Motion Behavior of Nonmetal Inclusions at the Interface of Steel and Slag. Part II: Model Application and Discussion
- PDF / 999,663 Bytes
- 11 Pages / 593.972 x 792 pts Page_size
- 59 Downloads / 215 Views
INTRODUCTION
IN part I, a mathematical model was developed to describe the dynamics of nonmetal inclusions at the steel-slag interface.[1] Here, we shall discuss using this model the dependence of the separation and removal of inclusions at the interface on various parameters, mainly focusing on interfacial tension, inclusion diameter, and slag viscosity. Nakajima and Okamura found the separation of the different sizes of inclusions is strongly influenced by the interfacial properties such as interfacial tension and slag viscosity.[2–5] Nakajima and Okamura[2–4] and Cleaver and Yates[5] also found that the overall wettability should be positive and that the slag viscosity should be as low as possible to obtain the most favorable conditions for inclusion transfer at the steel-slag interface. The study of Valdez et al.[6] indicated that the interfacial energy between slag and inclusion is the more pertinent property that could hinder interfacial separation. Also the film drainage is primarily a hydrodynamic problem and the subsequent separation depends largely on the interface. Bouris and Bergeles[7] found that the smaller diameter inclusions were trapped at the inter-
SHUFENG YANG, Lecturer, JINGSHE LI, Professor, CHAO LIU, Master Student, and HONGBO YANG, Ph.D. Student, are with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China. Contact e-mail: [email protected] LIYUAN SUN, formerly Ph.D. Student with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, is now Posdoctor with the Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China. Manuscript submitted February 10, 2014. Article published online August 26, 2014. METALLURGICAL AND MATERIALS TRANSACTIONS B
face, and that larger ones were more easily removed by lift forces from turbulent shear stress. The results obtained in part I show that, for Al2O3 inclusions floating up to the steel-slag interface with Stokes terminal velocity, the critical size for the formation of the liquid film is 150 lm; if smaller than the critical size, no liquid film will be formed. Adopting the Stokes flotation velocity as the terminal velocity, the viscosity of slag is 0.08 Pa s and the interfacial tension between inclusions and slag is 0.24 N/m. When the inclusion diameters lie within the range 150 to 190 lm, the inclusions will be bounced back at the interface owing to effects of the liquid film. In this article, inclusions that are smaller than 150 lm at the steel-slag interface when no liquid film is generated will be investigated using the model. The study also includes separate analyses of inclusions with sizes in the range 150 to 190 lm and larger than 190 lm when liquid film does form.
II.
RESULTS AND DISCUSSION
Based on the model developed, programs were written to obtain the evolution of displacement for inclusions at the steel-slag interface. For two different conditions, with and without liquid film formation, factors, such a
Data Loading...
