Comparison of Different Approaches to Strategic Open-Pit Mine Planning Under Geological Uncertainty

Abstract

Uncertainty has been a main topic in mine planning research during the last decade. Several models have been proposed to address and incorporate the uncertainty in the strategic mine planning process, to generate a better, more profitable plan even in adverse conditions such as geological or metal price uncertainty. Among these models, in the general two-stage approach, the extraction is usually the first-stage decision while processing considers the uncertainty as a second-stage decision. Another option is to minimize deviations from production targets (ore, average grade, and contaminants) considering the uncertainty in the grade of the deposit, or the risk averse approaches where some risk measure is introduced to minimize the losses in unfavorable scenarios. However, it is not clear how these models perform comparatively since they often consider the uncertainty in a fundamentally different way, with different objectives functions, constraints and uncertainty modeling. Therefore, there are no general guidelines under which conditions some approach is better than other. For this reason, this works aims to compare two of these proposed models (two-stage and minimization of deviations) under the same conditions, to verify the advantages of each one of them and generate recommendations about the applicability of these approaches. This comparison is performed considering the production plan, the distribution of the net present value, the total deviations from the target, among other indicators.