Influence of rock blast advance direction on boulder generation : a case study.

Abstract

In quarries, rock blasting is important for mining and transportation, being the first step in the comminution. Discontinuities present in a rock mass can interrupt the propagation of the shock wave and evacuate gases, thereby reducing the efficiency of the explosives. Differences in the orientation of joint sets and the advancing direction of the mine produce different fragmentation results. In this study, the blastability of a rock mass was evaluated as a function of mining advance direction relative to the direction of the main joint set using particle size curves generated by photo-analysis. The data were analysed for each bench, and the optimal direction of advance was determined as the one to generate the smallest boulders. The particle size curves reveal optimal fragmentation when the mining direction is orthogonal to the main joint set, reducing the number of boulders by 64.40%.