Mining the retreat zone between two converging pyramids at Noranda`s Bell-Allard mine

CIM Montreal 2003
Bradford S Simser, Denise Ouellet, Guy Gagnon,
Abstract Under current metal prices, Canadian hard rock mines are pressured to attain high mining rates and decrease costs to maintain profitability. Under moderate to high in-situ stress conditions, the problem is exacerbated by the need to restrain the size of openings, in order to mitigate geomechanical problems such as excessive dilution or rockbursting.

Optimum stope dimensions and rigorous mine sequencing are required to attain viability while maintaining control of the operation. In many mines, and particularly in single lens orebodies, multiple mining fronts are required to achieve economic production rates. These fronts eventually converge into sill or rib pillars. Recovery of these zones requires a different approach from the usual mining method.

This paper briefly briefly discusses the approach retained for two zones at Noranda`s Brunswick mine and details the recovery of the retreat zone between two converging pyramids at Noranda`s Bell-Allard mine in Northern Québec. Three mining options were evaluated for Bell-Allard and are presented in this paper along with the ground support and instrumentation that were required as the mine proceeds with the recovery of the retreat zone.
Keywords: Retreat zone, failed rock mass, Mine design, Seismicity, Risk assessment
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