One of the key technologies in developing hydrogen-enriched ironmaking operations is the control
of the carburisation, melting, and dripping behaviour of the iron ore burden materials. When a hot
compacted iron (HCI) is charged in the blast furnace or the FINEX Melter-Gasifier, iron oxide
reduction, the reduced iron’s carburisation, and the melting of iron and slag occur successively. This
study investigated the reduction, carburisation, melting and dripping behaviour of HCI under a COH2
gas mixture using the high-temperature X-ray radiographic technique. Under 100 per cent CO
gas atmosphere, the dripping temperature was 1410°C. When 5 per cent H2 was introduced, the
dripping temperature slightly decreased to 1400°C. Furthermore, the dripping temperature gradually
increased as the H2 gas composition increased. As 30 per cent H2 was introduced, the dripping
temperature reached 1414°C. The carbon concentration in the drained metal samples gradually
increased with increasing H2 composition. It is considered that H2 decreased FeO content in the slag,
yielding the increased melting temperature and viscosity of the slag. On the other hand, H2
accelerated the carburisation of the reduced iron by CO gas, enabling the homogenisation of the
oxide materials to form a liquid phase. Therefore, it is considered that introducing H2 in the reactor
is helpful to increase productivity and energy efficiency by accelerating the liquid phase’s formation.