Bubble behavior in aluminum reduction cell with inert anode

Abstract

The bubble behavior is one of the key factors for the design and the process of aluminum reduction cell using inert anode. A see-through cell is constructed to investigate the bubble flow behavior and the electrolyte flow pattern induced by bubbles. The test results show that the electrolyte is driven by the bubble to move around the cathode, and also some vortices occur in local areas. The bubble generated at the anode bottom undergoes the processes of formation, growth, sliding, detachment and coalescence. However, the bubble generated at the middle of anode detaches rapidly from the anode surface and moves upward and collides with other bubbles, which results in coalescence or break-up. Most bubbles are released into the atmosphere at the liquid surface, while some other bubbles taken by the electrolyte flush to the height higher than the mean horizontal level of the liquid and then drop down and move horizontally and they are released finally. Some bubbles are kept unbroken and are sliding on the electrolyte surface. The diameter of bubble generated at inert anode is smaller than that of bubble generated at graphite anode. Moreover, the bubbles on inert anode are spherical, which was different from those in tubular or disk form on graphite anode.

摘要

气泡的行为是惰性阳极铝电解槽设计和工艺控制必须考虑的重要因素。为了研究气泡的行为和 电解质的流动形态,构建了透明铝电解槽以进行观察。试验结果表明:受阳极气体的驱动,槽内电解 质围绕阴极作循环运动,并在局部区域形成旋涡。气体产生于阳极底掌和垂直工作面。在阳极底掌, 能够观察到气泡的形成、长大、滑移和脱离等现象。然而,阳极垂直工作面产生的气体则迅速脱离, 然后向上运动,途中与别的气泡碰撞,导致气泡的并聚或破碎。大部分气泡达到液面时立即逸出至空 气中,少部分气泡被冲出水平液面的电解质携带着继续向上运动,形成一个波峰,然后作水平运动并 最终逸出。在电解质表面,部分气泡能保持不破裂,并在电解质上滑动。通过对比分析,惰性阳极上 产生的气泡比石墨阳极上产生气泡的直径小。另外,石墨阳极上的气泡不呈球形,而呈圆盘状或扁平 状,惰性阳极上的气泡则近似呈球状。