FLUE GAS TREATMENT SYSTEM

摘要

PROBLEM TO BE SOLVED: To facilitate the treatment of Se in a flue gas by providing the system with a means for subjecting a flue dust slurry to which an insolubilizer and an adsorbent are added, to solid-liquid separation. SOLUTION: In this system, dust contg. Se stuck thereto is collected and removed from a flue gas by using an electrostatic precipitator 5 or the like and then, subjected to extraction treatment with a liquid supplied from a wet desulfurization equipment 20 in an extraction means 13 to extract soluble components in the dust and to form a dust slurry. Thereafter, an insolubilizer A that is used for insolubilizing at least quadrivalent Se and supplied from an insolubilizer supply means 16, is added to the dust slurry in a mixing means 14 and further, an adsorbent X that is used for adsorbing at least hexavalent Se and supplied from an adsorbent supply means 100 is added to the resulting dust slurry in another mixing means 101 and then, the dust slurry contg. the insolubilizer and adsorbent is subjected to solid-liquid separation with a separation means 15 to separate quadrivalent and hexavalent Se in the solid phase from the liquid phase. At that time, each of a slurry withdrawal line of the desulfurization unit 20 and a wastewater treatment equipment 50 is similarly provided with a mixing device 14, an insolubilizer supply means 16, another mixing means 101, an adsorbent supply means 100 and a separation means. Moreover, in the desulfurization equipment 20, minimum required oxidation is performed by using an oxidation-reduction potential control method to inhibit oxidation of quadrivalent Se to hexavalent Se from occurring and to facilitate the Se treatment in the wastewater treatment equipment 50, etc. As the adsorbent X, an organismic raw material such as eggshell membrane or feather is used and as the insolubilizer A, FeCl3 or Fe(SO4 )3 is used.