1

TECHNICAL MEMORANDUM

TO: Tina Ndoh , U

. S

. EPA/OAQPS/SPPD

- Minerals and Manufacturing Group

FROM: Eastern Research Group, Inc.

DATE: June 3 , 201 3

SUBJECT: Applicability Clarifications to the Phosphoric Acid Manufacturing Source

Category

1.0 INTRODUCTION
The definitions for wet

- process phosphoric acid process line and superphosphoric acid process line provide a list of emission points, whose emissions must be included when determining compliance with the emission limits of the P hosphoric A cid M anufacturing NESHAP ( 40 CFR part 63, subpart AA) and Phosphoric Acid Manufacturing NSPS ( 40 CFR part 60, subparts T and U)

. W e determined that it was unclear whether emissions from clarifiers and defluorination systems at wet

- process phosphoric acid (WPPA ) process lines, and oxidation reactors at superphosphoric acid (SPA) process lines, were regulated by the Phosphoric Acid Manufacturing NESHAP and NSPS

. These emission points are common to phosphoric acid and superphosphoric acid process es but were not clearly listed as applicable to subpart s AA , T, and
U

. This memorandum examines how oxidation reactors, defluorination processes , and clarifiers are incorporated into WPPA or SPA process lines and analyzes the available data in relation to emissi on limits.

2.0 OXIDATION REACTORS Oxidation reactors are used to remove organics by mixing SPA with nitric acid, ammonium nitrate, or potassium permanganate. Four facilities currently use oxidation reactors and i nformation provided for the o xidation processes at these facilities included sufficient d etail that indicated the processes are integrated into the SPA process line and thus part of their typical operations. In fact, one facility already duct s oxidation reactor emissions through the same stack

as SPA em issions and thus oxidation reactor emissions were included in past performance tests.2

As part of the section 114 requests, test data were provided by three of the four facilities for their oxidation processes. 1 We evaluated the inclusion of hydrogen fluoride (HF) emissions or total fluoride (TF) emissions , if HF data were not available, from oxidation reactors to determine if facilities currently using an oxidation process would be affected by this clarification for compliance purposes. Simpl ot Don operates an oxidation reactor and its emissions are currently controlled by the same control device as their SPA process. Therefore, this facility has already shown it can achieve compliance as emis sions for EP

- 401 are below SPA emission limits. PC S White Springs has two distinct SPA process lines ( 36 and 70) and an oxidation

reactor process line ( 61) which is associated with SPA process line 36. Test data was available for all three processes , although it was noted that process line 36 was not oper ating with both of its evaporators. Because both evaporators were not operating, the emissions were not expected to be at their expected maximum value. Summing the total fluoride emissions f rom process lines 36 and 61 may not provide an accurate picture of the emissions for compliance purposes, so test data for process line 70 was used in place of line 36 (total fluoride emission for process line 70 were greater than process line 36). When the total fluoride emissions for process lines 61 and 70 are summed , this summation value fall s below the current SPA emission limit , therefore we determined that the PCS White Springs combined emissions would meet the SPA process line limit. Agrium Nu

- West also incorporates an oxidation reactor into their SPA process. Emissions from oxidation reactor feed tanks are currently controlled by the main SPA scrubber (EP

- 522) but the oxidation reactor itself (EP

- 541) is not controlled by this scrubber. Test data

were pr ovided for both emission points

. The oxidation reactor HF emissions (EP

- 541) were much higher than HF emissions from the SPA scrubber, and emissions from EP

- 541 exceed the proposed HF limit. This may be due to the fact the oxidation reactor emissions are u ncontrolled. Because the SPA process line exceeds the HF limit, costs were estimated to reduce the oxidation reactor emissions; this discussion is presented in a separate memo randum

. 2 While Agrium Nu

West may incur a cost to comply with the proposed HF lim it due to the clarification that emissions from oxidation reactors must be included with SPA process line emissions, it would be minimal.3

3.0 DEFLUORINATION Defluorination of phosphoric acid is performed using diatomaceous earth for at least two facilities. D efluorination processes were identified for Agrium Nu

- West and Simplot Don

. Emissions t est data was not provided by facilities with these operations and limited information was available on the emissions expected from these processes . Simplot Don did provi de details on their operations, but this information was classified as confidential business information ( CBI ) . We ca n , however, state that the defluorination process es are fed by the phosphoric acid
process line and are part of the typical operations at t he facilit ies

.

4.0 CLARIFIERS
Clarifiers are used at most phosphoric acid facilities as an additional separation step after evaporators. The clarifiers separate the phosphoric acid slurry into a lighter stream and a heavier stream. The lighter stream from a clarifier continues downstream (e.g., sent to the next evaporator in the series). The heavier stream from a clarifier is recycled back to the process upstream of the clarifier for further processing (e.g., to the reactor or filter). It is not uncommon for facilities to have several clarifiers in their process and their use is part of their typical WPPA process line operations

. When reviewing facility data, it was also noted that several facilities already includ e clarifier emissions when determining complia nce with subpart AA emission limits. There are two facilities, however, that do not include emissions from clarifiers when determining compliance and instead route their clarifier emissions to a scrubber separate from the main WPPA process line scrubbers. These two facilities are Mosaic New Wales and Mosaic Bartow. Emissions data were provided by Mosaic New Wales (EP

- 12 and EP

- 22) and Mosaic Bartow (EP

- 06) for their clarifiers. 1 Including emissions from clarifiers would not affect each facility’s ability to meet the subpart AA emission limits, based on the data available.

5.0 CONCLUSION Phosphoric acid facility operations were reviewed in detail, and i n each instance the oxidation reactors , defluorination process, and clarifiers were included as a typical part of the WPPA or SPA process line

. Several facilities already include emissions from these emission points when determining compliance with the Phosphoric Acid Manufacturing NESHAP or NSPS

. When emissions data were available to analyze, e ach facili ty’s emissions w ere also below the applicable WPPA or SPA emission limit when emissions from oxidation reactor s or clarifiers4

were included , except for one facility’s oxidation reactor

. The intention of the current regulations was not to exclude emissions from certain emission points when facilities were determining compliance for WPPA or SPA process lines. Therefore, the clarifications provided to the process line definitions will make this easier to understand and ensure that all emission points related to a process line will be accounted for in the future.

6.0 REFERENCES
1. Eastern Research Group, Inc. “ Emissions Data Used in Residual Risk Modeling: Phosphoric Acid and Phosphate Fertilizer Production Source Categories

. ” Docket ID : EPA

- HQ

- OAR

- 2012

- 0522. August 2014

. 2

. Eastern Research Group, Inc. “ Control Costs and Emissions Reductions for Phosphoric Acid and Phosphate Fertilizer Production Source Categories

. ” Docket ID: EPA

- HQ

OAR

- 2012

- 0522. June 2014

.