Thermodynamic model of dephosphorization of CaO-SiO2-MgO-Al2O3-FeO-P2O5-TiO2 slag system based on IMCT theory
Based on the theory of ionic-molecular coexistence(IMCT),a seven-component slag phos-phorus distribution ratio(Lp)model for CaO-SiO2-MgO-Al2O3-FeO-P2O5-TiO2 was established.This model has been validated in multiple slag systems and has the ability to accurately predict the enrich-ment behavior of phosphorus.The influence of each component on activity and Lp 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 1 000 to 1 600 ℃,as the tem-perature increases,the activities of FeO,MgO and CaO increase,while those of SiO2 and A12O3 de-crease,with no significant effect on TiO2.As the basicity increases from 0.92 to 1.32,the activities of CaO and MgO significantly increase,while those of SiO2 and Al2O3 decrease significantly,with a gradu-al increase in the activity of FeO and a nearly constant activity of TiO2.As the mass fraction of CaO in the slag increases,the activities of Al2O3 and SiO2 decrease,while those of CaO,MgO and FeO in-crease.As the mass fraction of SiO2 in the slag increases,the activities of basic oxides CaO,MgO and FeO decrease,while those of acidic oxides SiO2,Al2O3 and TiO2 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 frac-tion of Al2O3,FeO and TiO2 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 Al2O3 and TiO2 mass fractions increase,Lp gradually decreases.When the TiO2 mass fraction is around 10％,the slag composition of CaO(35.5％)-SiO2(26％)-MgO(10.2％)-Al2O3(12.5％)-FeO(5％)-TiO2 is selected,and the[P]in the molten iron can be controlled below 0.01％.
vanadium titanium magnetiteHIsmelt processslagphosphorus ratiothermodynamic modelion and molecule coexistence theory
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