Electrochemical behavior of Fe(Ⅲ)in Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)molten salt  

Fe(Ⅲ)在Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)熔盐中的电化学行为

作　　者：FENG Sen ZHANG Jun-jie DIOP Mouhamadou Aziz LIU Ai-min WANG Zhao-wen BOCA Miroslav SHI Zhong-ning 冯森;张俊杰;刘爱民;王兆文;BOCA Miroslav;石忠宁(Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education),Northeastern University,Shenyang 110819,China;Institute of Inorganic Chemistry,Slovak Academy of Sciences,Dubravska cesta 9,SK-84536 Bratislava,Slovakia;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]Key Laboratory for Ecological Metallurgy of Multimetallic Mineral,Northeastern University,Shenyang 110819,China [2]Institute of Inorganic Chemistry,Slovak Academy of Sciences,Dubravska cesta 9,SK-84536 Bratislava,Slovakia [3]State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China

出　　处：《Journal of Central South University》2024年第9期3024-3033,共10页中南大学学报（英文版）

基　　金：Project(52074084)supported by the National Natural Science Foundation of China。

摘　　要：The high-temperature requirement for liquid iron smelting via molten oxide electrolysis presents significant challenges.This study investigates the electrochemical reduction of Fe(Ⅲ)in a novel low-temperature electrolyte,Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3),utilizing cyclic voltammetry and square wave voltammetry techniques.The results show that Fe(Ⅲ)reduction occurs in two steps:Fe(Ⅲ)+e^(−)→Fe(Ⅱ),Fe(Ⅱ)+2e^(−)→Fe,and that the redox process of Fe(Ⅲ)/Fe(Ⅱ)at the tungsten electrode is an irreversible reaction controlled by diffusion.The diffusion coefficients of Fe(Ⅲ)in the molten Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)in the temperature range of 1248–1278 K are between 1.86×10^(−6)cm^(2)/s and 1.58×10^(−4)cm^(2)/s.The diffusion activation energy of Fe(Ⅲ)in the molten salt is 1825.41 kJ/mol.As confirmed by XRD analysis,potentiostatic electrolysis at−0.857 V(vs.O_(2)/O_(complex)^(2-))for 6 h produces metallic iron on the cathode.为了降低熔融氧化物电解冶炼铁的温度,本文找到一种新的熔融氧化物电解质体系Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3),并研究了Fe(Ⅲ)在该电解质中的电化学行为。首先,通过热力学论证了该工艺的理论可行性。其次,以钨丝为工作电极,采用循环伏安法和方波伏安法在Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)低温电解质中研究Fe(Ⅲ)络合离子的电化学还原机理。结果表明,在Na_(2)SiO_(3)-SiO_(2)-Fe_(2)O_(3)熔融氧化物的循环伏安曲线中出现4个还原峰,其中,0.243 V和−0.857 V(vs.O_(2)/O_(complex)^(2-))处还原峰对应的反应为Fe(Ⅲ)络合离子两步还原为金属铁,包括Fe(Ⅱ)络合离子的形成。络合离子Fe(Ⅲ)在钨电极上被还原为金属铁是受扩散控制的不可逆反应。在1248–1278 K温度范围内,Fe(Ⅲ)在Na_(2)SiO_(3)-SiO_(2)熔盐中的扩散系数在1.86×10^(−6)cm^(2)/s和1.58×10^(−4)cm^(2)/s之间。Fe(Ⅲ)在熔盐中的扩散活化能为1825.41 kJ/mol。最后,分别对1278 K下的阴极产物进行扫描电子显微镜、能量分散光谱和X射线衍射分析。结果表明,在−0.857 V下恒电位电解6 h的产物为金属铁。

关 键 词：molten oxide electrolysis(MOE) electrochemical behavior cyclic voltammetry potentiostatic electrolysis diffusion coefficients Fe(Ⅲ) 

分 类 号：TF55[冶金工程—钢铁冶金] O657.1[理学—分析化学]