United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S7-90/013 Jan. 1991
SEPA Project Summary
Assessment of Physical Coal
Cleaning Practices for Sulfur
Removal
Albert J. Herhal and Chris Minnucci
This report gives results of a study
of the current level of coal cleaning
activity in the U.S. in 1983, the U.S.
Department of Energy's (DOE's) Energy
Information Administration (EIA)
expanded coal data collection
activities to include information on the
extent and type of coal preparation
conducted in each coal-producing
region. The additional information
included data on raw coal input to
coal cleaning plants, clean coal
output, quality characteristics of the
prepared coal, and end-use markets of
both raw and prepared coal. These
data, combined with other EIA data,
provide information on the extent and
type of coal cleaning activity in each
major coal-producing state or region.
The impact on coal preparation of
differences in mining methods and
requirements of the various end-use
markets also is discussed. Estimates
were developed of SO2 emission .
reduction by current mechanical
cleaning plants based on clean coal
quality characteristics reported to EIA
and bed/county raw coal quality
estimated from the EIA/U.S. Bureau of
Mines (USBM) analytical file. Estimates
also were developed of the potential
for improving current SOZ reduction.
The current level of SO2 reduction by
mechanical cleaning is estimated at
about 5 million metric tons per year.
An estimated 2 to 3 million metric
tons of additional emission reduction
could be achieved through additional
coal cleaning activity, at an average
cost of about $150 to $200 per ton of
SO2.
This Project Summary was
developed by EPA's Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Overview
Coal preparation removes ash, sulfur,
moisture, and other impurities from raw
coal. Coal preparation processes vary
among regions because mining methods,
geological conditions, and end-use
market requirements differ by geographic
area. In this study, the extent to which
coal producers in different regions of the
U.S. currently clean their coal was
estimated and the potential S02
reduction that can be achieved through
increased cleaning was determined.
Estimates of the potential for increasing
SO2 reduction were derived on the basis
of a consideration of commercially-
proven, conventional cleaning technology
(i.e., physical coal cleaning) only;
chemical coal cleaning is not considered
in this study.
Coal Preparation* Techniques
All coal, including the final product
shipped to; end-use markets, contains
impurities. Some impurities are
introduced from the area around the coal
seam during extraction; others are within
Printed on Recycled Paper
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(he seam itself. The raw coal's physical
characteristics, and the intensity of the
preparation it undergoes, determine the
quality of the final product. The two basic
cleaning procedures used in preparation
plants are crushing and screening, and
mechanical cleaning ("washing").
The simplest cleaning procedure is
crushing and screening. In crushing and
screening, the raw coal is pulverized into
fragments small enough to pass through
a screen, separating the coal from the
harder non-coal rock particles that are
more difficult to crush. Crushing and
screening, however, tends not to remove
the smaller foreign particles or impurities
within the coal seam. Smaller particles
and internal impurities respond only to
mechanical cleaning, a more expensive
and involved process that begins with
crushing and screening and ends with
separation and dewatering. Separation
uses the specific gravity differences
between coal and other particles to filter
out impurities. However, coal is filtered
out along with the impurities during
mechanical cleaning. As the amount of
refuse material removed approaches
100% the amount of coal lost increases
and mechanical cleaning becomes
economically unattractive beyond a
certain level of purity. Thus, the decision
to mechanically clean (as opposed to
simply crushing and screening) involves
an economic trade-off between the
quality and the quantity of the end
product.
Typically, preparation plants are
classified according to four preparation
levels (the same scheme used
throughout this report): level 1 consists
of crushing and screening only; level 2
uses a single mechanical cleaning
circuit); level 3 consist of two separate
mechanical cleaning circuits, one for
coarse and one for mid-sized coal the
fine coal may or may not be passed
through the mid-sized circuit); and level 4
consist of three (sometimes four)
mechanical cleaning circuits - one for
coarse, one for mid-sized, and one for
fine coal.
Data Sources
The results of this study for current
coal preparation activities are based
primarily on analysis of data derived from
two (EIA) survey forms: the 1983 EIA-7A
and the 1983 EIA-7A (Supplement) "Coal
Production Report." The EIA-7A forms
are sent annually to mines that produce,
process, or prepare 9,070 or more metric
tons (10,000 or more short tons) of coal
per year. The EIA-7A form requests data
on the:
Type of mining operation (under-
ground, surface, preparation plant,
etc.).
Production by coal bed and coal rank.
Breakdown of production by market
type (captive, openstocks, etc.) and
the value free-on-board (FOB) mine.
Respective percentages of prepared
coal (for mines that include
preparation plants) from surface and
from underground mines.
The EIA-7A Supplement is a biennial
survey of coal mines that produce,
process, and prepare 90,700 or more
metric tons (100,000 or more short tons)
per year. The EIA-7A Supplement form
requests data on:
Tonnage shipped without preparation.
Tonnage crushed and screened only.
Tonnage mechanically cleaned
Tonnage shipped to each end-use
market (electric utilities, coke plants,
exports, etc.).
Information from each form is
combined to produce the EIA-7A coal
data base, a computer file maintained
and updated annually by EIA.
Coal data also are available from the
Federal Energy Regulatory Commission
(FERC) Form 423 computer file
(maintained by EIA), "Cost and Quality of
Fuels for Electric Utility Plants." The file
includes information on the quality of coal
delivered to electric powerplants and, for
most plants, the name(s) and location(s)
of the mine(s) from which they purchased
the coal. The U.S. Bureau of Mines/EIA
analytical computer file (also maintained
by EIA) supplements the EIA-7A and
FERC-423 forms by providing information
on raw coal quality by seam and county
for each producing state.
The conclusions drawn in this report
concerning the potential SO2 reduction
from additional preparation of both the
cleaned and uncleaned portions of
current production are based on an
extensive analysis of currently available
data on coal washability and
demonstrated coal reserves. The coal
washability data were obtained from the
U.S. DOE's washability data base* and
several U.S. Bureau of Mines Reports of
Investigation. These data were combined
into a single data base representing the
major producing coal seams in the U.S.
The 1971 U.S. Demonstrated Coal
Reserve Base (DRB) (maintained as a
* This data base was originally developed by the
USBM but is now maintained and updated by the
U.S. DOE's Pittsburgh Energy Technology Center.
The data base is available on computer tape.
computer file by EIA) was the principal
source of information on coal reserves at
the bed/county level. This data base is
the only source of coal reserve data
disaggregated by coal seam (bed) and
location (county). However, because
substantial changes in quantities have
been assigned to the DRB since 1971, it
was necessary to adjust the 1971 figures
to reflect the most recent updates. The
updating was accomplished using the
1983 DRB (containing reserves only at
the state level) together with the more
disaggregated data base to derive the
best possible estimates of reserves by
bed and county.
After the demonstrated coal reserves
were distributed by bed and county, the
reserves were disaggregated further by
quality within each bed/county
combination, using a coal quality data
base assembled from the USBM/EIA
analytical file and other sources. Overall,
more than 33,000 coal quality samples
were obtained and merged into the new
reserve data base. The result was a set
of data that identified both coal quantity
and quality at the lowest possible level of
aggregation.
The study divides the U. S. into five
coal-producing regions: Central
Appalachia, Southern Appalachia,
Northern Appalachia, the Midwest, and
the West. The division was made to
capture existing differences in mining
methods, geologic conditions, in-seam
coal quality, and end-use markets
factors that affect the type and degree of
coal-cleaning activities.
Regional Analysis
In 1983, over 50% of U.S. raw coal
production was cleaned. Of underground
coal production, 70% was mechanically
cleaned, and 23% of surface coal
production was mechanically cleaned.
The percentage of underground-mined
coal mechanically cleaned is high
because virtually all production of
metallurgical-grade coal comes from
underground mines. Also, more use of
highly mechanized mining techniques,
such as continuous and longwall mining,
has reduced the average particle size of
'the run-of-mine product, thereby making
the output less responsive to crushing
and screening alone. Lastly, increased
emphasis on quality on the part of end-
users has had a direct impact on the
amount of co'al being mechanically
cleaned.
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Central Appalachia
The Central Appalachia region
consists of eastern Kentucky, Tennessee,
Virginia, and West Virginia. In 1983,
Central Appalachian mining operators
mechanically cleaned 73% of their
production and crushed and screened an
additional 20%. /As for the Nation as a
whole, the use of mechanical cleaning in
Central Appalachia is highly correlated
with mining method. For the region as a
whole, over 96 percent of the more than
100 million metric tons (110 million short
tons) of raw coal output from
underground mines was at least crushed
and screened before being sold.
However, 21% of surface production, 7.6
million metric tons (8.4 million short tons),
was sold without any form of preparation.
Virtually all of the "no-preparation" coal
was sold to electric utilities.
Nonetheless, mechanical cleaning is
important in Central Appalachia; the
region contains 158 mechanical cleaning
plants, more than half the U.S. total.
During the period of study (1983), Central
Appalachia sold most of its output to
domestic electric utility companies. The
second leading customer was the export
market, both in terms of metallurgical-
and steam-grade products.
Some 88 of Central Appalachia's
mechanical cleaning plants are in West
Virginia; more of that state's output is
mechanically cleaned than that of any
other Central Appalachian state except
Tennessee (by volume a relatively minor
coal producer) (Table 1). This reflects
West Virginia's importance as a source of
metallurgical coal for both foreign and
domestic use.
Data for 1983 show that plants in
Central Appalachia prepared 146.6
million metric tons (161.2 million short
tons) of their 200.9 million metric tons
(221.5 million short tons) of coal. The
region's mechanical cleaning plants
showed an overall clean-coal yield
(salable product as a percentage of input
to preparation plants) of 64 %. The clean
coal yield for individual Central
Appalachian states are: eastern
Kentucky, 62%; Tennessee, 57 %;
Virginia, 59%; and West Virginia, 65 %.
Southern Appalachia
The Southern Appalachia region
consists of Alabama and Georgia;
however, since Georgia is not a major
coal producer, data are available only for
Alabama. The state's coal, 79% of which
was mechanically cleaned, is relatively
low in sulfur. Alabama contains about 30
mechanical cleaning plants that have
stepped up coal preparation considerably
in recent years. Of the 20.8 million metric
tons (22.9 million short tons) of raw input
to preparation plants, the final salable
yield was 65 percent, or 13.6 million
metric tons (15 million short tons). Like
those in Central Appalachia, Alabama
plants sold most of their coal to the
domestic utility industry, and
mechanically cleaned most of that coal.
Northern Appalachia
The Northern Appalachia region
consists of Pennsylvania, Ohio, and
Maryland. The plants in the region
mechanically cleaned 70% of the
region's coal and crushed and screened
22% (Table 2). In 1983, the region
contained over 85 mechanical cleaning
plants, about 20% of the U.S. total. As
the largest coal producer in the region
and the only state with any significant
metallurgical coal reserves, Pennsylvania
contains most of these plants.
Plants in Ohio, however, have drama-
tically increased mechanical cleaning in
recent years (from 47% in 1978 to 82%
of total production in 1983) so that Ohio
coal, relatively high in impurities, can
compete in today's quality-conscious
market. Although more Ohio coal is
washed now, a third of Ohio's mechanical
cleaning plants are single-circuit; that is,
coal fed into the plants undergoes the
lowest level of mechanical preparation.
(The highest number of cleaning
circuits in mechanical cleaning plants
currently in operation is four).
Clean-coal yields in Northern
Appalachia exceed considerably those in
Central Appalachia. The difference in
yields for the two regions partly reflects
the fact that Northern Appalachia coal
seams tend to be thicker (1.63 versus
1.37 m based on 1983 EIA-7A data), thus
reducing the amount of dilution material
added to the coal during the mining
process. Also, much of the coal cleaning
in Central Appalachia is for metallurgical
purposes, and thus entails a generally
more intensive process than the
preparation of steam coal. Preparation
reduced the region's total output from
103 to 82.9 million metric tons (113,5 to
91.4 million short tons), a loss of about
20%. Yields from mechanical cleaning
were 76, 70, and 71% for Maryland, Ohio,
and Pennsylvania, respectively.
The Midwest
Illinois, Indiana, and western Kentucky
constitute the Midwest region. Some 95
percent of the region's coal was either
mechanically cleaned or crushed and
screened (Table 3). Illinois producers
mechanically clean about 93% of their
raw coal output, and Indiana, whose coal
is almost all surface-mined, mechanically
cleans over 70% of its coal. Preparation
reduced the region's 133 million metric
tons (146.6 million short tons) of raw coal
to 104 million metric tons (114.6 million
raw tons). The Midwest's overall
mechanical cleaning yield was 74%,
significantly higher than yields for the
coal-producing areas of Appalachia (64%,
65% and 70% for Central, Southern, and
Northern Appalachia, respectively). Much
of this difference can be attributed to the
fact that very little metallurgical coal is
mined and prepared in the Midwest. Yield
figures for Midwestern preparation plants,
therefore, do not reflect the cleaning
losses associated with the intense
preparation of this product type.
As indicated above, most of the
production from this region is sold as a
steam product to electric utilities. In
Illinois and Indiana, 86% of the total
salable output was sent to the utility
market. In western Kentucky, 92% of
production went to electric utilities. Of
this production, 91%, 72%, and 65% was
mechanically cleaned for Illinois, Indiana,
and western Kentucky, respectively.
These percentages reflect differences in
in-place reserve quality as well as mining
conditions and methods within each
state.
The West
Coal washing in the Western coal-
producing states, except for the interior
states,* is not very extensive. The coal
mined in this region is primarily a sub-
bituminous product, none of which is
mechanically cleaned. Bituminous coal,.
for use by electric utilities, is mined in
Colorado, Utah, and, to a much lesser
extent, New Mexico. Utility coal mined in
these states is inherently high Btu, low-
sulfur, and low-ash and does not require
extensive cleaning. Only 6% of the utility
coal mined in Colorado in 1983 was
mechanically cleaned. In Utah, the figure
was about 13% of utility coal production,
and in New Mexico, less than l% of the
bituminous steam coal was cleaned. In
contrast, Missouri produces bituminous
coal exclusively, and the utility coal
mined in the state is high in sulfur.
Approximately 51%,of Missouri's utility
coal production was cleaned in 1983.
Although very little coal produced in the
West is mechanically cleaned, over 80%
The interior states are Arkansas, Iowa, Kansas,
Missouri, and Oklahoma.
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Table 1. Central Appalachian Coal Preparation (1983)^
Area
Eastern
Kentucky
Tennessee
Virginia
West Virginia
Total
Quantity
Produced
(million raw
metric tons)
50.7
4.2
25.0
121.0
200.9
Percentage
Mechanically
Cleaned
57
80
77
79
74
Percentage ,
Crushed and
Screened
27
20
16
19
20
Percentage
Not
Prepared
16
0
7
2
6
"All values include only mines producing more than 90,700 metric (100,000
short) tons of coal per year and reporting on Form EIA-7A Supplement.
Table 2. Northern Appalachian Coal Preparation (1983)3
Area
Maryland
Ohio
Pennsylvania
Total
Quantity
Produced
(million raw
metric tons)
5.39
33.39
64.35
103.13
Percentage
Mechanically
Cleaned
58
82
65
70
Percentage
Crushed and
Screened
26
14.
25
22
Percentage
Not
Prepared
16
4
10
8
All values include only mines producing more than 90,7000 metric (100,000
short) tons of coal per year and reporting on Form EIA-7A Supplement.
Table 3. Midwestern Coal Preparation (1983)*
Area
Illinois
Indiana
Western
Kentucky
Total
Quantity
Produced
(million raw
metric tons)
63.0
33.7
36.5
133.2
Percentage
Mechanically
. Cleaned
93
78
72
83
Percentage
Crushed and
Screened
6
17
18
12
Percentage
Not
Prepared
1
5
10
5
aAH values include only mines producing more than 90,700 metric (100,000
short) tons of coal per year and reporting on Form EIA-7A Supplement.
of all production (both bituminous and
sub-bituminous) is crushed and
screened.
Current SOg Reduction
The method used to determine current
SO2 reduction levels was structured to
take advantage of the 1983 EIA-7A
Supplement data. In addition to providing
information on the quantity of coal
mechanically cleaned, this data base also
includes quality information on coal
shipped to each end-use sector. By
obtaining raw sulfur inputs on a
bed/county basis from the EIA/USBM
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analytical file, estimates of SO2 reduction
obtained through mechanical cleaning
could be derived.
The use of the average bed/county
S02 content as a proxy for the actual
S02 content of the raw feed" to the plant
is the primary cause of uncertainty in the
estimation procedure. The data used
represent information on coal in place
and coal being mined at the time the
samples are taken. This could result in an
estimate at the bed/county level
substantially different from the coal
currently mined. Consequently, any
inferences drawn from the analysis must
be viewed against the potential
uncertainty caused by inherent limitations
of the raw data.
The problem of uncertainty is
addressed separately from the analysis.
A method was developed whereby
estimates of uncertainty at different levels
in the analysis could be combined
meaningfully to develop an overall
estimate of the probable error. The
uncertainty analysis is discussed in more
detail in the full report.
The procedure used to develop the
SO2 reduction estimates is described in
the full report. Table 4 presents the
results obtained through the application
of the procedure.** As the data indicate,
Appalachian operators cleaned more coal
than their Midwestern and Western
counterparts combined; of approximately
245 million metric tons (270 million short
tons) of as-shipped coal produced by
Appalachian operations in 1983,
approximately 156 million metric tons
(172 million short tons), or 64%, was
mechanically cleaned. The coal that was
processed by the region's plants
contained a total of 8.0 million metric tons
(8.8 million short tons) of SO2; of this 2.9
million metric tons (3.2 million short tons)
(36%) was removed from the coal
through cleaning. Nearly all of this 2.9
million metric tons (3.2 million short tons)
of SO2 was removed from coal that was
mined and processed in the northern part
That is, the SOa equivalent of the sulfur
content of the raw feed, assuming that all of
the sulfur in the feed would be released as SO2
upon consumption. The convention of referring
to the SC>2 equivalent of the sulfur content of
coal as the "SC>2 content" of the coal has been
adopted herein for convenience. Unless
otherwise noted, all estimates of the SO2
content of coal are based on the assumption
that all of the sulfur in the coal would be
released as SO2-
"Results for Maryland are not included in this
table. In 1983, only one cleaning plant was
operating in Maryland, and data for this plant
were not usable.
of the region (i.e., Pennsylvania, Ohio,
and West Virginia); in fact, Northern
Appalachian plants accounted for 88% of
the total SO2 reduction. This is in part
because Northern Appalachian coal is
generally higher in sulfur content than is
the coal in Southern Appalachian
reserves; more SO2 can be removed
from Northern Appalachian coal because
more SO2 is present in the coal. In fact,
more SO2 was removed from Ohio,
Pennsylvania, and West Virginia coal
than was present in the raw coal
processed by Southern Appalachian
operators.
In Northern Appalachian states
(particularly Pennsylvania), good SO2
reduction results are being achieved
through cleaning; thus, Northern
Appalachia may represent an area in
which increased mechanical cleaning
could significantly increase the SO2
removed*. In general, the same is not the
case for Central and Southern Appalachia
because the sulfur content of Central and
Southern Appalachian coal is quite low; at
least in Virginia and Alabama, the coal is
not amenable to sulfur reduction through
washing. Within Southern Appalachia,
only the unwashed coal of eastern
Kentucky contains a relatively large
quantity of SO2 that is potentially
removable through cleaning.
Although Midwestern operators
cleaned less coal than those in
Appalachia in absolute terms--82.5
versus 156 million metric tons (82.5
versus 172 million short tons) for
Appalachia - in relative terms, it cleaned
a larger percentage of its as-shipped
production (76, versus 64% for
Appalachia). The coal that was processed
by the region's plants contained 7.5
million metric tons (8.3 million short tons)
of SO2; of this total, 2.5 million metric
tons (2.8 million short tons), or about 34
percent, was removed through cleaning.
These sulfur and sulfur-reduction
quantities are not much lower than the
corresponding quantities for Appalachia,
despite the fact that in Appalachia nearly ,
twice as much coal was cleaned as in the
Midwest. This indicates that Midwestern
coal is much higher in sulfur than
Appalachian coal, a fact that has clearly
forced Midwestern operators to rely more
"Note that, throughout this report, coal cleaning is
considered in isolation from other SO2 reduction
technologies, such as flue gas desulfurization.
Therefore the statement that significant increases
in SOj reduction can be achieved by cleaning
Northern Appalachian coal is based on the
assumption that no SOg is currently being
removed from this coal by other means.
heavily on mechanical cleaning than do
their Appalachian counterparts. In fact, of
operators in all the mining regions, only
those in the Midwest are cleaning as
large a percentage of their surface
production as their underground
production; thus, it appears that sulfur,
rather than ash, reduction may be the
primary objective of Midwestern
preparation plant operators.
In addition to presenting SO2
reduction estimates for the major
Appalachian and Midwestern coal-
producing states, Table 4 also provides
estimates for Western states for which
usable EIA-7A data were available. Four
Western states are included in the table;
one of these is characterized by high-
sulfur reserves (Missouri), and three are
characterized by low-sulfur coal
(Colorado, New Mexico, and Utah).
Because of the low absolute tonnage of
bituminous coal production and/or
processing in these states, relatively little
SO2 reduction is achieved through coal
cleaning.
Potential Reductions
The method used to determine
potential S02 reduction from physical
coal cleaning is based on assigning
average washability characteristics to
coal reserves on a bed/county basis. This
approach allows calculating a range of
SOa reduction estimates for various coal
preparation options. Within each option
(corresponding to a given level of
preparation), separation gravities could
be chosen to yield optimum SO2
reduction levels .for preselected,
economically acceptable heat content
yields (95%, 90%, etc.). Thus for each
preparation option, a range of SO2
reduction estimates corresponding to
selected heat content yield values could
be developed.
To implement this methodology, a
considerable amount of effort was
expended to identify and gather available
data on coal washability and to construct
a data base that could be mapped
against demonstrated coal reserves,
providing an enumeration, as complete
as possible, at the bed/county level. The
data sources used to complete this task
were discussed above.
Another critical component of this
effort was selecting a model to assist in
determining SO2 reduction and costs
associated with preparation options. For
this project the Skea and Rubin coal
preparation model was chosen as the
basic analysis tool. While the basic
framework of the model was left intact,
several modifications were made to the
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Table 4. Current SC-2 Reduction Estimates (Based on 1983 Data)
Region and State
Appalachia b
Ohio
Pennsylvania
West Virginia
Alabama
Eastern Kentucky
Tennessee
Virginia
Total
Midwest
Illinois
Indiana
Western Kentucky
Total
West
Colorado
Missouri
New Mexico
Utah
Total
Grand Total
Quantity
of Coal
Cleaned3
(thousand
clean"
meiric
tons)
19,317
29,689
62,745
13,377
18,067
1,919
11,186
156,300
43,448
19,588
19,599
82,635
1,434
2,362
145
1,367
5,308
244,243
Quantity of SO2 in Raw Coal3
(thousand metric tons)
Input to
Mechanical
Cleaning
Plants
2,175
1,838
2,875
397
431
81
243
8,040
3,877
1,466
2,163
7,506
27
363
3
24
417
15,963
Removed
Through
Mechanical
Cleaning
741
827
943
55
159
58
45
2,828
1,463
204
848
2,515
10
130
1
12
153
5,486
Remaining
in Clean
Coal
1,434
1,011
1,932
342
272
23
198
5,212
2,414
1,262
1,315
4,991
17
. 233
2
13
265
10,468
"Includes only coal produced and SO2 removed by operators that mined over 90,700
metric (100,000 short) tons in 1983.
bMaryland results not included (see text).
costing algorithms and other components
lo fit the specific needs of this study.
Overall, considerable work was
expended to come up with potential SO2
reduction estimates and costs for both
the cleaned and uncleaned portions of
current production. Because of the detail
and complexity of the methodology, a
lengthy discussion of the approach is
provided in the full report.
As discussed above, the first step in
the process was to develop a coal
reserve base by bed/county, which
contained corresponding average
washability data. Using this reserve base,
washability curves were prepared for
both the cleaned and uncleaned portions
of each region's current production.
These curves show the S02 reduction
potential by preparation option and heat
content yield, as well as the correspond-
ing cleaning costs in dollars per metric
ton (In parentheses). Examples of the
curves are shown by Figures 1 and 2.
Using these figures and information on
the coal preparation and mining
industries within each region, a range of
SO2 reductions and corresponding costs
was developed using "light" and "heavy"
coal cleaning scenarios.
Each scenario is defined by a
preparation level and a heat content
yield. In defining the scenarios, economic
as well as technical considerations were
taken into account. The definition of light
and heavy cleaning thus varies from state
to state, reflecting regional variability in
the washability of coal. Also, the scenario
definitions vary within each state for the
cleaned and uncleaned portion of the
state's production. For the cleaned
production, both the light and the heavy
cleaning options represent additional or
more intensive cleaning, over and above
the cleaning to which the coal has
already been subjected. Mine operators
already cleaning their coal can attain
highly intensive levels of cleaning at a
lower additional cost than other
operators, simply by expanding their
existing cleaning plants and/or modifying
the plants' operating characteristics. For
this reason, the definitions of light and
heavy cleaning reflect a more intensive
degree of preparation than for the
uncleaned coal. Significant additional
SO2 reduction through further cleaning of
the uncleaned production, beyond heavy
cleaning, is thus technically feasible in
many states, although the resulting costs
would be high if not prohibitive. The
cleaning scenarios within each state are
defined in Table 5.
Using available information, it was
estimated that approximately 19 million
metric tons (21 million short tons) of SO2
is contained in the raw coal mined in the
coal-producing states east of the
Mississippi River. These states contain
most of the bituminous coal reserves that
traditionally are cleaned. It is estimated
that slightly over 5 million metric tons
-------
<0
8
TO
or
o
g
CD
-------
m
3
5
8
o
Cf)
0.9-
0.8-
0.7-
~ 0.6 -
0.5-
0.4-
S 0.3 -
0.2 -
0.1-
Level 2 (2.26)
Level 3 (2.90)
Level 4 (3.66)
(2.52) (2.79)
(3,20) (3.50)
(4.00) (4.30)
Level 4
Level 3
Level 2
Preparation Costs
($/Clean Metric Ton)
95 90 85 80
Heat Content Yield (percent)
1 r I
75
Figure 2. Clean coal content versus heat content yield and preparation costs for
Illinois' clean production.
bringing them in-line with alternative
control technologies.
A question often raised when
examining coal supply issues is the
quantity, availability and price of low-
sulfur eastern bituminous coal. The
answer to this question, for the most part,
has been given in terms of in-place coal
reserves' meeting specific pre-
preparation quality characteristics. With
the data base it is possible to identify the
amount of coal that can be cleaned to a
specified level, and the associated costs.
Obviously, many similar questions can be
addressed. The fact that the data base
was constructed at the bed/county level
makes it flexible and easy to use for
addressing many varying coal
supply/demand issues.
Some words of caution are in order.
Throughout this study every effort was
made to obtain the most complete and
reliable washability data available. To that
end it is believed that the study was
successful. However, while the data base
was constructed on a bed/county basis, it
does not cover all beds and all counties
where mining is prevalent. Data gaps do
exist, some more pronounced than
others.
Also, as discussed above, the
definitions of light and heavy cleaning are
based on economic as well as technical
considerations, and reflect a less
intensive degree of cleaning for the
uncleaned portion of current production
than for the cleaned portion.Therefore,
significant increases in SO2 reduction,
beyond those estimated for the heavy
cleaning scenario, are technically feas-
ible in some regions.
"The definitions of light and heavy cleaning for
uncleaned coal were selected based on an
analysis of the regional SO2 reduction curves
(see, for example, Figure 1), and do not
necessarily correspond to current degrees of
cleaning for cleaned coal.
-------
Table 5. Definitions of Cleaning Scenarios
Light Cleaning
Heavy Cleaning
Area/State*
West Virginia
Uncleaned
Cleaned
Eastern Kentucky
Uncleaned
Clean
Virginia
Uncleaned
Cleaned
Alabama
Uncleaned
Cleaned
Pennsylvania
Uncleaned
Cleaned
Ohio
Uncleaned
Cleaned
Illinois
Uncleaned
Cleaned
Indiana
Uncleaned
Cleaned
Western Kentucky
Uncleaned
Cleaned
Preparation
Level
3
4
2
4
2
N/A>>
2
4
3
N/AC
2
4
2
4
2
3
2
4
Heat Content
Yield
95
88
95
89
97
N[A>>
95
90
95
N/A<=
95
89
95
90
95
95
95
87
Preparation
Level
3
4
2
4
3
N/A>>
3
4
4
4
3
4
3
4
3
4
'3
4
Heat Content
Yield
90
85
90
86
96
NIAf>
85
85
90
85
90
85
90
85
90
85
90
85
aThe analysis of the potential for removing SO2 through cleaning was limited to major coal-
producing states east of the Mississippi River. Available data for major coal-producing
states are too limited to support the development of SO2 reduction estimates, and SO2
reduction is not a major concern for western coal (which is already low in SO2).
t>N/A = not applicable. The available washability data for Virginia are too limited to support
the development of SO2 reduction estimates for the state's cleaned production.
°N/A = not applicable. Pennsylvania's cleaned production is already being subjected to an
intensive degree of cleaning; therefore any additional cleaning must be heavy rather than
light.
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Tablo 6. Economic Assumptions for All Model Runs (Potential Reduction Scenarios)
Annual plant operation
Plant output
Economic life of plant
Nominal interest rate
Rate of inflation
Index updating 1978 base year costs
to mid-1986 dollars (mid-1978 -1)
3325 hours per year
454 dry metric tons (500 dry tons) per hour
20 years
10 percent
5 percent
1.484 I
Table 7. Current and Potential SO2 Reduction Estimates and Preparation Cost Estimates
Quantity of SO2
Preparation Costs ($/
Region and State
Appalachia
Ohio
Pennsylvania
W. Virginia
Alabama
E. Kentucky
Virginia
Tola!
Midwest
Illinois
Indiana
W. Kentucky
Total
Grand Total"
HJtOI I&OO
Raw Production
(thousand raw
metric tons)
33,400
64,400
121,000
26,300
50,700
25,000
320,800
63,000
33,700
36,500
133,200
454,000
Total SO2a in Raw
Coal (thousand raw
metric tons)
2,594
2,845
4,066
766
1,209
386
11,866
4,134
1,986
2,967
9,087
20,953
Currently13
741
827
943
55
159
45
2,770
1,463
204
848
2,515
5,285
Potentially
Light0 Heavy0
126
312
286
80
145
16
965
142
322
229
693
1,58
282
486
519
182
240
21
1,730
367
610
385
1,362
3,092
, Light
204.84
167.03
309.17
309.06
306.17
464.91
251.71
277.59
74.48
1 51 .23
141.46
205.63
Heavy
119.66
172.58
194.53
180.47
238.84
455.13
183.99
141.61
84.76
114.96
108.79
150.79
"Includes cleaned and uncleaned.
bTennessee, Colorado, Missouri, New Mexico, Maryland, and Utah costs are not included because potential SO2 reduction estimates
wore not developed for these states (see Table 5, especially footnote a.)
cUght and heavy cleaning vary by region, and are defined in Table 5.
10
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A. Herhal and C. Minnucci are with Science Applications International Corp.,
Norristown, PA 19403
Julian W. Jones is the EPA Project Officer (see below).
The complete report, entitled "Assessment of Physical Coal Cleaning Practices
for Sulfur Removal," (Order No. PB 90-250 1431 AS; Cost: $23.00, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/60Q/S7-90/013
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