FULL-SCALE HYDROGEN ANODES FOR IMMERSED-TANK ELECTROWINNING

Full-scale (1.2 m2) immersed-tank hydrogen-diffusion anodes have been prepared by a newly patented lamination technique onto metallic sheet substrates. The use of such free-standing electrodes has been characterized in the electrowinning of zinc, but the electrodes are also suitable for use in the electrowinning of other metals and in electroplating. The electrodes may find application in processes where voltage savings of approximately 1.8-2.0 V versus oxygen evolution are of importance, or where parasitic anodic oxidations need to be eliminated. The hydrogen-diffusion anode structure developed incorporates a novel microporous polymeric coating designed to prevent both the percolation of feed hydrogen through the electrode to the electrolyte and the seepage of electrolyte into the gas plenum.