A novel molecular interaction chemical model (MICM) for silicate melts has been suggested based on statistical thermodynamics. It can simultaneously predict activities of all components in the CaO-FeO-SiO2 and CaO-Al2O3-SiO2 melts using only four binary parameters for each binary melt which can be determined by fitting activities of its two components. The results indicate that the predicted values of activity of FeO and SiO2 are in good agreement with the experimental data at 1823 K and 1873 K, and those of CaO, SiO2 and Al2O3 are in reasonable agreement with the graphical integration data of the Gibbs-Duhem equation. This shows that the model is effective in which the physical interaction plays a main role and the chemical one does the auxiliary function.
To confirm sub-regular solution model valid for predicting the activity of component in binary oxide systems,seven systems in the whole concentration and twelve systems presenting saturation concentration have been studied.The total average relative errors of component 1 and 2 are 3.2% and 4.1% respectively by application of the sub-regular solution model into the systems within the whole concentration.However,the total average relative errors are 16% and 1 088% in the systems presenting saturation concentration.The results show that sub-regular solution model is not good for predicting the systems presenting saturation concentration,especially for the systems containing acidic or neutral oxide.The reason may be that the influence of the two types of oxide on the configuration is greater in binary oxide systems.These oxides can be present in the form of complex anion partly,Si-O,Al-O,Ti-O and so on,for example (SiO4)4-.That is contrary to sub-regular solution model which is supposed that the oxide systems consist of cation and O2-.But compared with regular solution model and quasi-regular solution model,sub-regular solution model is closer to the characteristics of actual solution and the calculated results are superior.
Modified quasi-regular solution model has been available based on the sub-regular solution model and quasi-regular solution model in this article.The three parameters of this model are set by the computer-aided analysis based on the experimental data of activity at two different temperatures.Seven binary molten slag systems in the whole concentration are calculated by application of the model and the average relative error is within 10%.Ten binary molten slag systems presenting saturation concentration are also calculated,but the average relative error is bigger,especially for the systems containing acidic oxide and neutral oxide.The results show that the calculated results are superior to those calculated by application of regular solution model,sub-regular solution model and quasi-regular solution model.
The activity of FetO is very important in ironmaking and steelmaking process.In order to predict the activity of FetO and optimize the operation conditions in ironmaking and steelmaking process,by application of regular solution model in molten slag systems,FeO-Fe2O3-SiO2 ternary system,FeO-Fe2O3-SiO2-CaO and FeO-Fe2O3-SiO2-NiO quaternary systems have been studied by the chemical equilibrium between H2/H2O gas mixture and liquid slag contained in solid iron.The values of interaction energy between cations concerning steelmaking slags have been determined by application of ferric-ferrous iron equilibrium and iron-ferric iron equilibrium.And then the activity of FetO can be calculated.The results show that the relative error is 3.9% in FeO-Fe2O3-SiO2 system and 18% in FeO-Fe2O3-SiO2-CaO system.The prediction of activities of FetO in the systems are in good agreement with the measurements and the regular solution model is valid for predicting the activity of FetO in complex molten slags systems.The activity of FetO in FeO-Fe2O3-NiO system have not been tested presently,and the calculated result can not be assessed.
HOU Yan-qing,XIE Gang,TAO Dong-ping,YU Xiao-hua,LI Rong-xing (Faculty of Metallurgical and Energy Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China)
The component activity of Mn in Fe-C-Mn system as well as the component activities of C and Si in Fe-C-Si system was predicted by applying the pseudo-multicomponent approach of the molecular interaction volume model(MIVM)and the Wagner interaction parameter formalism(WIPF)respectively.The average relative errors between the predicted values of MIVM and the experimental data for the three components were 4.5%,17.0% and 13.0%,respectively,and those between the calculation results of the WIPF and the experimental data were 18.0%for Mn,9.0%for C and 27.0%for Si.The results indicated that the MIVM method could better predict the component activity of carbonaceous iron-based solution.Based on the data in an actual blowing process,the MIVM method was applied to predict the component activities of C and V as well as the transition temperature of vanadium oxidization(TTVO)in Fe-C-V-Si quaternary iron-based solution,and a comparative analysis of the predictions against the experimental data was carried out,with their average relative errors being 24.0% for C,7.3% for V and 1.0% for TTVO respectively.On that basis,the TTVO at Panzhihua Iron and Steel(Group)Co.,Ltd.was estimated by the MIVM method and an expression that the TTVO changed with composition and temperature of iron solutions was obtained by multiple linear regression method.The research results showed that the estimated values were in good agreement with the practical data.
The molecular interaction vacancy model (MIVM) is used to estimate simultaneously activities of all components in a range of entire composition of six binary oxide solid solutions and the MnO-FeO-CaO ternary solid solution by their binary infinite dilute activity coefficients. The average errors are the 0.03%-5.0% for the binaries and the 4.11%-25.2% for the ternary which is less than that (4.84%-41.2%) of the sub-regular solution model (SRSM). This shows that MIVM is more effective and reliable than SRSM for the ternary and does not depend on a polynomial approximation with some ternary adjustable parameters.
