Swelling Behavior of Iron Ore Pellets during Reduction in H2 and N2/H2 Atmospheres at Different Temperatures

The need to develop green steelmaking techniques has led to the replacement of reducing agents such as CO with H-2. H-2 and N-2/H-2 mixtures can be used for the carbothermal reduction of iron ore. Herein, the reduction swelling index (RSI) of iron ore pellets in a forming gas (N-2/H-2) atmosphere at temperatures of 700-1000 & DEG;C is investigated and it is compared with that in pure H-2. It is showed in the experimental results that the RSI increases with increasing temperature for both the H-2 and N-2/H-2 atmospheres. The maximum swelling is reached approximately 5 min into the H-2 reduction process, while in the N-2/H-2 atmosphere, it is reached after 25-45 min of reduction, depending on the temperature. When the reduction temperature exceeds 900 & DEG;C, the RSI is greater than 20%. Scanning electron microscopy/energy-dispersive X-ray spectroscopy is performed to detect the changes in the microstructure and chemical composition of the samples. The nonreduced areas in the reduced pellets during the N-2/H-2 reduction process are analyzed using light optical microscopy.

Automated summary

The study investigates the reduction swelling index (RSI) of iron ore pellets in a forming gas atmosphere and compares it with that in pure H-2. Experimental results show that the RSI increases with increasing temperature in both H-2 and N-2/H-2 atmospheres. The maximum swelling is reached earlier in the H-2 reduction process compared to the N-2/H-2 atmosphere.