Shaft Sinking Begins at Ivanhoe’s Platreef Project

Nighttime view of the headframe at Ivanhoe Minerals’ Platreef
Shaft 1. Final depth of the 7.25-m-diam shaft will be 1,025 m.
(Photo: Ivanhoe Minerals)
Ivanhoe Mines began permanent shaftsinking work on Shaft 1 at the Platreef platinum-group-metals, nickel, copper, and gold project in South Africa in mid-July. The shaft will have an internal diameter of 7.25 m and will provide initial access for early underground development. A second shaft, Shaft 2, is planned for Platreef. It will be the project’s main production shaft—10 m in diameter and with capacity to hoist 6 million metric tons per year (mt/y). Early works for Shaft 2 are scheduled to begin next year.

Sinking of Shaft 1 is now progressing at rate of 1.8 m/d, targeting an initial depth of 107 m below surface, at which point the main sinking phase will begin. The main sinking phase is planned to advance at an average rate of 2.7 m/d until it reaches a final depth of 1,025 m below surface in 2018.

Aveng Mining holds the Shaft 1 shaft-sinking contract, including development of two main stations at depths of 450 m and 750 m below surface. Sinking is scheduled to reach the Flatreef deposit at a depth of 777 m during the third quarter of 2017. Mining areas proposed in the current prefeasibility study occur at depths ranging from approximately 700 m to 1,200 m below surface.

Mining is planned in three phases: 1) an initial mining rate of 4 million mt/y to establish an operating platform to support future expansions; 2) a doubling of production to 8 million mt/y; and 3) a final expansion to steady-state production of 12 million mt/y.

Mining methods will include long-hole stoping and drift-and-fill mining. Minedout areas within the deposit will be backfilled with a paste mixture utilizing tailings from the process plant and cement. Ore will be hauled from the stopes to a series of ore passes that will connect to the main haulage level to Shaft 2. Ivanhoe Mines owns 64% of the Platreef project through a subsidiary, Ivanplats, and is directing all mine development work.

PEA Backs Kipushi Redevelopment: In other news from Ivanhoe, the company has reported the results of a positive preliminary economic assessment (PEA) for redevelopment of the Kipushi zinc-copper mine 30 km southwest of the provincial capital of Lubumbashi in southeast Democratic Republic of Congo (DRC). The Kipushi mine produced approximately 60 million mt of ore grading 11% zinc and 7% copper between 1924 and 1993. Ivanhoe acquired its 68% interest in the mine in November 2011. The balance is held by the DRC’s state-owned mining company, Gécamines.

The redevelopment PEA focuses on mining of Kipushi’s Big Zinc zone to produce an average of 530,000 mt/y of zinc concentrate over a 10-year mine life at a concentrate grade of 53% zinc. Total preproduction capital costs to redevelop the mine are estimated at $409 million. Life-of-mine average cash cost of production is estimated at $0.54/lb of zinc.

Existing underground infrastructure at Kipushi includes a series of vertical mine shafts to various depths, with associated head frames. The newest shaft, No. 5, is 8 m in diameter and 1,240 m deep. The PEA assumes this shaft will be recommissioned as the main production shaft, providing primary access to the lower levels of the mine through an existing haulage level 1,150 m below surface.

Kipushi’s Big Zinc zone has an estimated 10.2 million mt of measured and indicated mineral resources grading 34.9% zinc. Successful restoration to production would make Kipushi the world’s highest-grade major zinc mine.

As featured in Womp 2016 Vol 08 -