Modern Mining January 2015

DIAMONDS

than 10,8 carats, including 67 larger than 50 carats and 25 larger than 100 carats.” In fact, several stones have been above 200 carats, with the biggest to date being 281 carats. Diamonds above 100 carats – and, even more so, 200 carats – are extremely rare and, apart from Karowe, the only other regular produc- ers of stones this size in the Southern African region – and indeed globally – are Letšeng in Lesotho, owned by Gem Diamonds, and Petra’s Cullinan mine near Pretoria. The value of Karowe’s diamonds has also been greater than originally anticipated, with the average price achieved in H1 2014 being over US$750/ct (including all the ‘specials’ above 10,8 ct). Operationally, Karowe is run on an out- sourced model, with contractors running the main functions of open-pit mining operations and ore processing. The mine is operated by Lucara’s local subsidiary Boteti Mining headed by MD Ribson Gabonowe. Day-to-day manage- ment of the mine is in the hands of GM Gerry Ndlovu and the total employee complement he is responsible for (including contractors) is around 800 people. He takes satisfaction from the fact that his senior managers are mainly Batswana with just one expat in the team. Ndlovu is a metallurgist (he graduated from Queen’s University in Kingston, Ontario, Canada) and prior to joining Boteti Mining in 2010 spent nearly 20 years with BCL in Selebi-Phikwe. He was Karowe’s third employee and has seen the project move through from concept to commissioning to operation. Like Day, he labels it a “huge success” but says that a particular focus at the moment is safety. “In 2012 we were one of the best performing mines in Botswana in terms of safety and received an award from the Botswana Chamber of Mines,” he notes.

a formidable high US$/carat resource. The mine plan is based on probable reserves of 33,1 Mt containing 5,1 million carats from an open pit designed to 320 m depth. The indi- cated resource from surface to a depth of 400 m amounts to 48 Mt containing 7,6 million carats. There is also an inferred resource from 400 m to 750 m of 21 Mt containing 3 million carats. The deposit is open at depth. The geologists describe AK6 as “a three-lobed body primarily composed of volcanoclastic kimberlite with lesser hypabyssal facies kim- berlite.” The three lobes are referred to as the North, Centre and South lobes, with the bulk of the reserve (75 %) being contained in the South Lobe. All the lobes are currently being mined and the North Lobe, the initial focus of mining operations, is over 60 %mined out. At the pres- ent processing rate of approximately 2,5 Mt/a, the open-pit mine life is around 13 years – with the ultimate dimensions of the pit expected to be 800 m x 700 m by 320 m. Commenting on the performance of Karowe, Paul Day – who joined Lucara as COO in March 2013 and who was previously GM at the Trekoppje uraniummine in Namibia (and before that a senior manager with AngloGold Ashanti in Mali) – says the mine has met Lucara’s expectations, and more. “It was designed to be roughly a 400 000 carats a year producer and we are achieving this easily,” he says. “In 2013 we produced just over 440 000 carats and our guidance for 2014 is between 400 000 and 420 000 carats at an operating cost of US$31 to US$33 per tonne treated. But the really exciting feature of Karowe is the sheer number of large stones that have been recovered which is way ahead of what Lucara expected when it com- missioned the mine. For example, in the first half of 2014 we recovered 547 diamonds larger

Above: Aerial view of the Karowe mine, which is located in the Orapa Kimberlite Field near the town of Letlhakane. Centre: The pit at Karowe. All the lobes are currently being mined and the North Lobe, the initial focus of mining operations, is over 60 %mined out. Remaining pit life is about 13 years (photo: Arthur Tassell).

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50  MODERN MINING  January 2015