Blasting in Mines – New Trends.

Abstract

Modern mine productivity places a very strong focus on achieving high levels of control over fragmentation, wall control (damage to excavation limits) and environmental impact. The introduction and extensive use of electronic initiation heightens the focus of each one of these blasting outcomes, though systems to permit optimisation are not readily or widely available, and are seldom used in any routine manner in the mining industry. Seed wave modelling, in conjunction with electronic initiation, enables blasting engineers to identify optimum timing configurations for any type of blast, with respect to each of the three mentioned blasting outcomes. Fragmentation, either in the body of the blast or in the stemming zone of blasts, can be increased substantially by optimising timing from the point of view of maximising induced stresses within the rock mass, enabling quantification of a fragmentation index for specific vertical bench sections. Damage, either in the bench batter behind a limits blast, or in the underlying berm, can similarly be minimised by careful delay timing, often more effectively than by costly reduction of blasthole diameter, enabling definition of a Probability of Damage curve. Environmental vibration impacts, either in the medium-field as an impact on vibration-sensitive slopes or mine sectors, or in the far-field as an impact on nearby occupied structures, can also be minimised by careful selection of delay timing. This paper presents the use of seed wave modelling as an everyday tool to enable blasting engineers to make engineering-based decisions regarding the delay timing which will bring maximum control over these blasting impacts.