Processing of poly-cracked ash of printed circuit boards for recovery of valuable and rare metals

Abstract

In the present study, recovery of valuable and rare metals from the poly-cracked ash of printed circuit boards obtained from pyrolysis has been incorporated by following physical beneficiation and hydrometallurgical process. The ash is subjected to size reduction for the separation of metallic component from non-metallic fractions by tabling and froth flotation by which 95-97% of metal enrichment in the concentrate was obtained. Subsequently the enriched metal concentrate was subjected to selective metal extraction by hydrometallurgical treatment. Most of the metals (Cu, Pb, Fe, etc) were leached in HNO3 at elevated temperature and variable time interval using a pulp density of 100 g/L. The characterization of both poly-cracked ash and residues left after leaching were made by XRD, EPMA, EDS, etc. to validate the experimental results. The metals of interest from the leach liquor could be recovered/separated using solvent extraction technique which can further be processed to get pure metal salts/ sheets.