Physical and thermal processing of Waste Printed Circuit Boards aiming for the recovery of gold and copper

Ventura, Emily E.; Silva, Aurora Futuro; Pinho, Sílvia C.; Almeida, Manuel Fonseca; Dias, Joana Maia

doi:10.1016/j.jenvman.2018.06.019

Cited by 31 publications

(13 citation statements)

References 32 publications

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“…Physical processing is as an alternative method for the recovery of valuable metals from the end of life PCBs. It includes size separation, density separation [17][18][19], magnetic separation [16], dry-wet fluidization, gravity separation [17,20,21], pneumatic separation [22,23], electrostatic separation, and eddy current separation [24].…”

Section: Introductionmentioning

confidence: 99%

Processing of Discarded Printed Circuit Board Fines via Flotation

Barnwal

Mir

Dhawan

2020

J. Sustain. Metall.

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The recovery of metals from discarded printed circuit boards using environmentally-friendly physical routes is gaining importance. Physical separation of metal values from non-metallic constituents exploits various characteristics of crushed powder such as density, liberation, shape, size, and wettability. However, the generation of fines during grinding/crushing of the printed circuit boards is an unavoidable but essential by-product. The fine fractions are discarded due to the higher amounts of non-metallic fraction and poor separation of metallic values. In this study, the flotation process was studied to separate metallic and non-metallic values without the addition of external additives from the fine fraction of printed circuit boards (< 212 µm). The natural hydrophobic response of plastic and organic matter in fines stabilized the froth without additional reagents. The difference in tapped density for tailing (~ 0.5 g/cm 3 ) and concentrate (~ 2.7 g/cm 3 ) fraction ensures good separation. The metallic fraction increases from 14.3% in the feed to 91.7% in the concentrate. Recovery for metallic values was observed as ~ 72.3% with a purity of ~ 92% and comprised 77.9% Cu, 8.3% Sn, and 5.5% Pb.The contributing editor for this article was Veena Sahajwalla.

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Section: Introductionmentioning

confidence: 99%

Processing of Discarded Printed Circuit Board Fines via Flotation

Barnwal

Mir

Dhawan

2020

J. Sustain. Metall.

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“…The economic value of EEEs concentrates in the printed circuit boards (PCB), which contain a variety of valuable metals as well as hazardous materials . Especially, the gold recovery from the used PCBs from the electronic industry has received the most attention because of the presence of a considerable quantity of this metal, which is generally 100 times higher in concentration than that of the gold ore …”

Section: Introductionmentioning

confidence: 99%

“…The economic value of EEEs concentrates in the printed circuit boards (PCB), which contain a variety of valuable metals as well as hazardous materials. 1-3 Especially, the gold recovery from the used PCBs from the electronic industry has received the most attention because of the presence of a considerable quantity of this metal, which is generally 100 times higher in concentration than that of the gold ore. 2,[4][5][6][7][8][9] The existing processes of recycling PCBs are either pyrometallurgical, hydrometallurgical, or extraction and refining to recover the metals by pyro−/hydrometallurgical after upgrading the metal content by mechanical pretreatment, which generate atmospheric pollution through the…”

mentioning

confidence: 99%

“…[14][15][16][17] A PCB assembly is a PCB mounted with electronic components (ECs), connected by solder. 9,[18][19][20][21] Gold is generally plated on PCB contacts to increase the hardness of the contact and to take advantage of its good conductivity to minimize contact resistance of the circuit. [22][23][24] The main part of the contact is nickel and copper foil.…”

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confidence: 99%

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Alkaline electrochemical leaching of Sn and Pb from the surface of waste printed circuit board and the stripping of gold by methanesulfonic acid

Zhang

Chenglong

Zheng

et al. 2019

Env Prog and Sustain Energy

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The variety of metals and organic in the waste printed circuit board (PCB) that makes them harmful to environment but also contain high economic value. The precious metals of gold on the surface of waste PCB has a high recovery value. In this article, a cleaner hydrometallurgical process for production of Sn, Pb, and Au from the surface of waste PCB was developed. With the alkaline electrochemical leaching, 100% of Sn and Pb in the solder can be extracted at NaOH concentration of 3 mol/L, current density of 300A/m2, and temperature over 8°C after electrochemical leaching of 120 min, and the components can be removed simultaneously. With the technique of methane sulfonic acid etching, the copper and nickel undered the gold plate were leached and then the gold foil can be collected. The optimum conditions of methane sulfonic acid etching technique was explored: under the room temperature, with the solid‐liquid ratio of 1:5, the amount of the hydrogen peroxide is 20%, and the volume fraction of methane sulfonic acid is 15%, the soaking time of the phone board is 150 min (the coating flaking time varied slightly due to the type difference of plates), the recovering rate of gold may be up to 95%. In addition, the method has a good selectivity for element Au, the stripped gold can be melted directly, while the treated waste PCB can be used for other metal or nonmetal recovering, the solution can also be recycled after recovering copper and nickel.

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“…As a consequence, intensive researches were dedicated to the DPCMBs recycling, being proposed various processes, e.g. physico-mechanical [7,9], hydrometallurgical [6,10,11], pyrometallurgical [12,13], pyrolytic [14] biometallurgical [15] or combination of thereof as presented in research papers [9,16] or exhaustive reviews [17][18][19]. In spite of the intense efforts, confirmed by the high number of published papers [20] and patents [21], the great majority of the proposed technologies presents serious disadvantages, e.g.…”

Section: Introductionmentioning

confidence: 99%

"Influence of the composition evolution of waste computer motherboards on their recycling strategy "

Dorneanu¹,

Avram²,

Mărincaş³

et al. 2018

Studia UBB Chemia

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Even if the mobile devices gain more popularity comparing to the desktop personal computers (DPCs), the last ones are still intensively used where highly computing or storage capabilities are required. Because the replacing rate of DPCs are very high, the amount of obsolete equipments is also huge, reclaiming adequate efficient and ecological recycling techniques. In this field, the main efforts are focused on the DPCs motherboards (DPCMBs) recycling because, even if they represent only 5 to 10% from the DPCs weight, they concentrate up to 80% from the recoverable value. By accounting the DPCMBs' traditional and incipient recycling technologies, it is obvious that none of them can solve alone the problem of this waste type. In this context, during the present work, the composition evolution of 10 DPCMBs released between 1998 and 2008 was evaluated and analyzed, the obtained results being used to design a feasible and eco-friendly combined strategy for integral DPCMBs recycling.

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Physical and thermal processing of Waste Printed Circuit Boards aiming for the recovery of gold and copper

Cited by 31 publications

References 32 publications

Processing of Discarded Printed Circuit Board Fines via Flotation

Processing of Discarded Printed Circuit Board Fines via Flotation

Alkaline electrochemical leaching of Sn and Pb from the surface of waste printed circuit board and the stripping of gold by methanesulfonic acid

"Influence of the composition evolution of waste computer motherboards on their recycling strategy "

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