基于IMCT理论的CaO-SiO_(2)-MgO-Al_(2)O_(3)-FeO-P_(2)O_(5)-TiO_(2)渣系脱磷热力学模型

Thermodynamic model of dephosphorization of CaO-SiO_(2)-MgO-Al2O3-FeO-P_(2)O_(5)-TiO_(2) slag system based on IMCT theory

基于离子分子共存理论(IMCT)建立了CaO-SiO_(2)-MgO-Al_(2)O_(3)-FeO-P_(2)O_(5)-TiO_(2)七元熔渣磷分配比(LP)模型,该模型已在多个熔渣体系中被验证,具有较为精确的预测磷富集行为的能力,进一步分析了各组元成分对活度及L_(P)的影响,通过该模型总结了冶炼钒钛磁铁矿的合理熔渣成分。结果表明:在1000~1600℃范围内,随着温度的升高,FeO、MgO与CaO活度上升,SiO_(2)与Al_(2)O_(3)的活度随之减小,对TiO_(2)无明显影响。随着碱度由0.92升高至1.32,CaO、MgO的活度明显上升,SiO_(2)和Al_(2)O_(3)的活度明显下降,FeO的活度逐渐增加,TiO_(2)的活度基本保持不变。随着渣中CaO质量分数增加,Al_(2)O_(3)、SiO_(2)的活度随之减少,CaO、MgO、FeO的活度随之增大。随着渣中SiO_(2)质量分数增加,渣中碱性氧化物CaO、MgO、FeO的活度随之减少,渣中酸性氧化物SiO_(2)、Al_(2)O_(3)、SiO_(2)的活度随之增加。渣系中MgO质量分数由4%增加到14.5%后,各组元活度的变化规律与CaO基本相同,但影响程度弱于CaO。渣系中Al_(2)O_(3)、FeO和TiO_(2)质量分数增加后,仅使得自身活度显著增加,对其它组元的活度影响程度相对较小;随着碱度和FeO质量分数的增加,LP逐渐增加;随着MgO质量分数的增加,Lp先降低后增加;随Al_(2)O_(3)、TiO_(2)质量分数的增加,LP逐渐降低;TiO_(2)质量分数在10%左右时,选取熔渣组分为CaO(35.5%)-SiO_(2)(26%)-MgO(10.2%)-Al_(2)O_(3)(12.5%)-FeO(5%)-TiO_(2),铁水中[P]可控制在0.01%以下。

Based on the theory of ionic-molecular coexistence(IMCT),a seven-component slag phosphorus distribution ratio(L_(P))model for CaO-SiO_(2)-MgO-Al_(2)O_(3)-FeO-P_(2)O_(5)-TiO_(2)was established.This model has been validated in multiple slag systems and has the ability to accurately predict the enrichment behavior of phosphorus.The influence of each component on activity and L_(P)was further analyzed,and the reasonable slag composition for smelting vanadium-titanium magnetite was summarized through this model.The results show that within the temperature range of 1000 to 1600℃,as the temperature increases,the activities of FeO,MgO and CaO increase,while those of SiO_(2)and Al_(2)O_(3)decrease,with no significant effect on TiO_(2).As the basicity increases from 0.92 to 1.32,the activities of CaO and MgO significantly increase,while those of SiO_(2)and Al_(2)O_(3)decrease significantly,with a gradual increase in the activity of FeO and a nearly constant activity of TiO_(2).As the mass fraction of CaO in the slag increases,the activities of Al_(2)O_(3)and SiO_(2)decrease,while those of CaO,MgO and FeO increase.As the mass fraction of SiO_(2)in the slag increases,the activities of basic oxides CaO,MgO and FeO decrease,while those of acidic oxides SiO_(2),Al_(2)O_(3)and TiO_(2)increase.After increasing the mass fraction of MgO in the slag from 4%to 14.5%,the variation law of each component activity is basically the same as that of CaO,but the influence is weaker than that of CaO.After increasing the mass fraction of Al_(2)O_(3),FeO and TiO_(2)in the slag,only their own activities significantly increase,with relatively small effects on the activities of other components.As the basicity and FeO mass fraction increase,LP gradually increases.As the MgO mass fraction increases,Lp first decreases and then increases.As the Al_(2)O_(3)and TiO_(2)mass fractions increase,LP gradually decreases.When the TiO_(2)mass fraction is around10%,the slag composition of CaO(35.5%)-SiO_(2)(26%)-MgO(10.2%)-Al_(2)O_(3)(12.5%)-FeO(5%)-TiO_(2)is selected,and the[P]in the molten iron can be controlled below 0.01%.