Evaluation of Reduction Behavior of the Acid Pellets Prepared with Sinter-Grade Iron Ore Fines by 55% H₂–35% CO–10% N₂ and 100% H₂

Hydrogen is receiving much attention as a reducing agent in iron and steel production processes. Hydrogen-based DRI (Direct-Reduced Iron) production in a shaft furnace is currently under development in many countries. However, due to the limited resources for DR-grade pellets, the hydrogen reduction technology of the pellets produced with sinter-grade iron ore fines is highly anticipated. In this study, the reduction characteristics of the acid pellets produced with sinter-grade iron ore fines were investigated by a typical reformed natural gas (55% H₂–35% CO–10% N₂), and 100% H₂ at temperatures ranging from 973 to 1173 K. The lab-made acid pellet exhibited an average cold crushing strength of 335 kg. When the pellets were reduced by 55% H₂–35% CO–10% N₂, the degree of metallization was satisfied only at 1173 K. On the other hand, when the pellets were reduced by 100% H₂, the degree of metallization was acceptable: 93.04 and 95.54% at 1073 and 1173 K, respectively. The reduction time by 100% H₂ at 1073 K was 29 min, whereas that by 55% H₂–35% CO–10% N₂ at 1173 K was 57 min. Accordingly, the hydrogen reduction process can reduce the reduction time by 51%, although the reduction temperature by 100% H₂ is 100 K lower than that by 55% H₂–35% CO–10% N₂.