Contact nucleation of MgSO4·7H2O in a continuous MSMPR crystallizer
1974; Elsevier BV; Volume: 29; Issue: 5 Linguagem: Inglês
10.1016/0009-2509(74)80125-9
ISSN1873-4405
AutoresLarry Gene Bauer, M. A. Larson, V.J. Dallons,
Tópico(s)Calcium Carbonate Crystallization and Inhibition
ResumoA frequent problem encountered in crystallizers is the control of the crystal size distribution (CSD) produced in the crystallizer. The most effective means of controlling the CSD is to control the nucleation rate. In most crystallizers the dominant type of nucleation is contact nucleation. This investigation was initiated in order to learn more about the mechanism of contact nucleation and the parameters affecting it. It was established that periodic contacting of a MgSO4·7H2O crystal mounted in a continuous MSMPR crystallizer produced a concentration of nuclei that could be measured with a Coulter counter. Based on the CSD, the number of nuclei produced per contact was obtained. This number was related to the system parameters–supersaturation, residence time, contact energy and frequency of contact. The number of nuclei produced per contact increased with an increase in the supersaturation. A deterioration of the nucleating properties of the crystal surface was noted at a contact frequency of about 8 per min. The energy of contact affects the number of nuclei produced per contact. This number initially increased to a maximum value and then declined with a further increase in the contact energy.
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