Removal of manganous dithionate (MnS 2 O 6 ) with MnO 2 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-MnO 2 , β-MnO 2 , γ-MnO 2 , and δ-MnO 2 were prepared for MD removal in desulfurization manganese slurry. Results showed that δ-MnO 2 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-MnO 2 dosage, and reaction at 90 °C for 3 h. The MD removal with MnO 2 followed the decomposition-oxidation pass and direct oxidation-reduction reaction and consequently induced structure destruction and crystalline transfer. MD removal with natural MnO 2 ore was also examined, and natural MnO 2 ore in the δ type was found to have prominent activity. Thus, this type of natural MnO 2 may serve as a good alternative to pure MnO 2 for decreasing the cost of MD removal from desulfurization manganese slurry.