Japan’s Sojitz is set to divest its 12.5% stake in Gibraltar Mine in south-central British Columbia, Canada, to majority owner and operator Taseko Mines, reported Mining.com.

Taseko currently owns a 75% stake in the Gibraltar copper-molybdenum mine, which is claimed to be the country’s second-largest open-pit copper mine.

The mine has an average annual production of 135Mlb of copper and 2.5Mlb of molybdenum (100% basis). It is expected to have operational life until 2038.

This divestment by the trading house comes due to unstable operations, rising risks of environmental liabilities, and deteriorating grades.

The deal is expected to close by the end of next month.

Japanese firms Furukawa and Dowa Holdings each hold a 6.25% interest in the Gibraltar mine.

Last December, production from the mine was impacted by unplanned mill downtime, including a power outage late in the month.

Last month, Taseko president and CEO Stuart McDonald said: “Mill throughput in October and November averaged above design capacity, but production in December was impacted by unplanned mill downtime, including a sitewide power outage late in the month.

“Mining operations have advanced deeper into the Gibraltar pit and were largely unaffected by this recent severe winter weather and power outage.”

Separately, Taseko plans to start construction on its Florence Copper Project in Arizona this year. The project is expected to nearly double the firm’s annual copper production capacity.

Taseko also owns advanced staged projects, including Yellowhead Copper Project, New Prosperity Gold-Copper Project and Aley Niobium Project.