A mixed integer linear programming model for short-term open pit mine production scheduling

Short-term production scheduling in open pit mines usually generates a scheme to enable mining operations to deliver the budgeted tonnes and grades to the mill while following the long-term mine plan. The goal of this paper is to develop and test an optimisation model for short-term open pit mine production scheduling. A multidestination mixed integer linear programming (MILP) model is proposed, which minimises the overall cost of mining operations including mining, processing, haulage, rehandling and rehabilitation costs. The model is solved by branch-and-cut algorithm using TOMLAB/CPLEX optimiser. The model incorporates buffer and blending stockpiles, horizontal directional mining, and decisions on ramps while controlling technical constraints. A monthly production schedule in an iron ore mine is developed over 12 months to illustrate the practicality of the developed model. Three scenarios with different mining horizontal directions are considered. The scenario with minimum number of drop-cuts is selected as the best practical schedule.