Developed Commercial Processes to Recover Au, Ag, Pt, and Pd from E-waste

Abstract

Due to the supply gap towards increasing demand as well as loss of precious metals by illegal recycling, present research reports application-oriented processes developed at CSIR-NML, India to recover precious metals from small components of e-waste containing ~0.1–0.8% Ag, ~0.03–0.9% Au, ~0.01–0.02% Pd, ~0.0003–0.0005% Pt, and related effluent. Firstly, ~99.99% Au was recovered from plated e-waste using the process of selective leaching followed by charcoal adsorption and heat treatment, whereas the second process consists of dismantling, physical/ chemical pre-treatment of e-waste followed by hydrometallurgical processing to recover 99% Ag, 99.9% Au, 95% Pd, and 90% Pt. Apart from the above, leaching and selective precipitation were used to recover ~95% Ag from waste computer keyboards. The effluent generated during the e-waste processing was found to contain ~8–10 mg/L Au, which was also recovered using ion-exchange technique. All processes presented are scientifically validated and commercially viable after scale-up studies.