JEE Challenger
More from General Principles and Processes of Isolation of Elements
ChemEasyAdv 2007 • Paper 1

Extraction of Zinc from Zinc Blende Ore

Extraction of zinc from zinc blende is achieved by

Options

A

electrolytic reduction

B

roasting followed by reduction with carbon

Correct
C

roasting followed by reduction with another metal

D

roasting followed by self-reduction

Topics & Concepts

General Principles and Processes of Isolation of ElementsMetallurgy

Step-by-Step Solution

The extraction of zinc from its sulfide ore, zinc blende (ZnS\text{ZnS}), involves the following chemical steps:

  1. Roasting:
    The concentrated ore is heated in a reverberatory furnace in the presence of excess air at around 1200 K1200\text{ K} to convert zinc sulfide into zinc oxide:
    2ZnS+3O2→Δ2ZnO+2SO2↑2\text{ZnS} + 3\text{O}_2 \xrightarrow{\Delta} 2\text{ZnO} + 2\text{SO}_2 \uparrow

  2. Reduction with Carbon (Coke):
    The zinc oxide obtained is mixed with crushed coke (carbon) and heated to a high temperature (around 1673 K1673\text{ K}) in a fireclay retort:
    ZnO+C→1673 KZn+CO↑\text{ZnO} + \text{C} \xrightarrow{1673\text{ K}} \text{Zn} + \text{CO} \uparrow
    Zinc vaporizes at this temperature (boiling point ≈1180 K\approx 1180\text{ K}) and is collected by rapid cooling (condensation).

Thus, the extraction of zinc from zinc blende is achieved by roasting followed by reduction with carbon.

Therefore, the correct option is (B).

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