Extraction of Iron

Extraction of Iron

Iron is the most widely used metal in the world, mainly in the form of steel. The main

ore of iron is called haematite. It is a  mineral composed of iron(III) oxide, Fe₂O₃.

About 4.12% (or 4.15%) of earth’s crust is Iron. Mainly Fe is extracted from oxide ore. Commercially Fe is extracted from Haematite by three steps: Condensation. Roasting & Smelting.

Reduction of Iron (III) oxide (Fe₂O₃) in the Blast Furnace is the main step of Fe extraction. It is a cylindrical steel-made furnace. It has 3 pasts:

1. Upper portion or Stock column
2. Middle portion or Boss
3. Lower portion or Hearth

The significant reactions occurring within the Blast Furnace can be described via the following steps showing how the reducing agent varies depending on the height in the furnace (i.e. on the Temperature).

At 500 °C

3Fe₂O₃ +CO → 2Fe₃O₄ + CO₂

Fe₂O₃ +CO → 2FeO + CO₂

At 850 °C

Fe₃O₄ +CO → 3FeO + CO₂

At 1000 °C

FeO +CO → Fe + CO₂

At 1300 °C

CO₂ + C → 2CO

At 1900 °C

C+ O₂ → CO₂

FeO +C → Fe + CO

The temperature of the furnace increases from its mouth to the hearth.

• In different parts of blast furnace, the temperature varies from 400°C to 1500°C.
• The temperature of stock column is 400°≈750°C & that of boss is 900°C ≈ 1000°C.
• Near the hearth, the temperature is 1300°C ≈ 1500°C.
• The iron obtained from blast furnace is known as Pig iron/Cast iron, it’s composition is:

C → 2 – 4.5%; Si→ 1-1.5%; Mn → 0.4%.