Secondary smelting uses scrap, dross, or other recycled feedstocks rather than mined ore concentrates. For trade professionals, this distinction matters because imported secondary feedstocks (scrap and residues) are classified under different HTS chapters than primary ores or refined metal, and may be subject to different duty rates, export licensing requirements in the country of origin, or Basel Convention controls on hazardous waste shipments.

Importers of nonferrous scrap and secondary materials must verify EPA and CBP requirements for hazardous waste exclusions, confirm that the material meets the definition of a commodity rather than a regulated waste under RCRA, and check whether the exporting country imposes export restrictions or licensing on scrap. Certain lead- and cadmium-bearing secondary materials may also trigger EPA import notification requirements.