PROCESS FOR PRODUCING GYPSUM FROM A CALCIUM SULFITE GAS DESULFURIZATION SLURRY

摘要

Calcium sulfate dehydrate (dehydrate gypsum) is producedfrom an aqueous flue gas desulfurization slurry containingprimarily calcium sulfite. The aqueous slurry, containing calciumsulfite, is charged, at a pH of about 5.8 to 6.0 into the top of avertically oriented pressurized oxidation vessel and passeddownwardly therethrough while contacting the aqueous slurry with acountercurrent flow of oxygen-containing gas. The pressure in thebottom portion of the oxidation vessel is maintained at about 22-32psig, and a pressure in the top portion of the oxidation vessel ismaintained at about 10-17 psig. The aqueous slurry is maintainedat a pH of about 4.0-5.5 and at a temperature of between about 180-217°F in the vessel such that calcium sulfite in the aqueous slurryis oxidized to dehydrate gypsum with the oxidized slurry removedfrom the bottom of the oxidation vessel.