Abstract: Magnesium hydroxide of high purity, having a fine particle size suitable for use in flame retardants and other high-end uses, is produced by utilizing flue gas desulfurization system process slurry as feedstock; the production process is absent energy-intensive steps as well as high-cost chemical usage.

Abstract: A process for the simultaneous removal of sulfur dioxide and nitrogen oxides from a gaseous stream uses a sorbent containing magnesium ions and sulfite ions for sulfur dioxide removal and a metal chelating agent for nitrogen oxides removal, with the production of an amine disulfonate salt, such as potassium amine disulfonate, as a purified saleable by product.

Abstract: Sulfur dioxide is removed from a gaseous stream using an aqueous scrubbing medium containing calcium components and magnesium ions, so as to produce a more readily dewatered aqueous calcium sulfite-containing sludge by providing in the aqueous scrubbing medium in an aqueous scrubbing unit an effective amount of at least one amine sulfonate ion of the formula: ##STR1## where R is H or OH, and R' is H or SO.sub.3, with R and R' not both being H. The amine sulfonate ion is preferably provided by adding an amine disulfonate salt having the formula HN(SO.sub.3 X).sub.2 or a hydroxylamine monosulfonate salt having the formula HO--NH--(SO.sub.3 X), when X is an alkali or alkaline earth metal. Or an effluent stream from a scrubbing unit for nitrogen oxides containing a metal chelate and an amine sulfonate may be added to provide the amine sulfonate ion.