Jan. 17 (Bloomberg) –Rio Tinto Plc (RIO)'s mined copper production in the fourth quarter fell 31 percent at Kennecott Utah Copper from a year earlier, 14 percent at Escondida and 75 percent at Grasberg. The following comments were in the company's statement on fourth quarter operations.

Kennecott Utah Copper:
"Copper contained in concentrates was higher than the prior two quarters but was lower than the fourth quarter of 2010 due to variability in ore grades. Higher ore grades are expected in the second half of 2012 and into 2013. A 26 day maintenance shutdown at the smelter is planned for the second quarter of 2012 to take advantage of the mining of lower grade areas of the pit."

Escondida:
"Fourth quarter mined copper production rebounded from the third quarter which was impacted by a work stoppage, halting operations for 15 days. Lower ore grades and the work stoppage impacted full year production."

Grasberg:
"Rio Tinto's share of production in 2011 was impacted by industrial action and damage to concentrate and fuel pipelines in the second half of the year."