Electrochemical studies of the effect of TiO2 and B2O3 additions on the aluminium deposition reaction in the molten cryolite bath

Raj, S.C.; Skyllas‐Kazacos, Maria

doi:10.1016/0013-4686(92)85082-v

Cited by 11 publications

(4 citation statements)

References 6 publications

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“…These reactions were assumed to be due to deposition and oxidation of aluminium. The peak potential separation indicated that the n value was close to 3, which suggests that titanium is deposit-ed according to Ti (III) (diss) + 3 e − → Ti (s) (10) The cathodic current increase at more anodic potentials was then assumed to be due to the following reaction Ti (IV) (diss) + e − → Ti (III) (diss)…”

Section: Methodsmentioning

confidence: 99%

Electrochemical Behaviour of Dissolved Titanium Oxides during Aluminium Deposition from Molten Fluoride Electrolytes

Haarberg

2017

Mater. Trans.

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A small but signi cant amount of dissolved titanium is always present in the molten cryolite based electrolyte used during electrowinning of aluminium. The fact that titanium can appear in several oxidation states may be a cause for reduced current ef ciency for aluminium, although codepositon of titanium should be thermodynamically favoured. Voltammetric studies were carried out in molten Na 3 AlF 6 -Al 2 O 3 (sat) containing TiO 2 at 1020 C. The results suggested that titanium was reduced in two steps from Ti (IV) to Ti (III) followed by reduction of Ti (III) to Ti metal.Experiments were also carried out in industrial aluminium cells. Large quantities of TiO 2 were added to the electrolyte during electrolysis, and samples of electrolyte and produced metal were taken and analysed as a function of time after addition. The results suggested that titanium was codeposited at the aluminium cathode by a diffusion controlled reaction. The apparent current ef ciency for titanium deposition was estimated to be higher than 90%.The valency problem seems to be less challenging when depositing liquid titanium alloys from molten uoride electrolytes. This approach may give rise to the development of production of a valuable titanium containing alloy TiAl 3 . [

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Section: Methodsmentioning

confidence: 99%

Electrochemical Behaviour of Dissolved Titanium Oxides during Aluminium Deposition from Molten Fluoride Electrolytes

Haarberg

2017

Mater. Trans.

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“…Ray [29] discovered that small additions of TiO2 and B2O3 to the cryolite-based melt (Na3AlF6-Al2O3-CaF2) at about 1000 °С increase the wettability of the graphite electrode by molten aluminum due to formation of Al-Ti or Al-B alloys on the graphite surface. Moreover, the Al-B alloy improves the wettability of graphite more efficiently.…”

Section: Introductionmentioning

confidence: 99%

Borated graphite cathodes for low-temperature aluminum electrolysis

2022

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Electrochemical boriding of the graphite plates in the potassium cryolite based electrolytes was studied. The boriding were carried out in a cell with vertical electrodes. The procedure included 2 stages: 1) electrolysis in the KF–AlF3–KBF4 melt (CR=1.3) at low current density (0.01–0.02 A/cm2), required for the boron reduction, at 700 and 750 °C; 2) electrolysis in the KF–AlF3–Al2O3 melt at higher current density (0.2 A/cm2), required for the aluminum reduction. The optimal conditions of electrodeposition for obtaining the borated wettable cathodes were determined. According to the SEM data, a continuous AlB2 layer with a thickness of 7–10 μm was formed on the graphite surface. The borated graphite was tested as a wetted cathode during the low-temperature aluminum electrolysis. Prolonged electrolysis in a vertical cell with the graphite anode and the borated graphite cathode was carried out in the KF–NaF(10 wt.%)–AlF3–Al2O3 electrolyte (CR=1.5) at 830 °C. After 100 h of electrolysis, the thickness of the AlB2 layer on the graphite surface was 5 μm, while the cathode surface was completely wetted with aluminum. Thus, we demonstrated the feasibility of using the borated graphite cathode as a wettable dripping cathode in the low-temperature aluminum electrolysis in the vertical cell.

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“…Для получения лигатуры Al-B наибольшее распространение получил метод алюмотермического восстановления борсодержащих соединений как прямым сплавлением компонентов [2][3][4][5][6][7][8][9][10][11][12], так и с использованием солевых флюсов [13].…”

Section: Introductionunclassified

Production of the Al–B master alloy by KBF4and B 2O3aluminothermic reduction in molten salt flux medium

Катаев

Молчанова

Zaikov

2019

Izv.VUZ. Tsvet. Met.

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The study covers the process of obtaining the Al–B master alloy by the KBF4and B2O3aluminothermic reduction using KF–AlF3and KF–NaF–AlF3fluoride fluxes at 983 and 1123 К, respectively, and KCl–NaCl–KF chloride-fluoride fluxes at Т= 1173÷1223 К. All experiments were carried out under the same conditions: molten mixture stirring rate was 400 rpm, synthesis duration was 30min. The maximum amount of boron (1,5 %) in the Al–B alloy was obtained when using KBF4(3 % per B) as a boron-containing raw material in the KF–AlF3medium with a molar (cryolite) ratio (CR) of KF/AlF3equal to 1,3, atТ= 983 К, while boron recovery ratio did not exceed 75 %. Comparable results were obtained in experiments with KF–NaF–AlF3f lux (CR = 1,5) at Т= 1123 К. However, with the increased concentration of fed boron its recovery ratio decreased substantially. It is connected with the higher decomposition temperature of not only KBF4, but also less thermally stable NaBF4 formed as a result of exchange reaction in the melt. Therefore it is not recommended to use sodium salts as a f lux component. The Al–B master alloys obtained by KBF4reduction in fluoride fluxes were solid solutions of B in Al containing the AlB2intermetallic compound. The lowest amount of boron in aluminum with the minimum degree of extraction was obtained in experiments with the B2O3in molten KF–AlF3with CR = 1,5. Nevertheless, the results of scanning electron microscopy indicate a uniform distribution of B over the Al matrix and the absence of intermetallic compounds, while a large amount of Al2O3was found, which is the product of B2O3reactions with both liquid Al and KF–AlF3flux.

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Electrochemical studies of the effect of TiO2 and B2O3 additions on the aluminium deposition reaction in the molten cryolite bath

Cited by 11 publications

References 6 publications

Electrochemical Behaviour of Dissolved Titanium Oxides during Aluminium Deposition from Molten Fluoride Electrolytes

Electrochemical Behaviour of Dissolved Titanium Oxides during Aluminium Deposition from Molten Fluoride Electrolytes

Borated graphite cathodes for low-temperature aluminum electrolysis

Production of the Al–B master alloy by KBF4and B 2O3aluminothermic reduction in molten salt flux medium

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