Methods for simultaneous removal of SO2 and NOx from flue-gases under recovery of value

摘要

It is known to scrub out SO2 and NOx from flue gases using EDTA solutions. Sulphur-nitrogen compounds are formed in the scrubbing liquid, as are sulphite compounds and sulphate compounds which are precipitated out as calcium sulphite and sulphate as solids from the scrubbing liquid using lime. In order, in a process of this type, to create a recovery of valuable materials, according to the invention it is proposed that the sulphur dioxide, after the simultaneous scrubbing in the scrubber (2), and the solid precipitated as calcium sulphite/calcium sulphate by lime as a suspension are fed to the gravity separator (6) and, after settling the solids, a portion of the clear liquid is fed to an evaporation (9). From the evaporation (9), the evaporation residue, composed of Na2SO4, Na2SO3 and NS compounds is thermally decomposed at 750 DEG C together with the dewatered solids CaSO3/CaSO4 from the gravity separator, so that SO2 liberated at (11) is returned to the dirty gas process and a solid product in the form of anhydrite is produced at (12) which is used as a commercial material, preferably in mining underground as dam material. IMAGE