Experimental Study On Foaming Slag For Steel Refining And Physical And Mathematical Simulation Of LF Process

Based on the experimental study on LF foaming slag for steel refining and physical mathematical simulation to the main metallurgy processes of ladle furnace, analysis was accomplished in detail to certain ladle furnace in a domestic steel company.The technology of foaming slag refining is a effective method to improve heating efficiency and reduce the cost. Because of the characteristic of ladle furnace, its slag foaming technology is different form other metallurgy equipments. Relationship between slag foaming capability with ingredients of slag was researched in experiments, so did the refining capability of foaming slag. According to the results, there is some conflict between slag foaming and desulphurizing capabilities. The composition extension of foaming slag for steel refining was obtained: w(CaO)45～60%, w(Al2O3)30～40%, w(SiO2)10～15%, w(MgO)5～10%, w(CaF2)<5%.Foaming agent was necessary in ladle furnace because its reducing condition. As foaming agent, carbonates were superior to carbide. And better result would be acquired if composite agent was used. Additionally, action mechanism of foaming agent should be understood on aspects both supplying of gas and changing to the physical property of molten slag.Compared with ordinary bottom stirring ladle, heating arc and much more slag are main differences of ladle furnace. Water model study to the specific dimension LF was completed in research according to similarity principle for physical simulation, emphasis laid on the influence of arc phenomenon and foaming slag. Arc phenomenon is a obstacle to ladle bottom stirring, especially in case of centre blowing. Foaming slag is liable to generate slag drop when bottom stirring, so slag entrapment is much easier to be observed in LF. Under such experimental conditions, the critical gas-blowing rate for slag entrapment is about 0.3m3h-1.As to blowing mode, the manner with less gas rate in wall-nearer nozzle is better when double nozzles blowing, but it was not much effective than off-center blowing with single nozzle.The mathematical models of main LF metallurgical processes were obtained (temperature prediction model, removal model of non-metal inclusion, LF desulphurization prediction model). The comparison between calculated results and actual data shows that the obtained models were corresponded with the actuality. So the models were reliable for theoretical analysis of certain LF process.Calculated results of temperature prediction model showed, much higher input power and foaming refining technology should be used to achieve the production requirement. In treat process, slot of the most temperature gradient is the time adding refining slag. If excessive slag were added into ladle, there would be some difficulty to achieve end-point temperature. Therefore, utilization of...