Evaluating compressed air operational improvements on a deep-level mine through simulations

Deep-level mines make use of energy intensive compressed air systems to supply energy for underground mining equipment. These systems are complex due to large underground networks and the size and age of existing infrastructure. Typical deep-level mine compressed air systems consume approximately 20% of the mine's total electricity demand. An insufficient supply of compressed air can result in costly production losses. Mine compressed air systems are consequently often operated to oversupply pressurised air to working areas. Significant scope for operational and energy efficiency improvements therefore exist on compressed air systems in the South African mining sector. However, the dynamic nature and magnitude of these systems makes identifying and evaluating operational improvements difficult. In-depth studies are not presently economically viable due to time and logistic constraints associated with these studies. A new approach using simulations to investigate operational efficiency and service delivery solutions is presented in this paper. The method was tested on a compressed air system of a South African deep-level gold mine complex. Various evaluations were conducted by applying a new easy-to-use method, in conjunction with simulation, to determine feasible and credible operational improvements. Eight solutions were evaluated. Simulation results showed a 51 kPa potential improvement in compressed air pressure, on average during peak drilling shifts. The selected solutions result in annual electricity cost savings of up to R 1.5 million.