DESIGN AND PERFORMANCE OF A LABORATORY CELL FOR DETERMINATION OF CURRENT EFFICIENCY IN THE ELECTROWINNING OF ALUMINUM

A new and improved laboratory cell has been specifically designed for determination of current efficiency (CE) as a function of isolated var iable parameters in the Hall-Heroult aluminium electrolysis process. T he anode is designed to give enhanced and reproducible bubble induced electrolyte convection, while the wettable cathode gives a well define d cathode area, and thus a uniform cathodic current density. Results a re given of CE and cathode polarization as functions of cathodic curre nt density, and of CE as a function of interpolar distance. Experiment s show reproducible and high values of CE, and low and consistent valu es of cathode polarization. The CE does not vary for interpolar distan ces between 10 and 40 mm in the present cell. The cell is well suited for experimental determination of CE as function of electrolyte compos ition, including impurity concentrations, temperature and current dens ity.