PROCESS FOR THE PRODUCTION OF ALPHA HEMIHYDRATE CALCIUM SULFATE FROM FLUE GAS DESULFURIZATION MATERIALS

摘要

Process for producing alpha-hemihydrate calcium sulfate from FGD sludge comprising treating an aqueous slurry of the sludge with a stabilizing effective amount of a stabilizing polyhydric alcohol to stabilize the .alpha.HH to obtain .alpha.HH crystal growth, at atmospheric pressure and a temperature greater than 80.degree.C and a pH selected from 3 to 6. The polyhydric alcohol may be selected from ethylene glycol, glycerol and a carbohydrate. The process offers a commercially viable method of making .alpha.HH from FGD sludge wastes.