Recycling of organic materials and solder from waste printed circuit boards by vacuum pyrolysis-centrifugation coupling technology

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 30 min 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 1000 rpm for 10 min. The type-A of WPCBs pyrolysed to form an average of 67.91 wt.% residue, 27.84 wt.% oil, and 4.25 wt.% gas; and pyrolysis of the type-B of WPCBs led to an average mass balance of 72.22 wt.% residue, 21.57 wt.% oil, and 6.21 wt.% 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.

► An efficient recovery technology of WPCBs (vacuum pyrolysis-centrifugation coupling technology (VPCT)) is first put forward.
► Vacuum technology was used to enhance the process of pyrolysis of organic resin and separation of volatile compounds.
► The organic resin, glass fiber and metal were separated simultaneously by VPCT.
► A new equipment of recycling of WPCBs is exploited, which can separate solder and pyrolyze organic materials simultaneously.
► Two kinds of vacuum pyrolysis products of WPCBs were characterized and the utilization methods of them were made.