The Earth's resources of metal ores are limited. Copper ores are becoming scarce, so new ways of extracting copper from low-grade ores are needed. Two of these are phytomining and bioleaching. Both avoid traditional mining, which means 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, which produces ash that contains the metal compounds. Bioleaching uses bacteria to produce a leachate solution that contains metal compounds.
The metal compounds can then be processed to obtain the metal. For example, 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, compare them with traditional mining. They are better for the environment and make use of low-grade ores, but they are usually slower.