Design of Refrigeration Plant at Impala Platinum's No.17 Shaft

CIM Montreal 2015
Andrew Branch (BBE Projects), Frank von Glehn (BBE Consulting), Rudolph Janse van Vuuren (BBE)
Impala Platinum’s’ No 17 Shaft is a new mine situated near Rustenburg in South Africa, and is designed to handle 255kton/month of reef and waste with primary ventilation ramping up to 1300kg/s. The bottom level is 28L at 1820m below collar; virgin rock temperature at that depth is around 63°C. The refrigeration plant is to be built in phases: In Phase 1 14MW of air cooling was installed, in Phase 2 this will be increased to 42MW together with the introduction of ice thermal storage and in Phase 3 the air cooling capacity will be finally increased to 56MW. Chilled air is produced in two adjoining bulk air coolers and directed underground in the main shaft and a dedicated fridge shaft. Some notable features of the plant include: dual-compressor R134a refrigeration machines; the plant building is constructed on top of the bulk air cooler to save space, necessitating a loading bay fully serviced by 30-ton overhead crane; the largest cooling tower cells on a mine in South Africa. Impala has adopted progressive cooling tactics: in Phase 2 the ice thermal storage system will allow electrical load smoothing and load management through the diurnal cycle; and the fridge shaft is a dedicated downcast shaft to convey ultra-cold air directly down to the mine’s deep levels. Detailed design of Phase 1 started in August 2010, construction started in January 2011 and the plant was commissioned in September 2012.
Keywords: Refrigeration, South African Platinum mine, Mine heat loads, Innovative mine cooling tactics, Air cooling
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