Proposed amendments to air toxics standards for primary copper smelting

On July 13, 2023, the U.S. Environmental Protection Agency (EPA) proposed to update and expand the 2022 proposal of the National Emission Standards for Hazardous Air Pollutants (NESHAP) Risk and Technology Review (RTR) for Primary Copper Smelting major sources (subpart QQQ)

Primary copper smelting is the industry which refines copper sulfide ore concentrate from mined ore to produce anode grade copper, using pyrometallurgical processes. Smelting includes the handling and blending of ore concentrate; the drying of copper concentrate; the smelting of concentrate to matte grade copper; the conversion of matte grade copper to blister grade copper; the refining of blister grade copper to anode grade copper; and the pouring of copper anodes. 

The 2022 proposal of subpart QQQ proposed particulate matter emission limitations, as a surrogate for metal hazardous air pollutants (HAP), for anode refining point sources; roofline vents of smelting furnaces, converters and anode refining operations; new converters; and mercury limits for any combination of vents from copper concentrate dryers, converting department, the anode refining department, and the smelting vessels.

Since the issuance of the 2022 proposal, the EPA has obtained additional information that impacts the decisions made for certain amendments in the 2022 proposed RTR and that indicates there are additional unregulated HAP for the source category.

Based on the EPA’s review of additional information, EPA is now proposing amendments that would enhance the effectiveness of the major source standards by improving compliance and implementation. Specifically, EPA is proposing to:

• Revise the standards for particulate matter (PM) – as a surrogate for HAP metals – that would apply to anode refining furnace point source emissions and roofline emissions from anode furnaces, smelting furnaces, and converters by changing from individual roofline PM standards to a combined roofline PM standard.
• Revise the standards that apply to the secondary converter emissions and anode baghouse emissions. o Revise the mercury standards for a combination of point source emissions from the converters, smelting furnaces, and anode refining to account for new mercury test data.
• Add HAP standards for the following pollutants: benzene, toluene, hydrogen chloride (HCl), chlorine, polycyclic aromatic hydrocarbons (PAH), naphthalene and dioxin/furans (D/F).

This action also presents minor revisions to the residual risk assessment estimates in the 2022 proposal, but the risk review decisions have not changed. EPA will accept comment on the proposed amendments for 45 days after publication in the Federal Register.