Enhancing the performance of integer models for addressing the long-term production planning problem in open pit mines by decision variable fixation based on parametric analysis of the final pit limit

Abstract

The importance of strategic mine planning to ensure the long-term viability of mining projects has increased significantly because of the limited availability of high-grade ore deposits. Given its high-dimensional and combinatorial nature, developing a precise mathematical optimization technique to solve the entire problem remains challenging, particularly for real-size block models. The primary objective of this study was to propose a method that combines a nested pit strategy with integer programming (IP) models to overcome computational limitations by reducing the problem’s complexity, decreasing solution times, and providing insights into alternative production schedules for large-scale open-pit mines. The proposed algorithm strategically fixes the decision variables based on parametric analysis of the ultimate pit limit to simplify the IP model. The approach was applied to various block models from MineLib, and the results were compared with standard IP solutions and findings from related studies using alternative algorithms. Applying the proposed method demonstrated significant reductions in the solution time (up to 95%) and the ability to solve intractable models.