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How are retorts used in small-scale mercury extraction?

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Mercury thermometer — mercury processing Mercury in the bulb of a thermometer.

In small-scale mining operations, retorts are used as a cost-effective method for mercury extraction. Because they function as batch operations, they require manual charging and removal of material, which makes them more expensive to operate than large-scale furnaces.1

In the context of gold recovery, retorts are essential for processing amalgam—an alloy formed when gold or silver is dissolved in mercury. After the amalgam is filtered and washed, it is placed into a sealed retort and heated. This distillation process vaporizes the mercury, allowing it to be recovered for reuse while leaving the precious metal behind.23

Additionally, retorts are used to process soot collected from the condensing tubes of larger industrial furnaces. Given the significant health risks associated with mercury poisoning, it is ethically imperative that operators use properly sealed equipment to prevent the release of toxic vapors into the environment or the workplace.12