The influence of the process parameters on the hydroxyapatite continuous crystallization kinetics

The results of the mass crystallization kinetics of the process of calcium ions precipitation with the use of ammonium dihydrogenphosphate NH4H2PO4 in water under alkaline conditions (pH = 9) are presented. The experiments were carried out in the continuous laboratory DTB MSMPR (Draft Tube Baffle, Mixed Suspension Mixed Product Removal) crystallizer with the internal circulation of the suspension. The influence of calcium ions concentration in the feed stream, the temperature and the residence time on the nucleation and the growth rates of hydroxyapatite crystals formed, was established. The kinetic parameters were evaluated from the crystal size distributions employing selected SDG (Size Dependent Growth) models.