PA
United States
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park NC 27711
EPA-450/3-79-017b
April 1982
Air
Phosphate Rock
Plants -
Background
Information for
Promulgated Standards
EIS
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EPA-450/3-79-017b
Phosphate Rock Plants -
Background Information
for Promulgated Standards
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
April 1982
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This report has been reviewed by the Emission Standards and Engineering
Division of the Office of Air Quality Planning and Standards, EPA, and
approved for publication. Mention of trade names or commercial products
is not intended to constitute endorsement or recommendation for use. Copies
of this report are available through the Library Services Office (MD-35) ,
U.S. Environmental Protection Agency, Research Triangle Park, N.C. 27711;
or, for a fee, from the National Technical Information Services, 5285 Port
Royal Road, Springfield, Virginia 22161.
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A
A^>>C U
ENVIRONMENTAL PROTECTION AGENCY
Background Information
and Final
Environmental Impact Statement
for Phosphate Rock Plants
Prepared by:
Don R. Goodwin I (Date)
Director, Emission Standards and Engineering Division
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
1. The promulgated standards of performance will limit emissions of
particulate and visible emissions from new, modified, and recon-
structed phosphate rock plants. Section 111 of the Clean Air Act
(42 U.S.C. 7411), as amended, directs the Administrator to establish
standards of performance for any category of new stationary source
of air pollution that ". . . causes or contributes significantly to
air pollution which may reasonably be anticipated to endanger
public health or welfare." The promulgated standards are expected
to primarily affect the states of Florida, North Carolina, Tennessee,
Idaho, Wyoming, Utah and Montana.
2. Copies of this document have been sent to the following Federal
Departments: Labor, Health and Human Services, Defense,
Transportation, Agriculture, Commerce, Interior, and Energy; the
National Science Foundation; the Council on Environmental Quality;
members of the State and Territorial Air Pollution Program
Administrators; the Association of Local Air Pollution Control
Officials; EPA Regional Administrators; and other interested parties.
3. For additional information contact:
John Crenshaw
Standards Development Branch (MD-13)
U. S. Environmental Protection Agency
Research Triangle Park, NC 27711
Telephone: (919) 541-5421
4. Copies of this document may be obtained from:
U. S. EPA Library (MD-35)
Research Triangle Park, NC 27711
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
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TABLE OF CONTENTS
Section . Page
1. SUMMARY 1-1
1.1 Summary of Changes Since Proposal 1-1
1.2 Summary of the Impacts of the Promulgated
Action 1-3
1.3 References • 1-6
2. SUMMARY OF PUBLIC COMMENTS 2-1
2.1 Applicability and Need for New Source
Performance Standards 2-1
2.2 Definitions 2-8
2.3 Cost/Benefit Impact 2-9
2.4 Technical Feasibility 2-15
2.5 Testing and Monitoring 2-28
2.6 References 2-34
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1. SUMMARY
On September 21, 1979, the U.S. Environmental Protection Agency (EPA)
proposed new source performance standards (NSPS) for phosphate rock
plants under the authority of Section 111 of the Clean Air Act. The
proposed standards were published in the Federal Register (44 FR 54970)
with a request for public comment. A total of 16 commenters representing
industry, trade associations, private environmental organizations, Federal
agencies, and State air pollution control agencies responded to this
request. Their comments and EPA's responses are summarized in this
document. The summary of comments and responses serves as the basis for
the revisions that have been made to the proposed standards.
1.1 SUMMARY OF CHANGES SINCE PROPOSAL
In response to the public comments, several changes have been made
in the original proposed standards. The most significant change has been
a revision in the allowed particulate emission and opacity limits for
phosphate rock dryers and calciners. The proposed standards would have
limited particulate emissions from all dryers and calciners to 0.02 and
0.055 kg/Mg (0.04 and 0.11 Ib/ton), respectively. Several industrial
commenters indicated that the proposed emission limits did not reflect
the level of control achievable with the best demonstrated control systems
on dryers and calciners operating under the most adverse control conditions.
In support of this argument, the commenters provided test data representing
controlled emissions from units operating at worst-case conditions.
Based upon the evaluation of these new test data, the particulate emission
limits for all dryers and calciners calcining unbeneficiated rock have
been revised to 0.03 and 0.12 kg/Mg (0.06 and 0.23 Ib/ton), respectively.
The emission limit of 0.055 kg/Mg (0.11 Ib/ton) will still apply to
calciners that are calcining beneficiated rock.
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Several commenters also questioned the zero-percent opacity limits
for dryers and calciners. They felt that the zero-percent limit was
unreasonable since all the observations used to support the standard had
steam plume interference, and the observations from an ESP-controlled
dryer had readings as high as 7.7 percent. Since the particulate emission
limits for dryers and calciners have been revised upward and since the
ESP-controlled facility had particulate emissions lower than any of the
emission limits with corresponding opacity up to 7.7 percent, the opacity
limit for dryers and calciners was revised to 10-percent opacity.
Another important change was made to exempt ground rock storage and
handling systems from the continuous monitoring requirements. The
proposed standards would have required continuous monitors on ground rock
storage and handling system emission control equipment. The primary
purpose of continuous monitoring equipment is to ensure continuous and
proper operation of required particulate collection equipment. The
ground rock storage and handling systems are subject only to an opacity
limit under the standards, and there are no specific control equipment
requirements. Therefore, compliance can be demonstrated routinely with
Method 9, making continuous opacity monitors economically unreasonable
and unnecessary.
A commenter also suggested that small laboratory or pilot-scale
facilities used exclusively for testing and research should be exempted
from the standards. In response to this comment, the standards have been
revised to exempt plants with maximum hourly production capacities equal
to or less than 3.6 Mg/hr (4 tons/hr). This capacity range is less than
that of any existing production facility.
In addition to these changes, several wording and definition changes
have been made to clarify the applicability of the promulgated standards.,
The definition of ground rock storage and handling systems has been
changed to more clearly define the exclusion of ground rock transfer
sources at fertilizer plants from the standards. The definition of
grinders has been modified to more clearly define the exclusions of
crushers used during mining operations. Additional explanation has been
included to explain that the standards would not be applicable to
elemental phosphorus producing facilities.
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1.2 SUMMARY OF THE IMPACTS OF THE PROMULGATED ACTION
1-2.1 Alternatives to the Promulgated Action
The alternative control techniques are discussed in Chapter 4 of
"Phosphate Rock Plants - Background Information for Proposed Standards."
(This document is also referred to as the background information docu-
ment [BID], Volume I.) These alternative control techniques are based
upon the best demonstrated technology, considering costs and environmental
impacts, for phosphate rock plants. The alternatives-of taking no action
and of postponing the promulgated action-are analyzed in Chapter 6 of the
BID, Volume I. These alternatives remain unchanged.
1-2.2 Environmental and Energy Impacts of the Promulgated Action
The environmental impacts of the original proposed standards are
discussed in Chapter 6 of BID, Volume I. The environmental impacts
presented at proposal were based on the proposed emission limits and 1971
growth-projection data from the U.S. Bureau of Mines. Changes made in
the proposed standards that would modify the environmental impacts are
the revisions in the particulate emission limits for dryers and unbene-
ficiated rock calciners. There has also been a change in the growth-
projection data. Based on more recent (1979) growth-projection data from
the U.S. Bureau of Mines, phosphate rock production in 1985 will be
approximately 63.0 million Mg (69.4 million tons). Assuming a 20-year
life expectancy of existing equipment, the portion of the 1985 production
that will be subject to the standard will be approximately 23.3 million
Mg (25.7 million tons). Under typical existing State implementation plan
(SIP) regulations, allowed particulate emissions from new, reconstructed,
or modified dryers, grinders, and calciners would equal 15,400 Mg (17,000
tons) in 1985. However, actual emissions at the existing level of control
are less than the allowed emissions because the industry has employed
more effective control techniques than required by existing SIP
regulations, such as the use of baghouses on grinders.
Assuming that all phosphate rock sources that would be subject to
the new source performance standards are operating at the most adverse
control conditions, actual particulate emissions in 1985 from phosphate
rock grinders, dryers, and calciners using typical existing control
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equipment would equal 4,600 Mg (5,000 tons). Under the promulgated
emission limits the allowed particulate emissions in 1985 from the same
grinders, dryers, and calciners would equal 1,300 Mg (1,400 tons). These
figures indicate that the promulgated standards would cause a reduction
in 1985 of 14,100 Mg (15,600 tons) in the particulate emissions allowed
by typical SIP regulations. However, the promulgated standard would
actually cause a reduction of 3,300 Mg (3,600 tons) in the 1985 particu-
late emissions occurring at the control level typical of current industry
practices (i.e., low- or medium-energy scrubber on dryers or calciners
and baghouses on grinders).
The revisions in the emission limits as originally proposed for
dryers and calciners did not involve a change in the best demonstrated
continuous control systems. The best demonstrated control systems remain
the baghouse and the high-energy venturi scrubber at the originally pro-
posed design parameters. The promulgated emission limits are instead
based on a reevaluation of the emission levels achievable with best
demonstrated control equipment on worst-case uncontrolled emissions.
Therefore, energy impact of the best demonstrated control systems, as
presented in Chapters 1 and 6 of the BID, Volume I, remains unchanged.
1.2.3 Economic Impact of the Promulgated Actions
The economic impact of the promulgated standards, like the energy
impact, depends on the best demonstrated control systems used as the
basis for the standards. Since there has been no change in the best
demonstrated control systems, the economic impact, as discussed in
Chapters 1 and 7 of the BID, Volume I, remains unchanged.
1.2.4 Other Considerations
1.2.4.1 Adverse Impacts. Based on test data supplied by the phosphate
rock industry, worst-case uncontrolled particulate emissions from dryers
and calciners are higher than those used to set the original proposed
emission limits. The required control techniques and resulting control
performance levels (approximately 99.3 percent) are the same as those
that formed the basis of the original proposal. Because the uncontrolled
particulate emission rates are higher than originally evaluated, the same
reduction level will result in a slightly higher rate of collected emissions.
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The collected emissions present a solid-waste disposal problem. However,
as explained in Chapters 1 and 6 of the BID, Volume I, the solid waste
from participate control equipment is insignificant in comparison to the
solid waste produced by mining and beneficiation. Therefore, the
incremental increase in solid waste production at the promulgated
standard level over the SIP level is considered reasonable.
Other adverse impacts are discussed in Chapters 1 and 6 of the BID,
Volume I and have not been changed since the standards were" proposed.
1.2.4.2 Relationship Between Local Short-Term Uses of Man's
Environment and the Maintenance and Enhancement of Long-Term Productivity.
This impact is discussed in Chapters 6 and 8 of the BID, Volume I and
remains unchanged since proposal.
1.2.4.3 Irreversible and Irretrievable Commitments of Resources.
This impact is discussed in Chapter 6 of the BID, Volume I and remains
unchanged since proposal.
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1.3 REFERENCES FOR CHAPTER 1
1. Stowasser, W. F. Phosphate Mineral Commodity Profiles. U.S. Department
of the Interior, Bureau of Mines. January 1979.
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2. SUMMARY OF PUBLIC COMMENTS
Comments received on the proposed phosphate rock NSPS and on the
BID, Volume I have been divided into the following categories:
1. Applicability and Need for New Source Performance Standards
2. Definitions
3. Cost/Benefit Impact
4. Technical Feasibility
5. Testing and Monitoring
The list of commenters and their affiliations is given in Table 2-1.
2.1 APPLICABILITY AND NEED FOR NEW SOURCE PERFORMANCE STANDARDS
2.1.1 Reasons for New Source Performance Standards
The need for NSPS for phosphate rock facilities was questioned
because phosphate rock facilities are not currently violating ambient air
quality standards. The purpose of NSPS is not limited to ensuring com-
pliance with ambient air quality standards. They are, instead, intended
to ensure that best demonstrated systems of continuous emission reduction
are applied to new, modified, or reconstructed stationary sources that
have been determined to "cause or contribute significantly to air pollution
which may reasonably be anticipated to endanger public health or welfare."
NSPS will minimize both the deterioration of existing air quality and the
costly retrofitting of control equipment that future air quality problems
could necessitate. They will ensure the uniform nationwide application
of emission controls. NSPS will also prevent unfair competition for
industrial growth that would result from nonuniform environmental regula-
tions. As existing equipment is replaced, new source performance
standards will also result in improved air quality.
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2.1.2 Environmental Impacts
Several commenters questioned the reduction in particulate emissions,
as explained in Chapter 6 of the BID, Volume 1, that would be achieved by
the standards. Three commenters indicated that the particulate emission
reduction claimed in the proposed standards were overrated because they
were based on outdated and overestimated production forecasts, which
weakens the rationale for the standard. All three commenters argued that
EPA should use the most recent production estimates from the Bureau of
Mines. In response to the comments, EPA obtained the most recent Bureau
of Mines production forecast data. Although these data significantly
reduce the originally estimated 1985 emissions reduction due to the
standards by 25 percent, the new estimates of environmental benefits
still justify the standards.
Bureau of Mines data from 1979 indicate that U.S. phosphate rock
production will increase from 47 million megagrams in 1977 to 64 million
megagrams in 1986, but will then decrease to 56.0 million megagrams in
1995. An increase in production of 11.0 million megagrams is expected
between 1980 and 1986. In addition, some existing equipment must be
replaced because of normal wear. The new equipment would be subject to
the standards. Assuming a 20-year life expectancy for existing equip-
ment, the production from replacement equipment subject to the standards
will be 13.3 million megagrams in 1985. Of the total phosphate rock
production, approximately 23.3 million megagrams will be subject to the
standards by 1985. As explained in Chapter 1, Section 1.2.2 of this
document, the promulgated standards will reduce the SIP-allowed
particulate emission level by 14,100 Mg (15,600 tons) and the actual
existing emission level by 3,300 Mg (3,600 tons).
Finally, the primary purpose of an environmental impact analysis is
to compare the impacts of alternative regulatory options. The Adminis-
trator has determined the need for NSPS for phosphate rock plants because
they cause or contribute significantly to air pollution which may reasonably
be anticipated to endanger public health or welfare. These significant
air pollution impacts include not only total national impacts but also
significant local impacts. The promulgation standards will significantly
improve and protect local air quality and do justify the standards.
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Three commenters suggested that the environmental benefits of the
standards were exaggerated because actual emissions from grinders are
much less than those allowed by the SIP emission limits. Another
commenter felt that the standards should be modified since emission
reductions were concentrated in the grinding operation. According to
this commenter, possible emission reductions from the other controlled
sources would be insignificant. EPA agrees that actual emissions from
existing grinders are less than those allowed by SIP regulations. However,
because of this fact, the emission reductions resulting from the
standards are actually concentrated in drying and calcining operations.
Typical industry practice is to control particulate emissions from
grinders with baghouses and to control emissions from dryers and calciners
with low- to medium-energy venturi scrubbers. Since baghouses and
high-energy venturi scrubbers are the designated best continuous control
systems, there is much greater emission reduction potential from the
control of dryers and calciners than from the control of grinders. The
emissions reduction potential in 1985 is presented in terms of allowed
and actual emissions. The actual emission reduction figure does not
claim any reductions from the control of grinders. Because baghouses are
the typical control technique for grinders and are also designated as the
best demonstrated control system, the proposed standards support current
industry practice and provide uniformity in control levels with minimal
incremental economic impact to the industry above current practice.
Two commenters felt that the environmental benefits were exaggerated
because actual emission rates are lower than those allowed by the existing
SIP level of control. They also stated that the SIP emission rates used
in the BID, Volume 1 were based on obsolete SIP regulations for existing
plants rather than on current SIP regulations for new plants.
As noted previously, the environmental benefits presented in Chapter 1,
Section 1.2.2 include both actual emission reductions achievable from the
existing level of control and reductions in the emissions allowed by the
SIP level of control. The SIP emission limits used in Volume 1 of the
BID are not all obsolete SIP regulations for existing plants. Of the
seven states controlling phosphate rock plants, only Idaho has changed
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its applicable emission limits. This change occurred after Volume 1 of
the BID had been completed. As explained in Volume 1, Idaho accounted
for just 12.1 percent of the 1977 production capability; thus changes in
the typical SIP limits resulting from the revision in the Idaho limits
would be insignificant.
Another commenter stated that the air quality improvements resulting
from the original proposed standards were exaggerated since new plants
would be subject to limitations on air quality impacts imposed by prevention-
of-significant-deterioration (PSD) regulations. It is true that many new
or modified facilities subject to the NSPS would also be subject to PSD
limitations. PSD is a case-by-case review subject to a number of site-
specific variables, including stack heights, stack gas velocities, stack
gas temperatures, downwash and meteorological conditions, as well as
emission rates. With these variations the ambient air quality impact can
also vary. Because of the potential variability in the site-specific
parameters, an analysis of incremental PSD impacts above the NSPS level
is excessively complex and unnecessary. NSPS support PSD by providing
the baseline for "best available control technology" determinations.
Because NSPS is therefore the minimum control level that new plants will
have to meet, the air quality impacts presented are appropriate for NSPS
rulemaking. The analysis of air quality impacts compares the NSPS emission
rate to both the typical SIP allowed emission rate and the actual existing
emission rate resulting from current industry practice. While the commenter
is correct in pointing out that PSD requirements may go beyond NSPS, an
assessment of PSD impacts is not within the scope of an analysis to
support NSPS.
2.1.3 Opacity Standard
The need for an opacity standard was questioned by two commenters.
The two commenters felt that it is unrealistic to have both an opacity
standard and a particulate emission limit for the same emission source.
The primary purpose of an opacity standard is to provide a simple and
inexpensive means for enforcing the requirement of continuous and proper
operation of emission control equipment. It is true that both the opacity
limits and the particulate mass emission limits apply to the same pollutant.
However, compliance with the particulate emission limits can only be
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demonstrated with Reference Method 5 performance tests. Method 5 tests
are time consuming and require long-term advance scheduling and sophisti-
cated test equipment. Without additional enforcement procedures, emission
control equipment could be improperly operated between or after Method 5
tests. Compliance with opacity standards are determined with Method 9.
Method 9 consists of visible observations conducted by a qualified observer
following a specified procedure. Method 9 is quicker, simpler, and less
expensive than Method 5. It can be performed routinely to document
compliance with the intent of the standards. Therefore, opacity limits
provide an enforcement tool for routine demonstration of compliance with
the standards. It should be noted that the United States Court of Appeals
for the District of Columbia Circuit has specifically upheld the use of
opacity standards to measure and aid in controlling mass emissions under
NSPS. Portland Cement Association v. Train, 513 F.2d 506, 508 (1975).
2.1.4 Testing Facilities
The need to exclude small sources such as pilot plants or testing
facilities was pointed out by one commenter. EPA agrees with the comment
and has added an exemption for facilities processing less than 3.6 Mg/hr
(4 ton/hr). The decision to exempt small facilities from the standards
is based on the cost-effectiveness of control. That is, the costs per
megagram (ton) of emissions reduction. The cost-effectiveness evaluated
is reduction in uncontrolled emissions, not reductions from the SIP
level. Although the commenter requested a .9 Mg/hr (1.0 ton/hr cutoff),
the plant capacity level chosen of 3.6 Mg/hr (4.0 tons/hr) is based on
the fact that no affected source (i.e., dryer, calciner, grinder) at a
production facility has a maximum capacity less than 4.5 Mg/hr (5.0 tons/hr).
An economic analysis of a dryer and grinder with capacities of 3.6 Mg/hr
(4 ton/hr) has been performed to determine the cost-effectiveness of the
standards at this cutoff level.
Since research facilities would not operate sources continuously or
as frequently as production facilities an annual operating figure of
500 hours was assumed. Based on industry comments it was assumed that
for compliance purposes a high energy venturi scrubber would be chosen
for the dryer and a baghouse for the grinder. The cost of the standards
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would be about $1,075 and $2,000 per megagram ($975 and $1,800 per ton)
of particulate removed for the dryer and the grinder, respectively.
Comparative cost for a typical 145 Mg/hr (150 ton/hr) dryer and a typical
14 Mg/hr (15 ton/yr) grinder indicate a cost-effectiveness of $79/Mg
($72/ton) and $260/Mg ($236/ton), respectively.
Although the cost of control at the 3.6 Mg/hr (4.0 ton/hr) level may
not be excessive, most research and development facilities will actually
use smaller equipment. Therefore, the cost of control will'increase even
higher. Because no production facilities exist with a capacity less than
4.5 Mg/hr (5.0 ton/hr) and control cost become excessive below 3.6 Mg/hr
(4.0 ton/hr), the lower capacity cutoff is justified.
2.1.5 Other Pollutants
One State air pollution control agency suggested that the standards
should contain emission limits for carbon monoxide, sulfur dioxide,
fluoride, nitrogen oxides, and hydrocarbons from dryers and calciners.
EPA has analyzed the need for regulating emissions of these pollutants
from dryers and calciners and has concluded that there is no justification
for their regulation.
In addition to particulates, both phosphate rock dryers and calciners
emit sulfur dioxide (S02), carbon monoxide (CO), nitrogen oxides (NO ),
J\
hydrocarbons and fluorides. Typical phosphate rock has a fluoride content
of approximately 4 to 5 percent by weight, expressed as fluorine. There
is a potential to volatilize these fluorides at high temperatures.
However, in experiments by the Tennessee Valley Authority (TVA), phosphate
rock samples were heated to 500°C, 600°C, 700°C, 800°C, and 950°C for
3
30 minutes each. Chemical analysis showed fluorine volatilization only
in the sample heated to 950°C. Seven percent of the fluorine in that
sample was volatilized. Typical final temperatures for dryers and calciners
are 95°C and 870°C, respectively. These data indicate that typical
process temperatures in both dryers and calciners are insufficient to
cause gaseous fluoride emissions. Since any solid fluorides would be
controlled by the particulate control equipment, there is no need for a
fluoride standard.
S02, CO, NO , and hydrocarbon emissions from dryers and calciners
/\
are primarily due to fuel combustion. Fuel combustion in phosphate rock
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dryers and calciners does not differ appreciably from fuel combustion in
lime kilns. Typical lime kilns operate at approximately 3.25 x 106 Btu
per ton of rock feed and have exhaust gas temperatures in the range of
593° to 760°C. Process energy varies from 251,000 to 481,000 Btu per ton
of rock feed for phosphate rock dryers and from 375,000 to 525,000 Btu/ton
for calciners. Therefore, there is a significantly larger amount of fuel
combusted per ton of rock in lime kilns with correspondingly higher
emissions of S02, NO , CO and hydrocarbons per ton of rock feed.
/\
Emission tests of NO , S02, and CO emissions have been performed on
4
lime kilns firing coal, natural gas, and No. 6 fuel oil. These tests
indicated that flue gas NO concentrations are normally in the range of
/\
200 ppm or approximately 0.45 pounds per million Btu of heat input. At
adverse meteorological conditions, with aerodynamic downwash, dispersion
modeling indicates a maximum concentration of about 10 pg/m3 for a typical
lime kiln (1,000 tons/day of feedrock). Because of less fuel combustion
per unit of rock, this level would be even lower for typical phosphate
rock dryers and calciners. Also, NO control combustion modifications
/\
have not been demonstrated for dryers and calciners. Therefore, NO
emissions were not selected for control.
Both CO and hydrocarbons result from incomplete fuel combustion.
The emission tests on lime kilns indicate that CO emissions are normally
in the range of 100 ppm. Under adverse meteorological conditions, with
aerodynamic downwash, dispersion modeling indicates that CO emissions
from a typical lime kiln would cause an insignificant maximum concentration
of about 30 ug/m3 (8-hour average). CO emissions from typical phosphate
rock dryers and calciners would be even lower because of lower fuel
consumption. Since hydrocarbons would result from the same incomplete
combustion that produces the CO, their emission levels would vary with
the CO. The most effective control technique for both CO and hydrocarbons
would be incineration of the flue gas. The use of incineration would
cause a significant fuel use increase with little environmental benefit.
Therefore, neither CO or hydrocarbon emissions from phosphate rock dryers
and calciners were selected for control.
The emission tests of the lime kilns indicate that the calcium oxide
in the feed rock causes an S02 reduction of about 88 percent with dry
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particulate control devices and about 94 percent with wet scrubbers. The
S02 reduction is caused by a chemical reaction with CaO that forms solid
CaS04. Because phosphate rock typically contains about 55-percent calcium
oxide, similar S02 reductions can be expected. Since potential S02
emissions from phosphate rock dryers and calciners would likely be
significantly reduced by up to 80-90 percent, no additional control
requirements were selected.
2.2 DEFINITIONS
2.2.1 Phosphate Rock Plants
Several commenters requested wording and definition changes in the
proposed standards to clarify the meaning of certain terms. It was
requested that the definition of phosphate rock plants be modified to
clearly define the exclusion of elemental phosphorus plants and fertilizer
production facilities. The promulgated standards for phosphate rock
plants are not intended to include mining, beneficiation, thermal defluorina-
tion, elemental phosphorus production, or nodulizing. Section 60.400(a)
of the promulgated standards specifies that the standards apply only to
facilities at phosphate rock plants, including grinders, calciners,
dryers, and ground rock storage and handling systems. The definition of
phosphate rock plant implicitly excludes fertilizer plants.
The proposed standards are not intended to apply to elemental
phosphorus plants, because no significant growth is expected in these
facilities. However, the appropriate method of excluding these
facilities is to modify applicability. Section 60.400(a) has been modified
to read: "The provisions of this subpart are applicable to the following
affected facilities used in phosphate rock plants: dryers, calciners,
grinders, and ground-rock-handling and storage facilities, except those
facilities producing or preparing phosphate rock solely for consumption
in elemental phosphorus furnaces."
2.2.2 Grinders and Ground Rock Handling
A request was also made to more clearly define the exclusion of
phosphate rock handling and crushing during mining operations. The
promulgated standards are not intended to cover phosphate rock handling
or crushing during mining operations. The definition of grinder has been
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changed to "a unit used to pulverize dry phosphate rock to the final
product size used in the manufacture of phosphate fertilizer and does not
include crushing devices used during mining operations." Section 60.402(a)(5)
has been modified to read: "From any ground phosphate rock handling and
storage system any gases which exhibit greater than zero percent opacity."
This modification prevents the incorrect inclusion of unground phosphate
rock handling and storage at mining or transfer sites.
2.2.3 Feed Rate
One commenter questioned whether the allowable emission limits
(weight per megagram (ton) of phosphate rock) were based on wet or dry
rock. As specified in the standards, the emission limits are based on
the weight of the phosphate rock feed. The term "feed" means all weight
entering into the process, including moisture and any recycled materials.
2.3 COST/BENEFIT IMPACT
2.3.1 Sliding Scale Standard
One commenter recommended that production rate size differences be
considered in setting the standards, since the cost effectiveness for
controlling larger plants is often greater than for controlling smaller
plants. The commenter pointed out that under existing SIP regulations,
large plants were subject to a more stringent level of control than
smaller plants.
EPA agrees that, because of the sliding scale in State process
weight tables, larger sources are subject to more stringent emission
limits than the typical plants used in the Volume 1 analysis. However,
the SIP regulations are all miscellaneous process standards and do not
apply solely to phosphate rock plants. The typical plants used in the
analysis were selected to compare the environmental, energy, and economic
impacts of alternative regulatory options. The actual emission limits in
the standard are based on the application of the best demonstrated control
technologies to the emission sources. Available data do not indicate
that particulate concentration and particle size distributions vary with
production rate; therefore, there is no significant variation in the
performance of the best demonstrated control techniques on units of
different sizes. Thus the promulgated emission limits resulting from the
application of the best control techniques do not vary with production
rate.
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2.3.2 Additional Power Requirements
One commenter stated that the increases in particulate and sulfur
dioxide (S02) emissions from power plants caused by the additional energy
production required by the more stringent control techniques of the
promulgated standards were not considered in the standard analysis for
Florida phosphate rock plants.
EPA has analyzed these impacts and concluded that environmental
benefits resulting from the standards outweigh any adverse environmental
effects. If high-energy venturi scrubbers are used to comply with the
NSPS, the process energy required would increase by about 4,041 Btu per
ton of rock processed above the existing SIP level of control. In 1985,
the quantity of particulate emissions attributable to the additional NSPS
energy demands produced by Florida power plants under existing power
plant regulations will be only about 1.1 percent of the total emission
reduction potential of the NSPS on Florida phosphate rock dryers. The
quantity of S02 emissions produced from the power plants supplying the
additional energy requirements cannot be compared directly to the
particulate reduction potential of the standard, because the two pollutants
produce different environmental effects. However, the increase in S02
emissions from energy production would amount to about 18 percent of the
decrease in phosphate rock plant particulate emissions if a 2.0-percent
sulfur coal is utilized. It. should also be noted that any new power
plants would be subject to NSPS and the increases in S02 and particulate
emissions from the additional energy production would be even less.
Another commenter indicated that the power grid for some Western
plants would not be able to handle the additional energy needs of the
proposed standard. The commenter did not supply any specific energy
production capability data for the power grids in question. Although the
commenter did use the city of Portland, Oregon's energy problems as an
example, there are no existing or projected phosphate rock plants in that
location. It is expected that the emission limits on Western plants will
result in an 8-percent increase in total process unit energy over the SIP
level if high-energy venturi scrubbers are used, approximately no change
in energy requirements if electrostatic precipitators (ESP's) are used
and about a 5-percent increase when baghouses are used. For a typical
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new western plant with three 54 Mg/hr (60 ton/hr) calciners, one 83 Mg/hr
(91 ton/hr) grinder, and two 13 Mg/hr (14 ton/hr) grinders, the estimated
annual power usage would be 44.3 million kWh. With an 8 percent increase
in total process energy resulting from the standards, the total plant
energy requirement would increase to 47.8 million kWh. This incremental
increase in power requirements should not adversely affect the ability of
the local power grid to supply additional energy needs for new or modified
sources. If the local power grid is able to supply the energy requirements
for processing equipment and SIP level control equipment for a new or
modified source, it should be able to meet the minor incremental increase
caused by the promulgated control levels.
2.3.3 Control Cost
Since Western rock usually contains a higher precentage of fines
than Eastern rock, one commenter indicated that particulate loadings and
corresponding control costs would be higher for Western plants. Western
unbeneficiated rock does contain higher percentages of fines than Eastern
rock; however, the source tests used to set the emission limits for
calciners processing unbeneficiated rock were conducted with unbene-
ficiated Western rock. The economic analysis of control costs in Chapter 7
of Volume I of the BID conclude that control costs, although higher for
Western plants, are not excessive.
Three commenters stated that baghouses on dryers and calciners would
require an auxiliary heat source that has not been costed. The need for
an auxiliary heat source for baghouses on dryers and calciners was not
addressed in the proposed standards because it should be unnecessary.
Baghouses are presently operated on similar applications, including
asphalt aggregate dryers, without an auxiliary heat source. The temper-
ature differential necessary to prevent condensation can be maintained by
properly insulating the baghouse and all ductwork to prevent heat loss.
During start-up, the baghouse can be heated to operating temperature by
operating the burners at low fire with no rock in the dryer or calciner.
The commenters further stated that the annualized costs for baghouses
had been underestimated in comparison to venturi scrubber costs because
the costs of the baghouse were depreciated over a fifteen year period,
while venturi scrubber costs depreciated over a ten year period. They
also suggested that the baghouse cloth area requirements that were costed
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should have been based on 120 to 125 percent of the calculated cloth area
for the designated gas volume processed. They felt that the additional
capacity would assure proper operation during unexpected high gas volume
flow. However, the baghouse was depreciated over a longer period because
experience indicates that baghouses typically have a longer equipment
life than venturi scrubbers. The economic analysis was performed to
compare the costs of the alternative regulatory options. Therefore, the
costed cloth area of the baghouse was based on the same volume of gas
processed as was the venturi scrubber. For comparative purposes, it
would be inappropriate to cost the venturi scrubber for a particular gas
volume and then cost the baghouse at 120 to 125 percent of that same
flow.
The commenters also argued that baghouse costs for calciners had
been underestimated because the air flows that were costed for the model
facilities were too low. However, as pointed out in Volume I of the BID,
calciner air flows for typical 45.4 Mg/hr (50 ton/hr) units range from
850 to 1,700 standard mVmin (30,000 - 60,000 scfm). At a typical exhaust
temperature of 120°C, these figures would present an air flow range of
1,160 to 2,310 actual mVmin (40,800 to 81,600 acfm). The air volume
costed for the model calciner facility was 2,930 actual m3/min (103,460 acfm)
for a 54 Mg/hr (60 ton/hr) unit. Therefore, the air flow costed is
representative of the upper range of air flows and does not cause an
underestimation of control costs.
Another commenter pointed out that, unlike typical Western plants,
the model Western plants given in Volume I of the BID do not incorporate
a drying cycle between the beneficiation and calcining processes. This
omission causes the estimated control cost to be erroneously low. EPA
agrees that the addition of a dryer to a model Western rock processing
facility would increase annual control costs for typical Western plants.
However, existing SIP regulations already require control of dryer emissions.
The level of control required by SIP regulations for new dryers will
probably be achieved with scrubbers. Based on industrial comments, plant
owners would install venturi scrubbers to comply with the promulgated
NSPS. Scrubber installation costs are approximately the same even at
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different performance levels. Since SIP regulations already require
scrubbers, there would be no significant increase in installation costs
for the promulgated standards above the SIP level. There would, however,
be an increase in operating costs for a higher energy scrubber. For a
typical 160-ton/hr dryer, increased annualized costs above the SIP level
would be approximately $0.07 (1978 dollars) per ton of product. The
estimated cost of phosphate rock at model Western plants under the pro-
mulgated level of control (venturi scrubbers on calciners, baghouses on
grinders, and handling) would increase with the addition of a high-energy
venturi scrubber on a dryer from approximately $22.25/ton to $22.32/ton
(1978 dollars). This cost increase would not significantly affect the
cost-effectiveness of the standards.
A general comment was that the emission limits originally proposed
were based on typical rather than worst-case conditions and that the cost
estimates to meet these emission limits on a continuous basis were under-
estimated. Although the original emission limits were erroneously based
on typical conditions, the control equipment costs were not under estimated.
The promulgated standards are based on the application of best demonstrated
continuous emission reduction systems to the emission sources under
consideration. Applicable emission limits result from the application of
these controls to worst-case conditions. The available control options
for phosphate rock plants are baghouses and high-efficiency venturi
scrubbers. The costs of these control devices do not vary appreciably at
a particular performance level on a particular application. The typical
cases used in the original analysis did not reflect worst-case conditions.
Therefore, the particulate loading to the control devices are larger than
originally analyzed. As a result, the reduction in these uncontrolled
particulate emissions available with the best control systems (approximately
99.3 percent) results in higher controlled emission levels. The emission
limits for dryers and calciners have been revised upward accordingly.
However, the available control systems have not changed, and the costs
presented in the analysis for a control system on a particular emission
source have not changed.
The comment was also made that collected waste from baghouses and
ESP's would probably be slurried for disposal, thus causing higher waste
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disposal costs than those presented in the analysis. If collected waste
from baghouses and dry ESP's were slurried for disposal, there would be
an increase in solid waste, water pollution, and energy consumption.
However, the resulting solid waste and water pollution treatment require-
ments would still be insignificant when added to the total plant waste
from mining and beneficiation. As discussed in Volume 1 of the BID,
these insignificant increases would not affect the cost effectiveness of
the standards.
One commenter stated that the control costs presented in Volume 1 of
the BID were underestimated since they did not include the costs to
install, calibrate, maintain, ar\d operate a device for measuring phosphate
rock mass feed. The cost of rock feed rate (by weight) equipment was
addressed and considered in Volume 1 (page 7-58). Rock feed measuring
equipment is normally used at phosphate rock plants to measure production
process feed rates and is not solely a part of control requirements. The
installation cost of rock feed measuring equipment is about $14,000
(1978 dollars) for a facility processing 150 tons per hour of rock; the
annualized cost is about $3,500. This annualized cost is only about
1.1 percent of the annualized cost for a high-energy venturi scrubber on
a 150-ton/hour dryer. This additional cost does not significantly affect
the cost-effectiveness of the standards.
2.3.4 Exhaust Stacks
Two commenters noted that an opacity standard would penalize companies
that use larger than normal diameter stacks or that duct several sources
into a common stack for economic considerations. The commenters are
correct in stating that the opacity level would increase with increasing
stack diameter because the width of the plume would also increase.
However, the test data base indicates that facilities with normal diameter
stacks which are complying with the mass emission limits will comply with
the opacity standard. In addition, stack diameter would have no effect
on the particulate mass emission limits. There is site-specific relief
(40 CFR 60.11(e)) from the opacity standard for sources achieving the
mass emission limit. Facilities considering abnormal stack configurations
would have to weigh the benefits of ducting several sources to a single
stack or of using larger than normal stacks against the inconvenience of
applying for site-specific opacity relief.
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2.4 TECHNICAL FEASIBILITY
2.4.1 Particulate Emission Limits
Several commenters complained that the test data base presented in
Volume 1 was skimpy, old, and outdated. They further stated that the
data base for dryers and calciners did not account for the full range of
operating conditions in the industry. One commenter stated that the
particle size distribution used in determining control equipment efficiency
requirements did not represent worst case conditions and led to incorrect
conclusions concerning the ability of available control technology to
achieve the proposed limits. Finally, the commenters suggested that the
proposed emission limits be revised to 0.085 kg/Mg (0.17 Ib/ton) for
dryers and 0.20 kg/Mg (0.40 Ib/ton) for calciners.
In response to the commenters, EPA has revised the emission limit
for dryers and has added an emission limit for calciners processing
unbeneficiated rock. The proposed emission limit for calciners was
retained for units processing beneficiated rock. The revised emission
limits are based on new source test data, as supplied by industry and
local air pollution control agencies. However, the evaluation of the new
source test data does not justify revisions to 0.85 kg/Mg (0.17 Ib/ton)
and 0.20 kg/Mg (0.40 Ib/ton) for dryers and calciners, respectively, as
requested by the industrial commenters. The emission limits for both
dryers and unbeneficiated rock calciners are based on actual achieved
emission levels from industry-supplied source tests of well-controlled
facilities. Only the retained emission limit for beneficiated rock
calciners is based on an engineering evaluation of the achievable control
level. This engineering evaluation assumed more severe control conditions
(particle size distribution from unbeneficiated rock) than would be
expected to occur. The emission limit for beneficiated rock calciners is
a conservative determination of the consistently achievable emission level.
Therefore, these emission limits are more representative of the levels
achievable by well-controlled facilities than the limits suggested by
industry.
EPA agrees that the achievable emission limits should be set at a
level based on the application of the best demonstrated control systems
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to the worst-case emission control conditions that can reasonably be
expected to recur. The test data on whch the emission limits are based
must be representative of the full range of operating conditions in the
industry. Without consideration of the extremes in emission levels that
can be caused by process variables, emission limits cannot be set at
levels that can be achieved by all sources on a continuous basis under
all reasonable process conditions.
A review of the data base used in the original proposal indicates
that the control situations used did not always represent the worst-case
control levels. As a result, new test data representing worst-case
conditions were requested from the industry and State air programs. The
comment period was extended to allow industry time to submit more detailed
information concerning the range of operating conditions routinely
experienced by dryers and calciners. In response to the request for new
data, source tests from two facilities that dry coarse pebble rock in
residual oil-fired rotary units were submitted. Test data were also
received for a fluidized-bed, natural gas-fired calciner calcining a
blend of unbeneficiated and beneficiated Western rock. This is the only
existing facility calcining unbeneficiated Western rock.
An analysis of the new test data and additional information submitted
by industry indicated three major variables that have the potential to
affect particle size distributions and emission levels from phosphate
rock dryers and calciners. The three major variables are feed rock
characteristics, dryer or calciner unit type, and the fuel type.
The feed rock characteristics are the most important of the process
variables that affect emission levels. Industrial contacts have indicated
that the effects of feed rock variations greatly outweigh the effects of
other variables. Several feed rock characteristics can affect the emission
levels and particle size distribution of the exhaust gas streams. Surface
properties affect emission levels; rough or pitted surfaces can have
greater clay adhesion, resulting in higher emission levels and smaller
average particle size. During beneficiation, the least washed rock will
have more fines, higher emission levels, and smaller average particle
size. The residence time during which the rock is dried or calcined may
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also affect emission levels. Although increasing the residence time may
lower participate concentration per volume of exhaust gas, the total
weight of particulate emisison per weight of feed rock will increase.
Other feed rock characteristics can also cause fluctuations in the particu-
late emission levels. Coarse pebble rock from Florida is beneficiated
the least and has the longest residence time in the dryer of all Eastern
rock. Along with other properties including hardness and clay adhesion,
these properties cause coarse pebble rock to produce the most adverse, or
worst-case, control levels for Eastern operations. However, unbeneficiated
Western rock has a slightly smaller average particle size then Eastern
rock and represents the most adverse of all feed rock control situations.
Fuel combustion that provides the heat source for drying or calcining
has the potential to affect emission levels. The four fuel types used in
dryers and calciners are natural gas, distillate oil, residual oil, and
coal. The particulate emissions resulting from combustion of natural gas
and distillate oil are insignificant and will not affect processing unit
emission levels or control equipment performance. Residual oil and coal
contain noncombustibles that are emitted as ash during combustion. This
ash contributes to the particulate emission from dryers and calciners.
Calciners and dryers are direct fired; that is, the products of
combustion pass through the dryer or calciner and contact the process
feed rock. No data are currently available on what percentage of the
residual oil or coal ash would be collected on the process rock by impac-
tion or other processes. Therefore, there is no data available to determine
the impact of residual oil or coal firing on achievable emission limits.
Although there is no test data, an analysis of coal and residual oil
firing can be performed using those assumptions that would result in the
greatest environmental impact. A dryer and a calciner using 10-percent
ash coal at 29,073 kJ/kg (12,500 Btu/lb) and AP-42 pulverized coal-fired
boiler emission rates would have uncontrolled particulate emissions of
about 1.3 and 1.6 kilogram per megagram (2.5 and 3.2 Ib/ton) of feed
o
rock, respectively. Pulverized firing has the highest mass emission
level and lowest average particle size of all coal-firing types and
represents the most difficult control situation. The mass median diameter
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of the particle size distribution from pulverized coal used in the analysis
q
is 20 urn. The fractional efficiency curves for baghouses and 7.5 kPa
(30 inches of water) pressure drop venturi scrubbers used in Volume I of
the BID indicate an efficiency of about 99.7 percent with this particle
size distribution. Assuming that all of the coal fly ash passes through
the process unit and into the collection device, the contribution to the
controlled emissions at 99.7 percent control would be 0.0037 and
0.0048 kilogram per megagram (0.0075 and 0.0096 Ib/ton) of feed rock for
the dryer and calciner, respectively.
Using AP-42 emission factors and assuming a residual oil with
1.5 percent sulfur, the uncontrolled particulate emissions from residual
oil combustion would be about 0.025 kilogram per megagram (0.05 Ib/ton)
of feed rock for a dryer and 0.03 kilogram per megagram (0.06 Ib/ton) for
a calciner. The average particle size of particulates from residual oil
combustion is much smaller than that from coal combustion. The fractional
efficiency curves for the 7.5 kPa (30 inches of water) venturi scrubber
indicate a control efficiency of about 60 percent on residual oil-fired
particulate emissions. Assuming that all the particulate emissions from
the oil combustion pass to the control device, the contribution to con-
trolled emissions would be about 0.01 kilogram per megagram (0.02 Ib/ton)
of feed rock for dryers and calciners. Based on the analysis above,
residual oil would have a greater effect on controlled emissions and
represent the worst case fuel type.
This analysis assumes the most adverse effects from coal and oil
firing. In reality, some percentage of the coal and oil fly ash would
probably be collected on the process rock. As a result, any increase in
controlled emissions would probably be even less than that calculated.
The major unit types are rotary and fluidized-bed units. Fluidized-
bed units are designed to pass the heated combustion gases up through the
bed of phosphate rock. Therefore, there would be a greater potential for
entrainment of fines than with the rotary unit. However, test data
indicate no significant differences in the gas volumes or emission levels
from fluidized-bed or rotary units.
The worst-case test data received for one of the dryer facilities
contained seven tests with inlet loadings to the particulate control
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device. The existing control equipment was not equal in performance to
the designated best demonstrated control systems. Therefore, the con-
trolled emission levels could not be used directly to set an emission
limit. However, three of the tests were conducted with coarse pebble
rock and the inlet loading data were representative of the worst-case
control conditions. The inlet loadings to the control device were 3.49,
2.50, and 2.92 kg/Mg (6.98, 5.01, and 5.83 Ib/ton). The data base pro-
vided in BID, Volume I presented a particle size distribution from coarse
pebble rock at this facility. Application of this particle size distri-
bution to the fractional efficiency curves for the best demonstrated
control systems used in BID, Volume 1 (page 4-10) indicates a control
efficiency of 99.3-99.4 percent. If the highest inlet loading provided
is reduced by 99.3 percent, an emission level of 0.025 kg/Mg (0.049 Ib/ton)
is achievable.
The other dryer facility was controlled by a venturi scrubber operating
at 7.5 kPa (30 inches of water) pressure drop, which is equivalent to the
designated best demonstrated control systems. Four tests with controlled
emissions were provided. During two of the tests, the rock processed was
a blend of coarse pebble and pebble rock. The blends were 67 and 33 percent
coarse pebble, respectively, during the two tests. The results of the
tests indicated that the controlled emission levels were 0.028 and
0.029 kg/Mg (0.055 and 0.057 Ib/ton).
Western rock processing facilities usually calcine all rock. As a
result dryers at Western facilities are used only to reduce the moisture
content before transportation of the rock from mine site to the processing
plant. Because Western rock is relatively low in natural moisture content,
the moisture removed by a Western dryer is primarily due to beneficiation.
Unbeneficiated western rock would require no drying. Therefore, the
tested dryer facilities processing coarse pebble rock are representative
of dryers processing the worst-case rock type. Because these units are
fired with residual oil they are also representative of the worst-case
fuel types. Based on the tests from the two dryer facilities, the parti-
culate emission limit for phosphate rock dryers has been revised to
0.03 kg/Mg (0.06 Ib/ton). These tests indicate that this emission limit
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is achievable with either worst-case rock or blends of worst-case and
other rock types.
The worst-case calciner test data consists of 10 source tests with
controlled emissions. The emissions are controlled with a centrifield
scrubber operating at 5 - 7.5 kPa (20-30 inches of water) pressure drop.
There is no significant difference in the performance of a centrifield
scrubber and a venturi scrubber operating at the same pressure drop.
Therefore, this particular centrifield scrubber is equivalent to the
designated best demonstrated control systems. The controlled emissions
from the 10 tests ranged from 0.019 to 0.104 kg/Mg (0.037 to 0.208 Ib/ton).
The rock processed during the tests was a blend of unbeneficiated and
beneficiated rock. The highest emission level is representative of the
upper range of controlled emissions from any mix of beneficiated and
unbeneficiated rock; up to 100 percent unbeneficiated. Although the rock
processed is representative of the worst-case rock type, the unit is
fired with natural gas. The worst-case fuel type as presented previously
is residual oil. As explained in the previous analysis residual oil can
increase controlled emissions from a high energy venturi scrubber on a
calciner by about 0.01 kg/Mg (0.02 Ib/ton). This emission increase would
raise the highest controlled emission level to 0.12 kg/Mg (0.23 Ib/ton).
Based on this evaluation, the emission limit for calciners calcining
unbeneficiated rock or blends of beneficiated and unbeneficiated rock has
been set at 0.12 kg/Mg (0.23 Ib/ton). Calciners processing blends with a
small percentage of unbeneficiated rock could comply with a lower emission
limit. However, existing data are insufficient to determine an exact
relationship between emission level and blend ratios. This emission
limit applies to all mixtures of unbeneficiated and beneficiated rock,
but is not intended for facilities that would normally beneficiate all
rock.
The majority of existing calcining facilities are using beneficiated
rock. If this trend continues with new facilities, an emission limit
based on unbeneficiated rock would allow the many sources using beneficiated
rock to comply with the emission limits with less than the best demonstrated
control systems. The purpose of NSPS is to require the best demonstrated
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control systems on emission sources; therefore, the emission limit for
calciners of 0.055 kg/Mg (0.11 Ib/ton) that was originally proposed is
retained for those calciners processing beneficiated rock. The rationale
for the original proposed emission limit is presented in Volume 1 and is
based on tests at a facility processing beneficiated rock.
Several commenters questioned the modeling techniques used to set
the emission limit for beneficiated rock calciners. They felt that it
was unreasonable to use theoretical modeling techniques to project the
performance of a high-energy venturi scrubber from the demonstrated
performance of a low-energy scrubber. They also felt that the particle
size distribution used in the scrubber model was in error.
In situations where there are no existing facilities controlled with
either best available control systems or equivalent systems available for
testing, it is technically feasible to use calibrated modeling techniques.
The test data used in the analysis contained controlled emissions from a
3.0 kPa (12 inches of water) pressure drop venturi scrubber. The calibrated
scrubber model was used to project the performance of the same venturi
scrubber at 6.75 kPa (27 inches of water). The original model analysis
presented in Volume I of the BID (page 8-30, 31) indicated that the
controlled emissions would decrease by about 71 percent with the increase
in pressure drop. Using the industry supplied worst-case particle size
distribution for calciners (unbeneficiated Western rock) from Volume I of
the BID (page 4-11), the scrubber performance at both pressure drops has
been remodeled. This particle size distribution actually presents a more
difficult control situation than would occur with beneficiated rock. The
remodeling supports the 71-percent decrease in controlled emissions. The
highest controlled emissions from the source tests of the 3.0 kPa (12
inches of water) unit is 0.12 kg/Mg (0.24 Ib/ton). A reduction of 71
percent in this emission level would indicate an achievable level with
the higher-energy venturi scrubber of about 0.035 kg/Mg (0.07 Ib/ton).
The actual emission limit promulgated for the beneficiated rock calciners
of 0.055 kg/Mg (0.11 Ib/ton) includes a margin to account for any
inaccuracies in the scrubber model and the impact of potential residual
oil firing.
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A frequent comment was that the particulate emission limits could
not be met on a continuous basis because the particulate control equip-
ment could not be operated continuously at maximum efficiency. The
particulate matter emission limits are based on the performance of the
best available control equipment on the worst-case emission levels.
These emission levels represent the most adverse conditions that could
reasonably occur. These levels do not represent the emission levels
occurring under all conditions in the industry. Therefore,'maximum
efficiency will not be required to meet the emission limits at all times.
However, the specified control equipment has demonstrated the ability to
comply continuously with the standards under all conditions. In fact,
equipment malfunctions are the only conditions which could conceivably
prevent compliance at any time. Section 60.11(a) of the general provi-
sions explains that only reference method performance tests are used to
determine compliance with mass emission limits. After or between the
performance tests, opacity limits will indicate compliance of emission
control systems on a continuous basis. Section 60.11(c) states that
opacity standards shall apply at all times except during periods of
start-up, shutdown, and malfunction. Therefore, provisions are provided
for unavoidable excursions above the standards caused by equipment mal-
function. However, it should be noted that Section 60.11(d) requires
that the emission control equipment must be maintained and operated at a
level consistent with good air pollution control practice at all times,
including start-up, shutdown, and malfunction.
2.4.2 Opacity Standard
Several commenters questioned whether the zero-percent opacity
requirements could be achieved continuously. Although the opacity limits
for calciners and grinders have been revised to 10 percent, the opacity
limits for grinders and ground rock storage and handling systems have
been retained at zero percent. One reason stated for this comment is
that, for any deviation of opacity above zero percent, the average for
that time period must exceed zero percent. However, the procedure in
Method 9 takes 24 observations in a 6-minute period, recorded in 5-percent
increments (i.e., 0, 5, 10, etc.). The arithmetic average of the 24
observations, rounded off to the nearest whole number (i.e., 0.4 would be
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rounded off to 0) is the value of opacity used to determine compliance
with the opacity standard. Consequently, the zero-percent opacity standard
for grinders and ground rock handling systems does not necessarily mean
that there are no visible emissions. It means that either visible emissions
during a 6-minute period are insufficient to cause a certified observer
to record them as 5-percent opacity, or that the average of the 24
observations is calculated at less than 0.5 percent.
Another comment was made that high humidities in Florida may result
in "steam plume" formation, which will prevent accurate opacity readings.
However, there are specific procedures in Method 9 for dealing with steam
plume interference. The procedures require that readings on stacks with
steam plume interference are taken on the plume after steam dissipation.
Because of plume diffusion, opacity readings after steam dissipation
should represent more conservative readings than those made at the stack.
Therefore, the presence of a steam plume will not increase the probability
of an opacity violation.
Several commenters questioned the zero-percent opacity standard for
phosphate rock dryers and calciners. They stated that the data base for
the proposed opacity standards on dryers and calciners did not justify
zero-percent opacity, since there were no observations of baghouses, all
the observed scrubbers had steam interference, and one observed ESP-
controlled dryer facility had readings as high as 7.7 percent. They felt
that a 5- to 10-percent opacity standard would be more realistic.
Opacity of a plume varies with the concentration, particle size
distribution, and physical characteristics of the particulates in the
plume and with the thickness of the plume itself. Since the opacity
level is a function of the particulate characteristics of the plume,
opacity is subject to the same variations as the particulate emission
levels from dryers and calciners. Opacity standards are intended to
ensure that particulate emission control systems are properly maintained
and operated to comply with particulate emission limits on a continuous
basis. Opacity limits should be set at levels no more restrictive than
corresponding particulate mass emission limits and should be based on the
demonstrated performance of the best control systems. Opacity limits are
set at levels no more restrictive than particulate limits to ensure that
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any observed violation of the opacity standard will accurately indicate a
violation of the particulate mass emission limits. As noted in
Section 2.4.1, the participate emission limits for dryers and calciners
have been revised based on new data supplied by industry. This worst-
case emission test data did not contain corresponding opacity data.
However, the opacity data base contains observations from an ESP-controlled
dryer with observed average opacity up to 1-1 percent. This particular
ESP system was designed to process twice the gas volume actually processed.
Therefore, the exhaust stack diameter is larger than would typically
occur. If the stack had been designed for half the volume of gas, the
diameter would have been reduced by approximately 29 percent. A
reduction of 29 percent in the stack diameter would theoretically reduce
the opacity level from 7.7 percent to about 6 percent. At the time of
these opacity observations, a Method 5 source test performed on the stack
indicated a particulate emission rate of 0.02 kg/Mg (0.039 Ib/ton) and a
particulate concentration of 0.023 gm/m3 (0.010 gr/acf).
The particulate emission limit for dryers of 0.03 kg/Mg (0.06 Ib/ton)
is based on test data from a 7.5 kPa (30 incheds of water) venturi scrubber-
controlled facility processing coarse pebble rock. This source represents
the application of the best available control system to the worst-case
emission control conditions. The particulate concentration during the
source test was 0.037 g/m3 (0.016 gr/acf). EPA emission test data from
an asphalt aggregate dryer indicated that, for this source, the opacity
increased by about 1.1 percent for every 0.023 g/m3 (0.01 gr/acf) increase
12
in particulate concentration. Since the particle characteristics from
an asphalt aggregate dryer are similar to the particle characteristics
from phosphate rock dryers and calciners, the correlation between opacity
and particulate concentration should also be similar. This correlation
data indicate that the increase in concentration from 0.023 g/m3
(0.010 gr/acf) to 0.037 g/m3 (0.016 gr/acf) would increase opacity from
6 percent at the 0.02 kg/Mg (0.039 Ib/ton) level to 7 percent at the
0.03 kg/Mg (0.06 Ib/ton) emission limit level. The calculated 7 percent
opacity supports a revision in the opacity limit for phosphate rock
dryers to 10 percent. The 10 percent limit was selected to account for
possible deviations above the calculated level. The standard has been
revised accordingly.
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The source test data used as the basis for the particulate emission
limit for calciners processing unbeneficiated rock were also supplied by
the industry. This source test data also did not contain any corresponding
opacity data. However, particulate emissions from phosphate rock calciners
are very similar in particle composition and particle size distribution
to emissions from phosphate rock dryers. Therefore, the opacity
observations from phosphate rock dryers can be used to estimate opacity
levels from phosphate rock calciners. The particulate concentration
during the emission test used to set the promulgated emission limit for
calciners processing unbeneficiated rock was 0.06 g/m3 (0.026 gr/acf).
Based on the 6-percent dryer exhaust opacity at 0.023 g/m3 (0.010 gr/acf)
and the concentration and opacity correlation data from the asphalt
aggregate dryer, the opacity expected at 0.06 g/m3 (0.026 gr/acf) would
be about 8 percent.
The source test used as the basis for the particulate emission limit
for calciners processing beneficiated rock did have corresponding opacity
data at zero-percent opacity. However, there was an attached steam plume
during the observations that may have affected the accuracy of the reading
at the stack. During the emission test, the particulate concentration
was 0.073 g/m3 (0.032 gr/acf). As explained in Section 2.4.1, this unit
was controlled with a 3.0 kPa (12 inches of water) pressure drop venturi
scrubber. With an increase in pressure drop to 7.5 kPa (30 inches of
water) the particulate concentration in the stack would be expected to
decrease to about 0.023 g/m3 (0.010 gr/acf). At this concentration, »
opacity should be about 6 percent as observed on the phosphate rock
dryer. Based on this data, the opacity limits for calciners processing
beneficiated and unbeneficiated rock have been revised to 10-percent
opacity.
A commenter requested a provision to provide for site-specific
relief from the opacity standard at sources where other emission limits
were being met. No provision is necessary in these standards, because
provisions for individual review and site-specific relief are included in
the general provisions under §60.11(e) of 40 CFR 60. These provisions
allow an owner/operator to petition the Administrator for site-specific
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opacity standards in specific cases in which it can be demonstrated that
the opacity standard is being violated while the particulate mass emission
limit is being met.
Another commenter asked whether the visible emission data base for
dryers was based on units firing natural gas, oil, or coal. It was
stated that high sulfur oils and coals would cause higher opacity readings
than natural gas. It was further stated that, if the tested units were
fired with natural gas, the opacity standard should be modified.
EPA acknowledges that some sulfur compounds, because of high
light-reflective properties, can cause disproportionately high opacity
levels. However, the visible emission tests were based on oil-fired, not
natural gas-fired, units. Although the sulfur content of the oil was not
specified, the fuel was a No. 6 fuel oil (indicating moderate to high
sulfur content), and no observations exceeded zero percent opacity.
Also, stack test data has indicated that fuel-bound sulfur reacts chemically
with the calcium oxide in the rock and will form solid calcium sulfate or
sulfite, both of which could be collected in particulate control devices.
2.4.3 Available Control Technology
The comment was made that Volume I of the BID should not have contained
ESPs as a control technique because it was stated in Volume I that ESPs
were not the best demonstrated system, although they are equally efficient
as baghouses and high-energy venturi scrubbers. The commenters further
questioned EPA's judgement that ESPs were equally as efficient as baghouses
or high energy venturi scrubbers on dryers and calciners. The commenters
felt that the source test data base did not support this judgment, and
ESPs should not be used as a basis for the standards.
Alternative particulate control equipment options with control
efficiency levels in the range of, or above, existing controls on phosphate
rock plants are baghouses, venturi scrubbers, and ESPs. Therefore, ESPs
were analyzed in Volume I as a control alternative. The level of control
required by the standards is estimated to be approximately 99.3 percent
when processing the worst-case rock types. EPA agrees that the source
tests of ESPs presented in the BID, Volume I, do not achieve this level
of control. The ESPs tested achieved efficiencies in the range of 93 to
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99 percent efficiency. However, ESP efficiency is a direct function of
the collector plate area to gas volume ratio. By increasing the collector
plate area of the tested ESPs, the efficiency can be increased to 99.3 per-
cent. The economic evaluation of ESPs presented in Volume I of the BID
presented the cost of ESPs at the increased plate area to gas volume
ratio necessary to achieve 99.3 percent control. Because the cost of
ESPs is primarily a function of collector plate area, the larger plate
area results in significantly higher cost. The annualized costs of an
ESP on a model dryer or calciner are 2 to 2.5 times higher than high
energy venturi scrubber or baghouse costs on the same source. Because of
these higher costs, ESPs were not designated as a basis for the standards.
The promulgated emission limits are based on the performance of high
energy venturi scrubbers and baghouses.
The designation of baghouses as best available control technology
was questioned. The commenters complained that no baghouses are in
current use on dryers or calciners, and technological problems associated
with high temperatures and moisture blinding of the bags limit their use.
EPA agrees that no baghouses are currently in use on phosphate rock
dryers or calciners. The selection of baghouses as one of the best
available control equipment options is based on transfer of technology
from similar applications in other industries. Baghouses have been
installed and are operating effectively on kaolin rotary-kiln dryers.
The typical particle size entering filters from kaolin dryers is 80
percent less than 2 micrometers. The kaolin gas stream typically contains
between 20- and 50-percent moisture, a dew point between 160° and 180°F,
13
and a dry bulb temperature between 200° and 250°F. These conditions
represent more severe conditions than typically occur from phosphate rock
dryers or calciners. Two baghouse manufacturers contacted have stated
that baghouses have been applied successfully to more difficult applications,
such as asphalt plants.
Moisture blinding of the bags can be prevented by maintaining
temperatures in the baghouse above the dew point of the water vapor.
This can be accomplished by proper insulation of the baghouse walls to
maintain a 50°F difference between wet-bulb and dry-bulb temperatures.
During cold start-up, the burner can be operated at low fire with no rock
2-27
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in the dryer or calciner until the temperature in the baghouse is raised
14
above the dew point.
High temperature operation is required for baghouses on phosphate
rock dryers and calciners. Filter fabric that has a high-temperature
limit (450°F) well above the typical exhaust temperature from dryers and
calciners (Nomex) is available. However, high-temperature protection
devices may be required to protect the filter bags from damage if exhaust
gas temperatures should rise above the operating limit of the filter
material. The bags can be protected from high temperatures by installing
a temperature sensor in the baghouse inlet with shutoff valves in the
burner fuel supply or by installing an "air bleed" system where a temper-
ature sensor opens a door in the inlet duct so that cold external air is
14
pulled in to dilute the hot exhaust. There are no technical reasons
that prohibit the use of baghouses on phosphate rock dryers or calciners.
In addition, baghouses are not the only control alternative. There is no
reason to prevent an owner from complying with the standards with a
scrubber. The baghouse was designated as the best control system based
on a lower annualized cost.
2.4.4 Coal Firing
A comment was also made that, in the future, calciners and dryers
may be fired with coal, but coal-firing problems had not been considered
or analyzed in the development of the standard. During the development
of Volume 1, a review of existing industrial sources revealed no coal-
fired units. However, as explained in Section 2.4.1 the impacts of coal
and residual oil firing on achievable emission levels has been evaluated.
This analysis indicated that residual oil firing would have the greatest
effect on controlled emission levels. The potential impacts from residual
oil firing have been included in the dryer and calciner emission limits.
2.5 TESTING AND MONITORING
2.5.1 Continuous Opacity Monitoring
The method of determining opacity readings for continuous monitoring
were questioned. The commenters asked whether continuous monitoring
equipment would be needed, or if periodic readings by qualified human
observers would suffice. Section 60.403 of the standards requires that
continuous opacity monitoring equipment be installed, calibrated, maintained,
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and operated on the exhaust from all control equipment except scrubbers.
Continuous pressure-drop and liquid-supply-pressure monitoring equipment
is required for wet scrubber-controlled facilities. However, scrubber-
controlled facilities must still comply with the opacity standard. The
purpose of continuous monitoring equipment is to ensure continuous and
proper operation of particulate control equipment. Sections 60.403(d)
and (e) require that continuous monitoring violations be reported. The
United States Court of Appeals for the District of Columbia" Circuit has
specifically upheld the use of continuous opacity monitors in
National Lime Association v. EPA 627 F.2d 416 (1980). However, only EPA
reference method tests can be used to determine compliance with regulations.
Section 60.404 specifies that Method 5 is used to determine compliance
with the particulate standards and Method 9 (using a trained observer) is
used to determine compliance with the opacity regulation.
Several commenters pointed out that the EPA performance specifications
for continuous opacity monitors allow for a cumulative accuracy error of
up to 9.2 percent. They contend that this allowed error would prevent
accurate demonstrations of attainment of the opacity standards. The
purpose of continuous monitoring equipment is to ensure continuous operation
of control equipment and not to demonstrate compliance with the opacity
standards. Only Method 9 can demonstrate attainment of the opacity
standards. Therefore, the possible 9.2-percent variation will not affect
demonstration of attainment of the standards. Section 60.13(c) requires
that continuous monitoring equipment be evaluated during particulate
performance tests. The performance of the continuous monitoring equipment
can then be correlated to particulate control equipment performance.
Enforcement agencies can incorporate any demonstrated variations in
continuous monitoring equipment performance in evaluating continuous
operation of the control equipment at the required control level.
Two commenters stated that opacity averaging periods of 6 minutes
with overlapping time intervals would produce an excessive amount of
paperwork. The required 6-minute opacity averaging periods are discrete,
successive 6-minute periods and are not composed of overlapping time
intervals. Section 60.13(e)(l) states that opacity continuous monitors
shall complete a minimum of one cycle of sampling and analyzing for each
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successive 10-second period and one cycle for data recording for each
successive 6-minute period. The volume of paperwork produced would not
be as large as believed by the commenter.
The comment was also made that the costs to purchase, install,
operate, and maintain continuous opacity monitors is totally unreasonable.
The cost impact to purchase, install, operate, and maintain continuous
opacity monitoring equipment was addressed and evaluated in Volume 1 of
the BID (page 7-58). The annualized cost of a typical opacity monitoring
system is about $12,500 per year (1978 dollars). This cost is relatively
minor compared to emission control system costs (about 4.2 percent of a
high-energy venturi scrubber on a 150-ton/hour dryer) and was determined
to be cost-effective.
One commenter questioned the rationale for requiring continuous
monitoring equipment on the small control equipment usually located on
ground rock storage and handling system emission points. The purpose of
continuous monitoring equipment is to ensure the proper and continuous
operation of emission control equipment. Because ground rock storage and
handling systems vary greatly from plant to plant, no typical handling
and storage system can be defined. Most of the potential emissions from
storage and handling systems are fugitive emissions. These fugitive
emissions often result from holes in enclosures. Therefore, it is
difficult to define or predict emission points and appropriate emission
control equipment. However, Method 9 opacity observations can routinely
locate and quantify fugitive emissions from these sytems. Observations
have indicated that properly maintained ground rock storage and handling
systems have no visible emissions; therefore, these systems are subject
only to a zero-percent opacity standard. The annualized cost of a
typical opacity monitoring system is about $12,500 per year (1978 dollars).
Because there is no specified emission control equipment requirement and
compliance with the opacity standard can be routinely demonstrated with
Method 9, these costs are considered excessive. Therefore, the require-
ment for continuous opacity monitors on ground rock storage and handling
systems has been deleted from the standards.
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Table 2.1 LIST OF COMMENTERS ON THE PROPOSED STANDARDS
OF PERFORMANCE FOR PHOSPHATE ROCK PLANTS
Commenter Affiliation
IV-D-1 Marion DeRonde, President .
The Sarasota Audubon Society, Inc.
Post Office Box 15423
Sarasota, Florida 33579
IV-D-2 James W. Cooper, Director
Division of Air Pollution Control
Alabama Air Pollution Control Commission
645 S. McDonough Street
Montgomery, Alabama 36130
IV-D-3 Robert S. Hearon
Environmental Services Supervisor
Minerals Division
International Minerals & Chemical Corp.
Post Office Box -867
Bartow, Florida 33830
IV-D-4 Archie Carr III, Ph.D.
Special Assistant to the President
Florida Audubon Society
IV-D-5 William R. King
Environmental Manager
FMC Corporation
2000 Market Street
Philadelphia, Pennsylvania 19103
IV-D-6 James H. Rathlesberger
Special Assistant to the Secretary
U. S. Department of the Interior
Office of the Secretary
Washington, D. C. 20240
IV-D-7 William A. Schimming, Director
Environmental Affairs
CF Industries
Post Office Box 1480
Bartow, Florida 33830
(continued)
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Table 2-1. Continued
Commentor Affiliation
IV-D-8 William V. Skidmore
Acting Deputy General Counsel
U. S. Department of Commerce
Washington, D. C. 20230
IV-D-9 E. R. Bingham, President
AMAX Environmental Services, Inc.
4704 Marian Street
Denver, Colorado 80212
IV-D-10 H. A. Snell
Alumet
Post Office Box 834
Soda Springs, Idaho 83276
IV-D-11 Edwin M. Wheeler
The Fertilizer Institute
1015 18th Street, N. W.
Washington, D. C. 20036
IV-D-12 J. F. Cochrane, Director
Environmental Engineering Department
J. R. Simplot Company
Post Office Box 912
Pocatello, Idaho 83201
IV-D-13 Mohamed T. El-Ashry
Director of Environmental Quality
Tennessee Valley Authority
Morris, Tennessee 37828
IV-D-14 Steve Smallwood
Bureau of Air Quality Management
Twin Towers Office Building
2600 Blair Stone Road
Tallahassee, Florida 32301
IV-D-15 Douglas G. Mercer, Supervisor
Environmental Programs and Industrial Hygiene
Texasgulf, Inc.
Post Office Box 48
Aurora, North Carolina 27806
(continued)
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Table 2-1. Concluded
Commenter Affiliation
IV-D-16 Samuel M. Lane, Manager
Environmental and Manufacturing Services
Mobil Chemical Company
Phosphorus Division
Post Office Box 26683
Richmond, Virginia 23261
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2.6 REFERENCES
1. Stowasser, W. F. Phosphate Mineral Commodity Profiles. U.S. Department
of the Interior, Bureau of Mines. January 1979.
2. Information obtained from the following sources: a. Letters from
A. B. Capper, Catalytic, Inc., to Lee Beck, EPA, dated August 30, 1974;
September 6, 1974; October 18, 1974; October 25, 1974; October 30, 1974;
November 4, 1974; November 20, 1974; December 30, 1974; and
January 6, 1975. b. Letter from R. A. Schutt, EPA, to Mr. Lee Beck,
EPA, dated October 15, 1974.
3. Letter from Mr. J. C. Barber, Tennessee Valley Authority, to Mr. Lee Beck,
U.S. Environmental Protection Agency, dated November 18, 1975.
4. Standards Support and Environmental Impact Statement, Volume I:
Proposed Standards of Performance for Lime Manufacturing Plants,
U.S. Environmental Protection Agency. Research Triangle Park, N.C.
Publication No. EPA-450/2-77-007a. April 1977. p. 8.4-8.8.
5. The Maintenance and Operation of Exhaust Systems in the Hot Mix
Plant. Part 1. The National Asphalt Pavement Association. Infor-
mation Series 52 & 52A. p. 27-35.
6. Neveril, R.B. Capital and Operating Costs of Selected Air Pollution
Control Systems. CARD, Inc. EPA Contract No. 68-02-2899.
December 1978. p. 3-16.
7. Letter from George DeNobile, Marketing Department, Merrick Scale
Manufacturing Company, to George Richard, Environmental Engineering
Divison of TRW, Inc. May 1, 1979. Phosphate rock equipment costs.
8. Compilation of Air Pollutant Emissions Factors, 2nd edition.
U.S. Environmental Protection Agency. Publication No. AP-42.
February 1976.
9. Particulate Pollutant System Study, Volume II - Fine Particle Emissions.
U.S. Environmental Protection Agency. Publication No. APTD-0744.
p. 73.
10. Air Pollution Engineering Manual, 2nd edition. U.S. Environmental
Protection Agency. Publication No. AP-40. May 1973. p. 561.
11. McCain, J. D. Evaluation of Centrifield Scrubber. Southern Research
Institute for U.S. Environmental Protection Agency. Research Triangle
Park, North Carolina. Publication No. EPA-650/2-74-129a. June 1975.
32 p.
12. In-Stack Transmissometer Measurement of Particulate Opacity and Mass
Concentration. U.S. Environmental Protection Agency. Publication
No. EPA-650/2-74-120. November 1974. p. 34-45.
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13. Lindsey, A. M., and R. Segars. Control of Particulate Emissions
from Phosphate Rock Dryers. U.S. Environmental Protection Agency.
Atlanta, Georgia. January 1974. p. 6.
14. Reference 5, p. 27-35.
2-35
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/3-79-0175
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Phosphate Rock Plants
Promulgated Standards
- Background Information for
5. REPORT DATE
April 1982
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle Park, North Carolina 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-3063
12. SPONSORING AGENCY NAME AND ADDRESS
DAA for Air Quality Planning and Standards
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Standards of performance for the control of particulate and visible emissions
from phosphate rock plants are being promulgated under the authority of Section 111
of the Clean Air Act. These standards apply only to phosphate rock dryers,
calciners, grinders and ground rock storage and handling systems for which construc-
tion or modification began on or after September 21, 1979. This document contains
comments received on the proposed standards and responses to those comments. The
promulgated standards will limit particulate emissions from all dryers and from
calciners processing unbeneficiated rock to 0.03 and 0.12 kg/Mg, respectively.
Particulate emissions from beneficiated rock calciners will be limited to 0.055 kg/Mg.
Visible emissions from all dryers and calciners will be limited to 10 percent
opacity. Particulate emissions from grinders will be limited to 0.006 kg/Mg with
0 percent opacity. Visible emissions from ground rock storage and handling
systems will be limited to 0 percent opacity.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDEDTERMS
c. COSATl E;ield/Group
Air Pollution
Pollution Control
Standards of Performance
Phosphate Rock Plants
Particulate Matter
Air Pollution Control
13B
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
49
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (Rev. 4-77) PREVIOUS EDITION is OBSOLETE
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