Modern Mining September 2018

SHAFT SINKING AND RAISEBORING

represents a 26 % increase on where the Underground Mining platform was a year ago. What is also very encouraging is that much of this secured work has a long time horizon. For example, one of our most recent awards is for the contract mining at Kalagadi Manganese Mine in the Northern Cape, which has a five- year duration.” Turning specifically to shaft sinking (includ- ing decline shafts), Widlake says this represents a major area of activity for Murray & Roberts Cementation and its sister companies, with recently completed and current projects including the construction or rehabilitation of 20 vertical shafts and some 30 decline shafts in South Africa, Australia, Canada, Indonesia, Mongolia, the USA and Zambia. “Murray & Roberts Cementation’s current flagship contract is the Venetia Underground Project (VUP) of De Beers which includes two 7 m diameter vertical shafts which are being sunk to a depth of just over 1 km, as well as a 6 x 5 m decline system for trackless equipment with a total length of 7 km,” he states. “We’re also working on a 6,1 m diameter vertical shaft at Mopani’s Mufulira mine on the Zambian Copperbelt. What is unique about this shaft is that it is a triple raisebore – we have three raisebored sections of 500 m, one on top of the other, which have been joined to form a single shaft of 1 500 m. The raiseboring has now been completed and we’re now equipping the shaft. We also have a second contract at Mufulira for decline development.” Although it is still too early to give details, Widlake says Murray & Roberts Cementation is the preferred contractor on a new 8,5 m diame- ter, 1 200 m deep shaft at a South African mine, which will be a blind sink. Of course, the big upcoming project in the shaft-sinking space in South Africa is the No 2 shaft at Ivanhoe’s Platreef project near Mokopane, which will have an internal diam- eter of 10 m and be sunk to a depth of over 1 100 m below surface. In terms of hoisting capability (6 Mt/a), it will rank as the biggest shaft in Africa. All the big shaft-sinking companies will be hoping to win the contract for Shaft 2, includ- ing Murray & Roberts Cementation, which already has an involvement with the project. It has completed the design of the 103-metre- high concrete headframe that will house the shaft’s permanent hoisting facilities and is currently busy with the ‘early works’ contract for the shaft, which involves excavation of a surface boxcut to a depth of approximately 29 m below surface and the construction of the

concrete foundation for the headframe. Widlake makes the point that Murray & Roberts Cementation and its sister companies within the Underground Mining platform all work closely with each other, with the MDs of the individual companies reporting to the platform’s CEO, Mike da Costa. The synergies between the companies can often result in their collaborating on specific projects, as is the case currently with a contract to sink two 1 000 m deep shafts at Rio Tinto’s Oyu Tolgoi copper mine in Mongolia which has been awarded to RUC Cementation Mining in Australia. “To do the pre-sinks on the shafts, our Australian company is adopting the pre-sink technology that we pioneered very successfully at Venetia,” Widlake explains. “In essence, this comprises a rail-mounted gantry which com- bines the stage and kibble hoists as well as the blast barricade. Use of this technology is expected to cut the time for the pre-sink quite dramatically. We’ve been tasked with engineer- ing the entire pre-sink arrangement and the

The steel headgears of the two shafts of the Venetia Underground Project (VUP). The shafts are currently being sunk by Murray & Roberts Cementation.

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September 2018  MODERN MINING  37