Extraction of zinc from zinc blende:

Zinc blende, also known as sphalerite, is the most common ore of zinc. The extraction of zinc from zinc blende involves several steps, including roasting and reduction with carbon.

1. Roasting:
Roasting is the process of heating a substance in the presence of oxygen. In the case of zinc blende, it is roasted in air to convert zinc sulfide (ZnS) into zinc oxide (ZnO) and sulfur dioxide (SO2) gas.

2. Chemical equation:
ZnS(s) + 3/2 O2(g) → ZnO(s) + SO2(g)

The reaction is exothermic, and the temperature is raised to about 1200°C to ensure complete conversion of zinc sulfide into zinc oxide.

3. Reduction with carbon:
The next step is the reduction of zinc oxide to obtain metallic zinc. This reduction is carried out by heating zinc oxide with carbon (in the form of coke or coal) in a furnace. The carbon acts as a reducing agent, removing oxygen from the zinc oxide and forming carbon dioxide gas (CO2).

Chemical equation:
ZnO(s) + C(s) → Zn(g) + CO2(g)

The reduction reaction is highly favorable as zinc has a higher affinity for oxygen than carbon. The temperature in the furnace is maintained around 1300-1500°C to ensure the completion of the reaction.

4. Collecting the zinc:
The zinc vapor produced in the reduction reaction is then cooled and condensed to obtain metallic zinc. This is usually done by passing the zinc vapor through a condenser where it solidifies into a pure metallic form.

5. Purification:
The obtained metallic zinc may still contain impurities, such as lead, iron, and cadmium. These impurities can be removed by various purification techniques, such as fractional distillation or electrolysis.

Conclusion:
The extraction of zinc from zinc blende involves roasting the ore to convert it into zinc oxide, followed by reduction with carbon to obtain metallic zinc. This process is carried out in a furnace at high temperatures. The extracted zinc may then undergo further purification to remove impurities.