Recycling of valuable metals from poly cracker ash of printed circuit boards (PCBS) by physical beneficiation and hydrometallurgical treatment

Abstract

In the present paper, recovery of valuable metals from the poly-cracked ash obtained by pyrolysis of discarded PCBs has been studied following physical beneficiation and a hydrometallurgical process alternate to smelting. The ash is subjected to comminution for the separation of metallic components from non-metallic fractions by scrubbing, tabling and froth flotation which enriched the metal in the concentrate ~97% which was further screened to separate high and low metal concentrate. The finer fraction containing ~12% metallic value was leached in acidic solution. Almost all (Cu, Pb, Fe, etc) were leached in 4M HNO3 at 90◦C in 75 min at a pulp density 100 g/L. The characterization of both ash and residues were made by XRD, EPMA, EDS, etc. to validate the experimental results. The metals from the leach liquor could be recovered/separated using solvent extraction techniques which can further be processed to get pure metal salts/ sheets.