Rio Tinto's investment at its Kennecott operation in Utah will begin in 2020 and extend strip waste rock mining and provide infrastructure to allow mining into a new area of the ore body, which is forecast to deliver nearly 1mn tonnes of refined copper from 2026 to 2032.
"This is an attractive, high value and low risk investment that will ensure Kennecott produces copper and other critical materials to at least 2032," Rio Tinto chief executive J-S Jacques said.
Early in 2019, Rio Tinto also announced that it would cut the carbon footprint at Kennecott with the closing of its coal-fired power plant.
Rio Tinto has invested over $5bn since it acquired Kennecott in 1989. Rio Tinto will finish the first phase of a $1.2bn project in 2021 that extended production from 2019 to 2026.
Kennecott also produces gold, silver, platinum and molybdenum, and is a potential source of rhenium and tellurium.
By Mike Hlafka