Removal of manganous dithionate (MnS2O6) with MnO2 from the desulfurization manganese slurry

Manganese desulfurization has been increasingly explored, but the generated manganous dithionate (MD) by-product affects the valuable use of the desulfurized slurry. In this study, α-MnO2, β-MnO2, γ-MnO2, and δ-MnO2 were prepared for MD removal in desulfurization manganese slurry. Results showed that δ-MnO2 had the best activity among the four because of its porosity and favorable surface properties. The operation conditions showed that 12.00 g L−1 MD can be removed by more than 80.00% under the conditions of 1.4 mol L−1 sulfuric acid, 100 g L−1 δ-MnO2 dosage, and reaction at 90 °C for 3 h. The MD removal with MnO2 followed the decomposition–oxidation pass and direct oxidation–reduction reaction and consequently induced structure destruction and crystalline transfer. MD removal with natural MnO2 ore was also examined, and natural MnO2 ore in the δ type was found to have prominent activity. Thus, this type of natural MnO2 may serve as a good alternative to pure MnO2 for decreasing the cost of MD removal from desulfurization manganese slurry.