Reduction mechanism of Fe2O3-Cr2O3-NiO system by carbon  

作　　者：张延玲 郭文明 刘洋 贾昕磊 

机构地区：[1]State Key Laboratory of Advanced Metallurgy (University of Science and Technology Beijing), Beijing 100083, China

出　　处：《Journal of Central South University》2016年第6期1318-1325,共8页中南大学学报（英文版）

基　　金：Project(51074025) supported by the National Natural Science Foundation of China;Project(FRF-SD-12-009A) supported by the Fundamental Research Funds for the Central Universities,China

摘　　要：Isothermal experiments on the reduction of Fe_2O_3-Cr_2O_3-NiO(molar ratio of Fe-to-Cr-to-Ni is 3:2:2)by graphite were carried out at 1350–1550°C,and effects of various factors on reduction degree were studied.The results show that the reaction rate of the Fe_2O_3-Cr_2O_3-NiO system is fast during the initial period(reduction degree,α<38%),and then the rate decreases until the end of the reduction.Factors such as temperature,carbon content,sample size have a more significant effect during the final stage(α>38%).The metallic product formed at the initial stage(a Fe-Ni alloy)greatly promotes the reduction of Cr2O3 at the final stage.Further,during the reduction of Fe_2O_3-Cr_2O_3-NiO by carbon,interfacial reaction is the rate-controlling step and g(α)=1-(1-α)0.5 is the reaction mechanism for the initial stage,whereas two-dimensional diffusion is the rate-controlling step and f(α)=α+(1-α)ln(1-α)is the reaction mechanism for the final stage.The apparent activation energies are 55.43 k J/mol and 174.54 k J/mol for the initial and the final stages,respectively.Isothermal experiments on the reduction of Fe2O3-Cr2O3-NiO （molar ratio of Fe-to-Cr-to-Ni is 3：2：2） by graphite were carried out at 1350–1550°C, and effects of various factors on reduction degree were studied. The results show that the reaction rate of the Fe2O3-Cr2O3-NiO system is fast during the initial period （reduction degree,α〈38%）, and then the rate decreases until the end of the reduction. Factors such as temperature, carbon content, sample size have a more significant effect during the final stage （α〉38%）. The metallic product formed at the initial stage （a Fe-Ni alloy） greatly promotes the reduction of Cr2O3 at the final stage. Further, during the reduction of Fe2O3-Cr2O3-NiO by carbon, interfacial reaction is the rate-controlling step and g（α）=1？（1？α）0.5 is the reaction mechanism for the initial stage, whereas two-dimensional diffusion is the rate-controlling step and f（α）=α＋（1？α）ln（1？α） is the reaction mechanism for the final stage. The apparent activation energies are 55.43 kJ/mol and 174.54 kJ/mol for the initial and the final stages, respectively.

关 键 词：Fe2O3-Cr2O3-NiO system isothermal reduction reduction degree KINETICS reaction mechanism 

分 类 号：O643.12[理学—物理化学]