Reducing deep-level mine refuge bay compressed air consumption

Abstract

The South African mining industry has been experiencing a difficult time with most local mines operating in unprofitable or marginal conditions. The reason for the dire situations is mainly due to the high operating costs for the South African deep-level gold mines. It is necessary for mines to continuously reduce operating costs by implementing cost-saving initiatives by reducing waste or optimising processes. One of the most considerable costs for a deep-level gold mine is the electricity costs. Compressed air is supplied to the mines through large compressors which are the single largest consumer of electricity in the mine; second only to a combination of activities grouped into material handling and processing. One of the users of compressed air present in every deep-level gold mine is refuge bays. It was evident that a need existed to optimise the refuge bay compressed air use. "Rapid Re" business process re-engineering was applied to the South African deep-level mining environment in this dissertation. The methodology aimed at focusing the solution on the technical and the important social aspect of the process. The application of the adapted Rapid Re-engineering identified the value-adding activity as the valves controlling the flow to the refuge bays. The process was modelled and understood from a technical and social aspect. The inefficiencies of the current process were identified, and goals were set for the solution step. A theoretical benefit was calculated using simulation that resulted in a power reduction of 840 kW. A solution was generated along with a method of implementation based on the goals set out. The solution was implemented on the refuge bays in a deep-level gold mine. 42 refuge bay valves were replaced. The replacement of the valves led to a baseload reduction in power of 962 kW that was estimated to yield R 5.25 million in annual savings. An additional environmental benefit was calculated related to the energy savings achieved by the project. To ensure the year-to-year realisation of the benefit, sustainability methods for the project were put in place.