Thermodynamics of Tungsten Ores Decomposition Process Options

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Volume Title

A3 Kirjan tai muun kokoomateoksen osa

Date

2018

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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