Study On Recovery Of Copper From PCB Waste By Ion-exchange Membrane Electrolysis

The recovery of copper from PCB（Printed Circuit Board）waste materials can not only make full use of the resources,but also effectively solve the pollution problems of waste water containing copper.In this paper,the ion-exchange membrane electrolyzer was used to carry out the recovery experiment.The copper was obtained by cathodic deposition,and the PCB was treated by recycling the etching solution at the anode.Electrolytic determination of cathodic polarization curves and different Cu²⁺/Cl^-ratio of electrolyte electrolysis showed that when the chloride solution was electrolyte,cathodic deposition of copper reduction with Cu²⁺ to Cu+ was the main reaction.Cu²⁺/Cl^-was exceeded 1:2.3,the current efficiency can reach above 95%.Single factor experiments indicated that the optimal process conditions of recycling waste pretreatment PCB: temperature of 45 ℃,stirring speed of 300-400 r/min,reaction time of 5 h,solid-liquid ratio of 10 g/50 ml.Experimental results showed that the optimal process conditions of single factor of anodic oxidation regeneration: temperature of 40 ℃,current density of 100-200 A/m2,the electrode area ratio of 2:1,stirring speed of 100 r/min,reaction time 2 h.U nder the optimized conditions,the liquid was recycled,and the regenerated etching solution was used to dissolve the metal copper.Finally,the enriched solution was obtained.It was found that the Cu²⁺/Cl^-ratio in solution can reached 1:2.22 after 3 cycles,the corrosion resistance of the etching solution decreased greatly and the copper dissolving capacity was lost.The mechanism research shows that the dissolution of copper was controlled by surface reaction.It was deduced by formula that increasing Cl^-concentration can improve the concentration of copper in solution and increase the treatment capacity.The single factor test and orthogonal test were carried out to obtain the optimum conditions of copper cathode.The results were the temperature of 35 ℃,current density of 250 A/m2,Cu²⁺ concentration of 75 g/L and the stirring speed of 100 r/min.Under the optimized conditions of electrodeposition for 2 h,the current efficiency was 97.73%,the energy consumption was 2.4157 k Wh/kg,the cell voltage was 2.80 V and the membrane potential was 0.423 V.The results indicated that the current density has the greatest influence on the tank pressure and current efficiency in all the factors.From the SEM diagram,we can conclude that the influence of current density,temperature and agitation on the morphology of electrodeposited copper was obvious.Increasing the temperature and the current density without stirring was not conducive to the formation of crystalline and fine sedimentary layers.XRD analysis showed that the X diffraction peak of the cathode copper sheet was mainly the crystalline pattern of（111）surface,and the characteristic peaks of copper besides the copper peaks were Cu²⁺1O.This is due to the oxidation of the sample during the test and th e sample preparation process.The amplification test and repeatability test were carried out on the electrolytic test.The results showed that the tank pressure was 3.76 V,the anode potential was 1.06 V,the cathode potential was 0.52 V,the current efficiency was 87%,and the energy consumption was 3.64 k Wh/kg.The average deviation of the current efficiency was 1%,and the relative deviation was 1.15%.The average deviation of energy consumption was 0.125 k Wh/kg,and the relative deviation was 3.48%.At the end of the electrolytic copper scrap recycling PCB market prospect and economic cost were analyzed.Compared with the traditional method of recycling,the technology of waste etching solution and PCB electrolytic copper recovery was no pollution,waste water treatment and resource recovery advantages.