The effect ultrasound sonification on nitric acid leaching of pyrolyzed printed circuit board powder

Abstract

Numerous electronic devices are put out of use every day, and most of them have printed circuit boards (PCBs) that are lased and imbued with various precious and valuable metals in abundant amounts. This makes PCB an unexploited resource of the future from whom many metals such as Cu, Zn, Sn, Al, Li, Co, Nd, Pd, Pt, and Ba can be extracted. Since leaching plastic polymers can lead to the vaporization of toxic fumes, to avoid this the PCB are pyrolyzed. The PCB is crushed and the pyrolyzed product is a powder that can easily be separated into metallic and nonmetalic fractions. The aim of this work is to investigate the influence of ultrasound sonification on the nitric acid leaching of pyrolyzed printed circuit board (PPCB) powder. The impact of ultrasound sonification had a positive effect on the leaching degree for all investigated metals except for Cobalt. The biggest difference in leaching degree was for Lithium while the smallest was for platinum. Because of the complexity of the PPCB powder system overall, the measurement of oxidation-reduction potential (ORP) didn’t yield any insight into the leaching mechanism since the measured values mainly followed the expected trend due to nitric acid degradation.