Non-intrusive Flow Measurement of Compressed Air in a Deep-Level Underground Platinum Mine

Compressed air systems are one of the most significant energy users in underground mines, with a contribution of about 20% to the total electrical energy consumption. As a matter of fact, compressed air is considered to be a 4th utility in many industrial settings, in the same category as water, electricity and gas. In underground mine settings, compressed air is used to power pneumatic tools, mainly rock drills. Also, it is used to provide respirable air for underground workings ventilation systems. Surface compression facilities supply air to an underground network of pipes laid in vertical shafts and horizontal adits. The air is typically provided from a 24″ supply line to 12″ and 6″ feeder pipes at around 90 PSI. As various sections of the ore body are extracted, air supply is needed in different locations of the mine. The electricity costs associated with supplying compressed air are significant. In the case of a platinum mine in South Africa, it was approximately $25 K per day. Flow measurement is needed for the following objectives:

One may note that traditional leak detection technologies are more suitable for commercial building settings such as warehouses where compressed air piping is within line of sight. A mine being a complex web of shafts and adits, leak detection instruments need to be more innovative. Also, some compressed air audits and surveys include opening up of electrical panels, which may include disruption of production to conduct electrical energy isolation safety procedures lock out tag out try out (LOTOTO).