Estimation of Operating Ranges of Jet Mills using Dynamic Modeling

ABSTRACT In today's process industry there is an increasing demand for fine polymer powders with a narrow, well defined particle size distribution. Several types of jet mills are used on a semi-large scale, though their energy efficiency is very poor. The research project aimed at a 50% energy reduction of the jet milling process by developing a control system and an improved design of the grinding plant. An important feature of the plant was the on-line particle size analysis. The topic of this paper will be the dynamic modeling of a fluid energy driven mill, in this case the opposed type. A population balance model was developed for a mechanistic description of the plant behaviour. The model contains terms for size reduction, particle transfer between zones, and internal classification. Experimental data was used to verify and optimize the model. The model served as a tool for plant control and scale-up.