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

Abstract 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% H 2 –35% CO–10% N 2 ), and 100% H 2 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% H 2 –35% CO–10% N 2 , the degree of metallization was satisfied only at 1173 K. On the other hand, when the pellets were reduced by 100% H 2 , the degree of metallization was acceptable: 93.04 and 95.54% at 1073 and 1173 K, respectively. The reduction time by 100% H 2 at 1073 K was 29 min, whereas that by 55% H 2 –35% CO–10% N 2 at 1173 K was 57 min. Accordingly, the hydrogen reduction process can reduce the reduction time by 51%, although the reduction temperature by 100% H 2 is 100 K lower than that by 55% H 2 –35% CO–10% N 2 . Graphical Abstract