Noble-metals recovery from printed circuit boards: a multidisciplinary approach towards sustainability

A robust database of the noble metals (NM) content of different classes of Printed Circuit Boards (PCB) was build through an accurate characterization of samples of different origin, underwent mechanical comminution and representative sampling, by ICP-AES quantitative chemical analysis, to work as reference for researcher and companies interested in waste valorisation. The results identified RAM and mobile phone’s PCB as the “richest” classes of PCB, while TV PCB as the “poorest” in term of NM content. On these basis, a sustainable three-step NM recovery method, previously set-up on a finely shredded WEEE sample deprived by non-metallic and ferrous materials, was applied on a coarse sample of shredded RAM boards provided by companies, as a case study. Preliminary results highlighted that good NM recovery yields (from 65% to quantitative) and limited by-products formation could be achieved, despite a huge amount of composite materials was present in the mixture. Nevertheless, 10- times increased leaching times found for copper dissolution suggested that improved mechanical pretreatments might increase leaching effectiveness.