40 C.F.R. § 60.121a
As used in this subpart, all terms not defined herein shall have the meaning given them in the Act and in subpart A of this part.
Blast furnace means any furnace used to recover metal from slag.
Lead means elemental lead or alloys in which the predominant component is lead.
Process fugitive emissions source means a source of particulate matter (PM) emissions at a secondary lead smelter that is associated with lead smelting or refining including, but not limited to, smelting furnace charging points; smelting furnace lead and slag taps; pot and refining furnaces; and casting kettles.
Reverberatory furnace includes the following types of reverberatory furnaces: stationary, rotating, rocking, and tilting.
Secondary lead smelter means any facility producing lead from a lead-bearing scrap material by smelting to the metallic form.
40 C.F.R. §60.121a