Gangue

Gangue is the unwanted mineral material mixed with valuable minerals in an ore deposit. It is separated from ore minerals during mineral processing.

Ore: Rock or mineral material containing substances that can be extracted economically. Gangue is the nonvaluable material accompanying the minerals that make an ore economically useful.
Mineral processing: The treatment of mined material to separate valuable minerals from waste and prepare them for further processing. Gangue is removed during the stages that concentrate ore minerals.
Mineral liberation: The physical separation of individual mineral grains from one another in a ground ore. Gangue must be liberated from valuable grains for many separation methods to work.
Cutoff grade: The minimum concentration of a valuable substance that makes mined material worth processing under specified conditions. Gangue dilutes valuable minerals and can push material below the economic cutoff.
Ore mineral: A mineral containing a valuable element or compound that can be extracted from ore. Ore minerals are the valuable constituents separated from gangue.
Comminution: The crushing and grinding of mined material into smaller particles. Breaking ore exposes boundaries between valuable minerals and gangue.
Grain boundary: The interface where two mineral grains meet within a solid material. Gangue and ore-mineral grain boundaries affect how crushing releases separate particles.
Ore grade: The concentration of a valuable substance in ore. A high gangue proportion generally means a lower grade of valuable material.
Mineral: A naturally occurring inorganic solid with a characteristic chemical composition and crystal structure. Gangue consists of minerals, not simply any unwanted material in a deposit.
Froth flotation: A mineral-separation process that uses bubbles and surface chemistry to concentrate selected particles. Flotation can separate hydrophobic ore minerals from gangue particles in water.

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