Grinding mills generally process materials with small particle sizes, with products reaching 0.074mm or finer. They achieve pulverization by crushing mineral particles sandwiched between media (steel or non-metallic media) through impact and abrasion. Based on the fineness of the resulting product, they are classified as coarse grinding (1-0.3mm), fine grinding (0.1-0.074mm), and ultrafine (micro) grinding (usually referring to the production of powder materials with a particle size of 1.0-10.0μm or finer). Grinding mills are broadly classified according to their uses and characteristics as follows:

(1) Ball mill. The cylinder is cylindrical or conical, using metal balls as grinding media. Based on the discharge method, it is further divided into overflow type and grate type. Ball mills are widely used in mineral processing plants for grinding various ores.

(2) Rod mill. The cylinder is long and cylindrical, using metal rods as grinding media. Due to selective grinding, the product particle size is uniform, and it is mostly used in gravity separation plants. (3) A pebble mill is a steel-free grinding device that uses pebbles or hard rocks of various sizes to grind ore into fine particles.

(4) An autogenous mill. In this type of mill, the ore is crushed by its own impact and abrasion within a short cylinder. The ore serves as both the grinding medium and the material being ground. To improve the autogenous grinding effect, a small amount (2%–8%) of steel balls is sometimes added to the cylinder, resulting in a semi-autogenous mill. Autogenous mills have a large crushing ratio, which greatly simplifies the crushing process.

(5) Ultrafine grinding equipment. Currently, this type of equipment is mainly used for the deep processing of non-metallic minerals. It mainly falls into two categories: mechanical and pneumatic impact. Mechanical ultrafine grinding equipment relies on various high-speed rotating grinding media (hammers, blades, toothed columns, etc.) to collide with coarse ore particles dispersed on the inner wall of the grinding chamber due to centrifugal force, or to impart a certain linear velocity to these particles, causing them to impact and collide with each other. These types of equipment include vibratory mills, stirred mills, suspension roller mills (Raymond mills), tower mills, colloid mills, centrifugal mills, and high-pressure (extrusion) disc mills. Airflow ultrafine grinding equipment utilizes high-pressure airflow (compressed air or superheated steam) to pulverize materials through impact (collision), friction, and shearing. Product particle sizes can generally reach 1.0~5.0 μm or finer. Types of pulverizers include flat-type airflow mills, circulating tubular airflow mills, and jet mills. These grinding equipment are mainly used for ultrafine grinding of materials.