The Earth's resources of metal ores are limited. Copper ores are becoming scarce, so new ways are needed to extract copper from low-grade ores. These methods avoid traditional mining, which involves digging, moving and disposing of large amounts of rock.
Phytomining uses plants to absorb metal compounds from the soil. The plants are harvested and then burned to produce ash that contains the metal compounds. Bioleaching uses bacteria to produce a leachate solution that contains metal compounds.
The metal compounds are then processed to obtain the metal. Copper can be obtained from solutions of copper compounds by displacement using scrap iron, because iron is more reactive than copper, or by electrolysis.
When you evaluate these methods, remember the benefits: less digging and less waste rock, and they work on low-grade ores. The drawbacks are that they are slow compared with traditional mining and plants need land and time to grow.
