Effect of Flux Addition on the Reduction of EAF Slag Containing Cr<sub>2</sub>O<sub>3</sub> and MnO

When using steel scraps containing Cr and Mn as raw materials in electric arc furnace (EAF) steelmaking, EAF steelmaking slag containing Cr2O3 and MnO is inevitably produced as a by-product. Since Cr and Mn are valuable elements, it is economically and environmentally important to recover by reduction of EAF slag and reuse those elements into steelmaking process as alloying materials. In this study, to improve the recovery efficiency, flux addition to EAF slag was investigated both thermodynamically and experimentally. At first, thermodynamic calculations were performed using Al2O3, CaF2 and SiO2 as candidate fluxes, and it was found that SiO2 has the greatest potential to increase the slag liquid fraction and to improve the recovery efficiency. Then, reduction experiments using an actual EAF slag containing 8mass% Cr2O3 and 6mass% MnO were carried out at 1573 K with SiO2 flux addition. As a result, slag liquid fraction and the recovery efficiency of Cr and Mn increased with increasing the amount of SiO2 addition. Up to 81% of Cr and 61% of Mn in an EAF slag could be recovered. Furthermore, reduction experiments using different reducing agents were conducted. Despite the slag liquid fraction being the same, differences in recovery efficiency were observed. It was suggested that not only slag liquid fraction, but also liquid fraction of reduced metal is necessary to improve the recovery efficiency.