Use of large pieces of printed circuit boards for bioleaching to avoid ‘precipitate contamination problem’ and to simplify overall metal recovery

Abstract

Graphical abstract

Hydrometallurgical Recovery of Metals from Large Printed Circuit Board Pieces

“…The metals present on the PCB are covered by a chemical coating 3 20 21 . This makes metal recovery complicated because the chemical coating inhibits the contact between a lixiviant and the metal.…”

“…Therefore, it is necessary to find an alternative process for removing the chemical coatings from PCBs without loss of metals. Adhapure et al 21 used sodium hydroxide to remove the chemical coating. A similar process was used in the present study to remove the chemical coating.…”

“…2b ). The use of HCl is advantageous compared with the technique of Adhapure et al 21 , who demonstrated complete metal recovery from a large PCB piece using a bioleaching process in 10 days (240 h). They also found poor lead solubilization, which caused the PCB pieces to show traces of solder, even after bioleaching.…”

Recovery of Lead and Noble Metals After Processing Printed Circuit Boards From Cell Phones by Leaching With Mixtures Containing Hydrogen Fluoride

“…at 25 o C. Lead, palladium and silver were recovered in this order, leaving gold as final solid. After 1 h at [35][36][37][38][39][40] o C, 5 mol L -1 HF + 0.3 mol L -1 NaClO mixtures leached the base metals, copper, gold and palladium. Gold was recovered by liquid-liquid extraction with methyl isobutyl ketone.…”

“…36 This coating does not allow leaching of metals present in PCBs. 37,38 Taking into account that epoxy resins are frequently used as coatings, 37,39 the PCBs were immersed in 6 mol L -1 NaOH (10 mL g ), dried at 25 o C and weighed. This solid was placed in a ceramic crucible and calcined in a furnace (600 °C, 3 h).…”