The Formation of Manganous Dithionate in the Manganese Oxide Flue Gas Desulfurization

Background & Objective: The Manganous Dithionate (MnS2O6, MD) was formed during the flue gas desulfurization process over manganese ore slurry, which impeded the following valuable using of the desulfurized lixivium. In this study, the MD formation and restraint in the desulfurization process using manganese was carefully investigated. Methods & Results: Different type of manganese oxides/carbonate was used for the flue gas desulfurization, and the MD formation with the process was detected to obtain the basic information of the MD formation and restraint. The MD was directly formed by the uncompleted oxidation of SO2 with MnO2. The increased MD formation by Mn2O3, Mn3O4 and MnCO3 was due to their influence on the pH of slurry. Processability study showed that an increase in the acidity of slurry, the gaseous oxygen content and reaction temperature could inhibit the MD formation effectively. The optimum operating conditions to restrain the MD formation were temperature higher than 60°C, 10% or more oxygen and slurry pH lower than 3. The formed MD content was different with the different manganese compounds, which cloud be controlled by the ore-proportioning in industrial application. Conclusion: Using anolyte to prepare the manganese slurry for desulfurization could perform a good MD formation restraint, which provided valuable technical support for the cleaner production of electrolytic manganese industry.