Alteration of grindability of minerals due to applying different explosives in blasting operation

This study aims to characterize the alteration in mineral grindability due to applying different types of explosives in the blasting operation. For this purpose, several experimental blastings have been carried out on some granite blocks using three kinds of explosives; ANFO, Emulite and Pentolite. Then the mechanical strength of the resulting fragments has been measured by point load index and P-wave velocity tests. In the next step, the performance of rock fragments in comminution processes was examined by conducting some crushing and grinding experiments. Results showed that the blasting process can reduce the Bond work index of fragments as much as 18% and enhances their crushability by 9.5%. Moreover, using different explosives brought about sensible changes in results, so that substituting ANFO with pentolite or emulite decreased the Bond index by 9.2% and 6.7% respectively, and increased the crushability index by 6.3% and 4.9% respectively. Besides, all results indicated that any increase in velocity of detonation (VOD) is followed by reduction of Bond work index and increase of milling throughput.