.40 Tons Of Lf Refining Slag System Optimization And Research

Because the slag system of CaO-Al₂O₃-SiO₂-MgO used for the refining by the first steel-making factory belong to Hengsteel Corporation can not meet the needs of production, In this thesis have been designed and researched new refining slags onsisted of CaO,Al₂O₃,SiO₂,MgO and CaF₂.Two new slag systems with strong desulphurization and deoxidization ability have been found. One of two is slag A onsisted of CaO 40～50%,Al₂O₃ 30～40%,SiO₂ 10～20% and MgO 4～6%,with the characteristics of low content of CaO and high Al₂O₃. Another slag system is slag B onsisted of CaO 50～60%,Al₂O₃ 15～25%,SiO₂ 5～15%, MgO 6～10% and CaF₂ 0～5%, with the characteristics of high basic and low content of SiO₂.Both of the slag systems have good foaming ability. The foaming ability of slag A is better if CaF₂ is added in it. The expected effects have been obtained in the commercial experiment: both melting point and viscosity of this slag is in perfect limits, inclusion can be actively eliminated, slag has strong desulphurization and deoxidization ability; The quality of refining steel have been improved greatly: the big inclusion content in steel is lower than 15mg/10kg, sulphur and oxygen can be controlled to be lower than 100 and 30ppm or 50 and 20ppm, respectively, due to different material addition. In addition this type of slag is cheap. So this type of slag can be meet the needs of refining different steel.