comminution

Comminution is the reduction of solid materials from one size distribution to a finer size distribution. In mining and mineral processing, it refers to crushing and grinding operations that break ore into smaller particles to liberate valuable minerals and prepare material for separation and metallurgy. The process typically includes coarse crushing, intermediate crushing, and fine grinding, with the goal of achieving a product size suitable for downstream concentration processes such as flotation, magnetic separation, or leaching.

The main mechanisms are fracture by compression, impact, and shearing, and wear by abrasion and attrition. Equipment categories include crushers (jaw, gyratory, cone), grinders (ball mills, rod mills, autogenous and semiautogenous mills), vertical roller mills, high-pressure grinding rolls, and various types of ultrafine grinders and stirred mills. Energy consumption is a major consideration; comminution can account for a significant share of mine energy use. Throughput and product size are controlled by feed rate, mill speed, grinding media, liner design, and the presence of moisture.

Design and optimization rely on models and material properties. Bond's work index provides a proxy for grindability; selection functions estimate product size distributions; and population balance models simulate particle flows and grinding kinetics. Operators use metrics such as F80 and P80 to specify feed and product sizes and to monitor liberation and efficiency. In recent years, energy-efficient approaches and circuit innovations—such as high-pressure grinding rolls and stirred media mills—have improved performance for hard ores and fine grinding.

Comminution is foundational in mineral processing; its efficiency directly affects plant throughput, overall energy use, and cost. It also has applications beyond mining, including construction materials processing, recycling, and material science.