Alternative methods of extracting metals
Why we need new methods (Higher tier only)
The Earth's supply of (with lots of copper) is running out. Traditional mining involves digging up, moving and disposing of huge amounts of rock, which damages the landscape.
New biological methods extract metals from and waste that contain only small amounts of metal. They avoid traditional mining, but they are slow.
Key terms
Phytomining (Higher tier only)
uses plants to absorb metal compounds:
- Plants are grown on soil that contains metal compounds, such as low-grade ore or mine waste.
- The plants absorb the metal compounds through their roots and build them up in their leaves.
- The plants are harvested and burned.
- The ash contains metal compounds, which are dissolved in acid to make a solution.
Key terms
Bioleaching and getting the metal (Higher tier only)
uses bacteria to produce solutions that contain metal compounds. It can produce toxic substances, which must be dealt with carefully.
The metal compounds from phytomining or bioleaching are then turned into the metal by:
- with scrap iron, which is more reactive than copper and cheap: Fe + CuSO₄ → FeSO₄ + Cu
- of the solution, with copper collecting at the cathode