Circular 117—Batch grinding model

By R. J. Roman and G. W. Becker, 1971, 7 pp., 2 tables, 2 figs., 1 appendix.

A grinding model has been developed which can be used to predict the product size distribution at any retention time in a batch grinding mill, given the feed size distribution and product size distribution at any other retention time. This model differs from other models published in that (1) the breakage function is completely specified through the Schuhmann equation and a mass balance, and (2) the apparent selection function is assumed to be dependent on the size distribution of the material in the mill, as well as the particle size being considered. These two factors have been used to develop a model which can make use of data obtained from grinding a size distribution to predict the results of grinding over a 10-fold change in size modulus.

Beginning in the mid-1950s, grinding models have been developed from numerous investigations, the aim of which have been to help the engineer predict the performance of grinding circuits. Another goal has been to offer a model by which grinding circuits may be controlled through the use of an on-line computer. Models presented to date have not been entirely satisfactory as evidenced by the continued work in this area. The model to develop a realistic grinding model, the logical starting point of which is the development of a batch grinding model. From this point, the model can be made more sophisticated by incorporating factors for each of the variables deemed important. Finally, a model of a complete grinding circuit will be developed by combining a model of continuos grinding mill together with that of a classifier.