i

2000
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1000

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6000
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"V ' ' i

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. D
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A-"^ li*


T
0 1 ii
100 200 300 400 50C
Mixing Time, Mrs.
D Exxon Run 27 * * 1ST -2 pp
• Exxon Run 30. 2^ » LST-3 of
y * Exxon Run 19.6^ o LST-4 *-f
              o Exxon Run 8.4 tf
              & Argonne Run C2/C3JJP
              ^ PER Atmospheric Runt/»
              « VAR-4  Pf
              « LSI -1  ^
 • REC-3  OR.P
— Natural Gypsum
Figure  17.   Leachate  Characteristics as a Function
             of Mixing Time of Spent Sorbents
                           68

-------
       TABLE 22.  COMPARISON OF SPECIFIC CONDUCTANCE OF LEACHATES
           FROM SPENT BED MATERIALS FROM VARYING FBC PROCESSES
Sample
Identification
Argonne C2/C3
Argonne VAR-4
Argonne LST-2
Argonne LST-3
Argonne REC-3
Argonne CCS-10
Argonne LST-1
Argonne LST-4
Exxon 8.4
Exxon 30.2
Exxon 19.6
PER
Process Variation
Dolomite, once-through, pressurized system
Dolomite, once-through, pressurized system
Dolomite, once-through, pressurized system
Dolomite, once-through, pressurized system
Dolomite, regenerative, pressurized system
Dolomite, regenerative, pressurized system
Limestone, once-through, pressurized system
Limestone, once-through, pressurized system
Limestone, once-through, pressurized system
Limestone, once-through, pressurized system
Limestone, once-through, pressurized system
Limestone, once-through, atmospheric system
Specific
Conductance
(p -mhos /cm)
3980
3510
3310
3140
8710
9540
8540
8570
7760
8000-8500
8000-8500
8590

     In addition to the shake test, a small column leaching experiment
was conducted on Argonnefs spent dolomite and gypsum at a constant run-off
rate.  Solid residues were manually packed into the columns of 11 mm dia.
to 213 mm depth.  Successful 250 ml leachates were collected at a flow
rate of 5 ml/min.  Results plotted in Figure 19 showed equilihrated cal-
cium and sulfate concentrations but a gradual decrease in total dissolved
solids and leachate alkalinity.  It showed that the leachate character-
istics of Argonne's spent dolomite were comparable to or better than the
gypsum leachate except for Argonne's higher pH.
     Sulfide was not found in spent bed sorbent or its leachate for the
once-through system.  Some sulfide O25 ppm) was found in the anaerobic
leachate from the regenerated sorbent.  This may not be a problem because
                                    69

-------
                                       Curve 684735-A
               I	1	1	1	1	1	1	1
  o>
o
c:
-£S
o
1
o
CD
   S
   <_>
1500
1000
 500
   0
  13
  11
   9
   7
   5
8000
6000
4000
2000
   0
               D—D-
                                                   -O-
               5   10   15   20   25   30  35   40  45  50
                 Stone Loading (gm in 250 ml HJD)
             o	  Exxon Spent Stone Run 8 4
             a	Argonne Spent Stone C2/C3
             °	Iowa Ground Gypsum 114
    Figure  18.  Leachate Characteristics as  a Function
               of Stone Loading
                            70

-------
                                         Curve 686%9-A
•g
"c ^5
o en
c E
o —^
o
TO
O
           1500
           1000
           500
              0
                Gypsum
                        i    i    i
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-  2000
|  1500
-H  1000
CD
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PH
    CD
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              0
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                      Gypsum
                      Gypsum
                        i   i    i    i   i    i
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.a b
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3000


2000

1000
n
_ Gypsum

^ _^ 	 ^
"" CP ° v 	 Q — o — o- — o 	 o

™ ~
II 	
Figure  19.
       u 0   1   2  3   4   5   6  7
           Numbers of 250 ml Samples
    Leachate Characteristics of the Argonne Spent Stone
    C2/C3 Leachates Induced by the Column Tests
                             71

-------
of the apparent ease of air oxidation of sulfide under aerobic conditions.
Since only limited quantities of regenerative sorbent were available for
testing at this time, further investigation should be conducted in the future.
Flv Ash and Fines
     Leaching tests were conducted on four batches of fly ash and fines
from the Exxon miniplant.  Results presented in Figure 20 showed that
the leachates of fly ash and fines displayed lower pH, calcium, and TDS
than did those found in the leachates of spent limestone bed materials.
This could be attributed to the greater amount of insoluble silica
present in fly ash and the relatively small amounts of free lime that
might be either partially dead-burned or covered with impermeable CaSO,
because of its smaller particle size or might form insoluble pozzolanic
reaction products (e.g., aluminosilicates)  during the aqueous leaching
process.  The fines (Exxon No. 34) collected from the flue gas sampling
system produced leachates of quality similar to those of the fly ash
collected from the cyclone.  In general, leachates of fly ash and fines
displayed chemical characteristics (Ca, S0~  and TDS) similar to those
of the gypsum leachates except for the higher pH of fly ash.  No sulfide
was present in the leachates.
Spent Sorbent/Fly Ash Mixtures
     Since both the spent sorbent, which is generated in the bed,  and the
fly ash, which is collected in the particulate collection device,  are pro-
duced from the fluidized-bed combustion process, it is likely that they
will be disposed of together.  Mixtures of various ratios (80/20,  70/30,
50/50, 30/70, 20/80) of the spent sorbent and fly ash from Exxon runs 27
and 19.6 were tested for their combined leaching properties.  Results
shown in Figure 21 indicated that the leachates of spent sorbent/fly ash
mixtures displayed lower total dissolved solids, pH, and calciun concen-
tration than did the leachates of the spent sorbent alone.  An addition
of >20 x
-------
                                               Curve  686361-B
—
E
E
03
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,w«i-. Dun 10 A Matnral Huncnm
          o Exxon Run 26
Figure  20.  Leachate Characteristics as a Function of Mixing
            Time of Fly Ash
                               73

-------
                                        Curve 686359-B
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=3
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1

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00
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2000
1500
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500
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2000
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1000
500
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12 {
10
8
6
10000
8000.
6000
4000
2000
R
I !
^** -^.CL r, * r-, *
1 1

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1 1 1 1

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1 1 1 1
H\ X) 4n An sn im
Figure 21.
                D  Exxon Run 27
                A  Exxon Run 19.6
            	  Natural Gypsum

Leachate Characteristics of Bed Material/Fly
Ash Mixtures
                             7A

-------
Processed Spent Sorbent/Fly Ash Compacts
     Leaching property was investigated for  the processed cubes prepared
by room temperature compacting of  sorbent/ash blends,  (see identification
of the blends on p. 52).  Among the parameters investigated are the
sorbent/ash mixing ratio and the air  curing  time.  These cubes, prepared
in duplicate, were leached by two  procedures.  One of  the cubes was
leached by the continuous shake for 1000 hr.  The other underwent the
15 x 72 hr intermittent shake cycles.  Figure 22 compares the leaching
rates of four processed sorbent/ash compacts with different mixtures and
air curing time.  Several preliminary observations can be made from the
up-to-date data presented in Figure 22.
     (1)  The leachate quality improves with time.  The amounts of solid
leached (e.g., TDS, Ca, SO.) decrease significantly with the total
number of 72-hour consecutive leach periods.  The decreasing leach rate
with time is most likely attributable to the formation of the practically
insoluble CaCO, on the sample surface and within the pores, which would
retard the solid dissolution.  Indeed, a white CaCO, scale was observed
on the surface of these cubes and  on the container wall after leaching.
     (2)  The leachate pH also decreases gradually with time.  This is
also attributed to the neutralization effect of CO- from the air.
     (3)  Leachates from cubes made from mix II (10 wt % fly ash) had a
lower initial SO, concentration and a higher initial pH than did those
of mix I (36 wt % fly ash) cubes,  but they fell within the same range
after approximately 400 hours of leaching.  It should be pointed out that
the compacts made from 10 wt % fly ash also had higher compressive strength.
     (4)  The leaching properties  were relatively independent of the air
curing time of the compacts within the experimental range.
     Table 23 compares the chemical characteristics of leachates from the
unprocessed Exxon run 27 spent bed material, fly ash, and their mixtures
with those of the processed Exxon  run 27 sorbent/ash blends.  Note that
                                    75

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                                                     Curve 687523-B
         800
         600
         400
         200
                    180
                       t = Total Leach Time =(72) (n) Hour
                       360      540      720      900
                                                             1080
                                o  I ID Mix I, 7 Day Curing
                                o II ID Mix II, 7 Day Curing
                                °  I2D Mix I, 11 Day Curing
                                A H4D Mix II, 52 Day Curing
        1600
        1400
        1200
    ^
    I1  1000
    sT  80°
         600
         400
         200
           0
          12
          11
          10
          9
          8
          7
     E
     u
     o
        3000
g   2000
|
1   1000
    1
                                     -fi  § -n.
                                         O   A
                                         I
                            5               10
                        n =Total Number of 72 Hr Consecutive Leach
                                                         15
Figure  22.  Chemical Characteristics from Consecutive Leachates
              for Processed Exxon No.  27  Spent  Sorhent/Fly Ash
              Compacts
                                     76

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TABLE 23.  LEACHATE CHARACTERISTICS OF PROCESSED AND UNPROCESSED
           SPENT SORBENT AND FLY ASH FROM EXXON RUN 27
Sample

Leaching Condition
Leachate Characteristics
PH
Specific
Conductance
( y-mhos-cm"-'-)
Ca
(Mg/O
so4
(Mg/£)
Unprocessed

Exxon
Exxon
27 spent sorb en t
27 fly ash
Exxon 27 sorbent/ash
mixture (80:20)
Processed
Compacts








I1C:
I1D:
I2C:
I2D:
12D:
II1C:
HID:
H4C:
II4D:
36 wt % fly ash,
7 day cure
36 wt % fly ash,
7 day cure
36 wt % fly ash,
11 day cure
36 w/o fly ash,
11 day cure
36 wt % fly ash,
11 day cure
10 wt % fly ash,
7 day cure
10 wt % fly ash,
7 day cure
10 wt % fly ash,
52 day cure
10 wt % fly ash,
52 day cure
10
10
10
g/100 ml/100
g/100 ml/100
g/100 ml/197
hr Cont.
hr Cont.
hr Cont.
174 g/1740 ml/1224 hr
Cont.
182
1st
181
180
180
220
220
216
220
g/546 ml/72
72 hr cycle
hr
.5 g/1815 ml/1080 hr
g/540 ml/72
g/540 ml/72
hr
hr
g/2200 ml/1224 hr
g/660 ml/72
hr
.5 g/2165 ml/1080 hr
g/660 ml/72
hr
12
9
9
8
10
7
10
10
8
11
8
11
.4
.5
.5
.5
.3
.7
.2
.2
.4
.5
.3
.4
6320
2490
2570
2550
2580
2570
2430
2430
2230
2740
2370
2590
1128
684
760
576
572
552
552
552
560
640
544
600
1512
1711
1783
1692
1600
1410
1493
1493
1366
983
1548
1083

-------
the processed sorbent/ash compacts generated leachates of quality superior
to the unprocessed spent sorbent alone.  This improved leaching property
was also observed in leachates from mixtures of unprocessed sorbent and
ash mixtures, as reported in the previous section.
     Specific conductance is a measurement of total dissolved solids in
a solution and serves as a good index for leachate quality.  Figure 23
shows a log-log plot of specific conductance versus total leach time
and total leachate volume passing through the solid for the sorbent/ash
compact, compact crushed to powder, unprocessed sorbent/ash mixtures, and
gypsum; and shows a straight line relation.  The data in Figure 23 can be
extrapolated to long-term leachability to indicate that gypsum leached
constantly, independently of the total leach time and the volume of leach-
ate passing the sample.  On the other hand, the leachates from the sorbent/
ash compact, the crushed compact powder, and the unprocessed sorbent/ash
mixture displayed improvement with time and total volume and, therefore,
are much less contaminating than are the natural gypsum from their long-
term leachability.  Finally, these results clearly demonstrate that the
sorbent/ash compacting process improves the leaching property and reduces
the potential environmental impact through leachate contamination.

Trace Metal Elements
     Leachability of trace metal elements was determined by emission
and atomic absorption methods.  Table 24 summarizes the heavy metal
concentrations in the spent sorbent and fly ash from the fluidized-bed
coal combustion process and their leachates based on data from all the
available residues.  The National Primary Drinking Water Standards
and Public Health Service Regulations     and World Health Organiza-
    (18)
tion    as well as the EPA guidelines and standards for power plant
        ( 8)
effluent    are listed for comparison.  It should be noted that the
leachability of the trace metal ions was so low for all the spent sorbent
                                     78

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                                                                                          Curve 689564-A
VO
                   o
                   I
10.0
 8.0
 6.0

 4.0


 2.0
8  1-0
S  0.8
o
I  0.6
o
o
•^  0.4
                   o
                   o>
                       0.2
                                       Normalized Leachate Quantity,  mi per g of Starting Solid
                                                   3         6   9   12   18    30    45
                                         r
                                         D
I    I
                                                                               T
                  Gypsum
                  Unprxessed Sorbent/Ash Mixture
                  I 4C1 Crushed Powder
                  I 4D1 Original Compact
                                                                              I	I
                                   20      40   60  80  100
                                                        Total Leach Time, hr
                                                             1000
                                                                                4000
             Figure 23.  Comparison Specific Conductance  of Leachate  from Sorbent Compact, Crushed
                          Compact, Unprocessed Mixture,  and Cypsum

-------
TABLE 24.   TRACE METAL ION  CONCENTRATIONS  IN SPENT SORBENTS  AND  FLY ASH
          FROM THE FLUIDIZED  BED COMBUSTION  PROCESS AND  LEACHATES
Substance
Ae
Al
As
B
Ba
Be
Bi
Ca
Cd
Co
Cr
Cu
Ge
Fe
Hg
K
Li
Me
Mn
Mo
Na
Xi
Pb
Sb
Se
Si
Sn
Ti
V
Zn
Zr
Solid wt "
Bed Material fly Ash
'O.ooi 10
'0.03 '0.05
'0.03 o.ni to n.i
'0.02
'0.0005 '0.003
'0.01 <0.01
>10 >1
'0.006 '0.03
'0.01 '0.01
'0.02 '0.1
'0.02 '0.02
'0.01
2 to 5 0 to >in
ND -0.02
0.2
'0.01
o to >in 'O.i
'0.05 '0.05
0.1 '0.01
-0.01
'O.oi 'O.i
'0.01 '0.05
'0.01 '0.05
>:D** NT>
o.i to >in >io
'0.005 '0.01
0.01 to '\ 0.1 to '10
'0.05 '0.05
'0.03 <0.1
'0.02 '0.1
Leachates (mg/1)
Bed Material Fly Ash
'0.01 '0.01
'0.1 '1.0
'0.05 '0.05
<0 '6.0
—
<0.02 <0.02
<0.04 '0.04
>500 >500
'0.04 <0.04
'0.1 <0.1
<0.04 '0.04
<0.04 '0.1
'0.1 '0.1
'0.04 <0.04
'0.001 '0.001
'0.5
'0.2
'30 0 to '300*
'0.04 '0.04
<0.1 '1.0
>10
'0.04 '0.1
<0.04 <0.4
'0.08 '0.08
'0.005 <0.005
'2.0 0 to 30
'0.04 '0.04
'0.04 '0.04
'0.1 '0.1
'0.4 <0.4
'0.05 <0.05
National Primarv
Drinking Water
Standards (mg/1)
0.05

0.05

1.0
1.0


0.01

0.05
1.0

0.3
0.002



0.05


2.0
0.5

0.01

1.0


5.0

Proposed Guidelines
for Power Plant
Effluent (mg/1)










0.2
1.0

1.0















1.0

 *High value resulted  from leachate of fines collected from the flue gas particulate collection
**ND - Not detected.
                                        80

-------
and fly ash that non,e  of  the  leachates  exceeded  the  drinking water stand-
ards.  Leachates from  the processed  sorbent/ash  compacts  displayed sim-
ilarly low trace element  concentrations.   Although the  levels  of detec-
tion were in some  cases limited  by the  analytical sensitivity  achieved
with the small quantity of samples available,  the leachability of trace
metal ions from the  spent sorbents and  fly ash from  the fluidized-bed
combustion process will probably not cause water pollution problems, at
least for those trace  metals  covered by some  form of drinking  water
standard.  This is easily understood since the leachates  from  a spent
limestone or dolomite  system  are highly alkaline and suppress  the heavy
metal dissolution, since  their solubility  in  an  alkaline  environment is
governed by their  practically insoluble hydroxides and  carbonates.
COD/BOD/TOC
     Determination of  chemical oxygen demand  (COD) provides a  measure
of  the oxygen  equivalent  of that portion of the  organic matter in a
sample that is susceptible to oxidation by a  strong  chemical oxidant.
The dichromate reflux  method  is  usually employed for the  COD determina-
tion because it has  advantages over  other  oxidants in oxidizability.
The biochemical oxygen demand (BOD)  determination is an empirical test
in  which standardized  laboratory procedures are  used to determine the
relative oxygen requirements  of  waste waters,  effluents,  and polluted
waters.  The test  is of limited  value in measuring the  actual  oxygen
demands of surface waters; and the extrapolation of  test  results to
actual situations  is highly questionable,  since  the  laboratory environ-
ment does not  reproduce actual conditions,  particularly as related to
temperature, sunlight, biological population,  water  movement,  and oxygen
concentration.  Since  both the COD and  BOD procedures are time-consuming,
total organic  carbon (TOC) determination is often adapted to provide a
speedy and convenient  way of  estimating the other two parameters that
                                            (45)
express the degree of  organic contamination.
     Total carbon  (TC) and TOC were  determined for leachates from
processed and unprocessed spent  limestone  and dolomite  and fly ash from
                                    81

-------
Argonne and Exxon pressurized fluidized-bed units, along with a control

leachate from a natural gypsum.  A model 915 Beckman TOC analyzer was

used.  Results summarized in Table 25 verified the assumption that the

organic content is extremely low or nonexistent.  The TC and TOC values

were near the limit of detectability for all the leachates and control

analyzed.

Activity Tests

     The activity of residual lime in spent sorbents and fly ash was

determined by its heat release property on contact with water, as the

hydration reaction of CaO is extremely exothermic.      This was done
        TABLE 25.  TOTAL INORGANIC AND ORGANIC CARBON IN LEACHATE
             FROM UNPROCESSED AND PROCESSED FBC SOLID WASTE
Sample
Exxon No. 19.6
Bed Material
Exxon No. 19.6
Fly Ash
Argonne C2/C3
Bed Material
Argonne LST-1
Bed Material
Argonne CCS- 10,
Regenerator Bed
Material
History
Limestone, pressurized once-
through, unprocessed
Limestone, pressurized once-
through, unprocessed
Dolomite, pressurized once-
through, unprocessed
Limestone, pressurized once-
through, unprocessed
Dolomite, pressurized
regenerative, unprocessed
Total Carbon
Inorganic
<7
<5
<5
<5
<5
(ppm)
Organic
<5
<14
<16
<5
<5
 Processed
 Compacts:
 I2C, I3C, I3D,
 I4C, II4C
Processed cubes by room-
temperature blending of
Exxon No. 27 spent
sorbent and fly ash
<5
<5
 Natural Gypsum
Control
                                  <7
                                              <8
                                   82

-------
calorimetrically.  In a  standard  test  3  g  of  stone were  added  to 20 ml
of deionized water in a  Dewar  flask which  had been thermally equilibrated.
Chromel-alumel thermocouples were used to  monitor the  temperature rise
in the stone/water system with an Omega  cold  junction  compensator and a
millivolt recorder.  The heat  release  tests were conducted on  the actual
spent sorbent and fly ash from the fluidized-bed combustion units.  Cal-
cined and uncalcined limestone and dolomite samples were also  tested for
comparison.  Table 26 summarizes  the maximum  temperature rise when 3 g
of a solid sample were added to 20 ml  of deionized water.  Results showed
that the available batches  of  spent sorbent and fly ash did not give off
heat spontaneously on contact  with water.  In cases where there was
residual calcium oxide present, it might have been hydrated in air during
storage, dead-burned during the process, or coated with impermeable
CaSO, so that no spontaneous heat of hydration was detected.  These
results seem to indicate that  no  heat-release problem  is to be expected
as a result of the solid waste disposal  from  the once-through pressurized
FBC process.  One must bear in mind, however, that the compositions of
the spent sorbent, and therefore  the heat-release properties, differ with
processing variations and operating conditions.  The potential heat-release
must be determined from  the atmospheric  spent sorbent, since the only
sample available in this category was  a  PER sample from an unknown stor-
age pile that had neither an identified  sample history nor a "typical"
sample composition.*
     The presently used  activity  test  procedure was established in our
laboratories as a screening test  to compare the residual lime activity
of spent sorbent from different processing conditions.  The solid/water
                                                               f / "7 \
ratio selected in the bulk  range  as specified by the ASTM C110<-    (76 g
in 380 ml water) and work by Murray et al.(48) (lime:water being 1:7) was
found empirically to provide much better repeatability than that from a
*Since the date  of  the  preliminary  issuance  of  this report, several addi-
 tional batches  of  FBC  residue  (AFBC  and  regenerative PFBC) have been
 made available  for testing.  The heat  release  property summarized in
 Table 27 reflects  the  up-to-date results.
                                     83

-------
             TABLE 26.  HEAT-RELEASE PROPERTY OF FBC WASTE
Sample, Solid/Waste (3g/20 ml)                              AT      °(
                                                              TtlaX 9
Argonne C2/C3 spent dolomite                                    <0.2
Argonne VAR-4 spent dolomite                                    <0.2
Argonne REC-3 spent dolomite (3rd cycle comibustor)              <0.2
Argonne CCS-10 spent dolomite (10th cycle regenerator)          <0.2
Argonne LST-1 spent limestone                                   <0.2
Argonne LST-2 spent dolomite                                    <0.2
Argonne LST-3 spent dolomite                                    <0.2
Argonne LST-4 spent limestone                                   <0.2
Exxon No. 8.4 spent limestone                                   <0.2
Exxon No. 27 spent dolomite/limestone                           <0.2
Exxon No. 27 fly ash                                            <0.2
Exxon No. 19.6 spent limestone                                  <0.2
Exxon No. 19.6 fly ash                                          <0.2
Exxon No. 30.2 spent limestone                                  <0.2
Exxon No. 26 fly ash                                            <0.2
Exxon No. 34 fines                                              <0.2
PER spent limestone (atmospheric)                               <0.2
Natural gypsum                                                  <0.2
Tymochtee dolomite, -16 +18 mesh                                <0.2
Limestone 1359, -18 +35 mesh                                    <0.2
Calcined limestone 1359, -18 +35 mesh                           >55
                                   84

-------
higher solid/water ratio  that would  give  greater  magnitude of tempera-
ture rise but lack reproducibility,  most  likely because of local heat-
ing.  The former procedure has been  adopted  because  it is fast, it
requires only a small quantity of  stone,  and its  results reproduce
well.  The latter procedure  (small quantity  of water added to larger
quantity of solid) is also planned,  however,  because it provides higher
sensitivity and simulates rainfall onto the  disposed solid.
CONCLUSIONS AND ASSESSMENT
     Results from laboratory testing indicate that the spent sorbent and
fly ash from the fluidized-bed combustion process can be disposed of
directly as landfill.  The design  and construction of the landfill site
should minimize leachate  generation  so that  potential water contamination
from calcium and sulfate  ion dissolution  and leachate alkalinity can be
prevented.
     Data from the laboratory-scale  investigation of direct disposal of
the FBC residues indicated that:
     •  Trace metal ions  are not likely to be water-contaminating.
     •  The dissolved organic concentration  is low and near the limit of
        detectability.
     •  Magnesium is not  soluble,  even from  the spent dolomite sorbent.
     •  Sulfide will probably not  be a problem for the once-through FBC
        system.
     •  Heat-release on contacting water  decreases with the following
        order:  AFBC bed  -* AFBC ash  -> PFBC bed, regenerative -> PFBC
        bed, once-through •>  PFBC ash.  Heat-release property from the
        AFBC residues may be an environmental concern which nay be pre-
        vented by careful selection  and design of the disposal site.
     •  Potential environmental concerns  are:  heat-release, leachate
        alkalinity, TDS,  calcium and SO^.  Calcium and SO^ from most FBC
        leachates are similar to those of natural gypsum leachate.
     •  The potential environmental  impact from leaching can be improved
        by further processing.
                                    85

-------
     Intermittent leaching results indicated that initial leachate
characteristics were better from the spent dolomite sorbent, but the spent
limestone leachate improved much faster with total leaching time or
leachate volumes.  Spent dolomite from the once-through system gave bet-
ter quality leachate than did the regenerated sorbent.  Preliminary
results also showed that the spent sorbent from the atmospheric FBC
process displayed leaching properties similar to those of the pressurized
FBC sorbent.  This is encouraging but should be confirmed with more
typical spent sorbents from the atmospheric FBC process.
     Results also show that the leachate of spent limestone bed material
had higher pH, calcium, and IDS than did the corresponding leachate of
fly ash.  The leachate from fly ash is similar to that of natural gypsum,
except for higher pH from the fly ash.  The addition of _>20 wt % fly ash
to the spent bed sorbent improved the leachate quality so that it meets
the gypsum criteria except for pH.   This suggests codisposal of spent bed
sorbent and fly ash generated from the fluidized-bed combustion process
to minimize the environmental impact from the sorbent's leachability.
The environmental impact from disposal is reduced further by room tem-
perature processing — in other words, spent FBC sorbent/FBC ash blending.
     Since there are no criteria for leachates at the present time,
results from the continuous leach test which represents the worst
possible case are compared with drinking water standards and leachate
characteristics for natural gypsum.  As an indication of environmental
acceptability, a preliminary comparison is presented in Table 27 for
those categories of spent bed material and fly ash tested.  The proc-
essed spent sorbent/fly ash compacts from room-temperature blending
possessed similar and better leachate characteristics than did the unpro-
cessed sorbent/ash mixtures, which in turn displayed better leachate
quality than did the spent bed sorbent alone.
                                    86

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                          TABLE 27.   PRELIMINARY  INDICATIONS  OF  ENVIRONMENTAL  IMPACT  FROM THE FBC
                                                         SOLID  WASTE DISPOSAL
           Sample
     Process
                    Sorbent Type
                                                                                        Environmental Parameters
                        Heat Release*-
                    Spontaneous Temp. Rise
                          (3g/20 ml)
Trace
Metal
  Total
Dissolved
 solids
                                                                                Total
                                                                               Organic
                                                                               Carbon
                                                                                            Calcium
                                                                                                                            Sulfate
                                                                                                                                      Sulfide
       .ed Material
                       Pressurized FBC,
                       once-through
                 Limestone
                            <0.2°C
      Bed Material
                       Pressurized  FBC,
                       once-through
                                        Dolomite
                                             <0.2°C
      Bed Material
                       Pressurized  FBC,
                       regenerative
                                        Dolomite
                                         To be determined
                                                                                                             To  be
                                                                                                             determined
00
—]
      Bed Material
                       Atmospheric FBC,
                       once-through
                                        Limestone
                                         To be determined
      Fly Ash
Pressurized FBC,
once-through
                                        Limestone
                                                                    <0.2°C
       Mixture of bed
       material and
       fly  ash
       (unprocessed)
Pressurized FBC,
once-through
Dolomite/limestone
                                                                    <0.2"C
       Processed
       Compacts from
       bed material/
       fly ash
       mixtures
Pressurized FBC,
once-through
                                         Dolomite/limestone
                                              <0.2°C
       Gypsum
                       Natural
                                                                     <0.2°C
       *Based on results from limited samples  available and subject  to the procedures specified in the section on "Activity".

       (§  Do  not meet either the drinking water or gypsum leachate criteria

       Q  Pass gypsum leachate criteria but  not drinking water standards

       []  Pass both  drinking water and gypsum  leachate criteria

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                                SECTION 6
                             OCEAN DISPOSAL

     Sorbent, whether regenerated or not, must eventually he disposed
of.  Spent sorbent may well be utilized as a product raw material.  Some
spent sorbent, particularly from inland plants,  will probably be dis-
posed of in landfills.  At some sites,  however,  it is anticipated that,
as an alternative ocean disposal may be preferred or may even be
necessary.
FEASIBILITY STUDY
     The first of two studies, an investigation  of ocean dumping feasi-
                                         )
bility, was completed in September 1976.   This report entitled "The
Feasibility of Ocean Dumping as an Interim Alternative to Disposal of
Spent Stone from the Fluidized-Bed Gasification  Process" is  included
in its entirety in Appendix A.  This report presents the following
information relative to ocean disposal  of spent  sorbent:
     •  Federal regulations and permit  procedures;  summary of EPA
        regulations and criteria
     •  Approved sites for ocean dumping
     •  Ocean dumping mechanisms; ocean dumping  costs
     •  Feasibility of dumping spent stone at sea
           Attitudes toward various disposal methods
           Requirements under the established permit system
        -  Description of the Westinghouse test  program for  measurement
           of solution characteristics, heat release, and chemical
           changes associated with ocean  dumping of spent stone.
                                   88

-------
     The test results led to  the  conclusion  that because of the high pH
caused by mixing the spent  stone  and  [ocean] water, there may be synergis-
tic effects or the formation  of toxic  compounds during the immediate
release process.  This matter must be  clarified further before proceeding
with a permit consideration.
     This preliminary study clearly outlined the requirements for obtain-
ing a dumping permit.  Before continuing experimental dispersion studies
and biotoxicity testing, a  second investigation was conducted to sense
the current attitudes toward  issuing dumping permits and to identify
specific testing requirements.
SURVEY OF CURRENT EPA ATTITUDE TOWARD  OCEAN DUMPING
     This study completed February 1,  1977,  is attached as Appendix B.
It is an assessment of today's practice in issuing permits and a projec-
tion of the probability of  dumping spent sorbent.
     The specific objectives  of this assessment were to (1) determine
EPA's attitude toward ocean disposal of sulfated and sulfided limestone
in all contiguous U. S. EPA regions, with emphasis on Regions III and IV,
(2) estimate the probability  of EPA issuing an ocean disposal permit
in calendar year 1977 and between 1978 and 1983, and (3) determine what
preliminary bench-scale dispersion and biotoxicity test will satisfy
current EPA requirements.
     These three objectives were  met by contacting EPA Regional Offices
and research laboratories and reviewing rules and regulations as reported
in the Federal Register.  From these contacts and reviews it is con-
cluded that obtaining a permit from EPA to dump waste on a commercial
scale would be extremely difficult in  either 1977 or between 1978 and
1983 because of EPA's general policy to phase out all ocean disposal
of industrial waste by 1981.  The feasibility of ocean dumping is further
limited by the kinds of constituents associated with the waste and by
the regulatory requirements to perform a detailed environmental assess-
ment of the waste and to monitor  the dump site.
                                    89

-------
TEST PROGRAM
     The resistance to ocean dumping makes issuance of a permit seem
improbable and discourages the appreciable cost of bioassays,  chemical
characterization, and dispersion analyses.  A revised test program is
being prepared which would permit an initial assessment of the environ-
mental impact of disposal in the ocean and an assessment of ocean utili-
zation as an alternative.
                                   90

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                                SECTION 7
                               UTILIZATION

     Whatever the outcome of studies on direct disposal of FBC spent
sorbent, a review of possible commercial uses for the large tonnages
of solids involved was undertaken as an appropriate parallel effort.
This review considered and developed several subjects, including a
detailed look at potential markets, an estimate of the maximum invest-
ment in processing facilities, an examination of work in related areas,
execution of bench-scale tests, and an assessment of utilization.
OPTIONS
     An initial appraisal of the problem of spent stone disposition was
                                                                    (*^fi^
given in Appendix F of the 1975 Westinghouse contract report to EPA.
This included consideration of the effect of variations in the FBC
process itself, the production rate of spent sorbent and its chemical
composition, governmental regulations, possible markets, and stone
processing alternatives.  It was apparent that only large markets should
be evaluated.  The acceptable final chemical forms for disposal to the
environment would be carbonate, silicate, or sulfate.  For dolomitic
sorbents, magnesium would emerge as MgO.  Should processing of spent
sorbent prove necessary for either disposal or utilization, twenty-one
alternatives were proposed.  Possible end uses identified were:
     •  Soil stabilization
     •  Landfill
     •  Concrete/aggregate
     •  Gvosum
                                    91

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     •  Acid mine drainage treatment
     •  Municipal waste treatment
     o  Refractory brick.
These options remain attractive, although the work of the past year has
led to assignment of higher priorities to those requiring a minimum of
processing and, preferably, only low-temperature processing.  Low-
temperature fixation of the material is also of interest solely from
the standpoint of reducing the leaching properties of the residue after
disposal.
MARKET DATA
Primary Markets
     When considering potential utilization of the spent sorbent, a prime
consideration is the potential quantity of material to be generated.
A 1000 MWe plant operating on a 3 percent sulfur coal will produce per-
haps 570,000 Mg/yr of spent limestone or 450,000 Mg/yr of spent
dolomite.  Such quantities can only be utilized in some sector of the
construction industry.  This could mean landfill or road construction
and, at upgraded levels of utilization, cement, concrete, and aggregate.
               (49)
Some statistics     are given in Table 28.  The higher prices for aggregate
(sand and gravel) appear to pertain to metropolitan areas that are
exhausting local supplies  of acceptable aggregates.  Agricultural uses
(liming, soil conditioning) might also be outlets for spent sorbent but
are at a competitive disadvantage with limestone.
Special Markets
     On the assumption that a concrete of sufficient compressive strength
could be developed, three  specific utilizations, in addition to use in
general heavy construction, were explored.  One is in coal mining, a
second in low-cost housing, and the third in radiation shielding.  These
are discussed in the following paragraphs.
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        TABLE  28.   MARKET DATA ON SELECTED CONSTRUCTION MATERIALS
   Material               Million Mg/year           Price level  ($/Mg)
Portland Cement
Masonry Cement
Quicklime
Sand
Gravel
67.5
2.8
13.0
333
495
21.10-29.10
22.90-37.50
28.70-70.60
1.75-4.75
, 1.80-4.95

     The room-and-pillar method for underground mining of coal has  the
disadvantage of leaving about half the coal in the supporting pillars.
On the other hand, mine disposal of solid wastes is economically unat-
tractive in the United States because the transportation costs through
miles of underground tunnels are too high.  If recovery of coal frora the
pillars were made possible by the use of pillars made frora spent sorbent,
however, the combined disposal/recovery operation might prove economical.
     Assuming square cross-sectional pillars of coal with side W are left
under the present system, and the space between the pillars is aW,  then
the fraction of coal recovered is given by:

                            f   (1 + a)2 - 1
                                         2    '
                                  (1 + a)
from which
                                            ,1/2
                         a
                           = -i +  (i/d - f)r
For the typical 50 percent recovery, a = 0.414.  Since half the coal is
removed, the compressive load on the remaining coal has been increased
by a factor of 2.
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     If the coal has an average sulfur content of 3 percent and an ash
content of 13 percent, and if the gasification or combustion processes
use a limestone/sulfur treat ratio of 3:1, the amount of waste produced
is 37.8 kg/100 kg coal.  Adding water at the rate of 0.3 kg/kg of mix
to produce a solid compact, the amount of waste returned to the mine is
0.49 kg/kg coal.  If the density and compressive strength of the solid
compact are comparable to those of coal in situ, such an application
would be at least technically feasible.
     Another possibility is low-cost modular housing.  Assuming a 12
by 15 by 8 ft (inside dimensions)  module with 6-in thick walls and
plates, the module would require about 6.8 Mg of material.  This
allows for one door and four window cutouts per module.  A 1000 MWe
plant on limestone could generate material for about 120,000 such
modules annually.  Domestically, assuming a 1 percent population growth,
the demand for dwelling units would be about 1,000,000/yr.  At five
modules/unit, the output of forty 1000 MWe power plants would be required.
The potential in other parts of the world is considerably greater.
     A further aspect domestically is the potential for radiation shield-
ing either for industrial or residential use.  Civil Defense activity
has been at a low level for many years, after an initial flurry of con-
cern.  Strategic planning, however, could include the systematic conver-
sion or modification of at least critical plants from conventional
industrial designs to those that offer radiation protection from nuclear
attack.  The technology of concrete for such applications involves the
use of such high-density aggregates as iron scrap, iron ores, barium
sulfate, plus a higher water content.  With a low-cost concrete, it may
prove feasible to use thicker sections.  At present, a concrete reactor
shield for biological protection may be 10 ft thick.  Water content is
an important factor for neutron shielding.  The presence of calcium
sulfate should not be deleterious per se, since barium sulfate can be
used.  Iron oxide from coal ash should be advantageous, but the effect of
trace elements would have to be determined.
                                    94

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Other Markets

     Use of spent sorbent  as  a  source  of  low-cost  lime  in applications
such as acid mine drainage and  municipal  sludge  treatment was not
examined in detail during  this  reporting  period.   It is assumed, a priori,
that this is technicallv feasible; what is  needed  is a  sufficient
quantity of spent sorbent  to  make  a  field test.
     Tn the high-temperature  area  both cement and  brick remain as pos-
sibilities, although  it is expected  that  these would be at a competitive
disadvantage with respect  to  low-temperature processes.  Nevertheless,
bench-scale tests were planned,  at least  for limestone-tvpe sorbents,
to explore cement production.
OVERALL ECONOMICS
     A rough estimate can  be  made  of the  maximum capital investment per-
missible for sorbent  processing.   A  suitable reference case is that of
simple disposal, for which there will  be  some minimal investment in cool-
ing facilities and, perhaps,  storage capacity for  a nominal period of 1 to
3 shifts.  The major  direct operating  cost would probably be that of
transporting the spent sorbent  to  a  disposal site.  Any alternative
would involve some incremental  capital investment  over that for the
reference case and either  a lower  operating cost or some incremental
direct operating cost, plus a product  realization.
     If P  is the selling  price  of a marketable product per Mg,  and
         s
AC  is the incremental production  cost per Mg of spent sorbent,  then
  P
the gross realization in the  case  of making a saleable product is
P  - AC  S/Mg.  Since a 1000  MWe plant would produce about 450,000 Mg/yr
 s     p
of a sulfated dolomite, each  $/Mg  realization would have the effect of
reducing operating costs by $450,000/vr.  Assuming 17 percent capital
charges, 48 percent taxes,  and  a 20-year  life, the allowable incremental
investment then works out  to  about $890,000 per $/Mg realization in sell-
ing price over incremental  direct  production cost.  The cost includes
utilities, chemicals, direct  labor,  and certain charges estimated on the
basis of direct labor.  This  incremental  investment would be recovered
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in 5 years through the realization.  If it is argued that sorbent dis-
posal is not intended to be a profit-making operation, a longer pavout
time can be used.  For a 20-year payout time, the incremental investment
would be about $2,060,000.
     Since aggregate is selling for about $4.50/Mg, if the flv ash com-
pacts were technically competitive, and therefore could command the same
price, the processing plant obtained for a Si,000,000 incremental
investment over simple disposal would have to have an operating cost
of no more than $3.50/Mg.  This would be lower if an economic incentive
had to be provided to permit the compacts to enter the market.  If the
usual cost estimating factors apply, each $l/Mg realization would sup-
port a bare equipment investment of about $270,000.
     These rough calculations support the viex^ that it is at least mar-
ginally justifiable economically to invest in simple processing facilities
for spent sorbent.  It should be noted that all estimates of the economics
of environmental protection are at a disadvantage compared to the do-
nothing or the direct disposal cases since there is as yet no
accepted figure for the cost of the environmental impact.
TECHNICAL REQUIREMENTS
     Study of environmental aspects of spent sorbent disposition led to
a recognition of the need to understand the nature of water pollution
control, as well as the nature of aggregates and the characteristics
of cement and concrete.
Environmental Considerations
     Water pollution will, of course, be a consideration whether the
final material is used as a landfill, a road bed, or in solid conmacts
exposed to the environment.  To put this in an engineering perspective,
such water pollution requires a series of events:
     •  There must be a source of water.
     •  The water must contact the solid.
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     •  The substances  subject  to  leaching must  be in a chemical  and
        physical condition  such that  leaching  is possible.
     •  The contact time, contact  temperature, and water/solid ratio
        must favor leaching.
     •  The leachate must be  able  to  migrate to  a water stream in
        sufficient quantity.
The addition of solutes  to  ground  water  supplies can  therefore be con-
trolled, or prevented, but  perhaps not completely eliminated by appro-
priate action to modify  one or  -more of these events.
     With respect to water  sources, omitting man-made  sources as sus-
ceptible to control, the question  is  essentially one  of management of
precipitation (rain or  snow).   Such water  either flows  to its lowest
level on the surface of  the earth  or  permeates the earth, always flow-
ing downward under the  influence of gravity until  it  reaches an imper-
meable stratum such as  rock or  dense  clay.  If an  underground aquifer
does not develop, water  will  collect  on  the surface,  forming a lake
until it is deep enough  to  overflow the  lowest point  in its banks.
     Thus, if one wishes to avoid  water  pollution  by  eliminating the
water source, the site  chosen for  accumulation of  the  spent sorbent
must be well above the  local  water table and must  have more annual
evaporation than precipitation.  It is likely that  neither of these
conditions can be more  than partially met  for most  power plant locations.
     Whatever water is available at the  site can  still be prevented from
contacting the spent sorbent.   The site  can be designed for maximum
diversion of surface runoff from adjacent  areas  and for maximum runoff
of surface water from the site  itself.   Ground water moving vertically
under a hydrostatic head created by its  sources  can be  diverted by
bottom drains and liners.   Earth movements  and chemical reactions with
the local soil, however, over many vears can change the permeability
of the soil to leachate  from  the spent solids.   In  addition, liner life
is probablv no more than about  20  years.
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     Even if some water contact cannot he prevented, the potential
pollutants must be in a form that can he leached out hy water.  It is
known that exposure to high temperature modifies the pore structure of
solids like lime and gypsum so that they are considerably less reactive
and are hence termed dead-burned.  Further, other pollutants like sul-
fide or sulfate sulfur and trace elements may be contained within the
solids and, therefore, may not be leachable except with long contact
times.  What this suggests is that a disposal pile might be designed
for maximum porosity to permit any water falling on its surface to drain
off as rapidly as possible.  The effluent would, of course, have to be
monitored.
     Finally, if some leachate is produced, it can be collected and
treated, since it presumably represents a much smaller amount of pollu-
tant than that in the original solids.
     Overall, this brief review indicates that one or more of several
simple design features can be used effectively to control and minimize
water pollution.  Leachates must be managed to avoid more expensive cor-
rective measures in subsequent years.   Competition for disposal sites
near population centers does exist, but this is a matter of long-term
economics.  The trade-off is the cost  of mine-mouth power generation
or even population dispersal versus the cost of transporting wastes long
distances.  Such a study is outside the scope of the present investiga-
tion but is considered relevant to the total solution.
     Some researchers have been investigating the retentive capacity of
clay soils for pollutants.  Griffin     reported on the ability of mix-
tures of kaolinite, montmorillonite, and illite with sand to remove
heavy metals as well as other substances from leachate from a Chicago
landfill.  Anaerobic conditions and long contact times, corresponding
to a flow of less than 2 pore volumes  per month, were used.  Permeabili-
ties were of the order of 10   cm/s for the pure clays and 10   for
sand.  Mercury, lead, zinc, and cadmium were strongly attenuated by the
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clays, with montmorrillonite being  the  least  effective  of  the  three.
The capacity of the clays  for  heavv metal  ions was  low, however, as
indicated by the range of  2 to 16 ppm for  lead or kaolinite.   This means
leachates permeating soils will eventually saturate  them,  and  a further
influx of such ions will result in  a breakthrough.   Such findings favor
immobilizing potential pollutants as a  means  of  environmental  protection
in the event landfill is chosen as  the  disposal  method.
     The preceding considerations support  the conclusion that  a synthetic
aggregate would offer the  potential for immobilizing pollutants while
avoiding the question of mass  permeability.   Some of the spent sorbent
might be usable as fine aggregate,  but  fines  would have to be  screened
and disposed of in a suitable  manner.   By  pozzolanic reactions, either
they or the entire spent sorbent might  be  converted into a coarse
aggregate.  A final possibility is  to dispose of the spent solids in a
landfill by casting essentially monolithic blocks.  If the aggregate
possibility is supported by test data,  then the  spent sorbents would be
directed to road construction  or concrete.
Characteristics of Aggregate
     To aid in assessing the potential  for synthetic aggregate, the
basic characteristics of natural aggregate were  reviewed.  By defini-
tion     aggregate consists of uncrushed or crushed gravel, crushed
stone or rock, sand, or artificially produced inorganic materials.   For
use in concrete, aggregate should be hard, durable, tough,  strong,  and
clean, with only limited amounts of flaky  or  elongated particles,
adherent coatings, or harmful  materials.   The terms gravel, stone,  and
rock appear to be used interchangeably,  but they may be distinguished by
size; in other words, stones are small  rocks  or  fragments of rock and
gravel consists of small rounded stones or fragments of stones.
     Rocks contain one or  more minerals, of which the more common are
feldspars, ferromagnesians, micas,  clavs,  zeolites, silicates, car-
bonates, sulfates, iron sulfides, and iron oxides.  Chemically, the first
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five are silicates of aluminum, calcium, iron, or magnesium, with potassium
and/or sodium present in some cases.  What is of interest is the chemical
reactivity and the physical structure.  Clay minerals and zeolites show
large changes in volume on wetting and drying.  Sulfates, as in gypsum
and anhydrite, offer the risk of attack on cement.  Porous cherts,
shales, some limestones, and some sandstones are known to be susceptible
to frost damage.  Chert is a very fine-grained rock composed of silica
in the form of cryptocrystalline quartz, chalcedony, opal, or com-
binations thereof, and may be alkali reactive.  Quartz is anhydrous,
opal is hydrous, and chalcedony is believed to be a mixture of the two.
Other known alkali-reactive constituents are tridymite,  cristobalite,
zeolites, heulandite, the glassy-to-cryptocrystalline rhyolites, dacites,
andesites, and certain phyllites.  The deleterious expansions sometimes
do not occur until two or more years after the concrete  is placed.
     Unconsolidated sediments include gravel, sand,  silt, and clay,
according to particle size.  There is, however,  also a trend in composi-
tion.  Gravel and coarse sands usually are rock  fragments.  Fine sands
and silt are predominantly mineral grains.  Clay consists exclusively
of mineral grains, largely of the clay minerals  group.  On consolidation,
sandstones, siltstones, and claystones are formed.  The  cementing mate-
rial may be quartz, opal, calcite, dolomite, clay, iron  oxides, or other
materials.  Hard, platy claystones are shales.  Some shales cause concrete
to fail because of excessive shrinkage.  Dolomite in certain carbonate
rocks is present as large crystals scattered in  a finer-grained matrix
of calcite and clay.  Such a structure leads to  deleterious expansions
in concrete.
     Micas are subject to cleavage and also may  alter during the hydra-
tion of cement.  Iron sulfides form ferrous sulfates that, in turn  yield
iron hydroxide and calcium sulfoaluminate.  Surface staining is also
possible.
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Characteristics of Cement and  Concrete
     Concrete has a variety  of uses  depending  on  its  density, compressive
strength, and durability.  These  properties  depend, in  turn, on the
chemical nature of the  cement  used,  the  density of the  aggregate, the
cement and water content of  the mix,  the method of preparation of the
concrete and the air content of the  mix.   Three main  types of concrete
may be distinguished.
     Structural lightweight  concrete  aggregate is defined^52^ as con-
crete having a 28-day compressive strength in  excess  of 17.2 MPa and a
28-day air dry weight not exceeding  1850 kg/m  .   Compressive strengths
of 41.4 MPa are possible with  lightweight  aggregate.  Low-density con-
cretes from lightweight aggregate have compressive strengths in the
                                                           o
range of 0.7 to 7.0 MPa and  unit  weights of  320 to 800 kg/m .  Moderate
strength lightweight aggregate concretes fall  in between.  Lightweight
aggregate reduces the dead weight of  a structure but  usually costs more
per cubic yard than ordinary concrete.  A  lower overall cost can be
obtained through a lower volume of cement  and reduced structural and
reinforcing steel and lower  forming and  handling costs.  The low-density
concretes are used for  insulation, and moderate strength concretes are
often used as fill.  The structural grade  is used for high-rise
buildings.
                                                           3
     High-density concretes, with unit weights to 6010 kg/m  are used in
radiation shielding.  The high-densitv results from the type of aggre-
gate used, but the water content  is also a factor in  effectiveness of
neutron deceleration and capture.
                                               3
     Normal density concrete 1840 to  3200  kg/m  has a wide range of prin-
cipally structural applications.   It  has compressive  strengths in the
range of 17.2 to 27.6 MPa, but strengths are affected bv many factors,
as noted above.
     A cement is a material with  adhesive  and cohesive properties that
render it capable of bonding mineral  fragments into a composite whole.
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In construction the bonded materials are stones, sand, bricks, blocks,
and so on.  The cements used for this purpose are based on compounds
derived from lime and are mainly silicates and aluminates.  Various
                                   (53)
kinds of cements as defined by ASTM  "   are shown in Table 29.
     From these definitions it appears that all of these cements contain
calcium silicates formed at elevated temperatures that in concrete are
hydrated to a silicate gel plus free calcium hydroxide.  The current
development effort includes examining the properties of compacts made
by hydrating a blend of coal fly ash and spent sorbent that has not
been exposed to temperatures as high as those in a cement kiln.  The
nature of the hydration products has not yet been determined.  An alter-
native is to expose such blends to various temperature levels:  auto-
claving under moderate steam pressure,  processing below the sintering
temperature, processing at the sintering temperature,  and processing
above the melting point.
State of the Art - Disposal/Utilization of Solid Wastes
     Relatively little has been done on disposal/utilization of FBC
wastes.  In contrast, so much has been done in related fields that it
is a major task to summarize the contributions to defining and under-
standing the problem of disposal or utilization of calcium-based wastes.
These fields include flue-gas scrubbing, sulfate wastes,  cement, con-
crete, and fly ash.  Certain contributions have been singled out to
help answer the following questions:
     •  What is the impact of a calcium-based waste on the environment?
     •  Can this impact be lessened by one or more techniques?
     •  If the waste is utilized, will the product have a potential
        impact on the environment?
     •  What properties can be expected of solid products made from
        calcium-based wastes?
     •  What is the effect of mix composition on field performance?
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            TABLE  29.   DEFINITIONS OF VARIOUS KINDS 07 CEMENT
Hydraulic Cement -


Natural Cement -
   ASTM C10-73
Portland Cement -
   ASTM C150-73a
Portland Blast Furnace
Slag Cement -
   ASTM C595-73

Portland-Pozzolanic  Cement
   ASTM C595-73
Slag Cement -
   ASTM C595-73

Supersulfated Cement -
Masonry Cement -
   ASTM C91-71
A cement  capable  of  setting  and hardening
under water

A hydraulic  cement produced  by calcining
a clay  limestone  containing  up to 25%
by weight  of argillaceous material below
the  sintering  temperature and then
grinding  to  a  fine powder

A hydraulic  cement produced  by pulveriz-
ing  clinker  consisting mainly of
hydraulic  calcium silicates  and usually
containing calcium sulfate as an inter-
ground  addition

An interground mixture of Portland cement
clinker and  granulated fine  blast furnace
slag in which the slag is between 25 and
65 wt % of the blend

A uniform  blend of Portland  cement or
Portland blast furnace slag  cement and
fine pozzolan produced by intergrinding
clinker and  pozzolan or blending cement
and finely divided pozzolan, in which
the pozzolan is between 15 and 40 wt % of
the blend
A uniform  blend of granulated blast
furnace slag and hydrated lime in which
the slag is at least 60 wt % of the blend

An interground mixture of 80-85 wt %
granulated blast furnace slag with 10-15
wt % dead-burned gypsum or anhydrite and
about 5 wt % Portland cement clinker

A hydraulic cement for masonry construc-
tion containing one or more parts of
Portland cement, natural cement,
Portland-pozzolan cement, slag cement,
or hydraulic lime, and, in addition, one
or more parts of hydrated lime,  lime-
stone,  chalk, calcareous shale,  talc,
slag, or clay
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Such a review is also constructive insofar as it helps identify the kind
of information still needed from an experimental program in order to
formulate recommendations.  A practical consideration in the current
work was the delay in receiving adequate supplies of representative
spent sorbents.
Sulfate Wastes
     Smith et al.,     in work sponsored by the Federal Highway Adminis-
tration, reported on the suitability of mixtures of fly ash, lime, and
sulfate wastes for highway construction.  This work closely parallels
that planned under the present contract for the examination of the lime-
sulfate waste sorbent from fluid-bed combustion and, therefore, is
reviewed in detail.  Following an optimization of the mix composition,
the reaction products were characterized, engineering properties were
determined, and aggregate production was studied.  The study differs
from the present one mainly in that fluid-bed combustion waste was not
examined.  Conclusions relevant to Westinghouse studies are summarized
in the following paragraphs.  First, the effect of calcium sulfate was
explored using simulated wastes.   Four hydrated limes from commercial
sources were used, including both calcitic and dolomitic types.  Four
calcium compounds were used to simulate wastes:  two gypsums, pure
anhydrous calcium sulfate, and a  pure calcium sulfite hemihydrate.
Five low-carbon fly ashes were used, low carbon meaning 1 to 6 percent
loss on ignition at 950°C.  No rationale was given for why high fly ash
contents were used in the mixes:   80 percent fly ash, 12 percent lime,
and 8 percent gypsum.
Effect of Water Content on Compressive Strength
     Three methods were used for  adjusting the water content of the
mixes:  compaction, extrusion, and slump.  The latter involved mixing
in just enough water to produce a consistency comparable to a slump by
a standard AASHTO test on concrete.  The water content obtained was
about 18 to 27 percent for the compaction method and 35 to 45 percent
for the slump method.  The range  of values of compressive strengths for
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test specimens produced  by  compaction  was  16.5  to  35.4 MPa, which was
generally 1.3 to  3.5  times  those  for specimens  produced bv  the slump
method.  Values for extruded  specimens were  closer  to those for  the
slump method than to  those  for  the  compaction method.  These results
are in line with  a commercial technique  known as the Schokbeton  method
for producing high-density,  low water-content,  high-strength concrete
by subjecting it  to rapid,  vertical oscillations without causing segre-
gation of the aggregate.
Effect of Lime Type
     The two limes used  contained 0.7  and  33.4  percent MgO, respectively.
In two-thirds of  the  cases,  the calcitic lime yielded higher strengths
                                                                       \
than the dolomitic.   Six of the results  showed  the  reverse, and  the
remaining four were of about  equal  strength.  Statistical analysis of
the data showed that  all main effects  (lime  type, calcium compound, fly
ash source, and water content)  and  all interactions were significant at
the 95 percent level.  Apparently because  a  highway construction applica-
tion was in mind, however,  the  analysis  was  done only for the 7- and
the 28-day values.  It would  appear relevant to examine the long-term
(91-day) results  since it is  probable  that the  optimum techniques for
utilizing these waste materials have not yet been identified.
Effect of Type of Calcium Compound
     For the compactible data only, after  28 days calcium sulfite and
calcium sulfate were  equivalent.  This finding  is of importance  to the
present work since it implies that  conclusions  from the work on  FGD
sludges, especially in the  fixation work,  might be directly applicable
in the processing and disposition of FBC wastes.
Effect of Lime/Sulfate Ratio
     Smith found  that with  the  better  fly  ashes, that is, with the two
which gave the highest early  strength  in the preceding tests,  28-day
strengths were maximized  by using a lime/sulfate weight ratio of 1:1.
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Strengths dropped off sharply on either side of the maximum.  Lime/sulfate
ratios in the range of 0.75 to 1.25:1 yielded compressive strengths
within 85 percent of the peak.  These results are for the specimens pro-
duced by compaction.  No explanation was given for the results.  Chemi-
cally, the lime/silica mole ratios for these two sets of data were
nearly identical (0.28 and 0.26).  These ratios are very low compared to
Portland cement in which the lime/silica mole ratio is 2:3.  On the
other hand, it appears very encouraging that strengths in the normal
concrete range can be obtained with such low lime/silica ratios.
Effect of Fly Ash Content
     For the same two fly ashes as above, there was a monotonic and rapid
decrease in strength as this ratio was increased from 4 to over 11,
achieved by increasing the actual fly ash content of the mixes from 83
to 95 percent.  It appears unreasonable to expect mixtures containing
as much as 95 percent fly ash to be effective in binding waste sulfates.
These data may be interpreted instead to say that no more than about
85 percent fly ash should be used.
Effect of Sulfate Content
     It was found that 10 to 20 percent gypsum in mixtures containing
3 to 5 percent lime would yield maximum compressive strength.   In another
study     addition of up to 50 percent gypsum on cement showed a linear
increase in compressive strength.  Smith found further that substitution
of anhydrous calcium sulfate for gypsuri did not change the strength at
28 days, explaining this on the hypothesis that the calcium sulfate
hydrated to gypsum.  Strengths at 7 days were higher with the anhydrous
sulfate, suggesting that this was a more reactive form.  In the case of
fluid-bed combustion wastes, any sulfate present should be at least
partially dead-burned and, therefore, less reactive.  The question of
longer term effects, however, such as gradual hydration, needs to be
answered.
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Effect of Portland Cement  Content
     Addition of Portland  cement was found to be detrimental to strength.
Fly ash and sulfate  levels within  each data set, were held constant,
however, so that increasing Portland cement meant decreasing lime.  Since
Portland cement depends primarily  on hydration of dicalcium and trical-
cium silicates, it would appear that a more meaningful experiment would
keep lime constant or  even increase it at the expense of the fly ash.
To be sure, there is a cost factor, but in the case of FBC wastes optimi-
zation of the process  design might include a certain minimum amount of
CaO in the spent sorbent before it enters the spent sorbent processing
section.
Effect of Other Components
     Other substances  tested for their effect on compressive strength
were impurities and  accelerators.  Aluminum sulfate at the 1 percent
level was concluded  to have no effect, but from the data it appears to
have been associated with  a decrease in strength both at 7 days and at
28 days.  The lime used, however, was dolomitic, and the fly ash used
already included 25  percent alumina.  Ferric hydroxide at the level of
2.8 percent also resulted  in weak mixes.
     The small amount  of alumina in normal Portland cement is believed
to have no useful function other than to lower the melting point of the
kiln feed to facilitate the sintering process.
X-Ray Examination
     Characterization  of the reaction products for selected mixes by
X-ray diffraction showed that for  the reference lime-gypsum fly ash mix,
lime disappeared within 7  days of  curing, gypsum diminished, mullite
increased over 9 months, and ettringite appeared after 28 days.  It was
concluded that a new phase consisting mainly of a calcium sulfoaluminate
was formed, but it was not positively identified as ettringite.  New
crystals were observed to  grow from the fly ash surface into the pore
                                    107

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structure and intertwined, which might be an explanation for the strength
increases at early curing times.  It was also found that at least 10 wt %
ettringite had to be present before it was visible under X-ray
diffraction.
Tests on Industrial Sulfate Wastes
     Having explored the effect of calcium sulfate on the properties of
fly ash compacts, actual industrial sulfate wastes were tested in fly
ash formulations.  These included three neutralized acid mine drainage
samples, one titangypsum from extraction of titanium dioxide, one gypsum
from hydrofluoric acid manufacture, one neutralized waste pickling
liquor from steel manufacture and two FGD scrubber sludges.  The refer-
ence mix, containing 5 percent lime and 95 percent fly ash, developed
a compressive strength of 2.6 MPa (370 psi) in 28 days.  The specimens
were prepared by the compaction technique.  In all of the mixes prepared
with waste sulfates, the fly ash content was in the range 72 to 93 per-
cent, while the lime was 1 to 11 percent.
Screening Tests for Compressive Strength
     Only two of the acid mine drainage samples were tested, the third
being omitted because its solids content was too low (and apparently
could not be concentrated by mechanical techniques like centrifuging).
Significantly different strengths were demonstrated:  2.6 to 2.8 versus
4.6 to 5.6 MPa (370-405 versus 660-805 psi).  No explanation was given
for this difference.  The waste with the higher CaO and SO  content,
however, gave the higher strengths.  Both had about 8 percent alumina
plus iron oxide in the waste.  The steel pickling liquor waste had
similarly low values of strength, 2.4 to 3.2 MPa (355-465 psi), at the
level of 5 percent waste.  At 10 percent,  the strength dropped to
0.34 MPa (50 psi) .
     The two waste gypsums yielded strengths in the range 6.6 to 10.1 MPa
(950-1470 psi).   It nay be of interest that the total of alumina and
                                   108

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iron oxide for these wastes was  low  (2-4 percent).  At 3.2 percent lime
increasing the waste sulfate  content  to 25 percent for the hydrofluoric
acid waste showed a trend of  increasing compressive strength for speci-
mens prepared by compaction,  7.9  to  10.1 MPa  (1150-1470 psi).
     The scrubber sludge from Kansas  Power and Light, which had 5 percent
S03 (presumably sulfate sulfur)  and  28 percent calcium as CaO, also
showed a trend of increasing  strength, with increasing waste content to
13 percent from 6 percent, 12.4  versus 6.3 MPa (1180 versus 920 psi).
     The maximum compressive  strength obtained was with a sulfite
scrubber sludge from Louisville  Gas  and Electric, containing 68 percent
solids and 4 percent sulfur as SO  and 32 percent calcium as CaO.  The
28-day strengths were  10.2 and 12.3 MPa (1480 and 1790 psi).  It was
found that, unless mixing was adequate, pockets of unmixed sludge would
be found in the compacted samples.   The highest strength corresponded
to the mixing technique in which  the  lime and fly ash were preblended
and slowly added to the mixer containing the sludge and mixing water.
Engineering Evaluation
     Six lime—fly-ash—sulfate formulations were used to make an evalua-
tion of engineering properties like  freeze-thaw resistance, wetting and
drying resistance, California bearing ratio, permeability, splitting
tensile strength, and  leachability.   Again, lime was never more than
5.6 percent of the mix; and the  lowest fly ash content used was 62 per-
cent, with four of the six mixes prepared in the range of 80 to 86 per-
cent fly ash.  Only calcitic  lime was used in these mixes.  A gypsum
mix was used as the reference mix.
     Effect of Aging on Strength.  All of the mixes showed an improve-
ment in strength properties on aging  to 91 days.  The standard developed
as much as twice the unconfined  compressive strength as the other five
test mixes, 15.8 to 7.6 MPa (2295 psi versus 1100) and developed two to
three times the splitting tensile strength, 3.6 MPa versus 1.1 to 1.6 MPa
(520 psi versus 165 to 225 psi).  Its CBR was 617 in 28 days versus 335
to 487 for the other mixes.
                                    109

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      These  values  are  all higher  than that of  the well-graded  crushed
 stone CBR standard.
      Effect of Mix Type on Permeability.  In some cases,  the permeability
 for  the  test mixes was lower than that for the reference  mix,  reaching
 values as low as 0.8 x 10   cm/s  in 28 days.  One of the  scrubber
 sludges, Kansas PEL sludge, had a permeability of 17.0 x  10    cm/s.
 To put this in a more  direct perspective, a permeability  of 1  x 10    cm/s
                                                                      2
 means that  at steady state, leachate production would be  0.6 cc/min/m .
 It appears  that acceptably low values of permeability can be achieved
 with fly ash/sulfate sludge mixes.
      Samples cured for 28 days had generally much less solute  leached
 than at  7 days, reaching concentrations in the range of 0 to 50 ppm of
 sulfate  for some samples.  It was concluded that lime and gypsum had
 reacted  chemically to form insoluble material and that, considering the
 low  levels  of permeability achieved, ground water infiltration by leach-
 ates from these mixes would be very small.
      Effect of Freeze-Thaw Exposure.  In the freeze-thaw tests, it was
 found that  7 days  curing was insufficient, since only one sample besides
 the  reference mix  survived 12 cycles.   Wetting and drying proved to be
 less severe  than freeze-thaw exposure.   Curing for 28 days before freeze-
 thaw exposure yielded terminal values  of compressive strength of the
 order  of 2.1 MPa (300 psi).
      These  results are not favorable,  but nor are they considered applic-
 able to Westinghouse studies since the mix composition was at a much
higher level of fly ash.
Aggregate Properties
     Two formulations were also prepared, using somewhat more lime (7.5-
 8.0  percent), which were then cast or  extruded to form solid specimens
 for  testing as aggregate.  After 28 days of moist curing, the mixes were
still  too soft for use.  Curing for 14  days at 40.9°C yielded one usable
material.   This was crushed and graded.   At least 10 percent fines were
produced, in this  step, that would in  commercial operation represent
                                   110

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waste that might not be  recyclable  or  usable  in  some other way.  The
specimens failed the freeze-thaw, the  sulfate soundness, and the Los
Angeles abrasion tests.  When  made  into  a  concrete with Type II Portland
cement and an air-entraining agent,  28-day strengths up to 23.1 MPa were
obtained.  Again,  all  six  beam samples tested failed the AASHTO T-161
freeze-thaw  test in less than  104 cycles.   It was concluded that none of
the mixes yielded  aggregates suitable  for  concrete subject to freeze-thaw
conditions.  Lime-fly-ash-waste-sulfate  mixtures, however, might be
suitable for road  construction as base course, subbase, or embankment
material.  Longer  curing times,  of  the order  of  6 to 9 months, should
produce stronger and more  resistant aggregate particles.  The effect of
curing time  specifically on freeze-thaw  durability should be investigated.
Fly Ash
     Dunstan,      in work  done through the Bureau of Reclamation, con-
cluded that, although  lignite  and subbituminous  fly ashes would make
concrete with satisfactory freeze-thaw durability and adequate compres-
sive strengths,  they should not  be  used  where a  severe sulfate condition,
as defined by the  Bureau's standards,  exists. Fly ash characteristics
found are summarized in  the following  paragraphs.
Composition
     None of the five  fly  ashes  tested met all of the requirements for
Federal Class F pozzolans.
     Dunstan noted that  fly ash from the lower rank coals generally had
lower Fe 0   contents in  the glass fraction, which typically is in the
range of 60  to 70  percent.  The glass  fraction is considered the most
reactive portion of the  fly ash. Iron oxide  appears to have a moderating
influence on the formation of  ettringite which,  in turn, is mainly
responsible  for deleterious expansions.  Fluidized-hed combustion fly
ash, on the  other  hand,  is formed at much  lower  temperatures than is
                                    111

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normal fly ash, and the glass content can be expected to be lower.  It
is not necessarily less reactive because the lower temperature of
formation may result in less change in pore structure.
     Other properties of these low-rank fly ashes also differed from the
requirements of Class F pozzolans.  The total of SiO  + k1~p~ + Fe2°3
for all three lignite ashes and one of the subbituminous ashes were less
than the 75.0 percent required.  These same four ashes also had MgO in
excess of 5.0 percent.  Two of the lignites and the other subbituminous
                                                2   3
ash had specific surface areas less than 6500 cm /cm" .  It was not
established that these variations were responsible for the differences
in 7-day strength of a standard lime-pozzolan mix and alkali reactivity.
Compressive Strength
     When mixed with sand, cement, aggregate, water,  and an air-entraining
agent, the 7-day strengths were in the range of 10.A  to 18.9 MPa (1510-
2470 psi) versus 17.9 MPa (2600 psi)  for a mix containing no fly ash.
Compressive strengths continued to increase on aging for 180 days to
the level of 31.1 to 39.0 MPa (4510-5650 psi) versus  41.0 MPa (5940 psi)
for the mix without fly ash.  At 365  days, the corresponding values were
32.3 to 41.5 MPa and 38.6 MPa (4680-6020 and 5560 psi), respectively.
Dunstan pointed out that the fly ash  mixes had less total cementitious
material (cement + fly ash) than did  the fly ash-free mix.  Somewhat
lower compressive strengths for the fly ash mixes were therefore not
unexpected.
Linear Expansion
     Mixes with 25 percent replacement of cement by fly ash generally
showed larger expansions due to sulfate attack than did those with only
15 percent replacement.  The reference fly ash, a Class F pozzolan
representing a blend of six bituminous coal fly ashes from the Chicago
area, showed about the same linear expansion at 15 and 25 percent fly
ash.  Continuous soaking in 10 percent sodium sulfate at room tempera-
ture produced expansions of 0.01 percent in 460 days.  In an accelerated
                                   112

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test consisting of cycles of  16 hours  soaking  in  2 percent sodium sul-
fate and 8 hours drying at  54.4°C,  the expansions in  the  same length of
time were about double  (0.019 percent).   In  all other  cases, including
the no fly ash mix, greater expansions were  obtained  in less time, some
nearly to the point of  failure  (0.5  percent).
     This indicates a need  to identify the cause  and whether higher
Fe2°3 content will be effective in  reducing  these expansions.  Until
these expansions can be controlled,  the use  of lignite and subbituminous
fly ashes in cement-type products will not be possible.
STATE-OF-THE-ART SPECIFICATIONS AND  TEST METHODS
     Before a new material  can become  commercially acceptable,  it must
be standardized to the  extent of meeting  specifications on important
characteristics as shown by particular tests.  It appears that not only
are there no specifications on FBC solids or products made from them,
but there are also no directly applicable tests.  In anticipation of
adapting existing tests, such as ASTM-C666,  to the FBC program,  work
done by others on freeze-thaw resistance and the more general question
of test methods is presented  in the  next  two sections.
Freeze-Thaw Resistance
     BackstronT    investigated  the effect of water-cement ratio on the
freeze-thaw resistance of non-air- and air-entrained concrete.  He con-
cluded that the freeze-thaw resistance varies inversely with the water/
cement ratio of the concrete.  For non-air-entrained concrete with a
water/cement ratio less  than 0.45, the increased resistance is probably
due to a decreasing amount of  freezable water in the cement paste, which
approaches zero at a ratio of  0.40 or less.  For air-entrained concrete,
the air void spacing varies directly with the water-cement ratio, and
the freeze-thaw resistance varies inversely with the air-void spacing.
                                      (52)
This parameter is defined in ASTM C457V    as the maximum distance of
any point in the cement  paste  from the periphery of an air void.  The
                                    113

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spacing factor for the specimens used were in the range of 0.10 to
0.23 mm.  Air voids reduce the strength of concrete hut increase its
durability.  Cordon^    notes that the protective action is obtained
when the spacing factor for the air-void system is 0.20 ran or less.
                                                       (59)
There are several kinds of pores and voids in concrete:
     •  Gel pores - the interstitial cavities between the particles of
        tobermorite (CaO-SiO «H 0) and other calcium silicate hydrates,
        averaging 0.0015 to 0.0020 urn
     •  Capillary pores - the unfilled spaces between aggregations of
        gel particles formed by uncombined water in excess of that
        required for hydration and averaging 0.5 urn in diameter
     •  Bubbles of entrained air averaging from a few microns to a few
        millimeters in diameter.
Water in gel pores in concrete below 0°C is supercooled but not frozen
until, perhaps, -78°C.  Water in capillary cavities will freeze since
the cavities are large enough to accommodate a sufficient number of
molecules to make ice crystals.  Bubbles of air are ordinarily not
filled with water unless saturation has been brought about by vacuum or
pressure.  The basic mechanism of deterioration of concrete,  and pre-
sumably of any solid body under freeze-thaw conditions, is the formation
of ice in voids insufficiently large to contain them and insufficiently
connected to the neighboring voids to permit excess water to escape or
the ice to expand into them.  Pressures are then developed in excess of
the tensile strength of the cement paste.
     In order to cure concrete so that it develops its maximum strength,
sufficient water for hydration must be present within the mix and at the
the boundaries of the mix.  This can be provided by moist coverings, fog
cure, or immersion.  On the other hand, it appears detrimental to use
conditions leading to saturation of all voids.  It is, therefore  an
objective in the development of a cementitious material to determine
                                   114

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optima for particle  size  distribution,  water content,  and  air  content.
Backstrom's work      did  not  cover the  effect of air voids on  sulfate
resistance.
Standard Tests and Specifications
     Another area of investigation is that  of test methods and specifica-
tions.  Brown,     in a paper dealing with  energy conservation, con-
cluded that a lack of standard tests and specifications was an important
factor inhibiting the use of  blended cements to  perhaps 1  percent of
the domestic market, whereas  in France  it is 60  percent.   The indus-
trialized countries  use 20 to 30 percent blended cements.
     ASTM C595-74, for example,  covers  three types of  blended cements
containing 15 to 40  percent fly ash, or 25  to 65 percent blast furnace
slag or a minimum of 60 percent slag.   Other compositions  are not
covered, so there is no basis for  evaluating their suitability.  The
specification, however, includes six chemical tests and ten physical
tests which may be unnecessarily restrictive.  The fly ash specifica-
tion C618-73 effectively  excludes  many  western coal ashes  on the basis
of their total SiO , AIJ}., and Fe-0  content, even though use of fly
ash not meeting the  minimum total  of these  constituents has not been
shown to produce unsatisfactory cements.  This specification also
includes six chemical tests and thirteen physical tests.   With regard to
standard tests, Brown believes that new or  improved tests  are needed,
including soundness, sulfate  resistance,  and freeze-thaw durability.
The present test for soundness is  intended  to show whether the hydration
of any dead-burned CaO or MgO in the cement after the  cement has hardened
will cause failure through excessive expansion.   To get results in a
reasonable time, an  autoclave procedure is  used  in an  effort to acceler-
ate the hydration rate.   This may  be overly severe for Portland cement
and inadequate for blended cements.  Another objection is  directed at
testing specimens after only  one dav of curing.   It is argued  that this
biases the results against fly ash cements  because their one-day strengths
are normally lower than those of Portland cement.
                                     115

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     The only standard sulfate resistance test available is ASTM C452-68,
which deals with the expansion of mortar and is applicable only to Port-
land cement.  The description of the method also states that the method
is intended for research on methods of determining sulfate resistance.
Brown points out that the test procedure is not representative of field
conditions.  Gypsum is mixed with cement and then water is added.  It
is likely that adverse reactions can occur under these conditions before
the mortar has developed its full strength.  In the field, sulfate attack
probably occurs by diffusion into the concrete after it has undergone
substantial hydration.
     Brown's objection to the ASTM C666-73 freeze-thaw test is similar
to that for the soundness test — namely, testing after a short curing
period.  In this case, the curing time specified is 14 days, although
other times are permitted.  This may not be an important objection in
the case of FBC sorbents because strengths in the range 6.9 to 13.8 MPa
(1000-2000 psi) within 7 days have already been demonstrated.   The test
has not been correlated with field performance quantitatively, however,
so service life cannot be predicted.  It would appear that the effect
of curing time before subjecting to freeze-thaw testing should be
included in testing new materials.
EXPERIMENTAL PROGRAM
     Actual tests devised reflected the constraint of delay in spent
sorbent supply.  Pilot units were operated to yield data on the FBC
process itself; thus, production of spent sorbent and associated fly
ash were generally incidental aspects of the test runs.  Within this
constraint, the test program identifies the sorbents to be included,
feasibility tests, and more extensive screening tests.
Identification of Spent Sorbents to Be Tested
Combustor Variables
     The spent sorbent from fluid-bed combustion is basically a new
material whose physical and chemical properties must be defined by
                                    116

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appropriate tests.  Examination  of  the  main  process  as  discussed in an
earlier section reveals  that  at  this  stage of  development  there are still
several potential spent  sorbents to be  characterized.   The sorbent may
be a limestone or a dolomite,  or a  synthetic based on these or on a
different metal atom,  such  as  iron.  The  spent sorbent  is exposed to
elevated temperatures  for several hours and  has  a variable sulfur bur-
den, which for calcium-based  sorbents is  in  the  form of calcium sulfate,
possibly with traces of  calcium  sulfide.  The  balance of the calcium
is expected to be principally  a  mix of  calcium oxide and calcium car-
bonate, depending on the operating  pressure  and  temperature.  It is pos-
sible that some of the calcium may  enter  into  reactions with the coal
fly ash to form calcium  silicates or  aluminates.  Trace elements from
the fossil fuel and from the  fresh  sorbent will  also be present.  The
physical structure of  the sorbent will  be modified by chemical reactions,
pore migration, and pore size  changes.
     Further variations  enter  through other  process  conditions.  The
calcium/sulfur molar treat  ratio will depend on  whether the process is
once-through or regenerative,  the sulfur  retention required, and the
calcium utilization obtainable.   For  limestone once-through the ratio
may be in the range of 1 to 5  for 90  percent sulfur  retention.  For
dolomite the range may be somewhat  narrower.   For regenerative processes
the range is projected as 0.2  to 2.0.   The number of potential calcium-
based sorbents to be characterized  is estimated  as follows:
     •  Two sorbent types           Limestone  or dolomite
     •  Three molar treat ratios   Normal,  high extreme, low
                                    extreme
     •  Three CaO/CaCO  ratios     Normal,  high extreme, low
                                    extreme
     •  Two coal types             Reflects the Si02/Al203/Fe203
                                    content  of the coal ash
     •  One temperature  level       One is probably  representative
                                     117

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This leads to 36 different spent sorbents, that must be taken into
account by the spent sorbent test program.  It is expected that the
sorbent properties relevant to disposal will not all be critical; thus,
the actual number to be tested should be substantially less than 36.
The manner in which this was handled is tested in the next paragraph.
Composition Ranges
     To define the spent sorbent composition range of interest, Fig-
ure 24 was prepared with the aid of information reported in Appendix D
of Reference 35 on sulfur retention in the fluidized-bed combustor ver-
sus calcium/sulfur mole ratio.  The temperature selected was 850°C.
The projected percent sulfur retention versus calcium/sulfur mole ratio
of 850°C is:
                                           Percent
                 Ca/S                 Sulfur Retention
                  1.0                        50
                  2.0                        80
                  3.0                        95
                  5.0                        98
The sorbent was 1359 limestone.  It is not intended to imply that these
values are definitive (since they are based upon laboratory TGA data at
limited conditions), merely that they are representative.   Ideally,
90 percent retention will be achieved at Ca/S = 1.0,  in which case the
spent sorbent will be mostly CaSO^.  Although the graph shows only three
components, the calculations include an allowancexof  5 percent for non-
calcium impurities in the limestone.  The parameter reflects the effect
of varying degrees of calcination of the unreacted CaCO
     Based on available pilot-plant data, a representative composition,
on an impurity-free basis is 63.3 wt % CaCO   28.4 wt % CaSO   and
                                           J                4'
                                   118

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I-"
VD
                          Parameter;  Percent of original
                          CaCCL surviving calcination
                                                                     98% S Retention @Ca/S = 5.0
                                                                             90% S Retention @Ca/S= 2.5
                                                                                  50% S Retention @Ca/S = 1.0
                                                                                            90% S Retention
                                                                                             @Ca/S = 1.0
                                                                                                 CaStX
         Figure 24.  Projected Composition Range  for Spent Sorbent  from Fluidized Bed Combustion at 850°C

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8.3 wt % CaO.  Table G.I of the same report shows the calcium/sulfur
ratio used was 1.67.
Weight percent CaSO
                    /OON
ratio used was 1.67.      The equations defining the system are:
                                     136.14 a
                                             s                	 x 100
                    80.06 ag
                                f                         /^L^l
                             + R[56.08 + 44.01 ^ + 100.09^-^ — )\
                                   56.08 [(l-aL)R-agl
              Weight percent CaO =	 x 100  ,

where D is the same denominator as in equation 1; and
                                       100.09 SL  R
                Weight percent CaCO  =	 x 100  ,

where
      R = molar treat ratio, Ca/S
     a  = fractional sulfur removal
      s
     a^ = fraction of CaCO, feed surviving uncalcined
      LJ                   -3
     fT = fraction of CaCO, in feed limestone.
      LI                   j
Solving these simultaneously with the above composition, including f
as 0.9218, yields R = 2.2, and a  = 50.2 percent and a^  = 60.9 percent.
                                5                     J_i
The latter checks out fairly well, but the other two values do not.  As
data are located and processed, they will be used to confirm the area
of interest shown in Figure 24.  Obviously, adequate quantities of spent
sorbent of the proper compositions are not yet readily available for
testing.
Sources
     Upon review of available information on pilot-plant operations, it
was decided to use the sources shown in Table 30 to represent the vari-
ous FBC options.  Chemical analyses of actual material used are in
Table 31; B&W stone is included for comparison in anticipation of
                                    120

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               TABLE 30.  SPENT SOKBENT TEST COMPOSITIONS

Fluidized-Bed Process Type
Once- through
Combustor
Once- through
Boiler
One-Step
Regenerative
Combustor
Pressure
Sorbent
Projected Composition,
wt %
   CaSO.
       4
   CaO
   CaS
   MgO
   Balance
Expected Sorbent Source
Actual Sorbent Composition,
ash-free basis, wt %
   CaSO.
       4
   CaO
   MgO
Atmospheric
Limestone
    2.3
   PER
   69.4
   30.6
Pressurized   Atmospheric
Dolomite      Limestone
43.7
54.0
_
64.1
6.6
—
26.1/43.1
70.1/54.6
1.3/0
   28.1
    1.2
   Exxon
   61.2
   22.6
   16.2
 2.5/2.3
Not available
aSpent  sorbent  from regenerator/combustor.

future  tests.   Table 30  shows  the PER stone is more sulfated than
expected while  the Exxon stone is close  to target.  The actual free CaO
content is not  known because of  its  possible chemical combination with
oxides  in the ash.
                                    121

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TABLE 31.  CHEMICAL ANALYSES OF FBC SPENT SORBENTS
Source
Material
Typical
Duquesne
Fly Ash
( Conven tional)
PER Bed
Exxon
Run 43
Bed
Run 43
Fly Ash
B&U
Run 19
Bed
Composition, wt
CaO
MgO
Si02
A12°3
Fe2°3
so3
LOI
Other
Composition,
moles/lOOg
CaO
MgO
Si02
A12°3
Fe2°3
so3
Molar Ratios
S03/CaO
CaO/SiO
CaO/MgO
%
0.40
1.0
44.9
19.1
9.6
—
14.0
11.0
100.00

0.0071
0.0248
0.7472
0.1873
0.0601
—

—
0.0095
—

28.84
2.13
27.20
10.26
5.39
19.90
1.04
5.27
100.00

0.5142
0.0528
0.4526
0.1006
0.0338
0.2486

0.4835
1.1361
—

38.64
13.25
8.60
5.70
3.95
29.00
0.32
0.44
100.00

0.6890
0.3287
0.1631
0.0559
0.0247
0.3635

0.5276
4.8148
2.0951

15.62
7.70
29.40
11.20
8.80
16.38
4.23
6.67
100.00

0.2785
0.1910
0.4893
0.1098
0.0501
0.2046

0.7346
0.5692
1.4581

67.01
1.25
3.90
5.55
2.00
19.09
0.51
0.69
100.00

1.1949
0.0310
0.0649
0.0544
0.0125
0.2384

0.1995
18.4114
—
                        122

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Feasibility Tests
Blending Tests

     Experimental work began with  bench-scale  feasibility  tests, making
solid compacts by blending with  fly  ash.  Using available  materials,
4.4 by 4.4 by 2 cm blocks were cast  from mixes  containing  Duquesne Light
Company fly ash (from a  conventional coal boiler)  and  oxidized sulfided
Tymochtee dolomite made  in the Westinghouse  10-cm  laboratory test unit
in Run D-l.  The latter  contained  28 wt % CaSC^.   The  spent sorbent
was ground to -125 urn.   Compressive  strengths given in Table 32 were
normal to the 4.4 x 4.4  faces.   These showed that  the  addition of 10 to
20 percent fly ash with  or without Type I Portland cement yields com-
pacts with significant compressive strength within 5 days' curing time.
By way of perspective, a dense clay  is perhaps  the poorest soil con-
sidered suitable on which to erect buildings.   It has an allowable bear-
ing strength of at least 192 kPa.  The cubes without Portland cement
had a compressive strength of about  1380 kPa.

   TABLE 32.   COMPRESSIVE STRENGTH OF SULFATED DOLOMITE/FLY ASH BLENDS





Test


Composition (g)

Sulfated
Dolomite


Fly Ash
Type I
Portland
Cement


Water
Compressive
Strength
(5 days)


MPa


psi
1A
IB
1C
100
100
100
20
10
20
                                     10
76
70
80
1.59
1.17
2.21
230
170
320
                                    123

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     When Exxon spent sorbent from the miniplant became available, its
pozzolanic activity was tested.  Five-centimeter cubes were cast from
mixes of the spent dolomite from miniplant run 27     (refer to EPA-
600/7-77-107) and the associated "fly ash" collected in the miniplant
cyclones.  The latter actually is a mixture of dolomite fines and coal
fly ash.  The spent sorbent was ground to -125 ym and two cubes of each
of the two mixes prepared as shown in Table 33.
     These values were considered very encouraging, especially since the
MgO content was high.  Mix 2 can potentially be used for low-grade
structural production, i.e., continuously supported beams.  The Mix 2
specimens weakened somewhat at 21 days, but at 28 days were back to the
level of 7-day strength (9.33 MPa or 1352 psi).
           TABLE 33.  COMPRESSIVE STRENGTH OF 5-CM CUBES CAST
                     FROM EXXON RUN 27 SPENT SOLIDS

Composition (g)
Pfizer 1337 spent dolomite
Fly ash from miniplant
Fly ash, wt %
Water
Compressive Strength (7 day)
Psi
Average (psi)
(MPa)
Mix 1
765
425
36
530

355, 383
364
2.51
Mix 2
1080
120
10
360

1405, 1325
1365
9.41
     Chemical analyses showed that, although the CaSO  and CaO contents
of the spent sorbent were approximately as desired, the Ca/Mg ratio was
about 2:1 instead of the expected 1:1.  The interpretation was that the
material received from Exxon was probably from an early part of Run 27
and limestone that had served as the start-up bed material had not been
                                    124

-------
completely purged from the bed.  The  inert  content was estimated from
chemical analyses for sulfur, magnesium, C(>2,  and H20 as  38 percent, so
the bed apparently retained a substantial amount of  fly ash.  The fly
ash taken overhead had a Ca/Mg mole ratio of about 1.
Isostatic Pressing
     An exploratory experiment was made on  another portion of Exxon
run 27 spent sorbent that had been ground to -125 ym.  A cylindrical
specimen was prepared dry, with no fly ash, by isostatic compression at
138 MPa (20,000 psi) for 1 to 2 minutes.  The  specimen was cured in
water for about 2 weeks and then cut  into four segments with an L/D
ratio of 1 and the axial compressive  strengths determined.  Values
obtained were 27.8, 40.1, 30.8, and 4.98 MPa (4040,  5822, 4472, and
7222 psi).
     Follow-up data on this technique for three samples cured for about
40 days showed an average compressive strength of 89.3 MPa (12,960 psi).
For comparison, normal Portland cement will yield values in the range
of 103.4 and 172.4 MPa (15,000-25,000 psi).
     These feasibility tests showed that:
     •  Stable solid compacts could be made at ambient temperature
        by blending spent sorbent with fly ash and adding water.
     •  Significantly high values of  compressive strength could be
        achieved relative to the landfill requirements.
     •  At least for the curing times tested,  MgO did not inter-
        fere with the pozzolanic reactions.
     •  Strengths higher than normal  concrete  are attainable by
        isostatic pressing.  The strengths approach  those of Port-
        land cement cylinders made by isostatic pressing.
Screening Tests - Exxon Stone
     It having been demonstrated that stable compacts could be produced
even with a dolomite sorbent, prior to undertaking studies of engineer-
ing properties and durability, a screening test was  designed to explore
                                    125

-------
the effect of mix composition, water content, and curing time on com-
pressive strength, response to leaching (which is reported elsewhere in
this document),  and compressive strength after leaching.  Three mix
compositions were chosen to reflect typical production proportions of
spent bed material and fly ash, a low fly ash content, and an inter-
mediate level of fly ash.  The low was chosen arbitrarily at 10 percent,
and the intermediate level was set 50 percent higher.  Processing vari-
ables included fly ash/spent sorbent ratio, water/total solids ratio,
particle size range, and free CaO/Si02 ratio.  In these tests no CaO
was added, and the spent sorbent was in every case ground to -125 um.
     As an incidental aid in planning tests, the predicted spent sorbent/
fly ash weight ratio as a function of the sulfur content of the fuel
and the calcium/sulfur molar treat ratio was developed (Appendix C,
Figure C-l).  Projections are based on 10 percent ash in the fuel,
90 percent retention of fuel sulfur, and the impurities in the sorbent.
The ratio varies directly with the sulfur content of the fuel and
inversely with the ash content of the fuel.  For dolomite, the calcula-
tions predict 1.8 kg of spent sorbent will be produced per kg of coal
ash from a 2 percent sulfur fuel at a calcium/sulfur treat ratio of 2,
or 0.346 kg ash/kg sorbent + ash.  These conditions appeared to be
reasonable estimates applicable to Exxon run 27 material.  Chemical
analyses are given in Table 31 for the Exxon residues and for other
residues used in this program.
     The three fly ash contents chosen were 10, 35.8, and 15 percent,
corresponding to low, typical production proportions, and intermediate
levels.  Two water contents were used, 44.5 and 30.0 percent, with a few
observations at 34.2 percent.  A minimum of three curing times was used:
7, 28, and 60 days.  Duplicate samples were prepared in most cases.  A
parallel set of samples was made to be subjected to leaching for
1040 hours after curing for various lengths of time and then tested for
compressive strength.  The data obtained are presented in Table 34 and
Figures 25 through 28, from which the following observations are made:
     1.  Significant compressive strength (at least 3 MPa or 435 psi)
         can be developed with mixes containing 10 to 36 wt % fly ash.
                                    126

-------
     2.  Most of the mixes  developed  75 percent  of  their apparent
         ultimate strength  within  7 to 10  days.
     3.  At 30 days of curing  time, Mix III with 15 percent fly ash was
         35 percent stronger than  Mix II with  10 percent fly ash.  Mix II
         was 2.5 times stronger  than  Mix I, which had 35.8 percent fly
         ash.  All these contained 30 percent  water.  These trends per-
         sisted at 60 days  of  air  curing time.
     4.  At higher fly ash  contents (36 percent  as in Mix I), the trend
         of the data in Figure 25  suggests the existence of an optimum
         water content.  This  is supported by  the crossplot in Fig-
         ure 28, where the  optimum for 36 percent fly ash mixes is about
         35 percent water.  Similar optima are postulated for the other
         two mixes.
     5.  Leaching for 1040  hours appears equivalent to water curing.
         From Figure 25 strengths  equivalent to  that for the optimum
         water content (34  percent) were obtained by leaching specimens
         containing 45 percent water  for 1040  hours.  This suggests that
         it is preferable to have  somewhat more  water than optimum in
         order to have sufficient  plasticity in  the mix and then achieve
         the desired strength  by adequate water  curing.
Screening Tests - PER Stone
     A 55-gallon drum of spent bed material was  received from Pope,
Evans and Robbins (PER).  This was produced by burning Sewickley coal
with Greer limestone at 815°C.  Chemical analyses in Table 31 show that
the calcium was about 48 percent sulfated.  This was not a typical sul-
fation level but did offer  an  opportunity  to test a spent sorbent at
the high end of the sulfation  range.  Free CaO/Si02 works out to 0.6 on
a molar basis.  Initial results obtained for 2-in cubes with this mate-
rial are shown in Table 35.
     These tests were an exploration  of processing PER as received.
PER-1 showed that merely adding water does not result in significant
cementitious reactions.  Tables  36 and 37  provide possible explanations
                                     127

-------
                      TABLE 34.   MATRIX FOR SCREENING TEST USING 2-INCH CUBES MADE FROM SPENT
                                       SORBENT AND FLY ASH FROM EXXON RUN 43
NJ
00

Mix Sample
I 1A
IB
1C
ID
2A
2B
2C
2D
2E
2F
2G
2H
3A
3B
3C
3D
3E
3F
3G
3H
4A
4B
Fly Ash/
as % of
Total
Solids
0.358

0.358

0.358

0.358

0.358

0.358

0.358

0.358

0 . 358

0.358

0.358

Water/
as % of
Total
Solids
0.445

0.445

0.445

0.448

0.300

0.342

0.445

0.445

0.300

0.342

0.445

Nominal
Curing
Time (days)
7

7

21

21

21



28

28

28

28

60

Test
CS
CS
L+CS
L+CS
CS
CS
L+CS
L+CS
CS
CS
CS
CS
CS
CS
L+CS
L+CS
CS
CS
CS
CS
CS
CS
Date
Cast
5/28
5/28
5/28
5/28
5/28
5/28
8/9
8/9
6/11
6/11
8/20
8/20
8/9
8/9
8/9
8/9
6/11
6/11
8/20
8/20
11/22
11/22
Compressive
Strength
MPa
2.64
2.45
7.38
8.48
1.74
2.64
6.34
6.20
3.68
3.44
6.88
8.69
5.14
4.45
6.43
6.83
4.03
3.23
6.74
6.58
5.35
5.25
psi
383
353
1070
1230
253
383
920
900
535
500
998
1260
745
645
933
990
585
468
978
955
776
761
Actual
Age at
Test (days)
7
7
7
7
17
17
11
11
14
14
19
19
30
30
28
28
31
31
34
34
64
64

-------
                                                TABLE 34.  (Cont'd)
1-0
VO

Mix Sample
4C
4D
4E
4F
5G
5H
II 1A
IB
1C
ID
2A
2B
2C
2D
2E
2F
3A
3B
3C
3D
3E
3F
Fly Ash/
as % of
Total
Solids
0.358
0.358
0.358
0.100
0.100
0.100
0.100
0.100
0.100
0.100
0.100
Water/
as % of
Total
Solids
0.445
0.300
0.342
0.300
0.300
0.300
0.300
0.445
0.300
0.300
0.445
Nominal
Curing
Time (days)
60
60
45
7
7
21
21
21
28
28
28
Test
L+CS
L+CS
CS
CS
CS
CS
CS
CS
L+CS
L+CS
CS
CS
L+CS
L+CS
CS
CS
CS
CS
L+CS
L+CS
CS
CS
Date
Cast
11/22
6/11
6/11
8/20
8/20
6/16
6/16
6/17
6/17
6/17
6/17
«_-
12/3
12/3
6/17
6/17
12/3
12/3
12/3
12/3
Compressive
Strength
MPa
6.55
4.69
4.34
7.77
8.32
9.69
9.14
16.20
14.65
6.89
6.12
—
6.03
7.55
8.65
10.00
14.71
15.24
6.33
6.74
psi
950
680
630
1127
1207
1405
1325
2350
2125
1000
888
—
875
1095
1255
1450
2133
2210
918
978
Actual
Age at
(Test (days)
60
66
66
46
46
7
7
7
7
21
21
—
24
24
29
29
28
28
28
28

-------
                                                 TABLE  34.   (Cont'd)
u>
o

Fly Ash/ Water/
as % of as % of
Total Total
Mix Sample Solids Solids
4A 0.100 0.300
4B
4C 0.100 0.300
4D
4E 0.100 0.445
4F
III 1A 0.150 0.300
IB
1C
ID
IE 0.150 0.342
IF
2A 0.150 0.300
2B
1C
2D
3A 0.150 0.300
3B
3C
3D
4A 0.150 0.300
4B
Nominal
Curing
Time (days) Test
60 CS
CS
60 L+CS
L+CS
60 CS
CS
7 CS
CS
L+CS
L+CS
7 CS
CS
21 CS
CS
L+CS
L+CS
28 CS
CS
L+CS
L+CS
60 CS
CS
Date
Cast
6/16
6/16
6/16
6/16
12/3
—
11/8
11/8
—
—
1/6
1/6
10/21
10/21
11/8
11/8
10/21
10/21
—
—
—
—
Compressive
Strength
MPa
10.89
10.98
13.79
12.98
7.44
—
9.48
8.57
—
—
10.24
10.47
11.38
11.00
14.65
14.38
11.46
13.53
—
—
—
—
psi
1580
1593
2000
1883
1079
—
1375
1243
—
—
1485
1518
1650
1595
2125
2085
1663
1963
—
—
__
—
Actual
Age at
Test (days)
61
53
52
52
53
—
7
7
—
—
7
7
20
20
21
21
28
28
—
—
	
__

-------
                                        TABLE 34.  (Cont'd)



Mix




Fly Ash/ Water/
as % of as % of
Total Total
Sample+ Solids Solids
AC
4D
5A 0.15 0.300
5B
Nominal
Curing
Time (days) Test
L+CS
L+CS
14 CS
CS

Pate
Cast
__
—
11/8
11/8
Compressive
Strength
MPa psi
__ 	 	
—
9.96 1445
9.41 1365
Actual
Age at
Test (days)
	 	
—
14
14

NOTES:  1.  CS = compressive strength
            L+CS = specimen was leached as reported elsewhere and then checked for compressive
            strength.
        2.  "Age at  test" means age at the end of the initial curing period, when the specimen was
            either tested for compressive strength or suhjected to leaching.

-------
                                                                              Curve 688036-A
oo
co






psi
1600

1400
^ 1200
"c1
£ 1000
00
1 80°
O)
fe. 600
E
o
o
400
*TwU
200
0
i i i
i i i
Symbol Test Water/Total Solids Curve No.
o CS 0.445
V CS 0.341
a CS 0. 300
A L+CS 0.445
Mix I Used Fly ash/Total Solids


~
A V Curve 2
	 ^^^^-^^^^^BB*^
A .—" 	
/r v § $
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~ / n ^^— — 0- 	
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1
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1
2
Ratio of 0. 358

_

__ v 	
V


6
Curve 1 	 D
	 • 	 u



Portland Cement Concrete
in the Range of
13. 8-^1. 4 M Pa (2000-6000 psi)
i 1 1







MPa
10





c
J






0
                                    10
20       30        40

        Curing Time, days
50
60
70
                 Figure 25.   Compressive Strength  of  5-cm Cubes Cast from Spent Solids from Exxon

                              Run 27 Using Mix I

-------
                                                            Curve 688035-A
•&
c
o>
i_
CO
$
t
o
o
                Symbol    Test    Water/Total Solids
                  a     CS           0.300
                  O     L+CS        0.300
                  o     CS           0.445
                                                       I

                                                Curve No.
                                                   1
                                                   2
                                                   3
                   Mix III Used Fly ash/Total Solids Ratio of 0.100
 psi
2400

2200

2000

1800

1600

1400

1200

1000

 800

 600

 400

 200

   0
                                                                           MPa
                                                                           15
                                                                           10
                                                                    60
                                  Curing Time,  days
 Flgure
                                 Strength  of 5-cm  Cubes Cast  from Spent
                                            ??
                                        133

-------
                                                      Curve 688083-A
£
oo

o>


to
to





psi
2000
1800
1600
1400
1200
1000
800
600
400
200
0
I i i i i
Symbol Test Water/Total Solids
n CS 0. 300
O L+CS 0.300
Mix III Used Fly ash/Total Solids Ratio of 0. 150

-
O
D ^-
^^ n
./^U u
jr D
su
TY n
/
~ /
/
-/
/
»
1
1
1
t
\_
1 1 i i i



MPa
15



10

5


                  10
20        30        40

   Curing Time, days
50
60
   Figure  27.   Compressive Strength  of 5-cm Cubes Cast from  Spent

                Solids from Exxon Run 27 Using >tix III
                                   134

-------
                                                            Curve 688082-A
4/0


OJ
ISl

cu
o
o

psi
2000
1800
1600
1400
1200
1000
800

600
400
200
0
0.
1 r I 	 1 	 — [—
Symbol Fly ash/Total Solids Curing Time days
XT, ^,-Cr 0.358 7-46
n 0. 100 7 - 61
•n- 0. 150 7 - 28
•D-
s*' 	 '">.. Curve 3
^ 	 ^ X\

_ ^
3 / \ Curve 2
• * ^*w
-' ,_„ ^^
y $%. >s
T?" ^*^
D /p ^\. curve 1X>^
n / V ^urve ^


*
/ ^v ^^ ~
1 X
r >
1 i i i i
2 0. 3 0. 4

MPa
15


10



5


0
                              Ratio, Water/Total Solids
       Figure 28.  Effect of Water  Content on Compressive Strength

                    of 5-cn Cubes  Cast from Spent Solids  from

                    Exxon Run 27
                                     135

-------
       TABLE 35.  COMPRESSIVE STRENGTH OF PER SPENT SORBENT MIXES
Composition (g)
PER spent
sorbent
CaO adder
Water
PER-1
1000
—
300
PER- 2
600
300
200
PER- 3
250
500
1000
PER- 4
600
300
500
   Duquesne Fly
   Ash
   Fused Silica
              100
150
Compressive Strength, MPa (psi)
   Curing 4 days   0.034(5)   7.5(1090)   0.33(48)
   Curing 7 days      —        —         —
   Curing 17 days
       0.90, 0.83 (130,120)
       1.07, 1.19 (155,173)

TABLE 36. ESTIMATED COMPOSITION OF PER COMPACTS

Basis
CaO(C)
Si02(S)
A1203
-------
          TABLE 37.  COMPARISON OF COMPOSITION OF PER COMPACTS
                       WITH NORMAL PORTLAND CEMENT

Composition
CaO
Si02
A12°3
Portland
Cement
69.22
27.57
3.21
100.00
PER-1
28.44
51.96
19.60
100.00
PER- 2
63.41
26.57
10.02
100.00
PER- 3
68.80
27.92
3.28
100.00
PER-4
57.45
30.67
11.88
100.00

for the results obtained on PER-1/4.  If constituents are allocated into
compounds found in cement, in PER-1 the alumina content is in excess of
that needed to tie up  the unsulfated CaO as C«A, or (CaO) -Al 0 .   Hence,
no CaO is available  for SiO  or Fe.O .  Since the strength of normal
cement is attributable largely to hydrated calcium silicates, the essen-
tially zero strength of PER-1 is a reasonable expectation.  Also,  look-
ing at the three main  constituents of cement (CaO, Al^, and SiO?), the
as-is composition of the PER stone is definitely outside the Portland
cement area.
     PER-2 was intended to test a mix with the CaO/(CaO + Si02 + A1203)
ratio closer  to 69.22  percent.  This was accomplished by adding fresh
lime to the residue.  Although only 63.4 percent was achieved, the com-
pact showed a substantial compressive strength  (7.5 MPa or 1090 psi) .
     Since alumina in  PER-2 was high, relative  to that in Portland
cement, mix PER-3 included both extra CaO and SiOr  The extra silica
was obtained  by adding commercially available fused silica to the
residue.  Table 37 shows  the composition achieved was very close to
that of Portland cement, but apparently this was not sufficient since
the compressive strength was very  low  (0.33 MPa or 48 psi).  It may be
that pulverized fused  silica is not an effective pozzolan.
                                    137

-------
     PER-4 used Duquesne fly ash from a conventional coal boiler  as  the
silica source, limiting it to 10 percent of the  total solids.   The com-
position was appreciably lower in CaO and higher in Al 0« than  is normal
cement.  Compressive strength was somewhat higher than in PER-3,  sug-
gesting that silica in fly ash is a better pozzolan than ground fused
silica.
     A final conclusion on the free lime content needed was deferred,
but  the tests were considered to show PER stone must be ground.
ASSESSMENT OF UTILIZATION
Preliminary Flow Sheets
     Figure 29 shows a schematic diagram of a flow sheet for spent sor-
bent collection from AFBC.  Although industries such as iron and steel
manufacture practice dumping hot slag, the FBC spent sorbent probably
will have to be cooled as the minimum processing step.   Since heat
recovery of stack gas to combustion air may be utilized, except in
large plants, as shown in a recent PER report,     the heat picked up
from the spent sorbent will probably be discarded.   Since contact with
moisture will initiate pozzolanic reactions, the cooled material is sent
to temporary enclosed storage and then sent via rail car to a processor.
The flow sheet also shows secondary particulate removal, which might  be
a granular bed filter, to take full advantage of advanced technology.
     From this flow sheet other possibilities can be derived.  It may be
economical to add on-site grinding facilities to reduce the spent sor-
bent to -125 mm or possibly -44 mm.  The next stage would be to add
facilities for making aggregate.  Two variations are being examined,
direct casting and isostatic pressing.
Preliminary Economics
     In view of the rising cost of energy,  attention was given to the
possibility of a closer integration of basic industries.  Table 38 shows
figures for the energy consumption in the cement industry.  Combining
                                   138

-------
LO
VO
                                                   Secondary
                                                   Particulate
                                                   Removal
                                                         Air
                                                      Preheater
FBC Cells A,B,C
CBC      D
                                                 Solids
                                                 Cooler
    Dv,r  6404A01

          Stack

135°C
                                                                                               25°C
                                                                                            Spent Sorbent
                                                                                            & Ash Silo
                      Figure 29.   Spent Sorbent and  Fly Ash Collection from Atmospheric-Pressure
                                   Fluidized-Bed Combustion

-------
          TABLE 38.  ENERGY CONSUMPTION OF THE CEMENT INDUSTRY*

Energy Source
Process
Dry Processes
Total annual usage**
Per bbl cement
Per ton cement
Wet Processes
Total annual usage**
Per bbl cement
Per ton cement
Coal, Mg
3.599
0.02311
0.1229
5.036
0.02102
0.1118
Oil
(bbls)
0.775
0.00499
0.0265
4.987
0.02082
0.1107
Gas
(CF)
62,484
402
2140
140,436
586
3118
Electricity
(kWh)
3,948
25.42
135.2
5,621
23.46
124.8

 *Unit quantities based on 155.337 x 10  bbl of cement produced by dry
  processes and 239.572 x 10^ bbl by wet processes.  One barrel of
  cement contains 376 pounds of cement.
**A11 total quantities in millions of indicated units.
Source:  Minerals Yearbook, 1968
the different forms of energy input using 27 x 10  Btu/ton of coal,
6.3 x 10  Btu/bbl oil, 1000 Btu/CF gas, and 10,000 Btu/kWh; the energy
requirement works out to 1,376,000 Btu/bbl cement for dry processes and
                                                     ( 62^
1,423,000 for wet processes.  For comparison, the FEAV  ' has estimated
the average energy requirement at 1,391,000.  The Conference Board^63^
arrived at 1,318,000 for 1967, which has since declined through tech-
nological improvements to 1,218,000 in 1971.  The Board did not include
a breakdown, but the kiln itself may consume 700,000 Btu/bbl for the dry
process, of which 95 percent is required for heating from ambient tem-
perature to 900°C and calcining the CaC03 and MgC03 in the limestone.
Additional heat is required to get to the clinkering temperature of about
2600°F,  but is largely offset by exothermic clinkering reactions.
     Two possibilities for integration with fluid-bed combustion arise.
Close integration would feature transfer of the hot spent sorbent
                                    140

-------
directly to a  cement  process.   The Trief process(64)  probably would be
best suited to utilizing this  approach,  since the charge is  fully melted
rather than merely  clinkered.   Whether the dust problems of  a cement
plant are  compatible  with the  air requirements of a large power plant
needs careful  review.   Alternatively,  the spent sorbent  would be cooled
and shipped to a  cement plant  at another location.   There it  would be
ground to  at least  Ik ym and used as the CaO source.   In this case,
the saving in  energy  for the cement operation is only the calcination
energy, which  is  about 54 percent of the kiln energy  requirement.  If
applied to the entire production of 395  x 10  bbl of  cement,  the saving
amounts to about  65,000 bbl of fuel oil  equivalent  (FOE)/day.  This
does not have  tremendous national significance when compared  to the
daily demand of  17  x  10  bbl of petroleum in the United  States or even
to the heavy fuel oil demand of 2.4 x  10  bbl/day.  Its  importance is,
therefore, indirect,  since cutting the operating costs of  cement manu-
facture would  help  keep down construction costs.  At  378,000 Btu/bbl,
fuel consumption  would be reduced from 0.218 bbl FOE/bbl  cement to
0.158, a reduction  of 27 percent.  With  cement at $4.50/bbl and fuel
oil at $10/bbl,  the fuel cost  represents half the cement price, and the
saving is  about  14  percent.  Equally important factors may be the supply
of limestone of a quality suitable for fluid-bed combustion and the
economics  of transportation.
     Cement production requires about  0.21 Mg of limestone/bbl of cement
or 33 x 106 Mg of limestone/year, which, by  reference to  the  section in
this report on market data,  would correspond to the output of spent
sorbent from about  48-1000 MWe FBC plants using limestone.  The minimum-
sized cement plant  in 1971 appears to  have produced about  1 x 10  bbl/
year, with 16 percent producing over 5 x 10  .   A 3  x  10  bbl  plant
could take the output from a 1000 MWe  power  plant.  Electrical require-
ment would be  76,000  MWh/yr or about 230 MW,  based  on a  330-day operating
year.  So  an interesting possibility is  for  cement  plants  to  generate
their own  electricity via an FBC plant.   A larger plant  could practice
blending of the FBC spent sorbent with fresh limestone if  there were
                                     141

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technical reasons why the spent sorbent could not be used alone.  A
further projection is that, by 1980, 60 percent of the energy requirement
of the cement industry will be coal, with another 8 percent from pur-
chased electricity.  In 1971, coal provided 35 percent and gas 45 percent
of the energy requirement.  Along with the higher consumption of coal
is the higher production of coal ash, a potential source of pozzolan.
A more detailed study of the profitability of the cement business is
needed, however, to clarify the potential FBC market.  The long-term
growth rate has been about 2.8 percent/yr from 1909 to about 1967.
Although this growth rate is expected to slow down, partly because
imports will increase to 50 x 10  bbl/yr, there could be 100 x 10  bbl
of domestic capacity required by 1980.  Demand for hydraulic cement is
expected to increase in this same period at the rate of 3.0 percent/year.
Analysis of Results
     The work described in the foregoing sections has focused on deter-
mining the potential for utilizing FBC spent sorbent and associated fly
ash.  Simple tests have shown that stable, solid compacts can be pro-
duced by grinding the spent sorbent to -125 ym, combining it with coal
fly ash, and adding water.  Compressive strengths are adequate for land-
fill applications and may permit use of the mixes as replacement for
concrete in low-strength fill applications.  The initial work on iso-
static pressing has revealed a potential for use in high-strength
columns and in aggregate.  Although a full demonstration of utilization
is considered outside the scope of the present content, certain addi-
tional laboratory tests are under way to confirm further these poten-
tials.  Included are an examination of the Trief Process     under a
related contract and of resistance to freeze-thaw conditions and to sul-
fate attack.
     Process economics will be checked to identify any additional
information that may be needed to support any recommended processing
sequence.
                                    142

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     From a broader view, the  effect  of  requiring  environmental protec-
tion is expected, in general,  to  increase the cost of  power  generation
and probably the cost of most  industrial operations.   The  pressure of
increasing demand on finite  resources is also strengthening  the case
for conservation.  Power generation has  grown as a separate  entity in
the economy from industrial  production.   Although  plant  expansion can
certainly continue in the historical  pattern, the  work reported here
has shown that potential exists for achieving both environmental protec-
tion and conservation by integrating  power generation  and  cement pro-
duction.  Instead of each drawing upon high-quality limestone reserves,
the limestone could be  used  first in  a fluidized-bed combustor and then
used to make  either a new type of concrete or a new type of  cement.
Even if these new materials  were found not to be as strong or as durable
as  those they might replace, these deviations might merely require modi-
fication of the  design  of the application.
                                    143

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                               SECTION  8
                              REFERENCES

1.  Abelson,  H.  I.,  and W.  A.  Lowenbach,  "Procedures Manual  for Environ-
    mental Assessment of Fluidized-Bed  Combustion  Processes,"  for EPA,
    The Mitre Corporation,  McLean,  VA,  January  1977, EPA-600-7-77-009.
2.  Dorsey, J. A., L. D. Johnson, R.  M. Statnick,  and  C.  H.  Lochmuller,
    "Environmental Assessment  Sampling  and  Analysis:   Phased Approach
    and Techniques  for Level 1,"  Environmental  Protection Agency,
    Office of Research and  Development, Research Triangle Park,  NC,
    June 1977, EPA-600/2-77-115.
3.  Archer, D. H., et al.,  "Evaluation  of the Fluidized Bed  Combustion
    Process," Vols.  I, II,  and III, Final Report to EPA,  Westinghouse
    Research and Development Center,  November 1971, OAP Contract 70-9,
    NTIS PB 211-494, 212-916,  and 213-152.
4.  Coutant,  R.  W.,  J. S. McNulty,  R. E.  Barret, J. J. Carson,  R. Fischer,
    and E. H. Loughner; "Investigation  of the Reactivity  of  Limestone
    and Dolomite for Capturing SO-  from Flue Gas," Battelle  Memorial
    Institute, August 1968.
5.  Ruch, R.  R., H.  J. Gluskoter, N.  F. Shimp,  "Occurrence and Dis-
    tribution of Potentially Volatile Trace Elements in Coal," 1974,
    EPA-650/2-74-054.
6.  Keairns,  D.  L.,  et al., "Evaluation of  the  Pressurized Fluidized-
    Bed Combustion Process  - Pressurized  Fluidized-Bed Combustion
    Process Development and Evaluation,"  Vols.  I and II;  "Pressurized
    Fluidized-Bed Boiler Development  Plant  Design," Vol.  Ill,  Report
    to EPA, Westinghouse Research and Development  Center, Pittsburgh,
    Pa., December 1973, EPA 650/2-73-048  a, b,  and c,  NTIS Num-
    bers 231-162, 231-163,  232-433.
                                  144

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 7.   Zielke, C. W., H. E. Lebowitz, R. T.  Struck, E. Gorin, "Sulfur
     Removal During Combustion of Solid Fuels  in a Fluidized Bed of
     Dolomite," J. Air Pollution Control Association, _20  (3), 165 (1970).
 8.   "Proposed EPA Effluent Guidelines for Steam Electric Power Gener-
     ating" Federal Register 39 FR 8294, March 4, 1974, Environmental
     Reporter, March 8, 1974, p. 1869.
 9.   "Corps Regulation Cover Sanitary Landfill in Navigable Water,"
     Solid Waste Report. August 4, 1975, p. 153.
10.   "Permits for Activities in Navigable Waters or Ocean Waters,"
     Federal Register, 40 FR 31321, July 25, 1975.
11.   "Environmental Protection Agency Regulations on State Program
     Elements Necessary for the Participation  in the National Pollutant
     Discharge Elimination System," Federal Register, 37 FR 28390,
     Dec. 22, 1972; 41 FR 11303 & 11458, March 18, 1976, Environmental
     Reporter, May 14, 1976.
12.   "Environmental Protection Agency Regulations on Policies and Pro-
     cedures for the National Pollutant Discharge Elimination System,"
     Federal Register, 38 FR 13527, May 22, 1973; 40 FR 29848,
     July 16, 1975; FR 11303 & 11458, March 18, 1976, Environmental
     Reporter, April 30, 1976, p. 31.
13.   "Environmental Protection Agency-Guidelines for the Thermal Proc-
     essing of Solid Wastes and for the Land Disposal of Solid Wastes,"
     Federal Register, 39 FR 29328, Aug. 14, 1974; 40 FR 5159,
     Feb. 4, 1975, Environmental Reporter, Feb. 28, 1975.
14.   "Environmental Protection Agency-Solid Waste Management Guidelines,"
     Federal Register, 41 FR 2359, Jan. 15, 1976.
15.   "Federal Water Pollution Act," Environmental Reporter, Feb. 28, 1975.
16.   "Environmental Protection Agency National Interim Primary Drinking
     Water Regulations," Federal Jtegister, *0 FR 59565, Dec. 24, 1975,
     Environmental Reporter, Feb. 13, 1976, p. 81.
                                   145

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17.  "U.S. Drinking Water Standards 1962," U.S. Public Health Service
     Publication No. 956, 1962.
18.  Lund, H. F., Industrial Pollution Control Handbook, New York:
     McGraw-Hill Book Co., 1971.
19.  Water Quality Criteria, Ecological Research Series, EPA-R3/73-033,
     March 1973.
20.  Schomaker, N. B., "Current EPA Research Activities in Solid Waste
     Management," Gas and Leachate from Landfills, March 1976, EPA-600/
     9-76-004, NTIS PB 251-161.
21.  Schomaker, N. B., "Current Research on Land Disposal of Hazardous
     Wastes," paper presented at Hazardous Waste Research Symposium,
     Tucson, AR, Feb. 2-4, 1976.
22.  "Development of Construction and Use Criteria for Sanitary Landfill,"
     County of Los Angeles,  1973, EPA-SW-19D-73, NTIS PB 218-672.
23.  Qasim, S. R., "Chemical Characteristics of Seepage Water from
     Simulated Landfills," Ph.D. Dissertation,  West Virginia University,
     Morgantown, WV, 1965.
24.  Fungaroli, A. A., "Pollution of Surface Water by Sanitary Landfills,"
     1971, NTIS PB 209-001.
25.  DeGeare, Jr., T. V., "Current Office of Solid Waste Management
     Programs-Landfill Activities," Gas and Leachate from Landfills,
     1976, EPA-600/9-76-004,  NTIS PB 251-161.
26.  Jones, J. W., "Research and Development for Control of  Waste  and
     Water Pollution from Flue Gas Cleaning System," paper presented
     at the EPA Symposium on Flue Gas Desulfurization,  New Orleans, LA,
     March 8-11, 1976.
27.  Mahloch, J. L.  and D. E.  Averett,  "Pollutant Potential  of Raw and
     Chemically Fixed Hazardous Industrial Wastes and Flue Gas Desulfur-
     ization Sludges," U.S.  Army Engineer,  Interim Report to EPA
     January 1975,  Interagency Agreement  EPA-IAG-D4-0569.
                                   146

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                                   in
28.  Radian Corporation,  "The  Environmental  Effects  of  Trace  Elements i
     the Pond Disposal of Ash  and  Flue  Gas Desulfurization Sludge,"
     Final Report to EPRI, EPRI-202,  September  1975, NTIS PB  252-090.
29.  Fling, R. B., W. M.  Graven, F. D.  Hess, P.  P. Leo, R. C. Rossi,
     and R. Rossoff, "Disposal of  Flue  Gas Cleaning Wastes-EPA Shawnee
     Field Evaluation," The  Aerospace Corporation, March 1976,
     EPA/600/2-76-070.
30.  "Pressurized Fluidized  Bed Combustion," Report to Office of Coal
     Research, National Research and  Development Corporation, November
     1973, Contract No. 14-32-0001-1511.
31.  Pope Evans and Robbins, Inc., "Multicell Fluidized Bed Boiler Design
     Construction and Test Program,"  Interim Report No. 1 to Office of
     Coal Research, August 1974, Report PER-570-74, Contract
     No. 14-32-0001-1237.
32.  Vogel, G. J., Jonke, A. A., et al., "Reduction of Atmospheric Pol-
     lution by the Application of Fluidized Bed Combustion  and Regenera-
     tion of Sulfur-Containing Additives," Report to EPA, Argonne
     National Laboratories, Argonne,  111, June 1973,  EPA R2-73-253.
33.  Henschel, D. B. , "The U.S. Environmental Protection Agency Program
     for Environmental Characterization of Fluidized  Bed Combustion
     Systems," Proceedings of  the Fourth International  Conference  on
     Fluidized Bed Combustion,  McLean, VA., Dec. 9-11,  1975.
34.  Ralph Stone and Company,  "Environmental Assesment  of Residues from
     the Fluidized Bed Combustion of  Coal and Gasification  of  High
     Sulfur Fuel Oils," Report  to EPA, 1976,  EPA Contract No.  68-03-2347.
35.  Tennessee Valley Authority, "Processing Sludges  From Lime/Limestone
     Wet Scrubbing Processes for Disposal or Recycle  and Studying
     Disposal of Fluidized Bed  Combustion Waste Products,"  1976, Inter-
     agency Agreement TV-41967A, EPA-IAG-D5-0721, Subagreement No.  17,
     E-AP No. 77BBA.
147

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36.  Keairns, D. L.,  et al.,  "Fluldized Bed Combustion Process Evalua-
     tion, Phase II-Pressurized Fluidized Bed Coal Combustion Develop-
     ment," Report to EPA,  Westinghouse Research and Development Center,
     September 1975,  EPA-650/2-75-027c, NTIS PB 246-116.
37.  Keairns, D. L.,  Peterson,  C.  H.,  and Sun,  C.  C.,  "Disposition of
     Spent Calcium-Based Sorbents  Used for Sulfur  Removal  in Fossil fuel
     Sasification," paper presented at the 69th Annual Meeting,  AIChE,
     Nov. 28-Dec. 2,  1976.
38.  Hoke, R. C., et  al., "Studies of  the Pressurized  Fluidized-Bed Coal
     Combustion Process," Report to EPA, Exxon  Research and Engineering,
     Linden, NJ, September 1976, EPA-600/7-76-011.
39.  Gruenfeld, M., Private Communication, Industrial  Environmental
     Research Laboratory, EPA,  Edison, NJ, 08817.
40.  Henschel, D. B., Private Communication,  Industrial Environmental
     Laboratory, EPA, Research Triangle Park, NC 27711.
41.  Meritt, G. H., Private Communication, Commonwealth of Pennsylvania
     Solid Waste Management,  Harrisburg, PA.
42.  Duritsa, C. A.,  Private  Communication,  Commonwealth of Pennsylvania
     Department of Environmental Resources,  Pittsburgh, PA.  15222.
43.  Bern, J., "Probable Environmental Impacts  from the Disposal of
     Sulfur Removal Sludges Generated  by the Slaked Lime-Wet Scrubber
     Process," Commonwealth of Pennsylvania Department of  Environmental
     Resources, Division of Solid Waste Management, Pittsburgh,  PA.,
     March 1974.
44.  Weeter, D. W., J. E. Niece, and A. M. DiGioia, Jr., "Environmental
     Management of Residues from Fossil Fuel Fired Power Stations," paper
     presented at Annual Water Pollution Control Federation Conference,
     Denver, CO, Oct. 8, 1974.
                                   148

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45.  Standard Methods  for  the  Examination  of Water  and Wastewater,
     13th Ed., American  Public Health Association,  1974.
46.  Boynton, B.  S.,  Chemistry and Technolggy  of Lime and Limestone,
     New York:   Interscience Publishers,  1966.
47.  "Physical  Testing of Quicklime, Hydrated  Lime  and Limestone,"
     ASTMC110-76.  1976 Annual Book of ASTM Standards Part  B, p.  68-85.
48.  Murray,  J.  A., et al., "Shrinkage of High-Calcium Limestone  during
     Burning,"  J. Am. Ceram. Soc. 37, 7 (1954) p. 323-328.
49.  Lewis, J.  R. , "Cement," Minerals Yearbook, 1968.  Bureau of  Mines,
     U.S.  Department of the Interior.
 50.   Griffin, R. A., and N. F. Shimp, "Interaction of Clay Minerals  and
      Pollutants  in Municipal Leachate," Illinois Geological Survey,
      Urbana, IL, Proceedings of  the Second National Conference  on Com-
      plete Water Reuse, 1975,  pp. 801-811.
 51.   ASTM Annual Book of  Standards, Part  10,  "Concrete  and Mineral
      Aggregates,"  1973, American Society  of Testing and Materials,
      Philadelphia, PA.
 52.  ACI Manual  of Concrete Practice, Parts 1 and  2.  American  Concrete
      Institute,  Detroit,  MI,  1968.
 53.  ASTM  Annual Book of  Standards,  Part  9, "Cement, Lime, and  Gypsum,"
      1973, American  Society of Testing and Materials, Philadelphia, PA.
 54   Smith,  L.  M., et al.. "Technology for Using Sulfate Waste in High-
      way Construction," Federal Highway Administration, Gllette Research
      institute, Rockville, MD., December  1975, FHWA-RD-76-31, NTIS
      PB 254-815.
 55   Peterson,  C. H. and H. Gunasekaran,  "Utilisation of  Spent Limestone
      from a Fluidized Bed Oil Gasification/Desulfurization Process  in
      Concrete," Proceedings of the Fifth Mineral Waste  Utilisation
      Symposium, IIT Research  Institute,  Chicago, IL, April 1976.
                                     149

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56.  Dunstan,  E.  R.  Jr,  "Performance of Lignite and Subbituminous
     Fly Ash in Concrete;  A Progress Report," Bureau of Reclamation,
     Denver, CO,  January 1976,  REC-ERC-76-1,  NTIS  PB 253-010.
57.  Backstrom, J.  E.,  "Investigation into the Effect of Water - Cement
     Ratio on the Freezing - Thawing Resistance of Non-Air and Air-
     Entrained Concrete,"  Bureau of Reclamation, Denver, CO, Novem-
     ber 1955, Concrete Laboratory Report No.  C-810.
58.  Cordon, W. A.,  "Freezing and Thawing of  Concrete - Mechanisms and
     Control,  "ACI Monograph No. 3, American  Concrete Institute, Detroit,
     Michigan, 1966.
59.  "Solid Waste Disposal Act," Environmental Reporter, Feb.  28,  1975.
60.  Brown, P. W.,  et al., "Energy Conservation through the Facilitation
     of Increased Blended  Cement Use," Prepared for ERDA,  Institute for
     Applied Technology, National Bureau of Standards,  Washington, D.C.,
     Interim Report July 1-Dec. 1, 1975,  NBSIR 76-1008,  NTIS PB 251-218.
61.  Hoke, R.  C., et al.,  "Studies of the Pressurized Fluidized-Bed Coal
     Combustion Process,"  Report to EPA,  Exxon Research and Engineering
     Company,  Linden, NJ,  September 1977,  EPA-600/7-77-107.
62.  Energy Conservation Potential in the Cement Industry,  FEA Conserva-
     tion Paper No.  26,  1975.
63.  Energy Consumption in Manufacturing,  The Conference Board, Cam-
     bridge, MA.:  Ballinger Publishing Co.,  1974.
64.  "New Cement Uses Fly  Ash,  Costs Less to  Make," Chemical and
     Engineering News,  April 5, 1976.
65.  Newby, R. A.,  and D.  L. Keairns, "Alternatives to Calcium-Based
     S0_ Sorbents for Fluidized-Bed Combustion: Conceptual Evaluation,"
     Report to EPA,  Westinghouse Research and Development Center,
     Pittsburgh,  Pa., January 1978, EPA-600/7-78-005.
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66.  Newby, R. A. S. Katta,  and D. L. Keairns, "Calcium-Based Sorbent
     Regeneration for Fluidized-Bed  Combustion:  Engineering Evaluation,"
     Report to EPA, Westinghouse  Research  and Development Center,
     Pittsburgh, Pa., March  1978,  EPA-600/7-78-039.
67.  Alvin, M. A., E. P.  O'Neill,  L. N.  Yannopoulos, and D. L. Keairns,
     "Evaluation of  Trace Element Release  from Fluidized-Bed Combustion
     Systems," Report to  EPA,  Westinghouse Research and Development
     Center,  March  1978,  EPA-600/7-78-050.
                                     151

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76184
                             APPENDIX A
             THE FEASIBILITY OF OCEAN DUMPING
                AS AN INTERIM ALTERNATIVE TO
                   DISPOSAL OF SPENT STONE
                   FROM THE FLUIDIZED BED
                      COMBUSTION PROCESS
                            20 September 1976
          Report To:  WESTINGHOUSE ELECTRIC CORPORATION
                   Research and Development Center
                   Churchill, Pennsylvania        *
              By:   J. M. Forns
                   WESTINGHOUSE OCEANIC DIVISION
                   Ocean Research Laboratory
                   Annapolis, Maryland  21404
                           152

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INTRODUCTION

      The oceans cover  more than 70% of the earth's surface, incorporating approximately 140
million square m.les with an average depth of more than 12,000 feet. They are critical in maintaining
the world s environment,  contributing to the oxygen-carbon dioxide balances in the atmosphere
affecting global climatology, and providing the  base for the world's hydrologic system Oceans are
economically valuable to man in providing necessary food and mineral resources In addition they are
a medium of transportation and recreation to more than 60% of the Nation's population The
continental margins of the world's oceans are the most important individual environmental areas from
the standpoint  of gross organic production. According to Odum (1959), estuaries and coastal oceans
contribute more than 58% of the total primary caloric carbon energy for the entire planet. Any serious
detrimental impacts on  these marine systems could have far-reaching  effects on  our global
environment in years ahead.

       While  our coastal oceans are biologically  diverse, extending from tropical  to  arctic
environments,  they  are also the ultimate  receptacle  for many  of our wastes. Sewage, chemicals,
construction debris, and many other waste materials are transported to the ocean by riverine systems
or directly by barges, ships, and pipelines. Although the amount of waste presently dumped directly
into the ocean  is small compared to the total amount of wastes reaching the oceans, in the future the
impact of ocean dumping, as a means of waste disposal, will increase significantly relative to that of
other sources. Cognizant of this, the Council on  Environmental  Quality prepared in  1970  a
formulation and recommendation for a national policy concerning ocean dumping. They concluded
that the problem was growing rapidly and that in many  cases, feasible and economic alternative
methods were available for disposal of wastes currently being dumped at sea. They also realized that
certain ocean dumping practices did not have immediate or viable alternatives and recognized that
there was no regulatory authority controlling ocean dumping as the jurisdictions of individual State
and the Army Corps of Engineers extended only within the three-mile territorial sea. Their report also
 pointed out the international implications of ocean dumping off the U.S. continental margins.

       The purpose of the following report is to describe the present national position with regard to
 ocean dumping and identify the mechanisms and procedures of ocean disposal as it applies to the spent
 stone wastes from the fluidized bed combustion process. In no way is there any intention to predict
future government policy concerning ocean dumping. The material in this report has been gathered
and organized  solely to present the established governmental criteria and evaluation process by which
 the federally designated ocean dumping permit system operates. The determination of ocean disposal
 feasibility is based on presently enacted legislation and existing precedents. Included in this report are
 specific sections dealing the the federal regulations, criteria and evaluation process, identification of
 approved sites for ocean disposal, the mechanisms to  carry out an ocean dumping program, and the
 feasibility of dumping spent stone wastes at established ocean dumpsites.
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FEDERAL REGULATIONS AND PERMIT PROCEDURES

      Since  1970, two  significant pieces of federal legislation have been enacted to establish a
mechanism for evaluation and control of ocean dumping. The first passed in  1972, is known as the
Marine Protection. Research and Sanctuaries Act (M PRSA) (Appendix A). This pulblic law (92-532)
enables Congress to establish a national policy on ocean dumping and to regulate the dumping of all
types of materials into the oceans. It also establishes a system to prevent or strictly limit the ocean
disposal of any materials which  would adversely affect human health and the marine environment.
ecological systems, or economic potentialities. This Act became effective April 23, 1973, and since that
time, all ocean  dumping of  waste materials has been done under a permit from EPA, except for
dredged spoils which are regulated by  the Corps of Engineers.

      When  the ocean dumping program was first initiated, many procedural and technical decisions
were encountered resulting in the development by EPA of Final Regulations and Criteria (Appendix
B) to be included in the MPRSA. These Final Regulations governing ocean dumping were published
in the  Federal  Register, October 15,  1973, and constitute the  legal requirements  which  must be
followed by anyone using the oceans for waste disposal. The combination of Title I of the MPRSA and
the Final  Regulations put out by EPA establish a permit granting procedure to utilize designated
ocean dumpsites  for five categories including industrial wastes, sewage sludge, construction and
demolition debris, solid wastes,  and explosives. Presently, of the total 281 available disposal areas,
eleven ocean dumping sites in the Atlantic Ocean and Gulf of Mexico are now in active use for disposal
of municipal and industrial wastes. There is no dumping of these wastes in the Pacific Ocean, although
sewage sludge is currently being discharged via several outfalls.

      Since the legislation was established ocean dumping activity showed a net increase of about 1.6
million tons from  1973 to 1974, primarily because of a 1.1 million ton increase in construction and
demolition debris. While figures  are not yet available, EPA expected to reduce this volume somewhat
because alternative methods of disposal are being developed and implemented. According to EPA
(1975), the major problem in the future with regard to ocean dumping is the anticipation of increased
pressures  to  dispose of wastes  at sea  resulting from more and better  waste treatment  facilities
removing increased amounts of wastes  from both municipal and industrial sources. Clearly, the
understanding and technology required to deal with waste disposal has not kept pace with population
growth. EPA's basic approach has been to find and use the least environmentally damaging site and
methodology of waste disposal whether it be via air, land, or water.

       The basis for regulation of ocean dumping is given in the form of criteria which reguire EPA to
balance several factors before determining whether or not to issue a dumping  permit. These factors,
which are the essence of the federal regulation on  ocean dumping, include:
        I.  The need for the proposed dumping in the ocean, as determined by EPA.
        2.  The effect of dumping on the marine environment.
        3.  Social and economic considerations involving the dumping, including effects on human
           health and welfare, fishery, and  recreational resources.
        4.  Alternative means of disposal,  including alternate methods of treatment, land-based
           disposal and recycling.
        5.  The feasibility of dumping beyond the continental shelf.


                                            154

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       Upon consideration  of these factors, EPA,  through the regional  offices, will  cons.der
application for a permit for ocean dumping. Schematically, Figures 1  and 2 show the procedural
sequence ,n obtaining dumping permits. In Figure 1  the procedure covers the applicat.on process
where waste d.sposal takes place within a  single EPA region's jurisdiction.  Figure 2 describes the
application procedure for inter-regional permits.

       One important aspect of the Federal  Regulations and Criteria is contained in Section 220 3 (d)
(2). This specifies that an "interim permit will reguire the development and active implementation of a
plan to either eliminate...or bring it within limitations of...the ocean dumping criteria". While interim
permits may not be renewed, new  interim permits  may be granted provided that the  permitee
completes  the sequence of phases required to meet ocean dumping criteria. By this mechanism EPA
intends to  limit the use of ocean dumpsites wherever  possible and allow ocean disposal only when
materials dumped fall within the criteria identified.

       On  Monday, June 28, 1976 EPA published in the federal  register a "Proposed Revision of
 Regulations and Criteria" on Ocean  Dumping (Appendix C). These proposed revisions, if and when
 promulgated, would affect both the  procedures to be followed in reviewing applications for ocean
 dumping and the substantive criteria to be applied in evaluating those applications.

       Several aspects of these revisions would directly affect the feasibility of the disposal of spent
 stone by ocean dumping.  Following is summary of those salient  aspects of the proposed revisions.

       Section 102 of the Act requires that criteria for the issuance of ocean disposal permits be
 promulgated after consideration of the environmental effect of the proposed dumping operation, the
 need for ocean dumping, alternatives to ocean dumping, and the effect of the proposed action on
 esthetic, recreational and  economic  values and on other uses of the ocean.  Parts 227, 228 of the
 proposed revisions constitute the criteria established pursuant to Section  102 of the Act. The decision
 of the Administrator,  Regional Administrator or the District Engineer, to issue or deny a permit and
 to impose specific conditions on any permit issued with be based on an evaluation of the permit
 application pursuant to these criteria. Following is a summary of those criteria which apply to the
 ocean disposal of spent stone from the fluidized bed combustion process.

       Section 227 states that if an applicant can satisfy the following conditions, a permit will be
 granted. First, the applicant must satisfy the environmental impact criteria of sub-part B. Several of
 these criteria apply to spent stone. Section 227.7 (d) states that in the dumping of wastes of highly
 acidic or alkaline nature consideration  shall be given to: 1) the effects of any change in acidity or
 alkalinity  of the  water  at the  disposal  site; and  2) the potential for synergistic effects or for the
 formation of toxic compounds at or near the disposal site. It further states that allowance may be made
 in the permit  conditions for the capability of ocean  waters to neutralize acid or alkaline wastes;
 provided  however the dumping conditions must be such  that the average total alkalinity or total
 acidity of the ocean water after allowance for initial mixing, may be changed, based on stoichiometnc
 calculations by no more than 10 percent during all dumping operations at a site. A definition of initial
 mixing is  given in Section 227.29 of subpart as that dispersion or diffusion of a waste which occurs
 within four hours after dumping. In addition, several methods are listed which can be used to estimate
 this.
                                             155

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                             APPLICATION
                             SUBMITTED
                             TO REGIONS


PRELIMINARY
EVALUATION
OF APPLICATION
                            PUBLIC NOTICE
                           WITH TENTATIVE
                              DECISION
                                                          TENTATIVE
                                                          DECISION
                                                          TO DENY
                            REQUEST FOR
                              HEARING
                           PUBLIC HEARING
                          FINAL EVALUATION
                           OF APPLICATION
                                                         DENIAL OF
                                                          PERMIT
COAST GUARD
SURVEILLANCE
                                                        ENFORCEMENT
                                                           ACTION
MONITORING OF
             Figure 1.  EPA Regional Permit Application Procedure

                               156

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                   APPLICATION SUBMITTED TO
                       INITIATING REGION
                    TECHNICAL EVALUATION
                   OF NEED AND ALTERNATIVES
                     BY INITIATING REGION
                  INITIATING REGION FORWARDS
             APPLICATION AND TECHNICAL EVALUATIONS
                  WITH RECOMMENDATIONS FOR
                 ISSUANCE OR DENIAL OF PERMIT
                    SITE REGION EVALUATES
                 IMPACT OF PROPOSED DUMPING
                           ON SITE
                     DISPOSAL SITE REGION
                  FORWARDS APPLICATION WITH
                    IMPACT EVALUATION WITH
                    RECOMMENDATIONS FOR
                 ISSUANCE OR DENIAL OF PERMIT
                      TO HEADQUARTERS
              HEADQUARTERS REVIEWS INFORMATION
                FROM BOTH REGIONS AND MAK^S
                   TENTATIVE DETERMINATIONS
               FOR ISSUANCE OR DENIAL OF PERMIT
                   PUBLIC NOTICE IS GIVEN IN
                BOTH REGIONS WITH OPPORTUNITY
                 FOR HEARING IN BOTH REGIONS
                RECOMMENDATIONS FORWARDED
                      TO ADMINISTRATOR
                FINAL ACTION BY ADMINISTRATOR
Figure 2.  Permit Procedure for Interregional Application
                  for Ocean Dumping

                         157

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       Section  227.7 (c) states that wastes containing biodegradable constituents, or constituents
which consume oxygen in any fashion, may be dumped in the ocean only under conditions in which the
dissolved  oxygen after allowance for initial mixing will  not be depressed by more than 25 percent
below  the normally anticipated ambient conditions in the disposal area at the time of dumping.

        Section 227.8 states that no wastes will be deemed acceptable for dumping unless they can be
dumped so as not to exceed the "limiting permissible concentrations." This is defined in Section 227.27
as:

        1) "that concentration of a material or chemical constituent in the receiving water
        which, after reasonable allowance for initial mixing, will not exceed  a toxicity
        threshold defined as 0.01 of a concentration shown to be toxic to appropriate sen-
        sititve marine organisms in a bioassay carried out in accordance with approved EPA
        procedures; or 2) 0.01 of a concentration of a waste material or chemical constituent
        otherwise shown to be detrimental to the marine environment."

In section 227.27 (b) a definition of "appropriate sensitive marine organisms", and the necessary
experimental conditions and procedures for an acceptable bioassay are given.

       Section  227.9 states that the quantity of the substance dumped at any single time and place
must be controlled to prevent damage to the environment or to amenities.

       After satisfying the environmental impact criteria,  the applicant must secondly demonstrate a
need for ocean dumping. The specific detailed factors which will be considered in determining if there
is a need for ocean disposal of a material are given insubpart C (sections 227.14 - 227.16). The degree of
treatment feasible for the waste and to what extent this  will be carried out will be considered. The
process by which the waste is generated will be  examined to see  if this process is essential to the
provision of the applicants goods or services or to see if less polluting materials could be used. A
consideration will  be made of the relative environmental impact and cost for ocean dumping as
opposed to  other feasible alternatives including,  but  not  limited to: land fill; well  injection;
incineration;  spread of material over open ground;  recycling of material for reuse; additional
biological, chemical or physical treatment of intermediate or final waste streams; and storage. At the
same time, a consideration of any irreversible  or irretrievable consequences  of the use of the
alternatives to ocean disposal will be made. It must be determined after these considerations that there
are no  practicable alternative locations and  methods of disposal (i.e., which are available at reasonable
incremental cost and energy expenditures, which need not be competitive with  the costs of ocean
dumping, taking into account the environmental benefits  derived from such activity) or recycling
available which would  be less detrimental.

       In  addition, the administrator may, at his discretion, grant the permit with other terms and
conditions. He may require that the permittee  terminate all ocean dumping by a specified date, or
continue research and development  of alternative methods of disposal and make  periodic reports of
such research and development in order to provide additional information for periodic review of the
need for an alternative to ocean dumping.
                                             158

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      The third major requirement is that there can be no unacceptable adverse effects on esthetic
recreational, or economic values of the ocean. The criteria used for making a judgement of this are
given in subpart D (section 227.17 - 227.19).

      In  section  227.18 it is stated  that the  following factors  will be considered in making a
determination  of this impact: present recreational  and commercial use of areas which might be
affected by the proposed dumping; existing  water quality and disposal activities in the areas which
might be affected: applicable water quality standards; visible characteristics of the materials which
result in an unacceptable esthetic nuisance in  recreational areas; presence in material of toxic chemical
substances released  in volumes which might affect  humans directly; bioaccumulative or persistent
chemical constituents which may affect humans adversely directly or through food chain interractions;
and constituents in the material which might significantly affect living marine resources of recreational
or commercial value.

       A  fourth condition upon which being granted a dumping permit is contingent is that the
proposed dumping will not have an unacceptable  adverse effect on "other uses" of the ocean. These
uses, listed in  section 227.21 of subpart E, are  as follows: commercial and recreational fishing;
commercial and recreational navigation; actual oranticipated exploitation of living marine resources
as well as  non-living resources  such as mineral deposits, oil and gas exploration and development,
future offshore marine terminal or other structure development; and possible scientific research and
study. The assessment of impact on other uses of the ocean will consider both temporary and long-
range effects within the state-of-the-art,  but  particular emphasis will be placed on any irreversible or
irretrievable commitment of resources that would result from the proposed dumping.

       If, in fact, all the criteria presented under the above four broad headings are satisfied, a permit
for ocean  disposal can be issued.

       Permits are of different kinds. Section 220.3 liss them and describes each. A "general permit"
 may be issued  for dumping certain materials which will have minimal adverse environmental impact
 and are  generally disposed of in small  quantities, or for specific  classes of materials that must be
 disposed  of in emergency situations. They may be issued with or without application whenever the
 Administrator determines that is is necessary or appropriate.

       A second kind of permit is a "special  permit" which may be issued for materials which satisfy
 those criteria discussed above. They are issued with an expiration date no later than three years from
 the date of issue.

       A third kind of permit, an "interim permit" is described in section 220.3 as one which may be
 issued under certain conditions in accordance with subpart A of part 227 to dump materials which are
 not in compliance with the environmental impact criteria of subpart B of part 227, or subnarts Dor E
 orforwhichan ocean disposal site has not been designated on other than an interim basis.  Subpart
 A says essentially that interim permits will be granted when it is determined  that even though all the
 criteria are  not satisfied, the need for  dumping and unavailability  of alternatives  are of greater
 significance to public interest than the potential for adverse effects on any aspect of the ocean. An
 interim permit is not valid for  more than one year and requires substantial efforts by the  perm.t
 5™nuo bring the waste within the limitations required of a special permit or to take the necessary
                                              159

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measures to cease ocean dumping. A limitation, though, found in the description of interim permits in
section 220.3 may make an interim permit unattainable for spent stone. It states that no interim permit
will be granted for the dumping of waste from a facility which has not previously dumped wastes in the
ocean, from a new facility, or from the expansion or modification of an existing facility, after the
effective date of these regulations.

       Part 228 is an altogether new addition to the existing regulations with no counterpart in them.
It serves to establish the criteria for the management of ocean disposal sites by EPA, and presents
criteria  for the selection of  sites, and factors which must  be considered with  respect  to the
determination of the permissible levels of disposal of materials at a particular site. It states the belief
that permit issuance should not be based solely on the testing of waste, but that the specific marine
environment must be considered. In addition, limitations are placed on the times and rates of disposal
of materials (sec. 228.7) and an appropriate monitoring program is made (228.9). It is stated in this
section  that  EPA will require  the full participation of the permittee in  the development  and
implementation of the monitoring program. Section 228.12 lists sites which will, beginning on the
effective date of these regulations, be approved for dumping certain materials therein indicated on an
interim basis  pending completion  of baseline or trend  assessment surveys and designation for
continuing use or termination of use.
                                            160

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APPROVED SITES FOR OCEAN DUMPING.

       Prior to the enactment of MPRSA in 1973, a total of 281 disposal areas were known to exist
within the estuaries and coastal oceans of the United States. Figure 3 shows these disposal sites in the
Atlantic, Pacific, and Gulf of Mexico. From Table 1 more than half the ocean disposal sites were used
by the Army Corps for dredge spoil disposal. The second largest use of ocean dumping by location was
for industrial wastes constituting 13.7% of the total number of dumpsites available. It is the location of
these dumpsites that is  of concern when considering the spent stone wastes from the  fluidized bed
combustion process. These industrial disposal areas are located between 15 and 100 miles offshore
depending on the type of waste and established regulatory procedure. For examr/.e, acid wastes from
the New York metropolitan area are dumped in a designated zone 15 miles from New York City while
certain chemically toxic materials must be disposed of at distances more than 125 miles offshore. Most
of the industrial disposal in the Gulf of Mexico is conducted beyond the 400-fathom contour, which in
the case of Galveston, Texas, requires a transport  of more than  125 miles one way.

       By contrast sewage sludge disposal sites account for a mere 0.6% of the approved dumpsites
and are all within 50 miles of shore.  However, when comparing the total tonnage (Table 2) of ocean
dumped municipal and industrial wastes, sewage sludge comprises greater than 50% of the amount of
waste disposed at sea. It is interesting to note that these wastes do not meet the criteria identified in the
 Final Regulations and  yet additional interim permits have been issued.

       It  is important to note that only 11  of the  42 municipal and industrial dumpsites from the
 Atlantic and  Gulf regions are considered active by EPA. This is primarily  because most industrial
 dumpers have found alternatives to ocean dumping or the costs of disposal and subsequent monitoring
 have become uneconomic. While the remaining 31 sites are presently on the inactive list, they could be
 utilized once again.  For such a case, it would have to be determined by EPA  that the proposed ocean
 dumping constitutes the  least  deleterious environmental impact, does not  infringe on other socio-
 economic potentials and the wastes to be dispossed have no other feasible alternative. If, however, the
 wastes meet the criteria specified in the Final Regulations, then an interim permit could be given which
 would be subject to review before continuance. The review cycle is presently on an annual basis. At
 each review the permitee would have to state the plan and  phases for alternatives to ocean disposal,
 show the results of monitoring  effects and provide quantitative environmental information to
 substantiate the case for ocean dumping.
                                              161

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              LEGEND

     D DRfDGE SPOILS
     I  INDUSTRIAL WASTES
     S S!WAGE SLUDGE
     £ F XPl OSWES
     R KOOIOACTIVE WASTES
     W ^01 ID WASTE
     X INACTIVE SITE
     N^—•->*•  • — ,j,   w i  :  •
    »   / ^-^vZ  «\—W
    ^ R     r"—:^F~— E' •'
>    .  ;       .^•-.7=v-
                \
           — i    w
X t
           Pacific
 ~t
     T    EX
                              VT-" \   : 1
                              C, 0    )
                                    '     "
                            Atlantic
                                                I <   ',1    —-i— , > . .
                                                     V. . i  •• •*
                              Gulf
   Figure 3.  Ocean Disposal Areas Along the U.S. Continental Margins

                                  162

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                       Table 1.  Ocean Waste Disposal Areas (By Region and Waste Type)"

WASTE TYPE
Dredge spoil
Industrial waste
Sewage sludge***
Refuse
Radioactive waste
Explosive and chemical ammunition
TOTAL
(no duplicates)
DISPOSAL AREAS
PACIFIC
15
9**
0
3**
10**
19**
54

ATLANTIC
83**
15**
2
0
25**
19**
135

GULF
63
16
0
0
2
11
92

TOTAL
161
40
2
3
37
49
281

  * Revised and updated by James L Verber, Food and Drug Administration, U.S. Apartment of Health, Education,
    and Welfare.
 ** Areas used for two or more types of wastes.
*** Does not include outfalls

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                                Table 2. Ocean Disposal:  Types and Amounts, 1974* and 1973**
                                                   (In Tons, Approx.)

WASTE TYPE
Industrial Waste
Sewage Sludge
Construction &
Demolition
Debris
Solid Waste
Explosives
TOTAL
ATLANTIC
1974
4,767,000
5,676,000
2,242,000


0
0
12,685,000
1973
3,997,100
5,429,400
1,161,000


0
0
10,587,500
GULF
1974
950,000
0
0


0
0
950,000
1973
1,408,000
0
0


0
0
1,408,000
PACIFIC
1974
0
0
0


200
0
200
1973
0
0
0


240
0
240
TOTAL
1974
5,717,000
5,676,000
2,242,000


200
0
13,635,200
1973
5,405,100
5,429,400
1,161,000


240
0
1 1,995,740
 *1974 Source   EPA Regional Offices. Unpublished Reports, updated information, 1974 (12 months of dumping activity).
**1973 Source - EPA Regional Offices.Unpublished Reports, 1973 (8 months of dumping activity  May to December 1973 under
  permits issued by Ocean Disposal Program extrapolated for 12 months to provide an annual rate).

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OCEAN DUMPING MECHANISMS

       Proceeding with an ocean dumping program requires the establishment of specific ground rules
before planning, organization, estimating, and governmental regulatory permhs can be given For
spent stone wastes from the fluidized bed combustion process, several initial assumptions must be
made including:                                                               K


        1.  Materials will be of sufficient quantity to utilize a standard dumping vessel operating on a
           semi-regular schedule.
        2.  For initial evaluations,  the  spent stone will be taken unprocessed, directly from the
           combustion apparatus in a dry granular form.
        3.  Disposal will be at established  ocean dumpsites designated for industrial wastes.
        4.  Transport  will be from  major seaport locations  on the Atlantic and Gulf costs by a
           commercially established dumping operator.

       The vessel type for disposal of granular spent  stone will be determined by the magnitude of
 initial dispersion desired, ultimate physical fate of the waste and the relative economic advantage. As
 this material falls into the category of dry solid waste, similar to crushed rock or constructive debris,
 the most probable vessel type to be  used is the deck barge with over-the-side dumping. Perhaps the
 more modern barges with clamshell bottoms can be used. Deck barges are most frequently used
 because disposal time is relatively long. This allows for spreading of the disposed materials over a large
 area and minimizes concentrated buildup in a small area of the dumpsite. For spent stone disposal,
 deck barge  dumping can be accomplished by hydraulic jets flushing the material overboard or by
 changing mass to tip down one  side of the barge to allow gravity dumping. While dilution and
 dispersion over large areas is desirable for liquid wastes, controlled concentration and even spreading
 is desired for particulate wastes.

       Various types and  sizes of dumping craft are used for specific operations. The deck barges
 which would be used for spent stone dumping employ different dump actuating mechanisms. It is these
 differences which determine the physical characteristics of ocean dumped materials. Older type vessels
 have six to eight pockets, each equipped with double gravity dump doors on the bottom. Others have a
 hinge type configuration consisting of port and starboard sections hinged topside fore and aft. Large
 hydraulically-operated pistons beneath the hinged doors allow controlled gravity forced release of the
 materials dumped. Most modern barges are remotely operate from the towing vessel which is equipped
 with Loran navigational aid for positive positioning when locating the dumpsite.

       Several physical factors influence the disposal of dumped material from the barges. The same
 parameters  used  to control the physical  characterist.es and effects of  disposed material are the
 principal considerations affecting the  cost of ocean  dumping. Included  are such  conditions as
 discharge rate, water depth, barge capacity, distance to the disposal site and  chermcal reactivity of the
 dumped materials. Based on existing practices,  barging econom.cs have been calculated by EPA
 M97H  From their data  bulk industrial  wastes which include spent stone, would in  197!  cost
 (1971). From their^data^D                 Atlanticand $2.30alongtheGulf Coast foreach ton of
 approximately $ 1 -00 m the Pa< ficjL80             ^ ^ to ^ ^ distances t(j ^
 material dumped.  The principal reason iui m"
                                             165

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waters where industrial dumpsites are located. Deep waters can be reached within 20 miles from shore
along the west coast, but one way distances along the eastern Atlantic and Gulf coasts are as much as
100 miles from shore. From Figure 4, 5, and 6 by EPA (1971) one gets a rough order estimate of the
dumping costs for ocean disposal of industrial waster such as spent stone from the fluidized bed
process.

      Although ocean dumping has been declining in total tonnage in the past two years, primarily
because of the EPA permit system, there are many dumping operators along the Gulf and Atlantic
coasts. In 1975 EPA reported that  11 private companies were involved in industrial waste ocean
disposal operating under the regulations provided in the permit system. Table 3 includes most of these
operators and their present bases of operation. The primary reason for the observed decline in ocean
dumping has been the reluctance of EPA to issue permits, especially in cases where the wastes to be
disposed do not meet the criteria set forth in the Final Regulations. As a result, many operations which
previously went unchallenged are now being scrutinized by the permit process. More industrial waste
disposers are finding alternative methods to disposal at sea or recycling wastes. However, since the
basic premise of MPRSA and the Final Regulations is to seek out the least environmentally damaging
means of waste disposal, the oceans will undoubtedly continue to be used as a receptacle for man's
waste.
                                            166

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      §
             SO     100  '  ISOMO "  250

                   Round Trip Oist«c« In N1lcs
                                               300
     Figure 4. Cost Per Trip Mile as a Function
            of Round Trip Haul Distance
       -is-
               100
                       "~  150       200      250
                      »
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                   Table 3.  Ocean Dumping Operators Licensed by EPA
EPA Approved
Ocean Dumpsites
Departure
 Points
Number of
Operational
Barges
Safety Projects & Eng. Co.

Pine State By-Products

A & S Trans. Co.

Spentonbush Trans. Service

Sun Trans. Co.

Interstate Ocean Disposal Trans. Co.

Port Arthur Towing Co.


DuPont Lessee


Domar Ocean Trans. Ltd.


Dixie Carriers Inc.

Lockport Chemical Co.
Hingham, Mass.

Portland, Me.

S. Kearny, N.J.

NYC, N. Y.

Marcus Hook, Pa.

Marcus Hook, Pa.

Beaumont, Tx.
La Porte, Tx.

Beaumont, Tx.
La Porte, Tx.

Beaumont, Tx.
La Porte, Tx.

Deer Park, Tx.

Baton Rouge, La.
     1

     1

     2

     3

     1

     1

    4
    2

    1
                                        168

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FEASIBILITY OF DUMPING SPENT STONE AT SEA

      There are two philosophies regarding the dumping of wastes at sea. In the first case certain
ocean areas which are deemed to have limited ecological and sociological significance are designated
ior waste disposal. Dumping is conducted in such a way that any adverse biological effects are
restricted to the dumpsite; the area is "written off and hopefully the surrounding environment not
affected. Generally this  philosophy is used to  regulate   ocean diposal activities in areas off the
continental shelf in deep waters. This rationale of waste disposal has been adopted for most industrial
wastes.

      The second philosophy regarding waste disposal in the ocean establishes a classification system
of entire ocean environments within range of the generated wastes. This categorization of the marine
environment is based on the potential or present used of the various areas, taking into consideration
such sociological and ecological values as prime fishing areas, recreational  zones or spawning areas.
For each of these designated environments acceptable types and concentrations of wastes can be
computed and dumping proceeds  until the area has reached the saturation point for the particular
waste. Upon reaching these specified concentrations dumping must cease until the ecology can absorb
the waste  and thereby lower the pollutant concentration.  This attitude  points toward dispersed
dumping in shallow or surface waters. While segregating wastes to restrict the dumping of particularly
toxic or nondegrading materials in these areas, this philosophy of ocean disposal often finds conflicts
between sociological and ecological values. It would not be suitable for the consideration of industrial
wastes.

       Considering ocean dumping of the spent stone from the fluidized bed combustion process, the
first philosophy may be acceptable if controlled disposal at designated sites is demonstrated  to have a
minimal impact. As a result, most locations for spent stone disposal would be at offshore areas as
much as 100 miles from the nearest point of embarkment. The feasibility of using the oceans  for waste
disposal under the established permit  system requires that certain measures be taken. The material to
be disposed must be characterized. Quantities must be estimated. Physical characteristics as well as
chemical constituents must be identified for conditions in a natural state and as the result of seawater
mixing. Such particulars as elemental composition, reactive state, and paniculate sizes of the material
must be quantitated. This characteri/ation must then be checked against the evaluation criteria set
forth in the Final Regulations and any amendments to the regulations. Biological impact assessment
 must be performed.

       The Westinghouse Ocean Research laboratory has performed some initial impact assessments
of the spent stone likely to the generated from the fluidized bed combustion process. A preliminary
feasibility evaluation was performed  with CAFB stone in various mixtures ol seawater taken off the
coast of Maryland in the vicinity  of  two existing mid-Atlantic dumps.tes.  The area from wh.ch the
seawater was taken  represents two  sites which EPA Region  III has .ssued dumping permits for
municipal sewage wastes and industrical liquid wastes (acids with an average PH of 0.1) The m.tial
tests  performed  included  CAFB  stone/seawater mixing   experiments  to  identify  solution
charactenstics, heat  release and  chemical changes. Using  sample  matena  prov.ded by  the
 Wcstinehouse R&D Center, a series of scale experiments were undertaken. Calculations  for these
 westmgnouse K"                         capacity of 2,600 cubic yards, average barge area of 15.
^"eared  erTi y of ' 2*««/«' for ,he CAFB .one and a, ta« 1,200 ft. depth where
  7m  mg wTl take piace Oust off the conunental rt.ll). So*ng ,h,s down we «„ ab,e ,„ work w,,h
a .horoughly mixed spent stone concentration of 4.7 x  10 mg I.

                                            169

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      The first test undertaken was a simple mixing evaluation to determine the proportions of
material which actually settled out. A series of 50 gram aliquots of CAFB stone were mixed in 1 liter
settling tubes with seawater for 1 and 2 minutes and allowed to settle for 1,3 and 18 hours. Data for this
test are given in Table 4. Two distinct liquid phases were observed, a surfactant layer and a lower
flocculant layer. The surfactant layer was a soapy, thinnly clouded mixture while the flocculant was a
more dense wooly mixture. From the results in Table  4, 7 to 309f of the  CAFB stone remained
suspended in the water column over the 18 hour test. As expected, the surfactant layer comprised a
greater percentage of the water column with time and the concentration of suspended particulates
(greater than 0.45/z) decreased from 340 to about 12 mg/1. The lower flocculant layer comprised a
smaller percentage of the water column, but its concentration increased from 2.8 x 10  mg/lto 1.6x
102 mg/1. It is interesting to note that there is not an equilibrium effect where the total suspended solids
remain the same and their proportions in each layer shift. It appeared that the flocculant layer near the
bottom continued to react with  the seawater and paniculate material was released throughout the
entire  18 hours.  As a result, a continuous dense layer  remained just above the sediment mound.
Comparing this test with actual submersible observations of sewage disposal at the Maryland Ocean
Dumpsite there is evidence that a surficial blanket does form near the bottom and breaks up only when
storm-induced mechanical energy  causes forced mixing. The result is that ridges of ocean  bottom are
clear of this floe and that swails tend to accumulate this material. In all probability this same effect will
be realized from the dumping of spent stone granules.

       Another experiment was conducted to measure the heat released as a result of mixing CAFB
stone in seawater. Once again approximately 50 gms of granular spent stone  was placed into a 1 liter
settling tube. The ambient seawater temperature was 14.2°C. Thermisters placed in the sediment, at
mid-water and at the water surface were monitored and temperatures plotted from the time the stone
was  dumped into the settling tube. Figure 7 shows  these results which indicate that the maximum
increase in temperature was 10.4°C over ambient and occurred 19 minutes after the start. Projecting
the curves in Figure 7 equilibrium temperatures would  be reached within 1  hour after dumping.

       A final experiment was conducted whereby the  phases of the spent  stone in seawater were
isolated and chemical analysis performed on the solid and  liquid fractions.  In this test 50 g/1 were
mixed, pH recorded over a 24-hour period and the samples allowed to settle into distinct layers. Heavy
metals analysis was performed  on  liquid and solid fractions  of CAFB stone/sea water mixtures.
Results of the pH  data are given in Table 5 and the  metals analysis are shown with a comparison to
other ocean dumpsite data in Table 6.  From these results it appears that only Vanadium shows any
significant increase over  ambient  levels expected in seawater.

       From the initial assessments made by the Ocean  Reasearch Laboratory we believe it may be
possible to secure an interim permit for ocean disposal of spent stone. Our initial judgement is based on
certain precedents which have been set as well as the specific requirements in the Final Regulations.
Some questions have arisen with regard  to the amended regulations. Spent stone  waste disposal
permits may be secured under the regional permit system in the North and Mid-Atlantic, as well as
Western Gulf states. This includes areas  covered by Region 1 in Boston, Region II in  New York,
 Region III in Philadelphia and  Region VI in  Dallas as  they are the only EPA regional offices with
jurisdiction over active industrial dumpsites. Region IV which includes the Southeastern Atlantic and
Eastern Gulf states does not have any designated industrial dumpsites and would reguire and inter-
regional permit. This would be possible, but more difficult to obtain through the administrator's office
in Washington.
                                            170

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                                                            SEDIMENT
      8    10   12   14   16    18    20   22   24   26   28   30   32
            MINUTES  FROM  START
34   36
Figure 7.  Temperature Changes with CAFB/Seawater Mixture

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                                      Table 4. Suspended Particulates From CAFB/Seawater Mixtures
TIME
MINUTES HOURS
MIXED SETTLED
1 - 1
2 - 1
1 - 3
2 3
2 - 18
SURFACTANT FRACTION
% OF TOTAL
LIQUID
8.5
25.1
77.2
83.1
82.8
CONCENTRATION
(mg//)
340
179
37.8
94.6
11.9
FLOCCULANT FRACTION
% OF TOTAL
LIQUID
91.5
74.9
22.8
16.9
17.2
CONCENTRATION
(nig/I)
279 X 101
289 X 101
393 X 101
1 12 X 102
159 X 102
i-o

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     Tables.  Cnanges in pH witii CAFB Mixed in Seawater




TIME (HOURS)
    START




    0.25




    0.50




    0.75




    1.00




    6.00




   12.00




   18.00




   24.00
 9.75




11.85




11.95




12.00




12.00




12.25




12.40




12.50




12.80
                       173

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Table 6  Heavy Metals Evaluation of CAFB Stone
     Compared to Other Ocean Dumpsites

Chromium
Copper
Nickel
Lead
Zinc
Silver
Iron
Manganese
Antimony
Titanium
Vanadium
CaCO^
Dump
Control
Dump
Control
Dump
Control
Dump
Control
Dump
Control
Dump
Control






» COMPARABLE DUMPS1TE DATA:
<
a.
UJ
|,
m
5-
Z
43
<34
<53
<32
<15
<12
<88
<75










Mid-Atlantic Bight
Sewage Disposal
Site (EPA)
2
<]


6
8








Mid-Atlantic
Bight-
Shellfish Data

7.52
6.33
4.13
2.11
3.37
3.51

3.73
1.18






o
1(3 s
m^S
> ' § a
Z < u
Range
1 .8-460.0
Mean
60.7
Range
1.5-330.0
Mean
6.32
Range
3.O45.0
Mean
13.9
Range
7.0-700.0
Mean
102.5
Range
9.0-900.0
Mean
141.9







.2 °
~5j -~
£ «
•s g-
c S.<
IQS
il
s <
200
8
16
52
110
1.2
50,000
1,700
10
3,000
220
225,000
(a measure
of acidity
** CAFB SPENT STONE:
Water Mixture
(ppm in solution)
<0.02
0.2
<0.02
<0.02
<2.5
1.3
o.:
<.07
<2.0

-------
      in        requirements in the EPA Final Regulations which provide the mechanism for ocean
      ing are contained m Part 227, SecUons 227.3, 227.4. and 22*.5. Certain classification, -thin
these sections must be made concerning the applicability of spent stone wastes to ocean disposal.
According to Section 227.31 (b). such elements as Nickel and Vanadium mu>t not be available in
the waste atconcentrat.ons greater than 0.01 of the concentration established to be toxic to biota of the
receiving waters. While the evaluation criteria does allow for a mixing zone, special care must bo taken
with elements in the waste which are normally found in sea water at trace concentrations (less than 1
part per million). Section 227.34 of the Final Regulations also identifies the considerations which must
be given to the alkalinity of the waste disposal. Because of the high p H caused by mixing of the spent
stone and water there may be a potential for synergistic effects or the formation of toxic compounds to
be found during the immediate release process. This matter must be clarified further before proceeding
with a permit consideration.

       The most important  section of the Final  Regulations regarding  feasibility of spent stone
disposal is contained in  Section  227.4 which establishes the implementation plan requirements for
interim permits. This includes the necessary planning and implementation phase for securing ocean
dumping permits.  The most critical issue in this section states that for industrial wastes the dumper
must "(a) demonstrate the  need for proposed  dumping...compared to alternative locations and
methods, (b) demonstrate the need for the proposed dumping outweights the potential harm...and (c)
provide as satisfactory implementation plan...of the best practical technology currently available for
removal of such materials." This also  includes the best economically available technology for waste
removal.
                                               175

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REFERENCES

E PA, 1971.   The Barged Disposal of Ocean Wastes - A Review of Current Practice and Methods of
Evaluation. B.D. Clark, et. al..  Pacific Northwest Water Laboratory. CorvnlHs. Oregon.

EPA. 1975    Ocean Dumping in the L 'nited States - 797.5. Third Annual Report. Office of Water and
Hazardous  Materials, Washington D.C.

Odum, E.P.,  1959.  Fundamentals of Ecology, 2nd. edition, W.B. Saunders.  Philadelphia.
                                          176

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 APPENDIX VB




OCEAN DUMPING
      177

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Environmental Systems Department
236-7146
February 1, 1977
Ocean Dumping
R & D CENTER - BLDG. 501 3E19

W. G. Vaux


The following memorandum describes the results of my assessment of the
Environmental Protection Agency's (EPA) attitude toward ocean dumping
and the kinds of studies required by EPA to obtain a permit for ocean
dumping.  The purpose of the assessment as defined in Work Order 34-JP-
CPFF-935644-L-A (WESD Contract #743) was to determine:  (1) EPA's atti-
tude toward ocean disposal of sulfated and sulfided limestone in all
contiguous U.S. EPA Regions with emphasis on Regions VI and III,
(2) estimate the probability of EPA issuing an ocean disposal permit in
calendar year 1977 and between 1978 and 1983 inclusive and (3) determine
what preliminary bench-scale dispersion and biotoxicity test will satisfy
current EPA requirements.

These three objectives were met by contacting EPA Regional Offices and
research laboratories and reviewing rules and regulations as reported in
the Federal Register.  From these contacts and reviews, it is concluded
that obtaining a permit from EPA to dump waste on a commercial scale
would be extremely difficult in either 1977 or between 1978 and 1983
because of the general policy of EPA to phase out all ocean disposal of
industrial waste by 1981.  The feasibility of ocean dumping is further
limited by the kinds of constituents associated with the waste and the
regulatory requirements to perform a detailed environmental assessment of
the waste and monitor the dump site.  Reasons leading to these conclusions
are presented in detail in the following paragraphs.

EPA Regions III and VI and the Environmental Research Laboratory in Nar-
rangansett, Rhode Island were contacted regarding EPA policy.  Region III
indicated that EPA in all regions is currently attempting to phase out
ocean dumping of industrial waste by 1981.(D  Region III summarized the
situation in each region as follows:

     Region I (Boston) has at present only two existing ocean dispo-
     sal permits.  Region II (New York) where most of the ocean
     dumping is currently taking place, has currently eliminated
     approximately 50 industrial dumping permits and most others are
     on a compliance schedule to phase out dumping by 1981.  Region III
                                  178

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                                    -2-
      (Philadelphia)  has one ocean dumping permit  which will  he  elimi-
     nated  by 1980.   No ocean dumping of industrial  waste, is being
      conducted in either Region IV (Atlanta) ,  Regions  IX (San Fran-
      cisco)  or Region X Seattle) .

Of the _ seven dumping permits issued in Region  VI  (Dallas) only  two are
operational. (2)   Region VI is currently being  sued by  a local" fishing
group for having allowed ocean dumping.

Conversations with personnel at the EPA Environmental  Research  Laboratory
who are  involved in assessing effects of ocean dumping,  concurred that
EPA is currently attempting to phase out ocean dumping. (3.4)  When the
type  of  waste being considered was described to one  of the staff respons-
ible  for research activities, he felt that the vanadium content would pre-
clude it from meeting ocean dumping criteria and  that  the waste might also
contain  higher than allowable mercury levels,  particularly if the facility
is to be fitted with scrubbers.
EPA has  promulgated regulations and criteria  governing  ocean dumping
pursuant to  Title I of the Marine Protection,  Research  and Sanctuaries
Act of 1972,  Public Law 92-532.  Regulations  and  criteria were published
in the Monday,  October 15, 1973 Federal Register.  Proposed revisions
of these regulations and criteria were  published  in  the Monday, June 28,
1976 Federal  Register, and final revisions  of  regulations and criteria
were published  in the Tuesday,  January  11,  1977 Federal Register.  The
January  11,  1977 regulations and criteria are  the effective regulations
and were reviewed to determine  kinds of studies to be conducted in order
to obtain a  permit.

The regulations and criteria issued January 11, 1977 identify six basic
types of permits.  These are general permits,  special permits, emergency
permits,  interim permits, research permits  and permits  for incineration
at sea.   General permits may be issued  for  the dumping  of materials
which have a "minimal adverse environmental impact and  are generally
disposed of  in  small quantities, or for specific  classes of materials
that must be disposed of in emergency situations."  Special permits may
be issued for the dumping of materials  which  satisfy criteria (refers
to criteria  described in January 11, 1977 Federal Register which are
discussed below) and shall expire no later  than 3 years from the date
of issue.  Emergency permits may be issued  to  dump such materials where
there is demonstrated to exist:  "an emergency requiring the dumping of
such materials, which poses an  unacceptable risk  relating  to human
health and admits of no other feasible  solution." Interim permits may
be issued prior to April 23, 1978 to dump materials  which  are not in
compliance with the environmental impact criteria or which would cause
substantial  adverse effects as  determined by  the  criteria  or for^which
an ocean disposal site has not  been designated on other than an  interim
basis.   A permittee may continue to dump past the April 23,  1978 dead-
line if  the  permittee has an implementation schedule to phase  out ocean
                                  179

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                                   -3-

dumping by December 31, 1981 or if he can meet the requirements of  a
special permit.  In addition, no interim permit will be granted for the
dumping of waste from a facility which has not previously dumped wastes
in the ocean, from a new facility or for the dumping of an increased
amount of waste from the expansion or modification of an existing facil-
ity.  Research permits may be issued for the dumping of materials into
the ocean as part of a research project when it is determined that  the
"scientific merit of the proposed project outweighs the potential environ-
mental or other damage that may result from the dumping."  Permits  for
incineration at sea may be issued in special cases but are not applicable
to disposal of spent stone from fluidized bed combustion.

By considering the types of permits issued, only an interim permit  and
special permit are applicable for the disposal of the spent stone on a
commercial scale.  However, no interim permits will be issued to new
facilities and existing interim permits will be eliminated by 1981  such
that all ocean dumping of industrial waste must be in compliance with
the rules and regulations of a special permit.  Therefore, it is con-
cluded that ocean dumping of spent stone from fluidized bed combustion
process is possible only if provision of a special permit can be met.
Criteria for evaluation of permit applications for ocean dumping and
criteria for management od disposal sites for ocean dumping are pre-
sented in Parts 227 and 228 or the "Final Revision of Regulations and
Criteria" published in the January 11, 1977 Federal Register.

Criteria for the evaluation of permit applications for ocean dumping
require an assessment of the environmental impact, the need for ocean
dumping, impact of the proposed dumping on esthetic,  recreational and
economic values and impact of the proposed dumping on other uses of the
ocean.  Even if an applicant demonstrates that the material to be dumped
staisfies environmental impact criteria, a permit may be denied if  the
other criteria are not met.

Ocean dumping criteria prevent disposal of certain compounds including
mercury and mercury compounds and cadmium and cadmium compounds.  Spent
stone could contain significant amount of these substances, depending
on the source of limestone and coal.

To assess the environmental impacts, it is necessary to conduct exten-
sive bioassays.  These bioassays must be conducted on the liquid, sus-
pended particulate and solid phases to demonstrate at the 95 percent
confidence level, that when materials are dumped, no significant, unde-
sirable effects will occur.  In addition to determination of lethal
effects, the possibility of sub lethal effects due to bioaccumulation
must be considered.  Bioassay tests shall be conducted on at least  one
species each of phytoplankton or zooplankton, crustacean or mollusk and
fish.  Chronic toxicity and bioaccumulation of the solid phase shall be
conducted on benthic organisms, including at least one species each
                                  180

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                                    -4-

representing  a  filter-feeding, deposit feeding and burrowing species.
Therefore,  these  bioassay and bioaccumulation studies must  be conducted
on a total  of at  least six different test organisms.

The liquid  phase  of a material is defined as the supernatant remaining
 after  1 hour undisturbed settling, after centrifugation and filtration
through a 0.45  micron filter."  The suspended particulate phase  is  the
"supernatant  as obtained above prior to centrifugation and  filtration"
and the solid phase includes all material settling to the bottom in
1 hour.

It is  also  necessary to determine if the liquid phase after allowance for
initial mixing  (dispersion which occurs within 4 hours after dumping)
meets water quality criteria contained in "Quality Criteria for  Water."
A permit may  also be denied if "mercury and its compounds are present
in any  solid  phase in concentrations greater than 0.75 mg/kg or  more
than 50 percent greater than the average total mercury of natural sedi-
ments  of similar  lighographic characteristics as those at the disposal
site"  or cadmium  and its compounds are present "in amy solid phase  of
material in concentrations less than 0.6 mg/kg or less than 50 percent
greater than  the  average total cadmium content of natural sediments of
similar lithographic characteristics as those at the  disposal site."

In disposing  of alkaline waste such as the spent stone, dumping  condi-
tions  must  be such that the total alkalinity after allowance for initial
mixing may  be changed based on stoichiometric calculations  by no more
than 10 percent during all dumping operations.  To meet this criterion,
it would involve  a thorough analysis of proposed dumping procedures and
dispersion  of the waste.  Models for predicting disposal of a substance
containing  both solid and soluble phases such as spent stone are not
available at  this time.(6,7)  if no feasible means is available  for
estimating  dispersion, the liquid and solid phases may be assumed to be
evenly distributed after 4 hours over a column of water bounded  on  the
surface by  an area swept out by the locus of points constantly 100  meters
from the perimeter of the dumping point and extending to the ocean  floor,
thermocline or  halocline, if one exists, or to a depth of 20 meters
whichever is  shallower.

Need for ocean  dumping must also be demonstrated.  Particular attention
should be given to the relative environmental risks,  impact and  cost for
ocean  dumping as  opposed to other feasible alternatives, including  but
not limited to:  (1) land fill, (2) well injection, (3) incineration,
(4) spread  of material over open ground, (5) recycling of material  for
reuse   (6)  additional biological, chemical or physical treatment or
intermediate  or final waste streams and (7) storage.

If a potential  ocean dumper meets all criteria and regulations and  obtains
   ermit  the EPA Regional Administrator has the authority  to require the
permittee to  conduct a monitoring program at the dump site.  If  it  is
                                      181

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                                   -5-

detennined that the waste to be dumped is not compatible with waste
being dumped at an existing site, the EPA may require the selection  of  a
new dump site.  If a new site is designated, the permittee must  conduct
a base line monitoring program at the site.vl)

In summary, EPA is currently attempting to phase out ocean dumping of
industrial waste by 1981.  However, if a potential ocean dumper  can meet
the stringent criteria of a special permit, a possibility exists for
a permit to be granted.  Criteria to be met include not only physical/
chemical characterization and bioassay of the material to be dumped but
also full evaluation of alternatives followed by mointoring of the dump
site if a permit is issued.  The possibility that this particular waste
contains constituents such as vanadium, mercury and arsenic from com-
bustion of coal and is highly alkaline suggests that it will not meet
criteria.

The policy of EPA to phase out ocean dumping of industrial waste by 1981,
the stringent criteria which must be meet to obtain a special permit
and the cost associated with demonstrating compliance with the criteria
preclude, in my opinion, consideration of ocean dumping as a means of
disposal of sulfated and sulfided limestone waste from the fluidized bed
combustion process on a commercial scale.
Henry A. Donaldson
Aquatic Biological Sciences

HAD:knw

cc:  M. Kirshner
     G. A. Valiulis
     C-743
                                    182

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                               APPENDIX B

                               REFERENCES


1.  Muir, W., U.S.  Environmental Protection Agency, Region III, personal
    communication  to  H.  A..Donaldson, Westinghouse Electric Corporation,
    Environmental  Systems  Department, January 31, 1977.

2.  Vickey, R.,  U.S.  Environmental  Protection Agency, Region VI, personal
    communications to H. A.  Donaldson, Westinghouse Electric Corporation,
    Environmental^Systems  Department, December 20, 1976.

3.  Gentile,  J. , U.S. Environmental Protection Agency, Environmental
    Research  Laboratory, Narragansett, RI, personal communication to
    H. A. Donaldson,  Westinghouse Electric Corporation, Environmental
    Systems Department,  December 20,  1976.

4.  Payne, R. ,  U.S. Environmental Protection Agency, Environmental
    Research  Laboratory, Narragansett, RI, personal communicatinn to
    H. A., Donaldson, Westinghouse  Electric Corporatinn, Environmental
    Systems Department,  January  27, 1977.

5.  Quality Criteria for Water,  U.S.  Environmental Protection Agency,
    prepublication copy,  July 26, 1976.

6.  Callaway,  R.,  U.S. Environmental Protection  Agency, Evnironmental
    Research  Laboratory,  Corvallis, OR, personal communication  to
    H. A. Donaldson,  Westinghouse Electric Corporation, Evnironmental
    Systems Department,  January  21, 1977.

7.  Schmike,  G., Arthur D. Little Company, personal communications to
    H. A. Donaldson,  Westinghouse Electric Corproation, Environmental
    Systems Department,  January  27, 1977.
                                    183

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                               APPENDIX C

            PREDICTED PRODUCTION PROPORTIONS OF SPENT SORBENT
                AND FLY ASH FROM FLUIDIZED BED COMBUSTION
     Let

     Xc = weight fraction of total sulfur in the fuel
      J
     X  = weight fraction of ash in the fuel
      f\
     2L. = weight fraction of inerts in the fresh sorbent

      R = Ca/S molar treat ratio

Then, on the basis of 100 kg of fuel fed, the fly ash production is
                               W. = 100 X.
                                A        A
The sorbent feed rate is
                    100 Xs
              W_ = (——	) R M.. in the case of limestone
               L      M        1
and
                           100 Xg
                     W  = (——	) R M  for dolomite
                              D

where M   M  and M^ are the molecular weights of sulfur, calcium car-
       O   i_i      JJ
bonate and pure dolomite, respectively.

     Let

     SR = fraction of feed sulfur retained by the sorbent

     The products may contain CaO, CaSO,, CaCO_, fuel ash and limestone
inerts in the case of limestone and CaO-MgO, CaSO -MgO, CaCO «MgO,  fuel
                                    184

-------
ash and dolomite  inerts in the case of dolomite.  The two cases can be
treated as  one  by writing the sorbent as CaCo~-aMgCO  where a = Mg/Ca
molar ratio in  the fresh sorbent and is 1 for dolomite and 0 for lime-
stone.  The dolomite feed rate is then:
                             100 X
                       WD = (-^—> R [ML + a V

where M..  is the molecular weight of magnesium carbonate.
     The  production rate of spent sorbent is then as follows.   (these
calculations assume that magnesium is fully calcined to oxide,  and  the
calcium is  distributed among oxide, sulfate and carbonate):
      Let
                 fraction of feed CaCO  surviving calcination
 Then
                                      100 X
               (CaCO. + a MgO) = a  [ (—rj	) R] [H.  + a
                    J             L     ns

                                      100 Xs
               (CaS04 + a MgO) = SR [ (—	) ]  [MA + a

                                             100 Xg
          (CaO + a MgO) =  [ (1 - a ) R - SR]  [—g	] [MQ + a
                                                S
 where M , M , and M  are  the molecular weights of magnesia (MgO),
 anhydrite (CaSO^) and quick  lime (CaO), respectively.  The insert con-
 tent in the output is
                           XT      100 X
                  W, = fc-^r>  [C-v-^ R^  IML + aMM]
                                      185

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     The spent sorbent production rate is then the sum of the above


four expressions which can be reduced to:



           100 X        M  + a M                        X


    WSS = [-lT^] {R [(1-X   } + MC K + (1 + a)  1~FT)] + W
              O               L                            i-



where Mp and M  are the molecular weights of carbon dioxide and sulfur
       \s      J.

trioxide, respectively.



     The sorbent/fly ash ratio, assuming a sharp separation, is



  W      X            M  + a M                        X
      - <3r> {R ^-XT  )  + Mc
   A      A   S             I
     Inserting molecular weights and typical  values  as  a  =  1.0,

SR = 0.90, aL = 0.0, XA = 0.10,  ^  = 0.05,  this yields:
for limestone
                     W
                     Wqq

                     r-2- = X_  [19.1353 R +  22.4747]
                     W .      b
                      A
for dolomite

                     W
                      CO

                         =  Xc  [33.0929  R +  22.4747]

These equations are plotted  in  Figure  C-l.
                                   186

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8
                                         Curve 686999-A
        I    '    I    •    I
I   Parameter:  Ca/S Molar Treat Ratio
            Dolomite
  L	Limestone
   Basis:
   10% Ash in Fuel
 |_90% Retention of Sulfur by
   Sorbent
   5% Impurities in
 I  Sorbent
                 2       3       4
               Weight % Sulfur in Fuel
 Figure C-l.  Spent Sorbent/Fuel Ash Katie in Fluidized-Bed
            Combustion
                          187

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                                TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse, before completing)
1  RtPORT NO.
 1 TITLE AMD SUBTITLE D^pQg^ of Solid Residue from
 Fluidized-bed Combustion: Engineering and
 Laboratory Studies
 C. C. Sun,  C. H. Peterson, R. A. Newby,  W. G. Vatvx.
 and_p_i_l.i._Ke_airns_ 	
 i'. Ki.P.FOHMING ORGANIZATION IMAMIr AND Ar.TJRESS
 Westinghouse Researcli and Development Center
 1310 Beulah Road
 Pittsburgh. Pennsylvania 15235
 *'i. SPCNUORING AGENCY NAME AND ADDRESS
 EPA, Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC 27711.
                                                      3. RECIPIENT'S ACCESSION- NO.
                                    5. REPORT DATS-
                                     March 1978
                                    6. PERFORMING ORGANIZATION CODE
                                                      a. p;:r-iFORMiNG ORGANIZATION RFPORT NO
                                    10. PROGRAM E LT M~h:N 1" NO.
                                    _EHE6_23A
                                    11. 'CON?"RACT/cfH ANT "NO".

                                     68-02-2132
                                                      13. TYPE OF Ptl'ORT AN.O PERIOD COVERED
                                      SPONSORING
                                      EPA/600/13
 is. SUPPLEMENTARY NOTES ffiRL-RTP project officer is D. Bruce Henschel, Mail Drop 61,
 919/541-2825.  EPA-650/2-75-027c is the previous report relating to this work.
 1C.. ABSTRACT
          The report gives results of an engineering and laboratory study to evaluate
 the environmental impact of disposing of solid residue (spent SO2 sorbent and fuel
 ash) from fluidized-bed combustion (FBC) processes. The quantity and composition
 of spent sorbents produced by six reference FBC processes were projected.  The
 experimental investigation considered residue from atmospheric and pressurized
 FBC processes, with and without sorbent regeneration,  and with and without proces-
 sing of the residue. Laboratory tests were conducted to determine residue charac-
 teristics, leaching behavior, and thermal activity. The environmental impact from
 land disposal of the residue was assessed by comparing the leaching and thermal
 activity results with both available drinking water standards and the behavior of
 natural gypsum. Processing of the spent sorbent and ash, through fixation of the
 residue as a cement-like material, was investigated as away to reduce the envi-
 ronmental impact, and to provide alternatives for potential utilization.  The poten-
 tial for at-sea disposal was also assessed.
17.
                             KEY WORDS AND DOCUMENT ANALYSIS
                DESCRIPTORS
                                          b. IDENTIFIERS/OPEN ENDED TERMS
                                                 :.  COSATl Field/Group
 Pollution
 Combustion
 Fluidizing
 Coal
 Residues
 Waste Disposal
Waste Treatment
Desulfurization
Ashes
Laboratory Tests
Leaching
Properties
Pollution Control
Stationary Sources
Fluidized-bed Combus-
 tion
Environmental Impact
At-sea Disposal
13B
2 IB
07A,13H
2 ID
14B
15E
07D

14B
13. DISTRIBUTION STATE1-

 Unlimited
                        19. SECURITY CLASS (This Report}
                        Unclassified
                                          20. SECURITY CLASS (This page)
                                          Unclassified
                         21. NO. OF PAGES
                         	208
                         22. p~mci
EPA Form 2220-1 (9-73)
                                        188

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