Optimization of converter dephosphorization process by simulation calculation based on FactSage

Abstract:

Dephosphorization has always been a high concern in the metallurgical industry. The melting temperature has a great impact on dephosphorization. Exploring the influence of main components in liquid steel on the melting temperature and the influence of different component contents on the liquid phase zone have laid a theoretical foundation for further optimizing dephosphorization process parameters. Therefore, this paper combines dephosphorization theory with factsage software for simulation calculation, the effects of CaO, SiO2, P2O5, MgO and FeO contents on the melting temperature are studied, and finds the best slag content combination through single factor analysis, orthogonal experimental analysis, analysis of variance and phase diagram analysis. The experimental results show that the melting temperature decreases with the increase of SiO2 concentration, the melting temperature increases with the increase of CaO concentration, the complete melting temperature decreases when MgO is between 3%~7.5%, and the melting temperature decreases with the increase of P2O5 concentration. CaO has the greatest influence on the initial melting temperature, and SiO2 and FeO have the greatest influence on the complete melting temperature. At the lowest initial melting temperature, the lowest values of various factors are: CaO=26%, SiO2=24%, FeO=21%, P2O5=9.8%, MgO=9%, and at the lowest complete melting temperature they are: CaO=38%, SiO2=22.5%, FeO=18%, P2O5=5.3% and MgO=3%. The effects of CaO content on FeO-SiO2-P2O5 phase diagram, FeO content on CaO-SiO2-P2O5 phase diagram and SiO2 content on the liquid phase region of CaO-FeO-P2O5 phase diagram are analyzed and compared. The results show that with the increase of CaO content, the temperature of liquid phase region in FeO-SiO2-P2O5 system increases, and the liquid phase region at 1800 ℃ expands. The increase of FeO content has an obvious effect on the liquid phase region of CaO-FeO-P2O5 system, especially in the range of 15%~18%, the temperature range of 1600 ℃ continues to expand, and the temperature range of 1400 ℃ and 1600 ℃ increases. The increase of SiO2 content has the least effect on the liquid phase range of CaO-FeO-P2O5 system, that is, it increases the melting temperature, which reduces the content of P2O5 in the slag and is conducive to dephosphorization.