Miner Rio Tinto said it expects mined copper production to fall about 15% this year, mainly due to lower grades, an executive said.

Head of Rio’s copper unit, Andrew Harding, said copper output would fall to about 680,000t in 2010 from 804,700t last year, he told Reuters.

Profits from copper contributed 32% to the company’s underlying earnings in 2010.

The global copper market is expected to see a small surplus in 2010 but a strong deficit next year, Harding said.