Column Generation for Mining Cut Definition with Geometallurgical Interactions

Overview & Synopsis

In this work we propose a novel approach to solve the mining cut definition problem in open pit mines with geometallurgical interactions. Mining cut definition deals with the aggregation of blocks into clusters which are extracted and processed as a single unit. The aggregation must fulfill operational considerations given by the loading equipment selectivity and should maximize the objectives given by the mine operation. The proposed approach utilizes mixed integer programming and a model inspired by column generation that, contrarily to previous works, has its decision variables defined directly on the set of all feasible cuts. The advantage of this is that the model does not require linear approximations of the geometallurgical behavior of the cuts based on the blocks it contains, and therefore, can utilize any non-linear function. We apply our methodology to a real-size case study to show that the model can be solved in reasonable time, but also that non-linear recovery functions influence the destination policy and expected profit, i.e., that following the traditional free selection policy (based on cutoff grade) is not the best strategy when realistic geometallurgical interactions are considered.