Understanding Powder Caking

By Tim Freeman, Director of Operations, Freeman Technology

Caking, or unwanted agglomeration, presents major problems in powder processing, capable of making even those powders that are normally free-flowing and easily processable, challenging. Its control depends on understanding the influence of, and closely managing, environmental conditions. Modern powder testers help make the link between different variables and the tendency towards caking, providing useful information for the determination of an optimal environment.

A significant number of materials in the food, chemical and pharmaceutical industries, from raw feeds, additives and intermediates through to manufactured products, are sold as free-flowing, easily processable powders, however caking can adversely affect their performance. Caking (agglomeration) occurs via a number of mechanisms, both mechanical and chemical, with the migration and absorption of water often the most influential. Control can be achieved by managing environmental conditions in a way that keeps feed or product in an optimal state. Powder rheometers can assist by measuring powder properties that indicate the progression of caking - as a function of humidity and consolidation for example enabling a greater understanding of which factors are most influential at different stages of processing.