非化学计量对铁氧化物还原热力学平衡的影响

铁氧化物是具有非化学计量比的化合物，非化学计量对铁氧化物的还原过程带来一系列影响。本文采用Dieckmann缺陷模型和Weiss的浮氏体理想固溶体模型分别对非化学计量比的磁铁矿和浮氏体进行了热力学计算。同时根据电荷守恒和物质守恒，对铁氧化物固溶体的综合缺陷度δ与还原失重率和亚铁含量的关系进行了分析，以期对实验终产物的判定提供依据。通过理论分析与计算，最终明确了不同化学计量比的磁铁矿和浮氏体在不同温度下的平衡还原势PCO(H2)，即相应的优势区图。在给定还原势的纯赤铁矿等温还原过程(未有金属Fe生成时)，当失重率小于6%时，还原产物属于Fe3+占优势的磁铁矿区域；当失重率高于6%时，反应进入Fe2+占优势的浮氏体区域。

Effect of nonstoichiometry on the thermodynamic equilibrium of iron oxide reduction processes

Iron oxides were nonstoichiometric chemical compounds. Their reduction processes were remarkably influenced by non-stoichiometries. Dieckmann’ s defect model of magnetite and Weiss’ s ideal solid solution model of wustite were adopted to analyze the thermodynamic influences on the reduction processes. The dependences of deficiency degreeδon weight loss and Fe2+ mole ratio were analyzed by using the charge conservation and mass conservation principles. These relationships were recommended to judge the final product of the reduction processes. According to theoretical analyses and calculations, the predominance area diagrams including dif-ferent nonstoichiometries of magnetite and wustite were determined in equilibrium with the reduction potentials PCO(H2) at different tem-peratures. It comes to a conclusion that when the reduction weight loss ratio is less than 6% ( without metallic Fe) , magnetite is pre-dominant in the pure hematite reduction at a certain temperature and reduction potential; but when the reduction weight loss ratio is higher than 6%, the process then enters the zone of wustite.