Liberation characteristics after cryogenic modification and air table separation of discarded printed circuit boards

Zhou, Cuihong; Pan, Yuxin; Lu, Maxi; Yang, Changshun

doi:10.1016/j.jhazmat.2016.03.008

Cited by 26 publications

(12 citation statements)

References 29 publications

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“…It has been confirmed that using a thermal pretreatment before crushing can significantly reduce energy consumption and noise pollution of the whole liberation (Chen et al 2011;Duan 2010;Li et al 2010a). Zhou et al (2016) discussed lowtemperature modification of discarded printed circuit board, revealing that the PCBs' mechanical properties decreased significantly under the condition of cryogenic treatment at −20°C, which supported subsequent crushing and improved the recovery efficiency. However, these could cause an inconvenient operation and serious dust pollution.…”

Section: Introductionmentioning

confidence: 91%

Effect of thermal shock process on the microstructure and peel resistance of single–sided copper clad laminates used in waste printed circuit boards

Liu

Wan

Wang

et al. 2019

Journal of the Air & Waste Management Association

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Efficient pre-processing is essential to the mechanical recovery of waste printed circuit boards (WPCBs). In this work, a thermal shock pretreatment was utilized to damage the interface between metals and nonmetals of single-sided copper clad laminates (SSCCLs), which are usually employed as the base material of printed circuit boards (PCBs). The effects of three thermal shock treatment parameters-i.e., peak temperature, holding time, and thermal shock cycle times-on the adhesion strength of SSCCLs were evaluated by orthogonal experiments. Microstructures and peel resistance of SSCCLs before and after thermal shock were characterized by scanning electron microscopy (SEM) and 90°peel test, respectively. Our results showed that the impact of three major factors that influence liberation efficiency was in the sequence of peak temperature > shock cycle times > holding time. Furthermore, the optimal thermal shock level could be achieved when the peak temperature was 300°C with the soaking time of 30 min and three cycle times. In the meantime, the corresponding peel strength of the SSCCLs (0.065 N/mm) was sharply decreased by 94% in comparison with those without thermal shock treatment. The manual dismantling experimental data verified the good feasibility of the optimal thermal shock process, suggesting that the copper foil could be readily dismantled from the substrate by hand after pretreatment, with a successful separation rate of 100% and a peeling efficiency of~30 seconds per piece. Therefore, the optimal thermal shock process could notably improve liberation of metals and nonmetals, which would be helpful for efficient recycling of WPCBs.Implications: The interface between copper foil and laminate dielectric in a PCB can be weakened significantly via efficient thermal shock method. Thus, a good liberation could be achieved after thermal shock. In this work, a manual peeling of copper foil from the SSCCL substrates was achieved efficiently after optimal thermal shock pretreatment, confirming the feasibility of a shorter process of metal recovery from scrap SSCCLs without pulverization. The results will be useful for the pretreatment of recovery of the WPCBs.

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Section: Introductionmentioning

confidence: 91%

Effect of thermal shock process on the microstructure and peel resistance of single–sided copper clad laminates used in waste printed circuit boards

Liu

Wan

Wang

et al. 2019

Journal of the Air & Waste Management Association

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“…• cryocomminution of waste allows to crush and liberate materials from certain kinds of waste more effectively [33]; • high-temperature superconducting magnets outperform permanent magnets and they work at the temperature of liquid nitrogen [34]; • liquid nitrogen enables dry, eco-friendly cleaning (already used in industry [35]), so it can be applied to the waste as well.…”

Section: Unused Effects and Materials Propertiesmentioning

confidence: 99%

Technological Landscape and Ideation in the Field of Waste Separation with Help of TRIZ

Ivanovskis

Kärki

Lahtela

2019

IFIP Advances in Information and Communication Technology

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Solid waste separation is an imperative part for closing material flow under principles of the circular economy. A multitude of technologies are at a different stage of development to perform this task and meet performance requirements at extracting valuable resources from waste streams. A thorough review of available options and possibilities for future development was required to pursue further progress. TRIZ (from Russian abbreviation: Theory of Inventive Problem Solving) methodology facilitated drawing a technological landscape for state of the art in solid waste separation for material recovery, as well as generating new directions of research. From the vast collection of TRIZ tools for systematic invention two approaches helped in the survey: effects databases and function-oriented search. Positive outcomes of their application include systematization of available knowledge, identification of potentially useful phenomena and getting ideas for the adoption of technologies from other domains. The case illustrates how rather loose (due to the broadness of the topic) application of TRIZ methods results in fruitful insights. A view at the effects databases as a collection of technological "genes" is given.

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“…Reducing of the size at which liberation starts to take place (D 1 ) is the key factor for efficient physical concentration. Low-temperature pyrolysis of PCB, 26,40) cryogenic treatment 8,41) and microwave inducing 42) are some of the preprocesses which enables the Cu to liberate in coarser size ranges. It should be noted that liberation phenomenon alteration promoted by the prior treatments demand more detailed quantification in terms of evaluation of the process performance.…”

Section: Liberation Behavior Of Cumentioning

confidence: 99%

Liberation Characteristics Assessment for Copper Component in PCB Comminution Product by Image Analysis

et al. 2018

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Cu is one of the most valuable metals found in waste printed circuit boards (PCBs). In order to recover the metals from the e-waste, PCB recycling process exploiting physical concentration techniques have widely been applied. Size reduction steps including crushing and grinding are done for liberation of Cu from the non-metallic materials such as glass fiber and epoxy resin. Degree of liberation is an important factor by which liberation performance of comminution process is evaluated. The primary purpose of this study was to investigate liberation characteristics of Cu particles in comminuted PCB by using image analysis method. The analysis procedures include image processing such as noise reduction, edge detection and component discrimination so that a set of images of ground PCB particles provides quantitative information such as Cu grade distribution and degree of Cu liberation. The Cu liberation phenomenon was also discussed in terms of its disassociation behavior from non-metallic material and grindability difference.

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Liberation characteristics after cryogenic modification and air table separation of discarded printed circuit boards

Cited by 26 publications

References 29 publications

Effect of thermal shock process on the microstructure and peel resistance of single–sided copper clad laminates used in waste printed circuit boards

Effect of thermal shock process on the microstructure and peel resistance of single–sided copper clad laminates used in waste printed circuit boards

Technological Landscape and Ideation in the Field of Waste Separation with Help of TRIZ

Liberation Characteristics Assessment for Copper Component in PCB Comminution Product by Image Analysis

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