Advances in iron and manganese removal technologies for sustainable copper-cobalt hydrometallurgy

The global adoption of new energy vehicles has expanded rapidly in recent years, driving intensified use of cobalt in lithium battery technologies. This trend has triggered a substantial rise in worldwide demand for both cobalt resources. Therefore, cobalt recycling is crucial for sustainable resource management and environmental protection. The presence of impurities, such as iron and manganese, adversely affects the subsequent recovery and application of cobalt. This paper examines technologies and methods for removing these impurities prior to cobalt recovery. It systematically analyzes various iron removal techniques and discusses recent developments, and evaluates their economic feasibility in terms of capital investment, operating costs, and environmental risks. Among iron removal methods, the jarosite process demonstrates higher cost-effectiveness for industrial-scale applications, while the hematite process requires stringent operational conditions. Additionally, it compares and evaluates manganese removal technologies, such as precipitation, ion exchange, electrolysis, and extraction methods. Moreover, this paper presents other treatment methods that can remove and separate iron and manganese simultaneously: neutralization precipitation and SO₂/O₂ oxidative precipitation. The SO₂/O₂ oxidative precipitation method offers a simplified and eco-friendly alternative to conventional techniques. The paper also addresses cobalt precipitation techniques, including primary cobalt deposit and secondary cobalt deposit, pressurized ammonia distillation, and liquid-phase reduction precipitation. In general, this paper summarizes the various methods of iron and manganese removal, and analyzes the limitations and future trends, this provides new insights for advancing iron and manganese removal technologies in cobalt hydrometallurgy.