Abstract
The effect of Fe–Si on the carbothermaic reduction of Panzhihua titanomagnetite concentrates were investigated under argon atmosphere by isothermal experiments at 1623 K and non-isothermal experiments in the temperature range from room temperature to 1723 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 1273 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 (1273–1423 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.
