Micro-nano Copper Powders Recovery From Waste Printed Circuit Boards By Electrokinetic Process

Printed circuit board is an essential part of almost all electronic and electrical products.With the technology innovation,large amount of wast e printed circuit boards(WPCBs)were produced.The concentration of p-recious metals in WPCBs is much higher than that of rich minerals.Ther-efore,WPCBs reutilization show significant importance on both resources and economics,especially at present there is an increasingly sharp confli-ction between the supply and demand of natural resources.In this study,electrokinetics was successfully applied in the separation of metal and non-metal contained in WPCBs metals concentrated scraps,which could also be used to prepare micro and nano copper powders from WPCBs metals concentrated scraps without pretreatment.Main results obtained are as followings:1.The experimental results of metal and nonmetal separation by electrokinetics show:under the optimal conditions,30 g/L CuSO4·SH2O,60 g/L NaCl,170 g/L H2SO4,30 g/L WPCBs,80 mA/cm2 for 4 h,the total metals seperating rate is up to 95.56%;copper recovery rate and current efficiency of copper are 94.45%and 56.91%;the recovery rate of other metals,Al,Cr,Fe,Pb,Sn and Zn,are 19%、43.33%.99.24%、66.55%、95.55%and 68.68%,respectively.The results show that electrokinetics can effectively realize the separation of metal and nonmetal from WPCBs metal concentrated scraps.2.The experimental results of recycle micro-copper powders from WPCBs metal concentrated scraps by electrokinetics show:the optimum condition is:30 g/L PVP,6 mL/L oleic acid,150 g/L H2SO4,80 mA/cm2 and 4 h.Under these conditions,the purity of copper can reach to 99.3%with a particle size of 7.142 μm.The whole structure of the obtained copper powder is dendritic,and the surface of dendrite is clubbed and spherical.This provides the possibility to control the directional growth of particles in the electrochemical process.3.The experimental results of recycle nano-copper powders from WPCBs metal concentrated scraps by electrokinetics show:When the PVP concentration is 6 g/L,electrokinetic can effectively recovery sphere nano-copper powder,and the purity and particle size of nano-copper is 99.53%and 489.7 nm respectively.As an additive,when the[BSO3HMIm]HSO4 concentration is 40%,the structure of the obtained nano-copper is dendritic,and the purity and the mean particle size of nano-copper are 96.75%and 544.2 nm.PVP controls the morphology and particle size of nano-copper powder through the group of N-C=O,and[BSO3HMIm]HSO4 by the lower surface tension and the hydrogen bonds formed because of liquid.