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Wan L.,Jiangxi University of Science and Technology | Huang X.,Zhangyuan Tungsten Industry Co. | Deng D.,Zhangyuan Tungsten Industry Co. | Li H.,Zhangyuan Tungsten Industry Co. | Chen Y.,Zhangyuan Tungsten Industry Co.
Hydrometallurgy | Year: 2015

Abstract Sodium tungstate solution can be prepared by decomposing wolframite with sodium hydroxide. A new technique is developed for precipitating scheelite from the sodium tungstate solution by the addition of calcium hydroxide. In this study, the effects of several variables on the conversion of sodium tungstate are investigated. Results show that the effects of temperature and sodium tungstate concentration are significant. Specifically, 96.4% WO4 2 - was converted to scheelite in 2 h at 100 C with a calcium hydroxide stoichiometric ratio of 1.4 and a stirring speed of 350 rpm. The parent solution containing sodium hydroxide can be recycled as a leaching agent return to the wolframite decomposition process. © 2015 Elsevier B.V. All rights reserved. Source


Wan L.,Jiangxi University of Science and Technology | Yang L.,Jiangxi University of Science and Technology | Chen Y.,Jiangxi University of Science and Technology | Zhao L.,Zhangyuan Tungsten Industry Co. | Li H.,Zhangyuan Tungsten Industry Co.
International Journal of Refractory Metals and Hard Materials | Year: 2015

Scheelite was successfully prepared by solid-state calcination synthesis using wolframite [(Fe,Mn)WO4] and calcium carbonate as materials in air atmosphere. The effects of processing parameters, such as calcination temperature, holding time and calcium carbonate dosage on conversion ratio of wolframite were investigated. The conversion of wolframite increased with increasing of temperature, holding time and calcium carbonate dosage. The results demonstrated that 97.58% of wolframite was converted to scheelite in 2 h at temperature of 800 °C under the condition of calcium carbonate stoichiometric ratio of 1.3, and the corresponding reaction products are scheelite, iron oxide and manganese dioxide. © 2014 Elsevier Ltd. All rights reserved. Source


Wan L.-S.,Jiangxi University of Science and Technology | Liang Y.,Jiangxi University of Science and Technology | Liang Y.,HIGH-TECH | Yang L.,Jiangxi University of Science and Technology | And 2 more authors.
Environment, Energy and Sustainable Development - Proceedings of the 2013 International Conference on Frontier of Energy and Environment Engineering, ICFEEE 2013 | Year: 2014

In view of the technology status quo of unclosed smelting and sewage discharge in the current tungsten smelting, a novel method is proposed to digest scheelite with ammonium phosphate under the condition of low concentration of ammonia in this paper. Under the condition of 40 hours' mechanical activation, 450 rpm agitation speed, 2.0 times Ammonium phosphate dosage to stoichiometry, 3 hours' reactive time, temperature of 180 °C, 30 g L-1 concentration of ammonia water and ratio of liquid to solid 2, the WO 3 extraction is more than 98%. The ammonium tungstate can be obtained directly by the method, which ends over 200 years of history of tungsten smelting with acid or alkli and establishes the foundation for the development of closed smelting process of scheelite. © 2014 Taylor & Francis Group, London. Source


Wan L.-S.,Jiangxi University of Science and Technology | Huang Y.,Jiangxi University of Science and Technology | Xu G.-Z.,Zhangyuan Tungsten Industry Co. | Li H.-C.,Zhangyuan Tungsten Industry Co. | And 2 more authors.
Environment, Energy and Sustainable Development - Proceedings of the 2013 International Conference on Frontier of Energy and Environment Engineering, ICFEEE 2013 | Year: 2014

In this paper, thermodynamics research on ammonium phosphate digestion of scheelite under the condition of low concentration of alkali was studied. Gibbs free energy of formation and equilibrium constant under different temperature on ammonium phosphate digestion of scheelite was presented by thermodynamic calculation. It shows that scheelite and ammonium phosphate reaction has great thermodynamic driving force. 100°C is the best reaction temperature in theroy because ΔG is the minimum value. © 2014 Taylor & Francis Group, London. Source


Wan L.-S.,Jiangxi University of Science and Technology | He R.-U.,Jiangxi University of Science and Technology | Xu G.-Z.,Zhangyuan Tungsten Industry Co. | Li H.-C.,Zhangyuan Tungsten Industry Co. | And 2 more authors.
Environment, Energy and Sustainable Development - Proceedings of the 2013 International Conference on Frontier of Energy and Environment Engineering, ICFEEE 2013 | Year: 2014

In this thesis, we study on low alkali environment, the dynamics factors affecting of decomposition of ammonium phosphate scheelite, the experimental results show that under the condition of low alkali decomposition of pressurized scheelite is heterogeneous reaction process, PO4 3- from the solution to the scheelite surface diffusion, to infiltrate into the internal after react with scheelite. © 2014 Taylor & Francis Group, London. Source

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