Thermodynamics of Tungsten Ores Decomposition Process Options

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Volume Title
A3 Kirjan tai muun kokoomateoksen osa
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Date
2018
Major/Subject
Mcode
Degree programme
Language
en
Pages
12
2441-2453
Series
Extraction 2018, The Minerals, Metals & Materials Series
Abstract
The thermodynamics of tungsten ore decomposition in mineral acid and alkaline solutions were studied. The published thermodynamic data of tungsten minerals were collected and assessed. The Gibbs energies of CaWO4 (−1538.43 kJ/mol), FeWO4 (−1053.91 kJ/mol), MnWO4 (−1206.08 kJ/mol), H2WO4 (−1003.92 kJ/mol), and Na2WO4 (−1455.58 kJ/mol, aq) at 25 °C were adopted in the calculation using HSC software. The results show that CaWO4 is decomposed more readily in Na2CO3 solution than in NaOH, while FeWO4 and MnWO4 are more reactive in NaOH solutions. From a thermodynamic point of view, tungsten ore decomposes easily in acid solutions despite most ΔG o T ΔGTo increasing slightly with temperature. Oxidizing Fe2+ to Fe3+ in acidic solutions facilitates decomposition of FeWO4, and the reaction of CaWO4 in H2SO4 solution occurs more easily than in other mineral acids, due to the formation of sparsely soluble CaSO4. The results fit well with the experimental data and industrial experience previously reported in the literature.
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Keywords
Scheelite, Wolframite, Mineral acid, Alkaline media, Gibbs energy
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Citation
Shen , L , Li , X & Taskinen , P 2018 , Thermodynamics of Tungsten Ores Decomposition Process Options . in B Davis , M Moats & S Wang (eds) , Extraction 2018 : Proceedings of the First Global Conference on Extractive Metallurgy . The Minerals, Metals & Materials Series , Springer , pp. 2441-2453 , Global Conference on Extractive Metallurgy , Ottawa , Ontario , Canada , 26/08/2018 . https://doi.org/10.1007/978-3-319-95022-8_206