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Subpart Z—Phosphoric Acid Production

§98.260 Definition of the source category.

The phosphoric acid production source category consists of facilities with a wet-process 

phosphoric acid process line used to produce phosphoric acid. A wet-process phosphoric acid 

process line is the production unit or units identified by an individual identification number in an 

operating permit and/or any process unit or group of process units at a facility reacting phosphate 

rock from a common supply source with acid.

§98.261 Reporting threshold.

You must report GHG emissions under this subpart if your facility contains a phosphoric 

acid production process and the facility meets the requirements of either §98.2(a)(1) or (a)(2).

§98.262 GHGs to report.

(a) You must report CO2 process emissions from each wet-process phosphoric acid 

process line.

(b) You must report under subpart C of this part (General Stationary Fuel Combustion 

Sources) the emissions of CO2, CH4, and N2O from each stationary combustion unit following 

the requirements of subpart C of this part.

§98.263 Calculating GHG emissions.

You must calculate and report the annual process CO2 emissions from each wet-process 

phosphoric acid process line using the procedures in either paragraph (a) or (b) of this section.

(a) Calculate and report under this subpart the process CO2 emissions by operating and 

maintaining a CEMS according to the Tier 4 Calculation Methodology specified in §98.33(a)(4) 

and all associated requirements for Tier 4 in subpart C of this part (General Stationary Fuel 

Combustion Sources).
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(b) Calculate and report under this subpart the process CO2 emissions using the 

procedures in paragraphs (b)(1) and (b)(2) of this section.

(1) Calculate the annual CO2 mass emissions from each wet-process phosphoric acid 

process line using the methods in paragraphs (b)(1)(i) or (ii) of this section, as applicable.

(i) If your process measurement provides the inorganic carbon content of phosphate rock 

as an output, calculate and report the process CO2 emissions from each wet-process phosphoric 

acid process line using Equation Z-1a of this section:

where:

Em = Annual CO2 mass emissions from a wet-process phosphoric acid process line m 

according to this Equation Z-1a (metric tons).

ICn,i = Inorganic carbon content of a grab sample batch of phosphate rock by origin i 

obtained during month n, from the carbon analysis results (percent by weight, expressed as a 

decimal fraction).

Pn,i = Mass of phosphate rock by origin i consumed in month n by wet-process 

phosphoric acid process line m (tons).

z = Number of months during which the process line m operates.

b = Number of different types of phosphate rock in month, by origin. If the grab sample 

is a composite sample of rock from more than one origin, b = 1.

2000/2205 = Conversion factor to convert tons to metric tons.

44/12 = Ratio of molecular weights, CO2 to carbon.
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(ii) If your process measurement provides the CO2 content directly as an output, calculate 

and report the process CO2 emissions from each wet-process phosphoric acid process line using 

Equation Z-1b of this section:

where:

Em = Annual CO2 mass emissions from a wet-process phosphoric acid process line m 

according to this Equation Z-1b (metric tons).

CO2n,i = Carbon dioxide content of a grab sample batch of phosphate rock by origin i 

obtained during month n (percent by weight, expressed as a decimal fraction).

Pn,i = Mass of phosphate rock by origin i consumed in month n by wet-process 

phosphoric acid process line m (tons).

z = Number of months during which the process line m operates.

b = Number of different types of phosphate rock in month, by origin. If the grab sample 

is a composite sample of rock from more than one origin, b=1.

2000/2205 = Conversion factor to convert tons to metric tons.

(2) You must determine the total emissions from the facility using Equation Z-2 of this 

section:

Where:

CO2 = Annual process CO2 emissions from phosphoric acid production facility (metric 

tons/year).
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Em = Annual process CO2 emissions from wet-process phosphoric acid process line m 

(metric tons/year).

p = Number of wet-process phosphoric acid process lines.

(c) If GHG emissions from a wet-process phosphoric acid process line are vented through 

the same stack as any combustion unit or process equipment that reports CO2 emissions using a 

CEMS that complies with the Tier 4 Calculation Methodology in subpart C of this part (General 

Stationary Fuel Combustion Sources), then the calculation methodology in paragraph (b) of this 

section shall not be used to calculate process emissions. The owner or operator shall report under 

this subpart the combined stack emissions according to the Tier 4 Calculation Methodology in 

§98.33(a)(4) and all associated requirements for Tier 4 in subpart C of this part.

§98.264 Monitoring and QA/QC requirements.

(a) You must obtain a monthly grab sample of phosphate rock directly from the rock 

being fed to the process line before it enters the mill using one of the following methods. You 

may conduct the representative bulk sampling using a method published by a consensus 

standards organization, or you may use industry consensus standard practice methods, including 

but not limited to the Phosphate Mining States Methods Used and Adopted by the Association of 

Fertilizer and Phosphate Chemists (AFPC). If phosphate rock is obtained from more than one 

origin in a month, you must obtain a sample from each origin of rock or obtain a composite 

representative sample.

(b) You must determine the carbon dioxide or inorganic carbon content of each monthly

grab sample of phosphate rock (consumed in the production of phosphoric acid). You may use a 

method published by a consensus standards organization, or you may use industry consensus 
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standard practice methods, including but not limited to the Phosphate Mining States Methods 

Used and Adopted by AFPC.

(c) You must determine the mass of phosphate rock consumed each month (by origin) in 

each wet-process phosphoric acid process line. You can use existing plant procedures that are 

used for accounting purposes (such as sales records) or you can use data from existing 

monitoring equipment that is used to measure total mass flow of phosphorous-bearing feed under 

40 CFR part 60 or part 63.

§98.265 Procedures for estimating missing data.

A complete record of all measured parameters used in the GHG emissions calculations is 

required. Therefore, whenever a quality-assured value of a required parameter is unavailable, a 

substitute data value for the missing parameter must be used in the calculations as specified in 

paragraphs (a) and (b) of this section.

(a) For each missing value of the inorganic carbon content or CO2 content of phosphate 

rock (by origin), you must use the appropriate default factor provided in Table Z-1 of this 

subpart. Alternatively, you must determine a substitute data value by calculating the arithmetic 

average of the quality-assured values of inorganic carbon contents or CO2 contents of phosphate 

rock of origin i (see Equation Z-1a or Z-1b of this subpart) from samples immediately preceding 

and immediately following the missing data incident. If no quality-assured data on inorganic 

carbon contents or CO2 contents of phosphate rock of origin i are available prior to the missing 

data incident, the substitute data value shall be the first quality-assured value for inorganic 

carbon contents or CO2 contents for phosphate rock of origin i obtained after the missing data 

period.
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(b) For each missing value of monthly mass consumption of phosphate rock (by origin), 

you must use the best available estimate based on all available process data or data used for 

accounting purposes.

§ 98.266 Data reporting requirements.

In addition to the information required by § 98.3(c), each annual report must contain the 

information specified in paragraphs (a) through (f) of this section.

(a) Annual phosphoric acid production, by origin of the phosphate rock (tons).

(b) Annual phosphoric acid production capacity (tons).

(c) Annual arithmetic average percent inorganic carbon or carbon dioxide in phosphate 

rock from monthly records (percent by weight, expressed as a decimal fraction).

(d) Annual phosphate rock consumption from monthly measurement records by origin 

(tons).

(e) If you use a CEMS to measure CO2 emissions, then you must report the information 

in paragraphs (e)(1) and (e)(2) of this section.

(1) The identification number of each wet-process phosphoric acid process line.

(2) The annual CO2 emissions from each wet-process phosphoric acid process line 

(metric tons) and the relevant information required under 40 CFR 98.36 (e)(2)(vi) for the Tier 4 

Calculation Methodology.

(f) If you do not use a CEMS to measure emissions, then you must report the information 

in paragraphs (f)(1) through (9) of this section.

(1) Identification number of each wet-process phosphoric acid process line.

(2) Annual CO2 emissions from each wet-process phosphoric acid process line (metric 

tons) as calculated by either Equation Z-1a or Equation Z-1b of this subpart.
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(3) Annual phosphoric acid production capacity (tons) for each wet-process phosphoric 

acid process line.

(4) Method used to estimate any missing values of inorganic carbon content or carbon 

dioxide content of phosphate rock for each wet-process phosphoric acid process line.

(5) Reserved.

(6) Reserved.

(7) Number of wet-process phosphoric acid process lines.

(8) Number of times missing data procedures were used to estimate phosphate rock 

consumption (months), inorganic carbon contents of the phosphate rock (months), and CO2

contents of the phosphate rock (months).

(9) Annual process CO2 emissions from phosphoric acid production facility (metric tons).

§ 98.267 Records that must be retained.

In addition to the records required by § 98.3(g), you must retain the records specified in 

paragraphs (a) through (d) of this section for each wet-process phosphoric acid production 

facility.

(a) Monthly mass of phosphate rock consumed by origin (tons).

(b) Records of all phosphate rock purchases and/or deliveries (if vertically integrated with 

a mine).

(c) Documentation of the procedures used to ensure the accuracy of monthly phosphate 

rock consumption by origin.

(d) Verification software records. You must keep a record of the file generated by the 

verification software specified in § 98.5(b) for the applicable data specified in paragraphs (d)(1) 
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through 4) of this section. Retention of this file satisfies the recordkeeping requirement for the 

data in paragraphs (d)(1) through (4) of this section.

(1) Inorganic carbon content of a grab sample batch of phosphate rock by origin obtained 

during month by wet-process phosphoric acid process line, from the carbon analysis results 

(percent by weight, expressed as a decimal fraction) (Equation Z-1a of § 98.263).

(2) Mass of phosphate rock by origin consumed in month by wet-process phosphoric acid 

process line (tons) (Equation Z-1a).

(3) Carbon dioxide content of a grab sample batch of phosphate rock by origin obtained

during month by wet-process phosphoric acid process line (percent by weight, expressed as a 

decimal fraction) (Equation Z-1b of § 98.263).

(4) Mass of phosphate rock by origin consumed in month by wet-process phosphoric acid 

process line (tons) (Equation Z-1b).

§98.268 Definitions.

All terms used in this subpart have the same meaning given in the Clean Air Act and 

subpart A of this part.

[74 FR 56374, Oct. 30, 2009, as amended at 78 FR 71965, Nov. 29, 2013]

Table Z-1 to Subpart Z of Part 98—Default Chemical Composition of Phosphate Rock by 

Origin

Origin

Total carbon

(percent by weight)

Central Florida 1.6

North Florida 1.76

North Carolina (Calcined) 0.76

Idaho (Calcined) 0.60
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Morocco 1.56