July 14 (Bloomberg) -- Rio Tinto Group's share of mined copper from Chile's Escondida, the world's largest producer, rose 6.3 percent as it mined higher copper grades during the second quarter.

Rio, which owns 30 percent of Escondida, was entitled to 81,000 metric tons of mined copper compared with 76,200 tons a year earlier. The London-based company's share of refined copper production dropped to 23,100 tons from 25,700 tons because of "maintenance activities and the continued ramp up to following improvements to safety procedures," Rio said in a statement.

Total output at the mine, located in the Atacama desert and operated by BHP Billiton Ltd., last year stood at 1.103 million tons of copper, according to the Minera Escondida SA website.

BHP, the world's largest mining company, owns 57.5 percent of Escondida, Rio is the second largest stakeholder and a group led by Mitsubishi Corp. owns 10 percent. International Finance Corp. owns the remainder.