A novel porous Pb–Ag anode for energy-saving in zinc electrowinning: Part II: Preparation and pilot plant tests of large size anode

A new method for the preparation of large size porous anodes has been developed, called counter-gravity infiltration; and four kinds of porous Pb–Ag anodes with different pore sizes were prepared. The anodes were tested in a pilot plant for 24 days with the electrolyte drawn from the zinc electrowinning plant. The results show little impact on the electrowinning system. However, the weight of the porous anode was 60% less than the flat plate anode; the corrosion rates were only one-fifth of the flat plate anode; and the pass rate of cathode zinc almost reached 100%. The cell voltages associated with each porous anode were lower than the flat plate anode with no difference in current efficiencies. This reduced the energy consumption by up to 78 kWh/t-Zn for the porous anode with a pore size of 1.6–2.0 mm.