Brazilian miner Vale SA, the world's biggest iron ore producer, has said it is open to working with state-controlled Petroleo Brasileiro SA towards a possible project cooperation on rare earths.

"Petrobras uses rare earths and Vale has reserves of rare earths," Vania Somavilla, Vale SA's human resources and corporate services director, was quoted by Dow Jones Newswires as saying to reporters at an event in Minas Gerais state.

Last week, Vale SA and Petrobras finalised an agreement that will pave the way for cooperation projects on fertilisers raw materials, oil, gas and biodiesel, areas of which both Brazilian firms hold interests.

"There are various areas, we're going to put everything on the table for discussion and work towards a common agenda," Ms Somavilla said, noting both companies have not yet discussed any specific joint decision.

Vale SA is a Brazilian multinational diversified metals and mining corporation and is regarded as the second-largest mining company in the world. It is the largest producer of iron ore, pellets, and second largest of nickel. It also produces manganese, ferroalloys, copper, bauxite, potash, kaolin, alumina and aluminium.

In October 2011, the world got excited when the company announced the major discovery of deposits of rare-earth minerals at its giant Salobo copper-mine project at Carajas in Para state.

Scheduled to start supplying copper in 2012, Salobo is one of Vale SA's biggest copper projects. Expected yield in the first quarter is pegged at 100,000 metric tonnes copper.

The rare earths discovery at Salobo has been likened to the rare-earth potential of Australia's Olympic Dam multimineral deposit.

"Vale would bring big benefits to Brazil by entering into this rare earth market and I think it's an important thing for the west as a whole. It would also benefit Vale as a company," Aloizio Mercadante, Brazil's science and technology minister, said in 2011.