Method for recovering magnesium from flue gas desulfurization wastewater by using recycled heat-sensitive amine

The invention discloses a method for recovering magnesium from flue gas desulfurization wastewater by using recycled heat-sensitive amine. Comprising the following steps: (1) pretreating flue gas desulfurization wastewater to obtain flue gas desulfurization wastewater without suspended solids; (2) mixing the flue gas desulfurization wastewater obtained in the step (1) with heat-sensitive amine to obtain slurry containing magnesium hydroxide precipitate and residual hardness ions; (3) filtering the slurry obtained in the step (2) to respectively obtain precipitate and filtrate; (4) washing and drying the precipitate obtained in the step (3), and calcining at 500 DEG C for 2 hours to obtain magnesium oxide with high reaction activity; (5) heating the filtrate separated in the step (3) to obtain regenerated heat-sensitive amine; and (6) returning the regenerated heat-sensitive amine obtained in the step (5) to the step (2) for recycling. The method provided by the invention not only can remove most hardness in t