Voltammetric Study on the Electrowinning of Cobalt in the Presence of Additives

Cobalt electrowinning is an intensive energy-consuming process, and allied to the increasing demand for pure cobalt, has led to the need for optimization. Based on a statistical approach, the effects of additives, including sodium lauryl sulfate (SLS), boric acid (H₃BO₃), and cobalt chloride (CoCl₂) on the current efficiency of electrowinning have been studied using the cyclic voltammetry (CV). CV tests indicated the concentration range of the more appropriate additives to be used in the factorial design study of electrowinning. Regarding the electrowinning tests, the addition of 0.05 g L^-1 SLS, 10 g L^-1 H₃BO₃, 50 g L^-1 Na₂SO₄, and 1 g L^-1 CoCl₂ led to a current efficiency of 96% and energy consumption of 1.95 kWh kg^-1, along with a smooth metallic deposit without evident pits and other defects. SLS in its higher concentration level led to the formation of compact structures, while the higher concentration level of H₃BO₃, lightens the deposits.

Keywords:
cyclic voltammetry; electrowinning; cobalt metal; additive