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Kong X.,Kunming University of Science and Technology | Kong X.,Key Laboratory of Vacuum Metallurgy of Non Ferrous Metals of Yunnan Province | Yang B.,Kunming University of Science and Technology | Yang B.,Key Laboratory of Vacuum Metallurgy of Non Ferrous Metals of Yunnan Province | And 9 more authors.
Vacuum | Year: 2014

A novel technology was developed to remove impurities from crude lead with high impurities by vacuum distillation. Refined lead (purity over 99%) was achieved through vacuum distillation using crude lead (92.88%) with high impurities as input material under a dynamic vacuum of 5-15 Pa. The results show that vacuum distillation should be taken to obtain lead from crude lead matrix, in which low-volatile impurities namely Cu, Sn, Ag and partial Sb are concentrated in residue at the first fraction stage of 1373 K. Volatilized lead containing high-volatile impurities such as Zn and As is distilled to remove these impurities at the second fraction stage of 973 K. But the property of impurity Bi is similar to lead that can not be separated from crude lead. The separation coefficient (βi) and the activity coefficient (γi) of impurity elements are calculated according to the experiments to fill the inadequate data of the thermodynamics. © 2014 Elsevier B.V. All rights reserved. Source


Wang F.,Kunming University of Science and Technology | Wang F.,Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province | Wang F.,State Key Laboratory Breed Base Of Complex Nonfer Metal Resources Clear Utilization In Yunnan Province | Chen X.,Kunming University of Science and Technology | And 11 more authors.
Journal of Molecular Structure | Year: 2012

Quantum chemistry and experimental method were used to study on pure and doped Gd2O2S crystals in this paper. The band structure and DOS diagrams of pure and doped Gd2O2S crystals which calculated by using DFT (Density Functional Theory) method were illustrated to explain the luminescent properties of impurities in crystals. The calculations of the crystal structure were finished by using the program of CASTEP (Cambridge Sequential Total Energy Package). The samples showed the characteristic emissions of Tb3+ ions with 5D4- 7FJ transitions and Eu3+ ions with 5D0-7FJ transitions which emit pure green luminescence and red luminescence respectively. The experimental excitation spectra of Tb3+ and Eu3+ doped Gd 2O2S are in agreement of the DOS diagrams over the explored energy range, which has allowed a better understanding of different luminescence mechanisms of Tb3+ and Eu3+ in Gd 2O2S crystals. © 2012 Elsevier B.V. All rights reserved. Source


Kong L.,Kunming University of Science and Technology | Kong L.,State Key Laboratory Breed Base Of Complex Nonfer Metal Resources Clear Utilization In Yunnan Province | Kong L.,Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province | Yang B.,Kunming University of Science and Technology | And 11 more authors.
Vacuum | Year: 2014

In this paper, the molecular interaction volume model (MIVM) has been used for a calculation of the activities of components of Pb-Sn-Sb ternary alloy system. The separation coefficients of the related binary alloys Sn-Pb and Sn-Sb and the vapor-liquid phase equilibrium of the Pb-Sn-Sb alloy system were also calculated by using the MIVM. Experiments for the separation of the Pb-Sn-Sb ternary alloy were carried out for the proper interpretation of the results of the model. The predicted data are in good agreement with the experimental results, which indicates that MIVM is reliable and convenient since it has certain physical meaning from the viewpoint of statistical thermodynamics and requires only two infinite dilute activity coefficients for each sub-binary system. © 2013 Elsevier Ltd. All rights reserved. Source


Yang C.-B.,Kunming University of Science and Technology | Yang C.-B.,Key Laboratory for Nonferrous Vacuum Metallurgy of Yunnan Province | Yang C.-B.,State Key Laboratory Breed Base Of Complex Nonfer Metal Resources Clear Utilization In Yunnan Province | Tian Y.,Kunming University of Science and Technology | And 14 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

Recent findings related to coagulable magnesium vapor nucleation and growth in vacuum were assessed critically, with emphasis on understanding these processes at a fundamental molecular level. The effects of magnesium vapor pressure, condensation temperature, and condensation zone temperature gradient on magnesium vapor nucleation in phase transitions and condensation from atomic collision and coacervation with collision under vacuum conditions were discussed. Magnesium powder and magnesium lump condensates were produced under different conditions and characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The right condensation zone temperature approach to the liquid transition primarily improved the magnesium vapor concentration rate. The gas-solid phase transition was primarily inhibited by setting a small condenser temperature gradient. Under the right condensation temperature and temperature gradients, increasing magnesium vapor partial pressure improved crystallization and reduced the oxidation rate. © 2014 The Nonferrous Metals Society of China. 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

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