TORONTO (miningweekly.com) – Africa-focused project developer Ivanhoe Mines has released an updated mineral resource estimate for its flagship Platreef platinum-group metals (PGMs) nickel, copper and gold project on South Africa’s Bushveld Complex’s northern limb, located near the town of Mokopane, in Limpopo.

The TSX-listed firm reported an increase of 58% in the compliant indicated mineral resources tonnage to 346-million tonnes, at a grade of 3.77 g/t platinum, palladium, rhodium plus gold (3PE+Au), 0.32% nickel and 0.16% copper, at a cutoff grade of 2 g/t 3PE+Au.

The updated mineral resource had also calculated an increase of 21% in the inferred mineral resources tonnage to 506-million tonnes, at a grade of 3.24 g/t 3PE+Au, 0.31% nickel and 0.16% copper, at a cutoff grade of 2.0 g/t 3PE+Au.

Contained metal in the indicated resources rose 45%, at a cutoff grade of 2 g/t 3PE+Au, totalling 41.95-million ounces of 3PE+Au, plus a 47% increase in nickel to 2.44-billion pounds and a 50% increase in copper to 1.23-billion pounds, the company advised on Wednesday.

Contained metal in the inferred resource category, at a cutoff grade of 2 g/t 3PE+Au, had increased by 11% to total 52.77-million ounces of 3PE+Au, nickel had increased by 13% to total 3.44-billion pounds and copper had increased by 18% to 1.78-billion pounds, the company stated.

Mineralisation was found within a 19 m seam, on average, in the area of the TCU-T2 deposit, where indicated resources were estimated, and within a 13 m seam, on average, where inferred resources were estimated, using the 2 g/t 3PE+Au cutoff.

The updated estimate was for mineral resources amenable to underground mining methods within Platreef’s Flatreef deposit.

It was the first update of the overall resource estimate to be issued in more than three years. The new estimate included the Turfspruit Cyclic Unit (TCU), which hosted the majority of the Flatreef mineral resources, and also two underground zones of mineralisation – the Footwall and the Bikkuri – that occurred near to the TCU.

Ivanhoe noted that the Flatreef deposit was characterised by its extremely large vertical thicknesses of high-grade mineralisation and a platinum-to-palladium ratio of about 1:1, which, according to the company, was significantly higher than other recent PGM discoveries on the Bushveld Complex’s northern limb.

The company billed the project as having the potential to become a new model for safe, mechanised, underground platinum mining in South Africa.

The Platreef project was owned by Ivanplats, which was 64%-owned by Ivanhoe Mines. A 26% interest was held by Ivanplats’ broad-based black economic-empowerment partners, which included 20 local host communities that housed about 150 000 people, historically disadvantaged project employees and local entrepreneurs. A Japanese consortium of ITOCHU Corporation and its affiliate, ITC Platinum, plus Japan Oil, Gas and Metals National Corporation and JGC Corporation, owned a 10% interest in Ivanplats.