A preliminary investigation of some anod

The development of fluidized-bed electrowinning for copper and other metals appears to be impeded by the high electrical energy consumption associated with the anodes used in such electrowinning. This paper describes preliminary work aimed at seeking anodes which consume less energy and are suitable for scale-up. Using laboratory-scale cells in which copper was electrowon from strong (25 g dm–3 Cu), acidified (100 g dm–3 H2SO4) sulphate solutions on to fluidized cathodes, various anodes were tested. Among these were fluidized-bed anodes of catalyst-coated titanium particles, packed-bed anodes of lead shot and graphite, and various configurations of titanium mesh and cloth-covered anodes. The investigation included alternative anode reactions, such as oxidation of sulphur dioxide, ferrous ions or cuprous ions. Results indicated that except for the fluidized anode and the lead packed-bed anode, all tested systems yielded significant energy savings. Notably, the electrowinning from cuprous solutions with cuprous oxidation on a graphite packed-bed anode offered an energy consumption of 2.0 kWh kg–1 Cu, which was more efficient than conventional electrowinning methods.