Printed circuit board recycling: physicochemical and economic analysis of metals

Abstract

This study aims to present the characterization of five different types of printed circuit boards (PCBs) for use in future recycling processes. PCBs used: motherboards, lead free motherboards, video cards, memory and printer cards. The comminution of the circuit boards was performed using blade mills and hammer mills with 9mm and 6mm meshes, respectively. Throughout the physical processing, analysis was made with stereoscopic optics to ensure that the correct materials had been released. The pre-magnetic separation parts were given a granulometric classification followed by acid digestion and loss on ignition tests. The composition of the PCBs studied varied from one board to another, with the metallic fraction being the main constituent of lead free motherboards, video cards and printer PCBs, while the motherboard and memory cards contain a greater volume of polymeric and ceramic material constituents respectively. Three samples showed similar behavior in granulometric distribution with a tendency of material accumulation in the sieves with wider meshes and, in two of them the highest percentage of material was retained by those with smaller screens. Cu was the metal found in the greatest concentration. Silver, gold and copper were the metals with the highest value percentages.