The dependence of specific discharge and breakage rate functions on feed size distributions, operational and design parameters of industrial scale multi-compartment cement ball mills

Calculating specific discharge and breakage rates is an essential part of developing a grinding model for dry ball milling. With this purpose, detailed sampling surveys were performed to collect size distribution data at the steady state conditions of the cement grinding circuits at different plants. Effects of operational and design parameters on specific discharge and breakage rate of particles in geometrically different multi-compartment ball mills were evaluated. Results indicated that, effects of mill throughput rate, compartment length and mill feed size distribution on discharge rate function and effects of mill diameter and ball size distribution parameters on breakage rate function could be reflected using the industrial scale data directly.

This model structure is proposed for multi-compartment ball mills for the calculation of breakage (r) and discharge rate (d) functions in different segments of the mill using the experimentally measured mill inside size distributions (p1 and p2) and calculated mill feed and discharge size distributions (p3), in addition to segment hold-up (s1, s2, s3 and s4).Figure optionsDownload as PowerPoint slideHighlights
► Discharge rate increases with the throughput rate increase and decreases with the mill length.
► Coarser feed size increases the discharge rates.
► Finer ball size increases the breakage rates.
► Bigger mill diameter increases the breakage rates.