Discrete crack model for simulating rock comminution processes with the Discrete Element Method

Abstract

Comminution processes are not fully understood today and more research is necessary towards making improvements of existing comminution equipment. Presently, the best suited modeling technique is the Discrete Elements Method (DEM) but in its conventional form it is not suitable for industrial comminution processes where size reduction is an important, if not the main issue, as in crushers. Attempts for simulating such mining equipment with DEM have been carried out previously applying empirical models for rock rupture. The foundations of the Discrete Crack Model (DCM) are presented here as a new method for efficiently modelling rock fracture within a DEM work frame. In DCM, random cracks seeds are generated inside the rock specimens and the stress field in the vicinity of the cracks is calculated by the Convex Polygons Stress Approximation (CPSA), the basis of DCM. A rupture criterion is then applied to determine if or when the rock splits. CPSA stress fields are compared to those obtained by a more precise but much slower Finite Elements Method (FEM) solution. To validate DCM methodology, three illustrative loading cases are analyzed comparatively. It is shown that the failure mechanism predicted by the DCM methodology agrees to similar documented cases in the literature. The proposed approach is applicable both in 2D and 3D.