Metal Emulsion Behavior of Droplets with Various Sizes in the Na 2 B 4 O 7 /Sn Alloy System by Bottom Bubbling Gas and i
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DURING the passage of gas bubbles through the interface between two immiscible liquids, the lower phase can be extracted into the upper phase and ruptured into droplets. In steelmaking process, e.g., the bottom blowing converter, when gas bubbles pass through the interface between liquid steel and slag, metal phase are taken into slag phase and dispersed in the slag phase as
JIANG LIU is with the Graduate School of Engineering, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan, and also with the Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8550, Japan. Contact e-mail: [email protected] SUN-JOONG KIM is with the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan, and also with the Department of Materials Science and Engineering, College of Engineering, Chosun University, 309, Pilmun-daero, Dong-gu, Gwangju 61452, Korea. XU GAO, SHIGERU UEDA, and SHIN-YA KITAMURA are with the Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8055, Japan. Manuscript submitted February 27, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
metal emulsion. The metal droplets increase the interfacial area between molten steel and slag phases. Several studies have analyzed metal droplets sampled from the converter during gas blowing.[1–3] These confirmed that the carbon, phosphorus, and manganese contents in the droplets were lower than those in the bulk. Hence, the metal droplets kinetically promote the chemical reaction efficiency. Much attention has been paid to estimate the formation rate of metal emulsions. Cold systems have usually been used because it is easy to observe the phenomenon. Reiter et al. measured the number and size of the droplets using different materials (water/oil, Hg/water, etc.).[4,5] They found that the number and size of the droplets increased with increasing gas bubble size. The droplets formed in the water/oil system were much larger than those in the Hg/water system. Lin et al. estimated the volume of droplets generated in the ZnCl2/oil and water/oil systems by measuring their size.[6] They found that the total droplet volume increased with increase in the gas flow rate, and the droplet birth rate increased with decreasing viscosity of the upper phase. Zaidi and Lee et al. researched the water/kerosene system.[7,8] Droplets larger than 1 mm in diameter were collected by a volumetric pipette and measured. The correlation between holdup of
droplets (the volume fraction of the dispersed phase) and gas flow was discussed. However, due to the large differences in physical properties, such as viscosity and density, the results in cold systems are not directly applicable to the slag and steel system. Han et al. studied the mass of metal droplets entrained into the slag phase per gas bubble in the molten iron/slag system.[9–11] Droplet behavior was observed using X-ray fluoroscopy. Using different slags, the effect of interfac
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