Research On The Crystallization Process Of Calcium-L-Lactate Pentahydrate

Calcium-L-lactate, as one kind of calcium scources, is widely used in medicine industry and food industry such as beverages and cakes. But the separation and purification technique of calcium-L-lactate has many disadvantages in domestic, such as backward technology and lower level which caused low yield and unstalbe product quality. All of these questions lead to the domestic product of calcium-L-lactate under a disadvantageous position in the international market competition. It is necessary to study the crystallization process with experimental research and theoretical analysis.The solubility of calcium-L-lactate pentahydrate in water, water+ethanol and water+acetone mixture solvents, was determined in diferent temperature with the synthetic method. The experimental data were correlated with the Apelblat model, the CNIBS/R-K model and the hybrid model. The dissolution enthalpy, entropy and Gibbs energy change of dissolution of calcium-L-lactate pentahydrate in these solvent mixtures were obtained.The metastable zone and the induction time of calcium-L-lactate pentahydrate in water were investgated using laser method. The experimental metastable zone data were correlated with the Apelblat model. The nucleation mechanism and the growth mechanism of calcium-L-lactate pentahydrate were obtained based on the classical nucleation theory.Based on the investigation of the crystallization thermodybamics and nucleation kinetics of calcium-L-lactate pentahydrate, the bath cooling crystallization was investigated. The effect of raw material liquid pretreatment, stirring rate, seeding, crystallization temperature and cooling curve on the cooling crystallization of calcium-L-lactate pentahydrate were investigated. The new process of cooling crystallization was developed which can get perfect production, larger particle size and the quality in full compliance with national standards and the production time is under eight hours.The gelation phenomena usually occur during the research of the drowning-out crystallization and the cooling crystallization, so the gelation phenomena was investigated. The experimental conditions of how to avoid forming gelation was concluded and the mechanism was explained too, which can provide the basis for avoiding forming gelation efficiently.The above researches haven't been reported in literatures.