A sustainability index for strategic mine planning: integrating closure and environmental costs into phase prioritization

This paper proposes a phase-based evaluation workflow for strategic mine planning in which environmental and closure costs associated with each project phase are quantified after a base-case block sequencing and then compared with the economic performance of the resulting pushbacks through an integrated indicator. The method is therefore applied ex post to a fixed mine schedule and is intended as a diagnostic and decision-support tool for identifying and comparing critical phases from an economic-environmental perspective. The method was applied to a hypothetical sedimentary uranium deposit, chosen as a first case study because it allows consistent phase-by-phase comparison of environmental disturbance, closure obligations, and economic value under an annual pushback framework. In a second stage, the same methodological structure was applied to a hypothetical porphyry copper–molybdenum deposit as a complementary case to test the transferability of the approach under different geometric and economic conditions. The entire process was structured in five main steps: construction of the block model and project database; block sequencing; estimation of environmental and closure costs per phase; discounting of these costs; and calculation and interpretation of the Sustainability Index.