Mechanisms of dry flue-gas desulfurization using natural manganese oxide ores

The mechanisms of flue-gas desulfurization using high and low-grade natural manganese oxide ores were comparatively studied. Both manganese oxide ores exhibit good desulfurization capabilities with SO 2 content in the effluents less than 30 ppm, but the low-grade ores show the much better desulfurization capability. XRD and SEM/EDS results reveal that the MnO 2 absorbs the SO 2 to convert to MnSO 4 . The SO 2 give prior to react with the surface MnO 2 and the produced MnSO 2 enriched on the surface leads to the gradually decrease of the SO 2 removal rate during desulfurization process. The better desulfurization capability of the low-grade ores is ascribed to the more dispersive MnO 2 due to the poriferous/lax internal tunnel structure, and the embedded inert SiO 2 shows better support effects to avoid pore structure blocking, which is favorable for enhancing the diffusion of the SO 2 and desulfurization reaction process. This study is of significance in the comprehensive utilization of the low-grade natural manganese oxide ores, environmental protection and even the preparation of the desulfurization catalyst with MnO 2 .