The project also includes trial of underground battery electric vehicles to reduce carbon emissions at Kennecott and other operations
Rio Tinto has approved a $108m investment to conduct orebody characterisation studies for underground mining at the Kennecott copper operations in Salt Lake City, Utah in the US.
The announcement follows the company’s $25m investment approved in early 2020, to complete a pre-feasibility study of Kennecott underground operations, and $1.5bn investment approved in late 2019.
The Kennecott copper mine is expected to see potential underground mining, along with open pit operations, for increased copper output.
With declared mineral resources of 20Mt at 3.65% copper and 1.62g/t gold, the mine is said to hold a significant potential for underground development.
Rio Tinto Copper chief executive Bold Baatar said: “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.
“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.”
The works under the planned feasibility study include collecting important geological, geotechnical and hydrogeological data, and is expected to be completed in 2024.
Data collected during the study will be used to inform Rio Tinto’s assessment of underground development options.
The company intends to extend the existing infrastructure from previous underground projects to access the North Rim Skarn orebody, to enable the development of crosscuts and further drilling.
The project includes nearly 15,000ft (4,500m) of lateral development, 1,000ft (300m) of vertical development and associated support infrastructure.
Also, the project includes the trial of underground battery electric vehicles to reduce carbon emissions at Kennecott and across the company’s operations worldwide.
Sandvik Mining and Rock Solutions are planned to supply a battery electric haul truck and loader to evaluate performance and suitability for future underground mining fleets.