摘要:
以焦粉为还原剂,开展了氧化钛精矿含碳球团等温碳热还原试验研究,采用积分法进行了碳热还原动力学分析,还原温度分别为1 000、1 100、1 200、1 300℃。氧化钛精矿中铁氧化物还原度随还原温度和时间增加而增加,还原度可达91%。氧化钛精矿在1 000~1 300℃固相还原前期(<60 min)受界面化学反应控制,反应活化能为51.23 k J/mol;反应后期(>60 min)受扩散控制,反应活化能为93.53 k J/mol。氧化钛精矿碳热还原过程物相转变历程为:Fe2TiO5→Fe3Ti3O10→FeTiO3,物相转变过程增加颗粒内部空隙,增加还原比表面积,改善还原过程气体扩散条件,加快还原初期化学反应速率。
Abstract:
The isothermal carbothermal reduction of oxidized ilmenite concentrate/carbon composite pellets was performed with coke as reductant,and the kinetics was analyzed by integration method. The reduction temperature was set at 1 000,1 100,1 200 and 1 300 ℃,respectively.The reduction degree of iron oxides in the oxidized ilmenite concentrate,able to be 91%,increased with increase of the reduction temperature and time.The reduction of oxidized ilmenite concentrate was controlled by interface chemical reaction in early stage of solid state reaction（ ＜60 min） with activation energy of 51.23 k J/mol at 1 000 ~1 300 ℃,while it was controlled by diffusion in later period（ ＞ 60 min） with activation energy of 93.53 k J/mol. The main phase transformation during the reduction process can be described as follows: Fe2TiO5→ Fe3Ti3O10→FeTiO3.During the phase transformation,the particles’ inner pore and specific surface area were increased,the gas diffusion conditions were improved and the chemical reaction rate in early stage was accelerated.
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