Sustainable Recovery of Critical and High-Value Metals from Electronic Waste: Technologies, Process Intensification, Environmental Impacts, and Circular Economy Perspectives

Abstract

More people using electronics means ever-rising piles of old devices tossed away, piling up faster than almost any other kind of trash. These discarded gadgets aren’t just junk - they hold valuable materials like gold, copper, lithium, and rare earths, sometimes richer than what's dug from the ground. Urban areas now act like mines, where used circuit boards and dead batteries offer more concentrated metals than raw ore in certain cases. Still, pulling those metals out is tough because the mix inside e-waste varies wildly, while toxic stuff like flame retardants and lead lurks alongside useful parts. Smelting and chemical leaching methods work well at large factories, recovering plenty of metals yet guzzling fuel, creating pollution, and needing tons of chemicals. Newer ideas, like using microbes or eco-friendly liquids to extract metals, perform gently on nature and pick targets better, though slow reactions and shaky performance stop them from going mainstream so far. New progress in Solv metallurgy, together with ionic liquids and deep eutectic solvents, opens different paths to better separate metals while cutting harm to nature. When it comes to climate impact, pulling metals from old electronics creates far fewer emissions than digging new ore - this holds especially true for rare earths and valuable metals. Still, weak collection systems, scattered informal recycling, uneven rules across regions, and shifting market prices keep slowing down full reuse of electronic waste.