Question

Name the two substance that separate at the bottom of the blast furnace.

Answer 1

• In the blast furnace, coke $\left(\mathrm{C}\right)$ helps in reducing iron oxide $\left({\mathrm{Fe}}_2{\mathrm{O}}_3\right)$ into iron in the molten state which settles at the bottom.

$$\begin{gathered} {\mathrm{CO}}_2\left(\mathrm{g}\right)+\mathrm{C}\left(\mathrm{s}\right)\to 2\mathrm{CO}\left(\mathrm{g}\right) \\ {\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+3\mathrm{CO}\left(\mathrm{g}\right)\to 2\mathrm{Fe}\left(\mathrm{l}\right)+3{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{molten}\mathrm{iron} \end{gathered}$$

• At high temperature, limestone $\left({\mathrm{CaCO}}_3\right)$ decomposes into calcium oxide $\left(\mathrm{CaO}\right)$ which helps in removing slag $\left({\mathrm{CaSiO}}_3\right)$ from the bottom of the blast furnace.

$$\begin{gathered} {\mathrm{CaCO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ \mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{SiO}}_2\left(\mathrm{g}\right)\stackrel{∆}{\to }{\mathrm{CaSiO}}_3\left(\mathrm{l}\right) \\ \mathrm{silica}\mathrm{slag} \end{gathered}$$

Therefore, molten iron and slag are separated at the bottom of the blast furnace.