Using vacuum pyrolysis and mechanical processing for recycling waste printed circuit boards

Long, Laishou; Sun, Shuiyu; Zhong, Sheng; Dai, Wei; Liu, Jingyong; Song, Weifeng

doi:10.1016/j.jhazmat.2009.12.078

Cited by 168 publications

(57 citation statements)

References 33 publications

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“…Jie et al (Jie et al, 2010;Jie et al, 2008) performed the pyrolysis of WCB from waste personal computers, at temperatures between 300 and 700 ºC for 30 min, and suggested that the resulting pyro-oils and gases could be used as fuels or chemical material resource. Long et al (Long et al, 2010) proposed a combination of vacuum pyrolysis and mechanical processing using a pilot-scale fixed bed reactor to recycle the different fractions of waste WCB (i.e. organic resins, copper and glass fiber).…”

Section: Introductionmentioning

confidence: 99%

Pollutant emissions during pyrolysis and combustion of waste printed circuit boards, before and after metal removal

García

Conesa

Moltó

et al. 2014

Science of The Total Environment

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The constant increase in the production of electronic devices implies the need for an appropriate management of a growing number of waste electrical and electronic equipment.Thermal treatments represent an interesting alternative to recycle this kind of waste, but particular attention has to be paid to the potential emissions of toxic by-products. In this study, the emissions from thermal degradation of printed circuit boards (with and without metals) have been studied using a laboratory scale reactor, under oxidizing and inert atmosphere at 600 and 850 ºC. Apart from carbon oxides, HBr was the main decomposition product, followed by high amounts of methane, ethylene, propylene, phenol and benzene. The maximum formation of PAHs was found in pyrolysis at 850 ºC, naphthalene being the most abundant. High levels of 2-, *Corresponding author. E-mail: ja.conesa@ua.es. Phone: +(34)965903400 Fax: +(34)965903826 2 4-, 2,4-, 2,6-and 2,4,6-bromophenols were found, especially at 600 ºC. Emissions of PCDD/Fs and dioxin-like PCBs were quite low and much lower than that of PBDD/Fs, due to the higher bromine content of the samples. Combustion at 600 ºC was the run with the highest PBDD/F formation: the total content of eleven 2,3,7,8-substituted congeners (tetra-through heptaBDD/Fs) was 7240 and 3250 ng WHO 2005 -TEQ/kg sample, corresponding to the sample with and without metals, respectively.

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Section: Introductionmentioning

confidence: 99%

Pollutant emissions during pyrolysis and combustion of waste printed circuit boards, before and after metal removal

García

Conesa

Moltó

et al. 2014

Science of The Total Environment

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“…Zhan et al 151 demonstrated the application of vacuum metallurgy to enrich Cu from processed PWB by increasing the purity of Cu in Cu-Zn mixtures from 91% to over 99%. Long et al 152 used vacuum pyrolysis (a technique also discussed under Thermal WEEE Treatment) in combination with various mechanical processes to separate PWB organic and metal fractions. A high-purity Cu product (99.5%) was obtained; the authors observed that vacuum pyrolysis could also be used to decompose organic matter into gases or liquids that can be potentially used as fuel.…”

Section: Methods For Extracting Metals From Pwbsmentioning

confidence: 99%

Environmental Issues and Management Strategies for Waste Electronic and Electrical Equipment

Townsend

2011

Journal of the Air & Waste Management Association

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Issues surrounding the impact and management of discarded or waste electronic and electrical equipment (WEEE) have received increasing attention in recent years. This attention stems from the growing quantity and diversity of electronic and electrical equipment (EEE) used by modern society, the increasingly rapid turnover of EEE with the accompanying burden on the waste stream, and the occurrence of toxic chemicals in many EEE components that can pose a risk to human and environmental health if improperly managed. In addition, public awareness of the WEEE or "e-waste" dilemma has grown in light of popular press features on events such as the transition to digital television and the exportation of WEEE from the United States and other developed countries to Africa, China, and India, where WEEE has often not been managed in a safe manner (e.g., processed with proper safety precautions, disposed of in a sanitary landfill, combusted with proper air quality procedures). This paper critically reviews current published information on the subject of WEEE. The definition, magnitude, and characteristics of this waste stream are summarized, including a detailed review of the chemicals of concern associated with different components and how this has changed and continues to evolve over time. Current and evolving management practices are described (e.g., reuse, recycling, incineration, landfilling). This review discusses the role of regulation and policies developed by governments, institutions, and product manufacturers and how these initiatives are shaping current and future management practices.

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“…The highest conversion can be obtained under 800 • C and 135 min [1]. The conversion could be enhanced using vacuum pyrolysis [32,33]. For example, the oil yield could increase to 27.8% when 600 • C and 30 min were applied in the vacuum pyrolysis.…”

Section: Quantitative Comparison With Current Methodsmentioning

confidence: 99%

Materials recovery from waste printed circuit boards by supercritical methanol

Xiu

Zhang

2010

Journal of Hazardous Materials

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a b s t r a c tThe recovery of valuable materials from waste printed circuit boards (PCBs) is quite difficult due to the heterogeneous mix of polymer materials, multiple kinds of metals and glass fiber. A feasibility study was conducted using supercritical methanol (SCM) to simultaneously recover polymers and metals from waste PCBs. The study focused on the characteristics of both oils and solid products obtained from the SCMtreated waste PCBs. The operation conditions were temperature range of 300-420• C, treatment time between 30 and 120 min and solid-to-liquid ratio (S/L) of 1:10-1:30 (g/mL) so as to understand the products and depolymerization mechanisms of waste PCBs in SCM. GC-MS results revealed that the oils mainly contained phenol and its methylated derivatives, and the methylated derivatives increased with the increase of reaction temperature. The methylated reaction occurred mainly above 400• C. The liquid products also contained a significant number of phosphated fire retardant additives such as triphenyl phosphate, which decreased significantly with the increase of reaction temperature. The solid product mainly consisted of Cu, Fe, Sn, Pb and Zn, as well as lower concentrations of precious metals such as Ag and Au.

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Using vacuum pyrolysis and mechanical processing for recycling waste printed circuit boards

Cited by 168 publications

References 33 publications

Pollutant emissions during pyrolysis and combustion of waste printed circuit boards, before and after metal removal

Pollutant emissions during pyrolysis and combustion of waste printed circuit boards, before and after metal removal

Environmental Issues and Management Strategies for Waste Electronic and Electrical Equipment

Materials recovery from waste printed circuit boards by supercritical methanol

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