Foran Mining has announced the results of a positive prefeasibility study (PFS) of its McIlvenna Bay zinc-copper volcanogenic massive sulphide (VMS) deposit in east-central Saskatchewan, about 85 kilometers (km) by road west of Flin Flon, Manitoba. The study forecasts production of 89.2 million pounds per year (lb/y) of zinc and 27.9 million lb/y of copper in separate flotation concentrates over a mine life of nine years.

Preproduction capital expenditures to develop McIlvenna Bay are estimated at C$261 million. The PFS is based on a probable mineral reserve of 11.34 million metric tons (mt) grading 4.01% zinc, 1.14% copper, 0.54 grams/mt gold, and 20.97 g/mt silver. The probable mineral reserve is contained within indicated resources of 22.95 million mt grading 3.05% zinc, 1.17% copper, 0.44 g/mt gold, and 16.68 g/mt silver.

Cash costs of production at McIlvenna Bay, including sustaining capital, smelting and refining charges, royalties, and product transportation are estimated at $0.41/lb of zinc or $0.44/lb of copper, net of byproduct credits.

“We assembled a project team that has deep experience with projects similar to McIlvenna Bay to prepare this prefeasibility study,” Foran President and CEO Patrick Soares said. “We are proposing a modern underground mine supported by surface infrastructure designed to take into account feedback we have received from local communities. We are committed to taking the project through feasibility and into production in a safe, responsible manner that will provide economic benefits to the region for years to come.

“We are now in a position to advance discussions with potential investors with experience developing similar mines as we explore the best way to credibly and safely build and operate McIlvenna Bay. Our goal, as always, is to maximize value per share.”

Underground mining at McIlvenna Bay will employ a combination of longitudinal long-hole retreat (Avoca) and sub-level transverse stoping methods to mine at a nominal rate of 3,600 mt/d.

The operation will use 50-mt, battery-electric trucks to bring ore to the surface along the ramp for the first three years of production, followed by the installation of vertical conveyor technology to move ore to the surface from deeper parts of the mine.

The McIlvenna Bay processing plant is based on a conventional mineral processing circuit, with crushing, ball milling, and sequential selective sulphide flotation to produce clean copper and zinc concentrates. Metallurgical test work yielded robust recoveries of 80% for zinc, 88.2% for copper, 79.1% for gold, and 58.0% for silver.

Plant tailings will be de-sulphurized, filtered, and either used for cemented backfill or deposited on a dry stack tailings facility.

On-site infrastructure will include offices, workshops, mine dry, water treatment facilities, fuel storage areas, and a paste plant. An overhead powerline will supply hydropower to the project from Pelican Narrows, 65 km north of the project site.