Preparation And Properties Of Manganese Ion Co-deposited Lead Dioxide Composite Anode

The Pb-(0.75?1.0)wt%Ag alloy as anode material are being widely used in zinc electrowinning industry at present.However,it has some shortcomings,such as high oxygen evolution overpotential,poor electroconductivity,low mechanical strength,and it can reduce the quality of cathode zinc products caused by anodic dissolution.Based on lead dioxide and manganese dioxide's higher electrocatalytic activity,the Pb-Sn-Sb/?-PbO2/(?-PbO2-MnO2)composite anode was prepared on the surface of Pb-0.6wt%Sn-0.6wt%Sb alloy substrate by the composite electrodeposition technology in this paper.In this study,the dynamic behavior of PbO2 and MnO2 codeposition was studied,the deposition conditions of(?-PbO2-MnO2)layer were optimized,the cell voltage,current efficiency,power consumption and accelerated corrosion life of composite anodes were measured in the simulated zinc electrowinning system.The main research results are as follows:The influences of concentration of Mn(NO3)2,HNO3,Pb(NO3)2 and solution temperature on PbO2-MnO2 codeposition were studied by cyclic voltammetry using rotating disk electrode.The results indicate that there was a competitive relationship between the deposition of PbO2 and the deposition of MnO2.HNO3 could promote the formation of PbO2 and MnO2 simultaneously,but excessive acid could inhibit the deposition process.Higher temperature was beneficial to the formation of MnO2.The amount of deposited PbO2 also increased with the rise of temperature.However,the temperature exceeded 40 ?,the amount of deposited PbO2 would decrease slightly due to partial hydrolysis of Pb2+.The experiments concerning the effects of rotation rate of the electrode on the codeposition process of PbO2 and MnO2 indicate that the behavior of PbO2 and MnO2 codeposition process was mainly controlled by the electrochemical process.The electrochemical performances of Mn2+ co-deposited PbO2 composite anode,such as oxygen evolution electrocatalytic activity,corrosion resistance and charge transfer resistance,were measured in the simulated zinc electrowinning system.And the results indicate that the optimum conditions of(?-PbO2-MnO2)deposition layer were Mn(NO3)2:70 g·L-1,current density:15 mA·cm-2,bath temperature:40 ?.Pb-Sn-Sb/a-PbO2/(?-PbO2-MnO2)composite anode had higher electrocatalytic activity,lower overpotential of oxygen evolution and better reversibility of electrode reaction than Pb-Sn-Sb/a-PbO2/?-PbO2 composite anode,The cell voltage,current efficiency,power consumption and accelerated corrosion life of composite anodes were measured in the simulated zinc electrowinning system.Under the current density of 500 A·m-2,the cell voltage of Pb-Sn-Sb/?-PbO2/(?-PbO2-MnO2)composite anode was 2.77 V,which was reduced 0.34 V compared with Pb-0.8wt%Ag alloy anode.The power consumption was 2480.1 kW h/(t·Zn),which wwas reduced 343.2 kW·h/(t·Zn)compared with Pb-0.8wt%Ag alloy anode.The new composite anode shows the remarkable energy-saving effect.The accelerated corrosion life of Pb-Sn-Sb/?-PbO2/(?-PbO2-MnO2)composite anode was 6 h and its service life was 400 days under the general industrial current density of 500 A·m-2.