Disassembly Products Of Waste Mobile Phones And Precious Metals Directional Extraction From Waste Circuit Boards

E-waste such as waste mobile phones has the dual attributes of pollution and high added value.At present,the research focuses on the reuse of waste mobile phones and precious metal recycling technology and equipment,basically does not involve the characteristics of the products,and rarely discusses the directional recovery of precious metals in waste mobile phone circuit boards from the point of view of non-cyanidation,low corrosion and short process.Therefore,70 kinds of mobile phones were disassembled in this paper,and the content,distribution and occurrence state of precious metals as well as the characteristics of harmful substances were analyzed.Through market research and investigation,the data of key disassembly products of 200 kinds of mobile phones were collected.The study on the separation of precious metals on the surface of the products by sulfuric acid-hydrogen peroxide-glutamic acid system was carried out,and the inner precious metals of the products were extracted by wet leaching.The specific conclusions are as follows:（1）The disassembly products of mobile phone mainly include shell,screen,circuit board,battery,vibration motor,receiver,microphone,camera and fastening screw.According to different functional materials,the disassembled products with high precious metal content in mobile phone were subdivided into 9 kinds and 15 categories,and the precious metal content was tested.It was found that the gold content in chip and circuit board substrate in 1 t waste mobile phone is the highest,21.98 g and 9.51 g respectively,and the highest content of silver and palladium in patch capacitor was 45.27 g and 1.63 g,respectively.（2）Precious metals are mainly distributed on the surface of waste mobile phone circuit board substrate.The effect of sulfuric acid-hydrogen peroxide-glutamic acid system on the peeling of gold plating layer was studied by response surface experiment design.The gold peeling rate was 99.23%under the condition of 2.2 mol/L H₂SO₄,25 v/v%H₂O₂ and 12.5 g/L glutamic acid.The kinetic analysis shows that the peeling of gold coating in sulfuric acid-hydrogen peroxide system is a solid-liquid multiphase reaction,which accords with the unreacted nuclear contraction model,and the peeling process of gold is mainly controlled by diffusion and chemical reaction.（3）Precious metals are mainly distributed in the interior of waste mobile phone components.The ordinary metals in the components are leached by sulfuric acid-hydrogen peroxide system first.Under the condition of 2 mol/L H₂SO₄ 10 v/v%H₂O₂ at 30℃,3 h,and the solid-liquid ratio at 1:10,the leaching rate of copper is more than 98%,and the leaching rate of tin,iron and nickel is more than 80%.Finally,when the ultrasonic intensity is 139 W,thiourea is 12.57g/L,p H is 1.57 g/L,and the mass fraction of Fe³⁺is 0.62%,the gold leaching rate is 91.72%.The results of response surface analysis show that the simulation equation fits well with the experimental data,and the order of significant variables is thiourea concentration>p H value>Fe³⁺mass fraction>ultrasonic intensity.