Abstract: Phosphogypsum is a powder with high CaSO_4·2H_2O content, The P_2O_5 and F impurities present in phosphogypsum can not be removed completely by washing and chemical treatments. When heated at high temperature, phosphogypsum produced an anhydrite and the impurities became inert and harmless. The effects of different activators on setting and hardening of anhydrite cement was studied. The correlation between hydration and chemically combined water was established. The micro formation mechanism of anhydrite cement was examined by SEM and XRD.

Key words: phosphogypsum;calcination temperature;anhydrite cement;activator;compressive strength