Two-step bioleaching of copper and gold from discarded printed circuit boards (PCB)

• Arda Işıldar ^[1] ; Jack van de Vossenberg ^[1] ; Eldon R. Rene ^[1] ; Eric D. van Hullebusch ^[2] ; Piet N.L. Lens ^[1]
  1. [1] UNESCO-IHE Institute for Water Education (The Netherlands)
  2. [2] Université Paris-Est
• Localización: Waste management, ISSN-e 0956-053X, Vol. 57, 2016 (Ejemplar dedicado a: WEEE: Booming for Sustainable Recycling), págs. 149-157
• Idioma: inglés
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• Resumen

  • An effective strategy for environmentally sound biological recovery of copper and gold from discarded printed circuit boards (PCB) in a two-step bioleaching process was experimented. In the first step, chemolithotrophic acidophilic Acidithiobacillus ferrivorans and Acidithiobacillus thiooxidans were used. In the second step, cyanide-producing heterotrophic Pseudomonas fluorescens and Pseudomonas putida were used. Results showed that at a 1% pulp density (10 g/L PCB concentration), 98.4% of the copper was bioleached by a mixture of A. ferrivorans and A. thiooxidans at pH 1.0–1.6 and ambient temperature (23 ± 2 °C) in 7 days. A pure culture of P. putida (strain WCS361) produced 21.5 (±1.5) mg/L cyanide with 10 g/L glycine as the substrate. This gold complexing agent was used in the subsequent bioleaching step using the Cu-leached (by A. ferrivorans and A. thiooxidans) PCB material, 44.0% of the gold was mobilized in alkaline conditions at pH 7.3–8.6, and 30 °C in 2 days. This study provided a proof-of-concept of a two-step approach in metal bioleaching from PCB, by bacterially produced lixiviants.