Reuters reported that the world's biggest copper mine in Chile is shutting a key milling operation for 45 days for repairs after equipment problems contributed to a 38% decline in mine production of 2008 for 57.5% owner BHP Billiton.

BHP Billiton said that the shutdown in the current quarter would replace coils on one of two semi autonomous grinding mills required to crush ore. The company said that "We expect a more reliable mill operation after this maintenance."

Rio Tinto last week said that its share of mined copper from its 30% stake in Escondida fell 41% to 76,200 tonnes in the last quarter.

A company spokesman said that an update on the impact of the shutdown over the current quarter will not be disclosed until the company's next quarterly production report after September 30th.

Mr James Wilson analyst of DJ Carmichael & Company mining said that "They have had issues with that mill for a while and now seem to be saying, we are going to fix this once and for all."

BHP Billiton reported an overall 12% decline in copper production to 1.207 million tonnes in 2008/09, with lower ore grades at some mines also contributing to the decline.

It said that partially offsetting the drop was rising output from leaching operations to make cathodes at Escondida and at the Spence mine, also in Chile and better performance from the Olympic Dam smelter in Australia.

(Sourced from Reuters)