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Microbial Mining

Microbial Mining. Jennifer Caufield Alex Grippe Amy Weinberger. Outline. Brief History on Mining Industry Introduction of the role microbes play mining Methods of Microbial Mining Copper Gold Conclusions. Mining History. Since 4500 B.C. Conditions for traditional methods:

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Microbial Mining

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  1. Microbial Mining Jennifer Caufield Alex Grippe Amy Weinberger

  2. Outline • Brief History on Mining Industry • Introduction of the role microbes play mining • Methods of Microbial Mining • Copper • Gold • Conclusions

  3. Mining History • Since 4500 B.C. • Conditions for traditional methods: • High grade ore • Inexpensive energy • Limited environmental concern • Regulations – decline in mining industry

  4. Microbes used in Bio-mining must… • Catalysts • Mesophiles • Chemoauotlithotrophs • Inorganic sources for energy • CO2 for carbon source • Aerobes • Obligate acidophiles

  5. Thiobacillus ferrooxidans 4FeS2 + 15O2 + 2H2O  2Fe2(SO4)3 + 2H2SO4

  6. Methods of Microbial Mining

  7. Direct vs. Indirect leaching Direct Bio leaching • enzymes used for oxidation • Electrons are transported through cell membrane Indirect Bio Leaching • Energy generated by Bacteria

  8. Copper • Most important metal being recovered by bio-mining • Involves the conversion of copper sulfides to copper sulfates

  9. Old Process: Gold is extracted from ores using cyanide Pretreatment is required to open the molecular structure of the ore so as to allow the cyanide to make contact with the gold Concentrate must be heated to 700 degrees Celsius or digested with acid under pressure Gold Bio-oxidation

  10. New Process: Bio-mining bacteria decomposes ores and concentrates, and at more normal temperatures and at atmospheric pressure. Ores are then flushed with cyanide to remove the gold Gold Bio-Oxidation, cont.

  11. Advantages of Bio-oxidation • After bio-oxidation, 95% of the gold can be recovered, as opposed to normally 30-50% • Relatively little of the ore needs to be decomposed to allow gold recovery • Bio-oxidation takes advantage of natural weaknesses in structure • Costs 2-3 times less

  12. Conclusions • Has become a very significant part of industrial microbiology • Is a big part of the fermentation industry • Makes metal recovery more economical and environmentally friendly

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