Energy efficiency via optimisation of water reticulation in deep mines

Investigations into water reticulation systems at different deep-level mines have shown that water usage varies between 1.25 kl and 4.15 kl per ton of rock mined. This large variation in the water consumed per ton of rock mined indicates that some mines may be using water inefficiently. Three techniques were identified which could reduce water wastage and consequently water consumption of deep-level mines. These techniques include leak management, stope isolation control and supply water pressure control. The outcome of the evaluation at Mine 1 led to the implementation of all three water reduction techniques. Leak management realised a total daily reduction of 7 Ml with an additional reduction of 1.6 Ml per day from stope isolation and pressure control. An average daily energy reduction of 92 MWh was achieved. This relates to an estimated cost saving of R5 617 000 per annum. Further investigations revealed that a combined daily energy reduction of 170 MWh can be achieved by implementing water reduction techniques on five other mines. This relates to an estimated financial saving of R13 120 000 per annum.