Enrichment of Copper, Lead, and Tin by Mechanical Dry Processing of Obsolete Printed Circuit Board Residues

Waste printed circuit boards (WPCB) residues were mechanically processed to concentrate their metal content aiming to reduce costs of the subsequent recovery of copper, tin, and lead. A fully dry route was proposed to avoid the generation of liquid effluents that would require additional treatment. Firstly, 10.7% of the residue was segregated by magnetic separation; the remaining nonmagnetic fraction was comminuted and sieved. Ceramic and polymer materials (1/3 of the total weight) concentrated in the finer and the coarser size fractions, while metallic materials (2/3 of the total weight) concentrated in the intermediate size fraction (90.7, 94.5, and 95.6% of the total copper, tin, and lead contained in the milled WPCB, respectively). The fractions between 0.3-1.20 mm were submitted to gravity separation using a zig-zag air classifier; enrichment of copper (from 43±11% to 68±5%), tin (from 10±3% to 17±1%), and lead (from 4±1% to 6.4±0.5%) were obtained.