Geology

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Dear "hard core" economic geologist or "softer" geo-connoisseur,

Maybe you are able to describe some notions or answer some questions associated to geology? Maybe you are even interested in applying to become an administrator of the geology-section in BioMineWiki?

Geology notions that need an explanation

Fields Minerals Geologic processes and terms Evaluation, exploration, mining, metallurgy

Structure

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Hypogenic versus supergenic

  • Formation of minerals (or of the earth surface) - does that involve microbes? Does it involve bioleaching microbes?
  • Have minerals close to the surface already been leached? Can it be said that bioleaching is only speeding up conventional natural oxidizing processes?
  • If bioleaching bacteria have existed for many millions of years and so have rocks and mountains – why is not all possible bioleaching already done and the microbes starved to death?
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How to investigate whether or not a deposit is suitable for bioleaching

  • Chemical and size analysis
    • Why?
    • Briefly describe the methods XRD and X-ray mapping and perhaps other methods relevant for such an investigation
    • How small should the size of the particles preferably be? I have heard that crushing and grinding are pretty energy intensive activities ...
    • What about the ore texture?
  • What composition of minerals makes bioleaching a suitable method? Why? Maybe one can mention
    • sulphur compounds because these are the energy source for some bioleaching microbes and the oxidation of such compounds results in low pH necessary for efficient bioleaching
    • Iron-compounds such as pyrite since this will supply the leaching reaction with ferric iron necessary for oxidation of metal sulphides.
    • Silver (and Pb?) because it usually inhibits bioleaching microorganisms and makes bioleaching more difficult unless some adaption of the microbes is made. How long does such an adaption take?
    • Refractory gold since a biooxidation preparation-step makes the ore more prone to the added cyanide used for gold extraction. Thereby less toxic cyanide is needed.
    • Cation-exchangers like propylites because they has a high water absorbance and will retain leached metal ions
      • Does it matter that the propylites are also expandable?
    • Buffering minerals as CaCO3 etc will affect acid-consumption ...
  • What about the location of mine or waste-deposit? Perhaps comments on:
    • Water-access
      • Salt-water
    • What about heat-losses? Can heat-loss to some extent be avoided by placing the heap in a clever way in the surroundings? Is it even considered?
    • Closeness to city, inhabited area. Social aspects
  • Legislation. When is it legal to start bioleaching? When is it not?
  • Is waste-management considered already from the start? Where and how to store sulphidic metal containing waste? Are there any ponds? Is a landfill always possible?
  • Transportation of ore, rock
  • Volcanic activity increases the possibility for thermophilic bioleaching microorganisms …
  • Climate: How does precipitation, wind and heat affect the outcome of a bioleaching operation?

See also

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