After declaring a 730,000 tonne increase of contained copper in mineral resources at Kennecott Utah Copper, Rio Tinto (NYSE:RIO) expects to head underground.
Rio Tinto says that the mineral resource, known as the North Rim Skarn, is a high-grade copper-gold skarn deposit located approximately 300 metres below the current Bingham Canyon pit, the world's deepest open pit mine.
The company has committed US$165 million to complete the next stage of exploration and development studies by 2014. This pre-feasibility programme includes final shaft rehabilitation, an access decline from the pit and further underground exploration drilling. This investment follows the approval for US$238 million to advance studies extending the open pit life to 2028 and the purchase associated long-lead time equipment.
Rio Tinto has increased its copper mineral resources by 20 million tonnes to 106 million tonnes at its wholly-owned Kennecott Utah Copper Bingham Canyon Mine. The North Rim Skarn increases contained metal in mineral resources by 0.73 million tonnes copper, 1.0 million ounces gold and 13 million ounces silver over the 2010 year-end mineral resource estimate.
Image from Rio Tinto showing Bingham Canyon ore reserve and mineral resource pit