National Research Development Corporation

Robert P Leetham

Francis Goodridge

Raymond E Plimley

An electrolyte containing 65 g/l zinc and 150 g/l Cu is purified in zinc, that is, the copper is removed, by causing the electrolyte to fluidize a bed 8 of 1/2 mm copper particles. The bed is fluidized by 25% to make it 42 cm deep. An anode 11 is disposed above the top of the bed. A cathode 9 is disposed part-way up the bed. Copper is electroplated onto the bed particles. Any zinc which may be electroplated onto the bed particles tends to redissolve with concomitant cementation, on the particles, of copper, which can be recovered. The electrolyte is thus eventually completely stripped of copper and can be used for zinc electrowinning. By controlling the pH of the electrolyte, substantially one metal, or one desired combination of metals, may be removed. In particular, pure copper deposition can be completed at low pH even in the presence of cadmium; upon a substantial increase in pH, cadmium deposition will occur.

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Broadway, United Kingdom

Robert P Leetham