Application of Mass Blast for Stope Blasting in Deep Mines

CIM MEMO 2008
Abstract At deep and high stress mines such as LaRonde, stress levels are often high enough to cause holes to squeeze and/or back damage requiring rehabilitation following each blast. One of the most effective approaches to deal with high stresses for drilling and blasting is to minimize the number of blasts per stope by maximizing the use of available void for each blast. This mass blast principle has found success at several mining operations in Canada. Two key factors contributing to success are (a) the proper evaluation and use of existing voids and (b) the use of electronic detonators. While common practices demand about 30% void for regular blasts, tight blasts with less void have been proven possible by compacting the muck pile to a certain degree. The examples of “one shot” blasting per stope at LaRonde illustrate effective blast design and muck-handling procedures. Electronic detonators such as the i-konTM system offer a practical means of firing the detonators with long delay durations and high initiation accuracy. Significant production gains have been observed at mining operations with the use of the mass blast principle. It effectively reduces the blasting cycle time, the amount of re-drills and number of re-entries to blasted areas, therefore making it safer for employees who are involved in the re-drill and explosives charging processes.
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