VANCOUVER (miningweekly.com) – Canadian project developer Ivanhoe Mines is on track with the modernisation and upgrading of the Kipushi zinc/copper mine, in the Democratic Republic of Congo, having re-established clear and safe access to all areas of the main underground workings, the company stated Wednesday.

The current mine redevelopment plan, as outlined in the May preliminary economic assessment (PEA), includes a two-year construction period with a relatively quick ramp-up to a projected steady-state production of 530 000 t/y of zinc concentrate.

A prefeasibility study (PFS) is currently under way to refine the findings of the PEA and to optimise the mine’s redevelopment schedule, life-of-mine operating costs and initial capital costs required to bring the mine back into production. Ivanhoe expects to complete the PFS in the second quarter of 2017.

PROJECT PROGRESS
Kipushi Corporation, a joint venture between Ivanhoe (68%) and State-owned mining company Gécamines (32%), operates the Kipushi mine. It has upgraded the operating shafts, winders and underground infrastructure at the Cascade section of the mine, which are expected to serve as alternate personnel and material shafts – as well as a second egress route from the mine. A new high-volume ventilation fan has also been installed on surface at Shaft 4 to provide fresh air to the underground workings.

The main production shaft for Kipushi, Shaft 5, is in the process of being upgraded and recommissioned. The main personnel and material winder has been upgraded and modernised to meet western industry standards and safety criteria, and new cages will be installed in 2017. The rock-hoisting winder, which will have a potential annual hoisting capacity of 1.8-million tonnes, is being upgraded and is expected to be fully operational in late 2017.

Ivanhoe advised that the critical path for the redevelopment of the mine runs through the upgrading of the Shaft 5 rock-hoisting winder, as well as the recommissioning of the main pumping station at Shaft 5, the underground crusher at the bottom of Shaft 5, the Shaft 5 rock load-out facilities and the restoration of the main haulage way on the 1 150 m level between the Big Zinc access decline and Shaft 5.

Shaft 5, which is planned to be the mine’s main production shaft, is 8 m in diameter, 1 240 m deep and about 1.5 m from the planned main mining area. The rock hoist and load-out system will be upgraded to western industry standards during 2017 to fully restore the shaft’s hoisting capacity. Shaft 5 provides the primary access to the lower levels of the mine, including the Big Zinc deposit, through the 1 150 m haulage level and underground ramp decline.

The planned primary mining method for the Big Zinc deposit in the PEA and PFS is sublevel open stoping, with cemented backfill. The crown pillars are expected to be mined once adjoining stopes are backfilled using a pillar-retreat mining method. The Big Zinc deposit is expected to be accessed via the existing decline and without any significant new development. The main levels are planned to be at 60 m vertical intervals, with sublevels at 30 m intervals.

STANDOUT DEPOSIT
Kipushi mine's PEA and PFS focus on the mining of its ‘Big Zinc’ deposit, and have an estimated 10.2-million tonnes of measured and indicated resources grading 34.9% zinc.

Ivanhoe noted that analysis by international industry research and consulting group Wood Mackenzie has placed Kipushi’s zinc grade at more than twice as high as the measured and indicated resources of the world’s next-highest-grade zinc project.

The Kipushi PEA was based on a long-term zinc price of $2 227/t of zinc, producing an average of 530 000 t/y of zinc concentrate over a ten-year mine life at a total cash cost, including copper by-product credits, of about $0.54/lb of zinc.

After-tax net present value (NPV), at an 8% real discount rate, is $533-million, with an after-tax real internal rate of return (IRR) of 30.9%, providing a payback period of 2.2 years.

At a long-term zinc price of $2 500/t, near the current zinc price, the after-tax NPV is $794-million, scaling to $1.27-billion at a long-term zinc price of $3 000/t.

The zinc price has rallied 65% since the start of the year as a widening supply gap has emerged and above-ground stocks are being drawn down.