Magnesium bi:sulphite mfr. with low chloride content - obtd. from waste combustion gases produced in a lye boiler

摘要

The combustion gases are fed through a chemical recovery plant using a dry separator removing part of the MgO in the gas, followed by a wet scrubber in which the residual MgO and SO2 in the gas form magnesium bisuplhate (I) which enters the wash liq. together with chlorides. Wash liq. is heated so the (I) forms SO2 and magnesium sulphite (II) which is pptd. followed by removing part of the liq. contg. chloride. The gas leaving the scrubber enters other scrubbers to form (I). Wash liq. pref. also contains suspended (II), steam being used to form more (II) and SO2; the SO2 is pref. used in the succeeding scrubbers producing (I). Chlorides are removed from the (I) without losing large amt. of chemicals.