Pre-treatment of Printed Circuit Boards using eco-environmentally friendly techniques to concentrate metals prior their hydrometallurgical recovery and purification.

Printed circuit boards (PCBs) from dismantled WEEE contain various materials such as polymers, ceramics, wood, and metals. Metal recovery is the main objective of effective and appropriate recycling of PCB waste. In addition to precious metals (Ag, Au, Pd, etc.), this waste contains other valuable metals (Cu, Sn, Fe, Al, etc.). A crucial step in the recovery process is the concentration of metal particles. This study aims to determine an effective process for enriching metal particles, using simple methods suitable for developing countries, in order to recover metals, particularly precious metals, contained in PCBs. Two types of crushed PCBs, from RAM memory and mobile phone waste, were studied. Two concentration methods were used: a magnetic separation method using a neodymium magnet and a gravimetric separation method using a vibrating table. The results showed that magnetic separation, although not very effective, reduced the amount of magnetic metals. Gravimetric separation showed that the [0.355-0.09] mm particle size was more suitable for separation by vibrating table than the other particle sizes tested in this study (< 0.09 mm, [0.71-0.355] mm, and [1.5-0.71] mm). The precious metal yields for this particle size range between 73% and 87%.