| Solar energy as a promising clean energy has attracted the attention of various countries.The installed capacity of photovoltaics has grown rapidly in recent years.However,the life span of photovoltaic panels is only 25-30 years,and the continuous development of photovoltaic panel technology in recent years,the frequency of replacement has accelerated,resulting in the continuous increase of waste photovoltaic panels.These photovoltaic panels contain a lot of valuable materials.If they are directly discarded,it will cause great waste of resources and environmental pollution to the environment.Therefore,vigorously develop the separation technology of waste photovoltaic panels,which can effectively solve the problems of resource shortage and environmental pollution.According to the structural characteristics of photovoltaic panels,this research proposes physical crushing and pretreatment of photovoltaic panels.The removal of photovoltaic panel glass and the enrichment of silicon at different temperatures and different crushing times were investigated.The results show that during the crushing process,the photovoltaic panels are separated along the glass-silicon-based cell interface,with a certain selectivity.Compared with normal temperature crushing,mechanical crushing after liquid nitrogen treatment has a lower yield at 1 particle size.After 8 s of crushing,the enrichment rate of silicon reached 72% and the removal rate of glass reached 56%.As a result,most of the EVA film on the surface of the photovoltaic panel is exposed,and there are more diffusion channels,which is conducive to the deep separation of subsequent chemical methods.According to the sticking mechanism of EVA film,this study proposes a KOH-ethanol solution to degrade EVA film and recover silicon from waste photovoltaic panels.The effects of different alkalis,different sizes of photovoltaic panels,different temperatures,different concentrations,and different solid-liquid ratios on the separation rate of photovoltaic panels were experimentally studied.The results show that under optimal conditions,photovoltaic panels can be completely separated within 2 h,and the oxidation rate of recovered silicon wafers is less than2.5%.In addition,the excess KOH-ethanol solution can be recovered by distillation.Therefore,this method of recycling photovoltaic panels is of great significance to environmental protection and resource utilization.The absorption of microwaves,the difference in thermal expansion coefficient and similar compatibility principles of different components of photovoltaic panels are used.The technology of swelling and separating photovoltaic panels with microwave field enhanced EVA film is proposed.Taking into account the volatility of organic matter,the experiment adopts the method of condensation and reflux.This study mainly investigated the influence of the choice of swelling agent,different external fields,reaction temperature,concentration,solid-liquid ratio,etc.on the separation rate of photovoltaic panels.The results show that,using trichloroethylene as the swelling agent,in a microwave field,the reaction temperature is 70 ℃,the concentration is 4 mol/L,and the solid-to-liquid ratio is 50 g/L.It only takes 2 h to completely separate the photovoltaic panels.Through impedance analyzer,high temperature thermal expansion coefficient tester,thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),Fourier infrared analysis(FTIR),scanning electron microscope(SEM)and other means to analyze the mechanism of microwave enhanced swelling and separation.This research uses liquid nitrogen cryogenic crushing technology,polymer degradation technology,and field enhancement technology to achieve efficient separation of photovoltaic panels.It provides reliable solutions and theoretical support for the recycling and utilization of photovoltaic panels. |
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