The Earth's supply of metal ores is limited. For example, high-grade copper ores are becoming harder to find and mine. There are some alternative methods to extract metals from low-grade copper ores that use living organisms. These have advantages and disadvantages compared to the usual extraction methods.
Phytoextraction is slow but it:
Suggest reasons why phytoextraction reduces damage to the environment.
Mining for metal ores involves quarries, which are large holes in the ground. These create noise, dust and traffic. They also destroy natural habitats. Phytoextraction reduces the need for mining and reduces this damage.
Give one disadvantage of phytoextraction.
It is a slow process.
Bioleaching does not need high temperatures but it produces toxic substances, including sulfuric acid, which damage the environment.
Iron is more reactive than copper. It can displace copper from the leachate. For example:
iron + copper sulfate → iron(II) sulfate + copper
Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)
Since iron is cheaper than copper, the use of scrap iron is a cost-effective way to produce copper from the leachate.
Alternatively, the copper compounds can be dissolved and the solution electrolysed to produce copper metal.