Field study of the anodic overvoltage in prebaked anode cells

Abstract

The anodic overvoltage in aluminum electrolysis represents 10 15% of the total cell voltage, and possible means of reducing the overvoltage should then be studied. In the present work the anodic overvoltage was measured in two prebake cells, 180 kA and 235 kA, the latter having some anodes with slots, and in one 145 kA HSS cell. A special reference electrode was used. At normal current densities the overvoltage varied from 0.72 V at 5 wt% Al 2O3 to 0.86 V at 2 wt%. At comparable anodic current densities and alumina concentrations, the overvoltage for the anodes with one transverse 1.5 cm groove were 0.11 V less than for the conventional anodes. For the HSS cell the overvoltage was similar.