Physical And Mathematical Modeling Of Ladle Furnace Refing Process With Bottom Argon Blowing

A physical modeling system was set up from the similarity theory for the bottom blowing argon process in a110t ladle furnace to study the refining process of LF. The physical model experiment was performed in1:5scale to investigate the influence of gas flow rate on the flow field, mixing and mass transfer. The effect of the thickness and viscosity of slag as well as the pool depth on the exposed surface and the critacal slag entrapment was disscussed. Also, removal of inclusions in the ladle furnace was studied. The flow field while blowing argon in the ladle was numerically simulated. And the influence of gas flow rate on the complete mixing time of the alloy was calculated. The main conclusions were shown as follows:(1) During the process of argon blowing from the bottom of LF, there was an inflection point(250NL/min) on the curve of the relationship between gas volume and mixing time. Before the inflection point, with increase of argon flow rate, the complete mixing time became shorter. After the inflection point, the complete mixing time did not change significantly with the increase of argon flow rate. During tapping process, the argon flow rate did not have strong impact on the complete mixing time.(2) The physical modeling experiment suggested that under the same conditions, the thicker slag, the smaller the exposed surface. For the case of small volume(<200NL/min), the deeper the liquid steel, the smaller the exposed surface. While for the case of large volume, the deeper the liquid steel, the bigger the exposed surface. Under the same conditions, the higher viscosity, the smaller the exposed surface. The critical slag enrtapment experiment showed that the thicker the slag layer, the lower viscosity and the shallower the liquid steel, the easier became the slag enrtapment.(3) The experiment of the removal of inclusions in the ladle furnace showed that the removal of inclusions mainly occurred in the first8minutes after blowing. During the first0-4min the speed of removing inclusions was the fastest, the maximum removal rate was about25%. Until blowing to the seventh4min, the removal rate was all below5%. Extending the blowing time did little effect. The optimal bottom argon blowing volume was50NL/min and the the maximum removal rate was75%in this subjiect.(4) The results of the mathematical model showed that a large and a small circular motion were generated in the ladle with eccentric bottom blown argon, the small one of which is severer than the large one. The cycle center was at about0.75H-0.80H from the bottom and stayed unchanged under different bottom blowing volume. The results showed that the optimal bottom blowing volume was250NL/min. Under the bottom blowing volume, better mixing was obtained in the pool, the proportion of weak flow region became smaller and the mixing time became shorter. Also the gas volume of critical slag enrtapment was calculated as120NL/min, which is similar to the results of the physical simulation.