<Original Papers>Study of the Fixing of Chromium with Iron-silicate Slag (I) : Phase Equilibria of the FeO-Cr_2O_3-SiO_2 System in Contact with Metallic Iron

The dissolution behavior of chromium into iron-silicate melt is important in considering metallurgical processes or the disposal of solid waste material. However, little is known about the phase diagram of the iron oxide-chromium oxide-silica system. In this paper, the equilibrium phase relation of the FeO-Cr_2O_3-SiO_2 system when in contact with metallic iron has been clarified at temperatures of 1230 to 1400℃ under a nitrogen atmosphere. Through microscopic and EPMA examinations of samples prepared after melting and quenching in an ice-bath, the following facts have been presented : (l) An isothermal section at 1300℃ is drawn for a region containing the melt. Chromium is found in the melt and wustite or the spinel phase as a solid solution. (2) The temperature dependence of the liquidus surface is confirmed. The homogeneous liquid region becomes greater with increasing temperature, and the solubilities of Cr_2O_3 in iron-silicate melt at 1230,1300 and 1400℃ are 1.5,3 and 5% respectively. On the basis of the above results, the applicability of melting treatment of waste materials and the interaction between fire brick and slag are discussed