Printed circuit boards (PCBs) are a valuable source of raw materials for metal recycling considering that base metal concentration analyses have confirmed that PCB powders are multimetallic in nature and contain high concentrations of Cu, Zn, Ni, and Fe. Given that minerals are not renewable resources, these metals can be recycled through hydrometallurgical processes. In this study, we determined that 2 M sulfuric acid, 0.55 MPa oxygen pressure, and a temperature of 90 °C represent the optimal conditions for leaching of Cu, Zn, and Ni of PCBs, obtaining the highest observed values of recovery of greater than 90% for Zn and 98% for Cu and Ni. The characterization of PCBs by SEM–EDS analyses showed that plates mainly consist of Cu, Ni, and Zn. PCBs can be seen as a potential secondary resource for the recovery of copper, nickel, and zinc. The best potential and pH conditions for the extraction of Cu, Zn, and Ni were also determined on the basis of thermodynamic diagrams.
Bibliographical noteFunding Information:
The authors thank the Engineering Division, Chemical Engineering and Metallurgy Department, and the Geology Department of the University of Sonora, LANGEM, the National Laboratory of Geochemistry and Mineralogy in México, and CONACYT (National Council of Science and Technology) for the graduate scholarship of one author (G.M.-B.) and, Ing. Roberto Valenzuela Retroworks de México for their support of this study. The authors also thank Belem González Grijalva for analytical advice.
© 2023 by the authors.
- base metals
- pressure leaching
- printed circuit boards