Mining and minerals project house TWP has successfully completed the fridge shaft portion of the No 17 shaft project at Impala Platinum’s (Implats’) Rustenburg operation.

The refrigeration shaft is one of three concrete-lined shafts being developed at the mine. The company was awarded the feasibility study for the No 17 shaft in 2006 and, upon completion, the engineering, procurement and construction management contract, which includes the management of the construction of the shaft’s cooling system in the form of a refrigeration plant on surface.

TWP senior project manager Don Munro says the refrigeration shaft is crucial to the success of the No 17 shaft, as underground temperatures reach levels that make mining a significant challenge. At the deepest level of the mine, the virgin rock temperature rises to 63 ºC.

“The refrigeration shaft, being 6 m in dia- meter, will downcast cooled air at 3 ºC from a refrigeration plant on the surface to the lowest working level, and the air will be disseminated through the stoping areas and finally upcasted through the ventilation shaft,” explains Munro.

The refrigeration shaft-sinking project reached a final depth of 1 437 m without a fatality, which TWP is proud of. Shaft Sinkers is the sinking contractor and, in addition to the metres sunk, has also developed 1 000 m of horizontal infrastructure through this shaft barrel on three levels.

TWP explains that the project team is diligent in terms of mitigating risk and cover drilling – for example, drilling out of the fridge shaft bottom ensured that no accumulation of water or gas was intersected by the sinking shaft, which amounted to 35 cover rounds and 15 km of drilling. Other statistics include 400 000 m3 of broken rock and 75 000 m3 of concrete lining poured.

The refrigeration shaft project’s concrete- lining and sinking operation took place concurrently. The project has clocked over ten-million work hours to date, amounting to 1.18-million fatality-free shifts to date, of which the refrigeration shaft has contributed over two-million work hours and 244 000 shifts, while the project was completed over two- million fatality-free shifts, with a lost-time- injury frequency rate of 6.88.

Munro notes that the No 17 shaft project is one of the most challenging projects TWP has worked on, with over 4 500 m sunk and 1 000 m of horizontal metres completed to date, since July 2007. “The project, which will on completion have cost R12-billion to construct, is arguably the biggest shaft- sinking project in the world,” he states.

Therefore, the No 17 shaft project required a significant work force. “The project included more than 50 contracting companies and presently has in the region of 1 150 persons work- ing daily on site,” explains Munro. He assures that the No 17 shaft project is on schedule and below budget, while still achieving a high- quality finish, and should be completed in 2016.

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