Design and performance of a laboratory cell for determination of current efficiency in the electrowinning of aluminium

A new and improved laboratory cell has been specifically designed for determination of current efficiency (CE) as a function of isolated variable parameters in the Hall-Heroult aluminum electrolysis process. The anode is designed to give enhanced and reproducible bubble induced electrolyte convection, while the wettable cathode gives a well defined cathode area, and thus a uniform cathodic current density. Results are given of CE and cathode polarization as functions of cathodic current density, and of CE as a function of interpolar distance. Experiments show reproducible and high values of CE, and low and consistent values of cathode polarization. The CE does not vary for interpolar distances between 10-40 mm in the present cell. The cell is well suited for experimental determination of CE as function of electrolyte composition, including impurity concentrations, temperature and current density.