A Peruvian case study: optimising mine planning through mine closure decision assessment

Abstract

Mine planning sets the goals and decisions required for the extraction of mined minerals at desired quality and quantities. Mine planning involves short-term and long-term decisions to facilitate implementation of strategic business objectives. However, mine planning business value drivers may not be aligned with closure strategies and obligations, which results in closure risks/opportunities not being managed. This makes it difficult to manage closure costs over time, particularly relating to potential long-term water quality impacts associated with mine rock and tailings management. Confirming that business value drivers align with closure objectives and the decision assessment process captures closure risks and opportunities is crucial to reduce potential for long-term liabilities and costs. Establishing a closure strategic plan supported by clear objectives and success criteria is important as it helps align mine planning stakeholders. While this is not a new concept, implementation of closure strategies into mine planning varies across the industry. This paper discusses a recent case study at a mine in Peru, in which a set of mine closure ‘strategic pillars’, decision-analysis tools, and a supporting integrated water quality model (WQM) were used to inform shortterm and long-term mine planning. The WQM allows for potential future water quality impacts of mine plan options to be quantified, ranked, and the associated long-term mitigation costs considered within life of asset costs. This paper details the innovative approach taken to integrate decision analysis, integrated WQM and closure costing tools to inform mine planning and life of asset costs. The motivation for developing this paper is due to an observed need to increase dialogue on this topic, with a broader vision to improve the mining industry’s reputation in closure outcomes and maintaining social trust.