In order to solve the problem that MnS2O6 formed in the process of flue gas desulfurization and denitration with pyrolusite slurry will lower the purity of byproduct, the decomposition characteristics of MnS2O6 in liquid phase were studied. The decomposition rate of MnS2O6 was measured instead of the formation rate of SO2 based on the decomposition products of MnS2O6 and iodometry principle for SO2 determination. Factors affecting decomposition rate were investigated, which included manganese dithionate concentration, sulfuric acid concentration, manganese sulfate concentration, manganese nitrate concentration and reaction temperature. Experiment results indicated that the MnS2O6 decomposition rate increases with the increasing of manganese dithionate concentration, sulfuric acid concentration and reaction temperature, but decreases with manganese sulfate concentration increasing, and is independent of manganese nitrate concentration. The reaction is 0.8 order for manganese dithionate and 1.2 order for sulfuric acid, the activation energy is 96.9 kJ·mol-1 and the pre-exponential factor is 1.61×10^10 s-1.The study provided theoretical basis for the removal of MnS2O6 in the absorption solution of flue gas desulfurization and denitrificaiton with pyrolusite slurry.
