TORONTO (miningweekly.com) – The first six holes drilled by Africa-focused project developer Ivanhoe Mines confirm an expanded, thick, flat-lying, bottom-loaded zone of high-grade copper mineralisation at the southern part of the Kakula discovery of the Kamoa copper project, in the Democratic Republic of Congo.
Ivanhoe’s TSX-listed stock gained more than 7% on Monday on the back of the positive exploration news.
Ivanhoe reported that initial assay results confirmed the exceptional grades and widths of mineralisation from the expanded drilling programme on the Kamoa project – a joint venture between Ivanhoe and Zijin Mining.
Among the highlights of the first six assayed drill holes were copper intercepts that included 8.86 m (true width) grading 6.56% copper and 10.23 m (true width) of 6.18% copper, at a 2.5% copper cutoff. By comparison, the average grade of copper ores in the twenty-first century was considered to be below 0.6% copper, with the proportion of economic ore minerals (including copper) being less than 2% of the total volume of the ore rock.
Ivanhoe pointed out that the results so far had the potential to have a significant, positive impact on the Kamoa project’s future development plans.
“These initial results are consistent with our earlier drill intercepts in this remarkable discovery made by the Ivanhoe Mines geological team and confirm the consistent, high-grade nature of the Kakula copper mineralisation,” executive chairperson Robert Friedland stated.
He noted that the bottom-loaded nature of the nearly flat-lying, stratabound chalcocite and bornite mineralisation at Kakula offered the potential for selective, mechanised underground mining at significantly higher copper grades than other large-scale mining projects.
MORE EXPLORATION UPSIDE
Ivanhoe advised that the drilling programme at Kakula was now fully mobilised with seven rigs operational in the field and two rigs on standby. The planned 25 000 m of drilling were scheduled to be completed in the third quarter.
Ivanhoe was awaiting assay results on 14 drill holes in addition to the six holes for which assay results had been reported.
Of particular significance was hole DD1011 – a 400 m step-out hole south from DD996, which intercepted 9.96 m (true width) of 6.61% copper in 2015, at a 2.5% copper cutoff. Ivanhoe noted that hole DD1011 was highly significant as it confirmed the flat-lying, thick, high-grade Kakula mineralised zone encountered in the drill holes reported to date extended at least 400 m further to the south. The high-grade zone remained open to the south and drilling would continue to test the extent of the mineralised zone in this direction, the company said.
The 60 km2 Kakula exploration area is about 10 km south-west of the Kamoa project’s planned initial mining area at Kansoko Sud. The Kamoa project had previously been independently ranked as the world’s largest undeveloped, high-grade copper discovery by international mining consultants Wood Mackenzie.
Meanwhile, the twin declines for access at Kansoko Sud were progressing ahead of schedule, Ivanhoe advised.
Each decline had advanced more than 30 m since the first excavation blast occurred on May 12. Mine development was designed to reach the high-grade copper ore during the first quarter of 2017.
The Kansoko Sud initial mining footprint contained high-grade intercepts of up to 7.04% copper and a potential mining thickness of more than 15 m. The mineralised horizon was expected to be intersected by the declines at about 150 m vertically below surface, where initial mining operations will start.
An independent prefeasibility study (PFS) on the first phase of development envisaged the construction of an underground mine, a concentrator processing facility and associated infrastructure.
The PFS proposed mine production of three-million tonnes a year at an average grade of 3.86% copper over a 24-year mine life, resulting in production of 100 000 t/y of copper.
The first phase of mining will target high-grade copper mineralisation from shallow underground resources to yield a high-value concentrate.
The planned second phase will entail a major expansion of the mine and mill, as well as the construction of a smelter to produce blister copper.