Application of corona discharge and electrostatic force to separate metals and nonmetals from crushed particles of waste printed circuit boards

Printed circuit board (PCB) scrap has a metal content of nearly 28%, including an abundance of nonferrous metals such as copper, lead, and tin. The purity of precious metals in PCBs is more than 10 times that of content-rich minerals. Therefore, the recycling of PCBs is an important subject, not only from the viewpoint of waste treatment, but also with respect to the recovery of valuable materials. A new process was investigated which involved mechanical crushing, screening, drying and electrostatic separation via corona discharge. The results show that (1) a two-step crushing process could completely strip metals from base plates; (2) the effect of aggregation opposed the production on fine powders; (3) particle sizes between 0.6 and 1.2 mm are most feasible for separation in industrial application; (4) Corona electrostatic separation is an efficient and environmental means for recovering metals from PCBs.