Advances in Mine Tailings and Water Management in the Mining Industry for a Circular Economy

Abstract

The mining industry consumes vast quantities of water and energy to produce a metal or mineral product from mineral resources on the earth’s crust, leaving an enormous amount of mining waste. The linear thinking of the economy needs to be replaced with the circular economy to achieve sustainable development goals. In this context, the mining industry needs to improve in several aspects, such as reducing primary resource consumption and improve the efficiency of its processes. Strategies to reduce water and energy consumption, recycle water and wastes, and to recover energy are needed. The objective of this thesis is to develop methodologies to advance towards the circular economy in mining, with a focus on mine tailings and water management. The strategies and tools proposed are meant to be applied in mining processes to mitigate environmental impacts. The strategies proposed in water management include an integrated water distribution network to supply water to several mine plants while recovering energy using energy recovery devices. The method used is mathematical optimization to design the water distribution network. The methodology is validated with a case study that corresponds to an area of the Antofagasta Region. Results show that the optimal solution is an integrated system with energy recovery devices in areas with a complex topography where energy production is feasible. Reducing waste is a key component of the circular economy. Mine tailings are the main waste produced by the mining industries. Re-processing of mine tailings to obtain critical materials is proposed, the methodology is an economic assessment validated with a case study of tailing deposits of the Antofagasta Region. The economic evaluation considers the discounted cash flow method, sensitivity analysis, and real options analysis. Results show that an investment based on re-processing mine tailings to obtain critical materials is feasible in some cases. The contribution of this thesis is a collection of methodologies to improve mine tailings and water management to improve mining processes. About mine tailings management, the strategy proposed is re-processing mine tailings, which will reduce the amount of waste produced by mining plants and will reduce the need for mining primary ores. In the case of water management, the mining industry needs to reduce the demand for freshwater. To supply seawater is still an expensive option but having an integrated water distribution network with energy recovery devices will reduce the total cost of the network.