Mass transfer from an oxygen jet to liquid silver

A subsonic jet of pure oxygen discharging from a converging nozzle with a throat diameter of 2.5 mm was directed vertically on the surface of molten silver maintained at 1000°C. The effects of variation in lance height (5 to 25 cm), jet momentum (3000 to 56000 dyne), jet temperature (600° to 1000°C) and interfacial area (45 sq cm to 182 sq cm) were studied. In all cases the oxygen concentration in the silver was measured by lime stabilized zirconia probes. The mean liquid phase mass transfer coefficients calculated for transfer across the total surface area of the bath of 182 sq cm, ranged from 0.001 to 0.015 cmJs. The higher values were obtained with high jet momentums or with low values of the lance height. A decrease in the surface area of the bath to 45 sq cm only slightly reduced the rate of transfer and resulted in a threefold increase in the mass transfer coefficient based on the reduced area. The mass transfer coefficients were independent of the jet temperature providing the jet momentum was maintained constant and there were no thermal gradients in the liquid silver. A. CHATTERJEE, formerly Member of the John Percy Research Group in Process Metallurgy, Imperial College of Science and Technology, London, England. D. H. WAKELIN, formerly Member of the John Percy Research Group in Process Metallurgy, Imperial College of Science and Technology.