Flue gas desulfurization method and flue gas desulfurization system using slag slurry as desulfurizing agent

The invention discloses a flue gas desulfurization method and flue gas desulfurization system using slag slurry as a desulfurizing agent, the method comprises the following steps: preparation of mixed slurry, desulfurization, post-treatment of a desulfurization product, and a slurry supplementing step; the desulfurization system comprises a mixed slurry system, a desulfurization reaction system and a desulfurization aftertreatment system, the desulfurization reaction is carried out in an absorption tower, and the mixed slurry system comprises an absorption tower mixed slurry tank, a slurry pool and an absorbent slurry tank; and according to the invention. the mixed slurry is conveyed to an absorption tower for a flue gas desulfurization reaction, after the desulfurization reaction is carried out for a period of time, gypsum slurry is discharged, fresh slurry is supplemented, and the desulfurization reaction is continued. According to the invention, a mixed slurry treatment mode is adopted, and the slag slurry