# bioleaching



## glondor (Oct 11, 2010)

I cut a snip from an article on an interesting twist on metal recovery. credit to this site.

http://www.appropedia.org/Metal_reclamation_and_recycling_of_electronic_waste

Bioleaching
Bioleaching is the process of using bacteria and fungi to separate metals from electronic waste. It promises to be very energy efficient. Organisms such as Bacillus sp., Saccharomyces cereÍisiae, and Yarrowia lipolytica leach lead, copper, and tin from printed circuit boards when shredded into sub-millimeter sizes. Under ideal conditions, T. ferrooxidans and T. thiooxidans were able to mobilize at least 90% of the aluminum, copper, nickel and zinc present [23]. One type of bacteria, C. violaceum, was able to leach gold from larger pieces of electronic waste (5 x 10 mm). It dissolved 14.9% of the approximately 10 mg of gold present as dicyanoaurate [24].
The conditions required for the organisms to survive and leach these metals dictates that the electronic waste piece sizes are extremely small and have a low spatial density. This means that this process would be useful only for recovering metals from the dust generated by shredding.


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## Chumbawamba (Oct 11, 2010)

glondor said:


> This means that this process would be useful only for recovering metals from the dust generated by shredding.



What about the ash after incineration?

Anyway, neat.


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## nikod9410 (May 5, 2011)

HEllo i'm new here, I'm doing my International Bacalaureate Extended Essay, in other words I'm writting an essay on bioleaching and i need to do a research on it +experiment. I've been looking everywhere to find the bacterias i need(acidithiobacillus ferrooxidans) and what experiment to do, because i need an easy one and not too dangerous and complicated that i can do in school laboratory conditions. could anyone help me with ideas and where can i find the bacterias/chemicals and apparatus that i need. just any idea will be fine(sensible ones)
p.s. as gold is pretty expensive i was thinking of doing the experiment with something else as eg iron ore or copper ore to do an irrigational style bioleaching
thanks


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## DKEL (May 10, 2011)

On the topic of Ash after incineration........
...I have read that incineration of material such as wood can lead to some loss of gold via volatility. Anyone with any comments on this?


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## nikod9410 (May 10, 2011)

:mrgreen: what do you mean? :?: hmm :shock:


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## Harold_V (May 11, 2011)

DKEL said:


> On the topic of Ash after incineration........
> ...I have read that incineration of material such as wood can lead to some loss of gold via volatility. Anyone with any comments on this?


Highly doubtful if you're talking about incinerating elemental gold. You do risk losing a minor amount to dusting, depending on the nature of the gold in question. A filtered fume hood goes a long ways towards recovering the small traces that are lost. 

Harold


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## DKEL (Aug 28, 2011)

Sorry I have taken so long to reply to this.
Harold, as per usual you are spot on with your reference to elemental gold.
Elemental gold would be pretty much OK during incineration. Gold in a higher oxidisation state bound up in organic complexes is a different case. This is believed to be the case for gold bioaccumulated in plants. Volatility upon combustion is a real problem in such cases.


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