.
Metal Extraction Principles
As discussed in lecture 1, pyrometallurgical extraction of metals from natural oxide reserves involve the following steps:
- Removal of oxygen from the valuable mineral.
- Separation of metal from the gangue minerals.
For sulphide ore an additional step to convert sulphide into oxide is required. Several unit processes are employed to extract metal from ore by pyrometallurgical route. These are: roasting, matte smelting, reduction smelting, converting and refining. Different unit processes are combined to extract metal for example.
| Production of metal |
Combination of unit processes |
| Copper |
Roasting +matte smelting +converting +refining Flash smelting +converting +refining.
|
| Zinc & lead |
Roasting +reduction smelting + refining |
| Nickel |
Roasting +matte smelting + reduction smelting +refining. |
| Pig iron |
Reduction smelting |
| Steel |
Reduction smelting +refining. |
Hydrometallurgical extraction is suitable for lean ores .here leaching followed by separation of metal from solution are the principal unit processes. Some examples of Hydrometallurgical extraction are |
| Copper: |
Roasting +leaching +cementation+ electro wining |
| Zinc: |
Roasting +leaching +cementation+ electrolysis |
| Aluminum: |
Leaching + electrolysis |
| Magnesium: |
Leaching + electrolysis |
| Titanium: |
Reduction smelting +leaching +chlorination +reduction by Mg |
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