Motion dynamics of anodic gas in the cryolite melt–alumina high-temperature slurry

Abstract

The results of physical simulation of the behavior of bubbles formed due to the electrochemical evolution of oxygen on an inert anode during the high-temperature electrolysis of alumina slurry in the fluoride melt are presented. Similarity criteria are calculated, the experiments for a water model with vertically oriented electrodes are performed, and the data on the behavior of bubbles in the slurry are found with the help of video recording. The 20% aqueous solution of sulfuric acid with an alumina content of 30 vol % was used as the model electrolyte. The experiments were performed in a range of current densities from 0.05 to 0.25 A/cm2. Video was recorded using a Nikon D3100 camera with a recording frequency of 30 frames/s. The data on the motion dynamics of the bubbles, the quantitative data that characterize coalescence, and the bubble lifting velocity are found. To determine the average lifting velocity, 125 bubbles were analyzed. They were 0.8–2.3 mm thick. The bubble motion is performed in the slug regime with lifting velocity of 1.0–2.3 cm/s. The bubble layer thickness was about 5 mm. Further investigations will be directed to finding new data on the behavior of bubbles for various solid phase contents, current density, electrode slope angle, and granulometric composition.