Despite a slowdown in copper prices for most of this year, Asarco plans to boost annual copper production at its Mission mine complex by 16 percent, by expanding its copper concentrator.

The company also recently reopened a molybdenum production plant at Mission, about five years after it closed. Between them, the two projects will mean 25 additional jobs at the Mission complex south of Tucson, bringing the workforce there to 663.

The copper concentrator's production is being expanded by 10,000 tons a year, on top of 60,000 tons a year produced in 2012. The expansion is expected to be finished by the end of this year, meaning its full impact on annual copper production will first be felt in 2014.

The process of concentrating copper starts with a slurry of water and pulverized copper ore. Through several processes, concentrating produces a finely ground, dried, powdery material consisting of about 28 percent copper. It's then shipped to a smelter.

The molybdenum plant has an operational capacity of 544 tons annually. The amount produced each year will depend on the grade of the ore, said Tom Aldrich, an Asarco vice president.

Asarco's concentrator expansion comes just as copper prices have dropped for most of this year, although they did show signs of improvement late last week.

Global copper prices had fallen 13 percent this year through last Wednesday, amid concerns that efforts to keep China's economy from overheating would curb metals demand, Bloomberg News reported. Second quarter copper prices for 2013 dropped 8.3 percent compared to the second quarter of 2012.

During the second quarter, copper prices fluctuated between $3.01 and $3.42 per pound, due to the U.S.'s slow economic recovery, the continuing Eurozone recession and China's recent economic growth slowdown, said Grupo Mexico, Asarco's parent company, in its second quarter report.

But on Thursday, copper prices at Comex in New York City hit about $3.27 a pound, their highest level since June 11. That occurred after customs data showed the same day that copper shipments to China - the world's largest copper user - rose in July to their highest levels since May 2012, Bloomberg reported.

"It does appear as though the Chinese central economic authorities are transitioning their attention back to fundamental economic development, after having skimmed some speculative froth," Michael Turek, a senior director at Newedge Group SA in New York, told Bloomberg. The shift is helping push markets toward "more positive upside momentum, rather than the sideways price action we have been encumbered with recently."

Asarco owner Grupo Mexico believes copper industry fundamentals will remain solid, it said in its quarterly report. It cited the British metals analyst CRU's estimate that the global copper market closed with a 140,000-ton supply deficit in this year's second quarter, due to pressures on supply from strikes, lower ore grades, collapses at two major mines and the closing of the largest smelter in India.