Highly Efficient Evaporative Crystallization of a High Suspension Density Sodium Chloride Slurry in a Draft-Tube Stirred Vessel in Continuous Operation

Abstract

High suspension density slurries generally require high-power stirring, which can introduce a large amount of particle abrasion following particle collisions, and subsequent secondary nucleation. In this study, the influence of stirring operation and suspension density on evaporative crystallization of a high-density suspension of sodium chloride in continuous operation was investigated for an optimally designed draft-tube stirred vessel based on the time evolution of the number of crystals and the particle size distribution. For highly efficient evaporative crystallization in continuous operation, the particle suspension density should be kept high to eliminate excess nucleation with large particle surface areas. The impeller speed should be somewhat higher than the condition at which particles just become completely suspended to prevent particle agglomeration.