Mining Magazine > Panorama > BBE designs underground cooling system for PMC

BBE Consulting has completed a US$447,000 EPCM contract to design an underground cooling circuit at Rio Tinto’s Palabora Mining Co (PMC) in Phalaborwa, Limpopo Province, South Africa. BBE’s design makes provision for two refrigeration machines to provide cooling to current workings and mine development.

The underground cooling circuit comprises two 1.5MW BACs, ± 3.0MW of cooling coils, chilled and warm water dams, two 3.5MW refrigeration machines and a 9MW condenser spray chamber. The refrigeration duty not used for the BACs will be used for cooling coils.

The cooling circuit will be located approximately 1,200m below the surface, on the production level. Refrigeration systems are not often located underground at this depth, which is quite shallow compared to other mines.

Marle Hoorman, BBE’s lead engineer on the project, said: “At PMC high ambient conditions are experienced throughout the year and the surface virgin rock temperature as well as the geothermal gradient of the rock is high. Trade-off comparisons were conducted prior to this work to arrive at the most favourable refrigeration system. We made our decision based on achieving the best efficiencies and lowest operating costs, as well as a variety of practical advantages.”

PMC is currently installing the first BAC underground, and delivery of the refrigeration equipment to the site is imminent. Construction of the second BAC, condenser spray chamber, dams and the first refrigeration machine is due to be completed by November 2011.