Sunday, September 2, 2012

Extraction of Zinc from Zinc Blende


What is "Ore"?

It is a naturally source of a metal, and the metal can be extracted from it. Ore is commonly the oxides of metals (e.g. bauxite is hematite is Al2O3, hematite is Fe2Oand rutile is TiO2) or the sulfides (e.g. pyrite is FeSand chalcopyrite is CuFeS2). By nature, it contains lots of impurities.

What is "Zinc Blende"?


Zinc blende is the ore of zinc and is made up of zinc sulfide and a high percentage of iron.

 Zinc blende, also known as "sphalerite" or "black-jack", has a structure that is relatively similar to that of a diamond. It crystallizes in a cubic crystal system.

How to extract Zinc?

There are 2 steps to the extraction: concentration and reduction.

“Concentration”
It is the process of removing any impurities from the oxide or sulfide of the metal.       

Firstly, zinc blende is combusted in oxygen, resulting in the as follow reaction:
2ZnS (s) + 3O2 (g) --> 2ZnO (s) + 2SO2 (g)

The product of the reaction is then added to a solution that causes ZnO to be hydrophobic and float to the surface.


“Reduction”
A reducing agent is added to the metal oxide to cause it to reduce to the metal.

In the extraction of zinc, carbon monoxide is used to reduce zinc oxide to zinc:
ZnO (s) + CO (g) --> Zn (s) + CO2 (g)



However, in other cases, reduction by electrolysis can be done. During the process, electrons are added to the metal ions directly, producing very pure metals.

2 comments:

  1. Explanation of the methods and effects were very detailed, equations and information given were relevant. However more solutions to the problem can be come up with. For example, something can be done about the carbon dioxide for it to not pollute the water other than just for the company to take responsibility. Also, more can be mentioned about whether reducing via electrolysis or reducing via a reducing agent would be more cost efficient. Would more impure metals be better or purer ones?(in terms of cost-efficiency in the method used)

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  2. I am an igcse student and what I do not get is how is zinc extracted from zince blende?

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