Northam Platinum Ltd has announced the successful completion of the raise-bore pilot hole for the planned Number 3 Shaft at Zondereinde mine’s western extension. The new shaft system will provide additional access from surface to the underground workings for hoisting of men, material, services and ore.
The western extension was acquired on 6 December 2017 from the neighbouring Amandelbult mine, owned by Anglo American Platinum Ltd, for a cash consideration of ZAR1 billion. It comprises a 3.6 km wide mining block containing a PGM resource of over 21 Moz hosted within high-quality Merensky and UG2 orebodies.
The acquisition of the western extension significantly reduced Zondereinde’s operational risk profile and extends the mine’s life to beyond 30 years. Optimising these benefits required the development of an additional vertical shaft to supplement the existing two shafts at Zondereinde – this is the Number 3 Shaft project which was initiated in May 2019.
Number 3 Shaft is being raise-bored by Master Drilling. Raise-boring is safer, quicker and more cost effective than traditional drill and blast development. Raise-boring comprises two key phases; the drilling of a pilot hole, followed by reaming of this hole to its ultimate diameter. Critical to the success of raise-boring, especially when developing a hoisting shaft, is the accuracy of pilot drilling which becomes increasingly challenging the longer the hole.
The successful completion of the Number 3 Shaft pilot hole, at 1,382 m length, is a world record, the previous record being a 1,070 m shaft, drilled in 2012 at Lonmin’s K4 mine.
Drilling commenced on 25 September 2019 and holed into its receiving chamber underground on schedule on 18 July 2020. Master Drilling used ground-breaking oil-well directional drilling technology to limit lateral deflection on the 400 mm diameter pilot to less than half the hole diameter. Reaming of the hole to its final diameter will now commence and is expected to be completed during the coming year.
In parallel with the piloting of Number 3 Shaft, development of lateral access tunnels underground is progressing ahead of expectations and ore stoping is underway.
Paul Dunne, Northam’s Chief Executive Officer, said “this milestone has put us a significant step closer to realising the potential of the western extension, a high quality block of ground that has already breathed new life into Zondereinde. Our strong culture of technological innovation and rapid implementation is helping to create a mine that will benefit all stakeholders for many years to come. Congratulations to the Zondereinde management team and our partners, Master Drilling, on this record-breaking achievement.”