Abstract

Short-term open-pit mine production scheduling is a challenging task that must deal with several objectives, like maximization of the productivity of equipment (plant and mining), compliance of ore extraction, and others. Unfortunately, there are trade-offs between these objectives that make the problem of finding well-balanced short-term schedules complex to handle. To overcome this problem, we propose a methodology based on mathematical programming and a hierarchical method to generate short-term open-pit schedules considering multiple objectives. The mathematical program allocates shovels to different mining faces, including stockpiles. It considers plant capacity constraints, ore blending, precedences between mining faces, shovels throughput, and shovels' traveling time between mining faces. We also propose several compliance indicators, which we use to evaluate and compare different short-term schedules. We apply the proposed optimization model to a real iron open-pit mine to compare how the hierarchical method performs with regards to a single objective approach and show increases of waste extraction compliance up to 29% (when priority is production) and of 73% in production (when the priority is waste extraction). Moreover, in general, we observe that the hierarchical method produces more robust plans.