电渣重熔用La_2O_3-Al_2O_3-CaF_2精炼渣作用浓度模型

Calculating Model of Mass Action Concentration for La_2O_3-Al_2O_3-CaF_2 Refining Slag System for Electroslag Remelting

为了精确控制电渣重熔过程钢液的稀土含量,根据炉渣结构共存理论和相关相图,建立了La2O3-Al2O3-CaF2渣系的组元作用浓度计算模型,考察了炉渣成分、温度对渣中La2O3活度的影响。研究结果表明:模型计算的作用浓度值NLa2O3与文献实测的La2O3活度值吻合较好,说明本模型能够较好地反映该渣系的结构本质;La2O3活度随着渣系中Al2O3和CaF2含量的增加而降低,且Al2O3降低La2O3活度的能力比CaF2强;在成分为30%La2O3、20%Al2O3、50%CaF2(质量分数,下同)时,La2O3活度随着温度的升高而升高。因此,本模型能够对La2O3-Al2O3-CaF2渣系中La2O3活度进行定量分析,为电渣重熔过程精确控制钢液的稀土含量提供理论参考。

In order to accurately control the rare earth content in liquid steel in electroslag remelting （ESR） process, according to the ion and molecule coexistence theory （IMCT） of slag structure and corresponding phase diagrams, a thermodynamic calculating model for the evaluation of mass action concentrations （designated by Ni for structure unit i） for La2 O3-Al2 O3-CaF2 slag system was formulated. The results show that the calculated val- ues of Nt2O3 are in good agreement with the reported measured values, indicating that this calculating model can wholly embody the characteristics of the slag system. The activity of La2 O3 decreases with the increasing of the Al2 O3 and CaFe content, and Al2 O3 is stronger than CaF2 in decreasing the activity of La2 03. But the activity of La2O3 increase with the increasing in temperature at the composition range of 30% La2O3, 20% Al2O3, 50% CaFz. Above all, the activity of La2O3 in LazO3-Al2 O3-CaF2 slag system can be quantitatively analyzed by this thermodynamic model, and this model can provide a theoretical basis for precisely controlling the lanthanum con- tent in molten steel in ESR process.