Aluminium dissolution in the NaF-AlF3-Al2O3 system: Effects of alumina, temperature, gas bubbling and dissolved metal

Sum, E.; Skyllas‐Kazacos, Maria

doi:10.1007/bf01022103

Cited by 8 publications

(5 citation statements)

References 3 publications

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“…Dissolution rate depends on the ionic structure of the medium, so the increase in CR leads to the rise of the dissolution rate. This is in a good agreement with previous results for both low-melting and commercial electrolytes [3,6,32]. Dissolution rate depends on the dissolved alumina concentration in the melt at higher CR and temperature even at low concentrations (0-2 wt.%).…”

Section: Dissolutionsupporting

confidence: 92%

“…It is well known that the gas generation during the oxidation of carbon eliminates the agglomeration of alumina in the melt [25,26]. The alumina-feeding rate has importance and plays a key role in avoiding the agglomeration of the alumina particles in the melt when fed [27].…”

Section: Fig 1 -The Scheme Of Suspension Electrolysis Apparatusmentioning

confidence: 99%

“…The dissolution mechanism and kinetics in sodium cryolite are studied and reported elsewhere [3][4][5][6][7]. Alumina is believed to be dissolved in the commercial electrolyte by one or several of the following mechanisms [8,9]:…”

Section: Introductionmentioning

confidence: 99%

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Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions

Yasinskiy

Suzdaltsev

Polyakov

et al. 2020

Ceramics International

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The article addresses the properties of melts and alumina suspensions based on the molten KF-AlF 3 -Al 2 O 3 system, the kinetics of alumina dissolution and the rheological properties that determine the sedimentation stability. The study of such suspensions has become topical due to the prospects of their use as electrolytes in the production of aluminium using carbon-free anodes. The effects of the temperature, the particle size and the phase composition of the dispersed material and its volume fraction in the suspension on the dissolution kinetics and the sedimentation velocity are studied. The experiments were carried out over the melts with cryolite ratios 1.3 and 1.5 in the range of 750-850 °C. Three different types of aluminium oxide were used. The Reynolds numbers for sedimentation have indicated the Stokesian regime. Typical alumina dissolution rates were in the range 0.028-0.167 g•kg -1 •s -1 , which is close to the values reported previously. Sedimentation velocities were in the range (0.05-3.61)•10 -2 m/s, which is several times higher than those obtained previously for 700 °C and φ = 0.24-0.32. It is shown that mechanical activation of alumina increases the performance of the suspension in terms of the sedimentation stability and the dissolution rate increasing.

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Section: Dissolutionsupporting

confidence: 92%

Section: Fig 1 -The Scheme Of Suspension Electrolysis Apparatusmentioning

confidence: 99%

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Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions

Yasinskiy

Suzdaltsev

Polyakov

et al. 2020

Ceramics International

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“…Furthermore, as the concentration of aluminum-containing complex ions varies with the molar ratio of NaF to AlF 3 in the melt, the cryolite ratio of Na 3 AlF 6 -Al 2 O 3 -LiF system surely has some effects on the aluminum deposition and alloying effect. A series of researches [22][23][24][25] already gave about the current efficiency and aluminum dissolution loss in cryolite-aluminum oxide molten salt at tungsten electrode by means of cyclic voltammetry and chronopotentiometry years ago, and introduced reliable theoretical principles for the current aluminum electrolysis as well. However, most of previous studies just focus on the cryolite-aluminum oxide molten salt system, and the electrochemical measurement methods are single.…”

Section: Introductionmentioning

confidence: 99%

Cathodic electrochemical behavior in Na3AlF6-Al2O3-LiF-based melts at tungsten electrode with various cryolite ratios

Tao

Peng

et al. 2014

Rare Met.

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The cathodic behavior at tungsten electrode in Na 3 AlF 6 -Al 2 O 3 -LiF-based melt with various cryolite ratios was investigated by means of potentiodynamic cathodic polarization, potentiostatic electrolysis, chronopotentiometry, and open-circuit chronopotentiometry. The results show that the formation process of Al-W intermetallic compound is controlled by both diffusion and charge transfer when the cryolite ratio is below 2.5, and is completely controlled by diffusion when cryolite ratio is above 2.5. The deposition process of metal aluminum is completely charge-transfer controlled. Sodium vapor releases along with the deposition of metal aluminum as crylite ratio increases, which leads to a great influence on current efficiency. When the cryolite ratio is lower than 2.0, the critical cathodic current density of deposited aluminum at tungsten electrode is about 150 mAÁcm -2 , but the current density is above 200 mAÁcm -2 under other experimental conditions. A higher cryolite ratio can cause a higher cathodic overvoltage. The relative content of Al layer is higher with the decrease of cryolite ratio, and Al layer easily strips into the molten salt when the cryolite ratio is higher than 2.5.

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“…Furthermore, the inuence of LiF on the electrode reaction process is rarely reported in the literature in cryolite-aluminum oxide molten salt, especially using electrochemical analysis. A series of research papers [28][29][30][31] have already investigated the current efficiency and aluminum dissolution loss in cryolite-aluminum oxide molten salt by means of cyclic voltammetry and chronopotentiometry years ago, and introduced reliable theoretical principles for the current aluminum electrolysis as well. However, most of the earlier studies just focused on the cryolitealuminum oxide molten salt system, and the electrochemical measurement methods were basic.…”

Section: Introductionmentioning

confidence: 99%

The influence of various LiF concentrations on the cathodic electrochemical behavior at the tungsten electrode in Na₃AlF₆–Al₂O₃ molten salt

Tao

Liu

et al. 2015

RSC Adv.

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The electrochemical deposition process of Al metal at the tungsten electrode in the melts of Na 3 AlF 6 -Al 2 O 3 with various LiF concentrations was investigated at 1253 K by various electrochemical techniques. With the analysis of the potentiodynamic cathodic polarization curves, it can be demonstrated that LiF has an effect of increasing the conductivity of the molten salt. From the analysis of the potentiostatic electrolysis and chronopotentiometry curves, it can be deduced that the deposition potential of Na metal is more positive with the increase of LiF concentration. Spontaneous dissolution of the cathodic products occurs for the polarized electrode which is shown by the measurements of open-circuit chronopotentiometry.These show that the scanning time taken for the potential to reach zero is prolonged and the thickness of the reduced species to be dissolved increases with the increase of LiF concentration. Furthermore, it can be deduced that the Al activity also increases with the increase of LiF concentration. On the other hand, the deposited Al is more easily dissolved into the electrolyte and the physical dissolution is more intense with the increase of LiF concentration.

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Aluminium dissolution in the NaF-AlF3-Al2O3 system: Effects of alumina, temperature, gas bubbling and dissolved metal

Cited by 8 publications

References 3 publications

Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions

Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions

Cathodic electrochemical behavior in Na3AlF6-Al2O3-LiF-based melts at tungsten electrode with various cryolite ratios

The influence of various LiF concentrations on the cathodic electrochemical behavior at the tungsten electrode in Na₃AlF₆–Al₂O₃ molten salt

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Aluminium dissolution in the NaF-AlF3-Al2O3 system: Effects of alumina, temperature, gas bubbling and dissolved metal

Cited by 8 publications

References 3 publications

Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions

Behaviour of aluminium oxide in KF-AlF3-Al2O3 melts and suspensions

Cathodic electrochemical behavior in Na3AlF6-Al2O3-LiF-based melts at tungsten electrode with various cryolite ratios

The influence of various LiF concentrations on the cathodic electrochemical behavior at the tungsten electrode in Na3AlF6–Al2O3 molten salt

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The influence of various LiF concentrations on the cathodic electrochemical behavior at the tungsten electrode in Na₃AlF₆–Al₂O₃ molten salt