Extraction and Separation of Mn and Pb from Electrolytic Manganese Anodic Slime (EMAS) via SO2 Roasting Followed by Acid Leaching Process

Electrolytic manganese anodic slime (EMAS) with high contents of manganese and lead is a well-known refractory secondary resource because of its complex constituents and structure. Traditional stockpiling treatment of EMAS not only causes resource waste, but also leads to long-term environmental pollution. In this study, SO2 roasting followed by acid leaching process was put forward to extract and separate manganese and lead from the EMAS. Thermodynamic analysis showed that a coexistence area of MnSO4 and PbSO4 was present in both the roasting and leaching processes. During the roasting process, manganese and lead oxides were sulfated to MnSO4 and PbSO4 by SO2. Then, MnSO4 and PbSO4 could be separated in the following acid-leaching process owing to their different solubilities in acid solution. The leaching efficiencies of 92.5 wt.% for Mn and only 3.21 wt.% for Pb were obtained under optimal conditions. This study provides an alternative approach to utilize the EMAS.