Method for ammonium-enhanced flue gas desulfurization by using red mud slurry

A method for ammonium-enhanced flue gas desulfurization (FGD) by using red mud slurry, comprising the following steps:

• (1) crushing red mud, sieving the crushed red mud through a sieve with 50-200 meshes, slurrying the red mud by using slurry liquid according to a liquid-solid ratio of (25-30):1,;
• and introducing sulfur dioxide and oxygen gas for aeration of red mud slurry in a red mud aeration tank, adding an ammonium salt and/or ammonia to the red mud aeration tank, conducting natural sedimentation to obtain pretreated red mud slurry and pretreated red mud liquor, and using the pretreated red mud slurry and the pretreated red mud liquor as pre-desulfurization slurry and deep desulfurization liquor of sulfur-containing flue gas;
• (2) adding an ammonium salt and/or ammonia to the pretreated red mud slurry, adding water and conducting uniform mixing, allowing the sulfur-containing flue gas to be in countercurrent contact with the mixture in a desulfurization tower for pre-desulfurization, conducting deep desulfurization on treated flue gas by using the pretreated red mud liquor, and directly discharging desulfurized flue gas;
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• (3) charging the pretreated red mud slurry and the pretreated red mud liquor treated in step (2) to a replacement tank below, adding lime milk to the replacement tank, conducting stirring and natural sedimentation, comprehensively utilizing subnatant thick red mud slurry for soilization, and refluxing the supernatant to the red mud aeration tank.