| The reliability of the two components activity value of 8 entire-concentration and 4 existing-saturation-concentration binary systems at different temperature was tested by using Gibbs-Duhem equation combine withα-function, the general average relative deviation of the two components are 7% and 13% respectively. which two binary slag system-wide concentrations of B2O3-SiO2 (1450℃,1550℃) and FeO-TiO2 (1400℃) and the existence of four concentrations of slag saturated system error is larger.The reason induced this results may be the few experiment data or less accuracy of measurement data.The average relative deviations of the other 6 entire-concentration binary systems are all less than 5% at different temperature. Thereby, the results of the test which made by using Gibbs-Duhem equation combine withα-function show that the experimental data of the 6 binary slag systems at different temperatures, except B2O3-SiO2 (1450℃,1550℃),FeO-TiO2(1400℃) and the existence of four existing-saturation-concentration of slag system are reliable. Infinite dilution activity coefficient, one of the most important parameters of metallurgical thermodynamics, of each component of 8 entire-concentration the slag systems was calculated and the results could apply some reference.Polynomial ofωandη(ωandηare bond energy parameters of binary slag systems) was obtained from optimization fitting of excess Gibbs energy with dichotomy and Taylor expansion. The activity values of 18 binary slag systems were calculated with the model of modified quasi-chemical model, and error analysis comparing with experiment data indicates that the general average relative deviation of the two components are 13% and 12% respectively. It could conclude that the activity values obtained from calculation fit better with experimental values, hence that the application of semi-empirical model (modified quasi-chemical model) on calculation and prediction of slag systems thermodynamic is reliable. However the physical meaning of the coordination number in this theory is rather ambiguous and further improvement need to be made. Inner structural features of the system had not been considered in modified quasi-chemical model, but the maximum ordering of the system occurs near at the component of the strongest association (or complexation) effect between ions in the system, and it could be taken for that the association effect of ionic bond has been considered.In this model only interaction of ions has been considered in multiterm expression ofωandη, and it will be more closer to the fact.With the help of two methods of geometric model (symmetry approximate and non-symmetry approximate) modified quasi-chemical model has been extend to ternary slag systems.With the application of this model on the system of SiO2-CaO-FeO, the activity value aFeO of the system of SiO2-CaO-FeO (1600℃, 1550℃) was obtained, the average relative deviation compared with experiment data are S*FeO (1600℃)=±40%, S*FeO (1550℃)=±45%, it inosculates better with experimental data. The average relative deviation between activity value aCaO and aSiO2 of the system of SiO2-CaO-FeO (1550℃) and the system of SiO2-CaO-FeO (1550℃)and the experiment data are S*CaO=±1497%,S*SiO2=±681%, respectively, it inosculates not good with experimental data. Activity values of aFe0, aCaO, aSiO2 in this system was calculated with Pelton bond energy parameter, and it inosculates good with the calculation results obtained by the author.In the mean time the same method was applied on slag system of SiO2-CaO-MnO (1550℃,1500℃), Activity value of this system component aMnO was obtained with non-symmetry approximate calculation, the relative deviation compared with experimental data are S*MnO (1550℃) =±22%,S*MnO (1500℃)=±41%, Which are in accordance with Pelton's results. it inosculates better with experimental data.Thereby the modified quasi-chemical model has obviously advantage in ternary slag systems. |
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