Multi-destination mine planning for poly-metallic mineral deposits
In conventional mine planning practices, using pre-defined productions rates and corresponding cost structure, ore-waste discrimination and block sequencing problems are solved subsequently. Given low grades and increasing risks, the exploitation of poly-metallic mineral deposits would be more popular in mineral industries. This trend requires more sophisticated mine planning practices. Given that conventional approach generates sub-optimal plans, mining industry needs totally new solution approaches incorporating new challenges. In this paper, a new two-stage mine planning approach is introduced. Using a marginal cut-off and conventional block sequencing approach such as pushback – nested pits based Lerchs-Grossmann algorithm, a plan is generated. This plan is used as an input in second stage, which is based on a metaheuristics. To improve the results obtained in the first stage, the blocks whose grade is around corresponding destination cut-off are listed. Likewise, the blocks which can be swapped from one period to the other without violating access constraint are determined. Until a pre-defined stopping criterion is satisfied, new period and block identification configurations are created. To test the performance of the approach proposed, a case study was carried out. The approached implemented on an Au-Ag mineral deposit with five destinations (waste, sub-grade, marginal, low grade process and high grade process) gave a rise to the project profitability.