Biomining with microorganisms
2023-12-06T13:07:00Z
Mining
Biomining, also known as bioleaching or microbial mining, is a process that uses microorganisms (referred to as ‘microbes’) to extract metals from ores and minerals. This approach is an alternative to traditional mining and is more environmentally friendly. The microorganisms involved in microbial mining are typically bacteria, archaea or fungi that have the ability to oxidise and solubilise metals from mineral ores.
What does biomining extract?
The microbes used in microbial mining are acidophilic, meaning they thrive in acidic environments. They obtain energy by oxidising metal sulfides, such as iron, copper and zinc sulfides, in the ore. This oxidation process releases metal ions into the solution, making it easier to extract and recover the metals.
“Biomining is the kind of technique promised by science fiction: a vast tank filled with microorganisms that leach metal from ore, old mobile phones and hard drives. It sounds futuristic, but it’s currently used to produce about 5% of the world’s gold and 20% of the world’s copper. It’s also used to a lesser extent to extract nickel, zinc, cobalt and rare earth elements. But perhaps its most exciting potential is extracting rare earth elements, which are crucial in everything from mobile phones to renewable energy technology.” – Marcos Voutsinos, University of Melbourne.
Common metals gained from biomining:
- Gold
- Silver
- Uranium
- Nickel
- Copper
- Cobalt
- Zinc
What are microbes?
The important thing to understand about microbes is that they are consumers with a voracious appetite. They consume sunlight, nitrogen, sulfur, nutrients – and even each other. But of course, they also consume metal, which makes them useful for mining.
Microbes are organisms that are too small to be seen without using a microscope, so they include things like bacteria, archaea, and single cell eukaryotes — cells that have a nucleus, like an amoeba or a paramecium.
American Museum of Natural History
Biomining methods
1. Heap leaching
In this process, ore is crushed and stacked on a ‘heap’ - an impermeable linen pad. It needs to be impermeable so the acid that is poured on the ore does not seep through. The acid separates microscopic metals, like gold, from the rock.
2. Dump leaching
Similar to heap leaching, dump leaching involves soaking ore in acid to separate the valuable minerals. The processes differ in that as the ore in heap leaching is crushed and stacked, whereas in dump leaching it is dumped intact.
3. Agitated leaching
Agitated leaching involves extracting minerals from ores by dissolving them in a solvent. Miners put ore in a tank with a solvent and agitate the mixture to speed up the reaction.
