Research On Technology And Method Of Discarded PCB Reutilization Based On Supercritical CO₂ Fluid

The recycling of waste electrical and electronic equipments can not only save the limited resource but also can protect environment effectively from pollution. It is the important component for realizing circular economy and sustainable development stratagem. Among these Waste Electrical and Electronic Equipments, Printed Circuit Board scraps (PCBs) have the following characteristics: the large quantity of the whole wastes, the wide usage scope, the high value for recycle and the serious environment pollution. So many research institutions inside and outside of our country have had paid more attentions to the research on the technique and method of discarded PCBs' recycling. After summarizing the existing methods of recycling discarded PCBs, a new technique based on the supercritical fluid technology with a benign environmental performance has been studied in the paper. The basic principle of this method, the recycling technology model and the integral capability'valuation of the technology has been deeply analyzed in this paper. The research has laid the foundation for the industrialization application of the PCBs recycling based on supercritical fluid technology. It also provides a theory base and technical support to the application of this method in other waste electrical and electronic equipments recycling through the research.In the beginning of this paper, the research and application actuality of the existing PCB recycling technologyes, such as physical process, chemical process and so on, are summarized at first. And the merit and shortcoming of each recycling process have also been summarized at the same time. Then on the base of analyzing the structure and materials composition of PCBs, the technology and method of discarded PCBs recycling based on supercritical CO₂ fluid are introduced. The principle of the reaction process and the experiment research are all deeply studied.The primary work of the paper included the following aspects:1. The stress and strain of the PCBs in the supercritical CO₂ fluid are analyzed. On the base of analyzing the materials property and the different material layer combing forms, the model of supercritical fluid is established in ANSYS8.0. The amount and the distribution of the PCBs' stress and strain in supercritical fluid are studied, and the recation principle to the delaminating of PCBs is analyzed.2. The decomposition of the bonding resin material layer in PCBs is researched. On the base of establishing the experimental equipments, a series of experiments has being done. The decomposition product of resin is analyzed by means of Micromass GCT—MS, indicating the process of decomposition and the components of the product.3. PCB recycling technology model and its optimization research with CO₂-supercritical fluid. Establishing PCB recycling technology process model with supercritical fluid, using orthogonal table L₂₅(5⁶) to start four-factors-five-levels' trials, with SPSS software to analyze the PCB's delamination because of temperature, pressure, reaction time, solvent and some other parameters'...