Reduction Rate of Cr2O3 in a Solid Powder State and in CaO–SiO2–Al2O3–CaF2 Slags by Fe–C–Si Melts
Takamitsu Nakasuga, Haiping Sun, Kunihiko Nakashima, Katsumi Mori
In order to understand effective conditions to recover chromium from stainless steel-making slags, the kinetic behavior of Cr2O3 reduction by iron–carbon melts were investigated at various conditions by using solid Cr2O3 powder and Cr2O3–CaO–SiO2–Al2O3–CaF2 slags. The effect of temperature on the reduction rate of solid Cr2O3 was fairly large and the apparent activation energy was about 180 kJ mol-1. The overall reduction of solid Cr2O3 was considered to be controlled by a chemical reaction step. For reduction of Cr2O3 in slag, the addition of CaF2 to slag and of silicon to iron melt promoted the reduction rate, but the reduction of Cr2O3 powder was retarded by the silicon addition. The kinetic behavior of reduction of Cr2O3 in slag could be well simulated by the kinetic reaction model proposed previously. As a result, it was found that the overall reduction rate of Cr2O3 in slag was controlled by the mass transport in the slag phase.