Physical Simulation Of Floating And Distribution Of Non-metallic Inclusions In Molten Steel

Ultra clean steel is one of the key technical of the steelmaking industry in recent years with the development of steelmaking technology.The quantity,size and distribution of inclusions in molten steel is an important index of purity steel.There are different types,sizes and shapes of the inclusions in the molten steel.The different types,sizes and shapes of the inclusions in the molten steel are constantly colliding,coalition,aggregation.The inclusions are constantly colliding.The collision between inclusions is the reason of the agglomeration of the inclusions and the distribution of the inclusions in the molten steel.The main mechanism of inclusion removal is self-floatation,aggregation and adsorption on the inner wall or bubble surface.At present,the majority of workers who study on inclusions floating aggregation behavior in the metallurgical simplified the inclusions as ideal spherical shape,but the morphology of inclusions is irregular in practices,and the ideal of inclusion are different.It is difficult to fully reflect the true inclusions in molten steel in the floatation and agglomeration behavior.In this paper,based on the similarity theory,the physical simulation system of ladle bottom argon blowing is established by using the similitude ratio as?=1:4,Based on the hydraulic model experiment of the 60t refining furnace,the effects of air blowing,time and particle size on the removal of inclusions and spatial distribution of inclusions were studied by using high-speed camera and professional image processing software(Iamge Pro-Plus).The results show that the best flow rate is 0.08 m~3/h in the ladle bottom blowing process.The inclusion removal law is similar with the time and the inclusions are basically removed in fourteen minutes.The inclusions from 200 to355?m are easier to be removed than the micro-inclusions from 105 to 150?m.Under the same process parameters,the influence of the number of inclusion particles on the rate of inclusion floating is small.The number of inclusions in gas-liquid two-phase region is less than that in other regions,and the characteristic size is larger.There is a weak flow zone at the far bottom of the gas permeable brick.The density of inclusions in this area is larger and it is not easy to be removed.Taking pictures at different time points and using professional image analysis software(Iamge Pro-Plus),Matlab software and the method of the box dimension,the fractal dimension of single particles and aggregates were calculated.The relationship between floating velocity of the actual inclusion and particle edge fractal dimension.under different flow rates are studied.The results showed that the fractal dimension of inclusion can be accurately calculated by the method of box dimension,the more complex the morphology of inclusion,the larger the fractal dimension;The more complex the inclusion is,the larger the fractal dimension is.The outline of the fractal dimension is small before the single most collision plastic particles,about 1.6,aggregate after collision with air blowing,blowing the smaller amount of relatively loose aggregates,the fractal dimension decreases,with increasing of flow is greater than the fractal dimension of fractal dimension of single particle is about 1.8.The increase of air blowing is beneficial to the collision agglomeration of inclusion,which makes the fractal dimension of the aggregates larger.The fractal dimension of inclusion is positively correlated with the actual velocity.This is consistent with the theoretical value calculated by the fractal dimension and the dynamic diameter,which shows that the method is accurate and feasible.