In its interim results for the six months ended 30 September, London-listed Vedanta Resources says that its Gamsberg zinc project in South Africa – being undertaken by Vedanta Zinc International – is on track to commence production in mid-2018.
According to Vedanta, pre-stripping as part of open-pit mine development is progressing to plan. Says the company: “We achieved the full ramp-up to pre-stripping mining volumes of 3,5 million tonnes per month in Q1 and have continued at that rate since. To date, we have excavated over 50 % of waste rock of the total pre-stripping requirement. Construction works for the concentrator and other infrastructure are progressing well with all contractors fully mobilised to site.”
View of the Gamsberg site. Note the access road up to the mining area (photo: Vendanta Zinc International).
Bulk civil works related to mills and crusher foundations are on track. Water and power infrastructure installation is also progressing on schedule with more than 50 % of the work completed. Manufacturing and supply of all equipment is on schedule with mills expected to be at site this month (November).
The first phase of the project is expected to have a mine life of 13 years, replacing the production lost by the closure of the Lisheen mine in Northern Ireland. Once commissioned, it is expected that the mine will take 9-12 months to ramp up to full production capacity of 250 000 t/a of zinc-in-concentrate. Cost of production is estimated at US$1 000 to US$1 150 per tonne.
Gamsberg forms part of the Black Mountain Mining (BMM) operations and is located about 30 km from the BMM base at Aggeneys in Northern Cape Province. Discovered more than 40 years ago and held undeveloped in the asset portfolios of various mining companies, it was acquired from Anglo American by the Vedanta group in 2011. The project’s current reserve and resource is 214 Mt, with a grade of between 6 and 6,5 %.
From the first blast for Phase 1 in July 2015, pre-start mining advanced according to schedule. Completion in April 2017 of an access ramp – essential for waste pre-stripping to access the orebody for bulk mining – was a significant milestone. The contractor for the bulk mining is Aveng Moolmans.
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 reactor (SFR) technology of Canada’s Woodgrove Technologies in the plant. Benefits of the technology over conventional mechanical cells reportedly include a much more compact footprint, reduced power and air requirements, less instrumentation and reduced wear and maintenance costs due to lower impeller tip speeds.
The Gamsberg team was able to robustly review the capital cost of Phase 1 and reduce it from US$600 million to US$400 million. These measures enhanced Gamsberg’s viability considerably during the period when the zinc price weakened.