Selective selenium separation against arsenic coprecipitation and gradient recovery of minor metals from arsenic-selenium alloy waste

Minor metal-doped arsenic-selenium (As–Se) alloy has garnered widespread application across chalcogenide semiconductor materials owing to its distinctive optoelectronic properties, and its production and application generate a large amount of waste. Recycling these wastes through gradient separation delivers both economically and environmentally beneficial. However, the recovery of predominant Se would be accompanied by As precipitation, causing contamination. In this study, potential ( E )-pH diagram-guided gradient separation for efficient and selective recovery of Se, antimony (Sb) and germanium (Ge) from As–Se alloy waste has been proposed. Constructed E –pH diagram and half-wave potential equation display the existence of separation windows of sole production of elemental Se without As precipitation and the reduction potential of hydrazine hydrate locates at this region exactly, leading to selective reduction for Se production. Afterwards, the Sb, Ge and As can be gradually extracted through precipitation after hydrolysis precipitation, complexation-induced precipitation and sulfide precipitation. Under the optimized experimental conditions, the recovery efficiencies of Se, Sb, Ge, and As reach 98.9%, 98.7%, 99.9%, and 97.8%, respectively. After As removal treatment, the As concentration in the solution is below 0.2 mg/L, meeting the As-containing wastewater discharge standard (≤0.5 mg/L), realizing effective resource recycling and centralized disposal of hazardous substances.