Concepts and Measurement of Velocities and Viscosities at the Slag-Metal Interface
Dynamic studies on the mass transfer of surface-active elements from gas to molten iron through a suitable slag phase were carried out using sessile drop technique incorporating an x-ray imaging system. The surface active elements in focus were sulfur and oxygen using the slag systems CaO-SiO2-Al2O3-FeO and CaO-SiO2-Al2O3 respectively. In both cases, the slag was saturated with alumina in order to prevent any slag compositional changes due to reactions with the alumina crucible. Proper sulfur and oxygen potentials were maintained in all phases for both cases. X-ray videos were taken that were later processed to identify the oscillation of the molten iron drop occurring during the mass transfer. The oscillations were traced to the surface movement occurring due to the concentration difference of sulfur/oxygen at the interface, which created an instantaneous area change at the slag-metal interface. This area change was due to the combined effect of Marangoni flow and interface dilatation. The velocities of sulfur and oxygen at the interface were calculated from the area change. The interfacial velocities had a maximum order of magnitude of 10-4 m/s. The change in area measured from the oscillations was attributed to the change in interfacial tension. The Interfacial dilatational modulus was evaluated for slag-metal systems at 1823 K. The high values of the dilatational modulus (5-10 times that obtained for surfactant adsorption) was directly related to the higher change in apparent interfacial tension prevailing at the slag-metal interface. The variation in the dilatational modulus was due to the non-uniform distribution of surface active elements at the interface and also to the varying surface pressure. Further, cold-model experiments were designed and carried out in order to estimate the surface shear viscosity. A relationship was established to find the surface/interfacial shear viscosity from the Newtons law of viscosity. The order of magnitude of the interfacial shear viscosity at the slag-metal interface was estimated from the values obtained earlier for the interfacial velocity. The order of magnitude obtained for slag-metal systems was roughly 10-100 times that usually occurring in colloidal systems.
Interfacial Tension Sulfur Oxygen Sessile Drop Interfacial Velocity Interfacial Dilatational Modulus,Interfacial Shear Viscosity
Luckman Muhmood Nurni N Viswanathan Seshadri Seetharaman
CSIRO, Process Science and Engineering, Australia Lule(a) Technical University, Sweden Royal Institute of Technology, Sweden
国际会议
Ninth International Conference on Molten Slags,Fluxes and Salts(第九届国际熔渣、溶剂与熔盐学术会议 MOLTEN12)
北京
英文
1-16
2012-05-27（万方平台首次上网日期，不代表论文的发表时间）