Concentrate

Concentrate is ore that has been crushed and processed at a mine to raise the share of valuable metal before it is shipped to a smelter for further processing.

Mined ore contains only a small share of valuable metal mixed with a large amount of rock, so mines crush the ore and use processes like flotation to separate out and concentrate the metal-bearing particles before shipping anything. The result, concentrate, still needs a smelter to extract the metal itself, but it is far lighter and more valuable per tonne than the raw ore it came from.

Concentrate is bought and sold under contracts that pay for its metal content, assessed by assay, minus a treatment charge the smelter deducts for processing it. Weights in these contracts are usually stated in dry metric tonnes, since concentrate carries moisture that buyers do not want to pay for. Copper concentrate is the commodity most commonly traded this way, shipped from mines around the world to smelters concentrated in a much smaller number of countries.