Comminution refers to size reduction by crushing and/or grinding, and is usually the first step in mineral processing operations.

The goal of comminution processes may be to

• simply achieve product specifications (i.e., various sizes of crushed stone from aggregate quarries)
• liberate valuable minerals from waste (i.e., metallic minerals or diamonds from gangue)
• expose more surface area for subsequent processing (i.e., for leaching operations)

Figure: Comminution is the first stage of processing and necessary to improve separation efficiency between valuable minerals and wastes (i.e., gangue or impurities).