Fluidity And Structure Of CaO-SiO₂-MgO-Al₂O₃-FeO Bosh Slag In Blast Furnace

Blast furnace iron making is the process of reducing iron ore?sinter,pellet,lump ore?,softening melting and slag iron separation to obtain liquid metal iron.The soft melt zone and slag iron drop zone formed by iron ore softening and melting directly affect the fuel consumption and smelting efficiency of blast furnace.The properties of iron ore in soft melt zone and drip zone are related to the physical properties of intermediate slag.However,at present,there is a lack of physical property data of bosh slag composed mainly of CaO-SiO₂-Al₂O₃-MgO-FeO,which makes it impossible to correctly understand the phenomenon of iron ore soft melt dropping.Therefore,it is necessary to investigate the physical properties of CaO-SiO₂-Al₂O₃-MgO-FeO bosh slag,so as to provide theoretical basis for further research on the behavior of iron ore soft melt dripping.In this paper,10%FeO-CaO-SiO₂-MgO-Al₂O₃ slag,C/S=1.4 was studied.MgO content was 6%¹6%and Al₂O₃ content was 6%¹6%.The effects of MgO,Al₂O₃and MgO/Al₂O₃ on slag viscosity were measured.The influence of MgO and Al₂O₃with different contents on the fluidity and metallurgical properties of slag was judged by the stability temperature of slag and viscous flow activation energy.The relationship between slag structure and viscosity was investigated by means of XRD and infrared spectroscopy.Through FactSage Viscosity in the module and Phase Diagram calculation module,compared with the experimental determination of the slag Viscosity.In conclusion,the results show that:in the 10%FeO-CaO-SiO₂-MgO-15%Al₂O₃slag,When MgO content is 12%,slag viscosity reaches the minimum,in the10%FeO-CaO-SiO₂-10%MgO-Al₂O₃ slag,when the content of Al₂O₃ is 12%,the slag viscosity is the lowest;when MgO/Al₂O₃ is between 0.7 and 0.8,slag has good fluidity and metallurgical properties.When the content of MgO and Al₂O₃ are 10%,the activation energy of slag is the minimum and the performance of slag is the most stable.When Al₂O₃ content was 15%and MgO was 12%,the activation energy of slag was the minimum.The phase diagram and viscosity law of five-element slag system were calculated by FactSage.It is found that the simulated viscosity calculated by FactSage is basically the same as the measured viscosity.Through the simulation calculation of slag phase diagram,the viscosity law of slag is explained from the change of slag phase.At 1773K,when Al₂O₃ content was 6%and 8%,Merwinite was present in the slag system.In 10%FeO-CaO-SiO₂-MgO-15%Al₂O₃ slag system,when the content of MgO is 16%,MgO phase exists in the slag system.When the content of MgO reaches 12%,the total amount of Q₀ and Q₁ is the largest,resulting in the minimum viscosity of slag.When the content of MgO is more than12%,the influence of MgO on the silicate system is small,and the increase of slag viscosity is due to the appearance of MgO phase in the slag.When the content of Al₂O₃ reaches 12%,the total amount?Q₀+Q₁?is the largest and the slag viscosity is the smallest.When the content of Al₂O₃ is more than 12%,the total amount of slag?Q₀+Q₁?decreases slightly and the viscosity of slag increases due to the amphiphilic effect of Al₂O₃.