Integrated recovery of copper and gold from end-of-life LEDs using two-step leaching process with volatile fatty acids

Abstract

The rising demand for precious metals in clean energy technologies, coupled with their natural scarcity, has prompted the exploration of innovative processes targeting unconventional metal sources such as end-of-life electronic devices. Hydrometallurgical techniques hold promise, but environmental concerns persist, particularly concerning environmentally friendly solvent usage. This study investigates a hydrometallurgical approach, employing a two-step leaching process with mimic organic waste-derived volatile fatty acids (VFAs) for copper (Cu) extraction following gold (Au) recovery using thiourea (TU) solution from end-of-life light-emitting diodes (LEDs). Preliminary investigations with Cu powder using various organic and inorganic ligands revealed that acetic acid (AA) with hydrogen peroxide (H2O2) as an oxidant surpassed inorganic ligands at pH 4. The subsequent application of AA for Cu recovery from end-of-life LEDs resulted in a 75.36 % Cu leaching efficiency at pH 4, emphasizing VFAs’ potential in recovering Cu elements from heterogeneous electronic waste. The solid residues from AA-treated LEDs were then dissolved in a TU solution with H2O2. yielding a substantial improvement in Au recovery efficiency—94.42 % within an hour, compared to 19.47 % via direct leaching. This study demonstrates VFAs as a sustainable alternative to traditional solvents for Cu leaching, followed by Au recovery in a two-step leaching process. This approach supports a circular economy in electronic waste management by integrating biogenic waste streams for metal recovery. © 2024 Elsevier Ltd