The Method of Extracting Copper and Gold by Bacterial Leaching
The methods of extracting gold and copper have significant differences
and therefore require separate attention. Prior to leaching occurring,
either a tailings pile must be built up upon a base of impermeable
rock or a series of holes drilled into the ore, to provide access for
the bacteriaα.
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At process one the bacteria thiobacillus ferro-oxidans and
thiobacillus thio-oxidans, naturally occurring bacteria that obtain
the energy that they need to survive by oxidising Fe2+ and S2- ionsα,
are added to the copper ore. The bacteria in the acidic leaching
solution then convert the insoluble sulphide minerals into a solution
containing Cu2+, Fe2+, Fe3+ and SO42- ions. The acidic solution
provides the optimum pH for the bacteria to work at. Following the
bacterial action, the solution is drained off of the impermeable rock
or pumped out of the ground through the remaining holes and the
remaining solution prepared for concentration and extraction of the Cu2+
ions.
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Extraction and stripping then occur, here the copper ions are
selectively removed from the leaching solution by the "ligand exchange
solvent extractionγ " method. During this a good ligand (a molecule
containing one or more unshared pairs of electronsδ ) is dissolved in
an organic solvent, such as kerosene, which is immiscible with water.
This solution is mixed with ater containing Cu2+ ions and a
displacement reaction occurs.
Cu2+ (aq) + 2LH(organic) → CuL2(organic) + 2H+(aq) Equation 1γ
The copper ions are transferred from the water where they are of a
high concentr...
... middle of paper ...
... is likely to be placed and a thorough environmental
impact assessment carried out to ensure that the processes do not
cause undue environmental damageι. Finally governmental permission
must be obtained before commercial activity can take placeι.
References
α - Article 1 from examination pack: Mining with microbes, John
Merson.
β - How hydrometallurgy and the SX/EW process made copper the "green"
metal, William
Dresher.
γ - Article 2 from examination pack: Extracting copper from leaching
solutions.
δ - Columbia electronic encyclopaedia.
ε - www.allrefer.com/reference/encyclopaedia
η - Article 3 from examination pack: A golden opportunity, Jack
Barrett and Martin Hughes.
θ - www.gaiaguys.net
ζ - Wikipedia, the free online encyclopaedia.
ι - www.deh.gov.au/industry
Purpose: The purpose of the lab was to perform a series of chemical reactions in order to transform copper within different reactions in order to start and end with solid brown copper.
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ferrate(VI) acts as an effective coagulant that is suitable for the removal of metals, non-metals,
In this lab experiment, 0.46 grams of copper went through numerous chemical reactions, including being added to nitric acid for an oxidation-reduction reaction to occur, along with going through a precipitation reaction with sodium hydroxide, a decomposition reaction, and double displacement reaction. Theoretically, if 0.46 grams of copper was at the beginning of the reaction, after going through all of the chemical reactions, 0.46 grams should remain. However, due to some loss of copper through the chemical reactions, such as through decanting, only 0.32 grams of copper remained at the end, leaving a percent recovery of around 69.56%.
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In enrichment, the soil gets filled up to 15mL in a 50mL tube with 1x Arthobacter sp. phage buffer to the soil and vortex, then add 10mL of Lennox LB media, adding on 2.5mL of Anthrobacter sp. culture. Then the sample gets incubated for five days with shaking at
In Lab #5 five we will be exploring the cycle of copper through many chemical reactions. What we are going to do is take a piece of copper metal put it through a series of reactions that change it¡¦s state of matter and chemical formula, but in the end, we will return it to it¡¦s normal solid state. The idea of this lab is to try to recover as close to 100% of the copper we started with. Theoretically, this is possible, but for inexperienced college students, retrieving 100% of the copper metal is near impossible. There are five reactions that the copper will go through.
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