氢气还原1～3mm铁矿粉的动力学研究

Reduction Kinetics of 1-3mm Ore Fines With H_2

在自制的kg级高温流化床中研究了氢气还原1～3 mm矿粉的动力学试验。随着时间的增加,气体利用率下降,表明还原前期反应速度快,后期反应慢;温度越高,气体利用率越高,但随着还原时间的增加,差距在逐步缩小;对于750℃,前20 min的气体利用率为9%,金属化率达到84%,说明氢气还原矿粉反应是非常迅速的。随着气速的增加,金属化率在增加,并且几乎成线性关系,因此使用氢气作为还原剂,可以允许更高的气速,从而提高设备的生产效率。随着料高的增加,金属化率不断下降,然而气体利用率却在不断升高。使用氢气作为还原剂,可以将还原温度降低到700～750℃,避免流化床过程中的粘结难题;试验中氢气还原1～3 mm铁矿粉时的表观活化能为58.4kJ/mol。

Kinetics experiment was conducted in a self-prepared kg-scale high temperature fluidized bed for 1-3 mm ore fines reduction with hydrogen. The utilization rate of hydrogen decreases with reaction, which shows that the reactive speed is fast in the early reaction stage, hut afterwards slower. The higher the reaction temperature, the more the utilization rate of hydrogen, but difference of the utilization rate is narrowed gradually with the increase in reaction time. Under the conditions of the first 20min and 750 ℃, the utilization rate of hydrogen is 9%, and the metallization degree reaches 84 %, which shows that the speed of reduction reaction with hydrogen is very fast. With increase＇in hydrogen gas velocity, the metallization degree of iron ore fines increases linearly. So, in order to improve the productivity of facility, in case of hydrogen as reducing gas, much higher velocity of hydrogen can be allowed. With increase in the bed depth, metallization degree of iron ore fines decreases while the utilization rate of hydrogen increases gradually. The reaction temperature can lower to 700-750 ℃ with hydrogen as reducing gas, which is helpful to solve the sticking problems of fluidized bed. As for the reduction reaction of 1-3 mm iron ore fines with hydrogen, its apparent activation energy is about 58.4 kJ/mol in the fluidized bed experiment.