Formation of 2CaO·SiO2 -3CaO·P2 O5 solid solution can improve the ability of dephosphorization for liquid phase slag and reduce the slag amount, In order to understand the change regulation of activity for the components in CaO-SiO2 -FeO-P2 O5 -Al2 O3 slag system a calculation model was established according to the coexistence theory of molecule and ion. The results showed that with increase of Al2 O3 content, activities of 2CaO·SiO2 , 3CaO·P2 O5 , 3FeO·P2 O5 gradually decrease. When basicity of the slag increases, activity of 3CaO ·SiO2 increases, while activities of 2CaO ·SiO2 , 3FeO ·P2 O5 increase at first and then decrease. With increase of FeO content, activities of 2CaO ·SiO2 , 3FeO ·P2 O5 and CaO ·Al2 O3 increase at first and then decrease, the maximum values occur when w( FeO) is 15%. When temperature rises, activity of CaO, 3CaO·SiO2 , gradually increases, while activity of 2CaO·SiO2 decreases.%2CaO·SiO2-3CaO·P2O5含磷固溶体的生成可提高转炉液相渣的脱磷能力,减少渣量.但目前CaO-SiO2-FeO-P2 O5-Al2 O3渣系中各组元活度的变化规律尚不明确,无法为分析含磷固溶体的形成机理提供理论依据.为此,本文依据分子离子共存理论建立了熔渣组元的活度模型,分析了不同条件下组元活度的变化规律.结果表明:随渣中Al2O3含量的增加,2CaO·SiO2、3CaO·P2O5、3FeO·P2O5的活度逐渐降低;随着碱度的增大,3CaO·P2O5的活度升高,2CaO·SiO2、3FeO·P2O5的活度则呈先升高后降低的趋势;随着渣中FeO含量的增加,2CaO·SiO2、3FeO·P2O5及CaO·Al2O3的活度逐渐增大,并在w(FeO)为15%时达到最大值,之后逐渐降低;升高温度会导致CaO、3CaO·SiO2的活度增大,2CaO·SiO2的活度降低.
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