Murray & Roberts Cementation Brings Its Raiseboring Experience to Selebi North Shaft

Murray & Roberts Cementation has secured two contracts at BCL Limited’s Selebi North Shaft in Botswana. Both contracts are related to the deepening of the existing shaft to access the ore body at a deeper elevation. Murray & Roberts Cementation is responsible for the planning, logistics, construction and quality assurance of these 14 month contracts.

Piet Esterhuizen, senior projects engineer at Murray & Roberts Cementation, said: “Currently, access to the ore body is via a vertical shaft and vehicle ramp system. Over the next two years the vehicle ramp system will reach a depth below the current ore handling system where the current mining methods will become uneconomical. For BCL to sustain its current ore production profile it has become necessary to deepen the existing vertical shaft.”

The first contract, which commenced in May 2009, is for the raiseboring of the 4.1m diameter shaft from 433m to 758m over a vertical distance of 325m to deepen the shaft. Pat Muller, senior projects manager responsible for this raiseboring contract at Murray & Roberts Cementation, said: “Raiseboring was considered a more cost effective and safer option as opposed to traditional shaft sinking methods. It also allows for far greater accuracy especially with our Rotary Vertical Drilling System (RVDS).”

The RVDS steering device will be used on the raiseboring project to ensure optimum accuracy. Pioneered by the company, the RVDS has been used on numerous contracts and the company has a comprehensive reference base.

Muller said: “Essentially, this system is used to ensure accuracy on the drilling of the pilot hole and accuracies of between 0.005% and 0.15% have been achieved on contracts both in South Africa and internationally.”

The second contract entails equipping the raisebored shaft and constructing the balance of the infrastructure, including all associated underground infrastructure such as the crushing plant, conveyors and loading facilities and loading bins as well as station equipping.

Esterhuizen said: “Both projects will support the local industry and in particular the Selebi Pikwe industry as far as civil construction, steelwork fabrication and structural assembly and electrical installation is concerned.”

Esterhuizen concluded: “Skills transfer will take place within the local community and we will be instilling our safety awareness credo in all the people we train.”

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