Processing of Arsenopyritic Gold Concentrates by Partial Bio-Oxidation Followed by Bioreduction

A. Hol, R.D. van der Weijden, G. van Weert, P. Kondos, C.J.N. Buisman

Research output: Contribution to journalArticleAcademicpeer-review

3 Citations (Scopus)

Abstract

Gold is commonly liberated from sulfide minerals by chemical and biological oxidation. Although these technologies are successful, they are costly and produce acidic waste streams. Removal of mineral-sulfur to overcome the mineralogical barrier could also be done by bioreduction, producing hydrogen sulfide (H2S). To make the sulfur within these minerals available for bioreduction, the use of partial bio-oxidation as a pretreatment to oxidize the sulfides to elemental sulfur was investigated in gas lift loop reactor experiments. Experiments at 35 °C using a refractory concentrate showed that at pH 2 arsenopyrite is preferentially partially oxidized over pyrite and that elemental sulfur can be subsequently converted into H2S at pH 5 via bioreduction using H2 gas. A single partial bio-oxidation/bioreduction treatment increased the gold recovery of the concentrate from 6% to 39%. As elemental sulfur seems to inhibit further oxidation by covering the mineral surface, several treatments may be required to reach a gold recovery >90%. Depending on the number of treatments this method could be an interesting alternative to bio-oxidation
Original languageEnglish
Pages (from-to)6316-6321
JournalEnvironmental Science and Technology
Volume45
Issue number15
DOIs
Publication statusPublished - 2011

Keywords

  • sulfur
  • dissolution
  • bioreactor
  • mechanisms
  • reduction
  • oxidation
  • minerals
  • progress
  • removal
  • iron

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