Physical Modeling Of Mixing And Inclusion Removal Behaviors In A Refining Ladle With Bottom Blowing

Bottom blowing argon technology is widely used in refining ladles with the advantages of good uniform conditions of molten steel temperature and composition, high inclusions removal, improved yield rate of alloying elements, low cost and so on. Mixing time is an important parameter and has a great influence on refining effect, homogeneity of composition and temperature of molten steel, the speed of inclusions removal and so on. Inclusion is harmful to steel, and reducing the content of inclusion is the most important issue in steelmaking.After a comprehensive analysis of the research methods of mixing characteristics and the inclusion behaviors, a physical modeling system was set up based on the similarity theory for the bottom blowing argon process in an 80t ladle furnace to study the mixing time and inclusion removal behaviors. Three points were selected to measure the changes of tracer concentration and determine the mixing time in ladle. Mixed oil was used to simulate the slag layer, and small solid particles were selected to simulate the inclusions. RC-3000 particle counter was applied to measure the concentration of inclusions in molten steel. The influences of plug types, gas flow rate and the install position of plugs on mixing and inclusions removal were studied through physical simulation. The main conclusions were shown as follows:(1) For the slot plug, the mixing time of double-blowing is shorter than that of single-blowing. For the porous plug, the mixing time of single-blowing is shorter than that of double-blowing in small gas flow rate (50NL/min-250NL/min), and the mixing time of double-blowing is shorter when the gas flow rate is over 300NL/min.(2) For blowing process with double plugs, the mixing time of the ladle with slot plug is shorter than that of the one with porous plug when blowing with a small gas flow rate(50NL/min-250NL/min). The plug type has a small effect on the mixing time in ladles when the gas flow rate is over 300NL/min.(3) The variation of inclusion removal rate with time is similar in the condition of various gas flow rates, namely, the inclusions removal rate rises quickly first and then changes slowly. For the porous plug, the install position has a little has a small effect on the inclusion removal rate when blowing with a small gas flow rate (20NL/min?100NL/min), The inclusions removal rate of double-blowing is obviously higher than that of single-blowing when the gas flow rate is over 150NL/min.(4) Blowing with double plugs, the inclusion removal rate of slot plug is slightly higher than that of porous plug when blowing with a small gas flow rate (20NL/min?100NL/min). The inclusion removal rate of porous plug is higher when the gas flow rate is over 150NL/min. Blowing with double plugs, there is a few differences between the inclusion removal rate of slot plug and porous plug. The ladle bath depth has a little effect on the removal rate of inclusions. Therefore, the top slag of ladles would plays a more important role in inclusion removal.