Crystal growth kinetics of calcite and its comparison with readily solublesalts

The crystal growth kinetics. of calcite was investigated in batch crystalli zers of stirred tank and fluidized-bed type, which were maintained at a con stant pH by an autotitrator. Rhombohedron seed crystals were prepared using different techniques, then the growth experiments were conducted in the me tastable region, which was explored as part of this research, to suppress n ucleation. The crystal growth rates were evaluated from the consumption rat es of sodium carbonate and calcium ion for the stirred-tank and fluidized-b ed experiments, respectively. Several operating variables were investigated and the crystal growth rate data of constant pH and ionic strength were an alyzed by the two-step crystal growth model. The mass-transfer and surface- reaction coefficients were thus obtained and used to explain the growth beh aviors of calcite crystals. Then, the crystal growth kinetics of this spari ngly soluble salt was compared with that of readily soluble salts. Although the effects of pH and ionic strength on crystal growth were not reported f or the readily soluble systems, these effects were significant to calcite g rowth. (C) 2001 Elsevier Science B.V. All rights reserved.