Rio Tinto approved a $108 million investment in underground development to enable early orebody access and undertake orebody characterization studies for underground mining at the Kennecott copper operations in Utah.
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. Potential underground mining would occur concurrently with open pit operations and result in increased copper output.
Kennecott holds the potential for a significant and attractive underground development, with mineral resources of 20 million metric tons (mt) at 3.65% copper and 1.62 g/mt gold with further upside potential based on drilling.
The feasibility study work will focus on gathering critical geological, geotechnical and hydrogeological data 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 4,500 meters (m) of lateral development, 300 m of vertical development and associated support infrastructure.
The project will also include the trial of underground battery electric vehicles to reduce carbon emissions at Kennecott and across Rio Tinto’s global operations. Sandvik Mining and Rock Solutions will supply a battery electric haul truck and loader to evaluate performance and suitability for future underground mining fleets.
Prefeasibility 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. 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.