DDPM Simulation for Fluidization Behavior and Reduction of Iron Ore Fines with Hydrogen in the Fluidized Bed

In this paper, the hydrogen direct reduction of iron ore fines is numerically studied by using the Dense Discrete Phase Model (DDPM) in the fluidized bed. The fluidization behavior at different inlet gas velocities (U_g) as well as the influence of U_g and hydrogen concentration on reduction degree (RD) are comprehensively investigated. The result indicates the increase of time-averaged solids volume fraction for the same cross-sectional heights with increasing U_g when the bed height (H) exceeds 0.06 m. Furthermore, the reduction rate of mineral powder increases with higher U_g value, and the RD reaches almost 100 pct after 4000 seconds of reduction time with U_g ranging from 0.35 to 0.65 m/s. The reduction rate increases noticeably with the increase of hydrogen concentration in the range of 10 to 100 pct, and Fe₂O₃ can be completely converted to Fe under condition of 65 pct H₂ concentration after 4000 seconds. Moreover, higher H₂ concentration leads to faster rate of Fe₂O₃ consumption and Fe production. The mass fraction peak values of Fe₃O₄ and FeO are in the range of 0.29 to 0.34 and 0.21 to 0.24 under different H₂ concentrations, respectively.