Optimization, scale up and simulation of tumbling mills

Abstract: Grinding is a fundamental process in the mineral industries. Grinding mills are often very large machines. Their efficiency and energy consumption therefore are of major importance. Problems of large ball mills are discussed in this thesis. The employment of ball mills with a diameter over 5 meters in industry began only a decade ago. The abnormal behaviour of these big mills surely surprised many who had an optimistic view of them. However, the problems have to be overcome since the trend of increasing mill size is still prevailing. An optimization of the grinding process deals with a large number of co-operating parameters. Statistical approach provides a powerful tool for doing this. Its application on the simultaneous study of four important grinding parameters is described in this thesis. In the last part of the thesis a study on the population balance model is presented. Tremendous research has been carried out on this model. However, its application for designing grinding mills still requires more effort on the understanding of the selection and breakage functions. Heterogeneous materials were selected to be the experimental samples in this thesis. It is the author's opinion that the future of the population balance model depends on its ability to survive the applications on scaling-up fullscale mills for grinding those complex materials.: