| As a result both of the accelerating paces of technological development and of therapidly increasing number of new applications for electronics and ever shorter service life,the world are facing an ever growing stream of electronics waste. Electronic scrap recyclinghas been reinforced by strict legislations and will be pushed ahead by the increasingenvironmental awareness. Printed circuit board scrap (PCBs) is recognized as a typical kindof electronics waste, and a challenge to effective disposal. Treatment and recycling of thiskind of wastes properly have been laid store by researchers all over the world. Whereas,any attempt on basal research has not been made in our country up to the present. Firstly, the existing and potential technologies used for the treatment and recycling ofend-of-life PCBs have been identified and assessed in this thesis. Based on a preciseanalytical characterization of PCBs and considering the advantages of treatment of solidwastes by pyrolysis, a pyrolysis process for disposal and recycling of PCBs has beenproposed. The feasibility of this process has been demonstrated under experimentalresearch. For this purpose, this study has been processed as the following aspects. To develop proper recycling strategies and waste disposal systems for equipped circuitboards, a good knowledge of changing behaviors, both of the metals and the nonmetals,during treatment is required. The physical-chemistry characteristics of the maincompositions of PCBs have been determined qualitatively and quantificationally in thisthesis. The variety of physical properties of PCBs during mechanical treatment has beenstudied. The results indicate that classification and liberation of different materials areeffected by size distribution, shape and density of the particles obtained. A typical kind of FR-4 PCBs used widely is chosen as the experimental material. Thesamples have been pyrolyzed both in a laboratory scale tube-type reactor and thermalbalance. In addition, the effects of conditions of pyrolysis have been investigated. Theresults have indicated that atmosphere, heating rate, final pyrolysis temperature (FPT) andparticle size all influence the pyrolysis process of PCBs.Another important content of this thesis is the characteristics and the evaluation offeasibility of pyrolysis products. The information, such as composition, distribution,molecule structure and physical-chemistry properties of the pyrolysis products of PCBshave been provided by modern analytical methods. Simultaneity, the routes of recycling ofdifferent pyrolysis products have been discussed in this thesis. The behavior of brominated epoxy resin (BER), the major organic component of PCBs,in thermal decomposition with regard to the reaction step of decomposition anddecomposition products have been investigated using macromolecule chemistry theory.Thermoplysis of PCBs occurs in three steps: decomposition of brominated part of BER,decomposition of non-brominated part of BER, char formation. On the basis of thegeneration mechanism and the approach of treatment of HBr, three main process routes, Cl2peroxide, distillation and neutralization are brought forward to convert HBr into usableproducts. The evaluation of feasibility of HBr has been carried out. A pyrolysis mechanism describing the reaction is the foundation of a kinetic model forthe PCBs. It is confirmed that the pyrolysis reactions of PCBs occurred in three majorregions using thermogravimetric data analysis methods. The separation of data ofthermogravimetric weight loss has been achieved by using Gausses function method, and akinetic model has been established. The prediction ability of the developed model has beentested for a number of different heating rates. Experimental data have been compared tomodel results for constant linear heating rate cycles. The model is shown to accuratelypredict the extent of reaction of the pyrolysis of PCBs samples. Finally, general summary and conc...
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