Abstract
Bacterial leaching of metal sulphides is now recognized as an attractive industrial process and is successfully applied to recover copper from mixed and low grade sulphide ores. One of the main problems in the operation of bacterial leaching plants is the control of dissolved iron, generally present as a major impurity in all the treated sulphide ores.
The present study examines the behavior of the dissolved iron species in bacterial leaching systems and the different interactions observed between iron, bacteria and mineral solids. The rate of oxidation of ferrous iron by bacteria was studied for both free and attached bacteria, this showed a decrease of ferrous iron oxidation activity for bacteria attached to inorganic solids. On the other hand, the presence of attached bacteria on solid elemental sulphur and metal sulphides increases the reduction rate of ferric ions on the solid surface through oxido-reduction reactions.
In the presence of bacteria, the precipitation of oxidized ferric iron was increased and ferric ion precipitates even when the conditions in the bulk solution would permit its solubility. Moreover, the presence of solid particles increases iron precipitation. The precipitates were analyzed for iron and sulphate contents showing an iron/sulphate ratio very similar to that of jarosite. In the case of chemical precipitation of ferric ions by increasing pH, the sulphate content of the precipitate was lower, showing that in this case the precipitate was mainly ferric hydroxide.
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© 1994 Springer Science+Business Media Dordrecht
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Wiertz, J.V., Ríos, I.G., Miguel, B.E. (1994). Dissolved iron equilibrium in bacterial leaching systems. In: Hydrometallurgy ’94. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-1214-7_24
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DOI: https://doi.org/10.1007/978-94-011-1214-7_24
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-4532-2
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