Orvana Minerals‘ subsidiary Orvana Resources US has completed the prefeasibility study for its Copperwood copper project in Michigan, US.

The cost of pre-production capital is estimated at $198.5m, with working and sustaining capital costs of $212.5m, the study revealed.

The operating cost of the mine will be $13.51 per short ton ore with processing cost of $12.21 per short ton ore.

The study contemplates a 14-year underground operation that applies both conventional drill-and-blast and mechanised methods to room-and-pillar mining and develops a detailed mine plan for each.

The average production for the drill-and-blast case over the 14-year mine life will be about 24,000 short tons of copper per year and peak production is expected to reach 38,000 short tons of copper during the fourth year when throughput is at the 7,500 short tons of ore per day capacity.

KD Engineering will oversee improvement of the project’s economics such as recoveries, refinement of the design, reduction of costs at the tailings facility, and study of the application of a continuous miner.