By Robb M. Stewart

 

Rio Tinto PLC is pushing ahead with studies that could see underground mining at its Kennecott copper operation in Utah with a $108 million investment that would allow early orebody access and characterization studies.

Underground mining could happen at the same time as open-pit operations at Kennecott, which would increase copper production, the mining company said Thursday.

 

On underground mining plans:

Rio Tinto said it approved the investment in underground development to enable early orebody access and undertake orebody characterisation studies for underground mining at the Kennecott copper operations, near Salt Lake City.

The investment builds on $25 million approved in early-2020 to complete a pre-feasibility study to determine the viability of underground mining operations at Kennecott.

Kennecott has declared mineral resources of 20 Mt at 3.65% copper and 1.62 g/t gold with further upside potential based on drilling, the company said.

"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 of lateral development, 1,000 feet of vertical development and associated support infrastructure," it said.

The U.K.-Australian company said the project will also include the trial of underground battery electric vehicles to reduce carbon emissions at Kennecott.

Pre-feasibility studies are also being progressed to extend open pit mining at Kennecott beyond 2032, with a further push back of the North Wall to allow access to Mineral Resources, it said. This follows a $1.5 billion investment in the second phase of the South Wall Pushback project, approved in 2019, to allow open cut mining to continue between 2026 and 2032.

In March, Rio Tinto said it was investing $2.9 million to set up a new plant that would recover tellurium, a mineral used in solar panels, from copper refining at Kennecott. Tellurium production is expected to begin in the final quarter of the year, and the plant will have the capacity to produce about 20 tons a year, it said.

 

Write to Robb M. Stewart at robb.stewart@wsj.com

 

(END) Dow Jones Newswires

July 22, 2021 10:59 ET (14:59 GMT)

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