A Comparison Between the Reduction Behavior of DRI and BF Pellets in H2 and CO Atmospheres

The reduction behavior of two different iron ore pellets that are used in blast furnace (BF) and direct reduction (DRI) was investigated in this research. Single pellets reduction experiments were conducted isothermally using pure CO and H2 as reducing agent in the temperature range 700 degrees C to 1100 degrees C. Reduction by H2 was significantly faster than reduction by CO for both pellets and reduction rate increased with increasing the temperature. When CO was used as the reducing agent, the BF pellet achieved a reduction degree of 32% at 700 degrees C and 67% at 800 degrees C, while the DRI pellet reached 28% and 59% at the same temperatures. This difference is due to the lower magnetite content in BF pellets (1.93%) compared to DRI pellets (9.11%). However, at 1000 degrees C and 1100 degrees C, the DRI pellet achieved 93% and 100% reduction, and the BF pellet 88% and 94%, respectively, due to the higher porosity in the DRI pellet (38%) compared to BF (32%). Kinetics controlling model for hydrogen reduction of both pellets suggested as D2 (2D Diffusion through the solid ash), however, A1 (1D Nucleation and growth) and R3 (3D Chemical reaction) were found as the most compatible models for CO reduction of DRI and BF pellets, respectively.