摘要:
以钒钛铁精矿和煤粉为原料,在空气气氛下通过碳热还原法制备Fe-Ti(C,N)复合粉末。通过还原产物X射线衍射分析,对空气气氛下还原温度和配碳量对钒钛铁精矿碳热还原的反应过程以及物相演变进行了研究。结果表明,随着温度的升高,反应过程中的物相演变过程为:Fe3O4→Fe,FeTiO3→FeTi2O5→Ti4O7→Ti2O3→Ti(C,N),配碳量是使反应体系处于气相平衡的关键因素。在配碳量<25%时,体系内CO、CO2和N2的分压不能达到平衡或维持反应平衡的时间很短,钒钛铁精矿不能被还原或只能部分被还原为Ti(C,N)。在还原温度1 500℃,还原时间30 min,配碳量30%的条件下,还原产物中TiC1-xNx的颗粒尺寸约为3μm,TiC1-xNx的C/N值为0.491 5,x=0.67。
Abstract:
Fe-TiC1-xNxcomposites were successfully prepared directly from titanomagnetite concentrate by carbothermal reduction in air atmosphere.The influences of reduction temperature and carbon content on the reaction process and phase evolution during carbothermal reduction of titanomagnetite concentrate were mainly investigated using X-ray diffraction(XRD).The results show that,with the reduction temperature increasing,the phase evolution sequences in the reaction process are as follows:Fe3O4→Fe and FeTiO3→FeTi2O5→Ti4O7→Ti2O3→Ti(C,N).The carbon content is the key factor for gas phase equilibrium in the reaction system.When the carbon content is less than 25%,the partial pressure of CO,CO2 and N2 could not reach equilibrium or stays at equilibrium for a short time,and the vanadium titanomagnetite concentrate cannot or partially be reduced to Ti(C,N).At reduction temperature of 1 500℃ for 30 min with 30% carbon content,the TiC1-xNxhaving about 3 μm of particle size can be obtained with 0.491 5 of C/N ratio and x=0.67,and the obtained particles are obviously agglomerated.
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