Challenges and opportunities in the recovery of gold from electronic waste

Abstract

Rapid global technological development has led to the rising production of electronic waste that presents both challenges and opportunities in its recycling. In this review, we highlight the value of metal resources in the printed circuit boards (PCBs) commonly found in end-of-life electronics, the differences between primary (ore) mining applications and secondary ('urban') mining, and the variety of metallurgical separations, in particular those that have the potential to selectively and sustainably recover gold from waste PCBs.

Fig. 1. Overview of stages involved in metal recycling from electronic waste.

Fig. 2. Main stages in a hydrometallurgical process to recover metals from waste electronics.

Fig. 3. Leaching of gold from e-waste using N-bromosuccinimide/pyridine mixtures.

Fig. 4. Selective precipitation of gold as a KAuBr₄/α-cyclodextrin assembly.

Fig. 5. Metal organic frameworks, with catalytically active metal sites that bind and polymerise monomers within the pores, forming short redox-active polymer chains that bind and reduce gold.

Fig. 6. Metal-templated formation of MOFs with thioether-decorated pores for gold adsorption.

Fig. 7. Amide reagents exploited for the recovery of gold by solvent extraction.

Fig. 8. Transport of Au from an aqueous leach solution into and aqueous strip solution with selectivity provided by the extractant-embedded polymer inclusion membrane (PIM).

Fig. 9. Schematic diagram of a flow-through electrogenerative reactor (modified from ref. 94).