Integrating haulage management with waste encapsulation and progressive reclamation in long-term production planning of mining complexes under uncertainty

Abstract

Abstract

Control over extraction and destination of waste can be just as important as it is for ore. Waste haulage is a major operating cost, especially as open-pit mines deepen and waste dumps expand, increasing strip ratios and haul distances. Moreover, potentially acid-generating (PAG) waste rock can lead to substantial rehabilitation liabilities through acid rock drainage (ARD). Progressive reclamation can be integrated into production scheduling optimisation to reduce PAG exposure during operations, thereby mitigating ARD and lowering environmental risk. Furthermore, traditional production planning approaches overlook geological uncertainty, limiting their ability to generate schedules robust to waste misclassification and metal grade variability. This study incorporates haulage management into a simultaneous stochastic optimisation framework for mining complexes to create a production schedule and waste placement plan that reduces haulage costs and mitigates ARD risk through progressive reclamation. A case study at a copper–gold mining complex compares performance when waste placement is optimised sequentially rather than simultaneously. The simultaneous case deferred waste haulage costs, reducing them by 38.7% in the first year, contributing to an 8.3% increase in net present value. At the end of operation, the sequential optimisation failed to encapsulate 16% of total PAG material extracted, compared with 22% in the simultaneous case.