Smelt/Smelting

The process of melting ores or concentrates to separate out the gold, or other metal, from impurities. A flux or fluxes, such as silica, borax or soda ash, is used to dissolve out impurities which form into slag, leaving the gold free to be poured off.

Doré bullion cools at the smelter at
Zortman-Landusky mine (Credit:
Timothy Green)

On most gold mines, smelting is the final stage of recovering gold from an ore, thus obtaining a bar that is upwards of 850 fine, which can be sent to a refinery for purifying up to 995 or 999.9 fineness. Copper smelters also produce by-product gold, which then goes for refining. The terms smelting and refining sometimes overlap but whereas smelting is the separation of gold from non-metallic impurities, refining is the separating and purifying of gold from other metals.