PROCESS FOR PRODUCING GYPSUM FROM A CALCIUM SULFITE GAS DESULFURIZATION SLURRY

摘要

Calcium sulfate dehydrate (dehydrate gypsum) is produced from an aqueous flue gas desulfurization slurry containing primarily calcium sulfite. The aqueous slurry, containing calcium sulfite, is charged, at a pH of about 5.8 to 6.0 into the top of a vertically oriented pressurized oxidation vessel and passed downwardly therethrough while contacting the aqueous slurry with a countercurrent flow of oxygen-containing gas. The pressure in the bottom portion of the oxidation vessel is maintained at about 22-32 psig, and a pressure in the top portion of the oxidation vessel is maintained at about 10-17 psig. The aqueous slurry is maintained at a pH of about 4.0-5.5 and at a temperature of between about 180- 217.degree.F in the vessel such that calcium sulfite in the aqueous slurry is oxidized to dehydrate gypsum with the oxidized slurry removed from the bottom of the oxidation vessel.