Screening of Non-cyanide Leaching Reagents for Gold Recovery from Waste Electric and Electronic Equipment

Birich, Alexander; Mohamed, Seifeldin Raslan; Friedrich, Bernd

doi:10.1007/s40831-018-0160-x

Cited by 32 publications

(26 citation statements)

References 14 publications

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“…Afterwards, Au must be oxidized to Au(III). Aqua regia (a 3:1 mixture of HCl(c) and HNO 3 (c)) is typically employed to dissolve Au, [18,21] and is usually used for glassware cleaning at laboratory scale. However, although this mixture's efficiency, the resultant Au(III) solution presents a high ionic strength, making it incompatible for its further use in AuNPs synthesis.…”

Section: Resultsmentioning

confidence: 99%

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Gold Recycling at Laboratory Scale: From Nanowaste to Nanospheres

et al. 2019

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The market for products based on nanotechnology increases day by day, and with it the use of nanomaterials and the generation of waste that contain nanowaste. Among the vast variety of nanomaterials available, gold nanoparticles (AuNPs) are within the most studied and applied ones in commercial products. This current situation requires both, the development of recovery methods to reduce the amount of produced nanowaste and new synthetic methods that allow the reuse of recovered gold for new nanomaterial production; in both cases keeping in mind economical and ecological reasons. In this work, a methodology to recover gold from aqueous laboratory nanowaste and to transform it into an aqueous HAuCl 4 solution was developed, using extremely simple procedures and easily available chemical reagents (NaCl, HCl, H 2 O 2), allowing the recovery of more than 99% of the original gold. The experiments were performed using both simulated and real laboratory nanowastes obtaining practically the same results. Moreover, the subsequent use of the obtained aqueous HAuCl 4 solution, from the recovered gold, to produce spherical AuNPs through a seed-mediated approach was demonstrated. Thus, this work presents, for the first time to the best of our knowledge, a complete recycling cycle from nanowaste, to the reagent and back to the nanomaterial.

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Section: Resultsmentioning

confidence: 99%

“…), respectively. [16][17][18][19][20][21][22][23] A mechanochemical approach has also been presented, that require the use of specific equipment. [24] Thus, these approaches are not adequate for the treatment of laboratory scale nanowastes, due to the toxicity of the involved materials and/or the complexity of the methodology.…”

Section: Introductionmentioning

confidence: 99%

Gold Recycling at Laboratory Scale: From Nanowaste to Nanospheres

et al. 2019

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“…Au leaching was performed using standard AR solution, a mixture of nitric and hydrochloric acid with 1:3 molar ratio. Knowing that an increase of temperature tends to give faster Au leaching rates, the test was performed at 60 • C, which is adopted as upper temperature level, above which decomposition reactions and evaporation of AR are intensified [22]. Au leaching kinetic was investigated by measuring the concentration of Au in solution, in intervals of 30 min for total of 180 min of leaching.…”

Section: Laboratory Testsmentioning

confidence: 99%

“…Also, gold surface passivation as well as insufficiently tested risks for human health additionally complicate their application. Consequently, in addition to promising results of extraction rate and yield for iodine leaching, favorable leaching kinetic and ability to effectively prevent any interfering effect caused by residual BM still make AR one of the main reagents for PM recovery [22].…”

Section: Introductionmentioning

confidence: 99%

Hydrometallurgical Process for Selective Metals Recovery from Waste-Printed Circuit Boards

Kamberović

Ranitović

Korać

et al. 2018

Metals

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This paper presents an experimentally-proved hydrometallurgical process for selective metals recovery from the waste-printed circuit boards (WPCBs) using a combination of conventional and time-saving methods: leaching, cementation, precipitation, reduction and electrowinning. According to the results obtained in the laboratory tests, 92.4% Cu, 98.5% Pb, 96.8% Ag and over 99% Au could be selectively leached and recovered using mineral acids: sulfuric, nitric and aqua regia. Problematic tin recovery was addressed with comprehensive theoretical and experimental work, so 55.4% of Sn could be recovered through the novel physical method, which consists of two-step phase separation. Based on the results, an integral hydrometallurgical route for selective base and precious metals recovery though consecutive steps, (i) Cu, (ii) Sn, (iii) Pb and Ag, and (iv) Au, was developed. The route was tested at scaled-up laboratory level, confirming feasibility of the process and efficiencies of metals recovery. According to the obtained results, the proposed hydrometallurgical route represents an innovative and promising method for selective metals recovery from WPCBs, particularly applicable in small scale hydrometallurgical environments, focused on medium and high grade WPCBs recycling.

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“…[ 1 , 2 , 3 ]. In this context, stimulated by world-wide regulations aiming for a more respectful approach towards the environment and natural resources, several classes of organic ligands have been investigated in the last three decades as potential alternatives to the harmful and polluting cyanides and aqua-regia lixiviants conventionally employed at industrial level for the hydrometallurgical reclamation of NMs [ 4 , 5 , 6 , 7 , 8 , 9 ]. Among them, thiourea and thiourea derivatives have long been recognized as versatile and effective complexing agents, finding application in a variety of fields.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Structural Insights of the Reaction Products by Direct Leaching of the Noble Metals Au, Pd and Cu with N,N′-Dimethyl-piperazine-2,3-dithione/I2 Mixtures

et al. 2021

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In the context of new efficient and safe leaching agents for noble metals, this paper describes the capability of the Me2pipdt/I2 mixture (where Me2pipdt = N,N′-dimethyl-piperazine-2,3-dithione) in organic solutions to quantitatively dissolve Au, Pd, and Cu metal powders in mild conditions (room temperature and pressure) and short times (within 1 h in the reported conditions). A focus on the structural insights of the obtained coordination compounds is shown, namely [AuI2(Me2pipdt)]I3 (1), [Pd(Me2pipdt)2]I2 (2a) and [Cu(Me2pipdt)2]I3 (3), where the metals are found, respectively, in 3+, 2+ and 1+ oxidation states, and of [Cu(Me2pipdt)2]BF4 (4) and [Cu(Me2dazdt)2]I3 (5) (Me2dazdt = N,N′-dimethyl-perhydrodizepine-2,3-dithione) compared with 3. Au(III) and Pd(II) (d8 configuration) form square–planar complexes, whereas Cu(I) (d10) forms tetrahedral complexes. Density functional theory calculations performed on the cationic species of 1–5 help to highlight the nature of the bonding in the different complexes. Finally, the valorization of the noble metals-rich leachates is assessed. Specifically, gold metal is quantitatively recovered from the solution besides the ligands, showing the potential of these systems to promote metal recycling processes.

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Screening of Non-cyanide Leaching Reagents for Gold Recovery from Waste Electric and Electronic Equipment

Cited by 32 publications

References 14 publications

Gold Recycling at Laboratory Scale: From Nanowaste to Nanospheres

Gold Recycling at Laboratory Scale: From Nanowaste to Nanospheres

Hydrometallurgical Process for Selective Metals Recovery from Waste-Printed Circuit Boards

Characterization and Structural Insights of the Reaction Products by Direct Leaching of the Noble Metals Au, Pd and Cu with N,N′-Dimethyl-piperazine-2,3-dithione/I2 Mixtures

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