RIO DE JANEIRO -- Brazilian diversified miner Cia. Vale do Rio Doce (CVRD) could be considering the sale of its 54.5-percent stake in aluminum smelter Valesul Aluminio SA, according to reliable sources.

The stake in Rio de Janeiro-based Valesul, which produces 98,000 tonnes of primary aluminum a year, is valued at between $110 million and $120 million.

Fellow diversified miner BHP Billiton, which owns the remaining 45.5 percent, last week revealed plans to sell its minority stake. "The parties interested in buying BHP Billiton's stake may also be interested in CVRD's stake," said the sources, who are close to both companies.

Valesul is a relatively costly operation compared with CVRD's joint-venture Aluminio Brasileiro SA (Albras) smelter in north Brazil because its electrical energy costs are higher. The smelter accounts for less than 10 percent of BHP Billiton's global aluminum capacity of more than 1 million tonnes a year.

Oslo-based Hydro Aluminium ASA and Brazil's Cia. Brasileira de Aluminio (CBA), Sao Paulo, as well as several unnamed U.S. and Asian companies, are considered favorites to purchase BHP Billiton's stake.

"The purchase of a Valesul stake could be attractive to a foreign company because it would allow the buyer to participate in the Brazilian market, while for a Brazilian company the issue would be an increase in market share," said a source close to the sale of the stake by Anglo-Australian miner BHP Billiton, which reportedly is already at an advanced stage.