Journal of the Electrochemical Society p. 2126 - 2131 (1990)
Update date:2022-08-16
Topics:
Piron
Masse
Berube
Laboratory-scale experiments of zinc electrowinning under periodical reverse current (PRC) were carried out in acidic sulfate solutions. To study the effects of lead impurities on the zinc cathode, 0.3-15 mg/l of lead were added to the electrolyte. A square wave of current was used to produce the PRC. Current densities of 500 and 1500 A/m2 were investigated under both direct current and PRC. In the case of PRC, the direct and reverse pulses had respective durations of 100s and 0.1-1.0s. The current density of the reverse pulse was set at half the value of the direct pulse. Comparisons were 93.2%, while in PRC it raised it from 93.2 to 97.6%, using a reverse pulse duration of 0.1s. Correlation between the current efficiencies and the presence of the crystallographic plane (101) was also observed. It suggests that lead in the zinc deposit and the use of PRC influence the crystallographic growth of the zinc deposit. The presence of plane (101) increases the overpotential of hydrogen evolution on zinc, and this results in a higher current efficiency. A way of obtaining the beneficial plane is to use PRC and lead in the electrolyte together.
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