Effect of process parameters on fluidization and agglomeration behavior of iron ore fines

초록

A novel direct reduction process of iron ore fines in a hydrogen-based fluidized bed reactor has great advantages in achieving carbon neutrality, removing the pretreatment process such as pelletizing and expanding the variation of iron ores grades. However, the sticking and agglomeration of the iron ore fines may happen, resulting in defluidization. Eventually, these affect the required high reduction rate and the stable process operation of the reactor. In this work, the effect of process parameters on the fluidization and sticking-agglomeration behavior of the iron ore fines in a fluidized bed reactor is examined using a coupled DEM-CFD simulation. Different fluidizing gases such as H2, CO, and 70 % H2-30 % CH4 are considered at superficial inlet gas velocities ranging from 1 to 2.5 m/s at 873.15 to 1073.15 K. In each case, 30,000 particles with a diameter range of 75-150 mu m are employed. The present model is validated with an experimental result from the literature. The results demonstrate that higher gas viscosity and velocity enhance fluidization. Moreover, the increment of temperature results in the increment of gas viscosity and a slight decrease of the surface energy of the reduced iron, enhancing the tendency of fluidization of iron ore fines. Therefore, to tackle the sticking and agglomeration of iron ore fines, considering the physical properties of the reducing gases and the iron ore fines is necessary, along with optimizing the relevant process parameters.

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