Thermodynamic study of Multi-Component Calcium Ferrite

用试剂级粉末合成了三种不同组成的四元铁酸钙，研究了它们在CO-CO_2混合气体中的还原顺序和还原平衡。(1)三种具有不同化学成分的样品在1300 ℃下在空气中烧制1小时。成分矿物鉴定结果表明，合成的样品大部分由四元铁酸钙组成。(2)四元铁酸钙经磁铁矿（Fe_3O_4）和浮氏体（FeO）还原为铁，浮氏体中含有CaO、SiO_2和Al_2O_3。四元铁酸钙的还原顺序与二元铁酸钙不同。(3)除初始还原阶段外，四元铁酸钙的还原顺序由以下方程给出。'Fe_3O_4'（s）+CO（g）= 3 'FeO'（S）+CO_2（g）（1）'FeO'（s）+CO（g）=Fe（S）+CO_2（g）（2）四元铁酸钙还原的平衡CO浓度高于纯铁氧化物还原的平衡CO浓度。四元铁酸钙还原的CO-CO_2气体组成的温度平衡线与铁氧化物还原的温度平衡线大致平行。根据四元铁酸钙的组成，反应（1）和（2）的平衡CO浓度的值变化。

Three kinds of quaternary calcium ferrites, whose composition differed from each other, were synthesized from reagent grade powders and the reduction sequence and the equilibria of those samples with CO-CO_2 gas mixture were investigated and the following results were obtained.(1) Three kinds of samples having different chemical compositions were fired at 1300ﾟC for one hour in the air. The result of the identification of constituent minerals, revealed that most part of the synthesized samples consisted of quaternary calcium ferrite.(2) Quaternary calcium ferrite is reduced to iron by way of magnetite('Fe_3O_4') and wustite('FeO'), which contained CaO, SiO_2, and Al_2O_3. The reduction sequence of quaternary calcium ferrite is different from binary calcium ferrite.(3) The reduction sequence of quaternary calcium ferrite is given by the following equations except for the initial reduction stage.'Fe_3O_4'(s)+CO(g)=3'FeO'(S)+CO_2(g) (1)'FeO'(s)+CO(g)=Fe(S)+CO_2(g) (2)The equilibrium CO concentrations for the reduction of quaternary calcium ferrite were higher than those for the reduction of pure iron oxides. The lines of temperature-equilibrium CO-CO_2 gas composition for the reduction of quaternary calcium ferrite were in approximately parallel with those for the reduction of iron oxides. Depending on the composition of quaternary calcium ferrite, the values of the equilibrium CO concentration for the reactions (1) and (2) varied.