| Researches on the phase equilibrium of slag-melt-gas have always been the focuses of thermodynamics during the processes of pyrometallurgy. In this paper, the thermodynamic property of Sn and Fe in slag-melt-gas phase can be gotten with the method of Molecular Interaction Volume Model(MIVM) by introducing the concepts of pseudo-multicomponent approach in tin mineral concentrate reduction smelting process, which provides theoretical basis for tin metallurgical process.According to the method of extracting activity from binary phase diagrams suggested by G.Z. CHOU, the binary activity data of FeO-SnO and CaO-SnO were obtained in this thesis. Meanwhile, the corresponding parameters Bij and Bji can be fitted out using MIVM, which provides a good preparation for predicting the thermodynamic property of multi-component slag.In this paper, the activities of tin-based melts including Sn-Ag-Bi, Sn-Ag-In, Sn-Bi-Cu, Sn-Cu-Zn, Sn-Mg-Zn, Sn-Fe-Pb and Sn-Ag-Bi-Cu were predicted by RSM, SRSM and MIVM, respectively. Compared with the corresponding experimental values, the predicted results were as follows:the average standard deviations of RSM, SRSM, and MIVM were 0.0736,0.0771, and 0.0253, respectively. The corresponding average relative error was 30%,30%,9%, respectively. The predicted results agreed well with the experimental ones. Obviously, the results predicted by MIVM were obviously superior to those predicted by RSM and SRSM, the predicted values of RSM and SRSM were similar. And the data predicted by MIVM can be regarded as the reference data for the thermodynamics researches of tin-based melts. Consequently, It was determined that MIVM is the main model which is suitable for the thermodynamic properties researches of tin-based alloy.The activities of tin-based slag including CaO-FeO-SiO2, SnO-SiO2-FeO, SnO-SiO2-CaO and SnO-FeO-SiO2-CaO were predicted by MIVM and its pseudo-multicomponent approach. Furthermore, Comparison between the predicted values and the experimental ones was also conducted. The average standard deviation and average relative error of the predicted values were 0.032 and 8%, respectively, which coincides well with the experimental values. The predicted results can be used as the reference data for thermodynamics researches and optimizing the production process of the reduction and smelting of tin.Based on the accuracy of activity predicted by the MIVM and its pseudo-multicomponent approach, a calculating model of component activity in the quinary slag system of SnO-FeO-SiO2-CaO-Al2O3 was established by employing the MIVM pseudo-multicomponent approach. Furthermore, the activities of SnO and FeO in this system were also predicted, the average relative error was 23%. Meanwhile, the metal phase equilibrium constant and equilibrium distribution coefficient of Sn and Fe were also predicted by using different slag silicate degrees, and the average relative error was 2.5%. The predicted values coincided well with the data obtained during the actual production process. The formula of reflecting the variation relationship of tin equilibrium distribution coefficient with the temperature and composition was gotten as follows:lg L=3.001-1644/T-1.829x[Fe]+lg(γSnO/γFeO)The data calculated by this formula can be used as a thermodynamic reference data for the tin smelting process and practical production. In this paper, the research results have practical guiding for research and development of the metallurgical processes of tin and tin alloy. |
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