The final batch of 30 infill drill holes on the Salave gold project in northern Spain has returned the best ever grade-thickness for owner Rio Narcea Gold Mines (RNG-T).
Hole 70, the final hole in a 14,900-metre program, cut several mineralized intervals including 18.2 metres (beginning at a downhole depth of 252.2 metres) grading 29.3 grams gold per tonne, and 21.7 metres (from 281 metres) of 37.7 grams gold. The hole also returned 33.3 metres of 8.7 grams gold and 37.1 metres of 15.7 gram higher in the hole.
The vertical hole was offset some 25 metres from existing holes on the property, and returned a total grade-thickness of 1,798 g/t-m over an estimated true thickness of 34 metres. A hole previously sunk some 20 metres to the north yielded a grade thickness of around 1,000 g/t-m.
Highlights from the remaining holes are as follows:
Hole no. 53 stood out from the rest by failing to return at least one intercept exceeding 1 gram gold per tonne.
With the infill drilling wrapped up, Rio Narcea continues work to support a bankable feasibility study, expected later this year; permitting and preliminary applications are also being completed. The company expects to submit its final site restoration plans during the second quarter. The Salave deposit is an intrusive-related, disseminated deposit hosted in granodiorite below a shallow-dipping, altered but unmineralized roof pendant of quartzites and siltstones. The mineralization is refractory, with the sulphides mainly consisting of pyrite, arsenopyrite and minor molybdenite, plus lesser amounts of sphalerite, stibnite and chalcopyrite.
Late last year, Roscoe Postle Associates pegged Salave’s measured resource at 354,000 tonnes averaging 2.7 grams gold per tonne, while the indicated resource was estimated to be 14.8 million tonnes grading 3 grams gold, and the inferred figure stands at 2.8 million tonnes grading 2.5 grams gold. All the estimates employ a cutoff grade of 1 gram gold per tonne (T.N.M., Nov. 19-25/04).
Meanwhile to the south, about 90 km north of Seville, Rio has arranged the first sale of 20,000 tonnes of concentrate (grading 4.7% nickel and 5.7% copper) produced during ongoing commissioning of its Aguablanca nickel-copper mine. The sale is expected to generate $7 million in revenue under an existing long-term, off-take agreement with Switzerland’s Glencore International. The contract will see Glencore buy all of Aguablanca’s nickel concentrate produced until 2010.
Continuing commissioning efforts are focused on improving mill throughput, and bringing nickel concentrate grades and recoveries up to design standards. In June, a replacement discharge grate and lifters will be installed with the aim of reducing over-grinding to further improve the semi-autogenous grinding mill’s performance.
Engineering and construction contractor Fluor needs to get the processing plant up to at least 90% of design capacity before it can turn it over to Rio Narcea. The feasibility study at Aguablanca calls for throughput of 125,000 tonnes per month, recoveries of 82% nickel and 85% copper, and concentrate grades of 8-9% nickel and 4-5% copper. In April, mill throughput averaged 108,822 tonnes; recoveries averaged 60% and 87% for nickel and copper, and concentrate grades averaged 6% nickel and 7.9% copper.
Aguablanca has open-pit reserves of 15.7 million tonnes grading 0.7% nickel, 0.5% copper, and 0.5 gram PGEs per tonne, based on a cutoff grade of 0.25% nickel. Based on limited drilling, Rio figures underground mining could produce an additional 200,000-300,000 tonnes of ore as soon as 2006.
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