title: Copper extraction from coarsely ground printed circuit boards using moderate thermophilic bacteria in a rotating-drum reactor.
abstract: The current work reports on a new approach for copper bioleaching from Printed Circuit Board (PCB) by moderate thermophiles in a rotating-drum reactor. Initially leaching of PCB was carried out in shake flasks to assess the effects of particle size (-208μm+147μm), ferrous iron concentration (1.25-10.0g/L) and pH (1.5-2.5) on copper leaching using mesophile and moderate thermophile microorganisms. Only at a relatively low solid content (10.0g/L) complete copper extraction was achieved from the particle size investigated. Conversely, high copper extractions were possible from coarse-ground PCB (20mm-long) working with increased solids concentration (up to 25.0g/L). Because there was as the faster leaching kinetics at 50°C Sulfobacillus thermosulfidooxidans was selected for experiments in a rotating-drum reactor with the coarser-sized PCB sheets. Under optimal conditions, copper extraction reached 85%, in 8days and microscopic observations by SEM-EDS of the on non-leached and leached material suggested that metal dissolution from the internal layers was restricted by the fact that metal surface was not entirely available and accessible for the solution in the case of the 20mm-size sheets.
authors.affiliation: Bio&Hydrometallurgy Laboratory, Department of Metallurgical and Materials Engineering, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35400-000, Brazil. Electronic address: mitchel.marques@yahoo.com.br.
authors.forename: Michael L M
authors.initials: ML
authors.lastname: Rodrigues
authors.affiliation: Bio&Hydrometallurgy Laboratory, Department of Metallurgical and Materials Engineering, Universidade Federal de Ouro Preto, Campus Morro do Cruzeiro, Ouro Preto, MG 35400-000, Brazil. Electronic address: versiane@demet.em.ufop.br.
authors.forename: Versiane A
authors.initials: VA
authors.lastname: Leão
authors.affiliation: Centre for Mineral Technology - CETEM, Av Pedro Calmon, 900, 21941-908 Rio de Janeiro, Brazil.
authors.forename: Otavio
authors.initials: O
authors.lastname: Gomes
authors.affiliation: Mineral Processing and Recycling, University of Liege, SartTilman, 4000 Liege, Belgium.
authors.forename: Fanny
authors.initials: F
authors.lastname: Lambert
authors.affiliation: Mineral Processing and Recycling, University of Liege, SartTilman, 4000 Liege, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Bastin
authors.affiliation: Mineral Processing and Recycling, University of Liege, SartTilman, 4000 Liege, Belgium.
authors.forename: Stoyan
authors.initials: S
authors.lastname: Gaydardzhiev
mesh_terms: D000068016:Eubacteriales / Q000378:metabolism*; D003300:Copper / Q000737:chemistry*; D059029:Electronic Waste / Q000032:analysis*; D005296:Ferrous Compounds / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D059027:Recycling / Q000191:economics / Q000379:methods*; D018505:Waste Management / Q000191:economics / Q000379:methods*
chemical_list: D005296:Ferrous Compounds; D003300:Copper
keywords: Bioleaching; Copper; PCB; Rotating-drum reactor; Sulfobacillus thermosulfidooxidans