Canada-based Highland Copper has published the results of a preliminary economic assessment (PEA) for the White Pine North copper project, in the US, estimating average life-of-mine (LoM) copper production of 89-million pounds and silver production of 1.3-million ounces.

The study calculates that White Pine North, in Ontonagon county, Michigan, could operate at a cash cost of $1.40/lb, including royalties, over its 25-year mine life.

The PEA considers White Pine North as a standalone project that uses existing infrastructure to minimise capital expenditure (capex). The initial capex is expected to be $457-million.

Using a base case of $3/lb of copper and $16/oz of silver, the PEA calculated an after-tax internal rate of return of 16.8% and an after-tax net present value, using an 8% discount, of $416-million.

The project is the extension of the historical White Pine mine, which operated from 1953 to 1995. Highland is buying the project from Canadian miner First Quantum Minerals subsidiary Copper Range Company (CRC), subject to several conditions, including releasing CRC from certain environmental obligations relating to the historical mine.

Pending the final closing of the acquisition, Highland has started mineral exploration and baseline studies under an agreement with CRC.

The White Pine North project has indicated mineral resources of 133.4-million tonnes at 1.07% copper and 14.9 g/t silver, containing 3.2-billion pounds of copper and 63.8-million ounces of silver. The inferred mineral resources of 97.2-million tonnes at 1.03% copper and 8.7 g/t silver, contain 2.2-billion pounds of copper and 27.2-million ounces of silver.

The mineral resources included in the mine plan of 121.4-million tonnes at 0.98% copper and 11.80 g/t silver, contain 2.6-billion pounds of copper and 46.1-million ounces of silver.

Highland also owns the Copperwood project, a development stage copper project in Michigan fully permitted to move into the construction stage.