Carbothermic reduction of titanomagnetite concentrates with ferrosilicon addition

Abstract

The effect of Fe-Si on the carbothermaic reduction of Panzhihua titanomagnetite concentrates were investigated under argon atmosphere by isothermal experiments at 1 623 K and non-isothermal experiments in the temperature range from room temperature to 1 723 K with a heating rate of 10 K/min, respectively. The morphology of reduced samples obtained by isothermal experiments was checked by scanning electron microscope. The results show that the addition of Fe-Si accelerates the carbothermic reduction rate of PTC. A part of silicon in the Fe-Si substitutes for carbon to participate the reduction of PTC. The addition of Fe-Si facilitates the nucleation and coalescence of metallic iron formed by reduction. A reaction mechanism for the carbothermic reduction of PTC with Fe-Si addition was proposed. The reduction process could be divided into three stages. In the first stage (lower than 1 273 K), the solid phase reactions with carbon and silicon as reductants are dominant. The exdothermic reduction by silicon, to a certain extent, promotes the reduction of PTC. In the second stage (1 273-1 423 K), the rate of reduction by CO is much faster than that of reduction by silicon, resulting in little influence of Fe-Si on the reduction of PTC. In the final stage, the reduction by silicon markedly occurs again, which further facilitates the coalescence of metallic iron and the reduction of PTC. © 2013 ISIJ.