FRACTIONAL CRYSTALLIZATION FROM MELTS (thesis)

S>Studies of the separation process known as zone melting were enclosed in 5 to 10 mm glass tubes and pulled through a stationary heater, which generated a liquid zone. The separation increased as the zone travel rate decreased, as the size of the tube increased, and as the difference in liquid density between the belk solid and the freezing interface increased. It was also found that, for vertical tubes, the separation was much greater when the fluid of lower density Between the buld zone and the freezing interface) was on the bottom the When it was on the top. Insertion of an axial thbe or rod of metal or glass into the zone also increased the separation. A correlation was developed which enables estimation of the separation for various - sithations in zone melting, Equations and principles were developed which enable estimation of the thermal requirements for zone melting and a theoretical study of pure diffusional mass transfer in some melting was also made. A general expression for concentration profiles was derived for materials with a constant distribution coefficient and a method for the rapid estimation of these concentration profiles was developed, Numerical results for eutectic-forming systems were obtained, and summarized in an analytical approximation. Economic calculations are included for a separation in the multistaged semicontinuous zone refiner known as a zone-void refiner. Exploratory experiments were made on a cooled-drum apparatus (modified drum- flaker), using NaC1-water as a system. These indicated that this equipment might be useful for large scalp industrial separations, although further research and development are needed. (auth