Influence Rules Of Mineral Structure On Metallurgical Properties For Blast Furnace Slag

In the blast furnace burden structure,the increase of sinter of low grade,high Al₂O₃ and Ti O₂ have resulted in the increasing content of high melting point mineral in blast furnace slag,which seriously affected the blast furnace anterograde.The flow properties of the slag are closely related to blast furnace anterograde.At present,the study on the flow properties of blast furnace slag is limited to the inf luence of chemical composition.However,the relationship between the mineral phase structure and the flow properties of blast furnace slag,from the study of blast furnace slag technological mineralogy,has not been reported systematically.Therefore,the effect of the phase structure of blast furnace slag on the flow properties(viscosity,melting temperature)of blast furnace slag is studied.The mineralogical structure of blast furnace slag in Pan Zhihua,Chengde,Handan and Tangshan Iron and Steel Co.,Ltd.is studied by polarizing microscope and X-ray diffraction.The results show that the mineral compositions are composed of the melilite,perovskite,a small amount of rich titanium diopside,a trace amount of metal iron,Ti C,Ti N and their solid solution in high titanium and medium titanium blast furnace slag.The mineral compositions are composed of the rich titanium diopside,melilite,next perovskite,and a little of metallic iron,magnesia in ordinary blast furnace slag.The microstructure of blast furnace slag is mainly porphyritic,and different microstructures and porphyries are different,resulting in different viscosities of slag in molten state.By studying the viscosity and melting temperature of blast furnace slag,the viscosity of blast furnace slag is found to decrease with the increase of temperature.In the high temperature region of1480-1450?,the viscosity of blast furnace slag with high titanium is the highest,and the viscosity of blast furnace slag of medium titanium is the second,the viscosity of ordinary blast furnace slag is the smallest.When the temperature dropped to 1400?,the viscosity of ordinary blast furnace slag is the highest,the viscosity of titanium slag was the second,the viscosity of high titanium slag is the smallest,and the viscosity of high titanium slag has remained basically unchanged.The melting temperature of the high-titanium blast furnace slag is the highest and the melting temperature of the medium titanium blast furnace slag is the lowest,which are respectively 1400?and 1320?.The phase diagram of Si O₂-Al₂O₃-Ca O-Mg O-Ti O₂ slag and the law of crystallization of the blast furnace slag are simulated by Fact Sage software,which is consistent with the observation through polar izing microscope.Titanium nitride,titanium carbide and their solid solution are all high melting point minerals in high titanium blast furnace slag,w hich is the main factor that causes the slag viscosity to increase.Not only its own influence on the slag thickening,but also granular,strip-like distribution in the metal around the formation of solid iron shell,to promote the viscosity of blast furnace slag larger,resulting in a large amount of iron in the slag.The influence of perovskite on the viscosity of slag is inferior to that of the former.The dendritic or reticular structure of the perovskite deteriorated the fluidity of the slag and promoted the viscosity of the slag.Figure36;Table17;Reference 68...