Studies of the expansion mechanism on different pellets under hydrogen-rich reducing atmosphere

In response to the need to develop green low-carbon iron smelting technology, blast furnace hydrogen reduction technology is of great significance for reducing CO2 emissions from the ironmaking system. This study focuses on the change in swelling behaviour of different types of pellets during the blast furnace hydrogen smelting process. It analyses the reduction swelling index (RSI/%) and compression strength before and after reduction at 900 degrees C in a variety of reduction gas atmospheres, among other indices. The results show that under the condition of ore grade, the reduction expansion rate of pellet increases with the increase of grade. With the increase of basicity (R) (0 similar to 0.25) and the Mg-Al ratio (M/A) (0.4 similar to 1.4), the reduction in expansion of the pellet shows an upward trend. However, the RSI/% shows a downward trend with the increase of the synergistic effect of ore silicon and aluminium (S + A). The compression strength after reduction increases to different degrees with the increase of the proportion of hydrogen in the reduction atmosphere; the maximum increase was about 0.591 KN. SEM-EDS detection was carried out on pellet in different reduction atmospheres, and the structure and component changes of various regions during the reduction process were analysed.