Determining the depth and time of optimum transition from open-pit to underground mining in Songun copper mine

The most important issue, in the case of deposits with high axial expansion, is determining the "optimum transition depth from open-pit to underground mining (OTD)." The main objectives of the research are providing a framework-based method (mathematical model) to determine environmental costs and propose an optimization trick for combined mining options and transition planning (optimum transition depth), development, implementation and validation of the optimization framework based on the Mixed integer linear programming (MILP). The result of the MILP is to determine the most suitable mining option(s) for the mining of the ore and to schedule the extraction in such a way as to maximize the NPV. Python and MATLAB programming platforms were chosen to implement the MILP, and a large-scale meta-heuristic optimization solver was presented for this research. The MILP planned the Songun copper mine reserve with sequentially combined mining over a mine life of 13 years. The optimum transition depth from open-pit to underground mining was 950.