Bunker Hill CEO Sam Ash said the company intends to commence "profitable, sustainable, modern operations" by the end of 2023.

"As demonstrated in our PFS, Bunker Hill is a sustainable low-risk, high-margin asset with the potential to generate free cash flow of over $25 million per year while contributing to strategic metal production in the United States beginning in 2024," Ash said.

"We are now focused on driving forward to a formal construction decision while maintaining momentum with ongoing restart activities," he said.

An initial capital expenditure of $55 million is to achieve an expanded 1,800 tonnes per day operation, leveraging mineral endowment of "the largest-scale and shallowest major mine" in Idaho's Silver Valley, and "one of the most prolific mines in US history," the company said.

The mine has been in care and maintenance since 1991.

The PFS views a 2.1 year payback period while the company is presented with a "rapid restart" of 16 months to commercial production, it said.

The phase 1 mine plan is for zinc equivalent production of 475 million pounds at a zinc equivalent grade of 8.5%, including 317 million pounds of zinc, 146 million pounds of lead, and 3 million ounces of silver.

The all-in sustaining cost is expected at $0.77 per payable pound of zinc, net of by-products.

The mine is intended to be a first step for Bunker Hill in its plan in consolidating a portfolio of North American precious-metal assets with a focus on silver.

From initial discovery in 1885, until the mine's closure, production totaled 42.77 million tons at an average grade of 8.43% lead, 3.52 ounces silver per ton and 4.52% zinc, the company said.

Bunker Hill had a share price of C$0.093 (US$0.07) on 6 September, with a market capitalisation of C$20.42 million.