Modern Mining January 2015

DIAMONDS

Above: Kalcon machines working in the Karowe pit. By the time this article is in print, MCC will have taken over as the mining contractor (photo: Arthur Tassell).

DEBTECH X-ray sorting machines. According to Paul Day, the current modi- fications to the plant – which are budgeted at US$55 million and which are scheduled to be completed in Q2 2015 – are intended to optimise operations and allow the facility to maintain throughput at 2,5 Mt/a as the orebody at depth is mined. “The plant in its present configuration was designed around treating the near surface material, which is weathered and transitional ore,” he explains. “It was always understood that it would have to be modified to handle the harder unweathered ore present at depth – in the South Lobe in particular. Quite apart from the need for increased comminution capacity, it was also understood that the char- acteristics of the ore change as we go deeper, with the near density material (material with a density close to that of diamond) steadily increasing. This, in turn, results in the DMS cir- cuit becoming less effective, and this is another issue we’re addressing with the upgrade. “What was not originally realised when the plant was designed is that Karowe would become a prolific producer of large stones. It was only in 2013 that we started to recover

“Since then we have experienced three LTIs, all of them minor in nature. Nevertheless, we view them seriously and we are currently putting an enormous effort into safety, with the emphasis on internalising safety behavior. Overall our safety performance, though, is creditable and thankfully we have never had a fatality.” When Modern Mining was at Karowe late last year the mining contractor in place was Kalcon (part of WBHO), which was operating a fleet of 36 Cat 730 and Cat 740 ADTs, work- ing in conjunction with Cat 345, Cat 374 and Cat 390 excavators. The mining operation was explained to Modern Mining by Mining Manager Joe Mchive, who said that the pit would produce around 3,8 Mt of ore and 11 Mt of waste by year end. He noted that stripping levels would steadily increase as work started on Cut 2, with the intention of exposing ore by 2018. He also said that Kalcon’s three-year con- tract was drawing to a close and that – based on the results of an open tender – it would be replaced by MCC as from January 2015. MCC’s contract is for six years and the com- pany will be deploying a fleet which includes 100-ton rigid trucks for waste and 40-t ADTs for ore, with the largest excavator being a 150-t Liebherr machine. The EPCM contractor during the initial con- struction of Karowe was DRA and Minopex, also part of the DRA Group, has an SLA (ser- vice level agreement) contract to operate and maintain the process plant. The current flow- sheet is fairly simple and consists of primary crushed ROM being processed through a sin- gle autogenous grinding (AG) mill with the +35 mm product crushed in a single pebble crusher and recirculated back to the mill and the +1,5, -35 mm mill product being processed through a DMS with final recovery using

Lucara – based in Canada but rooted in Africa Although it can trace its antecedents back to the 1980s, Lucara in its present form was founded in 2007, with its first CEO – and now Chairman – being Lukas Lundin. The present President and CEO, William Lamb, a South Afri- can-trained metallurgist, joined the company as GM in 2008 (he was previ- ously Process Manager at De Beers’Victor mine in Canada). Lucara is listed on the Toronto Stock Exchange, Nasdaq OMX Stockholm and the Botswana Stock Exchange and has its corporate office – very lightly staffed – in Vancouver. The company’s focus, however, is entirely in Africa at present and it maintains an office in Gaborone where COO Paul Day and Ribson Gabonowe, MD of Boteti Mining, Lucara’s subsidiary in Botswana, are based.

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January 2015  MODERN MINING  51