For reducing boulder yield in bench blasting of an open pit mine, rock breaking mechanism in rock blasting is applied, while engineering geological survey, numerical simulation analysis and on-site tests are utilized. Through alteration of charge structure, detonate direction and adjustment of blasting sequence, fragmentation is obviously improved and the cost for secondary blasting, shoveling and loading are all reduced.
It is an important topic to lower boulder yield in drilling and blasting in mine. Rock blastability comprehensively reflects its own physical-mechanical properties as well as explosive and blasting process; natural rock mass contains numerous faults, joints, fractures and other structural surfaces, thus its strengthen depends on rock strength and strength of structural surface and is mainly controlled by the latter in more conditions. Therefore, most of fracture planes of rock are generated along structural surface inside the rock mass.
Structural surface imposes stress concentration, reflection enhancement of stress wave, energy absorption, energy release, pitching-in, change of break line, etc. on blasting effect. It is commonly wished to search for the most proper explosive and blasting parameters under set ore rock properties in mine production, thus to reach the composition featuring the lowest total mining production cost. Therefore, the method for lowering boulder yield in blasting for fracture-developed mine is directly associated with economic and safety benefit of mine.