Ceramics-Silikáty 52 (4) 291-295 (2008)

THERMAL TREATMENT OF THE PHOSPHOGYPSUM BRIQUETTES IN WATER VAPOUR UNDER ELEVATED PRESSURE

A. Kaziliunas , M. Bacauskiene

Wet process of impurities neutralization or their removal from phosphogypsum considerably increases the cost price of the product. The principal possibilities for the thermal treatment of dihydrate phosphogypsum into the gypsum binder by escaping wet processing are discussed in the paper. The pressure of saturated water vapour is not a sufficient condition initiating a complete neutralization reaction between the acidic impurities of phosphogypsum and the neutralization admixture or determining the growth of hemihydrate gypsum crystals. Under such condition, the transfer of the materials between particles does not take place. To achieve it, the cavities between the particles in the phosphogypsum briquette should be filled with water. Under this condition, the most reliable admixtures neutralizating the acidic impurities are ground carbonate solids (e.g. chalk, limestone, dolomite).

Keywords: Phosphogypsum, Impurities, Neutralization, Dehydration, Autoclave