A comparison of growth behavior between CaCO3 and CaF2 crystals in a constant-composition environment

For the comparison of crystal growth behavior of different sparingly soluble salts, a constant-composition technique was used to study the influence of process variables on the growth of calcite and fluorite in a stirred-tank crystallizer. The growth experiments were conducted in the metastable regions determined in this study and the growth rates were evaluated from the solution volume added to the crystallizer for keeping the system at constant composition, using the cured natural calcite and fluorite as seeding. Factors affected the growth rates, such as the pH of the solution, ionic strength, activity ratio and relative supersaturation, were identified and the influence of individual factor on the growth rate was compared between the two systems. Finally, growth rate expressions of calcite and fluorite were established and compared with that reported in the literature.