1

MEMORANDUM

DATE: August 29, 2014

SUBJECT: Revised MACT Floor Analysis for the Ferroalloys Production Source Category

FROM: Bradley Nelson, EC/R, Inc.

TO: Phil Mulrine, EPA OAQPS/SPPD/MICG

1.0 PURPOSE

The purpose of this memorandum is to document the methodologies and results of the revised 

maximum achievable control technology (MACT) floor determination for hydrochloric acid (HCl), 

and total polycyclic aromatic hydrocarbons (PAH) for the ferroalloys production source category

and Beyond the Floor (BTF) analyses. The MACT floor determinations for each of these pollutants 

were re-evaluated using test data received after the 2011 proposal of the amendments to the national 

emission standards for hazardous air pollutants (NESHAP) for the ferroalloys production source 

category published in the Federal Register on November 23, 2011 (76 FR 72508), along with the 

data we had received in 2010. 

The emission limits that were determined for the 2011 proposed amendments to the Ferroalloys 

Production NEHAP were based on limited data from the facilities. Since the 2011 proposal, EPA 

has recieved compliance test reports and other test data from the facilities, in addition to test reports 

received in response to an ICR sent out in December of 2012. These test reports provided 

additional HAP data for previously tested emission sources and HAP data from emission sources 

that were not tested in the 2010 ICR. The new dataset includes HAP data from each of the 

operational furnaces at the two facilities, and also includes HAP data during the production of 

different products (FeMn or SiMn at Eramet, Felman only produces SiMn). 

Based on the inclusion of the new test data, EPA decided to re-evaluate the emission limits for the 

proposed amendments to the NESHAP. This memorandum describes the re-evaluation and 

revisions to the PAH and HCl emissions limits. The emission limits for particulate matter (PM) in 

the proposed amendments to the NESHAP are addressed in the technology review memorandum1, 

and the proposed emission limits for mercury are addressed in the mercury control options 

memorandum.2 The new test data did not warrant any changes to the proposed emission limit for 

formaldhyde. 

 

1 Memorandum from Bradley Nelson, EC/R to Phil Mulrine, EPA OAQPS/SPPD/MICG, Revised Technology Review 

for the Ferroalloys Production Source Category, August 2, 2014.

2 Memorandum from Bradley Nelson, EC/R to Phil Mulrine, EPA OAQPS/SPPD/MICG, Mercury Control Options and 

Impacts for the Ferroalloys Production Industry, August 2014.
2

2.0 BACKGROUND

Under the "technology review" provision of CAA section 112, EPA is required to review maximum 

achievable control technology (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, within 8 years after 

promulgation of the MACT standards, EPA must evaluate the remaining risks due to emissions of 

air toxics from the source category and promulgate amendments to the standards if required to 

provide an ample margin of safety to protect public health or prevent an adverse environmental 

effect. EPA has combined the two review activities into the RTR reviews for the Ferroalloys 

Production source category. The EPA has also reviewed other aspects of the MACT standards to 

determine if other revisions to the rule are warranted.

The MACT standards, which are also known as NESHAP, for Ferroalloys Production apply to new 

and existing ferroalloy production facilities that manufacture ferromanganese and/or 

silicomanganese and are major sources of HAP emissions or are co-located at major sources of 

HAP emissions. The NESHAP established emissions standards for the following HAP emission 

sources at a ferroalloy production facility:

 Submerged arc furnaces

 Metal oxygen refining (MOR) process

 Crushing and screening operations

 Fugitive dust sources.

The current rule contains emission standards that limit PM emissions (as a surrogate for metal 

HAP) from existing and new or reconstructed emission sources. The limits for the submerged arc 

furnaces depend on the product produced and furnace design and size. The rule also includes limits 

for the air pollution control devices associated with the MOR process and crushing and screening 

operations. The current rule includes emission standards for process fugitive emissions based on 

limiting the amount of visible emissions (opacity) that can be observed from the furnace buildings. 

3.0 FERROALLOY FACILITY SUMMARY

The following section describes the HAP emission sources for the Eramet Marietta (Eramet) and 

Felman Production (Felman) ferroalloy production facilities, which are the two existing facilities in 

the source category. 
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Eramet Marietta Inc.

The Eramet facility is located in Marietta, Ohio, and it produces ferromanganese (FeMn) and 

silicomanganese (SiMn) using two furnaces identified as Furnace 1 and Furnace 12. Furnace 1 is a 

submerged arc furnace rated at 30 megawatts (MW) and is equipped with a negative pressure fabric 

filter to control particulate emissions and metal HAP. The fabric filter controls emissions from the 

furnace and was installed in 2011 to replace a wet scrubber system. A separate fabric filter system 

identified as Furnace 1 Tapping Baghouse is used to control captured fugitive emissions from the 

tapping process from this furnace. Furnace 12 is a submerged arc furnace rated at 22 MW and is 

equipped with two wet scrubbers to control primary (smelting) and secondary (tapping) emissions. 

The scrubbers operate simultaneously and exhaust through a single stack. Other HAP emission 

sources include the MOR process controlled by a positive-pressure baghouse which also controls 

fugitive emissions captured from casting of the product from MOR and a crushing and sizing 

system (C2P) that is controlled by three negative pressure baghouses. There are also fugitive 

emissions that are emitted from each of these emission sources, in addition to the fugitive emissions 

from the casting operations for Furnace 1, Furnace 12, and the MOR process.

Felman Production Inc.

The Felman facility is located in New Haven, West Virginia and produces SiMn using three 

furnaces identified as Furnace 2, Furnace 5, and Furnace 7. Furnaces 2, 5, and 7 are open 

submerged arc furnaces rated at 32, 20, and 20 MW respectively. Each of these furnaces is

equipped with a positive-pressure baghouse to limit emissions of PM and metal HAP from the 

furnace. Fugitive emissions that occur during tapping from the furnace and casting are also 

captured and routed to the respective positive pressure baghouse. The facility has a crushing and 

sizing system controlled using a negative pressure baghouse. There are also fugitive emissions that 

are emitted from each of these emissions sources, in addition to the fugitive emissions from the 

casting operations for Furnace 2, Furnace 5, and Furnace 7.

4.0 SUMMARY OF PROPOSED MACT LIMITS

The existing NESHAP for the Ferroalloys Production source category (40 CFR part 63, subpart 

XXX) established emissions standards for PM (as a surrogate for metal HAP). Table 4-1 

summarizes the emissions standards in the existing NESHAP.

As shown in Table 4-1, the current NESHAP does not specify emissions limits for pollutants other 

than PM. Pursuant to sections 112(d)(2) and (3) of the Clean Air Act (CAA), MACT floors for 

mercury (Hg), formaldehyde, hydrogen chloride (HCl) and PAH were calculated for the proposed 

amendments to the NESHAP for the ferroalloys production source category published in 2011. 
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Table 4-1. Emissions Standards in the Ferroalloys NESHAP

(40 CFR part 63, subpart XXX)

New or 

Reconstructed or 

Existing Source Affected Source

Applicable PM Emission 

Standards

New or reconstructed Submerged arc furnace 

0.23 kg/hr/MW (0.51 lb/hr/MW) 

or 

35 mg/dscm (0.015 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)
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Because MACT limits had already been established for PM (a surrogate for metal HAP), a

technology review was conducted to determine if revisions to the PM standards were approriate. A 

summary of the proposed emission standards for the proposed amendments to the NESHAP for the 

ferroalloys production source category published in the Federal Register on November 23, 2011 (76 

FR 72508) is presented in Table 4-2.

The MACT floors and MACT limits in 2011 were determined using test data collected through a 

2010 ICR sent to the two facilities. The test data from the 2010 ICR provided HAP test data from 

one of the furnaces located at each of the facilities (Eramet has 2 operational furnaces and Felman 

has 3 operational furnaces), the MOR process (Eramet), and one of the crushing and sizing systems 

from each facility (each facility has 2 crushing and sizing systems). Therefore, limited data was 

used to develop HAP emission limits for the 2011 proposed amendments to the NESHAP.

5.0 OVERVIEW OF MACT STANDARD DEVELOPMENT METHODOLOGY USED 

TO DEVELOP THE REVISED MACT FLOORS FOR PAH AND HCl

The revised MACT floor for PAH and HCl were calculated using test data collected in the 2010 

ICR, and test data received from the facilities in response to the 2012 ICR. In addition, compliance 

test reports and other test data were received from the facilities in 2011 and 2012. The following 

sections outline the procedures used to develop the MACT floor limits for these HAP.

MACT Determination

Section 112(d) of the CAA requires EPA to set emissions standards for HAP emitted by major 

stationary sources. The MACT standards for existing sources must be at least as stringent as the 

average emissions limitation achieved by the best performing 12 percent of existing sources (for 

which the Administrator has emissions information) or the five best-performing sources for source 

categories with less than 30 sources (CAA section 112(d)(3)(A) and (B)). The Ferroalloy 

Production source category consists of fewer than 30 sources. Where, as here, there are five or 

fewer sources, the MACT floor limits were based on the average emissions limitation achieved by 

those sources for which we have data. This level of minimum stringency is called the MACT floor. 

For new sources, MACT standards must be at least as stringent as the control level achieved in 

practice by the best controlled similar source (CAA section 112(d)(3)). These requirements 

constitute the MACT floor for new and existing sources. EPA may not consider costs or other 

impacts in determining the MACT floors. EPA must consider cost, non-air quality health and 

environmental impacts, and energy requirements in connection with any standards that are more 

stringent than the MACT floor (beyond-the-floor controls).
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Table 4-2. Proposed HAP Emission Standards for the Ferroalloys Production NESHAP

published in FR on November 23, 2011 (76 FR 72508)

HAP Pollutant

New or 

Reconstructed or 

Existing Source Affected Source

Proposed Emission 

Standard

PM (surrogate for 

metal HAP) New or reconstructed Electric arc furnace 9.3 mg/dscm corrected to 2% CO2

PM (surrogate for 

metal HAP) Existing Electric arc furnace 24 mg/dscm corrected to 2% CO2

Hg New, reconstructed, or 

existing Electric arc furnace 16 μg/dscm corrected to 2% CO2

PAH New, reconstructed, or 

existing Electric arc furnace 89 μg/dscm corrected to 2% CO2

HCl New, reconstructed, or 

existing Electric arc furnace 809 μg/dscm corrected to 2% CO2

Formaldehyde New, reconstructed, or 

existing Electric arc furnace 201 μg/dscm corrected to 2% CO2

PM (surrogate for 

metal HAP)

New, reconstructed, or 

existing

Local ventilation used 

to capture tapping, 

casting, or ladle 

treatment emissions

24 mg/dscm corrected 

to 2% CO2

PM (surrogate for 

metal HAP)

New, reconstructed, or 

existing MOR process 3.9 mg/dscm corrected to 2% CO2

PM (surrogate for 

metal HAP)

New, reconstructed, or 

existing

Crushing and 

screening operations

13 mg/dscm corrected 

to 2% CO2

MACT analyses involve an assessment of the emissions from the best-performing units in a source 

category. The assessment can be based on actual emissions data, on knowledge of the air pollution 

control in place in combination with actual emissions data, or on state regulatory requirements that 

may enable EPA to estimate the actual performance of the regulated units and other relevant 

emissions information. For each source category, the assessment involves a review of actual 

emissions data with an appropriate accounting for emissions variability. Other methods of 

estimating emissions can be used provided that the methods can be shown to provide reasonable 

estimates of the actual emissions performance of a source or sources. In a March 2007 court 

decision (Sierra Club v. EPA, 479 F. 3d 875 [DC Cir. 2007]) (Brick MACT), EPA was directed to 

set MACT floors conforming to the statute, with these specific directives:
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 Floors for existing sources must reflect the average emissions limitation achieved by the 

best-performing 12 percent of existing sources, not levels EPA considers to be achievable 

by all sources (479 F. 3d at 880–81).

 EPA cannot set floors of “no control.” The court reiterated its prior holdings, confirming 

that EPA must set floor standards for all HAP emitted by the major source, including those 

HAP that are not controlled by at-the-stack control devices (479 F. 3d at 883).

 EPA cannot ignore non-technology factors that reduce HAP emissions. Specifically, the 

court held that “EPA’s decision to base floors exclusively on technology even though nontechnology factors affect emissions violates the Act” (479 F. 3d at 883).

 EPA may not use emissions levels of the worst performers to estimate variability of the best 

performers without a demonstrated relationship between the two (479 F. 3d at 882).

Consideration of Variability in Establishing Emission Limits

On August 20, 2013, the D.C. Circuit Court of Appeals issued its decision in National Assn. of 

Clean Water Agencies v. EPA, which involved challenges to EPA’s MACT standards for sewage 

sludge incinerators, issued under section 129 of the Act. The NACWA court recognized that EPA 

has significant discretion in establishing the MACT floors, including how to account for variability. 

See NACWA v. EPA, 734 F.3d at 1142-43 (“EPA can decide what value the MACT floors are 

supposed to represent, as long as that decision is a reasonable interpretation of the statute.”).

However, the court expressed concern about the interpretation it believed EPA was taking of the 

“average” emissions performance of the best performing sources. Specifically, the court asked for 

further clarification of how “’average’ means the average of a future 3-run compliance test.” Id. at 

1143. As explained below, EPA does not interpret the term “average” as used in section 112(d)(3) 

in this manner. Rather, EPA interprets the average to mean the average emissions over time, based 

on both the calculated average of all emissions test data from the best performing source or sources 

and the available information regarding the variability of emissions. The UPL, which EPA uses to 

account for variability among the best performing sources, reflects an upper limit for the emissions 

of those sources at times other than when the emissions tests occurred. This not only is a prediction 

of the emissions performance of those sources in tests conducted in the future, but is also an 

indication of the range of current average emissions performance of those units.

In calculating MACT floors, EPA analyzes all available emissions information and then uses the 

emissions information for the best performing source or sources to calculate a value that represents 

the level achieved in practice by the best controlled similar source for the new source MACT floor 

and a value that represents the average emission limitation achieved by the best performing twelve 

percent of sources for the existing source MACT floor. EPA must establish the MACT floor 

standards based on the emissions information before the agency, and the standards must be met at 

all times by sources subject to them. The available emissions data are generally in the form of short 

term, three-run stack tests, with each test run lasting for between 1 and 4 hours. Those short term 

tests cannot encompass the emissions performance of a source over time. EPA interprets “emissions 

performance,” as used in section 112(d)(3) to mean the emissions of a source over the long term, 
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rather than just during a short-term stack test. This is a reasonable interpretation of the statutory 

directive that the MACT standard be no less stringent than the average emissions limitation 

“achieved by” the best performing sources, since the emissions level of a source is not expected to 

always be the same as it is during stack testing. 

Therefore, EPA applies a methodology that predicts the actual emissions levels the source is 

achieving at times other than when stack testing was conducted. This enables EPA to calculate the 

average emissions performance of the best performing sources over time. Therefore, the MACT 

floor calculation takes into account the inherent variability in emissions performance to more 

accurately reflect the range of the best performing sources’ emissions over time. 

As explained in the memorandum titled Use of the Upper Prediction Limit for Calculating MACT 

Floors (UPL memorandum)

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, EPA does not interpret the term “average” as used in section 

112(d)(3) in this manner. Rather, EPA interprets the average to mean the average emissions over

time, based on both the calculated average of all emissions test data from the best performing 

source or sources and the available information regarding the variability of emissions. The UPL, 

which EPA uses to account for variability among the best performing sources, reflects an upper 

limit for the emissions of those sources at times other than when the emissions tests occurred. This 

not only is a prediction of the emissions performance of those sources in tests conducted in the 

future, but is also an indication of the range of current average emissions performance of those 

units.

However, alternative statistical methods were employed to account for variability when calculating 

MACT floors for HCl due to limited emissions data and the large amount of analytical non-detects 

reported for the test runs, as discussed further in section 6.1 of this memorandum.

6.0 MACT DETERMINATION FOR FERROALLOYS SOURCE CATEGORY

Emissions data for each of the furnaces were obtained from the facilities from Information 

Collection Requests (ICR) in 2010 and 2012 and from stack test submittals by the facilities. More 

information on the test data collected in the ICR can be found in the test data review summaries4,5

located in the docket. The individual test reports submitted by the facilities can also be found in the 

docket. For PAH, the test data from the 2010 ICR were collected using EPA Method 0010, 

whereas test data from the 2012 ICR and other submitted test reports were collected using 

California Air Resources Board Method 429 (CARB 429). The PAH test results from the two test 

methods were considered to be comparable and were used in the MACT Floor analysis. The test 

data for HCl was collected using either EPA Method 26 or 26a. The following sections summarize 

 

3 Memorandum from Phil Mulrine, EPA OAQPS to Docket ID No. EPA-HQ-OAR-2010-0895, Use of the Upper 

Prediction Limit for Calculating MACT Floors, July 30, 2014.

4 Memorandum from Bradley Nelson, EC/R to Conrad Chin, EPA/OAQPS/SPPD/MMG, Ferroalloys 2012 Test Report 

Review, May 28, 2013.

5 Memorandum from Bradley Nelson, EC/R to Conrad Chin, EPA/OAQPS/SPPD/MMG, Ferroalloys 2013 Test Report 

Review, July 29, 2013.
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the approach in determining the revised PAH and HCl MACT floors for the Ferroalloys Production 

source category using the upper prediction limit (UPL) using the guidelines provided in the UPL 

memorandum. For datasets (for the development of a specific emissions limit) that consisted of at 

least 3 test runs but fewer than 7 test runs, an approach developed for limited datasets was used to 

calulate the UPL.6

Furnace test data submitted by Eramet for testing conducted in July 2012 were not included in the 

MACT Floor analysis for PAH. These data consisted of only one run each from both Furnaces 1 

and 12 and one run from the Furnace 1 tapping baghouse. The Furnace 12 scrubber outlet PAH test 

was conducted during FeMn production, and the Furnace 1 baghouse outlet and Furnace 1 tapping 

baghouse outlet PAH tests were conducted during SiMn production. The test samples were diluted 

2000 times to obtain concentration results within the calibration. Because of the extreme dilution of 

the samples, the quantitative accuracy of the isotope dilution corrections to the data were brought 

into question. Furthermore, a valid emissions test generally should include 3 test runs. However, 

as stated above, these July 2012 PAH emissions tests included only one run. Therefore, these July 

2012 PAH test data were excluded from the dataset for PAH MACT Floor determinations.

6.1 Non-Detect Values

At very low emissions levels where emissions tests result in non-detect (ND) values, the inherent 

imprecision in the pollutant measurement method has a large influence on the reliability of the data 

underlying the regulatory floor emissions limit. Because of sample and emissions matrix effects, 

laboratory techniques, sample size and other factors, method detection levels normally vary from 

test to test for any specific test method and pollutant measurement. The confidence level that a 

value measured at the detection level is greater than zero is about 99 percent. The expected 

measurement imprecision for an emissions value occurring at or near the method detection level is 

about 40 to 50 percent. Pollutant measurement imprecision decreases to a consistent level of 10 to 

15 percent for values measured at a level about 3 times the method detection level. 

7.0 MACT FLOOR AND VARIABILITY ANALYSIS RESULTS

This section provides the results of the revised MACT floor analyses and UPL calulations for 

existing and new sources for PAH and HCl. Tables 7-1 through 7-5 present the results of the 

existing source MACT floor and variability analyses for PAH and HCl.

7.1 Existing Furnace - PAH

The test data for the furnace total PAH concentrations during FeMn and SiMn production were 

determined to be non-normal based on the results of the skewness and kurtosis tests. Because the 

 

6 Memorandum from Barrett Parker and Brian Shrager, EPA OAQPS to Docket ID No. EPA-HQ-OAR-2010-0895, 

Approach for Applying the Upper Prediction Limit to Limited Datasets, September 3, 2014. (This memo is also 

referred to as the Limited Dataset Memo). 
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amount of manganese ore, coal, and coke differs when producing the different products, separate 

statistical analyses were performed on the PAH test data during FeMn and SiMn production. The 

results of these analyses are provided in Table 7-1 and 7-2. 

The results of the PAH analysis show that there is a significant difference in PAH emissions during 

FeMn production as compared to SiMn production. It was concluded that the difference of PAH 

emissions during FeMn production and SiMn reduction was a result of the recipe and input 

materials used to make the different products. Therefore, it was determined that it would be 

appropriate to have two subcategories for PAH emissions and establish separate MACT limits for 

each of these two subcategories. The UPL results for these data sets using a 99 percent confidence 

level were determined to be 1,365 μg/dscm for FeMn production and 111 μg/dscm for SiMn 

production. These values were rounded up to the next highest integer using 2 significant figures, 

therefore the MACT floor limits for existing furnace sources were determined to be 1,400 μg/dscm 

for FeMn production and 120 μg/dscm for SiMn production. At these levels, we expect neither 

source would need to install additional controls to meet the emission limits.

7.2 New Furnace - PAH

The datasets for determining new source performance standards for PAH were based on test data 

with 6 or fewer data points. For each dataset, we looked at the average concentration from each of 

the furnaces when producing FeMn and SiMn and selected the data distribution that best represents 

each dataset; ensuring that the correct equation for the distribution was then applied to the data; and 

comparing individual components of each small dataset to determine if the standards based on small 

datasets reasonably represent the performance of the units included in the dataset. The results of 

each analysis are described and presented below with calculations of the datasets provided in 

Appendix A.

The MACT floor dataset for PAHs from new furnaces producing FeMn includes 3 test runs from a 

single furnace (Eramet Furnace 12) that we identified as the best performing unit based on average 

emissions performance. After determining that the dataset is best represented by a normal 

distribution and ensuring that we used the correct equation for the distribution, we evaluated the 

variance of the best performing unit. Our analysis showed that this unit, which was identified as the 

best unit based on average emissions, also had the lowest variance. Therefore, we determined that 

the emission limit would reasonably account for variability and that no changes to the standard 

floor calculation procedure were warranted for this pollutant and subcategory, and we are proposing 

that the MACT floor is 880 μg/dscm for PAHs from new furnaces producing FeMn.
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Table 7-1. Existing Source MACT Floor and Variability Analysis Results for Furnace PAH

during FeMn Production

PAH MACT Floor - FeMn Furnace

Total Facility Count 1 # Facilities

Total Furnace Count 2 # Furnaces

Average - All Runs 591.85 μg/dscm

Minimum - All Runs 244.100 μg/dscm

Maximum - All Runs 1141.15 μg/dscm

Sample Size (n) 6 # of runs

Skewness (S) 0.96

Std Error of Skewness (SES) 1.00

Skewness Test (reported values) 0.96 S/SES 

Normal S/SES>2

Kurtosis (K) 0.67

Std Error of Kurtosis (SEK) 2.00

Kurtosis Test (reported values)

0.34 K/SEK 

Normal K/SEK>2

99% UPL (normal distribution) 1364.15 μg/dscm

Table 7-2. Existing Source MACT Floor and Variability Analysis Results for Furnace PAH

during SiMn Production

PAH MACT Floor - SiMn Furnace

Total Facility Count 2 # Facilities

Total Furnace Count 5 # Furnaces

Average - All Runs 65.31 μg/dscm

Minimum - All Runs 21.230 μg/dscm

Maximum - All Runs 117.89 μg/dscm

Sample Size (n) 18 # of runs

Skewness (S) 0.26

Std Error of Skewness (SES) 0.58

Skewness Test (reported values) 0.45 S/SES 

Normal S/SES>2

Kurtosis (K) -0.57

Std Error of Kurtosis (SEK) 1.15

Kurtosis Test (reported values)

-0.50 K/SEK 

Normal K/SEK>2

99% UPL (normal distribution) 110.39 μg/dscm
12

The MACT floor dataset for PAHs initially identified for new furnaces producing SiMn includes 6 

test runs from a single furnace (Felman Furnace 2) that we identified as the best performing unit 

based on average emissions. After determining that the dataset is best represented by a normal 

distribution and ensuring that we used the correct equation for the distribution, we evaluated the 

variance of this unit (Felman Furnace 2) and concluded that further consideration of the variance 

was warranted. In particular, we noted that the variance of the dataset for this unit was almost twice 

as large as the variance of the dataset for the pool of best performing units that was used to calculate 

the existing source MACT floor. The high degree of variance in the dataset for the unit with the 

lowest average prompted us to question whether this unit was, in fact, the best performing unit and 

to evaluate the dataset for the unit with the next lowest average (Felman Furnace 7). The dataset for 

Furnace 7 includes 3 test runs, the furnaces are controlled with the same type of add-on control 

technology, and the average emissions from Furnace 2 are only about 22 percent lower than the 

average emissions from Furnace 7. While we find the average performance of these 2 units to be 

similar, the unit with the higher average has a variance more than 2 orders of magnitude lower than 

that of the unit with the lower average, thus indicating that the unit with the higher average has a far 

more consistent level of performance. The combination of components from the unit with the 

higher average (Felman Furnace 7) yields an emissions limit that is lower than that calculated from 

the dataset of the unit (Felman Furnace 2) with the lowest average (71.7 versus 132.8 μg/dscm). For 

these reasons, we determined that the unit with the lowest average (Felman Furnace 2) is not the 

best performing source for this pollutant and we are instead selecting Furnace 7 as the best 

performing source. After selecting the source upon which the new source limit would be based, we 

next considered whether the selection of a different confidence level would be appropriate. In this 

case, we determined that a lower confidence level was not warranted given the small amount of 

variance in the data for the unit that we identified as the best performer. Based on the factors 

outlined above, we are proposing that the MACT floor is 72 μg/dscm for PAHs from new furnaces 

producing SiMn. For more discussion on the evaluation of these limited datasets, please see the 

preamble for the supplemental proposal.

7.3 Existing Furnace - HCl

The data set for HCl includes 20 runs that were measured below the detection limit (BDL) or ND, 

out of the 36 runs that were performed (e.g., 56 percent of the runs were reported ND) on the 

furnace exhaust. For those runs that were reported BDL, the detection limit was used to calculate

the HCl concentration in the exhaust gas. The HCl data set used to calculate the UPL is provided in 

Appendix A. 

The procedures outlined in Section 6.3 were applied to account for the effect of measurement 

imprecision associated with a database that includes ND values, and to address the concerns 

associated with use of a small data set, such as the HCl data set. As a first step, the HCL emissions 

data set for the industrial boilers rule, which represents several hundred emissions tests, were used 

to demonstrate HCl results for the best performing units and also reflect the capabilities of high 

quality testing companies and laboratories. Further, the method detection levels calculated from 
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larger data sets are more representative of the inherent measurement variability both within and 

between testing companies than the limited ferroalloys production dataset is. The emission tests 

conducted with these methods for most combustion operations (e.g., fossil fuel, biomass, and waste 

fired units; brick and clay kilns; Portland cement kilns), including ferroalloys production, should 

produce method detection levels very similar to the level of 60 μg/dscm that is the result of this 

review. Accordingly, this value (60 μg/dscm) was determined as the representative method 

detection level (RDL) for HCl for this data set. 

The second step in the process is to calculate three times the RDL and compare that value to the 

calculated floor or emissions limit. If three times the representative method detection level was less 

than the calculated floor or emissions limit calculated from the UPL, it was concluded that the 

measurement variability was adequately addressed, and the calculated floor or emissions limit 

would not need to be adjusted. If, on the other hand, three times the representative method 

detection level was greater than the UPL, it would be concluded that the calculated floor or 

emissions limit did not account entirely for measurement variability. Then the value equal to three 

times the representative method detection level would apply as the adjusted floor or emissions limit. 

This adjusted value would ensure measurement variability is adequately addressed in the floor or 

the emissions limit. 

The data set for HCl concentrations from the furnace outlet were determined to be non-normal and 

is a result of the mix of analytical results reported above and below the detection limit, and not due 

to the type of product being produced (e.g., FeMn or SiMn) in the furnace. Therefore, the HCl data 

set was not segregated into FeMn and SiMn production. The equation for log-normally distributed 

data (Equation 4) was used to determine the UPL of the HCl data set. The UPL for the log-normal 

data set was calculated to be 1,028 μg/dscm. A summary of the log-normal statistical results are 

provided in Table 7-3. This value was rounded up to the next highest integer using 2 significant 

figures and the HCl limit was determined to be 1,100 μg/dscm for existing furnaces. Because the 

majority of the data set was reported BDL, three times the RDL for HCl (180 μg/dscm), was 

compared to this HCl limit, and the existing source HCl limit was higher, and thus was selected as 

the MACT floor for existing furnaces.

7.4 New Furnace - HCl

To calculate the HCl MACT floor for new furnaces, the “best performing source” was determined 

by ranking the sources by the 99 percent UPL for each source. The source with the lowest average 

UPL is the “best performing source”, and the average 99 percent UPL is the value that would 

typically be proposed for the MACT Floor limit for new sources. A summary of the results of this 

analysis is provided in Appendix A. The 99 percent UPL for new sources was determined to be 

108 μg/dscm. However, this UPL value is less than three times the RDL (180 μg/dscm), therefore 

180 μg/dscm was selected as the MACT floor for HCl for new furnaces.
14

Table 7-3. Existing Source MACT Floor and Variability Analysis Results for Furnace HCl

Log-Normal Distribution

HCl MACT Floor - Furnace Outlet

Total Facility Count 2 # Facilities

Total Furnace Count 5 # Furnaces

Sample Size (n) 36 # of runs

Skewness (S) -0.71

Std Error of Skewness (SES) 0.41

Skewness Test (reported values) -1.74 S/SES 

Normal S/SES>2

Kurtosis (K) -0.19

Std Error of Kurtosis (SEK) 0.82

Kurtosis Test (reported values)

-0.23 K/SEK 

Normal K/SEK>2

99% UPL (log-normal distribution) 1027.48 μg/dscm

8.0 SUMMARY OF REVISED MACT FLOOR DETERMINATIONS

The revised MACT floor determinations based on the new test data received after proposal of the 

amendments to the national emission standards for hazardous air pollutants (NESHAP) for the 

ferroalloys production source category published in the Federal Register on November 23, 2011 (76 

FR 72508) is summarized in Table 8-1. 

As the table shows, the PAH test data showed a significant difference in PAH exhaust gas 

concentration between FeMn and SiMn production. Therefore, separate UPL analyses were 

performed for each of the different products. The PAH MACT floor limit calculated for the 2011 

proposed rule was based on a single test, whereas the revised MACT floor limits for PAH are based 

on 8 emissions tests for PAHs (2 during FeMn production and 6 during SiMn production). The 

PAH test data used for the analyses are provided in Appendix A.
15

Table 8-1. Summary of Revised MACT Floor Determination for PAH and HCl

HAP Pollutant

New or 

Reconstructed or 

Existing Source Affected Source

Revised MACT Floor 

Limits 

PAH Existing

Electric arc furnace 

during FeMn 

production

1,400 μg/dscm

PAH New or reconstructed

Electric arc furnace 

during FeMn 

production

880 μg/dscm

PAH Existing

Electric arc furnace 

during SiMn 

production

120 μg/dscm

PAH New or reconstructed

Electric arc furnace 

during SiMn 

production

72 μg/dscm

HCl Existing Electric arc furnace 1,100 μg/dscm

HCl New or reconstructed Electric arc furnace 180 μg/dscm

The HCl MACT floor analysis was based on a total of 12 tests performed on the furnace located at 

Eramet and Felman. There was no distinction found between the HCl concentration in the furnace 

exhaust during FeMn and SiMn production, and all of the test data was used to determine the 

MACT floor for existing and new or reconstructed sources. As previously stated, the HCl data set 

is based on 56 percent of the runs being measured BDL, which provides some uncertainty in the 

MACT floor calculation. In lieu of setting numerical emissions limits, another possible option

might be to establish a work practice standard to limit the HCL emissions from the furnace, by 

limiting the chlorine content of the coal, coke, or antifreeze compounds that are used in the furnace.

However, no feasible or practical approaches have been identified to limit the chlorine content of 

these materials in this industry therefore this option is not being proposed in the supplemental 

proposal.

9.0 BEYOND THE FLOOR

To evaluate opportunities for emissions reductions beyond those that would result from requiring 

facilities to meet the MACT floor emissions limits, we typically identify control techniques that 

have the ability to achieve an emissions limit more stringent than the MACT floor and evaluate 

whether the standard should be more stringent based on consideration of the factors enumerated in 

section 112 (d)(2) of the Act. The following paragraphs summarize the results of this “beyond-thefloor” analysis for the affected sources in the Ferroalloys production source category.
16

Through our technology review and risk analyses, we identified beyond-the-floor options to achieve 

further reduction in emissions of PAH and HCl. Additional detail on these options is presented 

below and in Cost Impacts for the Ferroalloys Source Category.

PAH 

For PAH emissions, the control performance that could be achieved via co-control of mercury 

emissions with activated carbon injection (ACI) were evaluated as a beyond-the-floor option. 

Based on information from carbon vendors, an activated carbon system that is designed to achieve 

up to 90 percent reduction in mercury emissions, should also achieve significant reductions in PAH 

with no additional costs. Albemarle noted in a presentation7that 9 out of 10 conventional boilers 

equipped with ACI reported PAH analytical results below the detection limit. The other boiler 

reported PAH results that were only 10 percent above the detection limit. Another study8found 

that ACI can achieve 74-91 percent reduction in PAH emissions depending on the concentration of 

activated carbon in the flue gas. Based on this information, it is believed that ACI can achieve 75

percent reduction of PAH emissions from the furnace. Therefore, for this analysis, we assume 

percent reduction of PAH with the use of an activated carbon injection system would be 75 percent 

reduction in PAH emissions from the furnace exhaust. Therefore, possible beyond the floor limits 

for PAH concentrations from the furnace outlet control device would be 342 μg/dscm for new, 

reconstructed, or existing FeMn production furnaces, and 28 μg/dscm for new, reconstructed, or 

existing SiMn production furnaces. The estimated capitol and annualized costs to achieve these 

beyond the floor PAH limits are the same costs as those shown for mercury in the mercury control 

options memorandum. For FeMn production, the capital cost was calculated to be $30.2 million 

and the annual cost was calculated to be $3.3 million and would only apply to the furnaces at 

Eramet. The capital cost for the beyond the floor PAH option for SiMn production was calculated 

to be $82.5 million with an annual cost of $10.4 million.

HCl 

No facilities in the source category use add-on control devices or work practices to limit emissions 

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

control device. Also, as explained above, there are a large number of non-detects for HCl (56

percent of test results were below detection). Thus, emissions are already considered relatively low. 

Nevertheless, we evaluated possible beyond the floor options to further reduce HCl to ensure our 

analyses were complete. 

There are available add-on control devices, such as dry sorbent injection (DSI) or lime injection that 

are believed to be a viable control technology to reduce HCl emissions from furnaces in cases 

 

7

Presentation by Dr.Ronald R. Landreth, Albemarle, Alternative Method of Hg and THC Control Using Existing 

Cement Kiln Particulate Control Equipment, February 9, 2010.

8 Hong-Cang Zhou, Zhao-Ping Zhong, Bao-Sheng Jin, Ya-Ji Huang, and Rui Xiao, Experimental study on the removal 

of PAHs using in-duct activated carbon injection, Chemosphere, November 17, 2004.
17

where HCl emissions are significant. 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 HCl, 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 (which have much higher HCl 

emissions compared to Ferroalloys plants) and achieves up 90 percent reduction of HCl from the 

coal-fired boilers.

The capital cost for DSI is estimated to be $10 per kilowatt for coal-fired boilers9. Converting this 

cost to an EAF produces an estimated capital cost of $625,000 for a 25 megawatt EAF10. However, 

the major cost of DSI systems is the sorbent11. The DSI control technology has a relatively high 

operating cost, which ranges from $3.4 to $5 per kilowatt-year ($/kW-yr)12, 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. 

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. 

 

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

2011.

10 Assumes 40 percent efficiency for the coal-fired boiler.

11 Sargent & Lundy, IPM Model – Revisions to Cost and Performance for APC Technologies, Dry Sorbent Injection 

Cost Development Methodology Final, August 2010.

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

2011.
18

Appendix A

PAH and HCl Data Sets used to Calculate UPL

and 

Non-normal UPL Calculation for PAH
19

Furnace PAH Data 

Facility Sample Date Sample Location Test Method Furnace Product

Run 1 Conc. 

(μg/dscm)

Run 2 Conc. 

(μg/dscm)

Run 3 Conc. 

(μg/dscm)

Average Conc. 

(μg/dscm)

Furnace 

Average Conc 

(μg/dscm)

Number of 

Test Runs in 

Furnace 

Average

Furnace 99% 

UPL

Eramet 3/6/2013 Furnace 1 Baghouse Outlet Method 429 FeMn 1141.2 646.9 732.2 840.1 840.1 3 2342.4

Eramet 8/17/2010 Furnace 12 Scrubber Outlet Method 23 FeMn 244.1 357.3 429.5 343.6 343.6 3 875.0

Eramet 3/6/2013 Furnace 12 Scrubber Outlet Method 429 SiMn 108.6 91.4 87.4 95.8 95.8 3 159.7

Felman 7/25/2012 Furnace 2 Baghouse Outlet Method 429 SiMn 27.8 25.2 21.2 24.7

Felman 3/18/2013 Furnace 2 Baghouse Outlet Method 429 SiMn 38.4 117.9 56.0 70.8 47.7 6 134.8

Felman 8/10/2012 Furnace 5 Baghouse Outlet Method 429 SiMn 58.2 57.4 59.9 58.5

Felman 3/14/2013 Furnace 5 Baghouse Outlet Method 429 SiMn 103.0 80.9 59.0 81.0 69.7 6 114.0

Felman 8/7/2012 Furnace 7 Baghouse Outlet Method 429 SiMn 62.9 59.2 61.2 61.1 61.1 3 71.7

Tapping BH PAH Data 

Facility Analyte Sample Date Sample Location Test Method Furnace Product

Run 1 Conc. 

(μg/dscm)

Run 2 Conc. 

(μg/dscm)

Run 3 Conc. 

(μg/dscm)

Average Conc. 

(μg/dscm)

Local 

Ventilation 

99% UPL

Eramet Total PAH 3/6/2013 Furnace 1 Tapping Baghouse Outlet Method 429 FeMn 80.4 56.9 57.2 64.8 141

Furnace Hydrogen Chloride Emission Test Data

Facility Sample Date Sample Location Test Method

Furnace 

Product

Run 1 Conc. 

(μg/dscm)

Run 2 Conc. 

(μg/dscm)

Run 3 Conc. 

(μg/dscm)

Average Conc. 

(μg/dscm)

Furnace 

Average Conc. 

(μg/dscm)

Number of 

Test Runs in 

Furnace 

Average

Furnace 99% 

UPL

Eramet 5/26/2011 Furnace 1 Baghouse Outlet Method 26A SiMn 442.739 440.086 405.136 429.320

Eramet 7/24/2012 Furnace 1 Baghouse Outlet Method 26A SiMn 599.911 424.139 457.346 493.799

Eramet 3/5/2013 Furnace 1 Baghouse Outlet Method 26A FeMn 375.064 380.767 378.624 378.152 433.757 9 567.7

Eramet 8/17/2010 Furnace 12 Scrubber Outlet Method 26A FeMn 484.293 311.048 309.224 368.189

Eramet 7/25/2012 Furnace 12 Scrubber Outlet Method 26A FeMn 499.973 515.675 499.607 505.085

Eramet 3/5/2013 Furnace 12 Scrubber Outlet Method 26A SiMn 314.859 303.571 349.403 322.611 398.628 9 586.4

Felman 7/9/2010 Furnace 2 Baghouse Outlet Method 26A SiMn 351.283 419.512 678.473 483.089

Felman 8/13/2012 Furnace 2 Baghouse Outlet Method 26A SiMn 231.305 286.679 260.077 259.354

Felman 3/19/2013 Furnace 2 Baghouse Outlet Method 26A SiMn 1056.107 864.390 658.620 859.706 534.050 9 1102.2

Felman 8/9/2012 Furnace 5 Baghouse Outlet Method 26A SiMn 85.939 98.271 94.156 92.788

Felman 3/19/2013 Furnace 5 Baghouse Outlet Method 26A SiMn 85.671 76.763 77.099 79.844 86.316 6 107.1

Felman 8/7/2012 Furnace 7 Baghouse Outlet Method 26A SiMn 171.202 258.313 144.393 191.303 191.303 3 530.0
20