|Workers prepare a jumbo before drilling blast holes. The Bakubung mine, a greenfield project, is on schedule to deliver full production by 2020. (Photo by Gavin du Venage)|
Work is progressing satisfactorily at one of the very few greenfield platinum projects under way in South Africa, according to South African Editor Gavin du Venage, with the Bakubung mine shaft sinking moving ahead of schedule and touching the orebody for the first time.
The project is majority owned by Wesizwe Platinum, which in turn was bought by Chinese iron mining company Jinchuan in 2010. It was a pioneering investment that brought one of the first-ever Chinese firms to the South African mining scene, and even during the heady days of the commodity boom, it was seen as risky.
“The project is on schedule and proceeding well,” Bakubung General Manager Eddie Mohlabi said. “Everything is going according to plan.”
Recently, the platinum belt has endured some trying times, having endured the longest strike in the country’s mining sector, which lasted for nearly half of 2014. The Bakubung project, though, is blasting through milestones as it heads toward production in 2020. An optimist may say the company’s management will have plenty of time to learn from the mistakes of its peers by the time it achieves first pour.
During the latter half of 2014, work proceeded on sink cutting for both the main and ventilation shafts; a milestone was reached with the cutting of the first station at 690 m on the ventilation shaft, and another target was reached soon after on the main shaft.
Sinking has since intersected the Merensky Reef for the ventilation shaft—the motherload of the platinum belt. The main shaft is now 730 m below collar and just above Merensky. Currently, the ventilation shaft is about 750 m underground and the next major milestone will be intersecting the Underground 2 (UG2) reef, about 40 m below Merensky.
The ventilation shaft, targeted to reach its final depth of 880 m in September 2016, is reported to be 144 days ahead of schedule.
Conventional sinking is the method being used, with jumbo drilling and cactus-grab serving to prepare the blasting environment and remove debris. South Africa’s Aveng Underground Mining is
The main shaft will eventually be developed to 970 m, will have a hoisting capacity of 255,000 mt of ore and 15,000 mt of waste a month. Shaft sinking would be completed by October next year, 55 days ahead of schedule.
Meanwhile, geological work has also delivered promising results. Geologist Linda Sithole said the mine falls within the western limb of the Bushveld Complex, just south of the Pilansberg intrusion. Samples taken from the just accessed Merensky area have already shown indications of PGMs.
“The first signs were significant levels of sulphur,” Sithole said. “When you find sulphur, as a geologist you get excited.”
The company is now bulk sampling; ore is hand-sorted and loaded into bags of around 730 kg each. Grade is between 5.6–6.5 g/mt on average, although indications of up to 6.9 g/mt are also in evidence. Samples had been taken from the hanging wall and the foot wall, Sithole said.
“Few areas have been drilled as extensively as this mine,” added Mohlabi. “We have drilled the area rotten.”
At full production, the mine will produce 420,000 oz/y of PGMs. Platinum will account for 62.4%, rhodium for another 7.4%, palladium at 28% and gold at 2.2%. Merensky is expected to provide 230,000 metric tons (mt) per month, with the balance sourced from the UG2 reef. Once Merensky becomes depleted in the next 10 to 15 years, the full 255,000 mt will be sourced from the UG2 reef only.
An optimization plan adopted earlier this year ensured that the mine would undergo its main commissioning in the fourth quarter of 2018, before being ramped up to full production in 2020. This is two years ahead of the original plan, which wouldn’t have seen full production until 2022.
The project’s Chinese management team has been content to leave the South African team to get on with it. Mohlabi said that apart from technical oversight to keep the head office updated, Jinchuan has kept a light touch on the project. Life-of-mine is expected to be 30 years.