MICHIGAN – Toronto-based Orvana Minerals has received the completed feasibility study for its Copperwood copper-silver project on the Upper Peninsula. The study outlines a 13-year underground operation using room-and-pillar mining.
Copperwood is a stratiform copper deposit hosted by the shales and siltstones of the lowermost Nonesuch Formation along the shallow-dipping southern limb of the Western Syncline. Copper occurs as very fine-grained chalcocite. Orvana has options to lease mineral rights on the other stratiform copper deposits within the Western Syncline.
The plan calls for the development of a ramp and box cut to access the deposit. All development will be focused on the orebody and virtually no waste rock will be handled. The 6,800-t/d mill will use conventional flotation. Life-of-mine direct operating cash costs are $1.26/lb of copper net of the silver credit.
The company reports that the fully-diluted mineable reserves are 21.0 million tonnes of 1.46% Cu and 3.98 g/t Ag proven and 6.4 million tonnes of 1.21% Cu and 2.44 g/t Ag probable, for a total of 27.4 million tonnes of 1.41% Cu (852 million lb) and 3.63 g/t Au.
A summary of the feasibility study will be posted shortly at Orvana.com.