Impact-Regulated Mixing and Segregation in Poured Granular Heaps

Abstract

A large body of work, for example [1–4] has concentrated on the observation that mixtures of granular material with dispersity in size and/or shape tend to separate in response to external perturbations, which are inevitable in almost all solids storage and handling operations. The focus of much of this work has been to determine the sensitivity of segregation phenomena to mixture properties. An underlying principle of much of this work seems to be that segregation is an innate property of granular mixtures; that it is in some sense unavoidable. This is certainly true if the mixture properties allow spontaneous percolation of fines through coarse; microstructural analyses [4] enable such mixtures to be identified. However, segregation problems in industry are often evident for mixtures where the dispersity in size or shape is sufficiently modest to preclude percolation. In such cases, we maintain that segregation is strongly influenced by process conditions as well as mixture properties, and so can (at least in principle) be controlled to some extent by careful manipulation of the process conditions.