CURRENT DISTRIBUTION AT THE ELECTRODES IN ZINC ELECTROWINNING CELLS

The current distribution in zinc electrowinning cells was determined experimentally by weighing the deposited zinc and it was calculated using a mathematical model. The Laplace equation was solved for a two-dimensional cross section of the interelectrode space with boundary conditions corresponding to secondary current distribution. Good agreement was obtained between experimental and calculated data. The effect of changing the position of the cathode with respect to a fixed anode position was studied. When moving one cathode 50 mm in either direction, the current density at the end of the active width of the cathode varied from 20 to 180% of the average current density. In this case some current flows between this cathode and the second nearest anode. Setting a cathode at an angle with respect to the anode had only a minor effect on current distribution. Depending on the thickness of the insulating edge strips the cathodic current density in some cases exhibited minima close to the strips going from 90 to 130% on the average for 2 mm thickness while no significant variation occurred for a 15 mm strip. The most uniform cathodic current density was obtained when the end of the active cathode width extended 10 to 20 mm beyond the active width of the anode.