Groupe d’études et de recherche en analyse des décisions

G-2013-56

An Extended Stochastic Optimization Method for Multi-Process Mining Complexes

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Traditionally, mining engineers plan an open pit mine considering pre-stablished conditions of operation of the plant(s) derived from a previous plant optimization. By contrast, mineral processing engineers optimize the processes of a plant through considering a regular feed from the mine, with respect to quantity and quality of the materials. The methods implemented to optimize mine and metallurgical plans simultaneously are known as global or simultaneous optimizers. The development of these methods has been of major concern for the mining industry in the last few years. Some algorithms are available in commercial mining software packages however, these algorithms ignore the inherent geological uncertainty associated with the deposit being considered, which leads to shortfalls in production, quality, and cashflow expectations.

This paper presents a heuristic method to generate life-of-mine production schedules that consider the whole single-pit mining complex and account for geological uncertainty, which allows for controlling the risk associated with not meeting production and blending requirements while maximizing the net present value expectations. The method uses iterative improvement by swapping periods and destinations of the mining blocks to generate the final solution. It considers multiple processes that may have several processing options with their corresponding costs, recoveries, additives and blending requirements associated. For meeting the blending requirements, multiple metallurgical ore types, attributes and properties related to each mining block can be considered. The stockpiling of the different metallurgical ore types is also incorporated in the method. Its implementation at a copper deposit shows its ability to control mine and processing capacities while increasing the expected net present value of an initial solution by 30%.

, 22 pages