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MEMORANDUM

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

FROM: Brad Nelson, EC/R

DATE: September 19, 2011

SUBJECT: Surrogate for Metal HAP Emissions for the Ferroalloys Source Category

The purpose of this memorandum is to establish whether the emissions of particulate matter (PM) can be 

used as a surrogate for non-Hg metallic hazardous air pollutants (HAP) emissions from electric arc 

furnaces (EAF) for the ferroalloys production industry. The metallic HAP emissions from this source 

include: arsenic, chromium, chromium VI, lead, manganese, mercury, and nickel. Since the majority of 

the HAP emissions from the EAF are particulate, establishing individual emission limits for each of the 

metallic HAP species emitted from this sources would be impractical. Measuring each individual 

metallic HAP would be costly and would pose unreasonable compliance and monitoring burden on the 

regulated community. In addition, EPA and state compliance oversight and enforcement efforts would 

also be unreasonably costly without concurrent benefits. Of greater significance, as explained below, the 

use of PM as a surrogate for HAP metals meets the test established in National Lime II. Therefore, it is 

proposed to control non-Hg metallic HAP using limits on the flue gas concentration of PM as a non-Hg 

metallic HAP surrogate.

1.0 Background

The ferroalloys production source category is currently being reviewed as part of the “risk and 

technology” (RTR) review for maximum achievable control technology (MACT standards. Under the 

"technology review" provision of CAA section 112, EPA is required to review MACT standards and to 

revise them "as necessary (taking into account developments in practices, processes and control 

technologies)" no less frequently than every 8 years. Under the "residual risk" provision of the CAA 

section 112, EPA must evaluate the MACT standards within 8 years after promulgation and promulgate 

standards if required to provide an ample margin of safety to protect public health or prevent an adverse 
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environmental effect. EPA has combined the two review activities into the RTR reviews for the 

Ferroalloys Production source category. 

The ferroalloy process involves the reduction smelting of metallic ores (ferrous oxides, silicon oxides, 

manganese oxides) and a carbon-source reducing agent, usually in the form of coke, charcoal, high- and 

low-volatility coal, or wood chips. These materials are fed into an electric arc furnace (EAF) at high 

temperatures and the carbon source reacts with the metal oxides to form carbon monoxide (CO) and the 

ferromanganese (FeMn) or silicomanganese (SiMn) product. This process also releases PM and metallic 

HAP from the furnace that is either captured by the furnace hood and routed to a particulate control 

device or is emitted as fugitive emissions. The particulate control device (e.g., fabric filter baghouse, wet 

venturi scrubber) achieves both reductions in PM and metallic HAP from the exhaust stream. For the 

fabric filter baghouse, it was estimated that emissions of PM and non-Hg metallic HAP are reduced by 99 

percent. The venturi scrubber is estimated to achieve reductions of 95 percent for both PM and non-Hg 

metallic HAP. The two particulate control devices are estimated to reduce mercury emissions by 

approximately 15 percent. This is because mercury is believed to be 80 percent elemental mercury, which 

is not captured by the particulate control device and 20 percent mercuric chloride, which can be captured 

by the particulate control device.

2.0 Metallic HAP Surrogate

The current NESHAP for ferroalloys production (40 CFR Part 63, subpart XXX) uses PM as a surrogate 

for metallic HAP by setting a PM standard for both new and existing EAFs. The recent DC Circuit 

Court opinion in the National Lime II (233 F.3d 625) has revised the methodologies used to 

determine if criteria pollutants can be used as a surrogate for HAP. The DC Circuit Court stated that 

EPA „„may use a surrogate to regulate hazardous pollutants if it is „reasonable‟ to do so‟‟ and 

laid out criteria establishing a three-part analysis for determining whether the use of PM as a 

surrogate for non-Hg metal HAP was reasonable. The DC Circuit Court found that PM is a

reasonable surrogate for HAP if: (1) „„HAP metals are invariably present in * * * PM;‟‟ (2) „„PM 

control technology indiscriminately captures HAP metals along with other particulates;‟‟ and (3)

„„PM control is the only means by which facilities „achieve‟ reductions in HAP metal 

emissions.‟‟ 233 F.3d at 639. If these criteria are satisfied and the PM emission standards reflect 

what the best sources achieve—complying with CAA section 7412(d)(3)—„„EPA is under no

obligation to achieve a particular numerical reduction in HAP metal emissions.‟‟ 
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Based on this opinion, the EPA justifies its decision to regulate PM as "a surrogate for 

nonvolatile HAP metals" by noting first that PM generated by EAFs invariably contains HAP 

metals. This was confirmed from the baghouse dust data that was collected for the Information 

Collection Request (ICR) for ferroalloys production. Based on these results, it can be stated that 

preventing the emission of a unit of PM prevents the emission of some quantum of HAP metals. 

Using PM as a surrogate thus "achieves exactly the same level of HAP metal emissions 

limitation" as would be reached were the metals to be regulated directly. The EPA also believes 

that the MACT floor equipment and level of control for non-Hg HAP metals is identical to that 

for PM. In addition, the use of a surrogate eliminates the cost of performance testing to comply 

with numerous standards for individual metals, and also reduces the costs of EPA and state 

compliance oversight and enforcement efforts. Therefore, it was determined that PM would be used 

as a surrogate for non-Hg metallic HAP (arsenic, chromium, chromium VI, lead, manganese, and 

nickel) and a separate standard would be proposed for mercury emissions from EAFs.