Preparation Of Cu And Graphene/Cu Composite Materials By Electrodeposition Of Waste Circuit Boards

With the vigorous development of science and technology,the frequency of mobile phone updates is increasing rapidly,which leads to a large increase of used mobile phones.The metal grade in the waste mobile phone printed circuit board is far higher than that in the natural mineral resources,so the recycling value is very high.The non-metallic resources in the printed circuit board can be used in the application of recycled composite materials,and can be used as reinforcements of plastics and building materials,which also have high utilization value.There are abundant metal resources in the printed circuit board,especially the single copper content,The abandonment of such resources is undoubtedly a huge waste,and its recycling and reuse is of great significance to environmental protection and recycling of resources.In this paper,the waste mobile phone circuit board is used as the experimental material,the process of"mechanical pretreatment--acid leaching of H₂SO₄+H₂O₂system--electrodeposition method to recover pure copper/prepare composite materials"was studied for waste mobile phone circuit board.This study can provide a new method for green recycling of waste printed circuit boards.In this paper,the waste mobile phone printed circuit board（PCB）was pre-treated,crushed and screened by mechanical physical method.The particle sizes of-0.074 mm and 0.074-0.45 mm were investigated by XRF.The results show that the particle size of-0.074 mm is lower in metal grade but higher in non-metal content;However,the metal grade of 0.074-0.45 mm powder is higher,and the content of metal Cu is the highest.Therefore,the acid leaching process of 0.074-0.45 mm powders in H₂SO₄+H₂O₂system was studied,the effects of sulfuric acid concentration,leaching time and hydrogen peroxide content on the leaching of Cu in circuit board powder were investigated,the optimal sulfuric acid concentration for leaching is 6 M,and the Cu leaching rate is 92.85%;The optimal leaching time is 3 hours,and the Cu leaching rate is 91.2%;The optimal hydrogen peroxide content is 50 ml,and the Cu leaching rate is 98.0%.Under the optimum single factor parameters,the average leaching rate of metal Cu is 98.91%through parallel experiments,this leaching system does not need to add any other additives and reduces the production cost to some extent.In this paper,the electrodeposition process of copper from acid leaching solution of waste mobile phone circuit board powder was studied,using the leaching solution of waste mobile phone circuit board powder as electrolyte under optimal leaching conditions.Single-factor experiments of current density,sulfuric acid concentration and deposition temperature were investigated to recover pure copper by electrodeposition,it is concluded that the recovery of copper increases with the increase of current density,and it is 98.18%at 60 m A/cm²;The recovery of copper increases with the increase of sulfuric acid concentration,the recovery of copper at6 M sulfuric acid concentration is 98.94%;The recovery of copper first increases and then decreases with the increase of temperature,the recovery of copper is 99.3%at50℃.The purity of the cathode product copper powder is above 97%,and the impurities are less.The recovery of electrodeposited pure copper was 98.41%and the purity of copper powder was 98.26%.The results of SEM analysis show that the morphology of copper powder recovered by electrodeposition is dendritic.Under different factors,the morphology of copper powder shows dense or loose among branches,and the looser morphology of copper powder is smaller.While recovering metal copper from waste circuit boards using the electrodeposition method,metal based ideal reinforcing material graphene is added.Through ultrasonic treatment with the leaching solution of waste mobile phone circuit board powder under optimal leaching conditions,graphene is evenly dispersed in the leaching solution.Graphene/copper composite powders were prepared by electrodeposition,and the binding of graphene to copper was verified by SEM,Raman and XPS characterization.The effects of graphene content and current density on the composite powder were investigated.The influence of graphene content and current density on the composite powder was investigated.The conclusion is that under the condition of constant current density,graphene provides crystal nucleation sites in the electrolyte,making it easier to combine graphene with copper powder.In addition,an increase in graphene content will cause the grain size of copper powder in the cathode product to become smaller,while also increasing the graphene content in the composite material;When the graphene content remains unchanged,the graphene/copper composite materials prepared at different current densities also verify the binding between graphene and copper.As the current density increases,the copper powder grains in the composite material exhibit a loose dendritic shape.The electrodeposition process can not only achieve the recovery of metal copper from waste circuit boards,but also prepare graphene/copper composite materials,the composite material formed by cold pressing and sintering is beneficial for rolling processing and can prepare materials with better performance.The recovery of this value-added compound has pointed out a new path for electrochemical recovery.