Product characteristics and potential energy recovery for microwave assisted pyrolysis of waste printed circuit boards in a continuously operated auger pyrolyser

Yingwen Zhang, Chunbao Zhou, Yang Liu, Tianhao Zhang, Xiangtong Li, Long Wang, Jianjun Dai, Junshen Qu, Changfa Zhang, Mengyan Yu, Yanxin Yuan, Yajie Jin, Hejie Yu and Jie Fu

Energy, 2022, vol. 239, issue PD

Abstract: The efficient disposal and recycling of nonmetal materials from waste printed circuit boards (WPCBs) can be a significant challenge due to their toxicity and complexity. In this paper, the characteristics and energy recovery of products from WPCBs pyrolysis at different temperatures were investigated using a two-mode auger pyrolyzer operated continuously under microwave irradiation. The results indicated that the organic matter in WPCBs was almost completely recovered (88.03%) and the maximum condensate yield (22.66 wt%) was obtained at 550 °C, with lower brominated compounds (1.83%) and higher phenols recovery (80.4%). Pyrolysis oil with low moisture content (0.5–2%) could be directly separated in-situ from condensates. Pyrolysis residue (PR) was further separated into valuable glass fiber and powder char with a certain degree graphitization by ball-milling. Bromine and sulfur mostly remained in powder char. The highest yields of CO (11.61 wt%) and H2 (1.50 wt%) were obtained at 750 °C. Energy balance analysis showed that 90.25% of energy was recovered at 550 °C, providing an energy efficiency as high as 72.00%. Bromine mainly remained in PR in the form of inorganic bromine (44.35–56.00 wt%), and was transferred to gas phases (HBr and CH3Br) with temperature increasing.

Keywords: Microwave pyrolysis; Waste printed circuit boards; Auger pyrolyser; Energy balance (search for similar items in EconPapers)
Date: 2022
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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:239:y:2022:i:pd:s0360544221026323

DOI: 10.1016/j.energy.2021.122383

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