Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
SELLERS, E.; FURTNEY, J.; ONEDERRA, I. and CHITOMBO, G.. Improved understanding of explosive-rock interactions using the hybrid stress blasting model. J. S. Afr. Inst. Min. Metall. [online]. 2012, vol.112, n.8, pp. 721-728. ISSN 2411-9717.
Since 2001, the Hybrid Stress Blast Model (HSBM) project members have developed a software suite to model the complete blasting process from non-ideal detonation to muck pile formation. To preserve the physics and improve solution time, the breakage engine uses a combination of analytical models and 2D axisymmetric finite differences to model near-field crushing, coupled to 3D discrete lattice fracturing and distinct element numerical methods to model throw and muck pile development. The model has been validated by comparison with laboratory and field tests in kimberlite. Multiple blasthole simulations are used to demonstrate how changes to blasting parameters can influence downstream efficiencies. Case studies of wall control blasting show that the presplit design must balance the two opposing effects of increased damage with increased charge and decreasing attenuation of the seismic waves with decreasing charge. Modelling of decoupled explosives needs further development. Reducing the charge towards the back of the trim blast results in a much more significant decrease in back damage than altering the timing. The model demonstrates how separation along the weaker planes in a jointed rock can coarsen the fragmentation, leading to inefficient beneficiation, and extends the damage to a distance of at least twice the burden behind from the blasthole, severely compromising the wall stability.
Keywords : blasting; modelling; discrete element method..