Rio Tinto has approved a $55 million investment in development capital to start underground mining and expand production at its Kennecott copper mine.

Rio Tinto to start underground mining at Kennecott Copper Mine

Rio Tinto — Rio Tinto has approved a $55 million investment in development capital to start underground mining and expand production at its Kennecott copper operations in Utah. 

Underground mining will initially focus on an area known as the Lower Commercial Skarn (LCS), which will deliver a total of around 30kt2 of additional high-quality mined copper through the period to 2027 alongside open-cut operations. The first ore is expected to be produced in early 2023, with full production in the second half of the year. It will be processed through the existing facilities at Kennecott, one of only two operating copper smelters in the United States. 

Kennecott holds the potential for significant and attractive underground development. The LCS is the first step toward this, with a Mineral Resource of 7.5 Mt at 1.9 percent copper, 0.84 g/t gold, 11.26 g/t silver, and  0.015 percent molybdenum identified based on drilling and a Probable Ore Reserve of 1.7 Mt at 1.9 percent copper, 0.71  g/t gold, 10.07 g/t silver, and 0.044 percent molybdenum3

Underground battery electric vehicles are currently being trialed at Kennecott to improve employee health and safety, increase productivity and reduce carbon emissions from future underground mining fleets. A  battery electric haul truck and loader supplied by Sandvik Mining and Rock Solutions are being used to evaluate performance and suitability as part of underground development work. 

Rio Tinto Copper chief executive Bold Baatar says, “This investment will allow us to quickly bring additional volumes of high-quality copper to the market and build our knowledge and capabilities as we evaluate 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.”  

“Trialling underground battery electric vehicles is an exciting step in our work to create a safer workplace for our employees, increase the productivity of the mine and reduce emissions from our operations. We look  forward to seeing their potential for deployment.” 

Existing undergound infrastructure is currently being extended to enable early access to the next underground resource and undertake characterization studies. A Feasibility Study to inform decisions on the next phase of underground production is expected to be completed in 2023. This will be one of several potential stages currently being investigated. 

Feasibility studies are also being progressed to extend open pit mining at Kennecott beyond 2032.  

The Table 1 Release was made in accordance with the JORC Code and the ASX Listing Rules. Mineral  Resources are reported in addition to Ore Reserves. Mineral Resources and Ore Reserves are quoted on a  100 percent basis.