Improving the underground pump scheduling of a dewatering system for a hydropowered gold mine

Abstract

The objective of this study was to reduce underground water pumping costs at a marginal hydropower gold mine located close to the town of Orkney, in the North West Province of South Africa, which has in recent years decreased its production by 50% as well as stopping all new development. A marginal mine is a mine with high production costs and low grades of ore, where profit will only be viable if the commodity prices are high. A hydropower mine is a mine which uses high pressurised water for scraping, better known as cleaning, and drilling. The underground water reticulation system at the mine currently pumps water on demand to several underground levels and includes manually operated dewatering pumps. An opportunity existed in investigating their dewatering pumping schedule. The results obtained from this investigation showed that the mine was pumping during Standard Time of Eskom (the national energy utility), which is not necessary. A newly developed simulation model to improve the pumping schedule was implemented at this gold mine. An annual saving of approximately R935 000 was achieved by implementing the simulation model. The model contains the inflow from the settlers to the underground dams and the flow from the dewatering pumps to surface. This gives the underground dam levels which can then be used to create a new pumping schedule. With the increase in the price of gold since the end of 2015, the production of the mine has been steadily increasing. The simulation model can be adapted if there is any increase or decrease in the production rate.