How does gravity separation recover coarse particles of native gold?

Gravity separation recovers coarse particles of native gold by exploiting the significant difference in density between gold and the surrounding gangue minerals. In endogenetic deposits, where gold is disseminated within sulfide minerals, the ore is first crushed and ground to liberate the gold particles.12

For coarse particles, techniques such as jigging or tabling are commonly employed. In jigging, a water stream is pulsed upward and downward through a bed of material, causing the bed to stratify by density; the heavy gold particles settle into the lowest layer, while lighter materials are carried away. Alternatively, on shaking tables, the ore slurry flows down an inclined, grooved surface that is vibrated. The vibration and water flow work together to stratify the material, allowing the dense gold to be trapped by the grooves or ridges while the lighter sand and gravel are washed away. These gravity methods are highly effective for initial concentration before further processing, such as froth flotation, is used to recover finer gold associated with sulfides.21