Application-driven recovery of precious metals from anthropogenic reservoirs: Extraction capacity, process selectivity, and circular economy pathways

Precious metals—gold (Au), silver (Ag), palladium (Pd), and platinum (Pt)—are indispensable enablers of modern electronic, catalytic, and energy technologies, yet their supply is increasingly constrained by geological scarcity, geopolitical concentration, and escalating environmental costs of primary mining. This manuscript presents a rigorous, application-centric assessment of precious metal recovery from anthropogenic reservoirs, identifying electronic waste, spent catalytic systems, and energy-related devices as the dominant secondary resource bases. Comparative analysis reveals that these urban ores exhibit metal grades exceeding those of primary geological deposits by one to three orders of magnitude, thereby offering exceptional extractable capacity when coupled with appropriate processing strategies. The study critically evaluates conventional and emerging extraction paradigms, emphasizing the transition toward green hydrometallurgical routes—including deep eutectic solvents, organic acids, bio-assisted processes, and electrochemical separation—that prioritize selectivity, reagent minimization, and environmental compatibility. Particular attention is devoted to co-leaching phenomena, copper interference, and chloride–sulfur chemistry, which collectively define the principal selectivity bottlenecks in precious metal recovery. Integrated hybrid process flowsheets are advanced as the most viable solution for translating extreme urban ore enrichment into high-purity metal products. Framed within circular economy principles, the analysis underscores the strategic role of urban mining in enhancing resource security, reducing supply-chain vulnerability, and decoupling technological growth from primary resource depletion.