Wetting Between Carbon and Cryolitic Melts. Part II: Effect of Bath Properties and Polarisation

Solheim, Asbjørn; Gudbrandsen, Henrik; Martínez, Ana María; Einarsrud, Kristian Etienne; Eick, Ingo

doi:10.1007/978-3-319-48248-4_113

Cited by 4 publications

(6 citation statements)

References 4 publications

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“…Figure 10c shows raw data of step 4. The change in the meniscus length is apparent also in step 4 and this suggests that the change in wetting seen after polarization is permanent due to adsorbed species on the anode surface as suggested by Solheim et al 33 Figure 11 shows corrected weight, m m -m t , of the sample during immersion where the weight in gas and the buoyancy effect (m t ) has been subtracted from the recorded weight (m m ) as described in Equation 6. The corrected weight is calculated from the raw data shown in Fig- ure 10c.…”

Section: Resultsmentioning

confidence: 71%

“…melt.-An in-house made apparatus 32,33 was used for investigating the wetting properties of carbon anode samples toward cryolitic melts before and after polarization. The set-up was designed to measure the weight of samples during immersion/emersion in an electrolyte.…”

Section: Wetting Properties Of Polarized Anode Samples In a Cryoliticmentioning

confidence: 99%

“…The wetting properties of the anodes were studied under electrochemical polarization by the immersion-emersion technique. 32,33 In situ electrolyte-anode wetting interactions were also characterized by capacitance measurements. In this manner, the voltage oscillations due to bubble formation could be correlated to the various anode properties and in particular the role of the material vs. the role of the porosity.…”

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confidence: 99%

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Comparing Anodic Bubble Behavior of Anodes from Anisotropic and Isotropic Cokes in Laboratory Scale Aluminum Electrolysis Cells

Sommerseth

Thorne

Ratvik

et al. 2019

J. Electrochem. Soc.

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During production of aluminum in Hall-Héroult cells, carbon anodes electrochemically oxidize to form mainly CO2. The CO2 bubbles block the anode working surface during growth and coalescence, leading to cell voltage loss and voltage oscillations. Lower grade isotropic petroleum cokes are currently being introduced to anodes worldwide, but little is known about effects of coke quality on the unavoidable voltage losses linked to bubble formation. To investigate this, a pilot carbon anode series was made with various blended ratios of isotropic to anisotropic coke. The anodes were characterized with respect to voltage oscillations related to bubble formation and release, wettability towards electrolyte and surface roughness before and after electrolysis. Results showed that voltage noise caused by gas bubbles was reduced for anodes containing isotropic coke. For blended anodes of isotropic and anisotropic coke, the potential oscillation amplitude was reduced by ~0.19 V compared to a 100 % anisotropic coke anode. The percentage of the anode surface screened by gas bubbles was also reduced as isotropic coke was introduced. Increased wettability between electrolyte and two anodes containing isotropic coke was observed after anode polarization. The reduced bubble screening on the anode surface was attributed to better wetting between anode and electrolyte.

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Section: Resultsmentioning

confidence: 71%

Section: Wetting Properties Of Polarized Anode Samples In a Cryoliticmentioning

confidence: 99%

mentioning

confidence: 99%

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Comparing Anodic Bubble Behavior of Anodes from Anisotropic and Isotropic Cokes in Laboratory Scale Aluminum Electrolysis Cells

Sommerseth

Thorne

Ratvik

et al. 2019

J. Electrochem. Soc.

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show abstract

“…Solheim et al [21] and Åsheim et al [22] used an immersion-emersion technique to measure wetting between carbon and cryolite. It was found that the polarization strongly improved wetting for the melt low in alumina (1 wt% Al 2 O 3 ), and the wetting increased with increased polarization.…”

Section: Wetting Of the Horizontal Anodementioning

confidence: 99%

“…Since the alumina concentration was 3 wt%, the bath is close to saturation. Solheim et al [21] observed in a bath with high alumina concentration (8 wt%) that polarization did not affect wetting significantly since the increase in alumina concentration changed the wetting of carbon by cryolite from non-wetting to good wetting. However, the actual alumina concentration might be as important as the degree of saturation.…”

Section: Wetting Of the Vertical Anodementioning

confidence: 99%

Bubble Phenomena and Bubble Properties for Horizontal and Vertical Carbon Anode Surfaces in Cryolite Melt Applying a See-Through Cell

Stanic

Martínez

Einarsrud

et al. 2021

Metals

Self Cite

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Gas bubble behavior on a carbon anode in a cryolite melt has been studied using a see-through cell. The phenomena studied have been growth, coalescence, detachment, and wetting during electrolysis. The surface orientation affects bubble behavior. Therefore, two different anode designs were tested, an anode with a horizontal downward-facing surface and an anode with a vertical surface. At the horizontal anode, it was found that one large bubble was formed by the growth and coalescence of smaller bubbles, and finally, the large bubble detached periodically. For the vertical anode surface, the detaching bubbles were smaller, and most of them had been going through a coalescence process prior to detachment. The bubbles detached randomly. The coalescence process from the initiation to the final bubble shape at the vertical surface took about 0.016–0.024 s. The current density did not affect the duration of the coalescence. The bubble diameter was decreasing with increasing current density for both anodes. The values were in the range 7.2 to 5.7 mm for the horizontal anode in the current density interval 0.2–1.0 A cm−2 and in the range 3.7 mm to 1.5 mm for the vertical anode in the current density interval 0.1–2.0 A cm−2. The wetting contact angle for the vertical anode stayed more or less constant with an increase in current density, which likely can be attributed to the decreasing bubble size rather than an increase in polarization. In addition to the bubble phenomena described and bubble properties found, the impact of the results for better design of laboratory-scale studies is discussed.

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The Impact of Bubble‐Bubble Interaction on Anodic Gas Release: A Water Model Analysis

Simonsen¹,

Einarsrud²,

Eick³

2015

Light Metals 2015

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Wetting Between Carbon and Cryolitic Melts. Part II: Effect of Bath Properties and Polarisation

Cited by 4 publications

References 4 publications

Comparing Anodic Bubble Behavior of Anodes from Anisotropic and Isotropic Cokes in Laboratory Scale Aluminum Electrolysis Cells

Comparing Anodic Bubble Behavior of Anodes from Anisotropic and Isotropic Cokes in Laboratory Scale Aluminum Electrolysis Cells

Bubble Phenomena and Bubble Properties for Horizontal and Vertical Carbon Anode Surfaces in Cryolite Melt Applying a See-Through Cell

The Impact of Bubble‐Bubble Interaction on Anodic Gas Release: A Water Model Analysis

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