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Kong L.,Kunming University of Science and Technology | Kong L.,State Key Laboratory Breeding Base of Complex Nonferrous Metal Resources Clear Utilization in Yunnan | Kong L.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | Yang B.,Kunming University of Science and Technology | And 12 more authors.
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2012

The activity coefficients of components of the Pb-Sn binary alloy system were calculated based on the molecular interaction volume model (MIVM). A significant advantage of this model lies in its ability to predict the thermodynamic properties of liquid alloys using only two binary infinite activity coefficients. Based on the MIVM, the vapor-liquid phase equilibrium of the Pb-Sn alloy system in vacuum distillation has been predicted using the activity coefficients of Pb and Sn. The results showed that the content of tin in the vapor phase was 0.008 wt pct, while in the liquid phase, it was 83 wt pct at 1173 K (900 °C); it reached 0.022 wt pct in the vapor phase, while in the liquid phase, it was 92 wt pct at 1223 K (950 °C); and it was 0.052 wt pct in the vapor phase, while in the liquid phase, it was 97.88 wt pct at 1273 K (1000 °C). The content of tin in the vapor phase increased with the distillation temperature increasing. Experimental investigations into the separation of Pb and Sn from the Pb-Sn alloy by vacuum distillation were carried out for the proper interpretation of the results of the model. The influence of the distillation time (20 to 80 minutes) and the distillation temperatures of 1173 K, 1223 K, and 1273 K (900 °C, 950 °C, and 1000 °C) on the separating effect was also studied. The experimental results showed that the content of tin in the vapor phase was 0.085 wt pct, while in liquid phase, it was 83 wt pct under the operational conditions of distillation temperature of 1173 K (900 °C), evaporation time of 20 minutes, and chamber pressure of 20 Pa; it reached 0.18 wt pct in the vapor phase, while in the liquid phase, it was 92 wt pct at 1223 K (950 °C), 20 minutes, and 20 Pa; and it was 0.35 wt pct in the vapor phase, while in the liquid phase, it was 97.88 wt pct at 1273 K (1000 °C), 20 minutes, and 20 Pa. In all these experiments, it was observed that the content of tin in the vapor phase increased as the distillation time and temperatures were increased. The experimental results are in good agreement with the predicted values of the MIVM for the Pb-Sn binary system. © 2012 The Minerals, Metals & Materials Society and ASM International. Source


Duan S.-F.,Kunming University of Science and Technology | Duan S.-F.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | Chen X.-M.,Kunming University of Science and Technology | Chen X.-M.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | And 8 more authors.
Journal of Central South University | Year: 2015

To make sure the intermediate products of the carbothermic reduction of Al2O3 process, such as Al4CO4, Al2CO and Al4C3, and the interaction of AlCl, AlCl2, AlCl3 with Al4CO4, Al2CO and Al4C3, respectively, thermodynamic analyses were used to study the chloride reaction production of them under the vacuum situation. The stable structures and electronic properties of AlCl, AlCl2 and AlCl3 adsorbed on Al4CO4, Al2CO and Al4C3 were calculated by first-principles calculations by the CASTEP module in the Materials Studio program. The results show that the AlCl3 and AlCl2 molecules have decomposed on the plane of Al4C3 (001), while there are no obvious decomposition of AlCl3 and AlCl2 on Al4CO4 (001) and Al2CO (001) planes. The adsorption of AlCl on the Al4CO4 (001) and Al2CO (001) planes is stronger than that on the Al4C3(001) plane. The interaction strength of AlCl3, as well as AlCl2, with Al4CO4, Al2CO and Al4C3 is in the sequence of Al4CO4Al2CO>Al4C3. © 2015, Central South University Press and Springer-Verlag Berlin Heidelberg. Source


Jiang W.-L.,Kunming University of Science and Technology | Jiang W.-L.,State Key Laboratory Breed Base Of Complex Nonfer Metal Resources Clear Utilization In Yunnan Province | Jiang W.-L.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | Deng Y.,Kunming University of Science and Technology | And 14 more authors.
Rare Metals | Year: 2013

Vacuum distillation is a technique suitable for low boiling and melting point materials, to remove the heavy and low vapor pressure impurities at low level. As indium has low melting point and high boiling point, it is suitable for refining by vacuum distillation. First, saturation vapor pressure for major elements in crude indium was calculated by the Clausius-Clay Prang equation, which could approximately predict the temperature and pressure during vacuum distillation process. Second, the activity coefficients for In-Cd, In-Zn, In-Pb, In-Tl at 1373 K, and In-Sn at 1573 K were acquired by means of molecular interaction on volume model. Vapor-liquid equilibrium composition diagrams of those above systems in crude indium were drawn based on activity coefficients. These diagrams could estimate the compositions of products in each process during the refinement of crude indium. Finally, 1.2-1.6 ton crude indium was used per day when vacuum distillation experiments were carried out, and experimental results are in good agreement with the predicted values of the vapor-liquid equilibrium composition diagrams. © 2013 The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg. Source


Chen X.-M.,Kunming University of Science and Technology | Chen X.-M.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | Yang B.,Kunming University of Science and Technology | Yang B.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | And 8 more authors.
TMS Annual Meeting | Year: 2013

To study on the generation of Al2O during the process of alumina carbothermal reduction reaction under high temperature and low pressure. Ab initio molecular dynamics simulation has been used to study on carbothermal reduction process under high-temperature and low-pressure. The models which consisted of Al2O3 and carbon(molar ratio 1:1 and 1:2) have been built to carry out ab initio molecular dynamics simulations under 60Pa and different temperature (1760K, 1860K, 1960K, 2160K). The results indicated, during the process of alumina carbothermal reduction, the order of the gaseous products discharge would be CO →Al → Al. The amount of carbon involved in the carbothermal reduction affected to the product. Under the condition of Al2O3: C (1:1), it tend to produce Al2O gas, under the condition of Al2O3: C (1:2), it tend to produce [Al2O]2 gas. The results can be used for the further study on the formation mechanism of Al2O in alumina carbothermal reduction. Source


Lu Y.,Kunming University of Science and Technology | Lu Y.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | Zhou Y.-Z.,Kunming University of Science and Technology | Zhou Y.-Z.,Yunnan Provincial Key Laboratory of Nonferrous Vacuum Metallurgy | And 12 more authors.
Journal of Central South University | Year: 2016

The feasibility study of the AlCl(g) generated by Al2O−AlCl2−C system under vacuum was carried out by thermodynamic analysis and CASTEP package of the Material Studio program which was based on density functional theory (DFT) formalism. Thermodynamic calculations indicate that AlCl and CO molecules can be formed under conditions of temperature 1760 K and the pressure of 60 Pa. The interaction of Al2O and AlCl2 with C shows that the chemical adsorption of Al2O and AlCl2 does take place on C(001) crystal plane, and at the same time, new chemical bond is formed between Al atom in Al2O and Cl atoms from one of the Al—Cl bonds in AlCl2. The results, after 1.25 ps dynamics simulation, indicate that adsorbed AlCl molecules are generated and CO molecule will be formed in this system, and they will escape from C(001) surface after a longer period of dynamic simulation time. It means that the reaction of Al2O and AlCl2 with C can be carried out under given constraint condition. © 2016, Central South University Press and Springer-Verlag Berlin Heidelberg. Source

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