Preparation of a High-strength Gypsum from FGD Gypsum by Autoclaved Semi-dry Process

摘要

This paper introduced the characteristics of a high-strength gypsum preparation from FGD gypsum by autoclaved semi-dry process. The compositions of the product in different stages of the reaction and the effects of crystal modifiers on the morphology of the a-HH crystals were examined and compared. The properties of a-HH and the feature of hydration products of a-HH were investigated. The results indicated that the a-HH crystals were well-shaped with the aspect ratio of 1 and the compressive strength of the a-HH could reach or exceed 60MPa. In the new process, the reaction time could be significantly shortened to 2.5hrs, which was much shorter than the conventional process. This process could be widely applied to prepare a high-strength gypsum with phosphogypsum, citric acid gypsum, etc.