How does heavy-media separation separate dense mineral particles from gangue?

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mineral processing Schematic diagram of a flotation separation cell.

Heavy-media separation, also known as sink-and-float separation, utilizes the principle of density differences to isolate valuable minerals from gangue.

The process involves creating a suspension in water using finely ground heavy substances, such as magnetite or ferrosilicon. This suspension acts as a fluid with a density higher than that of water. When ground ore is introduced into this medium, the separation occurs based on the relative densities of the particles:

Gangue particles: Because they possess a lower density than the suspension, these particles float and are removed as tailings.
Valuable mineral particles: Because they possess a higher density than the suspension, these particles sink and are collected as a concentrate.

To maintain efficiency and sustainability, the heavy substances like magnetite or ferrosilicon can be recovered from the tailings through magnetic separation and subsequently recycled for further use.1