Home › Tamil Nadu SSLC (Class 10) › Chemistry › Periodic Classification of Elements › During the smelting of iron in the blast furnace…
During the smelting of iron in the blast furnace, what is the main role of the limestone (CaCO3) added to the charge?
AIt supplies CaO that removes silica impurity as slag
BIt directly reduces ferric oxide to iron metal
CIt acts as the fuel that burns to give heat
DIt increases the carbon content of the iron
Answer & Solution
Correct answer: A. It supplies CaO that removes silica impurity as slag
1. Limestone decomposes in the furnace: CaCO3 gives CaO + CO2.
2. The CaO produced is a basic flux.
3. It combines with the acidic silica impurity: CaO + SiO2 gives CaSiO3 (slag).
4. So limestone provides CaO to remove silica as slag.
The actual reduction of Fe2O3 is done by carbon monoxide, not by limestone.
_Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 8 Periodic Classification of Elements "Metallurgy of Iron", p.124_
Related questions
In cathodic protection against corrosion, the metal that is deliberately attached to corroWhy does dilute or concentrated nitric acid fail to react vigorously with aluminium metal?Using electronegativity values F = 4.0 and Na = 0.9 (approx 1.0), the Na-F bond is best deIn Mendeleev's atomic-mass arrangement, argon (39.95 amu) was placed before potassium (39.In the metallurgy of iron, the charge of roasted ore, coke and limestone is taken in whichWhich of these alloys is a non-ferrous copper alloy made of copper and zinc?In the modern periodic table, the sixth period (atomic numbers 55 to 86) contains how manyA substance added to an ore to lower the fusion temperature and combine with the gangue is