氧气体积分数对钒钛磁铁矿球团氧化过程的影响

Effect of oxygen volume fraction on the oxidation process of vanadium-titanium magnetite pellets

提高高炉球团配比有利于降低钢铁行业的污染物和碳排放,为了使钒钛磁铁矿球团在高炉中得到更好的应用,本文研究了氧气体积分数对钒钛球团氧化速率的影响,利用动力学模型分析了其氧化反应的控速环节,分析了钒钛球团氧化过程物相组成、矿相结构等演变规律。结果表明:富氧能促进钒钛磁铁矿球团的氧化,钒钛磁铁矿球团的氧化过程符合未反应核模型,氧化过程前期以界面化学反应控速为主,后期以内扩散控速为主,内扩散阻力大于界面化学反应时的氧化度随着氧气体积分数的增加而降低。钒钛磁铁矿球团的氧化伴随着Fe_(3)O_(4)→Fe_(2)O_(3)、Fe_(2.75)Ti_(0.25)O_(4)→Fe_(2)TiO_(4)/FeTiO_(3)→Fe_(9)TiO_(15)的物相转变过程,在预热氧化过程会出现赤铁矿连晶,致使矿物间的孔隙率降低,氧气内扩散的阻力增大,氧化反应的速率降低。

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 Fe_(3)O_(4)→Fe_(2)O_(3),Fe 2.75 Ti_(0.25)O_(4)→Fe_(2)TiO_(4)/FeTiO_(3)→Fe_(9)TiO_(15).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.