Recent advances on hydrometallurgical recovery of critical and precious elements from end of life electronic wastes - a review

Waste electrical and electronic equipment (WEEE) constitutes a rapidly growing waste stream containing substantial quantities of critical raw materials (CRMs), precious metals, and rare earth elements (REEs). In view of the depletion of high-grade primary ores and the limitations of conventional pyrometallurgical processing, this review examines recent advances (2015–2018) in hydrometallurgical strategies for metal recovery from end-of-life electronic products. Drawing on more than 150 publications, the article surveys the types, origins, and elemental compositions of key WEEE fractions, including printed circuit boards, liquid crystal displays, cathode ray tubes, fluorescent lamps, hard disk drives, light-emitting diodes, and spent batteries. Particular emphasis is placed on leaching processes employing diverse lixiviants and on subsequent selective recovery of CRMs, precious metals, and REEs through ionic liquids, solvent extraction, electrowinning, adsorption, and precipitation. The review critically compares these methods in terms of selectivity, efficiency, environmental impact, and applicability to heterogeneous, low-volume waste streams that escape traditional smelting routes. It further discusses techno-economic aspects and the potential of WEEE to serve as a sustainable secondary resource base for strategic elements such as indium, yttrium, europium, and gold. Overall, the review highlights hydrometallurgy as a promising, more flexible and potentially cost-effective alternative for the recovery of critical and precious elements from electronic waste, while identifying research gaps and future directions for process optimization and commercial implementation.