A STUDY OF EXPLANATION OF CRYSTAL GROWTH UNIT IN CRYSTALLIZATION

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In the field of industrial crystallization, the control of crystal size distribution and purity is most essential aspect, and has been investigated extensively. However the phenomena of nucleation and crystal growth have not been well understood. Therefore, in this work, the process of secondary nucleation and the subsequent crystal growth process have been investigated both by fast-dynamic light scattering method and optical microscope under the micro gravity in drop shaft and 1 g. It was found that the movement of crystals formed in solution could be suppressed completely in micro gravity, in which collision and agglomeration phenomena did not take place. No nucleation occurred except for the seed crystal surface. Also it could be measured the number and size of produced crystals with order of nano-meter by fast-dynamic light scattering method. Also, to obtain of information for crystal growth unit, the solution structure in the region of interface of growing crystal have been observ … More ed by interference optical microscope, NMR and ESC.It was found that the concentration gradient and that's region appear with the supersaturation, the direction of crystal and addition ion concentration. From the results of NMR and ESC, the existence of molecular conglomeration and complex ions in supersaturated solution was inferred. Still more, to apply to products of crystals the above results, we try to examine for control of the crystal size distribution of products in a batch crystallizer, an in-situ measurement method of solid concentration at different heights in a crystallizer was proposed by using the light sensor with infrared light emitting diodes and phototarnsisters. And this method was applied to get the information about the crystal concentration in a batch crystallizer and to control of crystal dispersion by the change of the agitation rate based on the above information. It was found that this system proposed in this work could follow the crystalization process and was useful the control of the crystal size distribution accuratel. Less