Effect of delay time and firing patterns on the size of fragmented rocks by bench blasting

Abstract

This paper discusses the size control method of fragmented rocks induced by bench blasting in an open pit mine, especially the effect of delay time and firing pattern. Based on the results of a series of field tests, it can be said that the delay time and firing pattern have an impact on the size of fragmented rocks. The application of two directions of firing pattern that the order of ignition of blast holes is from the center to both ends of the row of blast holes can produce a more uniform size of fragmented rocks compared with that of a one-directional firing pattern which is the order of the ignition of blast holes from one side to the other. Due to the rock mass conditions and products specification, the size of fragmented rocks and its distribution can be controlled by applying an appropriate delay time and firing pattern.