Improved utilisation and energy performance of a mine cooling system through the control of auxiliary systems

Surface cooling and ventilation systems on deep level mines are energy intensive. The electricity price increase over the previous few years has been greater than the increase in the Rand price of gold. Mine cooling and ventilation systems are designed for a maximum thermal load. The maximum thermal load is encountered on the hottest and most humid days with the mine consuming as much water as possible. The refrigeration system is designed to maintain a temperature safety barrier when operating conditions are below the maximum thermal load. The temperature safety barrier is converted into energy saving through flow reduction. Worker safety and mine production may not be affected. Energy savings are achieved by implementing various strategies at constant boundary conditions. Implementation of these strategies results in improved utilisation and performance of the mine cooling system. A comparison was made between the performance of existing infrastructure with temperature safety barriers and the implementation of new equipment and instrumentation. An average demand saving of 1.8 MW was achieved with a case study.