This paper examines the retardation of breakage kinetics during the compressive loading of narrowly sized mineral feeds in confined particle beds. In particle-bed comminution, the granular composition of the particle-bed limits the maximum achievable degree of size reduction through a self-regulating mechanism. An analysis of the comminution of coarse-fine admixtures demonstrates that the mechanism of force-flux concentration/distribution accounts for the changing breakage rates. The evolution of the size spectra with energy expenditure is an asymptotic process in which size fractions reach their final state in a consecutive manner. An optimum energy or circuit factor exists for a given feed and cut size of a closed circuit. Addition of fines to a coarse feed can reduce the generation of fine particles resulting from stagewise size reduction of coarse particles,