alleryStart learning →In the smelting of haematite in the blast furnace, limestone is added mainly to
Aact as a reducing agent for the iron oxide
Braise the melting point of iron
Csupply carbon for the reduction
Dcombine with silica gangue to form a fusible slag
Answer & Solution
Correct answer: D. combine with silica gangue to form a fusible slag
1. Limestone decomposes to $CaO$, a **basic flux**.
2. $CaO$ combines with the acidic silica gangue: $CaO + SiO_2 \rightarrow CaSiO_3$ (calcium silicate slag).
3. The molten slag floats on the iron and is easily removed; reduction itself is done by CO.
_Source: Samacheer Kalvi Class 12 Chemistry Vol.1, Unit 1 'Metallurgy', §1.3.2 (Smelting) / Evaluation Q.3 (answers)_
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