Extraction of Zinc from Zinc Blende

Extraction of Zinc from Zinc Blende 
Zinc blende has a giant crystal lattice structure with strong electrostatic forces of attraction between zinc and sulphur in an tetrahedral structure.


As such, a blast furnace is required to extract zinc from zinc blende.


 Using the Blast Furnace Steps Taken to Extract Zinc from Zinc Blende 
1) Zinc Blende's Ore is mixed with oxygen to produce Zinc Oxide and Sulphate. 
    2ZnS(s) + 3O2 (g) ==> 2ZnO(s) + 2SO2 (g) 
2) Zinc Oxide is mixed with Coke (Carbon) in a fireclay retort. Carbon, the reducing agent, reduces Zinc Oxide to Zinc. Zinc Oxide is being reduced as Zinc Oxide loses oxygen molecules from Zinc Oxide to form      Zinc. ZnO(s) + C(s) ==> Zn(s) + CO (g) 

 How the extraction method has an impact on the environment 
Since carbon monoxide is the product, it causes the environment to be filled with more carbon monoxide, which is poisonous. When carbon monoxide is being breathed in, it binds to the red blood cell more easily than oxygen binding to the red blood cell. This causes more carboxyhaemoglobin to be formed instead of oxyhaemoglobin, leading to the amount of oxygen in a person's body to be reduced and can cause death of a person. 

Carbon monoxide is also a greenhouse gas, which can contribute to global warming as well.

Solutions: 

In order to prevent carbon monoxide from forming, an alternative method, electrolysis can be used when done will not release any harmful substances into the environment.

Zinc sulphide is oxidized by oxygen to produce zinc oxideand sulphur dioxide.

2ZnS(s) + 3O₂(g) è ZnO(s) + 2SO₂(g)

Most of the zinc in the zinc sulphide are oxidized form Zinc Oxide. Some of the zinc reacts with iron to form zinc ferrite.

Sulphur dioxide is then further processed to produce sulphuric acid.

Zinc oxide is then mixed with concentrated sulphuric acid to produce zinc sulphate.

ZnO(s) + H₂SO₄ (aq) è ZnSO₄ (aq) + H₂O(l)

The end product will be water and water will not be harmful to the environment.

Links:
http://www.chemguide.co.uk/inorganic/extraction/iron.html
http://chem-guide.blogspot.sg/2010/04/occurrence-and-extraction-of-zinc-from.html
http://kennychemistry.blogspot.sg/2012/09/extraction-of-zinc-from-zinc-blende.html
http://www.cpsc.gov/cpscpub/pubs/466.html
http://en.wikipedia.org/wiki/Sphalerite