f/EPA
EPA/600/R-09/152
December 2009
Evaluating the Thermal Stability of
Mercury and Other Metals in Coal
Combustion Residues Used in the Production
of Cement Clinker, Asphalt, and Wallboard
Susan Alice Thorneloe-Howard
Principal Investigator
Office of Research and Development
National Risk Management Research Laboratory
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
U.S. Environmental Protection Agency
Washington, D.C.
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Acknowledgements
Technical support for the preparation of this report was provided by ARCADSIS-US, Inc., 4915 Prospectus
Drive, Suite F, Durham, NC under EPA Contracts EP-C-04-023 and EP-C-09-027 (Work Assignment 0-27).
ARCADIS personnel participating in the research included Kevin Bruce, Peter Kariher, and Elizabeth Lee of
ARCADIS.
Also, Connie Senior with Reaction Engineering International is acknowledged for assistance in obtaining
coal combustion residue samples and related background information for this project.
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Table of Contents
Page i
Table of Contents
List of Tables iii
List of Figures iv
List of Acronyms vi
Executive Summary viii
Chapter 1 Introduction 1-1
1.1 Coal Combustion Residues from Multi-Pollutant Control Technology 1-1
aCalcium sulfate hemihydrate or gypsum produced by the FGD system 1-5
bSolid phase from hydroclone overflow stream sent to disposal 1-5
°Liquid phase from hydroclone overflow stream sent to disposal 1-5
1.1.1 CCR Use in Cement Clinker 1-5
1.1.2 CCR Use as Aggregate in Asphalt 1-5
1.1.3 FGD Gypsum Use in Wallboard 1-6
1.2 Objective 1-7
Chapter 2 Materials and Methods 2-1
2.1 CCR Materials for Evaluation 2-1
2.1.1 Brayton Point 2-2
2.1.2 Salem Harbor 2-3
2.1.3 Pleasant Prairie 2-5
2.1.4 Facility A 2-5
2.1.5 Facility B 2-6
2.1.6 Facility E 2-6
2.1.7 Facility M 2-6
2.1.8 Facility N 2-7
2.1.9 Facility O 2-7
2.1.10 Facility S 2-7
2.1.11 Facility T 2-7
2.1.12 Facility W 2-8
2.1.13 Facility X 2-8
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Page ii
2.1.14 Facility Aa 2-8
2.1.15 Facility Da 2-9
2.1.16 FGD Gypsum Sample from U.S. Gypsum 2-12
2.2 Thermal Stability Protocols 2-13
2.3 Analytical Methods 2-16
2.3.1 Mercury (CVAA Method 7471A, Method 3052, Method 7473, Method 30B) 2-16
2.3.2 Arsenic, Selenium and Lead (ICP-MS, Method 3052, Method 6020) 2-16
2.3.2.1 Severn Trent Laboratories, Inc. (STL) 2-17
2.3.2.2 Oxford Laboratories 2-17
Chapter3 Results and Discussions 3-1
3.1 Cement Simulations 3-1
3.2 Asphalt Simulations 3-2
3.2.1 Asphalt Simulation Tests for Mercury Thermal Stability on ADA Fly Ashes 3-2
3.2.2 Asphalt Simulation Tests for Non-Mercury Metals Thermal Stability on ADA Fly Ashes. 3-3
3.2.3 Asphalt Simulation Tests for Mercury Thermal Stability onNon-ADA Fly Ashes 3-5
3.2.4 Asphalt Simulation Tests for Non-Mercury Metals Thermal Stability on Non-ADA Fly
Ashes 3-8
3.2.5 Correlation of Carbon Content and Mercury Volatilization 3-10
3.3 Wallboard Simulations 3-10
3.3.1 Wallboard Simulation Tests for Mercury Thermal Stability on USG FGD Gypsum 3-11
3.3.2 Wallboard Simulation Tests for Non-Mercury Metals Thermal Stability on USG FGD
Gypsum 3-11
3.3.3 Additional Wallboard Simulation Tests for Mercury Thermal Stability on Gypsum Samples
3-12
3.3.4 Wallboard Simulation Tests for Mercury Thermal Stability at Various Temperatures 3-14
Chapter 4 Conclusions and Future Considerations 4-1
Chapters Quality Assurance / Quality Control 5-1
5.1 Quality Indicator Goals 5-1
5.2 Ontario Hydro and Method 29 Mercury Analyses 5-1
5.3 Method 29 Analyses for Arsenic, Lead, and Selenium 5-3
Chapter 6 References 6-1
Appendix A DOENETL Full-Scale Test Site Flow Diagrams 1
Appendix B Non-DOENETL Full-Scale Test Site Flow Diagrams 1
Appendix C Detailed Results for Additional Wallboard Simulation Tests 1
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Table of Contents
Page iii
List of Tables
Table E-l. Boiling Points and Temperatures for 10 Pa (0.075 mm Hg) Vapor Pressure of
Mercury, Arsenic, selenium, and lead viii
Table E-2. Typical Maximum Process Temperatures of Cement Clinker Kilns, Asphalt, and
Wallboard Manufacturing and Laboratory Testing Temperatures viii
Table 1-1. Fly Ash and FGD Gypsum Production and Use in the U.S.a 1-3
Table 2-1. Characteristics of air pollution control and for samples obtained from Brayton Point,
Pleasant Prairie, Salem Harbor, and Facilities A, B, and E 2-4
Table 2-2. ADA Fly Ashes: Elemental Composition (by X-ray Fluorescence) and Other
Characteristics 2-10
Table 2-3. Facility A (SNCR, Facility B (SCR), Facility E (SCR) and Facility M CCRs:
Elemental Composition (by X-ray Fluorescence) and Other Characteristics 2-11
Table 2-4. ADA Fly Ashes: Total Content of Mercury, Arsenic, Cadmium, Lead and Selenium1 2-12
Table 2-5. Facility A (SNCR, Facility B (SCR), Facility E (SCR) and Facility M (SCR) CCRs :
Total Content of Mercury, Arsenic, Lead and Selenium 2-12
Table 2-6. USG FGD Gypsum Samples: Total Content of Mercury, Arsenic, Lead and
Selenium1 2-13
Table 2-7. Description of Asphalt, Wallboard and Cement Clinker Simulations to Test for Metal
Thermal Stability 2-15
Table 3-1. Results of Cement Simulations for Arsenic, selenium, and lead (all values in (ig/g
unless noted) 3-1
Table 3-2. Asphalt Simulation Test results for Mercury on ADA Fly Ashes 3-3
Table 3-3. Comparison of Mercury by Method 29 and Ontario Hydro for Brayton Point Fly
Ashes 3-4
Table 3-4. Results for Asphalt Simulations of Brayton Point Fly Ashes for Arsenic, selenium,
and lead 3-5
Table 3-5. Mercury Results by Ontario Hydro Method forNon-ADA Fly Ashes 3-6
Table 3-6. Comparison of Mercury by Method 29 with Ontario Hydro for Facility B Fly Ashes 3-8
Table 3-8. Results for Asphalt Simulations of Facility M Fly Ash for Mercury, Arsenic,
selenium, and lead 3-9
Table 3-9. Results of Wallboard Simulation Tests for Mercury 3-11
Table 3-10. Results of Wallboard Simulation Tests for Arsenic, selenium, and lead 3-11
Table 3-11. Results of Additional Wallboard Simulation Tests for Mercury 3-13
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Page iv
Table 3-12. Results for Wallboard Simulation Tests on Sample DaAW at Various Temperatures 3-14
Table 5-1. Data Quality Indicator Goals 5-1
Table 5-2. Method 29 Matrix Spike Recoveries for Arsenic, Lead, and Selenium for the Cement
Kiln Simulations 5-3
Table 5-3. Method 29 Matrix Spike Recoveries for Arsenic, Lead, and Selenium for the Asphalt
Simulations 5-4
Table 5-4. Method 29 Matrix Spike Recoveries for Arsenic, Lead, and Selenium for the
Gypsum Wallboard Simulations 5-4
Table C-l. Description of Facilities Providing Eight Gypsum Samples 1
Table C-2. Detailed Results for Additional Wallboard Simulation Tests 2
Table C-3. Detailed Results for Wallboard Simulation Tests on Sample DaAW at Various
Temperatures 3
List of Figures
Figure E-l. Fixed-Bed Reactor Design ix
Figure E-2. Results of Fligh-Temperature Cement Kiln Simulations x
Figure E-3. Normalized Results of Asphalt Simulations Tests for ADA Fly Ashes xi
Figure E-4. Normalized Results of Asphalt Simulation Tests for Non-ADA Fly Ashes xii
Figure E-5. Results for Wallboard Simulation Tests on Gypsum Samples xiii
lrThe same gas mix was used for the simulation of cement clinker and asphalt production (a flow
rate of 400 cc/min of inlet flue gas consisting of 14% CO2, 3% O2, 5.6% H2O and
100 ppm NOX,). The wall board similar used inlet gas of N2 since kettle calciners are
indirectly fired and therefore the sample is not exposed to flue gas) 2-14
Figure 2-1. Schematic of the General Setup for Simulating the Production of Cement Clinker,
Asphalt, and Wallboard 2-14
Figure 2-2. Asphalt and Wallboard Simulation Quartz Reactor and Furnace with Sample 2-14
Figure 2-3. Fligh Temperature Cement Simulation Furnace with Method 29 Mini-Impinger Train 2-15
Figure 3-1. Results of Cement Simulations for Arsenic, selenium, and lead 3-2
Figure 3-2. Asphalt Simulation Test results for Mercury by Ontario Hydro Method on ADA Fly
Ashes 3-4
Figure 3-3. Mercury Results by Ontario Hydro Method for Non-ADA Fly Ashes 3-7
Figure 3-4. Mercury Volatilization as a Function of Carbon Content 3-10
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Figure 3-5. Results for Additional Wallboard Simulation Tests for Mercury 3-14
Figure 3-6. Results for Wallboard Simulation Tests at Various Temperatures 3-15
Figure 5-1. Ontario Hydro spike recovery for multiple runs 5-2
Figure 5-2. Method 29 Mercury spike recoveries for multiple runs 5-3
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List of Acronyms
: vi
List of Acronyms
ACI Activated Carbon Injection
ADA ADA Environmental Solutions
ASTM ASTM International1
BD Below Detection
BML Below Method Limit
CCR Coal Combustion Residues
CVAA Cold Vapor Atomic Absorption
DOE Department of Energy
DRC Dynamic Reaction Chamber
ELAN Emulated Local Area Network
EPA U. S. Environmental Protection Agency
EPRI Electric Power Research Institute
ESP Electrostatic Precipitator
FGD Flue Gas Desulfurization
FDVIS Flow Injection Mercury System
HH V Higher Heating Value
HMA Hot Mix Asphalt
ICP-MS Inductively Coupled Plasma Mass Spectroscopy
LOI Loss on Ignition
MDL Method Detection Limit
MLQ Minimum Level of Quantification
NA Not Applicable
NETL National Energy Technology Laboratory / DOE
NR Not Recorded
NRMRL National Risk Management Research Laboratory
NT Not Tested
OH Ontario Hydro
PRB Powder River Basin
QA/QC Quality Assurance/Quality Control
QAPP Quality Assurance Project Plan
SCA Specific Collection Area
SCR Selective Catalytic Reduction
SNCR Selective Non-Catalytic Reduction
'Previously ASTM was used as an acronym for American Society for Testing and Materials. The new name is ASTM
International.
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List of Acronyms
Page vii
SH Separation Technology Inc.
STL Severn Trent Laboratories
TBD To Be Determined
TPD Temperature Programmed Desorption
USG United States Gypsum Company
XRF X-Ray Fluorescence
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Executive Summary
: viii
Executive Summary
Research is underway by the U.S. Environmental Protection Agency (EPA) to document changes that
may occur to coal combustion residues (CCRs) as a result of implementation of mercury and multi-
pollutant control technology at coal-fired power plants. This work was cited as a priority in EPA's
Mercury Roadmap (http://www.epa.gov/mercury/roadmap.htm') to evaluate the potential for any cross-
media transfers from the management of coal combustion residues resulting from more stringent air
pollution control at coal fired power plants.
This report focuses on the potential for an increase in the volatilization of mercury and other metals from
the utilization of CCRs in the production of cement clinker, asphalt, and wallboard. All three of these
processes require heating during the production process. The four metals evaluated in this study are
mercury (Hg), arsenic (As), selenium (Se), and lead (Pb) (Table E-l). Heating temperatures of the CCRs
for this study were chosen to simulate actual conditions encountered in the cement, wallboard, and asphalt
industries (Table E-2).
Table E-l. Boiling points and temperatures for 10 Pa (0.075 mm Hg) vapor pressure of Mercury,
Arsenic, selenium, and lead
Element
Mercury
Arsenic
Selenium
Lead
Boiling Point
(°C)
357
614
685
1749
Temperature for Vapor
Pressure of 10 Pa (°C)
76.6
323
279
815
Table E-2. Typical maximum process temperatures of cement clinker kilns, asphalt, and
wallboard manufacturing and laboratory testing temperatures
Process
Cement Clinker Kiln
Asphalt Kettle
Wallboard Calciner
Kettle*
Maximum Manufacturing
Plant Temperature (°C)
14,30
168
162
Laboratory Testing
Temperature (°C)
1,450
170
120, 140, 160
*There are three processes in making wallboard that could result in Hg loss. However, the highest
temperature that Hg is exposed to is during the calciner process.
Fly ash and flue-gas desulfurization (FGD) gypsum was obtained from a range of facilities in an attempt
to span differences in air pollution control configuration and coal types. The samples evaluated include:
1. Fly ash from three different facilities evaluated by ADA-Environmental Solutions (ADA) under
contract for the Department of Energy's (DOE's) National Energy Technology Laboratory (NETL)
field evaluation program of sorbent to enhance mercury capture. At each of the three sites, the use of
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2.
Executive Summary
Page ix
activated carbon injection (ACI) was evaluated by adding powdered activated carbon upstream of
existing particulate control. Samples analyzed include fly ash from three facilities with and without
the use of ACI for a total of six fly ashes;
Fly ash from two facilities using selective catalytic reduction (SCR) for post-combustion control of
NOX and one utilizing selective non-catalytic reduction (SNCR) (four with SCR and one with SNCR,
total of five samples); and
3. FGD gypsum kettle feedstock obtained from US Gypsum (two samples).
4. FGD gypsum material obtained from eight different power plants (eight samples).
A fixed-bed reactor design was used to simulate the thermal processes of concern in this study. Figure E-l
provides a schematic of the general setup for simulating asphalt manufacturing, wallboard manufacturing,
and cement clinker manufacturing. For all simulations, samples consisting of various mixes and matrices
were loaded into shallow-bed containers and placed in the reactor. The fixed-bed reactor used for the
asphalt and wallboard simulation assays consisted of a horizontal quartz tube in a thermally controlled
unit (furnace). In the case of the high temperature cement clinker manufacturing (1450 °C), a Lindberg
high temperature furnace was used.
o
= one-way valve
= two-way valve
Figure E-l. Fixed-bed reactor design
In each simulation, the tests were performed in duplicate. Samples were exposed to a flow rate of 400
cc/min of inlet flue gas consisting of 14% CO2, 3% O2, 5.6% H2O and 100 ppm NOX) except for the
wallboard simulation of the kettle calciner, in which the inlet gas consisted solely of N2, because the
kettle calciners are indirectly fired and therefore the sample is not exposed to flue gases. The time in the
fixed-bed reactor for each simulation was one hour. The samples placed in the fixed-bed reactor, as well
as the temperatures in the processes, varied for each simulation. For mercury, the effluent of the reactor
was sampled using a mini-impinger Ontario Hydro train. For sampling the other metals, a Method 29
mini-impinger train was used.
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Executive Summary
Paeex
The making of cement involves the heating of various feedstocks in a cement kiln to make "clinker." This
clinker is ground with gypsum and transported to ready-mix concrete manufacturers. Various components
are needed for feedstock including lime (CaO), iron oxide (Fe2O3), silica (SiO2) or alumina (A12O3). Fly
ash can replace a portion of these, representing a maximum of about 5% (by weight) of the typical raw
mix to the kiln. Other inputs typically include limestone (90%), iron ore (3%), and sand (2%). Cement
kiln residence time is typically one to three hours, and temperatures reach over 1427°C (2600°F) (EPA,
2002). Cement simulation tests for arsenic, Se, and Pb desorption were performed in duplicate on the
ADA fly ashes (baseline only). The tests show good reproducibility and indicate that virtually all of the
metals tested are volatilized when exposed to high temperature as shown in Figure E-2.
o rc
E ~
100%
80%
60%
° £ 40%
Brayton Point Pleasant Prairie Salem Harbor
D Arsenic n Selenium n Lead
Figure E-2. Results of high-temperature cement kiln simulations
Note: Se levels for Pleasant Prairie Baseline fly ash were below minimum detection levels;
therefore, no volatility results are presented.
Hot mix asphalt is a combination of 95% aggregate (e.g., stone, sand, or gravel) bound together by asphalt
cement, a product of crude oil. Fly ash can make up approximately 5% of the total aggregate weight,
replacing natural fillers such as hydrated lime or stone dust (EPA, 2002). Asphalt manufacturing consists
of a very short residence time mixing process (about one minute), a long residence time storage process
(several hours), and then application. The storage process occurs at temperatures of about 5 °C higher
than the mixing process. Asphalt is delivered to the paving machine at approximately the same
temperature as it is stored. Therefore, the most important step (in terms of thermal desorption) is the
storage step. Storage temperatures typically range from 127 °C to 143 °C for binder grade PG46-28 and
157 °C to 168 °C for binder grade PG82-22.
Results for duplicate asphalt simulations tests at 170 °C using the ADA fly ashes are presented in
Figure E-3. Results shown are normalized for mercury measured after completion of the simulation tests.
In all cases, the majority of the mercury was retained in the solid after simulation, with minimal measured
volatilization of mercury (<10% in all cases). Generally, the addition of ACI increased the tendency for
mercury to be retained in the solids at the temperature tested. Total absolute mercury volatilized from
samples with activated carbon injection was <1% for all samples tested.
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Executive Summary
Page xi
— 100%
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N £ 40%
™ > 30%-
o o 20%
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0%
/
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s
5.9
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K
s
IO.O'
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9.6°
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n Brayton Peasant Pleasant Salem Salem
Point w/ Prairie Prairie w/ Harbor Harbor w/
le ACI Baseline ACI Baseline ACI
D Retained in Solid • Volatilizec
Figure E-3. Normalized results of asphalt simulations tests for ADA fly ashes
Asphalt simulations were run at 170 °C using fly ashes from six facilities (in addition to the ADA
samples). Four of the fly ashes were obtained with and without post-NOx combustion control in use
(Facility A and B). None of these samples had ACI in use. Except for Facility M with a mass balance of
74%, the non-ADA fly ashes have a mercury mass balance ranging from 92.5 to 101%. Figure E-4 shows
the results of these experiments that have been normalized by adjusting the mass balance to 100%. As
was the case for the ADA fly ashes, Facility A and Facility E showed minimal mercury loss upon heating.
Facility B, however, demonstrated high mercury volatility (-70-90% loss upon heating).
There was no obvious reason for the higher loss of mercury seen for the Facility B fly ash. Perhaps the
type of SCR catalyst in use at Facility B may have interacted with the fly ash making the mercury less
tightly bound. Additional testing is needed to evaluate this using a wider range of samples
Asphalt simulation tests at 170 °C for the Brayton Point and Facility B fly ashes showed no measurable
volatilization of arsenic, Se, and Pb at the temperature tested during duplicate runs.
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Executive Summary
100%^
= 90%-
£>
2 _ 80%-
c
° 1 70%-
O) O
2 £ 60o/0-
§ 0
" at 50%-
£ 01
Q- ra
•a a 40%-
N g
ra -" 30%-
| 20%-
10%-
n%
/|
38.2%
Facility A
SNCRon
/
34.70/
-?
W
/
/
10.7%
i
'
—
=
23.5%
ii
Facility A Facility B SCR Facility B SCR
SNCR off on off
D Retained in Solid •Volatilized
/
30.80/
-?
W
\
-
^-*
54.3%
-)
Facility E SCR Facility M
on SCR on
Figure E-4. Normalized results of asphalt simulation tests for non-ADA fly ashes
Wallboard is made using calcium sulfate which can be mined as natural rock or obtained from a coal-fired
power plant using flue-gas desulfurization (FGD) gypsum. The first step in the process to make wall
board is to dry the gypsum so that it contains no free moisture - only chemically bound waters of
hydration. This material is referred to as "land plaster". The next step is to calcine the land plaster in a
kettle for about one hour to form calcium sulfate hemi hydrate (i.e., stucco or plaster of Paris) according
to the following reaction:
2 CaSO4-2H2O + heat <-» 2 CaSO^tbO + 3 H2O
The stucco is mixed with water and additives to form slurry that is extruded between two sheets of paper
to form wallboard. The final step is to dry the wallboard prior to processing and stacking it as final
product. Any potential loss is mercury is assumed to occur during the thermal processes with losses most
likely to occur during the calcining step. The highest temperature that FGD gypsum is exposed to is
128°C. Loses could also occur in the gypsum dryer and the finished wallboard dryer. However, the
maximum temperatures that FGD gypsum is exposed to in the dryers is less than calcining (77 to 110°C).
(Sanderson et al., 2008)
Sanderson et al., (2008) provide the most extensive study to date on the fate of Hg when FGD gypsum is
used as feedstock for wallboard production. This work was conducted by U.S. Gypsum Corporation
(USG). Testing of full-scale production facilities is considered more reliable than laboratory testing to
simulate wallboard production. However, the study did not include other metals. Therefore, laboratory
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Executive Summary
Page xiii
simulation of wallboard production was conducted as part of this study. Results from Sanderson et al.,
(2008) indicate that the process where Hg loss is more likely to occur is the kettle calciner. Therefore,
laboratory simulation of wallboard production was conducted evaluating Hg and other metals with the
focus on trying to simulate potential loss across the kettle calciner. Only FGD gypsum samples were
used in this simulation since this is the material used in the production of wallboard (and not fly ash).
This research was conducted in two phases. The first phase resulted in unacceptable mass balance for Hg.
The results for the other metals are considered acceptable. Consequently, additional testing was
conducting in a second phase using more recent FGD samples.
The first phase of testing suggests that As and Se are more likely retained in the FGD gypsum and less
likely to be volatilized during the kettle calcining process. The second phase of testing provided
improved Hg mass balance results. The results (Figure E-5) indicate potential Hg loss of 9 to 48%. The
USG results from wallboard manufacturing facilities indicate Hg loss across the kettle calciner (excluding
the Texas lignite sample) of 2 to 50%. This is considered confirmation of the previous USG research and
emphasizes the variability across samples that may be attributed to how the wet scrubber is operated.
However, additional research is needed to better understand the parameters that might affect Hg loss
across a production facility.
120%-
100%
£ 80%
o>
2 60%-
o>
5
o>
a.
40%
20%-
0%
/^ ,
23%
79%
21%
81%
AaAW DaAW NAW OAW SAW TAW WAW XAW
Sample ID
D Retained in Solid D Volatilized
Figure E-5. Results for wallboard simulation tests on gypsum samples.
The results from this laboratory study demonstrate the varying degree of volatility for mercury, arsenic,
Se and Pb in CCRs depending on the process temperature being used. A high temperature process such as
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Executive Summary
Page xiv
cement clinker production has the ability to release all four metals from fly ash when exposed to the high
temperatures found in production. Laboratory simulation of the asphalt and wallboard production
processes showed a significant release of mercury during heating, but the temperatures were too low to
volatilize the arsenic, Se, or Pb. Whereas, the Hg loss for wallboard production suggest non-Hg metals
being retained in wallboard with a potential Hg loss of 9 to 48%. However, the actual mass emission
rates must be considered when determining potential concern to human health and the environment.
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Section 1
Page 1-1
Chapter 1
Introduction
More wide-spread implementation of multi-pollutant controls is occurring at U.S. coal-fired power plants.
Research is underway by the U.S. Environmental Protection Agency (EPA) to document changes that
may occur to coal combustion residues (CCRs) as a result of implementation of mercury and multi-
pollutant control technology at coal-fired power plants. The Air Pollution Prevention and Control
Division (APPCD) of EPA's Office of Research and Development (ORD) is conducting research to
evaluate cross media transfers of mercury and other constituents of potential concern (COPCs) resulting
from the management of CCRs resulting from wider use of state-of-the art air pollution control
technology. This research was cited as a priority in EPA's Mercury Roadmap to ensure that one
environmental problem is not being traded for another. (2006b) The objective is to understand the fate of
mercury (Hg) and other COPCs in air pollution control residues and support EPA's broader goal of
ensuring that emissions being controlled in the flue gas at power plants are not later being released to
other environmental media. The focus of this report is on the use of CCRs in high-temperature processes
that are encountered during the production of cement clinker, asphalt, and wallboard.
1.1 Coal Combustion Residues from Multi-Pollutant Control Technology
Coal-fired power plants are the largest remaining source of anthropogenic mercury emissions in the U.S.
Power plants are also a major source of nitrogen and sulfur oxides, particulate matter, and carbon dioxide.
New environmental regulations in the U.S. will result in lower mercury air emissions. However, the
mercury and other pollutants are transferred from the flue gas to fly ash and other air pollution control
residues. The Clean Air Mercury Rule (CAMR) would have required the electric utility sector to remove
at least 70% of the mercury released from power plant stack emissions by 2018. CAMR was vacated by
the United States Court of Appeals for the District of Columbia Circuit in 2008. EPA is currently
developing regulations under Section 112 of the Clean Air Act to reduce hazardous air pollutants
(including mercury) from coal-fired power plants. Twenty states have implemented their own mercury
regulations already, according to the National Association of Clean Air Agencies. (Senior et al., 2009)
Other EPA regulations2 will necessitate the addition of new air pollution control devices for NOx and SO2
at some power plants. This can also affect the fate of mercury and other COPCs.
Figure 1 illustrates the types of air pollution control that coal-fired power plants are installing to reduce
air emissions of concern. These control technologies include the addition of flue-gas desulfurization
(FGD) systems to control sulfur dioxide, post-combustion NOx control [selective catalytic reduction
(SCR) and selective non-catalytic reduction (SNCR)], and activated carbon injection to enhance mercury
capture. These controls are typically added to particulate control devices which include the use of electric
static precipitators (ESPs). Fabric filters are also in use for particulate control. The specific type and
combination of control technology as well as the coal type being burned can impact the physical and
2On March 10,2005, EPA announced the Clean Air Interstate Rule (CAIR) (FR 25612, May 2005) which is expected to increase
the use of wet scrubbers and selective catalytic reduction (SCR) units to help reduce sulfur dioxide and nitrogen oxides emissions
from coal-fired power plants. On July 11,2008, United States Court of Appeals for the District of Columbia Circuit remanded
CAIR back to EPA for further review and clarification. Thus the rule remains in effect; however, EPA is in the process of
developing a replacement rule that will address the Court's concerns.
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Section 1
Page 1-2
chemical characteristics of the CCRs. Use of air pollution control technologies will shift Hg and other
pollutants from the stack gas to fly ash, FGD gypsum, and other air pollution control residues.
Sorbenl injection
Scrubber
Fabric filter or
electrostatic
I precipitator
Selective catalytic
Fixed adsorption device reduction
Source: GAO analysis of Electric Power Research Institute data.
Figure 1-1. Illustration of the types of air pollution control that can be used at a coal-fired power plant
(U.S. Government Accountability Office, 2009)
Annual statistics of CCR production and utilization is provided through the American Coal Ash
Association, (www.acaa-usa.org) As of 2008, 136 million tons of CCRs were produced with ~61 million
tons (or 45%) being used in commercial, engineering, and agricultural applications (ACAA, 2009).
CCRs result from unburned carbon and inorganic materials in coals that do not burn, such as oxides of
silicon, aluminum, iron, and calcium. Fly ash, representing 53% of CCRs, is the unburned material from
coal combustion that is light enough to be entrained in the flue gas stream, carried out of the process, and
collected as a dry material in the air pollution control equipment. Bottom ash is the unburned material that
is too heavy to be entrained in the flue gas stream and drops out in the furnace. Boiler slag, unburned
carbon or inorganic material in coal that does not burn, falls to the bottom of the furnace and melts.
Bottom ash and boiler slag are not affected by air pollution control technology and, therefore, these
materials are not being evaluated as part of this study.
Both fly ash and FGD residues have been identified as CCRs with the potential to have increased mercury
and/or other pollutant concentrations from the implementation of new air pollution technologies (EPA,
2002; Srivastava et al., 2006; Thorneloe et al., 2008). The chemical and physical properties may also
change as a result of sorbents and other additives being used to improve air pollution control. The
samples used in this study have been evaluated for their chemical and physical composition and the
potential for leaching of mercury and other COPCs. Companion reports are available providing
additional data on the characterization of these samples. (EPA 2006b, 2008b, 2009)
Table 1-1 provides the quantity of fly ash and FGD gypsum generated in 2008, the amount used in
commercial applications, and the primary applications (ACAA, 2009). Three commercial applications of
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CCRs that involve exposure to high-temperature include production of cement clinker, asphalt, and
wallboard. As shown in Table 1-1, fly ash and FGD gypsum are used in the production of cement
clinker. According to the ACAA, 3.2 million tons of fly ash and 0.4 million tons of FGD gypsum are
used in the production of cement clinker. For wallboard production, only FGD gypsum (and not fly ash)
is used which avoids the need for mining natural gypsum. Of the 17.8 million tons of FGD gypsum
produced in 2008, 8.5 million tons (or 48%) were used in the production of wallboard. Because of the
wider use of wet scrubbers in response to CAIR regulations, this amount is expected to increase with a
higher volume of FGD gypsum3 being generated. Much less volume of CCRs is used in the production
of asphalt. Review of the ACAA statistics indicate that only fly ash is used as mineral filler in the
production of asphalt with a quantity of 17 thousand tons (ACAA, 2008). Therefore, of the three high-
temperature processes, about 12 million tons of CCRs were used in the production of cement clinker,
asphalt, and wallboard with asphalt representing less than 1% of this quantity.
Table 1-1. Fly ash and FGD gypsum production and use in the U.S."
CCRType
Fly Ash
FGD Gypsum
Produced
(million tons)
72.4
17.8
Used in Commercial
Applications (million tons)
30.1
10.6
Percent
Used
42%
60%
Primary Applications
Concrete & grout, structural fill, waste
stabilization/solidification, cement clinker
Wallboard, cement clinker, concrete
"Data from industry survey by ACAA, 2009
Tracking the fate of Hg and other metals removed from the flue gas at a coal-fired power plant, requires
an understanding of the air pollution control in use. Mercury can be found in the gaseous elemental
(Hg°), gaseous oxidized (Hg2+), and particulate bound (Hgp) forms. Air pollution control devices
designed to capture SO2 and particulate matter (PM) can also remove Hg from flue gases in two ways:
removal of Hgp in particulate control devices and removal of Hg2+ in FGD scrubbers. Thus, the Hg
removed from the flue gas may be found in fly ash and in the scrubber solids and liquid effluent. (Senior
et al., 2009)
The Hg that is removed in the FGD scrubber can partition to the solid or liquid streams. Figure 1-2
illustrates the measured partitioning of Hg in FGD outlet streams at five pulverized-coal fired power
plants. (Withum, 2006) The plants fired bituminous coals and had cold-side ESPs for particulate control.
Each of these plants had a selective catalytic reduction (SCR) system forNOx control and a wet FGD
using calcium-containing slurry to control SO2. Gaseous Hg removal by the FGDs ranged from 77% to
95%, and the Hg was found to be in the scrubber solids. (Senior et al., 2009)
' If natural or inhibited oxidation occurs, then calcium sulfite and not calcium sulfate (i.e., gypsum) is produced.
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100%
80%
%Hg in Outlet
Stream
60%
D Stack Gas
D Slurry filtrate
• Slurry solids
Fig. 1-2 Distribution of mercury in FGD scrubber outflows at five bituminous coal-fired power plants
with SCR and FGD. (Senior et al., 2009; Withum, 2006)
Mercury appears to be concentrated in fine particles of scrubber solids that are predominantly iron
oxyhydroxides, and is not strongly associated with the solid calcium sulfate in the scrubber. (Senior et al.,
2009; Kaires et al., 2006; Schroeder, 2007). In some wet FGD systems, the fine solids are recycled back
to the scrubber after dewatering of the byproduct solid, while in others, they are disposed of, as was the
case for two FGDs noted in an EPRI study. (Richardson et al., 2003) Table 2 shows the distribution of
mercury in the scrubber outlet streams for three limestone scrubbers in the EPRI study. For the two
forced-oxidation scrubbers sampled, most of the Hg leaving the scrubber did so in the gypsum fines or
fines liquor after the dewatering process. In forced oxidation scrubbers, this means that Hg can ultimately
be in the gypsum fines as well as in the FGD byproduct. Therefore, it is important to understand how the
FGD gypsum fines are managed in tracking the fate of Hg and other metals in the use of FGD gypsum in
wall board production or other applications.
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Table 1-2. Distribution of mercury among scrubber outlet streams. (Richardson et al., 2007)
Plant - Scrubber Type
1 - Forced Oxidation
2 - Forced Oxidation
3 - Inhibited Oxidation
FGD
Byproduct"
18.9%
7.3%
48.1%
65.7%
Gypsum
Fines"
7.8%
5.2%
48.1%
Gypsum Fines
Liquorc
58.9%
65.6%
0.0%
Stack Gas
14.4%
20.8%
3.7%
35.4%
aCalcium sulfate hemihydrate or gypsum produced by the FGD system.
bSolid phase from hydroclone overflow stream sent to disposal.
°Liquid phase from hydroclone overflow stream sent to disposal.
1.1.1 CCR Use in Cement Clinker
The making of cement involves the heating of various feedstocks in a cement kiln to make "clinker." This
clinker is ground with gypsum and transported to ready-mix concrete manufacturers. Various components
are needed for feedstock including lime (CaO), iron oxide (Fe2O3), silica (SiO2) or alumina (A12O3). Fly
ash can replace a portion of these, representing a maximum of about 5% (by weight) of the typical raw
mix to the kiln. Other inputs typically include limestone (90%), iron ore (3%), and sand (2%). Fly ash
contains high amounts of calcium, iron, silicon, and aluminum, replacing or augmenting raw feed stocks
used in cement production. Cement kiln residence time is typically one to three hours, and temperatures
reach over 1427 °C (2600 °F) (EPA, 2002). Because of the high temperatures, virtually all mercury will
be volatilized when CCRs are used as feedstock to cement kilns.
Because of the concern for Hg and other hazardous air pollutants, EPA has proposed (74 FR 21136m May
6, 2009) regulations to reduce Hg emissions from cement kilns, which may result in use of air pollution
control technology similar to that used at coal-fired power plants (e.g, wet scrubbers and sorbents for
enhanced Hg capture). The addition of air pollution control at cement kilns should not affect the ability to
use fly ash or FGD gypsum in the production of clinker. However, to avoid installation of air pollution
control, kiln inputs (such as fly ash) containing Hg may be avoided which could impact usage of some
CCRs.
1.1.2 CCR Use as Aggregate in Asphalt
Hot mix asphalt is a combination of 95% aggregate (e.g., stone, sand, or gravel) bound together by asphalt
cement, a product of crude oil. Fly ash can make up approximately 5% of the total aggregate weight,
replacing natural fillers such as hydrated lime or stone dust (EPA, 2002). Asphalt manufacturing consists
of a very short residence time mixing process (about one minute), a long residence time storage process
(several hours), and then application. The storage process occurs at temperatures of about 5 °C higher
than the mixing process. Asphalt is delivered to the paving machine at approximately the same
temperature as it is stored. Therefore, the most important step (in terms of thermal desorption) is the
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storage step. Storage temperatures typically range from 127-143 °C for binder grade PG46-28 and 157-
168 °C for binder grade PG82-22.).
1.1.3 FGD Gypsum Use in Wallboard
In 2007, FGD gypsum (e.g., gypsum produced from use of wet scrubbers) accounted for 35% of the total
domestic gypsum production (9.2 million tons of FGD gypsum used versus 26.4 million tons of domestic
gypsum supply (ACAA, 2008; USGS, 2008). Almost 85% of the gypsum consumed in the U.S.
(approximately 24 million tons) in 2008 was used in the manufacture of wallboard and plaster products
with U.S. wallboard plant capacity at 27 billion square feet per year (USGS, 2009). As more coal
combustion facilities add scrubbers, the production (and use) of FGD gypsum is projected to grow.
FGD gypsum is typically dewatered at the utility plant before shipment to a wallboard manufacturing
facility (EPA, 2002). The mercury in the FGD sludge has been reported to be associated with the fines
(i.e., fine solid particles) and not the FGD liquors (DOE; 2005; Schroeder and Kairies, 2005). There are
several ways FGD solids can be prepared for use at a wallboard manufacturing plant. If the FGD sludge
does not meet the wallboard manufacturer's specifications (as-is), then the fine solid particles are
typically removed. This removal process is often completed with hydrocyclones and the fines are either
disposed or sold for other uses (DOE, 2005). Other facilities have to "blow down gypsum fines" as a part
of the chlorine purge, limiting chlorine buildup in the FGD liquor (DOE, 2005). As wall deposits
buildup, the scrubber efficiency will be reduced until scrubber water rich in solids or salts is wasted or
"blown down" and replaced with low solids water. Since Hg is associated with the fine particles of the
FGD sludge (DOE, 2005), both of these processes result in a gypsum product which typically contains
less mercury than the wet FGD sludge itself. If the FGD sludge is used as-is, the mercury content is
typically greater than those processes that remove the fines.
The first process in making wall board is to dry the gypsum so that it contains no free moisture - only
chemically bound waters of hydration. This material is referred to as "land plaster". The next step is to
calcine the land plaster to form calcium sulfate hemi hydrate (i.e., stucco or plaster of Paris) according to
the following reaction:
2 CaSO4-2H2O + heat <-» 2 CaSO^tbO + 3 H2O
The stucco is mixed with water and additives to form slurry that is extruded between two sheets of paper
to form wallboard. The final step is to dry the wallboard prior to processing and stacking it as final
product. The drying step is not likely a release point for mercury since the wallboard is between two
sheets of paper at this point and typically does not reach temperatures of more than 100 °C. Meischen
(2004) conducted a study on laboratory-produced FGD containing Hg and concluded that Hg
volatilization would not be likely where only the edges of the wallboard were exposed. Mercury release
diminished as the weight of the wallboard increased.
Any potential loss in Hg is considered more likely to occur during the calcining step. The highest
temperature that FGD gypsum is exposed to is 128°C. However, possible loses could also occur in the
gypsum dryer and the finished wallboard dryer. However, the maximum temperature to which the
gypsum is exposed in the dryers is less than during calcining (77 to 110°C). (Sanderson et al., 2008)
The drying step is not likely a release point for mercury since the wallboard is between two sheets of
paper at this point and typically does not reach temperatures of more than 100 °C. Meischen (2004)
conducted a study on laboratory-produced FGD containing mercury and concluded that mercury
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volatilization would not be likely where only the edges of the wallboard were exposed. Mercury release
diminished as the weight of the wallboard increased.
Sanderson et al., 2008, provide data evaluating the fate of Hg in FGD gypsum across wallboard
production plants. This work was conducted by U.S. Gypsum through funding by DOE and the Electric
Power Research Institute (EPRI). Table 1-3 provides a summary of the results from measurements of the
Hg content in FGD gypsum and across the gypsum dryer, calciner, and wallboard dryer. The results show
a wide-range of Hg losses ranging from 2 to 55% loss of mercury in the feedstock and using Ontario
Hydro method at the process stacks. Most of the loss was found to occur at the gypsum calciner when the
total Hg loss was greater than 10%. There was less of a difference across the gypsum dryer, calciner, and
wall board dryer when the mercury loss was below 10%. (Sanderson et al., 2008)
The authors caution drawing conclusions from this research because only seven sets of wallboard plant
measurements were made and it is difficult to identify what factors impact mercury loss percentages. One
finding is that the operation of the wet scrubber can affect the fate of Hg. The effectiveness of the
scrubbing solution in removal of COPCs depends on the concentration of the scrubbing chemical which is
continuously being depleted during the process. COPCs transferred to the liquid phase are removed from
the scrubber by continuous or periodic overflow of blow down. For those facilities using higher blow
down rates of chlorides and fine solid particles at wet FGD systems led to higher percentage of Hg loss at
the wallboard plant. However, higher purge rates also led to FGD gypsum with lower Hg concentrations.
The authors conclude that improved understanding the physical and chemical association of the Hg in
gypsum might clarify the conditions that lead to the higher Hg loss.
The US Gypsum study did not include analysis of metals other than mercury. Therefore, wallboard
simulation study was included as part of this research. However, testing of full scale production facilities
is considered preferable over conducting smaller-scale laboratory simulations. US Gypsum provide two
samples from their earlier testing to use in this study.
1.2 Objective
With the increasing metals content of CCRs as a result of changes in air pollution control at coal-fired
power plants, there is interest in evaluating the fate of mercury and other metals. The objective of this
research is to conduct laboratory simulations of three high temperatures processes that use CCRs in the
production of cement clinker, asphalt and wallboard to determine the likelihood of metals being
volatilized during the production process. The metals that were analyzed for this study include Hg,
arsenic (As), selenium, and lead (Pb). The study support EPA's broader goal of ensuring that emissions
being controlled in the flue gas at power plants are not later being released to other environmental media
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Table 1-3. Sanderson et al., 2008 study to evaluate of Hg loss across wallboard production
facilities
Test#
Test Date (2 day test)
Power Plant
Coal Type
SCR in use
FGD Fines Blow Downa
Wallboard plant
Hg content, FGD gypsum
(ng/g)d
Moisture content, wt%
1
July 2004
A
High-Sulfur
Bituminous
Yes
Low rate
1
0.96 ±0.03
11.9
2
Dec 20004
A
High-Sulfur
Bituminous
By-passed
Low rate
1
1.10 ±0.04
11.1
3
Sept 2004
B
High-Sulfur
Bituminous
Yes
High rate
2
0.21 ±0.02
11.3
4
Feb 2005
C
Texas
Lignite
No
None
3
0.53 ±0.01
12.6
5
March 2006
E
High-Sulfur
Bituminous
By-passed
High rate
4
0.20 ±0.04
10.9
6
Sept 2006
E
High-Sulfur
Bituminous
Yes
High rate
4C
0.13 ±0.0
6.3
7
Aug 2007
F
Powder River
Basin
Yes
Variable"
5
1.06 ±0.06
7.2
Hg Loss at Wallboardd - % of inlet Hg to each process step
-Across Dryer Mill (%)
-Across Kettle Calciner (%)
-Across Board Dryer Kiln (%)
Overall Loss
Hg Loss Based on Raw
Gypsum & Wallboard
Product Hg Cone d,%
Hg Loss from Process Stacks,
g/hr
Hg Loss Rate, Ib/MM ft2 of
wallboard
Hg Loss Rate, g/ton of dry FGD
gypsum
1.1 ±0.9
2.3 ± 1.0
1.9 ±0.6
5.1± 1.7
2.0 ±5.0
4.1 ± 1.7
0.1
0.05
0.3 ±0.1
2.6 ±0.0
5.5 ±2.4
8.3 ±2.0
16±8
2.7 ±0.1
0.1
0.08
1.0 ±0.3
41±2
14 ±6
46 ± 16
66 ±2
8.2 ±0.5
0.2
0.09
0.8 ±0.1
0.8e
0.3e
1.8e
8.7e
0.26e
0.01e
0.01e
1.8 ±0.4
50 ±6
1.4 ± 1.2
51±5
40 ±21
2.0 ±0.2
0.2
0.09
4.1 ± 1.9
45 ± 1
5. 8 ±5.6
55 ±6
32 ±2
1.4 ±0.2
0.1
0.06
0.6 ±0.4
15 ±2
3.2 ± 1.0e
18±2e
32 ±3
4.2±0.6e
0.4e
0.17e
"More qualitative than quantitative as reported by Sanderson et al, 2008.
bWastewater treatment plant for FGD system uses filter press for removing fine particles from hydrocyclone overflow liquor, so fine and chlorides can be "blown
down" independently.
TDuring this test, soluble tri-sodium salt (or TMT) was used to precipitate dissolved Hg (by chemically binding to heavy metals via sulfur groups which can be
separated from the FGD liquor by filtration).
dMean value for three runs 5 ± 95% confidence interval of mean, unless noted otherwise; loss percentages across dryer mill, kettle calciner, and board dryer kiln
are based on feed material to each step, so percentages cannot be summed to the wallboard product overall loss percentage show.
eMean value for two runs
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Chapter 2
Materials and Methods
2.1 CCR Materials for Evaluation
Twenty-one CCR samples were used to evaluate the thermal stability of mercury and other metals during
the production of cement clinker, asphalt, and wallboard. This work has been conducted in stages with
initial work using samples collected as part of a DOE-funded program to evaluate sorbent technology for
enhanced mercury capture. Samples were also obtained through CCR characterization study evaluating
changes in CCR composition and constituent release by leaching that may occur to fly ash and FGD
gypsum in response to changes in air pollution control technology at coal-fired power plants (EPA 2006,
2008b, 2009). Because samples were obtained on a voluntary basis and represent a minor fraction (<1%)
of U.S. boilers, these results are not considered to provide a statistically representative sample.
Regardless, care was taken to obtain samples that are considered typical of the CCRs resulting from
improvements in air pollution control.
The samples analyzed include:
1. Fly ash from three different facilities evaluated by ADA-Environmental Solutions (ADA) under
contract for the Department of Energy's (DOE) National Energy Technology Laboratory (NETL).
Powdered activated carbon was injected upstream of particulate control to improve the capture
efficiency of mercury. Samples were collected from Brayton Point, Pleasant Prairie, and Salem
Harbor with and without the use of activated carbon injection (ACI) for atotal of six samples as
shown in Table 2-4.4
2. Fly ash from two facilities with and without the use of post-NOx combustion control [Facility A
using selective non-catalytic reduction (SNCR) and facility B using selective catalytic reduction
(SCR). Fly ash from two additional facilities (Facility E and M) both with SCR in use. This
represents atotal of five samples as shown in Table 2-5; and
3. FGD gypsum kettle feedstock obtained from U.S. Gypsum (two samples) as part of the research
documented in Sanderson et al., 2008. Only a small sample size was provided which did not allow
detail characterization as done for the other CCRs.
4 These samples were collected during early test programs to evaluate use of ACI for enhancing mercury
capture. Samples were obtained prior to and after ACI in use. Industry has found that less carbon is needed
to obtain the same level of mercury capture obtained during the early test programs. Therefore more recent
samples are suspected to contain less carbon than that used in this evaluation. However, this is not
suspected to impact the thermal evaluation.
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4. FGD gypsum material obtained directly from eight power plants with web scrubbers in use (eight
samples).
The fly ash samples from the NETL field evaluation program represent the first time that sorbent was
used to enhance mercury capture over a test program of several weeks. All three of the facilities in the
NETL program (Brayton Point, Salem Harbor and Pleasant Prairie) have particulate control devices and
do not use scrubbers (at the time the samples were collected). The same commercial sorbent, Norit
Americas Flue Gas Desulfurization (FGD) Carbon, was used for each test. This sorbent has a surface area
of 600 m2/g and a mass-mean diameter of 18 (im. The ACI was injected at a rate of 10 Ib/Macf during the
sorbent testing phase of these tests.
All of the facilities mentioned above are further described in subsequent sections. Tables 2-1 and 2-3
provide the elemental characteristics of the coal combusted at Brayton point, Pleasant Prairie, and
Facilities A, B, and E. Table 2-2 provides the elemental analysis [by x-ray fluorescence (XRF)
spectroscopy] of the fly ashes from the ADA samples and Facility A, B, E, and M. Except for the
samples from U.S. Gypsum (the sample size was too small), for each of the CCRs used in this study,
more detailed information is available on the air pollution control configurations, coal burned, and the
CCR composition and leaching characteristics. (EPA 2006, 2008b, 2009).
2.1.1 Brayton Poin t
Brayton Point Station, located in Somerset, Massachusetts, is operated by PG&E National Energy Group.
Unit 1 of this facility was selected for evaluation. Emissions from this facility are controlled through the
use of low-sulfur coal and cold-side ESP which is typical of coal-fired power plants in the eastern U.S.
The unit has a tangentially fired boiler rated at 245 MW, fires low-sulfur coal, and uses a cold-side ESP
for particulate control (Senior et al., 2003a).
The primary particulate control equipment consists of two cold-side ESPs in series, with an EPRICON
flue gas conditioning system provides SO3 for fly ash resistivity control and is used on an as-needed basis.
The first ESP in this particular configuration was designed and manufactured by Koppers with a weighted
wire design and a specific collection area of 0.512 m2/ amVmin (156 ft2/1000 acfm). The second ESP in
the series configuration was designed and manufactured by Research-Cottrell with a rigid electrode
design and a specific collection area of 1.3 m2/ amVmin (403 ft2/1000 acfm). The precipitator inlet gas
temperature is nominally 138 °C (280 °F) at full load (Senior et al., 2003b). The facility uses ACI to
increase mercury capture. The ACI control system injects the carbon between the ESPs to capture the
mercury with the fly ash. The baseline and post-control ashes used for this study were collected as
composite samples from the third row of ash hoppers of the second ESP. The baseline ash was collected
on June 6, 2002. The post-control fly ash was collected on July 21, 2002. Both fly ashes were stored in
five-gallon buckets in the onsite ADA-ES trailer at ambient temperatures. The buckets were filled to
approximately three-fourths capacity.
Elemental composition by XRF and additional characteristics of the fly ashes from baseline and enhanced
mercury control testing are provided in Table 2-2. Results for total content analyses for mercury, arsenic,
Pb, and Se are provided in Table 2-4.
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2.1.2 Salem Harbor
PG&E National Energy Group owns and operates Salem Harbor Station located in Salem, Massachusetts.
There are four fossil fuel fired units at the facility designated as Units 1, 2, 3, and 4. Units 1-3 fire a low
sulfur, bituminous coal and use oil for startup. Unit 1 was selected for the control technology evaluation
because of its combination of firing low-sulfur bituminous coal with urea-based selective non-catalytic
reduction (SNCR) for nitrogen oxide reduction, a cold-side ESP, and high loss-on ignition (LOI). This
configuration provided an opportunity to quantify the impact of SNCR on mercury removal and sorbent
effectiveness. In addition, test results from prior mercury tests have indicated 87 to 94% mercury
removal efficiency on this unit. Unit 1 is a B&W single-wall-fired unit with twelve DB Riley CCV-90
burners and is rated at 88 gross MW (Senior et al., 2003b).
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Table 2-1. Characteristics of air pollution control and for samples obtained from Brayton Point, Pleasant Prairie, Salem Harbor, and
Facilities A, B, and E
Parameter Measured
Coal Type
Sulfur, wt%
Ash,wt%
Moisture, wt:
HHV, Btu/lb
Hg, ug/g
Cl, ug/g
As, ug/g
Pb, ug/g
Se, ug/g
Paniculate Control
Device
Sorbent Injection Point
Sampling Location
Brayton Point
Low sulfur bituminous
0.7
10.8
4.7
12,780
0.044
1475
5.68
8.9
3
Two Cold-Side ESPs
in Series
Between Two ESPs
Ash Hopper Row C
Pleasant Prairie
Powder River Basin (PRB)
sub-bituminous
0.3
5.1
30.7
8,385
0.109
8.1
NT
NT
NT
Cold-Side ESP
Before ESP
ESP
Hopper 1 and 2 Composite
Salem Harbor
Low sulfur
bituminous
0.67
6.48
9.05
12,420
0.0617
64.3
2.4
3.8
4.8
Cold-Side ESP
Before ESP
ESP Hopper A
Facility A
Medium sulfur
bituminous
1.05
10.29
6.0
12,790
0.086
166
NT
NT
NT
Fabric Filter
NA
Pug Mill
Facility B
High sulfur
bituminous
3.34
12.4
6.1
12,000
0.08
615
NT
NT
NT
Cold-Side ESP
NA
Ash Hopper
Facility E
Low sulfur
bituminous
0.83
9.3
4.06
12,852
0.06
4500
4.0
6.0
3.0
Cold-Side ESP
NA
Ash Hopper
NT = Not tested, NA = Not applicable, HHV = Higher Heating Value (Heat of Combustion)
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The participate control equipment consists of a two-chamber, cold-side ESP (chambers designated 1-1
and 1-2), which provides two separate gas flow paths from the outlet of the tubular air heaters to the
inducted draft (ID) fan inlets. This Environmental Elements ESP has a rigid electrode design and a
specific collection area of 1.56 m2/ amVmin (474 ft2/1000 acfm). The precipitator inlet gas temperature is
nominally 124 °C (255 °F) at full load. Typical LOI of the Unit 1 ash is about 25%. This ash is landfilled
(Senior etal., 2003b).
The baseline and post-control ashes used for this study were collected as grab samples from the first ash
hopper (hopper A) of row 1-1 of the ESP. The baseline ash was collected on June 6, 2002. The post-
control fly ash was collected on July 7, 2002. Both fly ashes were stored in five gallon buckets in the
onsite ADA-ES trailer at ambient temperatures. The buckets were filled to approximately three-fourths
capacity. Elemental composition by XRF and additional characteristics of the fly ashes from baseline and
enhanced mercury control testing are provided in Table 2-2. Results for total content analyses for
mercury, arsenic, Pb, and Se are provided in Table 2-4.
2.1.3 Pleasan t Prairie
Wisconsin Electric Power Company, a subsidiary of Wisconsin Energy, owns and operates Pleasant
Prairie Power Plant located near Kenosha, Wisconsin. The plant has two 600 MW balanced-draft coal-
fired boilers designated units 1 and 2. Unit 2 was selected for inclusion in the NETL program because it
burns a variety of Powder River Basin low sulfur, sub-bituminous coals. (Starns et al., 2002).
The primary particulate control equipment consists of cold-side ESPs of weighted wire design with a
Wahlco gas conditioning system that provides SO3 for fly ash resistivity control. The precipitators were
designed and built by Research-Cottrell. The design flue gas flow was 61,164 anrVmin (2,610,000 acfm).
The precipitator inlet gas temperature is nominally 138 °C (280 °F) at full load (Starns et al., 2002).
Precipitator #2 is comprised of four electrostatic precipitators that are arranged piggyback style and
designated 2-1, 2-2, 2-3, and 2-4. Each of the four precipitators is two chambers wide and four
mechanical fields deep with eight electrical fields in the direction of gas flow. The specific collection area
is 1.54 m2/ anrVmin (468 ft2/1000 acfm) (Starns et al., 2002).
Hopper ash is combined from all four precipitators in the dry ash-pull system. The ash is sold as a "Class
C" fly ash to be used as a base for concrete (Senior et al., 2004). The baseline ash was collected as a
composite sample from ash hoppers 7-1 and 7-2 of ESP 2-4. The post-control ash was collected as a grab
sample from ash hopper 7-2 of ESP 2-4. The baseline ash was collected on September 11, 2001. The post-
control fly ash was collected on November 13, 2001. Elemental composition by XRF and additional
characteristics of the fly ashes from baseline and enhanced mercury control testing are provided in
Table 2-2. Results for total content analyses for mercury, arsenic, Pb, and Se are provided in Table 2-4.
2.1.4 Facility A5
The test site was a 440-MW coal-fired power plant with a reverse-air fabric filter followed by a wet flue
gas desulfurization system. The unit burns ~1 percent sulfur eastern bituminous coal. The unit operated at
nominally full load for the duration of the test program. A schematic diagram of the power plant is shown
in Appendix A. The unit is equipped with a pulverized-coal boiler and in-furnace selective non-catalytic
reduction (SNCR); urea was injected into the boiler during the course of operations within the duration of
5 EPA was requested not to disclose the identity of the other sites. Therefore, the remaining sites are coded as letters.
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the initial part of this test program. However, urea was not injected into the boiler for the final comparison
test ("SNCR off). Gas exiting the furnace is split between two flues equipped with comparable control
equipment. Particulate is removed with a reverse-air fabric filter. Flue gas is then scrubbed through a
multiple tower wet FGD unit; FGD is a limestone forced-oxidation design. The two flues are joined prior
to exhausting to a common stack. The annular stack rises 93.9 meters (308 feet) above the top of the
incoming flue. The stack is operated in a saturated condition with no reheat. The fly ash and FGD waste
are combined and then dewatered before landfill disposal. Elemental composition by XRF and additional
characteristics of the fly ashes from baseline and enhanced mercury control testing are provided in
Table 2-3. Results for total content analyses for mercury, arsenic, Pb, and Se are provided in Table 2-5.
2.7.5 Facility B
The test site was a 640 MW coal fired power plant with cold side ESP followed by a wet flue gas
desulfurization system with inhibited Mag-lime (CaO + MgO). The unit burns medium- to high-sulfur
eastern bituminous coal. The plant is equipped with a pulverized coal boiler and an in-furnace selective
catalytic reduction (SCR) system composed of vanadium pentoxide (V2O5), tungsten trioxide (WO3), and
titanium dioxide (TiO2) mixture. One set of samples was collected during a season of elevated ambient
ozone while ammonia was injected into the catalyst box at a concentration of 320 ppm ("SCR on") to
control NOX. A second set of samples was collected during the winter when ammonia was not being
injected ("SCR off). Particulate is removed with a cold-side ESP. Flue gas is then scrubbed through a
wet FGD unit; the FGD unit is an inhibited Mag-lime design. The fly ash and FGD waste are combined
and then dewatered before landfill disposal in a clay-lined site. Elemental composition by XRF and
additional characteristics of the fly ashes from baseline and enhanced mercury control testing are
provided in Table 2-3. Results for total content analyses for mercury, arsenic, Pb, and Se are provided in
Table 2-5.
2.1.6 Facility E
The test site was a 390 MW coal fired boiler with cold side ESP. The unit burns low-sulfur eastern
bituminous coals. The unit is equipped with a pulverized coal boiler and selective catalytic reduction
(SCR) system using a titanium dioxide/tungsten trioxide/silicon dioxide/vanadium pentoxide catalyst.
Particulate is removed with a cold-side ESP. The fly ash is transported by a dry handling system to a silo
where it is combined with fly ash from three additional boilers and wetted with water prior to being
transported to a clay-lined landfill. Elemental composition by XRF and additional characteristics of the
fly ash are provided in Table 2-3. Results of total content analyses for mercury, arsenic, Pb, and Se are
provided in Table 2-5.
2.7.7 Facility M
This test site was a 1,000 + megawatt (MW) power plant. The plant burns high-sulfur bituminous coal in
a dry-bottom pulverized coal boiler. Electrostatic precipitators (ESPs) are used on all units for particulate
control, and wet FGD systems are used to reduce SO2 emissions on two units. The wet FGD systems
utilize limestone slurry and an inhibited oxidation process. The FGD sludge, consisting primarily of
calcium sulfite, is pumped from the absorber to a thickener. Liquid overflow from the thickener is
recycled back into the FGD system, and the thickened sludge is pumped to a series of drum vacuum filter
for further dewatering. Water removed by the drum vacuum filters is recycled back into the FGD system,
and the filter cake is taken by conveyor belt to a pug mill, where it is mixed with dry fly ash and dry
quicklime for stabilization. The resulting stabilized FGD solids are taken by conveyor to a temporary
outdoor stockpile, and then transported by truck either to a utilization site or to an on-site landfill. The
active portion of the landfill is lined and leachate is collected. An older inactive portion of the landfill is
clay-lined but does not have leachate collection.
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2.1.8 Facility N
Facility N is a wall fired 715 MW coal-fired power plant with cold side ESP followed by a wet FGD
system using wet limestone in a forced oxidation process. The unit burns medium to high sulfur eastern
bituminous coals with approximately 3% sulfur. The gypsum is washed, dried and then sold to the
wallboard industry.
One 5 gallon bucket of un-washed gypsum (NAU) and one 5 gallon bucket of washed gypsum (NAW)
were collected from this site. Facility N was sampled on June 1, 2006. The samples were collected by
RMB Consulting & Research, Inc. (Raleigh, NC) personnel. The washed gypsum sample (NAW) was
used in the laboratory wallboard simulation.
2.1.9 Facility O
Facility O is a tangentially fired 500 MW coal-fired plant with cold side ESP followed by a wet FGD
system with wet limestone forced oxidation. The unit is equipped with a pulverized coal boiler and
ammonia based SCR. This unit burns high sulfur eastern bituminous coals. Slurry from the absorber goes
to a primary hydrocyclone for initial dewatering. The gypsum (hydrocyclone underflow) is dried on a
vacuum belt and washed to remove chlorides, before use in wallboard.
Two samples were collected from the FGD gypsum drying facility by compositing samples collected on
June 10, 11, and 12, 2006 when the SCR was operating. On each day, two gallon pails of unwashed
gypsum and washed/dried gypsum were collected. The unwashed gypsum was collected from the vacuum
belt prior to the chloride spray wash. The washed/dried gypsum was collected from the end of the vacuum
belt. The three daily samples were sent to Arcadis for compositing to form sample OAU (unwashed
gypsum) and sample OAW (washed gypsum). All samples were collected by plant personnel. The
washed gypsum sample (OAW) was used in the laboratory wallboard simulation.
2.1.10 Facility S
This test site is a 600 megawatt (MW) per unit power plant. The plant burns eastern high sulfur
bituminous coal in a dry-bottom pulverizer boiler. Cold-side electrostatic precipitators (ESPs) are used
on all units for particulate control, and wet FGD systems are used to reduce SO2 emissions on two units.
The wet FGD systems utilize limestone slurry sorbents and an forced oxidation process
Samples of washed (SAW) and unwashed (SAU) gypsum were collected at this site in July, 2007. One
five-gallon bucket of each was collected by plant personnel. The washed gypsum sample (SAW) was
used in the laboratory wallboard simulation.
2.1.11 Facility T
This power plant test site has three boilers producing a total of a 2,000+ megawatts (MW). The plant
burns medium sulfur eastern bituminous coal in a dry-bottom pulverizer boiler. Units 1 and 2 have coal
cleaning equipment to reduce ash ad SOX emissions. All three of these units have low NOX burners and
selective catalytic reduction systems for NOX control. Ammonia was injected upstream of the SCR
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catalysts. Cold-side electrostatic precipitators (ESPs) are used on all three units for particulate control. A
wet FGD systems using limestone in a forced oxidation mode are used to reduce SO2 emissions on Unit 3.
Four samples were collected by plant personnel on September 17, 2007: one 5 gallon bucket of fly ash
from Unit 2 (TFA), one 5 gallon bucket of un-washed gypsum from Unit 3 (TAU), one 5 gallon bucket of
washed gypsum from Unit 3 (TAW), and one 5 gallon bucket of FGD waste water treatment plant filter
cake from Unit 3 (TFC). The washed gypsum sample (TAW) was used in the laboratory wallboard
simulation.
2.LI2 Facility W
This site is operated by American Electric Power (AEP) and has two 800 MW coal-fired boilers for a
plant total of 1,600 MW. The plant burns eastern bituminous coal in a dry-bottom pulverizer boiler.
Cold-side electrostatic precipitators (ESPs) are used on both units for particulate control, and wet FGD
systems are used to reduce SO2 emissions on two units. The wet FGD systems utilize limestone slurry
sorbents and a forced oxidation process. SO2 concentrations of the inlet FGD are approximately 1990
ppm with removal efficiencies of 98%. The plant has a Trona injection system for SO3 control, but this
system was not operating at the time of sampling.
Samples were collected as follows: dry FGD gypsum after water wash (WAW), moist FGD gypsum
before the water wash (WAU), wastewater treatment system filter cake (WFC), and dry fly ash (WFA).
Five gallon buckets of each of the samples were collected by plant personnel on 11/20/08. Samples were
delivered to ARCADIS on 11/28/07. The washed gypsum sample (WAW) was used in the laboratory
wallboard simulation.
2.1.13 Facility X
Wisconsin Electric Power Company, a subsidiary of Wisconsin Energy, owns and operates Pleasant
Prairie Power Plant located near Kenosha, Wisconsin. The plant has two 600 MW balanced-draft coal-
fired boilers designated units 1 and 2. Unit 2 was selected for inclusion in the NETL program because it
burns a variety of Powder River Basin low sulfur, sub-bituminous coals. In addition, this facility has the
ability to isolate one ESP chamber (1/4 of the unit) (Starns et al., 2002).
The primary pollution control equipment consists of SCR, cold-side ESPs, and a wet-FGD system. NOX
is controlled in the SCR by injecting ammonia in the presence of a catalyst. The forced oxidation FDG
system uses wet-limestone as a sorbent for SO2 control. This site also contains an additional mercury
oxidation catalyst.
Samples were collected as follows: dry FGD gypsum after water wash (XAW), moist FGD gypsum
before the water wash (XAU), FGD wastewater treatment system filter cake (XFC), and dry fly ash
(XFA). Five gallon buckets of each of the samples were collected by plant personnel and delivered to
ARCADIS on 6/16//08. The washed gypsum sample (XAW) was used in the laboratory wallboard
simulation.
2.1.14 Facility Aa
This test site has four boilers producing a total of 2,424 megawatt (MW) of power. The plant burns
eastern-bituminous coal in a dry-bottom pulverizer boiler. Cold-side electrostatic precipitators (ESPs) are
used on three units and hot-side ESP on one unit for particulate control. Unit 1 at this plant was burning
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medium sulfur coal and the SCR was operating. Unit 2 burns medium sulfur coal and has an SCR, but
this unit was not operating during the time of sampling. Unit 3 was burning high sulfur coal and the SCR
was operating. Unit 4 was burning low sulfur coal; the SCR was operating, and uses a hot-side ESP to
control particulate. A dry handling system is used to collect the fly ash from the ESPs.
Units 3 and 4 were connected to a single FGD system. The wet FGD systems utilize limestone slurry
sorbents and a forced oxidation process. Samples of the washed (AaAW) and un-washed (AaAU) FGD
gypsum were collected. Fly ash was collected from units 1 (AaFA), 3 (AaAB), and 4 (AaFC). Unit 2
was not operating at the time of sampling. The washed gypsum sample (AaAW) was used in the
laboratory wallboard simulation.
2.1.15 Facility Da
This test site has two supercritical boilers producing 2,240 megawatts (MW) of power. The plant burns
eastern-bituminous coal in a dry-bottom pulverizer boiler. The primary pollution control equipment
consists of low NOX burners, SCR, cold-side ESPs, and a wet-FGD system. NOX is controlled in the SCR
by injecting ammonia in the presence of a catalyst. The forced oxidation FDG system uses wet-limestone
as a sorbent for SO2 control. A dry handling system is used to collect the fly ash from the ESPs.
One five gallon bucket each of fly ash (DaFA), washed gypsum (DaAW), and FGD waste water treatment
plant filter cake (DaFC) were collected by plant personnel. Samples were received by ARCADIS on
12/12/2008. The washed gypsum sample (DaAW) was used in the laboratory wallboard simulation.
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Table 2-2. ADA fly ashes: elemental composition (by X-ray Fluorescence) and other
characteristics
Element
Al
As
Ba
Br
Ca
Cl
Cr
Cu
Fe
I
K
Mg
Mn
Na
Ni
Pb
Pxl
Se
Si
Sr
Sx2
Ti
V
Zn
Zr
Total Carbon (%)
Surface Area (m2/g)
LOI(wt%)
Reference
Fly Ash
Average %
14.7
0.010
0.110
BML
0.860
0.026
0.017
0.018
5.11
BML
2.46
0.637
0.015
0.346
0.011
0.008
0.087
BML
26.4
0.089
0.174
0.897
0.031
0.023
0.050
0.76
1.36
0.85
Pleasant Prairie
Baseline
Average
%
10.0
BML
0.695
BML
18.4
BML
0.016
0.022
4.31
BML
0.371
2.81
0.057
1.66
0.006
BML
0.560
BML
16.6
0.369
0.635
0.964
0.030
0.009
0.035
0.25
1.8
0.60
w/ACI
Average
%
10.2
BML
0.647
BML
16.6
0.045
0.013
0.022
4.28
BML
0.455
2.46
0.020
1.31
0.006
BML
0.508
BML
16.2
0.341
0.971
0.943
0.033
0.010
0.035
3.6
23
3.5
Brayton Point
Baseline
Average
%
13.4
BML
0.010
0.005
6.08
0.030
0.022
0.022
4.650
BML
1.85
0.800
0.041
0.511
0.015
BML
0.161
0.005
23.1
0.124
0.351
1.015
0.043
0.021
0.031
2.3
6.5
5.5
w/ACI
Average
%
12.4
BML
0.095
0.065
2.03
0.440
0.018
0.020
2.50
0.014
1.50
0.641
0.020
0.242
0.016
0.010
0.042
0.020
23.2
0.083
0.582
0.100
0.032
0.011
0.031
13
92
12
Salem Harbor
Baseline
Average
%
9.52
BML
0.091
BML
1.30
0.101
0.011
0.007
4.87
BML
1.250
0.785
0.045
0.270
0.009
0.005
0.086
0.005
21.9
0.042
0.335
0.453
0.029
0.013
0.019
7.8
28
21
w/ACI
Average
%
7.62
BML
0.099
BML
0.803
0.203
0.012
0.008
3.63
BML
0.977
0.420
0.021
0.293
0.009
BML
0.057
0.005
23.5
0.032
0.761
0.407
0.030
0.013
0.019
11
36
25
Notes: BML=below method limit (As<0.009%, CKO.006%, KO.006%, Pb<0.003%, Se<0.003%); Tx = phosphorus in
oxidized form such as phosphate; 2Sx = sulfur in oxidized form such as sulfate
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Table 2-3. Facility A (SNCR, facility B (SCR), facility E (SCR) and facility M CCRs: elemental
composition (by X-ray Fluorescence) and other characteristics
Element
Al
As
Ba
Br
Ca
Cl
Co
Cr
Cu
Fe
Ga
Ge
K
La
Mg
Mn
Mo
Na
Nb
Ni
Pb
Pxl
Rb
Sc
Se
Si
Sr
Sx2
Ti
V
Y
Zn
Zr
Total Caibon (%)
Surface Area (m2/g)
LOI(wt%)
Fly Ash
Facility A
With
SNCR %
11.4
0.013
0.096
0.009
3.53
0.542
0.007
0.018
0.019
4.68
0.005
BML
1.67
0.012
0.835
0.030
BML
0.375
BML
0.012
0.007
0.122
0.011
0.003
0.003
19.5
0.092
0.364
0.767
0.033
0.009
0.013
0.026
9.15
13.9
17.6
Without
SNCR %
12.8
0.014
0.124
0.008
3.60
0.610
0.006
0.017
0.018
5.20
0.005
BML
2.10
BML
0.931
0.052
BML
0.362
0.004
0.010
0.007
0.137
0.013
0.002
0.003
23.1
0.116
0.394
0.931
0.029
0.009
0.013
0.031
3.69
2.57
5.30
Fly Ash
Facility B
With SCR
%
10.8
0.014
0.128
BML
3.40
0.044
0.005
0.024
0.005
10.782
0.004
0.003
1.960
BML
0.869
0.025
BML
0.724
0.003
0.007
0.004
0.235
0.013
0.002
BML
21.2
0.111
0.711
0.596
0.019
0.003
0.014
0.021
5.74
5.30
10.8
Without
SCR %
11.0
BML
0.122
BML
3.11
0.030
BML
0.022
0.006
11.1
BML
BML
1.87
BML
0.774
0.024
BML
0.663
BML
0.005
BML
0.170
0.011
0.002
BML
21.2
0.099
0.512
0.570
0.019
0.005
0.013
0.020
2.37
6.20
11.0
Fly Ash
Facility E
With SCR %
15.7
0.010
0.116
BML
1.21
0.010
0.014
0.020
0.023
4.17
0.011
0.003
2.50
0.011
0.714
0.021
BML
0.350
0.004
0.021
0.013
0.060
0.016
0.003
BML
25.2
0.100
0.162
1.03
0.041
0.012
0.022
0.030
1.12
4.48
5.62
FGD Fly Ash
Mix Facility M
With SCR %
6.44
BML
0.021
BML
32.3
0.096
0.004
0.009
0.013
7.63
0.003
0.006
0.972
0.009
0.797
0.018
0.005
0.884
BML
0.044
0.007
0.056
0.006
0.008
BML
11.6
0.038
37.7
0.399
0.024
0.003
0.021
0.016
0.75
7.36
4.01
Notes: BML=below method limit (As<0.009%, CKO.006%, KO.006%, Pb<0.003%, Se<0.003%); Tx = phosphorus in
oxidized form such as phosphate; 2Sx = sulfur in oxidized form such as sulfate
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Table 2-4. ADA fly ashes: total content of mercury, arsenic, lead and selenium1
Sample ID
Brayton Point Baseline
Brayton Point (w/ACI)
Pleasant Prairie Baseline
Pleasant Prairie (w/ACI)
Salem Harbor Baseline
Salem Harbor (w/ACI)
Mercury
(ng/g)
651+ 6.8
1530+ 1.1
158+ 0.2
1180 + 1.2
528 + 5.2
412 +13
Arsenic
(Hg/g)
80.5 + 1.9
27.9+ 2.1
21.3+0.3
24.0 + 0.8
25.9 + 0.04
26.0 + 0.03
Lead
(u-g/g)
117 + 4.9
82.9 + 2.3
41.5+0.8
47.0 + 0.3
24.9 + 1.4
24.0 + 0.02
Selenium
(u-g/g)
51.4 + 1.7
152 + 6.2
BML
BML
41.9 + 0.06
44.0 + 0.04
1 All analyses according to EPA Method 3052. Mercury analysis performed by ARCADIS, arsenic, Pb, and Se analysis
performed by STL Savannah. All samples tested in duplicate.
BML = below method limit (4.0 ug/g)
ACI = Activated Carbon injection (sorbent for enhancing mercury capture)
Table 2-5. Facility A (SNCR, facility B (SCR), facility E (SCR) and facility M (SCR) CCRs :
total content of mercury, arsenic, lead and selenium
All analyses were conducted according to EPA Method 3052. Mercury analysis performed by ARCADIS, arsenic, Pb,
and Se analysis performed by STL Savannah.
Sample ID
Facility A Fly Ash (SNCR on)
Facility A Fly Ash (SNCR off)
Facility B Fly Ash (SCR on)
Facility B Fly Ash (SCR off)
Facility E Fly Ash (SCR on)
Facility M Fly Ash (SCR on)
Mercury
(ng/g)
602 + 5.2
380 + 7.0
88.3+27.4
114 + 9.6
396 + 57.4
121+0.2
Arsenic
(u-g/g)
70.8 + 1.4
88.2 + 0.3
82.3 + 12.6
90.0 + 3.4
50.1+0.1
106 + 6.8
Lead
(ng/g)
80.5+2.1
68.6 + 0.3
47.4 + 8.1
36.0 + 0.1
34.1+0.1
5.2 + 0.4
Selenium
(u-g/g)
25.6 + 0.2
21.9 + 0.6
2.5+0.4
2.9+ 0.0
24.0 + 2.9
91.0 + 6.5
Note: All samples tested in duplicate.
2.1.16 FGD Gypsum Sample from U.S. Gypsum
As discussed in Section 1.1.3, U.S. Gypsum (USG) performed an evaluation of mercury release from
FGD gypsum use in the production of wallboard. This evaluation was completed at five wallboard
manufacturing plants (Marshall et al., April 2005). The USG study was limited to mercury and did not
evaluate other metals. Therefore, samples of the FGD gypsum from the USG study were obtained for a
simulation test in the U.S. EPA laboratory. The first USG sample, corresponding to Task #1 of the
USG/DOE study, obtained for this study was from a power plant that burned high-sulfur bituminous coal,
used limestone as the FGD reagent, had in situ forced oxidation, online SCR, and did not practice fines
blow down (no fines removed) (Marshall et al., April 2008). The sub-sample consisted of the FGD
gypsum fed to the kettle calciner (the most likely point of release as discussed in Section 1.1.3). For
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further details on the characteristics of this sample see Marshall et al., April 2005. The second USG
sample obtained for this study was from the same plant during recent testing performed by DOE. This
plant was sampled during a time period during which the SCR was bypassed. Results for total content
analyses for mercury, arsenic, Pb, and Se are provided in Table 2-6.
Table 2-6. USG FGD gypsum samples: total content of mercury, arsenic, lead and selenium1
Sample ID
USG Sample #1
(Corresponds to DOE Task #1)
USG Sample #2
(Corresponds to DOE Task #2)
Mercury
(ng/g)
674 ± 0.4
468 ± 21
Arsenic
Og/g)
5.88 ±0.4
5.74 ± 0.26
Lead
Og/g)
2.31 ±0.03
2.08 ±0.09
Selenium
(ng/g)
5.4 ±0.7
5.26 ±0.98
1 All analyses according to EPA Method 3052. Mercury analysis performed by ARCADIS, arsenic, Pb, and Se analysis
performed by STL Savannah. All samples tested in duplicate.
2.2 Thermal Stability Protocols
A fixed-bed reactor design was used to simulate the thermal processes of concern in this study. Figure 2-1
provides a schematic of the general setup for simulating asphalt manufacturing, wallboard manufacturing,
and cement clinker manufacturing. For all simulations, samples consisting of various mixes and matrices
were loaded into shallow-bed containers and placed in the reactor. The fixed-bed reactor used for the
asphalt and wallboard simulation assays consisted of a horizontal quartz tube in a thermally controlled
furnace. The low temperature furnace was manufactured by Lindberg/Blue M (Model 55035) and had a
reactor size of 12" by 1" and a maximum temperature of 1200 °C (Figure 2-2). In the case of the high
temperature cement clinker manufacturing (1450 °C), a high temperature furnace was utilized. This high
temperature furnace was manufactured by Lindberg/Blue M (Model STF54233C) and had a reactor size
of 12" by 2" and a maximum temperature of 1500 °C (Figure 2-3).
In each simulation the tests were performed in duplicate. Samples were exposed to a flow rate of 400
cc/min of inlet flue gas consisting of 14% CO2, 3% O2, 5.6% H2O and 100 ppm NOX, except for the
wallboard simulation of the kettle calciner, in which the inlet gas consisted of N2. Kettle calciners are
indirectly fired and therefore the sample is not exposed to flue gases. The time in the fixed-bed reactor for
each simulation was one hour. The samples placed in the fixed-bed reactor, as well as the temperatures in
the processes varied for each simulation. For mercury, the effluent of the reactor was sampled using a
mini-impinger Ontario Hydro train (ASTM, 2002). For sampling the other metals, a Method 29 (EPA,
1996b) mini-impinger train was utilized. Table 2-7 outlines the differentiations in the various simulations.
Some simulations involved the addition of sand, limestone (CaCO3) or iron powder. All added materials
were certified reagent grade from Fisher Scientific.
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Low Temperature
Furnace
Method 29
or
OH Train
O = one-way valve
\^_) = two-way valve
lrThe same gas mix was used for the simulation of cement clinker and asphalt production (a flow rate of 400 cc/min of
inlet flue gas consisting of 14% CO2, 3% O2, 5.6% H2O and 100 ppm NOX,). The wall board similar used inlet gas of N2
since kettle calciners are indirectly fired and therefore the sample is not exposed to flue gas)
Figure 2-1. Schematic of the setup for simulating the production of cement clinker, asphalt, and
wallboard
Figure 2-2. Asphalt and wallboard simulation quartz reactor and furnace with sample
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Figure 2-3. High temperature cement simulation furnace with Method 29 mini-impinger train
Although the percentage of fly ash in asphalt is typically 5%, a mix containing 50% fly ash was tested for
the ADA fly ashes. During the initial phase of these studies a 50% mix was used as a conservative
approach to optimize the chances of detecting any volatilized mercury. The fly ashes from Facilities A, B
and E were tested using a mix containing 10% fly ash.
Table 2-7. Description of asphalt, wallboard and cement clinker simulations to test for metal
thermal stability
Simulation
Asphalt (ADA-ES samples) - Hg
Asphalt (Facilities A and B
samples) - Hg
Asphalt - As, Se, Pb
Wallboard
Cement clinker (high temp)
Sample
5 g of fly ash and 5 g of quartz sand
1 g of fly ash and 9 g of quartz sand
1 g of fly ash and 9 g of quartz sand
10 g of FGD gypsum kettle feed
1 g of fly ash, 8.55 g CaCO3, 0.3 g iron
powder and 0.2 g sand
Inlet Gas
Flue gases
Flue gases
Flue gases
Nitrogen
Flue gases
Temperature
170 °C
170 °C
170 °C
160 °C
1450 °C
Notes: all samples were tested in duplicate, exposed to gases/temperatures for one hour.
-------
Section 2
Page 2-16
2.3 Analytical Methods
2.3.1 Mercury (CVAA Method 7471A, Method 3052, Method 7473, Method SOB)
Gas phase mercury emissions from the simulation studies for the production of cement clinker, asphalt,
and USG gypsum testing were analyzed according to ASTM Method D6784-02, Ontario Hydro (OH),
with the following modifications. Due to spacing constraints, mini-impingers were used for sampling
instead of the large impingers described in the OH method. The method states that flow will be pulled
through the impingers using negative pressure; however, for these experiments the flow had to be pushed
through the impingers using positive pressure in order to not change the flow through the reactor. The
method also requires a dry gas meter to continuously measure flow, but instead a Gilian Gilibrator 2
(Sensidyne, Inc.) bubble flow meter was used and measurements were recorded every five minutes
throughout the entire sampling period. A silica gel trap was not used in this study, so the measurements
obtained were wet gas flow rates. Because the flue gas was not particle-laden, the filter apparatus setup
prior to the impingers (i.e., Method 5 filter) was not required. Analysis of the samples was performed as
outlined in Method D6784-02, Ontario Hydro.
Sample preparation for the cement clinker, asphalt, and USG gypsum solids was carried out by HF/HNO3
microwave digestion according to Method 3052 (EPA, 1996a). Mercury analysis of each digest was
carried out by Cold Vapor Atomic Absorption Spectrometry (CVAA) according to EPA SW-846 Method
7470A "Mercury in Liquid Waste (Manual Cold Vapor Technique)", (EPA, 1998a). A Perkin Elmer
FIMS 100 Flow Injection Mercury System was used for the analyses. The instrument was calibrated with
known standards ranging from 0.025 to 1 |o,g/L Hg. The method detection limit for Hg in aqueous samples
is 0.01
Gas phase Hg sampling for the repeated gypsum testing was performed using an EPA Method SOB (EPA
2008a) system. This technique used an iodated activated carbon tube to capture the Hg in the gas stream.
A Lumex RA-915+ Zeeman effect atomic adsorption Hg analyzer with a RA-91C combustion furnace
attachment to analyze the carbon tubes. The Hg analyzer was calibrated with known standards ranging
from 50 to 1000 ng of Hg. The method detection limit for Hg in the carbon tube is 0.2 ng. Blank samples
measured by the analyzer resulted in an average of 0.5 ng detectable concentration by the software.
Thermal Hg analysis was conducted of the FGD solids that were retested. This analysis used a modified
Method 7473 "Mercury in Solids and Solutions by Thermal Decomposition, Amalgamation, and Atomic
Absorption Spectrophotometry" (EPA, 1998b). The instrument used was a Lumex RA-915+ Zeeman
effect atomic adsorption Hg analyzer with a RA-91C combustion furnace attachment for solids analysis.
The instrument was calibrated with known standards ranging from 50 to 1000 ng of Hg. The method
detection limit for Hg in solids is 0.145 ng/g. Blank samples measured by the analyzer resulted in a 0.0
ng/g.
2.3.2 Arsenic, Selenium and Lead (ICP-MS, Method 3052, Method 6020)
Inductively coupled plasma-mass spectroscopy (ICP-MS) analysis for other elements of interest were
carried out by Oxford and STL laboratories.
Liquid samples were analyzed by ICP-MS as recovered from the Method 29 trains. Solid samples were
digested by EPA Method 3052 prior to ICP-MS analysis.
-------
Section 2
Page 2-17
2.3.2.1 Severn Trent Laboratories, Inc. (STL)
STL (Savannah, Georgia) was selected to carry out the solid digest ICP-MS analyses for this project.
Analysis for As, Se, and Pb was performed on an Agilent ICP-MS with octopole reaction system (ORS).
Mixed calibration standards were prepared for each metal at five levels ranging from 0.5 (ig/L to 100
jig/L.
2.3.2.2 Oxford Laboratories
Oxford Laboratories (Wilmington, North Carolina) was selected to carry out the ICP-MS analyses for this
project on the Method 29 impinger samples. Analysis for As, Se, and Pb was performed on an Agilent
ICP-MS with octopole reaction system (ORS). Mixed calibration standards were prepared for each metal
at five levels ranging from 0.5 (ig/L to 100 (ig/L.
-------
-------
Section 3
Page 3-1
Chapter 3
Results and Discussions
3.1 Cement Simulations
Cement simulation tests for As, Se, and Pb desorption were performed in duplicate on the ADA fly ashes
without the use of ACI. Because of its inherently high volatility, Hg was assumed to volatilize at the
1450°C and therefore recovery was not analyzed in the samples. Table 3-1 and Figure 3-1 present the
results of these tests. Therefore the focus was on the other metals (i.e., As, Se, and Pb).
The tests show excellent reproducibility and indicate that virtually all of the metals tested were volatilized
when exposed to a temperature of 1450°C.
Table 3-1. Results of cement simulations for arsenic, selenium, and lead (all values in ug/g unless
noted)
Metal
Arsenic
Selenium
Lead
Run
As received
Runl
Run 2
As received
Runl
Run 2
As received
Runl
Run 2
Brayton Point
(ng/g)
80.5 ±1.9
82.6
81.8
103%
102%
51.4 ±1.7
53.6
52.6
104%
102%
117 ±4.9
118.6
106.0
101%
90.4%
Pleasant Prairie
(Mg/g)
21.3 ±0.3
20.6
20.6
96.8%
96.6%
BML
BML
BML
NA
NA
41.5 ±0.8
40.6
38.8
97.9%
93.5%
Salem Harbor
(Mg/g)
25.9 ±0.04
27.5
25.2
106%
97.5%
41.9 ±0.8
39.8
43.6
94.9%
104%
24.9 ±1.4
21.5
23.4
86.3%
94.1%
BML - Below method limit (4.0
NA = not applicable
-------
Section 3
Page 3-2
•a
9)
N ^.
IE in
•S c
JS =
o •-
> o
«
c o
o _ro^
100%
80%
60%
"5 §• 400/0
20%
0%
Brayton Point Pleasant Prairie Salem Harbor
D Arsenic n Selenium n Lead
Note: Se was not tested for Pleasant Prairie fly ash; the amount in the baseline
fly ash was below minimum detection levels.
Figure 3-1. Results of cement simulations for arsenic, selenium, and lead
3.2 Asphalt Simulations
5.2.7 Asphalt Simulation Tests for Mercury Thermal Stability on ADA Fly Ashes
Results for duplicate asphalt simulation tests using the ADA fly ashes are presented in Table 3-2. In all
cases, the majority of the Hg was retained in the solid after simulation, with minimal measured
volatilization of Hg (<10% in all cases). Generally, the addition of carbon increased the tendency for Hg
to be retained in the solids at the temperature tested. Total Hg volatilized from samples with activated
carbon injection was <1% for all samples tested. Figure 3-2 shows the results of these experiments that
have been normalized by adjusting the mass balance to 100%. Mass balances were approximately 90%
for all tests except for the Pleasant Prairie Baseline tests (-67%). No reason for the lack of closure for Hg
for this sample was found, though it is noted that the as-prepared sample had the lowest initial Hg value
of these fly ashes.
For confirmatory purposes, measurements of volatilized Hg were taken from Method 29 total metals
analyses for comparison to the Ontario Hydro values for the Brayton Point fly ashes. Table 3-3 shows the
comparison. The Method 29 runs agree well with the total Hg values obtained from the Ontario Hydro
tests, indicating minimal volatilization of Hg.
-------
Table 3-2. Asphalt simulation test results for mercury on ADA fly ashes
Section 3
Page 3-3
Brayton Point
Baseline
Brayton Point
ACI
Pleasant Prairie
Baseline
Pleasant Prairie
ACI
Salem Harbor
Baseline
Salem Harbor
ACI
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
As Prepared
ng/g)
650.6 ±6.8
1529.6 ±1.1
157.7 ±0.2
1180.1 ±1.2
528.5 ±5.2
411.5 ±12.6
After
Simulation
(Solid) ng/g
526
606
1,340
1,420
105
95.5
1,110
1,100
488
486
388
387
HgV
ng/g
31.7
5.3
BML
BML
BML
BML
1.3
2.2
0.1
BML
BML
BML
Hg°gas
ng/g
8.0
1.8
BML
BML
1.9
7.3
2.3
o o
J.J
BML
BML
0.5
BML
Total Percent
Volatilized Hg
6.1%
1.1%
0.0%
0.0%
1.2%
4.7%
0.3%
0.5%
0.0%
0.0%
0.1%
0.0%
Mass
Balance
86.9%
94.7%
87.3%
93.2%
67.8%
65.2%
94.6%
93.9%
92.4%
91.9%
94.4%
94.0%
BML=below method limit (Hg<0.05 ng/g)
3.2.2 Asphalt Simulation Tests for Non-Mercury Metals Thermal Stability on ADA
Fly Ashes
Since significant amounts of Hg were not significantly released from the ADA fly ash samples (and Hg is
the most volatile of the metals being investigated), only one of the three ADA facility sites was chosen to
evaluate the release of other metals. The Brayton Point facility samples were chosen because they
contained the highest amount of As and Se. Asphalt simulation tests for As, Se, and Pb volatilization were
performed on the Brayton Point fly ashes. Table 3-4 summarizes the results. The tests showed no non-Hg
metals in the gas phase, indicating that all the As, Se, and Pb were retained in the solid. While the mass
balances between the solids after simulation and the as-prepared sample prior to testing are not ideal
(varying between 50 and 150%), they generally agree and support that the metals are retained in the solids
for the asphalt simulation.
-------
ection 3
age 3-4
w 1 00%
o § 90%
S) | 80%-
1 ? 70%-
" a) 60%
Q) 0) UU /0
°- 5 50%
•C Q)
N £ 40%
| > 30%
o o 20%
* | 10%
0%
^^fl
5.9
—
1
o| 1^
w
' — /
10. 01
c
^=j
5.6°
/
0
s
1
c
0
9.6C
n
0
^
=
1(
>
I0.01
9
^ — /
9.9°,
Brayton Brayton Peasant Peasant Salem Salem
Point Point w/ Prairie Prairie w/ Harbor Harbor w/
Baseline ACI Baseline ACI Baseline ACI
n Retained in Solid • Volatilized
Figure 3-2. Asphalt simulation test results for mercury by Ontario Hydro Method on ADA fly ashes
Table 3-3. Comparison of mercury by Method 29 and Ontario Hydro for Brayton Point fly ashes
Sample
Brayton
Point
Baseline
Brayton
Point w/ACI
Run
Runl
Run 2
Runl
Run 2
As Prepared
ng/g
651 ±6.8
1530±1.1
Gas-Phase
Mercury
ng/g
72.0
23.0
20.0
23.0
Percent
Volatilized
11.1%
3.5%
1.3%
1.5%
Method 29
Average
7.3% ±5.3%
1.4% ±0.1%
OH Average
3.6% ±3.5%
0.0% ±0%
-------
Table 3-4.
Section 3
Page 3-5
Results for asphalt simulations of Brayton Point fly ashes for arsenic, selenium, and
lead
Metal
Arsenic
Selenium
Lead
Run
Baseline Test 1
Baseline Test 2
ACI Test 1
ACITest2
Baseline Test 1
Baseline Test 2
ACI Test 1
ACI Test 2
Baseline Test 1
Baseline Test 2
ACI Test 1
ACI Test 2
As Received
Hg/g
80.5 ±1.9
27.9 ±2.1
51.4 ±1.7
152 ±6.2
117 ±4.9
82.9 ±2.3
As Prepared
Hg/g
90.5 ± 6.6
41.9±0.15
47.7 ±2.6
156.7 ±9.3
245 ±71
194 ±0.68
After
Simulation
(solid) fig/g
85.5 ±2.0
95.5 ±22
26.0 ± 0.07
50.1 ±8.6
45.7 ±8.0
53.7±13
83.1 ±7.3
208 ± 47
318±25
279 ± 55
227 ± 74
291 ±14
Volatilized
Metal (gas
phase) fig/g
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
Mass
Balance
94.5%
106%
62.1%
120%
95.8%
113%
53.1%
132%
128%
113%
117%
150%
BML=below method limit (As<4.0 ug/g, Pb<0.6 ug/g, Se<4.0 ug/g)
3.2.3 Asphalt Simulation Tests for Mercury Thermal Stability on Non-ADA Fly Ashes
Asphalt simulations were run using the non-ADA fly ashes. These samples were from utilities not using
ACI; rather, the samples were taken from utilities using SNCR (Facility A) and SCR (Facilities B and E)
for NOX control, or none (Facility M). Table 3-5 shows the results of these experiments. Mass balances
for all runs were excellent (92.5 to 101%). Figure 3-3 shows the results of these experiments that have
been normalized by adjusting the mass balance to 100%. As was the case for the ADA fly ashes, minimal
Hg loss upon heating was found for the fly ashes from Facilities A and E. Facility B, however,
demonstrated high Hg volatility (-70-90% loss upon heating). Facility M showed moderate amounts of
the Hg being volatilized.
As with the Brayton Point fly ash, Method 29 sampling for Hg was conducted to confirm the results
obtained using the Ontario Hydro methodology. These comparisons are shown in Table 3-6. While
differing slightly from the Ontario Hydro results, the Method 29 experiments confirm that the Facility B
samples showed significantly greater loss of Hg on heating than the other fly ashes tested.
-------
Section 3
Page 3-6
Table 3-5. Mercury results by Ontario Hydro Method for non-ADA fly ashes
Sample
Facility A
SNCROn
Facility A
SNCROff
Facility B
SCR On
Facility B
SCR Off
Facility E
SCR On
Facility M
Run
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
As
Prepared
ng/g
602
380
88.3
114
396
121
After
Simulation
(Solid) ng/g
576
583
366
358
9.2
9.3
27.0
23.1
365
326
57.5
Hg2^
ng/g
5.2
4.6
9.8
8.5
36.5
37.6
37.5
40.4
15.0
22.6
NA
Hff°
S gas
ng/g
6.0
5.8
8.8
13.5
41.3
38.5
42.8
42.2
14.7
17.6
NA
Total Percent
Volatilized Hg
1.9%
1.7%
4.9%
5.8%
88.1%
86.2%
70.4%
72.4%
7.5%
10.1%
26.6%
Mass
Balance
97.5%
98.6%
101%
100%
98.5%
98.6%
94.1%
92.7%
99.6%
92.5%
74.2%
Facility M was sampled by Method 29 under Asphalt Simulation Conditions.
Gas phase total Hg emissions for Facility M were 32.1 ng/g.
NA = not applicable / no gas phase speciation
-------
Section 3
Page 3-7
01
E «•
01 -
O) O
•r Ol
& O)
^" CO
= 5.
(B
Facility A
SNCRon
Facility A Facility B SCR Facility B SCR Facility E SCR Facility M
SNCR off on off on SCR on
1 Retained in Solid
1 Volatilized
Figure 3-3. Mercury results by Ontario Hydro Method for non-ADA fly ashes
Facility M was sampled by Method 29. Series 1 = Retained in Solid, Series 2 = Gas Phase under Asphalt simulation
Conditions.
-------
Section 3
:3-8
Table 3-6. Comparison of mercury by Method 29 with Ontario Hydro for facility B fly ashes
Facility B
SCR on
Facility B
SCR off
Runl
Run 2
Runl
Run 2
As Prepared,
ng/g
88.3 ±27.4
114.0 ±9.6
Method
29Gas-Phase
Mercury, ng/g
44.2
37.8
75.2
57.5
Method 29
Percent
Volatilized
50.1%
42.8%
65.9%
50.5%
Ontario Hydro
Gas-Phase
Mercury, ng/g
77.8
76.1
80.3
82.6
Ontario Hydro
Percent
Volatilized
89.4%
89.1%
74.8%
78.1%
No clear-cut reason for the higher loss of Hg seen for the Facility B sample can be demonstrated. The
SCR design is of the in-furnace variety, contact between fly ash and SCR catalyst occurred even during
tests when SCR was not in use. Speculation is that contact between fly ash and SCR catalyst occurred
even when no ammonia injected. However, too little information is available to make a more definitive
statement. In addition, a similar effect was not found for the sample from Facility E (which is also has
SCR in use). Therefore, these results suggest that additional research may be warranted on a wider range
of samples to evaluate potential Hg loss from use of CCR in asphalt applications.
3.2.4 Asphalt Simulation Tests for Non-Mercury Metals Thermal Stability on
Non-ADA Fly Ashes
Because of the high volatility seen for Hg in the Ontario Hydro analyses for the Facility B fly ash, the
Facility B fly ash was selected for testing of volatility of As, Se, and Pb. Results from Method 29 tests
are shown in Table 3-7. As was the case for the Brayton Point fly ash, mass balances from the tests show
a high degree of variability (41-300%). However, once again no metals were detected in the gas phase,
indicating that As, Se, and Pb were retained in the solid after heating. The Pb results likely indicate some
degree of contamination of the solid sample prior to analysis. However, As, Se, and Pb were not detected
in the gas phase for the Facility B sample.
-------
Table 3-7.
lead
Section 3
Page 3-9
Results for Asphalt Simulations of Facility B Fly Ashes for arsenic, selenium, and
Metal
Arsenic
Selenium
Lead
Run
SCR on Test 1
SCR on Test 2
SCR off Test 1
SCR off Test 2
SCR on Test 1
SCR on Test 2
SCR off Test 1
SCR off Test 2
SCR on Test 1
SCR on Test 2
SCR off Test 1
SCR off Test 2
As Prepared
Hg/g
95.8
96.0
75.6
75.8
5.4
5.4
13.5
13.5
236
237
81.2
81.4
After
Simulation
(solid) fig/g
85.4
89.6
88.2
104
5.6
5.7
6.6
5.6
292
180
239
215
Volatilized
Metal (gas
phase) fig/g
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
Mass
Balance
89.1%
93.3%
117%
137%
104%
105%
48.8%
41.4%
124%
76.0%
295%
264%
BML=below method limit (As<4.0 ug/g, Pb<0.6 ug/g, Se<4.0 ug/g)
Table 3-8. Results for asphalt simulations of facility M fly ash for mercury, arsenic, selenium,
and lead
Metal
Arsenic
Hg/g
Selenium
Hg/g
Lead fig/g
Mercury
ng/g
Run
SCR on Test 1
SCR on Test 2
SCR on Test 1
SCR on Test 2
SCR on Test 1
SCR on Test 2
SCR on Test 1
SCR on Test 2
As Prepared
101
110
5.5
4.9
86.4
95.6
121
120
After
Simulation
(solid)
106
108
6.0
5.5
91.2
90.6
57.8
57.2
Volatilized
Metal
(gas phase)
BML
BML
BML
BML
BML
BML
31.6
32.5
Amount
Volatilized
0
0
0
0
0
0
26
27
Mass
Balance
105
97.5%
111
113
106
94.8%
74%
74%
Note: As, Se, and Pb concentrations in ug/g, Hg concentration in ng/g
BML = below method limit (As<4.0 ug/g, Pb<0.6 ug/g, Se<4.0 ug/g)
-------
Section 3
Page 3-10
5.2.5 Correlation of Carbon Content and Mercury Volatilization
In general, Hg volatilization appears to decrease with increasing carbon content. This was the case for 18
of the 22 samples evaluated. The four facilities that did not fit this trend are from the facility that has the
in-furnace SCR system. The mercury results were normalized using the ratio of the amount volatilized to
the total Hg remaining in the solids plus the amount of mercury volatilized. Figure 3-4 provides these
results along with the equation that was derived. The significant figures are not considered more than 1
given the uncertainties. Recommendations for future work include using a larger sample size to evaluate
potential Hg loss during asphalt production and to evaluate if the correlation for carbon content and Hg
loss is confirmed.
12.0%
0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0%
Percent of Carbon in Fly Ash
Note - The % Hg volatilized is "normalized" by dividing by the total amount of mercury in the solid and
gas phase. Significant figures are not greater than one.
Figure 3-4. Mercury volatilization as a function of carbon content
3.3 Wallboard Simulations
Sanderson et al., (2008) provide the most extensive study to date on the fate of Hg when FGD gypsum is
used as feedstock for wallboard production. Testing of full-scale production facilities is considered more
reliable than laboratory testing to simulate wallboard production. However, the study did not include
other metals. Therefore, laboratory simulation of wallboard production was conducted. Results from
Sanderson et al., (2008) indicate that the process where Hg loss is more likely to occur is the kettle
calciner. Therefore, laboratory simulation of wallboard production was conducted evaluating Hg and
other metals with the focus on trying to simulate potential loss across the kettle calciner. Only FGD
gypsum samples were used in this simulation since this is the material used in the production of wallboard
(and not fly ash). This research was conducted in two phases. The first phase resulted in unacceptable
-------
Section 3
Page 3-11
mass balance for Hg. The results for the other metals are considered acceptable. Consequently,
additional testing was conducting in a second phase using more recent FGD samples. The results from
this work are reported along with the results from phase 1. Please note, only the results from non-Hg
metals for phase 1 are considered reliable. However, we have not excluded the Hg results from phase 1.
3.3.1 Wallboard Simulation Tests for Mercury Th ermal Stability on USG FGD
Gypsum
Results for multiple wallboard simulations using the two samples received from U.S. Gypsum are shown
in Table 3-9. As noted, the results for the first USG sample had poor mass balance. The amount of Hg
remaining in the solids ranged between 90 to 99% which agrees fairly well with the results reported by
USG (-98.6%). The results for the second USG sample had a better mass balance than the first sample;
however, the mass balances were still less than ideal. The gas-phase results, however, indicate that the
samples lost between 75 and 105% of the Hg compared to a USG-reported value of-2.3%. The gas
phase results are not considered reliable as indicated by the poor Hg mass balance results. Therefore, and
additional testing was conducted.
Table 3-9. Results of wallboard simulation tests for mercury
Pre test
(solid), ng/g
USG-1
USG-2
Runl
Run 2
Run3
Run 4
Runl
Run 2
674.0 ± 0.4
467.9 ±21.3
After
Simulation
(solid), ng/g
664
626
627
606
98.4
81.9
Volatilized
Mercury (gas
phase), ng/g
518
602
606
705
478.7
334.9
Percent
Volatilized3
77%
89%
90%
105%
102%
71.6%
Percent
Remaining
in Solid
99%
93%
93%
90%
21.0%
17.5%
Mass
Balance
175%
182%
183%
195%
123%
89.1%
"These results are not considered reliable as indicated by the Hg mass balance. Therefore, additional
testing was conducted.
3.3.2 Wallboard Simulation Tests for Non-Mercury Metals Thermal Stability on USG
FGD Gypsum
Results for duplicate wallboard simulations using samples received from U.S. Gypsum are shown in
Table 3-10. In general, the results for the first USG sample showed that the non-Hg metals including As,
Se and Pb did not volatilize from the sample during the wallboard simulation test. While the mass
balances between the solids after simulation and the as-prepared sample prior to testing are not ideal
(varying between 116 and 128%). However, the results tend to suggest that As and Se are more likely
retained in the FGD gypsum and less likely to be volatilized during the kettle calcining process.
Table 3-10. Results of wallboard simulation tests for arsenic, selenium, and lead
Metal
Run
As Prepared
After
Volatilized
Mass
-------
Section 3
Page 3-12
Arsenic
Selenium
Lead
USG-1
USG-2
USG-1
USG-2
USG-1
USG-2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Runl
Run 2
Hg/g
5.88
5.74
5.39
5.26
2.31
2.08
Simulation
(solid) fig/g
7.02
7.34
5.89
5.79
6.27
6.62
5.17
5.30
2.95
2.82
2.04
1.97
Metal (gas
phase) fig/g
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
BML
Balance
119%
125%
102%
100%
116%
123%
98.2%
101%
128%
122%
98.2%
94.7%
BML=below method limit (As<0.4 ug/g, Pb<0.06 ug/g, Se<0.4 ug/g)
3.3.3 Additional Wallboard Simulation Tests for Mercury Thermal Stability on
Gypsum Samples
Because of the unacceptable Hg mass balance in the previous wallboard simulation, additional testing was
conducted using FGD samples from eight different facilities. Sufficient quantity of the USG FGD
gypsum was not available to be used in the repeated wallboard simulation tests. The experimental
method was modified to include additional quality assurance. Vapor phase Hg was collected with iodated
carbon sorbent tubes using Method SOB, at a constant temperature of 160 °C. Method 7473 was used to
analyze the Hg content of the solid gypsum. For each sample, three replicates were conducted. The
amount of volatilized Hg was calculated using the Hg trapped on the carbon tubes and the solid gypsum
before heating. The amount remaining in solid was calculated using the solid gypsum before and after
heating. Table 3-11 shows the averages and standard deviation for each sample. Figure 3-6 shows the
amount of Hg retained in solid and Hg volatilized. Appendix C has more detailed results.
This series of tests gave improved mass balance results compared to the earlier testing to loss of Hg
across the kettle calciner. The results (Figure 3-5) indicate potential Hg loss of 9 to 48%. The USG
results from wallboard manufacturing facilities indicate Hg loss across the kettle calciner (excluding the
Texas lignite sample) of 2 to 50% (found in Table 1-3). This is considered confirmation of the previous
USG research with emphasis on the degree of variability across samples.
-------
Section 3
Page 3-13
Table 3-11. Results of additional wallboard simulation tests for mercury
Sample
ID
AaAW
DaAW
NAW
OAW
SAW
TAW
WAW
XAW
Average
StDev
Average
StDev
Average
StDev
Average
StDev
Average
StDev
Average
StDev
Average
StDev
Average
StDev
Pre-test
(solid),
ng/g
538
20.9
653
15.0
466
9.27
44.3
2.12
312
6.75
765
58.3
938
18.6
1,030
6.24
After
Simulation
(solid), ng/g
426
24.3
529
6.86
228
17.8
32.0
1.29
159
27.8
519
17.5
865
26.1
815
14.0
Volatilized
Mercury
(gas phase),
ng/g
122
24.5
134
3.86
204
7.51
15.5
0.68
151
17.3
198
64.6
87.5
44.4
212
16.8
Percent
Volatilized
23%
5%
21%
1%
44%
2%
35%
2%
48%
6%
26%
8%
9%
5%
21%
2%
Percent
Remaining in
Solid
79%
5%
81%
3%
49%
3%
72%
6%
51%
8%
68%
6%
92%
3%
79%
2%
Mass
Balance
102%
4%
102%
4%
93%
3%
108%
7%
99%
3%
94%
4%
101%
5%
100%
2%
-------
Section 3
Page 3-14
120%
AaAW DaAW NAW OAW SAW
Sample ID
TAW WAW
XAW
D Retained in Solid D Volatilized
Figure 3-5. Results for additional wallboard simulation tests for mercury
3.3.4 Wallboard Simulation Tests for Mercury Thermal Stability at Various
Temperatures
Gypsum sample DaAW was tested at three temperatures (120°C, 140 °C, 160 °C) to compare the amount
of volatilized Hg versus temperature during the simulation test. Method 3 OB and Method 7473 were
used. Table 3-12 and Figure 3-7 display a summary of the results and show that the amount of volatilized
Hg increases as temperature increases. The linear trend line in Figure 3-7 shows an R-squared value of
0.9269. Detailed results are included in Appendix C. Therefore, the operating temperature of the kettle
calciner is important to consider in predicting potential loss at a production facility.
Table 3-12. Results for wallboard simulation tests on sample DaAW at various temperatures
Furnace
Temperature,
°C
120
i An
160
Average
StDev
Average
StDev
Average
StDev
Pre-test
(solid),
ng/g
551
8.85
621
34.7
653
15.0
Simulation
(solid),
ne/e
532
5.13
588
23.3
529
6.86
Volatilized
Mercury
(gas
phase),
ng/g
10.8
2.64
42.1
1.80
134
3.86
Percent
Volatilized
2%
0%
7%
1%
21%
1%
Percent
Remaining
in Solid
97%
1%
95%
2%
81%
3%
Mass
Balance
99%
2%
102%
2%
102%
4%
-------
Section 3
Page 3-15
20% -
3
0)
"o
0)
o>
« 10% -
0)
0)
0% -
1C
Sample Da AW
. N i
R2 = 0.9269 ./
s'
s/
//
/^.
/^
^
DO 110 120 130 140 150 160 170
Furnace Temperature (degrees C)
Figure 3-6. Results for wallboard simulation tests at various temperatures
-------
-------
Section 4
Page 4-1
Chapter 4
Conclusions and Future Considerations
Approximately 40% of the 126 million tons of CCRs produced in the U.S. as of 2006 were utilized in
agricultural, commercial, and engineering applications. The remainder (i.e., 75 million tons) was managed
in either landfills or impoundments. The physical and chemical characteristics of CCRs make them
potentially suitable as replacements for materials used in a wide range of products including cement,
concrete, road base, and wallboard. Use of CCRs as an alternative to virgin materials helps conserve
natural resources and energy, as well as decrease the amount of CCRs being land disposed.
This study evaluated the potential loss of Hg and other metals for the production of cement clinker,
asphalt, and wallboard. When this study was originally started, there were no controls for Hg from the
production of cement. Subsequent to this research, EPA has proposed (74 FR 21136m May 6, 2009)
regulations to reduce mercury emissions from cement kilns, which may result in use of air pollution
control technology similar to that used at coal-fired power plants (e.g, wet scrubbers and sorbents for
enhanced Hg capture). The addition of air pollution control at cement kilns should not affect the ability to
use fly ash or FGD gypsum in the production of clinker. However, to avoid installation of air pollution
control, kiln inputs (such as fly ash) containing Hg may be avoided which could impact usage of some
CCRs.
The focus of the laboratory simulation of cement clinker production using a high-temperature Lindberg
was on non-Hg metals (i.e., As, Se, and Pb). The results indicate that all of the As, Se and Pb are
volatilized as a result of the high temperatures (1450 °C) the samples are exposed to during this process.
With potential changes in air pollution control at cement plants, there will be less Hg and other metals
being emitted. However, these metals will be retained in the cement kiln dust and the air pollution control
residues. Ensuring that these metals are not later released based on how the air pollution control residues
(FGD gypsum and cement kiln dust) are managed, requires additional research to evaluate the potential
leaching of Hg and other metals for the conditions that the residues are managed. Currently there are no
federal requirements for lining of landfills used for cement kiln dust disposal. In addition, some sites are
using cement kiln dust in engineering and commercial applications.
The asphalt manufacturing simulation results presented indicate that all of the non-Hg metals including
As, Se and Pb are retained in the samples after exposure. Mercury showed minimal volatilization from the
ADA samples as well as the samples from Facilities A and E. The Facility B results, however, showed
significant loss of Hg into the gas-phase as a result of exposure to the asphalt manufacturing conditions.
Facility B is the only facility included in this study that has an in-furnace SCR design. This design type
necessitates that the fly ash come in contact with the SCR catalyst surface regardless of whether ammonia
is being injected or not. Further investigation of fly ashes from facilities with an in-furnace SCR design is
probably warranted.
Sanderson et al., (2008) provide the most extensive study to date on the fate of Hg when FGD gypsum is
used as feedstock for wallboard production. Testing of full-scale production facilities is considered more
reliable than laboratory testing to simulate wallboard production. However, the study did not include
other metals. Therefore, laboratory simulation of wallboard production was conducted as part of this
-------
Section 4
Page 4-2
study. Results from Sanderson et al, (2008) indicate that the process where Hg loss is more likely to
occur is the kettle calciner. Therefore, laboratory simulation of wallboard production was conducted
evaluating Hg and other metals with the focus on trying to simulate potential loss across the kettle
calciner. Only FGD gypsum samples were used in this simulation since this is the material used in the
production of wallboard (and not fly ash). This research was conducted in two phases. The first phase
resulted in unacceptable mass balance for Hg. The results for the other metals are considered acceptable.
Consequently, additional testing was conducting in a second phase using more recent FGD samples.
The first phase of testing suggests that As and Se are more likely retained in the FGD gypsum and less
likely to be volatilized during the kettle calcining process. The second phase of testing provided
improved Hg mass balance results. The results (Figure 3-5) indicate potential Hg loss of 9 to 48%. The
USG results from wallboard manufacturing facilities indicate Hg loss across the kettle calciner (excluding
the Texas lignite sample) of 2 to 50% (found in Table 1-3). This is considered confirmation of the
previous USG research with emphasis on the degree of variability across samples. Additional testing
was conducted at three different temperatures that the kettle calciner can be operated. The linear trend
line in Figure 3-7 shows an R-squared value of 0.9269. Therefore, the operating temperature of the kettle
calciner is important to consider in predicting potential loss at a production facility.
In interpreting the results from this study, please note that the samples are not considered to be a
representative sample. Samples were obtained on a voluntary basis and represent a minor fraction (<1%)
of U.S. boilers at coal-fired power plants. However, every effort was made to obtain samples that are
considered typical of the air pollution control configurations to be more widely used as the result to
changes in U.S. EPA and state regulations.
The results from this laboratory study demonstrate the varying degree of volatility for mercury, arsenic,
Se and Pb in CCRs depending on the process temperature being used. A high temperature process such as
cement clinker production has the ability to release all four metals from fly ash when exposed to the high
temperatures found in production. Laboratory simulation of the asphalt and wallboard production
processes showed a significant release of mercury during heating, but the temperatures were too low to
volatilize the arsenic, Se, or Pb. Whereas, the Hg loss for wallboard production suggest non-Hg metals
being retained in wallboard with a potential Hg loss of 9 to 48%. However, the actual mass emission
rates must be considered when determining potential concern to human health and the environment.
-------
Section 4
Page 4-3
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-------
-------
Section 5
Page 5-1
Chapter 5
Quality Assurance / Quality Control
5.1 Quality Indicator Goals
Data quality indicator goals for critical measurements in terms of accuracy, precision and completeness
are shown in Table 5-1.
Table 5-1. Data Quality Indicator Goals
Measurement
As, Se, and Pb Concentration
Hg Concentration
Method
ICP/6010B
CVAA/7470A
Accuracy
90-110%
80 - 120 %
Precision
10%
10%
Completeness
>90%
>90%
Accuracy was determined by calculating the percent bias from a known standard. Precision was
calculated as relative percent difference (RPD) between duplicate values and relative standard deviation
(RSD) for parameters that have more than two replicates. Completeness is defined as the percentage of
measurements that meet DQI goals of the total number measurements taken. Types of QC samples used
in this project included blanks, instrument calibration samples, replicates, and matrix spikes
5.2 Ontario Hydro and Method 29 Mercury Analyses
Accuracy and precision for the Ontario Hydro samples for Hg concentration in the process gas
determinations were made using replicates and matrix spike analyses. The Figure 5-1 shows the spike
recoveries obtained during the analysis of the recovered fractions. Figure 5-2 shows the spike recoveries
for Hg obtained during the Method 29 sampling. The Ontario Hydro samples had a completeness of 98%
and the Method 29 samples had a completeness of 94%.
Required QC samples for metals and Hg sampling trains are detailed in EPA Method 29 and the Ontario
Hydro Method. QC samples required for CVAA analysis are detailed in 7470A. The Hg analyzer
software has been programmed with the acceptance criteria for Method 7470A. All calibrations and
samples analysis parameters have passed the QA/QC criteria and may be considered valid samples. The
Ontario Hydro samples had a completeness of 98% and the Method 29 samples had a completeness of
94%.
5-1
-------
Section 5
•5-2
o
140%
120%
100%
80%
60%
40%
20%
0%
• KMNO4 fraction —•—KCI fraction H2O2 fraction Acceptance criteria
Figure 5-1. Ontario Hydro spike recovery for multiple runs
-------
Section 5
Page 5-3
140%
120%
100%
80%
60%
40%
20%
0%
10
• H2O2/HNO3 fraction —•— KMNO4 fraction Acceptance Criteria
Figure 5-2. Method 29 mercury spike recoveries for multiple runs
5.3 Method 29 Analyses for Arsenic, Lead, and Selenium
QA/QC samples for the determination of As, Pb, and Se included blanks, replicates, and matrix spikes.
Table 5-2 presents accuracy of the matrix spike recovery data for the Method 29 cement kiln simulation
metals analyses. Table 5-3 presents the accuracy of the matrix spike recovery data for the asphalt
simulation testing. Table 5-4 presents the accuracy of the matrix spike recovery data for the gypsum
wallboard simulation testing.
Table 5-2. Method 29 Matrix Spike Recoveries for Arsenic, Lead, and Selenium for the Cement
Kiln Simulations
Facility Name
Brayton Point BL
Pleasant Prairie BL
Salem Harbor BL
As
111%
104%
92%
Se
104%
102%
90%
Pb
108%
109%
89%
5-3
-------
Section 5
•5-4
Table 5-3. Method 29 Matrix Spike Recoveries for Arsenic, Lead, and Selenium for the Asphalt
Simulations
Facility Name
Brayton Point BL
Brayton Point ACI
Facility B (SCR on)
Facility B (SCR off)
USG-1
USG-2
As
109%
109%
91%
93%
106%
101%
Se
111%
103%
92%
97%
107%
103%
Pb
101%
111%
91%
110%
108%
100%
Table 5-4. Method 29 Matrix Spike Recoveries for Arsenic, Lead, and Selenium for the Gypsum
Wallboard Simulations
Facility Name
USG-1
USG-2
As
106%
101%
Se
107%
103%
Pb
108%
100%
Overall completeness for the Method 29 non-Hg metals matrix spike samples was 30 valid out of 33 total
matrix spikes or 91%.
-------
Section 6
Page 6-1
Chapter 6
References
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Use Survey, http://acaa.affiniscape.com/associations/8003/files/2003_CCP_Survey (10-l-04).pdf
Accessed July 2008.
ASTM. Standard test method for elemental, oxidized, particle-bound, and total mercury in flue gas
generated from coal-fired stationary sources (Ontario-Hydro method), Method D 6784-02,
American Society for Testing and Materials, 2002.
Garrabrants, A. C., F. Sanchez, and D. S. Kosson. Changes in constituent equilibrium leaching and pore
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emissions from coal-fired electric utility boilers: interim report. EPA-600/R-01-109, U.S.
Environmental Protection Agency, December 2001.
Marshall, Jessica, Gary Blythe and Mandi Richardson. Fate of mercury in synthetic gypsum used for
wallboardproduction, topical report, task 1 wallboardplant test results. U.S. Department of
Energy, Pittsburgh, PA, Cooperative Agreement Number DE-FC26-04NT42080, April, 2005.
Marshall, Jessica, Gary Blythe and Mandi Richardson. Fate of mercury in synthetic gypsum used for
wallboard production, topical report, task 2 wallboard plant test results. U.S. Department of
Energy, Pittsburgh, PA, Cooperative Agreement Number DE-FC26-04NT42080, August, 2005.
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wallboard production, topical report, task 3 wallboard plant test results. U.S. Department of
Energy, Pittsburgh, PA, Cooperative Agreement Number DE-FC26-04NT42080, August, 2005.
Meischen, S. The effect of mercury controls on wallboard manufacture. ECM-01-CBRC-M12,
Combustion Byproducts Recycling Consortium, Tennessee Valley Authority, Final Report, July,
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Sanderson, J., Blythe, G.M., and Richardson, M. 2008. Fate of Mercury in Synthetic Gypsum Used for
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http: //www .net!. doe .gov/technologies/coalpower/ewr/coal_utilization_byproducts/pdf/420 8 OFinal
Rpt20080624.pdf. Retrieved: March 10, 2009.
6-1
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Section 6
Page 6-2
Schroeder, K. and C. Kairies. Distribution of mercury in FGD byproducts. U.S. Department of Energy,
National Energy Technology Laboratory, 2005.
Senior, C., S. Thorneloe, B. Khan, and D. Goss (2009). "Fate of Mercury Collected from Air Pollution
Control Devices." Environmental Management. Journal of the Air & Waste Management Association
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Senior, C., C. J. Bustard, K. Baldrey, T. Starns, and M. Durham. "Characterization of Fly Ash From Full-
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D.C., May 19-22, 2003.
Senior, C., C. J. Bustard, M. Durham, T. Starns, and K. Baldrey. "Characterization of Fly Ash From Full-
Scale Demonstration of Sorbent Injection for Mercury Control on Coal-Fired Power Plants,"
presented at the Air Quality IV Conference and Exhibition, Washington D.C, September 22-27,
2003.
Senior, C., C. J. Bustard, M. Durham, K. Baldrey, and D. Michaud. Characterization of fly ash from full-
scale demonstration of sorbent injection for mercury control on coal-fired power plants. Fuel
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Srivastava, R.K., and W. Jozewicz. Flue gas desulfurization: the state of the art. Journal of Air and Waste
Management 51, 1676-1688,2001.
Srivastava, R.K., N. Hutson, B. Martin, F. Princiotta, and J. Staudt. Control of mercury emissions from
coal-fired electric utility boilers. Environ. Sci. & Technol. A-Pages, 40(5): 1385-1393, 2006.
Starns, T., J. Bustard, M. Durham, C. Lindsey, C. Martin, R. Schlager, B. Donnelly,S. Sjostrom, P.
Harrington, S. Haythornthwaite, R. Johnson, E. Morris, R. Change, and S. Renninger. "Full-Scale
Test of Mercury Control with Sorbent Injection and an ESP at Wisconsin Electric's Pleasant
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Section 6
Page 6-3
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U.S. Environmental Protection Agency, 1998c. Test methods for evaluating solid waste,
physical/chemical methods, SW-846, U.S. Environmental Protection Agency, 1998.
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6-3
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Section 6
•6-4
U.S. Environmental Protection Agency, 2009. Characterization of Coal Combustion Residues from
Electric Utilities-Leaching and Characterization Data. Anticipated publication date is
December 2009.
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6-5
-------
-------
Appendix A
Page A-1
Appendix A
DOE NETL Full-Scale Test Site Flow Diagrams
A.1 Brayton Point Unit 1
• Carbon injected upstream of second ESP (Research Cottrell). Only !/> of the unit was treated, or
carbon was injected into one of the two new ESPs (Research Cottrell ESPs).
• Hopper ID's also shown. Samples from C-row are from the first row of hoppers in the second ESP.
Gas Flow
Hg S-CEM
HgS-CEM
Air Prcheater
First ESP
(Koppers)
Hg S-CEM
Sorbent Injection
-Second ESP
(Research-Cottrell)
-Hg S-CEM
Figure A-l. Brayton Point Unit 1
-------
Appendix A
Page A-2
Old
Pracslpg
Bast
West
^
Figure A-2. Brayton Point Unit 1 Hopper Identification
-------
Appendix A
Page A-3
A.2 Pleasant Prairie Unit 2
• Carbon injected upstream of cold-side ESP. Only 1/4 of the unit was treated. Test ESP was ESP 2-4.
TO ID, BIN
Figure A-3. Pleasant Prairie Unit 2
-------
Appendix A
Page A-4
A.3 Salem Harbor Unit 1
• Carbon injected upstream of cold-side ESP. Row-A hoppers were the front hoppers.
Boiler
Long Air
Heater
Short Air
Heater
Steam Coils
Figure A-4. Salem Harbor Unit 1
-------
Appendix B
Page B-l
Appendix B
Non-DOE NETL Full-Scale Test Site Flow Diagrams
B.1 Facility A
Coal
' Sampling
Ontario
Hydro Sampling
Figure B-l. Facility A
-------
Appendix B
Page B-2
This page intentionally left blank.
-------
Appendix B
Page B-3
-------
-------
Appendix C
Page C-l
Appendix C
Detailed Results for Additional Wallboard Simulation Tests
Table C-l. Description of Facilities Providing Eight Gypsum Samples.
Sample ID
AaAW
DaAW
NAW
OAW
SAW
TAW
WAW
XAW
Coal Rank
Eastern-
Bituminous
Eastern-
Bituminous
Bituminous
Bituminous
High
Sulfur
Bituminous
Eastern-
Bituminous
Eastern-
Bituminous
Sub-
Bituminous
Powder
River
Basin
NOx Control
SCR
SCR
None
SCR
SCR
SCR
SCR off
SCR
Paniculate
Control
ESP
ESP
CS-ESP
CS-ESP
CS-ESP
CS-ESP
ESP
ESP
FGD Scrubber Type
Lime Type
Limestone
Limestone
Limestone
Limestone
Limestone
Lime
Limestone
Trona
Limestone
Oxidation
Forced
Forced
Forced
Forced
Forced
Forced
Forced
Forced
Date Received
10/14/08
12/12/08
6/1/06
6/10-6/12/06
7/19/07
9/18/07
11/28/07
6/16/08
SCR = selective catalytic reduction
ESP = electro static precipitator
CS-ESP = cold-side electro static precipitator
-------
Appendix C
Page C-2
Table C-2. Detailed Results for Additional Wallboard Simulation Tests
Sample ID
AaAW
DaAW
NAW
OAW
SAW
TAW
WAW
Runl
Run 2
Run 3
Run 4
Run 5
Run 6
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Runl
Run 2
Run 3
Run 4
Run 5
Run 6
Run?
Average
Pre-test
(solid), ng/g
571
554
515
522
536
531
538
20.9
647
670
641
653
15.0
473
455
469
466
9.27
46.7
42.8
43.3
44.3
2.12
307
320
309
312
6.75
831
723
739
765
58.3
910
929
928
960
933
955
954
938
After
Simulation
(solid), ng/g
428
467
440
412
414
398
426
24.3
528
523
536
529
6.86
240
207
237
228
17.8
30.7
32.0
33.3
32.0
1.29
127
172
178
159
27.8
521
536
501
519
17.5
843
836
870
866
890
906
843
865
Volatilized
Mercury
(gas phase),
ng/g
107
112
97.2
111
149
157
122
24.5
132
132
139
134
3.86
196
206
211
204
7.51
15.5
16.2
14.8
15.5
0.68
167
153
133
151
17.3
240
123
230
198
64.6
97.3
24.0
33.7
128
103
84.1
141
87
Percent
Volatilized
19%
20%
19%
21%
28%
30%
23%
5%
20%
20%
22%
21%
1%
41%
45%
45%
44%
2%
33%
38%
34%
35%
2%
54%
48%
43%
48%
6%
29%
17%
31%
26%
8%
11%
3%
4%
13%
11%
9%
15%
9%
Percent
Remaining
in Solid
75%
84%
85%
79%
77%
75%
79%
5%
82%
78%
84%
81%
3%
51%
46%
51%
49%
3%
66%
75%
77%
72%
6%
41%
54%
58%
51%
8%
63%
74%
68%
68%
6%
93%
90%
94%
90%
95%
95%
88%
92%
Mass
Balance
94%
104%
104%
100%
105%
105%
102%
4%
102%
98%
105%
102%
4%
92%
91%
96%
93%
3%
99%
113%
111%
108%
7%
96%
101%
100%
99%
3%
92%
91%
99%
94%
4%
103%
93%
97%
104%
107%
104%
103%
101%
-------
Appendix C
Page C-3
XAW
StDev
Runl
Run 2
Run 3
Average
StDev
18.6
1033
1023
1021
1026
6.24
26.1
799
823
823
815
14.0
44.4
222
193
222
212
16.8
5%
21%
19%
22%
21%
2%
3%
77%
80%
81%
79%
2%
5%
99%
99%
102%
100%
2%
Table C-3. Detailed Results for Wallboard Simulation Tests on Sample DaAW at Various
Temperatures
Furnace
Temperature
(°C)
120
140
160
Runl
Run 2
Run 3
Run 4
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Runl
Run 2
Run 3
Average
StDev
Pre-test
(solid),
ng/g
547
546
546
564
551
8.85
640
642
581
621
34.7
647
670
641
653
15.0
After
Simulation
(solid),
ng/g
525
531
536
536
532
5.13
601
603
561
588
23.3
528
523
536
529
6.86
Volatilized
Mercury
(gas
phase),
ng/g
8.87
14.6
9.08
10.6
10.8
2.64
40.4
41.8
44.0
42.1
1.80
132
132
139
134
3.86
Percent
Volatilized
2%
3%
2%
2%
2%
0%
6%
7%
8%
7%
1%
20%
20%
22%
21%
1%
Percent
Retained in
Solid
96%
97%
98%
95%
97%
1%
94%
94%
97%
95%
2%
82%
78%
84%
81%
3%
Mass
Balance
98%
100%
100%
97%
99%
2%
100%
100%
104%
102%
2%
102%
98%
105%
102%
4%
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