Recycling of gold from waste electronic devices
Tremendous generation of e-waste and its illegal recycling are causing immense threat to environment as well as the loss of precious metals.
The present research reports a novel hybrid process for the total recovery of gold from small depopulated components of e-waste.
Connectors and integrated circuits (ICs) liberated from printed circuit boards (PCBs) were pulverized and processed for gold leaching using 10 g/L sodium cyanide solution at 40 °C and mixing time 15 min, where more than 95% gold was found to be leached out in single stage. From the obtained leach liquor, gold metal was recovered by charcoal adsorption followed by heat treatment. The raffinate left after adsorption of gold was found to contain ~10 mg/L gold, which was also recovered using Amberlite IRA 400Cl at equilibrium pH 9.6 in 30 min maintaining aqueous/resin (A/R) ratio 25 mL/g.The raffinate solution was enriched to 882.41 mg/L and the solution was further processed to get metal/salt using cementation / evaporation.Obtained leached residue is processed for non-ferrous metals recovery and finally disposed-off after treatment and TCLP test.The effluent left after leaching could be easily decomposed and treated in ETP using standard environmental procedure.