Ivanhoe Mines has announced a positive, independent 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 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 pre-production capital costs to develop the project are estimated at $409 million. Life-of-mine average cash cost of production is estimated at $0.54/lb of zinc, placing the mine in the bottom quartile of the cash cost curve for zinc producers globally.

Leveraging Kipushi’s existing surface and underground infrastructure will significantly lower the required redevelopment capital as compared to a greenfield project and also will shorten the time required to renew production to about two years.

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

Existing underground infrastructure includes a series of vertical mine shafts to various depths, with associated headframes.

The newest shaft is 8 m in diameter and 1,240 m deep. The PEA assumes that the shaft will be recommissioned as the main production shaft, providing the primary access to the lower levels of the mine through the existing 1,150-m level. A series of crosscuts and ventilation infrastructure are still in working condition, and existing underground infrastructure also includes a series of pumps to manage the influx of water into the mine.

Surface infrastructure includes a concentrator, offices, workshops and a connection to the national power grid.

The process flowsheet is based on dense media separation (DMS), with unit operations to include crushing, screening, heavy-liquid separation, and spirals to produce a high-grade zinc concentrate.

An abundant supply of water from underground dewatering operations is expected to provide adequate water for processing and mining operations.

The proposed export route for concentrate will utilize the existing rail network from Kipushi to Ndola, Zambia, connecting to the North-South Rail Corridor from Ndola to Durban, South Africa.