Abstract
SYNOPSIS Long-term production scheduling is a major step in open pit mine planning and design. It aims to maximize the net present value (NPV) of the cash flows from a mining project while satisfying all the operational constraints, such as grade blending, ore production, mining capacity, and pit slope during each scheduling period. Long-term plans not only determine the cash flow generated over the mine life, but are also the basis for medium- and short-term production scheduling. Mathematical programming methods, such as linear programming, mixed integer linear programming, dynamic programming, and graph theory, have shown to be well suited for optimization of mine production scheduling. However, the long-term plans generated by the mathematical formulations mostly create a scattered block extraction order on several benches that cannot be implemented in practice. The reason is the excessive movement of mining equipment between benches in a single scheduling period. In this paper, an alternative integer linear programming (ILP) formulation is presented for long-term production scheduling that reduced the number of active benches in any scheduling period. Numerical results of the proposed model on a small-scale open pit gold mine show a 34% reduction in the average number of working benches in a given scheduling period. Keywords: long-term production scheduling, mathematical programming, practical plans, equipment movements.
Highlights
One of the significant stages in open pit mine planning and designing is the optimization of long-term production scheduling
It can be seen that the new model (NM) scheduling pattern appears more practical and needs less equipment movement between benches within each scheduling period
The average number of active benches in the schedules was 7.6 for the traditional model (TM) and 5 for the NM, which represents a 34% reduction
Summary
One of the significant stages in open pit mine planning and designing is the optimization of long-term production scheduling. Mathematical programming has been effectively used by various researchers to tackle long-term open pit scheduling problems. Many researchers subsequently used mathematical programming models to solve the long-term production scheduling problems (Dagdelen and Johnson, 1986; Ramazan and Dimitrakopoulos, 2003; Dimitrakopoulos and Ramazan, 2009; Goodfellow and Dimitrakopoulos, 2015, 2017). A complete bibliography of the mathematical programming models that were used in mine production scheduling is provided by Osanloo, Gholamnejad, and Karimi (2008) for open pit optimization, and by Newman et al (2010) for optimization in underground mine planning
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