Research On Refining Slag Composition Optimizing And Industrial Practice Of Deep Desulphurization In LF

Being considered as one of high- efficiency methods of second refining, LF was in virtue some measures of heating up by the electric arc, reductive slag and argon blowing to achieve the aims of rapid deoxidation, desulphurization, mixing the temperature and components of liquid steel and removing the inclusion from the liquid steel availably, which played a very important role in pure steel development. It was very important to find out the optimum composition of refining slag and argon bottom blowing routine, which will offer a great significance on reducing the time of desulphurization, harmonizing the LD, LF and continuous casting and accelerating the production rhythm.Base on the composition of refining slag for No.2 steel plant in Anshan Steel, a model of quadratic regressive perpendicular design was developed to optimize the composition of a new-type refining slag in the paper firstly, and the effect of FeO content and slag amount on desulphurization capacity was carried out accordingly. Then, considering the optimum slag composition as the base, effect of industrial materials and Al ash-bearing refining slag on the desulphurization capacity was performed in the laboratory experiment, and comparison of desulphurization capacity of all kind of agents with different industrials materials was carried out in an intermediate frequency faradic furnace. The results showed that, In the case of FeO and MgO content being a constant, the desulphurization ratio increased firstly then decreased with w (CaO)/w (SiO₂) increasing. Under the condition of different slag basicity, the influence degree of Al₂O₃ and CaF₂ on desulphurization capacity was dissimilar. When the content of Al₂O₃ and CaF₂ accounted for much ratio in the refining slag, whether any element content increased continuously or not, the desulphurization ratio will decrease. In the process of production of ultra-low-sulphur steel, FeO content was suggested to be less than 0.5%, and slag amount not more than 20 kg·t^-1. In the condition of those experiments, the optimum composition of refining slag was w (CaO)/w (SiO₂) 9-11, Al-2O₃ content 27%²9%, MgO content 9%, CaF₂ content 8-10% and FeO content less than 0.5% respectively. For the desulphurization capacity comparison of types of Al ash-bearing refining slag, the desulphurization ratio was list in term of value as followings, electrolytic Al ash without fluorine, optimum refining slag, electrolytic Al ash being...