Numerical Modeling of Macroscale Brittle Rock Crushing during Impacts

Abstract

Abstract Several machines, such as crushers use the physical effect of compression to cause fragmentation “crushing” of brittle rocks. As a consequence of the complex fragmentation process, crushers are still sized by empirical approaches. This paper presents the results of a numerical study to understand some aspects of rock crushing phenomenon in terms of energy consumption. The study uses the discrete element approach of PFC2D code to simulate a stamp mill. The stamp mill has a simple crushing mechanism of a fixed kinetic energy delivered by a rigid ram impact. A single rock fragment crushing process dependent on the number of stamp mill ram blows is numerically examined. Both amount and type of energy generated by a ram blow are monitored besides the type of fractures generated. The model results indicate that the ram impact energy is mainly consumed in form of friction energy (up to 61 %) while strain energy stays at about 5 % of delivered energy. The energy consumed by crushing the rock represents only 32 % to 45 % of stamp mill energy and tends to decrease as the number of impacts increases. The rock fragmented matrix tends to convert into more friction energy with reduced number of new fractures as number of blows increase. The fragmentation caused by tensile is more often compared to those caused by shear, this behaviour increased with increasing number of ram blows.