Challenges and opportunities in the recovery of gold from electronic waste

Rao, Mudila Dhanunjaya; Singh, K. K.; Morrison, Carole A.; Love, Jason B.

doi:10.1039/c9ra07607g

Cited by 197 publications

(114 citation statements)

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“…The HNO 3 favors the formation of trivalent gold ions, which further react with chloride to form tetrachloroaurate anions, according to Eq. (12) [21,43]. The aqua regia leaching is mostly used for alloys with high gold content [36].…”

Section: Aqua Regia Leachingmentioning

confidence: 99%

Hydrometallurgical Recovery of Gold from Mining Wastes

Neag¹,

Kovács²,

Dinca³

et al. 2021

Strategies of Sustainable Solid Waste Management

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Gold is a highly required material for a wide range of personal and industrial applications. The high demand for gold, together with the shortage of natural resources and high pollution potential of wastes generated during mining and ore processing activities led to search for alternative sources of gold. A possible source is represented by mine wastes resulting from the processing of polymetallic or sulfidic ores. The reprocessing of wastes and old tailings with moderate to low content of gold offers not only a business opportunity, but also enhances the quality of the surrounding environment, changes the land use and offers a wide range of socio-economic benefits. Cyanidation, the most widespread Au leaching option, is progressively abandoned due to the high risk associated with its use and to the low public acceptance. Therefore, alternative methods such as thiocyanate, thiourea, thiosulphate and halide leaching gained more and more interest. This chapter presents the most important features of some Au leaching methods, emphasizing their advantages, limitations and potential applications.

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Section: Aqua Regia Leachingmentioning

confidence: 99%

Hydrometallurgical Recovery of Gold from Mining Wastes

Neag¹,

Kovács²,

Dinca³

et al. 2021

Strategies of Sustainable Solid Waste Management

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“…Not only is gold a common precious metal in jewels and coins, it is also employed increasingly within modern industries such as telecommunications, nanotechnology, chemical synthesis, and medicine. As a result, world demand for gold continues to increase which raises interest in developing new methods of extracting it from the earth or recovering it from societal waste streams [1, 2] . In addition, there is a growing need for advanced materials that are comprised of gold‐containing nanocomposites with nanoscale architecture [3, 4] .…”

Section: Introductionmentioning

confidence: 99%

Supramolecular Paradigm for Capture and Co‐Precipitation of Gold(III) Coordination Complexes

Shaffer

Liu

Oliver

et al. 2020

Chemistry A European J

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A new supramolecular paradigm is presented for reliable capture and co‐precipitation of haloauric acids (HAuX4) from organic solvents or water. Two classes of acyclic organic compounds act as complementary receptors (tectons) by forming two sets of directional non‐covalent interactions, (a) hydrogen bonding between amide (or amidinium) NH residues and the electronegative X ligands on the AuX4−, and (b) electrostatic stacking of the electron deficient Au center against the face of an aromatic surface. X‐ray diffraction analysis of four co‐crystal structures reveals the additional common feature of proton bridged carbonyls as a new and predictable supramolecular design element that creates one‐dimensional polymers linked by very short hydrogen bonds (CO⋅⋅⋅OC distance <2.5 Å). Two other co‐crystal structures show that the amidinium‐π⋅⋅⋅XAu interaction will reliably engage AuX4− with high directionality. These acyclic compounds are very attractive as co‐precipitation agents within new “green” gold recovery processes. They also have high potential as tectons for controlled self‐assembly or co‐crystal engineering of haloaurate composites. More generally, the supramolecular paradigm will facilitate the design of next‐generation receptors or tectons with high affinity for precious metal square planar coordination complexes for use in advanced materials, nanotechnology, or medicine.

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“…Approximately 40% of the world's tantalum production is used in this application, but its recycling is limited, at only 1% [1]. This is surprising, as electronic waste (e-waste) is becoming one of the fastest growing waste categories worldwide [2,3]. Furthermore, it was found that metal recovery from secondary resources is gradually becoming more cost-effective than virgin mining, especially as the volume of e-waste is projected to increase substantially; over the next few decades, new technologies will become cheaper and more accessible, driving up the rate of device obsolescence [4,5].…”

Section: Introductionmentioning

confidence: 99%

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

Kinsman

Crevecoeur

Singh-Morgan

et al. 2020

Metals

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The recycling of tantalum (Ta) is becoming increasingly important due to the criticality of its supply from a conflict mineral. It is used extensively in modern electronics, such as in capacitors, and so electronic waste is a potentially valuable secondary source of this metal. However, the recycling of Ta is difficult, not least because of the challenges of its leaching and subsequent separation from other metals. In this work, we show that Ta(V) halides, such as TaCl5 and TaF5, which can potentially be accessed from Ta metal upon acid halide leaching, can be recovered by solvent extraction using a simple primary amide reagent. The need for high halide concentrations in the aqueous phase implies the formation of the hexahalide salts [TaX6]− (X = F, Cl) and that an anion-swing mechanism operates. While extraction of the fluorides is poor (up to 45%), excellent extraction under chloride conditions is found (>99%) and presents an alternative route to Ta recycling.

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Challenges and opportunities in the recovery of gold from electronic waste

Abstract: Rapid global technological development has led to the rising production of electronic waste that presents both challenges and opportunities in its recycling.

Cited by 197 publications

References 100 publications

Hydrometallurgical Recovery of Gold from Mining Wastes

Hydrometallurgical Recovery of Gold from Mining Wastes

Supramolecular Paradigm for Capture and Co‐Precipitation of Gold(III) Coordination Complexes

Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

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