Biomining
Contents
Bio-mining and Bio-leaching
Microorganisms are used in the mining industry for their natural ability to digest, absorb, and change the quality of different chemicals and metals. It is often a low capital, low energy input and a low operational cost process. Low concentrations of ores as well as mine tailings may be mined.
A perfect example is copper mining, nearly 25% of which is today performed with the organism Acidithiobacillus ferrooxidans that leaches copper from mine tailings. Related fields: bioleaching, biooxidation, biosorption, bioreduction, bioaccumulation, bioprecipitation, bioflotation, bioflocculation, and biosensors, as well as microbiological research.
Biohydrometallurgy
is an interdisciplinary field involving processes that: 1) are driven by microbes - bio. 2) mainly take place in aqueous environment - hydro and 3) deals with metal production and treatment of metal containing materials and solutions. More here: [1]
Applications and Product Ecology
- Aluminum: As was previously demonstrated, aluminum can be extracted from clays. While only very preliminarily explored, aluminum-bio-extraction may become a possibility in the future, as demonstrated here
- Phosphorus: duckweed for phosphate biomining - Use of duckweed for phosphate reclamation from wastewater. Duckweeds are highly efficient at extracting phosphates from wastewater, down to trace concentrations. Excavated subsoil could be dissolved in water, and duckweeds would extract the phosphates from the muddy water. The processed sediment can later still be used to make compressed earth blocks, for pottery or for aluminum extraction.
- Copper - the extraction technique with Acidithiobacillus ferrooxidans should be perfectly doable on the small scale
- Nitrogen: fixation from air - cyanobacteria used in Asia, grown in shallow ponds which then dry out, leaving green sludge, a high-nitrogen natural fertilizer (... this is not mining though !)
- further refinement of components after extraction of metals from clay: a process with potentially much lower energy requirements than smelting
Considerations and Discussion
- to what extent can biomining from clays be made practical ? (big advantage: already in powder form)
- how can we get a good idea what microorganisms we are dealing with ?
- Question: if Acidithiobacillus ferrooxidans leaches out copper, could it be used to produce copper from soil? There's about 1kg of copper in every six tons of soil, though for some soils it could be a kilo per two tons.
Links
- Wikipedia entries for Biomining, Bioleaching, Biohydrometallurgy and Acidithiobacillus
- BioMineWiki- a wiki on biohydrometallurgy
- Biomining - A Useful Approach Toward Metal Extraction
- Biomining: A Green Technology to Mine Valuable Metals
- The BioMinE Project (Europe)
