RIO DE JANEIRO -(Dow Jones)- Murilo Ferreira, chief executive officer of Brazilian iron ore miner Vale SA (VALE, VALE5.BR), the world's biggest iron ore producer, said it is "critical" for the company to win back market share for the steelmaking raw material in Brazil's domestic market. "We used to have 70% of the Brazilian iron ore market and now we have 50%, and this will fall to 29% in 2014," Ferreira said Thursday on a conference call with analysts. The company is proceeding with plans to build steelworks in Brazil in order to guarantee local demand for its ore, he said. The loss in market share is not because domestic demand for the steelmaking ingredient is shrinking but because some of Vale's major steelmaking customers in Brazil, including Companhia Siderurgica Nacional (CSNA3.BR, SID), Usinas Siderurgicas de Minas Gerais SA (USIM5.BR), ArcelorMittal Brasil (MT) and Gerdau SA (GGBR4.BR) are now developing their own iron ore mines to gain self-sufficiency, Vale strategies director Jose Carlos Martins said. Vale's steelworks project in Brazil's northeastern Ceara state is now at a "very advanced stage," Ferreira said. Vale currently has a 50% stake in the project, whose other partners are South Korean steelmakers Posco and Dongkuk Steel, who have shown great motivation for the project, Ferreira said. Vale will eventually reduce its stake in the mill, named Companhia Siderurgica do Pecem, to 20% as the overseas partners up their stakes, he said. Vale will reveal full plans for its steelmaking strategies in Brazil in its investment plan that will be announced Nov. 28 at the Vale Day for investors in New York on Nov. 28, Ferreira said. -By Diana Kinch, Dow Jones Newswires; +552125866086; diana.kinch@dowjones.com