Blockbuster mine developer Ivanhoe Mines has reached a significant development milestone at its Platreef platinum/palladium/gold/nickel/copper discovery, on the northern limb of South Africa’s Bushveld Complex, after Shaft 1 reached a depth of 750 m.

Lateral development will now take place to create the first underground access to the high-grade orebody, which will enable the development team to continue with mine development while the main production Shaft 2 is being built.

The mining zones in the current Platreef mine plan occur at depths ranging from 700 m to 1 200 m below surface. Shaft 1’s 750 m station will also allow access for the first raisebore shaft that will provide ventilation to the underground workings during the mine’s ramp-up phase.

The first of the mine’s planned fleet of mechanised, mobile, underground mining equipment – a small 5.5 t load-haul-dump machine – had arrived on site and would be used for off-shaft station development work on the 750 m, 850 m and 950 m levels, Ivanhoe advised last week.

Sinking of the 7.25-m-wide Shaft 1 will resume after construction of the 750 m station has been completed. The shaft is expected to intersect the upper contact of the Flatreef deposit (T1 mineralised zone) at a shaft depth of about 783 m. As shaft sinking advances, two further 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 in 2019.

Shaft 2 will have an internal diameter of 10 m and the capacity to hoist six-million tonnes a year. The headgear design for the six-million-tonne-a-year permanent hoisting facility has been completed by South Africa-based Murray & Roberts Cementation. The company reported that the first two blasts had been successfully completed at surface for the boxcut for Shaft 2.

The project will produce platinum, palladium, rhodium and gold (3PGE+Au), as well as nickel and copper.

The first phase of the project will entail a four-million-tonne-a-year operation, with possible expansions to eight-million tonnes and 12-million tonnes in two further stages.

A July 2017 definitive feasibility study (DFS) has estimated a preproduction capital requirement of about $1.5-billion for the first stage, which will produce about 476 000 oz/y of 3PGE+Au, 21-million pounds of nickel a year and 13-million pounds of copper a year.

Platreef will rank at the bottom of the cash cost curve, at an estimated $351/oz of 3PGE+Au produced, net of by-products and including sustaining capital costs, and $326/oz before sustaining capital costs.

The DFS also estimates a net present value of $916-million and an after-tax internal rate of return of 14.2%; however, Ivanhoe expects the actual return to project equity owners to be higher as a result of the significant amount of project financing that is being raised.

Ivanhoe, which holds a 64% indirect interest in the Platreef project through its subsidiary, Ivanplats, appointed two mine-financing institutions and three financial institutions during 2017 to arrange the $1-billion in project financing for the development of Platreef.