10/27/2011 1 

MEMORANDUM

TO: Conrad Chin, U.S. Environmental Protection Agency, OAQPS

FROM: Beth Friedman,Jeff Harris, and Brad Nelson, EC/R

DATE: October 27, 2011

SUBJECT: Draft Technology Review for the Ferroalloys Production Source Category

This memorandum summarizes the results of an analysis to identify developments in practices, 

processes, and control technologies for emissions sources of hazardous air pollutants (HAP) from the 

ferroalloys production source category. This analysis is part of EPA’s review efforts in accordance with 

section 112(d)(6) of the Clean Air Act (CAA). This memorandum is organized as follows:

1.0 Background

1.1 Requirements of Section 112(d)(6) of the CAA

1.2 Description of the Ferroalloys Production Source Category and 

 Requirements of the Current NESHAP

2.0 Developments in Practices, Processes and Control Technologies

2.1 Stack Emissions

2.2 Fugitive Emissions

3.0 Recommended Revisions Based on Developments in Practices, 

 Processes and Control Technologies

3.1 Stack Emissions

3.2 Fugitive Emissions

4.0 Conclusions

1.0 BACKGROUND

1.1 Requirements of Section 112(d)(6) of the CAA

Section 112 of the CAA requires EPA to establish technology-based standards for sources of HAP. 

These technology-based standards are often referred to as maximum achievable control technology, or 
10/27/2011 2 

MACT, standards. Section 112 also contains provisions requiring EPA to periodically revisit these 

standards. Specifically, paragraph 112(d)(6) states:

(6) REVIEW AND REVISION. – The Administrator shall review, and revise as necessary 

(taking into account developments in practices, processes, and control technologies), 

emissions standards promulgated under this section no less often than every 8 years.

1.2 Description of the Ferroalloys Production Source Category and Requirements of the 

Current NESHAP

The current National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Ferroalloys 

Production: Ferromanganese and Silicomanganese was promulgated on May 20, 1999 (64 FR 27450) 

and codified at 40 CFR part 63, subpart XXX. The 1999 NESHAP (40 CFR 63.1650(a)) applies to all 

new and existing ferroalloys production facilities that manufacture ferromanganese or silicomanganese 

and are major sources or are co-located at major sources of HAP emissions. The rule’s product-specific 

applicability reflected the only known major source at the time of promulgation. 

Today, there are two ferroalloys production facilities subject to the MACT rule. No new manganese 

ferroalloys production facilities have been built in over 20 years, and we anticipate no new ferroalloys 

production facilities in the foreseeable future, although one facility is currently exploring expanding 

operations. 

Ferroalloys are alloys of iron in which one or more chemical elements (such as chromium, manganese, 

and silicon) are added into molten metal. Ferroalloys are consumed primarily in iron and steel making 

and are used to produce steel and cast iron products with enhanced or special properties. 

HAP generating processes at Ferroalloys facilities include electrometallurgical (furnace) operations 

(primary and tapping), other furnace room operations (ladle treatment and casting), raw material 

handling and product handling. HAP are emitted from ferroalloys production as process emissions, 

process fugitive emissions, and outdoor fugitive dust emissions. 

Process emissions are the exhaust gases from the control devices, primarily the furnace control device, 

metal oxygen refining control device and crushing operations control device. The HAP in process 
10/27/2011 3 

emissions are primarily composed of metals (mostly manganese, arsenic, nickel, lead, mercury and 

chromium) and also may include organic compounds that result from incomplete combustion of coal or 

coke that is charged to the furnaces as a reducing agent. There are also process metal HAP emissions 

from the product crushing control devices. Process fugitive emissions occur at various points during the 

smelting process (such as during charging and tapping of furnaces and casting) and are assumed to be 

similar in composition to the process emissions. Outdoor fugitive dust emissions result from the 

entrainment of HAP in ambient air due to material handling, vehicle traffic, wind erosion from storage 

piles, and other various activities. Outdoor fugitive dust emissions are composed of metal HAP only.

The MACT rule applies to process emissions and process fugitive emissions from the submerged arc 

furnaces, the metal oxygen refining process, and the product crushing equipment and outdoor fugitive 

dust emissions sources such as roadways, yard areas, and outdoor material storage and transfer 

operations. For process sources, the NESHAP specifies numerical emissions limits for particulate matter 

(as a surrogate for non-mercury metal HAP) from the electric (submerged) arc furnaces (including 

primary and tapping emissions), depending on furnace type, size, and product being made. Particulate 

matter emission limits (again as a surrogate for non-mercury metal HAP) are also in place for the metal 

oxygen refining process and product crushing and screening equipment. Table 1 is a summary of the 

applicable limits.

The 1999 NESHAP established a building opacity limit of 20 percent that is measured during the 

required furnace control device performance test. The rule provides an excursion limit of 60 percent 

opacity for one 6-minute period during the performance test. The opacity observation is focused only on 

emissions exiting the shop due solely to operations of any affected submerged arc furnace. In addition, 

blowing taps, poling and oxygen lancing of the tap hole; burndowns associated with electrode 

measurements; and maintenance activities associated with submerged arc furnaces and casting 

operations are exempt from the opacity standards.. For outdoor fugitive dust sources, the 1999 NESHAP 

requires that plants operate according to an outdoor fugitive dust control plan that describes in detail the 

measures that will be put in place to control outdoor fugitive dust emissions from the individual outdoor 

fugitive dust sources at the facility.
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Table 1. Emission Limits in Subpart XXX

New or Reconstructed or 

Existing Source

Affected Source Applicable PM Emission 

Standards

New or reconstructed Submerged arc furnace 0.23 kilograms per hour per 

megawatt (kg/hr/MW) (0.51 

pounds per hour per megawatt 

(lb/hr/MW) or 35 milligrams per 

dry standard cubic meter 

(mg/dscm) (0.015 grains per dry 

standard cubic foot (gr/dscf)

Existing Open submerged arc furnace producing 

ferromanganese and operating at a furnace 

power input of 22 megawatts (MW) or less

9.8 kg/hr (21.7 lb/hr) 

Existing Open submerged arc furnace producing 

ferromanganese and operating at a furnace 

power input greater than 22 MW

13.5 kg/hr (29.8 lb/hr) 

Existing Open submerged arc furnace producing 

silicomanganese and operating at a furnace 

power input greater than 25 MW

16.3 kg/hr (35.9 lb/hr) 

Existing Open submerged arc furnace producing 

silicomanganese and operating at a furnace 

power input of 25 MW or less

12.3 kg/hr (27.2 lb/hr) 

Existing Semi-sealed submerged arc furnace (primary, 

tapping, and vent stacks) producing 

ferromanganese

11.2 kg/hr (24.7 lb/hr) 

New, reconstructed, or 

existing

Metal oxygen refining process 69 mg/dscm (0.03 gr/dscf)

New or reconstructed Individual equipment associated with the 

product crushing and screening operation

50 mg/dscm (0.022 gr/dscf)

Existing Individual equipment associated with the 

product crushing and screening operation

69 mg/dscm (0.03 gr/dscf)
10/27/2011 5 

2.0 DEVELOPMENTS IN PRACTICES, PROCESSES AND CONTROL TECHNOLOGIES

Our technology review focused on the identification and evaluation of developments in practices, 

processes, and control technologies that have occurred since the 1999 NESHAP was promulgated. In 

cases where the technology review identified such developments, we conducted an analysis of the 

technical feasibility of applying these developments, along with the estimated impacts (costs, emissions 

reductions, risk reductions, etc.) of applying these developments.1 We then made decisions on whether it 

is necessary to propose amendments to the regulation to require any of the identified developments.

Based on our analyses of the data and information collected by the ICR and our general understanding 

of the industry and other available information on potential controls for this industry, we identified 

several potential developments in practices, processes, and control technologies. For the purpose of this 

exercise, we considered any of the following to be a “development”:

• Any add-on control technology or other equipment that was not identified and considered during 

development of the 1999 NESHAP.

• Any improvements in add-on control technology or other equipment (that were identified and 

considered during development of the 1999 NESHAP) that could result in significant additional 

emissions reduction.

• Any work practice or operational procedure that was not identified or considered during 

development of the 1999 NESHAP.

• Any process change or pollution prevention alternative that could be broadly applied to the 

industry and that was not identified or considered during development of the 1999 NESHAP.

In addition to reviewing the practices, processes, or control technologies that were not considered at the 

time we developed the 1999 NESHAP, we reviewed a variety of data sources in our evaluation of 

whether there were additional practices, processes, or controls to consider for the Ferroalloys Production 

industry. Among the data sources we reviewed were the NESHAP for various industries that were 

promulgated after the 1999 NESHAP. We reviewed the regulatory requirements and/or technical 

 

1 Details of costs and emissions reductions are available in Cost Impacts for the Ferroalloys Source Category, available in the 

docket for the Ferroalloys Production source category
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analyses associated with these regulatory actions to identify any practices, processes, and control 

technologies considered in these efforts that could possibly be applied to emissions sources in the 

Ferroalloys Production source category, as well as the costs, non-air impacts, and energy implications 

associated with the use of these technologies. 

Additionally, we requested information from facilities regarding developments in practices, processes, 

or control technology. Finally, we reviewed other information sources, such as state or local permitting 

agency databases and industry-supported databases. The results of these analyses are presented in the 

following sections.

Although not a development in technology, we also considered the feasibility of reducing emissions 

from pollutants that were not identified and regulated under the 1999 NESHAP, which focused solely on 

metal HAP. These pollutants are mercury, polycyclic aromatic hydrocarbons (PAH), hydrochloric acid 

(HCl), and formaldehyde.

2.1 Stack Emissions

The current NESHAP specifies emissions limits for metal HAP (using PM as a surrogate) from stacks. 

This section of the technology review will focus on developments in practices, processes, and control 

technologies applicable to emissions of metal HAP and organic compounds from stacks.

2.1.1. Metal HAP Emissions from Stacks

Based on a review of the ICR responses, the most common control technology employed by the industry 

to control emissions of PM as well as non-mercury metal HAP from furnace, metal oxygen refining, and

crushing/sizing stacks is fabric filtration (or baghouses). Several types of baghouses are currently used 

by the industry, with cleaning mechanisms including shaker, pulse jet, and reverse air, and including 

positive pressure and large custom negative pressure baghouses. One facility also uses a venturi

scrubber on one of their furnace stacks. The results from the ICR test program showed that all of the 

sources of stack emissions are emitting at significantly lower levels than their MACT permitted levels. 
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2.1.2. HCl and Formaldehyde Emissions from Furnace Stacks

Although HCl and formaldehyde emissions limits are not specified in the current NESHAP, we 

investigated technologies available for prevention and/or control of HCl and formaldehyde emissions 

from furnace stacks. .No facilities in the source category use add-on control devices or work practices to 

limit emissions of these pollutants beyond what is normally achieved as co-control of the emissions with 

particulate matter control device. There are available add-on control devices, such as dry sorbent 

injection (DSI) (lime injection) that is believed to be a viable control technology to reduce HCl 

emissions from furnaces. The DSI control system works by injecting a sodium-based powder such as, 

Trona (Na2CO3) or sodium bicarbonate (NaHCO3) into the flue gas duct upstream of a baghouse used 

for particulate control. For the acid gases, the NaHCO3 or Na2CO3 reacts with HCl to form sodium 

chloride (NaCl), carbon dioxide (CO2) and water (H2O). The NaCl is a solid which can be removed 

from the exhaust stream using a particulate control device. This technology is currently used to reduce 

acid gas emissions from coal-fired boilers and achieves up 90 percent reduction of HCl .

The capital cost for DSI is estimated to be quite high, both because of expensive sorbent material and 

because the use of sodium-based DSI also affects the marketability and beneficial use of baghouse fly 

ash, which is currently used in the concrete, wallboard and asphalt products industries as well as road 

and bridge construction. The collected fly ash from DSI technologies would need to be disposed of in a 

landfill, and would prevent the current practice of reusing or selling baghouse dust and the resulting 

waste reduction benefits.

Activated carbon (also called activated carbon injection) is a possible control technology for 

formaldehyde emissions. However, the same disadvantages apply in terms of baghouse dust 

contamination as for HCl control. Other control technologies used to reduce formaldehyde emissions 

include thermal incineration and catalytic oxidation. However, these control technologies are not 

technologically or economically feasible for EAF emissions because of the high volume of exhaust gas 

that would need to be treated.

2.1.3. Mercury Emissions from Furnace Stacks

Although mercury emissions limits are not specified in the current NESHAP, we investigated 

technologies available for prevention and/or control of mercury emissions from furnace stacks. No 
10/27/2011 8 

facilities in the source category use add-on control devices or use work practices to limit emissions of 

mercury emissions beyond what is normally achieved as co-control of the emissions with the particulate 

matter control device. We estimated that the bulk of mercury emissions are emitted from the furnace 

control devices as measured during the ICR test program. Because of the magnitude of mercury 

emissions (estimated to be 540 pounds per year (lb/yr) at one plant and 140 lb/yr at the other plant), we 

evaluated potential add-on control in the form of carbon beds or activated carbon injection. Based on 

discussions with a vendor2

, we determined that using a fixed bed carbon system for treating the high 

flow rate from furnace control devices is neither feasible nor practical.

The use of activated carbon injection is being considered in other recent NESHAP such as the Utility 

MACT NESHAP and the Portland Cement NESHAP, and mercury reductions of up to 90 percent should 

be achievable at ferroalloys production facilities. Based on our experience with mercury controls for 

other combustion sources such as boilers, we conclude that activated carbon injection is a viable control 

technology in the Ferroalloys Production source category. However, we recognize the potential concern 

that use of these controls upstream of the particulate matter control device may pose issues with fabric 

filter dust contamination or sludge contamination and may result in some waste products being classified 

as Resource Conservation and Recovery Act (RCRA) waste. In addition, some companies re-use or sell 

their baghouse dust (primarily for use in cement kilns). There is concern that even if the material meets 

quality standards, that re-introduction of the dust into a furnace or kiln would cause the mercury to 

become unbound from the carbon and be emitted into the atmosphere. 

Because of these concerns, we reviewed control options that included putting the mercury controls 

downstream of the existing furnace baghouse to avoid the potential issues associated with upstream 

controls. Under this scenario, the activated carbon injection system would be followed by a “polishing” 

baghouse to capture the activated carbon for disposal. In the case of an existing furnace scrubber, we 

assumed the source could put the activated carbon injection system upstream of the scrubber, the carbon 

would be captured by the scrubber and the resulting sludge treated according to the existing treatment 

process at the plant. Based on discussion with a vendor3 and other control technology experts at EPA, 

we do not believe that the resulting carbon waste in either scenario would trigger the RCRA compliance 

 

2

Calgon Carbon Contact Report, August 17, 2011. 3 Albemarle Contact Report, August 22, 2011.
10/27/2011 9 

concerns raised by the companies. This is because once the mercury absorbs to the activated carbon, it 

will stay there until heated above 400 degrees Fahrenheit. The captured activated carbon should pass the 

Toxicity Characteristic Leaching Procedure test, which is an EPA test method used to characterize waste 

as either hazardous or non-hazardous for the purpose of disposal.4 Therefore, the captured activated 

carbon would unlikely be considered hazardous waste and can be disposed of in a landfill.

2.1.4. Polycyclic Aromatic Hydrocarbons from Furnace Stacks

Although PAH emissions limits are not specified in the current NESHAP, we investigated technologies 

available for prevention and/or control of PAH emissions from furnace stacks. Like mercury, no existing 

facilities in the source category control PAH or use work practices to limit emissions of PAH emissions 

beyond what is normally achieved by modest co-control of the emissions with the particulate matter 

control device. Also like mercury, these pollutants may be controlled with activated carbon injection 

technology. Because of this, emission reductions could be achieved via co-control at no additional costs. 

2.2 Fugitive Emissions

As outlined in section 1.2 of this memorandum, the pollutants emitted from fugitive emissions sources 

in this source category occur at various points during the smelting process (such as during charging and 

tapping of furnaces and casting) and are assumed to be similar in composition to the process emissions. 

Outdoor fugitive dust emissions result from the entrainment of HAP in ambient air due to material 

handling, vehicle traffic, wind erosion from storage piles, and other various activities. Outdoor fugitive 

dust emissions are composed of metal HAP only.

2.2.1. Metal HAP emissions from process fugitives

We evaluated several options to improve and increase the capture and control of process fugitive 

sources. The two main options involve either local ventilation or building ventilation. Local ventilation 

is common in this industry, but performance varies due to design of the capture system, maintenance 

practices and control device capacity. Industry representatives have expressed concern that extensive 

retrofitting of local ventilation is complicated at existing facilities because of the need for material 

movement using large overhead cranes and ladles. 

 

4 Albemarle Contact Report, August 22, 2011.
10/27/2011 10 

We evaluated several options to improve capture of fugitive emissions via improvements in hood design 

and the addition of new capture systems (with emissions ducted to new or existing control devices). We 

also identified a furnace building ventilation system at a ferrosilicon producer, using a similar 

production process. This “system” is basically an enclosure of the furnace building with evacuation of 

emission to a control device. We evaluated an option to enclose the furnace building(s) and evacuate the 

emissions to a control device(s) similar to the system used at the ferrosilicon producing facility 

described above. 

2.2.2. Outdoor Fugitive Dust Emissions

The existing rule has a requirement for an outdoor fugitive dust control plan. We are unable to quantify 

HAP emissions from outdoor fugitive dust sources and did not identify any additional procedures or 

controls that could be expected to have a significant impact on these emissions. 

3.0 RECOMMENDED REVISIONS BASED ON DEVELOPMENTS IN PRACTICES, 

PROCESSES, AND CONTROL TECHNOLOGIES

Based on the analyses presented above, we are recommending the following revisions to the current 

NESHAP with regards to stack and fugitive emissions from the Ferroalloys Production source category.

3.1 Stack Emissions

3.1.1. Metal HAP Emissions from Stacks

As described in section 2.1.1 of this memorandum, the concentrations of PM emissions in stacks 

reported by this industry in the ICR are far below the level specified in the current NESHAP, indicating 

improvements in the control of PM emissions since promulgation of the current NESHAP. Our analysis 

indicates that this is primarily a result of improved performance of baghouses (and a scrubber at one 

facility.) Therefore, we recommend revising the current NESHAP to reflect the level of performance 

currently being achieved by facilities that implement well-performing baghouses to control emissions of 

PM and metal HAP from stacks.

We calculated the proposed emission limits based on a MACT floor UPL analysis, resulting in a 

proposed existing source furnace stack PM emissions limit of 24 mg/dscm and proposed new source 

furnace stack emissions limit of 9.3 mg/dscm. We also calculated a proposed stack emission limit of 13 
10/27/2011 11 

mg/dscm for crushing and screening equipment that would apply to both new and existing sources. 

The metal oxygen refining operation is a unique process, and so we only have a single ICR test data 

point. Therefore, we calculated a proposed emissions limit for this source using the 99 percent UPL 

from the test data, resulting in a proposed limit of 3.9 mg/dscm that would apply to new and existing 

metal oxygen refining operation sources. 

Based on our analyses, we expect that no additional controls would be required for the facilities to 

comply with these proposed PM limits. 

3.1.2. HCl and Formaldehyde Emissions from Furnace Stacks

As described in section 2.1.2, there is an available add-on control device believed to be a possible

control technology to reduce HCl emissions from furnaces (DSI). However, because of high capital cost 

and the likelihood that implementation of sorbent injection would prevent the current practice of reusing 

or selling baghouse dust and the resulting waste reduction benefits, we determined that it is not a 

feasible option for the Ferroalloys Production source category.

The capital cost for DSI is estimated to be $10 per kilowatt for coal-fired boilers5. Converting this cost 

to an EAF produces an estimated capital cost of $625,000 for a 25 megawatt EAF6. However, the major 

cost of DSI systems is the sorbent7

. The DSI control technology has a relatively high operating cost, 

which ranges from $3.4 to $5 per kilowatt-year ($/kW-yr)8

, which averages to a cost of $263,000 a year 

for a 25 megawatt EAF. In addition, there are currently only a few suppliers of Trona, which is primarily 

mined in the western United States. Therefore, transporting the supply of Trona to facilities in the 

eastern United States could increase the delivered cost of Trona from $150 per ton to approximately 

$200 per ton. 

 

5 URS, Assessment of Technology Options Available to Achieve Reductions of Hazardous Air Pollutants, April 5, 2011.

6

Assumes 40 percent efficiency for the coal-fired boiler. 7 Sargent & Lundy, IPM Model – Revisions to Cost and Performance for APC Technologies, Dry Sorbent Injection Cost 

Development Methodology Final, August 2010.

8 URS, Assessment of Technology Options Available to Achieve Reductions of Hazardous Air Pollutants, April 5, 2011.
10/27/2011 12 

The use of sodium-based DSI also affects the marketability and beneficial use of baghouse fly ash, 

which is currently used in the concrete, wallboard and asphalt products industries as well as road and 

bridge construction. This is because sodium-based dry sorbents are soluble and contribute greatly to the 

available alkali content. As a result, fly ash produced with emissions controls systems employing 

sodium-based DSI technologies exceed the available alkali criteria established by the American 

Association of State Highway and Transportation Officials for concrete. Therefore, the collected fly ash 

from DSI technologies would need to be disposed of in a landfill, and would prevent the current practice 

of reusing or selling baghouse dust and the resulting waste reduction benefits. 

Activated carbon (also called activated carbon injection) is a possible control technology for 

formaldehyde emissions. However, the same disadvantages apply in terms of baghouse dust 

contamination as for HCl control. We recognize the potential for some co-control of formaldehyde 

emissions that would be achieved by using activated carbon injection to control mercury emissions, but 

we were unable to quantify those reductions. Other control technologies used to reduce formaldehyde 

emissions include thermal incineration and catalytic oxidation. However, these control technologies are 

not technologically or economically feasible for EAF emissions because of the high volume of exhaust 

gas that would need to be treated. 

3.1.3. Mercury Emissions from Furnace Stacks

As described in section 2.1.3 above, activated carbon injection is an available add-on control device 

believed to be a viable control technology to reduce mercury emissions from furnaces. 

Using the concentrations of mercury in stacks reported by this industry in the ICR, we calculated a 

MACT floor (or 99 percent UPL) for exhaust mercury concentrations from existing furnaces to be 80 

μg/dscm at 2 percent CO2. This MACT floor limit is higher than the actual emissions measured during 

the ICR performance tests at each plant. Therefore, we anticipate that both of the existing sources would 

be able to meet this limit without installing additional controls. Because of our limited data set, we 

considered setting a MACT limit for existing sources based on the performance of the best performing 

source (i.e., based upon the test data used to calculate the MACT floor for new sources) such that the 

MACT limit for existing sources would be the same as the UPL MACT limit for new sources (i.e., 16 
10/27/2011 13 

μg/dscm). We believe this level could be achieved by an activated carbon injection system, which is a 

proven technology for mercury control.

3.1.4. Polycyclic Aromatic Hydrocarbons from Furnace Stacks

As described in section 2.1.4 above, as with mercury, PAHs may be controlled with activated carbon 

injection technology. Based on available stack test data for PAH and applying the 99 percent UPL, we 

calculated that the MACT floor limit for PAHs would be 887 μg/dscm. We also evaluated control 

performance that could be achieved via co-control of mercury emissions with activated carbon injection 

as a beyond-the-floor option. Based on information from carbon vendors, an activated carbon system 

that is designed to achieve a 90 percent reduction in mercury emissions (which we expect would be 

applied to meet the proposed mercury standard discussed above) should also achieve a high degree of 

reduction in PAH with no additional costs. Assuming a 90 percent reduction from the calculated 99 

percent UPL of 887 μg/dscm, the resulting limit would be 89 μg/dscm. Thus, a proposed limit for PAHs 

of 89 μg/dscm could be achieved with the same controls needed for mercury with no additional costs.

3.2 Fugitive Emissions

3.2.1. Metal HAP emissions from process fugitives

As described in section 3.2.1 above, we evaluated an option to enclose the furnace building(s) and 

evacuate the emissions to a control device(s). Based on that evaluation, we believe that it is feasible to 

install enclosures and have the fugitive emissions at the ridge vents of the shop building collected under 

negative pressure and ducted to a control device, with a PM emissions limit at the control device stack 

outlet set at the same level as for the furnace stacks. This would allow sources the option to duct some or 

all process fugitive emissions to an existing furnace control device if it has excess capacity. 

However, recognizing that there may be other control measures that could achieve equivalent emissions 

reductions that we have not yet identified, and to provide some flexibility for facilities to determine the 

best approach to reduce their emissions, we are also proposing an equivalent alternative compliance 

approach. Facilities can design an equivalent alternative approach (e.g., local capture, controls, work 

practices) to achieve equivalent emissions reductions. Compliance would be demonstrated using 

fenceline monitoring to show that the ambient concentration of manganese at the facility boundary is 

less than 0.1 μg/m3 on a 60-day rolling average.
10/27/2011 14 

We propose to set the fenceline concentration level to reflect the equivalent level of emissions control

that we estimate will be achieved with the requirement to enclose the furnace building(s) and evacuate 

the emissions to a control device(s). According to the risk assessment, the maximum modeled chronic 

noncancer inhalation target-organ-specific hazard index (TOSHI) value is 2 after full enclosure and 

evacuation of emissions based on the post-control modeling analysis. This means that the modeled 

concentration at the maximum impact location after these controls are in place would be 0.1 μg/m3

, 

which is 2 times higher than the current value of the reference concentration (RfC) for manganese. 

Therefore, achieving and maintaining a manganese level of 0.1 μg/m3 at the facility boundary is 

proposed as the equivalent alternative standard to minimize fugitive emissions of HAP metals..

We are also proposing a change in the building opacity limit as an indication of performance of the 

capture system operation. This change is described in a separate memorandum, Draft Selection of 

Opacity Limits for the Ferroalloys Production Source Category, available in the docket for the 

Ferroalloys Production source category.

3.2.2. Outdoor Fugitive Dust Emissions

As described in section 3.2.2 above, we are unable to quantify HAP emissions from outdoor fugitive 

dust sources and did not identify any additional procedures or controls that could be expected to have a 

significant impact on these emissions. Existing requirements that that plants operate according to an 

outdoor fugitive dust control plan are still in effect.

4.0 CONCLUSIONS

This review identified several developments in practices, processes, or control technologies that have 

been implemented in this source category since promulgation of the current NESHAP. Our analysis 

indicates that both facilities have significantly reduced stack emissions of metal HAP compared to 

allowable levels, primarily through improved performance of baghouses. 

Based on our review, we conclude that it is feasible and cost-effective for facilities to achieve an

existing source furnace stack PM emissions limit of 24 mg/dscm and new source furnace stack 

emissions limit of 9.3 mg/dscm. We also conclude that a stack PM emission limit of 13 mg/dscm for 
10/27/2011 15 

new and existing crushing and screening equipment is reasonable. Our analyses indicate that a stack 

emission limit for PM of 3.9 mg/dscm is achievable for new and existing metal oxygen refining 

operations.

We conclude that a mercury emission limit from EAF of 16 μg/dscm is feasible for new and existing 

sources, requiring some sources to implement activated carbon injection. We also conclude that a PAH 

emission limit from EAF of 89 μg/dscm is feasible for new and existing sources, taking into account cocontrol from controls which may be implemented for mercury. We conclude that it is feasible for all 

facilities to enclose the furnace building(s) and evacuate the emissions to a control device(s) to limit 

fugitive emissions, with PM emission limits equal to those for furnaces . As described above, we also 

recommend that the proposed rule should include an equivalent alternative fenceline concentration limit.

We believe that these controls and measures are cost-effective measures that reflect achievable 

performance for this industry. Details of the costs and emissions reductions associated with these 

measures are available in Cost Impacts for the Ferroalloys Source Category, available in the docket for 

the Ferroalloys Production source category.