New technology for recovering residual metals from nonmetallic fractions of waste printed circuit boards

Zhang, Guangwen; He, Yaqun; Wang, Haifeng; Zhang, Tao; Wang, Shuai; Yang, Xing; Xia, Wencheng

doi:10.1016/j.wasman.2017.03.030

Cited by 38 publications

(9 citation statements)

References 27 publications

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“…The ratio of the upper size limit and the lower size limit was maintained at 2:1 that would decrease the effect of the particle size on the separation process. [ 38 ] The screened size fractions were subjected to the ASTM standard float‐sink test (D4371). Organic liquids with different specific gravities (1.4, 1.6, 1.8, 2.0, 2.2, and 2.4) were prepared by mixing tetra bromoethane (SG 2.95) and kerosene (SG 0.8).…”

Section: Methodsmentioning

confidence: 99%

Assessing the Applicability of Gravity Separation for Recycling of Non‐Metal Fraction from Waste Printed Circuit Boards

Kumar¹,

Holuszko²,

Janke³

2020

Advanced Sustainable Systems

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Printed circuit boards (PCB) are one of the most studied electronic waste streams due to the presence of high‐value metals. The rejects from waste PCB recycling, also known as a non‐metal fraction (NMF), are usually sent to landfill. This work explores the applicability of gravity separation, widely used in the mineral processing industry, to separate organic and inorganic components in the NMF. The float‐sink test is conducted to understand the gravity separation performance, and the results show that a 47% yield at 86% organic content with 70% combustible recovery can be obtained using dense media separation. The washability behavior of NMF is assessed using different washability indices standard in the coal industry; and the material is classified as difficult‐to‐clean. The float‐sink products show the concentration of organic stream in −1.8 g cm−3 range, fiberglass in +2.0–2.5 g cm−3 range, and metals in +2.5 g cm−3 range. The recovery of these components will facilitate the concept of the circular economy and promote sustainability.

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Section: Methodsmentioning

confidence: 99%

Assessing the Applicability of Gravity Separation for Recycling of Non‐Metal Fraction from Waste Printed Circuit Boards

Kumar¹,

Holuszko²,

Janke³

2020

Advanced Sustainable Systems

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“…27−29 Without the acid leaching, heavy metals still exist in the char, which cannot be directly disposed of by landfilling. 16 Shen et al 30 summarized the dehalogenation of plastics (e.g., e-waste plastics) during the process of pretreatment and thermolysis. It is found that chemical pretreatment is an efficient method for removal of halogens and metals.…”

Section: ■ Introductionmentioning

confidence: 99%

Co-pyrolysis of E-Waste Nonmetallic Residues with Biowastes

Shen

Yuan

Chen

et al. 2018

ACS Sustainable Chem. Eng.

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This work studied the copyrolysis of nonmetallic fractions from waste printed circuit boards (NMF-WPCB) with rice husk (RH). The chemical pretreatment integrated with pyrolysis was evaluated for copyrogasification valorization of e-waste plastics and biowastes for value-added fuel (e.g., syngas) production. The copyrolysis with cellulose-rich biomass can improve the NMF thermolysis efficiency, while the copyrolysis with lignin-rich biomass improved the activation energy. The copyrolysis NMF with RH can improve the fuel property and thermal conversion efficiency. Metals in the NMF were primarily removed by the acid leaching. Subsequently, the preloaded NaOH could react with the small-molecular bromine compounds (e.g., HBr/Br 2 releasing from the BFRs pyrolysis) to form more stable NaBr. Minerals (e.g., alkalis) in RH and NMF enhanced the Br stabilization in the char. In general, the syngas from the copyrolysis of PNMF with RH can be applied for fuels, while the char with lower contents of heavy metals is terminally disposed of by safely landfilling it.

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“…PCB consists not only of metals but of various other materials such as glass, resin, and paper; and various types of PCB recycling methodology, targeting different materials, have been proposed. Recent studies have, for example, employed hydrometallurgy [7,8], leaching and digestion [9][10][11], flotation [12,13], super-gravity separation [14], corona electrostatic separation [15], catalytic pyrolysis [16], and supercritical methanol [17].…”

Section: Introductionmentioning

confidence: 99%

An automated assessment method for integrated circuit chip detachment from printed circuit board by multistep binarization and template matching of X-ray transmission images

Ueda

Oki

Koyanaka

2020

J Mater Cycles Waste Manag

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Given the increase in digital product waste, demand for recycling of printed circuit boards (PCBs) is increasing. Precious and minor metals are often well concentrated in integrated circuit (IC) chips, especially in PCBs; hence, IC chips are primary targets for recycling. The technology for the non-destructive detachment of IC chips from PCBs is increasing in sophistication; however, the effectiveness of IC chip detachment is currently assessed manually and visually. In the present study, an automated IC chip detachment assessment method was developed, which combines multistep binarization and template matching of X-ray transmission images of crushed PCBs. To validate the method, five types of mechanically crushed PCBs from mobile phones were examined, and the developed method successfully assessed the IC chip detachment rate, with an average error rate of only 2.2% compared to visual assessment.

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New technology for recovering residual metals from nonmetallic fractions of waste printed circuit boards

Cited by 38 publications

References 27 publications

Assessing the Applicability of Gravity Separation for Recycling of Non‐Metal Fraction from Waste Printed Circuit Boards

Assessing the Applicability of Gravity Separation for Recycling of Non‐Metal Fraction from Waste Printed Circuit Boards

Co-pyrolysis of E-Waste Nonmetallic Residues with Biowastes

An automated assessment method for integrated circuit chip detachment from printed circuit board by multistep binarization and template matching of X-ray transmission images

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