Study On Dephosphorization Of High Phosphorus Hot Metal Based On CaO-Si O₂-Al₂O₃-Fe₂O₃-MgO Slag System

China is the country with the largest consumption of iron and steel in the world.The country's infrastructure,roads,railways,bridges and so on all need a large amount of steel.For a long time,a large amount of high-quality iron ore resources have been imported from abroad.However,as the international iron ore price increases year by year,the cost of imports of iron ore are increased and the pressure of iron and steel enterprises are the same.How to effectively use low-grade iron ore has become a problem faced by iron and steel enterprises and scientific researchers.High phosphorus hematite is widely distributed in our country.The use of these iron ores leads to the increase of phosphorus content in molten iron.In order to solve the dephosphorization problem of medium and high phosphorus hot metal,this paper studies the influence of basicity,Fe₂O₃ and Al₂O₃ content of CaO-SiO₂-Al₂O₃-Fe₂O₃-Mg O slag system on dephosphorization effect of hot metal,analyzes the influence of B₂O₃,Li₂O,La₂O and Ca F₂ as dephosphorization flux on dephosphorization effect of molten iron,and studies the influence of CaO-SiO₂-Al₂O₃-Fe₂O₃-Mg O slag system on magnesium carbon The main conclusions are as follows:(1)The melting temperature and viscosity of CaO-SiO₂-Al₂O₃-Fe₂O₃-Mg O slag system gradually decrease with the increase of basicity of slag system,first decrease and then increase with the increase of w(Fe2O3),and then increase with the increase of w(Al2O3).When the basicity R of slag system is 4.5,w(Al₂O₃)=3%,w(Fe₂O₃)=55%,the melting temperature of slag system is relatively low(1427.18?).(2)With CaO-SiO₂-Al₂O₃-Fe₂O₃-Mg O slag system for dephosphorization of high phosphorus molten iron,the dephosphorization rate of slag system increased first and then decreased with the increase of basicity of slag system,increased with the increase of w(Fe₂O₃)and decreased with the increase of w(Al₂O₃).The dephosphorization rate of CaO-SiO₂-Al₂O₃-Fe₂O₃-Mg O slag system is 88.57%when w(Fe₂O₃)=55%,w(Al₂O₃)=3%,w(Mg O)=5%and R=4.0.(3)With the increase of B₂O₃ content,the dephosphorization rate of CaO-SiO₂-B₂O₃-Fe₂O₃-Mg O slag system decreases gradually.With the increase of Li₂O content,the dephosphorization rate of CaO-SiO₂-Li₂O-Fe₂O₃-Mg O slag system increases gradually.when the slag system R=4.5,w(Fe₂O₃)=55%,w(Mg O)=5%and w(Li₂O)=9%,the dephosphorization rate of slag system can reach 95.27%.With the increase of Ca F₂ content,the dephosphorization rate of CaO-SiO₂-Ca F₂-Fe₂O₃-Mg O slag system increased at first and then decreased.With the increase of La₂O₃ content,the dephosphorization rate of CaO-SiO₂-La₂O₃-Fe₂O₃-Mg O slag system gradually increased.When the slag system R=4.5,w(Fe₂O₃)=55%,w(Mg O)=5%,w(La₂O₃)=9%,the dephosphorization rate of slag system exceeded 90%.Using Li₂O and La₂O₃ as fluxing agents,better dephosphorization effect can be obtained.(4)There are well-defined magnesia-carbon brick layer,transition layer and slag layer at the interface after erosion of magnesia-carbon brick.In the experiment of studying the erosion of Cao-SiO₂-Al₂O₃-Fe₂O₃-Mg O-Mn O-P₂O₅ slag system on magnesia-carbon brick,the erosion of magnesia-carbon brick intensified with the increase of basicity and Fe₂O₃ and Al₂O₃ content in slag system.