A new approach for the recovery of precious metals from solution and from leachates derived from electronic scrap

• Published in: Biotechnology and bioengineering Vol. 96; no. 4; pp. 631 - 639
• Main Authors: Macaskie, L.E., Creamer, N.J., Essa, A.M.M., Brown, N.L.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.03.2007; Wiley; Wiley Subscription Services, Inc
• Subjects: Aerobiosis - physiology; Aqueous solutions; Bacteria; Biodegradation, Environmental; Biogas; Biological and medical sciences; Biotechnology; Chemical Precipitation; Conservation of Natural Resources; Electron Probe Microanalysis; Electronics; Fundamental and applied biological sciences. Psychology; Gold - isolation & purification; gold recovery; Industrial Waste; Klebsiella pneumoniae; Klebsiella pneumoniae - growth & development; Klebsiella pneumoniae - metabolism; Metals; Palladium - isolation & purification; palladium recovery; Silver - isolation & purification; silver recovery; Sulfides - isolation & purification; Waste Disposal, Fluid; X-Ray Diffraction; Silver; Gold; gold recovery; silver recovery; Electronics; Bacteria; Biogas; Metal; Leachate; Klebsiella pneumoniae; palladium recovery; Enterobacteriaceae
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.21108

A new approach is described for the recovery of precious metals (PMs: Au, Pd and Ag) with >99% efficiency from aqueous solution utilising biogas produced during the aerobic growth of Klebsiella pneumoniae. Gold was recovered from electronic scrap leachate (∼95%) by this method, with some selectivity against Cu. The recovered PM solids all contained metal and sulphur as determined by energy dispersive X‐ray microanalysis (EDX). X‐ray powder diffraction analysis (XRD) showed no crystalline metal sulphur compounds but a crystalline palladium amine was recorded. Silver was recovered as a sulphide (found by EDX), carbonate and oxide (found by XRD). EDX analysis of the Au‐precipitate showed mainly gold and sulphur, with some metallic Au(0) detected by XRD. The gold compound was shock‐sensitive; upon grinding it detonated to leave a sooty black deposit. Biotechnol. Bioeng. 2007;96:631–639. © 2006 Wiley Periodicals, Inc.