STUDIES OF UNIDIRECTIONAL CRYSTAL GROWTH AS THE BASIS OF NORMAL FREEZING

Abstract

As a fundamental study of growth rates in zone refining, the growth rates of crystal layers of sodium thiosulfate on a cooling surface placed at the bottom of an agitated tank were measured and compared with calculated growth rates in which the assumptions were made that the growth process of crystal layers involves mass transfer, heat transfer in the liquid and in the crystal layer and surface rate process. Good agreement between them was obtained except for the initial period, in which the crystal grew rapidly with very rough interfaces. This difference was explained as a result of the inclusion of the mother liquor at the growing interface.