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$_3$).

Answer 2

Step 1: Understanding Slag in Metallurgy
Slag is a byproduct formed during the smelting process of ores. It mainly consists of impurities combined with fluxes added to remove unwanted materials. The purpose of slag is to separate the impurities from the molten metal, making it easier to extract pure metal.

Step 2: Smelting of Copper Ore
During copper extraction, copper ore is heated strongly in the presence of flux such as silica (SiO₂). The flux reacts with impurities like iron oxides present in the ore.

Step 3: Formation of Slag
The impurities, mainly iron oxides (FeO), react with silica (SiO₂) to form iron silicate (FeSiO₃), which is the slag. This slag is molten at high temperature and can be easily separated from the molten copper metal because it is lighter and floats on top.

Step 4: Final Conclusion
Thus, the chemical composition of slag formed during the smelting of copper is primarily iron silicate, FeSiO₃. It acts as a vehicle to remove impurities and helps in the purification of copper.