The Impact of Mn2+ ions Concentration on Co-electrowinning Using a Dimensionally Stable Anode (Ti/RuO2): Effects on Physical and Chemical Properties

Metallic cobalt is valued for its thermal and corrosion resistance. In 2018, cobalt prices surged to 95,250 USD/t, fueled by the growing electric vehicle market. However, metallurgical challenges persist, including cost reduction and impurity control. Manganese, a frequent impurity in cobalt electrowinning from laterite and copper ores, can reach up to 560.6 mg·L−1 in leach solutions. Though solvent extraction removes ~90% of manganese, residual amounts impact current efficiency (CE), specific energy consumption (SEC), and deposit quality. Electrowinning tests at 200 A·m−2, 60°C, and pH 4 showed that 0.12 g·L−1 Mn2+ increased CE to 92.2% but raised SEC to 1.96 kWh·kg−1. Mn2+ altered deposit morphology, reducing microhardness and increasing brittleness. Thermogravimetric analysis revealed ~1.35% mass loss in deposits with Mn2+, while higher concentrations enhanced residual strain and enlarged crystallite sizes. Deposits exhibited primarily hexagonal close-packed (HCP) structures with occasional face-centered cubic (FCC) phases.