Study On Mixing Characteristics Of Bottom Blowing Ladle Furnace And Behavior Of Slag-Steel Interface

The bottom blowing process is one of the important means of secondary refining.It has important functions such as degassing,de-inclusion,and uniform molten steel composition and temperature.This refining functions has much to do with the flow characteristics of the fluid in the ladle.Due to the complex environment of the ladle refining process,it is very difficult to directly observe the flow behavior of the fluid in the ladle.Numerical simulation and physical simulation have become the main methods and means to study the ladle bottom blow refining.In order to study the effect of different bottom blowing conditions on the flow characteristics of molten steel in the ladle,this paper takes a 150 t ladle refining furnace as the research object,and adopts the research method combining numerical simulation and physical simulation : the three-dimensional multiphase numerical model was established,and the unsteady numerical calculation of the ladle bottom blowing was carried out using the software Ansys Fluent;according to the similarity theory,a physical model of ladle bottom blowing with a similarity ratio of 1:5 was established,and a water simulation test was carried out in the laboratory.The flow characteristics,mixing characteristics of the ladle and the variation law of the slag-gold interface were studied and analyzed.Research indicates:(1)When the two blowing positions are close,the dead zone of the ladle is likely to appear in the middle of the two blowing positions at the lower part of the ladle;as the distance between the two blowing positions increases,the dead zone is likely to be at the lower part of the ladle wall near the blowing position;when the distance between the blowing position and the center of the bottom of the bag is greater than 0.45 R,even if the blowing rate increases to 750L/min,the mutual influence between the air columns is small;when the blowing position is 0.6R,the erosion of the air column on the ladle wall is intensified.(2)Under the same blowing rate,the mixing effect of the 0.6R blowing position is generally better than that of the 0.3R and 0.45 R blowing positions.The mixing time decreases with the increase of the air blowing rate.When the air blowing rate exceeds 750L/min,the mixing time does not change significantly with the air blowing rate.(3)When the blowing position is close to the package wall,the erosion of the gas-liquid two-phase flow on the ladle wall is serious;When the blowing rate reaches 650L/min,the slag entrainment depth will not deepen;when the blowing rate reaches 750L/min,the drained liquid area will not continue to expand.The positions of the two bottom blowing are between0.45R～0.6R,and the blowing rate is between 550～750L/min,which is conducive to mixing the molten steel in the ladle and preventing slag entrainment.