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Impurity effects on crystallization of KCL from aqueous solutions in a MSMPR crystallizer
Author(s) -
Dash S. R.,
Rohani S.,
Sokhansanj S.
Publication year - 1996
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450740212
Subject(s) - crystallization , impurity , nucleation , chemistry , magnesium , ion , aqueous solution , crystal growth , crystal (programming language) , sulfate , chemical engineering , inorganic chemistry , analytical chemistry (journal) , crystallography , chromatography , organic chemistry , engineering , computer science , programming language
Extensive experimental investigations into the effect of magnesium and sulfate ionic impurities on cooling crystallization of KCl were carried out in a steady‐state Mixed Suspension Mixed Product Removal (MSMPR) crystallizer. The impurities selected for investigation were chosen from those naturally associated with KCl in potash industry. Eighty one experiments were performed in a factorial experimental design scheme. The results exhibited that magnesium ion did not have any significant influence upon crystallizations of KCl, while the sulfate ion enhanced the aggregation rate. The nucleation rate was only slightly affected by the presence of impurities. The size enlargement in presence of sulfate ion was ascribed to an increase in aggregation rate. It was demonstrated that the role of the impurities studied upon KCl crystallization is consistent and predictable and is a function of the chemical character of the impurity species. Based on these results two mechanisms for size enlargement were identified, first due to crystal growth by solid deposition and second due to aggregation. Aggregation was found to be the governing mechanism for producing large crystals.