Preparation Of Conductive Composites Cathode And Its Application In Copper Electrorefining

Electrolytic refining is one of the effective methods for preparing copper withhigh purity.The cathode plates intraditional electrolytic refining cell are mainly titanium seed plates or stainless steel plates,which areexpensive,complicated in machining,moreover,the deposited copper on cathode is difficult to peel off.In order to solve the above mentioned problems,this paper attends to print cathode by using 3D printing technology,and focuses on the preparation of conductive 3D printing consumables.Multi-walled carbon nanotubes(MWCNTs)and expanded graphite(EG)were used as conductive fillers,and thermoplastic polyurethane(TPU)was used as matrix material.Conductive 3D printing consumables were prepared by melt blending method,the electrical conductivity and mechanical properties of the composites were studied.EG/MWCNTs/TPU was applied to the experiment of electrolytic refining copper to explore the effect of process conditions on the quality of copper plating on plastic cathode plates.In this paper,MWCNTs/TPU 3D printing consumables were prepared by melt blending of MWCNTs and TPU,and the MWCNTs content in the composites was adjusted.The electrical and mechanical properties of the composites were investigated by four-probe semiconductor test and universal testing machine.It is found out that with the increase of MWCNTs content,the electrical conductivity of composites has been significantly improved,while the tensile strength and elongation at break of composites have decreased significantly,and the mechanical properties of composites have deteriorated.The optimum addition amount of MWCNTs was 10 wt.%,the electrical conductivity was 1.8006 Ω·cm,and the tensile strength was 6.95 MPa.In order to further improve the conductivity of the composite material,EG/MWCNTs/TPU 3D printed conductive consumables were prepared by using EG and MWCNTs two-component mixed conductive filler.Through the performance test of EG/MWCNTs/TPU composites,it is found that the resistivity of composites is effectively reducedwith the addition of EG,and the tensile strength and elongation at break increase first and then decrease.This is probably because EG promotes the matrix effectively,which facilitate the formation of a conductive network and distribution of conductive fillers.Finally,EG(9wt%)/MWCNTs(10wt%)/TPU(81wt%)was selected as the optimal condition to prepare 3D printing consumables.The electrical conductivity of the composite was 0.23 Ω·cm and the tensile strength was 6.99 MPa.EG/MWCNTs/TPU was used as a 3D conductive printing consumable,a conductive plastic cathode plate is printed.Moreover,the electrolytic copper electrolysis cell for laboratory use was designed and printedby using pure acrylonitrile-butadiene-styrene copolymer as 3D printing consumables.Copper was deposited on cathode by using galvanostatic electrolytic refining experiment.It has been found that the surface of the copper plateson the conductive plastic cathode plate is flatter and easier to peel off than that on conventional titanium seed plate and stainless steel cathode plate.In order to investigate the feasibility of industrial application of conductive plastic cathode plates,the effects of conditionsin electrolytic refining process on the quality of copper plating were studied,includingconcentration of anhydrous copper sulfate,current density,electrolysis temperature,pole spacing,and the component and concentration of additives to obtain copper plating layers of different qualities.Morphology and structure analysis were carried out by SEM and XRD,it was found that with the concentration of anhydrous copper sulfate of 90-110g/L,the current of 110-130 mA,the electrolysis temperature of 50-60°C,the pole spacing of 4-5cm,and the concentration of 15mg/L,ethyl-3-methylimidazolium chloride as an additive,the surface of the copper plating layer was flat and easily peeled off,and the copper content in the cathode copper of the ICP test is as high as 99.97989%.