Investigation into the characteristics of H2-rich gas injection over iron ore sintering process: Experiment and modelling

Highlights: • H₂-rich gas injection (HGI) improved sinter quality and abated pollutants emissions. • HGI decreased solid fuel and moisture consumption for sintering. • Deep mechanism of HGI on sintering was revealed via experiments and modelling. -- Abstract: Applying hydrogen energy into iron ore sintering process is an efficient strategy to abate CO₂ emission. This investigation mainly focused on revealing the influence of H₂-rich gas injection on sintering performance and elucidating the deep mechanism through both laboratory tests and mathematical model. Results showed that injecting H₂-rich gas contributed to reducing the proper moisture content and coke breeze rate from 7.00% and 5.60% to 6.75% and 5.30% due to the negative influence of generated H₂O and excessive heat supply. Under main operation conditions, increasing the injection concentration of H₂-rich gas improved the sinter yield and tumbler index gradually till reaching the proper concentration of 0.80%. The emission reduction of NO and SO₂ mainly brought by the decreased coke breeze consumption reached around 10% and 6%. The mechanism of H₂-rich gas injection was mainly attributed to the improved thermal patterns of sintering bed, which increased liquid phase formation area and high temperature (≥1200 °C) duration, thereby facilitating the formation of enough adhesive phase calcium ferrite. Moreover, the cooling velocity of adhesive minerals was obviously slowed down, which facilitated the formation of needle-like calcium ferrite with high mechanical strength. The research findings are of great significance for guiding the application of cost-effective H₂-rich gas into practical sintering plants.