Ceramics-Silikáty 49 (2) 115-119 (2005)

THE TREATMENT OF GYPSUM AS A PRODUCT OF THE FLUE GAS DESULPHURIZATION PROCESS

A. Kostic-Pulek, S. Marinkovic, S. Popov, M. Djuricic, J. Djinovic

The modified hydrothermal method for the preparation of the alpha hemihydrate calcium sulphate was applied for the dehydration of gypsum as a product of the flue gas desulphurization process with the gypsum/acid solution mixing ratios 0.125, 0.250, 0.500 and 0.750 g/cm³. The obtained products were investigated by IR, DTA and microscopic analysis. The result of IR analysis indicated complete reaction at different rates, in the first three suspensions (0.125 - 0.500 g/cm³) giving a mixture of the both (alpha and beta) hemihydrate forms. In the suspension with the ratio 0.750 g/cm³ the dehydration of gypsum was not complete. The results showed that an increasing the gypsum/acid solution mixing ratio brings an increase of the fraction of the superior alpha form in the final product, as well as an increase of the reaction rate and the average lengths of the alpha hemihydrate single crystals.

Keywords: Alpha and beta hemihydrate, FGD gypsum, Hydrothermal method