Attrition and Secondary Nucleation in Agitated Crystal Slurries
The objective of our study is to determine methods of scaling-up nucleation rates, measured in the laboratory, for the design and optimisation of full-scale crystallisers. It is usually accepted that the dominant form of nucleation occurring in continuous industrial crystallisers is secondary nucleation. Recent research has shown that this nucleation is caused by some form of attrition mechanism, (1, 2). This mechanism is either the detachment, by impact or fluid-shear, of clusters from a parent crystal or the fracture of the parent crystal surface, by some form of comminution, and the production of discrete crystal fragments. The major factors influencing this mechanism are the system super-saturation and the crystalliser hydrodynamics. The supersaturation will control both the parent crystal surface and the survival and development of the clusters or fragments into product crystals. The crystalliser hydrodynamics will control the collision energies and collision frequencies of the parent seeds.
KeywordsNucleation Rate Attrition Rate Coulter Counter Seed Crystal Secondary Nucleation
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- 1.Clontz N A and McCabe W L, Chem. Eng. Progr. Symp. Ser., No. 110, 67, (1971) 6.Google Scholar
- 2.Strickland-Constable R F, “Kinetics and Mechanism of Crystallisation”, Academic Press, London (1968).Google Scholar
- 3.Ramshaw C and Parker I B, Trans. Instn. Chem. Engrs., 51, (1973), 72.Google Scholar