Urban mining by flash Joule heating

• Published in: Nature communications Vol. 12; no. 1; p. 5794
• Main Authors: Deng, Bing, Luong, Duy Xuan, Wang, Zhe, Kittrell, Carter, McHugh, Emily A., Tour, James M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.10.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 01 COAL, LIGNITE, AND PEAT; 140/133; 140/146; 147/135; 147/143; 639/301/299/891; 639/638/169/896; Agricultural wastes; batteries; Cadmium; Chromium; Electronic waste; Environmental impact; flash Joule heating; Furnaces; Gold; Heavy metals; High temperature; Humanities and Social Sciences; Leaching; Lead; Materials recovery; Mercury (metal); Metallurgy; Metals; Mine wastes; multidisciplinary; Noble metals; Ohmic dissipation; Palladium; pollution remediation; Resistance heating; Science; Science (multidisciplinary); Silver; Smelting; Smelting furnaces; Solvents; Urban agriculture; urban mining; Wastes
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26038-9

Precious metal recovery from electronic waste, termed urban mining, is important for a circular economy. Present methods for urban mining, mainly smelting and leaching, suffer from lengthy purification processes and negative environmental impacts. Here, a solvent-free and sustainable process by flash Joule heating is disclosed to recover precious metals and remove hazardous heavy metals in electronic waste within one second. The sample temperature ramps to ~3400 K in milliseconds by the ultrafast electrical thermal process. Such a high temperature enables the evaporative separation of precious metals from the supporting matrices, with the recovery yields >80% for Rh, Pd, Ag, and >60% for Au. The heavy metals in electronic waste, some of which are highly toxic including Cr, As, Cd, Hg, and Pb, are also removed, leaving a final waste with minimal metal content, acceptable even for agriculture soil levels. Urban mining by flash Joule heating would be 80× to 500× less energy consumptive than using traditional smelting furnaces for metal-component recovery and more environmentally friendly. Precious metals recovery from electronics wastes, termed urban mining, is significant for a circular economy. Here, the authors reported a solvent-free and ultrafast process based on flash Joule heating to recover precious metals and remove toxic heavy metals in electronic wastes.