Disposaland Resource Recovery For Waste Aluminum Electrolytic Capacitors

Large quantities of waste printed circuit boards(WPCBs)mounted with electronic components(ECs)are generating continuously due to the market explosion for electronic and electrical products.Currently,most of studies about recycling process of WPCBs are focused on the disassembling of WPCBs and PCB substrates recycling.However,researchers have not paid much attention to the recycling of ECs.Therefore,the research on the efficient and environmentally friendly recycling process of ECs is of great importance to integrate the recycling chain of WPCBs.This paper reviews the progress of the recycling technologies of ECs at home and abroad.We disassembled the aluminum electrolytic capacitors(AECs)from WPCBs by automatic disassembling system.We propose an efficient and environmentally friendly recycling process for waste AECs,which consists of heating treatment and comprehensive separations(magnetic separation,eddy current separation and electrostatic separation).In this study,experiments were conducted to obtain the optimal parameters.The results demonstrated that the optimal parameters of disassembling process are heating temperature 260 °C,preheating time 2min,inclination angle of the disassembling machine 1°,and the rotating speed of rotating cylinder 5 rpm).The optimal temperature and time of heating treatment were 260 °C and 10 min,respectively.The aim of heating treatment was to evaporate and absorb the electrolyte containing many toxic materials.The AECs without electrolyte were crushed and separated by magnetic separation to get ferrous pins.Then the particles ofbig sizes and small sizes were separated by eddy current separation and electrostatic separation respectively to recycle aluminum and nonmetal.The optimal parameters of eddy current separation were feeding speed of1.0-1.1 m/s and rotation speed of magnetic field 3000-3180 rpm.The optimal parameters of electrostatic separation were roll speed of 30-50 rpm and high voltage level of 25-27.5 kV.The total recovered ratio of metals(aluminum and iron)and nonmetals reached 87.90% and 92.42%respectively under the optimal experimental condition of the comprehensive separations.Based on these results,a process combining heating treatment,crushing,sieving and comprehensive separations(magnetic separation,eddy current separation and electrostatic separation)is proposed,contributing to the efficient disposal and resource recovery for waste AECs and other ECs in a large industrial scale.