Crystal growth kinetics of calcite in a dense fluidized-bed crystallizer

The growth kinetics of calcite crystals are studied in a batch-fluidized-be d crystallizer, which is maintained at a constant pH. The growth experiment s are conducted in the metastable region explored as part of this research. The crystal growth rates are evaluated from the consumption rates of calci um ions, using the cured natural calcite or silica sand as seeding material s. Several operation variables are investigated, including supersaturation, pH, ionic strength, superficial velocity and particle size and type of see n. The significant factors that affect the crystal growth rate are identifi ed. Then the crystal growth data of constant pH and ionic strength are anal yzed by the two-step growth model. The mass-transfer coefficients are obtai ned and compared at various crystal sizes and superficial velocities. Final ly, a growth-rate equation of calcite crystal, which is based on the two-st ep growth model, is proposed for design purposes.