Solid phase formation during aluminium electrolysis

• Published in: Electrochemistry communications 2020-01, Vol.110, p.106624, Article 106624
• Main Authors: Tkacheva, Olga, Arkhipov, Pavel, Zaykov, Yury
• Format: Article
• Language: English
• Subjects: Alumina; Bottom ledge; Cryolite-alumina melt; Electrolysis; Electrolyte crust; Side ledge
• ISSN: 1388-2481; 1873-1902
• DOI: 10.1016/j.elecom.2019.106624

•The side ledge does not form at the electrolyte overheating by ≥18 °C.•The bottom ledge thickness is noticeably smaller than that of side ledge at the higher electrolyte motion rate.•Heat flow has a great influence on the thickness of the side and bottom ledges.•Changes in the heat flow result in the increase in the electrolyte crust thickness. The paper illustrates the results of experimental study on the formation of the solid phase on the graphite crucible wall in the cryolite-alumina electrolyte depending on the temperature, rates of the liquid phase motion and heat flow in the laboratory electrolytic cell. The side ledge stability is shown to depend on the rate of the heat flow, which is caused by changes in the temperatures of the electrolyte, electrolytic cell walls and liquidus. When the temperature of the inside wall is higher than the electrolyte liquidus temperature the side ledge does not form, but in the case when it is lower than the liquidus temperature the side ledge formation proceeds until the temperatures equalize. As the electrolyte motion rate increases the thickness of the bottom ledge exceeds the thickness of the side ledge. The changes in the heat resistance of the electrolytic cell walls have a significant influence on the crust growth over the electrolyte and have less influence on the thickness of the bottom and side ledges.