All mining and mineral processing operations require water and energy. Reducing water consumption and increasing energy efficiency are emerging as two key requirements to move towards a more sustainable mining industry. However, the two targets can be in conflict as water management initiatives often lead to an increase in energy consumption. On the other hand, some water initiatives may lead to reduction in energy consumption, leading to synergy between energy and water efficiency initiatives. To maximise energy and water sustainability in mine water management, it is essential that synergy and trade-off potentials between the water and energy targets related to water initiatives are recognised. In the last few years, considerable effort has been expended to improve our understanding of mine water systems and to report water use. However, limited research has been conducted to develop a tool or approach to consider water and energy impacts of water initiatives in a coupled manner.
The lack of a tool to analyse water and energy impacts in a coupled manner has been identified as a critical gap. Research is required to understand the impacts of mine water management on mine energy use. The aim of this research is to develop a comprehensive approach to evaluate the efficiency of water use in conjunction with energy use to assist in the selection of mine water management options at a mine system level. The research outcomes is that any progress in water efficiency does not lead to increased energy consumption, or at least leads to the minimal energy use option, and the synergies between the water and energy systems can be identified and maximised. The technique used to achieve these outcomes is exergy analysis as its field of application is large and it has proven successful to optimise the efficiency of other engineering systems, e.g. thermal, mechanical, and chemical processes optimisation, as well as ecological assessment and cost analysis.
This research involves the use of exergy analysis to show critical factors affecting energy demand of water management options. The analysis provides the focus points to reduce or avoid additional energy demand. At the same time, energy demand of different water options is quantified. The resultant energy demand and water volume availability analysis is examined to identify synergy and trade-off potentials between mine water and energy systems. The sustainable water use aspect is also taken into account by the estimation of water replacement energy demand. Finally, a multi-criteria selection approach is introduced to assist the selection of mine water management options. The approach introduced by this research has been demonstrated at three case study mine sites, a copper mine, a coal mine, and a gold mine. They were chosen based on the criteria of different commodities, climate, and geography.