On the Electrochemical Reduction Mechanism of CaWO4 to W Powder

Erdogan, Metehan; Karakaya, Ishak

doi:10.1007/s11663-012-9689-4

Cited by 17 publications

(9 citation statements)

References 8 publications

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“…The use of W as the WE for CV measurements in CaCl 2 was also reported by Claux et al 19 Some small peaks are visible in their CVs in the same potential region, but only a brief mention of a possible tungsten oxide reduction and re-oxidation was postulated. Erdogan and Karakaya 16 performed CVs on CaWO 4 in molten CaCl 2 , and the location of redox peaks are consistent with our observations. Tang et al 17 A list of plausible electrochemical reactions involving CaCl 2 , CaO, and W and their calculated standard potentials at 1123 K based on thermochemical data is given in Table II.…”

Section: Resultssupporting

confidence: 87%

“…1,2 The solubility and thermodynamic stability of oxide ions in these melts makes CaCl 2 an attractive flux for the reduction of oxides to metal. [3][4][5][6][7] It also has been the subject of extensive research and development as an ideal medium for the electrolytic reduction of titanium oxide, [8][9][10][11][12][13][14] scheelite (calcium tungstate), [15][16][17][18] rare earth oxides, [19][20][21][22] other metal oxides [23][24][25][26][27] and conversion of CO 2 28,29 due to its solubility for oxide ions. In some cases, the solubilization of oxide ions into CaCl 2 is desirable.…”

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confidence: 99%

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Electroanalytical Measurements of Oxide Ions in Molten CaCl₂on W electrode

Zhang

Rappleye

Nelson

et al. 2021

J. Electrochem. Soc.

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The electrochemical interaction of oxide ions with tungsten electrodes in molten calcium chloride (CaCl2) was analyzed by combining electroanalytical techniques with X-ray photoelectron spectroscopy. During a cyclic voltammetry (CV) scan, the oxide ions appear to interact with the tungsten working electrode via a multi-step oxidation and reduction process. The overall redox peaks behave reversibly up to 750 mV s−1. This electrochemical process enables the oxide ion concentration to be correlated to CV oxidation peaks. The resulting correlation agrees well (8.8% difference) with back titration measurements and can be used to monitor oxide content in the salt in real-time during CaCl2 based pryoprocesses.

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Section: Resultssupporting

confidence: 87%

mentioning

confidence: 99%

Electroanalytical Measurements of Oxide Ions in Molten CaCl₂on W electrode

Zhang

Rappleye

Nelson

et al. 2021

J. Electrochem. Soc.

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“…For the electrolytic tungsten from solid precursors, scheelite is a more proper feedstock than solid WO 3 due to the significant loss of WO 3 from the cathode due to the formation of highly volatile WO 2 Cl 2 in molten CaCl 2 . 23,24 The simultaneous electrodeoxidation and de-calcification of scheellite in molten CaCl 2 for the electrolytic preparation of tungsten can be expressed as Reaction (9a). As displayed in Fig.…”

Section: Simultaneous Electro-deoxidation and De-calcificationmentioning

confidence: 99%

The electrochemical reduction processes of solid compounds in high temperature molten salts

2014

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Solid electrode processes fall in the central focus of electrochemistry due to their broad-based applications in electrochemical energy storage/conversion devices, sensors and electrochemical preparation. The electrolytic production of metals, alloys, semiconductors and oxides via the electrochemical reduction of solid compounds (especially solid oxides) in high temperature molten salts has been well demonstrated to be an effective and environmentally friendly process for refractory metal extraction, functional materials preparation as well as spent fuel reprocessing. The (electro)chemical reduction of solid compounds under cathodic polarizations generally accompanies a variety of changes at the cathode/melt electrochemical interface which result in diverse electrolytic products with different compositions, morphologies and microstructures. This report summarizes various (electro)chemical reactions taking place at the compound cathode/melt interface during the electrochemical reduction of solid compounds in molten salts, which mainly include: (1) the direct electro-deoxidation of solid oxides; (2) the deposition of the active metal together with the electrochemical reduction of solid oxides; (3) the electro-inclusion of cations from molten salts; (4) the dissolution-electrodeposition process, and (5) the electron hopping process and carbon deposition with the utilization of carbon-based anodes. The implications of the forenamed cathodic reactions on the energy efficiency, chemical compositions and microstructures of the electrolytic products are also discussed. We hope that a comprehensive understanding of the cathodic processes during the electrochemical reduction of solid compounds in molten salts could form a basis for developing a clean, energy efficient and affordable production process for advanced/engineering materials.

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“…2MoO 3 (k)+CaCl 2 (s)=CaMoO 4 (k)+MoO 2 Cl 2 (g) (1) Benzer bir problem tungsten oksitten tungsten metali üretiminde de mevcuttur. Tungsten özelinde, reaksiyonda WO 3 yerine CaWO 4 kullanılmasıyla ağırlıkça en az %99 saflıkta tungsten eldesi baĢarı ile gerçekleĢmiĢtir [11,12]. Yöntem, Kanada, Rusya ve Türkiye olmak üzere 3 farklı ülkede korumaya alınarak patentlenmiĢtir [13][14][15].…”

Section: Introductionunclassified

Katı Molibden Bileşiklerinin Elektrokimyasal İndirgenmesiyle Molibden Üretimi

Erdogan¹,

Akpinar²,

Karakaya³

2017

Çukurova Üniversitesi Mühendislik-Mimarlık Fakültesi Dergisi

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ÖzĠletken bir telin ucuna tutturulmak suretiyle hücrenin katodunu oluĢturan, molibden bileĢikleri; CaMoO 4 ve MoS 2 'nin elektrokimyasal yöntemlerle indirgenmesi incelenmiĢtir. Elektrolit olarak, erimiĢ haldeki CaCl 2 -NaCl tuz çözeltileri kullanılmıĢtır. Ġndirgenen örneklerin içeriği ve morfolojisi X-ıĢınları kırınımı (XRD) ve taramalı elektron mikroskobu (SEM) analizleri aracılığıyla belirlenmiĢtir. Molybdenum Production by the Electrochemical Reduction of Solid Molybdenum Compounds AbstractThe electrochemical reduction of molybdenum compounds; CaMoO 4 and MoS 2 , which form the cathode of the cell by being attached to a current collector, was investigated. Molten CaCl 2 -NaCl salt solutions were used as the electrolyte. The compositions and morphologies of the reduced samples were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The examinations showed that it is not possible to produce Mo without loss by the electrochemical reduction of CaMoO 4 . The aforementioned compound has around 1.9% solubility in eutectic CaCl 2 -NaCl salt solution at 750 o C. Formation of Mo was not observed at 600 o C where the solubility was relatively not important. On the other hand, production of molybdenum from MoS 2 , which is the most important Mo mineral found in nature, was accomplished successfully. Pure molybdenum powder was obtained by the dissolution of calcium products found in the reduced samples in dilute acid solution.

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On the Electrochemical Reduction Mechanism of CaWO4 to W Powder

Cited by 17 publications

References 8 publications

Electroanalytical Measurements of Oxide Ions in Molten CaCl₂on W electrode

Electroanalytical Measurements of Oxide Ions in Molten CaCl₂on W electrode

The electrochemical reduction processes of solid compounds in high temperature molten salts

Katı Molibden Bileşiklerinin Elektrokimyasal İndirgenmesiyle Molibden Üretimi

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On the Electrochemical Reduction Mechanism of CaWO4 to W Powder

Cited by 17 publications

References 8 publications

Electroanalytical Measurements of Oxide Ions in Molten CaCl2on W electrode

Electroanalytical Measurements of Oxide Ions in Molten CaCl2on W electrode

The electrochemical reduction processes of solid compounds in high temperature molten salts

Katı Molibden Bileşiklerinin Elektrokimyasal İndirgenmesiyle Molibden Üretimi

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Electroanalytical Measurements of Oxide Ions in Molten CaCl₂on W electrode

Electroanalytical Measurements of Oxide Ions in Molten CaCl₂on W electrode