Experimental Research On Effect Of Electromagnetic Field On Slag-Metal Interfacial Reaction Kinetics

Slag-metal interfacial reaction is one of the most important multiphase reactions in metallurgical industry, so improvement on slag-metal interfacial reaction kinetics is beneficial to promotion of metallurgical efficiency. Traveling magnetic field and high magnetic field can effectively influence the behaviors of liquid metal so as to change the slag-metal interfacial reaction kinetics greatly, while most of the researches on application of electromagnetic stirring in ferrous metallurgy mainly focused on continuous casting process, and researches on effect of high magnetic field on slag-metal interfacial reaction are quite limited so far. Therefore, slag-metal interfacial reactions with imposition of traveling magnetic field (electromagnetic stirring) and high magnetic field were investigated experimentally with support of national natural science foundation projects of china to study influence mechanism of electromagnetic field on slag-metal interfacial reaction kinetics.Desulphurization in hot metal pretreatment is a typical slag-metal interfacial reaction in ferrous metallurgy. Desulphurization experiments with different electromagnetic stirring intensity and stirring types were investigated, and the volume mass transfer coefficients corresponding to different stirring conditions were determined finally. The experiment results show that desulphurization rate of hot metal differed with electromagnetic stirring types, and electromagnetic stirring could change the interfacial state and boundary layer thickness of sulphur mass transfer so as to promote the desulphurization process. The contacting area and contacting time of desulphurizer and hot metal would increase greatly when the desulphurizer was carried into hot metal with argon. The volumetric mass transfer coefficient of sulphur in desulphurization experiment with rotating electromagnetic stirring was very large, and the desulpurization efficiency in the desulphurization process was improved greatly. The environment-friendly technology has potential to be widely used in metallurgical industry.The effect of electromagnetic stirring on slag-metal interfacial reaction kinetics is mainly caused by promotion of electromagnetic stirring on liquid metal behaviors (internal flow, free surface shape, level fluctuation, etc.)-Internal flow of Pb-Sn-Bi alloy was successfully measured with ultrasonic Doppler velocimetry for the first time in order to further study flow field of liquid metal exposed to various electromagnetic stirring types. Furthermore, free surface shape and level fluctuation of liquid metal exposed to various electromagnetic stirring types were measured and analyzed with laser liquid level apparatus in order to quantify the effect of electromagnetic stirring on slag-metal interfacial reaction kinetics in this study. The results showed that effect of electromagnetic stirring on internal flow and level fluctuation of liquid metal differed with electromagnetic stirring types, so different electromagnetic stirring types should be introduced to meet technological requirements. The study also provides evidence for stirring parameter adjustment. Due to the physical properties of Pb-Sn-Bi alloy are similar to molten steel, this study is of important guiding significance for research on metallurgical kinetics under the imposition of magnetic field.The internal flow distribution of liquid metal on slag-metal interface was measured and analyzed with ultrasonic Doppler velocimetry for the first time to determine the important metallurgical parameters such as critical velocity of slag entrapment as well as the relevant parameters of actual ladle furnace. The results showed that the maximum horizontal velocity on the slag-metal interface increased parabolically with the increase of stirring intensity. The determined critical velocity of slag entrapment, weber number, magnetic field intensity in molten steel next to electromagnetic stirrer and magnetic field intensity in the center of ladle furnace were800mm/s,20,0.023T and0.0023T respectively. Different electromagnetic stirring intensity should be introduced to meet different refining requirements according to the critical velocity of slag entrapment.On the other hand, rate of slag-metal interfacial reaction in high magnetic field under different conditions was investigated to make sure of how the high magnetic field influence every step in the reaction process on slag-metal interface and the global reaction rate. The reaction rate between Al-Cu alloy and quaternionic slag revealed that the reaction rate was quickened owing to the micro-MHD effect if the high magnetic field applied to the reaction interface is of zero gradient, while the reaction rate changed in gradient magnetic field because the reaction interface was under the action of both the magnetization force evoked by the magnetic field and micro-MHD effect. A conclusion is thus drawn that the reaction rate on slag-metal interface can be controlled efficiently via high magnetic field.