Crystallization Kinetics of Calcium Lactate in a Mixed-Suspension-Mixed-Product Removal Crystallizer

Continuous crystallization of calcium lactate pentahydrate was investigated in a mixed-suspension-mixed-product removal crystallizer. Wide ranges of the mean residence time, relative supersaturation, and magma density were covered (40−215 min, 0.01−1.12, and 2−65 kg/m3, respectively). Crystal growth was found to be dependent on crystal size. The Abegg, Stevens, and Larson model and the Mydlarz and Jones model were tested for the determination of the kinetics parameters from experimental results. Zero-size and larger size crystal growth rate values were found to be on the order of 10-13 and 10-8 m/s, respectively. A first-order growth kinetics resulted for both large and small crystals. Nucleation rate values were very high (≈1013−1015 no./m3·s). Nucleation kinetics could not be described by a unique power law equation because two different nucleation mechanisms appeared to control crystallization at low and high residence times, respectively.