Water management in mining and mineral processing
Water is essential to mineral processing. It is used in various steps in the process to recover valuable metals from ore. The water use is quite high – for example, around 1600 litres of water are used to obtain the 19 kilograms of copper found in a medium-sized family car.
Water is not always readily available for processing operations. In many locations where mining operations occur, such as in remote Australia, water is a scarce resource. Even in environments where water is readily accessible, making that water suitable for use in the ore refining process, such as through desalination, can add significant costs and increase energy use.
As ore grades decline the amount of water required increases because more intensive processing is required. The industry, particularly in Australia, is increasingly mining lower-grade ores and interest in reducing water use is high.
Estimating water footprints
We're developing a way to estimate water footprints for major mineral commodities, focusing on the mining and processing of nickel, copper and gold (because of their relatively high water intensity).
By investigating methods of valuing water in mining, mineral processing and metal production, and comparing these with other industrial processes and water users, we will be able to better manage water and reduce the risk of water scarcity.
Our method uses a technique called life cycle assessment. Using our method, industry can measure and analyse its water footprint from the point where ore is extracted through the production process, and on to its end use and disposal.
Working out water use
Using life cycle assessment, operators can identify and calculate the direct water use of various processes such as milling and flotation as well as indirect water use.
Water use 'hotspots' can be detected and opportunities for water savings – and the associated cost benefits – highlighted. It is leading to more sustainable minerals processing operations.