Effect of pre-crushing with a vertical shaft im-pactor (VSI) crusher on the performance of an industrial cement ball mill classification circuit

Abstract

A vertical shaft impactor (VSI) type crusher can also be used as a pre-crushing unit in cement grinding circuits to carry out an efficient grinding process. This type of application will reduce the total grinding energy requirement by increasing the grinding capacity. The effect of operating a VSI crusher as a pre-crushing unit on grinding performance and capacity of an industrial scale two compartment ball mill classification circuit was investigated. Specific discharge and breakage rate of particles were calculated by using the perfect mixing modeling approach. It was shown that particles were discharged with a slightly higher rate in both grinding compartments when a VSI crusher was not applied in the circuit. Specific breakage rates of particles in the first compartment were found to be lower than that of second compartment in both grinding cases. Specific breakage rates were decreased in the first and second compartment when a VSI crusher was applied which could be attributed to the applied ball size distribution and mill feed grindability.