Reducing energy consumption of a deep-level platinum mine dewatering system through infrastructure reconfiguration
Abstract
South Africa is the largest producer of platinum in the world, accounting for up to 80% of global production. The mining sector contributes significantly to the South African economy, but this contribution is hindered by rising operational costs. A large contributor to rising operational cost is electricity expenditure, with above-inflation annual electricity tariff increases being the norm since 2008. Electricity tariffs have increased far more than the average national inflation rate. These above-inflation electricity tariff increases pose a great threat to the profitability of South African mining companies if not mitigated properly.
South Africa’s mining sector is a large consumer of electricity, accounting for up to 14.3% of the national electricity consumption. Dewatering systems consume on average about 14% of a typical mineshaft’s total electricity demand. Previous studies have showed that cost savings can be achieved on dewatering systems through load management and supply optimisation. Unfortunately, mines often do not have the correct dewatering infrastructure in place to implement cost-saving measures. Furthermore, research on infrastructure modification to reduce electricity consumption on deep-level platinum mine dewatering systems is limited and focuses on individual sub-systems within the dewatering system.
Therefore, there is a requirement for infrastructure reconfiguration to combine individual sub-systems to reduce the electricity consumption of dewatering systems. Furthermore, there is a need for a methodology to achieve additional cost savings through load management and improvement of underground water recirculation. The main objective of this study was to reduce electricity consumption and costs on the dewatering system of a deep-level platinum mine.
To address the study objective, a five-step methodology was developed to modify the dewatering infrastructure of deep-level platinum mines to achieve electricity cost savings. By
using this methodology, possible solutions were formulated to reduce the electricity consumption of dewatering systems. The different solutions were verified using a simulation model. The solutions were implemented on the case study shaft and validated by comparing the simulation results with the actual results. The simulation results showed that by modifying the dewatering infrastructure, two potential solutions could be implemented, namely load shifting on the dewatering pumps and underground water recirculation.
Underground water recirculation reduced the annual electricity consumption by 1 033 MWh and yielded a cost saving of R1.23 million per annum. A further saving of R300 000 per annum could be achieved through load shifting, i.e., running the dewatering pumps outside the Eskom peak periods. The achieved electricity cost savings bear testimony to the effectiveness of the developed methodology.
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