Pig Iron
Pig Iron is made directly from the molten iron that comes out from the blast furnace. The pig iron is neither ductile nor malleable in nature.
It contains some impurities like carbon, manganese, sulphur and phosphorus. The pig iron in the molten form is used for making mild carbon steel and special alloy steel.
It is also used as cast in desired shapes and size in the foundry. Pig iron cast are used in making pipes, heat resistant casing & plates used in sub-surface construction works.
Wrought Iron
It is the pure form of iron produced after removal of impurities like carbon, manganese, sulphur and phosphorus. It is produced by heating of pig iron with
hematite ore in the secondary furnace .The wrought iron is malleable and ductile. It is used for making machine parts, wires, nails, bolts, chains, angles and agricultural implements.
Sponge Iron
Sponge iron is the metallic mass with more than 90% of iron present in it. The sponge iron is produced in the rotary kiln by direct reduction of iron ores in solid states using
non coking coal and gaseous fuel. The reduction takes place at temperature between 800'C to 1000'C. Due to the reduction of iron ore, oxygen is removed from it.
The removal of oxygen leaves pores in the iron giving a sponge like appearance and hence, the name sponge iron. The sponge iron is also called Direct Reduced Iron (DRI).
The sponge iron produced by using of gaseous fuels helps to form dense briquettes. It is called Hot Briquetted Iron (HBI).The metallic content of standard sponge iron is more than 90%.The remaining materials are gangue materials.
The sponge iron is used for the production of mild carbon steel and special alloy steel using Electric Arc Furnace, Induction Furnace and Electrothermal Furnace.
The countries having inferior Quality of iron ore and non coking coal can use this process for making of steel at a lower cost. At present the countries like India
& Brazil are using sponge iron technologies for production of steel through secondary steel plant.
