TECHNICAL MEMORANDUM

TO: Tina Ndoh, U.S. EPA/OAQPS/SPPD - Minerals and Manufacturing Group

FROM: Eastern Research Group, Inc.

DATE: June 2, 2014

SUBJECT: Control Costs and Emissions Reductions for Phosphoric Acid and Phosphate 

Fertilizer Production Source Categories

The U.S. Environmental Protection Agency (EPA), under section 112 of the Clean Air 

Act (CAA), is required to establish maximum achievable control technology (MACT) standards 

for phosphoric acid manufacturing plants (40 CFR part 63, subpart AA) and phosphate fertilizer 

production plants (40 CFR part 63, subpart BB) source categories. This memorandum documents 

the control costs and emissions reductions associated with proposed subparts AA and BB. The 

following is an outline of the memorandum:

1.0 Introduction

2.0 Control Costs for Proposed Limits

2.1 Beyond-the-Floor Mercury Limit for Phosphate Rock Calciners

2.2 Hydrogen Fluoride Limit Applicability for Oxidation Reactors, 

Defluorination Processes, and Clarifiers

3.0 Testing and Monitoring Costs

4.0 References

1.0 INTRODUCTION

As part of the risk and technology review required under section 112 of the Clean Air 

Act, MACT and beyond-the-floor (BTF) limits were calculated for mercury (Hg) from phosphate 

rock calciners regulated under subpart AA.1 It was determined that the one facility currently 

operating phosphate rock calciners would likely be required to install controls in order to comply 

with the calculated limits. EPA also determined that clarification of the applicability 

requirements for subpart AA and BB was necessary. As a result of the clarifications, it was 

assumed that one facility would be required to route previously uncontrolled emissions to an 

existing control device. This memorandum describes the methodologies for estimating costs and 

the associated emissions reductions as a result of facilities complying with the proposed emission 

1
limits and clarifications. Cost estimates for the revised testing and monitoring requirements 

included in the proposed rule are also provided.

The following assumptions were applied throughout this analysis. For all cost estimates, 

an annual operating time of 8,760 hours was used to determine the maximum cost a facility 

would incur. For most equipment installations, an equipment life of 20 years and a 7 percent 

discount rate was used to calculate capital recovery factors (CRF). All facilities were assumed to 

have adequate space to install additional emissions control equipment, and installation would not 

cause a production loss and could be completed during a routine maintenance outage. All costs 

are presented in 2013 dollars. For the cost analyses, only currently operating sources were 

considered as no new facilities are anticipated to be built in the near future.

2.0 CONTROL COSTS FOR PROPOSED LIMITS

2.1 Beyond-the-Floor Mercury Limit for Phosphate Rock Calciners

A BTF limit for Hg is proposed for phosphate rock calciners. In order to meet this BTF 

limit, three methods of control were evaluated: installation of a fixed-bed (FB) carbon adsorption 

system, installation of an activated carbon injection (ACI) system prior to an existing wet 

electrostatic precipitator (WESP), and installation of ACI followed by a fabric filter to collect the 

carbon. Two variations on the application of ACI were evaluated for the phosphate rock 

calciners because the moisture content of the stack gas (approximately 30 percent) may be too 

high to effectively use a fabric filter. Fabric filters are known to plug excessively when used in a

high moisture application. 

Carbon adsorption in a FB with pelletized carbon was chosen for this particular 

application based on information available from industrial applications.

2,3 Because a WESP is 

currently installed after each of the six phosphate rock calciners, the option to use ACI ahead of 

the WESP was also evaluated. Although there are no known applications with this combination 

of controls, there is control effectiveness information available for ACI followed by an 

electrostatic precipitator,2,4 therefore, this may be a potential control option for the calciners. For 

this analysis, we assumed the currently installed WESPs have the capacity to capture the 

additional particulate created by the ACI, however data are not available to support this 

assumption. Additionally, installation of a fabric filter after ACI was evaluated so that a 

representative range of control and cost options were considered. 

2
To comply with the BTF limit, Hg emissions from the six phosphate rock calciners would 

need to be reduced by 86 percent. The associated emissions reductions and cost effectiveness 

were calculated based on the control technologies achieving an 86 percent reduction. The full 

BTF cost calculation methodology is presented in a separate memorandum,

1 a summary is 

provided in Table 2.1.

Table 2.1. Costs and emissions reduction for complying with the BTF Hg limit for phosphate rock 

calciners.

BTF Scenario Total Capital 

Investment (TCI)

Total Annual 

Cost (TAC)

Hg 

Emissions 

Reduction

(lbs/yr)a

Cost 

Effectiveness 

($/lb of Hg

Removed)

FB Carbon Adsorption $4,900,000 $1,200,000 145 $8,000

ACI (using existing WESP) $6,500,000 $1,800,000 145 $12,100

ACI with Fabric Filter $16,500,000 $2,500,000 145 $17,100

Notes: 

(a) Mercury reductions are based upon test results using US EPA Method 30B. 

2.2 Hydrogen Fluoride Limit Applicability for Oxidation Reactors, Defluorination Processes, 

and Clarifiers

Wet-process phosphoric acid (WPPA) and superphosphoric acid (SPA) process line 

definitions were revised to specify that emissions from oxidation reactors, defluorination 

processes, and clarifiers must be included when determining compliance with hydrogen fluoride 

(HF) limits. Some facilities were not previously including emissions from these emission 

sources, as was the intention of subpart AA. The cost impact and emissions reduction associated 

with the subpart AA applicability clarifications were evaluated.

Oxidation reactors are used to remove organics by mixing SPA with nitric acid, 

ammonium nitrate, or potassium permanganate. Oxidation is used in the production of SPA at 

four facilities. The inclusion of emissions from oxidation reactors was evaluated to determine if 

facilities currently using oxidation would meet the proposed HF limit for SPA process lines. 

Based on the available HF data, three of the facilities were below the HF limit when the 

emissions associated with oxidation reactors were added to emissions of applicable equipment 

(e.g., evaporators) at SPA lines. In certain instances, facilities already duct oxidation reactor 

emissions through a common SPA emission point and thus oxidation reactor emissions would 

have been included in past performance tests. However, the oxidation reactor at Agrium Nu3
West (EP-541) is not controlled and according to HF data in 2014, the combined emissions from 

the SPA emission point (EP-522) and EP-541 would exceed the HF limit. 

Agrium Nu-West’s SPA process line was examined to determine their potential control 

options. One option would be to install a new wet scrubber to control emissions from the 

oxidation reactor (EP-541). However, the volumetric flow rate for EP-541 varies from about 600 

to 1,300 acfm and EP-522, which is currently controlled by a wet scrubber, has a volumetric 

flow rate of 6,500 to 9,500 acfm. Therefore, a second option is to duct the oxidation reactor 

emissions to the existing wet scrubber for EP-522. The combined volumetric flow rate would not 

change significantly and it is expected the existing wet scrubber would be able to control 

emissions from both emission points without modification. The Agrium Nu-West SPA plot plan

was reviewed to determine if EP-522 and EP-541 were in close enough proximity to make this a 

practical option. Each emission point was identified on the plot plan and, using Google Earth, it 

was estimated that approximately 400 feet of ductwork would be necessary. This distance and 

the arrangement of the emission points suggested this option was feasible.

To duct the oxidation reactor emissions to the existing wet scrubber, costs were estimated 

for ductwork, a blower, and electricity. Ductwork costs were estimated using algorithms from the 

EPA Air Pollution Control Cost Manual, see Attachment A for details.

6 The cost to move the gas 

exhaust using a blower was estimated from data available in Plant Design and Economics for 

Chemical Engineers. Using the maximum flow rate of 1,300 acfm, a purchased cost of $13,000 

(in $2002) was extrapolated for a turbo blower with 3 psi max discharge.7 Electricity costs were 

calculated using equation 2.10 in the EPA Air Pollution Control Cost Manual,

8 presented as

equation 1.

η

θ

6356 *

0.746 * * * * * pe Q P s ElectricityCost

∆ = (Eqn. 1)

Where:

Q = Gas flow rate (acfm)

ΔP = Pressure drop (inches of water)

s = Specific gravity of gas (1,000)

θ = Operating hours (8,760)

pe = electricity cost (0.0682 $/kW-hr)

η = Efficiency (0.6)

4
The pressure drop through the ductwork (ΔP) was estimated as part of the ductwork cost 

methodology, and equaled 0.36 pounds per square inch (psi). For purposes of estimating 

electricity cost, the pressure drop was multiplied by 2 to provide ample margin. The costs for 

ductwork, the blower, and electricity are summarized in Table 2.2.

Table 2.2. Oxidation reactor costs and emissions reduction for installing ductwork to an existing 

wet scrubber.

Item Total Capital 

Investment (TCI)

Total Annual Cost 

(TAC)

Ductwork $5,000 $470

Blower $18,600 $1,800

Electricity for Blower N/A $350

Total $23,600 $2,620

Emissions reductions for the Agrium Nu-West SPA process line were also determined. 

The emissions data for the SPA process line at Agrium Nu-West are presented in Table 2.3. In 

order to meet the proposed HF limit of 0.011 pounds of HF per ton of feed, expressed as 

phosphorus pentoxide (lb/ton P2O5 feed), HF emissions for EP-541 would need to be reduced by 

55 percent. Based on information provided by Agrium Nu-West, the existing wet scrubber for 

EP-522 achieves a fluoride removal efficiency greater than 90 percent, so reducing emissions by 

55 percent would be technically feasible.

Table 2.3. Agrium Nu-West SPA process line emissions data.

Facility EP

HF 

Emissions 

(lb/yr)

HF Emission 

Rate

(lb/ton P2O5

feed)

% Reduction 

to Meet HF 

Limit

HF 

Emissions 

Reduction 

(lb/yr)

Agrium Nu-West

SPA (EP-522) 1,093 0.0037 0% 0

SPA (EP-541) 4,826 0.0162 55% 2,660

Combined 5,919 0.0199 2,660

At least two facilities defluorinate phosphoric acid using diatomaceous earth. The 

inclusion of emissions from phosphoric acid defluorination processes were evaluated to 

determine if facilities currently using defluorination processes would meet the proposed HF limit 

for their process lines. Based on the HF data available, in each instance the facility’s process line 

emissions were below the HF limit when the emissions associated with defluorination processes 

5
were added to emissions of applicable equipment. Therefore, no additional control costs were 

estimated for defluorination processes. 

Several phosphoric acid manufacturing facilities employ clarifiers as an additional 

separation step. The clarifiers are typically intertwined with the flow of phosphoric acid as it is 

concentrated with evaporators. All facilities include emissions from clarifiers in the emission 

points they currently test for compliance, except for two facilities. Based on the HF data 

available, the two facilities would meet the proposed HF limit when emissions from clarifiers

were included in their process line emissions. Therefore, no additional control costs were 

estimated for inclusion of clarifier emissions.

3.0 TESTING AND MONITORING COSTS

The proposed subparts AA and BB require that facilities comply with an HF emission 

limit instead of a TF emission limit. As a result, the increase in testing costs for Method 320 

($15,000) versus Method 13B ($7,000) was calculated. Method 320 will cost facilities an 

additional $8,000 for each emission point tested. 

WPPA and SPA process line definitions were clarified to specify that emissions from 

oxidation reactors, defluorination processes, and clarifiers must be included when determining 

compliance. There are eight known emission points for oxidation reactors, defluorination 

processes, and clarifiers that would incur an additional cost. The full Method 320 cost of $15,000 

was included for these eight emission points.

A mercury limit was proposed in subpart AA for phosphate rock calciners. Costs were 

estimated to perform annual Hg testing for the six phosphate rock calciners in operation. It was 

also assumed that one of the phosphate rock calciners would perform semi-annual Hg tests to 

determine carbon bed life. The cost estimates reflect the cost to perform Method 30B ($6,400 per 

test) for Hg. The annual testing costs by emission source for HF and Hg are shown in Table 3.1. 

6
Table 3.1. Summary of testing costs to perform Methods 320 and 30B.

Emission Source

Total Annual 

Cost (TAC)

($/yr)

Phosphate Rock Calciners $44,800

Oxidation Reactors, Defluorination

Units, and Clarifiers

$120,000

Incremental Method 320 Cost $624,000

TOTAL $788,800

Control device monitoring costs were also evaluated. Costs were estimated for 

monitoring to comply with the proposed Hg limits for phosphate rock calciners in subpart AA; 

costs related to phosphate rock calciners were developed for the case where a FB carbon 

adsorption system was installed. The FB carbon adsorption beds do not require parametric 

monitoring; however the life of the bed must be established with semi-annual testing for three 

bed change-outs on one representative bed. Therefore, stack testing will be required on one of 

the calciners two times a year for at least the first three years. This cost is included in the 

summary costs in Table 3.1. No capital or annual costs for parametric monitoring of Hg control 

equipment were estimated. Additionally, no parametric monitoring costs were estimated due to 

inclusion of oxidation reactors, defluorination processes, and clarifiers when complying with HF

limits.

Performance evaluations of control device monitoring equipment are a proposed 

requirement for all facilities. An annual labor cost for completing the calibration requirements 

for scrubbers were estimated at seven hours per facility; this labor is included Table 3.2.

Recordkeeping and reporting costs were developed based on rule requirements. This includes 

report preparation and recordkeeping of monitoring and test data. Changes are proposed for the 

monitoring section of subparts AA and BB that require development of a monitoring plan.

Subpart AA also proposes the development of a gypsum dewatering stack and cooling pond 

management plan. Recordkeeping and reporting annual costs will be the highest in the first year

as initial costs will be incurred for reading the rule and developing the monitoring and 

management plans, and all subsequent years will have a lower annual cost. The annual costs for 

recordkeeping and reporting are presented in Table 3.2. See the Supporting Statement and 

burden tables for details on calculating testing, monitoring, recordkeeping, and reporting costs.5

7
Table 3.2. Summary of annual recordkeeping and reporting costs. Annual costs are presented for 

the first year of compliance and subsequent years.

Cost for First Year of 

Compliance

Annual Cost for 

Subsequent Years

($/yr)

$165,000 $66,200

8
4.0 REFERENCES

1. Eastern Research Group, Inc. “Beyond-the-Floor Analysis for Phosphate Rock Calciners 

at Phosphoric Acid Manufacturing Plants.” Docket ID: EPA-HQ-OAR-2012-0522. May 

2014.

2. EPA. “Mercury Study Report to Congress, Volume III: An Evaluation of Mercury 

Control Technologies and Costs (EPA-452/R-97-010).” December 1997.

3. Parsons Infrastructure and Technology Group Inc; prepared for U.S. DOE, National

Energy Technology Laboratory. “The Cost of Mercury Removal in an IGCC Plant.”

September 2002.

4. Jones, A., Hoffmann, J., Smith, D., Feeley III, T., Murphy, J.; prepared for U.S. DOE, 

Office of Fossil Energy, National Energy Technology Laboratory. “DOE/NETL’s Phase 

II Mercury Control Technology Field Testing Program, Updated Economic Analysis of 

Activated Carbon Injection.” May 2007. 

5. Eastern Research Group, Inc. “Supporting Statement for Phosphoric Acid and Phosphate 

Fertilizers NESHAPs.” Docket ID: EPA-HQ-OAR-2012-0522. September 2014.

6. U.S. Environmental Protection Agency. “EPA Control Cost Manual. Section 2: Generic 

Equipment and Devices, Chapter 1: Hoods, Ductwork, and Stacks,” December 1995. 

Publication Number EPA/452/B-02-001.

7. Peters, Timmerhaus, and West. Plant Design and Economics for Chemical Engineers. 

Fifth Edition. Figure 12-32, page 533. 2003. 

8. U.S. Environmental Protection Agency. “EPA Control Cost Manual. Section 1: 

Introduction, Chapter 2: Cost Estimation Concepts and Methodology”. January 2002. 

Publication Number EPA/452/B-02-001.

9
Attachment A
A-1: Ductwork Cost Algorithm

Parameter/Cost Variable Equation/Value1. Ductwork Inputs

a. Exhaust Flowrate (acfm) FL Value specific to facilityb. ut (ft/min) ut 3500c. Number of 90 Degree Elbows Elb90 5

d. k Value for 90 Degree Elbows k90 0.33e. Number of 45 Degree Elbows Elb45 5

f. k Value for 45 Degree Elbows k45 0.165

g. Material Factor, Galvanized Carbon Steel a1 0.322h. Material Factor, Galvanized Carbon Steel b1 1.22i. Material Factor, Galvanized Carbon Steel a2 30.4j. Material Factor, Galvanized Carbon Steel b2 0.0594k. Material Factor, Galvanized Carbon Steel a3 45.5l. Material Factor, Galvanized Carbon Steel b3 0.0597m. Number of Dampers Damp 4n. Length of Duct (ft) LDuct 400o. Exhaust Flowrate (acfm) FL Value specific to facilityp. Capital Recovery Factor (20 yrs, 7%) CRF = (0.07*(1+0.07)^20)/((1+0.07)^20-1) = 0.09439

2. Cost Index Values (CEPCI)

a. 1998 CEPCI 98CEPCI 389.5b. 2013 CEPCI 13CEPCI 567.3

3. Ductwork Capital Cost

a. Duct Diameter (ft) Diam_ft =1.128 * (FL / ut)^0.5

b. Duct Diamter (in) Diam_in = Diam_ft * 12c. Friction Losses (in H2O) Fd = 0.136 * (1 / Diam_ft)^1.18 * (ut / 1000)^1.8 * Lduct / 100

d. Velocity Pressure (in H2O) VP = (ut / 4016)^2e. Friction Loss from Elbows (in H2O) Fc = Elb90 * k90 * VP + Elb45 * k45 * VPf. Total Friction, Static Pressure Ft = Fd + Fcg. Straight Duct Cost, Galvanized CostStrDu = a1 * (Diam_in^b1) * LDucth. Elbow Cost CostElb = a2 * exp(b2 * Diam_in) * (Elb90 + Elb45)i. Damper Cost CostDamp = a3 * exp(b3 * Diam_in) * Dampj. Material Duct Cost CostMat = CostStrDu + CostElb + CostDampk. Total Material Duct Cost CostTotMat = CostMat * V#l. Duct Installation Cost CostInstDu = 0.375 * CostTotMatm. Total Material and Installation CostDuct = (CostTotMat + CostInstDu) * (13CEPCI / 98CEPCI)

4. Ductwork Annual Cost

a. Annual Cost CostDuctAn = CostDuct * CRF
A-2: Ductworks Costs for SPA Process Line Emissions

Facility Emission Point Flow Rate (ft3/min) Number of ducts Duct diam. (ft) Duct diam. (in) Length of Duct (ft) Friction losses, Fd (in H2O) velocity pressure, VP (in H2O) Fc, frict

loss fro

elbows 

H2O

Agrium Nu-West SPA, EP-541 1,300 1 0.69 8.25 400 8.07 0.76 1.88 

Facility Emission Point

Total 

Straight duct 

cost, 

galvanized

Total 

Elbow 

cost

Total 

Damper 

cost

Total 

Ductwork 

Material 

Cost

Duct 

Installatio

n Cost

Material + 

Installation 

cost 

(TOTAL)

2013 

Material + 

Installation 

cost 

(TOTAL)

2013 An

Cost

Agrium Nu-West SPA, EP-541 $1,690 $496 $298 $2,484 $932 $3,416 $4,975 $

DUCTWORK COSTS

DUCTWORK COSTS