A Simulation Study of the influence of Process Factors on the Fluidized Reduction Effect of Iron Ore Powder

Taking the high-pressure circulating fluidized bed as a prototype, the geometric model of the tube inside the fluidized bed was established.Considering the characteristics of heat and mass transfer between particles and chemical reactions comprehensively, with metallization rate and reaction equilibrium time as evaluation indices, Barracuda software was used to simulate and analyze the effects of the process factors such as the reduction temperature, the particle size of the ore powder, and the reduction atmosphere on the fluidized reduction of iron ore powder, in order to determine the optimal scheme for the fluidized reduction of iron ore powder. Scanning electron microscope (SEM) was used to characterize the micro-morphology of the ore powder, and the influence of process factors on the fluidized reduction of iron ore powder and the bonding mechanism were explored. The results show that when the particle size of mineral powder is 0.150, 0.180) mm, the reduction temperature is in the range of 573–1 173 K, increasing the temperature is beneficial for improving the metallization rate and the longitudinal velocity of the particles and shortening the reaction equilibrium time. If the temperature is too high, the longitudinal velocity of the particles decreases. This is due to the interlocking of iron whiskers to form agglomerations, which inhibits the fluidization of the iron ore powder.When the temperature is 973 K, the particle size of the ore powder is in the range of 0.080,1.000) mm, decreasing the particle size can increase the surface area, which is beneficial for improving the metallization rate of iron ore powder. If the particle size is too small, it will make it difficult for the particles to accumulate and fluidize.Under the condition of reducing the atmosphere of H₂ + CO, the reduction efficiency of pure H₂ is better than that of CO. However, increasing the content of CO can reduce the generation of water vapor, which is beneficial for improving the fluidization performance of mineral powder. Under conditions of gas linear velocity at 0.6 m/s and pressure at 0.2 MPa, the optimum process parameters for fluidized reduction of iron ore powder are identified as: reduction temperature of 973 K, particle size of 0.150,0.180) mm, and reduction atmosphere of 70%H₂ + 30%CO.