Study On The Pyrolysis Of Waste Printed Wiring Boards

With the development of the technology, the number of new applications for electronics increases rapidly and the service life become even shorter than before, which results in a large number of waste electronic and electric equipments. Waste printed wiring boards (PWB) are recognized as a typical kind of electronic waste and are numerous. Treatment and recycling of this kind of waste is a complex problem and needs to be solved urgently.The metal components and non-metal components of PWB can be recycled by pyrolysis. However, HBr and brominated organic compounds which are pollutants and can cause the equipment corrosion are generated during the pyrolysis of the brominated flame retardants, which exists in the PWB. Therefore, the brominated flame retardant has negative effect on the pyrolysis of PWB.A typical kind of FR-4 PWB, tetrabromobisphenol A and the decabromodiphenyl oxide are chosen as the experimental materials. The characteristics and products during the pyrolysis of the samples have been investigated by using TG-FTIR method under N₂ atmosphere. Polypropylene, plastic, calcium hydroxide and calcium carbonate have been used as additives with PWB in co-pyrolysis experiments, which have also used the TG-FTIR mean to study the characteristics and pyrolysis products. It is helpful for the co-pyrolysis experiments in quartz tube furnace.The effects of additives, Ca/Br molar ratio and the co-pyrolysis temperature on the HBr removal and the bromine conversion have been studied in quartz tube furnace co-pyrolysis experiments and ion chromatography experiments. Consequently, a better bromine conversion condition has been found and the bromine distribution in the pyrolysis products has been investigated.The gas phase, liquid phase and solid phase pyrolysis products generated in the best operation condition have been determined and analyzed by several methods, and the possible resource utilization of pyrolysis product has been discussed.