1

MEMORANDUM

DATE: May 22, 2015

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 results of the revised maximum achievable 

control technology (MACT) floor determination for mercury (Hg), 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 

incorporating newly provided test data1,2 received prior to and after the publication of the 2014

supplemental proposed amendments to the national emission standards for hazardous air pollutants 

(NESHAP) for the ferroalloys production source category, published in the Federal Register on 

October 10, 2014 (79 FR 60238). This additional test data was received from one of the facilities, 

and provides additional HAP data for some pollutants at previously tested emission sources, 

including PAH and Hg data from each of the operational furnaces at a single facility, one furnace 

producing FerroManganese (FeMn) and the other producing SilicoManganese (SiMN). 

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

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

the PAH and Hg emissions limits for new and existing sources. The new test data included only 

PAH and Hg emissions, and thus did not warrant any changes to the previously proposed emission 

limits for other pollutants. Background information, facility summaries, details of previously 

proposed limits, and details of methodology are unchanged from those described in MACT Floor 

memorandum supporting the supplemental proposal and thus is not included here.

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 1 "Emission Measurement Summary Report Furnace No. 12 Scrubber PAHs and Mercury Eramet Marietta Inc. 

Marietta, OH", January 2013. 2 "Polycyclic Aromatic Hydrocarbons and Mercury Emission Summary Report EAF No. 12 Scrubber EAF No. 1 

Baghouse Eramet Marietta Inc. Marietta, OH". 3 Memorandum from Bradley Nelson, EC/R to Phil Mulrine, EPA OAQPS/SPPD/MICG, Revised MACT Floor 

Analysis for the Ferroalloys Production Source Category, August 29, 2014, EPA-HQ-OAR-2010-0895-0174.
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2.0 SUMMARY OF PROPOSED MACT LIMITS

A summary of the proposed emission standards as they stand after the supplemental proposal of

amendments to the Ferroalloys NESHAP published in the Federal Register on October 10, 2014 (79

FR 60238) is presented in Table 2-1. With the exception of the revisions detailed in the following 

sections, these will be the final MACT emission limits.

3.0 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. The 

individual test reports submitted by the facilities can be found in the docket for this rulemaking 

(EPA-HQ-OAR-2010-0895). 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 Hg was collected using either EPA Method 29 or 30b. 

The following sections summarize the approach in determining the revised PAH and Hg 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.4

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.

 4 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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Table 2-1. Proposed HAP Emission Standards for the Ferroalloys Production NESHAP 

Subsequent to the Supplemental Proposal of October 10, 2014 (79 FR 60238)

HAP Pollutant

New or 

Reconstructed or 

Existing Source Affected Source

Proposed

Emission 

Standard

PM (surrogate for 

metal HAP) New or reconstructed Electric arc furnace (EAF) 9.3 mg/dscm 

PM (surrogate for 

metal HAP) Existing EAF 24 mg/

Hg Existing EAF (FeMn production) 170 μg/dscm 

Hg New or reconstructed EAF (FeMn production) 170 μg/dscm 

Hg Existing EAF (SiMn production) 12 μg/dscm 

Hg New or reconstructed EAF (SiMn production) 4 μg/dscm 

PAH Existing EAF (FeMn production) 1,400 μg/dscm

PAH New or reconstructed EAF (FeMn production) 880 μg/dscm

PAH Existing EAF (SiMn production) 120 μg/dscm

PAH New or reconstructed EAF (SiMn production) 72 μg/dscm

HCl Existing EAF 1,100 μg/dscm

HCl New or reconstructed EAF 180 μg/dscm

Formaldehyde New, reconstructed, or 

existing EAF 201 μg/dscm 

PM (surrogate for 

metal HAP)

New, reconstructed, or 

existing

Local ventilation used to 

capture tapping, casting, or 

ladle treatment emissions

24 mg/dscm 

PM (surrogate for 

metal HAP) New, reconstructed, or 

existing MOR process 3.9 mg/dscm 

PM (surrogate for 

metal HAP) New, reconstructed, or 

existing

Crushing and screening 

operations 13 mg/dscm 
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4.0 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 Hg. Tables 4-1 through 4-4 present the results of the 

existing source MACT floor and variability analyses for PAH and Hg. The procedures outlined in 

the UPL caclulation memorandum5 were used to determine the approriate UPL equation to use.

4.1 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 

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 4-1 and 4-2. 

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 were rounded up to the next highest integer using 2 or 3 significant figures, therefore the 

MACT floor limits for existing furnace sources were determined to be 11,500 μg/dscm for FeMn 

production and 130 μg/dscm for SiMn production. At these levels, we expect neither source would 

need to install additional controls to meet the emission limits.

4.2 New Furnace - PAH

There are only two furnaces in the source category that produce FeMn, and both furnaces are 

located at Eramet. The units are similar in design and process the same types of raw materials, and 

we, therefore, expect little or no difference in the performance of these units. The available 

emissions data, which show that the two units mean emissions are only 2 percent different, support 

this hypothesis. We conclude, based on the similarities in the units and the available data that these 

two furnaces achieve the same degree of control of PAH emissions with their current control 

devices. Accordingly, we consider these two units to be equal performers with regard to PAH 

emissions and we used all the data from both units to calculate the new source limit. Using the 99 

percent UPL calculation, we derive an emissions limit of 11,500 ug/dscm for new furnaces 

producing ferromanganese.

 5 Memorandum from Phil Mulrine, EPA OAQPS/SPPD/MICG to Docket ID No. EPA-HQ-OAR-2010-0895, Use of 

Upper Prediction Limit for Calculating MACT Floors, July 30, 2014. EPA-HQ-OAR-0895-0179.
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Table 4-1. 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 4482.04 μg/dscm

Minimum - All Runs 244.100 μg/dscm

Maximum - All Runs 10488.44 μg/dscm

Sample Size (n) 13 # of runs

Skewness (S) 0.25

Std Error of Skewness (SES) 0.68

Skewness Test (reported values) 0.36 S/SES 

Normal S/SES>2

Kurtosis (K) -1.84

Std Error of Kurtosis (SEK) 1.36

Kurtosis Test (reported values) -1.35 K/SEK 

Normal K/SEK>2

99% UPL (normal distribution) 11458.21 μg/dscm

Table 4-2. 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 74.84 μg/dscm

Minimum - All Runs 21.230 μg/dscm

Maximum - All Runs 158.53 μg/dscm

Sample Size (n) 22 # of runs

Skewness (S) 0.46

Std Error of Skewness (SES) 0.52

Skewness Test (reported values) 0.88 S/SES 

Normal S/SES>2

Kurtosis (K) 0.09

Std Error of Kurtosis (SEK) 1.04

Kurtosis Test (reported values)

0.09 K/SEK 

Normal K/SEK>2

99% UPL (normal distribution) 128.12 μg/dscm
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The analysis and calculations used to determine the MACT floor for PAHs from new furnaces 

producing SiMn are unchanged from the October 2014 supplemental proposal. The final MACT 

floor is 72 μg/dscm for PAHs from new furnaces producing SiMn.

4.3 Existing Furnace - Hg

The mercury test results for FeMn production were significantly different in comparison to the 

mercury test results during SiMn production. This difference is a direct result of the amount of raw 

materials and procedures used to produce the different products. The FeMn product consists of 

approximately 78 percent Mn content with a carbon content ranging from 7.5 to 0.5 percent carbon, 

and is produced using Mn ore and high carbon coke. The formula used to produce FeMn requires a 

much greater amount of Mn ore in comparison to the SiMn production, and the high carbon coke is 

needed to reduce the manganese oxide (MnO2) in the ore to produce the high Mn content in the 

FeMn product. The SiMn product is approximately 65 percent manganese, and includes 

approximately 16 percent silicon and 2 percent carbon. A different formulation of raw materials is 

used to produce the SiMn product. The primary source of mercury emissions from the furnace 

smelting process is the Mn ore used to produce the products. Because of the difference in the 

amount of Mn ore that is needed for FeMn production, the mercury emissions from FeMn 

production are significantly higher than the mercury emissions from SiMn production. Therefore, 

the ferroalloy products (FeMn and SiMn) were subcategorized for determining mercury emissions 

limits, and separate MACT limits were established for each of these two subcategories.

A total of fourteen mercury tests from the outlet of the control device from the furnace smelting 

process were submitted to EPA from the Ferroalloy facilities. Two of the tests were measured 

using EPA Method 29 and the other twelve were measured using EPA Method 30B. One of the 

EPA Method 30B tests was invalidated (Felman Furnace 5 performed on 3/20/2013) because the 

test runs did not meet the breathrough criteria and lacked sufficient QA/QC to be used in the 

MACT Floor calculations. In addition, eight of the individual Method 30B runs were also 

invalidated because the paired sample agreement was greater than the EPA Method 30B quality 

assurance criteria that requires the paired samples to have a relative deviation of less than or equal 

to 10 percent for samples with a mercury concentration of greater than 1 microgram per dry 

standard cubic meter (μg/dscm). Therefore, the data set used to calculate the UPL for the MACT 

Floor consisted of a total of 13 tests (5 during FeMn production and 8 during SiMn production) for 

a total of 33 individual runs (15 runs during FeMn production and 18 runs during SiMn 

production).

A statistical analysis was performed on the FeMn data seta and the SiMn data set and a summary of 

the results is provided in Tables 4-3 and 4-4. The skewness and kurtosis tests performed on each of 

the data sets showed that both the FeMn Production and the SiMn Production data sets were 

normally distributed. The UPL for normally distributed data was used to calculate the UPL for 

each of the two data sets. As the results show, the FeMn Production UPL result of 130 μg/dscm

(rounded up to the nearest whole integer using 2 significant figures) provides a limit that is higher 
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than any of the test data results (to account for variability in the data set) and provides a limit that 

can be achieved using the current control technology. 

The mercury data set for SiMn production was also determined to normally distributed and the UPL 

for the data set was calculated to be 12 μg/dscm (rounded up to the nearest whole integer). The 

UPL, as described above, accounts for variability in the test data set and was determined to be 

achievable using the current control technology.

4.4 New Furnace - Hg

The MACT floor for new sources was calculated by first determining the “best performing source” 

for each of the FeMn and SiMn production data sets. This was done by ranking the sources by the 

99 percent UPL of the test data for each furnace. The source with the lowest UPL by furnace 

product (FeMn or SiMn) would be established as the “best performing source”, and the 99 percent 

UPL would be the MACT floor limit for new sources. A summary of the test data and the UPL 

rankings are provided in Appendix A. 

The test data for FeMn production included 9 test runs from a single furnace (Eramet Furnace 12) 

that was identified as the "best performing source" based on average emissions, and the 99 percent 

UPL was calculated to be 130 μg/dscm (rounded up to the nearest whole integer using 2 significant 

figures).

The analysis and calculations used to determine the MACT floor for Hg from new furnaces 

producing SiMn are unchanged from the October 2014 supplemental proposal.Error! Bookmark not defined.

The final MACT floor is 4 μg/dscm for Hg from new furnaces producing SiMn. 

5.0 SUMMARY OF REVISED MACT FLOOR DETERMINATIONS

The revised MACT floor determinations for PAH and Hg based on the new test data received prior 

to and after the publication of the 2014 supplemental proposed amendments to the national 

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

category, published in the Federal Register on October 10, 2014 (79 FR 60238) are summarized in 

Table 5-1. The test data used for the analyses are provided in Appendix A.
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Table 4-3. Existing Source MACT Floor and Variability Analysis Results for Furnace Hg 

during FeMn Production

Hg MACT Floor - FeMn Furnace

Total Facility Count 1 # Facilities

Total Furnace Count 2 # Furnaces

Average - All Runs 68.58 μg/dscm

Minimum - All Runs 28.614 μg/dscm

Maximum - All Runs 130.36 μg/dscm

Sample Size (n) 15 # of runs

Skewness (S) 0.42

Std Error of Skewness (SES) 0.63

Skewness Test (reported values) 0.66 S/SES 

Normal S/SES>2

Kurtosis (K) -1.38

Std Error of Kurtosis (SEK) 1.26

Kurtosis Test (reported values) -1.09 K/SEK 

Normal K/SEK>2

99% UPL (normal distribution) 127.84 μg/dscm

Table 4-4. Existing Source MACT Floor and Variability Analysis Results for Furnace Hg 

during SiMn Production

Hg MACT Floor - SiMn Furnace

Total Facility Count 2 # Facilities

Total Furnace Count 5 # Furnaces

Average - All Runs 4.42 μg/dscm

Minimum - All Runs 0.347 μg/dscm

Maximum - All Runs 11.87 μg/dscm

Sample Size (n) 18 # of runs

Skewness (S) 0.61

Std Error of Skewness (SES) 0.58

Skewness Test (reported values) 1.06 S/SES 

Normal S/SES>2

Kurtosis (K) -1.52

Std Error of Kurtosis (SEK) 1.15

Kurtosis Test (reported values) -1.32 K/SEK 

Normal K/SEK>2

99% UPL (normal distribution) 11.61 μg/dscm
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Table 5-1. Summary of Revised MACT Floor Determination for PAH and Hg

HAP Pollutant

New or 

Reconstructed or 

Existing Source Affected Source

Revised MACT 

Floor Limits 

PAH Existing

Electric arc furnace 

during FeMn 

production

11,500 μg/dscm

PAH New or reconstructed

Electric arc furnace 

during FeMn 

production

11,500 μg/dscm

PAH Existing

Electric arc furnace 

during SiMn 

production

130 μg/dscm

PAH New or reconstructed

Electric arc furnace 

during SiMn 

production

72 μg/dscm

Hg Existing

Electric arc furnace 

during FeMn 

production

130 μg/dscm

Hg New or reconstructed

Electric arc furnace 

during FeMn 

production

130 μg/dscm

Hg Existing

Electric arc furnace 

during SiMn 

production

12 μg/dscm

Hg New or reconstructed

Electric arc furnace 

during SiMn 

production

4 μg/dscm
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6.0 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. 

No beyond the floor options were selected for PAH, as detailed in Revised MACT Floor Analysis 

for the Ferroalloys Production Source Category.

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For new and reconstructed furnaces producing FeMn, it was determined to employ a beyond the 

floor approach based on 90 percent mercury reduction as set out in Mercury Control Options and 

Impacts for the Ferroalloys Production IndustryError! Bookmark not defined. (fabric filters and the 

installation of brominated carbon activated carbon injection), with a resultant emission limit of 13

μg/dscm (rounded up to the nearest whole integer.) 
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Appendix A

PAH and Hg Data Sets used to Calculate UPL
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Furnace Hg 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)

Run 4 

Conc.

(μg/dscm)

Average 

Conc.

(μg/dscm)

Furnace 

Average 

Conc.

(μg/dscm)

Number 

of Test 

Runs in 

Furnace 

Average

Furnace 

99% UPL

Eramet 3/4/2013 Furnace 1 Baghouse Outlet Method 30B FeMn 28.614 44.339 36.477

Eramet 10/16/2014 Furnace 1 Baghouse Outlet Method 30B FeMn 96.403 130.358 108.607 71.602 101.602 79.894 6 172.754

Eramet 8/16/2010 Furnace 12 Scrubber Outlet Method 29 FeMn 30.917 29.046 34.713 31.559

Eramet 7/25/2012 Furnace 12 Scrubber Outlet Method 30B FeMn 79.865 117.865 106.733 101.261

Eramet 10/23/2012 Furnace 12 Scrubber Outlet Method 30B FeMn 47.050 39.321 64.470 50.280 61.033 9 125.618

Eramet 7/24/2012 Furnace 1 Baghouse Outlet Method 30B SiMn 8.826 11.867 10.347 10.347 2 72.804

Eramet 3/4/2013 Furnace 12 Scrubber Outlet Method 30B SiMn 2.231 2.231

Eramet 10/16/2014 Furnace 12 Scrubber Outlet Method 30B SiMn 10.660 10.637 9.307 10.452 10.264 8.657 5 18.606

Felman 7/9/2010 Furnace 2 Baghouse Outlet Method 29 SiMn 0.694 4.949 4.327 3.323

Felman 8/13/2012 Furnace 2 Baghouse Outlet Method 30B SiMn 0.679 0.783 0.731

Felman 3/20/2013 Furnace 2 Baghouse Outlet Method 30B SiMn 0.469 0.528 0.498 1.775 7 6.040

Felman 8/9/2012 Furnace 5 Baghouse Outlet Method 30B SiMn 0.629 0.629 0.629 1 N/A

Felman 8/7/2012 Furnace 7 Baghouse Outlet Method 30B SiMn 0.347 0.683 1.535 0.855 0.855 3 4.337

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)

Run 4 

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

Eramet 10/15/2014 Furnace 1 Baghouse Outlet Method 429 FeMn 6148.1 8939.9 9056.3 4405.5 7137.5 4438.6 7 12528.6

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

Eramet 10/23/2012 Furnace 12 Scrubber Outlet Method 429 FeMn 10488.4 9343.7 6333.3 8721.8 4532.7 6 15920.0

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

Eramet 10/16/2014 Furnace 12 Scrubber Outlet Method 429 SiMn 109.5 95.2 158.5 107.9 117.8 108.3 7 160.1

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 38.3 117.9 56.0 70.7 47.7 6 134.7

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