Improving demand-side pressure of compressed air distribution networks in mines

Abstract

The Platinum Group Mining industry is a large contributor to South Africa’s economy. Approximately 90% of the world’s remaining platinum group metals are in South Africa, with 54% of the global palladium & platinum mined in 2019 from South Africa. However, South Africa’s PGM industry has been facing challenges due to decreased demand and escalating costs due to mines becoming deeper and electricity tariffs increasing annually. This encourages platinum mines to implement cost-saving initiatives on existing infrastructure. From the literature, it was found that compressed air (CA) network inefficiencies offer enormous potential for optimisation. These studies showed that CA network inefficiencies result in low service delivery pressure being supplied to machinery, such as pneumatically operated drill rigs, pneumatic cylinders used to operate loading chutes, mechanical loaders, etc. These studies suggest that lowered demand-side pressure leads to longer drilling and loading times and higher consumption of compressed air, which contributes to higher operational costs, and affects the amount of ore hoisted. Research pertaining to demand-side pressure improvement initiatives on platinum mines is limited. Therefore, a need exists to optimise the compressed air network to improve the demand-side pressure by mitigating network inefficiencies on platinum mines. A methodology was developed to identify, evaluate, and address these network inefficiencies. With the use of this methodology, possible solutions were developed to increase demand-side pressure using an iterative process. These solutions were verified through simulation and

implemented on a case study mine, Mine A. The implemented solutions were then validated by comparing the simulation results with the actual results. After validation, the results were used to calculate and quantify the production increase. An investigation performed on Mine A indicated a pressure drop of approximately 135 kPa from the compressed air supply on the surface to the main production levels. Three initiatives to improve demand-side pressure were identified during the investigation. The first initiative focused on reconfiguring the main compressed air supply line, the second initiative focused on wastages and leaks found on the compressed air distribution network, and the third initiative focused on removing condensate from the compressed air. After implementation, the impact of the initiatives was validated, with results indicating an improvement in demand-side compressed air pressure. With the increased pressure, an increase in production is also expected.