Research On The Carbothermal Reduction Of Fe-Ti-O System Doping With Magnesia Oxide

Chinese holds abundant vanadium-titanium magnetite resources.It is one of the important raw materials for the steel industry.Vanadium-titanium magnetite has many characteristics such as complex structure,various components,and various kinds of impurity oxides.These characteristics restrict the processing and utilization of valuable elements in it.The presence of magnesium oxide in the mine has a greater impact on the reduction.In this paper,we take synthesized FeTiO₃,Fe₂TiO₄,Fe₂TiO₄-Fe₃O₄ as raw materials,though isothermal reduction and non-isothermal reduction experimental methods,based on thermodynamic calculations and combined with analytical detection technologies like scanning electron microscopy-energy dispersive spectroscopy?SEM-EDS?,X-ray diffraction?XRD?to research on the carbon thermal reduction rules in the Fe-Ti-O system doping with magnesia oxide?MgO?.The main contents are as follows:Under the condition of non-isothermal reduction,doping magnesium oxide increased the reaction fraction of FeTiO₃.The reaction fraction gradually decreased when the doping amount of MgO exceeded 2%.Compared with the undoped MgO sample,doping MgO reduces the temperature required for the reduction reaction.Isothermal reduction studies have shown that the metallization rate of FeTiO₃ doped MgO is better than that of undoped MgO,and the preferred MgO doping amount is 4%.During the reduction process,the volume of the unit cell trend to increase and the iron particles of the sample which doped with magnesium oxide are coarser,magnesium exists as?Fe,Mg?TiO₃,?Fex,Mg1-x?Ti₂O₅,Mg_xT_i3-xO₅.With the reaction fraction of 0 to 20%,the control link is changed from FeTiO₃carbon reduction reaction control to carbon gasification reaction control.Doping magnesia oxide reduces the activation energy required for the reaction,but does not change the reaction restriction.Research on carbon-thermal reduction of Fe₂TiO₄ doped MgO through non-isothermal reduction shows that the doping of MgO significantly reduces the Fe₂Ti O₄ reaction fraction.The reaction fraction of Fe₂TiO₄ with 4%doped MgO is the lowest,which is 67.67%.As the doping amount increases,the metallization rate decreases first and then increases.In the reduction process,the control links in different temperature zones in order are:chemical reaction control,diffusion control,diffusion and chemical reaction control,and chemical reaction control.Doping MgO extends the chemical reaction control temperature interval.The stability of Fe₂TiO₄ samples doped with MgO is better.After reducing to1100°C,Fe₂TiO₄ is gradually deoxidized to FeTiO₃,FeTi₂O₅ and TiO₂,and iron particles begin to be enriched obviously.When the Fe₂TiO₄-Fe₃O₄ was doped with MgO,the phase of MgFe₂O₄ was produced.In one hand,the Fe₂TiO₄-Fe₃O₄ was reduced to phase of Fe₂TiO₄,Fe TiO₃,FeTi₂O₅,TiO₂,meanwhile the iron was separated out.In the other hand,the MgO was produced by the Fe₂TiO₄ reaction with MgFe₂O₄ and C,and the iron was reduced.In the non-isothermal reduced process,the reaction fraction and metallization rate of sample doping with MgO were deceased gradually.The highest reaction rate was 0.707%·?^-1.After reduction of more than 1100?,the iron particles was enriched gradually,and the iron particle was big and dispersed.In the process of isothermal reduction,the reaction fraction was improved gradually with the increase of the doping amount.Under reducing 5 minutes,the iron particles increases gradually.The transformation of crystal type was in turn:tetragonal system,trigonal system,orthorhombic system.