Analysing electricity cost saving opportunities on South African gold processing plants

Costs saving measures are important for South African gold producers due to increasing energy costs and decreasing production volumes. Extensive research has been published on electricity cost saving methods for mining services. These primarily focus on water reticulation, refrigeration, compressed air and rock transportation systems. However, research has been limited on the energy savings potential of gold processing plants, despite the significant amounts of energy that this sector consumes.This paper reports on techniques that were developed to identity, analyse and implement relevant electricity cost saving opportunities on gold processing plants. Electrical load management was identified as an opportunity that can deliver substantial cost savings. However, due to the high value of revenue generated by gold plants it was imperative to ensure that overall production targets were maintained during implementation. The study methodology therefore focussed on production forecasting and the simulation of key process indicators, such as silo levels, material flow rates and densities. Load management case studies on comminution equipment at two gold processing plants showed peak load shifts of 3.6 MW and 0.6 MW respectively for a period of three months. This resulted in specific electricity cost reductions of 3% and 7% for the two respective case studies. These results show that downstream processing plants should not be overlooked when scoping for electricity cost saving opportunities in the mining sector.