Effect of Different Modification Methods on Fluidized Bed Hydrogen Reduction of Cohesive Iron Ore Fines

To develop breakthrough technologies that enable a drastic reduction in CO2 emissions from the ironmaking industry, the direct reduction of iron ore fines by H2–N2 in a fluidized bed with different modification methods was investigated. The results show that powder coating could prevent the defluidization of cohesive iron ore fines through the physical spacer effect, while granulation modification with cheap cement as the binder not only inhibits the occurrence of sticking, but also greatly accelerates the reduction rate. Microstructure observations indicate that granulation modification has reconstructed the irregularly shaped iron ore fines to be spherical, consisting of small grains, and created porous channels for gas diffusion, thereby increasing the reduction rate. In addition, structure reorganization constructs nonsticking barriers on the surface using native gangue and cement, and the occurrence of defluidization is avoided. Moreover, granulation modification has been demonstrated to be an effective and general solution for efficient and stable fluidized bed reduction of iron ore fines. This makes hydrogen ironmaking through fluidized bed direct reduction technically attractive.