Rock Fragmentation Control in Blasting

Abstract

Rock fragmentation, which is the fragment size distribution of blasted rock material, is used in the mining industry as an index to estimate the effect of bench blasting. It is well known that the rock fragmentation in bench blasting is affected by blast condition such as specific charge, spacing and burden, involving rock heterogeneity, dynamic fracture phenomena, etc. Rock fragmentation in bench blasting was examined using a numerical approach, based on dynamic fracture process analysis and image analysis. Five models were used to consider the effect of specific charge and geometry in bench blasting. To investigate the influence of blast condition on fragmentation in bench blast simulations, the fragmentation obtained using the numerical approach was compared and analyzed. To discuses controlled fragmentation related to the blast pattern, widely spaced blast patterns were simulated. The fracture process and fragmentation were compared with that in general bench blasting. Controlled fragmentation with respect to delay timing was also discussed. Ultimately it was discussed that the optimal fragmentation in the field with respect to delay time depends strongly on the gas flow through the fractures caused by the stress wave.