Sponge iron is the metallic form of iron produced from reduction
of iron oxide below the fusion temperature of iron ore (1535 ◦C)
by utilizing hydrocarbon gases or carbonaceous fuels as coal. The
reduced product having high degree of metallization exhibits a
‘honeycomb structure’, due to which it is named as sponge iron. As
the iron ore is in direct contact with the reducing agent throughout
the reduction process, it is often termed as direct reduced iron
(DRI).
It is seen that the growth of sponge iron industry in last few
years is unremarkable and today India is the largest producer of
sponge iron as it covers 16% of global output. According to Sponge
Iron Manufacturers Association [1], India has produced around 23
million tonnes of sponge iron in the financial year of 2009–2010.
Sponge iron is used as feedstock and a recognized alternative to
steel scraps in iron and steel making processes. Due to certain problems
inherent in blast furnace and induction furnace process such
as the scarcity of steel scraps in international markets, depleting
reserves of high quality metallurgical grade coking coal, environmental
constraints on coke and sinter plants, and requirement of
auxiliary plants with increased capital and operational intensity
direct reduction technology has emerged as a potential process for
iron and steel making.