Cu and Ag Separation in Alkahest-Enabled Electrochemical Processing of Sulfide Minerals

The chemical inertness of sulfide ores presents a major challenge for the direct extraction and separation of mineral feedstocks into high-purity metals. Conventional processing therefore relies on high-temperature pyrometallurgy or cyanide-based hydrometallurgy following indirect oxidative pretreatment. Here, we report an alkahest-enabled strategy for direct electrochemical extraction of Cu and Ag from chalcocite (Cu2S) and acanthite (Ag2S) under mild, room-temperature, and acid-free conditions using 2-mercaptoethanol (merc) and ethylenediamine (en). Dissolution in the thiol-amine solvent system generates electrochemically active Cu- and Ag-containing species that can be directly transformed into high-purity metallic films through electrowinning. Cu electrowinning exhibits a Faradaic efficiency of 84% with an electrical energy consumption of 0.41 kWh/kg, while Ag recovery achieves a Faradaic efficiency of 87% with an electrical energy consumption of 0.14 kWh/kg. Beyond individual sulfide systems, water-mediated phase selectivity enables separation of Cu–Ag–S mixtures, yielding isolated Cu and Ag solutions for selective recovery with final metal purities of 99.4% and 99.0%, respectively. These findings establish alkahest-mediated chemistry as a promising framework for direct sulfide-to-metal transformations and selective conversion of multicomponent sulfide minerals into high-purity metals.