Abstract
Printed circuit boards (PCBs) are difficult to recycle because of the layered structure of non-metal (i.e., epoxy resin, glass fiber) and copper. In this work, we conducted a systematic investigation to effectively recover copper from PCB. A thermal treatment was employed for improving the crushing performance of PCB and conducted by varying the temperature and the gas. Then, the mechanical strength, degree of liberation (DL), and copper separation efficiency of the heat-treated and untreated PCBs were investigated. After heat treatment under a 300 °C air atmosphere, the mechanical strength of PCB decreased from 386.36 to 24.26 MPa, and copper liberation improved from 9.3% to 100% in the size range of a coarser size fraction (>1400 μm). Accordingly, when electrostatic separations were performed under these conditions, a high-Cu-grade concentrate and high recovery could be obtained. The results show that the change in the physical properties of the PCBs leads to an improvement in the DL following thermal decomposition at 300 °C in air. Our study elucidates the physical properties of PCBs and the DL under various heat treatment conditions. Furthermore, it shows that the heat treatment condition of 300 °C in air is ideal for recovering copper from the PCB.
Highlights
We investigated the changes in the properties of Printed circuit boards (PCBs), degree of liberation (DL), and separation efficiency, which depended upon the thermal treatment
The heat treatment of PCB was conducted at temperatures ranging from 200 to 325 ◦ C under N2 and air atmospheres
For PCB undergoing thermal treatment, delamination at 300 ◦ C caused an increase in thickness
Summary
The quantity of electronic waste (e-waste) generated has increased with the growing use of electronic devices, increasing by approximately 4–5% every year [1]. At least 53.6 million tons of e-waste was produced in 2019 [2]. Most e-waste has a vital module—the printed circuit board assembly (PCBA)—which is designed to exchange electronic signals between the parts of an electronic device. An increase in e-waste naturally leads to an increase in waste PCBA
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