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Vacuum co-pyrolysis of Chinese fir sawdust (CFS) and waste printed circuit boards (WPCBs) at different heating conditions were examined in this paper. The composition of the pyrolysis oils was analyzed by gas chromatography–mass spectrometry (GC–MS). It was found that the content of most of the compounds with relatively long molecular chain had a higher value at relatively low temperature (400–600 °C) and short holding time (10 min), and decreased at relatively high temperature (800 °C) and long holding time (30–90 min); while the content of most of the compounds with relatively short molecular chain presented an adverse trend. The co-pyrolysis process was also analyzed by thermogravimetric (TG) analysis with evolved product analysis by Fourier transform infrared (FTIR) spectroscopy. The results showed that the volatiles were mainly generated between 300 and 500 °C, and after 500 °C, noncondensable gases (CO 2 , CO and CH 4 ) were the main components in the pyrolysis process. [ABSTRACT FROM AUTHOR]

Highlights: [•] Co-pyrolysis process presents antagonistic effect in the yields of the volatiles. [•] Co-pyrolysis process is good for the formation of brominated aromatic compounds. [•] The volatiles were mainly formed between 300 and 450°C in the pyrolysis process. [•] Noncondensable gases (CO2, CO, CH4, etc.) were the main components after 450°C. [•] Co-pyrolysis oils show better synthetic properties than the separate ones. [ABSTRACT FROM AUTHOR]

Abstract: Waste printed circuit boards (WPCBs) contain lots of valuable resources together with plenty of hazardous materials, which are considered both an attractive secondary resource and an environmental contaminant. In this research, a new process of “centrifugal separation+vacuum pyrolysis” for the combined recovery of solder and organic materials from WPCBs was investigated. The results of centrifugal separation indicated that the separation of solder from WPCBs was complete when WPCBs were heated at 240°C, and the rotating drum was rotated at 1400rpm for 6min intermittently. The results of vacuum pyrolysis showed that the type-A of WPCBs without solder pyrolysed to form an average of 69.5wt% residue, 27.8wt% oil, and 2.7wt% gas; and pyrolysis of the type-B of WPCBs without solder led to an average mass balance of 75.7wt% residue, 20.0wt% oil, and 4.3wt% gas. The pyrolysis residues contain various metals, glass fibers and other inorganic materials, which could be recycled for further processing. The pyrolysis oils can be used for fuel or chemical feedstock and the pyrolysis gases can be collected and combusted for the pyrolysis self-sustain. This clean and non-polluting technology offers a new way to recycle valuable materials from WPCBs and prevent the environmental pollution of WPCBs effectively. [Copyright &y& Elsevier]

Abstract: Here, we focused on the recycling of waste printed circuit boards (WPCBs) using vacuum pyrolysis-centrifugation coupling technology (VPCT) aiming to obtain valuable feedstock and resolve environmental pollution. The two types of WPCBs were pyrolysed at 600°C for 30min under vacuum condition. During the pyrolysis process, the solder of WPCBs was separated and recovered when the temperature range was 400–600°C, and the rotating drum was rotated at 1000rpm for 10min. The type-A of WPCBs pyrolysed to form an average of 67.91wt.% residue, 27.84wt.% oil, and 4.25wt.% gas; and pyrolysis of the type-B of WPCBs led to an average mass balance of 72.22wt.% residue, 21.57wt.% oil, and 6.21wt.% gas. The GC–MS and FT-IR analyses showed that the two pyrolysis oils consisted mainly of phenols and substituted phenols. The pyrolysis oil can be used for fuel or chemical feedstock for further processing. The recovered solder can be recycled directly and it can also be a good resource of lead and tin for refining. The pyrolysis residues contained various metals, glass fibers and other inorganic materials, which could be recovered after further treatment. The pyrolysis gases consisted mainly of CO, CO2, CH4, and H2, which could be collected and recycled. [Copyright &y& Elsevier]

Abstract: In this research, a two-step process consisting of vacuum pyrolysis and vacuum centrifugal separation was employed to treat waste printed circuit boards (WPCBs). Firstly, WPCBs were pyrolysed under vacuum condition at 600°C for 30min in a lab-scale reactor. Then, the obtained pyrolysis residue was heated under vacuum until the solder was melted, and then the molten solder was separated from the pyrolysis residue by the centrifugal force. The results of vacuum pyrolysis showed that the type-A of WPCBs (the base plates of which was made from cellulose paper reinforced phenolic resin) pyrolysed to form an average of 67.97 wt.% residue, 27.73 wt.% oil, and 4.30 wt.% gas; and pyrolysis of the type-B of WPCBs (the base plates of which was made from glass fiber reinforced epoxy resin) led to an average mass balance of 72.20 wt.% residue, 21.45 wt.% oil, and 6.35 wt.% gas. The results of vacuum centrifugal separation showed that the separation of solder was complete when the pyrolysis residue was heated at 400°C, and the rotating drum was rotated at 1200rpm for 10min. The pyrolysis oil and gas can be used as fuel or chemical feedstock after treatment. The pyrolysis residue after solder separation contained various metals, glass fibers and other inorganic materials, which could be recycled for further processing. The recovered solder can be reused directly and it can also be a good resource of lead and tin for refining. [ABSTRACT FROM AUTHOR]