The Kipushi Project, also in the DRC's province of Katanga and southeast of the company's Kamoa discovery, is adjacent to the town of Kipushi and approximately 30 kilometres southwest of the provincial capital of Lubumbashi. Ivanhoe Mines acquired its 68% interest in the Kipushi Project in November 2011; the balance of 32% is held by the DRC's state-owned mining company, Gécamines.
The Kipushi Project is based on the high-grade, underground zinc-copper mine in the Central African Copperbelt, which mined approximately 60 million tonnes grading 11% zinc and 7% copper between 1924 and 1993. In addition to producing copper and zinc, the mine produced 12,673 tonnes of lead and approximately 278 tonnes of germanium between 1956 and 1978. The mine has been managed on a care and maintenance basis since 1993.
Gécamines discovered the Big Zinc Deposit before 1993 and the deposit remains unmined. Historical estimates of the Big Zinc's resources between the mine's 1,295- and 1,500-metre levels total 4.7 million tonnes averaging 39% zinc and 0.76% copper. Several exploration holes confirmed the continuation of the Big Zinc Deposit below the 1,640-metre level. Kipushi's historical resource estimates above the 1,500-metre level total approximately 17 million tonnes averaging 16.7% zinc and 2.3% copper, including the Big Zinc historical resources.
A Qualified Person has not done sufficient work to classify the historical estimates as current Mineral Resources and Ivanhoe Mines is not treating such estimates as current Mineral Resources. The historical resources noted above are derived from an estimate prepared by Techpro Mining and Metallurgy in 1997 and are presented at an indicated level. A discussion of the material assumptions, parameters and methods relating to the historical resource estimate, as well as a discussion of relevance, reliability and other information regarding the estimate, is included in the Kipushi Technical Report dated September 2012 prepared by IMC Group Consulting Ltd. and available at www.sedar.com
Click here to view the Kipushi Technical Report
Schematic of Kipushi cross-section showing mine infrastructure and the Big Zinc and Kipushi Fault Zones.
Project development and infrastructure
Work began in early March 2014 on the planned underground diamond-drilling program at the Kipushi Project, a major advance made possible by the ongoing dewatering program directed by Ivanhoe during the past three years following its acquisition in November 2011.
The mine, which had been placed on care and maintenance in 1993, flooded in early 2011 due to a lack of pump maintenance over an extended period. Water reached 851 metres below surface at its peak. A major milestone was reached in December 2013 when Ivanhoe restored access to the mine's principal haulage level at 1,150 metres below the surface.
Since then, crews have been upgrading underground and surface infrastructure to support the drilling program. Recent improvements have included the fabrication of an air deflector for ventilation Shaft #4 to reduce noise impact, tie-in of the water piping from shafts P1Ter and P15 to the 1,112-metre-level dam, and the start of the removal of corroded ventilation columns from Shaft #5.
Water levels are stabilized below the 1,150-metre-level haulway and 1,272-metre-level hanging wall drift, enabling access for drilling, with two rigs targeting the Série Récurrente and Big Zinc mineralization.
Exploration and development drilling
As of April 12, 2015, Ivanhoe had drilled 81 holes, totalling approximately 17,860 metres of its planned 20,000-metre underground diamond drilling program. Assays for holes one through 73 now have been released, while assays for holes 74 through 81 are pending.
Ivanhoe's current drilling program is focused on exploring for additional mineralization at depth, below the Big Zinc zone and on the Fault zone. Exploration drilling from both the 1,272-metre level hanging-wall drift and from the footwall ramp has been ongoing with significant success. Ivanhoe now has intersected new sphalerite zones in a total of five holes, including drill hole KPU072 for which assays now have been received. The intercepts suggest a possible pipe-like structure similar in geometry to the Big Zinc body, although this hypothesis is still unproven and it is still uncertain whether the new zone connects to the Big Zinc.
Summary of recent assay results by Ivanhoe Mines at Kipushi reported on April 15, 2015.
Note: Kipushi FZ = Kipushi Fault Zone; NR = Nord Riche, SBZ = Southern Big Zinc (New zone of mineralization to south of Big Zinc of uncertain geometry).
As of April 12, 2015, Ivanhoe had received final assays for the 34 holes drilled into, or through, the Big Zinc zone. Ivanhoe's drilling was designed to allow estimation of the historical Big Zinc indicated resource -- originally established through pre-1993 drilling by Gécamines -- in line with current guidelines set by the Canadian Institute of Mining, Metallurgy and Petroleum (CIM).
Historical Resource Estimate
|Measured & Indicated
|- including Big Zinc zone
Note: A Qualified Person has not done sufficient work to classify these historical estimates as current Mineral Resources and Ivanhoe Mines is not treating such historical estimates as current Mineral Resources. For the material assumptions relating to the Kipushi Project historical resource estimate, please see note 2 in the appendix hereto. Source: Historical resource estimate by Techpro Mining and Metallurgy in 1997.
- Low grade: 1% < copper < 2% and 7% < zinc < 14%.
- Waste: copper < 1% and zinc < 7%.
Big Zinc's grade and tonnage potentially are higher than previously estimated, new review indicates
Ivanhoe recently received the findings of an independent review conducted by MSA Group (Pty.) Ltd., of Johannesburg, based on results of a comprehensive re-sampling program of historical Kipushi core collected from drilling by Gécamines into the Big Zinc Discovery in the early 1990s.
A total of 384 historical quarter-core (NQ-sized) samples were collected and dispatched to Bureau Veritas Minerals Pty. Ltd.'s laboratory in Australia. A total of 457 samples, including quality-control samples, were submitted to Bureau Veritas and analyzed for gold by fire assay, and for multi-elements, including zinc and copper, by sodium peroxide fusion and ICP-AES/MS finish. The re-sampling program was conducted over eight complete drill intersections of the Big Zinc from eight separate section lines and represented 18% of the total samples in the Big Zinc's historical assay database.
MSA's review of the recent re-sampling revealed that the zinc assay results generally report higher -- and averaged 5.5% higher -- than the assay results originally reported by Gécamines. MSA also concluded that density applied by Gécamines for estimating the tonnage in the Big Zinc Discovery was understated by an average of 9%. Despite the low bias, the review confirms that historical assay values reported by Gécamines are reasonable and can be replicated within a reasonable level of error by international, accredited laboratories under strict QA/QC control. This is an important milestone for Ivanhoe as part of its program to establish current resource estimates for its Kipushi Project.