Revised resource and preliminary reserve estimates for the Chapada copper-gold project in Goias state, Brazil, will provide a basis for a new feasibility study planned by Yamana Gold (YRI-T).
The revised calculations, made by Tucson-based firm International Mining Consultants (IMC), place the resource at 421 million tonnes grading 0.31% copper and 0.23 gram gold per tonne, in measured and indicated categories. There is a further inferred resource of 68 million tonnes at 0.2% copper and 0.14 gram gold per tonne.
A pre-feasibility estimate, based on a gold price of US$325 per oz. and a copper price of US85 per lb. (US$1,870 per tonne), puts the reserve at 263 million tonnes at 0.36% copper and 0.27 gram gold per tonne. An additional 47 million tonnes of stockpiled material, grading 0.3% copper and 0.22 gram gold, is classified as a probable reserve.
Chapada, a flat-lying tabular deposit, would be mined by open pit; as designed by IMC, the pit would have a very low stripping ratio of 0.65:1. A starter pit, with a five-year life, would have grades of 0.46% copper and 0.43 gram gold per tonne.
Yamana plans to update the 1998 feasibility study to provide definitive capital and operating cost figures. The study, to start this month, is scheduled to be done by the middle of the year.
Yamana acquired Chapada, an 84-sq.-km property about 250 km northwest of Brasilia, in a deal with Brazilian-based Minerazao Santa Elina in August 2003. Santa Elina had previously been advancing the project in a joint venture with Echo Bay Mines (now part of Kinross Gold [K-T]), which came to a feasibility study in 1998. That study based production of 12.7 million tonnes annually from a reserve of 187 million tonnes grading 0.39% copper and 0.31 gram gold per tonne.