The separation principle of placer gold is to use gravity separation to recover the most of gold and its associated heavy minerals from the raw ore first, and then use gravity separation, flotation, amalgamation, magnetic separation, electric separation and other combined actions to separate gold and heavy minerals from each other to achieve the purpose of comprehensive recovery. The placer gold mining methods is usually divided into three operations:
(1) Washing operations
The cemented ore sand is separated by water immersion, washing and mechanical agitation, and the gravel, sand and clay are separated, and the clay and gold particles adhered on the gravel are cleaned. The ore washing operation includes three processes: crushing, screening and desliming.
(2) Rough separation
According to the characteristics of the mine can be divided into these modes: fixed sluice - shaking table process; fixed or vibrating sluice-jig machine-shaking table process; multi-stage jig machine-shaking table process; centrifugal concentrator – shaking table process.
(3) Cleaning separation
Heavy sand and mercury are mixed in a mercury mixing cylinder, heavy sand is not adsorbed by mercury and is removed, but the gold will be adsorbed into the mercury.