Description of grinding in a ball mill using statistical moments

Abstract

Many researchers who investigate the process of grinding and try to describe its kinetics use the classical form of equations developed by Sedlatschek and Bass and their modified form presented by Austin. Some difficulty in applying the above mentioned models is caused by their complex form of notation, particularly when increasing the accuracy of analysis which induces a growing number of size grades into which the granular material is divided. At present, there are no models which would be characterized by a simple notation on the one hand, and would take into account the effect of numerous process parameters on grain size composition of a ground product on the other hand. This chapter presents results of investigations of grinding which covered the analysis of particle size distribution and statistical analysis using the theory of moments. The investigations are carried out in a laboratory mill 6 dm 3 in volume and 200 mm of inner diameter. Experiments are performed for four rock materials with significant differences in Mohs hardness numbers. During the experiments the mass and type of balls, the degree of mill filling with feed and rotations frequency of the mill are changed. Dependence of the concentration and asymmetry coefficients and mean grain size on different equipment and process parameters is presented in the form of mathematical relations.