The connection between production schedule and cut-off optimization in underground mines

Abstract

While commercial systems are available for optimizing open cut design and production schedules, no similar system is available for underground mining. The opportunity for improving the economics of selective operations is especially attractive due to the complex interaction between the cut-off grade, mine plan and production schedule. No system is available that is capable of integrating all three strategic planning decisions within the context of life-of-mine optimization. The following discussion presents the history and state-of-the-art in cut-off grade theory and optimization with the conclusion that the accepted methods are inadequate when applied to selective underground mining. An alternative approach is presented, by way of an example, of scheduling copper production for a large sublevel stoping operation. The case study demonstrates that optimal cut-off policy is a consequence of production schedule optimization and that direct methods that treat cut-off as a decision variable may not be necessary or even desirable.