* Ores, maintenance boost world No.1 copper mine's output * Copper output in 2012 reaches 1.076 mln T * Production jumps vs strike-hit 2011 SANTIAGO, Feb 5 (Reuters) - Output from Chile's Escondida jumped 31.6 percent in 2012 from a year earlier, state copper commission Cochilco said on Tuesday, as processing work and higher ore grades boosted production in the world's largest copper mine. Output from the world's largest copper mine, Chile's Escondida, jumped 31.6 percent in 2012 from a year earlier, state copper commission Cochilco said on Tuesday, boosted by processing work and higher ore grades, Escondida, which is majority owned by global miner BHP Billiton , produced roughly 1.076 million tonnes of copper last year compared with 817,700 tonnes in strike-hit 2011. Two "high return" projects intended to improve ore grades and increase capacity were completed last year, according to a BHP presentation on its website. The Escondida Ore Access program was completed in the June 2012 quarter and the Laguna Seca debottlenecking project ended in September. The mine's union stunned the copper market in 2011 by staging a two-week work stoppage, sending the mine's output tumbling. Workers at Escondida late last month approved a new contract proposal, calming fears of labor unrest. BHP said last month the mine was on track to increase its red metal output by 20 percent in the 2013 financial year. World No. 1 copper producer Chile is also on track to boost output this year, as it seeks to put operational woes, dwindling ore grades and labor stoppages behind it. BHP and Rio Tinto , which owns 30 percent of Escondida, have approved plans for a $4.5 billion expansion of the mine to boost output. Escondida produced 1.086 million tonnes of copper in 2010, according to Cochilco.