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| Titel |
Simulation of acid mine drainage generation around Küre VMS Deposits, Northern Turkey |
| VerfasserIn |
Cansu Demirel, Mehmet Ali Kurt, Nurgül Celik Balci |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104655
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| Publikation (Nr.) |
 EGU/EGU2015-4084.pdf |
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| Zusammenfassung |
| This study investigated comparative leaching characteristics of acidophilic bacterial strains
under shifting environmental conditions at proposed two stages as formation stage or post
acidic mine drainage (AMD) generation. At the first stage, initial reactions associated with
AMD generation was simulated in shaking flasks containing massive pyritic chalcopyrite
ore by using a pure strain Acidithiobacillus ferrooxidans and a mixed culture of
Acidithiobacillus sp. mostly dominated by A. ferrooxidans and A. thiooxidans at 26oC.
At the second stage, long term bioleaching experiments were carried out with the
same strains at 26oC and 40oC to investigate the leaching characteristics of pyritic
chalcopyrite ore under elevated heavy metal and temperature conditions. During the
experiments, physicochemical characteristics (e.i. Eh, pH, EC) metal (Fe, Co, Cu, Zn)
and sulfate concentration of the experimental solution were monitored during 180
days.
Significant acid generation and sulfate release were determined during bioleaching of the
ore by mixed acidophilic cultures containing both iron and sulfur oxidizers. In the early stage
of the experiments, heavy metal release from the ore was caused by generation of acid due to
accelerated bacterial oxidation of the ore. Generally high concentrations of Co and Cu
were released into the solution from the experiments conducted by pure cultures of
Acidithiobacillus ferrooxidans whereas high Zn and Fe was released into the solution from
the mixed culture experiments. In the later stage of AMD generation and post AMD,
chemical oxidation is accelerated causing excessive amounts of contamination, even
exceeding the amounts resulted from bacterial oxidation by mixed cultures. Acidithibacillus
ferrooxidans was found to be more effective in leaching Cu, Fe and Co at higher
temperatures in contrary to mixed acidophiles that are more prone to operate at
optimal moderate conditions. Moreover, decreasing Fe values are noted in bioleaching
experiments with mixed acidophiles at higher temperatures. Further depleted Fe(III) values
coinciding with decreasing pH may point to precipitation of secondary phases (i.e.
jarosite).
This study revealed that the metals (Fe, Cu, Co and Zn) released during short term
leaching of the ore (34 days) are generally caused by acid produced by dissolution reactions
rather than oxidation. In the long term experiments a more complex biogeochemical reactions
(oxidation and dissolution) take place in conjunction.
Key words: Bioleaching, AMD, heavy metal release, environment, acidophilic bacteria,
Küre copper ore deposits, volcanogenic massive sulfide deposits |
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