甲烷气氛中铁精矿粉闪速还原行为研究

Flash reduction behavior of fine iron ore in CH4 atmosphere

高炉炼铁工艺存在流程长、能耗高以及强烈依赖冶金焦等问题,发展绿色低碳的非高炉炼铁工艺对钢铁生产具有重大意义。本文采用超级铁精矿粉进行了甲烷闪速还原试验,考察还原温度及甲烷体积分数对金属化率的影响,研究铁精矿粉在试验条件下的闪速还原行为,并对还原产物微观形貌进行观察,分析闪速还原机理。结果表明:还原温度为1550 K、甲烷体积分数7.5%、还原时间为5.49 s时,矿粉金属化率可达90.0%;还原温度的升高及甲烷体积分数的增加提高了矿粉的金属化率;甲烷在还原过程中发生裂解,生成的固体碳在还原产物表面沉积,促进铁氧化物的还原和金属铁的渗碳;渗碳过程降低了金属铁的熔点,还原产物由不规则形状向球型转变;矿粉内部为致密的铁层包裹着未反应的铁氧化物的结构,在FeO/Fe界面处FeO的还原主要是由铁中的固溶碳[C]完成。

Blast furnace ironmaking process has some problems,such as long process,high energy consumption and strong dependence on metallurgical coke.It is of great significance to develop green and low-carbon non-blast furnace ironmaking process.The current study investigated the flash reduction behavior of fine iron ore in methane atmosphere at 1450-1550 K.The effects of reduction temperature and methane concentration on the metallization rate were investigated,and the microstructure of the reduction products was observed to analyze the mechanism of flash reduction.The results showed that the metallization rate reached 90.0%when the reduction temperature was 1550 K,CH4 concentration was 7.5%and the reduction time was 5.49 s.The increase of reduction temperature and reduction time increased the metallization rate of fine iron ore.The solid carbon generated from the pyrolysis of methane was attached to the surface of particles,which was deposited on the surface of the reduction product,promoting the reduction of iron oxides and carburizing of metal iron.The carburization process decreased the melting point of metal iron,making the reduction product from irregular shape to spherical shape.Cross-sectional morphology was the structure of a dense iron layer wrapping the unreacted iron oxide.The reduction of FeO at the FeO/Fe interface was mainly accomplished by[C]in Fe.