Analysis of grinding in a spiral jet mill. Part 1: Batch grinding

Abstract Jet milling is widely used in several industrial applications to produce fine particles with a narrow size distribution. We studied by means of experiments, the influence of grinding pressure, holdup and milling time on the performance of a spiral air jet-mill operating in a batch mode, with respect to the particles. The experimental results indicated that a uni-modal size distribution of feed particles yields trimodal particle size distributions. The data for variation of the mean particle size and specific surface area with energy supplied collapsed to a curve for all the cases studied, indicating that mean size is primarily dependent on the energy supplied. A population balance model for the dynamics of the batch milling process, based on empirical breakage functions is developed, which describes the experimental results quite well. The form of the breakage functions provides an insight into the mechanisms of breakage of particles.