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How does amalgamation use mercury to recover fine gold particles?

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A worker in safety gear walks beside a conveyor belt carrying ore at the Tanami gold mine in the arid, expansive landscape of the Tanami Desert. — gold processing The Tanami gold mine, Northern Territory, Australia.

Amalgamation is a process that exploits the solubility of elemental gold in mercury. When fine gold particles come into contact with a fresh mercury surface, they are wetted and dissolved to form an amalgam, which is an alloy of mercury and another metal.12

This recovery is typically achieved through several methods:
* Passing a slurry of ore over mercury-coated copper plates.1
* Mixing the ore slurry and mercury in a vessel, such as an amalgam barrel.1
* Grinding the ore in a mill with mercury until the gold dissolves.1

Once the denser amalgam is separated from the barren ore, it is filtered and washed to remove impurities. The mixture is then heated in a sealed retort to distill off the mercury, which is recovered for reuse, leaving the gold behind.12

It is essential to recognize that while this process is effective for recovery, it poses severe ethical and safety risks. The use of mercury carries significant hazards of mercury poisoning for operators and can cause devastating environmental contamination, necessitating the use of strictly controlled equipment.1