Question

Which of the following is not related to extraction of copper?

• A. \( 2\text{Cu}_2\text{S} + 3\text{O}_2 \to 2\text{Cu}_2\text{O} + 2\text{SO}_2 \)
• B. \( 2\text{FeS} + 3\text{O}_2 \to 2\text{FeO} + 2\text{SO}_2 \)
• C. \( \text{FeO} + \text{SiO}_2 \to \text{FeSiO}_3 \)
• D. \( \text{SiO}_2 + \text{CaO} \to \text{CaSiO}_3 \)

Hint:

Flux selection: - If impurity is acidic (\( \text{SiO}_2 \)), use basic flux (\( \text{CaO} \)) [Iron Metallurgy]. - If impurity is basic (\( \text{FeO} \)), use acidic flux (\( \text{SiO}_2 \)) [Copper Metallurgy].

Answer 1

The Correct Option is D

Step 1: Understanding Copper Extraction:

Copper is usually extracted from Copper Pyrites (\( \text{CuFeS}_2 \)). - Roasting/Smelting: The ore is heated. \( \text{CuFeS}_2 \) breaks into \( \text{Cu}_2\text{S} \) and \( \text{FeS} \). - Oxidation: \( \text{FeS} \) oxidizes to \( \text{FeO} \) (Reaction B). \( \text{Cu}_2\text{S} \) partially oxidizes to \( \text{Cu}_2\text{O} \) (Reaction A). - Slag Formation: The main impurity is Iron oxide (\( \text{FeO} \), basic). Silica (\( \text{SiO}_2 \), acidic) is added as a flux to remove it. \( \text{FeO} + \text{SiO}_2 \to \text{FeSiO}_3 \) (Slag) (Reaction C).
Step 2: Analyzing Option D:

- Reaction (D): \( \text{SiO}_2 + \text{CaO} \to \text{CaSiO}_3 \). This reaction involves removing Silica (\( \text{SiO}_2 \)) impurity using Calcium Oxide (\( \text{CaO} \)) flux. This is the characteristic slag formation step in the Metallurgy of Iron (Extraction from Haematite in a Blast Furnace). In Copper metallurgy, Silica is the flux, not the impurity to be removed by lime. Therefore, this reaction is not part of the standard copper extraction process.
Step 3: Final Answer:

Reaction (D) is not related.