title: Concentration of precious metals during their recovery from electronic waste.
abstract: The rapid growth of electronic devices, their subsequent obsolescence and disposal has resulted in electronic waste (e-waste) being one of the fastest increasing waste streams worldwide. The main component of e-waste is printed circuit boards (PCBs), which contain substantial quantities of precious metals in concentrations significantly higher than those typically found in corresponding ores. The high value and limited reserves of minerals containing these metals makes urban mining of precious metals very attractive. This article is focused on the concentration and recovery of precious metals during pyro-metallurgical recycling of waste PCBs. High temperature pyrolysis was carried out for ten minutes in a horizontal tube furnace in the temperature range 800-1350°C under Argon gas flowing at 1L/min. These temperatures were chosen to lie below and above the melting point (1084.87°C) of copper, the main metal in PCBs, to study the influence of its physical state on the recovery of precious metals. The heat treatment of waste PCBs resulted in two different types of solid products, namely a carbonaceous non-metallic fraction (NMFs) and metallic products, composed of copper rich foils and/or droplets and tin-lead rich droplets and some wires. Significant proportions of Ag, Au, Pd and Pt were found concentrated within two types of metallic phases, with very limited quantities retained by the NMFs. This process was successful in concentrating several precious metals such as Ag, Au, Pd and Pt in a small volume fraction, and reduced volumes for further processing/refinement by up to 75%. The amounts of secondary wastes produced were also minimised to a great extent. The generation of precious metals rich metallic phases demonstrates high temperature pyrolysis as a viable approach towards the recovery of precious metals from e-waste.
authors.affiliation: Centre for Sustainable Materials Research and Technology (SMaRT), School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Cayumil
authors.affiliation: Centre for Sustainable Materials Research and Technology (SMaRT), School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia. Electronic address: ritakhanna@unsw.edu.au.
authors.forename: R
authors.initials: R
authors.lastname: Khanna
authors.affiliation: Centre for Sustainable Materials Research and Technology (SMaRT), School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Rajarao
authors.affiliation: Advanced Materials Technology Department, CSIR-Institute of Minerals and Materials Technology, Bhubaneswar 751013, India.
authors.forename: P S
authors.initials: PS
authors.lastname: Mukherjee
authors.affiliation: Centre for Sustainable Materials Research and Technology (SMaRT), School of Materials Science and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: V
authors.initials: V
authors.lastname: Sahajwalla
mesh_terms: D002516:Ceramics; D003300:Copper / Q000737:chemistry; D059029:Electronic Waste; D006046:Gold / Q000302:isolation & purification; D008669:Metallurgy / Q000379:methods*; D008670:Metals / Q000302:isolation & purification*; D010165:Palladium / Q000302:isolation & purification; D010984:Platinum / Q000302:isolation & purification; D059027:Recycling / Q000379:methods*; D012834:Silver / Q000302:isolation & purification
chemical_list: D008670:Metals; D012834:Silver; D010984:Platinum; D010165:Palladium; D006046:Gold; D003300:Copper
keywords: Concentration; E-waste; PCBs; Precious metals recovery; Recycling