New EAF dust treatment process with the aid of strong magnetic field

Abstract

A new EAF dust treatment process named as "Lime Addition and Magnetic Separation Process (LAMS Process)" has been proposed to recover zinc oxide from the dust and to use solid residue as a flux for steel refining. The LAMS Process consists of the reaction of EAF dust with CaO followed by the adequate crushing and high gradient magnetic separation. The basic principle of this process has been established by revealing the phase equilibria in the CaO-Fe2O3-ZnO system where Ca2Fe 2O5 can be in equilibrium with pure ZnO rather than ZnFe2O4, which Is the major component of EAF dust, at higher CaO region. The conversion of zinc ferrite in EAF dust to ZnO and Ca 2Fe2O5 has been experimentally demonstrated by heating the dust with double molar amount of CaO at 1173 and 1373 K. It has also been demonstrated that the formed ZnO and Ca2Fe2O 5 can be separated by the strong magnetic field. Therefore, it may be possible to recover ZnO from EAF dust without the carbothermic reduction like Waelz process. © 2008 ISIJ.