Sustainable Process to Recover Metals from Waste PCBs Using Physical Pre-Treatment and Hydrometallurgical Techniques

Printed Circuit Boards (PCBs) are an essential component of electronic devices. The digitalization and upgrading of gadgets generates a significant amount of PCB-containing electronic waste, necessitating efficient recycling methods to conserve resources and protect the environment. This paper presents a sustainable process for the recovery of metals from waste PCBs utilizing physical pre-treatment and hydrometallurgical techniques. The initial phase involved pre-treating and beneficiating the waste PCBs to separate the metallic and non-metallic fractions. The resulting metallic concentrate underwent leaching with nitric acid, a strong oxidative agent, in a fully jacketed system equipped with a scrubber and condenser to mitigate toxic gas emissions. Various process parameters such as acid concentration, pulp density, temperature, and time were systematically studied, optimized, and validated. Kinetic analysis of the leaching process revealed that it fitted well with shrinking core models for copper, nickel, and lead, with an activation energy of 19.42 kJ/mol. Moreover, the residual tin was treated separately. This developed process effectively recovers metals from waste PCBs, contributing to sustainable e-waste management.