Separation and characterization studies of end-of-life mobile printed circuit boards

Abstract

Separation and characterization studies were carried out on end-of-life mobile printed circuit boards (EoL Mobile PCBs). The raw material has been subjected to a hammer mill to reduce the particle size. A series of comminution experiments were conducted to produce different size particles, which indicates that a number of crushing stages are needed to generate finer products. Comminution products consist of fine hydrophilic metals and hydrophobic nonmetal particles. Further, flotation studies were conducted to separate metals and nonmetals. The experimental results indicated that the product grade of 84-90% metals could be achieved from the feed containing 48% metals and recovery values varying between 44 and 66%. Characterization of the feed and flotation products was carried out following stereomicroscope and scanning electron microscope. The stereomicroscopic investigations show that the metallic particles were irregular in shape and the majority of them were liberated and few interlocks observed with the plastic/nonmetallic materials. The scanning electron microscope studies showed the presence of different metallic phases in the flotation products.