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

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• 作者：Alex Hol ; Renata D. van der Weijden ; Gus Van Weert ; Peter Kondos ; Cees J. N. Buisman
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：August 1, 2011
• 年：2011
• 卷：45
• 期：15
• 页码：6316-6321
• 全文大小：824K
• 年卷期：v.45,no.15(August 1, 2011)
• ISSN：1520-5851

文摘

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 掳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.