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PRO*^ 2020 National Emissions Inventory Technical Support Document: Industrial Processes - Mining and Quarrying ------- ------- EP A-454/R-23 -00 lbb March 2023 2020 National Emissions Inventory Technical Support Document: Industrial Processes - Mining and Quarrying U.S. Environmental Protection Agency Office of Air Quality Planning and Standards Air Quality Assessment Division Research Triangle Park, NC ------- Contents List of Tables i 28 Industrial Processes - Mining and Quarrying 28-1 28.1 Sector Descriptions and Overview 28-1 28.2 EPA-developed estimates 28-1 28.2.1 Activity data 28-1 28.2.2 Allocation procedure 28-2 28.2.3 Emission factors 28-5 28.2.4 Controls 28-8 28.2.5 Emissions 28-8 28.2.6 Example calculations 28-9 28.2.7 Improvements/Changes in the 2020 NEI 28-10 28.2.8 Puerto Rico and U.S. Virgin Islands 28-10 28.3 References 28-10 List of Tables Table 28-1: NAICS Codes for Metallic and Non-Metallic Mining 28-2 Table 28-2: Withheld data ranges and midpoints 28-4 Table 28-3: Example County Business Pattern for NAICS 2123 28-4 Table 28-4: Sample calculations for estimating PM25-PRI emissions from mining and quarrying 28-9 l ------- 28 Industrial Processes - Mining and Quarrying 28.1 Sector Descriptions and Overview Mining and quarrying activities produce particulate matter (PM) emissions due to the variety of processes used to extract the ore and associated overburden, including drilling and blasting, loading and unloading, and overburden replacement. Fugitive dust emissions for mining and quarrying operations are the sum of emissions from the mining of metallic and nonmetallic ores and coal. Each of these mining operations has specific emissions factors accounting for the different means by which the resources are extracted. 28.2 EPA-developed estimates Four specific activities are included in the emissions estimate for mining and quarrying operations: overburden removal, drilling and blasting, loading and unloading, and overburden replacement. Not included are the transfer and conveyance operations, crushing and screening operations, and storage since the dust emissions from these activities are assumed to be well controlled. Fugitive dust emissions for mining and quarrying operations are the sum of emissions from the mining of metallic and nonmetallic ores and coal. Emissions for each activity are calculated by multiplying the emissions factors by the activity data. 28.2.1 Activity data Activity data for this source category include state-level metallic and non-metallic (a.k.a. mineral) crude ore handled at surface mines from the U.S. Geologic Survey (USGS) [ref 1] and mine-specific coal production data for surface mines from the Energy Information Administration (EIA) [ref 2], Emissions are not estimated for underground mining given that emissions factors are calculated exclusively for surface activity. In some cases, the amount of mining waste is withheld for some states to avoid disclosing company proprietary data. To estimate state-level withheld waste data the fraction of crude ore production in the state is multiplied by the amount of waste data withheld at the national level. The national-level amount of waste withheld is calculated by subtracting all known state-level waste values (i.e. those that are not withheld) from the national-level waste value. Note that this calculation only needs to be completed for states where state-level mining waste data are withheld. (1) Where: Ws Wus Amount of metallic and non-metallic mining waste for state s, in metric tons Amount of metallic and non-metallic mining waste withheld at the national level, in a metric tons Amount of crude ore produced in state s, in metric tons 28-1 ------- Ous = Amount of crude ore produced at the national level, in metric tons The data on state-level mining production and waste is split into production and waste for metallic and nonmetallic ores using the fraction of national-level metallic and non-metallic ore production. Values are also converted from metric tons to short tons. Throughout the remainder of this document references to "ton(s)" refer to short tons, while metric tons will be explicitly labeled. MPU = (W, + 0,) X ^ x 1.1023 t07mefric ton (1) Where: MPt,s = Amount of mining material type t (i.e. either metallic or non-metallic ore) produced in state s, in tons Ws = Amount of total metallic and non-metallic mining waste for state s, in metric tons Os = Amount of crude ore produced in state s, in metric tons MPt,us = Amount of mining material type t produced at the national-level, in metric tons MPus = Total metallic and non-metallic ore production at the national level, in metric tons 28.2.2 Allocation procedure The state-level data on metallic and non-metallic mining materials (from Equation (2)) is distributed to the county level based on the proportion of employees in the metallic and non-metallic ore sectors (see Table 28-1 for a list of NAICS codes), from the U.S. Census Bureau County Business Patterns [ref 3], Separate fractions are determined for metallic ore mining employees and non-metallic ore mining employees in each county. Emptr EmpFractc = (2) Empts Where: EmpFract,c = The fraction of mining employees for material type t in county c Empt,c =The number of mining employees for material type t in county c Empts =The number of mining employees for material type t in state s Table 28-1: NAICS Codes for Metallic and Non-Metallic Mining NAICS Code Description 2122 Metal Ore Mining 212210 Iron Ore Mining 21222 Gold Ore and Silver Ore Mining 212221 Gold Ore Mining 212222 Silver Ore Mining 28-2 ------- NAICS Code Description 21223 Copper, Nickel, Lead, and Zinc Mining 212231 Lead Ore and Zinc Ore Mining 212234 Copper Ore and Nickel Ore Mining 21229 Other Metal Ore Mining 212291 Uranium-Radium-Vanadium Ore Mining 212299 All Other Metal Ore Mining 2123 Nonmetallic Mineral Mining and Quarrying 21231 Stone Mining and Quarrying 212311 Dimension Stone Mining and Quarrying 212312 Crushed and Broken Limestone Mining and Quarrying 212313 Crushed and Broken Granite Mining and Quarrying 212319 Other Crushed and Broken Stone Mining and Quarrying 21232 Sand, Gravel, Clay, and Ceramic and Refractory Minerals Mining and Quarrying 212321 Construction Sand and Gravel Mining 212322 Industrial Sand Mining 212324 Kaolin and Ball Clay Mining 212325 Clay and Ceramic and Refractory Minerals Mining 21239 Other Nonmetallic Mineral Mining and Quarrying 212391 Potash, Soda, and Borate Mineral Mining 212392 Phosphate Rock Mining 212393 Other Chemical and Fertilizer Mineral Mining 212399 All Other Nonmetallic Mineral Mining Due to concerns with releasing confidential business information, the CBP does not release exact numbers for a given NAICS code if the data can be traced to an individual business. Instead, a series of range codes is used. To estimate employment in counties and states with withheld data, the following procedure is used for NAICS code being computed. To gap-fill withheld state-level employment data: a. State-level data for states with known employment in each NAICS are summed to the national level. b. The total sum of state-level known employment from step a is subtracted from the national total reported employment for each NAICS in the national-level CBP to determine the employment total for the withheld states. c. Each of the withheld states is assigned the midpoint of the range code reported for that state. Table 28-2 lists the range codes and midpoints. d. The midpoints for the states with withheld data are summed to the national level. e. An adjustment factor is created by dividing the number of withheld employees (calculated in step b of this section) by the sum of the midpoints (step d). f. For the states with withheld employment data, the midpoint of the range for that state (step c) is multiplied by the adjustment factor (step e) to calculate the adjusted state-level employment for landfills. These same steps are then followed to fill in withheld data in the county-level business patterns. 28-3 ------- g. County-level data for counties with known employment are summed by state. h. County-level known employment is subtracted from the state total reported in state-level CBP (or, if the state-level data are withheld, from the state total estimated using the procedure discussed above). i. Each of the withheld counties is assigned the midpoint of the range code (Table 28-2). j. The midpoints for the counties with withheld data are summed to the state level. k. An adjustment factor is created by dividing the number of withheld employees (step h) by the sum of the midpoints (step j). I. For counties with withheld employment data, the midpoints (step i) are multiplied by the adjustment factor (step k) to calculate the adjusted county-level employment for landfills. Table 28-2: With leld data ranges and midpoints Employment Code Employment Range Midpoint A 0-19 10 B 20-99 60 C 100-249 175 E 250-499 375 F 500-999 750 G 1,000-2,499 1,750 H 2,500-4,999 3,750 1 5,000-9,999 7,500 J 10,000-24,999 17,500 K 25,000-49,999 37,500 L 50,000-99,999 75,000 M 100,000+ As an example, sample county CBP data for NAICS 2123 (Nonmetallic Mineral Mining and Quarrying) are provided in Table 28-3. The values in the table and subsequent steps are for demonstration purposes and are not representative of any specific NEI year or county. Table 28-3: Example County Business Pattern for NAICS 2123 County FIPS NAICS Employment Code Employment 001 2123 86 003 2123 19 005 2123 30 009 2123 B withheld 012 2123 A withheld 013 2123 505 015 2123 55 017 2123 60 019 2123 167 021 2123 72 023 2123 A withheld 025 2123 144 027 2123 43 28-4 ------- 1. The total number of employees reported at the county level is 1,181. 2. The state-level CBP reports 1,195 employees for NAICS 2123. This means that there are 14 employees withheld at the county level. 3. The counties with withheld data are assigned midpoints according to the employment codes. For example, County 009 is given a midpoint of 60 employees (since employment code B is 20- 99). 4. The sum of the midpoints for all withheld counties is 80 employees. 5. The adjustment factor is 14/80 = 0.175. 6. The adjusted employment for county 009 is 60 x 0.175 = 10.5 employees. Once county- and state-level metal and non-metal employment are known for each county, the ratio of county to state employees (from equation 3) is multiplied by the state-level metal and non-metal production (from equation 2) to calculate county-level production. Where: MPt c = MPt s x EmpFract c (2) MPt,c = Amount of mining material type t produced in county c, in tons MPt,s = Amount of mining material type t (i.e. either metallic or non-metallic ore) produced in state s, in tons EmpFract,c = The fraction of mining employees for material type t in county c 28.2.3 Emission factors Emissions factors are calculated separately for metallic ore mining, non-metallic ore mining, and coal mining and are provided in the "Wagon Wheel Emission Factor Compendium" on the 2020 NEI Supporting Data and Summaries site. This section describes those calculations and the relevant data sources. Metallic Ore Mining The emissions factor for metallic ore mining includes emissions from overburden removal, drilling and blasting, and loading and unloading activities, and are taken from emissions factors for copper ore mining from EPA's National Air Pollutant Emission Trends Procedures Document for 1900-1996 [ref 4]. The emissions factors are applied to all three activities with PM10/TSP ratios of 0.35 for overburden removal [ref 5], 0.81 for drilling and blasting [ref 6], and 0.43 for loading and unloading operations [ref 6], EFPMW,m = EF0 + (B x EFb) + EFi + EFd (3) Where: EFpMio,m = PM10-PRI metallic ore mining emissions factor, in Ibs./ton EF0 = PM10-PRI open pit overburden removal emissions factor for copper ore, in Ibs./ton B = Fraction of total ore production that is obtained by blasting at metallic ore mines 28-5 ------- EFb = PM10-PRI drilling/blasting emissions factor for copper ore, in Ibs./ton EFi = PM10-PRI loading emissions factor for copper ore, in Ibs./ton EFd = PM10-PRI truck dumping emissions factor for copper ore, in Ibs./ton Using values from the National Air Pollutant Emission Trends Procedures Document for 1900-1996, Table 3.1-3[ref 4], the PM10-PRI emissions factor is calculated as: 0.0548 lbs/ton = 0.0003 + (0.57625 X 0.0008) + 0.022 + 0.032 (5a) The PM25-PRI emissions factor is assumed to be 12.5% of the PM10-PRI emissions factor. EFPM25,m — EFPMW,m X 0.125 (4) 0.0069 = 0.0548 x 0.125 (6a) Where: EFpM25,m = PM25-PRI metallic ore mining emissions factor, in Ibs./ton EFpMio,m = PM10-PRI metallic ore mining emissions factor, in Ibs./ton Non-Metallic Ore Mining The emissions factor for non-metallic ore mining includes overburden removal, drilling and blasting, and loading and unloading activities. The emissions factor is based on western surface coal mining operations from AP-42 [ref 7] and a PM10/TSP ratio. EFPM10,nm = EFv + (P x EFr) + EFa + (°-5 x (EFe + EFt)) (5) Where: EFpMio,nm = PM10-PRI non-metallic ore mining emissions factor, in Ibs./ton EFV = PM10-PRI open pit overburden removal emissions factor at western surface coal mining operations, in Ibs./ton D = fraction of total ore production that is obtained by blasting at non-metallic ore mines EFr = PM10-PRI drilling/blasting emissions factor at western surface coal mining operations, in Ibs./ton EFa = PM10-PRI loading emissions factor at western surface coal mining operations, in Ibs./ton EFe = PM10-PRI truck unloading: end dump-coal emissions factor at western surface coal mining operations, in Ibs./ton EFt = PM10-PRI truck unloading: bottom dump-coal emissions factor at western surface coal mining operations, in Ibs./ton Applying the TSP emissions factors developed for western surface coal mining operations from AP-42 [ref 7] and a PM10/TSP ratio of 0.4 [ref 8] yields the following non-metallic ore mining emissions factor: 28-6 ------- 0.293 lbs./ton = 0.225 + (0.61542 X 0.00005) + 0.05 + 0.5 (0.0035 + 0.033) ( ' The PM25-PRI emissions factor is assumed to be 12.5% of the PM10-PRI emissions factor. EFpM25,nm ~ * 0.125 (6) 0.037 lbs/ton = 0.293 X 0.125 (8a) Where: EFpM25,nm = PM25-PRI non-metallic ore mining emissions factor, in Ibs./ton EFpMio,nm = PM10-PRI non-metallic ore mining emissions factor, in Ibs./ton Coal Mining The emissions factor for coal mining includes overburden removal, drilling and blasting, loading, and unloading and overburden replacement activities. The amount of overburden material handled is assumed to equal ten times the quantity of coal mined, and coal unloading is assumed to split evenly between end-dump and bottom-dump operations. The emissions factor is based on the PMio emissions factors developed for western surface coal mining operations from AP-42 [ref 7], EFpmio.co = (10 X (EFt0 + EFor + EFdt)) + EFV + EFr + EFa + (0.5 X (EFe + EFt)) (7) Where: EFpMio,co= PM10-PRI coal mining emissions factor, in Ibs./ton EFt0 = PM10-PRI emissions factor for truck loading overburden at western surface coal mining operations, in Ibs./ton of overburden EFor = PM10-PRI emissions factor for overburden replacement at western surface coal mining operations, in Ibs./ton of overburden EFdt = PM10-PRI emissions factors for truck unloading: bottom dump-overburden at western surface coal mining operations, in Ibs./ton of overburden EFV = PM10-PRI open pit overburden removal emissions factor at western surface coal mining operations, in Ibs./ton EFr = PM10-PRI drilling/blasting emissions factor at western surface coal mining operations, in Ibs./ton EFa = PM10-PRI loading emissions factor at western surface coal mining operations, in Ibs./ton EFe = PM10-PRI truck unloading: end dump-coal emissions factor at western surface coal mining operations, in Ibs./ton EFt = PM10-PRI truck unloading: bottom dump-coal emissions factor at western surface coal mining operations, in Ibs./ton Applying the PM10-PRI emissions factors developed for western surface coal mining operations [ref 7] yields the following coal mining emissions factor: 28-7 ------- 0.513 lbs/ton = (10 X (0.015 + 0.001 + 0.006)) + 0.225 + 0.00005 + 0.05 + (0.5 X (0.0035 + 0.033)) (9a) The PM25-PRI emissions factor is assumed to be 12.5% of the PM10-PRI emissions factor. EFpM25,co — EFiq,co x 0.125 (8) Where: EFpm25,co= PM25-PRI coal mining emissions factor, in Ibs./ton EFpMio,co= PM10-PRI coal mining emissions factor, in Ibs./ton PM-FILand PM2.5-PRI Emissions Factors PM-FIL emissions factors are assumed to be the same as PM-PRI emissions factors. In reality, there is a small amount of PM-CON emissions included in the PM-PRI emissions, but insufficient data exists to estimate the PM-CON portion. In 2006, the EPA adopted new PM2.5/PM10 ratios for several fugitive dust categories and concluded that the PM2.5/PM10 ratios for fugitive dust categories should be in the range of 0.1 to 0.15 [ref 9], Consequently, a ratio of 0.125 was applied to the PM10 emissions factors to estimate PM2.5 emissions factors for mining and quarrying. A summary of emissions factors is are provided in the "Wagon Wheel Emission Factor Compendium" on the 2020 NEI Supporting Data and Summaries site. 28.2.4 Controls There are no controls assumed for this category. 28.2.5 Emissions Emissions from mining and quarrying are calculated by multiplying the amount of mining material produced (from equation 4 for metallic and non-metallic mining, and from the EIA [ref 2] for coal) by an emissions factor (from Table 4-129). Et,P,c = Annual emissions of pollutant p from mining material type t in county c, in lbs. EFt/P = Emissions factor for pollutant p from mining material type t, in Ibs./ton of material produced MPt,c = Amount of mining material type t produced in county c, in tons The final step of the process is to sum the mining emissions estimates for each pollutant in each county. Emissions estimates are then converted from pounds to tons. Ep,t,c = EFt,p x MPtiC (9) Where: 28-8 ------- AEPiC = ^ EPitiC X 0.0005 ton/lb (10) Where: AEP/C = Annual emissions of pollutant p in county c, in tons Et,P,c = Annual emissions of pollutant p from mining material type t in county c, in lbs. 28.2.6 Example calculations The steps below provide sample calculations to determine the PM25-PRI emissions from mining and quarrying operations. Constant emissions factor calculations that are used in all counties are not repeated here. Table 28-4 provides a summary of these calculations. Note that equations 5-10 produce constant emissions factors that are used in all counties. Those calculations are not repeated here. The values in these equations are demonstrating program logic and are not representative of any specific NEI year or county. Ta )le 28-4: Sample calculations for estimating PM25-PRI emissions from mining and quarrying Eq. # Equation Values Result 1 ws=7T-*wus uus N/A Waste data is not withheld for the state 2 MPt,s f ¦ MPt.us ~ « + « X MPUS v 1 1 n?3 short ton/ /metric ton (3,720 + 42,900) X (2,660,000 -h 5,060,000) v 1 If)?'1? t°n/ /metric ton 27,015 thousand tons metallic ore in the state (3,720 + 42,900) X (2,400,000 -h 5,060,000) X 1.1023 ton/metric ton 24,375 thousand tons non-metallic ore in the state 3 „ „ EmPt,c EmpFract c — Empt>s 25 metallic mining employees in the count Metallic employee fraction of 0.015 1,662 metallic mining employees in the sta 94 nonmetallic mining employees in the cc Nonmetallic employee fraction of 0.069 1,354 nonmetallic mining employees in the 4 MPt c = MPt s x EmpFract c 27,015 tons x 0.015 27,015 thousand tons metallic ore 24,375 tons x 0.069 112 thousand tons non- metallic ore 28-9 ------- Eq. # Equation Values Result 0.0068 lbs-/ton X 27,015,167 tons 184,922.19 lbs. PM25-PRI emissions from metallic ore 11 Ep,t,c = EFt,p X MPt,c 0.037 lbs-/ton X 112,039 tons 4,107.38 lbs. PM25-PRI emissions from non-metallic ore 0.064^s/ton x 0 tons 0 lbs. PM25-PRI from coal mining 12 AEpc = EPiC x 0.0005 short ton/lb 184,922.19 lbs. +4,107.38 lbs. +0 lbs. x 0.0005 ton/lb 95 tons PM25- PRI from mining and quarrying 28.2.7 Improvements/Changes in the 2020 NEI No changes were made to this category. Activity data was updated to reflect the most recent, best available data at the time of the NEI. 28.2.8 Puerto Rico and U.S. Virgin Islands Since insufficient data exists to calculate emissions for the counties in Puerto Rico and the US Virgin Islands, emissions are based on two proxy counties in Florida: 12011, Broward County for Puerto Rico and 12087, Monroe County for the US Virgin Islands. The total emissions in tons for these two Florida counties are divided by their respective populations creating a tons per capita emissions factor. For each Puerto Rico and US Virgin Island county, the tons per capita emissions factor is multiplied by the county population (from the same year as the inventory's activity data) which served as the activity data. In these cases, the throughput (activity data) unit and the emissions denominator unit are "EACH". 28.3 References 1. U.S. Geologic Survey. Minerals Yearbook 2015. 2. U.S. Department of Energy, Energy Information Administration. "Detailed data from the EIA-7A and the U.S. Mine Safety and Health Administration", data pulled for year 2020. 3. U.S. Census Bureau. 2020 County Business Patterns. 4. U.S. Environmental Protection Agency. 1998. National Air Pollutant Emission Trends Procedure Document for 1900-1996, EPA-454/R-98-008. 5. U.S. Environmental Protection Agency, AP-42, Fifth Edition, Volume 1, Chapter 13: Miscellaneous Sources, Section 13.2.4: Aggregate Handling and Storage Piles. 28-10 ------- 6. U.S. Environmental Protection Agency. 1986. Generalized Particle Size Distributions for Use in Preparing Size-Specific Particulate Emissions Inventories, EPA-450/4-86-013. 7. U.S. Environmental Protection Agency, AP-42, Fifth Edition, Volume 1, Chapter 11: Mineral Products Industry, Section 11.9: Western Surface Coal Mining. 8. United States Environmental Protection Agency, AIRS Facility Subsystem Source Classification Codes and Emission Factor Listing for Criteria Air Pollutants, EPA-450/4-90-003, March 1990. 9. Midwest Research Institute. 2006. Background Document for Revisions to Fine Fraction Ratios Used for AP-42 Fugitive Dust Emission Factors. MRI Project No. 110397. 28-11 ------- United States Office of Air Quality Planning and Standards Publication No. EPA-454/R-23-001bb Environmental Protection Air Quality Assessment Division March 2023 Agency Research Triangle Park, NC ------- |