engleski

Effect of off-bottom impeller clearance on nucleation and crystal growth of borax decahydrate in batch cooling crystallizer

The main topic of this study was to estimate the impact of the off-bottom impeller clearance on the metastable zone width, nucleation kinetics and the crystal size distribution of borax decahydrate. The importance of impeller position was studied in baffled stirred crystallizer with a volume of about 2 L, equipped with straight four blade turbine (4-SBT) cooling at constant cooling rate. Metastable zone width was determined by visual method, while concentration changes during the process were monitored in line using ion-selective electrode. The nucleation behavior in the batch cooling crystallizer was presented according to Mersmann's criteria. On the basis of the experimental results and observations it is evident that in an agitated batch crystallizer metastable zone width, nucleation rate, crystal growth as well as crystal size distribution are significantly influenced by hydrodynamic regime in the system determined by impeller used and its position.

crystallization; borax; mixing; off-bottom clearance; metastable zone width; nucleation; crystal growth; crystal size distributions

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