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Sen W.,National Engineering Laboratory for Vacuum Metallurgy | Sen W.,Key Laboratory of Vacuum Metallurgy for Nonferrous Metal of Yunnan Province | Sen W.,Kunming University of Science and Technology | Xu B.-Q.,National Engineering Laboratory for Vacuum Metallurgy | And 11 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2011

The preparation of fine TiC powders by carbothermal reduction of TiO 2 in vacuum was investigated by XRD, SEM, XRF and laser particle sizer. Thermodynamic analysis indicates that it is easy to prepare TiC in vacuum and the formation sequence of products are Ti4O7 (Magneli phase), Ti3O5, Ti2O3, TiC xO1-x and TiC with the increase of reaction temperature. Experimental results demonstrate that TiC powders with single phase are obtained with molar ratio of TiO2 to C ranging from 1:3.2 to 1:6 at 1 550 °C for 4 h when the system pressure is 50 Pa, and TiC1.0 is gained when the molar ratio of TiO2 to C is 1:4 and 1:5. In addition, fine TiC1.0 powders (D50 equals 3.04 μm) with single phase and low impurities are obtained when the molar ratio of TiO2 to C is 1:4. SEM observation shows that uniform shape, low agglomeration, and loose structure are observed on the surface of block product. © 2011 The Nonferrous Metals Society of China. Source


Yan H.,National Engineering Laboratory for Vacuum Metallurgy | Xiong H.,National Engineering Laboratory for Vacuum Metallurgy | Xiong H.,State Key Laboratory of Complex Non Ferrous Metal Resources Clear Utilization | Xiong H.,Key Laboratory of Vacuum Metallurgy for Nonferrous Metal of Yunnan Province | And 8 more authors.
Xiyou Jinshu/Chinese Journal of Rare Metals | Year: 2016

The theoretical analysis and the experimental study on intensive removal of Tl and In from pure Cd by vacuum distillation were investigated respectively. Furthermore, the effect of distillation temperature on separating process was analyzed, and the influence of iron in steel materials on experimental result was discussed. According to the theoretical analysis, there was a possibility that Tl and In might be separated from Cd under vacuum conditions with ideal effect, which demonstrated that much purer Cd could be available through vacuum distillation. The experimental result showed that the volatilization rate of Cd had an increase trend as temperature of distillation rose. In content of volatiles increased rapidly, while its removal rate decreased a lot. In content of volatiles increased slowly, as its removal rate decreased a little and was kept at a low level with a rising temperature of distillation. Fe content of volatiles was almost always low, under 1×10-8, and the result showed that iron in steel materials did not affect the purification of Cd. When the system pressure was 2~5 Pa, the distillation temperature was 643 K and the holding time was 7 h, the volatile rate of Cd was 16.21%, the volatile content of Tl was 2.83×10-7, the removal rate reached 99.76%, In content was 2.327×10-7, the removal rate reached 97.97%, and the purity of Cd was 99.9999%. © Editorial Office of Chinese Journal of Rare Metals. All right reserved. Source


Xu S.,National Engineering Laboratory for Vacuum Metallurgy | Xu S.,State Key Laboratory of Complex Non Ferrous Metal Resources Clear Utilization | Xu S.,Key Laboratory of Vacuum Metallurgy for Nonferrous Metal of Yunnan Province | Song B.,National Engineering Laboratory for Vacuum Metallurgy | And 8 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2015

The activities of the constituent elements in a variety of binary alloys were calculated with the widely used thermodynamic models, including but not limited to the regular solution model, Miedema model, molecular interaction volume model (MIVM), non-random two-liquid (NRTL) equation and Wilson equation. The numbers of major parameters involved in each model were found to be in a descending order: Miedema model and MIVM > Wilson equation > NRTL equation and the regular solution model. The activities and average deviations of the alloys were calculated, such as the Bi-Pb, Bi-Sn, Cd-Pb and Pb-Sn alloys. The calculated results show that when it comes to prediction precision, NRTL equation does the best job and Miedema model does the worst. ©, 2015, Science Press. All right reserved. Source


Xu S.,National Engineering Laboratory for Vacuum Metallurgy | Xu S.,State Key Laboratory of Complex Non Ferrous Metal Resources Clear Utilization | Xu S.,Key Laboratory of Vacuum Metallurgy for Nonferrous Metal of Yunnan Province | Song B.,National Engineering Laboratory for Vacuum Metallurgy | And 8 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2015

A novel technique was developed to recycle Ag from the Pb-Ag-Cu ternary alloy, contained in copper anode slime and similar stuffs in electrolytic refining of non-ferrous metals, by vacuum distillation. The influence of the distillation conditions, including but not limited to the distillation temperature and time, Ag content and pressure, on the recovery rate of Ag and removal rate of Pb was physically modeled, theoretically analyzed and experimentally evaluated. The preliminary results show that the distillation temperature and time strongly affect the recycling of Ag. For example, distilled at 1173 K for 60 min (at 6 Pa), the direct recovery rate of Ag and removal rate of Pb were over 98% and 99%, respectively. For a Pb-Ag-Cu alloy with low Ag-content, Ag-recovery rate was 92%~94% and the Pb-removal rate was 99%, after vacuum distillation at 1223 K for 60 min. ©, 2015, Science Press. All right reserved. Source


Yan H.,National Engineering Laboratory for Vacuum Metallurgy | Yan H.,Kunming University of Science and Technology | Xiong H.,National Engineering Laboratory for Vacuum Metallurgy | Xiong H.,Key Laboratory of Vacuum Metallurgy for Nonferrous Metal of Yunnan Province | And 14 more authors.
Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology | Year: 2015

A novel technique was developed to separate Zn and Cd from high-Cd Zn-concentrate by vacuum distillation. The effect of the distillation conditions, including the pressure, distillation temperature and time, on the separation rates of Zn and Cd was theoretically calculated and experimentally investigated. Theoretically speaking, the novel technique is feasible. The experimental results show that a higher distillation temperature and a longer distillation time considerably increased direct-recovery rate of Cd and decreased Cd-purity in the volatile. For instance, distilled at 30 Pa and 400℃ for 60 min, the Cd-purity in the volatile was 96.5% with a Cd direct-recovery rate of 60.1%, and the Zn-purity in the residue was 87.42%. The multi-cycle (say, 3 cycles) distillation increased the Cd purity up to over 99.99% in the volatile. We suggest that the newly-developed, environmental friendly, simple technique be of much technological interest in processing the high-Cd Zn-concentrate on industrial scale. ©, 2015, Zhenkong Kexue yu Jishu Xuebao/Journal of Vacuum Science and Technology. All right reserved. Source

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