Fracture kinetics of particle bed comminution - ramifications for fines production and mill optimization

This paper examines the retardation of breakage kinetics during the compres sive loading of narrowly sized mineral feeds in confined particle beds. In particle-bed comminution, the granular composition of the particle-bed limi ts the maximum achievable degree of size reduction through a self-regulatin g mechanism. An analysis of the comminution of coarse-fine admixtures demon strates that the mechanism of force-flux concentration/distribution account s for the changing breakage rates. The evolution of the size spectra with e nergy expenditure is an asymptotic process in which size fractions reach th eir final state in a consecutive manner. An optimum energy or circuit facto r exists for a given feed and cut size of a closed circuit. Addition of fin es to a coarse feed can reduce the generation of fine particles resulting f rom stagewise size reduction of coarse particles, (C) 1999 Elsevier Science S.A. All rights reserved.