The Optimal Conditions of Preparation of Phosphogypsum-Based Calcium Sulfate Hemihydrate Whiskers by Hydrothermal Method Using Phosphogypsum

Calcium sulfate hemihydrate whisker was prepared successfully by hydrothermal method with phosphogypsum; the morphology and synthesis rate of calcium sulfate hemihydrate whisker were very sensitive to reaction temperature, reaction time, and additives. Therefore, L25(5⁶) orthogonal experiments were carried out to obtain the optimal conditions. Composition, morphology, and structure of calcium sulfate hemihydrate whisker were characterized by SEM, XRD, and FT-IR. The results showed that the optimal conditions were ball-milling time 1.5 h, reaction temperature 160 °C, reaction time 2 h, solid–liquid mass ratio 1:20, V (glycerol)/V (solution) = 10 %, and drying temperature 140 °C. Calcium sulfate hemihydrate whisker synthesis rate was 95 %; its aspect ratio was up to 45.