After more than 100 years, Rio Tinto announced Tuesday that the Kennecott Copper Mines will resume underground mining.

The company has approved a $55 million investment in development capital to start underground mining and expand production at its Kennecott copper operation.

Kennecott is one of just two operating copper smelters in the United States. Underground mining will initially focus on an area known as the Lower Commercial Skarn.

“This investment will allow us to quickly bring additional volumes of high-quality copper to the market and build our knowledge and capabilities as we evaluate large-scale underground mining at Kennecott.” said Bold Baatar, chief executive of Rio Tinto Copper, in a statement. “We are progressing a range of options for a significant resource that is yet to be developed at Kennecott, which could extend our supply of copper and other critical materials needed for electric vehicles and renewable power technologies.”

According to projections from Rio Tinto, the Lower Commercial Skarn will deliver a total of around 30kt2 of additional high-quality mined copper through the period to 2027 alongside open-cut operations.

The company expects the first ore from the mine to be produced in early 2023, with full production in the second half of the year. The ore will be processed through the existing facilities at Kennecott.

Rio Tinto is currently testing underground battery electric vehicles at Kennecott, including a battery-electric haul truck and loader supplied by Sandvik Mining and Rock Solutions.

According to Baatar, these battery electric vehicles would help to create a safer work environment, as well as reduce carbon emissions from future underground mining fleets.

“Trialling underground battery electric vehicles is an exciting step in our work to create a safer workplace for our employees, increase the productivity of the mine and reduce emissions from our operations. We look forward to seeing their potential for deployment,” he said.

Operations at Kennecott were previously halted after an earthquake in Magna in 2020 caused a hydrochloric acid leak at the mine’s refinery.

A Feasibility Study to inform decisions on the next phase of underground production is expected to be completed in 2023, and studies are also being progressed to extend open pit mining at Kennecott beyond 2032. Kennecott’s pre-existing underground infrastructure is currently being extended to enable early access to the next underground resource and undertake characterization studies.

Newsletter