Quantifying the effects of system constraint improvements on the electricity cost of dewatering pumps

The recent above-inflation increases in electricity tariffs have put large energy consumers such as gold mines under increasing pressure to implement and optimise Demand Side Management (DSM) initiatives to reduce electricity costs. With dewatering systems accounting for around 15% of gold mines' total electricity usage, it contributes significantly to mine operating costs. One of the most common types of DSM initiatives implemented on mine dewatering systems is load shifting. Load shifting projects in brief aim to reduce electricity costs by minimising electricity consumption during peak time-of-use (TOU) periods. Load shifting projects should be kept as efficient as possible in order to maximise electricity cost-savings performance. The performance of such load shifting projects are greatly dependent on system constraints. It is therefore important to determine and quantify the potential impact of certain constraints on dewatering systems. In this paper, the impact of some of the common constraints on mine dewatering systems are analysed. Improvement strategies to address the constraints are presented and simulated in order to quantify their cumulative impact on the electricity costs of a mine dewatering system. Results indicate that annual electricity cost savings of up to R21-million can be expected if dewatering system constraints are well-maintained and managed.