* Unusual winter storm hit top copper mines for a week
* Escondida, Collahuasi normalizing as weather improves
* Chile disruptions may further constrain copper supply
SANTIAGO, July 9 (Reuters) - Some of the world’s top copper mines started to return to normal on Saturday after a once in half a century winter storm dissipated over Chile’s copper-rich north, companies’ officials and union leaders said.
A week of heavy rains and sporadic snow hit mining operations in a region that produces about a fifth of the world’s mined copper, helping lift global copper prices to three-month highs and en route to another historical record.
The wet weather affected thousands of residents in the world’s driest desert, Chile’s Atacama, which experiences a winter storm of such intensity only once every half a century, authorities and weather forecasters said.
The weather is expected to improve during the weekend after the cold snap passed the region and moved to neighboring Argentina, a forecaster with the nation’s meteorological center said.
More than half a dozen mines had to halt operations or slow mining during the week after rains and snow made the dirt roads at their open pit operations dangerously slippery.
Another unusual cold front at the start of the year hit the first-quarter copper output results of global mining giants Xstrata XTA.L and Anglo American (AAL.L).
Graphic on top Chile mines tinyurl.com/3juxctk
The world’s biggest copper mine, BHP Billiton’s Escondida, was inspecting operations and slowly restarting extraction after it halted mining for two days, said union leader Luis Valdes. BHP (BHP.AX) (BLT.L) has declined to comment on conditions at its operation.
“In my 22 years working at Escondida I haven’t seen a storm of this magnitude and for operations to remain down for such a long time,” Zeiso Mercado, a mine machinery operator, told Reuters by telephone from the mine site. Mercado, a former Escondida union president, said the rains had also forced the shutdown of mineral processing plants.
Collahuasi, the world’s No. 3 copper mine jointly owned by Xstrata and Anglo American, is gradually normalizing operations as the weather improves, said a mine operator spokeswoman. Heavy snow earlier this week hit operations at the mine with its main worker union saying daily output fell as much as 70 percent.
Codelco’s 375,000 tonnes-per-year Radomiro Tomic mine had to shutdown extraction operations for about seven hours on Friday due to safety concerns after heavy rains, a company official said. The mine returned to normal earlier on Saturday.
Local news outlets reported that the nearby giant Chuquicamata mine complex, also owned by the state-run Codelco [CODEL.UL], had to close its copper refinery due to technical problems after heavy rains. A Codelco official at the mine was not immediately available for comment. (Reporting by Alonso Soto; Editing by Vicki Allen)