Rio Tinto has upgraded mineral resources at its wholly owned Kennecott Utah Copper Bingham Canyon Mine.
The resource, upgraded to 637 million tonnes at 0.48 percent copper, represents an increase of 628 million tonnes over December 2007 figures.
The resource, located beneath the current Bingham Canyon pit, is currently under study for extraction by open-pit mining methods, says Rio.
Studies at the mine are part of an ongoing technical development programme, which includes new resource drilling and the study of open pit and underground mining options, the company says.
The company says it is continuing with pre-feasibility studies to examine options to develop the resources.
The Kennecott Utah Copper mine is the second largest copper producer in the US and meets about 13 percent the country's copper requirements.
By Ozge Ibrahim
