Metal melting and holding furnaces as specified in this section are permitted by rule.(1) crucible furnaces, pot furnaces, or induction furnaces with a holding capacity of 1,000 pounds or less, with the following limitations:(A) no smelting, reduction, sweating, metal separation, or distilling is conducted;(B) in ferrous melting furnaces where gray iron or steel is melted:(i) ductile iron is produced only when emissions are captured by a vent hood and filtered or within a crucible with a lid which allows no visible emissions; and(ii) the furnace charge is free of oil, grease, and paint;(C) in nonferrous melting furnaces, only the following metals are melted, poured, or held in a molten state:(i) aluminum or any alloy containing over 50% aluminum;(ii) magnesium or any alloy containing over 50% magnesium;(iii) tin or any alloy containing over 50% tin;(iv) zinc or any alloy containing over 50% zinc;(v) copper, brass, or bronze; or(vi) precious metals;(D) no lead, leaded brass, leaded bronze, or manganese bronze is melted, poured, or held in a molten state;(2) aluminum melting or holding furnaces with a holding capacity of 2,000 pounds or less that melt only clean aluminum ingots or pigs and in which no refining, smelting, metal separation, sweating, distilling, or fluxing with chlorine bearing gases is performed.