Question

Magnesium oxide is used for the lining in steel making furnace because:
A. MgO acts as an acidic flux to remove impurities of Si, P and S
B. MgO acts as a basic flux to remove impurities of Si, P and S
C. MgO acts as an oxidizing agent to remove impurities of oxides
D. MgO does not react with any type of impurities

Answer 1

The impurities which are going to be formed in the lining of the furnace are acidic in nature. To neutralize the formed impurities there is a need for the basic flux at the time of the lining of the furnace.

Complete answer:
- In the question it is asked to find the reason behind the usage of the magnesium oxide in lining in steel making furnaces.
- Generally, the furnace lining should withstand a higher temperature therefore the lining in the furnace is going to be made up of steel and MgO.
- The magnesium oxide is going to act as a basic flux and remove the acidic impurities like Si, P and S which are going to be formed while lining the furnace.
- Therefore, MgO is going to act as a basic flux and remove the impurities of Si, P and S and the chemical reactions are as follows.
$\underset{Basic\text{ }flux}{\mathop{MgO}}\,+\underset{Acidic\text{ }impurite}{\mathop{Si{{O}_{2}}}}\,\to \underset{slag}{\mathop{MgSi{{O}_{3}}}}\,$
- In the same manner MgO is going to remove the phosphorus and sulphur impurities.

So, the correct option is B.

Note:
The chemical reactions of magnesium oxide with acidic impurities like sulphur and phosphorus are as follows.

& \underset{Basic\text{ }flux}{\mathop{MgO}}\,+\underset{Acidic\text{ }impurite}{\mathop{{{P}_{2}}{{O}_{5}}}}\,\to \underset{slag}{\mathop{M{{g}_{3}}{{(P{{O}_{4}})}_{2}}}}\, \\\ & \underset{Basic\text{ }flux}{\mathop{MgO}}\,+\underset{Acidic\text{ }impurite}{\mathop{S{{O}_{2}}}}\,\to \underset{slag}{\mathop{MgS{{O}_{3}}}}\, \\\ \end{aligned}$$