Canadian Mining Journal


COPPER: Excelsior updates PFS for Gunnison in situ project

ARIZONA – Vancouver-based Excelsior Mining Corp. has updated the prefeasibility study for the North Star copper deposit at its Gunnison project in Cochise County. The PFS was updated to reflect the company’s recent acquisition of the Johnson Camp mine and facilities and a savings in the needed initial capex requirement.

Excelsior plans in situ solution mining followed by copper recovery in a solvent extraction/electrowinning plant. Production will start at 25 million lb/y of copper in the existing Johnson Camp facilities and will be raised in stages to 125 million lb/y by the end of a 27-year mine life.

Using a copper price of $2.75 per lb, (all US dollars) the North Star deposit has an after tax net present value of US$829 million at a 7.5% discount and a post-tax internal rate of return of 45.8%. The all-in cost (all capital plus operating) would be $1.24 per lb. Start-up capital is expected to be about $45.9 million, and that amount would be repaid over 2.6 years.

Commenting on the results, Excelsior president and CEO, Stephen Twyerould said, “Even at today’s copper prices of $2.00 per lb, the Gunnison copper project would still return a post-tax IRR of over 26%.”

Additional details from the Gunnison PFS are available in the Feb. 9, 2016, news release posted at

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