Mechanism of hydrogen reduction

In conventional steelmaking processes, CO₂ gas is generated when iron ore is reduced with CO gas. On the other hand, with hydrogen reduction H2O gas is generated instead of CO₂, and therefore this method can be regarded as an environmentally - friendly steelmaking process.

Advantages of hydrogen reduction

Conventional blast furnace - based steelmaking processes use CO gas to remove oxygen in iron ore.

As CO gas has a larger molecular size, it is difficult for the molecules to penetrate into iron ore. On the other hand, H₂ gas, with a much smaller molecular size, can easily penetrate into iron ore with a penetration rate five times as large as that of CO, achieving rapid reduction of iron ore in a blast furnace.

Direct reduction processes with natural gas are in operation in the world. In Japan, however, no direct reduction process is working due to the lack of natural gas. Moreover, the technology to reduce iron ore with hydrogen in blast furnaces has not been commercially operated because of the difficulty in obtaining hydrogen at low production costs'.