What are bioleaching and phytomining?

Bioleaching and phytomining are two methods of extracting metals from low-grade ores using biological means.

Bioleaching is a process that uses bacteria to extract metals from their ores. It's a type of biomining, where biological processes are used to extract valuable elements from ores. In bioleaching, bacteria feed on the low-grade ores and through their natural biological processes, they produce leachate, a solution containing the metal. This solution is then collected and the metal is extracted from it. This method is particularly useful for extracting metals like copper and gold.

Phytomining, on the other hand, uses plants to extract metals from low-grade ores. Certain plants, known as hyperaccumulators, have the ability to absorb metals from the soil through their roots. These plants are grown on low-grade ore bodies, and as they grow, they absorb the metal. Once the plants are mature, they are harvested and burned. The ash that remains after burning contains a higher concentration of the metal, which can then be extracted. This method is often used to extract nickel.

Both bioleaching and phytomining are considered more environmentally friendly than traditional mining methods. They do not require the large-scale excavation of land or the use of harmful chemicals. However, they are slower processes and may not be suitable for all types of ores. They are most effective for extracting metals from low-grade ores, where traditional mining methods may not be economically viable.