Research Progress on Reductive Leaching Technology of Iron, Cobalt and Manganese Minerals

Objective In response to the problem that high-valent minerals of variable valence metals such as iron, cobalt and manganese are difficult to leach directly and the leaching efficiency is low in the hydrometallurgical process, a green and efficient reduction leaching technology is studied and developed to achieve comprehensive recovery and green resource utilization of valuable metals. Methods This article reviews the reduction leaching methods of iron, cobalt and manganese, including chemical reduction leaching, microbial reduction leaching and reduction calcination - leaching. The mechanism of action of the reducing agent was analyzed from the perspectives of thermodynamics and kinetics. Result The reduction leaching method can significantly increase the metal leaching rate. SO₂ reduction leaching can decompose zinc ferrate. Organic acids such as citric acid combined with reducing agents can increase the leaching rate of cobalt in used batteries from 75% to 99%. The selective leaching of nickel and cobalt can be achieved through reduction roasting - ammonia leaching or acid leaching processes. Reducing agents such as ferrous ions, hydrogen peroxide and biomass can increase the leaching rate of manganese in pyrolusite to over 90%. Conclusion Compared with pyrometallurgical processes, the reduction leaching method has advantages such as low energy consumption, low carbon emissions, high reaction efficiency, and environmental friendliness. It is an effective way to achieve green and efficient recovery of variable valence metals such as iron, cobalt, and manganese. However, there are still some technical challenges at present, and large-scale industrial application has not yet been achieved. In the future, efforts should be focused on developing combined processes and conducting in-depth research on reaction kinetics and the behavioral patterns of associated dispersed metals.