Mining giant Rio Tinto (NYSE: RIO; LSE: RIO; ASX: RIO) says it's investing US$55 million to start underground mining and expand production at its Kennecott copper operations, the world's largest open pit mine, near Salt Lake City, Utah.
The move will add 30,000 tonnes of copper production from early 2023 to 2027, alongside the site's open pit operations, the company said in a news release. The open pit produced 159,400 tonnes of copper last year.
The new underground ore will come from the mine's Lower Commercial Skarn, which has a measured resource of 200,000 tonnes at 2.52% copper, 1.27 grams gold per tonne, 10.56 grams silver per tonne and 0.056% molybdenum, Rio Tinto said.
Rio Tinto Copper chief executive officer Bold Baatar said the investment would help the miner build knowledge and capabilities as it evaluates larger scale underground mining at Kennecott.
“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,” the CEO said in the news release.