Question

Describe the different steps involved in the extraction of iron from its haematite ore. Write the necessary chemical equations involved.

Answer 1

Part:1

• It’s a long process that begins with Concentration through calcination roasting.
• Concentration is used to remove the water and other volatile compounds such as Sulphur and Carbonates.
• This concentrated ore is reacted with Limestone and Coke and then goes into the blast furnace from the top.
• In the blast furnace where the extraction of Iron happens.
• The concentrated Iron ore, Coke, and Limestone are goes from the top, and a blast of hot air is blown into the bottom.
• All the ingredients are crushed into small pieces and mixed.
• Hot air is blown from the bottom and coke is burned to yield temperatures up to about $\mathbf{2200}\mathbf{K}$.
• Burning coke gives the maximum of the heat required for this process.
• At such high temperatures, Coke reacts with the Oxygen in the presence of hot air to give Carbon Monoxide.
• The Carbon Monoxide and heat now move up.
• The temperature in the upper section of the Furnace is generally lower compared to the bottom.
• Hematite and Magnetite are reduced to Ferrous Oxide.
• The Limestone also decomposes to Calcium oxide which helps to remove the Silicate impurity of the ore in form of Slag.
• Silicate can be easily separated from molten Iron.
• The Iron formed in Blast Furnaces contains about $\mathbf{3}\mathbf{-}\mathbf{4}\mathbf{}\mathbf{\%}$ of Carbon and very little quantities of many other impurities such as Sulphur, Silicon, etc.
• Which is called Pig Iron. Pig Iron is a hard but brittle metal and the impurities greatly affect its strength.
• Carbon appears significant role in affecting the brittleness and hardness balance in Iron.
• To further reduce the Carbon content of pig iron, the pig Iron is melted again with scraps of Iron and Coke.
• This kind of Iron is called Cast Iron and has a lower Carbon content of $\mathbf{2}\mathbf{-}\mathbf{3}\mathbf{}\mathbf{\%}$.
• Cast Iron is harder than pig iron.

Part 2:

• Reactions in the Blast furnace at $\mathbf{500}\mathbf{-}\mathbf{800}\mathbf{}\mathbf{K}$, In the upper parts with lower temperatures,
• $$\begin{gathered} \mathbf{3}{\mathbf{Fe}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{CO}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}\mathbf{2}{\mathbf{Fe}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{4}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{CO}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)} \\ \mathbf{Iron}\mathbf{}\mathbf{\left(}\mathbf{II}\mathbf{\right)}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Carbon}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Iron}\mathbf{}\mathbf{(}\mathbf{II}\mathbf{,}\mathbf{III}\mathbf{)} \\ \mathbf{Oxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Monoxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Oxide} \end{gathered}$$
• $$\begin{gathered} {\mathbf{Fe}}_{\mathbf{3}}{\mathbf{O}}_{\mathbf{4}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{4}\mathbf{CO}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}\mathbf{3}\mathbf{Fe}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{4}{\mathbf{CO}}_{\mathbf{2}} \\ \mathbf{Iron}\mathbf{}\mathbf{(}\mathbf{II}\mathbf{}\mathbf{III}\mathbf{)}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Iron} \\ \mathbf{Oxide} \end{gathered}$$
• $$\begin{gathered} {\mathbf{Fe}}_{\mathbf{2}}{\mathbf{O}}_{\mathbf{3}}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{CO}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}\mathbf{2}\mathbf{FeO}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{CO}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)} \\ \mathbf{Iron}\mathbf{}\mathbf{\left(}\mathbf{II}\mathbf{\right)}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Iron} \\ \mathbf{Oxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Oxide} \end{gathered}$$
• At $\mathbf{900}\mathbf{-}\mathbf{1500}\mathbf{}\mathbf{K}$,
• $$\begin{gathered} \mathbf{C}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{CO}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}\mathbf{2}\mathbf{CO}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)} \\ \mathbf{Carbon}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Carbon}\mathbf{} \\ \mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Monoxide} \end{gathered}$$
• $$\begin{gathered} \mathbf{FeO}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}\mathbf{CO}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)}\mathbf{}\mathbf{\to }\mathbf{}\mathbf{Fe}\mathbf{}\mathbf{\left(}\mathbf{s}\mathbf{\right)}\mathbf{}\mathbf{+}\mathbf{}{\mathbf{CO}}_{\mathbf{2}}\mathbf{}\mathbf{\left(}\mathbf{g}\mathbf{\right)} \\ \mathbf{Iron}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Carbon}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Iron}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Carbon} \\ \mathbf{Oxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Monoxide}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Dioxide} \end{gathered}$$