Polyacrylamide flocculating agent has been used in the Leaching Division of the Risdon Works of the Electrolytic Zinc Co. of Australasia Ltd since October, 1960. Since the introduction, the.: number of thickeners in use in the continu- ous thickening stage has been reduced from eight to three; there has been an increase of 25% in throughput and a reduc- tion of solids in.:thickener overflow from 3-4 gpl . solids to 0.5 g.p.l. solids. Reagent addition has been at the rate of 0.25. lb SEPARAN, NP10 per ton solids._x000D_
Additionally there has been a gain of 3% in current efficiency as the direct result of the addition of SEPARAN NP10 to purified cadmium sulphate solution prior to electrolysis for cadmium metal. A smoother deposit has resulted and it has been possible to increase deposition time between strip- pings from 47 to 71 hours. However, there has been a slight increase the lead content of the cadmium-metal produced.