Why must most ores be crushed and ground before concentration?

In the field of mineral processing, ores must be crushed and ground—a process known as comminution—primarily to liberate valuable minerals from their interlocked state within waste rock, or gangue.1

Because valuable minerals are often physically bound to waste material, they must be reduced to a specific particle size to allow for effective separation. This liberation is essential for subsequent concentration processes, such as flotation, magnetic separation, or gravity separation, which rely on the distinct physical properties of the minerals to isolate them from the gangue.123

The required degree of fineness depends on how the desired mineral is disseminated throughout the ore; in some cases, this requires grinding the material into a fine powder with diameters of less than 0.1 millimetre. By removing as much waste rock as possible before smelting, the process ensures that only the concentrated metallic constituents proceed to further refining stages.213