Study On The Behavior Of Powder Penetrating Gas-liquid Interface In Ladle With Bottom Powder Injection

Adding alloy in ladle refining to adjustment the composition can improve the comprehensive performance of steel such as strength and plasticity.In the refining process,it is very important to reduce the alloy loss,stabilize the yield of alloy and enhance the homogenization of the alloy.And,refining in ladle with bottom powder injection has significant advantages in strengthening stirring,accelerating chemical reaction and improving alloy yield in molten pool and can provide strong support for the construction of clean steel platform.So,it has great development potential.In the refining process with bottom powder injection,there are still many uncertainties in the transportation and the movement behavior of powder after entering the ladle.Therefore,it is of great theoretical significance for the practical application of refining process in ladle with bottom powder injection to explore the gas-liquid interface behavior of powder penetration.In this paper,the bubble motion,mixing time and powder penetration ratio in the process of bottom blowing argon and powder injection in ladle were studied by water model.Based on the force of the powder in the molten pool,the penetration rate model of the powder at the gas-liquid interface was established,and the penetration behavior of a single powder was numerically simulated.Finally,a mathematical model of gas-solid-liquid multiphase flow in the powder injection process was established.The effects of solid-gas ratio,powder characteristics,gas flow rate and injection position on the distribution of powder and the utilization rate of powder in the molten pool were investigated.The results show that:(1)As the gas flow rate increases,the mixing time decreases.When the gas flow rate exceeds 11.4 L/min,the reduction in mixing time becomes less pronounced.When using a single porous element for argon blowing in a ladle,the best mixing effect is achieved when the element is positioned at 0.67R.For dual porous elements blowing at a brick angle of 135°and distributed at 0.67R,the shortest mixing time of 34 s is achieved with the gas flow rate of 15.3 L/min.Furthermore,as the blowing rate increases,the bubble rise velocity also increases.At the blowing rate of 7.6 L/min,the bubble velocity is 0.447m/s,and it reaches 0.84 m/s when the blowing rate is increased to 19.1 L/min.Meanwhile,the bubble sizes under various conditions were statistically analyzed,revealing that the bubble sizes are mainly concentrated in the range of 1～3 mm.(2)In the study of powder penetration ratio,it was found that increasing the solid-gas ratio and the powder particle size can effectively increase the powder penetration ratio.When the solid-gas ratio is 5 and the powder particle size is in the range of 0.212 to 0.38mm,the powder penetration ratio can reach 78%,which is approximately 40%higher than the solid-gas ratio of 3.5.The powder penetration ratio for a particle size range of0.212 to 0.38 mm is also about 20%higher than that of a particle size range of 0.12 to0.15 mm.(3)The phenomenon of powder penetration into bubbles occurs when there is a velocity difference between the bubbles and the powder.The larger the velocity difference,the faster the powder penetration behavior occurs.When the velocity difference increases from 0.6 m/s to 1.2 m/s and 1.8 m/s,the time for powder penetration decreases from 5 ms to 2.4 ms and 1.6 ms,respectively.In terms of the initial diameter of the bubbles,smaller bubbles make it easier for the powder to penetrate the gas-liquid interface,and the change in powder velocity before and after penetration is smaller compared to larger bubbles.Regarding the characteristics of the powder itself,the density of the powder has little influence on powder motion,while the particle size of the powder significantly affects powder motion.Larger powder particle size allows for faster powder penetration.(4)The solid-gas ratio has a relatively small impact on the uniformity of powder distribution in the molten pool,but increasing the solid-gas ratio reduces the proportion of powder captured by the liquid surface.Decreasing the particle size of the powder leads to a more uniform distribution in the molten pool,and the proportion of powder captured by the liquid surface decreases.When the powder density is 1400 kg/m~3,it is distributed more uniformly in the molten pool,with the proportion of powder captured by the liquid surface being 1.2%.Additionally,dual porous bricks are more favorable for the uniform distribution of powder compared to a single porous brick,and the proportion of powder captured by the liquid surface at 135°-0.67R is 2.5%lower than that at 180°-0.67R.