STUDIES IN FLUID ENERGY GRINDING

The results of 239 experimental runs on grinding calcite of particle size range 0.15-1.70 mm in an experimental jet mill of 20 mm diameter, using feed rates of 5-150 g/min and air pressure of 3-6 kg/cm2 G are reported. The effects of (1) solids feed rate, feed size and grinding nozzle pressure on product size distribution, specific surface area produced, grinding ratio, holdup, residence time and grinding rate, (2) injector nozzle pressure on product size distribution and product specific surface area and (3) grinding nozzle diameter on product size distribution are indicated. Observations are made on the efficiency of grinding and choking conditions. Correlations for grinding ratio, specific surface area produced and optimum feed rate are presented. The present work seems to be the first attempt to bring together the variables involved in jet milling, to suggest conditions for optimum feed and choking and to develop quantitative relationships within the range of experimental work investigated. © 1969.