Sulfuric acid magnesium salt (1:1) → Calcium Sulfate

According to the present invention, a portion of the scrubbing fluid from the scrubbing unit is treated so as to form and remove calcium components while recycling magnesium components back to the scrubbing unit. Scrubbing fluid is withdrawn from the scrubbing unit 1 through line 21 to an oxidizer 23, wherein the scrubbing fluid is contacted with an oxygen-containing gas, such as air, injected from a source, not shown, through line 25 and a plurality of discharge nozzles 27. Spent gas is removed overhead from oxidizer 23. After the desired contact time in the oxidizer 23, to convert sulfites and bisulfites of magnesium to magnesium sulfate, in a soluble form, the treated scrubbing fluid is discharged through line 29 to a reagent addition and regeneration tank 31, where the scrubbing liquor, which now comprises mainly magnesium sulfate and a minor amount of calcium sulfate is contacted with an aqueous slurry of magnesium-containing lime. A magnesium-containing lime slurry charged to the regeneration tank 31 through line 33, is formed in slaker 35 by the addition of magnesium-containing lime thereto through line 37, and water through line 39. The amount of water needed is only that sufficient to convert the magnesium and calcium compounds to their corresponding hydroxides and to form the desired aqueous slurry therewith. In the regeneration tank 31, the soluble magnesium sulfate is reacted with calcium hydroxide, which results in precipitation of calcium sulfate and magnesium hydroxide The regenerated aqueous medium is passed from the regeneration tank 31, through line 41, by means of a pump 43, to a solids separator 45, such as cyclone separator. Solids are discharged from the solids separator through line 47, while the aqueous suspension of magnesium hydroxide is discharged through line 49 to a return tank 51. The solids from line 47 may be further dewatered in a dewatering unit 53, such as a filter, with dewatered solids discharged from the system at line 55, while aqueous solution, or filtrate, from the filter 53 is returned to the clear feed return tank 51 through line 57. From the return tank 51, which contains magnesium hydroxide, scrubbing solution is returned to the scrubber 1, by means of a pump 59, through line 61.

1. customto form the desired aqueous slurry

ORD record

ord-74968674557949f897f0f803a6a503a0

Source dataset

uspto-grants-1991_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05039499