Treatment charges are negotiated between miners and smelters and reflect the cost of processing concentrate into refined zinc metal. When mine supply is tight, TCs fall (favoring miners); when smelter capacity exceeds concentrate supply, TCs rise (favoring smelters). For importers acting as intermediaries or traders, TC levels directly affect the economics of concentrate arbitrage between origins and destinations, making benchmark TC negotiations — typically set at major industry conferences — a key market signal.

Cadmium is a naturally occurring impurity in zinc ores and is recovered as a byproduct during smelting. High cadmium concentrations can reduce concentrate value because of the additional processing and waste-management costs involved. In the US, cadmium is regulated as a hazardous substance, and smelters must manage cadmium-bearing residues under EPA hazardous waste rules. Importers should confirm that receiving facilities hold appropriate permits for cadmium-bearing materials.