1. Mining and Preparation:
* Iron oxide, commonly found in the form of hematite and magnetite, is mined from the earth.
* The ore is crushed and ground to a fine powder to increase its surface area and facilitate chemical reactions.
2. Smelting Process:
* Blast Furnace: The crushed ore is fed into a tall, cylindrical furnace called a blast furnace.
* Coke and Limestone: Coke (almost pure carbon) and limestone (CaCO₃) are also added to the furnace.
* Hot Air: Hot air is blown into the furnace from the bottom. This air reacts with the coke to produce carbon monoxide (CO).
* Reduction Reactions: The carbon monoxide reduces the iron oxide to iron metal through a series of chemical reactions:
* Fe₂O₃ + 3CO → 2Fe + 3CO₂
* Slag Formation: The limestone decomposes into calcium oxide (CaO), which reacts with impurities in the ore to form slag (molten waste).
* Molten Iron: The molten iron, heavier than slag, collects at the bottom of the furnace.
* Tapping: The molten iron and slag are tapped off separately from the furnace.
3. Further Processing:
* Pig Iron: The molten iron from the blast furnace is called pig iron. It contains impurities such as carbon, silicon, manganese, and phosphorus.
* Steelmaking: Pig iron is further processed in a steel mill to remove impurities and add specific elements to produce various types of steel.
Key Points:
* Reduction: Smelting involves the chemical reduction of iron oxide using carbon monoxide.
* High Temperature: The blast furnace operates at very high temperatures (around 1500 °C) to facilitate the chemical reactions.
* Slag Formation: Slag removes impurities from the iron ore, producing a cleaner, usable iron.
* Steelmaking: The pig iron produced from the blast furnace is further refined to produce steel, a stronger and more versatile material.
In summary, iron is made from iron oxide through the smelting process, which involves heating iron oxide with carbon in a blast furnace to reduce the iron oxide to iron metal.
