Metal Extraction by Biological Methods

Biological Methods for Metal Extraction refer to utilising living organisms such as bacteria, fungi, or plants to extract metals from ores in a process known as bioleaching.
This method is increasingly being used as a more environmentally-friendly and sustainable way to extract metals compared to traditional mining methods that are energy-intensive and cause a lot of pollution.
Bioleaching involves bacteria which feed on the low-grade ores. As they metabolise the ore, they produce leachate, a solution that contains the metal. The metal can then be extracted from this solution.
Bioleaching is especially useful in extracting copper and gold from their ores, but can also be used for other metals, including nickel, cobalt and zinc.
An advantage of bioleaching is that it allows for the extraction of metals from ores that are too low grade for conventional methods of extraction, thus making it a cost-effective method.
Another plus point of bioleaching is its ability to be done on site. It can be carried out in heaps and lagoons, reducing the need for transportation, thereby saving energy and decreasing emissions.
Phytomining is another biological method for metal extraction. In this method, plants, often hyperaccumulators (plants that can tolerate and accumulate high levels of specific metals), are used to absorb metals from the soil. When these plants are harvested and incinerated, the metal can be extracted from the ash.
Phytomining is particularly effective for extraction of nickel and has been exploited to rehabilitate nickel mining sites.
A limitation of both methods is the time it takes. Both processes are slower than traditional methods of extraction.
There are also concerns about the inadvertent environmental impacts of introducing new species (bacteria or plants) into an ecosystem. These organisms might become invasive, causing harm to native species or altering habitats.
Understanding and employing these biological methods is part of the wider move towards sustainable development. By harnessing naturally occurring biological processes, we can extract essential materials in a way that has less environmental impact.