TSX-listed Ivanhoe Mines’ Platreef Shaft 1 in South Africa has reached the top of the high-grade Flatreef deposit at a depth of 780.2 m.
The achievement by the Ivanplats shaft-sinking team is the first time that the Platreef – a strongly mineralised, polymetallic belt that extends northward from the town of Mokopane for more than 30 km – has been intercepted by underground mining activity.
Ivanplats’ Flatreef deposit, with a strike length of 6 km, lies within a flat to gently dipping portion of the Platreef mineralised belt at relatively shallow depths of approximately 700 to 1 200 m below surface.
The Platreef mining team has delivered the first ore from the underground mine development to a surface stockpile for metallurgical sampling.
The estimated thickness of the mineralised reef (T1 & T2 mineralised zones) at Shaft 1 is a never-seen-before 26 m, with grades of platinum-group metals ranging up to 11 g/t 3PE (platinum, palladium and rhodium) plus gold, as well as significant quantities of nickel and copper.
The 26 m intersection will yield approximately 3 000 t of ore, estimated to contain more than 400 oz of platinum-group metals (PGMs).
“This is a significant milestone for Ivanplats and a tribute to the excellent work by the Platreef Project team and its South African sinking contractor, Aveng Mining,” says Ivanplats’ MD Dr. Patricia Makhesha.
“We now can proudly show our stakeholders and investors Flatreef’s remarkably high-grade and thick, flat-lying orebody that is ideal for safe, underground, bulk-scale, mechanized mining.
“Our focus is to keep advancing the Platreef Project along its critical path. We remain true to our commitment to build Platreef into the world’s next great platinum-group metals mine ─ a showcase for South Africa and the international investors that have financed the exploration and development work,” adds Makhesha.
Ivanplats’ Executive Co-Chairman, Robert Friedland notes that while some investors have expressed concern about the current price of platinum, Platreef also has massive quantities of palladium, nickel and copper, as well as rhodium and gold.
He says the steady surge in the price of palladium could see it become more valuable than gold for the first time in 16 years, and rhodium prices are near eight-year highs.
The platinum-to-palladium ratio at the Platreef Mine is approximately 1:1.
Palladium and rhodium are used as catalysts to control exhaust emissions in gasoline-fuelled vehicles, while diesel vehicles mostly use platinum.
Platinum also is used as the catalyst in zero-emission, hydrogen-powered, fuel-cell electric vehicles now being developed.
“Building a new, large-scale mine such as Platreef is a capital- and time-intensive process that requires us to embrace the future, and the future we see will include more electric vehicles using batteries and fuel cells,” says Friedland.
“We are confident that platinum, copper and nickel will be among the biggest beneficiaries of the accelerating global transition to electric vehicles and clean energy.
“The Northern Limb is the future of platinum-group-metals mining. We will have the distinct advantage of having a highly-mechanized, underground mining operation with a small environmental footprint.
“On behalf of our stakeholders, international shareholders and progressive end users of our metals, we are pleased to be leading the positive transformation in the way future underground platinum mining operations in South Africa will be conducted,” adds Friedland.
In July 2017, Ivanhoe issued an independent, definitive feasibility study (DFS) for Platreef covering the first phase of production at an initial mining rate of 4 Mtpa.
The DFS estimated that Platreef’s initial, average annual production rate will be 476,000 oz of platinum, palladium, rhodium and gold, plus 21 million pounds of nickel and 13 million pounds of copper.
Flatreef is an estimated 26 m thick at Shaft 1 intersection
Geotechnical drill hole GT008, drilled vertically below Shaft 1, indicates that the grade for the T1 mineralized zone at the Shaft 1 location is 4.83 g/t 3PE plus gold, 0.33% nickel and 0.15% copper over a vertical thickness of 12 m.
A well-developed chromitite stringer, marking the stratigraphic contact between the T1 and T2 mineralized zones, is expected to be intersected at a shaft depth of approximately 795 m.
This will be followed by the T2 mineralized zone, which grades 4.14 g/t 3PE+gold, 0.35% nickel and 0.18% copper over a vertical thickness of 11.26 m (at a 2 g/t 3PE+gold grade cut-off).
Completed 750-metre station on Shaft 1 will provide initial, underground access to the high-grade Flatreef orebody
The 750-metre station on Shaft 1 will provide initial, underground access to the high-grade orebody, enabling mine development to proceed during the construction of Shaft 2, which will become the mine’s main production shaft.
The mining zones in the current Platreef Mine plan occur at depths ranging from approximately 700 m to 1,200 m below surface.
Shaft 1’s 750-m station also will allow access for the first raise-bore shaft, which will have an internal diameter of six m, to provide ventilation to the underground workings during the mine’s ramp-up phase.
As shaft-sinking advances, two additional shaft stations will be developed at mine-working depths of 850 m and 950 m.
Shaft 1 is expected to reach its projected, final depth of 980 m below surface, complete with the stations, in early 2020.
The thick, flat-lying orebody at the Platreef Project is ideal for bulk-scale, mechanized mining.
As underground development progresses, the mine plan calls for the addition of large, mechanized mining equipment, such as 14- and 17-t load-haul-dump machines and 50-t haul trucks to support the planned long-hole mining method.
Approximately 40% of Platreef’s shaft-sinking team now is comprised of employees from local Mokopane communities who had no previous mining experience.
New employees receive intensive, on-site training for underground mining and complete a workplace-safety induction program.
Construction progressing well at Shaft 2 surface box cut
Excavation of the Shaft 2 box cut to a depth of approximately 29 m below surface is progressing well.
Completion of the box cut will allow for the construction of the concrete hitch (foundation) for the 103-m-tall concrete headgear (headframe) that will house the shaft’s permanent hoisting facilities and support the shaft collar.
Shaft 2, to be located approximately 100 m northeast of Shaft 1, will have an internal diameter of 10 m, will be lined with concrete and sunk to a planned, final depth of 1,104 m below surface.
It will be equipped with two 40-t rock-hoisting skips with a capacity to hoist a total of 6 Mt of ore per year – the single largest hoisting capacity at any mine in Africa.
Headgear for the permanent hoisting facility was designed by South Africa-based Murray & Roberts Cementation.
Platreef’s development team has decided to unbundle the complete Shaft 2 sinking contract into smaller commitment portions, while still maintaining the critical development path.
Development focused on construction of a state-of-the-art underground mine
The Platreef Project is located on the Northern Limb of the Bushveld Complex, adjacent to Anglo Platinum’s Mogalakwena Mine.
The Platreef Project, which contains the Flatreef Deposit, is a tier-one discovery by Ivanhoe Mines’ geologists.
Based on the findings of the July 2017 independent DFS, Ivanhoe plans to develop the Platreef Mine as a major underground mining operation in three phases to achieve: 1) An initial rate of 4 Mtpa to establish an operating platform to support future expansions; 2) a doubling of production to eight Mtpa; and 3) expansion to a steady-state 12 Mtpa.
As Phase 1 is being developed and commissioned, there would be opportunities to refine the timing and scope of subsequent phases of expanded production.
Given the size and potential of the Platreef Mineral Resource, Shaft 2 has been engineered with a crushing and hoisting capacity of 6 Mtpa.
This allows for a relatively quick and capital-efficient first expansion of the Platreef Project to 6 Mtpa by increasing underground development and commissioning of a third, two-Mtpa processing module and associated surface infrastructure as required.
A further expansion to more than 8 Mtpa would entail converting Shaft 1 from a ventilation shaft into a hoisting/ventilation shaft.
This would require additional ventilation exhaust raises, as well as a further increase of underground development, commissioning of a fourth, 2-Mtpa processing module and associated surface infrastructure, as described in the PEA as Phase 2 of the project.