Vacuum Pyrolysis Treatment Of Waste Integrated Circuits(ICs) And Utilization Of Pyrolysis Oil

With the development trend of high integration,miniaturization and intelligence of electronic products,integrated circuits(ICs)are widely used in various electronic products.They have the advantages of small size,light weight,high reliability and good performance.Due to the rapid update and replacement of electrical and electronic equipment,a large number of waste ICs are produced.On one hand,waste ICs contain many recyclable resources such as copper,silver and so on.On the other hand,waste ICs contain organic compounds,which will cause environmental pollution and do harm to human health if not properly handled.Therefore,reasonable methods should be adopted to treat and recycle waste ICs.The disposal and recycling of waste ICs is an extremely difficult task because the organic packaging material is tightly wrapped around them,which hinders the recycling of metal resources.And if the organic packaging material is not properly treated,it will cause serious pollution to the environment.At present,there are few studies on the recycling technology of ICs,and there is no mature recycling technology for ICs.This study proposes to use vacuum pyrolysis combining mechanical physics to process waste ICs and recover metals.The pyrolysis oil collected was used as raw material to synthesize oil-base resin,so as to realize the resource utilization of pyrolysis oil.In this study,vacuum pyrolysis was used to degrade the organic packaging materials of waste ICs and destroy the structure to facilitate metal recovery.The response surface methodology was used to investigate the effects of temperature,pressure and holding time on the degradation rate of organic matter in the process of vacuum pyrolysis of waste ICs.The optimal pyrolysis conditions were temperature of 615?,pressure of 20 Pa,holding time of 24 min.Under this condition,the organic degradation rate reached 80.05%.The composition and content of pyrolysis products were analyzed.It is found that the higher the pyrolysis temperature was,the more complex the components of pyrolysis oil were,and the pressure had no obvious influence on the components of pyrolysis oil.On this basis,combined with the composition of pyrolysis oil and valence bond theory,the pyrolysis mechanism of vacuum pyrolysis treatment of waste ICs was revealed as fracture of covalent bond,generation of free radical and combination of free radical.Pyrolysis oil was recovered by regions through the means of temperature-controlled condensation.And the components of the collected pyrolysis oil were analyzed.Pyrolysis oil which can be utilized was used as raw material to synthesize oil-based resin.The optimum conditions for the synthesis of oil-based resin were as follows: the molar ratio of phenol to formaldehyde in the pyrolysis oil was 1:0.8,the synthesis temperature was 90?,the reaction time was 2 h and the concentration of hydrochloric acid was 5.0%.Under this condition,the yield of oil-based resin was 82.5%.Oil-based resin was characterized and it was found that oil-based resin and commercial resin have similar morphology,thermal stability and chemical structure,indicating that the synthetic oil-based resin has a certain application prospect.According to the composition of pyrolysis oil and the characterization results of oil-base resin,the mechanism of synthesis of oil-base resin was revealed as formaldehyde protonation reaction,phenolic addition reaction and condensation reaction.The pyrolysis residue was crushed and screened after pyrolysis and it was concluded that metal concentrate and nonmetals accounted for 43.17% and 56.83%,respectively.The magnetic separation method was used to separate the metal iron from the metal concentrate and recover metal copper.And the recovery rate of copper reached 98.21%.On this basis,a process route combining the vacuum pyrolysis and mechanical physics to recycle and dispose waste ICs was established.This study provides a theoretical basis and reference for the treatment and resource utilization of organic packaging materials and metal recovery of waste ICs.