LIBS and Hyperspectral Imaging as a Real-Time Process Control Tool for Metal Recovery from E-Waste

The rapid increase in e-waste creates challenges, requiring more efficient recycling methods. This study explores the application of laser-induced breakdown spectroscopy (LIBS) combined with hyperspectral imaging to monitor leaching processes of Ag, Au, Cu and Sn in e-waste recycling. The method involved the use of sequential leaching strategies of printed circuit boards (PCBs), the best strategy was applied using HNO3 for Cu, HCl for Sn and thiourea/Fe(NO3)3 for Ag and Au. Inductively coupled plasma optical emission spectrometry (ICP OES) was used to validate the metal extraction efficiency, achieving recoveries of 100% for Cu and Ag, 97% for Sn and 86% for Au. LIBS spectra showed a strong correlation with the ICP OES data, revealing reductions in the emission signals corresponding to the extracted elements. Hyperspectral imaging provided an analysis of the spatial distribution of trace elements, confirming the progressive extraction of metals. The results indicate that LIBS, associated with multivariate analysis, offers a fast and economical alternative.