Open pit optimisation - modelling time and opportunity costs

Strategic mine planning is the process of determining the configuration that will optimise project objectives. Current methods for ensuring that objectives are optimised, for a given project configuration, contain a number of limitations. In particular, the strategic mine planning process for a given configuration is often completed by the sequential optimisation of key decisions. This approach does not allow for relationships between decisions to be measured accurately. As such, suboptimal mine plans are often produced. The ability to model and optimise key decisions simultaneously, so as to achieve greater value, is investigated in this paper. Some of the areas in which significant advances are made include time cost modelling, cutoff grade and stockpile optimisation for open pit operations. A case study was used to benchmark the proposed model against a marginal cutoff grade scheduling method, resulting in significant net present value increases.