Modern Mining March 2018

DIAMOND MINING

production drilling in the pit, while there are seven smaller drills operated by a contractor to conduct the trim and pre-splitting drilling. “By reducing the equipment fleet we are also achieving better efficiencies, with some machines being put on care and maintenance while others take on more hours,” says Horak. “Careful analysis of the benches to be mined, the dump deposition strategy, the cycle times and all relevant data allows us to forecast our primary equipment requirements year on year; we then align our ancillary equipment to these plans.” With approximately 1 288 employees at Venetia, he says the future integration of the open pit with underground operations is already in the planning stages, with the mine considering the range of implications for staff, infrastructure and other issues. The intention is to absorb as many employees as possible into the new phase of the mine, in order to retain as much of the company’s valuable skills base as possible. The environmental rehabilitation work – conducted on a concurrent basis – has been particularly successful, he says, with rock dumps being covered with topsoil, seeded and grassed on the northern side of the property. As the mine itself will not be closing, the end of the open pit will not necessitate a closure cer- tificate, but rehabilitation work will be ongoing. Water management remains a focus at

Above: An overview of Venetia’s K2 pit showing the haul road. Right: Pumping facilities in the K1 pit. Venetia, especially since significant floods in 2013 caused major disruption. Facilities are now in place to mitigate a 1-in- 200-year flood event, with pumping facilities in place at Bench 15 to dewater the pit’s main sump. The mine con-

serves large quantities of water by re-using rainwater from the pit. There are three dams in place as well as a circulation system that allows this water to be used for non-potable purposes like dust suppression and in the plant. Report by Paul Crankshaw

Venetia – SA’s biggest diamond producer Mining began in Venetia’s open pit in 1992, and has made the mine South Africa’s biggest diamond producer – contributing about 40 % of the country’s annual diamond output. The first kimberlite to be mined was K1 – which remains the backbone of the operation – followed by K2 in 2007 and K3 in 2010. The ‘Venetia cluster’ of kimberlites comprises around a dozen pipes located over an area of about three square kilometres, although the satellite pipes tend to be lower grade kimberlites; the surface areas of the actual kimberlites make up some 28 hectares. 

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March 2018  MODERN MINING  35