The Bunker Hill silver-lead-zinc mine in Idaho has a projected net present value of US$143 million upon restart, according to the company's preliminary economic assessment.

The updated PEA also predicts a 35% investor rate of return with a 2.6-year payback.

Bunker Hill said it will decide whether to start construction at the end of the first quarter in 2022.

The Toronto-based company is in negotiations for project finance, and is working on optimising the mine design.

Bunker Hill is conducting metallurgical test work to finalise process flow and confirm recoveries, with resulted in the first quarter of 2022.

Negotiations are also underway with commercial partners to acquire a process plant, which Bunker Hill expects will conclude by the end of the year. Bunker Hill is also in talks with contractors to support the process plant construction, once a plant is acquired.

Engineering of the in-mine water treatment system will be 60% complete by the end of the month, Bunker Hill said. The system will be in compliance with Idaho Pollutant Discharge Elimination System standards.