Development of a rapid measurement of current efficiency in the electrowinning of zinc

A method for the rapid measurement of current efficiency for the deposition of zinc by a computer controlled anodic stripping technique has been successfully developed and evaluated in the laboratory and in a zinc tankhouse. This method provides rapid measurement of the efficiency within about 3 min from 1 to 2 L of electrolyte at a fixed temperature. Minimum preparation time is involved as the pure lead wire cathode surface can be easily renewed by simply cutting the coated wire to expose a new surface. Reproducible results have been achieved which compare very favourably with those obtained by longer term conventional methods. It has been demonstrated that the technique can also prove to be useful as a convenient method for the study of cathode morphology and for the nature of the potential/time transients during nucleation and growth of zinc deposits under various conditions. Thus, the effects of the concentrations of various impurities such as selenium, antimony and cobalt on the current efficiency and the morphology of the zinc deposits have been studied. The effects of the addition of additives such as glue and gelatine have similarly been evaluated. The results have been shown to be consistent with published data.