초록 ▼

The dewatering capabilities of sulfite sludges from flue gas desulfurization facilities are substantially improved by the addition of relatively small amounts of sodium thiosulfate additive, or additives derived from or related to sodium thiosulfate, into the scrubber slurry liquor. As an added embe

The dewatering capabilities of sulfite sludges from flue gas desulfurization facilities are substantially improved by the addition of relatively small amounts of sodium thiosulfate additive, or additives derived from or related to sodium thiosulfate, into the scrubber slurry liquor. As an added embellishment, these predetermined amounts of said additives are greater than those required for effecting substantial scale inhibition in the scrubber innards. Subsequently, conventional dewatering of the sulfite sludge to about 80 to 90 percent solids directly produces a waste product disposable in both an economically and an environmentally acceptable manner, in that the thixotropic characteristics of such sludges which are associated therewith upwards to about 70-percent solids therein are completely eliminated.

대표청구항 ▼

In an improved process for the removal of SO2 from an input gas stream containing SO2 wherein the input gas stream is contacted, in a gas-liquid scrubbing zone, with an aqueous scrubbing slurry containing an alkaline reagent wherein said alkaline reagent contained in said scrubbing slurry is selecte

In an improved process for the removal of SO2 from an input gas stream containing SO2 wherein the input gas stream is contacted, in a gas-liquid scrubbing zone, with an aqueous scrubbing slurry containing an alkaline reagent wherein said alkaline reagent contained in said scrubbing slurry is selected from the group consisting of lime, limestone, or mixtures thereof at scrubbing conditions selected to form a resulting treated gas stream containing substantially less SO2 than said input gas stream and a resulting SO2 enriched scrubbing slurry containing as a substantial portion of the solids therein calcium sulfite hemihydrate; subsequently effecting at least a partial dewatering of said SO2 enriched scrubbing slurry; and removing the resulting at least partially dewatered sludge to waste disposal; the improvement in combination therewith for substantially increasing the yield of solids in said dewatered sludge to thereby render same eminently suitable for use in solid landfill waste disposal operations, which improved process comprises adding to and maintaining in said aqueous scrubbing slurry from about 250 ppm to about 2500 ppm of thiosulfate ion, said improved process characterized by the fact that the addition and maintenance of said amounts of thiosulfate ion in said aqueous scrubbing slurry is sufficient to effect therein a crystal habit of the calcium sulfite hemihydrate comprising a substantial portion of the solids therein in a tabular prismatic mode and substantially eliminates therein the occurrence of porous lamellar aggregates of randomly oriented micaceous crystallites of said calcium sulfite hemihydrate, thereby altering the agglomerative characteristics of said crystallites in the spent slurry removed from said gas-liquid scrubbing zone to a mode which substantially increases the settling rate thereof and results in the ultimate dewatering of said sludge up to the range of about 80 to 90 percent solids by weight.