Rio Tinto has approved a $108 million investment in underground development to enable early orebody access and undertake orebody characterisation studies for underground mining at the Kennecott copper operations in Utah.
The investment builds on $25 million approved in early-2020 to complete a prefeasibility study to determine the viability of underground mining operations at Kennecott.
Potential underground mining would occur concurrently with open-pit operations, according to the company.
“Kennecott holds the potential for a significant and attractive underground development, with declared Mineral Resources of 20 Mt at 3.65% copper and 1.62 g/t gold with further upside potential based on drilling,” Rio Tinto said in a release.
The feasibility study work will focus on gathering critical geological, geotechnical and hydrogeological data to inform Rio Tinto’s assessment of underground development options and is expected to be completed in 2024.
Existing infrastructure from previous underground projects will be extended to access the North Rim Skarn orebody, allowing for the development of crosscuts and further drilling of the resource.
The project includes approximately 15,000 feet (4,500 metres) of lateral development, 1,000 feet (300 metres) of vertical development and associated support infrastructure.
The project will also include the trial of underground battery electric vehicles to reduce carbon emissions at Kennecott.
According to Rio Tinto, pre-feasibility studies are also being progressed to extend open pit mining at Kennecott beyond 2032.
“Kennecott holds a range of options to extend our supply of copper and other critical materials, to meet the strong demand being driven by electric vehicles and renewable power technologies,” said Rio Tinto Copper chief executive Bold Baatar.
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“The operation is uniquely positioned to supply these emerging markets, with one of only two operating smelters in the United States that also processes concentrates from third parties, a long history delivering high-quality products and significant resources that are yet to be developed.”
Rio Tinto bought Kennecott in 1989 and has invested more than $2 billion in modernizing the mine and another $450 million to clean up historic workings and groundwater.
Bingham Canyon, 30 miles south of Salt Lake City, has been mined since 1906. The mine has produced more copper than any mine in history – more than 19 million tonnes.