Factor analysis and process optimization of stainless steel desulfurization process
REN Ying1, ZHANG Lifeng2
1. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 2. School of Mechanical and Materials Engineering, North China University of Technology, Beijing 100144,China
Abstract：In the current study,the whole process of 304 stainless steel production was investigated through industrial trial,and the change of sulfur content in steel at the AOD start,decarburization,AOD end,and LF end was analyzed and studied. The correlation between different processes and final sulfur content was determined through machine learning,and it was found that LF refining process had a greater impact on desulfurization. The LF refining was determined as the key optimization process for desulfurization of 304 stainless steels. Thermodynamic calculations were conducted to predict the reaction between the refining slag and the molten steel using the FactSage Macro Processing. With the increase of slag basicity during the LF refining,the sulfur distribution ratio of slag and steel in the LF refining increased obviously,and the sulfur content in steel decreased. Meanwhile,with the mass percent of Al2O3 in slag increasing from 10% to 30%,the sulfur distribution ratio between slag and steel decreased,and the sulfur content in steel increased.Increasing the basicity of the refining slag and decreasing the Al2O3 content were beneficial to lower the sulfur content in 304 stainless steel and improve the sulfur distribution ratio between slag and steel. A kinetic model was established for the reaction between the refining slag and the molten steel during the LF refining process. The slag-steel reaction model in the LF refining process included three reaction steps: the first step was mass transfer from the bulk steel to steel boundary layer,the second step was mass transfer from the bulk slag to slag boundary layer,and the third step was the interfacial equilibrium chemical reaction between slag boundary layer and steel boundary layer. The increase of the slag basicity was beneficial to reduce the sulfur content in steel and improve the desulfurization rate. The sulfur content after reaction rose up with the increase of initial sulfur content. A higher flow rate of argon blowing in the ladle enhanced the reaction rate,while it has little effect on the sulfur content in steel. With the increase of the initial sulfur content in steel from 0.006% to 0.012%,the sulfur content in steel also increased after the reaction,and the initial sulfur content in steel had little effect on the desulfurization rate.
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2023, Vol. 58 
