Gravity Separation is a mineral processing technique that exploits differences in the specific gravity (density) of minerals to separate valuable ore minerals from lighter gangue (waste) minerals using gravitational forces, sometimes enhanced by water flow or centrifugal acceleration. It is one of the oldest and most environmentally friendly beneficiation methods, requiring no chemical reagents and generating relatively simple waste streams.
In gold mining, gravity separation is widely used as a primary concentration step, particularly for coarse free gold, using equipment such as jigs, spirals, shaking tables, and centrifugal concentrators like the Knelson or Falcon concentrator. In iron ore processing, gravity separation through dense media separation (DMS) and spirals is used to upgrade lower-grade ores by removing lighter silicate gangue minerals.
In diamond mining, gravity separation is the cornerstone of the recovery circuit, as diamonds have a relatively high density compared to most host rock minerals and are effectively concentrated using DMS cyclones, jigging, and pan plants. In bauxite processing — specifically the Bayer process — gravity separation is used less frequently, though it may be applied to remove coarse silica or iron minerals in some operations.
The efficiency of gravity separation depends on the density contrast between minerals, particle size, and the viscosity of the separation medium. The technique is particularly effective for coarse particles and is often used ahead of flotation or leaching circuits to pre-concentrate ore.