THE METHOD FOR SYNTHETIC GYPSUM PRODUCTION FROM A PRODUCT OF SEMI-DRY METHOD OF FLUE GAS DESULPHURISATION

摘要

A typical product from semi-dry method of flue gas desulphurisation contains 50 - 70% CaSO{sub}3·0.5H{sub}2O, 10 - 20% Ca(OH){sub}2, 5 - 10% CaSO{sub}4·2H{sub}2O, 5 -10% CaCO{sub}3, 2% CaCl{sub}2·4H{sub}2O and small amount of other pollutants - components of the combusted fuel. Usually the material is dumped. The paper presents results of the studies on development of a technology for processing that material into synthetic gypsum. The investigations covered the process based on neutralisation of alkaline components of the material with H{sub}2SO{sub}4 and simultaneous oxidation of CaSO{sub}3 by strongly dispersed air at pH about 4, in a reactor of flotation machine type structure. Influence of suspension density, sulphuric acid concentration, retention time, linear velocity of mixing and air flow intensity on oxidation kinetics and gypsum crystal quality was studied. Optimum operating conditions of the process were determined.