Chloride-promoted leaching of chalcopyrite concentrate by biologically-produced ferric sulfate

✍ Scribed by Päivi H-M Kinnunen; Jaakko A Puhakka

• Publisher: Wiley (John Wiley & Sons)
• Year: 2004
• Tongue: English
• Weight: 150 KB
• Volume: 79
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/jctb.1051

✦ Synopsis

Abstract

The effects of chloride ions on chalcopyrite leaching by biologically‐produced ferric sulfate solution and on the iron‐oxidizing culture were determined. Chloride ions significantly increased chalcopyrite leaching by ferric sulfate at 67 °C and 87 °C, but slowed down the leaching at 50 °C. At 90 °C, chloride at 5 g dm^−3^ (0.25 g Cl^−^ g^−1^ concentrate) increased the copper yield from 60 to 100% in approximately 2 weeks. Further increase in Cl^−^ concentration did not affect the leaching. Addition of chloride increased both leaching yields and iron precipitation, which shows that the passivation was not due to iron precipitation. A decreased Ag‐potential of 60 mV against an Ag/AgCl reference electrode in the presence of Cl^−^ indicates the accumulation of partially oxidized forms of dissolved sulfur compounds such as thiosulfate and polythionate instead of elemental sulfur and, thus, a decrease in sulfur passivation. A chloride concentration of 5 g dm^−3^ did not affect the iron oxidation rate of the iron‐oxidizing culture dominated by Leptospirillum ferriphilum. Copyright © 2004 Society of Chemical Industry