ABSTRACT
105Electronic waste (e-waste) is a recent environmental problem worldwide, because it is bulky in size causing solid waste disposal problems, especially due to the release of toxic heavy metals into the environment. On the other hand, metal scarcity is another global issue with e-waste, making it a prominent candidate for metal recovery. In this study, desktop computer printed circuit boards (PCBs) were evaluated as a potential source of Cu, Ni and Zn recovery using a hydrometallurgical method. The process parameters for metal leaching i.e. different particle sizes (< 0.5, 0.5–1.0, 1.0–5.0 and 5.0–9.5 mm), leaching agents (HNO3, H2SO4 and C2H5ONa), contact time (18 h), liquid to solid (L/S) ratio (10, 20 and 40), and agitation speed (0, 100 and 200) were evaluated in batch systems. At the following optimal conditions of 1M HNO3, L/S ratio of 20 with 200 rpm agitation speed using 0.5 – 1.0 mm particle size, the concentrations of Cu, Ni and Zn leached out from the PCBs were 450, 8 and 4 mg/g PCBs, respectively. Continuous leaching in an up-flow leaching column using the optimized parameters, coupled to sulfide precipitation yielded > 90% Cu recovery (0.48 g/g PCBs).
