pulverization

Pulverization is the process of reducing solid materials to small particles by mechanical means. Commonly applied to brittle materials, it is used to produce powders for further processing. Pulverization is often distinguished from crushing, which yields larger fragments, and from coarse grinding, though the terms are used variably. The result is a material with a particle size distribution that depends on the material properties and the equipment used.

The process relies on mechanical energy delivered through impact, compression, attrition, or abrasion. Equipment ranges from mills and pulverizers such as ball mills, roller mills, hammer mills, jet mills, and ring-and-roller mills, to more specialized devices like pin mills and planetary mills. Pulverization can be performed dry, or with a liquid medium (wet milling). Cryogenic milling uses very low temperatures to embrittle materials and prevent heat-related changes.

Material properties strongly influence pulverization. Hardness, brittleness, toughness, and moisture content affect energy requirements and product quality. Finer particles require higher energy, longer milling, or finer grinding media. Process variables include feeding rate, grinding speed, media size and material, milling time, and temperature. Particle size distributions are often controlled by classifiers or sieving after milling.

Applications span pharmaceuticals, chemicals, ceramics, metals, pigments, food ingredients, and energy production. In industry, pulverization enables uniform mixing, improved solubility, set and curing properties, or increased surface area. Pulverized coal is a notable example in power generation, while pharmaceutical powders are carefully processed to meet dosage and bioavailability standards.

Safety and environmental concerns include dust generation, inhalation hazards, and explosion risks with combustible powders. Proper containment, ventilation, dust control, and equipment maintenance are essential. Energy efficiency and wear of grinding media are important economic considerations in industrial use.