The Effect of Impurities on the Gypsum Crystallization in Phosphoric Acid Production Process

Gypsum crystallization in the dehydrate process of phosphoric acid production was studied. The main part of impurities existing in the phosphate rock enters the liquid phase during chemical reaction. These impurities can affect the chemical reaction and gypsum crystallization. The study was done in a glass reactor acts as a MSMPR crystallizer. The method employed here is the study of impurities effects on the filterability of crystals (specific resistance of filter cake) with help of crystal size distribution obtained in the presence of impurity. The impurity effects can be classified as direct and indirect effects. This results shows that type and presence of impurities can affect the crystal properties such as density, shape, size and size distribution, filterability and washing properties. These effects are not similar for different impurity concentrations and are function of impurity type and its concentration.