Extraction of zinc from zinc blende is achieved by:

A. electrolytic reduction

B. roasting followed by reduction with carbon

C. roasting followed by reduction with another metal

D. roasting followed by self reduction

The extraction of zinc from zinc blende, which is primarily composed of zinc sulfide (ZnS), is a fascinating process that involves several key steps. The correct method for extracting zinc from zinc blende is B: roasting followed by reduction with carbon. Let’s break down why this is the case and how the process works.

Understanding the Extraction Process

Zinc blende (ZnS) must first be converted into a more suitable form for extraction. This is where roasting comes into play. Roasting involves heating the zinc sulfide in the presence of oxygen, which leads to a chemical reaction that converts the sulfide into zinc oxide (ZnO) and sulfur dioxide (SO2).

The Roasting Step

During roasting, the reaction can be summarized as follows:

• 2 ZnS + 3 O2 → 2 ZnO + 2 SO2↑

This step is crucial because it transforms the zinc sulfide into zinc oxide, which is more amenable to reduction. The sulfur dioxide gas produced is typically released into the atmosphere, and the zinc oxide remains as a solid.

Reduction with Carbon

Once we have zinc oxide, the next step is to reduce it to obtain metallic zinc. This is achieved by heating the zinc oxide with carbon (usually in the form of coke) in a high-temperature furnace. The reduction reaction can be represented as:

• ZnO + C → Zn + CO

In this reaction, carbon acts as a reducing agent, donating electrons to zinc oxide and converting it into zinc metal while forming carbon monoxide (CO) as a byproduct.

Why Other Options Are Incorrect

Let’s briefly examine why the other options are not suitable for extracting zinc from zinc blende:

• A. Electrolytic reduction: This method is typically used for metals that are more reactive than zinc, such as aluminum. It is not the primary method for zinc extraction from its ore.
• C. Roasting followed by reduction with another metal: This is not a common practice for zinc extraction. Other metals are usually not used for reducing zinc oxide.
• D. Roasting followed by self-reduction: Self-reduction is not applicable in this context, as it generally refers to a process where a metal oxide is reduced by its own metal, which does not occur with zinc oxide.

Conclusion

In summary, the extraction of zinc from zinc blende is effectively achieved through roasting followed by reduction with carbon. This method is efficient and widely used in the metallurgical industry, allowing for the production of high-purity zinc metal. Understanding these processes not only highlights the chemistry involved but also the practical applications in metal extraction.