Managing grade risk in stope design optimisation: probabilistic mathematical programming model and application in sublevel stoping

Abstract

Optimising stope design is an intricate element of underground mine planning where optimal designs are expected to integrate multiple technical aspects. Orebody uncertainty is a critical aspect affecting the forecasted performance of designs and is linked to the failing of meeting production targets and project financial expectations. Following recent conceptual developments in open pit mining, the present paper develops and explores a new probabilistic mixed integer programming model developed to optimise stope designs, including size, location and number of stopes under consideration of grade uncertainty and predefined levels of acceptable risk. An application of the method at Kidd Creek Mine, Ont., Canada, demonstrates its practical aspects including risk quantification for contained ore tonnes, grade and economic potential.