Effect mechanism of manganese on hydrogen-based reduction behavior of magnetite pellet

Abstract

In the ironmaking industry, using hydrogen energy as a reducing agent or fuel instead of fossil energy has emerged as the primary development direction in future. This study investigates the action mechanism of Mn3O4 in manganese-bearing magnetite pellets during hydrogen-based shaft furnace direct reduction (HSFDR). The findings indicated that with the increase of Mn3O4 addition, the content of MnxFe1-xO and Mn-rich silicate phases in the reduced pellets gradually increased, while the metallization rate of pellets decreased. With the augmentation of Mn-rich silicate phases, numerous metallic iron particles were wrapped by them, which resulted in the loss of clear boundaries between the metallic iron particles and the silicate phases. Concurrently, the MnxFe1-xO inhibited the growth of metallic iron whiskers, altered their growth structure, and reduced the reduction swelling index (RSI) of pellets. This study provides theoretical and practical insights into the hydrogen-based shaft furnace reduction of manganese-containing magnetite pellets.