Influence of nickel on cathode process of zinc electrowinning

The influence of Ni2 + on the cathode polarization process and the kinetics equation and its parameters in zinc electrowinning has been investigated in this paper. When [Ni2 +] < 4 mg L− 1, the limiting current density increases with increasing Ni2 + concentration up to a maximum where [Ni2 +] = 4 mg L− 1. This indicates the depolarization of nickel in zinc electrowinning. The limiting current density decreases and the passivation point gradually disappears owing to the polarization function of nickel when [Ni2 +] > 4 mg L− 1. In addition, the presence of Ni2 + decreases the current efficiency and worsens the surface morphology in the zinc electrowinning process.

► The limiting current density is a maximum when [Ni2 +] = 4 mg L– 1.
► The phenomenon of “cathode deposit resolution” occurs in the presence of Ni2 +.
► The CE decreases when Ni2 + increases especially over long electrowinning periods.