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Ivanhoe restores access to underground working level at Kipushi

18th December 2013

By: Henry Lazenby

Creamer Media Deputy Editor: North America

  

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TORONTO (miningweekly.com) – Africa-focused project developer Ivanhoe Mines’ ongoing dewatering programme at the Kipushi copper/zinc/germanium/lead/precious-metals mine, in the Democratic Republic of Congo (DRC), had achieved its critical first objective of restoring access to the main underground working level before the end of this year.

The water level, which reached 851 m below surface at its peak, had now been reduced to the mine's main working level at 1 150 m below the surface. This progress allowed the company to start its planned 20 000 m underground diamond-drilling programme early in 2014.

The programme was designed to confirm the mine's estimated, remaining high-grade resources – which were included in the September 2012 Kipushi technical report prepared by IMC Group Consulting – and to seek to further expand the resources on strike and at depth.

"Steelwork and equipment are being progressively replaced and upgraded as the water level drops, providing access for drilling and advancing us to a very significant milestone in the redevelopment of the Kipushi mine.

"Now we are in a position to begin our aggressive drilling programme, which we believe will confirm and expand the mine's historical resources and set the stage for Kipushi to return to production as one of the world's highest-grade mines,” CEO Lars-Eric Johansson said on Wednesday.

TSX-listed Ivanhoe expected to complete dewatering to the bottom of the mine's lowest level, at 1 270 m below the surface, during the first quarter of 2014. Ivanhoe's planned 2014 drilling programme was scheduled to complete about 100 holes totaling more than 20 000 m.

Among the programme's objectives was to conduct confirmatory drilling to validate the historical resources within Kipushi's Big Zinc and Fault zones and qualify them as current resources conforming with standards established by the Canadian Institute of Mining, Metallurgy and Petroleum (CIM).

Previous mining at Kipushi was conducted to a below-surface depth of 1 207 m on the Kipushi Fault Zone, a deposit of high-grade, copper/zinc/lead mineralisation that had a strike length of 600 m.

The Fault Zone was known to extend to at least 1 800 m below the surface, based on drilling reports by State-owned mining company Gécamines (La Générale des Carrières et des Mines). Ivanhoe's planned 2014 drilling programme was also designed to conduct extension drilling to test and upgrade the deeper portions of the Big Zinc and Fault zones, below the 1 500 m level, that were previously classified as inferred resources.
The programme would also include exploration drilling to test areas that have not been previously evaluated, such as the deeper portions of the Fault Zone and extensions to the high-grade copper mineralisation of the mine's Northern deposit, and aim to obtain large-diameter drill core from the Big Zinc for confirmatory metallurgy test work

From its start-up in 1924 as the Prince Léopold mine, Kipushi produced a total of 6.6-million tonnes of zinc and four-million tonnes of copper from 60-million tonnes of ore grading 11% zinc and about 7% copper, until 1993.

Between 1956 and 1978 the mine also produced 278 t of germanium, a high-tech metal used in light-emitting diodes, fibre-optic networks, infrared night vision systems and solar cell applications; it was currently garnering a spot price of about $1 850/kg.

Kipushi also contains the Big Zinc, a bonanza-grade zinc deposit discovered at about 1 200 m below the surface in the early 1990s, shortly before the mine's closure. The Big Zinc, which remains unmined and open to depth, would be accessible from existing underground workings.

Based on drilling reports by Gécamines multiple steeply dipping exploratory holes have intersected exceptionally high-grade zinc mineralisation, grading 42% to 45% zinc, between the 1 375-m-level and 1 600-m-level elevations, with more than 60 m to 100 m of apparent thickness.

South Africa's national mineral research organisation Mintek recently completed a preliminary metallurgical test campaign on existing drill core from the Big Zinc, and comminution tests indicated that the material was soft and, therefore, easy to crush and mill. Flotation tests indicated that the material was easily upgradable to a very high-grade concentrate composition at high zinc recoveries.

Kipushi currently has a historic measured and indicated resource - stated only to the 1 500 m level - of 16.92-million tonnes grading 2.32% copper and 16.76% zinc.

Ivanhoe Mines, formerly known as Ivanplats, also owns the high-grade Kamoa copper deposit in the DRC, as well as the Platreef polymetals project, in South Africa.

Edited by Creamer Media Reporter

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