Question

The chemical composition of 'slag' formed during the smelting process in the extraction of copper is:

• A. Cu$_2$O + FeS
• B. FeSiO$_3$
• C. CuFeS$_2$
• D. Cu$_2$S + FeO

Hint:

Slag formation is crucial in metallurgy as it helps remove unwanted iron impurities during copper extraction.

Answer 1

The Correct Option is B

Step 1: Understanding Smelting in Copper Extraction 
- Copper is extracted from copper pyrites (CuFeS$_2$) in a blast furnace. - The ore contains iron as an impurity, which must be removed as slag. Step 2: Chemical Reactions During Smelting 
- Iron present as FeS gets oxidized to iron oxide (FeO): \[ 2FeS + 3O_2 \rightarrow 2FeO + 2SO_2 \] - FeO then reacts with silica (SiO$_2$) to form ferrous silicate (FeSiO$_3$), which is the slag: \[ FeO + SiO_2 \rightarrow FeSiO_3 \] Step 3: Role of Slag 
- The formation of FeSiO$_3$ helps in removing iron impurities from the molten copper. - The lighter FeSiO$_3$ floats on top of the molten copper and is separated easily. 
Final Answer: The slag formed is ferrous silicate (FeSiO$_3$).