Assessing the blue-water footprint of an opencast platinum mine in South Africa

Abstract

South Africa’s extensive mineral resources have resulted in mining activities dispersed across the country, playing a critical role in its socio-economic development. In contrast to this abundance of mineral wealth, water resources are generally limited, and vulnerable to environmental impacts from the mining industry. These circumstances make tailored management of water resources in the mining sector essential. To achieve this, detailed information on water use throughout a mine operation as well as an accurate water balance account is required. Blue-water footprints have the potential to contribute to this task as they allow for quantification of direct and indirect water use across the supply chain of a process, while incorporating both spatial extension and temporal duration. As defined by the Water Footprint Network’s (WFN) globally acknowledged water footprint assessment methodology, a blue-water footprint is determined by calculating the net consumptive use of water by an operation. According to the WFN, this includes water which is evaporated, incorporated into a product, or lost to outflows which do not return to the same catchment area in the same period. The applicability of this tool in the mining sector has not been fully explored. Therefore, it was decided to investigate the bluewater footprint of a South African platinum mining operation. The results showed that the largest consumption of water in the production of platinum was due to evaporation from the mineral processing plants (36.8%) and the tailings storage facilities (19.4%). To improve its water-use efficiency, measures should be taken by the operation to mitigate evaporative losses. Floating covers can assist in this effort as they reflect a proportion of the incoming solar radiation and act as a physical barrier to the passage of water vapour, both vertically and horizontally.