Question

How is iron extracted from hematite?

Answer 1

Hematite

• Hematite is an iron oxide with formula${\mathrm{Fe}}_2{\mathrm{O}}_3$.
• It is commonly found in rocks and soil.
• It has a rhombohedral lattice system.
• It is a common ore used for the extraction of Iron.

Extraction of Iron from Hematite

• Iron is extracted from hematite (${\mathrm{Fe}}_2{\mathrm{O}}_3$) in a blast furnace.
• In a blast furnace, the ore is led into the top of the furnace along with coke and limestone and the limestone is decomposed into the hot furnace, forming calcium oxide. This reacts with the sandy impurities (silicon dioxide) to form a slag.
• The Hematite reacts with Carbon in the cast iron to give pure iron and carbon monoxide gas which escapes.
• In a blast furnace, different compartment shows different reactions and all the compartment works at a different range of temperature.

At temperatures 500-800K

$$\begin{gathered} 3{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+\mathrm{CO}\left(\mathrm{s}\right)\to 2{\mathrm{Fe}}_3{\mathrm{O}}_4\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ {\mathrm{Fe}}_3{\mathrm{O}}_3\left(\mathrm{s}\right)+4\mathrm{CO}\left(\mathrm{g}\right)\to 3\mathrm{Fe}\left(\mathrm{s}\right)+4{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ {\mathrm{Fe}}_3{\mathrm{O}}_3\left(\mathrm{s}\right)+4\mathrm{CO}\left(\mathrm{g}\right)\to 2\mathrm{FeO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \end{gathered}$$

In the lower portion of the Blast Furnace (at 900-1500K)

$\mathrm{C}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(g\right)\to 2\mathrm{CO}\left(g\right)$

$3\mathrm{FeO}\left(s\right)+{\mathrm{CO}}_2\left(g\right)\to \mathrm{Fe}\left(s\right)+{\mathrm{CO}}_2\left(g\right)$

Fig: Diagram of Blast furnace

The Iron obtained from the blast furnace contains 4% carbon and many impurities in a small amount. This iron is called pig iron.