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.