Gold extraction

Gold extraction is the recovery of gold from ores, concentrates, and recycled materials through physical separation or chemical processing.

Gravity separation: A mineral-processing method that separates particles by differences in density and motion through a fluid. Dense native gold can be concentrated from crushed ore without dissolving it.
Placer mining: The recovery of valuable minerals from loose sediments, commonly in riverbeds or ancient stream deposits. Placer operations recover liberated gold grains through washing and gravity concentration.
Mercury pollution: Environmental contamination caused by the release of mercury into air, water, or soil. Amalgamation-based gold recovery can release mercury during burning and tailings handling.
Amalgamation: A process in which mercury forms an amalgam with gold or another metal, enabling physical separation. It can recover gold from concentrates but introduces severe mercury hazards.
Gold cyanidation: A process that dissolves gold from ore using dilute cyanide solution, typically with oxygen present. It is the dominant chemical route for recovering gold from many low-grade ores.
Refractory gold ore: Gold-bearing ore in which minerals or chemical associations prevent efficient direct cyanide leaching. Its gold may require pretreatment before conventional leaching can recover it.
Cyanide poisoning: Illness caused by exposure to cyanide, which disrupts cellular use of oxygen. Cyanide used in gold leaching poses acute hazards if mishandled or released.
Thiosulfate leaching: A gold-leaching method that dissolves gold using thiosulfate-based solutions instead of cyanide. It is studied as an alternative where cyanide use is unsuitable.
Carbon-in-pulp process: A gold-recovery process in which activated carbon adsorbs dissolved gold directly from cyanide leach slurry. It captures gold from leach solution while ore solids remain in the tanks.
Gold recycling: The recovery of gold from discarded products, industrial residues, and other previously used materials. Recycled feed can supply gold without extracting it from newly mined ore.

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