Hydrometallurgical process for extraction of metals from electronic waste-part I: material characterization and process option selection

  • Željko Kamberović The University of Belgrade, Faculty of Technology and Metallurgy
  • Marija Korać The University of Belgrade, Faculty of Technology and Metallurgy
  • Dragana Ivšić The University of Belgrade, Faculty of Technology and Metallurgy
  • Vesna Nikolić The University of Belgrade, Faculty of Technology and Metallurgy
  • Milisav Ranitović The University of Belgrade, Faculty of Technology and Metallurgy
Keywords: electronic waste, printed circuit boards, recycling, hydrometallurgy, copper, precious metals

Abstract

Used electronic equipment became one of the fastest growing waste streams in the world. In the past two decades recycling of printed circuit boards (PCBs) has been based on pyrometallurgy, highly polluting recycling technology which causes a variety of environmental problems. The most of the contemporary research activities on recovery of base and precious metals from waste PCBs are focused on hydrometallurgical techniques as more exact, predictable and easily controlled. In this paper mechanically pretrated PCBs are leached with nitric acid. Pouring density, percentage of magnetic fraction, particle size distribution, metal content and leachability are determined using optical microscopy, atomic absorption spectrometry (AAS), X-ray fluorescent spectrometry (XRF) and volumetric analysis. Three hydrometallurgical process options for recycling of copper and precious metals from waste PCBs are proposed and optimized: the use of selective leachants for recovery of high purity metals (fluoroboric acid, ammonia-ammonium salt solution), conventional leachants (sulphuric acid, chloride, cyanide) and eco-friendly leachants (formic acid, potassium persulphate). Results presented in this paper showed that size reduction process should include cutting instead of hammer shredding for obtaining suitable shape & granulation and that for further testing usage of particle size -3 +0.1mm is recommended. Also, Fe magnetic phase content could be reduced before hydro treatment.

Published
2018-07-20
Section
Articles - archived