Clean Stepwise Extraction of Valuable Components from Electrolytic Manganese Residue via Reducing Leaching–Roasting

Abstract

Electrolytic manganese residue (EMR) is a solid waste that poses a significant environmental risk. With the importance of environmental sustainability, a harmless utilization process for EMR should be developed. In this study, a clean process of stepwise extraction was proposed to recover valuable components from EMR. First, the mineral phase composition of EMR was determined using a mineral liberation analyzer. Then, a weak acid reducing agent was used on the basis of the valence characteristics of metal elements to extract valuable elements. The recoveries of manganese and iron were 96.04 and 89.64%, respectively. After valuable metallic elements were separated from EMR, silicon was found to be the main component. As such, the feasibility of converting EMR into silicon-source nutrition powder was verified. Through silicon activation, the effective silicon content of EMR increased from 0.13 to 9.81%. Toxicity leaching tests revealed that the process promoted safe EMR utilization. Thus, the whole process reduces the need not only for ore mining but also for EMR inventory to avoid harmful solid waste pollution in the environment, thereby achieving a zero-waste approach.