The coarse fraction refers to the portion of a crushed, screened, or classified mineral material that is retained on a specified screen size or above a defined particle size threshold during size separation processes. In mining operations — including bauxite, gold, iron ore, and diamond extraction — the characterisation of the coarse fraction is essential for designing and controlling comminution circuits, managing material handling systems, and optimising downstream processing. For example, in bauxite mining, the coarse fraction of a run-of-mine ore sample may indicate the degree of disaggregation achievable through scrubbing, which directly influences whether additional crushing is required. In gold processing, the coarse fraction of a milled ore sample is critical to identifying the presence of coarse gold particles that may require gravity concentration to avoid losses in cyanide leach circuits. In iron ore operations, the coarse fraction characteristics determine product lump-to-fine ratios, which have significant commercial implications. Particle size analysis of the coarse fraction is routinely performed using sieve analysis or laser diffraction techniques as part of metallurgical testwork programmes.
