An overview of energy efficiency in South African hard rock mining

This paper is an overview of energy efficiency possibilities in South African hard rock mining. Most of the hard rock mining operations are energy intensive. Elements discussed are compressed air, pumping, ventilation and refrigeration in existing mines. Case studies are presented and their respective influence on energy efficiency is discussed. Amongst others, the energy efficiency improvement by changing to high efficiency fan impellers, ventilation flow control equipment, and conversion from pneumatic- to hydro power and the detection of worn pump impellers are investigated. Trends in the design of new mines, with the view on energy efficiency, are presented. The themes investigated include the use of modern equipment and designs with improved efficiencies. The discussion touches on items such as compressors with built-in variable speed drives (VSD's), the use of higher voltages in reticulation, the use of over sized conductors to reduce electrical losses and CFD modelling to determine the optimum, yet safe, ventilation fan flow rates.