EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

In order to enhance the reaction rate between the slag and the metal, the formation of metal droplets in the slag phase (metal emulsion) is an effective measure. In this paper, the formation behavior of metal droplets by the bubble rupture of the gas injected into the metal phase was investigated. To extract the metal droplets, the water soluble chloride (KCl-LiCl-NaCl) and oxide (Na2B4O7) were used as the upper phase and the influence of viscosity was clarified. As the lower phase, Sn and Sn-Te were used to show the influence of interfacial tension. By the sampling of upper phase during gas bubbling, the size distribution of the emulsified metal droplets, extracted by the immersion of the sample into the aqueous solution, was measured. In addition, the direct observation of the bubble detachment and droplets formation behaviors by high speed camera was conducted as the upper phase was transparent. The following results were obtained: (1) As the increase in the gas flow rate, formation rate of droplets increased. The decrease in the interfacial tension and the increase in the viscosity showed the negative effect on the formation rate. (2) The frequency of bubble rupture increased and bubble volume decreased by the decrease of the interfacial tension. (3) The dimension less equation which showed the total volume of droplets divided by bubble volume was formulated as a function of physical properties and bubble Eötvös number to predict the droplets formation rate in the bottom blowing converter.