Rio Tinto (NYSE: RIO; LSE: RIO; ASX: RIO) has approved a US$108 million underground development at the Kennecott copper project in Utah. The expenditure will support a feasibility study for underground mining.
The study will assess underground development options for the Bingham Canyon mine and is expected to be completed in 2024. Existing workings from previous underground projects will be extended to access the North Rim Skarn orebody, allowing for cross-cuts and additional drilling.
The underground project includes approximately 4,500 metre of lateral development and 1,000 metres of vertical development.
The study will also present the results of trials of battery electric mining vehicles at Kennecott and across Rio Tinto's global operations. Sandvik will supply a battery electric haul truck and loader for the trial.
The company approved US$25 million for a prefeasibility study last year on the opportunity to extend Bingham Canyon open pit mining beyond 2032 with a further push-back of the North Wall. This follows the US$1.5 billion investment in the second phase of the South Wall push-back, approved in 2019, to allow open pit mining between 2026 and 2032.
The underground North Rim Skarn contains an estimated 1 million measured tonnes at 3.5% copper, 9 million indicated tonnes at 3.6% copper, and 10 million inferred tonnes at 3.7% copper. The remaining pit resource is 1 million measured tonnes at 0.46% copper, 142 million indicated tonnes at 0.33% copper, and 15 million inferred tonnes at 3.7% copper.
Rio Tinto has copper mines in Chile and Mongolia as well as the United States.