ABSTRACT
In the fragmentation of rocks with explosives at least eight breakage mechanisms are involved, with more or less responsability, but they all exert influence upon the results of the blastings. According to T. N. Hagan, the breakage mechanism consumes almost 30% of the energy transported by the strain wave, only contributing a very small volume to the actual rock fragmentation, around 0.1% of the total volume corresponding to the normal breakage per blasthole. The rock fragments created by the mechanisms and accelerated by the gases are projected towards the free face, colliding with each other and thereby producing additional fragmentation which has been demonstrated by ultra-speed photographs. The estimates carried out by Hagan have demonstrated that only a 15% of the total energy generated in the blasting is used as a working tool in the mechanisms of rock fragmentation and displacement.
