Optimization of process parameters for the selective leaching of copper, nickel and isolation of gold from obsolete mobile phone PCBs

The sequential separation of base and precious metals from the end-of-life mobile phone printed circuit boards (PCBs) is a significant challenge for development recycling process that exhibit material circularity. In this contribution, simple, eco-friendly, efficient leaching developed dissolution copper nickel obsolete PCBs to facilitate isolation gold-rich residue. Chemical pre-treatment downsized produced metallic portion which parameters were optimised, including type reagent, temperature, time, pulp density agitation speed. It was found quantitative occurred using 3.0 M nitric acid at 30 °C with 50 g/L density, 2 h residence 500 rpm stirring speed; under these conditions, no gold dissolved. Design Experiment analysis Response Surface Methodology also undertaken validate process. Finally, kinetics studied shown conform chemically controlled surface reaction model, activation energies 39.7 18.4 kJ/mol nickel. Importantly, optimised in work avoids need high temperatures reduces energy consumption effluent generation, leading cleaner processing dominant metals.