EPA
October 1974
       BACKGROUND INFORMATION
  FOR STANDARDS OF  PERFORMANCE:
       COAL  PREPARATION PLANTS
   VOLUME  1:  PROPOSED STANDARDS
         U.S. ENVIRONMENTAL PROTECTION AGENCY
           Office of Air and Waste Management
         Office of Air Quality Planning and Standards
         Research Triangle Park, North Carolina 27711

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                              EPA 450/2-74-021a
    BACKGROUND INFORMATION
FOR STANDARDS  OF PERFORMANCE:
     COAL  PREPARATION  PLANTS
VOLUME  1:  PROPOSED STANDARDS
        Emission Standards and Engineering Division
        U.S. ENVIRONMENTAL PROTECTION AGENCY
           Office of Air and Waste Management
        Office of Air Quality Planning and Standards
        Research Triangle Park, North Carolina 27711

                 October 1974

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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers.  Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations  as supplies permit from the Air
Pollution Technical Information Center, Environmental Protection Agency,
Research Triangle Park,  North Carolina  27711; or, for a  fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia  22161.
                Publication No. EPA-450/2-74-021a

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                            PREFACE
A.  Purpose of this Report
     Standards of performance under section 111  of the Clean
Air Act—  are proposed only after a very detailed investigation
of air pollution control methods available to the affected
industry and the impact of their costs on the industry.  This
report summarizes the information obtained from such a study
of coal preparation plants.  It is being distributed in
connection with formal proposal of standards for that industry
in the Federal Register.  Its purpose is to explain the
background and basis of the proposal in greater detail than
could be included in the Federal Register, and to facilitate
analysis of the proposal by interested persons,  including those
who may not be familiar with the many technical  aspects of the
industry.  For additional information, for copies of documents
(other than published literature) cited in the Background
Information Document, or to comment on the proposed standards,
contact Mr. Don R. Goodwin, Director, Emission Standards and
Engineering Division, United States Environmental Protection
Agency, Research Triangle Park, North Carolina 27711 [(919)688-8146].
B.  Authority for the Standards
     Standards of performance for new stationary sources are
promulgated in accordance with section 111 of the Clean Air Act
(42 USC 1857c-6), as amended in 1970.  Section 111 requires
     T7Sometimes referred to as "new source performance
standards" (NSPS).

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the establishment of standards of performance for new stationary
sources of air pollution which "... may contribute significantly
to air pollution which causes or contributes to the endangerment
of public health or welfare."  The Act requires that standards
of performance for such sources reflect "... the degree of
emission limitation achievable through the application of the best
system of emission reduction which (taking into account the cost
of achieving such reduction) the Administrator determines has
been adequately demonstrated."  The standards apply only to
stationary sources, the construction or modification of which
commences after regulations are proposed by publication in
the Federal, Register.
     Section 111 prescribes three steps to follow in establishing
standards of performance.
     1.   The Administrator must identify those categories of
         stationary sources for which standards of performance
         will ultimately be promulgated by listing them in the
         Federal Register.
     2.   The regulations applicable to a category so listed must
         be proposed by publication in the Federal Register within
         120 days of its listing.  This proposal provides Interested
         persons an opportunity for comment.
     3.   Within 90 days after the proposal, the Administrator
         must promulgate standards with any alterations he deems
         appropriate.
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     It Is Important to realize that standards  of performance,
by themselves, do not guarantee protection of health  or welfare;
that 1s, they are not designed to achieve any specific air
quality levels.  Rather, they are designed to reflect best
demonstrated technology (taking into account costs)  for the
affected sources.  The overriding purpose of the collective
body of standards is to maintain existing air quality and to
prevent new pollution problems from developing.
     Previous legal challenges to standards of  performance for
Portland cement plants, steam generators, and sulfuric acid
plants have resulted in several court decisions-/ of Importance
in developing future standards.  In those cases, the principal
issues were whether EPA:  (1) made reasoned decisions and
fully explained the basis of the standards, (2) made available
to interested parties the information on which  the standards
were based, and  (3) adequately considered significant comments
from Interested parties.
     Among other things, the court decisions established:
(1) that preparation of environmental impact statements 1s not
necessary for standards developed under section 111  of the Clean
Air Act because, under that section, EPA must consider any
counter-productive environmental effects of a standard 1n
determining what system of control 1s "best;"  (2) 1n considering
costs 1t 1s not necessary to provide a cost-benefit analysis;
     27  Portlant Cement Association v Ruckelshaus, 486 F. 2nd
375 (D.C. Cir. 1973); Essex Chemical Corp. v Ruckelshaus, 486
F. 2nd 427  (D.C. Cir. 1973).

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 (3)  EPA is not required to justify standards that require different
 levels of control in different industries unless such different
 standards may be unfairly discriminatory; and (4) it is
 sufficient for EPA to show that a standard can be achieved
 rather than that it has been achieved by existing sources.
     Promulgation of standards of performance does not prevent
 State or local agencies from adopting more stringent emission
 limitations for the same sources.  On the contrary section 116
 of the Act (42 USC 1857-D-l) makes clear that States and other
 political subdivisions may enact more restrictive standards.
 Furthermore, for heavily polluted areas, more stringent standards
may be required under section 110 of the Act (42 USC 1857c-5) in
order to attain or maintain national ambient air quality standards
prescribed under section 109 (42 USC 1857c-4).  Finally, section 116
makes clear that a State may not adopt or enforce less stringent
standards than those adopted by EPA under section 111.
     Although it is clear that standards of performance should be
1n terms of limits on emissions where feasible,—' an alternative
method of requiring control of air pollution is sometimes
necessary.  In some cases physical measurement 'of emissions
from a new source may be impractical or exorbitantly expensive.
     37"'Standards of performance,1  ...  refers to the degree of
emission control which can be achieved through process changes,
operation changes, direct emission control, or other methods.   The
Secretary [Administrator] should not make  a technical judgment
as to how the standard should be implemented.   He should determine
the achievable limits and let the owner or operator determine  the
most economical technique to apply."  Senate Report 91-1196.
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 For example, emissions of hydrocarbons from storage vessels  for
petroleum liquids are greatest during storage and tank filling.
The nature of the emissions (high concentrations for short
periods during filling and low concentrations for longer
periods during storage) and the configuration of storage tanks
make direct emission measurement highly impractical.  Therefore,
a more practical approach to standards of performance for
storage vessels has been equipment specification.
C.  Selection of Categories of Stationary Sources
     Section 111 directs the Administrator to publish and from
time to time revise a list of categories of sources for which
standards of performance are to be proposed.  A category is to
be selected  "... if [the Administrator] determines it may contribute
significantly to air pollution which causes or contributes to the
endangerment of public health or welfare."
     Since passage of the Clean Air Amendments of 1970, considerable
Attention has been given to the development of a system for
assigning priorities to various source  categories.  In brief,
the approach that has evolved is as follows.
     First,  we  assess any areas of emphasis by .-considering the
broad  EPA strategy for  implementing the Clean Air Act.  Often,
these  "areas" are actually pollutants  which  are  primarily emitted
by stationary sources.  Source  categories which  emit  these
pollutants are  then  evaluated and ranked by  a process involving

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such factors as  (1) the level of emission control (1f any)
already required by State regulations; (2) estimated levels
of control that might result from standards of performance for the
source category; (3) projections of growth and replacement  ,
of existing facilities for the source category; and (4) the
estimated Incremental amount of air pollution that could be
prevented, 1n a preselected future year, by standards of
performance for the source category.
     After the relative ranking is complete, an estimate
must be made of a schedule of activities required to develop
a standard.  In some cases, 1t may not be feasible to immediately
develop a standard for a source category with a very high
priority.  This might occur because a program of research
and development is needed or becaMse techniques for sampling
and measuring emissions may require refinement before study
of the Industry can be initiated.   The schedule of activities
must also consider differences in  the time required to complete
the necessary investigation for differenl  source categores.
Substantially more time may be necessary, for example, if a
number of pollutants must be investigated in a single source
category.  Even late in the development process the
schedule for completion of a standard may change.  For
example, inability to obtain emission data from

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well-controlled sources In time to pursue the development
process in a systematic fashion may force a change in
scheduling.
     Selection of the source category leads to another major
decision:  determination of the types of sources or facilities
to which the standard will apply.  A source category often
has several facilities that cause air pollution.  Emissions
from some  of these facilities may be insignificant and, at the
same time, very expensive to control.  An investigation of
economics  may show that, within the costs that an owner could
reasonably afford, air pollution control is better served by
applying standards to the more severe pollution problems.  For
this reason  (or perhaps  because there may be  no adequately
demonstrated system  for  controlling emissions from certain
facilities), standards often do not apply to  all  sources within
a category.   For  similar reasons/the standards may  not  apply
to all  air pollutants  emitted  by  such sources.  Consequently,
 although a source category  may be  selected  to be  covered by  a
 standard of performance, treatment of some  of the pollutants or
 facilities within that source  category  may  be deferred.
 D.  Procedure for Development  of Standards  of Performance
      Congress mandated that sources regulated under section  111
 of the Clean Air Act be required to utilize the best practicable
 air pollution control  technology that has been adequately
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 demonstrated at the time of their design and construction.   In so
 doing, Congress sought to:
      1.  maintain existing high-quality air,
      2.  prevent new air pollution problems, and
      3.  ensure uniform national  standards  for new facilities.
      The selection of standards of performance to  achieve the
 intent of Congress has been surprisingly difficult.   In  general,
 the standards  must (1) realistically  reflect best  demonstrated
 control practice;  (2)  adequately  consider the cost of such control;
 (3) be applicable  to  existing  sources that  are modified  as well
 as  new installations;  and  (4)  meet these conditions for  all
 variations of  operating  conditions  being considered anywhere in
 the country.
     A major portion of  the program for  development of standards
 is  spent  identifying the best  system of  emission reduction which
 "has been adequately demonstrated" and quantifying the emission
 rates  achievable with  the system.   The legislative history of
 section 111 and the court decisions referred to above make clear
 that the Administrator's judgment of what is adequately demonstrated
 is not  limited to systems that are in actual rodtine use.
 Consequently, the search may include a technical assessment
 of control systems which have been adequately demonstrated but
 for which there is limited operational experience.   To date,
determination of the "degree of emission limitation achievable"
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has been commonly based on (but not restricted to)  results
of tests of emissions from existing sources.   This  has
required worldwide investigation and measurement of emissions
from control systems.  Other countries with heavily populated,
industrialized areas have sometimes developed more effective
systems of control than those used in the United States.
     Because the best demonstrated systems of emission reduction may
not be  in widespread use, the data base upon which the standards
are established will necessarily be somewhat limited.  Test
data on existing well-controlled sources are an obvious starting
point in developing  emission limits for new sources.  However,
since the control  of existing sources generally represents
retrofit technology  or was  originally designed to meet  an
existing State or local  regulation, new sources may  be  able
to meet more stringent emission standards.  Accordingly,  other
information must be  considered  and judgment is  necessarily
 involved  in setting  proposed  standards.
      Since  passage of the Clean Air Amendments  of  1970, a
 process for the development of a standard has evolved.   In
 general,  it follows  the  guidelines below.
      1.  Emissions from existing well-controlled sources
          are measured.
      2.  Data on emissions from such sources are assessed with
          consideration of such factors as:  (a) the representativeness
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     of the source tested (feedstock, operation, size, age,
     .etc.); (b) the age and maintenance of the control
     equipment tested (and possible degradation in the
     efficiency of control of similar new equipment even
     with good maintenance procedures); (c)  the design
     uncertainties for the type of control  equipment being
     considered;  and (d)  the degree of uncertainty affecting
     the  judgment that new sources will  be  able to achieve
     similar levels  of control.
 3.   During development of the  standards,  information  from
     pilot  and prototype  installations,  guarantees  by  vendors
     of control equipment,  contracted  (but not yet  constructed)
     projects,  foreign technology,  and  published literature
     are  considered, especially  for sources where  "emerging"
     technology appears significant.
4.   Where  possible, standards are  set at a level that is
     achievable with more than one  control technique or
     licensed process.
5.  Where  possible, standards are set to encourage (or at least
    permit) the use of process modificatio'ns or new processes
    as a method of control rather than "add-on" systems of
    air pollution control.
6.  Where possible, standards are set to permit use of

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        systems capable of controlling more than one pollutant
         (for example,  a scrubber can remove both gaseous and
        partlculate matter emissions, whereas an electrostatic
        precipitator  is specific to particulate matter).
     7.  Where  appropriate, standards for  visible emissions are
         established in conjunction with mass emission standards.
         In such  cases, the standards are  set in such a way that
         a source  meeting  the  mass emission  standard will be able
         to meet  the visible emission standard without additional
         controls.  (In some cases,  such as  fugitive dust, there
         is no  mass standard).
     Finally, when all pertinent data  are  available, judgment
is again required.  Numerical  tests  may not  be  transposed directly
Into regulations.   The design  and operating  conditions of those
sources from which emissions  were actually measured cannot  be
reproduced exactly by each new source to which  the standard of
performance will  apply.
E.  How Costs are Considered
     Section 111  of the Clean Air Act requires  that cost be
considered in setting  standards of performance:  To do this requires
an assessment of the possible economic effects of implementing
various levels of control technology in new plants within a
given industry.  The  first step in this analysis requires the
generation of estimates of installed capital costs and annual

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 operating  costs  for various demonstrated control systems,
 each  control  system alternative having a different overall
 control capability.  The final step in the analysis 1s to
 determine  the economic impact of the various control alternatives
 upon  a new plant in the industry.  The fundamental question to
 be addressed  in  this step is whether or not a new plant would
 be constructed given that a certain level of control costs would
 be Incurred.  Other Issues that would be analyzed 1n this step
 would be the effects of control costs upon product prices and the
 effects on product and raw material supplies and producer
 profitability.
     The economic Impact upon an industry of a proposed standard
 1s usually addressed both 1n absolute terms and by comparison
wfth the control costs that would be incurred as a result
of compliance with typical  existing State control regulations.
This Incremental approach is taken since a new plant would
be required to comply with State regulations 1n the absence
of a Federal  standard of performance.   This approach requires
a detailed analysis of the Impact upon the Industry resulting
from the cost differential  that usually exists between the
standard of performance and the typical  State standard.
     It should be noted that the costs for control  of air
pollutants are not the only control costs considered.   Total
environmental costs for control  of water pollutants as well

                             x1v

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as air pollutants are analyzed wherever possible.
     A thorough study of the profitability and price-setting
mechanisms of the industry is essential to the analysis so
that an accurate estimate of potential adverse economic impacts
can be made.  It is also essential to know the capital requirements
placed on plants in the absence of Federal standards of performance
so that the additional capital requirements necessitated by these
standards can be placed in the proper perspective.  Finally, it
is necessary to recognize any constraints on capital availability
within an industry as this factor also influences the ability
of new plants to generate the capital required for installation
of the additional control equipment needed to meet the standards
of performance.
     The end result  of the analysis is a  presentation of costs
and potential economic impacts for a  series of control
alternatives.  This  information  is then a major factor which
the Administrator considers  in selecting  a standard.
F.  impact  on  Existing Sources
     Proposal  of standards  of performance may affect  an existing
source  in either of  two ways.  First, if  modiffed after
proposal  of the  standards,  with  a subsequent  increase in
air pollution,  it  is subject to  standards of  performance  as
if 1t were  a new source.   (Section 111  of the Act defines  a
new  source  as  "any stationary source, the construction or
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 modification of which is commenced after the  regulations  are
 proposed.")^/
      Second, promulgation of a  standard  of  performance  requires
 States to establish standards of performance  for the same pollutant
 for existing sources in  the  same industry under section lll(d) of
 the Act;  unless the pollutant limited by the  standard for new
 sources is one  listed under  section 108  (requiring promulgation of
 national  ambient air quality standards)  or  one listed as a
 hazardous pollutant under section  112.   If  a  State does not act,
 EPA must  establish  such  standards.  Regulations prescribing
 procedures for  control of existing sources  under section lll(d)
 will  be proposed as  Subpart  B of 40 CFR  Part  60.
 G.   Revision  of Standards  of Performance
      Congress was aware  that  the level of air pollution control
 achievable by any industry may improve with technological
 advances.   Accordingly,  section  111 of the Act provides that
 the Administrator may revise  such standards from time to time.
Although  standards proposed and promulgated by EPA under section 111
are designed to  require  installation of the "... best system of
emission  reduction  ... (taking into account the cost)..."
the standards will be reviewed periodically.  Revisions will be
proposed  and promulgated as necessary to assure that the.standards

     |7Specific provisions dealing with modifications to existing
facilities are being proposed by the Administrator under the
General Provisions of 40 CFR Part 60.
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continue to reflect the best systems that become available
in the future.  Such revisions will not be retroactive but
will apply to stationary sources constructed or modified after
proposal of the revised standards.
                            xv11

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                          TABLE OF CONTENTS
Section                                                   Pa9e

Introduction	     1
Summary of Proposed Standards	     2

Description of Process	     3
   Wet Cleaning Systems	     4
   Dry Cleaning Systems	     7

Emissions and Methods of Control	     9
   Wet Cleaning Systems	     9
   Dry Cleaning Systems	    10

Existing Air Pollution Standards	    10

Rationale for Proposed Standards	    H
   Selection of Pollutants for  Control	    11
   Selection of Units for Standard	    13
   Selection of Sampling and Analytical Methods	    16
   Discussion of Standards Development	   17
       Wet Cleaning  Systems	   23
       Dry Cleaning  Systems	   27
   Visible  Emission Data	   29
   Conclusions	   30
Environmental  Impact of  Proposed  Standards	   31
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Economic Impact of Proposed Standards	 32
References	 39
Bibliographic Data Sheet	 40
                                 xx

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INTRODUCTION
                       *
     "Coal preparation" is one segment of the coal  industry.   Coal
preparation encompasses operations between the mining of raw coal
and the distribution of product coal.
     The extent of preparation and type of processing depend upon
the physical character and chemical composition of the raw coal and
the customer specifications on product coal.  Coal  preparation is
therefore a function of the demand for an improved quality product.
     Coal preparation  plants were specifically named as major sources
of air pollution in 40 CFR Part 52 "Prevention of Significant Air
Quality Deterioration," published as proposed in the Federal Register.
July 16,  1973.  One study on emissions from  coal preparation esti-
mated that  particulate emissions  from  thermal dryers alone exceeded
150,000 tons in 1968.

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SUMMARY OF PROPOSED STANDARDS
                                       »
     Standards of performance are being proposed for new coal
preparation plants.  The proposed standards would limit emissions
of particulates (including visible emissions) from the following
sources, which are the affected facilities:  thermal driers,
pneumatic coal-cleaning equipment (air tables), coal processing
and conveying equipment (including breakers and crushers), screen-
ing (classifying) equipment, coal storage, coal transfer points,
and coal loading facilities.
     The standards apply at the point(s) where undiluted gases are
discharged from the air pollution control system or from the affected
facility if no air pollution control system is utilized.   If air or
other dilution gases are added prior to the measurement point(s),
the owner or operator must provide a means of accurately determining
the amount of dilution and correcting the pollutant concentration to
the undiluted basis.
     The proposed standards for these sources would limit parti oil ate
emissions to the atmosphere as follows:
Particulate Matter from Thermal  Driers
     1.   No more than 0.070 gram per dry standard cubic meter (0.031 grain
         per dry standard cubic  foot).
     2.   Less than 30 percent opacity.
Particulate Matter from Pneumatic Coal-Cleaning Equipment
     1.   No more than 0.040 gram per dry standard cubic meter (0.018
         grain per dry standard  cubic foot).

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     2.  Less than 20 percent opacity.
Particulate Matter from Other Affected Facilities
     Less than 20 percent opacity.
DESCRIPTION OF PROCESS
     Coal in its natural state contains impurities such as sulfur,
clay, rock, shale and other inorganic materials, generally called
ash.  Coal mining also adds more  impurities.in the form of mine rock,
dirt, tramp iron and wood.  To remove these impurities, coal prepara-
tion plants utilize the difference in specific gravities to separate
coal from the heavier contaminants.
     Since this  separation  depends on the coal and impurities already
being  separate entities,  the  larger  coal lumps must be.broken up  to
free entrapped impurities.   Thus  impurities which occur as  finely
divided  mixtures in  coal  are  more difficult to  remove  than  the  coarser
materials, e.g., pyritic  sulfur  is much more  difficult to remove  than
 rock or  shale.   Scalpers  and magnets remove wood and  iron prior to
 size reduction.
      Coal  preparation  plants prepare various  types  of coal  in  response
 to market demand.   Three  types of preparation plants  are  common:
 (1) "complete preparation," those that clean  both coarse  and fine
 coal; (2) "partial preparation," those that clean only coarse  coal;
 and (3)  "coal crushing,"  where the coal  is merely crushed to a
 specified maximum size.  Since all features of the two other types
 are incorporated into the complete preparation plant, only it will
 be described.

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      Figure  1 is a schematic diagram of a complete coal preparation
 facility.  Coal from the mine is broken and screened to remove over-
 size  material, then stored until the batch processing in the plant
 is begun.  Secondary breaking or crushing is sometimes necessary to
 ensure good  separation of coal from impurities in the cleaning plant.
 Classifying  screens separate coal particles by size and route them
 to various cleaning processes represented by the "cleaning process"
 portion of the diagram.  In general this cleaning process may be
wet,  dry, or a combination of both.
Wet Cleaning Systems2
      Wet cleaning systems utilize centrifugal or gravity separation
 of heavier rejects from coal (see Figure 2).  None of the variety
of wet cleaning methods emit pollutants.  However, the auxiliary pro-
 cesses of handling and drying can be major sources.  After the coal
is wetted by the cleaning process, it is dried mechanically by de-
watering screens followed by centrifugal driers.   Removing excess
moisture from coal decreases shipping costs, increases the higher
heating value of coal, and prevents freezing in very cold climates.
     Where customer demand is for low surface moisture (3 to 6 percent)
of finer coal sizes,  secondary drying is required.  Such low moisture
levels can best be accomplished by thermal  drying.  It appears that
new coal  preparation  plants that install thermal  driers will use a
fluid-bed type.
      In the fluid-bed drier, hot combustion gases from a coal-fired
furnace are passed upward through a moving  bed of wet coal  of fine

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       BREAKER
FROM
MINE
STORAGE
  SILO
 FIRST
SCREENS
                                                               CRUSHER
SECOND    CLEANING
SCREEN     PROCESS
          EQUIPMENT
                                                                                                           STORAGE
                                                                                                             SILO
                                                                                                    LOAD-
                                                                                                     OUT
                        Figure 1.  Flow diagram for coal cleaning plant (for section A - A', see Figures 2 and 3).

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             RAW COAL IN
                                                             TO
                                                          STORAGE
Figure 2. Wet cleaning circuit process.

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particle size.   As the bed fluidizes, the coal  is dried as the
fine particles  come into intimate contact with  the hot gases.
Particulate emissions occur predominately from ultrafine (-200 mesh)
coal particles which are entrained and carried from the drier by the
combustion gases.
     The primary  control device, a dry centrifugal collector  (orig-
inally justified  primarily to recover product, thereby increasing
yield),  can retain  up  to 95 percent  of the entrained  fines.   These
are  returned to  the product coal.  All secondary emission  control
systems  are wet  collectors.  The high dew point  and explosion potential
of the  exhaust gas  make other emission control systems  impractical.
The dried coal is conveyed to storage where  it remains  until  being
 loaded into railroad cars, trucks, or  barges.
 Dry Cleaning Systems
      Since 1966, all dry coal  cleaning systems in operation have used
                                                             2
 pulsating air columns to separate coal  from reject material.   Figure
 3 is a schematic diagram of such a system.   Coal containing refuse
 particles enters the air table where it  is stratified into a bed by
 pulsating air.   The heavier refuse settles in a  layer beneath the
 coal.  As the bed  travels forward,  the  refuse drops  into  packets or
 wells from which it is withdrawn  to the refuse  bin.  The  upper layer
 of  coal  is removed as  it  completes  its  travel over the slowly moving
 bed of  refuse.   Dust,  entrained and airborne  by the  pulsating air,
 is  drawn  into an overhead hood  to be recovered  by  cyclone dust

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                                                     RAW COAL IN
CO
                                                                                          SECONDARY
                                                                                          COLLECTORS
                                                                                            PRIMARY
                                                                                          COLLECTORS
                                                                                                         TO
                                                                                                  / STORAGE SILO
                                                          Figure 3.  Dry cleaning process.

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collectors which have been installed based on economical  product
recovery.  Secondary collectors, which are added for control of air
pollution, are usually fabric filters.
EMISSIONS AND METHODS OF CONTROL
     Emissions from uncontrolled coal preparation plants include
NO  , SO  , CO and fine particulates from thermal drying.  Particulate
  A    C>
emissions come from crushing, screening, storage, transfer, grinding,
conveying, or loading operations.  Particulate emissions, at times
severe and highly  visible, increase  as the surface moisture in  the
coal decreases.  Their  control  requires good capture  of  the emissions
which must then  be fed  to  a  control  device.   None of  the plants
attempt  to control combustion products or S02>
Met Cleaning  Systems
      Thermal  driers in  a coal plant  which uses wet  cleaning incorporate
 cyclones as  an  integral part of the  coal  cleaning  process.   Potential
 particulate  emissions upstream  of the cyclone have  been measured in
 the range of 50 to 200 grains per dry standard cubic foot (gr/dscf)
 for fluid-bed driers.3  Emissions measured downstream ranged from
 0.7 to 14 gr/dscf.  An average emission factor often used for  fluid-
 bed driers without secondary control is 3.0 gr/dscf.  (With 3.0
 gr/dscf, a 500-ton-per-hour thermal  drier would emit over 5,000
 pounds of particulates per hour.)
      Well-controlled thermal driers  with high-efficiency, venturi-
 type wet scrubbers reduce particulate emissions to less than 0.03
 gr/dscf.  This  is equivalent to  about 99 percent control efficiency.

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 Dry Cleaning  Systems
      Implementation of new  health  and safety  regulations within the
 coal  mines  resulted in addition  of increasing amounts of water to
 coal  to  minimize  dust  inhalation and reduce its explosive hazard.
 This  has resulted in a rise in the surface moisture of coal from
 underground mines and  has caused a corresponding reduction in emis-
 sions  from  air tables  which have a control device.  Measurements
 prior to 1970 indicated grain loadings of 0.16 gr/dscf from plants
 which  had only a  primary control device.  A 70-tons-per-hour air
 table  with  such control could emit up to 50.pounds per hour.  In
 1973  this same facility would emit only 10-15 pounds per hour.  Fabric
 filter secondary  collectors  have been reported to further reduce emis-
 sions  to  less than 0.01 gr/dscf.3  A fabric filter collector is a dry
 process  and all dust which  it recovers becomes part of the product.
 EXISTING AIR POLLUTION STANDARDS
     Most States  do not have specific air pollution limitations for
 coal preparation  plants but rather make them subject to a general
 process weight regulation.    This  type of restriction is not uniform.
 For example, under the most restrictive such regulation, a 500-tons-
 per hour thermal  drier could emit 70 pounds of particulate each hour,
 approximately equivalent to an exit-gas concentration of 0.035 gr/dscf.
A smaller air table with a capacity of 75 tons per hourVould be allowed
to emit 48 pounds per hour,  an exit-gas concentration of approximately
0.150 gr/dscf.
                              10

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     Three States have codes applicable exclusively to  coal  prepara-
tion plants.4  The most restrictive is 0.02 gr/dscf for thermal  driers
and air tables with capacities above 100 tons per hour.  However, it
permits exit concentrations to increase with decreasing capacity.
     All coal-producing States have a general visible emission re-
striction that limits all sources to a maximum 20 percent opacity.
RATIONALE FOR PROPOSED STANDARDS
Selection of Pollutants for Control
     The only pollutant evolved from air tables is particulate.  Emis-
sions  from thermal driers  include combustion products  from  the coal-
fired  furnace, but these quantities of emissions  are a small fraction
of the particulates  entrained by the  flue  gases passing  through  the
fluidized  bed of coal.   Initial emission samples  from  thermal driers
were analyzed for products of combustion and heavy metals.  Table  1
presents  the results of the analyses  of combustion products.  The  table
permits a comparison with  the standards  of performance for  coal-fired
power plants.
      Both NOX and S02 emissions  were  found below the performance
 standards required of new coal-fired power plants.  Admittedly  the
 driers tested were processing (and using as fuel) low-sulfur coal.
 However, only 12 percent of all  thermally dried coal is greater than
 2 percent sulfur, primarily because thermal drying of lower quality
 coals is not generally an economically attractive alternative.
       For those few  driers that may thermally dry high-sulfur coal in
 the future, the cost of controlling S02 emissions is  considered un-
 reasonable.  The largest  thermal driers at  500 tons per hour bum
                               11

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                                      TABLE 1

                          COMBUSTION PRODUCT EMISSIONS FROM

                           WELL-CONTROLLED THERMAL DRIERS
Pollutant Concentration, ppm
N0x
S0x
HC (as methane)
CO
40 to 70
0 to 11.2
20 to 100
< 50
L-iiii^aiuii r a it*? ,
0.39 to 0.68
0 to 0.09
0.07 to 0.35
<0.30
                                                                    Coal-fired  power.piant»e
                                                                        lh/(Rtu Y  in6)

                                                                            0.70

                                                                            1.20
Standards of Performance for Fossil-Fuel-Fired  Steam  Generators as promulgated  in
                                        12

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approximately 5 tons per hour coal as fuel.   The accompanying
furnace would be rated at 130 million BTU/hr which is less than
the smallest power plants required to control S02 emissions under
standards of performance.
     Finally the wet scrubbers used to control particulate emis-
sions from thermal driers also appear to control S02 emissions.
The two driers tested emitted S02 at 0-10 percent of the levels
expected, based on firing rate and fuel sulfur content.
     For these reasons no standards for S02 or NOX were proposed.
Standards for hydrocarbons and carbon monoxide were also rejected
because the emission levels were  low.
     Table 2 shows a typical analysis of the  heavy metals  content
of particulates emitted  from thermal driers.  The largest  well-
controlled thermal driers  (500 tons/hr feed  and  50  Ib/hr emissions)
would discharge less than 0.005  Ib/hr arsenic.   Emissions  of  other
heavy metals are  somewhat  lower.  Since most  heavy metals  are emitted
as particulates,  a particulate standard limitation will also  control
these pollutants.  Hence,  only standards of  performance have  been
recommended  for particulate  emissions from coal  preparation  plants.
Selection of Units  for  the Standard
     Both mass  and  concentration units were  considered for the stand-
ard.  A limitation  on mass  (such as  pounds of particulate  emission
per  ton of  coal feed) has  the  advantage of being universally restric-
tive in that it precludes  circumvention by  the addition of dilution

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                                TABLE 2
  "PACE METALS ANALYSIS OF PARTICULATE EMISSIONS FROM A COAL DRIER

                 Concentration,                           Concentration,
Element              ppmwa              Element              ppmwa
Be
Cd
As
V
Mn
Ni
Sb
Cr
Zn
Cu
Pb
Se
B
F
Li

Ag
Sn
Fe
Sr
Na
1
«50
< 100
50
50 to 100
20 to 30
< 50
30
< 100
30
< 30
—
10
--
< 10

< 1
< 50
5000
100
300
K
Ca
Si
Mg
Bi
Co
Ge
Mo
Ti
Te
Zr
Ba
Al
Cl"
so"
4





1000 to 2000
3000
1.5%
1000
< 10
< 10
< 30
< 10
500
< 100
10
200
1.0%
40 to 118
1040 to 3920






  a  Parts per million by weight.
                                  14

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air.  Such a standard would require an accurate determination  both
of mass emission rate and the weight of the feedstock to the pro-
cess.  Also an operator could defeat a mass standard by adding
coarse coal to the drier feed, resulting in a significantly larger
process weight and little change in emissions.
     A limitation based on concentration (such as 0.03 grain per
dry standard cubic foot) requires limited knowledge of coal feed
rates.  Although this type of standard could conceivably be
circumvented by dilution, such action would not be an economically
viable option to the operator for the following reasons:
     1.  A thermal drier operates most efficiently with a maximum
         temperature differential (limited only by safety considera-
         tions) between the hot combustion gases and the coal  bed.
         Consequently dilution of the hot combustion gases with much
         cooler ambient air would reduce drying efficiency and
         increase fuel costs.
     2.  Introduction of air between the drier and the final control
         device would not achieve any operating cost savings since
         the horsepower required to move the greater volume of air
         at lower pressure through a lower energy control device is
         equivalent to that required to move the lower volume  of
         air at the greater pressure with the higher energy venturi
         type scrubbers.
     3.  Introduction of air downstream of the control device  is not
         only specifically precluded, but such adulterations to the
         typical control device would be obvious.
                                15

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     It was concluded that concentration units,  grains  per dry
standard cubic foot (gr/dscf),  should be used for the standards
of performance for coal  preparation plants,  with a suitable in-
clusion to prevent circumvention by dilution air.   This conclusion
is based on the following:
     1.  Only precise measurement of emissions is required to
         enforce a concentration standard.
     2.  Less precise information on feedstock or product weights
         is required for a concentration standard than  for a mass
         standard.
     3.  Emission data used as  a basis for  development  of the stand-
         ards of performance were measured  in concentration units.
         Since process feed rates were merely estimated, data to
         support a mass  standard would be less reliable.
     4.  A mass standard based  on process weight would  be ineffective.
         An operator could circumvent the standard by passing the
         larger sizes of coal through the drier, which  could increase
         process weight significantly without increasing emissions.
Selection of Sampling and Analytical Methods
     All tests of particulate emissions conducted under EPA contract
to provide a basis for proposing standards  of performance have used
Method 5, "Determination of Particulate Emissions from  Stationary
Sources," as described in Appendix A of 40  CFR Part 60.  Therefore,
                 i
it was  concluded  that the proposed standards should be based on the
same method.
                              16

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     Most control  devices now in operation discharge exhaust gases
in a swirling pattern.   Any flow pattern other than one parallel
to the stack wall  has a detrimental  effect on the accuracy of standard
measurement techniques.  For this reason, it was concluded that the
standard should require new control  systems for thermal driers and
air tables to discharge exhaust gases in parallel flow and to pro-
vide sufficient stack height for representative sampling according
to EPA Method 5.
Discussion of Standards Development
     Early investigation (which included the preliminary results of
an industry study by EPA and discussion with local control agencies,
manufacturers of control equipment, and the industry trade association)
revealed the location of several reportedly well-controlled coal
preparation plants.  Of the approximately 130 in the nation which have
thermal driers or air tables, 31 were visited to obtain information
on the emission control system.  During the visits, the plants were
critically appraised to determine those which represented the best
demonstrated air pollution control technology for the industry.  The
general criteria used were:  (1) the opacity of plant emissions,
(2) results of previous emission tests,  (-3) air pollution control
equipment and operating techniques,  (4) suitability of control equip-
ment for testing, and  (5) maintenance practices.
     Communications with persons knowledgeable in coal preparation
indicated the major variable which contributes to particulate emissions

                                17

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from thermal driers is the size distribution of the feed.   To
ensure results of the program were not biased optimistically, it
was decided to test installations which processed the largest per-
centage of "fines" but utilized what appeared to be the best system
of emission reduction.  Consequently, a specific criterion for
selection of test sites was high fines content in the feed ,to the
drier.  Representatives of the coal industry, manufacturers of thermal
driers, and vendors of control equipment indicated coal from the
Pocahontas coal region of West Virginia and Virginia is the most
friable and hence most difficult to control.  As a result, all but
one of the plants which was sampled processed coal from the Pocahontas
seam.  In all tests by EPA, the maximum available amount of fines was
fed to the drier.
     Although not apparent during the initial visits, the mode of
flow of the exhaust gas was to become a very important consideration
in the evaluation of the results of emission tests.  Figure 4 repre-
sents the general type of control system used by all plants that were
selected for testing.  Exhaust gases from the primary collector pass
through a venturi-type wet scrubber which may operate at pressure
differentials of  15 to 32 inches water gauge (but which may be raised
as high as 57 inches).  Water consumption was about 8 gallons per
minute per 1,000  cubic feet per minute of gas cleaned.
     The exhaust  gases entrain water from the scrubber which  is re-
moved by a mist eliminator.  Gases enter the cylindrical mist
eliminator tangentially and flow upward in spiral flow.  In theory,

                               18

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                      SAMPLING
                       PORTS
Figure 4.  Venturi scrubber-mist eliminator.
                    19

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the water is centrifugally thrown  to the  cylinder wall where  it
flows by gravity to a drain.   Mist eliminators  of this design can
present two problems to accurate emission mi  surement:
     1.  The design parameters used by at least one  manufacturer
         appear inadequate because significant  amounts of water
         exit from the top of the mist eliminator.   High  gas  velo-
         cities in the stack continue to  carry  water up  the stack
         wall until it is ejected from the top  of  the stack by the
         turbulent gas stream.  A steady  "rain" of  black, dust-laden
         water was evident in the vicinity of such  stacks.  Several
         of these systems had been retrofitted with  a "catch-ring"
         as shown in Figure 5.  It is designed to  capture the water
         which is carried over and return it to a  drain.   The effi-
         ciency of these catch rings appears moderate to poor.
         Obviously, the contribution to total emissions  of the random
         emissions of mist cannot be accurately measured.
         A  similar collector  by another manufacture  (Figure 6) differs
         in  three obvious aspects:   (1)  the length-to-diameter ratio
         of the mist eliminator is  greater,  (2) it has a  taller stack,
         and (3)  it has a proportionately larger stack diameter which
         permits  lower gas velocity  within the stack.  The exhaust
         streams  from mist eliminators made  by this  manufacturer con-
         tain little or no entrained water.
                                20

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CATCH
 RING
                                                                                   DRAIN
   STACK WALL
                                 Rgure 5.  Retrofitted catch ring.

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                                      SAMPLING
                                        PORTS
                              STRAIGHTENING
                                  VANES
                                                         L-.L-.J
                    VENTURI
                    THROAT
Figure 6.  Venturi scrubber-mist eliminator with straightening vanes.
                                    22

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     2.   The cyclonic flow patterns common to all  cylindrical  mist
         eliminators make measurements of particulate emissions
         suspect.
Wet Cleaning Systems
     Twenty-eight thermal driers were inspected.  These were of
various designs, processed a variety of coals, and utilized wet
scrubbers of various designs.  Of these, five fluid-bed driers
were selected for emission measurement because it is expected that
new driers will be of the fluid-bed type.  EPA tested three of these
facilities, designated C, D, and E in Figure 7.  All utilize a mist
eliminator with the poorer efficiency.  Plant C, the only plant with
permanent straightening vanes, was tested twice.  The first test
(C,) showed average particulate emissions of 0.014 gr/dscf, the second
test (C2) 0.019 gr/dscf.
     Emissions from Plant D were evaluated on two separate occasions.
The first test  (D-j) indicated an average  emission rate of 0.017 gr/dscf
(without vanes).  Two additional series of tests at  a later date were
taken in quick succession in an attempt to reveal the effect of
straightening vanes.  Without vanes  (test D2),  average emissions were
0.024 gr/dscf.   With temporary  straightening  vanes  installed as shown
in Figure 8, three  samples  averaged  0.044 gr/dscf  (test  D3).   Also,
with the vanes  installed, the visibility  of  the particulate-laden  "rain"
increased notably.  As might be expected, the straightening vanes  appear
to nullify  the  centrifugal  flow and  the  effectiveness  of the  catch ring.
                                23

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            0.06
            0.05
            0.04
        I
        i

        !  0.03
        UJ
        LLJ


        3


        2  0.02
            0.01
                   ft
                                             I I
                                             1^1

                                             * t
                                  t I
                                  0
                                                               AVERAGE
                                                           d
                                                           • EPA TEST METHOD
                                                           O OTHER TEST METHOD
                                                                     b
   "PLANT G!    C2     DI    02     03     EI     ii     F     G     H
NO. OF RUNS'3     3     33      3      2     2     4     3     2
                                                                                  0
                                                                                   2
FIGURE  7.   Particulate emissions  from thermal  dryer exhausts  controlled by wet  scrubbers.

                                              24

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                                  SAMPLING
                                   PORTS
                          STRAIGHTENING
                             VANES
                                     WATER
                                     INLET
                                                     MIST
                                                  ELIMINATOR
Figure 8.  Venturi scrubber-mist eliminator with straightening vanes.
                               25

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     The scrubber at Plant E operated with the lowest energy con-
sumption, 21 inches of water.  This plant was also sampled on two
occasions.  During the test labeled E, on Figure 7, the drier was
operating normally.  The surface moisture content of the product coal
was about 3 percent.  However, when the test represented by point E?
was made, the surface moisture content of the product coal was about
1.2 percent, far below normal.  "Overdrying" of coal is generally
acknowledged to greatly increase particulate emissions.  For this
reason, data from test E~ were not considered in the selection of
the standard.
     Test results shown for Plants F, G, H and I were provided by the
industry.  Only the results of the test on Plant H, 0.029 gr/dscf,
were reportedly obtained using EPA methods.  The methods used at the
other  plants is not known.  The proposed standard of 0.031 gr/dscf
is supported by measurements of emissions at all plants tested.  There
are two instances where the proposed standard was exceeded.  The first
occurred when flow straighteners were inserted at Plant D.  This ob-
viously increased emissions because the discharge of dirty water in-
creased.  (Doubtlessly the particulate in the dirty water reentrained
from the stack wall after installation of flow straighteners was
largely responsible for the difference in test results D« and D~.)
Secondly, during test Ep coal was being dried to about 1 percent sur-
face moisture, well below the 2 percent threshold at which dust emis-
                    5
sions become severe.   The overdrying was confirmed both by moisture
analysis on the product coal and the abnormally high temperatures
recorded on the drier exit monitor.
                               26

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     Vendors of control  equipment have guaranteed emissions  of less
than 0.030 gr/dscf.  'One vendor has guaranteed 0.020 gr/dscf,  while
another is considering such a guarantee.  *    Based on these  findings
it is the Administrator's judgment that the achievability of the pro-
posed standard of 0.03 gr/dscf for partlculate emissions from thermal
driers has been adequately demonstrated.
Dry Cleaning Systems
     Of the 37 plants that operated air tables in 1972, 13 had emis-
sion control equipment.   EPA representatives visited three plants.
Two, which used fabric filters for control, exhibited no visible
stack emissions and were subsequently tested.  The third, which had
no air pollution control ..device, showed visible emissions of greater
than 20 percent opacity.  Results of the two series of tests on the
air tables with fabric filter controls are presented in Figure 9.
Particulate loadings averaged 0.008 gr/dscf and 0.005 gr/dscf for
Plant A and B, respectively.  Figure 9 also presents, as test B2,
emission data provided by the operator of Plant B.  Their results
averaged 0.007 gr/dscf and ranged from 0.004 to 0.011.  Based on these
findings it is the Administrator's judgment that  the achievability
of an 0.018 gr/dscf particulate emission standard for pneumatic
cleaning has been adequately demonstrated.
     A projected decline in  the  use of air tables (substantiated by
the small number of new  installations during  the  past 2 years) dimin-
ished the requirement for extensive testing.  Although  it is  expected
                              27

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        1 0.02
          0.01
       3
       on
                        14
                                                14
                                                0
                                                                H-H AVERAGE
                                                                 O
                                                                 ©EPA TEST METHOD
                                                                 O OTHER TEST METHOD
17
                   PLANT  A
              NO. OF RUNS  2
 10
FIGURE 9.  Particulate emissions  from air table exhausts  controlled by fabric filters.
                                           28

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that few new air tables will  be constructed,  the  standard  is  proposed
because they are still  available from equipment vendors.
Visible Emission Data
     Visible emission readings were made at well-controlled
coal preparation plants operating at or near  design rates.  The
sources monitored at each of two plants were:
     (1)  thermal drier exhaust, controlled by 35" AP venturi
          scrubber,
     (2)  breaker and raw coal transfer exhaust, controlled by a
          fabric filter,
     (3)  cleaned coal transfer exhaust, controlled by a fabric
          filter, and
     (4)  cleaned coal loadout exhaust, controlled by a 6" AP wet
          scrubber.
     One plant showed visible emissions of 10 percent or less from
all sources monitored during a 7-hour period.  A second plant ex-
perienced frequent upsets in which visible emissions from all sources
exceeded 20 percent.  Duuring normal operation visible emissions
from all sources at  the  second plant were 10 percent opacity or less.
     Visible emissions from both thermal driers exceeded 20 percent
during  routine startups  and shutdowns.  These periods of excessive
visible emissions were 10-20 minutes for startups  and 10-15 minutes
for shutdown.
                                29

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 Excessive visible  emissions would  be  expected  from a startup or
 shutdown; however, these  periods are  exempt  from the standards
 [40  CFR 60.11(c)].
      Furthermore,  visible emissions from wet scrubber exhausts are
 a  function  of  ambient  atmospheric  conditions.  Visible emissions
 on a  cold,  damp day are masked by  uncombined water vapor, hence may
 be zero while  the  same exhaust on  a hot, dry day may exhibit emis-
                                               «
 sions  of 20 percent opacity.  Therefore, it is concluded that a
 "cushion" should be included in the opacity limits for thermal driers
 to compensate  for  the seasonal variations in visible emissions.
      It is  the policy of  EPA in proposing particulate emission stand-
 ards  to include visible emission standards as  an enforcement tool.
 Since  the operator of an  affected  facility may be penalized for viola-
 tion  of these visible emission standards, they are established such
 that  a  violation of a visible emission standard would unquestionably
 indicate  a  simultaneous violation  of the particulate standard.
     Thus,  a 30 percent opacity limit for thermal  driers during normal
 operation is proposed, while for all other sources which are unaffected
 by operating parameters or seasonal variations, a 20 percent opacity
 limit is proposed.
 Conclusions
     The proposed particulate emission standards of 0.031 gr/dscf for
 thermal driers and 0.018 gr/dscf for pneumatic coal-cleaning equip-
ment are supported by emission measurements by EPA on Plant C, D, and
 E and Plants A and B, as presented in Figures 7 and 9,  respectively.
                             30

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Proposed opacity standards of less than 30 percent for thermal  driers
and less than 20 percent for air tables and all  other affected
facilities are supported by visible emission observations.   The
standards will require installation and proper maintenance of equip-
ment representative of the best technology wh-ich has been demonstrated
for the industry.  In the Administrator's judgment, the achievability
of the proposed standards has been adequately demonstrated.
ENVIRONMENTAL IMPACT OF PROPOSED STANDARDS
     Coal preparation plants generate large quantities of solid wastes
and waste water.  Solid wastes include mine rock scalped from raw coal
and fine impurities from wet coal cleaning.  Liquid wastes are gen-
erated by wet coal washing and scrubber discharges.
     For a typical coal preparation plant processing  600 TPH raw
coal, approximately 180 TPH of solid refuse and 4500  gpm waste water
are generated.   A wet scrubber  used to meet the  proposed  thermal
drier standard would  contribute  640 gpm waste water and  1.54 TPH
solids  in the waste water discharge.
     Since all  plant  waste waters  are  clarified and reused in  plant
processing no water pollution will  result.  Solids  in the  scrubber
liquid  discharge may  or may  not  be  reclaimed  as product  coal.   If the
scrubber  solids  are discharged with other solid refuse the contribu-
tion is  less than  one percent  of total wastes.  With the rising  price
of coal,  it  seems  unlikely that  new preparation plants would discard
the 1.54 TPH fine  coal  in scrubber liquids.
                                31

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      In dry  coal processing, all material captured by emission
 controls  is  returned to the process.  No water is used by best
 emission  controls.  Thus no water or solid waste pollution is
 generated.
      Energy  requirements of emission controls used to meet the pro-
 posed standards for thermal driers are roughly 3 kilowatt-hours per
 ton of coal  dried.  Based on anticipated growth of 5.6 million tons
 per year  of  dried coal, the annual energy consumed by new thermal
 drier controls would be 16.8 x 106 kilowatt-hours.  Of this, one-third
 or 5.6 x  10^ kilowatt-hours would be used to meet Federal standards
 over existing State standards.
     Since zero growth is anticipated for dry coal cleaning, no
 additional energy is required to meet the proposed standard.
 ECONOMIC  IMPACT OF PROPOSED STANDARDS
     The  outlook for growth in the coal  cleaning sector is clouded
 by several factors.  Current restrictions imposed by State Implementation
 Plans on  the burning of high-sulfur coal  could cause dislocations in
 the Eastern coal-producing areas during  the next few years.   The use
 of air tables, one of the two prime sources of particulate pollution,
 may be discontinued.  Compliance with Department of Interior dust
 abatement regulations promulgated under the authority of the Coal Mining
 Health and Safety Act results in a high  moisture content in  the coal
which renders the coal  unsuitable for air table processing.
     Nevertheless, long-term forecasts of energy requirements indicate
 a rise in cleaned coal  requirements from 323 million tons in 1970 to
580 million tons in 1985.   The new thermal  driers required for this

                                32

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expansion plus replacement driers,  which historically have run  at
about 4 to 5 percent of existing capacity per year, indicate that
nine new driers per year will  be required.   No new or replacement
air table installations are projected.
     Essentially all of the current coal cleaning operations are
subject to particulate regulations.  Figures 10 through 12 show the
proposed standard of performance in relationship to existing State
regulations covering 88 to 98 percent of the coal cleaned.  Air
table operations are typically controlled by a fabric filter and
this control device is capable of meeting all existing State regula-
tions as well as the proposed standard of performance of 0.018 gr/dscf.
Therefore, if a fabric filter capable of handling the entire air table
effluent is installed, it will, if adequately maintained, meet the pro-
posed standard and  result in no adverse economic impact.
     Emissions from thermal driers are universally controlled by wet
scrubbers.  A significant explosion potential exists as hot gases come
in contact with finely divided coal.  Electrostatic precipitators have
not been considered for this reason.  Fabric filters are generally un-
suitable for the same  reason and because the high dew point of the
gases could result  in  blinding the filtration surfaces.  The degree
of control available from wet scrubbers is a function of the pressure
drop across the unit and thus cost is directly proportional to the
emission limits.  Table 3 depicts the maximum impact of the proposed
standards of performance  (0.031 gr/dscf) for driers by comparing it
to the 0.07 gr/dscf standard of a State where 49 percent of the thermally
                                  33

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£      —
                \/  \   \  \\\\\\
                                                 \   \  \  \\ 11
      104
105
                                                PROCESS WEIGHT, Ib/hr
     SOURCE: STATE IMPLEMENTATION PLANS, BUREAU OF MINES

          Figure 10.  Proposed thermal drier regulation (0.031 gr/dscf) compared with existing State regulations
          (62% of 1971 production represented) - basis: 24,000 dscf/ton.

                                                     34

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X
                                                      I      I    I    I  I  MM
                                                    PROCESS WEIGHT, Ib/hr
       SOURCE:  IMPLEMENTATION PLANS

             Figure 11.  Proposed air table regulations (0.018 gr/dscf) compared with existing State regulations
             (98% of 1971 production represented)  - basis:  30.000 dscf/ton.

                                                             35

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o
S3
                                                    PROCESS WEIGHT, Ib/hr
        THIS REGULATION WAS PROPOSED FOR UTAH IN THE FEDERAL REGISTF.r, JULY 27,1972, TO BE PROMULGATED BY EPA.

        SOURCE: STATE IMPLEMENTATION PLANS, BUREAU OF MINES.

            Figure 12.  Proposed thermal drier  regulation  (0.031 gr/dscf) compared with existing State regulations
            (26% of 1971  production represented) - basis:  24,000 dscf/ton.

                                                             36

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dried coal is produced.  The State standard will  require  a unit
with 16 inches of water pressure drop.   To meet the proposed
standard a pressure drop of 25 to 35 inches water gauge is required.
The operating costs are geared for that level.   However,  prudence
would dictate the purchase of equipment capable of doing  better
than just meeting the current regulation.  Therefore, where possible,
the equipment is sized to provide 10 more inches of water pressure
drop than that required by regulation.
     Table 3 shows that the total drier investment will be increased
by about  3 percent.
     Annualized operation costs including additional power, maintenance,
taxes, insurance, depreciation, and interest charges were in the
range of  6.5<£ per ton  of coal cleaned for the plant sized considered.
     The  after-tax drop in net income, if the increase cannot be
passed on, is anticipated at  less than 1 percent.  However, since the
price of  coal has risen $1.43/ton to $8.50/ton from 1971 to 1973,
the extra cost of 2  cents per ton representing the impact of Federal
standards over State standards should be easily passed along.
     Since all States  require particulate  control, the impact of
standards of performance on equipment suppliers will  amount to a
need to  upgrade equipment rather  than to  increase  the  number of
units.
                                37

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                                                    TABLE 3

                    CONTROL  COSTS  FOR  COAL CLEANING  - WET SCRUBBING  EQUIPMENT  FOR THERMAL  DRIERS
oo
00
      Plant  Size,  Run  of Mine
        3,000,000  Tons/Year
                             5,000,000 Tons/Year
      Drier Feed*
           401  Tons/Hour
                                                                                    668 Tons/Hour
      Drier Investment
             $883,000
                                                                                     $1,199,000
     Emission Standard
    A State
  Regulation
'(0.07 gr/dscf)
Proposed U.S.
  Standard
(0.03 gr/dscf)
   A State        Proposed  U.S.
 Regulation        Standard
(0.07  gr/dscf)   (0.03 gr/dscf)
Control Investment**
Investment Increase
Required
Annual Cost
$256,000
$88,200
$284,000
2.5%
$118,200
$409,000
$142,600
$454,000
2.8%
$192,300
     Cost Per Ton of Cleaned
     Coal
     *Based on 3480 hours/year and 46.5% feed to  driers.
     **Fabric filters for fugitive dust would add about $20,000 to each system and $5000 to annual  costs.

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REFERENCES
1.  "Background Information for Establishment of National  Standards
    of Performance for New Sources - Coal  Cleaning  Industry,"
    Contract No.  CPA 70-142, Task Order No.  7, Environmental
    Engineering,  Inc., and Herrick Associates, July 15, 1971.
2.  Leonard, Joseph W. and Mitchell, David R., Coal Preparation. AIME,
    New York, New York, 1968.
3.  EPA Coal Preparation Industry Survey, conducted May-August, 1972,
    Survey Form OMB No. 158-S 72008.
4.  "Analysis of Final State Implementation Plans - Rules and
    Regulations," Contract No. 68-02-0248, MITRE Corporation,
    July  1972.
5.  Private  Communication, Joseph Notary, Heyl  and Patterson, Inc.,
    to Charles B. Sedman,  Industrial Studies  Branch, OAQPS, EPA,
    January  17,  1973.
6.  Letter,  H. Soderberg,  American  Air  Filter,  Inc., to C. Sedman,
    Industrial Studies  Branch,  Office  of  Air Programs, EPA,
    November 2,  1972.
 7.  Letter,  R. Dubrovsky,  Research  Cottrell,  Inc., to  J.  McCarthy,
    Performance  Standards  Branch, Office  of Air Programs, August  10,
    1972.
                               39

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                                     TECHNICAL REPORT DATA
                              /flease read Instructions on the reverse before completing)
    EPA-450/2-74-021a
                                                              3. RECIPIENT'S ACCESSIO(*NO.
     PLE
          ) SUBTITLE
    BACKGROUND INFORMATION FOR STANDARDS OF PERFORMANCE:
    Coal  Preparation  Plants, Volume  1,  PROPOSED STANDARDS
              5 REPORT DATF
                  October  1974
              6. PERFORMING ORGANIZATION CODE
                                                              8. PERFORMING ORGANIZATION REPORT NO
                           ME AND ADDRESS
   U.S.  Environmental  Protection Agency
   Office  of Air Quality Planning and  Standards
   Research Triangle Park, N.C.  27711
                                                              10. PROGRAM ELEMENT NO.
              11. CONTRACT/GRANT NO.
  2. SPONSORING AGENCY NAME AND ADDRESS
                                                              13. TYPE OF REPORT AND PERIOD COVERED
                                                              14. SPONSORING AGENCY CODE
            rARY NOTES
   This volume is the first  of a series on  standards of  performance for  coal
   preparation plants.  This volume presents  the proposed  standards and  the
   rationale  for the degree  of control selected.  The volume also discusses
   the analytical methods  for sampling emissions and the environmental and
   economic impact of the  standards.
                                 KEY WORDS AND DOCUMENT ANALYSIS
                   DESCRIPTORS
                                               b.lDENTIFIERS/OPEN ENDED TERMS  C.  COSATI Field/Group
   Air pollution
   Pollution control
   Performance standards
   Coal  Preparation  Plants
 Air pollution control
   DISTRIBUTION STATEMENT
         Unlimited
19. SECURITY CLASS (This Report)
 Unclassified
                                                                           21. NO, OF
                                               20. SECURITY CLASS (Thispage/
                                                Unclassified
                            22. PRICE
EPA Form 2220-1 (9-73)
                                              40
 U.S. GOVERNMENT PRINTING OFFICE) 1974 - 640-877/620  - Region 4

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