Infill drilling is proving up the open-pit mining potential of the Tabakoto gold deposit in Mali.
Since April,
Gold values varied from 1.14 to 156.6 grams per tonne over core lengths of 0.85-36 metres. The longest interval averaged 4.83 grams and included higher-grading sub-intervals, as did several other long intervals in other holes.
Fourteen holes failed to return any significant results. However, those holes were drilled in the peripheral areas of the proposed pit.
Holes 412-435 targeted the primary, northeast-trending structure over a strike length of 325 metres. The results demonstrate the necessity of additional drilling and, accordingly, more holes are being sunk there.
Infill diamond drilling continues as well.
Recent metallurgical tests have proved encouraging: gravity alone liberated 80-82% of the gold from four composite samples, with cyanidation extracting 87-97% from the tailings. Previous tests gave an overall recovery rate of 92%.
In 2000, Snowden Consultants of Australia pegged Tabakoto with near-surface resources of 1 million tonnes averaging 6.7 grams gold. Another 1.2 million tonnes averaging 8.7 grams were defined as potentially amenable to underground mining. Both estimates are based on a cutoff grade of 6 grams per tonne.
The consultant envisions an 8-year operation, starting with an open pit in the first three years and then moving underground. About 250,000 tonnes would be mined in each year, to yield 68,000 oz.
Life-of-mine capital costs total US$39 million. At a gold price of US$300 per oz., this translates into an internal rate of return of 18%.
Life-of-mine operating costs are projected at US$161 per oz., or US$261 when capital costs and royalties are included.
Nevsun plans to update the resource estimate once the infill program is complete. A feasibility study will follow.
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