Ivanhoe Mines’ 64% platinum-focused subsidiary Ivanplats is making remarkable progress at its multi-billion dollar Platreef project, located just outside Mokopane on the Northern Limb of the Bushveld Complex.
The project will intersect its ultra-thick, 19 m ‘flatreef’ at Shaft 1 in just 30 m – which will represent a milestone achievement in the development phase. With five years of development work already behind it, Ivanplats’ Vice President & Executive Head of Projects Gerick Mouton says the project remains on track – an impressive feat considering this is one of the largest projects being developed in South Africa at present.
Shaft sinking at Shaft 1 is quickly approaching completion – it is now 750 m below surface and needs to extend to a depth of 980 m once finished.
This article first appeared in Mining Review Africa Issue 6 2018
The 750 m mark is in itself a major achievement as it enables lateral development of the first mine access station to commence.
This station will provide initial underground access to the high grade Platreef ore body, enabling mine development to proceed during the construction of Shaft 2, which will become the mine’s main production shaft.
It will also allow access for the first raisebore shaft that will provide ventilation to the underground workings during the mine’s ramp-up phase.
Sinking of Shaft 1 will resume after the 750 m station is completed in the next few months.
“The shaft is expected to intersect the upper contact of the Flatreef Deposit at approximately 783 m before the end of the year.”
Both Mouton and Ivanhoe Mines’ chairman Robert Friedland eagerly await the reef intersection – “Soon we will be able to show our stakeholders and investors Flatreef’s remarkably thick, high-grade mineralised zones that will allow us to be at the forefront of safe, underground bulk mining,” Friedland highlights.
And while activity continues with speed underground at Shaft 1, Ivanplats is making quick and steady progress in development work at its second shaft – located just 100 m adjacent to Shaft 1.
The first two surface blasts for Shaft 2’s box cut were successfully completed in April 2018.
This blasting will enable the excavation of the box cut to a depth of approximately 29 m below surface and the construction of the concrete hitch (foundation) for the 103 m-tall concrete headgear (headframe).
Similar in size and design to Impala Platinum’s 16 Shaft headgear, it will house the shaft’s permanent hoisting facilities and support the shaft collar.
Excavation of the box cut is expected to be completed by the end of the year.
“Shaft 2 will have an internal diameter of 10 m and 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,” Mouton outlines.
Headgear for the permanent hoisting facility was designed by South Africa-based Murray & Roberts Cementation.
DFS delivers promising numbers
In July 2017, Ivanhoe issued an independent, definitive feasibility study (DFS) for Platreef that covers the first phase of production at an initial mining rate of 4 Mtpa.
The DFS estimates that Platreef’s initial, average annual production rate will be 476 000 oz of platinum, palladium, rhodium and gold, plus 21 Mlb of nickel (at 0.3% nickel) and 13 Mlb of copper (at 0.15% copper).
Subsequently, the company is working with potential concentrate processing partners to study ways to incorporate an upgrading step to produce battery-grade nickel sulphate.
Building the mine in phases will assist in managing the capital outlay to establish what could be the world’s largest PGE mine.
At +450 000 4E ozpa, Platreef would already be ranked as the third largest PGE mine in the world however.
“Our strategy is to start small and sell our concentrate into the local market which eliminates the need to pre-commit to smelting and refining, although we will evaluate this option as we expand the operation – based on capacity in the market at the time.”
The intention is to increase production to 6 Mpta prior to a full-scale second phase ramp-up to 8 Mtpa – followed thereafter by a third phase expansion to 12 Mtpa – should the market require this.
Although this is considerably well into the distant future at this stage, Mouton affirms that even at this enormous scale, the mine could still deliver production for several decades.
An increase to 8 Mtpa would not prove too difficult. “Shaft 1 has been designed to hoist 2.5 Mtpa.
Shaft 2 will have a capacity of 6 Mtpa and in combination with Shaft 1 could easily ramp-up to deliver the second phase 8 Mtpa production target,” Mouton confirms.
Like Impala Platinum’s 16 Shaft, the 103 m-tall Platreef headgear will be straight and concrete in design, incorporating Koepe winders inside near the top of the headgear given that footprint space on surface is limited.
“This will be an iconic mining symbol in Limpopo and one of the tallest structures in the province.”
The connecting shaft will be 10 m in diameter and concrete lined as well - which will easily accommodate transporting the mechanised equipment underground.
Mining the “flatreef”
Because of the thick ore body, the predominant mining method selected for optimal extraction of the flatreef is longhole stoping.
The underground main haulages will be a minimum of 5 m wide x 5 m high to enable the large, heavy duty equipment to move seamlessly.
The stopes will be 15 m wide by 20 m high and up to 60 m in length.
“There will be 20 active stopes on average at any given time to reach the target capacity of moving around 11 000 tpd of ore,” Mouton outlines.
The mine will also backfill the mined-out stopes.
To minimise its surface environmental impact, 60% tailings will be used as backfill material which will result in a small tailings footprint which will be located about 8 km away from the mine’s infrastructure footprint in an uninhabited area.
With such massive mining areas, the mechanised longhole stoping method makes economic sense and will be delivered like never seen before within the underground PGE mining environment.
“This also requires skills sets unseen in South Africa. Equipment operators will have the skills set not only to operate the machine effectively, but to do fault finding as well.”
Ivanplats is also focused on being on the low left quartile of the global cash cost curve, which is achievable according to Mouton because “our ore body dictates our mining approach”.
The thick, unconventional Merensky Reef lends itself to full-scale mechanised mining which has the added benefit of delivering highly safe working conditions and upskilled technicians and mining operators.
Approximately 40% of Platreef’s shaft-sinking team now is comprised of employees from local communities who had no previous mining experience. New employees receive intensive, on-site training for underground mining and complete a workplace-safety induction programme.
The first of the mine’s planned fleet of mechanised, mobile, underground mining equipment – a small, 5.5 t LHD has arrived on site and will be used for off-shaft station development work on the 750, 850 and 950 m levels.
The LHD will be the first piece of mechanised, mobile equipment to be used underground on the Northern Limb of South Africa’s famous Bushveld Complex.
As underground development progresses, the mine plan calls for the addition of significantly larger mechanised mining equipment, such as 14 t and 17 t LHDs and 50 t haul trucks.
“As we approach reef intersection at Shaft 1, we look forward to celebrating this milestone achievement.
"It will validate our promises to market to mine this ultra-thick flatreef which in combination with the entire project’s status as a mechanised mine, will make Ivanplats one of the most cost effective PGM miners in South Africa,” Mouton concludes.