Investigation of the melting conditions for recovery of precious metals from printed circuit boards

One of the most important problems of technological developments in today?s world is electric and electronic waste (E-waste). The e-wastes contain certain heavy metals, plastics and flame retardants etc., threats to health and environment. Due to precious metal contents, e-wastes especially PCB?s, has an economic value. Therefore, the recycling of PCBs is an important subject, not only from the hazardous effects, but also with respect to the recovery of valuable materials. The recovery and recycling processes of e-wastes mainly are classified into pyrometallurgical, hydrometallurgical and electrometallurgical processes. In the pyrometallurgical process, e-wastes are melted with several metal concentrates and flux components as slag formatives at high temperature. As a result of melting process, valuable metals are accumulated in metallic phase and then the extracted valuable metals are separated and purified with other processes.In this study, the effect of collector metal and composition and quantity of fluxes, for the recovery of precious metals from PCB?s in discarded computers are examined using with pyrometallurgical method. The waste PCB?s were manually dismantled and cut to a size of 2,5cm-2,5cm, incinerated at 850-950°C. In each experiment, residues contain precious metals were melted adding different types of fluxes and with/without copper as a collector metal at 1250-1350°C.According to the experimental results, the amount of input 95% of the precious metals could be collected in metallic phase. In melting process high recovering ratios have been e in %20 and %30 flux level, in the presence of collector metal; %20-%30 copper level, 10% B2O3, 15% Al2O3, 30% SiO2, 30% CaO, 10% Fe2O3, 5% CaF2 flux composition, in the absence of collector metal; 43% B2O3, 6% Al2O3, 18% SiO2, 12% CaO, 18% Fe2O3, 5% CaF2 flux compositions, have been determined most appropriate conditions for recovering of precious metals.