Document ID: EPA-HQ-OAR-2017-0664-0002
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2019-09-25T04:00Z

MEMORANDUM

TO:		Taconite Iron Ore Processing RTR Docket (Docket ID No. EPA-HQ-OAR-2017-0664)

FROM:	David Putney, EPA

DATE:	August 23, 2019

--------------------------------------------------------------------------------
SUBJECT:	Development of the Residual Risk Review Emissions Dataset for the Taconite Iron Ore Processing Source Category

The purpose of this memorandum is to document the technical approach and rationale used to assign hazardous air pollutant (HAP) emissions data for taconite iron ore processing facilities. This work is being performed pursuant to section 112(f) of the Clean Air Act as part of the residual risk assessment for facilities subject to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Taconite Iron Ore Processing (i.e., 40 CFR part 63, subpart RRRRR). A list of the acronyms used in this document, and their meanings, is shown below.
CFR	Code of Federal Regulations
CY2014	Calendar year 2014
D/F	Dioxins and Furans
EPG	Emission Process Group
FR	Federal Register
FDECP	Fugitive dust emissions control plan sources
ft[3]	Cubic feet
HAP	Hazardous Air Pollutant(s)
HCl	Hydrochloric acid (hydrogen chloride)
HF	Hydrofluoric acid (hydrogen fluoride)
MAERS	Michigan Air Emissions Reporting System
MMBtu	million British thermal units
MI	Michigan
MN	Minnesota
MPCA	Minnesota Pollution Control Agency
NEI	National Emissions Inventory
NESHAP	National Emission Standards for Hazardous Air Pollutants
OCH	Ore crushing and handling operations
PAH	Polycyclic Aromatic Hydrocarbons
PH	Pellet handling operations
PI	Pellet induration
TIOP	Taconite iron ore processing
I.	Taconite Iron Ore Processing Source Category
The Taconite Iron Ore Processing source category consists of eight individual facilities. Six of these facilities are located in Minnesota (MN) and two are located in Michigan (MI). Table 1 details the names, ownership, locations, and National Emission Inventory (NEI) site identification numbers of these facilities. Note that in all cases except for United Taconite and Northshore Mining the taconite iron ore processing (TIOP) facilities are located adjacent to the associated taconite mine. In the case of United Taconite, the processing facility is located in Forbes, MN whereas the mine is located in Eveleth, MN (about 11 miles away). In the case of Northshore Mining, the processing facility is located in Silver Bay, MN whereas the mine is located in Babbitt, MN (about 47 miles away). TIOP facilities take a low grade iron ore (i.e., taconite, which has about 20 - 25 percent iron content) and process that ore to generate marble size (about 3/8 inch diameter) pellets with an iron content of about 60 - 65 percent. Most of these pellets, about 98 percent, are sent to iron and steel manufacturers for use as feed material.[1,2]
                          Table 1: Facility Summaries
                                 Facility Name
                              Parent Company(ies)
                                    Address
                              Previous Ownership
                                NEI Site ID No.
Minorca Mine
ArcelorMittal
5950 Old Hwy 53 North
Virginia, MN 55792
Ispat-Inland Steel Mining Company
NEI44497
Empire Mine
ArcelorMittal and
Cliffs Natural Resources
101 Empire Mine Road
Palmer, MI 49871

NEIMIB 1827
Hibbing Taconite
ArcelorMittal,
U.S. Steel and
Cliffs Natural Resources
4950 County Hwy 5 North
Hibbing, MN 55746

NEIMN 1525
Northshore Mining
Cliffs Natural Resources
10 Outer Drive
Silver Bay, MN 55614
Reserve Mining
NEI44734
Tilden Mine
U.S. Steel and
Cliffs Natural Resources
1 Tilden Mine Road
Ishpeming, MI 49849

NEIMIB 4885
United Taconite
Cliffs Natural Resources
8479 Townline Road
Forbes, MN 55738
Eveleth Taconite Company (EVTAC)
NEI45720
Keewatin Taconite
(also known as Keetac)
U.S. Steel
1 Mine Road
Keewatin, MN 55753
National Steel Pellet Company (NSPC)
NEIMN 0612713
Minnesota Taconite
(also known as Minntac)
U.S. Steel
8819 Old Hwy 169
Mountain Iron, MN 55768

NEI44493
                                       
Refer to Figure 1, above, for the approximate locations (the map is not to scale) of the subject taconite iron ore processing facilities. Refer to Figure 2, below, for an example process flow diagram of a typical taconite iron ore processing facility.
Figure 2: Typical Taconite Iron Ore Processing Facility Process Flow Diagram [3]
                                       
Table 2, below, provides a summary of actual and effective pellet production rates at the eight subject taconite iron ore processing facilities. For the facilities located in Minnesota, the actual and effective pellet production rates were obtained from the MN 2016 Mining Tax Guide.[4] For the facilities located in Michigan, the calendar year 2014 (CY2014) pellet production rates were obtained from the Michigan Air Emissions Reporting System [5,6] (MAERS) and the effective pellet production rates were obtained from the background information document for the proposed taconite iron ore processing NESHAP (refer to page 2-6 of that document).[7]
             Table 2: Summary of Taconite Pellet Production Rates
                                   Facility
                          CY2014 Capacity Factor [a]
          Taconite Pellet Production (million long tons per year) [b]
                                       
                                       
                                    CY2014
                                   Effective
  Minorca Mine
                                     89.6%
                                                                           2.51
                                                                            2.8
  Empire Mine
                                     31.3%
                                                                           2.63
                                                                            8.4
  Hibbing Taconite
                                     91.8%
                                                                           7.34
                                                                            8.0
  Northshore Mining
                                     82.6%
                                                                           5.12
                                                                            6.2
  Tilden Mine
                                     86.8%
                                                                           6.77
                                                                            7.8
  United Taconite
                                     89.3%
                                                                           4.82
                                                                            5.4
  Keetac
                                     85.8%
                                                                           5.15
                                                                            6.0
  Minntac
                                     85.7%
                                                                          13.71
                                                                           16.0
   [a]	The 2014 Capacity Factor is the ratio of actual pellet production during calendar year 2014 at a given facility to the effective pellet production rate for that facility.
   [b]	Note that 1 long ton = 1.12 ton = 2,240 pounds. CY2014 refers to the actual pellet production rate during calendar year 2014. Effective pellet production rates are the maximum annual production rates that can be achieved under normal operating conditions.
II.	Source Category HAP Emissions
HAP emissions from taconite iron ore processing facilities fall into the following pollutant categories: metals (HAP metals), polycyclic aromatic hydrocarbons (PAH), dioxins/furans (D/F), acid gases (i.e., hydrogen chloride (HCl) and hydrogen fluoride (HF)) and other combustion-related HAP (e.g., benzene, formaldehyde, etc.). Note that, although D/F emissions have never (to the best of our knowledge, after reasonable investigation) been measured at a taconite iron ore processing facility, these HAP are included since (1) it is reasonable to assume emissions of D/F from combustion of coal in the indurating furnaces, and (2) the TIOP facilities included D/F emission estimates (using AP-42 factors) in the Petition to Delist (see sections IV and V.1.c of this document, below). Table 3 summarizes the specific pollutants emitted from taconite iron ore processing plants corresponding to these HAP categories.
                 Table 3: Summary of HAP Emissions Categories
                                     Code
                                   Pollutant
                                     Code
                                   Pollutant
                                  HAP Metals
                                                                      7440-36-0
Antimony
                                                                      7439-92-1
Lead
                                                                      7440-38-2
Arsenic
                                                                      7439-96-5
Manganese
                                                                      1327-53-3
Arsenic Trioxide
                                                                            200
Elemental Gaseous Mercury
                                                                      7440-41-7
Beryllium
                                                                            201
Gaseous Divalent Mercury
                                                                      7440-43-9
Cadmium
                                                                            202
Particulate Divalent Mercury
                                                                     18540-29-9
Chromium (VI)
                                                                      7440-02-0
Nickel
                                                                     16065-83-1
Chromium III
                                                                     12035-72-2
Nickel Subsulfide
                                                                      7440-48-4
Cobalt
                                                                      7782-49-2
Selenium
                                  Acid Gases
                                                                      7647-01-0
Hydrogen Chloride
(Hydrochloric Acid)
                                                                      7664-39-3
Hydrogen Fluoride
(Hydrofluoric Acid)
                       Polycyclic Aromatic Hydrocarbons
                                                                        91-20-3
Naphthalene
                                                                       207-08-9
Benzo[k]Fluoranthene
                                                                        91-57-6
2-Methylnaphthalene
                                                                       192-97-2
Benzo[e]Pyrene
                                                                        83-32-9
Acenaphthene
                                                                        50-32-8
Benzo[a]Pyrene
                                                                       208-96-8
Acenaphthylene
                                                                       198-55-0
Perylene
                                                                        86-73-7
Fluorene
                                                                       193-39-5
Indeno[1,2,3-c,d]Pyrene
                                                                        85-01-8
Phenanthrene
                                                                        53-70-3
Dibenzo[a,h]Anthracene
                                                                       120-12-7
Anthracene
                                                                       191-24-2
Benzo[g,h,i,]Perylene
                                                                       206-44-0
Fluoranthene
                                                                        57-97-6
7,12-Dimethylbenz[a]Anthracene
                                                                       129-00-0
Pyrene
                                                                            102
Benzo[b+k]Fluoranthene
                                                                        56-55-3
Benzo[a]Anthracene
                                                                     56832-73-6
Benzofluoranthenes
                                                                       218-01-9
Chrysene
                                                                        92-52-4
Biphenyl
                                                                       205-99-2
Benzo[b]Fluoranthene
                                                                               

                              Dioxins and Furans
                                                                      1746-01-6
2,3,7,8-Tetrachlorodibenzo-p-Dioxin
                                                                     51207-31-9
2,3,7,8-Tetrachlorodibenzofuran
                                                                     36088-22-9
Total Pentachlorodibenzo-p-Dioxin
                                                                     30402-15-4
Total Pentachlorodibenzofuran
                                                                     34465-46-8
Hexachlorodibenzo-p-Dioxin
                                                                     55684-94-1
Total Hexachlorodibenzofuran
                                                                     37871-00-4
Total Heptachlorodibenzo-p-Dioxin
                                                                     38998-75-3
Total Heptachlorodibenzofuran
                                                                      3268-87-9
Octachlorodibenzo-p-Dioxin
                                                                     39001-02-0
Octachlorodibenzofuran
                         Other Combustion-Related HAP
                                                                        75-07-0
Acetaldehyde
                                                                       110-54-3
Hexane
                                                                        98-86-2
Acetophenone
                                                                        78-59-1
Isophorone
                                                                       107-02-8
Acrolein
                                                                        74-83-9
Methyl Bromide
                                                                        71-43-2
Benzene
                                                                        74-87-3
Methyl Chloride
                                                                       100-44-7
Benzyl Chloride
                                                                        71-55-6
Methyl Chloroform
                                                                       117-81-7
Bis(2-Ethylhexyl)Phthalate
                                                                        80-62-6
Methyl Methacrylate
                                                                        75-25-2
Bromoform
                                                                      1634-04-4
Methyl Tert-Butyl Ether
                                                                       106-99-0
1,3-Butadiene
                                                                        56-49-5
3-Methylcholanthrene
                                                                        86-74-8
Carbazole
                                                                      3697-24-3
5-Methylchrysene
                                                                        75-15-0
Carbon Disulfide
                                                                        75-09-2
Methylene Chloride
                                                                        56-23-5
Carbon Tetrachloride
                                                                        60-34-4
Methylhydrazine
                                                                      7782-50-5
Chlorine
                                                                       100-02-7
4-Nitrophenol
                                                                       532-27-4
2-Chloroacetophenone
                                                                        87-86-5
Pentachlorophenol
                                                                       108-90-7
Chlorobenzene
                                                                       108-95-2
Phenol
                                                                        67-66-3
Chloroform
                                                                      7723-14-0
Phosphorus
                                                                        91-58-7
2-Chloronaphthalene
                                                                       123-38-6
Propionaldehyde
                                                                        98-82-8
Cumene
                                                                        78-87-5
Propylene Dichloride
                                                                        57-12-5
Cyanide
                                                                       100-42-5
Styrene
                                                                       106-46-7
1,4-Dichlorobenzene
                                                                       127-18-4
Tetrachloroethylene
                                                                        77-78-1
Dimethyl Sulfate
                                                                       108-88-3
Toluene
                                                                        51-28-5
2,4-Dinitrophenol
                                                                        79-01-6
Trichloroethylene
                                                                       121-14-2
2,4-Dinitrotoluene
                                                                        88-06-2
2,4,6-Trichlorophenol
                                                                       100-41-4
Ethyl Benzene
                                                                       108-05-4
Vinyl Acetate
                                                                        75-00-3
Ethyl Chloride
                                                                        75-01-4
Vinyl Chloride
                                                                       106-93-4
Ethylene Dibromide
                                                                        95-47-6
o-Xylene
                                                                       107-06-2
Ethylene Dichloride
                                                                      1330-20-7
Xylenes (Mixture of o, m, and p Isomers)
                                                                        50-00-0
Formaldehyde
                                                                               

III.	Emission Process Groups
HAP are emitted from a variety of emission sources at taconite iron ore processing facilities which, for the purposes of this risk assessment, have been categorized into five emission process groups (EPG) as follows: ore crushing and handling operations (OCH), ore drying, pellet induration (PI), pellet handling operations (PH), and fugitive dust emissions control plan sources (FDECP). These EPG were described in the preamble for the initial NESHAP proposal for this source category (refer to 67 FR 77564 through 77565 and 77567 through 77570)[8] and are summarized as follows:
      Ore crushing and handling operations (OCH): "...begins where crude taconite iron ore is dumped into the primary crusher and ends where the unfired (green) pellets enter the indurating furnace." OCH operations exclude ore drying operations at the Tilden Mine facility and any operations wherein crushed ore is saturated with water (e.g., wet milling and magnetic separation). The OCH emission sources consist of operations to transport the raw ore and crush it down to about the size of coarse sand. Examples of OCH include ore crushers, ore screens, ore storage silos and bins, concentrate handling, and ore conveyors and transfer points.
      Ore drying: Refers to the two rotary-type, natural gas-fired ore dryers at the Tilden Mine facility. The ore dryers, which are made necessary due to the more fine-grained ore processed in this facility, further dry the raw, crushed ore prior to the agglomerating operations (i.e., prior to formation of the "green" pellets).
      Pellet induration (PI): "... begins at the point where the grate feed conveyor discharges green pellets onto the furnace traveling grate and ends where the hardened pellets exit the finished pellet cooler." PI refers to the pellet indurating furnaces, including the green pellet grate feeds and finished pellet discharges, which are utilized to indurate, or harden, the green pellets via oxidation from magnetite to hematite, at about 2,400 ℉. The indurating furnaces are one of two types: straight-grate type or grate-kiln type. These are typically natural gas-fired devices with another fuel (i.e., fuel oil, coal, coke and/or biomass) utilized as a backup fuel.
      Pellet handling operations (PH): "... begins at the indurating furnace discharge and ends where the finished pellets are stockpiled." The PH emission sources consist of operations to transport the finished pellets to stockpiles or storage bins and/or to load them for transport to customers. Examples of PH include pellet screens, conveyors, transfer points, storage silos and bins.
      Fugitive dust emissions control plan sources (FDECP): Refers to the emission sources that are subject to the fugitive dust control requirements of the NESHAP for taconite iron ore processing (see 40 CFR 63.9591). "All plants subject to the proposed rule would be required to prepare and implement a written fugitive dust emissions control plan. The plan would describe in detail the measures that will be put in place to control fugitive dust emissions from the following sources at a plant, as applicable: stockpiles, material transfer points, plant roadways, tailings basin, pellet loading areas and yard areas."
Any emission sources that do not fall into one of these five EPG are considered "non-category" emission sources. Some non-category sources emit HAP (e.g., boilers and space heaters) while others do not (e.g., wet processes and flux or binder handling or storage operations). Table 4 lists the emissions process groups and their corresponding pollutant category emissions.
        Table 4: Emission Process Groups and Associated HAP Categories
                                    EPG [a]
                           HAP Category(ies) Emitted

                                    Metals
                                      PAH
                                    D/F [b]
                                  Acid Gases
                                   Other [c]
Ore Crushing and Handling Operations (OCH)
                                       Y
                                       
                                       
                                       
                                       
Ore Drying
                                       Y
                                       Y
                                       Y
                                       
                                       Y
Pellet Indurating (PI)
                                       Y
                                       Y
                                       Y
                                       Y
                                       Y
Pellet Handling Operations (PH)
                                       Y
                                       
                                       
                                       
                                       
Fugitive Dust Emission Control Plan Sources (FDECP)
                                       Y
                                       
                                       
                                       
                                       
    [a]	SCCs associated with each EPG can be found in Section 11.23 of AP-42. [3]
    [b]	Although D/F emissions have never (to the best of our knowledge, after a reasonable amount of investigation) been measured at a TIOP facility, D/F are included in Table 4 since the TIOP facilities included D/F emission estimates (using AP-42 factors) in the Petition to Delist (see sections IV and V.1.c of this document, below.)
    [c]	Other = other combustion-related HAP (e.g., benzene, toluene, formaldehyde, etc.)
IV.	Emissions Data Collection
The two main sources of information utilized to estimate emissions from taconite iron ore processing facilities are the NEI data submitted for calendar year 2014 and the Petition to Delist. [9][,10,11] Also, taconite iron ore processing industry representatives provided us with additional information (e.g., recent stack emissions test data, EPG source clarifications, etc.), resulting in a more representative emissions dataset. [1][2][, 1][3]
Data on the numbers, types, dimensions and locations of the emission points for each facility were obtained from the NEI, state agencies (i.e., the Minnesota Pollution Control Agency and the Michigan Department of Environmental Quality), Google Earth(TM) and taconite iron ore processing industry staff.
V.	Development of Emission Rates for Modeling
 Estimated Actual HAP Emissions for Calendar Year 2014
Once the emissions data for the taconite iron ore processing source category were gathered, an emission process group (EPG) was assigned to each emission source. All six of the taconite facilities located in Minnesota entered HAP emissions data into NEI for each EPG. However, other than for lead, which was included, the two taconite facilities located in Michigan only entered HAP data into NEI for the boilers (which are non-category sources) at their facilities. Therefore, HAP emissions data (except for lead) for OCH, ore drying, PI and PH at the Michigan facilities were obtained from the Petition to Delist. Note that the Michigan facilities did not provide HAP emissions data for FDECP emissions sources in the NEI or the Petition to Delist. Therefore, estimates of HAP emissions from FDECP sources at the Michigan facilities were estimated as described in Section V.1.e of this document, below. The estimated HAP emissions from each EPG during CY2014 are summarized in Tables 5, 6, 12, 13 and 15, below, after making the following adjustments:
 The Petition to Delist cited HAP emission rates in units of grams per second. Those rates were converted to units of ton of HAP emitted per year as follows:
   Rate ton HAPyear = Rate gram HAPsecondx3,600 secondshourx8,760 hoursyearxpound453.6 gramsxton2,000 pounds
                   = Rate gram HAPsecondx34.76
 Emissions from the Michigan facilities were multiplied by the ratio of the 2014 pellet production rate (i.e., 2.63 million long tons for Empire and 6.77 million long tons for Tilden) to the pellet production rate cited in the Petition to Delist (i.e., 8.13 million long tons for Empire and 6.30 million long tons for Tilden) in order to scale the Petition to Delist HAP emissions to those that would be estimated for CY2014. That is, the HAP emissions cited for Empire in the Petition to Delist were multiplied by a factor of 0.32 (i.e., 2.63/8.13) and the HAP emissions cited for Tilden in the Petition to Delist were multiplied by a factor of 1.07 (i.e., 6.77/6.30) in order to reflect estimated expected emissions during CY2014.
 Ore Crushing and Handling Operations (OCH)
The OCH sources do not involve any fossil fuel combustion and handle only raw ore (i.e., before any pellet additives; typically dolomite, bentonite and limestone, have been incorporated). Therefore, the only HAP emissions expected from OCH sources are the metal HAP, summarized in Table 5, below.
                     Table 5: Summary of OCH HAP Emissions
                                      HAP
                       HAP Emission Rate (tons per year)
                                       
                                    Minorca
                                    Empire
                               Hibbing Taconite
                                  North-shore
                                    Tilden
                                United Taconite
                                    Keetac
                                    Minntac
Antimony
                                   2.10E-04
                                       
                                   1.65E-04
                                   5.68E-05
                                   7.29E-05
                                   4.78E-04
                                   1.15E-04
                                   9.15E-04
Arsenic
                                   3.54E-04
                                   1.55E-04
                                   2.60E-03
                                   1.53E-04
                                   2.74E-04
                                   5.97E-04
                                   2.23E-04
                                   2.64E-03
Beryllium
                                   1.40E-05
                                       
                                   2.36E-04
                                   4.36E-05
                                   1.83E-05
                                   1.99E-04
                                   5.01E-05
                                   3.90E-04
Cadmium
                                   1.40E-06
                                       
                                   5.90E-06
                                   1.13E-06
                                   7.29E-06
                                   1.99E-05
                                   3.27E-05
                                   1.13E-04
Chromium (VI)
                                   5.26E-07
                                       
                                   2.93E-04
                                   4.26E-05
                                       
                                   2.95E-05
                                   6.52E-06
                                   2.39E-04
Chromium III
                                   1.70E-05
                                   1.59E-03
                                   9.48E-03
                                   1.38E-03
                                   2.83E-03
                                   9.55E-04
                                   2.11E-04
                                   7.71E-03
Cobalt
                                   1.21E-04
                                   2.24E-04
                                   1.20E-03
                                   4.07E-04
                                   5.58E-04
                                   1.91E-03
                                   2.15E-04
                                   2.68E-03
Lead
                                       
                                   2.47E-04
                                       
                                       
                                   4.39E-04
                                   7.96E-04
                                       
                                       
Manganese
                                   8.24E-02
                                   2.51E-02
                                   6.13E-01
                                   6.50E-02
                                   4.46E-02
                                   1.55E-01
                                   1.07E-01
                                   7.46E-01
Mercury (202)
                                   1.93E-07
                                   1.03E-07
                                   2.16E-06
                                   1.34E-07
                                   1.83E-07
                                   3.98E-05
                                   2.44E-08
                                   5.13E-05
Nickel
                                   2.63E-05
                                   5.66E-04
                                   8.45E-04
                                   2.60E-04
                                   1.00E-03
                                   5.17E-04
                                   1.19E-04
                                   2.04E-03
Selenium
                                   1.75E-04
                                   1.03E-04
                                   5.90E-05
                                   1.16E-05
                                   1.83E-04
                                   1.99E-04
                                   3.27E-04
                                   1.09E-03
 Ore Drying
Only the Tilden Mine facility utilizes ore dryers. These dryers handle only raw ore, but do include fossil fuel combustion (these dryers mainly burn natural gas but can utilize oil as a backup fuel). Therefore, the HAP emissions expected from ore drying include metal HAP, PAH, other combustion-related HAP, and D/F (if fuel oil is utilized in the dryers). The metal HAP emissions are summarized in Table 6; below, however, the combustion-related HAP (e.g., PAH, D/F, benzene, etc.) are accounted for in section V.1.c of this document, below, in order to apply the gap-filling measures described in that section to the combustion-related ore drying HAP emissions.
                    Table 6: Summary of Ore Drying HAP Emissions
                                      HAP
                                 Emission Rate
                            (tons emitted per year)
                                      HAP
                                 Emission Rate
                            (tons emitted per year)
Antimony
                                   6.51E-03
 Lead
                                   1.10E-02
Arsenic
                                   2.68E-05
 Manganese
                                   3.12E-01
Arsenic Trioxide
                                   5.30E-08
 Elemental Gaseous Mercury
                                   7.01E-04
Beryllium
                                   1.36E-04
 Gaseous Divalent Mercury
                                   5.03E-05
Cadmium
                                   2.73E-03
 Nickel
                                   3.46E-02
Chromium (VI)
                                   4.46E-04
 Nickel Subsulfide
                                   2.08E-03
Chromium III
                                   2.24E-02
 Selenium
                                   1.50E-03
Cobalt
                                   4.76E-03
 
                                       
Note:	The PI speciation profiles (i.e., for indurating furnaces) for arsenic, mercury, and nickel emissions discussed in section V.1.c of this document were applied in Table 6.
 Pellet Induration (PI)
Pellet induration, or hardening, is conducted in the indurating furnaces. Once indurated, the pellets are suitable to handle, transfer, stockpile and/or load out for shipment to customers. The unfired, or "green", pellets are formed via agglomeration processes in which the raw, crushed ore is mixed with binders (e.g., bentonite) and flux additives (e.g., limestone and dolomite  -  if fluxed pellets, as opposed to standard pellets, are being produced). HAP emissions from PI sources result directly from the combustion of fossil fuels, from the entrainment of metal HAP from pellet fragments, and from the effect that combustion has on the green pellets. For example, the pellet additives contain fluorides and chlorides which are emitted from the indurating furnaces as acid gases (i.e., HCl and HF). Therefore, we expect PI sources to emit metal HAP, PAH, D/F, acid gases, and other combustion-related HAP.
The PI HAP emissions cited in the 2014 NEI (for the MN facilities, after adjustments to reflect emissions data and other information provided by industry [1][2][,1][3]) and in the Petition to Delist (for the MI facilities, after adjustment from units of grams per second to units of tons per year and adjustment to the 2014 production rates, as discussed above) are provided in Table 7. Note that the facilities are grouped in Table 7 according to the fuels utilized during 2014. Specifically, the Minorca, Hibbing Taconite, and Northshore facilities utilized only natural gas during 2014; the Empire, Tilden, United Taconite, and Keetac facilities utilized natural gas and coal during 2014; and the Minntac facility utilized natural gas, coal, oil, and biomass (unadulterated wood) during 2014. Further, the speciated HAP are grouped in Table 7 as: metal HAP, acid gases, PAH, D/F, and other combustion-related HAP.
        Table 7: Summary of NEI and Petition to Delist PI HAP Emissions
                                  HAP Emitted
                         HAP Emissions (tons per year)
                                       
                                    Minorca
                               Hibbing Taconite
                                  North-shore
                                    Empire
                                    Tilden
                                United Taconite
                                    Keetac
                                    Minntac
                                  HAP Metals
Antimony
                                   1.97E-02
                                   2.19E-03
                                   5.14E-04
                                   1.64E-03
                                   2.29E-02
                                   4.25E-03
                                   6.50E-03
                                   1.75E-01
Arsenic
                                   1.80E-02
                                   3.93E-01
                                   2.93E-02
                                   1.11E-05
                                   1.25E-04
                                   5.66E-01
                                   2.16E-01
                                   2.42E-01
Arsenic Trioxide
                                       
                                       
                                       
                                   2.20E-08
                                   2.47E-07
                                       
                                       
                                       
Beryllium
                                   9.88E-04
                                   5.20E-03
                                   3.00E-03
                                   1.64E-03
                                   3.42E-03
                                   8.85E-04
                                   1.39E-03
                                   1.66E-02
Cadmium
                                   3.97E-03
                                   5.15E-03
                                   8.48E-03
                                   5.12E-03
                                   5.36E-02
                                   4.49E-03
                                   6.47E-03
                                   3.52E-02
Chromium (VI)
                                   4.71E-04
                                   6.74E-04
                                   9.90E-03
                                   5.31E-04
                                   4.24E-03
                                   4.40E-03
                                   3.88E-03
                                   4.87E-02
Chromium III
                                   1.13E-02
                                   1.62E-02
                                   2.38E-01
                                   2.66E-02
                                   2.11E-01
                                   4.64E-02
                                   8.04E-02
                                   8.32E-01
Cobalt
                                   9.89E-04
                                   2.40E-02
                                   7.82E-03
                                   4.75E-02
                                   1.10E-02
                                   3.98E-03
                                   6.84E-03
                                   1.85E-02
Lead
                                   1.41E-02
                                   8.00E-02
                                   2.28E-01
                                   1.50E-01
                                   2.97E-01
                                   7.28E-02
                                   1.37E-01
                                   6.87E-01
Manganese
                                   1.61E-01
                                   4.33E-01
                                   4.49E-01
                                   1.80E-01
                                   8.22E-01
                                   1.34E-01
                                   1.78E-01
                                   1.43E+00
Mercury
                                   3.15E-02
                                   7.37E-02
                                   2.85E-03
                                   2.04E-02
                                   4.40E-02
                                   8.92E-02
                                   5.16E-02
                                   8.23E-02
Elemental Gaseous Mercury
                                       
                                       
                                       
                                   1.90E-02
                                   4.09E-02
                                       
                                       
                                       
Gaseous Divalent Mercury
                                       
                                       
                                       
                                   1.43E-03
                                   3.08E-03
                                       
                                       
                                       
Nickel
                                   3.02E-02
                                   3.02E-02
                                   5.43E-02
                                   1.41E-01
                                   2.41E-01
                                   1.44E-01
                                   2.58E-02
                                   7.51E-01
Nickel Subsulfide
                                       
                                       
                                       
                                   8.48E-03
                                   1.45E-02
                                       
                                       
                                       
Selenium
                                   1.14E-02
                                   2.21E-02
                                   7.73E-02
                                   2.14E-02
                                   2.79E-01
                                   4.86E-02
                                   4.38E-03
                                   1.77E-01
                                  Acid Gases
Hydrochloric Acid
                                   2.63E+01
                                   6.56E+00
                                   1.75E+01
                                   7.46E+01
                                   2.60E+02
                                   2.47E+01
                                   3.89E-01
                                   1.16E+02
Hydrogen Fluoride
                                   3.75E+00
                                   8.91E+00
                                   5.30E+00
                                   8.50E+00
                                   3.56E+01
                                   2.70E+01
                                   4.54E-02
                                   8.94E+01
                       Polycyclic Aromatic Hydrocarbons
Naphthalene
                                       
                                   7.37E-04
                                   8.68E-04
                                       
                                       
                                   7.35E-04
                                   7.48E-04
                                   5.30E-02
2-Methylnaphthalene
                                       
                                   2.90E-05
                                   3.42E-05
                                       
                                       
                                   1.57E-05
                                   2.73E-05
                                   1.88E-04
Acenaphthene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                   1.43E-05
                                   4.19E-06
                                   4.86E-04
Acenaphthylene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                       
                                   3.10E-06
                                   2.59E-03
Fluorene
                                       
                                   3.39E-06
                                   3.98E-06
                                       
                                       
                                   2.53E-05
                                   7.01E-06
                                   1.78E-03
Phenanthrene
                                       
                                   2.06E-05
                                   2.42E-05
                                       
                                       
                                   8.08E-05
                                   3.07E-05
                                   3.73E-03
Anthracene
                                       
                                   2.90E-06
                                   3.42E-06
                                       
                                       
                                   6.99E-06
                                   3.61E-06
                                   1.56E-03
Fluoranthene
                                       
                                   3.63E-06
                                   4.27E-06
                                       
                                       
                                   2.03E-05
                                   6.40E-06
                                   8.51E-04
Pyrene
                                       
                                   6.05E-06
                                   7.12E-06
                                       
                                       
                                   1.18E-05
                                   1.39E-06
                                   1.94E-03
Benz[a]Anthracene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                   3.24E-06
                                   3.37E-07
                                   4.28E-05
Chrysene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                   3.76E-06
                                   4.21E-07
                                   2.92E-05
Benzo[b]Fluoranthene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                   1.18E-06
                                   2.05E-10
                                   5.95E-05
Benzo[k]Fluoranthene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                   1.18E-06
                                   2.05E-10
                                   2.65E-05
Benzo[e]Pyrene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.34E-06
Benzo[a]Pyrene
                                       
                                   1.45E-06
                                   1.71E-06
                                       
                                       
                                   1.77E-06
                                   1.60E-07
                                   1.35E-03
Perylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.68E-07
Indeno[1,2,3-c,d]Pyrene
                                       
                                   2.18E-06
                                   2.56E-06
                                       
                                       
                                   2.75E-06
                                   2.57E-07
                                   5.38E-05
Dibenzo[a,h]Anthracene
                                       
                                   1.45E-06
                                   1.71E-06
                                       
                                       
                                   7.85E-07
                                   1.36E-10
                                   9.97E-06
Benzo[g,h,i,]Perylene
                                       
                                   1.45E-06
                                   1.71E-06
                                       
                                       
                                   1.48E-06
                                   1.14E-07
                                   5.37E-05
7,12-Dimethylbenz[a]Anthracene
                                       
                                   1.93E-05
                                   2.58E-05
                                       
                                       
                                   1.05E-05
                                   1.82E-09
                                   7.01E-05
Benzofluoranthenes
                                       
                                       
                                       
                                       
                                       
                                   2.84E-06
                                   4.62E-07
                                   1.84E-06
Biphenyl
                                       
                                       
                                       
                                       
                                       
                                   4.39E-05
                                   7.15E-06
                                   2.85E-05
                              Dioxins and Furans
Dioxin/Furan (TEQ)
                                       
                                       
                                       
                                   1.97E-08
                                   6.69E-08
                                       
                                       
                                       
                         Other Combustion-Related HAP
Acetaldehyde
                                       
                                       
                                       
                                       
                                       
                                   1.47E-02
                                   2.40E-03
                                   7.67E-01
Acetophenone
                                       
                                       
                                       
                                       
                                       
                                   3.87E-04
                                   6.31E-05
                                   2.54E-04
Acrolein
                                       
                                       
                                       
                                       
                                       
                                   7.49E-03
                                   1.22E-03
                                   3.66E+00
Benzene
                                       
                                   4.47E-01
                                   1.46E+00
                                       
                                       
                                   2.85E+00
                                   4.86E+00
                                   1.03E+01
Benzyl Chloride
                                       
                                       
                                       
                                       
                                       
                                   1.81E-02
                                   2.94E-03
                                   1.17E-02
Bis(2-Ethylhexyl)Phthalate
                                       
                                       
                                       
                                       
                                       
                                   1.88E-03
                                   3.07E-04
                                   1.25E-03
Bromoform
                                       
                                       
                                       
                                       
                                       
                                   1.01E-03
                                   1.64E-04
                                   6.53E-04
1,3-Butadiene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.24E-05
Carbon Disulfide
                                       
                                       
                                       
                                       
                                       
                                   3.36E-03
                                   5.47E-04
                                   2.18E-03
Carbon Tetrachloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   4.11E-02
Chlorine
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   7.21E-01
2-Chloroacetophenone
                                       
                                       
                                       
                                       
                                       
                                   1.81E-04
                                   2.94E-05
                                   1.17E-04
Chlorobenzene
                                       
                                       
                                       
                                       
                                       
                                   5.68E-04
                                   9.25E-05
                                   3.05E-02
Chloroform
                                       
                                       
                                       
                                       
                                       
                                   1.52E-03
                                   2.48E-04
                                   2.65E-02
2-Chloronaphthalene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.19E-06
Cumene
                                       
                                       
                                       
                                       
                                       
                                   1.37E-04
                                   2.23E-05
                                   8.87E-05
Cyanide
                                       
                                       
                                       
                                       
                                       
                                   6.45E-02
                                   1.05E-02
                                   4.19E-02
Dimethyl Sulfate
                                       
                                       
                                       
                                       
                                       
                                   1.24E-03
                                   2.02E-04
                                   8.04E-04
2,4-Dinitrophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.64E-04
2,4-Dinitrotoluene
                                       
                                       
                                       
                                       
                                       
                                   7.23E-06
                                   1.18E-06
                                   4.69E-06
Ethyl Benzene
                                       
                                       
                                       
                                       
                                       
                                   2.43E-03
                                   3.95E-04
                                   2.99E-02
Ethyl Chloride
                                       
                                       
                                       
                                       
                                       
                                   1.08E-03
                                   1.77E-04
                                   7.03E-04
Ethylene Dibromide
                                       
                                       
                                       
                                       
                                       
                                   3.10E-05
                                   5.04E-06
                                   5.02E-02
Ethylene Dichloride
                                       
                                       
                                       
                                       
                                       
                                   1.03E-03
                                   1.68E-04
                                   2.71E-02
Formaldehyde
                                       
                                   1.33E+00
                                   1.78E+01
                                   1.06E+00
                                   1.01E+01
                                   3.00E+01
                                   1.30E+00
                                   1.09E+02
Hexane
                                       
                                   1.36E-01
                                   1.58E+00
                                       
                                       
                                   2.85E+00
                                   1.46E+00
                                   1.03E+01
Isophorone
                                       
                                       
                                       
                                       
                                       
                                   1.50E-02
                                   2.44E-03
                                   9.71E-03
Methyl Bromide
                                       
                                       
                                       
                                       
                                       
                                   4.13E-03
                                   6.73E-04
                                   1.64E-02
Methyl Chloride
                                       
                                       
                                       
                                       
                                       
                                   1.37E-02
                                   2.23E-03
                                   2.99E-02
Methyl Chloroform
                                       
                                       
                                       
                                       
                                       
                                   5.16E-04
                                   8.41E-05
                                   2.86E-02
Methyl Methacrylate
                                       
                                       
                                       
                                       
                                       
                                   5.16E-04
                                   8.41E-05
                                   3.35E-04
Methyl Tert-Butyl Ether
                                       
                                       
                                       
                                       
                                       
                                   9.03E-04
                                   1.47E-04
                                   5.86E-04
3-Methylcholoanthrene
                                       
                                   2.18E-06
                                   5.12E-08
                                       
                                       
                                   1.18E-06
                                   2.05E-06
                                   3.95E-07
5-Methylchrysene
                                       
                                       
                                       
                                       
                                       
                                   5.68E-07
                                   9.25E-08
                                   3.68E-07
Methylene Chloride
                                       
                                       
                                       
                                       
                                       
                                   7.49E-03
                                   1.22E-03
                                   2.70E-01
Methylhydrazine
                                       
                                       
                                       
                                       
                                       
                                   4.39E-03
                                   7.15E-04
                                   2.85E-03
4-Nitrophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.00E-04
Pentachlorophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   4.65E-05
Phenol
                                       
                                       
                                       
                                       
                                       
                                   4.13E-04
                                   6.73E-05
                                   4.68E-02
Phosphorus
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.46E-02
Propionaldehyde
                                       
                                       
                                       
                                       
                                       
                                   9.81E-03
                                   1.60E-03
                                   6.20E-02
Propylene Dichloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   3.01E-02
Styrene
                                       
                                       
                                       
                                       
                                       
                                   6.45E-04
                                   1.05E-04
                                   1.73E+00
Tetrachloroethylene
                                       
                                       
                                       
                                       
                                       
                                   1.11E-03
                                   1.81E-04
                                   3.54E-02
Toluene
                                       
                                   2.30E-01
                                   1.46E+00
                                       
                                       
                                   3.17E+00
                                   2.06E+00
                                   1.14E+01
Trichloroethylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.74E-02
Vinyl Acetate
                                       
                                       
                                       
                                       
                                       
                                   1.96E-04
                                   3.20E-05
                                   1.27E-04
Vinyl Chloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.64E-02
o-Xylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.28E-02
Xylenes (Mixed and Isomers)
                                       
                                       
                                       
                                       
                                       
                                   9.55E-04
                                   1.56E-04
                                   6.19E-04
A quick review of Table 7 reveals that the taconite processing facilities reported different combustion HAP emissions, even when burning the same fuel(s). For example, even though the Minorca, Hibbing Taconite, and Northshore facilities all burned natural gas, only the Hibbing Taconite and Northshore facilities reported emissions of formaldehyde (that is, a HAP emission which would be expected from the combustion of natural gas) from PI sources. Therefore, in order to develop a more complete risk model input file, certain gap-filling steps were taken, as described below.
Acid Gases: Acid gas emissions would result from combustion gases reacting with the chlorides and fluorides found in the pellet additives and would depend heavily on the specific pellet additives utilized, which is site-specific. The taconite iron ore processing facilities have conducted emissions testing for these HAP and developed site-specific emissions factors, which are used in NEI and the Petition to Delist. Therefore, no gap-filling steps were applied to these emissions.
Metal HAP: Most metal HAP emissions would result from volatilized and/or entrained pellet metal contaminants (e.g., manganese, arsenic, nickel). These HAP emissions would depend heavily on the composition of the ore, which is site-specific. Again, the taconite iron ore processing facilities have conducted emissions testing for these HAP and developed site-specific emissions factors, which are used in the NEI and the Petition to Delist. Therefore, no gap-filling steps were applied to these emissions except that arsenic (As), chromium (Cr) and nickel (Ni) emissions from indurating furnaces were speciated based on emissions tests conducted at the subject facilities (see section 2.4.4 of the Petition to Delist and associated appendices of that document [14][,][15,16,][1][7]) as follows:
         0.198 percent of total arsenic is in the trivalent state; and
         6 percent of total nickel is nickel subsulfide.
Note that, although the tests indicated that 93.3 percent of gaseous mercury is in the elemental form and 6.7 percent of gaseous mercury is in the divalent state, the default speciation for this industry sector (i.e., 93 percent elemental and 7 percent divalent) was utilized since it is the more protective scenario. Also, as mentioned above, some metal HAP emissions were adjusted to reflect additional information (e.g., recent stack testing data for certain metal HAP, improvements in PM emissions controls installed on indurating furnaces, etc.). [1][2], [1][3]
D/F, PAH, and other combustion-related HAP: These HAP emissions result from combustion of fossil fuels in the indurating furnaces. The EPA is not aware of emissions factors developed for these pollutants specifically for taconite iron ore indurating furnaces. Therefore, we utilized the emissions factors for external combustion found in the most recent relevant sections of the Fifth Edition Compilation of Air Pollutant Emissions Factors (AP-42), Volume 1: Stationary Point and Area Sources, Chapter 1: External Combustion Sources for the fuels burned in the indurating furnaces. The relevant sections include 1.1 Bituminous and Subbituminous Coal Combustion,[1][8] 1.3 Fuel Oil Combustion,[1][9] 1.4 Natural Gas Combustion,[20] and 1.6 Wood Residue Combustion In Boilers.[21] These combustion emissions factors are summarized in Table 8, below.
Note that, for conservatism, whenever AP-42 listed an emissions factor as "less than" a cited value, the cited value was used in the modeling file. For example, AP-42 cites an emissions factor of "<1.8E-06 (lb/10[6] scf)" for chrysene emissions from the combustion of natural gas. Therefore, emissions of 1.8E-06 (lb/10[6] scf) were assumed for chrysene from combustion of natural gas.
            Table 8: Summary of AP-42 Combustion Emissions Factors
                                  HAP Emitted
                                  Natural Gas
                               (lb/10[6] ft[3])
                                   Fuel Oil
                              (lb/10[3] gallons)
                                     Coal
                                   (lb/ton)
                                 Wood Residue
                                (lb/10[6] Btu)
                       Polycyclic Aromatic Hydrocarbons
Naphthalene
                                    6.1E-04
                                   1.13E-03
                                    1.3E-05
                                    9.7E-05
2-Methylnaphthalene
                                    2.4E-05
                                       
                                       
                                    1.6E-07
Acenaphthene
                                    1.8E-06
                                   2.11E-05
                                    5.1E-07
                                    9.1E-07
Acenaphthylene
                                    1.8E-06
                                   2.53E-07
                                    2.5E-07
                                    5.0E-06
Fluorene
                                    2.8E-06
                                   4.47E-06
                                    9.1E-07
                                    3.4E-06
Phenanthrene
                                    1.7E-05
                                   1.05E-05
                                    2.7E-06
                                    7.0E-06
Anthracene
                                    2.4E-06
                                   1.22E-06
                                    2.1E-07
                                    3.0E-06
Fluoranthene
                                    3.0E-06
                                   4.84E-06
                                    7.1E-07
                                    1.6E-06
Pyrene
                                    5.0E-06
                                   4.25E-06
                                    3.3E-07
                                    3.7E-06
Benz[a]Anthracene
                                    1.8E-06
                                   4.01E-06
                                    8.0E-08
                                    6.5E-08
Chrysene
                                    1.8E-06
                                   2.38E-06
                                    1.0E-07
                                    3.8E-08
Benzo[b]Fluoranthene
                                    1.8E-06
                                       
                                       
                                    1.0E-07
Benzo[k]Fluoranthene
                                    1.8E-06
                                       
                                       
                                    3.6E-08
Benzo[e]Pyrene
                                       
                                       
                                       
                                    2.6E-09
Benzo[a]Pyrene
                                    1.2E-06
                                       
                                    3.8E-08
                                    2.6E-06
Perylene
                                       
                                       
                                       
                                    5.2E-10
Indeno[1,2,3-c,d]Pyrene
                                    1.8E-06
                                   2.14E-06
                                    6.1E-08
                                    8.7E-08
Dibenzo[a,h]Anthracene
                                    1.2E-06
                                   1.67E-06
                                       
                                    9.1E-09
Benzo[g,h,i,]Perylene
                                    1.2E-06
                                   2.26E-06
                                    2.7E-08
                                    9.3E-08
7,12-Dimethylbenz[a]Anthracene
                                    1.6E-05
                                       
                                       
                                       
Benzo[b,k]Fluoranthene
                                       
                                   1.48E-06
                                       
                                       
Benzo[j,k]Fluoranthene
                                       
                                       
                                       
                                    1.6E-07
Benzo[b,j,k]Fluoranthene
                                       
                                       
                                    1.1E-07
                                       
Biphenyl
                                       
                                       
                                    1.7E-06
                                       
                            Dioxins and Furans [a]
2,3,7,8-TCDD
                                       
                                       
                                   1.43E-11
                                       
Total PeCDD
                                       
                                       
                                   4.47E-11
                                       
Total HxCDD
                                       
                                       
                                   2.87E-11
                                       
Total HpCDD
                                       
                                       
                                   8.34E-11
                                       
Total OCDD
                                       
                                   3.10E-09
                                   4.16E-10
                                       
2,3,7,8-TCDF
                                       
                                       
                                   5.10E-11
                                       
Total PeCDF
                                       
                                       
                                   3.53E-10
                                       
Total HxCDF
                                       
                                       
                                   1.92E-10
                                       
Total HpCDF
                                       
                                       
                                   7.68E-11
                                       
Total OCDF
                                       
                                       
                                   6.63E-11
                                       
                         Other Combustion-Related HAP
Acetaldehyde
                                       
                                       
                                    5.7E-04
                                    8.3E-04
Acetophenone
                                       
                                       
                                    1.5E-05
                                    3.2E-09
Acrolein
                                       
                                       
                                    2.9E-04
                                    4.0E-03
Benzene
                                    2.1E-03
                                   2.14E-04
                                    1.3E-03
                                    4.2E-03
Benzyl Chloride
                                       
                                       
                                    7.0E-04
                                       
Bis(2-Ethylhexyl)Phthalate
                                       
                                       
                                    7.3E-05
                                    4.7E-08
Bromoform
                                       
                                       
                                    3.9E-05
                                       
Carbazole
                                       
                                       
                                       
                                    1.8E-06
Carbon Disulfide
                                       
                                       
                                    1.3E-04
                                       
Carbon Tetrachloride
                                       
                                       
                                       
                                    4.5E-05
Chlorine
                                       
                                       
                                       
                                    7.9E-04
2-Chloroacetophenone
                                       
                                       
                                    7.0E-06
                                       
Chlorobenzene
                                       
                                       
                                    2.2E-05
                                    3.3E-05
Chloroform
                                       
                                       
                                    5.9E-05
                                    2.8E-05
2-Chloronaphthalene
                                       
                                       
                                       
                                    2.4E-09
Cumene
                                       
                                       
                                    5.3E-06
                                       
Cyanide
                                       
                                       
                                    2.5E-03
                                       
1,4-Dichlorobenzene
                                    1.2E-03
                                       
                                       
                                       
Dimethyl Sulfate
                                       
                                       
                                    4.8E-05
                                       
2,4-Dinitrophenol
                                       
                                       
                                       
                                    1.8E-07
2,4-Dinitrotoluene
                                       
                                       
                                    2.8E-07
                                       
Ethyl Benzene
                                       
                                   6.36E-05
                                    9.4E-05
                                    3.1E-05
Ethyl Chloride
                                       
                                       
                                    4.2E-05
                                       
Ethylene Dibromide [a]
                                       
                                       
                                    1.2E-06
                                    5.5E-05
Ethylene Dichloride [a]
                                       
                                       
                                    4.0E-05
                                    2.9E-05
Formaldehyde
                                    7.5E-02
                                   3.30E-02
                                    2.4E-04
                                    4.4E-03
Hexane
                                    1.8E+00
                                       
                                    6.7E-05
                                       
Isophorone
                                       
                                       
                                    5.8E-04
                                       
Methyl Bromide [a]
                                       
                                       
                                    1.6E-04
                                    1.5E-05
Methyl Chloride [a]
                                       
                                       
                                    5.3E-04
                                    2.3E-05
Methyl Chloroform [b]
                                       
                                   2.36E-04
                                    2.0E-05
                                    3.1E-05
Methyl Methacrylate
                                       
                                       
                                    2.0E-05
                                       
Methyl Tert-Butyl Ether
                                       
                                       
                                    3.5E-05
                                       
3-Methylcholanthrene [c]
                                    1.8E-06
                                       
                                       
                                       
5-Methylchrysene
                                       
                                       
                                    2.2E-08
                                       
Methylene Chloride [a]
                                       
                                       
                                    2.9E-04
                                    2.9E-04
Methylhydrazine
                                       
                                       
                                    1.7E-04
                                       
4-Nitrophenol
                                       
                                       
                                       
                                    1.1E-07
Pentachlorophenol
                                       
                                       
                                       
                                    5.1E-08
Phenol
                                       
                                       
                                    1.6E-05
                                    5.1E-05
Phosphorus
                                       
                                       
                                       
                                    2.7E-05
Propionaldehyde
                                       
                                       
                                    3.8E-04
                                    6.1E-05
Propylene Dichloride
                                       
                                       
                                       
                                    3.3E-05
Styrene
                                       
                                       
                                    2.5E-05
                                    1.9E-03
Tetrachloroethylene [a]
                                       
                                       
                                    4.3E-05
                                    3.8E-05
Toluene
                                    3.4E-03
                                   6.20E-03
                                    2.4E-04
                                    9.2E-04
Trichloroethylene [b]
                                       
                                       
                                       
                                    3.0E-05
2,4,6-Trichlorophenol
                                       
                                       
                                       
                                    2.2E-08
Vinyl Acetate
                                       
                                       
                                    7.6E-06
                                       
Vinyl Chloride
                                       
                                       
                                       
                                    1.8E-05
o-Xylene
                                       
                                   1.09E-04
                                       
                                    2.5E-05
Xylenes
                                       
                                       
                                    3.7E-05
                                       
Note:	HAP names are listed as they were presented in the associated AP-42 sections, except that:
      [a]	When the names used for a given HAP varied between the different AP-42 sections, the name used in Section 1.1 (i.e., for coal combustion) was used in Table 8.
      [b]	For these HAP, the name used in the modeling file database was used in Table 8.
      [c]	AP-42 Section 1.4 (i.e., for natural gas combustion) includes a typographical error whereby this HAP was referred to as "3-Methylchloranthrene" instead of "3-Methylcholanthrene."
Since these HAP emissions factors are provided in terms of mass of HAP emitted per quantity of fuel combusted, the next step is to gather information on the types and quantities of fuel(s) burned in the indurating furnaces of each facility during CY2014. Fuel use data for the facilities located in Michigan during CY2014 were not readily available and were, therefore, estimated as follows:
 First, the average energy use rate (MMBtu per million long tons of pellets produced) was calculated for the facilities for which the information was available (i.e., Northshore, Hibbing Taconite, Keetac, and United [22]), as summarized in Table 9.
                        Table 9: Energy Use Rates for CY2014
                                   Facility
                                  Heat Input
                                    (MMBtu)
                                  Production
                              (million long tons)
                                Energy Use Rate
                           (MMBtu/million long ton)
Northshore
                                   2.95 E06
                                     5.12
                                   5.76 E05
Hibbing Taconite
                                   2.47 E06
                                     7.34
                                   3.36 E05
Keetac
                                   2.51 E06
                                     5.15
                                   4.88 E05
United Taconite
                                   1.40 E06
                                     4.82
                                   2.89 E05
      Notes:	MMBtu = million British thermal units	Average:	4.22 E05
      	Long ton = 1.12 ton = 2,240 pounds
 Second, a facility heat input rate was calculated based on the level of pellet production at each Michigan facility during CY2014, as follows:
      Empire: 2.63million long tonsyearx4.22 E05MMBtumillion long ton=1.11 E06MMBtuyear
      Tilden:   6.77million long tonsyearx4.22 E05MMBtumillion long ton=2.86 E06MMBtuyear
 Third, we gathered data on fuel heat values and how many tons of pellets were produced while burning each type of fuel (as cited in the MAERS) during CY2014:
      Empire:	          726 tons while burning coal;	2,940,989 tons while burning natural gas
      Tilden:	1,703,667 tons while burning coal;	5,877,250 tons while burning natural gas
      Empire/Tilden:	       8,750 Btu per pound of coal;	          903 Btu per cubic foot natural gas
 Finally, we estimated the amount of each fuel used in the indurating furnaces (i.e., coal and natural gas) by assuming indurating furnace fuel use proportionate to the tons of pellets produced while burning each fuel in the indurating furnaces, as follows:
      Empire coal:1.11 E06MMBtuyearx726 tons burning coal726+2,940,989 total tonsxpound coal8,750 Btuxton2,000 poundxE06 BtuMMBtu
               = 16 tons of coal
      Empire NG:1.11 E06MMBtuyearx2,940,989 tons burning NG726+2,940,989 total tonsxft3 NG903 BtuxE06 BtuMMBtu
               = 1,229 million cubic feet of natural gas
      Tilden coal:2.86 E06MMBtuyearx1,703,667 tons burning coal1,703,667+5,877,250 total tonsxpound coal8,750 Btuxton2,000 poundxE06 BtuMMBtu
               = 36,727 tons of coal
      Tilden NG:2.86 E06MMBtuyearx5,877,250 tons burning NG1,703,667+5,877,250 total tonsxft3 NG903 BtuxE06 BtuMMBtu
               = 2,455 million cubic feet of natural gas
The CY2014 fuel use data for facilities located in Minnesota were obtained from the MPCA (see the April 19, 2017 email from Anne Jackson[22]) and industry representatives (refer to the November 3, 2017 email from Rich Zavoda[23] and additional information provided by industry representatives[1][2][, 1][3]). The fuel use for all facilities during CY2014 are summarized in Table 10, below.
     Table 10: CY2014 Fuel Use at Taconite Iron Ore Processing Facilities
                                     Fuel
                                    Minorca
                                    Empire
                               Hibbing Taconite
                                  North-shore
                                    Tilden
                                United Taconite
                                    Keetac
                                    Minntac
Coal/Coke (tons/year)
                                       
                                                                             16
                                       
                                       
                                                                         36,727
                                                                         51,625
                                     8,408
                                                                         33,481
Natural Gas (million cubic feet/year) [a]
                                     1,494
                                                                          1,229
                                     2,418
                                     2,846
                                                                          3,079
                                                                          1,308
                                     2,274
                                                                          8,758
Fuel Oil (gallons/year)
                                       
                                                                               
                                       
                                       
                                                                               
                                                                               
                                       
                                                                         20,000
Wood (tons/year)
                                       
                                                                               
                                       
                                       
                                                                               
                                                                               
                                       
                                                                         64,499
Notes:	[a]	For the Tilden facility, the natural gas value includes the amount of fuel that was consumed in the dryers during CY2014 (i.e., 116,000,000 ft[3] in Dryer 1 and 508,000,000 ft[3] in Dryer 2  -  see pages 64 and 70 of the 2014 MAERS report for Tilden[6]).
	Note that information on the use of natural gas at the Minorca facility was provided by industry personnel in units of millions of British thermal units per year (MMBtu/year). This was converted to units of million cubic feet per year by assuming a heat value of 1,020 Btu per cubic foot for natural gas; the value calculated from information provided for the Hibbing Taconite facility, as follows, and assumed representative of natural gas in northern MN:
        Heat value (Btu/ft[3])	= Heat input (10[6] Btu, see Table 9, above)/Natural gas used (10[6] ft[3], from NEI)
                       = [2.47 x 10[12] (Btu)]/[2,418 x 10[6] (ft[3])] ≈ 1,020 (Btu/ft[3]).
The fuel use data in Table 10 were then combined with the AP-42 emissions factors for speciated HAP for each fuel utilized in the indurating furnaces during CY2014, summarized in Table 8, to produce the estimated combustion PI HAP emissions summarized in Table 11 below.
               Table 11: Summary of Combustion PI HAP Emissions
                                  HAP Emitted
                         HAP Emissions (tons per year)
                                       
                                    Minorca
                               Hibbing Taconite
                                  North-shore
                                    Empire
                                    Tilden
                                United Taconite
                                    Keetac
                                    Minntac
                       Polycyclic Aromatic Hydrocarbons
Naphthalene
                                   4.56E-04
                                   7.37E-04
                                   8.68E-04
                                   3.75E-04
                                   1.18E-03
                                   7.35E-04
                                   7.48E-04
                                   5.30E-02
2-Methylnaphthalene
                                   1.79E-05
                                   2.90E-05
                                   3.42E-05
                                   1.47E-05
                                   3.69E-05
                                   1.57E-05
                                   2.73E-05
                                   1.88E-04
Acenaphthene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   1.21E-05
                                   1.43E-05
                                   4.19E-06
                                   4.86E-04
Acenaphthylene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   7.36E-06
                                   7.63E-06
                                   3.10E-06
                                   2.59E-03
Fluorene
                                   2.09E-06
                                   3.39E-06
                                   3.98E-06
                                   1.73E-06
                                   2.10E-05
                                   2.53E-05
                                   7.01E-06
                                   1.78E-03
Phenanthrene
                                   1.27E-05
                                   2.06E-05
                                   2.42E-05
                                   1.05E-05
                                   7.58E-05
                                   8.08E-05
                                   3.07E-05
                                   3.73E-03
Anthracene
                                   1.79E-06
                                   2.90E-06
                                   3.42E-06
                                   1.48E-06
                                   7.55E-06
                                   6.99E-06
                                   3.61E-06
                                   1.56E-03
Fluoranthene
                                   2.24E-06
                                   3.63E-06
                                   4.27E-06
                                   1.85E-06
                                   1.77E-05
                                   2.03E-05
                                   6.40E-06
                                   8.51E-04
Pyrene
                                   3.74E-06
                                   6.05E-06
                                   7.12E-06
                                   3.08E-06
                                   1.38E-05
                                   1.18E-05
                                   7.07E-06
                                   1.94E-03
Benz[a]Anthracene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   4.24E-06
                                   3.24E-06
                                   2.38E-06
                                   4.28E-05
Chrysene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   4.61E-06
                                   3.76E-06
                                   2.47E-06
                                   2.92E-05
Benzo[b]Fluoranthene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   2.77E-06
                                   1.18E-06
                                   2.05E-06
                                   5.95E-05
Benzo[k]Fluoranthene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   2.77E-06
                                   1.18E-06
                                   2.05E-06
                                   2.65E-05
Benzo[e]Pyrene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.34E-06
Benzo[a]Pyrene
                                   8.96E-07
                                   1.45E-06
                                   1.71E-06
                                   7.38E-07
                                   2.55E-06
                                   1.77E-06
                                   1.52E-06
                                   1.35E-03
Perylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.68E-07
Indeno[1,2,3-c,d]Pyrene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   3.89E-06
                                   2.75E-06
                                   2.30E-06
                                   5.38E-05
Dibenzo[a,h]Anthracene
                                   8.96E-07
                                   1.45E-06
                                   1.71E-06
                                   7.37E-07
                                   1.85E-06
                                   7.85E-07
                                   1.36E-06
                                   9.97E-06
Benzo[g,h,i,]Perylene
                                   8.96E-07
                                   1.45E-06
                                   1.71E-06
                                   7.38E-07
                                   2.34E-06
                                   1.48E-06
                                   1.48E-06
                                   5.37E-05
7,12-Dimethylbenz[a]Anthracene
                                   1.20E-05
                                   1.93E-05
                                   2.28E-05
                                   9.83E-06
                                   2.46E-05
                                   1.05E-05
                                   1.82E-05
                                   7.01E-05
Benzo[b,k]Fluoranthene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.48E-08
Benzo[j,k]Fluoranthene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   8.26E-05
Benzo[b,j,k]Fluoranthene
                                       
                                       
                                       
                                   8.80E-10
                                   2.02E-06
                                   2.84E-06
                                   4.62E-07
                                   1.84E-06
Biphenyl
                                       
                                       
                                       
                                   1.36E-08
                                   3.12E-05
                                   4.39E-05
                                   7.15E-06
                                   2.85E-05
                            Dioxins and Furans [a]
2,3,7,8-Tetrachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   1.14E-13
                                   2.63E-10
                                   3.69E-10
                                   6.01E-11
                                   2.39E-10
Total Pentachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   3.58E-13
                                   8.21E-10
                                   1.15E-09
                                   1.88E-10
                                   7.48E-10
Hexachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   2.30E-13
                                   5.27E-10
                                   7.41E-10
                                   1.21E-10
                                   4.80E-10
Total Heptachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   6.67E-13
                                   1.53E-09
                                   2.15E-09
                                   3.51E-10
                                   1.40E-09
Octachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   3.33E-12
                                   7.64E-09
                                   1.07E-08
                                   1.75E-09
                                   7.00E-09
2,3,7,8-Tetrachlorodibenzofuran
                                       
                                       
                                       
                                   4.08E-13
                                   9.37E-10
                                   1.32E-09
                                   2.14E-10
                                   8.54E-10
Total Pentachlorodibenzofuran
                                       
                                       
                                       
                                   2.82E-12
                                   6.48E-09
                                   9.11E-09
                                   1.48E-09
                                   5.91E-09
Total Hexachlorodibenzofuran
                                       
                                       
                                       
                                   6.14E-13
                                   1.41E-09
                                   1.98E-09
                                   3.23E-10
                                   1.29E-09
Total Heptachlorodibenzofuran
                                       
                                       
                                       
                                   1.54E-12
                                   3.53E-09
                                   4.96E-09
                                   8.07E-10
                                   3.21E-09
Octachlorodibenzofuran
                                       
                                       
                                       
                                   5.30E-13
                                   1.22E-09
                                   1.71E-09
                                   2.79E-10
                                   1.11E-09
                         Other Combustion-Related HAP
Acetaldehyde
                                       
                                       
                                       
                                   4.56E-06
                                   1.05E-02
                                   1.47E-02
                                   2.40E-03
                                   4.38E-01
Acetophenone
                                       
                                       
                                       
                                   1.20E-07
                                   2.75E-04
                                   3.87E-04
                                   6.31E-05
                                   2.53E-04
Acrolein
                                       
                                       
                                       
                                   2.32E-06
                                   5.33E-03
                                   7.49E-03
                                   1.22E-03
                                   2.07E+00
Benzene
                                   1.57E-03
                                   2.54E-03
                                   2.99E-03
                                   1.30E-03
                                   2.71E-02
                                   3.49E-02
                                   7.85E-03
                                   2.20E+00
Benzyl Chloride
                                       
                                       
                                       
                                   5.60E-06
                                   1.29E-02
                                   1.81E-02
                                   2.94E-03
                                   1.17E-02
Bis(2-Ethylhexyl)Phthalate
                                       
                                       
                                       
                                   5.84E-07
                                   1.34E-03
                                   1.88E-03
                                   3.07E-04
                                   1.25E-03
Bromoform
                                       
                                       
                                       
                                   3.12E-07
                                   7.16E-04
                                   1.01E-03
                                   1.64E-04
                                   6.53E-04
1,3-Butadiene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.24E-05
Carbazole
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   9.29E-04
Carbon Disulfide
                                       
                                       
                                       
                                   1.04E-06
                                   2.39E-03
                                   3.36E-03
                                   5.47E-04
                                   2.18E-03
Carbon Tetrachloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.32E-02
Chlorine
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   4.08E-01
2-Chloroacetophenone
                                       
                                       
                                       
                                   5.60E-08
                                   1.29E-04
                                   1.81E-04
                                   2.94E-05
                                   1.17E-04
Chlorobenzene
                                       
                                       
                                       
                                   1.76E-07
                                   4.04E-04
                                   5.68E-04
                                   9.25E-05
                                   1.74E-02
Chloroform
                                       
                                       
                                       
                                   4.72E-07
                                   1.08E-03
                                   1.52E-03
                                   2.48E-04
                                   1.54E-02
2-Chloronaphthalene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.24E-06
Cumene
                                       
                                       
                                       
                                   4.24E-08
                                   9.73E-05
                                   1.37E-04
                                   2.23E-05
                                   8.87E-05
Cyanide
                                       
                                       
                                       
                                   2.00E-05
                                   4.59E-02
                                   6.45E-02
                                   1.05E-02
                                   4.19E-02
1,4-Dichlorobenzene
                                   8.96E-04
                                   1.45E-03
                                   1.71E-03
                                   7.37E-04
                                   1.85E-03
                                   7.85E-04
                                   1.36E-03
                                   5.23E-03
Dimethyl Sulfate
                                       
                                       
                                       
                                   3.84E-07
                                   8.81E-04
                                   1.24E-03
                                   2.02E-04
                                   8.04E-04
2,4-Dinitrophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   9.29E-05
2,4-Dinitrotoluene
                                       
                                       
                                       
                                   2.24E-09
                                   5.14E-06
                                   7.23E-06
                                   1.18E-06
                                   4.69E-06
Ethyl Benzene
                                       
                                       
                                       
                                   7.52E-07
                                   1.73E-03
                                   2.43E-03
                                   3.95E-04
                                   1.76E-02
Ethyl Chloride
                                       
                                       
                                       
                                   3.36E-07
                                   7.71E-04
                                   1.08E-03
                                   1.77E-04
                                   7.03E-04
Ethylene Dibromide
                                       
                                       
                                       
                                   9.60E-09
                                   2.20E-05
                                   3.10E-05
                                   5.04E-06
                                   2.84E-02
Ethylene Dichloride
                                       
                                       
                                       
                                   3.20E-07
                                   7.35E-04
                                   1.03E-03
                                   1.68E-04
                                   1.56E-02
Formaldehyde
                                   5.60E-02
                                   9.07E-02
                                   1.07E-01
                                   4.61E-02
                                   1.20E-01
                                   5.52E-02
                                   8.63E-02
                                   2.60E+00
Hexane
                                   1.34E+00
                                   2.18E+00
                                   2.56E+00
                                   1.11E+00
                                   2.77E+00
                                   1.18E+00
                                   2.05E+00
                                   7.88E+00
Isophorone
                                       
                                       
                                       
                                   4.64E-06
                                   1.07E-02
                                   1.50E-02
                                   2.44E-03
                                   9.71E-03
Methyl Bromide
                                       
                                       
                                       
                                   1.28E-06
                                   2.94E-03
                                   4.13E-03
                                   6.73E-04
                                   1.04E-02
Methyl Chloride
                                       
                                       
                                       
                                   4.24E-06
                                   9.73E-03
                                   1.37E-02
                                   2.23E-03
                                   2.07E-02
Methyl Chloroform
                                       
                                       
                                       
                                   1.60E-07
                                   3.67E-04
                                   5.16E-04
                                   8.41E-05
                                   1.63E-02
Methyl Methacrylate
                                       
                                       
                                       
                                   1.60E-07
                                   3.67E-04
                                   5.16E-04
                                   8.41E-05
                                   3.35E-04
Methyl Tert-Butyl Ether
                                       
                                       
                                       
                                   2.80E-07
                                   6.43E-04
                                   9.03E-04
                                   1.47E-04
                                   5.86E-04
3-Methylchloroanthrene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   2.77E-06
                                   1.18E-06
                                   2.05E-06
                                   7.88E-06
5-Methylchrysene
                                       
                                       
                                       
                                   1.76E-10
                                   4.04E-07
                                   5.68E-07
                                   9.25E-08
                                   3.68E-07
Methylene Chloride
                                       
                                       
                                       
                                   2.32E-06
                                   5.33E-03
                                   7.49E-03
                                   1.22E-03
                                   1.54E-01
Methylhydrazine
                                       
                                       
                                       
                                   1.36E-06
                                   3.12E-03
                                   4.39E-03
                                   7.15E-04
                                   2.85E-03
4-Nitrophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   5.68E-05
Pentachlorophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.63E-05
Phenol
                                       
                                       
                                       
                                   1.28E-07
                                   2.94E-04
                                   4.13E-04
                                   6.73E-05
                                   2.66E-02
Phosphorus
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.39E-02
Propionaldehyde
                                       
                                       
                                       
                                   3.04E-06
                                   6.98E-03
                                   9.81E-03
                                   1.60E-03
                                   3.78E-02
Propylene Dichloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.70E-02
Styrene
                                       
                                       
                                       
                                   2.00E-07
                                   4.59E-04
                                   6.45E-04
                                   1.05E-04
                                   9.81E-01
Tetrachloroethylene
                                       
                                       
                                       
                                   3.44E-07
                                   7.90E-04
                                   1.11E-03
                                   1.81E-04
                                   2.03E-02
Toluene
                                   2.54E-03
                                   4.11E-03
                                   4.84E-03
                                   2.09E-03
                                   9.64E-03
                                   8.42E-03
                                   4.87E-03
                                   4.94E-01
Trichloroethylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.55E-02
2,4,6-Trichlorophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.14E-05
Vinyl Acetate
                                       
                                       
                                       
                                   6.08E-08
                                   1.40E-04
                                   1.96E-04
                                   3.20E-05
                                   1.27E-04
Vinyl Chloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   9.29E-03
o-Xylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.29E-02
Xylenes (Mixture of o, m, and p Isomers) [a]
                                       
                                       
                                       
                                   2.96E-07
                                   6.79E-04
                                   9.55E-04
                                   1.56E-04
                                   6.19E-04
Note:	[a]	These HAP names have been changed from that used in Table 8, above, to use the name used in the risk model databases (i.e., dioxin and furans, and mixed isomers of xylenes).
Finally, the PI emission information from Tables 7 through 11 are combined to create a summary of gap-filled emissions, as shown in Table 12.
               Table 12: Summary of Gap-Filled PI HAP Emissions
                                  HAP Emitted
                         HAP Emissions (tons per year)
                                       
                                 Minorca Mine
                               Hibbing Taconite
                                  North-shore
                                  Empire Mine
                                  Tilden Mine
                                United Taconite
                                    Keetac
                                    Minntac
                                  HAP Metals
Antimony
                                   1.97E-02
                                   2.19E-03
                                   5.14E-04
                                   1.64E-03
                                   2.29E-02
                                   4.25E-03
                                   6.50E-03
                                   1.75E-01
Arsenic
                                   1.80E-02
                                   3.93E-01
                                   2.93E-02
                                   1.11E-05
                                   1.25E-04
                                   5.66E-01
                                   2.16E-01
                                   2.42E-01
Arsenic Trioxide
                                   3.56E-05
                                   7.78E-04
                                   5.80E-05
                                   2.20E-08
                                   2.47E-07
                                   1.12E-03
                                   4.28E-04
                                   4.78E-04
Beryllium
                                   9.88E-04
                                   5.20E-03
                                   3.00E-03
                                   1.64E-03
                                   3.42E-03
                                   8.85E-04
                                   1.39E-03
                                   1.66E-02
Cadmium
                                   3.97E-03
                                   5.15E-03
                                   8.48E-03
                                   5.12E-03
                                   5.36E-02
                                   4.49E-03
                                   6.47E-03
                                   3.52E-02
Chromium (VI)
                                   4.71E-04
                                   6.74E-04
                                   9.90E-03
                                   5.31E-04
                                   4.24E-03
                                   4.40E-03
                                   3.88E-03
                                   4.87E-02
Chromium III
                                   1.13E-02
                                   1.62E-02
                                   2.38E-01
                                   2.66E-02
                                   2.11E-01
                                   4.64E-02
                                   8.04E-02
                                   8.32E-01
Cobalt
                                   9.89E-04
                                   2.40E-02
                                   7.82E-03
                                   4.75E-02
                                   1.10E-02
                                   3.98E-03
                                   6.84E-03
                                   1.85E-02
Lead
                                   1.41E-02
                                   8.00E-02
                                   2.28E-01
                                   1.50E-01
                                   2.97E-01
                                   7.28E-02
                                   1.37E-01
                                   6.87E-01
Manganese
                                   1.61E-01
                                   4.33E-01
                                   4.49E-01
                                   1.80E-01
                                   8.22E-01
                                   1.34E-01
                                   1.78E-01
                                   1.43E+00
Mercury
                                   3.15E-02
                                   7.37E-02
                                   2.85E-03
                                   2.04E-02
                                   4.40E-02
                                   8.92E-02
                                   5.16E-02
                                   8.23E-02
Elemental Gaseous Mercury
                                   2.93E-02
                                   6.85E-02
                                   2.65E-03
                                   1.90E-02
                                   4.09E-02
                                   8.32E-02
                                   4.81E-02
                                   7.67E-02
Gaseous Divalent Mercury
                                   2.21E-03
                                   5.16E-03
                                   1.99E-04
                                   1.43E-03
                                   3.08E-03
                                   5.97E-03
                                   3.45E-03
                                   5.51E-03
Nickel
                                   3.02E-02
                                   3.02E-02
                                   5.43E-02
                                   1.41E-01
                                   2.41E-01
                                   1.44E-01
                                   2.58E-02
                                   7.51E-01
Nickel Subsulfide
                                   1.81E-03
                                   1.81E-03
                                   3.26E-03
                                   8.48E-03
                                   1.45E-02
                                   8.67E-03
                                   1.55E-03
                                   4.51E-02
Selenium
                                   1.14E-02
                                   2.21E-02
                                   7.73E-02
                                   2.14E-02
                                   2.79E-01
                                   4.86E-02
                                   4.38E-03
                                   1.77E-01
                                  Acid Gases
Hydrochloric Acid
                                   2.63E+01
                                   6.56E+00
                                   1.75E+01
                                   7.46E+01
                                   2.60E+02
                                   2.47E+01
                                   3.89E-01
                                   1.16E+02
Hydrogen Fluoride
                                   3.75E+00
                                   8.91E+00
                                   5.30E+00
                                   8.50E+00
                                   3.56E+01
                                   2.70E+01
                                   4.54E-02
                                   8.94E+01
                       Polycyclic Aromatic Hydrocarbons
Naphthalene
                                   4.56E-04
                                   7.37E-04
                                   8.68E-04
                                   3.75E-04
                                   1.18E-03
                                   7.35E-04
                                   7.48E-04
                                   5.30E-02
2-Methylnaphthalene
                                   1.79E-05
                                   2.90E-05
                                   3.42E-05
                                   1.47E-05
                                   3.69E-05
                                   1.57E-05
                                   2.73E-05
                                   1.88E-04
Acenaphthene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   1.21E-05
                                   1.43E-05
                                   4.19E-06
                                   4.86E-04
Acenaphthylene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   7.36E-06
                                   7.63E-06
                                   3.10E-06
                                   2.59E-03
Fluorene
                                   2.09E-06
                                   3.39E-06
                                   3.98E-06
                                   1.73E-06
                                   2.10E-05
                                   2.53E-05
                                   7.01E-06
                                   1.78E-03
Phenanthrene
                                   1.27E-05
                                   2.06E-05
                                   2.42E-05
                                   1.05E-05
                                   7.58E-05
                                   8.08E-05
                                   3.07E-05
                                   3.73E-03
Anthracene
                                   1.79E-06
                                   2.90E-06
                                   3.42E-06
                                   1.48E-06
                                   7.55E-06
                                   6.99E-06
                                   3.61E-06
                                   2.75E-03
Fluoranthene
                                   2.24E-06
                                   3.63E-06
                                   4.27E-06
                                   1.85E-06
                                   1.77E-05
                                   2.03E-05
                                   6.40E-06
                                   1.48E-03
Pyrene
                                   3.74E-06
                                   6.05E-06
                                   7.12E-06
                                   3.08E-06
                                   1.38E-05
                                   1.18E-05
                                   7.07E-06
                                   3.40E-03
Benz[a]Anthracene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   4.24E-06
                                   3.24E-06
                                   2.38E-06
                                   6.79E-05
Chrysene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   4.61E-06
                                   3.76E-06
                                   2.47E-06
                                   4.36E-05
Benzo[b]Fluoranthene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   2.77E-06
                                   1.18E-06
                                   2.05E-06
                                   9.85E-05
Benzo[k]Fluoranthene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   2.77E-06
                                   1.18E-06
                                   2.05E-06
                                   4.00E-05
Benzo[e]Pyrene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.37E-06
Benzo[a]Pyrene
                                   8.96E-07
                                   1.45E-06
                                   1.71E-06
                                   7.38E-07
                                   2.55E-06
                                   1.77E-06
                                   1.52E-06
                                   2.38E-03
Perylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   4.75E-07
Indeno[1,2,3-c,d]Pyrene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   3.89E-06
                                   2.75E-06
                                   2.30E-06
                                   8.76E-05
Dibenzo[a,h]Anthracene
                                   8.96E-07
                                   1.45E-06
                                   1.71E-06
                                   7.37E-07
                                   1.85E-06
                                   7.85E-07
                                   1.36E-06
                                   1.31E-05
Benzo[g,h,i,]Perylene
                                   8.96E-07
                                   1.45E-06
                                   1.71E-06
                                   7.38E-07
                                   2.34E-06
                                   1.48E-06
                                   1.48E-06
                                   9.01E-05
7,12-Dimethylbenz[a]Anthracene
                                   1.20E-05
                                   1.93E-05
                                   2.28E-05
                                   9.83E-06
                                   2.46E-05
                                   1.05E-05
                                   1.82E-05
                                   6.38E-05
Benzo[b+k]Fluoranthene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.48E-08
Benzofluoranthenes
                                       
                                       
                                       
                                   8.80E-10
                                   2.02E-06
                                   2.84E-06
                                   4.62E-07
                                   1.48E-04
Biphenyl
                                       
                                       
                                       
                                   1.36E-08
                                   3.12E-05
                                   4.39E-05
                                   7.15E-06
                                   2.85E-05
                              Dioxins and Furans
2,3,7,8-Tetrachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   1.14E-13
                                   2.63E-10
                                   3.69E-10
                                   6.01E-11
                                   2.39E-10
Total Pentachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   3.58E-13
                                   8.21E-10
                                   1.15E-09
                                   1.88E-10
                                   7.48E-10
Hexachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   2.30E-13
                                   5.27E-10
                                   7.41E-10
                                   1.21E-10
                                   4.80E-10
Total Heptachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   6.67E-13
                                   1.53E-09
                                   2.15E-09
                                   3.51E-10
                                   1.40E-09
Octachlorodibenzo-p-Dioxin
                                       
                                       
                                       
                                   3.33E-12
                                   7.64E-09
                                   1.07E-08
                                   1.75E-09
                                   7.00E-09
2,3,7,8-Tetrachlorodibenzofuran
                                       
                                       
                                       
                                   4.08E-13
                                   9.37E-10
                                   1.32E-09
                                   2.14E-10
                                   8.54E-10
Total Pentachlorodibenzofuran
                                       
                                       
                                       
                                   2.82E-12
                                   6.48E-09
                                   9.11E-09
                                   1.48E-09
                                   5.91E-09
Total Hexachlorodibenzofuran
                                       
                                       
                                       
                                   6.14E-13
                                   1.41E-09
                                   1.98E-09
                                   3.23E-10
                                   1.29E-09
Total Heptachlorodibenzofuran
                                       
                                       
                                       
                                   1.54E-12
                                   3.53E-09
                                   4.96E-09
                                   8.07E-10
                                   3.21E-09
Octachlorodibenzofuran
                                       
                                       
                                       
                                   5.30E-13
                                   1.22E-09
                                   1.71E-09
                                   2.79E-10
                                   1.11E-09
                         Other Combustion-Related HAP
Acetaldehyde
                                       
                                       
                                       
                                   4.56E-06
                                   1.05E-02
                                   1.47E-02
                                   2.40E-03
                                   4.38E-01
Acetophenone
                                       
                                       
                                       
                                   1.20E-07
                                   2.75E-04
                                   3.87E-04
                                   6.31E-05
                                   2.53E-04
Acrolein
                                       
                                       
                                       
                                   2.32E-06
                                   5.33E-03
                                   7.49E-03
                                   1.22E-03
                                   2.07E+00
Benzene [a]
                                   1.57E-03
                                   2.54E-03
                                   2.99E-03
                                   1.30E-03
                                   2.71E-02
                                   3.49E-02
                                   7.85E-03
                                   2.20E+00
Benzyl Chloride
                                       
                                       
                                       
                                   5.60E-06
                                   1.29E-02
                                   1.81E-02
                                   2.94E-03
                                   1.17E-02
Bis(2-Ethylhexyl)Phthalate
                                       
                                       
                                       
                                   5.84E-07
                                   1.34E-03
                                   1.88E-03
                                   3.07E-04
                                   1.25E-03
Bromoform
                                       
                                       
                                       
                                   3.12E-07
                                   7.16E-04
                                   1.01E-03
                                   1.64E-04
                                   6.53E-04
1,3-Butadiene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.24E-05
Carbazole
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   9.29E-04
Carbon Disulfide
                                       
                                       
                                       
                                   1.04E-06
                                   2.39E-03
                                   3.36E-03
                                   5.47E-04
                                   2.18E-03
Carbon Tetrachloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.32E-02
Chlorine
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   4.08E-01
2-Chloroacetophenone
                                       
                                       
                                       
                                   5.60E-08
                                   1.29E-04
                                   1.81E-04
                                   2.94E-05
                                   1.17E-04
Chlorobenzene
                                       
                                       
                                       
                                   1.76E-07
                                   4.04E-04
                                   5.68E-04
                                   9.25E-05
                                   1.74E-02
Chloroform
                                       
                                       
                                       
                                   4.72E-07
                                   1.08E-03
                                   1.52E-03
                                   2.48E-04
                                   1.54E-02
2-Chloronaphthalene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.24E-06
Cumene
                                       
                                       
                                       
                                   4.24E-08
                                   9.73E-05
                                   1.37E-04
                                   2.23E-05
                                   8.87E-05
Cyanide
                                       
                                       
                                       
                                   2.00E-05
                                   4.59E-02
                                   6.45E-02
                                   1.05E-02
                                   4.19E-02
1,4-Dichlorobenzene
                                   8.96E-04
                                   1.45E-03
                                   1.71E-03
                                   7.37E-04
                                   1.85E-03
                                   7.85E-04
                                   1.36E-03
                                   5.23E-03
Dimethyl Sulfate
                                       
                                       
                                       
                                   3.84E-07
                                   8.81E-04
                                   1.24E-03
                                   2.02E-04
                                   8.04E-04
2,4-Dinitrophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   9.29E-05
2,4-Dinitrotoluene
                                       
                                       
                                       
                                   2.24E-09
                                   5.14E-06
                                   7.23E-06
                                   1.18E-06
                                   4.69E-06
Ethyl Benzene
                                       
                                       
                                       
                                   7.52E-07
                                   1.73E-03
                                   2.43E-03
                                   3.95E-04
                                   1.76E-02
Ethyl Chloride
                                       
                                       
                                       
                                   3.36E-07
                                   7.71E-04
                                   1.08E-03
                                   1.77E-04
                                   7.03E-04
Ethylene Dibromide
                                       
                                       
                                       
                                   9.60E-09
                                   2.20E-05
                                   3.10E-05
                                   5.04E-06
                                   2.84E-02
Ethylene Dichloride
                                       
                                       
                                       
                                   3.20E-07
                                   7.35E-04
                                   1.03E-03
                                   1.68E-04
                                   1.56E-02
Formaldehyde [a]
                                   5.60E-02
                                   9.07E-02
                                   1.07E-01
                                   4.61E-02
                                   1.20E-01
                                   5.52E-02
                                   8.63E-02
                                   2.60E+00
Hexane [a]
                                   1.34E+00
                                   2.18E+00
                                   2.56E+00
                                   1.11E+00
                                   2.77E+00
                                   1.18E+00
                                   2.05E+00
                                   7.88E+00
Isophorone
                                       
                                       
                                       
                                   4.64E-06
                                   1.07E-02
                                   1.50E-02
                                   2.44E-03
                                   9.71E-03
Methyl Bromide
                                       
                                       
                                       
                                   1.28E-06
                                   2.94E-03
                                   4.13E-03
                                   6.73E-04
                                   1.04E-02
Methyl Chloride
                                       
                                       
                                       
                                   4.24E-06
                                   9.73E-03
                                   1.37E-02
                                   2.23E-03
                                   2.07E-02
Methyl Chloroform
                                       
                                       
                                       
                                   1.60E-07
                                   3.67E-04
                                   5.16E-04
                                   8.41E-05
                                   1.63E-02
Methyl Methacrylate
                                       
                                       
                                       
                                   1.60E-07
                                   3.67E-04
                                   5.16E-04
                                   8.41E-05
                                   3.35E-04
Methyl Tert-Butyl Ether
                                       
                                       
                                       
                                   2.80E-07
                                   6.43E-04
                                   9.03E-04
                                   1.47E-04
                                   5.86E-04
3-Methylcholanthrene
                                   1.34E-06
                                   2.18E-06
                                   2.56E-06
                                   1.11E-06
                                   2.77E-06
                                   1.18E-06
                                   2.05E-06
                                   7.88E-06
5-Methylchrysene
                                       
                                       
                                       
                                   1.76E-10
                                   4.04E-07
                                   5.68E-07
                                   9.25E-08
                                   3.68E-07
Methylene Chloride
                                       
                                       
                                       
                                   2.32E-06
                                   5.33E-03
                                   7.49E-03
                                   1.22E-03
                                   1.54E-01
Methylhydrazine
                                       
                                       
                                       
                                   1.36E-06
                                   3.12E-03
                                   4.39E-03
                                   7.15E-04
                                   2.85E-03
4-Nitrophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   5.68E-05
Pentachlorophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   2.63E-05
Phenol
                                       
                                       
                                       
                                   1.28E-07
                                   2.94E-04
                                   4.13E-04
                                   6.73E-05
                                   2.66E-02
Phosphorus
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.39E-02
Propionaldehyde
                                       
                                       
                                       
                                   3.04E-06
                                   6.98E-03
                                   9.81E-03
                                   1.60E-03
                                   3.78E-02
Propylene Dichloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.70E-02
Styrene
                                       
                                       
                                       
                                   2.00E-07
                                   4.59E-04
                                   6.45E-04
                                   1.05E-04
                                   9.81E-01
Tetrachloroethylene
                                       
                                       
                                       
                                   3.44E-07
                                   7.90E-04
                                   1.11E-03
                                   1.81E-04
                                   2.03E-02
Toluene [a]
                                   2.54E-03
                                   4.11E-03
                                   4.84E-03
                                   2.09E-03
                                   9.64E-03
                                   8.42E-03
                                   4.87E-03
                                   4.94E-01
Trichloroethylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.55E-02
2,4,6-Trichlorophenol
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.14E-05
Vinyl Acetate
                                       
                                       
                                       
                                   6.08E-08
                                   1.40E-04
                                   1.96E-04
                                   3.20E-05
                                   1.27E-04
Vinyl Chloride
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   9.29E-03
o-Xylene
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1.29E-02
Xylenes (Mixture of o, m, and p Isomers)
                                       
                                       
                                       
                                   2.96E-07
                                   6.79E-04
                                   9.55E-04
                                   1.56E-04
                                   6.19E-04
Notes:	[a]	Several taconite iron ore processing facilities included emissions of certain products of incomplete combustion (i.e., benzene, formaldehyde, hexane, and toluene) based on testing done in the mid-1990s.[24] That testing indicated that emissions of these HAP were typically below detection limits, but some facilities included emissions of these HAP assuming emissions at rates equal to the testing detection limits. Table 12 (and the risk file) instead includes emissions of these HAP based on fuel use during CY2014 and the emissions factors taken from AP-42.
     Values highlighted in yellow are those HAP for which the NEI or Petition to Delist did not indicate any emissions, but were gap-filled (i.e., emissions were included in the modeling file) either using the speciation profile provided in the Petition to Delist (e.g., for As and Ni for facilities in MN) or AP-42 emissions factors. Values highlighted in green are those HAP for which the NEI or Petition to Delist did indicate emissions, but the values listed in the modeling file and Table 12 differ from the provided values due either to the reason cited in note [a], above, or for other unknown reasons. Note however, that the values highlighted in green (other than those from note [a], above) are typically very close to the values provided via the NEI or the Petition to Delist.
     In order to match the names used in the risk modeling database: "Benzo[b,k]Fluoranthene" was changed to "Benzo[b+k]Fluoranthene"; and "Benzo[j,k]Fluoranthene" and "Benzo[b,j,k]fluoranthene" were combined in the more generic "Benzofluoranthenes."
     The Minntac facility reported emissions of 1,3-butadiene in the NEI. Although AP-42 did not include an emissions factor for this pollutant for the utilized fuels, it was retained in this table (and the modeling file).
 Pellet Handling Operations (PH)
PH sources do not include any fossil fuel combustion and, although these sources do handle finished pellets (i.e., after incorporation of additives - binders and/or fluxing agents), the volatile portion of the pellet additives have already been released via the pellet induration processes. Therefore, PH sources are only expected to emit metal HAP, summarized in Table 14, below.
                     Table 13: Summary of PH HAP Emissions
                                      HAP
                         HAP Emissions (tons per year)
                                       
                                    Minorca
                                    Empire
                               Hibbing Taconite
                                  North-shore
                                    Tilden
                                United Taconite
                                    Keetac
                                    Minntac
Antimony
                                   1.11E-04
                                   1.71E-05
                                   1.41E-05
                                   2.40E-05
                                   6.32E-05
                                   2.32E-04
                                   3.07E-04
                                   1.49E-04
Arsenic
                                   1.87E-04
                                   6.87E-05
                                   3.80E-04
                                   1.02E-04
                                   3.32E-04
                                   1.23E-04
                                   1.86E-03
                                   1.76E-03
Beryllium
                                   9.35E-06
                                   1.29E-05
                                   3.96E-05
                                   2.84E-05
                                   1.58E-05
                                   8.21E-05
                                   2.57E-04
                                   2.67E-04
Cadmium
                                   6.83E-06
                                   1.71E-06
                                   8.48E-07
                                   1.37E-06
                                   6.32E-06
                                   6.84E-06
                                   7.24E-05
                                   1.01E-05
Chromium (VI)
                                   2.78E-07
                                       
                                   2.20E-05
                                   4.03E-05
                                       
                                   5.25E-05
                                   3.37E-05
                                   2.55E-04
Chromium III
                                   8.98E-06
                                   6.44E-05
                                   7.10E-04
                                   1.30E-03
                                   2.85E-04
                                   1.70E-03
                                   1.09E-03
                                   8.24E-03
Cobalt
                                   7.48E-06
                                   8.58E-06
                                   1.05E-04
                                   4.67E-04
                                   5.39E-05
                                   8.34E-04
                                   8.32E-04
                                   2.54E-03
Lead
                                       
                                   1.71E-05
                                       
                                       
                                   6.32E-05
                                   3.69E-04
                                       
                                       
Manganese
                                   3.66E-03
                                   1.39E-03
                                   3.45E-02
                                   5.44E-02
                                   1.25E-02
                                   1.29E-02
                                   3.32E-01
                                   3.49E-01
Mercury (202)
                                   7.81E-08
                                   3.86E-09
                                   4.02E-08
                                   1.50E-08
                                   8.70E-09
                                   1.37E-05
                                   6.25E-08
                                   7.20E-08
Nickel
                                   3.70E-06
                                   3.00E-05
                                   1.30E-04
                                   3.34E-04
                                   7.92E-05
                                   6.84E-05
                                   8.68E-04
                                   2.03E-03
Selenium
                                   9.25E-05
                                   4.29E-05
                                   1.23E-05
                                   1.24E-05
                                   1.58E-04
                                   6.84E-05
                                   7.39E-04
                                   5.33E-05

 Fugitive Dust Emissions Control Plan Sources (FDECP)
As with OCH and PH, the FDECP sources do not involve combustion of fossil fuels and are only expected to emit metal HAP. The Michigan facilities (i.e., Empire and Tilden) did not include any FDECP emissions data in the NEI or the Petition to Delist. The FDECP emission point data for the Michigan facilities were estimated as follows (see summaries in Tables 14 and 15, below):
 Since OCH emission sources handle raw ore (i.e., before the concentration of iron content and addition of pellet additives), it is presumed that OCH HAP emissions are reflective of pre-induration FDECP HAP emissions;
 Since PH emission sources handle finished ("fired") pellets (i.e., after concentration of iron content and addition of pellet additives), it is presumed that PH HAP emissions are reflective of post-induration FDECP HAP emissions;
 The average ratio of FDECP/OCH HAP emissions and the average ratio of FDECP/PH HAP emissions were calculated for the MN facilities;
 The total HAP emissions from pre-induration FDECP emission sources at each MI facility were estimated by multiplying that facility's total OCH HAP emissions by the average ratio of FDECP/OCH HAP emissions calculated for the MN facilities. The total HAP emissions from post-induration FDECP emission sources at each MI facility were estimated by multiplying that facility's total PH HAP emissions by the average ratio of FDECP/PH HAP emissions calculated for the MN facilities;
 The total FDECP emissions cited in Table 14 for each of the MI facilities is equal to the sum of the pre-induration and post-induration total FDECP emissions, calculated as described in the previous bullet;
 The speciated HAP emissions from pre-induration FDECP emission sources at each MI facility were estimated by multiplying that facility's speciated OCH HAP emissions by the average ratio of FDECP/OCH HAP emissions calculated for the MN facilities. The speciated HAP emissions from post-induration FDECP emission sources at each MI facility were estimated by multiplying that facility's speciated PH HAP emissions by the average ratio of FDECP/PH HAP emissions calculated for the MN facilities;
 The speciated FDECP emissions cited in Table 15 for each of the MI facilities is equal to the sum of the pre-induration and post-induration speciated FDECP emissions, calculated as described in the previous bullet.
                    Table 14: Total 2014 EPG HAP Emissions
                                      EPG
    Actual Total 2014 EPG HAP Emissions (tons emitted per year) [a][,] [b]

                                 MN Facilities
                                 MI Facilities

                                    Minorca
                               Hibbing Taconite
                                  North-shore
                                United Taconite
                                    Keetac
                                    Minntac
                                     Ave.
                                    Empire
                                    Tilden
FDECP
                                    1.6E-01
                                    2.1E+00
                                    4.6E-02
                                    2.7E-02
                                    6.0E-01
                                    2.5E+00
                                    9.1E-01
                                    1.0E-01
                                    3.7E-01
OCH
                                    8.3E-02
                                    6.3E-01
                                    6.7E-02
                                    3.8E-01
                                    1.1E-01
                                    7.6E-01
                                    3.4E-01
                                    2.8E-02
                                    5.0E-02
PH
                                    4.1E-03
                                    3.6E-02
                                    5.7E-02
                                    1.9E-01
                                    3.4E-01
                                    3.6E-01
                                    1.7E-01
                                    1.7E-03
                                    1.4E-02
FDECP/OCH
                                    1.9E+00
                                    3.3E+00
                                    6.9E-01
                                    7.0E-02
                                    5.5E+00
                                    3.3E+00
                                    2.5E+00
                                       
                                       
FDECP/PH
                                    3.8E+01
                                    5.8E+01
                                    8.2E-01
                                    1.4E-01
                                    1.8E+00
                                    7.0E+00
                                    1.8E+01
                                       
                                       
[a]	Emissions from MN facilities were obtained from NEI
b	OCH and PH emissions from MI facilities were obtained from the Petition to Delist. FDECP emissions from MI facilities were calculated as described above.
              Table 15: Summary of Speciated FDECP HAP Emissions
                                      HAP
                         HAP Emissions (tons per year)
                                       
                                    Minorca
                                    Empire
                               Hibbing Taconite
                                  North-shore
                                    Tilden
                                United Taconite
                                    Keetac
                                    Minntac
Antimony
                                   3.93E-04
                                   3.08E-04
                                   3.86E-04
                                   6.32E-05
                                   1.32E-03
                                   1.80E-04
                                   6.36E-04
                                    3.95-03
Arsenic
                                   6.62E-04
                                   1.62E-03
                                   6.84E-03
                                   1.32E-04
                                   6.66E-03
                                   2.25E-04
                                   1.18E-03
                                   7.20E-03
Beryllium
                                   2.62E-05
                                   2.32E-04
                                   6.01E-04
                                   3.84E-05
                                   3.31E-04
                                   7.50E-05
                                   2.72E-04
                                   1.04E-03
Cadmium
                                   2.62E-06
                                   3.08E-05
                                   1.46E-05
                                   3.49E-07
                                   1.32E-04
                                   7.50E-06
                                   1.82E-04
                                   5.14E-04
Chromium (VI)
                                   9.83E-07
                                       
                                   8.18E-04
                                   2.46E-05
                                       
                                   1.11E-05
                                   3.54E-05
                                   3.45E-04
Chromium III
                                   3.18E-05
                                   5.14E-03
                                   2.65E-02
                                   7.96E-04
                                   1.22E-02
                                   3.60E-04
                                   1.15E-03
                                   1.12E-02
Cobalt
                                   2.26E-04
                                   7.13E-04
                                   2.88E-03
                                   1.52E-04
                                   2.37E-03
                                   7.20E-04
                                   1.18E-03
                                   4.90E-03
Lead
                                       
                                   9.26E-04
                                       
                                       
                                   2.24E-03
                                       
                                       
                                       
Manganese
                                   1.54E-01
                                   8.79E-02
                                   2.04E+00
                                   4.50E-02
                                   3.37E-01
                                   5.85E-02
                                   5.91E-01
                                   2.50E+00
Mercury
                                   3.60E-07
                                   3.26E-07
                                   3.77E-06
                                   1.92E-07
                                   6.13E-07
                                   1.50E-05
                                   1.35E-07
                                   2.48E-04
Nickel
                                   4.92E-05
                                   1.96E-03
                                   2.06E-03
                                   6.11E-05
                                   3.94E-03
                                   1.95E-04
                                   6.36E-04
                                   3.45E-03
Selenium
                                   3.28E-04
                                   1.03E-03
                                   1.55E-04
                                   5.24E-06
                                   3.31E-03
                                   7.50E-05
                                   1.82E-03
                                   5.29E-03
 Discussion of Actual, Allowable and Acute Emissions
 Actual Emissions
Actual emission rates were developed for each EPG for this dataset as described in section V.1 of this document, above, based on information found in the NEI, the Petition to Delist, the MAERS, and on information provided by the MPCA, the Michigan Department of Environmental Quality and industry representatives. Note that, although the Empire facility is currently in a state of indefinite idle due to a depleted mine, actual emissions for this facility were included in the dataset because the mine could reopen. The company has retained the operating permit for the processing facility and will resume operations if market conditions change and the necessary expense of expanding the mine are justified.
 Allowable Emissions
Allowable emission rates for the taconite iron ore processing facilities were developed by scaling up the actual emission rates. Specifically, once the actual emission rates were developed for a given facility, the allowable emission rate of each EPG at a given facility was estimated by multiplying the actual emission rate of that EPG by the ratio of the effective (maximum) production rate of that facility to the actual production rate of that facility during calendar year 2014. Again, allowable emissions for the Empire facility were included in the dataset even though that facility is currently idled because the company retains the ability to operate the facility.

             Table 16: Summary of Allowable Emissions Multipliers
                                   Facility
                    Production Rate (million long ton/year)
                                     Ratio
                                   Facility
                    Production Rate (million long ton/year)
                                     Ratio
                                       
                                     2014
                                   Effective
                                       
                                       
                                     2014
                                   Effective
                                       
Minorca Mine
                                     2.51
                                      2.8
                                     1.12
Tilden Mine
                                                                           6.77
                                                                            7.8
                                     1.15
Empire Mine
                                     2.63
                                      8.4
                                     3.19
United Taconite
                                                                           4.82
                                                                            5.4
                                     1.12
Hibbing Taconite
                                     7.34
                                      8.0
                                     1.09
USS-Keetac
                                                                           5.15
                                                                            6.0
                                     1.17
Northshore Mining
                                     5.12
                                      6.2
                                     1.21
USS-Minntac
                                                                          13.71
                                                                           16.0
                                     1.17
 Acute Emissions
To develop screening estimates of acute exposures in the absence of hourly emissions data, the EPA generally develops estimates of maximum hourly emissions rates by multiplying the average actual annual hourly emissions rates by a default factor to cover routinely variable emissions. The EPA chooses the factor based on process knowledge and engineering judgment reflecting, where appropriate, circumstances of the particular source category. The default factor reflects the findings of the Texas study of short-term emissions variability, which showed that most peak emission events in a heavily-industrialized area were less than twice the annual average hourly emissions rate.[2][5]
For the taconite iron ore processing source category, information was available to determine process-specific factors. The processes in the taconite iron ore processing source category are typically equipped with controls which will not allow startup of the emission source until the associated control device is operating and will automatically shut down the emission source if the associated controls malfunction.
The indurating furnaces, which are by far the largest sources of HAP emissions, typically operate continuously for long periods of time, so there are no significant spikes in emissions. The EPA believes emissions from the indurating furnaces are relatively consistent over time with minimal fluctuation and estimated that hourly emissions rates from indurating furnaces could occasionally increase by a factor of up to 2 times the average hourly actual emissions. The EPA believes this is a valid multiplier to estimate maximum acute emissions from indurating furnaces. Ore crushing and handling operations, ore drying operations, pellet handling operations and fugitive dust emissions control plan sources may have specific batch operation cycles with peak emissions occurring for a part of that cycle. The EPA believes these peak hourly emissions could be as high as 10 times the average hourly actual emissions for these sources. Note that for the Empire facility we used a slightly modified approach since that facility was nearing the end of mine capacity during 2014 (see discussion above) and was operating well below normal production rates. That is, the 2014 production rate at the Empire facility was so low (about 31% of its effective production rate, as shown in Table 2, above), that scaling up actual emissions by the cited factors of two times for furnaces and ten times for other sources results in acute emissions that are less than the allowable emissions for the Empire facility, which we believe is not representative. Note that the average ratio of effective production to actual 2014 production for the taconite iron ore processing facilities (other than the Empire facility) is 1.15 (refer to Table 17, above). Therefore, to estimate a more "typical" actual production rate for the Empire facility, the actual emissions were scaled up to the allowable rate (i.e., multiplied by 3.19  -  refer to Table 17, above) and then reduced by the average effective/actual factor (i.e., 1.15). Then, these modified actual emissions were scaled up by the cited factors of two times for furnaces and ten times for other sources.

VI.	Non-Category Emissions Development
A dataset representing facility-wide emissions was developed. This dataset consisted of HAP emissions from all category emission sources (i.e., those emission sources that are part of the taconite iron ore processing source category) at the taconite iron ore processing facilities, as well as all HAP emitted from non-category emission sources. The facility-wide emissions dataset was created by adding non-taconite iron ore processing source category emission points to the taconite iron ore processing source category dataset. Two modeling files were developed for use in the risk review; one file with data for only taconite iron ore processing emission sources (i.e., the source category file) and one file with data for all emission sources (i.e., the facility-wide file). A total of 8 major source facilities were modeled. The taconite iron ore processing source category does not include any non-major (i.e., area) sources.
All of the taconite iron ore processing facilities include non-category emission sources. The most common non-category emission sources include boilers, emergency generators and fire pumps. One facility (the Northshore Mining facility) includes two boilers which are utilized to generate electric power for use on-site and, when not needed for facility operation, for sale to the grid. The non-category emissions data were extracted from the 2014 NEI.
VII.	Emission Release Points
Category emissions: The Petition to Delist did not include reliable information on the location of the emission processes groups (EPG) emission release points. Further, Google Earth(TM) imagery indicated that the EPG emission release points' location information (i.e., the latitudes and longitudes) provided in the NEI is often not accurate. Therefore, for each taconite iron ore processing facility, the modeling file includes one emission release point, each, for ore crushing and handling operations, ore drying operations (Tilden only), pellet induration, and pellet handling operations. For each of these EPG, in an attempt to obtain the worst-case risk modeling results, the modeling file utilizes the emission release point located closest to the nearest residence, based on available Google Earth(TM) imagery, unless a more accurate location was provided by industry representatives. Further, for each EPG, the modeling file assumes that all HAP emissions from a given EPG are emitted from a stack with parameters (e.g., height, temperature, diameter, and exit velocity) equal to the average of the actual stacks' parameters of that EPG (as provided in NEI).
Again, for the fugitive dust emission control plan EPG, in an attempt to obtain the worst-case risk modeling results, the modeling file assumes all associated HAP are emitted from the area source at the facility that is located closest to the nearest residence, based on available Google Earth(TM) imagery, unless a more accurate location was provided by industry representatives.
Refer to Appendix A for the Google Earth(TM) image, with emission locations indicated, for each taconite iron ore processing facility.
Non-Category emissions: For the non-category emission sources, we made no changes to the emissions data provided in the NEI, except to make sure that the emission point is located onsite.
VIII.	Quality Control Checks and Resulting Changes
Data in the draft modeling file were checked in several ways. Data quality checks that were performed and changes that were made are briefly summarized below:
Source latitudes and longitudes cited in NEI were checked in Google Earth(TM) to verify accuracy and were corrected as needed. Correct format for latitude and longitude was reviewed and corrected as needed.
Emissions estimates were expanded to include those HAP expected from combustion of fossil fuels in the indurating furnaces.
Pollutant names and pollutant codes were reviewed and corrected, as necessary, in order to match the names and codes included in the modeling file lookup tables.
Any NEI exhaust temperatures, stack heights, stack diameters, and exhaust flow rates that appeared to be out of standard industry range were reviewed and corrected, as necessary.
Each calculation methodology was reviewed and emissions factors and estimated emission rates were reviewed for accuracy.
Actual emissions were verified to be less than or equal to allowable emissions which were, in turn, verified to be less than acute emissions.
As requested by the taconite iron ore processing industry representatives, the draft modeling file was made available to the subject facilities to provide an opportunity for them to review the associated emission release parameters and the estimated emission rates.
Reviewed and corrected, as appropriate, stack parameters (e.g., diameter, height, flow rate, and temperature) and estimated emission rates in accordance with additional information provided by industry representatives pursuant to their review of the draft file.
 The quality control efforts employed for this project resulted in a more accurate 2014 emissions dataset. Some data were modified in the final modeling file, however, the changes were relatively minor and did not significantly change the modeling inputs or outputs.
IX.	References	(All cited reference materials are available via the links provided below and/or may be found in Docket ID No. EPA-HQ-OAR-2017-0664)
Iron Mining Association of Minnesota (IMA) State of the Industry Update (2015)
Taconite Mining and Industry Profile (Draft Report, dated September 2001) https://www3.epa.gov/ttnecas1/regdata/IPs/Taconite_IP.pdf
Taconite Ore Processing section of AP-42 (Section 11.23) (https://www3.epa.gov/ttn/chief/ap42/ch11/final/c11s23.pdf)
2016 Mining Tax Guide (Minnesota Department of Revenue) http://www.revenue.state.mn.us/businesses/mineral/Documents/2016_mining_guide.pdf
MAERS 2014 Annual Report Summary for Empire
MAERS 2014 Annual Report Summary for Tilden
Initial NESHAP proposal Background Information Document (EPA/ 453/R-02-015, December 2002) (https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=2000NRYN.pdf)
Initial NESHAP proposal (67 FR 77562, December 18, 2002) https://www.gpo.gov/fdsys/pkg/FR-2002-12-18/pdf/02-31231.pdf
Petition to Delist
Petition to Delist, Appendix D for Empire
Petitions to Delist, Appendix I for Tilden
Additional facility-specific process information provided by taconite iron ore process industry representatives, received July 9, 2018.
Additional facility-specific process information provided by taconite iron ore process industry representatives, received July 26, 2018.
Petition to Delist, Appendix R for speciation of Hg
Petition to Delist, Appendix S for speciation of As and Ni, Part 1
Petition to Delist, Appendix S for speciation of As and Ni, Part 2
Petition to Delist, Appendix T for speciation of Cr
Section 1.1 of AP-42: Bituminous and Subbituminous Coal Combustion (https://www3.epa.gov/ttn/chief/ap42/ch01/final/c01s01.pdf)
Section 1.3 of AP-42: Fuel Oil Combustion (https://www3.epa.gov/ttn/chief/ap42/ch01/final/c01s03.pdf)
Section 1.4 of AP-42: Natural Gas Combustion (https://www3.epa.gov/ttn/chief/ap42/ch01/final/c01s04.pdf)
Section 1.6 of AP-42: Wood Residue Combustion in Boilers (https://www3.epa.gov/ttn/chief/ap42/ch01/final/c01s06.pdf)
April 19, 2017 email from Anne Jackson of the Minnesota Pollution Control Agency
November 3, 2017 email from Rich Zavoda of ArcelorMittal USA
Taconite Iron Ore Industry in the United States, A Background Information Report for MACT Determination (from MPCA to US EPA, dated December 30, 1999)
Variable Industrial VOC Emissions and their impact on ozone formation in the Houston Galveston Area (a report from The University of Texas at Austin and The University of North Carolina at Chapel Hill to Texas Environmental Research Consortium, dated April 9, 2004), available at https://www.tceq.texas.gov/assets/public/implementation/air/sip/sipdocs/2004-05-HGB/04042sipapi_pro.pdf.
 
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
          Appendix A: Taconite Iron Ore Processing Facility Site Maps
 
                                       
                                  Empire Mine
Empire Mine: Site Layout View

Empire Mine: EPG Location View

(width of FDECP-E ≈ 300 feet)
(width of FDECP-E ≈ 300 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-E
                                   46.444064
                                  -87.601539
PI-E
                                   46.445977
                                  -87.600293
PH-E
                                   46.446300
                                  -87.599174
FDECP-E1
                                   46.444322
                                  -87.596186
FDECP-E2
                                   46.450691
                                  -87.596085

                                  Tilden Mine
Tilden Mine: Site Layout View

Tilden Mine: EPG Location View

(width of FDECP-T ≈ 500 feet)
(width of FDECP-T ≈ 500 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-T
                                   46.440739
                                  -87.652715
Ore drying
                                   46.440723
                                  -87.652247
PI-T
                                   46.439810
                                  -87.650018
PH-T
                                   46.439372
                                  -87.650152
FDECP-T1
                                   46.437826
                                  -87.652762
FDECP-T2
                                   46.435940
                                  -87.642519

                                 Minorca Mine
Minorca Mine: Site Layout View

Minorca Mine: EPG Location View

(width of FDECP-MM ≈ 300 feet)
(width of FDECP-MM ≈ 300 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-MM
                                   47.561752
                                  -92.521476
PI-MM
                                   47.560920
                                  -92.521849
PH-MM
                                   47.560274
                                  -92.521486
FDECP-MM1
                                   47.555483
                                  -92.519306
FDECP-MM2
                                   47.558185
                                  -92.520467

                                United Taconite
United Taconite: Site Layout View

United Taconite: EPG Location View

(width of FDECP-UT ≈ 300 feet)
(width of FDECP-UT ≈ 300 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-UT
                                   47.354400
                                  -92.576050
PI-UT
                                   47.352078
                                  -92.576428
PH-UT
                                   47.351716
                                  -92.577405
FDECP-UT1
                                   47.355673
                                  -92.579453
FDECP-UT2
                                   47.356880
                                  -92.577675

                                    Minntac
Minntac: Site Layout View

Minntac: EPG Location View

(width of FDECP-US M ≈ 350 feet)
(width of FDECP-US M ≈ 350 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-US M
                                   47.561875
                                  -92.639217
PI-US M
                                   47.567420
                                  -92.627351
PH-US M
                                   47.566158
                                  -92.622651
FDECP-US M1
                                   47.561917
                                  -92.634701
FDECP-US M2
                                   47.563213
                                  -92.635088

                               Hibbing Taconite
Hibbing Taconite: Site Layout View

Hibbing Taconite: EPG Location View

(width of FDECP-H ≈ 250 feet)
(width of FDECP-H ≈ 250 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-H
                                   47.476813
                                  -92.969077
PI-H
                                   47.478451
                                  -92.967230
PH-H
                                   47.477112
                                  -92.967528
FDECP-H1
                                   47.475686
                                  -92.972148
FDECP-H2
                                   47.476110
                                  -92.968726

                                    Keetac
Keetac: Site Layout View

Keetac: EPG Location View

(width of FDECP-K ≈ 450 feet)
(width of FDECP-K ≈ 450 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-K
                                   47.413422
                                  -93.063711
PI-K
                                   47.412467
                                  -93.059638
PH-K
                                   47.411441
                                  -93.060531
FDECP-K1
                                   47.410896
                                  -93.064625
FDECP-K2
                                   47.411057
                                  -93.062707

                                  Northshore
Northshore: Site Layout View

Northshore: EPG Location View

(width of FDECP-N ≈ 250 feet)
(width of FDECP-N ≈ 250 feet)
                                      Pin
                                   Latitude
                                   Longitude
OCH-N
                                   47.290518
                                  -91.263702
PI-N
                                   47.285706
                                  -91.262978
PH-N
                                   47.284673
                                  -91.264012
FDECP-N1
                                   47.282767
                                  -91.263375
FDECP-N2
                                   47.285821
                                  -91.259879