Groupe d’études et de recherche en analyse des décisions

G-2017-91

Expanding simultaneous stochastic optimization of mining complexes to introduce geometallurgical constraints: Application at the Escondida mining complex, Chile

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A mining complex is a mineral value chain that consists of multiple activities, starting from material extraction to a set of sellable products delivered to various customers and/or spot markets. Simultaneous stochastic optimization of mining complexes aims to simultaneously optimize mining, destination, blending, stockpiling, processing, transportation and logistic decisions for multiple mines to maximize the value of integrated mining business and minimize deviations from production targets. This paper expands simultaneous stochastic optimization of mining complexes to include geometallurgical constraints and performs a simultaneous optimization of extraction sequence, destination policy, and processing stream utilization decisions. Geometallurgical properties, such as SAG power index (SPI) and bond work index (BWI) influence the throughput, recovery and energy consumption of comminution circuits. Integrating geometallurgical constraints in the simultaneous stochastic optimization model helps to achieve higher and more stable throughput of comminution circuits. A multiple neighborhood simulated annealing algorithm is used to solve the large combinatorial optimization model. The performance of the model is tested at a multiple pit copper-gold mining complex (Escondida) and is compared to the conventional mine plan. Results indicate capabilities of the model to generate risk-resilient mine designs with improved expected NPV (cumulative discounted cash flows) by 267% and reduced risk of deviation from production targets, as compared to the conventional plan, which highlights the importance of the simultaneous stochastic optimization model of mining complexes to generate higher value with less risk for the integrated mining business.

, 23 pages