Brazil's Vale SA said it has begun producing copper concentrate at its Lubambe mine in Zambia.

Production at the mine, which began on October 4, is expected to lead to an annual output of 45,000 tonnes of concentrate, the company said in a securities filing on Thursday. Copper concentrate is a raw version of commercial copper that is later refined by smelters.

Vale's efforts to increase copper production are part of a strategy by the company, the world's largest producer of iron ore, to diversify into other commodities.

In addition to copper, Vale in recent years has pushed into coal and fertilizer production. After increased efforts in nickel mining, the company this year expects to overtake Russia's Norilsk Nickel as the world's biggest producer of nickel.

Still, iron ore at present accounts for about 90 percent of Vale's profits and nearly three-quarters of its revenues.

The Lubambe mine is a joint venture with African Rainbow Minerals Ltd. and Zambia Consolidated Copper Mines Ltd., the statement added.