U.S. Environmental Protection Agency

Applicability Determination Index

Control Number: 9600081 

Category: NSPS 

EPA Office: METD 

Date: 11/30/1994 

Title: Various Subpart P Issues; Opacity 

Recipient: McKaughan, Colleen 

Author: Rasnic, John 

Subparts: Part 60, A, General Provisions 

Part 60, P, Primary Copper Smelters 

References: 60.11(e) 

60.11(g) 

60.161 

60.163 

60.164 

Abstract: 

Q: What is the scope of the term smelting furnace? 

A: "Smelting furnace" is defined in section 60.161(f) as "any vessel in which the smelting of 

copper sulfide ore concentrates or calcines is performed and in which the heat necessary 

for smelting is provided by an electric current . . ." The term smelting is defined as 

"processing techniques for the melting of a copper sulfide ore concentrate or calcine charge 

leading to the formation of separate layers of molten slag, molten copper, and/or copper 

matte." 

Q: What are the emissions points where the NSPS opacity standards in section 40.164 

apply? 

A: Any point where emissions are vented from the affected facility, which would include a 

vent fume stack that allows bypass of the acid plant. 

Q: What are the requirements when gas streams from NSPS and non-NSPS sources are 

comingled? 

A: It is policy that when gas streams are combined monitoring may be performed prior to 

when the gas streams are combined. If that is not feasible, the emissions can be measured 

at the stack. However, the stack must meet the lowest standard that applies to any affected 

facility that is routed to that stack. 

Q: What is the procedure for reviewing adjustments to the opacity standard? 

A: The Region reviews the request, but only headquarters has the authority to approve. 

Letter: 

MEMORANDUM

SUBJECT: Applicability Determination for a NSPS Subpart P Copper Smelter at Cyprus 

Miami Mining Corporation, Miami, Arizona 

FROM: John B. Rasnic, Director

Manufacturing, Energy, and Transportation Division

Office of Compliance

TO: Collen McKaughan, Chief

Air Compliance Branch

Region IX

This memorandum is in response to the questions regarding Cyprus Miami Mining 

Corporation's, Miami, Arizona copper smelters. The four questions were as follows: What is 

the scope of the term smelting furnace? What are the emissions points where the NSPS 

opacity standards applies? What are the requirements when gas streams from NSPS and 

non-NSPS sources are comingled; and what is the procedure for reviewing adjustments to 

the opacity standard? 

A "smelting furnace" is defined in section 60.161(f) as "any vessel in which the smelting of 

copper sulfide ore concentrates or calcines is performed and in which the heat necessary 

for smelting is provided by an electric current . . ." The term smelting is defined as 

"processing techniques for the melting of a copper sulfide ore concentrate or calcine charge 

leading to the formation of separate layers of molten slag, molten copper, and/or copper 

matte." The electric furnace that Cyprus Miami has labeled as "slag cleaning only" is 

separating slag and copper matte. This process is smelting as defined by NSPS subpart P: 

Primary Copper Smelters. The process is performed in an electric furnace which is included 

in the definition of smelting furnace. Therefore, if the electric furnace at Cyprus Miami was 

constructed, reconstructed, or modified after October 16, 1974 it is an affected facility. 

Cyprus Miami's other smelting furnace, the IsaSmelt, is a separate affected facility. 

In a telephone conversation with David Carlson, of your office, he indicated that the electric 

furnace was constructed prior to the applicability date. We cannot address the issue of 

whether the electric furnace is subject to NSPS subpart P under the reconstruction or 

modification provisions because information on this point was not available from the 

Region. 

The emissions from the electric furnace (if it is determined to be subject) and the IsaSmelt 

are subject to a sulfur dioxide standard of 0.065 percent by volume (60.163(a)) and a 20% 

opacity limit (60.164(b)). Section 60.164(b) states that "no owner or operator subject to the 

provisions of this subpart shall cause to be discharged into the atmosphere from any 

affected facility that uses a sulfuric acid plant to comply with the standard set forth in section 

60.163, any visible emissions which exhibit greater than 20 percent opacity." 

EPA document EPA 450/3-83-018a; Review of New Source Performance Standards for 

Primary Copper Smelters explains that the regulation was designed to control emissions to 

a level equivalent to using a double contact acid plant. Cyprus Miami uses an acid plant to 

control emissions and is subject to the opacity standard in section 60.164(b). The phrase 

"discharged into the atmosphere from any affected facility" includes any emission point, not 

just the emissions from the acid plant tail stack. Therefore, the emissions from the vent 

fume stack that bypass the acid plant are also subject to the 20 percent opacity standard. 

The monitoring of combined or divided gas streams is addressed in section 60.11(g) of the 

general provisions. This paragraph states that when different standards apply, each effluent 

must be monitored before they are co-mingled. If the emissions from the affected facility are 

vented to the atmosphere through more than one point, each emission point must be 

monitored. 

It has been our policy that when gas streams are combined monitoring may be performed 

prior to when the gas streams are combined. If that is not feasible, the emissions can be 

measured at the stack. However, the stack must meet the lowest standard that applies to 

any affected facility that is routed to that stack. Therefore, if the plant is designed such that 

measurements can not be obtained after the affected facility and before emissions are 

combined, the most restrictive standard applies at all points where emissions from the 

affected facility are vented to the atmosphere. 

If Cyprus Miami has combined emissions from NSPS and non-NSPS sources and can only 

measure emissions at the stack, the stack is subject to the 0.065% by volume standard for 

sulfur dioxide and a 20 percent opacity limit. 

In regards to an alternative opacity standard, under section 60.11(e)(6) a source may 

request an opacity standard specific to that plant. To make such a request the source must 

show compliance with all applicable standards, but fail to meet the opacity standard. The 

performance test and opacity readings must be taken at the same time, and the source 

must demonstrate that it has properly maintained and operated control equipment and has 

taken all practical means to reduce the opacity. 

In the second part of this question you refer to applying for a modification; I assume you 

mean applying for an alternative opacity standard. If the source wishes to apply for an 

alternative opacity standard, the request should be sent to the Region. The Region would 

provide a technical review, and if the source has provided adequate documentation that it 

has met the requirements set forth and the request is approvable, the Region drafts a 

Federal Register notice to approve the alternative limit. The draft approval package should 

be forwarded to the Manufacturing Branch of the Office of Compliance. The authority to 

approve alternative emissions standards is at the headquarters level; it has not been 

delegated to the Regional or state level. 

If you have any questions regarding this determination please contact Bob Fentress at 

(202)564-7023, Belinda Breidenbach at (202)564-7019, or in her absence, Sally Mitoff at 

(202)564-7012.