Fundamental Research On Application Of Magnesium Slag For Low-silicon Hot Metal In Steelmaking Processes

Compared with conventional iron,low-silicon hot metal steelmaking can effectively reduce the consumption of steel and slag-making agent and reduce the amount of steel slag,but in the smelting process is prone to slagging difficulties,lack of heat,low phosphorus removal efficiency and other problems.Based on this,this study uses the characteristics of magnesium slag component structure and low-silicon hot metal steelmaking slag-making material similar to the characteristics of the proposed magnesium slag as a low-silicon hot metal making process slag-making agent,can reduce lime material consumption,reduce production costs,but also optimize the slag system structure,rapid slagging,improve the dephosphorization effect;at the same time to achieve the resource utilization of magnesium slag,to solve the problem of a large number of magnesium slag pile,difficult to be applied on a large scale.Factsage software was used to study the mechanism of lime melting and phosphorus enrichment in low-silicon hot metal smelting,to investigate the route of slag formation in low-silicon hot metal smelting,and to clarify the physical requirements of slag-making materials in low-silicon hot metal steelmaking.The physical and chemical properties of magnesium slag were analysed and it was found that Ca O in magnesium slag components can reduce lime consumption,Mg O could reduce furnace lining erosion,Si O₂,Al₂O₃ and Fe₂O₃ could lower the melting point of slag and increase oxidation,which can improve the effect of dephosphorisation in low-silicon hot metal steelmaking,and the slag-making agent composition was designed based on the composition of magnesium slag in the application process,so that its melt characteristics could meet the requirements of low-silicon hot metal steelmaking.Based on the above analysis results,Factsage software was used to study the effect of different component changes in Ca O-Si O₂-Fe₂O₃-Al₂O₃-Mg O type magnesium slag slagging agent on its melting characteristics,and it was found that its basicity of 1.5～3.5can meet the steelmaking dephosphorisation conditions,and increasing the Fe₂O₃ content could improve the oxidation of slag and promote the formation of phosphorus-rich phase,but Fe₂O₃ content Too high would accelerate the phosphorus-rich phase melting,resulting in P₂O₅ re-entering the liquid slag,which was not conducive to dephosphorization.Appropriate increase of Al₂O₃ content could promote lime melting and accelerate slag formation,while to reduce lining erosion,the Mg O content in the magnesia slagging agent was set at 6%.In summary,a suitable range of Mg O slagging agent components was obtained,specifically Ca O:30%～64%,Si O₂:10%～33%,Fe₂O₃:10%～30%,Al₂O₃:2%～12%,Mg O:6%.A thermal experiment was designed using the response surface method for the dephosphorisation of low silicon hot metal with magnesium slag slagging agent.The effect of the different components of magnesium slag slagging agent on the dephosphorisation rate was found to be Fe₂O₃>basicity>Al₂O₃,with the interaction between basicity andω（Fe₂O₃）having the most significant effect on the dephosphorisation rate.The maximum phosphorus removal rate of 96.7%was achieved when the components of magnesia slagging agent were R=2.8,ω（Fe₂O₃）=25.94%,ω（Al₂O₃）=6.73%andω（Mg O）=6%,and the error was 2.6%after experimental verification,which indicated that the response surface method was meaningful for the optimization of the components of magnesia slagging agent and provided theoretical support for the use of magnesia slag for low-silica hot metal smelting in converters.