Fragmentation Efficiency of Comminution under High Velocity Impact

For several decades, the mining and mineral processing industry has contended with high energy costs of which a large portion is due to mineral comminution operations. This is related to the low fragmentation efficiency of comminution which ranges from a value of only ~1 percent to a few percent and is typically accompanied by low impact velocities ranging from 1 to 10 m·s-1. In order to study comminution at higher strain rates than those of conventional equipment, a compressed-air gas gun apparatus has been developed to directly measure the quantitative parameters of impact velocity on aggregated rock samples. Experiments have been conducted on three materials at projectile velocities up to 450 m·s-1. The results suggest the energy efficiency of rock breakage can be improved by as much as 2 to 3 times under high velocity impact for the same energy input level. Data analysis and trends are influenced by the impact zone dimension, the hardness and porosity of the material, and the degree of constraint of the sample