Numerical studies on the inter-particle breakage of a confined particle assembly in rock crushing

Understanding rock crushing mechanisms may provide an efficient key to better fragmentation efficiency. In this paper, firstly the fracture processes of a rock specimen under uniaxial and triaxial compressions are simulated using the rock and tool interaction (R-T2D) code and compared with the results from experimental observations in literatures. It is found that, with increasing confinement, the fracture process is more progressive and the failure mechanism gradually changes from axial splitting to shear fracture. Then the inter-particle breakage process in a particle bed under confined conditions is numerically investigated from a mechanics point of view. The results show that when the particle breaks depends on the strength criterion, how it is broken depends on the stress distribution and redistribution, and where it is broken depends on the heterogeneous distribution in the particle. It is found that, irrespective of the particle shape or particle bed arrangement, the fragmentation starts from the particles which are loaded in quasi-uniaxial compression. The resulting fragmentation is usually axial splitting between the two highest stressed loading points. After that, the particles which are loaded at first in quasi-triaxial compression, because of the confinement from the neighbouring particles, the loading plate or the container wall, fail progressively. Depending on the location of the loading points, small fragments are torn off at the loading points with a large piece preserved. In the final stage, the local crushing at the highest stressed contact points becomes an important failure mechanism. Through this study, it is concluded that the R-T2D code can capture the features of the inter-particle breakage process, and a better qualitative understanding of the physics and mechanics of deformation and breakage is gained.