A zero-wastage approach to benchmark energy efficiency on platinum mines

Abstract

The South African mining sector encompasses some of the largest mines in the world. These mines make use of high energy-consuming systems such as compressed air, ventilation, and refrigeration to extract ore from underground. However, the profitability of these mines faces constant threat due to escalating electricity costs and growing pressure from stakeholders to comply with environmental, social, and governance (ESG). Energy efficiency is thus a critical component in reducing energy consumption and producing ‘cleaner’ products. Energy efficiency emerges as a pivotal element in curtailing energy consumption and generating environmentally friendly outputs. Effectively managing energy consumption not only benefits struggling entities like the South African electricity provider Eskom but also aligns with utility cost reduction initiatives and augments ESG scores through the process of decarbonisation. This underscores the imperative role of ongoing research, particularly within the mining industry, in implementing measures to enhance energy efficiency. Historically, benchmarking methods have been employed to compare analogous systems across different mines with the objective of identifying less efficient systems and components. However, a prominent drawback of this approach lies in its dependence on a multitude of variables inherent in each system. The complexity introduced by these variables, compounded by insufficient available data, can impede the normalisation of diverse systems, rendering the identification of inefficiencies an arduous undertaking. Another critical issue that arises is the dearth of standardised methods for benchmarking a system against itself to discern the wastage within the system. This study proposes a novel benchmarking method, comprising three novel contributions, for calculating a system’s zero-wastage baseload for optimal efficiency, guided by comprehensive and reliable data considerations. Sub-processes have been developed to calculate zero-wastage baseload either through simulation or a theoretical perspective, depending on the available data. This study’s innovative benchmarking method provides mines with a tangible II target, facilitating a gradual approach towards achieving zero-wastage baseload. Ultimately, this method has the potential to yield substantial cost savings in terms of electricity and resources, advertently also promoting ESG objectives. The zero-wastage benchmarking process was applied to three case studies involving two compressed air networks and a water reticulation system, respectively the zero-wastage benchmarking process revealed a substantial 49% reduction potential in Case Study A, translating to a noteworthy 72.7 MWh energy efficiency gain over a 24-hour profile. Case studies B and C demonstrated comparable outcomes, with possible reductions of 56% and 25.7%, respectively. The study's findings underscore the efficacy of the methodology in pinpointing areas with the potential for enhanced efficiency within each case study. Furthermore, the model adeptly identified the least efficient mining levels within a system so that they could be prioritised. This targeted approach provides a more focused approach to energy efficiency projects compared to other efficiency methods.