Ceramics-Silikáty 40, (3) 99 - 102 (1996)

Flue gas gypsum was thermally treated in 3M boiling aqueous solution of sodium-chloride at atmospheric pressure (gypsum-salt solution mixing ratios were: 0.125; 0.25; 0.50; 0.75; and 1.00 g.cm⁻³). The results indicated that the gypsum conversion rate increased with the gypsum salt solution mixing ratio and that the products achieved at different rates consisted of crystals varied in morphology, size, and specific surface area; the product of the smallest specific surface area (and the highest usability) was that of the highest gypsum-salt solution mixing ratio. It has also been found that the prolonged thermal treatment, after the hemihydrate has been formed, was without a significant effect on its quality.