National Emission Standards for Hazardous Air Pollutants; Proposed Standards for Hazardous Air Pollutants Emissions for the Portland Cement Manufacturing Industry
Federal RegisterMar 24, 1998
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SUMMARY: This action proposes national emission standards for hazardous
air pollutants (NESHAP) for new and existing sources in portland cement
manufacturing plants. Exposure to the hazardous air pollutants (HAPs)
in these emissions may be associated with a wide variety of effects,
including carcinogenic, respiratory, nervous system, dermal,
developmental, and/or reproductive health effects. Implementation of
the proposed requirements would reduce emissions of several HAPs.
The standards are proposed under the authority of section 112(d) of
the Clean Air Act as amended (the Act) and are based on the
Administrator's determination that portland cement manufacturing plants
may reasonably be anticipated to emit several of the HAPs listed in
section 112(b) of the Act from the various process operations found
within the industry. The proposed NESHAP would provide protection to
the public by requiring all portland cement plants which are major
sources to meet emission standards reflecting the application of the
maximum achievable control technology (MACT).
DATES: Comments. The EPA will accept comments on the proposed rule
until May 26, 1998.
Public Hearing. If anyone contacts the Agency requesting to speak
at a public hearing, the hearing will be held at the Agency's Office of
Administration Auditorium, Research Triangle Park, North Carolina on
April 23, 1998 beginning at 10:00 a.m. Persons wishing to present oral
testimony must contact the Agency by April 14, 1998.
ADDRESSES: Comments. Comments should be submitted (in duplicate) to:
Air and Radiation Docket and Information Center (6102), Attention:
Docket No. A-92-53, U.S. Environmental Protection Agency, 401 M Street
SW., Washington, DC 20460. The Agency requests that a separate copy
also be sent to the contact person listed below (Mr. Joseph Wood).
Comments and data may also be submitted electronically by following the
instructions provided in the SUPPLEMENTARY INFORMATION section. No
confidential business information (CBI) should be submitted through
electronic mail.
Public Hearing. Persons wishing to present oral testimony or to
inquire as to whether or not a hearing is to be held should notify Ms.
Cathy Coats, Minerals and Inorganic Chemicals Group (MD-13), U.S.
Environmental Protection Agency, Research Triangle Park, NC 27711,
telephone number (919) 541-5422. Additional information regarding the
public hearing is given in the SUPPLEMENTARY INFORMATION section.
Docket. The official record for this rulemaking, as well as the
public version, has been established under Docket No. A-92-53
(including comments and data submitted electronically as described
below). A public version of this record, including printed, paper
versions of electronic comments and data, which does not include any
information claimed as CBI, is available for inspection from 8 a.m. to
4 p.m., Monday through Friday, excluding legal holidays. The official
rulemaking docket is located at the address in the ADDRESSES section
above. Alternatively, a docket index, as well as individual items
contained within the docket, may be obtained by calling (202) 260-7548.
A reasonable fee may be charged for copying.
FOR FURTHER INFORMATION CONTACT: For information about this proposed
rule, contact Mr. Joseph Wood, P.E., Minerals and Inorganic Chemicals
Group, Emission Standards Division (MD-13), U.S. Environmental
Protection Agency, Research Triangle Park, NC 27711, telephone number
(919) 541-5446; electronic mail address [email protected]. For
information about the proposed test methods contact Ms. Rima
Dishakjian, Emission Measurement Center, Emissions, Monitoring and
Analysis Division (MD-19), U.S. Environmental Protection Agency,
Research Triangle Park, NC 27711, telephone number (919) 541-0443.
SUPPLEMENTARY INFORMATION: Electronic filing. Electronic comments can
be sent directly to the EPA at [email protected].
Electronic comments and data must be submitted as an ASCII file
avoiding the use of special characters and any form of encryption.
Comments and data will also be accepted on disks in Wordperfect 5.1 or
6.1 file format or ASCII file format. All comments and data in
electronic form must be identified by the docket number A-92-53.
Electronic comments may be filed online at many Federal Depository
Libraries.
Implementation of the proposed requirements would achieve an
emission reduction from existing and projected new sources estimated at
82 megagrams per year (Mg/yr) (90 tons per year [tpy]) of HAPs and
4,900 Mg/yr (5,400 tpy) of other pollutants (volatile organic compounds
[VOC] and particulate matter [PM]). The EPA is also proposing to
require portland cement plants that are area sources to meet emission
standards for dioxins and furans reflecting the application of MACT.
The EPA is also proposing Methods 320, 321, and 322 with the
standards for addition to 40 CFR part 63, appendix A. These methods may
be used to assist in determining the applicability of the proposed
emission limitations.
Public Hearing. If a public hearing is requested and held, EPA will
ask clarifying questions during the oral presentation but will not
respond to the presentations or comments. Written statements and
supporting information will be considered with equivalent weight as any
oral statement and supporting information subsequently presented at a
public hearing, if held.
Confidential Business Information. Commenters wishing to submit
proprietary information for consideration should clearly distinguish
such information from other comments and clearly label it
``Confidential Business Information.'' Submissions containing such
proprietary information should be sent directly to the following
address, and not to the public docket, to ensure that proprietary
information is not inadvertently placed in the docket: Attention: Mr.
Joseph Wood, c/o Ms. Melva Toomer, U.S. EPA Confidential Business
Information Manager, OAQPS (MD-13); Research Triangle Park, NC 27711.
Information covered by such claim of confidentiality will be disclosed
by the EPA only to the extent allowed and by the procedures set forth
in 40 CFR part 2. If no claim of confidentiality accompanies a
submission when it is received by the EPA, the submission may be made
available to the public without further notice to the commenter.
Regulated entities. Entities potentially regulated by this action
are those who have the potential to emit HAPs listed in section 112(b)
of the Act in the regulated categories and entities shown in Table 1.
[[Page 14183]]
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that the EPA is now
aware could potentially be regulated by this action. Other types of
entities not listed in this table could also be regulated. To determine
whether your facility is regulated by this action, you should carefully
examine the applicability criteria in Sec. 63.1340 of the proposed
rule. If you have questions regarding the applicability of this action
to a particular entity, consult the person listed in the preceding FOR
FURTHER INFORMATION CONTACT section of this preamble.
Table 1.--Regulated Entities
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Category Examples of regulated entities
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Industry............................... Owners or operators of portland
cement manufacturing plants.
State.................................. Owners or operators of portland
cement manufacturing plants.
Tribal associations.................... Owners or operators of portland
cement manufacturing plants.
Federal agencies....................... None.
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Technology Transfer Network. The proposed regulatory text is also
available on the Technology Transfer Network (TTN), one of EPA's
electronic bulletin boards. The TTN provides information and technology
exchange in various areas of air pollution control. The service is
free, except for the cost of a phone call. Dial (919) 541-5742 for up
to a 14,400 BPS modem. The TTN is also accessible through the Internet
(world wide web) at http://www.epa.gov/ttn/. If more information on the
TTN is needed, call the HELP line at (919) 541-5384. The help desk is
staffed from 11 a.m. to 5 p.m.; a voice menu is available at other
times.
Outline. The information in this preamble is organized as shown
below.
I. Statutory Authority
II. Introduction
A. Background
B. NESHAP for Source Categories
C. Health Effects of Pollutants
D. Portland Cement Manufacturing Industry Profile
III. Summary of Proposed Standards
A. Applicability
B. Emission Limits and Requirements
C. Performance Test and Compliance Provisions
D. Monitoring Requirements
E. Notification, Recordkeeping, and Reporting Requirements
IV. Impacts of Proposed Standards
A. Applicability
B. Air Quality Impacts
C. Water Impacts
D. Solid Waste Impacts
E. Energy Impacts
F. Nonair Health and Environmental Impacts
G. Cost Impacts
H. Economic Impacts
V. Selection of Proposed Standards
A. Selection of Source Category
B. Selection of Emission Sources
1. Feed Preparation Processes (Grinding, Conveying)
2. Feed Preparation Processes (Drying, Blending, Storage)
3. Kiln
4. Clinker Cooler
5. Finish Grinding/Conversion of Clinker to Portland Cement
C. Selection of Pollutants
D. Selection of Proposed Standards for Existing and New Sources
1. Background
2. MACT Floor Technology, Emission Limits, and Format
E. Selection of Testing and Monitoring Requirements
1. Kiln and In-line Kiln Raw Mill PM Emissions
2. Kiln D/F Emissions
3. Kiln and Raw Material Dryer THC Emissions
4. Clinker Cooler PM Emissions
5. Raw and Finish Mill PM Emissions
6. Raw Material Dryer and Materials Handling Processes PM
Emissions
7. General Monitoring Requirements
F. Selection of Notification, Recordkeeping, and Reporting
Requirements
VI. Public Participation
VII. Administrative Requirements
A. Docket
B. Public Hearing
C. Executive Order 12866
D. Enhancing the Intergovernmental Partnership Under Executive
Order 12875
E. Unfunded Mandates Reform Act
F. Regulatory Flexibility Act
G. Paperwork Reduction Act
H. Clean Air Act
I. Statutory Authority
The statutory authority for this proposal is provided by sections
101, 112, 114, 116, 183(f) and 301 of the Clean Air Act, as amended (42
U.S.C. 7401, 7411, 7414, 7416, 7511(f) and 7601).
II. Introduction
A. Background
Nationwide baseline HAP emissions from portland cement
manufacturing plants are estimated to be 260 Mg/yr (290 tpy) at the
current level of control. The HAPs released from kiln systems include
acetaldehyde, arsenic, benzene, cadmium, chromium, chlorobenzene,
dibenzofurans, formaldehyde, hexane, hydrogen chloride, lead,
manganese, mercury, naphthalene, nickel, phenol, polycyclic organic
matter, selenium, styrene, 2,3,7,8-tetrachlorodibenzo-p-dioxin,
toluene, and xylenes. The HAPs released from raw material dryers should
be similar to those from the kiln. The HAPs released from clinker
coolers, raw mills, finish mills, storage bins, conveying system
transfer points, bagging systems and bulk loading and unloading systems
include arsenic, cadmium, chromium, lead, manganese, mercury, nickel,
and selenium. Implementing MACT-level controls is expected to decrease
emissions of these HAPs from existing and projected new sources by
approximately 82 Mg/yr (90 tpy). Plants can achieve this reduction by
upgrading or installing fabric filters (FF), also known as baghouses,
and electrostatic precipitators (ESP) to decrease HAP metals; limiting
temperatures at the particulate matter control device (PMCD) inlet to
decrease dioxin and furan (D/F) emissions; and selecting suitable feed
materials to decrease organic HAP emissions.
The overall effect of these standards would be to improve the
control performance of the industry to the level achieved by the best
performing plants. In addition to the health and environmental benefits
associated with HAP emission reductions, benefits of this action
include a decrease in site-specific emission levels of PM and VOC and
lowered occupational exposure levels for employees.
The nationwide capital and annualized costs of the proposed NESHAP,
including emission controls and associated monitoring equipment, are
estimated at $88 million and $27 million/yr, respectively. The economic
impacts are predicted to increase prices of portland cement by an
average of 1.1 percent.
To minimize adverse impacts, the Agency has proposed controls at
the MACT-floor level, tailored the requirements to allow less-costly
testing and monitoring by using surrogates for HAP emissions and
provided choice in methods of control. The proposed rule
[[Page 14184]]
is ``user friendly,'' with language that is easy to understand by all
of the regulated community. The EPA also proposes to allow existing
facilities up to 3 years to comply. And, as allowed under section
112(i)(3)(B) of the Act, the Administrator or delegated regulatory
authority also may grant 1 additional year if necessary for the
installation of controls.
B. NESHAP for Source Categories
Section 112 of the Act as amended specifically directs the EPA to
develop a list of all categories of major sources and such area sources
as appropriate that emit one or more of the HAPs listed in the Act. The
EPA is further directed to develop NESHAP to control emissions of HAPs
from both existing and new major sources, where a major source is
defined as a source that emits or has the potential to emit 9.1 Mg/yr
(10 tpy) or more of any one HAP or 22.7 Mg/yr (25 tpy) of any
combination of HAPs. The statute requires the standards to reflect the
maximum degree of reduction in HAP emissions that is achievable, taking
into consideration the cost of achieving the emission reduction, any
nonair quality health and environmental impacts, and energy
requirements. This level of control is commonly referred to as MACT.
The control of HAPs is achieved through the promulgation of
technology-based emission standards under sections 112(d) and 112(f)
and work practice standards under 112(h) for categories of sources that
emit HAPs. Emission reductions may be accomplished through the
application of measures, processes, methods, systems, or techniques
including, but not limited to: (1) Reducing the volume of, or
eliminating emissions of, such pollutants through process changes,
substitution of materials, or other modifications; (2) enclosing
systems or processes to eliminate emissions; (3) collecting, capturing,
or treating such pollutants when released from a process, stack,
storage or fugitive emissions point; (4) design, equipment, work
practice, or operational standards (including requirements for operator
training or certification) as provided in subsection (h); or (5) a
combination of the above. [See section 112(d)(2) of the Act.] The EPA
may promulgate more stringent regulations to address residual risk that
remains after the imposition of controls at a later date.
C. Health Effects of Pollutants
The Clean Air Act was created in part to protect and enhance the
quality of the Nation's air resources so as to promote the public
health and welfare and the productive capacity of its population. [See
section 101(b)(1).] In the 1990 Amendments to the Clean Air Act,
Congress specified that each standard for major sources must require
the maximum reduction in emissions of HAPs that EPA determines is
achievable considering cost, health and environmental impacts, and
energy requirements. Title III of the Act establishes a control
technology-based program to reduce stationary source emissions of HAPs.
The goal of section 112(d) (in Title III) is to apply such control
technology to reduce emissions and thereby reduce the hazard of HAPs
emitted from stationary sources.
Section 112(b) of the Act lists HAPs believed to cause adverse
health or environmental effects. The EPA recognizes that the degree of
adverse effects to health can range from mild to severe. The extent and
degree to which the health effects may be experienced is dependent
upon: (1) The ambient concentrations observed in the area (e.g., as
influenced by emission rates, meteorological conditions, and terrain);
(2) the frequency of and duration of exposures; (3) characteristics of
exposed individuals (e.g., genetics, age, pre-existing health
conditions, and lifestyle) which vary significantly with the
population; and (4) pollutant-specific characteristics (e.g., toxicity,
half-life in the environment, bioaccumulation, and persistence). In
essence, these MACT standards would ensure that all major sources of
air toxic emissions achieve the level of control already being achieved
by the better controlled and lower emitting sources in each category.
This approach provides assurance to citizens that each major source of
toxic air pollution will be required to effectively control its
emissions. At the same time, this approach provides a level economic
playing field, ensuring that facilities that employ cleaner processes
and good emissions controls are not disadvantaged relative to
competitors with poorer controls.
Available emission data, collected in conjunction with the
development of this NESHAP, show that non-volatile HAP metals, mercury,
organic HAPs and hydrogen chloride are the predominant HAPs emitted
from portland cement manufacturing plants. These pollutants (except
mercury and hydrogen chloride) have the potential to be reduced by
implementation of the proposed emission limits. In addition to the
HAPs, the portland cement manufacturing NESHAP would also control some
of the pollutants whose emissions are controlled under the National
Ambient Air Quality Standards (NAAQS). These pollutants include PM,
VOC, and lead. The following is a summary of the potential health
effects associated with exposures, at some level, to pollutants that
would be reduced by the standard.
Almost all metals appearing on the section 112(b) list are emitted
from portland cement manufacturing affected sources. There is a wide
range of targets of toxicity for these metals. Effects include skin
irritation, mucous membrane irritation (e.g., lung irritation),
gastrointestinal effects, nervous system effects (including cognitive
effects, tremor, and numbness), increased blood pressure, and
reproductive and developmental effects. Additionally, several of the
metals accumulate in the environment and in the human body. Cadmium,
for example, is a cumulative pollutant which causes kidney effects
after the cessation of exposure. Similarly, the onset of effects from
beryllium exposure may be delayed by months to years. Many of the metal
compounds are also known (arsenic, chromium (VI)) or probable (cadmium,
nickel carbonyl, lead, and beryllium) human carcinogens.
Organic compounds which will potentially be decreased by the
proposed standard include but are not limited to acetaldehyde, benzene,
chlorobenzene, formaldehyde, D/F, hexane, naphthalene, phenol,
polycyclic organic matter, styrene, toluene, and xylenes. Each of these
organic compounds has a range of potential health effects associated
with exposure at some level. Some of the effects associated with short-
term inhalation exposure to these pollutants are similar and include
irritation of the eyes, skin, and respiratory tract in humans; central
nervous system effects (e.g., drowsiness, dizziness, headaches,
depression, nausea, irregular heartbeat); reproductive and
developmental effects; and, neurological effects. Exposure to benzene
at extremely high concentrations may even lead to respiratory
paralysis, coma, or death.
Health effects associated with long-term inhalation exposure in
humans to the organic compounds which will potentially be decreased by
the proposed standard may include mild symptoms such as nausea,
headache, weakness, insomnia, intestinal pain, and burning eyes;
effects on the central nervous system; disorders of the blood; toxicity
to the immune system; reproductive disorders in women (e.g., increased
risk of spontaneous abortion); developmental effects; gastrointestinal
irritation; liver injury; and muscular effects.
[[Page 14185]]
In addition to the non-cancer effects described above, some of the
organic HAPs that would be controlled under this proposed standard are
either known (benzene) or probable (formaldehyde and D/F) human
carcinogens.
Hydrogen chloride (HCl) is highly corrosive to the eyes, skin, and
mucous membranes. Short-term inhalation of HCl by humans may cause
coughing, hoarseness, inflammation and ulceration of the respiratory
tract, as well as chest pain and pulmonary edema. Long-term
occupational exposure of humans to HCl has been reported to cause
inflammation of the stomach, skin, and lungs, and photosensitization.
The health effects of PM, lead, and VOC that would be reduced by
this standard are described in EPA's Criteria Documents, which support
the NAAQS. Briefly, PM emissions have been associated with aggravation
of existing respiratory and cardiovascular disease and increased risk
of premature death. Depending on the degree of exposure, lead can cause
subtle effects on behavior and cognition, increased blood pressure,
reproductive effects, seizures, and even death.
Volatile organic compounds are precursors to the formation of ozone
in the ambient air. At ambient levels, ozone has been shown in human
laboratory and community studies to be responsible for the reduction of
lung function, respiratory symptoms (e.g., cough, chest pain, throat
and nose irritation), increased hospital admissions for respiratory
causes, and increased lung inflammation. Animal studies have shown
increased susceptibility to respiratory infection and lung structure
changes. Exposure to ozone has also been linked to harmful effects on
agricultural crops and forests.
D. Portland Cement Manufacturing Industry Profile
Portland cement is a fine powder, usually gray in color, that
consists of a mixture of the minerals dicalcium silicate, tricalcium
silicate, tricalcium aluminate, and tetracalcium aluminoferrite, to
which one or more forms of calcium sulfate have been added (docket item
II-I-43, p. 746). The primary end use of portland cement is as the key
ingredient in portland cement concrete, which is used in almost all
construction applications.
In 1993, 44 companies operated 118 portland cement plants located
in 37 states. The manufacture of portland cement is covered by SIC code
3241 for hydraulic cements. According to U.S. Small Business
Administration size standards, companies owning portland cement plants
are categorized as small if the total number of employees at the
company is less than 750. Otherwise the company is classified as large.
A total of 7 companies are categorized as small, while the remaining 37
companies are in the large category (docket item II-D-200).
Few new plants are predicted to be constructed during the next 5
years. The EPA estimates that two to four existing plants will undergo
reconstruction in the next 5 years.
All existing kilns and alkali bypasses have PM control devices.
Some existing cement manufacturing plants are required to meet new
source performance standards (NSPS) for PM (40 CFR part 60, subpart F).
The affected facilities to which the NSPS apply are the kiln, kiln gas
alkali bypass, clinker cooler, raw material dryer, and materials
handling processes.
III. Summary of Proposed Standards
A. Applicability
The proposed standards apply to each existing, reconstructed, and
newly constructed portland cement manufacturing plant at any facility
which is a major source or an area source, with the following
exception. Some portland cement plants fire hazardous wastes in the
kiln to provide part or all of the fuel requirement for clinker
production. Portland cement kilns and in-line kiln/raw mills subject to
the NESHAP for hazardous waste combustors 1 (HWC) are not
subject to this standard; however other affected sources at portland
cement plants where hazardous waste is burned in the kiln are subject
to this standard.
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\1\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
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For portland cement plants with on-site non-metallic minerals
processing facilities, the first affected source in the sequence of
materials handling operations subject to this proposed NESHAP is the
raw material storage, which is just prior to the raw mill. The primary
and secondary crushers and any other equipment in the non-metallic
minerals processing plant, which precede the raw material storage are
not affected sources under the proposed NESHAP. Furthermore, the first
conveyor system transfer point subject to the proposed NESHAP is the
transfer point associated with the conveyor transferring material from
the raw material storage to the raw mill. Conveyor system transfer
points prior to this conveyor are not affected sources under this
proposed NESHAP (docket item II-B-53).
This regulation does not apply to the emissions from cement kiln
dust (CKD) storage facilities (i.e., CKD piles or landfills). A
separate rulemaking will be forthcoming from EPA's Office of Solid
Waste (OSW) that will apply to air emissions associated with CKD
management and disposal facilities.
Except for hazardous waste burning (HW) cement kilns and HW in-line
kiln/raw mills, EPA is proposing to apply these standards to all cement
kilns and in-line kiln/raw mills regardless of the material being
combusted in the kiln. This proposal, however, does not preclude EPA
from determining that cement kilns combusting solid waste materials
should be regulated under section 129 of the Clean Air Act, 42 U.S.C.
7429, and to revise the applicability section of these regulations
accordingly at the time section 129 regulations applicable to cement
kilns are promulgated.
The EPA believes that applying this regulation to all non-hazardous
waste burning (NHW) cement kilns regardless of the material combusted
in the kiln is necessary at this time due to the Court of Appeals for
the District of Columbia's recent decision in Davis County Solid Waste
Management District v. Environmental Protection Agency, 101 F.3d 1395
(D.C. Cir. 1996) (petition to review municipal waste combustor
(``MWC'') regulations promulgated on December 19, 1995 pursuant to
section 129 of the Act, 60 FR 65387). In the applicability section of
the MWC regulations, EPA applied the standards to all solid waste
incineration units combusting more than 30-percent municipal solid
waste. Two owners and operators of MWC units with capacity less than
250 tons/day filed petitions for review on the grounds that EPA
improperly had included their units in the large category. The Cement
Kiln Recycling Coalition (``CKRC'') also filed a petition for review on
the grounds that the standards should not apply to cement kilns. In its
opinion dated December 6, 1996, the Court indicated its intent to
vacate the standards in their entirety on the grounds raised by the two
petitioners who own and operate MWC units; as a result, the Court did
not reach the issue raised by CKRC. Accordingly, EPA believes that it
is appropriate to apply these regulations as a gap-filling measure to
control emissions from NHW cement kilns and in-line kiln/raw mills
regardless of the material combusted in the kiln (except for hazardous
waste) until EPA determines whether regulations applicable to cement
kilns combusting solid waste materials should be re-promulgated under
section 129. To
[[Page 14186]]
decide otherwise would have the potential effect of allowing cement
kiln owners and operators to avoid regulation by adding some solid
waste material to the cement kiln.
As background, section 129(a)(1)(A) requires the Administrator to
establish performance standards and other requirements pursuant to
section 111 and section 129 of the Act for each category of solid waste
incineration units [42 U.S.C. 7429(a)(1)(A)]. Whereas section 112(c) of
the Act requires EPA to determine major and area sources of the 188
hazardous air pollutants (HAPs) listed in section 112(b), Congress
specifically listed in section 129 various categories of solid waste
incineration units that EPA must regulate, including solid waste
incineration units combusting municipal solid waste [sections
129(a)(1)(B) and (C)], solid waste incineration units combusting
hospital waste, medical waste, and infectious waste [section
129(a)(1)(C)], solid waste incineration units combusting commercial or
industrial waste [section 129(a)(1)(D)], and ``other categories of
solid waste incineration units'' which are to be defined by EPA [42
U.S.C. 7429(a)(1)].
Section 129(g)(1) of the Act broadly defines a solid waste
incineration unit (``SWIU'') as ``a distinct operating unit of any
facility which combusts any solid waste material from commercial or
industrial establishments or the general public * * *.'' 42 U.S.C.
7429(g)(1) (emphasis added). Section 129(g)(1) expressly states that
``incinerators or other units required to have a permit under section
3005 of the Solid Waste Disposal Act, 42 U.S.C. 6925'' shall not be
considered a SWIU. That section also expressly excludes from the
definition of SWIU the following units:
(A) materials recovery facilities (including primary or
secondary smelters) which combust waste for the primary purpose of
recovering metals, (B) qualifying small power production facilities,
as defined in section 769(17)(C) of Title 16, or qualifying
cogeneration facilities as defined in section 796(18)(B) of Title
16, which burn homogeneous waste (such as units which burn tires or
used oil, but not including refuse-derived fuel) for the production
of electric energy or in the case of qualifying cogeneration
facilities which burn homogenous waste for the production of
electric energy (such as heat) which are used for industrial,
commercial, heating or cooling purposes, or (C) air curtain
incinerators provided that such incinerators only burn wood wastes,
yard wastes and clean lumber and that such air curtain incinerators
comply with opacity limitations to be established by the
Administrator by rule.
42 U.S.C. 7429(g)(1). Accordingly, with the exception of those solid
waste incineration units that are expressly excluded from regulation by
section 129(g)(1), Congress intended EPA to establish regulations for
all SWIU's under section 129. This includes cement kilns that combust
solid waste materials, including refuse-derived fuel.
Section 129 is similar to section 112 of the Act in that both
require EPA to establish performance standards that are based upon the
performance of maximum achievable control technology (MACT). Section
112(b), however, lists 188 hazardous air pollutants (HAPs) for
potential regulation, and section 112(c)(6) requires EPA to establish
performance standards under section 112(d) for categories of sources
emitting seven specific pollutants, including the following HAPs
emitted by cement kilns: mercury and dioxins/dibenzofurans [42 U.S.C.
7412]. By comparison, section 129 expressly requires EPA to regulate
emissions of the following criteria pollutants and HAPs--particulate
matter, opacity (as appropriate), sulfur dioxide, hydrogen chloride,
nitrogen oxides, carbon monoxide, lead, cadmium, mercury, and dioxins
and dibenzofurans [42 U.S.C. 7429(a)(4)]. Section 129 also gives EPA
the discretion to promulgate emission limitations or provide for the
monitoring of postcombustion concentrations of surrogate substances or
any other pollutant not expressly listed for regulation in section
129(a)(4). [See 42 U.S.C. 7429(a)(4).] In addition, section 129
contains other requirements not contained in section 112, such as
operator training requirements. [See 42 U.S.C. 7429(d).]
As stated previously, the regulations being proposed today are
pursuant to section 112 of the Act and apply to all cement kilns except
portland cement kilns and in-line kiln/raw mills that would be subject
to the NESHAP for hazardous waste combustors. In today's notice, the
EPA is proposing to establish emission limitations for particulate
matter (as a surrogate for metals, except mercury), dioxins/furans, and
total hydrocarbons (as a surrogate for organic HAPs) regardless of the
material being combusted in the cement kiln. If EPA determines that
additional regulations are required under section 129 for cement kilns
that combust solid waste materials (e.g., cement kilns combusting
materials containing more than 30-percent municipal solid waste or
cement kilns combusting medical waste), then such regulations will be
promulgated under section 129 and EPA will state clearly in the
applicability section of those regulations when those standards apply
and revise the applicability section of these regulations accordingly.
At no time, will a cement kiln be expected to comply simultaneously
with regulations promulgated pursuant to section 112 and regulations
promulgated pursuant to section 129. Section 129(h)(1) expressly states
that no solid waste incineration unit subject to performance standards
under section 129 and section 111 shall be subject to standards under
section 112(d) of the Act [42 U.S.C. 7429(h)(1)]. The EPA reads this
provision to mean that for emissions potentially subject to section
129, the Agency must elect whether to cover such emissions under that
section, or under section 112. If EPA elects to cover emissions under
section 129, those emissions must be excluded from regulation under
section 112. For example, if a cement kiln combusts only fossil fuels,
it would have to comply with the regulations being proposed today. If
the kiln combusts a mixture of 50% coal and 50% non-hazardous solid
waste, it would continue to comply with the regulations being proposed
today until EPA promulgates regulations applicable to such kilns under
section 129 of the Act. At that time, if the kiln is burning the 50%
coal and 50% solid waste mixture, it would have to comply with the
section 129 regulations as long as it continued to combust solid waste
material. Thus, in the same way that installation of a particular type
of combustion device determines which regulation is applicable,
combustion of certain materials in that combustion device would
determine whether the section 112 regulation or section 129 regulation
is applicable.
The EPA does not believe that this approach will subject cement
kiln owners to duplicative regulations. As noted earlier, regulations
under section 112 and section 129 are based on MACT. If EPA determines
that additional regulations under section 129 are appropriate because
cement kilns are combusting solid waste material, EPA would be required
to promulgate additional MACT standards for the following pollutants
pursuant to section 129(a)(4): opacity, sulfur dioxide, hydrogen
chloride, nitrogen oxides, carbon monoxide, lead, cadmium, and mercury.
The EPA also would determine whether the standards for particulate
matter, total hydrocarbon, and dioxins/furans should be revised for
kilns combusting solid waste materials [42 U.S.C. 7429(a)(4)].
B. Emission Limits and Requirements
The proposed NESHAP for portland cement manufacturing would apply
to both major and area sources of HAPs.
[[Page 14187]]
The affected sources for which emission limits are proposed include the
kiln, in-line kiln/raw mill, clinker cooler, raw material dryer, and
materials handling processes that include the raw mill, finish mill,
raw material storage, clinker storage, finished product storage,
conveyor transfer points, bagging and bulk loading and unloading
systems (hereafter referred to as materials handling processes).
The proposed NESHAP would limit emissions of HAPs from non-
hazardous waste (NHW) portland cement kilns, NHW in-line kiln/raw
mills, and NHW kiln alkali bypasses. Kiln emission limits would not
apply to kilns or in-line kiln/raw mills that will be subject to the
NESHAP for various hazardous waste combustor (HWC) types, including
cement kilns which burn hazardous waste.2
---------------------------------------------------------------------------
\2\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
The kiln emission limits would apply to the kiln and in-line kiln/
raw mill gases and to kiln alkali bypass gases (which may or may not be
discharged through a separate stack).
The proposed rule would limit emissions of HAPs from raw material
dryers, clinker coolers and materials handling processes, regardless of
the type of fuel burned in the kiln. The proposed rule would limit PM
(surrogate for non-volatile HAP metals) emissions from new and existing
NHW kilns, NHW in-line kiln/raw mills, and clinker coolers at portland
cement plants which are major sources. Particulate matter emitted from
portland cement manufacturing contains quantities of metal HAPs such as
compounds of arsenic, cadmium, chromium, lead, manganese, mercury,
nickel, and selenium. Controlling PM emissions would also control
emissions of HAP metals. A surrogate approach is used for particulate
metal HAPs in the proposed NESHAP to allow easier and less expensive
measurement, analysis, and monitoring requirements, and because the
control techniques for non-volatile metal HAPs are the same as the
control techniques for PM. Although trace amounts of mercury may be
found in the particulate matter, it is generally considered a volatile
metal, and appreciable reductions of mercury emissions are not expected
through the use of PM controls. Opacity limits would also apply to NHW
kilns, NHW in-line kiln/raw mills, clinker coolers, raw material
dryers, and materials handling processes.
The proposed rule also would limit D/F emissions from new and
existing NHW kilns and NHW in-line kiln/raw mills located at portland
cement plants which are major or area sources of HAPs. In addition, the
rule would limit total hydrocarbon (THC) as a surrogate for organic HAP
emissions from new NHW kilns, new NHW in-line kiln/raw mills, and new
raw material dryers at portland cement plants which are major sources.
Kiln, in-line kiln/raw mill, and raw material dryer organic emissions
contain various organic HAPs including, but not limited to,
acetaldehyde, benzene, formaldehyde, hexane, naphthalene, styrene,
toluene, and xylenes. Tables 2 and 3 present a summary of the proposed
emission limits for new and existing portland cement affected sources.
Table 2.--Summary of Proposed Emission Limitsa for Affected Sources at
Portland Cement Plants
[Metric units]
------------------------------------------------------------------------
Affected source and Emission limit for Emission limit for
pollutant existing sources new sources
------------------------------------------------------------------------
NHW kiln and NHW in-line 0.15 kg/Mg dry feedd 0.15 kg/Mg dry feedd
kiln/raw mill b PM. and opacity levelb and opacity levelb
no greater than 20 no greater than 20
percent. percent.
NHW kiln and NHW in-line 0.2 ng TEQ/dscm or 0.2 ng TEQ/dscm or
kiln/raw mill D/F b, c. 0.4 ng TEQ/dscm 0.4 ng TEQ/dscm
with PM control with PM control
device operated at device operated at
204 deg. 204 deg.
C. C.
NHW kiln and NHW in-line None................ 50 ppmvd (as
kiln/raw mill THC. propane).
Clinker cooler PM........... 0.05 kg/Mg dry feed 0.05 kg/Mg dry feed
and opacity level and opacity level
no greater than 10 no greater than 10
percent. percent.
Raw material dryer and 10 percent opacity.. 10 percent opacity.
materials handling
processes (raw mill system,
finish mill system, raw
material storage, clinker
storage, finished product
storage, conveyor transfer
points, bagging, and bulk
loading and unloading
systems) PM.
Raw material dryer THC...... None................ 50 ppmvd (as
propane).
------------------------------------------------------------------------
a All concentration limits at 7 percent oxygen.
b Includes main and alkali bypass stacks.
c Applies to both major and area source portland cement plants.
d If there is an alkali bypass stack associated with the kiln or in-line
kiln/raw mill, the combined PM emission from the kiln or in-line kiln/
raw mill and the alkali bypass must be less than 0.15 kg/Mg dry feed.
Table 3.--Summary of Proposed Emission Limits a for Affected Sources at
Portland Cement Plants
[English Units]
------------------------------------------------------------------------
Affected source and Emission limit for Emission limit for
pollutant existing sources new sources
------------------------------------------------------------------------
NHW kiln and NHW in-line 0.30 lb/ton dry feed 0.30 lb/ton dry feed
kiln/raw mill b PM. d and opacity level d and opacity level
b no greater than b no greater than
20 percent. 20 percent.
NHW kiln and NHW in-line 8.7 x 10-11 gr TEQ/ 8.7 x 10-11 gr TEQ/
kiln/raw mill D/F b, c. dscf or 1.7 x 10-10 dscf or 1.7 x 10-10
gr TEQ/dscf with PM gr TEQ/dscf with PM
control device control device
operated at 400 deg.F. eq>400 deg.F.
NHW kiln and NHW in-line None................ 50 ppmvd (as
kiln/raw mill THC. propane).
Clinker cooler PM........... 0.10 lb/ton dry feed 0.10 lb/ton dry feed
and opacity level and opacity level
no greater than 10 no greater than 10
percent. percent.
[[Page 14188]]
Raw material dryer and 10 percent opacity.. 10 percent opacity.
materials handling
processes (raw mill system,
finish mill system, raw
material storage, clinker
storage, finished product
storage, conveyor transfer
points, bagging, and bulk
loading and unloading
systems) PM.
Raw material dryer THC...... None................ 50 ppmvd (as
propane).
------------------------------------------------------------------------
a All concentration limits at 7 percent oxygen.
b Includes main and alkali bypass stacks.
c Applies to both major and area source portland cement plants.
d If there is an alkali bypass stack associated with the kiln or in-line
kiln/raw mill, the combined PM emission from the kiln or in-line kiln/
raw mill and the alkali bypass must be less than 0.30 lb/ton dry feed.
C. Performance Test and Compliance Provisions
A performance test would be required to demonstrate initial
compliance with each applicable numerical limit. Under the proposed
standard, the owner or operator would use EPA Method 5, ``Determination
of Particulate Emissions from Stationary Sources'' to measure PM
emissions from kilns, in-line kiln/raw mills and clinker coolers. These
tests would be repeated every 5 years. Kilns and in-line kiln/raw mills
equipped with alkali bypasses would be required to meet the particulate
standard based on combined emissions from the kiln exhaust and the
alkali bypass. Owners or operators of in-line kiln/raw mills would be
required to conduct a Method 5 performance test while the raw mill is
operating and a separate Method 5 performance test while the raw mill
is not operating. In conducting the Method 5 tests, a determination of
the particulate matter collected in the impingers (``back half'') of
the particulate sampling train would not be required.
The opacity exhibited during the period of the initial Method 5
performance test would be determined, if feasible, through the use of a
continuous opacity monitor (COM). Where the control device exhausts
through a monovent or where the use of a COM in accordance with the
installation specifications of EPA Performance Specification (PS)-1 of
appendix B to 40 CFR part 60, is not feasible, EPA Method 9, ``Visual
Determination of the Opacity of Emissions from Stationary Sources''
would be used. Where the control device discharges through a FF with
multiple stacks or an ESP with multiple stacks, the owner or operator
would have the option of conducting an opacity test in accordance with
Method 9, in lieu of installing a COM.
Under the proposed standard, the owner or operator would use EPA
Method 23, ``Determination of Polychlorinated Dibenzo-p-dioxins and
Polychlorinated Dibenzofurans from Stationary Sources'' to measure D/F
emissions from kilns and in-line kiln/raw mills. These tests would be
repeated every 5 years. The temperature at the inlet to the PMCD during
the period of the Method 23 performance test would be continuously
recorded. If carbon injection is used for D/F control the carbon
injection rate during the period of the Method 23 performance test
would be monitored. Owners or operators of in-line kiln/raw mills would
be required to conduct a Method 23 performance test, and monitor the
temperature at the inlet to the PMCD while the raw mill is operating,
and a separate Method 23 performance test and inlet temperature
monitoring while the raw mill is not operating. If applicable, the
carbon injection rate would be monitored during both performance tests.
Where applicable, the exhausts from both the kiln or in-line kiln/raw
mill and the alkali bypass would be required to meet the D/F standard.
Under the proposed standard, the owner or operator would use a THC
continuous emission monitor (CEM) to continuously measure THC emissions
from new or reconstructed kilns, new or reconstructed in-line kiln/raw
mills, and new raw material dryers. Owners or operators of new or
reconstructed in-line kiln/raw mills would be required to demonstrate
initial compliance by measuring THC emissions while the raw mill is
operating and while the raw mill is not operating. The proposed
standard for THC does not apply to the exhaust from the alkali bypass
of kilns or in-line kiln/raw mills. Each THC CEM would be required to
be designed, installed, and operated in accordance with EPA Performance
Specification (PS)-8A of 40 CFR part 60, appendix B. 3
---------------------------------------------------------------------------
\3\ The EPA proposed amendments to appendix B of 40 CFR part 60
on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
Under the proposed standard, the owner or operator would use EPA
Method 9, ``Visual Determination of the Opacity of Emissions from
Stationary Sources'' to measure the opacity of gases discharged from
raw mills, finish mills, raw material dryers and materials handling
processes. These tests would be repeated every five years. A summary of
proposed compliance and monitoring options is given in Table 4.
Table 4.--Summary of Proposed Compliance Demonstration and Monitoring
Requirements
------------------------------------------------------------------------
Affected source and Compliance Monitoring
pollutant demonstration requirement
------------------------------------------------------------------------
New and existing NHW kiln EPA Method 5 a...... COM if feasible d, e
and NHW in-line kiln/raw or daily EPA Method
mill b, c PM. 9 visual opacity
readings.
New and existing NHW kiln EPA Method 23 a..... Monitor temperature
and NHW in-line kiln/raw at inlet to PM
mill b, c, h, i D/F. control device f
and minimum carbon
injection rate if
activated carbon
injection is used.
[[Page 14189]]
New NHW kiln and NHW in-line THC CEM (EPA PS-8A) THC CEM (EPA PS-8A)
kiln/raw mill THC. j. j
New and existing clinker EPA Method 5 a...... COM d, g or daily
cooler PM. EPA Method 9 visual
opacity readings.
New and existing raw and EPA Method 9 a, g... Daily EPA Method 22
finish mill PM. visual opacity
readings or
operation of bag
break detectors.
New and existing raw EPA Method 9 a, g... None.
material dryer and
materials handling
processes (raw mill system,
finish mill system, raw
material storage, clinker
storage, finished product
storage, conveyor transfer
points, bagging, and bulk
loading and unloading
systems) PM.
New raw material dryer THC.. THC CEM (EPA PS-8A) THC CEM (EPA PS-8A)
j. j
------------------------------------------------------------------------
a Required initially and every 5 years thereafter.
b Includes main exhaust and alkali bypass.
c In-line kiln/raw mill to be tested with and without raw mill in
operation.
d Must meet COM performance specification criteria. If the fabric filter
or electrostatic precipitator has multiple stacks, daily EPA Method 9
visual opacity readings may be taken instead of using a COM.
e Opacity limit is 20 percent. Corrective action trigger is 15 percent.
f Site-specific temperature limit at APCD inlet is established during
successful D/F emissions testing.
g Opacity limit is 10 percent.
h Alkali bypass is tested with the raw mill on.
i Temperature parameters determined separately with and without the raw
mill operating.
j EPA Performance Specification (PS)-8A. Proposed on April 19, 1996 at
61 FR 17358.
D. Monitoring Requirements
The proposed rule requires owners or operators to monitor the
opacity of gases discharged from kilns, in-line kiln/raw mills, alkali
bypasses and clinker coolers using a COM, if a COM can be feasibly
installed in accordance with PS-1 of appendix B to 40 CFR part 60.
Where it is not feasible to install a COM, e.g., where the control
device discharges through a monovent, the owner or operator would be
required to monitor emissions by conducting daily Method 9 tests. Where
the control device discharges through an FF with multiple stacks or an
ESP with multiple stacks, the owner or operator would have the option
of conducting daily tests in accordance with Method 9, in lieu of
installing a COM. The duration of the Method 9 tests would be 30
minutes. Owners or operators would also be required to determine kiln
or in-line kiln/raw mill feed rate.
The opacity limit for kilns and in-line kiln/raw mills would be 20
percent. Any 30-minute average opacity reading greater than 20 percent
determined by the COM or daily Method 9 test would be a violation of
the standard. Any ten consecutive 30-minute average COM readings
exceeding 15 percent, or any single 30-minute average Method 9 reading
exceeding 15 percent would trigger a site-specific operating and
maintenance plan, incorporated within the owner or operator's part 70
permit. The owner or operator would be required to initiate the site-
specific operating and maintenance plan within one hour. If the opacity
exceeds 15 percent for five percent of the operating time as determined
by 30-minute average COM readings, or if the 30-minute average readings
exceed 15 percent during five percent of the daily Method 9 tests,
during any 180 day reporting period, the owner or operator would be
required to develop and implement a quality improvement plan (QIP)
consistent with subpart D of the draft approach to compliance assurance
monitoring.4 The owner or operator would be required to
implement the QIP as expeditiously as possible but in no case would the
period for completing the implementation of the plan exceed 180 days.
If the owner or operator determined that more than 180 days was
required to complete the appropriate improvements, the owner or
operator would be required to notify the permitting authority and
obtain a site-specific resolution subject to the approval of the
permitting authority.
---------------------------------------------------------------------------
\4\ The EPA announced its intention to propose subpart D of 40
CFR part 64 on August 13, 1996 at 61 FR 41991.
---------------------------------------------------------------------------
The opacity limit for clinker coolers would be 10 percent, based on
any 30-minute average COM or Method 9 reading.
The proposed rule requires the owner or operator to monitor D/F
emissions from kilns and in-line kiln/raw mill systems and to maintain
the temperature at the inlet to the PMCD at a level no greater than
either: (1) the higher of 400 deg.F or the level established during
the successful Method 23 performance test plus five percent (not to
exceed 25 deg.F) of the temperature measured in deg.F during the
successful compliance test, if D/F emissions were determined to be no
greater than 0.15 ng toxic equivalent (TEQ)/dscm (6.5 x
10-11 gr/dscf); (2) the higher of 400 deg.F or the level
established during the successful Method 23 performance test, if D/F
emissions were determined to be greater than 0.15 ng TEQ/dscm (6.5 x
10-11 gr/dscf) but less than 0.2 ng TEQ/dscm (8.7 x
10-11 gr/dscf); or (3) 400 deg.F if D/F emissions were
greater than 0.2 ng TEQ/dscm (8.7 x 10-11 gr/dscf) but
less than or equal to 0.4 ng TEQ/dscm (1.7 x 10-10 gr/
dscf).
Owners or operators of in-line kiln/raw mills would be required to
establish separate PMCD inlet temperatures applicable to periods when
the raw mill is operating and periods when the raw mill is not
operating. The appropriate ``raw mill operating status dependent'' PMCD
inlet temperature could not be exceeded. Owners or operators of kilns
or in-line kiln/raw mills equipped with alkali bypasses would be
required to establish separate temperatures for the inlet to the kiln
or in-line kiln raw mill exhaust PMCD and the kiln or in-line kiln
alkali bypass PMCD.
If carbon injection is used for D/F control, the carbon injection
rate would be monitored, and maintained at a level equaling or
exceeding the rate which existed during the successful Method 23
performance test.
The proposed rule requires the owner or operator to monitor THC
emissions from the main exhaust of new and reconstructed kilns; the
main exhaust of new and reconstructed in-line kiln/raw mills; and new
and reconstructed raw
[[Page 14190]]
material dryers using a CEM installed in accordance with PS-8A in 40
CFR part 60, appendix B.5
---------------------------------------------------------------------------
\5\ The EPA proposed amendments to appendix B of 40 CFR part 60
on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
The proposed rule requires the owner or operator to monitor the
opacity from raw mills and finish mills either by conducting a daily
six-minute test in accordance with Method 22, ``Visual Determination of
Fugitive Emissions from Material Sources and Smoke Emissions from
Flares'', or by installing, calibrating, operating and maintaining a
bag break detection system. In the event that fugitive emissions are
observed during the Method 22 test, the owner or operator would be
required to conduct a 30-minute Method 9 test commencing within 24
hours of the end of the Method 22 test. In addition, the owner or
operator would be required to initiate, within one hour, a site-
specific operating and maintenance plan developed as part of the
application for a part 70 permit.
In the event that the bag break detection system alarm were
triggered, the owner or operator would be required to initiate, within
one hour, a site-specific operating and maintenance plan developed as
part of the application for a part 70 permit.
As required by the NESHAP general provisions (40 CFR part 63,
subpart A), the owner or operator also must develop and implement a
startup, shutdown, and malfunction plan.
E. Notification, Recordkeeping, and Reporting Requirements
All notification, recordkeeping, and reporting requirements in the
general provisions (40 CFR part 63, subpart A) would apply to portland
cement manufacturing plants. These include: (1) Initial notification(s)
of applicability, notification of performance test, and notification of
compliance status; (2) a report of performance test results; (3) a
startup, shutdown, and malfunction plan with semiannual reports of
reportable events (if they occur); and (4) semiannual reports of excess
emissions. If excess emissions are reported, the owner or operator
would report quarterly until a request to return the reporting
frequency to semiannual is approved.
Owners and operators would also be required to prepare an operation
and maintenance plan for kiln, in-line kiln/raw mill, raw mill and
finish mill APCDs consistent with subpart D of the draft approach to
compliance assurance monitoring (CAM).6 The operation and
maintenance plan would become part of their operating permit required
by 40 CFR part 70.
---------------------------------------------------------------------------
\6\ The EPA announced its intention to propose subpart D of 40
CFR part 64 on August 13, 1996 at 61 FR 41991.
---------------------------------------------------------------------------
Under circumstances described in section III. D. of this preamble,
kiln and in-line kiln/raw mill monitoring may trigger a requirement to
prepare and implement a site-specific Quality Improvement Program
(QIP), that will also be consistent with the draft CAM
rule.7 Owners or operators would be required to report if a
QIP were required, and to notify the permitting authority if a required
QIP would take more than 180 days to implement.
---------------------------------------------------------------------------
\7\ The EPA announced its intention to propose subpart D of 40
CFR 64 on August 13, 1996 at 61 FR 41991.
---------------------------------------------------------------------------
The NESHAP general provisions (40 CFR part 63, subpart A) require
that records be maintained for at least 5 years from the date of each
record. The owner or operator must retain the records onsite for at
least 2 years but may retain the records offsite the remaining 3 years.
The files may be retained on microfilm, microfiche, on a computer disk,
or on magnetic tape. Reports may be made on paper or on a labeled
computer disk using commonly available and compatible computer
software.
IV. Impacts of Proposed Standards
A. Applicability
The EPA estimates that there are currently 118 portland cement
plants in the United States. All portland cement plants would be
subject to the proposed standards. The following sources would be
affected when located at a portland cement plant that is a major
source:
(1) New, reconstructed, and existing NHW kilns and NHW in-line
kiln/raw mills including alkali bypasses that are not subject to the
HWC NESHAP 8 would be subject to emission limits for PM, D/
F, and opacity;
---------------------------------------------------------------------------
\8\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
(2) New and reconstructed NHW kiln main exhausts and new and
reconstructed NHW in-line kiln/raw mills main exhausts, that are not
subject to the HWC NESHAP,9 would be subject to an emission
limit for THC;
---------------------------------------------------------------------------
\9\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
(3) New and reconstructed raw material dryers would be subject to
an emission limit for THC;
(4) New, reconstructed, and existing clinker coolers would be
subject to emission limits for PM and opacity; and
(5) New, reconstructed, and existing raw material dryers, raw and
finish mills, and material handling processes would be subject to an
opacity limit.
The following sources would be affected when located at a portland
cement plant that is an area source: new, reconstructed, and existing
NHW kilns and NHW in-line kiln/raw mills, including alkali bypasses,
that are not subject to the HWC NESHAP,10 would be subject
to emission limits for D/F.
---------------------------------------------------------------------------
\10\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
B. Air Quality Impacts
Nationwide baseline HAP emissions from portland cement
manufacturing plants are estimated to be 260 Mg/yr (290 tpy) at the
current level of control. The proposed standards would reduce emissions
of HAPs by 82 Mg/yr (90 tpy) from baseline levels. Estimates of annual
emissions of HAPs and expected reductions from implementation of the
proposed standards are given in metric and English units in Tables 5
and 6 (docket item II-B-76, docket item II-B-77). The following text
reviews the information provided in Tables 5 and 6.
Table 5.--Nationwide Annual Emissions of HAPS and Other Pollutants From Portland Cement Manufacturing Plants
[Metric units]
----------------------------------------------------------------------------------------------------------------
Baseline emissions (Mg/ Emission reduction
Source Pollutant yr) (Mg/yr)
----------------------------------------------------------------------------------------------------------------
Kilns, in-line kiln/raw mills, and HAP Metals a............... 150................... 35.
alkali bypasses.
PM a....................... 14,000................ 3,400.
D/F (TEQ) b................ 44 g/yr............... 16 g/yr.
Organic HAPs c............. 120................... 47.
THC c...................... 530................... 200.
[[Page 14191]]
Clinker coolers.................... HAP Metals a............... 1.1................... 0.18.
PM a....................... 8,100................. 1,300.
----------------------------------------------------------------------------------------------------------------
a These numbers pertain to existing sources only.
b These numbers pertain to both new and existing NHW kilns.
c These numbers pertain to new NHW kilns only.
Table 6.--Nationwide Annual Emissions of HAPS and Other Pollutants From Portland Cement Manufacturing Plants
[English units]
----------------------------------------------------------------------------------------------------------------
Baseline emissions Emission reduction
Source Pollutant (tpy) (tpy)
----------------------------------------------------------------------------------------------------------------
Kilns, in-line kiln/raw mills, and HAP Metalsa................ 160................... 38.
alkali bypasses.
PMa........................ 16,000................ 3,800.
D/F (TEQ)b................. 0.096 lbs/yr.......... 0.035 lbs/yr.
Organic HAPsc.............. 130................... 52.
THCc....................... 580................... 220.
Clinker coolers.................... HAP Metalsa................ 1.2................... 0.2.
PMa........................ 8,800................. 1,400.
----------------------------------------------------------------------------------------------------------------
a These numbers pertain to existing sources only.
b These numbers pertain to both new and existing NHW kilns.
c These numbers pertain to new NHW kilns only.
The proposed MACT standards would reduce PM emissions from the
existing NHW cement kilns and in-line kiln/raw mills by 3,400 Mg/yr
(3,800 tpy) from the baseline level, a reduction of 24 percent.
Emissions of HAP metals from the affected existing NHW cement kilns and
in-line kiln/raw mills would be reduced by 35 Mg/yr (38 tpy), a
reduction of 24 percent from the baseline level. Emissions of D/F TEQ
would be reduced by 15 grams (g)/yr (0.033 lb/yr), a reduction of 36
percent from the baseline level, at existing NHW cement kiln and in-
line kiln/raw mills.
For new NHW cement kilns and in-line kiln/raw mills, the MACT
standards are projected to reduce emissions of D/F TEQ by an average of
0.6 g/yr (0.001 lb/yr) over the next 5 years (from major and area
sources), a 36 percent reduction from projected baseline emissions. For
new kilns, the proposed standards would also reduce projected emissions
of THC by an average of 200 Mg/yr (220 tpy) and organic HAPs by an
average of 47 Mg/yr (52 tpy) over the next 5 years, an emissions
reduction for each of 39 percent from corresponding estimated
nationwide baseline emissions (docket item II-B-76).
The proposed MACT standards would reduce PM emissions from 35
percent of the existing clinker coolers by 1,300 Mg/yr (1,400 tpy) from
the baseline level, a reduction of 16 percent. Emissions of HAP metals
from the affected existing clinker coolers would be decreased by 0.18
Mg/yr (0.2 tpy), a reduction of 16 percent from the baseline level.
Additional reductions of THC and organic HAPs will result from the
MACT standards for new raw material dryers. However, information on THC
emission rates from raw material dryers and the number of such affected
sources is not currently available, so nationwide reductions cannot be
estimated.
The MACT standards would also reduce PM emissions from raw material
dryers, and other material handling processes. However, no impacts were
estimated for these affected sources because there is no available
information on typical PM emissions from the affected sources that do
not meet the NSPS, and no information on the number of sources
potentially affected by this MACT standard.
C. Water Impacts
Control of D/F emissions using water injection for temperature
reduction would result in an estimated increased water consumption
(evaporated into the kiln exhaust gas for cooling) of 190 million
gallons per year for existing NHW kilns and NHW in-line kiln/raw mills
of 8 million gallons per year for new NHW kilns and NHW in-line kiln/
raw mills (docket item II-B-77).
D. Solid Waste Impacts
The amount of solid waste from existing NHW kilns, in-line kiln/raw
mills, and clinker coolers (located at major sources) would increase by
an estimated 4,700 Mg/yr (5,200 tpy) due to the proposed standard for
PM control (docket item II-B-77).
E. Energy Impacts
For existing NHW kilns and NHW in-line kiln/raw mills the proposed
MACT standards for PM and D/F would increase energy consumption by an
estimated 11 million kilowatt hours (KWh)/yr [38 billion British
thermal units (Btu)/yr]. For new NHW kilns and NHW in-line kiln/raw
mills the proposed MACT standards for D/F would increase energy
consumption by an estimated (docket item II-B-77) 10,600 KWh/yr (36
million Btu/yr).
F. Nonair Health and Environmental Impacts
The reduction in HAP emissions would have a beneficial effect on
nonair health and environment impacts. D/F and HAP metals have been
found in the Great Lakes and have been listed as pollutants of concern
due to their persistence in the environment, potential to
bioaccumulate, and toxicity to humans and the environment (docket item
II-A-31, pp. 18 to 21). Implementation of the proposed
[[Page 14192]]
NESHAP would aid in reducing aerial deposition of these emissions.
Occupational exposure limits under 29 CFR part 1910 are in place
for some of the regulated HAPs (and surrogates) except D/F. The
National Institute for Occupational Safety and Health recommends an
exposure level for D/F at the lowest feasible concentration (docket
item II-I-45, p. 124). The proposed NESHAP would reduce emissions, and
consequently, occupational exposure levels for plant employees.
G. Cost Impacts
For existing NHW kilns, NHW in-line kilns/raw mills, clinker
coolers, raw and finish mills, and materials handling facilities, the
projected total capital costs (including estimated monitoring costs) of
the proposed standard for controlling emissions of PM and D/F are $87
million. The projected annual costs (including monitoring costs) for
these controls are $27 million. For new NHW kilns and NHW in-line kiln/
raw mills, the projected total capital and annual costs of the MACT
standard for D/F are $390,000 and $89,000, respectively. No capital and
annual costs are projected for new and reconstructed NHW kilns, NHW in-
line kilns/raw mills, and clinker coolers as a result of the proposed
standard for PM because these sources will be required to comply with
the existing NSPS for portland cement plants (40 CFR part 60, subpart
F). The proposed THC emissions limit for new NHW kilns and NHW in-line
kiln/raw mills can be met by processing materials with typical levels
of organic content, without installing and operating add-on pollution
control systems that would be relatively costly. Feed materials that
have sufficiently low levels of organic matter are widespread across
the U.S., and the siting of new kilns is not expected to be
significantly limited by the proposed emission limit. Information is
not available to quantify the costs of excluding deposits of feed
materials with the highest levels of organic constituents as the
primary feed for new kilns. Owners/operators of the few existing cement
plants that process feed materials containing relatively high levels of
organic material, and who desire to expand production through the
addition of a new kiln, would need to blend their existing feed
materials with lower THC materials from offsite, or selectively process
lower organic portions of the feed materials from the onsite mine or
quarry in the new kiln. Regarding the costs of monitoring, for new NHW
kilns and in-line kiln/raw mills, the projected fifth-year national
capital and annual costs of monitoring THC with a continuous emission
monitor at an estimated four new kilns are $576,000 and $340,000,
respectively (docket item II-B-77).
H. Economic Impacts
An economic analysis of the proposed NESHAP was conducted. The EPA
estimates that regional market price increases would be between 0.6 and
2.0 percent. The national average price increase is estimated to be 1.1
percent. The related decreases in quantity demanded are estimated to
range from 0.5 to 1.8 percent, with a national average of 0.9 percent.
Domestic production is estimated to decrease more than consumption (1.7
percent compared to 0.9 percent nationally because imports are
estimated to increase by 6.3 percent). The decreases in domestic
production may lead to the loss of approximately 230 jobs. No plants
are expected to close; two kilns are expected to cease operating
(docket item II-A-46).
V. Selection of Proposed Standards
A. Selection of Source Category
Section 112(c) of the Act directs the Agency to list each category
of major and area sources, as appropriate, that emits one or more of
the HAPs listed in section 112(b) of the Act. The EPA published an
initial list of source categories on July 16, 1992 (57 FR 31576), and
revised the list on June 4, 1996 (61 FR 28197). ``Portland Cement
Manufacturing'' is one of the 174 categories of sources on the initial
list. As defined in the EPA report, ``Documentation for Developing the
Initial Source Category List'' (docket item II-A-18), the Portland
Cement Manufacturing source category includes any facility engaged in
manufacturing portland cement by either the wet or dry process. The
category as described for the listing includes but is not limited to
the following process facilities: kiln, clinker cooler, raw mill
system, finish mill system, raw material dryer, raw material storage,
clinker storage, finished product storage, conveyor transfer points,
bagging, and bulk loading and unloading systems.
The term ``major source'' is defined under section 112(a)(1) of the
Act and in the EPA general provisions (40 CFR 63.2) as:
* * * any stationary source or group of stationary sources
located within a contiguous area under common control that emits or
has the potential to emit considering controls, in the aggregate, 10
tons per year or more of any hazardous air pollutant or 25 tons per
year or more of any combination of hazardous air pollutants * * *
This definition of major source has been upheld in a recent decision,
National Mining Ass'n v. EPA, 59 F.3d 1351 (D.C. Cir. 1995). In this
case, the Court also concluded that ``EPA may require the inclusion of
fugitive emissions in a site's aggregate emissions without conducting
any special rule making'' for the purpose of determining whether a
source is major.
The listing of the portland cement major source category was based
on the Administrator's determination that some portland cement plants
would be major sources of particulate HAPs, including but not limited
to compounds of arsenic, cadmium, chromium, lead, manganese, mercury,
nickel, and selenium. Information and data have been compiled by the
EPA characterizing the portland cement manufacturing process and its
associated emission sources. There are three main steps to
manufacturing portland cement: (1) kiln feed preparation (i.e.,
crushing and grinding), (2) firing the raw mix in a rotary kiln to
produce clinker (including fuel handling), and (3) clinker grinding to
produce cement. The responses received from the information collection
request (ICR) that was sent to every company in the industry indicated
that HAP emissions have been identified from all steps in the
manufacturing process. The kiln feed preparation and clinker grinding
operations all produce particulate emissions, a fraction of which are
metal HAPs. The responses also showed that HAPs are emitted from the
clinker production step; the kiln exhaust gases contain metal HAPs,
organic HAPs, and HCl.
All kiln exhaust gases are controlled at the existing plants by
either FFs or ESPs to limit PM emissions. Based on currently available
data, there are no plants that would be defined as major sources
according to section 112(a) of the Act on the basis of the mass of
metal HAPs emitted from kilns. That is, the reported emissions,
considering controls, did not exceed 9.1 Mg/yr (10 tpy) of a single
metal HAP or greater than 22.7 Mg/yr (25 tpy) of a combination of metal
HAPs from a cement kiln. However, operators of portland cement plants
must include HAP emissions from fugitive sources in determining whether
their facility is a major source of HAP emissions. Fugitive sources may
emit enough HAP metals to make a plant a major source (when fugitive
emissions are combined with all other HAP emissions at the site).
ICR responses for individual plants did show quantities of hydrogen
chloride (HCl) and chlorine each being emitted in excess of 9.1 Mg/yr
(10 tpy).
[[Page 14193]]
Most HCl emissions (reported in the ICR responses) were measured by EPA
Method 26, a method that may underestimate HCl emissions by a factor of
2 to 25 (docket item II-I-121). Results of Fourier Transform Infrared
(FTIR) spectroscopy emissions tests suggest that most plants may be
major sources of HCl. Hydrochloric acid concentrations of two wet
process portland cement kiln exhaust gases (docket item II-A-20, docket
item II-A-40) determined by FTIR spectroscopy ranged from 11 parts per
million by volume (ppmv) to 110 ppmv (dry basis corrected to 7 percent
oxygen). Assuming an average HCl emission of 50 ppmv (dry basis,
corrected to 7 percent oxygen), a wet kiln producing 600,000 tpy of
clinker would emit approximately 150 tpy of HCl.
Some plants reported formaldehyde, benzene, and toluene emissions
each to be in excess of 9.1 Mg/yr (10 tpy). One plant injects activated
carbon into the kiln exhaust to reduce the plume opacity thought to be
caused by hydrocarbons in the feed (docket item II-B-35). Various
organic HAPs were detected in its kiln exhaust using FTIR spectroscopy
(docket item II-A-41). Based on the kiln operating 330 d/yr, 24 hr/d,
kiln emissions were estimated at 331 Mg/yr (365 tpy) of hexane, 29 Mg/
yr (32 tpy) of benzene, 27 Mg/yr (30 tpy) of toluene, 15 Mg/yr (16 tpy)
of naphthalene, and 12 Mg/yr (13 tpy) chlorobenzene (docket item II-A-
41, docket item II-B-76).
Based on ICR responses, acetaldehyde, acrylonitrile, arsenic
compounds, lead compounds, manganese compounds, mercury compounds,
naphthalene, phosphorus, styrene, and xylenes were emitted at rates of
one tpy or greater from at least one portland cement kiln (docket item
II-B-69). The analysis of HAP emissions data from portland cement
manufacturing plants summarized above indicates that most if not all
cement plants are major sources of HAP emissions.
Consideration of subcategories or classes. Section 112(d)(1) of the
Act provides that the Administrator may distinguish among classes,
types and sizes of sources within a category or subcategory in
establishing standards. The EPA reviewed the listed source category to
determine if different classes were warranted. All portland cement is
manufactured in direct-fired, rotating kilns. In 1993, 210 kilns at 118
plants were in operation throughout the nation and Puerto Rico (docket
item II-I-101).
There are two main portland cement manufacturing processes
differentiated on the basis of feed preparation: wet process and dry
process. Approximately one-third of the kilns in operation use a wet
process; the other two-thirds use a dry process. The trend in the
industry for new kilns is toward the dry process because it is more
energy efficient than the wet process. Within the dry process there are
three variations: long kiln dry process, preheater process, and
preheater/precalciner process. The wet process kilns and all variations
of the dry process kilns use the same raw materials and use the same
types of pollution controls for PM emissions (docket item II-C-94,
attachment chapters 2 and 3). Based on ICR responses and test data the
use of these pollution controls to meet the NSPS for PM is feasible for
wet kilns and all types of dry kilns. Likewise test data show that
lowering kiln exhaust gas temperature to 400 deg. F at the APCD inlet,
MACT for reducing D/F concentrations, is feasible for wet and all types
of dry kilns. In any event, if classes were defined based on process
type, the MACT floor technology would be identical (docket item II-B-
73). For this reason, the EPA does not propose classes based on process
type.
The EPA OSW has recently proposed NESHAPs for various HWC types,
including cement kilns which burn hazardous waste.11 The
proposal is consistent with the terms of the 1993 settlement agreement
between the Agency and a number of groups that challenged EPA's final
RCRA rule entitled ``Burning of Hazardous Waste in Boilers and
Industrial Furnaces'' (56 FR 7134, February 21, 1991) and with the
Agency's Hazardous Waste Minimization and Combustion Strategy that was
first announced in May 1993. Hazardous waste burning cement kilns are
included in the portland cement manufacturing source category, but are
subject to different regulations than the NHW kilns. This proposed
NESHAP for portland cement manufacturing covers only NHW kilns and NHW
in-line kiln/raw mills. However, this proposed NESHAP does cover the
other affected sources (including clinker coolers, raw material dryers,
and materials handling processes) located at manufacturing plants
regardless of whether the plant has hazardous waste-burning cement
kilns.
---------------------------------------------------------------------------
\11\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
Decision to regulate portland cement area sources. Section
112(c)(6) of the Act states that by November 15, 2000, EPA must list
and promulgate section 112(d)(2) or (d)(4) standards (i.e., standards
reflecting MACT) for categories (and subcategories) of sources emitting
seven specific pollutants, including the following HAPs emitted by
cement kilns: mercury, 2,3,7-8 tetrachlorodibenzofuran, and 2,3,7-8
tetrachlorodibenzo-p-dioxin. (Although other 112(c)(6) HAPs have been
found in cement kiln exhaust, the majority of the emissions data and
concern for NHW cement kiln 112(c)(6) HAPs is for mercury and dioxin/
furans.) The EPA must assure that source categories accounting for not
less than 90 percent of the aggregated emissions of each enumerated
pollutant are subject to MACT standards. Congress (docket item II-I-13,
p. 155 to 156) singled out the HAPs enumerated in section 112(c)(6) as
being of ``specific concern'' not just because of their toxicity but
because of their propensity to cause substantial harm to human health
and the environment via indirect exposure pathways (i.e., from the air
through other media, such as water, soil, food uptake, etc.).
Furthermore, these pollutants have exhibited special potential to
bioaccumulate, causing pervasive environmental harm in biota (and,
ultimately, human health risks).
The EPA estimates that approximately five tons of mercury are
emitted annually in aggregate from NHW cement kilns at portland cement
plants in the U.S. (docket item II-B-65). Also, it is estimated that
NHW kilns emit in aggregate approximately 22 lb of D/F (or about 0.10
lb TEQ per year (docket item II-B-57, docket item II-B-76). To assure
that these pollutants are subject to MACT, EPA is proposing to add the
portland cement manufacturing area source category to the list of
source categories and subcategories listed pursuant to section
112(c)(6). [See 62 FR 33625, 33637-38; June 20, 1997.] The EPA is doing
so because area and major source cement kilns emit these HAPs in
roughly equal quantities, because the dioxins and furans emitted by
area sources are equally toxic as those emitted by major sources (i.e.,
the distribution of dioxin and furan isomers is the same for both area
and major sources), and because these are particularly toxic HAPs. In
addition, EPA is already counting on control of these pollutants from
cement kiln area sources through the MACT process in assuring that
sources accounting for at least 90 percent of the emissions of these
HAPs are subject to standards under section 112(c)(6). [See 62 FR at
33635, 33636; June 20, 1997.]
The EPA notes, however, as it did in the June 20th notice, that
although the section 112(c)(6) listing process makes sources subject to
standards under subsection (d)(2) or (d)(4), the language of section
112(c)(6) does not specify
[[Page 14194]]
either a particular degree of emissions control or a reduction in these
specific pollutants emissions to be achieved by such regulations.
Rather, the specific control requirements will result from determining
the appropriate level of control under MACT [section 112(d)(2), or
section 112(d)(4)], and this interpretation will be made during the
section 112(d) rulemakings affecting the particular source category,
not as part of the section 112(c)(6) listing process. [See 62 FR at
33631; June 20, 1997.]
As noted above, EPA is interpreting section 112(c)(6) to require
the Agency to establish standards under section 112(d)(2) or 112(d)(4)
for all sources listed pursuant to section 112(c)(6), whether such
sources are major or area sources. This interpretation reflects the
express language of section 112(c)(6) that sources * * * of each such
pollutant are subject to standards under subsection (d)(2) or (d)(4)
and is in accord with the function of section 112(c)(6):
To assure that sources emitting significant amounts of the most
dangerous HAPs are subject to the rigorous MACT standard-setting
process.
[See S. Rep. No. 228, 101st Cong. 1st Sess., pp. 155, 166.]
The EPA has in fact already adopted this interpretation in the
proposed rule for hazardous waste combustion sources.
[See 61 FR at 17365; April 19, 1996.]
Under an alternative interpretation of section 112(c)(6), the
Agency might also establish standards pursuant to section 112(d)(5)--
based on generally available control technology (GACT)--for area
sources listed under section 112(c)(6). Section 112(d)(5) states that
for categories and subcategories of area sources listed pursuant to
subsection 112(c), the Administrator may establish standards pursuant
to GACT rather than MACT. Although the reference to listing area
sources may have been intended to refer to the area source listing
process in section 112(c)(3), it arguably extends to listing under
section 112(c)(6) as well. The Agency requests comment on the use of
this alternative approach to standard-setting for area sources listed
under section 112(c)(6).
In addition, the EPA is interpreting section 112(c)(6) to require
that, for sources listed under section 112(c)(6), MACT [or section
112(d)(4)] controls apply only to the section 112(c)(6) HAPs emitted by
the source. Thus, in this proposed rule, only mercury, D/F, and POM
(using THC as a surrogate) emitted by cement kiln area sources would be
subject to the MACT standards. The EPA is aware that it proposed a
different interpretation in the hazardous waste combustion NESHAP (see
61 FR at 17365-66), but now believes that section 112(c)(6) is better
read to apply only to particular HAPs rather than to the entire source.
(Since the language of section 112(c)(6) is ambiguous as to whether the
entire source must comply with MACT, or just for the HAPs enumerated in
section 112(c)(6), [see 61 FR at 17365 n. 12], either interpretation is
legally permissible.) Applying the provision to the entire source could
result in applying MACT to all HAPs emitted by area sources under
circumstances where control would not otherwise be warranted.
B. Selection of Emission Sources
The portland cement manufacturing process consists of the following
unit operations:
(1) Grinding the carefully proportioned raw materials to a high
degree of fineness;
(2) firing the raw mix in a rotary kiln to produce clinker;
(3) grinding the resulting clinker to a fine powder and mixing with
gypsum to produce cement; and
(4) raw and finished materials handling.
The following sections include descriptions of the affected sources
in the portland cement manufacturing source category, the origin of
emissions from these affected sources, and factors affecting the
emissions. The affected sources for which MACT standards are being
proposed include the kiln, in-line kiln/raw mills, clinker cooler, raw
and finish mills, raw material dryer, and materials handling processes.
1. Feed Preparation Processes (Grinding, Conveying)
Oxides of calcium, silicon, aluminum, and iron comprise the basic
ingredients of cement. The calcareous raw materials include limestone,
chalk, marl, sea shells, aragonite, and an impure limestone known in
the industry as natural cement rock. The requisite silica and alumina
may be derived from clay or shale from a limestone quarry. Such
materials usually contain some of the required iron oxide, but many
plants need to supplement the iron with mill scale, pyrite cinders, or
iron ore. Silica is supplemented, if necessary by adding sand to the
raw mix; alumina may be supplemented by adding bauxite or alumina-rich
flint clays to the raw mix (docket item II-I-5, p. 180).
Industrial by-products and wastes are becoming more widely used as
feed materials for cement production, e.g., slags contain carbonate-
free lime, as well as substantial levels of silica and alumina. Fly ash
from coal-fired boilers can often be a suitable feed component, since
it is already finely dispersed and provides silica and alumina (docket
item II-I-5, p. 180).
Ball mills are used to grind the feed material to the required
fineness for both the wet and dry processes. In the wet-kiln process,
the raw materials are ground with water to produce a well-homogenized
slurry. In the dry-kiln process, raw materials are ground in closed-
circuit ball mills with air separators.
Emissions from the grinding and conveying operations are
essentially particulate emissions (e.g., dust from limestone, clay,
bauxite ore) which contain HAP metals. Particulate matter control
devices (FFs and ESPs) serve as HAP control devices. The quantity of
emissions of HAP metals from raw materials handling processes are site
specific and depend on dust control practices and weather conditions.
2. Feed Preparation Processes (Drying, Blending, Storage)
Drying of kiln feed materials can be carried out in separate units
that are gas-or coal-fired. However, to improve the process energy
efficiency, waste heat can be utilized directly in the mill by routing
the kiln gases through the raw mill. The catch from the APCDs that
follow the raw mill is returned to the process and therefore, the APCD
is also part of the process (docket item II-I-109, chapter 11.6). Where
kiln gases are routed through the raw mill, emissions from the combined
in-line kiln/raw mills must be controlled for the same pollutants and
to the same extent as kiln gases.
The more energy efficient preheater and preheater/ precalciner
kilns usually route the exhaust gas from the preheater to a raw mill to
dry the material in suspension in the mill. The gas stream exits the
raw mill heavily laden with kiln raw material and is exhausted to an
APCD to recover the raw material and any material entrained from the
kiln preheater system. The raw material is collected and fed to a
blending system to provide the kiln with a homogenous raw feed. Dry
process blending is usually accomplished in a silo with compressed air
(docket item II-I-5, p. 183).
If the raw material dryer uses heat from a separate combustion
source (fuel-fired raw material dryer), exhaust gases may contain trace
quantities of products of incomplete combustion (PICs), HCl, and metals
from the fuel. In addition, if the feed materials contain organic
matter, this material may volatilize in the raw material dryer
(regardless of the
[[Page 14195]]
source of the heat) and the dryer exhaust may contain organic HAPs.
Under the NSPS, emissions from the raw material dryer and the feed
preparation materials handling processes (raw mill system, raw material
storage, and conveyor transfer points) are currently subject to a limit
of 10 percent opacity.
3. Kiln
The high temperature processing required to produce portland cement
takes place in the rotary kiln. The rotary kiln consists of a
refractory-brick-lined cylindrical steel shell that is rotated by an
electrical drive. It is a countercurrent heating device slightly
inclined so that material fed into the cooler, upper end travels slowly
by gravity to be discharged onto the clinker cooler from the hotter,
lower discharge end. The burners at the firing end, i.e., the lower or
discharge end, produce a current of hot gases that heats the clinker
and the calcined and raw materials in succession as the gases pass
toward the feed end. As has been mentioned, a kiln can be classified as
wet (in which the kiln feed is a slurry) or dry. Dry process kilns
include the older-style, long dry process kiln with a single firing
point; the preheater/kiln system; and the preheater/precalciner kiln
system. In the preheater/precalciner system, a second burner is used to
carry out calcination in a separate vessel interposed between the
preheater and the kiln. The precalciner uses preheated combustion air
drawn from the clinker cooler and the kiln exit gases and is equipped
with an oil or coal burner that burns 50 to 60 percent of the total
kiln fuel input. The precalciner system permits the use of smaller
kilns since only the actual clinkering process is carried out in the
rotary kiln.
The kiln exhaust contains a wide variety of HAPs and other air
pollutants that originate from the fuel combustion and from the feed
material. In 1991, about 87 percent of the total U.S. kiln capacity
used coal, coke, or a combination of coal and coke as the primary fuel
(docket item II-I-42, p. 20). Only 3.5 percent of the kiln capacity is
fired with natural gas alone (not in combination with other fuels) and
oil as a primary fuel represented an insignificant fraction of the
total kiln capacity. Plants firing waste-derived fuels account for the
balance of the total capacity. The most common waste fuels used in
cement kilns are RCRA hazardous waste, tires and tire-derived fuel. To
a lesser extent, MSW, medical waste, and used motor oil are fired.
Feed materials are a source of gaseous organic HAP emissions. Some
feed materials contain organic carbon such as petroleum or kerogens.
The organic carbon can volatilize in the kiln and appear at the stack
exit as a ``blue haze'' which may contain organic HAPs. During one EPA-
sponsored test at a cement kiln using feed material with a high organic
matter content, significant levels of benzene (32 tpy) were detected in
the kiln exhaust (docket item II-A-41, docket item II-B-76). Organic
HAP emissions were found to vary with THC emissions during this test.
Chlorine entering the kiln system (from raw materials and also from
fuels) may react with the organic compounds present in the raw
materials or with PICs, to form chlorinated hydrocarbons or D/F in the
kiln stack exhaust. Approximately 20 percent of the HAPs listed in
section 112 of the Act are chlorinated organic compounds.
In the wet process and in the long kiln dry process, the emission
point for the kiln gases is typically the APCD discharge stack. In the
more complex preheater and precalciner process designs, the kiln gases
are routed through other pieces of process equipment, such as the raw
mill. In-line kiln/raw mills vent kiln gases through the raw mill. In
these systems the gases discharged from the APCD on the raw mill, are
in fact kiln exhaust gases.
The kiln alkali bypass stack is an additional emission point for
kiln gases which is sometimes found with preheater and precalciner
processes. The alkali bypass gas streams are kiln gases that have not
contacted the incoming feed material. The kiln gases that are drawn out
of the kiln prior to contact with the precalciner and preheater
sections pass through a separate APCD and may be discharged to the
atmosphere through a separate stack. In other process arrangements, the
treated alkali bypass gases are combined with the main kiln exhaust
gases and are discharged through a common stack. It is expected that
the same HAPs found in the main kiln stack are found in the alkali
bypass stack.
Kiln PM/HAP metals. All HAP metals have been identified in kiln
exhaust PM at various levels. Based on analysis of emissions test
reports, the total average HAP metal content of kiln exhaust PM is
approximately one weight percent (docket item II-B-36). Mass emission
rates of metal HAPs from the kiln depend on the concentration of metals
in the PM and the emission rates of PM. Analyses of emissions data
(docket item II-B-62) have shown that ESP-controlled PM emissions for
six NHW kilns ranged from 0.009 to 0.20 gr/dscf (corrected to seven
percent oxygen), with an average of 0.045 gr/dscf for 14 data points.
Fabric filter-controlled PM emissions for five NHW kilns ranged from
0.002 to 0.29 gr/dscf (corrected to seven percent oxygen), with an
average of 0.014 gr/dscf for 10 data points. For a 600,000 ton of
clinker/year kiln (this represents the capacity of a mid-sized kiln),
the range of kiln PM emissions (0.002 gr/dscf to 0.29 gr/dscf)
corresponds to 9 tpy to 1,360 tpy (docket item II-B-76). Based on an
average kiln PM emission of 0.03 gr/dscf, and assuming HAP metal
emissions are one percent by weight of PM emissions, HAP metal
emissions are approximately 1.4 tpy for a 600,000 ton of clinker/year
kiln (docket item II-B-76). Based on ICR responses, at least one plant
reported kiln emissions of over one tpy for one or more of the
following metal HAPs: chromium, lead, arsenic, mercury, antimony, and
manganese. However, no plant reported kiln emissions of more than 10
tpy of any single metal HAP (docket item II-B-69).
Kiln mercury. Mercury may be emitted in the kiln exhaust as either
a particulate or a gas. A summary was compiled of all currently
available mercury emission data for HW and NHW kilns (docket item II-B-
65). There are 8 data points for 7 NHW kilns, and 19 data points from
21 HW kilns (two sets of kilns shared a stack). The HW kiln data were
adjusted to remove mercury in the HW fuel and any mercury spikes. By
removing the portion of emissions attributed to test method spiking and
HW fuel mercury inputs, corrected emission data that are comparable
with data from NHW kilns were developed.
For a 600,000 ton of clinker/year kiln, the range of the mercury
emissions data [0.6 to 83 micrograms (g)/dscm at 7 percent
oxygen] corresponds to 0.0012 tpy to 0.17 tpy (docket item II-B-76),
while the average mercury emission (24 g/dscm) corresponds to
approximately 0.05 tpy (docket item II-B-76). One plant responding to
the ICR reported mercury emissions of over one ton per year.
Kiln D/F. For the purposes of analysis of the data, concentrations
of dioxin and furan congeners (specifically the tetra, hepta, hexa, and
octa congeners) were converted to a concentration that was equivalent
to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Determination
of TEQ concentrations was performed according to the international
method (docket item II-A-8).
An analysis of all available D/F emission data from 15 NHW kilns
showed that concentrations of D/F TEQ emitted in the kiln exhaust gas
measured downstream of the PMCD
[[Page 14196]]
ranged from 0.001 ng TEQ/dscm to over 1.2 TEQ ng/dscm with an average
of 0.20 ng TEQ/dscm (all concentrations at 7 percent oxygen)[D/F test
data are shown in Table 8 in Section V.D.2]. For a 600,000 ton of
clinker/year kiln, the range of the D/F TEQ concentrations (0.001 to
1.2 ng/dscm) corresponds to 0.0018 g/yr to 2.2 g/yr (docket item II-B-
76), while the average concentration (0.20 ng TEQ/dscm) corresponds to
an emission of 0.4 g TEQ/year (docket item II-B-76).
The predominant factor affecting D/F emissions is the temperature
of gases at the inlet to the PMCD (docket item II-I-81, docket item II-
I-82). Test data collected from both HW and NHW kilns show a trend of
decreasing D/F gas stream concentrations with decreasing temperature at
the inlet to the PMCD. In tests conducted on individual cement kilns
where the gas stream temperature was varied in the range of 350 to
500 deg.F, reductions in D/F TEQ concentrations by factors of 5 to 10
were observed when gas temperatures entering the PMCD were lowered from
the upper to lower end of the temperature range (docket item II-I-81,
docket item II-I-82).
Kiln THC/organic HAPs. The THC and organic HAP concentrations and
emission levels from kilns vary widely, depending primarily on the feed
materials (docket item II-I-66, docket item II-I-67, docket item II-I-
68). Some feed materials contain organic carbon such as petroleum or
kerogens. One kiln operator has conducted an extensive study of the
source of high THC and carbon monoxide (CO) emissions from the kiln
(docket item II-I-107). Higher than normal emissions from this kiln
were attributed to the shale used in the raw materials. Replacing the
shale with fire clay in the raw mix resulted in a dramatic reduction of
THC and CO emissions.
Another NHW kiln operator has determined that the raw materials are
the source of the majority of the observed benzene emissions (docket
item II-D-112). Kiln stack gas and preheater gas stream analyses before
and after switching fuel from a combination of coal and petroleum coke
to 100 percent natural gas showed little effect on benzene emissions.
These test data suggest that benzene emissions derived from the raw
materials (docket item II-I-41).
Fourier transform infrared spectroscopy was used to determine
organic HAP emissions at a NHW kiln. Estimated organic HAP emissions
(based on average concentrations measured in the kiln exhaust and 7,920
hr/yr of operation) showed that the kiln was a major source based on
organic HAP emissions. Organic HAP emission rates were estimated at 331
Mg/yr (365 tpy) hexane, 27 Mg/yr (30 tpy) toluene, 29 Mg/yr (32 tpy)
benzene, 14.5 Mg/yr (16 tpy) naphthalene, and 12 Mg/yr (13.2 tpy)
chlorobenzene (docket item II-A-41, docket item II-B-76).
In the ICR responses, many organic HAPs were reported as being
emitted in the kiln exhaust gas. Organic HAPs for which there was at
least one report of emissions of at least 0.91 Mg/yr (1.0 tpy) include
benzene, naphthalene, toluene, formaldehyde, xylenes, styrene, and
acetaldehyde. One facility reported more than 9.1 Mg/yr (10 tpy) each
of benzene and toluene emissions (docket item II-B-69).
Stack concentrations of THC were available for 16 NHW kilns (docket
item II-B-75). The concentrations were expressed in ppmv as propane on
a dry basis (ppmvd) at seven percent oxygen. For a 600,000 ton of
clinker/year kiln, the range of kiln THC emissions (0.4 ppmvd to 224
ppmvd as propane) corresponds to 1.5 tpy to 840 tpy (docket item II-B-
76), while the average kiln THC emissions (35 ppmvd as propane)
corresponds to 131 tpy (docket item II-B-76). Organic HAP
concentrations, as a percentage of THC for these data, ranged from 0 to
98 percent (docket item II-B-75). With an average of 23 percent of the
THC emissions being organic HAPs a 600,000 ton of clinker/year kiln
would emit from 0.3 tpy to 190 tpy of organic HAPs, based on the range
of THC stack concentrations.
The emissions from kiln alkali bypasses are expected to be the
result of incomplete combustion of fuel in the kiln, since this exhaust
gas stream does not contact incoming kiln feed materials. Alkali bypass
concentrations of THC were available for two kilns operating under NHW
conditions. The concentrations were expressed as ppmvd (as propane) at
seven percent oxygen, and averaged 3.4 ppmvd and 27 ppmvd, respectively
(docket item II-B-75). For typical alkali bypass gas flow rates at a
600,000 ton of clinker/year kiln, this range corresponds to
approximately 2.4 tpy to 19 tpy of THC, while the average kiln bypass
THC concentration (15 ppmvd) corresponds to 10.5 tpy of THC (docket
item II-B-76). Assuming that 5 percent of the THC emissions from alkali
bypasses are organic HAPs (docket item II-B-75), a 600,000 ton of
clinker/year kiln would emit from 0.3 tpy to 6 tpy of organic HAPs,
based on the range of THC alkali bypass stack concentrations.
Kiln HCl. The currently available HCl emission data obtained from a
total of 46 NHW and HW kilns range from 0.2 ppmvd to 157 ppmvd and the
average is 27 ppmvd for 72 data points (docket item II-B-62). (All
concentrations were corrected to seven percent oxygen.) For a 600,000
ton of clinker/year kiln, the range of kiln HCl emissions corresponds
to 0.6 tpy to 490 tpy, while the average HCl emission (27 ppmvd)
corresponds to 84 tpy (docket item II-B-76). Based on analyses of test
reports and ICR responses, HCl emissions range from less than 0.91 Mg/
yr (1 tpy) to over 272 Mg/yr (300 tpy). Ten plants responding to the
ICR reported emissions of HCl greater than 9.1 Mg/yr (10 tpy) from each
of 15 different kilns (docket item II-B-69).
The EPA notes that with the exception of three kilns that were
measured by FTIR, all of the HCl emission measurements included in the
analysis were obtained using EPA Method 26. A recently completed study
that compared the results of a draft test protocol using the gas filter
correlation infrared (GFCIR) instrumental method (proposed EPA Method
322) and EPA Method 26 found that HCl measured by GFCIR was typically
much higher than that measured by Method 26 (docket item II-I-121).
Concentrations of HCl measured by GFCIR ranged from 1.5 to 4.5 times
the concentrations measured by Method 26 for wet kilns and up to 30
times the concentrations measured by Method 26 for a dry kiln.
Subsequent laboratory recovery efficiency analyses suggested that
Method 26 is biased significantly low due to a scrubbing effect in the
front half of the sampling train. Therefore, it is likely that
currently available HCl emission data are understated.
4. Clinker Cooler
It is desirable to cool the clinker rapidly as it leaves the
burning zone of the kiln. Heat recovery, preheating of kiln combustion
air, and fast clinker cooling are achieved by clinker coolers of the
traveling-grate, planetary, rotary, or shaft type. Most commonly used
are grate coolers where the clinker is conveyed along the grate and
subjected to cooling by ambient air, which passes through the clinker
bed in cross-current heat exchange.
A portion of the clinker cooler exhaust serves as secondary
combustion air in the kiln. The remainder of the clinker cooler exhaust
is discharged to the atmosphere separately from the kiln exhaust gas
through a PM emission control device. Clinker cooler gases are also
sometimes routed through other pieces of process equipment, such as the
coal or raw mill, as a source of warm,
[[Page 14197]]
dry air prior to being reused as combustion air.
Since clinker coolers are not combustion devices, the only HAP
expected to be emitted are the metal HAPs associated with the clinker
cooler particulate, i.e., clinker dust. HAP metals that have been
detected in clinker include chromium, lead, nickel, arsenic, beryllium,
antimony, selenium, and mercury. In one study conducted by the Portland
Cement Association (docket item II-I-44, p. 4), the average
concentration of metal HAPs that has been detected in clinker is 555
parts per million by weight (ppmw). In an earlier study, cited by EPA
OSW the average HAP metal content in clinker was found to be 138 ppmw
(docket item II-A-24, pp. 3-62 to 3-65). Under the existing NSPS,
emissions of PM from clinker cooler gases are limited to 0.05 kg/Mg
feed (dry basis) (0.10 lb/ton). A plant producing 600,000 tpy of
clinker, emitting PM from the clinker cooler at the NSPS limit, would
emit 6 kg (14 lb) of HAP metals per year, assuming a 140 ppmw HAP metal
content in the PM (docket item II-B-76).
5. Finish Grinding/Conversion of Clinker to Portland Cement
The cooled clinker is conveyed to clinker storage or mixed with
gypsum and introduced directly into the finish mills. The finish mills
are large, rotating steel cylinders containing a charge of steel balls.
The clinker and gypsum are ground to a fine, homogeneous powder. Two
different types of mill systems may be used. In open-circuit milling,
the material passes directly through the mill without any separation of
fine and coarse particles. In closed-circuit grinding, the mill product
is carried to a cyclonic air separator in which the coarse particles
are rejected from the product and returned to the mill for further
grinding.
The finished portland cement is conveyed to bulk storage silos from
which it is dispensed for shipping. Portland cement is often loaded in
bulk into hopper trucks or rail cars. It may also be packaged in ``tote
bins'' or in 80 lb or 94 lb kraft paper bags. The bags are loaded onto
pallets for handling, warehousing, and shipping.
The only HAPs expected to be emitted from clinker/cement handling
processes are the metal HAPs associated with clinker and cement dust.
As was noted above, clinker dust is estimated to contain 555 ppmw of
metal HAPs. The HAP metals that have been identified in portland cement
include chromium, nickel, arsenic, lead, antimony, selenium, beryllium,
cadmium, and mercury. In cement (as opposed to clinker), the
concentrations of individual HAP metals range from an average of 0.014
ppmw mercury to an average of 76 ppmw chromium. The total average
concentration of metal HAPs in portland cement is 143 ppmw (docket item
II-I-44).
Total nationwide emissions of HAPs, PM, and VOCs from the above
emission sources in portland cement plants are estimated at 23,300 Mg/
yr (25,700 tpy). Over 260 Mg/yr (290 tpy) of these emissions are HAPs.
Emissions of PM and VOCs are estimated at 23,000 Mg/yr (25,400 tpy).
Given that these processes release significant quantities of HAPs
and the availability of emission control systems, the Agency selected
to develop and propose NESHAP for the following emission sources: NHW
kilns and NHW in-line kiln/raw mills; NHW kiln alkali bypasses; clinker
coolers; raw material dryers; feed preparation and materials handling
processes including raw mills, finish mills, storage bins (raw
material, clinker, finished product), conveying system transfer points,
bagging system, and bulk loading and unloading systems. Additional
information on the operations in portland cement plants selected for
regulation, and other operations, is included in the docket.
C. Selection of Pollutants
The proposed standards would limit emissions of metal HAPs [almost
all metals appearing in section 112(b) have been detected in portland
cement plant emissions] and organic HAPs (including D/F) from portland
cement manufacturing facilities. (Pollutant health effects were
discussed in section II.C.) These HAPs are emitted in significant
quantities from portland cement plant sources. The standards being
proposed to address metal and organic HAP emissions establish limits
for surrogate pollutants rather than for individual HAP compounds (a
separate emission limit is established for D/F). The reasons for using
surrogate pollutants are discussed below.
Controlling PM emissions will control the emissions of non-volatile
metal HAPs (and also the condensed organic HAPs including D/F which are
adsorbed on particulates). The available technologies used in the
cement manufacturing industry for the control of non-volatile HAP
metals are the same technologies (FFs and ESPs) as the proposed MACT
floor technologies for control of PM. Metal HAPs are estimated to
constitute about 1 percent by weight of kiln PM emissions from portland
cement manufacturing and about 0.06 percent by weight of clinker cooler
PM emissions. In addition, the use of PM as a surrogate for non-
volatile metal HAP emissions reduces the costs associated with
compliance testing and monitoring.
The proposed standards establish an emission limit for THC as a
surrogate for organic HAPs from new or reconstructed NHW kilns for the
following reasons. Methods used in the cement manufacturing industry
for the control of organic HAP emissions would be the same methods used
to control THC emissions. These emission control methods include using
feed materials with relatively low levels of organic matter and
achieving good combustion (docket item II-B-47, docket item II-B-48).
Standards limiting emissions of THC will also result in decreases in
organic HAP emissions (with the additional benefit of decreasing VOC
emissions).
Establishing emission limits for specific organic HAPs (with the
exception of D/F) would be impractical and costly. Total hydrocarbon,
which is less expensive to test for and monitor, can be used as a
surrogate for organic HAPs. Based on available data, organic HAPs range
from 0 to 98 percent of THC and are estimated to account for
approximately 23 percent on average of THC emissions from portland
cement manufacturing (docket item II-B-75). The Agency recognizes that
the level and distribution of organic HAPs associated with THC
emissions from cement kilns will vary from kiln to kiln. Limiting THC
as a surrogate for organic HAPs will eliminate costs associated with
speciating numerous compounds.
The proposed standards establish separate emission limits for D/F
because of the high toxicity associated with even low masses of these
compounds. In addition, data available to EPA establish the existence
of a separate MACT floor technology for D/F control.
The proposed regulation does not establish a limit for HCl
emissions from cement kilns because no MACT floor technology has been
identified. An HCl emission limit based on a beyond-the-floor control
option was determined not to be justified as discussed in section V.D.2
of this document.
The proposed regulation does not establish limits for mercury
emissions from cement kilns because no MACT floor control technology
has been identified. A mercury emission limit based on a beyond-the-
floor control option was determined not to be justified as discussed in
section V.D.2.
[[Page 14198]]
D. Selection of Proposed Standards for Existing and New Sources
1. Background
After the EPA has identified the specific source categories or
subcategories of sources to regulate under section 112, it must develop
MACT standards for each category or subcategory. Section 112
establishes a minimum baseline or ``floor'' for standards. For new
sources, the standards for a source category or subcategory cannot be
less stringent than the emission control that is achieved in practice
by the best-controlled similar source. [See section 112(d)(3)]. The
standards for existing sources may be less stringent than standards for
new sources, but they cannot be less stringent than the average
emission limitation achieved by the best-performing 12 percent of
existing sources for categories and subcategories with 30 or more
sources, or the average of the best-performing 5 sources for categories
or subcategories with fewer than 30 sources.
After the floor has been determined for a new or existing source in
a source category or subcategory, the Administrator must set MACT
standards that are technically achievable and no less stringent than
the floor. Such standards must then be met by all sources within the
category or subcategory. The regulatory alternatives selected for new
and existing sources may be different because of different MACT floors,
and separate emission limits may be established for new and existing
sources.
The EPA also may consider an alternative ``beyond the floor.''
Here, EPA considers the achievable reductions in emissions of HAPs (and
possibly other pollutants that are co-controlled), cost and economic
impacts, energy impacts, and other nonair environmental impacts. The
objective is to achieve the maximum degree of emission reduction
without unreasonable economic, energy or secondary environmental
impacts.
2. MACT Floor Technology, Emission Limits, and Format
The EPA conducted separate MACT determinations for PM (the
surrogate for HAP metals), D/F, mercury, THC (the surrogate for organic
HAPs), and HCl emissions from kilns and inline kiln/raw mills; for PM
emissions from clinker coolers; for PM and THC emissions from raw
material dryers; and for PM emissions from materials handling
facilities. For each combination of pollutant and affected source, MACT
floor technologies and beyond-the-floor control options were evaluated.
Several formats are available for establishing the emission limits
based on MACT. These include mass concentration (mass per unit volume),
volume concentration (volume per unit volume), mass emission rate (mass
per unit time), process emission rate (mass per unit of production or
other process parameter), and percent reduction.
For the portland cement manufacturing source category, EPA is
proposing numerical emission standards expressed as a process emission
rate and opacity limits for PM emissions from kilns; as mass per volume
of exhaust gas for D/F emissions from kilns; as volume per volume of
exhaust gas for THC emissions from kilns and raw material dryers; as a
process emission rate and opacity limit for clinker cooler PM
emissions; and as an opacity limit for materials handling facilities PM
emissions.
The following sections present a discussion of the rationale for
selecting the MACT technologies, emission limits, and format of the
standard for each affected source and associated pollutant.
Kiln and in-line kiln/raw mill PM HAP emissions. Well-designed and
properly operated FFs or ESPs are the PM control technologies presently
in use by the best performing 12 percent of existing kilns and in-line
kiln/raw mills. In the portland cement manufacturing industry, it is
estimated that at least 30 percent (docket item II-A-4) of existing
kilns are subject to the requirements of the NSPS for cement plants (40
CFR part 60, subpart F).
Table 7 lists the type of control device used with, and available
PM emissions data from, kilns and in-line kiln/raw mills subject to the
NSPS. The emission levels shown in Table 7 all meet the NSPS emission
limit and were all achieved with FFs and ESPs designed to meet the
NSPS. This represents the MACT floor technology for control of PM from
kilns and in-line kiln/raw mills.
Table 7.--Particulate Emissions From NSPS Kilns
[Docket Item II-A-4, Docket Item II-A-43, Docket Item II-B-62]
----------------------------------------------------------------------------------------------------------------
PM (kg/Mg dry
Kiln type APCD type feed) Location
----------------------------------------------------------------------------------------------------------------
PH................................. FF 0.0011 Southdown--Kosmosdale,
KY.
PC................................. FF a 0.0039 Boxcrow Cement--
Midlothian, TX.
PH................................. ESP b 0.0075 Ash Grove--Durkee, OR.
DRY................................ FF a 0.0090 Southdown #1--
Fairborn, OH.
PC................................. ESP c 0.015 RMC Lone Star--
Davenport, CA.
PC................................. FF 0.015 Kaiser Cement--
Cupertino, CA.
PH................................. ESP 0.015 Roanoke Cement--
Cloverdale, VA.
PC................................. FF 0.020 Moore McCormack--
Knoxville, TN.
PH................................. FF 0.029 Moore McCormack--
Brooksville, FL.
PC................................. FF 0.033 Kaiser Cement--Lucerne
Valley, CA.
PC................................. FF 0.035 Calif Portland--
Mojave, CA.
PC................................. FF 0.04 Martin Marietta--
Leamington, UT.
PC................................. ESP 0.044 Kaiser--San Antonio,
TX.
PC................................. FF 0.048 Martin Marietta--
Lyons, CO.
PH/PC.............................. ESP b 0.051 Lone Star--Cape
Girardeau, MO.
WET................................ ESP 0.056 Monolith Portland--
Laramie, WY.
DRY................................ FF 0.056 Lone Star--Pryor, OK.
DRY................................ ESP d 0.058 Ash Grove #2--
Louisville, NE.
PC................................. ESP 0.065 General Portland--New
Braunfels, TX.
PC................................. FF 0.068 Davenport Industries--
Buffalo, IA.
PH................................. FF 0.070 Ideal Basic--La Porte,
CO.
PH................................. FF 0.074 Southwestern Portland--
Odessa, TX.
DRY................................ ESP 0.11 Ash Grove #1--
Louisville, NE.
[[Page 14199]]
PC................................. ESP 0.12 Texas Industries--
Hunter, TX.
PC................................. ESP 0.13 Lehigh--Mason City,
IA.
WET................................ ESP 0.15 Genstar--San Andreas,
CA.
WET................................ FF 0.15 Lone Star--Salt Lake
City, UT.
----------------------------------------------------------------------------------------------------------------
PC = precalciner.
PH = preheater.
a = average of four tests.
b = average of three tests.
c = average of two tests.
d = average of five tests.
The data in Table 7 were obtained from EPA Method 5 compliance
tests on new kilns subject to the NSPS [0.15 kg/Mg dry feed (0.30 lb/
ton dry feed)]. These tests measure the performance of PM APCDs
associated with new kilns over a relatively short period (typically
three 1-hour test runs). These data show that PM emissions from ESPs
and FFs designed to meet the NSPS and operated and maintained to
demonstrate initial compliance with the NSPS under Method 5 test
conditions varied within a range of 0.0011 kg/Mg dry feed (0.0022 lb/
ton dry feed) to 0.15 kg/Mg dry feed (0.3 lb/ton dry feed). The data in
Table 7 show equivalent performance can be expected from FFs and ESPs,
and that neither technology offers a clear advantage. Due to the fact
that the best performing kilns and in-line kiln/raw mills use FFs and
ESPs designed to meet the NSPS and because of the variability in
performance of well-designed, well-maintained and properly operated FFs
and ESPs, the emission limit represented by the MACT floor technology
is equivalent to the NSPS of 0.15 kg/Mg dry feed (0.30 lb/ton dry
feed).
No technologies were identified for existing or new kilns or in-
line kilns/raw mills that would consistently achieve lower emission
levels of PM than the NSPS limit. Consequently, there is no beyond-the-
floor technology that has been shown to consistently achieve lower
emissions. Therefore the PM emission limit proposed for new and
existing kilns and in-line kiln/raw mills is 0.15 kg/Mg dry feed (0.30
lb/ton dry feed), which is equivalent to the NSPS limit.
The NSPS establishes an opacity limit, and an opacity limit is also
being proposed under this standard. The maximum 6-minute average
opacity level may not exceed 20 percent opacity, as is the case for the
NSPS.
The production-based emission limit format was chosen for kiln and
in-line kiln/raw mill PM emissions. The units for this emission
standard are kg of PM per Mg of dry feed (lb PM per ton of dry feed).
This format (mass per unit of production) and associated opacity limit
are consistent with the format of the portland cement plant NSPS (40
CFR part 60, subpart F). At least 30 percent of the kilns in the
industry are subject to the NSPS (docket item II-A-4) and these plants
are already monitoring the production-based emission rate and the
opacity.
A concentration format (e.g., g/dscm [gr/dscf]) was considered for
the kiln and in-line kiln/raw mill PM emission limit. One reason that
this format was not chosen was that it would be inconsistent with the
NSPS PM emission limit format. However, there are other considerations.
A concentration format would penalize more energy efficient kilns,
which burn less fuel and produce less kiln exhaust gas per megagram of
dry feed. This is because with a concentration based standard the more
energy-efficient kilns would be restricted to a lower level of PM
emitted per unit of production.
Kiln and in-line kiln/raw mill D/F emissions. The EPA has
identified two technologies for control of D/F emissions. One
technology achieves low D/F emissions by a combination of proper kiln
operation, proper combustion, proper control device operation, and a
reduction in the kiln gas temperature at the inlet to the PMCD. The
other technology is activated carbon injected into the kiln exhaust
gas.
The discussion in this section refers to D/F emissions in units of
TEQ. Toxic equivalent refers to the international method of expressing
toxicity equivalents for dioxins and furans as defined in EPA report,
``Interim Procedures for Estimating Risks Associated with Exposures to
Mixtures of Chlorinated Dibenzo-p-dioxins and -dibenzofurans (CDDs and
CDFs) and 1989 Update'' (docket item II-A-8).
Dioxin/furan emissions data were obtained from testing that was
conducted at NHW kilns, with NHW fuels at kilns that normally burn HW,
and under worst-case conditions at kilns that burn HW (as part of
Certificate of Compliance [COC] testing). Based on the test results for
both NHW and HW kilns, the predominant factor affecting D/F emissions
is the temperature of gases at the inlet to the PMCD (docket item II-A-
42; docket item II-B-78; docket item II-I-81, pp. 127 to 133; docket
item II-I-82, pp. 135 to 175). The highest D/F emissions (near 40 ng
TEQ/dscm) occurred at the highest gas temperatures (between 500 deg.F
and 700 deg.F) while the lowest emissions (near 0.02 ng TEQ/dscm)
occurred at the lowest temperature (at approximately 210 deg.F). [The
emission 0.02 ng TEQ/dscm is the average of the four NHW D/F test
results that were measured at gas temperatures less than 230 deg.F, as
shown in Table 8.]
Dioxin/furan TEQ emissions data and stack temperatures from kilns
firing NHW fuels are listed in Table 8. The data are listed in order of
ascending stack temperature. Fourteen NHW data points were obtained
during normal kiln operation, three points were obtained as NHW
baseline runs prior to HW COC testing, one data point (at the 518
deg.F stack temperature) was obtained at maximum combustion
temperature, and one point was obtained under unknown test conditions.
Stack temperatures are presented, since inlet PMCD temperature data are
not typically recorded during stack emissions testing. It is
acknowledged that stack temperatures will be lower than inlet PMCD
temperatures.
[[Page 14200]]
Table 8.--Average Dioxin/Furan Toxic Equivalent Emissions (at 7 Percent Oxygen) and Average Stack Gas Temperatures for NHW Cement Kilns and Kilns Tested
Under NHW Conditions
[Docket Item II-B-78]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Avg TEQ ng/
Kiln type APCD type Kiln fuel Avg Gas T ( deg.F) dscm Kiln location
--------------------------------------------------------------------------------------------------------------------------------------------------------
PH/PC...................... FF Natural gas; main stack 183 0.011 Capital Aggregates--San
tested. Antonio TX.
PC......................... FF Coal,tires, pulp/paper mill 220 0.0063 Calaveras Cement--Redding
sludge. CA.
PH/PC...................... FF Natural gas; raw mill on... 221 0.042 Ash Grove--Seattle WA (kiln/
in-line mill).
PH/PC...................... ESP Not reported............... 226 0.00087 RMC Lonestar--Davenport CA.
PC......................... FF Coal & tires............... 233 0.21 Calaveras Cement--Redding,
CA.
PH/PC...................... FF Natural gas; bypass stack 299 0.054 Capital Aggregates--San
tested. Antonio TX.
WET........................ ESP Coal....................... 305 0.0024 Holnam--Florence CO.
WET........................ ESP Coal & natural gas......... 315 0.072 Ash Grove--Montana City MT.
WET........................ ESP Coal....................... 346 q 0.37 Lehigh--Union Bridge MD.
WET........................ ESP coal & tires............... 358 q 1.2 Lehigh--Union Bridge MD.
WET........................ ESP Coal/coke.................. 366 0.032 Holnam kiln #1--Holly Hill
SC.
DRY........................ FF Coal, gas, tire derived 396 0.0035 Riverside--Oro Grande CA.
fuel.
WET........................ ESP Natural gas................ 397 0.020 Capital Aggregates--San
Antonio TX.
DRY........................ FF Coal & natural gas......... 403 0.0084 Riverside--Oro Grande CA.
WET........................ ESP Coal....................... 417 0.12 Lone Star--Greencastle IN.
WET........................ ESP Coal/coke.................. 418 0.04 Holnam kiln #2--Holly Hill
SC.
DRY........................ ESP Coal, coke, & tires........ 450 0.074 Lone Star--Oglesby IL.
WET........................ ESP Coal....................... 482 0.55 Continental Cement--
Hannibal MO.
WET........................ ESP Coal....................... 518 1.0 Holnam--Clarksville MO.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Abbreviations:
PH/PC = preheater/precalciner.
ESP = electrostatic precipitator.
PC = precalciner.
FF = fabric filter.
Note: Entries flagged with and q are listed in Table 9 and discussed in the text.
The data in Table 8 show that all NHW D/F emissions were less than
0.2 ng TEQ/dscm at stack temperatures below 340 deg.F, except for one
data point which is discussed below. The stack temperature of 340
deg.F corresponds to an estimated inlet PMCD temperature of
approximately 400 deg.F after accounting for cooling in the ductwork.
The EPA estimates that approximately 50 percent of existing PMCDs used
at both wet-and dry-type NHW kilns operate with a maximum inlet PMCD
temperature of approximately 400 deg.F (docket item II-B-73). Since
the MACT floor is based on the technology in use by the best performing
12 percent of the affected sources, the MACT floor for existing kilns
corresponds to reduction of kiln exhaust gas stream temperature at the
PMCD inlet to 400 deg.F.
One demonstrated method of temperature reduction is injection of
water to provide rapid cooling of kiln exhaust gases upstream of the
inlet to the PMCD. Rapid cooling reduces D/F formation that occurs
within the temperature window 232 deg.C (450 deg.F) to 343 deg.C
(650 deg.F).
As shown in Table 8, D/F emissions from 3 of the 13 tests conducted
at stack temperatures below 400 deg.F exceeded 0.2 ng TEQ/dscm. For
discussion purposes, the three data points are listed in Table 9 with
the corresponding stack temperature. The Calaveras kiln that emitted
0.21 ng TEQ/dscm when tested at a stack temperature of 233 deg.F
emitted 97 percent less D/F at a slightly lower stack temperature and
with a different mixture of fuels, demonstrating that the kiln could
achieve 0.2 ng/dscm through proper kiln combustion.
Table 9.--Data from KILNS at Which Dioxin/Furan TEQ Emissions Exceeded
0.2 ng/dscm
------------------------------------------------------------------------
Average
D/F TEQ
Average stack gas temperature (*F) (ng/dscm Kiln location
at 7%
O2)
------------------------------------------------------------------------
233.................................. 0.21 Calaveras--Redding CA.
346.................................. 0.37 Lehigh--Union Bridge
MD.
358.................................. 1.2 Lehigh--Union Bridge
MD.
------------------------------------------------------------------------
The Lehigh kiln emitted 0.37 ng TEQ/dscm at a stack temperature of
346 deg.F during coal combustion and 1.2 ng TEQ/dscm at a stack
temperature of 358 deg.F during coal and tire combustion. The EPA
concluded that the high emission (of 1.2 ng TEQ/dscm) resulted from
poorly controlled tire combustion/kiln operation, since (as shown in
Table 8) three other NHW kilns emitted less than 0.2 ng TEQ/dscm when
tested while burning tires. In the absence of detailed information on
kiln and APCD operating conditions, fuel firing and combustion control,
the Lehigh emission level of 0.37 ng TEQ/dscm at a stack temperature of
346 deg.F cannot be explained.
Temperature reduction to 400 deg.F, in conjunction with proper
control of kiln and PMCD operation and efficient combustion will limit
D/F emissions to 0.2 ng TEQ/dscm in most (if not all) cases, and the
proposed D/F standard for existing kilns is set at this level. The EPA
recognizes that the available emissions data show that one kiln (as
illustrated by the Lehigh data in Table 9) cannot achieve 0.2 ng TEQ/
dscm at an inlet temperature to the PMCD below 400 deg.F, and that
parameters consistent with proper equipment operation have not been
precisely specified. The proposed standards therefore provide that
kilns that cannot meet the 0.2 ng TEQ/dscm limit would be required to
maintain the temperature at the inlet to the PMCD at no more than 400
deg.F and to limit the D/F emissions to 0.4 ng
[[Page 14201]]
TEQ/dscm. This limit of 0.4 ng TEQ/dscm is consistent with the
emissions from the Lehigh kiln during coal combustion with an estimated
PMCD inlet gas temperature of 400 deg.F.
The Agency has considered whether and how to account for emissions
variability in establishing the alternative TEQ limit of 0.4 ng/dscm in
conjunction with the 400 deg.F temperature limit at the PMCD. As
discussed in this section, available emissions data indicate that most
kilns will be able to achieve an emission level of 0.2 ng TEQ/dscm or
lower when operating the PMCD at or below 400 deg.F. Even though the
Lehigh kiln's emissions were 0.37 ng TEQ/dscm at 346 deg.F (when not
burning tires), we believe that a TEQ limit of 0.4 ng/dscm is
appropriate given the preponderance of emissions data at or below 0.2
ng TEQ/dscm. These data (given the strong indications that all units
will meet the 0.4 ng TEQ/dscm limit at temperatures of 400 deg.F or
below) suggest that using a more specific approach for variability is
not needed for this proposed standard. The Agency invites comments on
other approaches for accommodating variability in D/F emissions for NHW
cement kilns.
Thus, the proposed standard requires that the temperature at the
inlet to the PMCD be maintained at a level no greater than either: (1)
the higher of 400 deg.F or the temperature established during the
successful Method 23 performance test plus five percent (not to exceed
25 deg.F) of the temperature measured in deg.F during the successful
compliance test, if D/F emissions were determined to be no greater than
0.15 ng toxic equivalent (TEQ)/dscm (6.5 x 10-11 gr/dscf);
(2) the higher of 400 deg.F or the temperature established during the
successful Method 23 performance test, if D/F emissions were determined
to be greater than 0.15 ng toxic equivalent (TEQ)/dscm (6.5 x
10-11 gr/dscf) but less than 0.2 ng toxic equivalent (TEQ)/
dscm (8.7 x 10-11 gr/dscf);, or (3) 400 deg.F if D/F
emissions were greater than 0.2 ng TEQ/dscm (8.7 x 10-11 gr/
dscf) but less than or equal to 0.4 ng TEQ/dscm (1.7 x 10-10
gr/dscf).
Activated carbon injection (ACI) was investigated as a potential
beyond-the-MACT-floor option for existing cement kilns. Activated
carbon injection is used at one cement plant on two NHW kilns for the
purpose of reducing plume opacity. The total capital cost of an ACI
system is estimated to range from $680,000 to $4.9 million per kiln.
The total annual costs of an ACI system are estimated to range from
$426,000 to $3.3 million per kiln. These costs include the carbon
injection system and an additional baghouse to collect the carbon
separately from the existing primary particulate collector (docket item
II-B-67). Based on these costs, and considering the level of D/F
emissions achievable at the floor level of control, the Administrator
has determined that this beyond-the-floor (BTF) option for D/F MACT for
existing kilns may not be justified. Therefore the Agency is not
proposing a BTF standard. Notwithstanding these costs and the limited
emissions reductions that a BTF standard would achieve, the Agency
solicits comment on whether a BTF standard would be appropriate given
the Agency's and the Congress' special concern about D/F. D/F are some
of the most toxic compounds known due to their bioaccumulation
potential and wide range of health effects at exceedingly low doses,
including carcinogenesis. Exposure via indirect pathways was in fact a
chief reason that Congress singled out D/F for priority MACT control in
section 112(c)(6) of the Act [see S. Rep. No. 128, 101st Cong. 1st
Sess. at 154-155 (1989)]. Thus costs to reduce dioxin emissions are
frequently justified by the benefits of removing this very toxic HAP.
[See 61 FR at 17382, 17392, and 17403 (April 19, 1996) (The EPA
proposes BTF standards for D/F emissions from hazardous waste
combustion sources).] The EPA is influenced here by the fact that most
sources appear to be able to achieve the 0.2 ng TEQ/dscm BTF option
through the use of the floor technology alone, i.e. solely through the
use of temperature control. Thus, the floor standard (which facially
allows the option of 0.4 ng TEQ/dscm) in reality may be virtually
equivalent to the BTF level.
Activated carbon injection was also considered as a candidate MACT
for new cement kilns. Since no D/F performance data are available on
the existing cement kiln ACI system installed to reduce opacity, EPA
considered the performance of ACI on other potentially similar sources.
Experience with ACI on municipal waste combustors (MWCs) and medical
waste incinerators (MWIs) has led EPA to develop emission limits for D/
F for these sources in the range of 0.26 to 2.5 ng TEQ/dscm (docket
item II-J-3, docket item II-J-7). Assuming the performance level of ACI
on MWIs or MWCs to be similar to that of a cement kiln, the D/F
emissions levels achieved with ACI are expected to be about the same
level that can be achieved with temperature reduction. Therefore,
considering the level of D/F emissions achievable by PMCD inlet
temperature reduction alone, the Administrator has determined that the
temperature reduction plus ACI option for D/F MACT for new kilns may
not be justified, and the Agency is not proposing a standard based on
ACI. Notwithstanding the limited emissions reduction that such a
standard would achieve, the Agency solicits comment on whether or not
such a standard would be appropriate, given the Agency's and the
Congress' special concern about D/F. The EPA is influenced here,
similarly to the situation for existing kilns, by the fact that most
new sources appear to be able to achieve a 0.2 ng TEQ/dscm emission
level solely through the use of temperature control. Thus the proposed
standards (which facially allow a 0.4 ng TEQ/dscm emission level where
the implementation of temperature reduction may not achieve a 0.2 ng
TEQ/dscm emission level) in reality may be virtually equivalent to a
0.2 ng TEQ/dscm emission level.
For the kiln and in-line kiln/raw mill D/F emission standard, a
mass per volume concentration emission limit format was chosen. The
specific units of the emission limit are ng of D/F TEQ/dscm, referenced
to seven percent oxygen. This emission limit format has historically
been used by EPA for many air emission standards. This format is
consistent with the format of the OSW MACT standard for HW cement
kilns.12 The concentration is corrected to seven percent
oxygen to put concentrations measured in stacks with different oxygen
concentrations on a common basis. Also, the typical range of oxygen
concentrations in cement kiln stack gas is from five to 10 percent
oxygen; therefore, seven percent is representative.
---------------------------------------------------------------------------
\12\ The EPA proposed regulations for subpart EEE of 40 CFR part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
A mass per volume concentration emission limit based on total D/F
congeners rather than TEQ was also considered. However, the TEQ format
was chosen in order to maintain consistency with the rule for cement
kilns which burn hazardous waste.
Kiln and in-line kiln/raw mill mercury emissions. Activated carbon
injection (ACI) was considered a potential control technology for
mercury MACT for cement kilns, since a form of this technology has been
demonstrated on medical waste incinerators and municipal waste
combustors (docket item II-A-36, pp. 98 to 99 and B-7 to B-8; docket
item II-A-11; docket item II-A-19; docket item II-A-23), and is being
used at one cement plant on two NHW kilns to reduce the opacity (docket
item II-B-35). In these
[[Page 14202]]
applications, the activated carbon (AC) is injected into the
uncontrolled exhaust gas stream ahead of the kiln PMCD.
In cement kiln applications for mercury control, the AC would need
to be injected downstream from the kiln PMCD and subsequently collected
in a separate PMCD, e.g., a baghouse. This is because the PM collected
from the kiln exhaust, i.e., cement kiln dust (CKD), is typically
recycled from the kiln PMCD back to the kiln, and in some cases may
constitute as much as 50 percent of the feed material input to the
kiln. If the AC is not injected downstream of the kiln PMCD, and then
collected in a separate PMCD downstream of the kiln PMCD, the AC would
also be recycled back to the kiln along with the adsorbed mercury. This
recycling of mercury back to the cement kiln via the AC would result in
the revaporization of the mercury in the kiln gas and ultimately the
mercury would be emitted to the atmosphere. The two cement kiln ACI
systems cannot be considered as controls for mercury for cement kilns
because they do not include provisions for injecting the AC downstream
of the kiln PMCD nor do they have the additional PMCD necessary to
remove the injected carbon from the exhaust gas stream for disposal,
but instead include the AC with the CKD that is recycled to the kiln.
Therefore there is no mercury MACT floor for new or existing kilns.
Activated carbon injection (with an additional PMCD) was
investigated as a potential beyond-the-MACT-floor option for mercury
for new and existing cement kilns. The total capital cost of an ACI
system is estimated to range from $680,000 to $4.9 million per kiln.
The total annual costs of an ACI system are estimated to range from
$430,000 to $3.3 million per kiln. These costs include the carbon
injection system and an additional baghouse necessary to collect the
carbon separately from the CKD (docket item II-B-67). The cost-
effectiveness of ACI applied to cement kilns ranges from $20,000,000 to
$50,000,000 per ton of mercury.
It is noted that the Agency has proposed a mercury emissions limit
for hazardous waste burning (HW) cement kilns (61 FR 17358), based on
the beyond-the-MACT-floor option of ACI. However, mercury levels in
hazardous waste fuels per million BTU of heat input are generally
higher than mercury levels in coal that is fired in non-hazardous waste
burning (NHW) cement kilns. Thus, HW cement kilns generally have higher
mercury emissions than NWH cement kilns. Further, the available data
indicate that existing mercury emissions from essentially all
individual NHW cement kilns are lower than the beyond-the-MACT-floor
emission limit that is now being considered by the Agency to be
promulgated for HW cement kilns. Based on the relatively low levels of
existing mercury emissions from individual NHW cement kilns, and the
costs of reducing these emissions by ACI, the Administrator has
determined that this beyond-the-MACT-floor option for reducing mercury
from new and existing NHW kilns may not be justified. Thus, the Agency
is not proposing a mercury standard for new and existing NHW cement
kilns.
Notwithstanding the reasons for not proposing a mercury standard
for NHW cement kilns, the Agency solicits comment on whether a BTF
standard would be appropriate given the Agency's and Congress' special
concern about mercury. Mercury is one of the more toxic metals known
due to its bioaccumulation potential and the adverse neurological
health effects at low concentrations especially to the most sensitive
populations at risk (i.e. unborn children, infants and young children).
In addition, as with D/F, Congress has singled out mercury in section
112(c)(6) of the Act for prioritized control. Furthermore, the amount
of mercury emitted by these sources is not inconsequential, roughly
10,000 pounds annually (or about 60 pounds per kiln annually) making
NHW cement kilns a significant source of mercury emissions that may
warrant attention under section 112(c)(6) of the Act depending on what
other opportunities for controlling mercury from other significant
sources are available.
It is EPA's tentative conclusion, however, that concerns as to
health risks from mercury emissions from these sources may be
appropriately addressed pursuant to the timetable set out in the Act,
namely through the residual risk determination process set out in
section 112(f) of the Act. A more accelerated determination may be
warranted, however, for other mercury-emitting sources, in particular
hazardous waste combustion sources, where there are special
considerations of immediately protective rules imposed by the Resource
Conservation and Recovery Act. [See 61 FR at 17369-17370 (April 19,
1996).]
Kiln and in-line kiln/raw mill THC main exhaust emissions. Based on
data from 31 tests conducted at 16 NHW kilns (docket item II-B-75), THC
emissions varied between 0.4 ppmvd and 224 ppmvd (as propane, corrected
to seven percent oxygen). With the exception of two kilns which employ
a precalciner system with no preheater, no add-on air pollution control
technologies are presently in use that decrease emissions of THC (the
surrogate for organic HAPs) from NHW cement kilns. On this basis the
MACT floor for THC emissions from existing kilns and in-line kiln/raw
mills is no control.
The precalciner/no preheater system was considered as a possible
beyond-the-floor technology for existing kilns and as a possible MACT
floor for new kilns (docket item II-B-47, docket item II-B-48). The
precalciner/no preheater technology acts like an afterburner to combust
organic material in the feed. However, it was found to increase fuel
consumption 79 percent relative to the preheater/precalciner designs
(docket item II-B-48, docket item II-D-199). The EPA estimates that
precalciner/no preheater kilns would emit six times as much
SO2 (at 3.7 lb SO2/ton clinker), two and one half
times as much NOX (at 9.8 lb NOX/ton clinker),
and 1.2 times as much CO2 (at 2,086 lb CO2/ton
clinker) as a preheater/precalciner kiln of equivalent clinker capacity
(docket item II-B-48). For a 600,000 ton clinker/year kiln, increased
emissions for a flash precalciner relative to a preheater/precalciner
are: 930 tpy SO2, 1,740 tpy NOX, and 109,000 tpy
CO2 (docket item II-B-76, docket item II-D-199).
One THC control method available is feed material selection. Total
hydrocarbon emissions from kilns can be limited by avoiding feed
materials which have excessive organic contents (docket item II-I-66,
docket item II-I-67, docket item II-I-68). A few existing kilns have
employed this method, but not enough to constitute a MACT floor for
existing kilns. Also, this method is not available for existing kilns
in that facilities are generally tied to existing raw materials sources
in close proximity to the facility. Raw material proximity
(transportation cost) is usually a major factor in plant site
selection. Feed material selection can be employed in the siting
process for new kilns, and to a limited extent at existing kilns.
The precalciner/no preheater technology was also considered as a
MACT floor for new sources but, when NOX, SO2,
and CO2 emissions and energy penalties are considered, the
Administrator has determined that it does not represent the MACT floor
for new sources, since the kilns employing this technology cannot be
considered to be the best controlled similar source. The combination of
feed material selection, site location and feed material blending was
determined to be MACT for new sources, in that this method has been
used at some existing sources and that site selection based on
availability
[[Page 14203]]
of acceptable raw material hydrocarbon content is feasible.
The numerical emission limit proposed for THC from the main exhaust
of new kilns and new in-line kiln/raw mills is 50 ppmvd (as propane,
corrected to seven percent oxygen). This represents a level which is
consistently achievable, as shown by tests across a broad spectrum of
feed material compositions, when feeds with high organic contents are
avoided. Based on the available THC main exhaust concentration data for
existing NHW kilns, approximately 62 percent of the tested NHW kilns
could meet the 50 ppmvd limit (docket item II-B-75).
For the new kiln and in-line kiln/raw mill main exhaust THC
emission standard, a volume per volume concentration emission limit
format was chosen. The specific units of the emission limit are ppmvd
(as propane, corrected to seven percent oxygen). This emission limit
format has historically been used by EPA for many air emission
standards. This format is consistent with the format of the OSW MACT
standard for HW cement kilns.13 The concentration is
corrected to seven percent oxygen to put concentrations measured in
stacks with different oxygen concentrations on a common basis, and
because the typical range of oxygen concentrations in cement kiln stack
gas is from five to 10 percent oxygen; therefore, seven percent is
representative. The THC concentration can be monitored directly with
the CEM required by this standard. The reference or calibration gas for
the THC CEM is propane, and the data analyzed in the development of
this standard were referenced to propane, therefore propane is the
appropriate reference compound for concentration data.
---------------------------------------------------------------------------
\13\ The EPA proposed regulations for subpart EEE of 40 CFR Part
63 on April 19, 1996 at 61 FR 17358.
---------------------------------------------------------------------------
Kiln and in-line kiln/raw mill HCl emissions. No technologies that
control HCl emissions have been identified that are currently being
used by more than six percent of the cement kilns in the U.S. For this
reason, there is no MACT floor for existing kilns. One technology
considered as potential MACT for new kilns was an alkaline scrubber,
since two kilns in the U.S. operate scrubbers to control SO2
emissions. However, these SO2 scrubbers are operated only
intermittently (docket item II-D-196) and thus cannot be considered
best controlled similar source. For this reason there is no MACT floor
for new kilns.
Alkaline scrubbers were considered as a beyond-the-floor option for
HCl control. Based on engineering assessment of HCl scrubbers used in
MWC and MWI applications and transfer of similar technology to the
cement industry and on vendor design information (docket item II-D-36),
an alkaline scrubber could achieve 15 ppmv HCl outlet concentration at
low inlet HCl loadings or at least 90 percent removal with an inlet HCl
level of 100 ppmv or greater. Based on this estimated performance,
annual emission reduction estimates range from 12 tpy of HCl and 27 tpy
of SO2 to 200 tpy of HCl and 600 tpy of SO2 per
kiln (docket item II-B-67). The total capital cost of installing an
alkaline scrubber on an existing kiln is estimated to range from
$980,000 to $4.6 million. The total annual cost is estimated to range
from $300,000 to $1.5 million per kiln (docket item II-B-67).
Based on the costs of control and the emissions reductions that
would be achieved, the Administrator has determined that beyond-the-
floor controls are not warranted. Therefore, there is no proposed
emission limit for HCl from new and existing NHW kilns and NHW in-line
kiln/raw mills. Analyses indicate that the ambient concentrations of
HCl produced by emissions from existing NHW kilns and in-line kiln/raw
mills are below the health effects reference concentration for HCl
(docket item II-B-71).
Clinker cooler PM HAP emissions. Particulate emissions from clinker
coolers are typically controlled by FFs (docket item II-B-69). In the
portland cement manuf
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