Effect of oxygen volume fraction on the oxidation process of vanadium-titanium magnetite pellets
Increasing the pellet ratio of blast furnace is conducive to reducing pollutants and carbon emissions in the iron and steel industry.In order to make the oxidation rate of vanadium titanium magnetite pellets better applied in blast furnaces,this paper studied the influence of oxygen volume fraction on the oxidation rate of vanadium titanium pellets,analyzed the speed control link of the oxidation reaction by using the kinetic model,and analyzed the evolution law of phase composition and mineral phase structure during the oxidation process of vanadium titanium pellets.The results show that oxygen enrichment can promote the oxidation of vanadium titanium magnetite pellets,and the oxidation process of vanadium titanium magnetite pellets accords with the unreacted core model.The oxidation process is dominated by interfacial chemical reaction in the early stage and internal diffusion in the later stage.Oxidation degree of vanadium-titanium magnetite pellets decreases with increasing oxygen volume fraction when internal diffusion resistance is greater than the interfacial chemical reaction.The oxidation of vanadium titanium magnetite pellets is accompanied by the phase transformation process of Fe3O4→Fe2O3,Fe2.75Ti0.25O4→Fe2TiO4/FeTiO3→Fe9TiO15.During the preheating oxidation process,hematite crystal will appear,resulting in decrease in the porosity between minerals,increase in the resistance of diffusion in oxygen,and decrease in the oxidation reaction rate.
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