Physical Origin of the Fine-Particle Problem in Blasting Fragmentation

Abstract

Blasting with explosives and crushing with mills are two major processes for extracting ore minerals. Longstanding problems with these processes are "fines" production in blasting and the related energy consumption of mills. Here, we demonstrate, using numerical simulations and comparison with experiments, that both problems emerge from two universal mechanisms: unstable tensile-crack propagation and compressive impact crushing. These lead to a universal mass-passing-fraction function in sieving. Crushing is limited to, and produces almost all the fines, and thereby inherently consumes a lot of fracture energy. Tensile cracks also produce fines, but the majority of the mass is confined in larger fragments. The key to resolving the fines and energy problem thus lies in minimizing crushing while inducing enough tensile load to reach the breakage threshold.