Modern Mining July 2022

water can be procured from a municipal source, the mine could use this directly in the plant – and only treat water to potable standards that is used in bath rooms, kitchens and for drinking. Korb points out, however, that with more exten sive reuse of water, the water quality within the mine system can deteriorate to the point where regular intervention is required. This is a consequence that must be carefully managed. “Fortunately, most regions have seasonal rainfall which assists with keeping the water quality cleaner,” she says. “However, concentration of salts will occur over time regardless, and the reality is that mines may need to consider water treatment for recycled water in the later stages of the life of the mine”. Developing the cascade approach requires a good understanding of the water and salt balance within the broader system – including the mine work ings, the processing circuit, the tailings dam, the fresh water supply and the receiving water courses. “By identifying the major drivers of water use, a mine can better target its recycling efforts,” says Korb. “For instance, if the water being returned from the tailings dam is sediment-laden or there are other elements within the water that do not easily settle out, then it may not be usable in certain key plant processes.” Achieving the best results from a water quality cascade relies on good communication between the management of the mine’s process plant and its tailings facility. Plant managers, who know the water volumes and qualities required from day to day, are important players in determining whether the pro cess water demand can be fulfilled by return water from the tailings dam. The communication is vital as the tailings return water dams are often where most of the mine’s water is stored. “The process plant and tailings teams together can assist significantly in managing the mine’s water balance, and in helping to reduce the volumes of water being procured externally,” Korb says. Shepherd notes that leading mining compa nies have recently begun appointing dedicated experts to focus on water stewardship, to ensure

Mines can optimise the reuse and recycling of their water.

that strategies are implemented and coordinated mine-wide to conserve water use. This, he says, is a positive step towards balancing a mine’s need for optimal recoveries in the plant with the need to reduce water consumption from external sources. 

Mining companies have begun appointing dedicated experts to focus on water stewardship.

July 2022  MODERN MINING  37