. H341001-0000-95-220-0007, Rev. 0 Page 1

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents. 

### Project Memo H341001 November 14, 2013
To: C. West From: J. Nikkari

cc: FCX

A. Binegar J. Spehar T. Weaver Hatch I. Carruthers R. Sullivan



## Freeport-McMoRan Copper & Gold Inc. (FCX) Miami Smelter Expansion Feasibility Study

SO2 Capture Efficiency - Current Operation
1. Introduction

Freeport-McMoRan Copper & Gold Inc. (FCX) retained Hatch to develop a Feasibility Study assessing expansion of the Miami Smelter throughput to a maximum permitted capacity of up to 1 million dry short tons per year of new metal b earing materials, while complying with the EPA’s revised National Ambient Air Quality Standard (NAAQS) for Sulfur Dioxide of 75 ppbv (1-h). The project is referred to as the Miami Smel ter Expansion Project. During the permitting process for the project the A DEQ and/or USEPA have requested further support for specific aspects of FCX Miami’s emissio n calculations. This response specifically addresses an EPA request for additional details supporting the current operation SO 2 capture efficiency to the primary and secondary sy stems, along with uncaptured smelter building (process) fu gitives. 

## 2. Design Basis 2.1 Emission Inventory - SO 2

Per current permit requirements, average hourly ope rating emissions have been used for the purpose of assessing compliance with the new ambien t SO 2 GLC standard of 75 ppbv (1-h). Average operating emissions are used to define the inputs for dispersion modeling, which ultimately determines the emission reduction requir ements and Miami Smelter Expansion Project compliance scope. The SO 2 emission inventory presented in this section was u sed as the basis for the sizing, selection and/or design of equipment to be installe d as part of the project to meet the ambient SO 2 objective.. H341001-0000-95-220-0007, Rev. 0 Page 2

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents. 

### 2.1.1 Annual SO 2 

### Emissions – Current Operation Annual emissions for “current” operation are summar ized in Table 2-1. Smelter building fugitive emissions are calculated based on roofline testing conducted over a 3-4 day period for each building in June 2012, in lieu of the prio r sulfur balance approach. Further details are available in the FS Environmental Design Criteria ( H341001-0000-07-122-0001).

Table 2-1: Annual SO 2 Emissions – Current Operation

Source Current Emissions (st/y) Basis

Vent Fume Scrubber Stack 331 2010 FCX Title V permit reporting
Acid Plant Tail Gas Scrubber Stack 1,415 2010 FCX Title V permit reporting Smelter Building Fugitives 1,031 June 2012 gas sampling x 120%
Acid Plant Bypass Stack Excluded from FS project scope 98 t in 2010. Excluded from

dispersion modeling at present. Miscellaneous/Other Fugitives N/A Assume negligible
It is noted that longer term roof line SO 2 measurements are currently being conducted to assess any potential project scope impacts ahead of the execution phase. 

### 2.1.2 Detailed SO 2 

### Inventory – Smelter Building Fugitives The annual SO 2 emissions in Table 2-1 do not provide sufficient d etail to establish the required SO 2 mitigation scope for smelter building fugitive SO 2 emissions. A more detailed inventory for the existing smelter, by activity and /or equipment (total of 35 identified), was developed and summarized in the FS Environmental De sign Criteria (H341001-0000-07-122- 0001). A high level summary by smelter building is provide d in Table 2-2.. H341001-0000-95-220-0007, Rev. 0 Page 3

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents.

Table 2-2: Smelter Building (Process) Fugitive SO 2 Emissions – Current Operation



### Emission Base Year: Sampling Campaign - Building Fugitives: 2012 Gas Sampling
, adjusted to 689k dstpy NMBM 

### Factor for Unmeasured Fugitive Emissions:

Stacks ANNUAL EMISSIONS OPERATING

HOURS EMISSIONS stpa hr g/s

1,415 7,610 46.9

331 8,157 10.2

Fugitive Sources Fugitive SO 2 Contribution ANNUAL

EMISSIONS OPERATING

HOURS EMISSIONS % stpa hr g/s

100% 1,031 7,610 34.1

0% 0 Per Above 0

28% 287 Per Above 9.5

4% 42 Per Above 1.4

68% 702 Per Above 23.2

0% 0 Per Above 0 Base (689k) 

### 1.2 2010 (689k dstpy NMBM)

Annual fugitive SO 2 tonnage scaled from test period SO 2 measured and corresponding throughput relative to annual throughput at 689k dstpy NMBM. Background / Unaccounted Sources*

IsasmeltTM Roof Vent

Electric Furnace Roof Vent

Converter and Anode Aisle Roof Vent

Other Non-Smelter Building Fugitive Sources*

*NOTE: Excellent operating/maintenance practices ar e required to minimize these to achieve 75 ppbv (le akage, etc.). Base (689k)

ITEM

- Total site-wide Fugitives (excluding bypass stack f or modeling) ITEM

-

Acid Plant Tail Gas

Vent Fume Scrubber. H341001-0000-95-220-0007, Rev. 0 Page 4

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents. 

## 3. Capture Efficiency Calculations – Existing Opera tion

The calculation approach used herein is consistent with the original EPA spreadsheet, updated to reflect the current measured emissions, as summarized in Section 2.1. 

### 3.1 Primary Capture 3.1.1 Isa (Smelting) Furnace

Almost all SO 2 generated from the Isa and electric furnaces comes from the Isa furnace. The electric furnace is included with the Isa furnace i n these calculations to ensure full accounting of SO 2 . Primary capture is to the acid plant. Uncaptured emissions are assumed to enter the vent fume scrubber, though in reality they enter ei ther the vent fume scrubber or are emitted from opening in the building, primarily at the roof line (see Section 4). Additional uncaptured fugitive emissions from either the acid plant or ve nt fume systems are accounted for separately in Section 3.2.2. Total vent fume scrubber emissions = 331 stpa (Table 2-1) Approximate vent fume scrubber efficiency (SO 2 ) ~ 80% based on reagent consumption data Uncaptured primary emissions from Isa and ELF to se condary (vent fume) system = Inlet SO 2 to vent fume scrubber from Isa and ELF = 331 stpa emissions / (1-80% capture) = 1655 stpa
Total SO 2 from Isa (and ELF) ~ 65% of total from feed = 65% x 689,438 stpa concentrate x 33.5% S x 64 lb SO 2 / 32 lb S = 300,048 stpa SO 2 Capture Efficiency = 1 – Uncaptured / Total SO 2 from Isa = 1 – 1655 / 300,048 = 99.45% Captured SO 2 = Total from Isa – Uncaptured = (300,048 – 1655) stpa = 298,393 stpa. H341001-0000-95-220-0007, Rev. 0 Page 5

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents. 

### 3.1.2 Hoboken Converters

Most SO 2 generated in the aisle comes from the converters a nd is captured in the acid plant. The entire aisle is included in these calculations, including the converters, anode furnaces, mold barrel, ladle transfer and crane activities, e tc. It is not practical to accurately separate the converter emissions from other aisle emissions. Primary capture is to the acid plant. Uncaptured emissions are emitted from the roofline building ventilation monitors in the combined aisle. Total roofline emissions (converter and anode aisle roof vents) = 702 stpa (Table 2-2)

Total SO 2 from converters (and anode furnaces) ~ 35% of total from feed = 35% x 689,438 stpa concentrate x 33.5% S x 64 lb SO 2 / 32 lb S = 161,564 stpa SO 2 Capture Efficiency = 1 – Uncaptured / Total SO 2 from converters = 1 – 702 / 161,564 = 99.57% Captured SO 2 = Total from converters – Uncaptured = (161,564 – 702) stpa = 160,862 stpa 

### 3.2 Secondary Capture 3.2.1 Electric Furnace

Total roofline emissions = 42 stpa (Table 2-2) Capture efficiency: Not applicable since this was grouped as a minor co ntributor with the Isa furnace (primary gas to acid plant, secondary gas to vent fume scrub ber) in Section 3.1.1.. H341001-0000-95-220-0007, Rev. 0 Page 6

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents. 

### 3.2.2 Isa (Smelting) Furnace

Total roofline emissions (Isa building only, ELF co vered in Section 3.2.1) = 287 stpa (Table 2-2)

Total SO 2 to vent fume scrubber = 331 stpa emissions / (1-80% capture) = 1655 stpa Capture Efficiency = 1 – Uncaptured / Total SO 2 to Vent Fume Scrubber
= 1 – 287 / 1655 = 82.66% 

### 3.3 Control Efficiency

Control efficiency for captured SO 2 is calculated individually for each of the three e mission routes, as follows: Acid Plant = 1 - Tail Stack Emissions / Inlet SO 2 = 1 - Tail Stack Emissions / (SO 2 from vessels – SO 2 missed by primary system) = 1 - 1425 stpa (Table 2-1) / [(300,048 + 161,564) stpa SO 2 from vessels – 1655 st/y SO 2 to vent fume scrubber - 287 stpa fugitives from Isa - 42 stpa fugitives from ELF]
= 99.69%
Vent Fume Scrubber ~ 80% based on reagent use

Roofline Emissions = 0% (no treatment at present) 

### 3.4 Overall SO 2 

### Removal Efficiency

Overall SO 2 removal efficiency (excluding minor bypass stack e missions) is calculated below: = 1 – Total SO 2 emissions (Table 2-1)/ Total SO 2 from vessels = 1 – (Stack Emissions + Fugitive Emissions) / Tota l SO 2 from vessels = 1 – (1415 stpa from tail stack + 331 stpa from ve nt fume stack + 1031 stpa total fugitives) / (300,048 stpa from Isa + 161,564 stpa from conver ters)
= 99.40%. H341001-0000-95-220-0007, Rev. 0 Page 7

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents.

At these high % removals for SO 2 from the smelter overall, estimation of residual e missions via mass (sulfur) balance is not inaccurate. 

## 4. Alternative Calculation Approach

All calculations have been updated above to better reflect the measured emissions, in lieu of the prior sulfur balance approach. However, the spr eadsheet provided presents a simplified sulfur balance for the Miami smelter. An alternate approach is presented below which would better reflect the capture efficiencies for the Isa (and ELF) buildings, where some gas is captured in the secondary system and a portion is e mitted untreated from the building. The same discrepancy does not exist in the aisle since any emissions missed by the primary system are emitted to atmosphere (no secondary capt ure). The calculations for the Hoboken converters (and other aisle emissions) would remain per Section 3.1.2 ( 99.57% ). The original calculations for the Isa (and ELF) bui lding are broken down for: 1) Primary capture to the acid plant vs. secondary capture to the vent fume system; and 2) Vent fume capture vs. smelter building fugitive emissions. In reality, Isa furnace emissions which are not cap tured in either the primary (acid plant) system or secondary (vent fume) system are emitted to atmosphere untreated from the building. The net impact is shown below: Overall Isa (and ELF) primary capture efficiency to acid plant = 1 – total SO 2 missed by primary system / total SO 2 from vessels = 1 – (Inlet SO 2 to vent fume scrubber + roofline fugitives) / tota l SO 2 from vessels = 1 – (1655 stpa + 287 stpa fugitives from Isa + 42 stpa fugitives from ELF) / 300,048 stpa = 99.34% (vs. 99.45% in Section 3.1.1) The Isa secondary capture efficiency reported in Se ction 3.2.2 would also be modified slightly. In particular, the roof vent emissions ar e not part of the 1655 stpa captured in the vent fume system; they should be in addition to it. If all roofline fugitives from these buildings are attributed to those missed by the secondary (ve nt fume) system the correct capture efficiency for Isa (and ELF) furnace gas to the ven t fume system is shown below: = 1 – roofline fugitives / total SO 2 missed by primary system = 1 – roofline fugitives / (total SO 2 to VFS + roofline fugitives) = 1 – (287 stpa fugitives from Isa + 42 stpa fugiti ves from ELF) / (1655 stpa + 287 stpa fugitives from Isa + 42 stpa fugitives from ELF)

= 83.4% (vs. 82.66% in Section 3.2.2) The end result is very similar efficiencies (and no change for the converter aisle) but what appears to be a more logical basis for reporting of primary and secondary capture efficiency.. H341001-0000-95-220-0007, Rev. 0 Page 8

© Hatch 2013 All rights reserved, including all rig hts relating to the use of this document or its con tents.

The overall capture efficiency for primary and seco ndary emissions from the Isa (and ELF) building is best reflected by the calculation below : = 1 – roofline fugitives / total SO 2 from vessels = 1 – (1415 stpa from tail stack + 331 stpa from ve nt fume stack + 287 stpa fugitives from Isa + 42 stpa fugitives from ELF + 702 stpa fugitives f rom aisle) / (300,048 stpa from Isa + 161,564 stpa from converters) = 99.89% 

## 5. Conclusions

An update of the FCX Miami annual emission spreadsh eet has been provided, with updated numbers reflecting current operation, notably fugit ive emissions based on a smelter building roofline sampling campaign conducted in June 2012. The resulting “capture” efficiency and overall SO 2 removal efficiency are significantly higher than t hose predicted using the prior sulfur balance approach. Similar results are also presented for an alternati ve calculation approach that should better reflect the capture efficiencies for vessels which have both primary and secondary capture in place (i.e., Isa and ELF).

J. Nikkari JJN:pp