流化床中CO还原1～3mm铁矿粉研究

Study on the Reduction of 1～3 mm Iron Ore Powder by CO in Fluidized Bed

在自制的公斤级高温流化床中研究了CO还原1～3 mm矿粉的还原行为。随着时间的增加,样品的还原率增加,气体利用率却在下降,说明还原前期反应速度快,后期反应慢;温度越高,样品的还原率越大,气体的利用率越高,但随着还原时间的增加,差距在逐步缩小。当还原温度为850℃时,前20 min的还原率为80%,气体利用率为8%左右,这说明高温下,CO还原1～3 mm铁矿粉的反应速度是很快的。温度越高,表观反应速率常数越大,而且增加的幅度也越来越大;随着气速的增加,铁矿粉的还原率增加,并且几乎成线性关系,表明高温下,使用CO气体作为还原剂时,可以允许更高的气速,从而可以提高设备的生产效率。随着料层高度的增加,金属化率与还原率不断下降,然而气体利用率却在不断升高。试验中CO还原1～3 mm铁矿粉时的表观活化能为59.11 kJ/mol。

The reduction behavior of ore powder by co in homemade kg-scale fluidized bed was studied.The reduction degree of the sample increases and the utilization ratio of gas decreases when the reaction lasts longer time,which indicates that the reaction is faster at the beginning of reduction,while it becomes slower in latter process.The higher the reaction temperature,the higher the utilization ratio of gas and the reduction degree are,but the difference of utilization ratio among the different temperatures becomes smaller with time.The utilization ratio of gas can reach about 8% and the reduction degree 80% for 20 min reduction at 850 ℃,which shows under high temperature the reduction reaction by CO is very fast.The higher the reaction temperature,the higher the apparent reaction rate constant is,but the difference of apparent reaction rate constant among the different temperatures becomes bigger.The increase of reduction degree with gas velocity increase performs quite good linearity,which shows under high temperature even higher velocity of reducing gas can be used to improve the productivity of reactor when CO is used as reducing gas.With the increase of charge height,the metallization ratio and the reduction degree decrease,but the utilization ratio of gas increases.The apparent activation energy of the reduction of 1～3 mm iron ore powder by CO is about 59.11 kJ/mol in the fluidized bed experiment.