Extraction of zinc from zinc blende

Question: Extraction of zinc from zinc blende – “even number” groups

• Explain how the metal is extracted from its ore and how the extraction method has an impact on the environment.

1)What is Zinc Blende/Sphalerite/Black-Jack

Sphalerite

It is a mineral that is a chief ore of zinc. It has a chemical formula of (Zn,Fe)S. It consists mainly of Zinc Sulfide in crystalline form but always almost contain variable amounts of Iron. The Iron content affects it's coulou and it is usually found in association with galena, pyrite, and other sulfides with calcite, dolomite and fluorite.

Zinc Blende has a crystal structure. In the structure, zinc and sulfur atoms are tetrahedrally coordinated. It's structure is closely related to diamond.

2)How zinc is extracted from zinc blende

Firstly, after the grinding of the ore,

zinc sulfide undergoes froth floatation, a process to separate materials based on whether it is hydrolilic or hydrophobic, to obtain an ore concentration. Note that at this point of time, only 50% of the ore concentration is zinc.

Next,
Roasting of the ore concentration will then convert the zinc sulfide into zinc oxide and sulfur dioxide. Based on the equation below:

2 ZnS + 3 O₂ → 2 ZnO + 2 SO₂

The sulphur dioxide is needed for the leaching process later on.

After this process, prometallurgy is by reducing the zinc oxide with carbon or carbon monoxide at a high temperature of 950 degrees Celcius.

From this reducing process, zinc vapour is distilled.

The equations for the reaction are as follows:

2 ZnO + C → 2 Zn + CO₂

ZnO + CO → Zn + CO₂                      

OR

After the  roasting of the ore, an electrowinning process will leach off zinc from its ore

ZnO + H₂SO₄ → ZnSO₄ + H₂O

And thereafter, electrolysis is used to produce zinc metal via this equation:

2 ZnSO₄ + 2 H₂O → 2 Zn + 2 H₂SO₄ + O₂

Note that the sulfuric acid is then recycled to be used in the leaching stage.

en.wikipedia.org/wiki/Sphalerite