Grade Uncertainty in Stope Design

CIM Vancouver 2010
Allan Earl,
Abstract There have been recent advances in the automated detailed design of stopes. However, the validity of a single design is limited by the uncertainty of the grades. This paper explores the grade uncertainty inherent in a single stope design, by generating pseudo-stope designs, or mining outlines, for series of condition simulations of the same deposit. This was completed at a range of cut-off grades. It was found that the grade-tonnage relationship, both locally and globally, was similar for each of the mining outlines. However, when matching the other simulations to a particular mining outline, the average grade was greatly reduced. This reflects the sensitivity of stope design to the location of grade. The design will inevitably change as the mine advances, to reflect additional drilling information, and avoid excessive dilution. This study suggests that, at an early stage in project feasibility, it is more important to understand the uncertainty in the grade-tonnage relationship, incorporating mining recovery and dilution of the mining method, than it is to produce detailed mine designs.
Keywords: Stope design, Uncertainty
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