Modern Mining January 2017

ZINC

as a substantial amount of productive capac- ity has been taken out of the market over the past couple of years and has not been replaced. “We’ll be the first new mine to start-up in what is increasingly a market in deficit,” she says. “The zinc price will obviously incentivise oth- ers to bring on line new mines but at this stage we’re way ahead of everyone else.” One spin-off of the price plunge in early 2016 was that it motivated VZI to look at ways of cutting Gamsberg’s capital budget. “We were originally planning to owner mine at Gamsberg but have now decided to use a mining contrac- tor and this, of course, is a less capital intensive approach,” says Naidoo. “We’ve also renegoti- ated various contracts and re-engineered the project to deliver substantial savings. All told, we’ve reduced the capex by US$200 million – which is an amazing achievement.” Updating on the current status of the project, Kumar – who used to be the GM at Skorpion – says the ground-breaking ceremony was held in July 2015 and that there are now around 300 workers on site, with this figure expected to peak at 1 500 at the height of construction. “Gamsberg is an inselberg that extends about 220 m above the surrounding ‘flats’,” he says. “We will be mining on top of the insel- berg, so we’ve had to build roads to access the mining area. We appointed a local Northern Cape contractor, Roux Mining, to carry out this work and to establish the starter pit and they are making very good progress. Roux is what we call the ‘pre-start contractor’ but we have now appointed our bulk mining contrac- tor, Aveng Moolmans, who will soon mobilise to site. There’s a huge amount of pre-stripping required to expose the orebody – close to 70 Mt – so we will only start producing ore in the middle of 2018. Although most of this pre- stripping will be the responsibility of the bulk mining contractor, Roux has made a start on it and 12 Mt has been moved already.” According to Kumar, the mining operation at Gamsberg will be a conventional load-and- haul exercise. “We have asked the contractor to use the latest technologies in drilling but other than this there is nothing unusual about the approach being adopted. The strip ratio in Phase 1 is about 7 to 1 so to achieve our targeted ore production we’ll be moving over 30 Mt/a. The explosives supply has been contracted out to BME, who have been performing that func- tion since 2015 when work first started on site.” Moving to the process plant, Kumar describes the flowsheet as “conventional with some tweaks” and says it will include primary crushing, milling (via SAG and ball mills),

flotation and dewatering. “We have three stages of flotation, the first to take out carbon, the sec- ond to remove the lead and the third for zinc, with the final product being a 48 to 52 % zinc concentrate,” he notes. He adds that the tail- ings facility will be constructed to the highest standards and will be HDPE lined. The EPCM contractor for the processing facility (and related infrastructure including the power and water plants) is ELB Engineering, who will be using – for the first time in a zinc application – the new staged flotation reac- tor (SFR) technology of Canada’s Woodgrove Technologies in the plant. Benefits of the tech- nology over conventional mechanical cells reportedly include a much more compact foot- print, reduced power and air requirements, less instrumentation and reduced wear and mainte- nance costs due to lower impeller tip speeds. As regards the power required, VZI has con- cluded an agreement with Eskom to supply 40 MW. The bulk water will be sourced from the Orange River, just 33 km to the north of the site. BMM already draws around 13 Mℓ a day from the Orange for its current operations and the new project will essentially double up on this. Additional housing will also be needed in the town of Aggeneys as the Gamsberg proj- ect will generate over 500 new permanent jobs once in full production. While Gamsberg, like any big mining project, has its share of technical challenges, perhaps the biggest challenge of all is its location in the arid Northern Cape in an area that has been identified as a biodiversity hotspot. Explains Naidoo: “Gamsberg lies in the Succulent Karoo Biome – one of only four hotspots in South Africa – which is home to 6 000 plant spe- cies, and it also forms part of the Bushmanland

Acting Mining Manager Mario Cloete on site at Gamsberg.

“The zinc price will obviously incentivise others to bring on line newmines but at this stage we’re way ahead of everyone else.”

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January 2017  MODERN MINING  59