EPA-450/2 -74-018a
BACKGROUND INFORMATION
FOR STANDARDS OF PERFORMANCE:
ELECTRIC SUBMERGED ARC FURNACES
FOR PRODUCTION OF FERROALLOYS
VOLUME 1: PROPOSED STANDARDS
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research. Triangle Park, North Carolina 27711
October 1974
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technical data of interest to a limited number of readers. Copies are
available free of charge to Federal employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the Air
Pollution Technical Information Center, Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
Publication No. EPA-450/2-74-018®
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PREFACE
A. Purpose of this Report
Standards of performance under section 111 of the Clean
Air Act- are proposed only-after a very detailed investigation
of air pollution control methods available to the affected
industry and the impact of their costs on the industry. This
report summarizes the information obtained from such a study
of the ferroalloy industry. It is being distributed in
connection with formal proposal of standards for that industry
in the Federal Register. Its purpose is to explain the
background and basis of the proposal in greater detail than
could be included in the Federal Register, and to facilitate
analysis of the proposal by interested persons, including those
who may not be familiar with the many technical aspects of the
industry. For additional information, for copies of documents
(other than published literature) cited in the Background
Information Document, or to comment on the proposed standards,
contact Mr. Don R. Goodwin, Director, Emission Standards and
Engineering Division, United States Environmental Protection
Agency, Research Triangle Park, North Carolina 27711 [(919)688-8146],
B. Authority for the Standards
Standards of performance for new stationary sources are
promulgated in accordance with section 111 of the Clean Air Act
(42 USC 1857c-6), as amended in 1970. Section 111 requires
I/ Sometimes referred to as "new source performance
standards" (NSPS).
in
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the establishment of standards of performance for new stationary
sources of air pollution which "... may contribute significantly
to air pollution which causes or contributes to the endangerment
of public health or welfare." The Act requires that standards
of performance for such sources reflect "... the degree of
emission limitation achievable through the application of the best
system of emission reduction which (taking into account the cost
of achieving such reduction) the Administrator determines has
been adequately demonstrated." The standards apply only to
stationary sources, the construction or modification of which
commences after regulations are proposed by publication in
the Federal Register.
Section 111 prescribes three steps to follow in establishing
standards of performance.
I. The Administrator must identify those categuries of
stationary sources for which standards of performance
will ultimately be promulgated by listing them in the
Federal Register.
2. The regulations applicable to a category so listed must
be proposed by publication in the Federal Register, within
120 days of its listing. This proposal provides interested
persons an opportunity for comment.
3. Within 90 days after the proposal, the Administrator
must promulgate standards with any alterations he deems
appropriate.
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It 1s Important to realize that standards of performance,
by themselves, do not guarantee protection of health or welfare;
that 1s, they are not designed to achieve any specific air
quality levels. Rather, they are designed to reflect best
demonstrated technology (taking Into account costs) for the
affected sources. The overriding purpose of the collective
body of standards is to maintain existing air quality and to
prevent new pollution problems from developing.
Previous legal challenges to standards of performance for
Portland cement plants, steam generators, and sulfuric acid
plants have .resulted in several court decisions^ of importance
1n developing future standards. In those cases, the principal
issues were whether EPA: (1) made reasoned decisions and
fully explained the basis of the standards, (2) made available
to interested parties the information on which the standards
were based, and (3) adequately considered significant comments
from interested parties.
Among other things, the court decisions established:
(1) that preparation of environmental impact statements is not
necessary for standards developed under section ill of the Clean
A1r Act because, under that section, EPA must consider, any
counter-productive environmental effects of a standard in
determining what system of control is "best;" (2) in considering
costs 1t is not necessary to provide a cost-benefit analysis;
27Portlant Cement Association v Ruckelshaus, 486 F. 2nd
375 (U.C. Cir. 1973); Essex Chemical Corp. v Ruckelshaus, 486
F. 2nd 427 (D.C. Cir. 1973).
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(3) EPA Is not required to justify standards that require different
levels of-control in different industries unless such different
standards may. be unfairly discriminatory; and (4) it is
sufficient for EPA to show that a standard can be achieved
rather than that it has been achieved by existing sources.
Promulgation of standards of performance does not prevent
State or local agencies from adopting more stringent emission
limitations for the same sources. On the contrary section 116
of the Act (42 USC 1857-D-l) makes clear that States and other
political subdivisions may enact more restrictive standards.
Furthermore, for heavily polluted areas, more stringent standards
may be required under section 110 of the Act (42 USC 1857c-5) in
.order to attain or maintain national ambient air quality standards
prescribed under section 109 (42 USC 1857c-4). Finally, section 116
makes clear that a State may not adopt or enforce less stringent
standards than those adopted by EPA under section 111.
Although it is clear that standards of performance should be
in terms of limits -tin"emissions where feasible,-'' an alternative
method of requiring control of air pollution is sometimes
necessary. In some cases physical measurement "of emissions
from a new source may be impractical or exorbitantly expensive.
37"'Standards of performance,' ... refers to the degree of
emission control which can be achieved through process changes,
operation changes, direct emission control, or other methods. The
Secretary [Administrator] should not make a technical judgment
as to how the standard should be implemented. He should determine
the achievable limits and let the owner or operator determine the
most economical technique to apply." Senate Report 91-1196.
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For example, emissions of hydrocarbons from storage vessels for
petroleum liquids are greatest during storage and tank filling.
The nature of the emissions (high concentrations for short
periods during filling and low concentrations for longer
periods during storage) and the configuration of storage tanks
make direct emission measurement highly impractical. Therefore,
a more practical approach to standards of performance for
storage vessels has been equipment specification.
C. Selection of Categories of Stationary Sources
Section 111 directs the Administrator to publish and from
time to time revise a list of categories of sources for which
standards of performance are to be oroposed. A cateaory is to
be selected "... if [the Administrator] determines it may contribute
significantly to air pollution which causes or contributes to the
endangerment of public health or welfare."
Since passage of the Clean Air Amendments of 1970, considerable
attention has been given to the development of a system for
assigning priorities to various source categories. In brief,
the approach that has evolved is as follows.
First, we assess any areas of emphasis by ^considering the
broad EPA strategy for implementing the Clean Air Act. Often,
these "areas" are actually pollutants which are primarily emitted
by stationary sources. Source categories which emit these
pollutants are then evaluated and ranked by a process involving
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such factors as (1) the level of emission control (if any)
already required by State regulations; (2) estimated levels
of control that might result from standards of performance for the
source category; (3) projections of growth and replacement
of existing facilities for the source category; and (4) the
estimated incremental amount of air pollution that could be
prevented, in a preselected future year, by standards of
performance for the source category.
After the relative ranking is complete, an estimate
must be made of a schedule of activities required to develop
a standard. In some cases, it may not be feasible to immediately
develop a standard for a source category with a very high
priority. This might occur because a program of research
and development is needed or because techniques for sampling
and measuring emissions may require refinement before study
of the industry can be initiated. The schedule of activities
must also consider differences in the time required to complete
the necessary investigation for different source categores.
Substantially more time may be necessary, for example, if a
number of pollutants must be investigated in a single source
category. Even late in the development process the
schedule for completion of a standard may change. For
example, inability to obtain emission data from
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well-controlled sources In time to pursue the development
process 1n a systematic fashion may force a change in
scheduling.
Selection of the source category leads to another major
decision: determination of the types of sources or facilities
to which the standard will apply. A source category often
has several facilities that cause air pollution. Emissions
from some of these facilities may be insignificant and, at the
same time, very expensive to control. An investigation of
economics may show that, within the costs that an owner could
reasonably afford, air pollution control is better served by
applying standards to the more severe pollution problems. For
this reason (or perhaps because there may be no adequately
demonstrated system for controlling emissions from certain
facilities), standards often do not apply to all sources within
a category. For similar reasons, the standards may not apply
to all air pollutants emitted by such sources. Consequently,
although a source category may be selected to De covered by a
standard of performance, treatment of some of the pollutants or
facilities within that source category may be deferred.
D. Procedure for Development of Standards of Performance
Congress mandated that sources regulated under section 111
of the Clean Air Act be required to utilize the best practicable
air pollution control technology that has been adequately
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demonstrated at the time of their design and construction. In so
doing, Congress sought to:
1. maintain existing high-quality air,
2. prevent new air pollution problems, and
3. ensure uniform national standards for new facilities.
The selection of standards of performance to achieve the
Intent of Congress has been surprisingly difficult. In general,
the standards must (1) realistically reflect best demonstrated
control practice; (2) adequately consider the cost of such control;
(3) be applicable to existing sources that are modified as well
as new installations; and (4) meet these conditions for all
variations of operating conditions being considered anywhere in
the country.
A major portion of the program for development,of standards
is spent identifying the best system of emission reduction which
"has been adequately demonstrated" and quantifying the emission
rates achievable with the system. The legislative history of
section 111 and the court decisions referred to above make clear
that the Administrator's judgment of what is adequately demonstrated
is not limited to systems that are in actual rodtine use.
Consequently, the search may include a technical assessment
of control systems which have been adequately demonstrated but
for which there is limited operational experience. To date,
determination of the "degree of emission limitation achievable"
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has been commonly based on (but not restricted to) results
of tests of emissions from existing sources. This has
required worldwide investigation and measurement of emissions
from control systems. Other countries with heavily populated,
industrialized areas have sometimes developed more effective
systems of control than those used in the United States.
Because the best demonstrated systems of emission reduction may
not be in widespread use, the data base upon which the standards
are established will necessarily be somewhat limited. Test
data on existing well-controlled sources are an obvious starting
point in developing emission limits for new sources. However,
since the control of existing sources generally represents
retrofit technology or was originally designed to meet an
existing State or local regulation, new sources may be able
to meet more stringent emission standards. Accordingly, other
information must be considered and judgment is necessarily
involved in setting proposed standards.
Since passage of the Clean Air Amendments of 1970, a
process for the development of a standard has evolved. In
general, it follows the guidelines below.
1. Emissions from existing well-controlled sources
are measured.
2. Data on emissions from such sources are assessed with
consideration of such factors as: (a) the representativeness
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of the source tested (feedstock, operation, size, age,
etc.); (b) the age and maintenance of the control
equipment tested (and possible degradation in the
efficiency of control of similar new equipment even
with good maintenance procedures); (c) the design
uncertainties for the type of control equipment being
considered; and (d) the degree of uncertainty affecting
the judgment that new sources will be able to achieve
similar" levels of control.
During development of the standards, information from
pilot and prototype installations, guarantees by vendors
of control equipment, contracted (but not yet constructed)
projects, foreign technology, and published literature
are considered, especially for sources where "emerging"
technology appears significant.
Where possible, standards are set at a level that is
achievable with more than one control technique or
licensed process.
Where possible, standards are set to encourage (or at least
permit) the use of process modifications or new processes
as a method of control rather than "add-on" systems of
air pollution control.
Where possible, standards are set to permit use of
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systems capable of controlling more than one pollutant ,
(for example, a scrubber can remove both gaseous and
particulate matter emissions, whereas an electrostatic
precipitator is specific to particulate matter).
7. Where appropriate, standards for visible emissions are
established in conjunction with mass emission standards.
In such cases, the standards are set in such a way that
a source meeting the'mass emission standard will be able
to meet the visible emission standard without additional
controls. (In some cases, such as fugitive dust, there
is no mass standard).
Finally, when all pertinent data are available, judgment
is again required. Numerical tests may not be transposed directly
into regulations. The design and operating conditions of those
sources from which emissions were actually measured cannot be
reproduced exactly by each new source to which the standard of
performance will apply.
E. How Costs are Considered
Section 111 of the Clean Air Act requires that cost be
considered in setting standards of performanceT To do this requires
an assessment of the possible economic effects of implementing
various levels of control technology in hew plants within a
given industry. The first step in this analysis requires the
generation of estimates of installed capital costs and annual
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operating costs for various demonstrated control systems,
each control system alternative having a different overall
control capability. The final step in the analysis 1s to
determine the economic Impact of the various control alternatives
upon a new plant 1n the Industry. The fundamental question to
be addressed in this step is whether or not a new plant would
be constructed given that a certain level of control costs would
be Incurred. Other Issues that would be'analyzed 1n this step
would be the effects of control costs upon product prices and the
effects on product and raw material supplies and producer
profitability.
The economic impact upon an industry of a proposed standard
1s usually addressed both 1n absolute terms and by comparison
with the control costs that would be incurred as a result
of compliance with typical existing State control regulations.
This incremental approach 1s taken since a new. plant would
be required to comply with State regulations 1n the absence
of a Federal standard of performance. This approach requires
a detailed analysis of the impact upon the industry resulting
from the cost differential that usually exists between the
standard of performance and the typical State standard.
It should be noted that the costs for control of air
pollutants are not the only control costs considered. Total
environmental costs for control of water pollutants as well
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as air pollutants are analyzed wherever possible.
A thorough study of the profitability and price-setting
mechanisms of the Industry is essential to the analysis so
that an accurate estimate of potential adverse economic impacts
can be made. It is also essential to know the capital requirements
placed on plants in the absence of Federal standards of performance
so that the additional capital requirements necessitated by these
standards can be placed in the proper perspective. Finally, it
is necessary to recognize any constraints on capital availability
within an industry as this, factor also influences the ability
of new plants to generate the capital required for installation
of the additional control equipment needed to meet the standards
of performance. •.....•
The end result of the analysis is a presentation of costs
and potential economic impacts-for a series of control
alternatives. This information is then a major factor which
the Administrator considers in selecting a standard.
F. Impact on Existing Sources
Proposal of standards of performance may affect an existing
source in either of two ways. First, if modiffed after
proposal of the standards, with" a subsequent increase in
air pollution, it is subject to standards of performance as
if it were a new source. (Section 111 of the Act defines a
new source as "any stationary source, the construction or
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modification of which is commenced after the regulations are
proposed.")—'
Second, promulgation of a standard of performance requires
States to establish standards of performance for the same pollutant
for existing sources in the same industry under section lll(d) of
the Act; unless the pollutant limited by the standard for new
sources is one listed under section 108 (requiring promulgation of
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national ambient air quality standards) or one listed as a
hazardous pollutant under section 112. If a State does not act,
EPA must establish such standards. Regulations prescribing
procedures for control of existing sources under section lll(d)
will be proposed as Subpart B of 40 CFR Part 60.
G. Revision of Standards of Performance
Congress was aware that the level of air pollution control
achievable by any industry may improve with technological
advances. Accordingly, section 111 of the Act provides that
the Administrator may revise such standards from time to time.
Although standards proposed and promulgated by EPA under section 111
are designed to require installation of the "... best system of
emission reduction ... (taking into account the- cost)..."
the standards will be reviewed periodically. Revisions will be
proposed and promulgated as necessary to assure that the standards
37Specific provisions dealing with modifications to existing
facilities are being proposed by the Administrator under the
General Provisions of 40 CFR Part 60.
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continue to reflect the best systems that become available
in the future. Such revisions will not be retroactive but
will apply to stationary sources constructed or modified after
proposal of the revised standards.
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TABLE OF CONTENTS
I. THE FERROALLOY INDUSTRY 1
A. General , 1
B. Processes or Facilities and Their Emissions 6
II. PROPOSED STANDARDS OF PERFORMANCE 15
A. Standards of Performance as Proposed. 15
B. Discussion of Proposed Mass Standards 15
C. Discussion of Proposed Opacity Standards 18
III. EMISSION CONTROL TECHNOLOGY 21
A. Open Furnace 21
B. The Semi-Enclosed Furnace 24
C. The Sealed Furnace 28
D. Control of Fumes During Tapping 31
IV. ENVIRONMENTAL EFFECTS 33
A. Impact on Air Pollution 33
B. Impact on Water Pollution 37
C. Impact on Solid Waste Pollution 38
D. Energy Considerations 39
V. SUMMARY OF THE PROCEDURE FOR DEVELOPING STANDARDS 41
A. Literature Review and Industrial Contacts 41
B. Selection of Pollutants and Affected Facilities 42
C. Plant Inspections 44
D. Sampling and Analytical Procedures 4$
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E. Emission Measurement Program 46
F. Units of the Standard 47
G. Development of Proposed Standards 48
VI. DATA TO SUBSTANTIATE A STANDARD 51
A. Concentration and Mass Data •• 51
B. Visible Emission Data 61
VII. SUMMARY OF ECONOMIC INFORMATION 65
A. Introduction.. •• 65
B. Model Plants 66
C. Control Costs 68
D. Discussion of the Control Costs 84
E. Economic Impact 87
VIII. ALTERNATIVE STANDARDS 89
A. Alternative Standards for Particulate Matter 89
B. Alternative Standards for Carbon Monoxide (CO) 99
C. Alternative Standards for Visible Emissions 101
IX. ENFORCEMENT ASPECTS OF THE PROPOSED STANDARDS. 103
A. Particulate Matter Standard 103
B. Visible Emissions Standard 107
C. Carbon Monoxide Standard 107
D. Emission Monitoring , 1°8
E. Monitoring of Operations 108
X. MODIFICATIONS • HI
A. Open Furnaces H3
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B. Semi-Enclosed Furnaces
C. Sealed Furnaces
113
113
XI. MAJOR ISSUES CONSIDERED 115
XII. REFERENCES
A. Cited References ..
B. General References
TECHNICAL REPORT DATA
135
135
145
147
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I. THE FERROALLOY INDUSTRY
A. General
A ferroalloy is "a crude alloy of iron with one or more other elements
(as metals) used for deoxidizing molten steels and making al,loy steels. '
A list of the major ferroalloys and their manufacturing processes is shown
in Table 1-1. Calcium carbide, although not a ferroalloy, is produced at
ferroalloy plants by a process similar to that for ferroalloys. For purposes
of this report, "ferroalloys" will include calcium carbide unless otherwise
specified.
The United States is the world's largest producer and user of ferroalloys.
In 1971, about 2,331,000 tons of ferroalloys valued at about 558 million
(2)
dollars were produced by the United States ferroalloy industry/ Another
400,000 tons of high-carbon ferromanganese were manufactured by the iron
and steel industry in blast furnaces. An additional 380,000 tons of
ferroalloys were imported. During the 10 years prior to 1972, the United
States' consumption of ferroalloys increased at an average annual rate of
(3)
2 percent while average production increases were 1.5 percent per year.
Table 1-2 shows the companies, plant locations, plant sizes, products, furnace
types and number of furnaces for each domestic producer for the year 1971.
(4)
In 1971 the industry employment was about 10,100 persons.
Section lll(b)(l) of the Clean Air Act, as amended, requires that the
Environmental Protection Agency develop standards of performance for
sources which "cause or contribute to the endangerment of public health
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Table 1-1
Major Ferroalloys and Their Manufacturing Processes
Submerged-are furnace process -
Exothermic process -
Electrolytic process -
Vacuum furnace process -
Induction furnace process
Silvery iron
50% Ferrosilicon
65-75% Ferrosilicon
Silicon metal
Calcium silicon
Silicomanganese zirconium (SMZ)
High-carbon (HC) ferromanganese
Silicomanganese
Ferromanganese silicon
Charge chrome and HC ferrochrome
Ferrochrome silicon
Calcium carbide
Low-carbon (LC) ferrochrome
LC ferromanganese
Medium-carbon ; (MC) ferromanganese
Chromium metal, FeTi, FeV and FeCb
Chromium metal
Manganese metal
LC ferrochrome
Ferrotitanium
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or welfare." The major pollutant from ferroalloy plants is participate
matter, a pollutant for which ambient air quality standards were
promulgated in 40 CFR 50. The health effects data necessary to issue
air quality criteria are based on non-specific particulate matter. In
addition, particulate matter emissions result in the deleterious effects
of soiling, nuisance properties, reduction of visibility and modification
of atmospheric conditions. Ferroalloy plants were specifically mentioned
in a Report of the Committee on Public Works, United States Senate,
as a source category to which standards of performance for new sources
could be expected to apply.^ '
The rate of particulate matter emissions from the United States ferroalloy
industry in 1967 is estimated to have been 160,000 tons per year/6'
This total consists of 1,000 tons from blast furnaces, 150,000 tons from
electric submerged-arc (ESA) furnaces, and 9,000 tons from handling of
materials. The estimate of 150,000 tons of emissions from ESA furnaces
assumes an average control efficiency of about 40 percent. It has been
estimated that in 1^70 about 50 percent of the existing ESA furnace capacity
operating in the United States was equipped with particulate matter emission
control systems which had efficiencies ranging from 75 to 99 percent (including
capture and treatment of tap fumes). ' Obviously the major source of
ferroalloy plant particulate matter emissions is the ESA furnace. It is
therefore the primary candidate for standards of performance for new sources.
There are several processes, which are minor sources of emissions
compared to the ESA furnace, for which standards are not now being
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recommended. These processes, listed below, are candidates for standards
which may be developed in the future:
. The electrolytic process
. Vacuum and induction furnaces
. Product sizing
. Raw materials handling and preparation
There are only six electrolytic process operations in the United States
ferroalloy industry. These produce chromium, manganese, and manganese
dioxide. The electrolytic process results in emissions of ammonia and
(8)
sulfur oxides.v '
Vacuum and induction furnaces are used to produce ferroalloys at fewer
than five locations in the United States.
The final ferroalloy products are marketed in sizes ranging from
75-pound pieces to fine powders. Several types of crushers and screens
are used for sizing the products. Although the amount of particulate matter
emitted from crushing and screening operations has not been quantified,
it is substantially less than particulate matter emissions from ESA furnaces.
About half of the existing ferroalloy plants have air pollution abatement
(Q]
equipment for these operations. ' No measurements of emissions from
ferroalloy crushing and sizing operations have been made by EPA.
Raw materials such as ores, quartz or quartzite, limestone, scrap
steel, coke, and coal are delivered to ferroalloy plants by ship,
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railroad cars, or trucks and then are normally transferred to outdoor
storage piles. These materials range 1n size from 5 Inches to 1/4 Inch,
but contain significant quantities of dust. Entrainment of the dust by
wind may be minimized by sheltering the storage piles with block walls,
snow fences, or plastic covers, or by spraying with water.
Additional dust may be generated during loading, unloading, transferring,
and pretreatment of this raw material. Pretreatment may include operations
such as crushing, sizing, drying, mixing, pelletlzing, and sintering.
Standards of performance for these operations are not recommended at this
time but may be considered 1n the future.
B. Processes or Facilities and Their Emissions
1. The electric submerged-arc furnace production process.
A typical flow diagram of ferroalloy production is shown in
Figure 1-1. As discussed previously, the major source of pollution
1s the electric submerged-arc furnace which performs the smelting
operation. The furnace (Figure 1-2) consists of a hearth lined
with a high-temperature refractory which has holes to permit tapping
(or draining) of metal and slag. The furnace shell and its hood or
cover components are fabricated from steel. These are water cooled
to protect them from the heat of the process* Above the hearth are
three carbon electrodes vertically suspended 1n a triangular formation.
Although these electrodes may be prebaked or of the self-baking,
1n situ Soderberg type, the trend 1s to use the Soderberg electrodes.
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Electrodes extend three to five feet into the charge materials.
Three-phase current arcs through the charge material from electrode
to electrode. The charge melts as the electrical energy is converted
to heat. Coke added to the furnace chemically reacts wiih the oxygen
in the metal oxides to form carbon monoxide and reduce the ores to
base metal. Large quantities of by-product carbon monoxide are formed.
These reaction gases entrain particulate matter and carry them from
the furnace.
Power is applied continuously to the ESA furnace. Feed materials
may be charged continuously or intermittently. Molten ferroalloy c id
slag are intermittently tapped into ladles from ports in the lower
furnace wall. (Furnaces producing calcium carbide may be intermittently
or continuously tapped.) From the ladles, the melt is poured into
molds or casting machines. After the product cools and solidifies,
it is crushed, sized, loaded and shipped to customers.
2. Emissions from ESA furnaces.
A study of emissions from the United States ferroalloy industry by
EPA and The Ferroalloys Association was completed in 1973. During this
study, which began before promulgation of the Clean Air Act Amendments
of 1970, EPA measured emissions from several ferroalloy furnaces and
collected samples of emissions for chemical analysis from open furnaces
producing ferrochrome-silicon, silicomanganese, and high-carbon ferro-
chrome. (Open, semi-enclosed, and sealed furnaces are described in
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Chapter III of this document.) in addition, metals analyses were
performed on samples of manganese ore, chrome ore, and ferromanganese
slag used as charge material for a silicomanganese furnace.
No significant concentrations of sulfur dioxide were found in
the exhaust gases from five furnaces tested by EPA. S02 concentrations
ranged from 1 to 17 ppm and emissions did not exceed 7 pounds per
hour.
(10)
A significant amount of carbon monoxide gas is formed as a by-
product of the ESA reduction process. Depending on the type of
furnace, this gas is either burned at the surface of the charge
material or captured by the emission control system. If the latter,
it may be flared at the stack of the collection device or used for
fuel or other chemical processes.
No nitrogen oxides are formed during the carbon reduction of
oxidic ores.
Particulate matter emissions, the major pollutant in this industry, may
vary from 150 to 2,000 pounds per hour from an uncontrolled ESA furnace.
The actual rate depends on:^
. The type of alloy produced.
. Choice and size of raw materials.
. Operating techniques.
Existence of a furnace shutdown or start-up condition.
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Chemical analyses of samples of participate emissions revealed
no significant amounts of heavy metals such as mercury, beryllium,
(12}
cadmium, or arsenic./ ' The physical properties and quantities
of particulate matter emitted generally depend upon the alloy beinq
produced, but the particle size is usually below 2 microns. The
mass median diameter (the diameter at which 50 percent of the
particles by weight are smaller and 50 percent are larger) of
emissions from open furnaces producing ferrochrome silicon,
silicomanganese, and high-carbon ferrochrome has been measured by
EPA as between 0.66 to 1.7 micron.'13^
The type of alloy produced affects the quantity of uncontrolled
emissions. Uncontrolled particulate matter emissions from open
furnaces tested by EPA (excluding tap fumes) varied from 25 to 144
pounds per megawatt-hour of power consumption for furnaces producing
ferrochrome silicon and silicon metal. The uncontrolled particulate
matter emission rate will also vary for different grades of a given
product. For instance, the rate of uncontrolled emissions will
increase with increasing silicon content of the product, so that
a furnace will emit more particulate matter when producing 75 percent
than when producing 50 percent ferrosilicon.
11
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The type and size of raw material also affects the emission rate.
A porous charge promotes uniform gas distribution and furnace operating
stability. Very fine materials may promote channelization of gas flow
through the furnace charge, and bridging and nonuniform descent of charge
materials. Collapse of a bridged area causes a momentary surge of gas
which results in unstable furnace operation. Another factor which
influences furnace operation and emissions is the volatile content
of the charge material, including moisture and undesirable chemicals.
The design of the furnace and its power consumption affect the
rate of uncontrolled emissions. A covered or sealed furnace without
control is reported to generate less emissions than an equivalent
open furnace without control/14' Uncontrolled emissions from a
furnace producing a given alloy are related to furnace production
which is a function of power consumption/ ''
Differences in operating techniques can also significantly affect
/1g\
the uncontrolled emissions from a furnace/ ' Operation at higher
voltages requires the electrodes to be positioned higher, resulting
in increased emissions. Poor placement of mix or insufficient feed
rate of the mix increases emissions through the open, annular areas
around the electrodes of a semi-enclosed furnace. Manufacture of
silicon metal requires stoking of the charge to break up crust,
permitting uniform evolution of reaction gases, and preventing
12
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violent jets of gas emanating from the furnace reaction zone.
Emissions can vary depending upon the frequency and adequacy of
stoking.
Furnace shutdowns may be caused by broken electrodes, water leaks,
tap hole problems, utility failures, and many other reasons. Upon
start up after short shutdown periods, uncontrolled emissions return
to normal levels in a time period approximately equal to the length
of interruption. When starting up a new furnace or one which has
been shut down for a long time period, heavier-than-norinal uncontrolled
emissions may occur for a period varying from a few days to several weeks.
Emissions from existing ferroalloy furnaces are restricted by
State regulations. These are all of the process weight type and most
are the result of State implementation plans developed pursuant to
section 110 of the Clean Air Act, as amended. Since production rate is a
function of the product being manufactured, allowable emissions must
be calculated for the particular alloy being produced. For example,
allowable emissions from a 30-megawatt furnace located in Ohio producing
calcium carbide, silicomanganese, and ferromanganese are about 29, 32,
and 46 pounds per hour respectively (0.97 to T.5 pounds per megawatt-
hour furnace power consumption). ' It is doubtful that these
regulations can be attained without control of tapping fumes.
Consequently, it would appear that with proper enforcement, the
State regulations will require installation of control systems which
will minimize emissions during the tapping operation.
13
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II. PROPOSED STANDARDS OF PERFORMANCE
A. Standards of Performance as Proposed
The proposed standards of performance for ferroalloy plants limit
the discharge of particulate matter as follows:
No owner or operator shall cause to be discharged to the atmosphere
from any affected facility any qases'which:
1. Contain participate matter in excess of 0.45 kg/Mw-hr
(0.99 Ib/Mw-hr) while that facility produces silicon
metal, ferrosilicon (50 percent silicon and above),
calcium silicon, or silicomanganese zirconium.
2. Contain particulate matter in excess of 0.23 kg/Mw-hr
(0.51 Ib/Mw-hr) while that facility produces high-carbon
ferrochrome, charge chrome, standard ferromanganese,
silicomanganese, calcium carbide, ferrochrome silicon,
ferromanganese silicon, or silvery iron.
3. Exhibit 20 percent opacity or greater. This opacity
requirement shall apply to all gas streams from the
affected facility except as follows:
(i) Any emissions which escape the furnace hood or cover shall not
be visually detectable without the aid of instruments.
(ii) Any emissions which escape the control device at the tapping
station shall not be visually detectable without the aid of
instruments for more than 40 percent of each tapping period.
15
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This requirement applies to fumes which may escape the device
(required by the standard) used to capture tapping fumes.
(iii) Any emissions from the dust handling equipment shall not
exhibit 10 percent opacity or greater.
The proposed standards limit the discharge of carbon monoxide as
follows:
No owner or operator shall discharge or cause the discharge into
the atmosphere from any affected facility any gases which contain
20 or greater volume percent of carbon monoxide, dry basis.
Combustion of carbon monoxide under conditions acceptable to the
Administrator shall constitute compliance with this paragraph. Acceptable
conditions include but are not limited to flaring of gases or use of gases
as fuel for other processes such as plant boilers or raw material dryers.
B. Discussion of Proposed Mass Standards
The proposed standards for particulate matter and visible emissions
can be achieved with open, semi-enclosed and sealed furnaces with appro-
priate hooding and air pollution control devices (i.e. venturi scrubbers,
venturi scrubbers in series with electrostatic precipitators, or fabric
filters). As pointed out in Chapter VIII, a standard was considered which
would encourage the use of sealed furnaces for those ferroalloy products
that can be produced in sealed furnaces; however, such a standard has a
major disadvantage in that it would restrict the flexibility of new furnaces
to respond to fluctuating market demands. A specific sealed furnace can be
16
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used to produce only one family of products. The sealed furnace cannot
be adapted to the production of other ferroalloys without changing the
electrode spacings (which are determined by the product family). To
do this on a sealed furnace also requires replacing the furnace cover.
Thus, modification of sealed furnaces to produce other products is pro-
hibitively expensive. Product flexibility is possible at minimum cost
with open furnaces which have multiple transformer taps and adjustable
electrodes.
The industry has alleged that a standard requiring sealed furnaces
(with their attendant limited product flexibility) would severely handicap
the small domestic producers: (1) It would eliminate his ability to
respond to a rapidly changing world market. (2) Only large companies
with adequate capital and marketing capabilities could commit a large
furnace to one product line. (3) Since a few large sealed furnaces
could supply the entire United States market for select materials, a
large company could install several and drive the small producer from
the market, thereby eliminating domestic competition.
EPA attempted to determine the need for furnace flexibility. Data
were obtained on various products made in each furnace over a 5 to 10-year
period from several United States ferroalloy producers, both large and
small. Some furnaces were reported to have been changed from one product
to another quite frequently while other furnaces produced the same product
for the entire period reported. This was true of both large and small
companies. Market conditions can fluctuate rapidly in the ferroalloy
17
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industry, however, so it is understandable why product flexibility
is advantageous. For these reasons, we are proposing a standard
which will allow open furnaces to be used in conjunction with the
best available control equipment for open furnaces. The standard is
also readily achievable by using sealed furnaces with adequate con-
trol equipment.
EPA's Control Systems Laboratory has contracted for a long-term
study to further investigate the issue of product flexibility. That
study could ultimately result in standards of performance based on
sealed furnaces.
C. Discussion of Proposed Opacity Standard
The visible emission regulations on emissions from the furnace hood
or cover and the tapping station were established to make enforcement
simpler. The revised regulations no longer require discerning opacities
in order to determine compliance. The proposed standard specifies no
visually detectable emissions without the aid of instruments. This pro-
posal does not require a distinction to be made between different opacity
levels because the observations are made inside the shop and the criteria
of Reference Method 9 for determining the opacity of emissions cannot be
followed. The distinction between no visible emissions and the existence
of visible emissions can be made however. The emission from the furnace
hood or cover and the tapping station are a significant portion of the
18
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furnace's total emissions. The no visible emissions limitation is
intended to require very good capture of these emissions.
In the case of hoods or covers used to capture fumes generated
within the furnaces, the standard requires that fumes which escape capture
by the furnace hood or cover be invisible at all times. This require-
ment is supported by observations at four open furnaces and several
sealed furnaces. (See Chapter VI.)
The visible emission limitation on fumes from the tapping station
is based on observations of one tap hood during two tapping periods.
These data are summarized in Chapter VI. During these two tapping periods,
no visible emissions were observed escaping the hood for 71.4 percent of
the time during the first tapping period, and 73 percent of the time
during the second tapping period. The remainder of the time, emissions
of various opacities escaped capture by the hood. The proposed standard
was established to require no visible emissions for at least 60 percent
of the time because the best system observed had some fumes escaping the
collector system at the tapping station, and to allow a margin of safety
between the data base (71.4 to 73 percent of the tapping with no visible
emissions) and the proposed standard, the proposed standard still requires
very good collection and control of tapping fumes.
The proposed standard limits the opacity of fugitive emissions from
the dust handling system at or near the control device to less than 10
percent to be consistent with the observed levels of 0 percent opacity
19
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and allow a small margin of safety. Thi-s proposed limitation is based
on observations of dust handling equipment in the steel and asphalt
concrete industries.
20
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III. EMISSION CONTROL TECHNOLOGY
Air pollution from the electric submerged-arc furnace is minimized
by good capture of fumes at the furnace and use of an appropriate
particulate matter collection device. The three different furnace
configurations—open, semi-enclosed, and sealed—strongly affect the
efficiency of air pollution control. In each type, the hood or cover
above the furnace not only collects emissions but also protects the
furnace superstructure and electrode column components. The three types
of furnaces and common control devices are discussed below. Emissions
from controlled furnaces of each of three types are discussed and compared
in Chapter VI, Data to Substantiate a Standard.
A. Open Furnace
The open furnace (Figure III-l) has a water-cooled canopy hood, normally
located 6 to 8 feet above the furnace crucible rim. This large opening
between the furnace crucible and hood permits large quantities of ambient
air to be drawn into the air pollution control system diluting the furnace
off-gas by as much as 50 to I/18' As the air combines with the hot
furnace gases, it combusts the carbon monoxide generated in the furnace.
Gas volumes from this type of system range from 100,000 to 400,000 standard
cubic feet per minute (scfm).^ ' Gas volume can be reduced by decreasing
the opening between the furnace and hood. This may be done by adding a
skirt to the hood or with chain curtains (lengths of chain hung in close
proximity around the perimeter of the hood).
21
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Gas cleaning devices used on open ferroalloy furnaces Include high-
energy venturi scrubbers, electrostatic precipitators, and fabric filters.
1. Venturi scrubbers applied to open furnaces.
Several designs of venturi scrubbers are used in the United
States, but the one most common on open furnaces is the flooded-disc
type. Because the particulate matter concentration is relatively
low (the result of copious dilution air) and a high proportion of
the particulate is submicron, these scrubbers must operate with very
high pressure losses of 60 to 80 inches water gauge to achieve removal
efficiencies of 96 to 99 percent. The venturi scrubber for an open
30-megawatt furnace producing silicomanganese requires 2,500 horsepower
for the fan alone. The power required to operate these high-energy
scrubbers is equivalent to approximately 10 percent of the power
requirements for the furnace itself.^20^' ^21^
2- Electrostatic precipitators applied to open furnaces.
Only two modern electrostatic precipitators are operating on
ferroalloy furnaces in the United States. Both are installed on
open furnaces producing chrome alloys.
Most fumes from ferroalloy furnaces do not have proper electrical
resistivity for satisfactory precipitator operation unless the gases
are humidified and conditioned with agents such as ammonia, or their
temperatures are maintained above 500°F.
23
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3. Fabric filters applied to open furnaces.
Fabric filter collectors, also referred to as baghouses or bag
filters, are frequently used with open furnaces. The most common
type used in the United States is pressurized (fan on the inlet)
and exhausts through an open top or monitor. Open grates at the
bottom of the baghouse permit cooling by natural convection. Radiant
coolers or dilution with cool, ambient air is used if the gas must
be cooled before it enters the baghouse. Cooling with water sprays
is much less common. Both felted and woven fabrics of many different
materials have been used. Cleaning of the bags may be done by either
reverse air or mechanical shaking. Air-to-cloth ratios vary between
1.2 and 2 actual cubic feet per minute (acfm) per square foot of cloth
area. Because the particulate matter has both a high proportion of
submicron particles and high electrostatic charge, the pressure drop
across a filter fabric is relatively high, 10 to 18 inches of water.
B. The Semi-Enclosed Furnace
The semi-enclosed furnace (Figure III-2) has a water-cooled cover which
contains gas and fume generated in the furnace. These emissions are drawn
from beneath the cover through one or more ducts to a gas cleaning device.
The cover completely seals the furnace except for annular spaces around
the three electrodes through which raw material is charged. The feed
material only partially closes the annuli and emissions still pass through
them. These leaks could be eliminated or minimized in two ways. The air
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pollution control system could be designed to maintain a negative pressure
within the furnace or the emissions could be captured and controlled by
hoods around the electrodes.
Because very little air enters a semi-enclosed furnace, the gases from
the furnace are rich in carbon monoxide and can be used as fuel.
l
Semi-enclosed furnaces have not been used to produce silicon metal
or alloys containing over 75 percent silicon because of inability to stoke
the furnace. Stoking is necessary to prevent crusting and bridging of
the charge, and "blows" during production of high-silicon alloys.
Crusting and bridging prevent uniform descent of the charge into the
furnace and blows may damage the furnace components. "Blows" are jets
of extremely hot gas that originate in the high-temperature reaction
zone in the vicinity of the electrode tips, and emerge around the
electrodes at high velocity.
1. Wet scrubbers applied to semi-enclosed furnaces.
Wet scrubbers are the most common air pollution control devices
applied to semi-enclosed ferroalloy furnaces. Both multistage
centrifugal scrubbers and venturi scrubbers are used. Centrifugal
scrubbers are generally limited to a maximum air flow of about
(22)
2,800 acfm, sufficient for a medium-size semi-enclosed furnace.
For larger furnaces, parallel centrifugal scrubbers or a venturi
scrubber are used. Depending on the product being made, centrifugal
scrubbers may have efficiencies of up to 99 percent; venturi scrubber
26
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efficiencies are higher. Pressure losses of up to 80 Inches of water
are common 1n venturi scrubbers controlling emissions from semi-
enclosed furnaces. Power and water requirements are generally
higher for Venturis than for centrifugal scrubbers.
Emissions from two semi-enclosed furnaces were measured by EPA.
One was a 40 to 50 megawatt furnace which produces 50 percent
ferrosilicon and is controlled by a venturi scrubber. The other is
a 24 megawatt calcium carbide furnace controlled by a centrifugal
scrubber. During these tests, large amounts of dust were emitted
from the annular openings at the electrodes. These emissions were
not controlled and so reduced the overall control efficiency. Emissions
from the scrubber on the furnace producing ferrosilicon averaged 0.078
pound per Mw-hr (3.6 pounds per hour); however, measurements of fugitive
emissions from around the electrodes indicated a total emission rate of
about 390 pounds per hour. Emissions from the calcium carbide furnace
scrubber averaged 0.017 pound per Mw-hr (0.40 pound per hour); however,
measurements of fugitive and tap emissions which were uncontrolled
indicated a total emission rate of about 4.0 pounds per Mw-hr (96
pounds per hour) for this furnace. Obviously, the emissions from the
electrode ports are of major concern in a semi-enclosed furnace.
2. Electrostatic precipitators and fabric filters applied to
semi-enclosed furnaces.
No known semi-enclosed furnaces are serviced by electrostatic
precipitators or fabric filters. Fabric filters, and an electrostatic
27
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precipitator in series with venturi scrubbers have been used on sealed
furnaces in Japan. The similarity in emissions from semi-enclosed
and sealed furnaces seems to imply that these control devices could
also be used on semi-enclosed furnaces. However, the semi-enclosed
furnace has a less positive seal. Air leaks through, the annuli at
the electrodes may increase the danger of explosion. This could
prevent use of fabric filters or electrostatic precipitators.
C. The Sealed Furnace
The tops of sealed furnaces (Figure III-3) have water-cooled covers
which prevent escape of any emissions from treatment by the air pollution
control system. Packing is used to seal around the electrodes and
charging chutes. No other openings are required since the furnaces are
not generally stoked. They are operated with a slight positive pressure
to prevent leakage of air into the furnace. The furnace exhaust gas,
predominantly carbon monoxide, can be used as fuel.
Because no air enters the furnace, gas volumes to the control device
are minimal and can be as little as 2 to 5 percent of that from an open
furnace of equivalent size. The very low gas volumes result in much lower
mass of particulate matter emissions from a controlled sealed furnace than
from an equivalent, well-controlled open furnace.
28
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29
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Sealed furnaces have not yet been used to produce silicon metal or alloys
containing over 75 percent silicon because of inability to stoke the furnace.
Stoking is necessary to prevent crusting and bridging of the charge, and
"blows" during production of high-silicon alloys.
1. Wet scrubbers applied to sealed furnaces.
r
Wet scrubbers are the most common device used to control air
pollution from sealed furnaces. Both multistage centrifugal and
venturi scrubbers are used. Their efficiency and energy requirements
for control of sealed furnaces are similar to those for semi-enclosed
furnaces.
2. Fabric filters applied to sealed furnaces.
Only one sealed ferroalloy furnace is known to use a fabric
filter for air pollution control. The baghouse is a closed suction
type cleaned by reverse gas flow. Air-to-cloth ratio is about 1.5
actual cubic feet per minute per square foot of cloth area. Gas from
the furnace is cooled in radiant coolers before entering the baghouse.
When necessary, additional cooling is obtained by running water over the
surface of the radiant coolers.
3. Electrostatic precipitators applied to sealed furnaces.
No applications are known in which electrostatic precipitators
alone are used with sealed ferroalloy furnaces. However, systems
consisting of two venturi scrubbers and a wet electrostatic
30
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predpltator, all in series, have been used to control emissions from
three sealed ferroalloy furnaces in Japan. The venturi scrubbers
serve as precleaners and gas conditioners and operate at relatively
low pressure drops (about 36 inches of water total). The precipitator
removes about 97 percent (according to EPA tests) of the particulate
remaining in the gas stream after the scrubbers.
D. Control of Fumes During Tapping
Best systems of emission reduction for ferroalloy furnaces of all
types includes capture and control of tapping fumes. A hood system
must be used over the tap hole and ladle to capture and direct tapping
fume to a gas cleaning device. The gas cleaning device may be common
to that controlling the furnace fume, or a separate fabric filter or
wet scrubber.
Efficient capture of tapping fumes has been difficult. One new hood
design encloses the ladle during tapping and can be retracted when tapping
is complete. When in place, it provides access to the tap hole. This
allows the hood to be in place to capture fume generated when the tap
hole is burned open with an oxygen lance, and also allows the tap hole
to be rodded during the tap to keep it open. This system provides very
good capture of the tapping emissions.
31
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IV. ENVIRONMENTAL EFFECTS
A. Impact on Air Pollution
The objective of standards of performance under section 111 of the
Act, as amended, is to prevent new air pollution problems from developing
by requiring affected facilities to use the best systems of emission
reduction available at a cost and within a time that is reasonable.
These standards pertain directly to emissions from the facility and
are only indirectly related to ambient air quality. Attainment and
maintenance of national ambient air quality standards is specifically
covered by State implementation plans as provided under section 110 of
the Act. Nevertheless, the impact of a new submerged arc ferroalloy
furnace on local ambient air quality should be closely investigated.
Such an investigation necessarily depends upon many specific factors
such as topography, meteorological conditions, proximity of other sources
of pollution and the mass of pollutants emitted from all sources in the
local area. As an illustrative example* maximum ground-level concentrations
of particulate matter were estimated for emissions from five hypothetical
sources employing the control systems of interest using an atmospheric
dispersion model. These estimates are shown in Table IV-1 for these
hypothetical point sources - control - system cases. Differing source confi-
gurations and surrounding terrain can cause significantly different results.
The maximum concentrations were estimated for 24-hour and 1-year averaging
periods for particulate matter. These averaging periods were selected
to permit direct comparison with the ambient air quality standard for
33
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particulate matter. Comparison of these maximum ground-level concentration
estimates with the national ambient air quality standard will not
necessarily indicate whether or not the standard (NAAqs) will be met
unless there is an estimate of background concentration arising from
natural and manmade sources available for the specific site. Cases 1 and
3 are based on emissions from a furnace operating in compliance with a
typical State process weight regulation. Cases 2 and 4 are based on
allowable emissions according to the proposed standards of performance
(Chapter II) and Case 5 is based on emissions of 0.07 Kg/Mw-hr, Alternative
flo. 1, Chapter VIII (Alternative Standards).
The dispersion estimates were made using a Gaussian point source
dispersion model developed by Meteorology Laboratory of EPA.
Because the pollutants emit from a monitor (no stack) on a baghouse in
Cases 1 through 4, aerodynamic downwash is a chronic problem, particularly
when wind speeds exceed 2 or 3 meters per second (mps). At very low wind
speeds the plume may rise, although probably not more than 20 meters.
Many of the nation's ferroalloy plants are in valleys in hilly country
such as West Virginia and eastern Ohio. Since it was readily available,
and the topography and climate are similar to West Virginia and eastern
Ohio, one year of hourly wind and surface stability data for Harrisburg,
Pennsylvania was used for the calculations.
35
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Maximum concentrations were estimated immediately downwind of the
source, and for distances of 0.3, 2, and 20 kilometers downwind. Because
of downwash, the overall maximum concentrations were likely to occur just
to the lee of the emission point. The 24-hour values are estimates of
typical high concentrations during any given year. Note that the 24-hour
primary national ambient air quality standard (NAAQS) for particulates
(260 yg/n? ) may be exceeded at distances of 0.2 to 1.0 kilometers
downwind, depending on the source. The annual NAAQS (75 yg/m3) may also
be exceeded, although not as far downwind and perhaps not at all when
a sealed furnace is used (Case 5).
As an indication of the degree of air pollution reduction achieved
by control systems on submerged arc ferroalloy furnaces, the emission
rates in Table IV-1 for controlled furnaces can be compared with estimated
uncontrolled emission rates of 270 grams per second (39 Kg/Mw-hr) for an
open, 25 Mw silicon furnace, and 190 grams per second (23 Kg/Mw-hr) for
an open, 30 Mw silicomanganese furnace.
Installation of systems to provide the best air pollution control
technology on all new plants will minimize the increase in emissions from
growth of the ferroalloy industry. By promulgating standards of
performance, there will be no incentive for a plant to locate in a State
which has less stringent standards. Without uniform standards of performance
36
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such an indirect inducement by State and local agencies could create
concentrations of industry and result in significant deterioration of
local air quality.
B. Impact on Water Pol TutIon
The control of air pollution from a ferroalloy plant need not affect
water pollution problems at all since fabric filter air pollution control
systems require no water. Scrubbers and electrostatic precipitators with
wet gas conditioners are potential major sources of water pollution.
Although up to 3,500 gallons of water per Mw-hr may be circulated through
a scrubber serving an open furnace, normally the water is clarified and
recirculated. As a result, the volume of actual waste water is much less
and is only that required to carry the sediment from the clarifier. Because
of the much larger volumes of exhaust gas from open furnaces, scrubbers
serving them have much larger water requirements than those for semi-
enclosed or sealed furnaces. This, of course, necessitates a larger water
treatment system for scrubber-equipped open furnaces.
The Environmental Protection Agency promulgated water effluent limitations
for the ferroalloy industry on February 22, 1974, (39 FR 6806).'23' For
new electric ferroalloy furnaces, the standard limits discharges of water
pollutants to levels attained by the "best available technology economically
achievable." Typically, chemical treatment, clarifier-flocculators, sand
filters, and recirculation would be required to meet the water effluent
standards for electric ferroalloy furnaces if scrubbers are used.
37
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C. Impact on Solid Waste Pollution
Increased recovery of participate matter normally emitted to the atmosphere
with the exhaust gases from a furnace can only increase the amount of solid
waste for disposal. This increased quantity of solid waste is a function
of the efficiency, not the type of the control device. Selection of the
type of device will determine if particulate is collected as a wet or dry
mass. Although the dry product from a fabric filter may be more prone to
re-entrainment than the sludge from a clarifier, it can easily be wetted
or pelletized to minimize wind losses during handling.
The domestic industry usually disposes of the collected material as
landfill. When this method is used practices similar to proper sanitary
landfill technology may be followed. The principles set forth in EPA's
Land Disposal of Solid Wastes Guidelines (CFR Title 40 of Chapter 1,
Part 241) may be used as guidance for acceptable land disposal techniques.
If hazardous materials are to be disposed of, landfill sites should be
selected to prevent horizontal or vertical migration of this contaminant
to surface or ground waters. Where geologic conditions may not reasonably
ensure this, adequate precautions such as impervious liners should be
taken to ensure long term protection to the environment. The location of
solid hazardous materials disposed of in this manner should be permanently
recorded in the appropriate office of the legal jurisdiction in which the
site is located.
38
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Although most of the dust captured is hauled to a landfill site, other
dispositions are possible. In some foreign ferroalloy plants, the dust
captured by the control system is palletized or sintered and returned to
the furnace as feed. Some of the dust captured by baghouses serving an
open 75 percent ferrosilicon furnace is sold for manufacture of fireproof
building materials.
D. Energy Considerations
Because gas volumes from open furnaces are large, power requirements
for the air pollution control system are generally high. A typical open
furnace control system has a fan of 1,400 to 4,500 horsepower.
(24)
A venturi
scrubber on an open furnace uses approximately 10 percent of the total
power supplied to a furnace. Fabric filters or electrostatic precipitators
generally require less power since they operate with lower pressure losses.
One type of venturi scrubber (by Aeronetics)— is being used on a small,
open sil'icomanganese furnace. It utilizes heat from the furnace exhaust
gas and nevo- comparatively little external power, only about 10 percent
of that nee •'d by a conventional venturi type.
Semi-enclosed and sealed furnaces have much lower gas emission rates
than open fun.aces. Hence, the power requirements for their control
systems are usually much lower than those for open furnaces. For example,
a control system on a closed furnace would typically need a fan of 100 to
400 horsepower.
(25)
It is obvious that not only do control systems on
I/
References to commercial products are not to be considered in any
sense an endorsement of the product by the Government.
39
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closed furnaces require only about 10 percent of the power of those on
open furnaces, but the power plant emissions to provide that power are
also commensurately less.
The exhaust gases from sealed and semi-enclosed furnaces are rich in
carbon monoxide and have significant value. Twenty to 35 percent of the
power fed to the furnace can be recovered from the heat of combustion of
the gases/ ' which have been used for chemical synthesis and as fuel
for dryers, plant boilers, and other process equipment.
Collection and control of tapping fumes are the only areas in which
a standard of performance may increase power consumption over present
practice, and even this increase is slight. Efficient collection of tap
fumes will require 20,000 to 60,000 cfm. If separate collectors or fans
are used, they need operate only during tapping and can be shut off at
other times to save power. Although relatively few furnaces now have
control systems for tap fumes, in many cases these will be necessary to
meet requirements of State implementation plans.
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V. SUMMARY OF THE PROCEDURE FOR DEVELOPING STANDARDS
A. Literature Review and Industrial Contacts
Information Initially available for use in the development of standards
of performance for new stationary sources in the ferroalloy industry resulted
from a joint study by EPA and The Ferroalloys Association (TFA). The study
had been in progress for over 2 years prior to the initiation of a program
to develop standards. The joint study was primarily concerned with emissions
and control techniques of the United States ferroalloy industry. It utilized
a survey of the industry (performed with questionnaires), a literature search,
and measurements of emissions from several electric submerged-arc (ESA)
furnaces. The study provided information on the history and trends of
the ferroalloy industry, industry statistics, processes and emissions,
emission control technology and procedures, and economics.
(27)
After passage of the Clean Air Act Amendments of 1970, the program
for development of the standard was begun. Results of the joint study by
The Environmental Protection Agency and The Ferroalloys Association (EPA-
TFA study) were reviewed, additional recent literature was obtained, and
several State agencies and manufacturers of furnaces and control equipment
were consulted. Meetings were held with .the United States and Japanese
ferroalloy trade associations, and producers of ferroalloys in the United
States, Norway, Belgium, Canada, and Japan to obtain additional information
useful in the development of standards.
41
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B. Selection of Pollutants and Affected Facilities
Sulfur oxide emissions from ESA furnaces were investigated as part
of the EPA-TFA study. Emissions were very low. The concentrations were
less than 20 parts per million and the rate did not exceed 7 pounds per
hour.
(28)
There are no nitrogen oxide emissions since NOV is not produced
A
by the carbon reduction process. Emissions from semi-enclosed and sealed
furnaces may contain 60 to 90 volume percent carbon monoxide (CO)/ '' ^ '
The rate of particulate matter emissions from the United States ferroalloy
industry in 1968 is estimated to have been 160,000 tons per year of which
1,000 tons were from blast furnaces, 150,000 tons from ESA furnaces, and
(31)
9,000 tons from handling of materials. '
Analyses of particulate matter emissions revealed no significant amount of
(32)
heavy metals such as mercury, beryllium, cadmium, and arsenic/ ' As
might be suspected, significant quantities of manganese are emitted when
manganese ores are used. There is evidence that the manganese in particulate
matter emissions resulting from production of ferromanganese and silicomanganese
may be hamful to human health.'33'' <34'• <35>' <36>' (37>
Particulate control technology for electric submerged-arc furnaces
(ESA), the largest source of particulate matter in ferroalloy plants, is well
demonstrated. Other sources of air pollution in the ferroalloy industry
are minor compared to ESA furnaces. Therefore, ESA ferroalloy furnaces
were selected as the affected facility for development of the initial
standards of performance for new stationary sources in the ferroalloy
industry.
42
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Only standards for emissions of participate matter and carbon monoxide
are being proposed at this time. Equipment now being used to control
emissions from ESA furnaces is designed for particulate matter only; control of
any other pollutants is incidental. Emissions of pollutants from ESA
furnaces other than particulate matter and carbon monoxide are minor. A
limitation on particulate matter emissions will also minimize the emission of
materials such as manganese because they are emitted as particulate matter.
Large quantities of carbon monoxide generated within open furnaces are
significantly reduced by combustion with air drawn into the furnace. Carbon
monoxide from closed furnaces is usually flared at the stack outlet unless
it is used for fuel or other processes. Since there is no way to measure
the concentration of carbon monoxide downstream from the flare, a numerical
standard can neither be defined nor enforced; however, a standard can assure
that the carbon monoxide is always burned before release to the atmosphere.
Standards of performance may be developed in the future for other
pollutants and other sources of pollutants in the ferroalloy industry.
Possibilities are product crushing and sizing, raw material preparation,
open-arc ferroalloy furnaces, casting machines, and the various exothermic
reactions.
The ferroalloy industry produces a large number of products, but over
90 percent of the total United States ESA furnace ferroalloy production
consists of alloys of chromium, manganese, and silicon.(38)»(39' Although
emission rates from uncontrolled furnaces can vary greatly among products,
similar alloys often have similar levels of controlled emissions from a
-------
given type of furnace. For this reason, standards of performance for
new ESA furnaces may be categorized on the basis of product groups.
Each group consists of products having similar emissions (with air
pollution control) and control techniques. Alternative schemes for
grouping alloys and possible standards are presented and discussed
in Chapter VIII of this report.
C. Plant Inspections
EPA engineers visited eight American ferroalloy plants to become
familiar with the industry and to locate those domestic ferroalloy furnaces
which appear to achieve the best air pollution control. Emissions from
seven of these furnaces at six plants were measured as part of the EPA-
TFA study of the ferroalloy industry. In addition, measurements were
made on one uncontrolled ESA furnace producing ferrochrome silicon.
Literature reviews and discussions with both members of industry
and manufacturers of •furnaces revealed that, although there is only
one sealed ferroalloy furnace in the United States, such furnaces are
commonly used in foreign countries. Since the air volumes from a
sealed furnace average 1/50 (and may be as little as 1/200) those from
an equivalent open furnace, controlled mass emissions from closed furnaces
average only 2 percent (and may be as little as 0.5 percent) of those
from open furnaces of equivalent production rate.
Because of this obvious superiority for air pollution control inherent
in the design of sealed furnaces, several were surveyed in Japan, Norway,
-------
Belgium, and Canada. Process, operating, and emission data were obtained.
Emissions were measured from two sealed furnaces in Norway and three in
Japan. Emissions were also measured from two well-controlled open furnaces
in Japan. They were well hooded and used suction-type fabric filter collectors
which had stacks that provide good conditions for sampling. In contrast,
most open furnaces in the United States use pressure-type baghouses with
roof monitors rather than stacks. These complicate emission measurements.
D- Sampling and Analytical Techniques
EPA Method 5 was used to obtain most of the data on which the ferroalloy
standards are based. Certain modifications to Method 5 sampling apparatus
and the sampling method were necessary at some of the facilities tested.
These changes are discussed case by case in a separate document, Background
Information for Standards of Performance^: Electric Submerged-Arc Furnaces
for the Production of Ferroalloys - Volume 2, Test
Data Summary. One such modification occurred when testing sealed and semi-
enclosed furnaces. The electric heaters for the sampling probe and filter
were turned off because they could ignite the carbon monoxide-rich exhaust
gases if an air leak occurred. For this reason, probe and filter heaters
are not required by the performance test when testing gas streams which
contain over 10 volume percent carbon monoxide.
The proposed particulate matter standard of performance for new ferroalloy
furnaces limits the mass emission rate rather than the concentration. Thus,
the flow rate must also be measured in order to calculate the mass emission
-------
rate. EPA Method 2 is used to measure gas flow. It too is specific
in the procedures to be used and can be carried out simultaneously with
Method 5 with little additional effort. Included in Method 2 is a procedure
for analyzing the stack gas (EPA Method 3 - Orsat Analysis) which will
determine compliance with the provisions of the proposed standard for carbon
monoxide, since an Orsat Analysis includes measurement of carbon monoxide.
E. Emission Measurement P ro gram
EPA has performed emission measurements on a total of 14 controlled
ferroalloy furnaces. Seven were open, two semi-enclosed, and five were
sealed. Tests were usually conducted for a time approximately equal to
that of a full furnace cycle (or multiple cycles if they were required
to obtain a sample large enough to weigh accurately). One complete
tap was included (with one exception) within each sampling period so
that samples were representative of all phases of furnace operation.
During tests, the control system and furnace operation were monitored
to detect process upsets or abnormal operation which might affect the
test results. Three or more individual test runs were generally made
for each furnace. No measurements from control systems on tapping
operations were performed, because none were located which had adequate
fume capture efficiency and which had discharges which could be accurately
measured.
Particulate matter samples were obtained for all furnaces tested. In
addition, chemical, particle size, gas, x-ray diffraction, and atomic absorption
»
analyses were performed in conjunction with many of the tests, and some
of the samples were examined optically.
16
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F. Units of the Standard
Several systems of units were considered for the proposed standard
for particulate matter. The units of kilograms per megawatt-hour were
selected for the following reasons:
1. Concentration units (grams per standard cubic meter) permit
designers of new furnaces to neglect consideration of the volumes
of gases exhausted. Disparities in gas volume from existing
furnaces have resulted in variations in mass emissions by a factor
of 50 even though the two types of furnaces may have the same exhaust
particulate concentration.
2. These units of Kg/Mw-hr do not require direct measurement of the
charge to the furnace or production rates during the test period. In the
ferroalloy industry, these quantities can rarely be accurately determined.
3. The average power consumed (Mw-hr) by the furnace is readily
obtained from instruments already installed on furnaces.
4. The power consumption of a furnace is a function of its production
and is related to emission rate. Consequently, these units are similar
to those for standards based on production or raw material feed rates.
5. An open furnace with fabric filter collection may achieve lower
exhaust particulate concentration than a sealed furnace which uses
a scrubber, even though the total weight of emissions from the
47
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sealed furnace 1s only 2 percent of those from the open furnace.
Under these circumstances, a concentration standard would be more
easily met by the open furnace and use of the open furnace would
be encouraged even though Its mass emissions are higher.
G. Development of Proposed Standards
On February 20, 1973, the Agency presented a draft technical report
and standard for the ferroalloy industry to the National Air Pollution
Control Techniques Advisory Committee (NAPCTAC). In summary the report
concluded that best demonstrated technology for control of fumes from
electric submerged arc furnaces producing ferromanganese,
silicomanganese, and calcium carbide is the sealed furnace in conjunction
with appropriate control equipment. The draft standard did not cover any
other ferroalloy products. The particulate matter limitation in the draft
standard was 0.15 Ib/MW-hr and 10 percent opacity; the carbon monoxide
limitation was 20 volume percent on a dry basis. The ferroalloy industry
was represented at the meeting and the representatives expressed their
comments to the committee members and suggested that the standard be 1.0
Ib/MW-hr and 20 percent opacity. The industry representatives stated
that a standard of 0.15 Ib/MW-hr would preclude the use of furnaces other
than sealed and not allow the use of open furnace configurations. They
felt the Agency's cost estimates for controlling sealed furnaces were low
and sealed furnaces presented safety hazards.
-------
The draft technical report and standard for the ferroalloy industry
were presented again to NAPCTAC on May 30., 1973. At this meeting the
Agency presented additional cost information on open and sealed
furnace configurations and the safety hazards of sealed furnaces.
Ferroalloy industry representatives again expressed their objections
to the draft standard because sealed furnaces in their opinion create
safety hazards and limit the flexibility of industry to produce a broad
range of ferroalloy products. They stated that the domestic industry
must use open furnaces to maintain competitiveness and flexibility of
furnace products.
The ferroalloy industry was again discussed at the NAPCTAC meeting
on January 10, 1974. The Agency representatives emphasized the advantages
(from an air pollution and energy standpoint) of sealed furnaces over open
furnaces. No standard was recommended or discussed and the Committee was
informed that if time permitted the standards to be proposed for the ferro-
alloy industry would cover the entire industry and Agency representatives
had met with the industry representatives several times since the May 30th
meeting to discuss the industry's position with respect to open versus
sealed furnaces. The industry representatives again reaffirmed their
concern to the Committee for any standard that would force the use of
sealed furnaces and not allow open furnaces.
During October 1973., Agency personnel conducted an extensive testing
program on several ferroalloy furnaces in Japan. During the latter part
of 1973 and the early part of 1974, Agency personnel visited additional
domestic furnaces and consulted with industry representatives to
49
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resolve the issue of product flexibility .and the need for a standard
which would allow open furnaces. The information obtained by the Agency
during this period of time allowed the proposed standard to cover the
entire product line of the ferroalloy industry and indicated that there
is a need to allow the use of open furnaces. The rationale for the
Agency's conclusion that the proposed standard should allow open furnaces
is discussed in Chapter II.
50
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VI. DATA TO SUBSTANTIATE A STANDARD
A- Concentration and Mass Data
Results of emission measurements conducted by EPA and other data
on emissions from controlled ferroalloy furnaces are shown in Figures
VI-1 through VI-6. Brief descriptions of each facility for which emission
data were obtained and tables summarizing the data are in a separate
document, Background Information for Standards of Performance: Electric
Submerged-Arc Furnaces for the Production of Ferroalloys
Volume 2, Test Data Summary.
Figures VI-1 and VI-2 show results of measurements of particulate matter
emissions from sealed ferroalloy furnaces. Data for Furnaces Al, A2,
B, S, R, and K were obtained by EPA on tests conducted in Norway and
Japan. Furnaces Al and A2 are the same. During runs designated Al,
only one venturi scrubber was operated, whereas during runs designated
A2, a second one was put in service, providing two separate but identical
venturi scrubbers operated in parallel. Data for Furnaces D, E, F, I,
J, and H are results of tests conducted by Japanese companies using the
Japan Industrial Standard test method.^41^ This method specifies use
of a filter with at least 99 percent collection efficiency. The test
method used to obtain emission data on Furnace 6, a Russian facility,
is unknown.^ '
Average particulate matter emissions from sealed furnaces ranged from
0.002 gr/dscf to 0.032 gr/dscf and from 0.002 Ib/Mw-hr to 0.036 Ib/Mw-hr,
not including tapping fume. Fugitive emissions escaped at the electrode
51
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seats of Furnace K during the tests. These emissions could not be measured
quantitatively; however, other sealed furnaces were observed to operate
with no fugitive fumes at the electrode seals.
Two semi-enclosed furnaces (C and P) were tested by EPA. Data from
these tests are shown in Figures VI-3 and VI-4. Outlet loadings from the
control devices of Furnaces C and P averaged 0.030 gr/dscf and 0.058 gr/dscf
(0.017 Ib/Mw-hr and 0.078 Ib/Mw-hr) respectively, not including tapping
emissions or those which emanate from the annular openings around the
electrodes. Particulate matter emissions from around the electrodes were measured
as 48 Ib/hr (2.0 Ib/Mw-hr) for Furnace C and 390 Ib/hr (8.3 Ib/Mw-hr) for
Furnace P.
Emissions from the spaces around the electrodes of semi-enclosed furnaces
are much greater than controlled emissions from the control device. Hoods
and ducts could conceivably be installed to capture fumes from the spaces
around the electrodes and send them to a control device. If a control device
with 99 percent overall efficiency had been used on these emissions for the
furnaces tested, total emissions (excluding those from tapping) would have
been 0.037 Ib/Mw-hr and 0.16 Ib/Mw-hr for Furnaces C and P respectively.
These values are well below typical emissions from controlled open furnaces.
Emission data obtained by EPA on open ferroalloy furnaces are shown in
Figures VI-5 and VI-6. Furnaces U and 0 are in Japan. LI, L2, and L3 are
-------
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(1) DOES NOT INCLUDE 48.2 Ib/hr UNCONTROLLED FUGITIVE FUMES FROM AROUND THE ELECTRODES.
(2) DOES NOT INCLUDE 388 Ib/hr UNCONTROLLED FUGITIVE FUMES FROM AROUND THE ELECTRODES.
Figure VI-4. Particulate emissions (excluding tapping fumes and fugitive fumes) from semi-enclosed
electric submerged-arc furnaces producing ferroalloys.
56
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FURNACE SIZE. Mw 27 27 27 7 40 18 20 27 17 D n«^nir
PRODUCT
SiMn
I H.C. I FeCrSi I 75% I Si
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57
Figure VI-5. Particulate concentrations in control system exhaust from open electric submerged-arc
furnaces producing ferroalloys.
-------
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FURNACE SIZE, Mw 27 27 27 7 40 18 20 27 PRECIPITATOR
PRODUCT SiMn 1 H.C. 1 FeCrSi 75% 1 Si B- BAGHOUSE
FeCr FeSi
58
Figure VI-6. Particulate emissions from open electric submerged-arc furnaces producing ferroalloys.
-------
the same furnace for which the energy loss across the venturl scrubber
was 57, 47, and 37 Inches water gauge, respectively. Average emissions
ranged from 0.0010 gr/dscf to 0.079 gr/dscf, or from 0.035 Ib/Mw-hr to
1.5 Ib/Mw-hr. Where noted, the data in Figures VI-5 and VI-6 include fume
captured in a tapping hood and ducted to the furnace control device.
Capture efficiency for these tapping hoods was estimated as 20 percent
for Furnace N and 80 percent for Furnaces T and U. Estimated capture
efficiencies of the furnace hoods ranged from 95 to 100 percent.
The data presented in Figures VI-19 3 and 5 present a wide variation
in particulate matter concentrations, but no correlation with furnace
configuration can be drawn because data for all three types of furnaces
have similar variations and span roughly the same range of values. From
this, one can conclude that a standard restricting the concentration of
particulate matter is not a good choice since it cannot mandate the sealed
furnace, which obviously provides better overall emission control. The
data show that mass emissions in terms of Ib/Mw-hr do vary significantly
with the type of furnace. Mass emissions from semi-enclosed furnaces
with uncontrolled emissions from the annular spaces around the electrodes
are highest. Open furnaces with efficient control have the next highest
emissions. Sealed furnaces have the lowest mass emissions and emissions
from semi-enclosed furnaces which capture and efficiently control electrode
emissions appear to be intermediate between open and sealed furnaces.
59
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No measurement was made of emissions from a tapping operation with
an independent control system because none was found from which they could
be measured with reasonable accuracy. They were measured at three furnaces
where the tapping hoods exhausted directly into the atmosphere without
control. Average uncontrolled tapping emission rates were 48 Ib/hr for
Furnace C, 53 Ib/hr for Furnace L, and 82 Ib/hr for Furnace P for the
duration of tapping. Furnace C is continuously tapped. If tapping emission
rates for Furnaces L and P were averaged over the entire furnace cycle
instead of only the tapping period, tapping emission rates would be reduced
to about 18 Ib/hr and 16 Ib/hr respectively. Capture efficiency of the
tapping hood was very good on Furnace C and was estimated as 75 percent on
Furnace P. Hood capture efficiency was not estimated for Furnace L. At
other plants, tapping hoods with apparent 100 percent capture efficiency
have been observed.
Based on measurements of emissions from furnaces where tapping emissions
are not controlled and observation of furnaces which very effectively
capture tapping emissions, calculation methods have been used to determine
the equivalent emissions from a furnace at which tapping emissions are
captured and ducted to an efficient control device. To determine the
effect of including tapping fumes, a conservatively high value of 150
Ib/hr of uncontrolled tapping emissions was assumed. If these are
completely captured and enter a control device with 99 percent efficiency,
emissions from tapping a 30-MW, continuously tapped furnace would be 0.05
Ib/Mw-hr. Continuously tapped furnaces are not common except for calcium
60
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carbide production. Tapping emissions averaged over the entire furnace
cycle for a 30-MW furnace tapped for 15 minutes during a furnace cycle
of 75 minutes (start of one tap to the start of the next tap) would
be 0.01 Ib/Mw-hr. Comparison of these calculated values for controlled
tapping emissions shows they about equal emissions from well-controlled
sealed ferroalloy furnaces, and are about 10 percent or less of typical
emissions from well-controlled open ferroalloy furnaces.
B. Visible Emission Data
Visible emission data were obtained at several facilities. No sealed
furnace had a residual visible emission after the flare. Visible emissions
from the scrubber serving semi-enclosed Furnace P also were zero percent
opacity. Visible emissions from control devices serving open furnaces
varied. They were consistently zero percent opacity for Furnaces U, M
and N during periods when samples were obtained for quantitative emission
measurements. Maximum visible emissions from other open furnace control
systems ranged from 5 to 15 percent opacity. In some cases, visible
emissions were traced to leaking bags in baghouses. Visible emission
data are summarized in a separate document, Background Informatjgn for
Standards of Performance: Electric Submerged-Arc Furnaces for the Production
of Ferroalloys - Volume 2, Test Data Summary.
Visible emissions from buildings which house electric submerged-arc
ferroalloy furnaces were observed at 100 percent opacity for brief periods.
These emissions may vary from 0 to 100 percent opacity depending on what
production operation is occurring and the capture efficiency of the hoods.
Possible sources of participate matter which may cause visible emissions from
61
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buildings are fumes which escape from the furnace, tapping operations,
oxygen lancing of tap holes, and reladling and pouring of the ferroalloy.
Visible emissions were observed at one tapping hood through two tapping
periods, the first of 19 minutes duration, and the second of 30 minutes
duration, and opacities of fume which escaped the hood were recorded.
During the first tapping period observed, the hood was moved out of
place twice for unknown reasons for a total of 1.5 minutes of the 19.
Excluding the observations made during the 1.5 minutes when the hood was
out of place, the opacities were observed to be zero percent for 12.5
minutes (or 71.4 percent of the time) and were observed to be less than
20 percent for 15.75 minutes (or 90 percent of the time). Opacities were
greater than or equal to 20 percent for 1.75 minutes of the 17.5 minutes
during which the hood was in place. The maximum opacity observed was 60
percent. During the second tap, the tapping hood was left in place
throughout the tapping period. Opacities were observed to be zero percent
for 22 minutes of the 30 minute tapping period (73.3 percent of the time),
and the maximum opacity observed was 15 percent.
Visible emission readings of fume escaping furnace hoods were obtained,
and furnace hood capture efficiencies were estimated at 3 open ferroalloy
furnaces. In each of these cases, no visible emissions were observed
escaping the hood, and capture efficiencies were estimated as 100 percent.
One other open furnace was observed and judged to achieve equivalent
collection, but formal opacity readings were not made. Visible emissions
62
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did not escape the covers of the sealed furnaces observed unless the seals
around the electrodes or charging chutes were leaking. This condition can
be corrected to prevent visible emissions.
63
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VI I. SUMMARY OF ECONOMIC INFORMATION
A. Introduction
This section will examine the cost of the alternative control systems,
evaluate the economic impact of the control costs on the industry, and
compare the cost of the proposed standard of performance to the cost
of achieving State standards.
The type of furnace and the method of hooding used to capture the
furnace gases have a great effect on the cost of the emission control
system. The main factor influencing the cost of the control system
is the gas volume that must be treated. The carbon monoxide and other
gases evolved from the furnace reaction zone can be withdrawn by an
exhaust system without combustion of the carbon monoxide provided the
furnace has a closed water-cooled cover and mechanical seals around the
electrodes. Although sealed ferroalloy furnaces cannot be used to
produce all products, they offer the advantage of smaller gas volumes
to clean than an open furnace. The small volume of undiluted dirty gases
from a sealed furnace is typically cleaned by venturi scrubbers. Foreign
installations also use electrostatic precipitators and one uses a sealed
baghouse.
In the open furnace system, induced air is mixed with the carbon mon-
oxide which burns above the charge. Depending on the design of the particu-
lar furnace, the evolution of gases may result in flows 50 to 200 times
those generated in a sealed furnace system. The gas flow rate depends on
65
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the hood design, the vertical opening between hood and furnace required
for stoking the charge, and the diameter of the furnace. Fabric filters
(baghouses) or wet scrubbers are typically used to control open furnaces.
B. Model Plants
The control costs were developed for model ferroalloy furnaces
(examples of ferroalloy furnaces typical of furnaces which may be built
in the future). The values of the parameters of each model were chosen
to represent the expected values for new ferroalloy furnaces. Because
the trend in the industry is toward larger furnaces than in the past,
the size chosen for the models is large - 30 megawatts (except for the
silicon metal furnace which is 25 megawatts). Table VII-1 shows the pertinent
design parameters associated with the model furnaces. Since silicomanganese
(SiMn) can be made in the same furnace interchangeably with high-carbon
ferromanganese (HC FeMn), we have assumed that the control equipment for
the SiMn furnace will be the same as that for the HC FeMn furnace.
Another emission source that must be controlled in addition to the
furnace is the tapping operation. The method of control assumed for this
cost analysis depends on the furnace type. For open furnaces the tapping
fumes can be collected with a separate hood and vented into the main
control device. For sealed furnaces a separate fabric filter control
system was assumed as the most probable method of control.
66
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Table VII-1. Model Furnace Parameters
Parameter
Power rating, Mw
Product rate,9 tons/yr
Gas volume from
sealed furnace.
scfm
Gas volume from open
furnace, b acfm @ 400° F
Tapping fume gas
volume for all furnace
types, acfm @ 150°Fd
Product
HC FeMn
30
99,000
5,000
350,000
60,000
SiMn
30
44,000
50% FeSi
30
47,500
5,000 6,000
|
350,000C
60,000
>
450,000
60,000
HC FeCr
30
51,000
5,000
250,000 ,
1
60,000 \
<
CaCg
30
91 ,000
4,000
200,000
60,000
Si Metal
25
14,100
6,000
750,000
60,000
"
At 90 percent of full capacity.
The gas volumes represent typical values obtained from the industry survey
questionnaires.
"Assumed to be the same for the HC FeMn since the furnace may be designed to produce
either product.
The figures shown for the tap fume collection are additive to the open furnace
volume, based on an open furnace configuration with the collection hood 5 to 7 feet
above the furnace deck.
67
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C. Control Costs
1. Open Furnace Control Costs
Control costs for the model open furnaces shown in Table VII-1
were developed for two types of control devices - fabric filters and
wet scrubbers. All costs are in 1972 dollars.
a. Fabric Filter Control Costs
Estimates of investment and operating costs required to control
open furnaces using fabric filter systems are shown in Table VII-2.
These costs were derived from information developed for EPA by
the Industrial Gas Cleaning Institute (IGCI).(43) The tapping fume
control system is vented into the fabric filter, and the costs for
that system are included. The assumptions that form the basis for
these cost estimates will be discussed below. The industry's cost
estimates for fabric filter systems are higher than the figures
in Table VII-2 because additional equipment and installation factors
are considered. The industry's cost estimates are shown in
Table VII-3 and will be discussed in the second part of this section.
The capital costs for fabric filter installations as received
from the IGCI were plotted against the associated collector inlet
volumes, and the graph is shown in Figure VH-1. The capital cost
for each model furnace may be determined from Figure Vtl-1 by
finding the capital cost that corresponds to the gas volume flow
rate for that model. The capital costs from the IGCI study are
based on a new plant situation (i.e., a simple duct run, no space
68
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Table VI1-2. Control Costs for Fabric Filters on Open Furnaces
Cost Item
Capital cost
(Thousands of $)
Fab'ric Filter
Auxiliary Equipment
Installation
Total Capital Cost
Annual Cost
(thousands of $
per year)
Operating Labor
Maintenance (6%)
Product
HC FeMn
and SiMn
$ &30
210
1,060
$1 ,900
$ 53
| 114
Electricity 1 87
1
Capital Recovery ! 222
(15 yr. life, 8%
interest) f
s
Administration (2%) I 38
<
Taxes and Insurance
(2%)
Total Annual Cost
Annual Cost Per Ton
50% FeSi
$ 770
250
1,280
$2,300
$ 53
HC FeCr
$ 500
160
840
$1 ,500 •
$ 53
138 | 90
1
106 1 68
a
269 I 175
K
46 | 30
! 1
! 38 \ 46 | 30
1 ' I 1
f $ 552
HC FeMn SiMn
$5.58 $12.55
|
\ $ 658
$13.85
!
$ 446
I $8.75
CaC2
$ 430
140
730
$1 ,300
| $ 53
78
Si
Metal
$1 ,260
520
1,420
$3,200
$ 53
192
57 j 194
1 152 374
26 64
26 I 64
$ 392 j $ 941
I
ft
4
$4.31 j $66.74
69
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Table VI1-3. Control Costs for Fabric Filters on Open Furnaces
(Estimated by Industry)
Cost Item
Capital Cost ( housands
of $)
Fabric Filter
Auxiliary Equipment
Installation
Total Capital Cost
Annual Cost (Thousands
of $ per year)
Operating Labor
Maintenance (61)
El ectri ci ty
Capital Recovery,
(15 yr. life, 8% interest)
Administration (2%)
Taxes and Insurance (2%)
Total Annual Cost
Product
HC FeMn
and SiMn
$1 ,000
360
1,640
50% FeSi
$1 ,265
455
j
I 2,080
$3,000 j $3,800
|
HC FeCr
$ 700
255
1,145 !
$2,100 !
1
$ 53 t $ 53 1 $ 53 1
i
180 \ 228 126
1 I 1
87 j 106
350 | 444
60 76 j
60
$ 790
76 i
$ 983 ;
68 I
245
?
42 i
5
42 |
$ 576 j
i
HC FeMn SiMnl j j
Annual Cost Per Ton j$7«9S $17.95| $20.69 ! $11.29 1
o » *
CaC£
$ 630
220
1,050
$1 ,900
$ 53
114
57
222
38
38
$ 522
$5.74
Si-
Metal
$1 ,890
780
2,130
$4,800
$ 53
288
194
561
96
96
$1 ,288
$91.35
70
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4.0
2.0
1.5
1.0
0.8
0.6
fe
LU
0.4
0.2
20 30 40 50 7u 100 200 400
INLET GAS VOLUME TO COLLECTOR, acfm x 103
Figure VI1-1 . Capital costs of open furnace control with fabric filters.43
800
71
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limitations, etc.)- The costs for the furnace hood and the incremen-
tal costs for increases in electrical substation capacity are not
included. The capital costs for the fabric filter installations
include the baghouse, fans, upstream mechanical collector, dust
storage bins with 24-hour capacity, dust hoppers and conveyors,
foundation support, ductwork connections, and stack. The costs
for engineering design, electrical and piping tie-ins, insulation,
erection, and performance testing are all included. Fiber glass
bags with a temperature resistance of 500° F are assumed to be
used. The baghouse is also assumed to contain one extra compart-
ment which permits maintenance on one section without shutting
down the entire baghouse.
The following assumptions concerning annual costs of operation
apply to operation of the control facility for open furnaces.
(1) Replacement parts and maintenance were estimated at
6 percent of the original plant investment for the purpose of
replacing 50 percent of the bags and 10 percent of the air
valves per year, and for contingencies.
(2) Manpower requirements were estimated to be 1/2 man
per shift.
(3) The main component of the electrical costs is the
power required by the fans to overcome the baghouse pressure
drop. The pressure drop ranges from 10-12 inches of water for
HC FeCr to 15-20 inches of water for 50 percent FeSi.
72
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(4) Depreciation and Interest charges are accounted for
by the use of a capital recovery factor based on 15 year life
and on 8 percent interest rate.
(5) Administrative costs of 2 percent of original
investment, and another 2 percent for property tax and
insurance were assumed.
The ferroalloy industry has estimated higher costs for fabric
filter installations for the following reasons:
(1) The industry's cost figures are based mainly on
installations at existing plant sites. Since these instal-
lations must be fitted into the available space, certain cost
items such as ducting will be more expensive.
(2) The industry's figures also include items that were
not included in the IGCI cost estimates. These items are the
furnace hood cost, electrical substation expansion costs,
equipment startup costs, and company engineering and con-
tingency costs.
If these items are included and installation in an existing
building is assumed, the capital costs can be as much as 50 percent
higher than the IGCI costs. Table VII-3 shows the industry's cost
estimates for the model furnaces.
If the average of the IGCI costs and the industry's costs are
used, the annual cost per ton ranges from a low of $5.03 per ton
for calcium carbide to $79.05 per ton for silicon metal.
73
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b. Wet Scrubber Control Co.sts
Estimates of the investment and operating costs required to
control open furnaces using wet scrubbers are shown in Table VII-4.
These estimates are derived from information from the Industrial
Gas Cleaning institute (IGCI)^43) and are based on equipment and
operating requirements to meet the process weight standard
published in the Federal Register of August 14, 1971 (36 FR 15486),
The costs have been adjusted from IGCI data to reflect the gas
flows of the model plants presented in Table VIM. The costs in
Table VII-4are based on a new plant installation and do not
include the furnace hood or additional electrical substation
costs. The industry's experience confirms the costs as presented
in Table VII-4.
Plots of investment cost for scrubbers to control furnaces
making 50 percent ferrosilicon that were developed by the IGCI
are shown in Figure '.VI1-2. The cost curve for ferrochrome was
used to develop the costs for all the other alloys except 50
percent ferrosilicon. The investment costs include a venturi
scrubber, a fan with at least 20 percent excess capacity, an
entrainment separator, aftercoolers, a slurry settler, two
filters to dewater the slurry product, and tapping emissions con-
trol. The charges for engineering design, electrical wiring.,
piping, insulation, erection, performance testing, and startup
are all included.
-------
Table VI1-4. Control Costs for Wet Scrubbers on Open Furnaces
Product
HC FeMn
Cost Item 1 and SiMn 50% FeSi
Capital Cost (thousands of $) 1
Scrubber jj $ 110 I $ 190
Auxiliary equipment I 290 I 510
Installation I 1,400 f 2,450
Total Capital Cost I $1,800 I $3,150
Annual Cost (thousands of $ per year)l I
Operating Labor 1 $ 26 I $ 26
Maintenance (1%) \ 126 I 220 i
Electricity 1 290 J 595 :
Water j 155 ! 298
Capital recovery f 210 | 368
(15 yr. life, 8% interest) I \ \
Taxes and Insurance (2%) 1 35 ' 63 1
Administration (2%) 1 36 63 i
Total Annual Cost ? $ 879 $1 ,633
:HC FeMn SiMn ,
Annual Cost Per Ton • $8.88 $19.97 $34.38 !
HC FeCr
$ 96
254
1,250
$1 ,600
$ 26
112 ;
225 j
118 i
187 j
32 !
32
$ 732 1
1
$14.35 |
CaC2
1
$ 87
233
1,130
$1 ,450
$ 26
102
190
99
169
29
29
$ 644
$7.08
75
-------
20
30
40 50 80 100 200
INLET GAS VOLUME, acfm x Ifl3
600
Figure Vll-2. Capital costs of open furnace control with wet scrubbers.
43
76
-------
The annual cost per ton of product ranges from a low of
$7.08 per ton for calctuin carbide to a high of $34.38 per ton
for 50 percent ferrosilicon. Wet scrubber control was not included
for silicon metal because of the difficulty of achieving good
control with wet scrubbers.
c. Actual Industry Costs
The Ferroalloy Association submitted to EPA the actual furnace
and air pollution control equipment cost data for several recent
installations.(44) The specific details of each installation are
somewhat different since each installation was an addition at an existing
plant, and to varying degrees existing equipment was used for the new
furnace. The costs reported for the control equipment when
adjusted for the year of installation range from -16 percent to
+40 percent of the costs in Figures VII-1 and VHh2. Considering the
differences in the bases,, the actual costs compare favorably with the
costs in Figure VII-1 and VII-2,, Since the EPA estima,te&.,ace
designed to represent typical installations, some differences
for specific installations are expected.
2. Sealed Furnace Control Costs
a. Furnace Fume Control Cost - Wet Scrubber
Capital and annual costs are presented in this section for
control devices on sealed furnaces. Since the furnace has a
tight cover with seals around the electrodes, the gas volume
going to the control device is much smaller than for an open
77
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furnace. Thus, the cost of the control device is much smaller
than the control device cost for an open furnace. However, the
pollution control equipment is not the only consideration in a com-
parison of open and sealed furnaces. Actually, the open and sealed
furnaces require two different sets of process equipment of which
the pollution control system is one part.
In order to make a complete comparision of the two furnace
types, the total system should be considered from both the process
side and the air pollution control side. In this section the costs
for a sealed furnace are compared to the costs for an open furnace
to illustrate this point.
The costs presented here are for a large sealed furnace
recently constructed in Canada. These costs should be represen-
tative of the costs that would be experienced at a U.S. location.
The maximum power rating for this furnace is 33 Mw for HC FeMn
and 38 Mw for SiMn.
The primary control system for the sealed furnace consists
of the sealed furnace cover, a water spray cooler, a mechanical
dust separator, and a variable-throat venturi scrubber followed
by a mist eliminator. The pressure drop across the scrubber is
in the range of 75 to 80 inches of water. The gas flow from the
furnace is about 6,600 scfm, and the gas flow at the scrubber
is about 9,700 scfm. The cleaned gas stream, which is rich in
78
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CO, can be used as a fuel source in the feed pretreatment plant
or diverted to a flare stack. A complete water treatment system
is included; the treated water is recycled to the scrubber and
the filter cake of solids is recycled to the sintering plant.
The furnace tapping system is designed with a hood over each
of four tapholes. A total flow rate of 30,000 acfm is combined
with another 20,000 acfm vent stream and sent to a fabric filter
collector.
Table VII-5 shows the costs for the sealed furnace and its
control equipment compared to the company's estimated costs for
an open furnace with a fabric filter collection system. The
prorated share of the project's utilities, electrical, and
engineering expense for the control system is included in the
control system cost. In addition to the furnace collection
system and the tapping emission collection system, the company
reported two other cost factors for the totally enclosed furnace
that are different from those of the open furnace. The first is the
incremental furnace cost which includes such items as more
complex electrode columns and electrical equipment. The
second item is an incremental feed pretreatment cost which
includes ore and coke dryers and a sinter plant.
The decision to use the incremental feed pretreatment
must be made after evaluation of the overall process. Drying and
sintering allow the use of coke and ore fines and the recovered
particulate matter from the air pollution control systems. Some foreign
79
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Table VU-5. Comparison of Capital and Annual Costs for an
upen and a Sealed HC FeMn and SiMn
Furnace Producing HC FeMn or SiMn
Cost Item
(45)
Comparison of total capital costs v '
(thousands of ?)
Basic furnace and associated process equipment
Incremental furnace cost
Incremental feed pretreatment
Air pollution control systems
Comparison of control equipment costs
Capital costs'45' (thousands of $)
Primary system
Taphole system (see Table VI-7)
Incremental furnace cost
Annual costs (thousands of $ per year)
Operating cost
Maintenance (6%)
Capital recovery (@ 8% interest)
Administration (2%)
Taxes and insurance (2%)
Open Furnace
$ 8,500
—
—
3,500
$12,000
$ 3,500
(inc. in above)
— ~
$ 3,500
$ 143
210r
409
70
70
Totally Enclosed
Furnace
$ 8,500
1 ,400
3,000
2,100
$15,000
$1 ,700b
400
1 ,400
$3,500
$ 135
210d
! 390
» 70
! 70
Annual cost per, ton
HC FeMn
SiMn
a ($/ton)
$ 902
$9.11
$20.50
$8.84e
$19.89
Based on 30 Mw for HC FeMn and 34 Mw for SiMn, both at 90% operating rate.
blncluues $900,000 fur the cooler, mechanical separator, scrubber, mist elimina-
tor, and water treatment equipment; $420,000 for the furnace cover and
mechanical seals; and $380,000 for the prorated share of electrical utility
and engineering costs.
Depreciation life: 15 years.
Depreciation lives: 10 years - furnace cover, 15 years - pollution control sys-
tem, 20 years - incremental furnace costs.
eThis does not include the annualized investment cost or operating cost of the
incremental feed pretreatment equipment. The ferroalloy industry has indicated
that the total manufacturing cost per ton of product is about equal for both
the open furnace with control and the sealed furnace with control arid feed
preparation.
80
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plants with sealed furnaces have these additional feed pretreatment
steps and some do not. It is even hard to define exactly what
should be included as incremental feed pretreatment equipment.
For example, some open furnaces have dryers and some do not
(depending on the availability of dry materials). Thus, dryers
may or may not be considered as incremental equipment for totally
enclosed furnaces. The incremental feed pretreatment cost could
be considered as part of the air pollution control cost, or could
be considered a process addition for which the economics must be
justified in each individual case.
In Table V-I.I-5 the capital cost for the incremental feed pre-
treatment is shown, but these costs are not included in the presen-
tation of the annual cost of the air pollution control equipment.
After an overall evaluation was made, this particular plant decided
that the sealed furnace with the additional feed pretreatment
was the best choice in this case. Japan Metals and Chemicals,
the largest producer of ferroalloys in Japan and a ferroalloy
furnace manufacturer, states that the final cost of product is
the same from either an open or totally enclosed furnace.'46'
The particular method of processing must be considered separately
for each individual installation.
It is not possible to generalize from this case to say that
in all cases the totally enclosed furnace with feed pretreatment
would be the most economical. For example, in the case where
a furnace is to be added at an.existing plant, an open furnace
81
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could possibly use the existing feed preparation and delivery
system whereas a sealed furnace might require a new, separate
feed preparation and delivery system. Also, the open furnace
could possibly be installed in an existing building while the
taller, totally enclosed furnace would probably require a new
or expanded building. These or other differences at any specific
site could affect the costs enough to change the choice of the most
economical type of furnace to an open furnace.
The cost data in Table V.1I-5 are for sealed furnaces producing
HC FeMn and SiMn. Table VII-6 shows the emission control device
cost for a sealed 30 megawatt CaC2 furnace. The costs are
based on extrapolation from the HC FeMn costs for the same type
of system using the following relationship:
CaC? gas volume
Cost of CaC2 System = Cost of HC FeMn System X HC FeMn gas volume
Only the emission control system is shown in Table VII-6.
b. Furnace Fume Control Cost - Fabric Filter
One known company uses a fabric filter as the control device
on a sealed furnace. This method of control has not been used
in the U.S., and the domestic industry does not expect to use
this method of control for sealed furnaces. The estimated
capital cost for a conventional fabric filter control system*con-
sisting of a radiant cooler, cyclone, fan, fabric filter, dust
removal and storage equipment, water seal tanks, and flare stack,
82
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Table VI1-6. Control Costs for a Sealed CaC2 Furnace
Cost Item
Cost
Capital Costs (Thousands of $)
Primary Control System
Taphole System (See Table VI-7)
Total Capital Cost
$1,280
400
$1,680
Annual Costs (Thousands of $ per year)
Operating Cost
Maintenance (6%)
Capital Recovery (15 year life, 8% interest)
Administration (2%)
Taxes and Insurance (2%)
Total Annual Cost
Annual Cost per ton of Product ($/ton)
$ 119
101
196
34
34
$ 484
$5.32
83
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is about $250,000. However, this system would have to be
specially designed because of the high concentration of CO gas.
These added design considerations could substantially increase
the cost.
c. Tapping Fume Control Cost
The estimated capital and annual costs presented in Table VU-7
are based on a separate fabric filter control system for emissions
generated during the furnace tapping operation. The assumed flow
rate was 60,000 acfm at 150° F. The system includes a hood, fan,
fabric filter, and dust removal and storage equipment.
Because the tapping operation can be scheduled with some
flexibility, this control system could serve more than one
furnace. Possibly tapping fume hoods from two furnaces could be
vented to the same fabric filter,which would reduce the control
cost per furnace. However, for this analysis a separate tapping
fume control system for each furnace has been assumed.
D. Discussion of the Control Costs
1. Cost Effectiveness Comparisons
In general, varying the level of control efficiency required will
result in a change of the control system cost. In the case of the
ferroalloy furnace controls, the costs do not follow the usual
pattern. This can be seen in two comparisons. Consider first the
open furnace control systems—fabric filters and wet scrubbers.
-------
Table VII-7. Control Costs for a Separate Tapping Fume Collection System
Cost Item
Cost
Capital Cost
Fabric Filter
Auxiliary Equipment
Installation
Total Capital Cost
$ 85,000
55,000
260,000
$400,000
Annual Cost
Operating Labor
Maintenance (10%)
Electricity
Capital Recovery (15 yr. life at
Administration (2%)
Taxes and Insurance (2%)
Total Annual Cost
Interest)
$ 10,000
40,000
23,000
47,000
8,000
8,000
$136,000
85
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The fabric filter systems can achieve the best control. If the
required control efficiency js lowered, wet scrubbers could be used.
But, as Tables V'IJ-2,3, and 4 indicate, the annual costs for wet
scrubbers are higher than those for fabric filters. Therefore,
there is no cost advantage to setting an emisssion standard which
requires a lower efficiency than what can be achieved using a fabric
filter system.
A second comparison can be made looking at sealed furnaces and
open furnaces for production of HC FeMn, SiMn, and CaC2- For
these products the cost of the control device for the sealed furnace
(Tables Vir-^,6) is lower than that for a fabric filter on an open furnace
As discussed in section C.2.a., when all costs are considered there
is no significant cost difference between an open furnace with
fabric filter and a sealed furnace with a wet scrubber. Therefore,
the choice of system will be influenced'by factors other than
cost.
2. Control Costs - New Source Performance Standards vs. State Standards
In order to meet typical State process weight standards, the
ferroalloy furnaces must install fabric filter control systems (or
equivalent) on open furnaces and provide control of tapping fumes.
This is, of course, equivalent to the requirements of the proposed
standard of performance. Therefore, the cost of control to meet
the proposed standard of performance is no qreater
than what the industry must spend to meet typical state standards.
86
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E. Economic Impact
It is estimated that five to eight new furnaces will be needed in the
next 5 years to provide the required new capacity and replacements
for existing units. However, only one unit is currently under construction
and that is due for completion in 1975. In 1972 four producers closed
their plants. Thus, there has been a net attrition rather than a slow
growth in the industry. As is true with many products, ferroalloy
prices were frozen at low levels which severely limited profits and
consequently limited funds available for expansion. With the exception of
the new unit mentioned above, the industry is investing a large proportion
of available capital in pollution control equipment to meet the 1975
emission control guidelines.
The combination of price controls and the upsurge in the steel
industry have caused a severe shortage of ferroalloys. Imported alloys
are selling at two and three times the controlled domestic prices. With
price control regulations relaxed, it is apparent the air pollution
control costs ranging from 5 percent of the selling price for ferromanganese
to 20 percent for silicon metal, can be passed on to the consumers.
87
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VIII. ALTERNATIVE STANDARDS
Listed below for each pollutant are alternatives which were considered
in developing the proposed standards of performance.
A. Alternative Standards for Participate Matter
1. Alternative No. 1.-!/
No owner or operator shall cause to be discharged into the
atmosphere from any affected facility any gases which:
a.
b.
Contain particulate matter in excess of 0.45 kg/Mw-hr
(0.99 Ib/Mw-hr) while that facility produces silicon metal,
ferrosilicori (60 percent and above), calcium silicon, or
silicomanganese zirconium.
Contain particulate matter in excess of 0.23 kg/Mw-hr
(0.51 Ib/Mw-hr) while that facility produces charge chrome,
ferromanganese silicon, or silvery iron (5 to 24 percent
silicon).
c. Contain particulate matter in excess of 0.07 kg/Mw-hr
(0.15 Ib/Mw-hr) while that facility produces silicomanganese,
]_/ The limitations of parts (a) and (b) of Alternatives 1 and 2
can be achieved by an open furnace with good control equipment such as
a fabric filter. Part (c) will probably require a well-controlled sealed
furnace although a tightly hooded open furnace with very good control may
suffice (see data for Plant U in Chapter VI).
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ferromanganese, calcium carbide, high-carbon ferrochrome,
nominal 50 percent ferrosilicon, or ferrochrome silicon.
Advantages
1) This option mandates "best technology."
2) It strongly encourages use of sealed furnaces for those product
lines for which they have been demonstrated. This has the
following advantages:
(a) A sealed furnace results in nearly 100 percent capture
of emissions.
(b) Restriction of air flow rate through the control system
minimizes emissions.-'
(c) Emissions of CO from a sealed furnace are sufficiently
concentrated that CO can be recovered for fuel or chemical
synthesis.—
% Air volumes and therefore mass emissions (for a fixed exit concentra-
tion) from a sealed furnace are only about 2 percent as much as from an
equivalent open furnace.
& The recoverable energy from a sealed furnace may approximate 20 to
35 percent of the total power input. For a 30 megawatt furnace this is
approximately equivalent to 15,000 gallons of fuel oil per day. In foreign
countries, this gas is commonly used to fire dryers and plant boilers, or
for chemical synthesis.
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(d) This limitation improves the working environment of employees
because the sealed furnace maximizes capture at the furnace
of emissions potentially harmful to human health.
(e) Sealed furnaces maximize product yield by minimizing loss
of charge material through the stack or as fugitive emissions.
(f) The sealed furnace minimizes power requirements for air
pollution control to about 10 percent that required for
open furnaces.—'
(g) Large sealed furnaces can be readily automated to reduce
labor and operating costs.
(h) Capital cost of control equipment is minimized because
sealed furnaces with their attendant low volumes of exhaust
gas require smaller and less expensive control devices.
(i) The use of sealed furnaces may provide for closer process
control by analysis and monitoring of gas consitutents.
3) Open furnaces with good control systems are permitted for those
products for which sealed furnace technology is not known to be
demonstrated.
4/
-' Energy requirements for equipment to control air pollution on open
furnaces approximate 10 percent of the power input to the furnace. For a
sealed furnace, control equipment power requirements approximate one percent
of the furnace power input.
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4) This alternative permits the use of scrap steel 1n open furnaces
for the production of silvery Iron.
5) This alternative requires control of tap fumes for all furnace
configurations and also requires control of any emissions occurring
from the annular openings at the electrodes of semi-enclosed furnaces.
Disadvantages
1) A regulation that requires sealed furnaces:
(a) Would restrict their use to a certain "family" of products
(precluding manufacture of certain other products), thereby
restricting the flexibility of new furnaces to respond to
market demands.
(b) Could indirectly encourage construction of open furnaces
outside of the United States where pollution requirements
5/
are less stringent in order to retain the flexibility.-
2) Sealed furnaces require additional safety precautions and facilities
for the transfer and treatment of CO gas. (See Issue 2, Chapter XI.)
& Such a trend could ultimately make the United States dependent on
foreign sources for steel additives (ferroalloys) necessary for defense
and consumer goods. However, this reason is somewhat mitigated by our
present dependence on foreign sources for ferroalloy ores (such as manganese)
Foreign suppliers are already beginning to process their own ores and may
one day ship only the ferroalloy to United States markets.
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3) Sealed furnaces may require additional pretreatment of raw
materials for production of some ferroalloys. (See Issue 3,
Item 1, Chapter XI).
4) This alternative could prevent the use of scrap steel turnings
in the production of 50 percent ferrosilicon, thereby increasing
costs and reducing capacity for production of this ferroalloy.
(See Issue 3, Item 3, Chapter XI).
5) -Limited data are available for sealed furnaces producing some
alloys included in Part 3 of this alternative.
(a) Only one sealed furnace each is known to produce high-carbon
ferrochrome and ferrochrome silicon.
(b) Only two sealed furnaces are known to produce 50 percent
ferrosilicon.
2. Alternative No._2.-^' -
No owner or operator shall cause to be discharged into the
atmosphere from any affected facility any gases which:
a. Contain particulate matter in excess of 0.45 kg/Mw-hr
(0.99 Ib/Mw-hr) while that facility produces silicon
6/ The emission limits of Alternatives 1 and 2 are identical._ Some
ferroalloys have been taken out of category c and put into categories a
and b.
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metal, ferrosilicon (50 percent and above), calcium
silicon, or silicomanganese zirconium.
b. Contain particulate matter in excess of 0.23 kg/Mw-hr
(0.51 Ib/Mw-hr) while that facility produces high-carbon
ferrochrome, ferrochrome silicon, silvery iron, ferromanganese
silicon, or charge chrome.
c. Contain particulate matter in excess of 0.07 kg/Mw-hr
(0.15 Ib/Mw-hr) while that facility produces silicomanganese,
ferromanganese, or calcium carbide.
Advantages
1) This alternative is consistent with the "best technology (taking
into account the cost)" requirement of the Clean Air Act.
2) This alternative permits 50 percent ferrosilicon, high-carbon
ferrochrome, and ferrochrome silicon to be produced in open
furnaces.
3) This alternative permits the use of scrap steel turnings for
producing 50 percent ferrosilicon and silvery iron. (See
Issue No. 3, Item 3, Chapter XI).
4) The technology to produce ferromanganese, silicomanganese and
calcium carbide in sealed furnaces is well demonstrated by over
20 years experience in foreign countries.
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5) This alternative increases the industry's flexibility. Fewer
sealed furnaces will be built since fewer products will be
required to be produced in them.
6) This alternative minimizes the number of products which will
require pretreatment of raw materials.-'
\
7) This alternative, by increasing the allowable number of open
furnaces, may decrease any tendency of the domestic industry to
build new furnaces outside the United States.
8) Advantage 5 of Alternative Number 1 applies.
9) The emission limitations of categories a and b of this alternative
could be easily met through use of sealed furnaces for those
products for which sealed furnaces have been demonstrated.
10) For category c of this alternative, Advantages 2(a) through 2(i)
of Alternative Number 1 apply.
Disadvantages
1) Open furnaces, with their inherently larger air volumes, will:
(a) Emit more participate than the sealed furnace.-/
~U Ferromanganese, silicomanganese, and calcium carbide are produced
in sealed furnaces in foreign countries without substantial feed pre-
treatment.
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(b) Consume greater quantities of energy and incur higher
operating costs for air pollution control than sealed
furnaces.
2) This alternative fails to encourage the development of technology
to overcome the limitations in product flexibility of the sealed
furnace.
3) Disadvantages 1 and 2 of Alternative Number 1 apply to category
c.
3. Alternative No. 3.
No owner or operator shall cause to be discharged into the
atmosphere from any affected facility any gases which:
a. Contain particulate matter in excess of 0.45 kg/Mw-hr
(0.99 Ib/Mw-hr) while that facility produces silicon
metal, ferrosilicon (50 percent and above), calcium
silicon, or silicomanganese zirconium.
b. Contain particulate matter in excess of 0.23 kg/Mw-hr
(0.51 Ib/Mw-hr) while that facility produces high-carbon
ferrochrome, ferrochrome silicon, silvery iron, charge
chrome, silicomanganese, ferromanganese, ferromanganese
silicon, or calcium carbide.
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Advantages
1) This alternative permits the use of open furnaces for the production
of all ferroalloys.
2) This alternative permits the use of scrap steel for the production
of ferrosilicon.
3) This alternative does not introduce any problems of product
flexibility.
4) This alternative will not encourage the domestic industry to
build new furnaces outside the United States.
5) This alternative will also permit use of sealed furnaces where
appropriate.
6) Advantage 5 of Alternative Number 1 applies.
Disadvantages
1) Disadvantages 1 and 2 of Alternative Number 2 apply.
2) This alternative does not require new facilities to utilize
the best methods of air pollution control for some ferroalloy
products.
4. Alternative No. 4.
No owner or operator shall cause to be discharged into the
atmosphere from:
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a. Any affected open furnace facility any gases which contain
participate matter in excess of 0.45 kg/Mw-hr (0.99 Ib/Mw-hr)
while that facility produces silicon metal, ferrosilicon
(50 percent silicon and above), calcium silicon, or silico-
manganese zirconium.
b. Any affected open furnace facility any gases which contain
particulate matter in excess of 0.23 kg/Mw-hr (0.51 Ib/Mw-hr)
while that facility produces high-carbon ferrochrome, ferro-
chrome silicon, silvery iron, charge chrome, silicomanganese,
ferromanganese, ferromanganese silicon, or calcium carbide.
c. Any affected sealed furnace facility any gases which contain
particulate matter in excess of 0.07 kg/Mw-hr (0.15 Ib/Mw-hr)
while that facility produces silicomanganese, ferromanganese,
calcium carbide, high-carbon ferrochrome, nominal 50 percent
ferrosilicon, or ferrochrome silicon.
Advantages
1) Advantages 1 through 4 of Alternative Number 3 apply to categories
a and b of this limitation.
2) Categories a and b of this limitation require any operator installing
open furnaces to use best control technology for open furnaces.
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B.
3) Category c of this limitation requires any operator installing
sealed furnaces to use best control technology for sealed furnaces.
4) Advantage 5 of Alternative Number 1 applies.
Disadvantages
1) Disadvantages 1 and 2 of Alternative Number 2 apply to categories
a and b of this limitation.
2) This alternative permits greater emissions from an open furnace
than from a sealed furnace even when producing the same product.
This could discourage the installation of sealed furnaces.
Alternative Standards for Carbon Monoxide (CO)
1. Alternative No. 1.-'
No owner or operator shall cause to be discharged into the
atmosphere from any affected facility any gases which contain
on a dry basis, 20 or greater volume percent of carbon monoxide.
Combustion of such gases under conditions acceptable to the
Administrator shall constitute compliance with this requirement.
y Consultation with a manufacturer of CO flares and incinerators
revealed that CO will support combustion in air at 12.5 percent or greater
CO by volume. (The lower limit is subject to minor variation depending on
the gas's temperature and humidity.) In the open furnace, CO burns upon
contact with ingested air at the surface of the charge material. In semi-
enclosed and sealed furnaces, which operate at slight positive pressure,
the CO exits from the furnace at a concentration of between 50 and 90
percent by volume.
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Advantages
1) The operation of open furnaces is not affected.
2) The operator using semi-enclosed or sealed furnaces must flare
the furnace gas or use it as fuel.
3) Enforcement and compliance are simple and inexpensive.
Disadvantages
None apparent.
2. Alternative No. 2.
Set no standard of performance for CO. Individual States will set
standards on the basis of air quality.
Advantages
None apparent.
Disadvantages
1) This would not require installation of best demonstrated technology
to preclude the creation of new air pollution problems by sealed
or semi-enclosed furnaces.
2) This could result in high localized concentrations of CO.
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C. Alternative Standards for Visible Emissions
1. Alternative No. 1.
No owner or operator shall cause to be discharged into the
atmosphere from any affected facility any gases which exhibit 10
percent opacity or greater.
Advantages
1) This alternative is consistent with the intent of the Clean Air
Act to mandate best technology.
2) This alternative requires control of tap fumes.
3) Open furnaces with scrubber or baghouse control devices can meet
this limitation.
4) This alternative minimizes the emissions since visibility of the
exhaust is a gross indication of particulate mattar content.
Disadvantage
It is possible that this limitation can be exceeded while the
9/
mass emission limitation is being met.—
-' One open furnace producing 75 percent ferrosilicon equipped with
a closed suction baghouse had emissions of up to 15 percent opacity while
nearly meeting a mass standard of 0.99 Ib/Mw-hr.
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2. Alternative No. 2.
No owner or operator shall cause to be discharged into the
atmosphere from any affected facility any gases which exhibit
20 percent opacity or greater.
Advantages
1) Advantages 1 through 3 of Alternative No. 1 apply.
2) It is not likely that this requirement can be exceeded while
still meeting the mass emission requirement.
Disadvantage
This alternative would permit greater emissions.
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IX. ENFORCEMENT ASPECTS OF THE PROPOSED STANDARDS
The proposed standard includes limitations on particulate matter,
visible, and carbon monoxide emissions. Open, sealed, and semi-enclosed
furnaces with proper control equipment could be used to meet the proposed
standard.
A. 'Particulate Matter Standard
The proposed standard limits all emissions of particulate matter from
the electric submerged arc furnace and includes those which occur during
the tap cycle of the furnace. Uncontrolled particulate matter emissions
will vary with the alloy produced, type and size of raw materials, operating
techniques, furnace design, and the input power at which the furnace is
operated.
When a new furnace is installed, a record should be made of the products
for which the furnace is designed and the maximum furnace power rating for
each. The control system must be designed to assure that the standards of
performance for each product will be achieved when the furnace is producing
at the maximum power input for that product. If possible, the performance
test should be performed when the furnace is producing the product having
the emissions most difficult to control. For example, the performance test
for a furnace designed to produce 75 percent ferrosilicon and silicon metal
should be performed while producing silicon metal.
Control devices on existing furnaces exhaust the effluent in three
possible ways: (1) through a single stack, (2) through multiple stacks,
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and (3) unconstrained (total absence of a stack or duct). Enforcement
aspects of measuring particulate matter which vary according to these
categories, are discussed below:
1. Effluent discharged through a single stack.
This configuration is most easily tested. The methods for measurement
of particulate emissions are specified in 40 CFR 60 (Reference Methods 1,
2, 3, 4, and 5).
New sources should be designed to assure optimum sampling conditions.
For example, the optimum sampling location is not less than 8 diameters
downstream and two diameters upstream from anything in the duct which
might disturb the gas flow. Although the Methods permit deviation
from these optimum criteria, there should be a design goal to ensure the
most accurate and precise results possible of any measurements of emissions,
Platforms, utilities and sampling ports should be located to
facilitate sampling at new or modified sources.
2. Effluent exhausted through multiple stacks.
The problems presented by this possibility are merely time and
expense. The number of tests required and their attendant costs may
make a rigorous compliance test impractical. In such a case, the
source and the enforcement agency should agree on a specific plan
for measuring emissions which will provide the data necessary to
determine compliance at a reasonable cost. The optimum plan will
vary from source to source.
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Portable opacity instruments have recently become available
and represent low-cost means of showing comparability between stacks.
These instruments may be a desirable tool for use in a test plan.
3. Effluent not constrained within a stack.
This category includes emissions that discharge through roof
monitors, open or pressurized baghouses, and, in some cases, open-
faced filters. Performance test methods for this category have not
been specified because of the lack of proven test techniques, a
consequence of limited sampling experience.
Several problems surface when attempts are made to measure
unconstrained effluent. The first is the difficulty of obtaining
a representative sample. Large and sometimes multiple areas (cross
sections) from which emissions exhaust make it impractical or impossible
to sample at sufficient points to represent the entire discharge area.
The accuracy of any alternative depends on the validity of the
engineering assumptions necessary. One alternative is to subdivide
the total flow area into sub-areas which are then sampled. Sampling
may parallel Method 5, or other techniques such as high-volume sampling
may be used. One scheme includes traversing across the horizontal
cross section of a roof monitor with a high-volume sampler. Another,
used in the aluminum industry, requires multipoint sampling by a
permanent sampling manifold mounted beneath the roof monitor. The
manifold discharges to a small stack which can be sampled using Method 5.
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A second problem results from the very low flow rates commonly
encountered in these systems. Often they cannot be measured with
conventional sampling equipment. This precludes accurate isokinetic
sampling and determination of volumetric flow rates. The isokinetic
sampling problem is usually resolved by determining average velocities
using extremely sensitive measuring devices and then sampling at this
average rate. Volumetric flow rate may be determined in a similar
manner. (It is usually possible to determine volumetric flow rate
more accurately by measuring flow on the inlet side of the control
device.)
The presence of dilution air presents a third and equally serious
impediment to determining accurate emission values. To determine if
a source complies with a concentration limitation, a correction must
be made for any dilution air present. To determine a mass emission
rate requires knowledge of the actual volumetric flow rate at the
sampling location. In either case, it is necessary to measure dilution
air flow rates. The difficulty in measuring dilution air may prevent
or at least will seriously limit accurate emission measurements.
Due to these problems, the accuracy and precision with which the
mass rate of emissions can be determined appears limited and, in
fact, the configuration of certain sources totally defies representative
sampling. Because of the potential cost of testing, the source and the
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enforcement agency should agree on a specific test plan or means
for determining compliance prior to construction of a new source.
EPA is reviewing discharge configurations from control
devices being sold in an attempt to improve test procedures.
As this investigation progresses, certain criteria can probably be
specified which will improve the accuracy of testing. Until such
criteria are available, new plants should be equipped with exhaust
systems which will allow representative sampling.
B. Visible Emissions Standards
The visible emissions standards serve three purposes:
1. To assure the capture and control of all particulate matter
emissions from the furnace and its tapping station.
2. To provide a quick and inexpensive means of enforcing proper
maintenance and operation of the control device, furnace hoods,
tapping hoods, and ducting.
3. To ensure that dust captured by the control device(s) is properly
handled and not reentrained in the atmosphere.
C. Carbon Monoxide Standard
Enforcement of the CO standard is easy. An open furnace cannot violate
the standard since the CO is burned with ingested air at the surface of the
charge materi al.
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The gases exhausted from the control device on a semi-enclosed or
sealed furnace contain 50 to 90 volume percent CO. The exhaust gases
from these furnaces must be flared prior to entering the atmosphere or
must be used in other processes.
D. Emission Monitoring
The proposed standard requires that a photoelectric or other type
smoke detector and recorder be installed to continuously monitor and
record the opacity of gases discharged into the atmosphere from the
control device(s).
EPA proposed performance specifications for opacity monitors on
September 11, 1974 (39 FR 32852). Instruments commercially available
which conform to these specifications are capable of measuring opacity
within a narrow path 50 or more feet long. Instruments which are
installed and operated in accordance with the specifications will
produce reliable opacity data. Effluent discharged through a stack or
duct can be readily monitored.
E. Monitoring of Operations
To ensure that the furnace and pollution control systems are being
operated within design parameters and at conditions for which the
compliance tests are representative, the following records must be made:
1. A daily record of the product being produced.
2. A daily record of the charge constituents to the furnace
including the proportions by weight of each constituent.
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3. Records of the average power input to the furnace during each cyc7e,
in megawatts.
4. Records of the time and duration of each tapping period and the
identification of material tapped (slag or product).
In addition, a wattmeter must be installed, calibrated, maintained, and
operated to continuously monitor and record the power consumption of the
furnace.
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X. MODIFICATIONS
Under conditions defined in section 111 of the Clean Air Act and
supplemented in §60.2 of 40 CFR 60, an existing source which is modified
may become subject to standards of performance.
Modifications to a ferroalloy furnace which could render the facility
subject to standards of performance are changes in raw materials which
force physical alterations to the furnace, changes in product grades or
"families" which increase emissions, and increasing the transformer capacity
to increase production (hence emission) rates. These changes are ways to
meet market demands, increase production, or respond to availability of
raw materials without investment of the large amount of capital necessary
for an entirely new furnace.
Any such modification will require that the air pollution control
system on an existing furnace be upgraded to meet the standards of
performance. This may be very costly, and in some cases almost
physically impossible. Reasons for this are:
A. The building which houses the furnace may prevent installation
of a hood or furnace cover because of space limitations above
the furnace.
B. Prohibitively expensive revisions of electrical components may
be required to install a hood or cover.
C. Installation of a hood or cover may require changes in the
furnace feed delivery system.
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4 D. Extensive changes to electrode columns and suspension systems
might be required.
Changes to the ferroalloy electric submerged arc furnace that would
not be considered a modification include:
A. Changing proportions of the charge materials to the furnace
if the products are ferroalloys for which the furnace was
originally designed.
B. Changes in reducing agents, types of scrap steel, or use of
slags to produce ferroalloys for which the furnace was
originally designed.
C. Replacement of carbon hearths, furnace linings, mix chutes,
furnace covers, hoods, ductwork, replacement of transformers
in kind, furnace digouts, tap hole repairs, or electrode spacing
adjustments, so long as production capacity was not increased and
the modifications did not result in changing the furnace capability
to permit manufacture of products other than those for which the
furnace was originally designed.
The impact of compliance with the standards of performance for new sources
will vary depending on the type of furnace. It is generally accepted that
the open and perhaps even the semi-enclosed furnaces cannot be economically
altered to achieve the standards of performance if it is based on technology or
emission rates from sealed furnaces. In such a case it would be less expensive
to construct an entirely new facility.
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A. Open Furnaces
An existing open furnace can be substantially modified, upgraded and
controlled for about $3 to $5 million.. An equivalent new installation
would cost $15 to $20 million. Obviously, the economics dictate up-
grading. A modified existing open furnace with proper control equip-
ment can comply with the proposed standards of performance for a new furnace.
B. Semi-Enclosed Furnaces
If the cover is removed from an existing semi-enclosed furnace to
permit the manufacture of a greater variety of alloys, the modified
furnace should become subject to the standards of performance. As with
the open furnace, a semi-enclosed furnace modified in this way probably
can comply with the standards if proper control equipment and adequate
hooding are used.
C. Sealed Furnaces
The possibility of a modification to an existing sealed furnace is
remote since there is only one in the United States. It is difficult to
imagine a modification which would preclude the ability of a sealed
furnace to meet the standards of performance for new sources. One
possible (but highly improbable) modification would be conversion to an
open furnace. The incentive would be to permit production of a different
product family than that for which it was designed. This very expensive
change would also require significant alterations to the transformer and
electrodes. The modified furnace could be controlled to meet the proposed
standard of performance.
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.XI. MAJOR ISSUES CONSIDERED
The mandate to base the standards of performance for ferroalloy electric
submerged arc furnaces on the best air pollution control technology which
has been demonstrated and which is economically viable seems clear.
In effect, however, repercussions from a standard which would allow only sealed
furnaces could be felt far beyond the ferroalloy industry.
A standard which restricts new furnaces to the totally sealed configuration
could:
A. Result in multinational corporations building new open furnaces
outside the United States where pollution requirements are less
stringent.
B. Cause the demise of portions of the United States ferroalloy
industry and place the country in the untenable position of
dependence on foreign sources of some steel additives (ferroalloys)
necessary for defense and consumer goods.—
The major areas of issue are tabulated as follows:
A. Do sealed furnaces represent demonstrated technology?
]_/ This reason is somewhat ameliorated by the fact that the United
States ferroalloy industry must rely on foreign sources for some ores
(such as manganese and chromium ores). These foreign suppliers are
beginning to process their own ores and may soon ship only the ferroalloy
to the United States market.
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B. Does use of the sealed furnace create a safety hazard?
C. Does use of the sealed furnace place the United States
industry at an economic disadvantage in the world market?
A. Issue 1. Does the Sealed Furnace Represent Demonstrated Technology?
Discussion
Section lll(a)(l) of the Clean Air Act, as amended, states: "The
term 'standard of performance1 means a standard for emissions of air
pollutants which reflects the degree of emission limitation achievable
through the application of the best system of emission reduction which
(taking into account the cost of achieving such reduction) the
Administrator determines has been adequately demonstrated." The term
"available control technology" is further defined in a report of the
Committee on Public Works, United States Senate, when air pollution con-
trol Was still a function of the Department of Health, Education and
Welfare, as follows: ". . . 'available control technology,' is intended
to mean that the Secretary should examine the degree of emission control
that has been or can be achieved through the application of technology
which is available or normally can be made available. This does not
mean that the technology must be in actual routine use somewhere. It
does mean that the technology must be available at a cost and at a time
which the Secretary determines to be reasonable. This implicit con-
sideration of economic factors in determining whether technology is
'available' should not affect the usefulness of this section. The
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overriding purpose of this section would be to prevent new air pollution
problems, and toward that end, maximum feasible control of new sources
at the time of their construction is seen by the Committee as the most
effective and in the long run, the least expensive approach."^ '
Sealed furnaces have been used in foreign countries to manufacture
silicomanganese, ferromanganese and calicum carbide since about 1954/48)'
In Japan and Norway, all standard ferromanganese is produced in sealed
furnaces. Almost all silicomanganese produced in Norway is made in
sealed furnaces and future plans presume that, ultimately, all will be produced
in them/ EPA measured emissions from sealed furnaces producing silico-
manganese and ferromanganese in Porsgrunn, Norway/ '* ^52'
Sealed furnaces have been used to produce ferromanganese, silicomanganese
and calcium carbide in Japan since at least 1962/53^' ^54^ The Japanese
also use sealed furnaces to produce 50 percent ferrosilicon (two furnaces
which have operated since 1968 and 1972 respectively), 75 percent ferro-
silicon (one furnace which has operated for 2 to 3 years), ferrochrome
silicon (one furnace, operated since 1970), and high-carbon ferrochrome
(one furnace, operated since 1971). These are the only sealed furnaces known
to be producing these ferroalloys/ ' Emission measurements were also
made by EPA on sealed furnaces in Japan producing 50 percent ferrosilicon,
ferrochrome silicon, and high-carbon ferrochrome/56'
Union Carbide of Canada has installed and is operating a large sealed
furnace for the production of ferromanganese and silicomanganese, and
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Interlake Steel Corporation 1s planning a similar Installation 1n Mexico.
The only known sealed furnace for the production of ferromanganese and
silIcomanganese in the United States is operated by Airco Alloys and
Carbide at its Theodore, Alabama, plant.
Conclusions
Ferroalloy manufacturers compete in the world market not only for the
sale of ferroalloys, but for ores and other raw materials as well. Since
foreign producers economically make a variety of ferroalloys in sealed
furnaces using raw materials also available to the United States ferroalloy
industry, it must be concluded that use of sealed furnaces is technically
feasible in the United States and that sealed furnaces are "demonstrated
technology."
B. Issue 2. Does the Use of Sealed Furnaces Present a Safety Hazard?
The United States ferroalloy industry has stated that sealed furnaces are
unsafe for the following reasons^57)' ^58^
1. Fusion or bonding together of the raw material charge is
characteristic of production processes for 75 percent ferrosilicon
and silicon metal. Similar behavior, but to a lesser degree, can
occur in the production of the high-silicon grades of ferrochrome
silicon and silicomanganese. Silicomanganese operations may be
subject to "slag boils" where the charge materials become crusted
over with slag which prevents uniform descent of the feed material
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within the furnace. Such fusion or crusting of materials requires
the use of open furnaces to permit the charge to be "stoked" to
allow Its uniform descent and uniform evolution of gas formed by
the reduction of the ores.
2. Moisture from water in the charge or from water leaks in furnace
components can result in an explosive-type gas release which may
lift the furnace cover and eject a major portion of the furnace
contents.
3. Production of high-silicon ferrosilicon and silicon metal is
characterized by high-temperature gas "blows," generally in the
vicinity of the electrodes. Jets of hot gas originate directly
from the high-temperature zones of the furnace near the bottom of
the electrodes. Hot as a cutting torch, they can destroy furnace
components.
4. Scrap steel is normally used for the domestic production of
ferrosilicon alloys. Such a highly conductive raw material
can short out the electrodes through the charge chutes, causing
component damage and water leaks if sealed furnaces are used.
5. The sealed furnaces generate carbon monoxide, a hazard to personnel.
In open furnaces, the carbon monoxide is combusted to carbon dioxide
with ingested air at the hot surface of the charge material.
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Discussion
The preceding items were investigated during the development of standards
of performance for the industry with results as follows:
1. The problems of slag boils and crusting or bridging of the furnace
charge constituents are more commonly associated with production
of the high-silicon (> 75 percent) ferroalloys. These problems
are no longer considered serious for the production of calcium
carbide, ferromanganese, and silicomanganese in sealed
furnaces.(59)' (60)> (61)> <62> "Enclosed furnaces are being
used increasingly where raw materials do not collect to build
bridges within the furnace, but instead sink evenly of their own
accord. Examples include the production of pig iron, carbide,
and the ferroalloys ferromanganese and silicomanganese."^63^
In a meeting with EPA engineers, a representative of one major
ferroalloy producer in the United States stated that properly
operated sealed furnaces producing ferromanganese, silicomanganese,
and calcium carbide are no more dangerous than equivalent open
furnaces producing these products.
2. EPA engineers discussed with personnel of foreign plants the
danger of explosions from water contained in the feed or from
water leaks. Foreign industry personnel state that they feel
safe working around a sealed furnace and that working conditions
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are vastly improved by them.^64'* '65' They elaborated that
fatalities are not unique to sealed furnaces; injuries and
fatalities have also been caused by expulsion of the charge
from open furnaces during gas "blows.
,,(66)
Explosions did occur during early development of sealed furnace
technology, but this type of hazard has been overcome with increased
knowledge of the operation and design of closed furnaces. Such
incidents are precluded by:'67)' (68>> (69>> (70>> <71>» ™
a. Where necessary, proper pretreatment of furnace charge materials.
b. Proper design of the furnace and its charging system.
c. Proper monitoring of the process. This may involve monitoring:
(1) furnace feed and product rates; (2) chemical compositions
of furnace feed, product and slag; (3) furnace temperatures;
(4) moisture content of charge material; (5) furnace power
consumption; (6) furnace off-gas chemical composition, and
possibly other furnace operating parameters.
3. It is generally agreed that the technology has not been developed
to produce silicon metal and ferrosilicon which contains greater
than 75 percent silicon in sealed furnaces. However, a Japanese
manufacturer of electric submerged arc furnaces predicts that silicon
metal will be produced in sealed furnaces by 1977.
(73)
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4. Scrap steel is normally used by the United States industry for
the open furnace production of ferrosilicon alloys. Union Carbide
is using a semi-enclosed furnace with steel scrap feed to produce
50 percent ferrosilicon.
The Japanese use pelletized iron ore as a feed material to their
sealed furnaces producing 50 percent ferrosilicon and "mill scale"
to the sealed furnace producing 75 percent ferrosilicon. They state
that a reason for this is that large quantities of high-quality
steel scrap are not available and economics justifies use of the
Iron ore.
One reason given by the United States industry for inability to
use scrap steel in a sealed furnace (although it is used in the
semi-enclosed furnace) is that it can conduct electricity from the
electrodes to the mix delivery bins and cause arcing which could
severely damage furnace components.
5. Foreign plants with sealed furnaces use CO alarm
systems, proper building ventilation and proper maintenance of
the CO handling system to minimize hazards of this gas. Semi-
enclosed furnaces, which present the same CO hazards, have been
used for years by the United States industry. Obviously, the
methods for safely handling CO gas are proven.
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Conclusions
The following conclusions are made regarding the safety aspects of
ferroalloy production in sealed furnaces:
1. Sealed furnaces for the production of silicomanganese, ferro-
manganese, and calcium carbide have been used in foreign countries
for over 20 years. When properly monitored, operated, and maintained,
sealed furnaces for the manufacture of those products appear to be more
dangerous than open furnaces.
2. There is no known technology for the production of ferrosilicon
with greater than 75 percent silicon in sealed furnaces.
3. Production of 50 percent ferrosilicon in sealed furnaces is being
safely accomplished in Japan with iron ores as a feed material.
Although no known use of scrap steel as feed material to a sealed
furnace exists, it does appear technically possible.
4. The safe handling of carbon monoxide gas has been accomplished by
the domestic and foreign ferroalloy industries.
5. The Japanese are also safely using sealed furnaces as follows:
a. One has produced 75 percent ferrosilicon since about September
1971.
b. One has produced high-carbon ferrochrome since 1971.
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c. One has produced ferrochrome silicon since June 1970.
These are the only known sealed furnaces producing these products.
6. The safe production of ferromanganese, silicomanganese and calcium
carbide in sealed furnaces has been demonstrated. A standard for
these products could be recommended based on the sealed furnace.
Recommendations
Since the safe production of 50 percent ferrosilicon has been demonstrated
only when using iron ore feed, and since only one sealed furnace each exists
to produce 75 percent ferrosilicon, ferrochrome silicon, and high-carbon
ferrochrome, standards for these products should be based on open furnaces.
Standards for these products should be reviewed as additional experience
with sealed furnaces is accumulated.
C. Issue 3. Would a Regulation That Mandates Sealed Furnaces Place the
United States Industry at an Economic Disadvantage in the
World Market?
The United States ferroalloy industry has stated that successful sealed
furnace technology and economics in foreign countries cannot be directly
extrapolated to the domestic industry for the following reasons:^74''
1. Sealed furnace operation requires extensive pretreatment of raw
material. This may include sintering or pelletizing.
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2. Foreign producers have operating schedules and practices which
allow greater furnace downtime for maintenance.
3. The only known sealed furnaces producing 50 percent ferrosilicon
use iron ore instead of scrap steel. This is not economical in
the United States where steel scrap is abundant and cheap.
4. A sealed furnace is restricted to production of one "family" of
products. Unless a large captive market for that family exists,
the United States industry must maintain the flexibility to produce
a variety of products required by rapidly changing world demands.
Discussion
1- Pretreatment of raw materials.
Almost all ferroalloy producers pretreat their raw materials in
some way to obtain smooth furnace operation and the desired quality
of the product.(76)» (77)» (78> Pretreatment processes include crushing,
sizing, mixing, drying, sintering, and pelletizing. Crushing and sizing
of raw materials are performed at nearly all ferroalloy plants and for
all types of furnaces. Raw materials are also mixed at nearly all
ferroalloy plants, regardless of the furnace type, to meet product
specifications and to obtain the composition, physical properties,
and (sometimes) moisture content desirable for safe, smooth furnace
operation.(79)> (8°)» (81)» <82) Raw materials are often dried for all
three types of furnaces. Dry feed materials result in reduced off-gas
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volumes and smoother furnace operation. Sintering and pelletizlng are
less common pretreatment processes. These could be used 1n conjunction
with any type of furnace, but are most commonly used with foreign sealed
furnaces. Both pell eti zing and sintering are means of upgrading less
expensive or friable ores which could not otherwise be used in ferroalloy
furnaces because of 'bridging (i.e., charge material fusing to prevent
uniform descent of charge into a furnace's reaction zone), high raw
material losses caused by its entrainment in the furnace gases, and
low porosity which would prevent escape of gases from the reaction zone.
Also, by pell eti zing or sintering dust captured by the air pollution
control system, it can be recycled as feed to the furnace.
Ferromanganese and silicomanganese are produced in sealed furnaces
without drying, sintering, or pelletizing raw materials. Such furnaces
were observed in Norway and Belgium by EPA engineers and a representative
of The Ferroalloys Association.
^83^'
EPA engineers monitored the
process and measured emissions from two of these furnaces in Norway,
one producing silicomanganese and the other producing ferromanganese.
A sealed furnace in the United States has produced ferromanganese and
silicomanganese without extensive material pretreatment. EPA engineers
observed sealed furnaces producing these products in Japan. Some used
drying, sintering, and pelletizing as pretreatment processes, while
others only performed routine mixing, crushing, and sizing.
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The Japanese sealed furnace producing high-carbon ferrochrome uses
materials which are dried, crushed, pelletized, dry roasted, and then
"hot charged" at 900°C to the furnace. Pellets charged to the furnace
may be either "prereduced" (provided coke is added to the ore before
pelletizing) or not. Cheaper friable ores are used in this furnace.
Pretreatment for the Japanese sealed furnace producing ferrochrome
silicon consists of material sizing and drying. No special pretreatment
of charge materials is performed for the Japanese sealed furnace producing
75 percent ferrosilicon. Fine iron ore is pelletized and baked in a shaft
rfurnace prior to being fed to the sealed furnaces producing 50 percent
ferrosilicon.
Although some sealed furnaces may be used without pretreatment
processes such as drying, pelletizing, or sintering, several reasons
may favor such preprocessing:
a. Even with the added cost of preprocessing, cheap and abundant
fine-sized or friable ores may be less expensive than the
relatively expensive lump ore. (Use of friable ores may
become more common as world supplies of high-grade "lump" ores
are depleted.)<85>' (86>> <87>
b. Preprocessing ores increases the product yield.7'5 ^88^
c. Twenty to 35 percent of the energy supplied to a closed furnace
can be recovered by fueling preprocessing equipment such as
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dryers, pellet furnaces, and sintering machines with carbon
monoxide-rich exhaust gas from the furnace.
d. Preprocessing may decrease furnace power consumption by as
much as 10 percent.<9°>- <91>' <92)
e. One preprocessing step, sintering, may reduce coke consumption
and increase furnace thermal efficiency.
(93)
f. Preprocessing reduces furnace particulate emissions. '*
g. Preprocessing equipment permits recycle of particulate matter
collected by emission control equipment.^ '' (For a
closed furnace producing ferromanganese, some 21.2 tons of
particulate may be recovered and recycled for every 100 tons
of alloy produced.
x(96)
2. Foreign operating practices allow more furnace down-time.
Personnel at foreign installations who have experience with all
three types of furnaces state that maintenance requirements are no
greater for sealed furnaces than for other types of comparable
size/97^' ^98^J ^"' "Due to the heat from the burning reaction
gases above open furnaces, there has been, throughout the years,
a tendency towards more down-time on these furnaces than on covered
ones, in spite of the Tatter's more complicated equipment.
,,(100)
Operating schedules and practices for installations in foreign
countries do not appear to allow any greater furnace down-time for
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maintenance and repair than that experienced at United States
installations. Company personnel estimate that the sealed furnaces
tested by EPA in Norway operate 97 to 98 percent of the time for the
ferromanganese furnace, and 96.2 to 98.2 percent of the time for the
silicomanganese furnace." ' Japanese ferroalloy manufacturers
estimate that sealed furnaces producing ferromanganese, silicomanganese,
high-carbon ferrochrome, and ferrochrome silicon operate from 95 to almost
100 percent of the time based on their experience to date.' ' The
United States ferroalloy industry estimates that normal furnace operating
times in the United States vary from 90 to 95 percent. A large percentage
of furnace down-time is for maintenance of air pollution control equipment
common to all three types of furnaces.^ ' Maintenance for the much
larger air pollution control equipment on open furnaces should far
exceed that for similar equipment on totally enclosed furnaces,
primarily because the open-furnace equipment must handle gas volumes
typically 50 times larger.
3. Sealed furnaces producing 50 percent ferrosilicon are charged with
iron ore. Use of ore is not economical in the United States"
The two known sealed furnaces which produce 50 percent ferrosilicon
(located in Japan) use iron ore as a feed material instead of the scrap
steel feed normally used by the United States industry. The United States
ferroalloy industry used about 270,000 tons of scrap steel for the
production of 50 percent ferrosilicon and about 500,000 tons of scrap
steel for the production of all grades of ferrosilicon in 1972. Their
reasons for using steel scrap rather than iron ore are as follows:
129
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a. Steel scrap turnings have historically been abundant and low
priced. (They are the lowest cost iron sources for United States
ferrosilicon production.)
b. The use of steel scrap results in less electrical energy and
coke consumption than if iron ore or mill scale were used.
c. Because of decreased charge resistance, furnace production
capacity is greater with steel scrap than with iron ore or
mill scale. This increased capacity is equivalent to about
60,000 tons per year of 50 percent ferrosilicon which has
a value of about $9,600,000.
d. The type of scrap steel used for ferroalloy production is
not suitable for recycling to new steel and, if not used
for ferroalloys, would add to the solid waste disposal problem.
e. Delivered price is high for the select grades of iron ore
required to produce 50 percent ferrosilicon.
In discussions with Japanese ferroalloy producers, EPA engineers
asked if use of the sealed furnace for producing 50 percent ferrosilicon
would preclude the use of scrap metal and how the use of iron ore affected
the economics of production. They answered that the use of iron ore in
a sealed furnace is economically better than the use of scrap steel and
that this is true in the United States as well as Japan because:
130
.(105)
-------
a. Japan has to import Iron ores while the United States has
natural iron ore resources.
b. Iron ore assures a more stable furnace operation.
„ c. Iron ore provides easier control against product impurities
in production of 50 percent ferrosilicon compared to scrap
steel.<106>
Although no unequivocal conclusion can be drawn from the above, it
appears that scrap steel has the economic advantage as a raw material
for 50 percent ferrosilicon production in the United States.
4. Sealed furnaces do riot have the flexibility necessary to produce
a variety of products.
Manufacturers of ferroalloy products and manufacturers of ESA
furnaces stated the following:
a. For a given furnace design, only certain products can be
economically manufactured, regardless of whether the furnace
construction is the open or totally enclosed type. It is not
economical to dejsign and use a large ESA ferroalloy furnace for
several product lines. To do so requires movable electrodes and
multiple transformer capacities, since combinations of raw
materials differ in resistivity for different ferroalloy products.
Consequently, crucible size, electrode spacing, and transformer
size are a function of the product being manufactured. Therefore,
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to minimize capital investment in the transformer, to reduce
down-time for changeover (moving electrodes, etc.), to reduce
waste produced by a furnace, and to optimize furnace efficiency,
companies design furnaces for manufacture of only one family
of products. Within those families, it is possible to switch
products in a totally enclosed furnace just as readily as in
an open furnace. For products outside of the design family of
products, however, the furnace must undergo substantial re-
construction for changing the electrode spacings. On a sealed
furnace this change requires replacement of the furnace cover.
This reconstruction of sealed furnaces to produce other products
is prohibitively expensive. Modification of an open furnace to
produce another family of products requires replacement of the
hood. The costs for changing from one product family to another
for open furnaces is significantly less than those for sealed
furnaces. Limited product flexibility could ultimately result
in decreased intercorporate competition.
b. In order to remain competitive, manufacturers of
ferroalloy products are converting to use of larger
furnaces. 007), 008), (109), (110) New fem)alloy furnaces
will probably be 30 Mw or larger because large furnaces require
less labor, less raw material and less electric power per ton
of product. In most cases, the large furnace also requires
a lower capital investment per ton of production.
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Conclusions
Based on the Information available, the following conclusions are made:
1. a. Ferromanganese and silicomanganese can be safely and economically
produced in sealed furnaces with or without substantial pre-
treatment of feed material.
b. Calcium carbide can be safely produced in sealed furnaces without
additional pretreatment beyond that already performed by domestic
producers.
c. For products other than those listed in (a) and (b) above,
foreign manufacturers use varying levels of feed pretreatment,
but can safely and economically produce 50 percent ferrosilicon,
75 percent ferrosilicon, high-carbon ferrochrome, and ferro-
chrome silicon in sealed furnaces.
2. The argument that maintenance requirements and operating schedules
of foreign manufacturers are significantly different from those of
domestic users seems unfounded.
3. There appear to be several economic advantages for the United States
industry to use steel scrap rather than iron ore for the production
of ferrosilicon.
4. It appears that the use of sealed furnaces would place the
domestic industry at a competitive disadvantage in the world
market by restricting the flexibility of new furnaces to respond
to fluctuating market demands.
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Recommendations
It is recommended that the standards of performance allow open
furnaces to be used in conjunction with the best available control
equipment. Although sealed furnaces are superior from an air pollution
control aspect, restricting the industry to this process could ultimately
result in limited product flexibility and possible decreased intercorporate
competition. The disadvantages arising from decreased competition out-
weigh the incremental benefits of the additional reduction in air
pollution. EPA's Control Systems Laboratory is further investigating the
technical and economic feasibility of using sealed furnaces to produce all
types of ferroalloys. This study could ultimately result in standards of
performance based on sealed furnaces.
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XII. REFERENCES
A. Cited References
1. Webster's Third International Dictionary, 6. C. Merriam Company,
Springfield, Massachusetts, 1966.
2. Fisher, Frank L., "Ferroalloys," Minerals Yearbook, Volume 1,
Bureau of Mines, United States Department of Interior, 1971.
3. Environmental Protection Agency - The Ferroalloys Association
Cooperative Study, Air Pollution Control Engineering and Cost
Study of the Ferroalloy Industry, draft document, January 21,
1974, p. II-l.
4. Data from Department of Commerce, Bureau of the Census Annual
Survey of Manufacturers, SIC number 3313, 1971.
5. "National Air Quality Standards Act of 1970," Report of the
Committee on Public Works, United States Senate, Report No.
91-1196, September 17, 1970, p. 16.
6. Vandegrift, A. E., et al., "Particulate Air Pollution in the United
States," Journal of the Air Pollution Control Association. June 1971,
p. 321-328.
7. Ref. 3, p. 11-10.
8. Ref. 3, p. V-9.
9. Ref. 3, p. VI-8.
135
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10. Ref. 3, p. VI-48.
11. Ref. 3, p. VI-11 to VI-41.
12. Ref. 3, Appendix E, p. 1-75.
13. Ref. 3, p. VI-47.
14. Coetzee, J. J., and Smit, N., "The Production of Ferroalloys,"
presented at the Commonwealth Mining and Metallurgical Congress,
1961, p. 1047.
15. Elutin, V. P., et al., "Production of Ferroalloys Electrometallurgy,"
2nd edition, Washington, D. C., National Science Foundation and
Department of the Interior (translated from Russian by the Israel
Program for Scientific Translations, 1957).
16. Person, R. A., "Control of Emissions from Ferroalloy Furnace
Processing," Journal of Metals, April 1971, p. 19.
17. Duncan, L. J., "Analysis of Final State Implementation Plans - Rules
and Regulations," APTD-1334, EPA Contract No. 68-02-0248, July 1972,
p. 30.
18. Ref. 16, p. 20.
19. Ref. 3, p, VI-26.
20. Ref. 16, p. 24.
136
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21. Letter from Mr. Richard D. Turner, Chromium Mining and Smelting
Corporation, to Mr. John Quarles, EPA, November 15, 1973.
22. Ref. 3, p. VII-16.
23. Environmental Protection Agency, "Ferroalloy Manufacturing Point
Source Category - Effluent Limitations Guidelines and Standards,"
Federal Register, 39 (37): 6806-6812, February 22, 1974.
24. Ref. 21.
25. Durkee, Kenneth R., EPA, International Trip Report, "Survey
of Japanese Ferroalloy Furnaces," August 9, 1973, p. 1-48.
26. Ref. 16, p. 28.
27. Ref. 3, Chapters I-X, Appendices A-G.
28. Ref. 3, p. VI-48.
29. Ref. 25.
30. Kelly, Winton E., "Emissions from Electric Arc Ferroalloy Furnaces
at Elkem A/S Porsgunn Elektrometallurgiske, PEA," Porsgunn, Norway,
EPA Project No. 72-PC-15, June 1973, Table II1-4.
31. Ref. 6.
32. Ref. 3, Appendix E,, p. 1-75.
137
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33. Sullivan, Ralph J., "Preliminary Air Pollution Survey of Manganese
and its Compounds," prepared for U. S. Department of Health,
Education and Welfare under Contract No. PH 22-68-25, October 1969,
p. 1-10.
34. Fredriksen, H., "Pollution Problems of the Norwegian Ferroalloy
Industry," Reprint No. 3197, KJEMI. No. 1, 1972. (EPA Translation
No. TR 1677.)
35. "Pollution Problems by Electric Furnace Ferroalloy Production,"
prepared by SINTEF, the Engineering Research Foundation at the
Technical University of Norway, for the Royal Norwegian Department
of Industry, September 28, 1968, p. 1-17.
36. Horiguchi, et a!., "A Survey on the Actual Conditions of Factories
Handling Manganese Compounds," Sangui Igaku (Japanese Journal of
Industrial Health), 8_ (6): 19-28, June 1966, APTIC Translation
No. TR 1525.
37. Manganese, prepared by Panel on Manganese, Committee on Biologic
Effects of Atmospheric Pollutants, National Academy of Engineering,
under EPA Contract No. 68-02-0542, 1973, Chapter 11, p. 205-211.
38. "Mineral Facts and Problems," Bureau of Mines Bulletin 650, 1970
Edition, p. 245.
39. Ref. 3, p. III-9.
138
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40. Environmental Protection Agency, "Standards of Performance for
New Stationary Sources," Federal Register, 36 (247): 24882-24895,
December 23, 1971.
41. Japanese Industrial Standard JIS-8808-1970, "Methods of Measuring
Dust Content in Stack Gas," revised June 1970.
42. Dobryakov, G. G., et al., "Operation of a Gas-Cleaning System
on a Closed-Top Electric Furnace," Steel in the USSR, May 1971,
p. 2.
43. "Air Pollution Control Technology and Costs in Nine Selected Areas,"
prepared by Industrial Gas Cleaning Institute under EPA Contract
No. 68-02-0301, September 30, 1972.
44. Letter from George A. Watson, The Ferroalloys Association, to
Kenneth R. Durkee, EPA, March 18, 1974.
45. Letter from D. J. Maclntyre, Manager, Environmental Affairs, Union
Carbide Canada, Limited, to Paul A. Boys, EPA, March 9, 1973.
46. Ref. 25, p. 20.
47. Ref. 5, p. 5-17.
48. Lorck, K., "The Development of the Elkem Covered Rotating Furnace
for the Production of Carbide and Ferro-alloys," reprint from
proceedings of Hie Congres International D'Electro Thermie,
Paris, May 18-23, 1953, p. 1-7.
139
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49. Bacalu, Ph., and Burzzone, G., "A Study of the Principal
Characteristics of a High Powered Carbide Furnace," from the
report presented at the V International Congress on Electro-Heat,
Wiesboden, Germany, 1963 (EPA Translation No. TR 1864), p. 1-19.
50. Ref. 34, p. 25.
51. Ref. 30.
52. Durkee, Kenneth R., EPA, International Trip Report, "Tests of
Ferroalloy Furnaces in Norway," April 2, 1973.
53. Ref. 25.
54. "Tanabe, Electric Reduction Furnaces Reference List," informational
brochure of Tanabe Kakoki Company, Ltd., Tokyo, Japan.
55. Ref. 25.
56. Seiffert, Randy D., EPA, International Trip Report, "Testing of
Japanese Ferroalloy Plants," April 5, 1974.
57. Letter with attachments from George A. Watson, The Ferroalloys
Association, to Stanley T. Cuffe, EPA, May 9, 1973.
58. Letter from George A. Watson, The Ferroalloys Association, to
Stanley T. Cuffe, EPA, April 25, 1973.
59. Ref. 34, p. 6-7.
60. Ref. 25.
140
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61. Rosserayr, Lars, "Manganese Alloy Production in a Large Submerged
Arc Furnace," Electric Furnace Proceedings, 1970, p. 121-123.
62. Hooper, Rex T., "The Production of Ferromanganese," Journal of
Metals, May 1968, p. 88-92.
63. Ref. 34, p. 6-7.
64. Ref. 25.
65. Ref. 34, p. 3.
66. Ref. 25.
67. Ref. 25.
68. Ref. 61.
69. Ref. 62.
70. Kanoh, Yasuhisa, "Solid State Reduction of Chrome Ores," Ferroalloys
Special Issue, published by Metal Bulletin Limited, London, England,
1971, p. 82-85.
71. Naruse, W., "Production by the Sintering Process," Ferroalloys Special
Issue, published by Metal Bulletin Limited, London, England, p. 86-90.
72. Tada, Y., et al., "On 50 Percent Eutectic Ferrosilicon and Refining
It In Closed Furnaces," Ferroalloys, 19 (1): 1-5, 1970 (EPA
Translation No. TR 362-73).
-------
73. Salto, Fred, "Self-taught Amateur Now Leading Ferroalloy Architect,"
ferroalloys section of American Metal Market, May 23, 1973.
74. Ref. 57.
75. Ref. 58.
76. Ref. 35, p. 8.
77. Ref. 49.
78. Ref. 3, p. VI-13 to VI-18.
79. Ref. 62.
80. Ref. 61.
81. Ref. 30.
82. Ref. 3, p. V-12 to V-13.
83. Ref. 52.
84. Dealy, James 0. and Kill in, Arthur M., International Trip Report,
"Observation of Covered Ferroalloy Furnaces Operating in Belgium
and Norway," 1972.
85. Ref. 25, p. 13 and 40.
86. Ref. 14, p. 1046.
142
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87. Naruse, W., op. cit., p. 86-90.
88. Hooper, R. T.t "Australian Industry," Ferroalloys Special Issue,
published by Metal Bulletin Limited, London, England, 1971,
p. 114-118.
89. Ref. 16, p. 28.
90. Ref. 70, p. 84-85.
91. Ref. 71, p. 86-92.
92. Ref. 25, p. 13, 23, 35, 40.
93. Ref. 71.
94. Ref. 88.
95. Ref. 25, p. 11, 12, 14, 20.
96. Ref. 14, p. 86-90.
97. Ref. 25.
98. Ref. 52.
99. Ref. 56.
100. Schanche, C. H., et al., "Todays Trend Towards Larger Electric
Smelting Furnaces - Some Features in Design and Operation,"
i,
presented at the 24th Electric Furnace Conference of the American
143
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Institute of Mining, Metallurgical, and Petroleum Engineers,
Philadelphia, Pennsylvania, December 7, 1966; reprint from the
Journal of Metals. 1967.
101. Letter from Mr. P. H. Hynne, El kern A.S., Porsgunn, Norway, to
Mr. Kenneth R. Durkee, EPA, November 2, 1972.
102. Ref. 25.
103. Ref. 61.
104. Ref. 58.
105. Ref. 25, p. 39.
106. Ref. 72.
107. Ref. 100.
108. Ref. 61.
109. Ref. 54.
110. Saito, F., "Japan Becoming Major Exporter of Ferroalloy Furnaces,
Equipment," American Metal Market. Vol. LXXVIII-35, February 22, 1971
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B. General References
1. "Trends 1n the Use of Ferroalloys by the Steel Industry of the
United States," a report of the National Advisory Board, Washington,
D. C., PB-204-142, July 1971.
2. "JIS Handbook, 1972, Ferrous Materials and Metallurgy," Japanese
Standards Association, Tokyo, Japan, 1972.
3. Environmental Protection Agency - The Ferroalloys Association
Cooperative Study,, Air Pollution Control Engineering and Cost
Study of the Ferroalloy Industry, draft document, January 21, 1974.
4. Sandberg, 0., and Braaten, 0., "Progress in Electric Furnace Smelting
of Calcium Carbide and Ferroalloys," presented at the Vth International
Congress on Electro-Heat, Weisboden, Germany, 1963.
5. Ferrari, Renzo, "Experiences 1n Developing an Effective Pollution
Control System for a Submerged Arc Ferroalloy Furnace Operation,"
Journal of Metals. April 1968, p. 95-104.
6. Prochazka, R.s "Dust Measurements in the Immediate Vicinity of
Electric Arc Furnaces for Ferro-Alloys," Staub-Reinhalt. Luft..
31(9): 8-16, September, 1971.
7. Silverman and Davidson, "Electric Furnace Ferrosilicon Fume
Collection," Journal of Metals. December 1955, p. 1327-1335.
145
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8. Takeshi, N., et al., "Concerning Dust Collection in Metal Silicon
Manufacturing," Ferroalloys, 21. (1): 46-57, 1972, EPA-APTIC
46141.
9. Andersen, H. C., "Some Significant Metallurgical Aspects of Smelting
Pig Iron in an Electric Furnace," reprint from The Canadian Mining and
Metallurgical Bulletin, July 1963.
10. Hamby, D. E., "Hollow Electrode System For Calcium Carbide Furnaces,"
Journal of Metals, 1_9. (1): 45-48, January 1967.
11. Sem, M. 0., "Closed Electric Reduction Furnaces Permit Utilization
of Furnace Gas," Journal of Metals, 6; 3-32, 1954.
12. Sem, M. 0., and Collins, F. C., "Fume Problems in Electric Smelting
and Contributions to Their Solution," Journal of the Air Pollution
Control Association. 5_ (3): 157-8, November 1955.
13. "Development Document for Effluent Limitations Guidelines and
Standards of Performance - Ferroalloys Industry," draft document
prepared under EPA Contract No. 68-01-1527, June 1973.
146
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/2—• 018a
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Background Information for Standards of Performance:
Electric Submerged Arc Furnaces Producing Ferroalloys
Volume 1, Proposed Standards
5. REPORT
Ve&ober
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8..PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
U. S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
This volume is the first in a series on the standard of performance for electric
submerged arc furnaces producing ferroalloys. This volume provides background
information and the rationale used in the development of the proposed standard
of performance. The economic and environmental impacts of the standard are
discussed.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Air Pollution, Calcium Silicon
Pollution Control, Ferromanganese Silicon
Standards of Performance, Charge Chrome
Ferroalloys, Silicomanganese Zirconium
Silicon Metal, High-Carbon Ferrochrome
50% Ferrosilicon, Ferrochrome Silicon, Sil\ery Iron
65-75% Ferrosilicon, Ferromanganese, Calciim Carbide
Air Pollution Control
8. DISTRIBUTION STATEMENT
Unlimtted
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PASE_S
•- 163
20. SECURITY CLASS (This page)
Unclassified
EPA Form 2220-1 (9-73)
147
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