Direct-reduced iron (
DRI), also called
sponge iron, is produced from direct
reduction of
iron ore (in the form of lumps, pellets or fines) by a reducing gas produced from
natural gas or coal. The reducing gas is a mixture, the majority of which is
hydrogen (H
2) and
carbon monoxide (CO) which act as reducing agents. This process of reducing the iron ore in solid form by reducing gases is called
direct reduction.