Preparation and performance of 3D-Pb anodes for nonferrous metals electrowinning in H2SO4 aqueous solution
(1. School of Metallurgical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, China;
2. Guangdong Institute of Rare Metals, Guangzhou 510650, China;
3. State Key Laboratory of Rare Metals Separation and Comprehensive Utilization, Guangzhou 510650, China)
2. Guangdong Institute of Rare Metals, Guangzhou 510650, China;
3. State Key Laboratory of Rare Metals Separation and Comprehensive Utilization, Guangzhou 510650, China)
Abstract: The effects of Pb2+ concentration, current density, deposition time and temperature on Pb deposit structure were investigated. In lower Pb2+ concentration (~0.15 mol/L), carambola-like 3D-Pb structure was constructed, while in higher Pb2+ concentration (≥0.30 mol/L), Pb deposits exhibited pyramid-like structure. Furthermore, the oxide layer and anodic potential of carambola-shaped 3D-Pb (Cara-Pb) and pyramid-shaped 3D-Pb (Pyra-Pb) anodes were investigated and compared with those of fresh Pb anode. After 72 h galvanostatic electrolysis (50 mA/cm2) in 160 g/L H2SO4 solution, the oxide layer on Pyra-Pb was much thicker than that on Cara-Pb and Pb anodes, which remarkably relieved intercrystalline corrosion of the metallic substrate. Additionally, the oxide layer on Pyra-Pb anode presented a larger surface area and higher PbO2 content. Hence, Pyra-Pb anode showed a 40 mV lower anodic potential compared to Cara-Pb and Pb anodes. In sum, Pyra-Pb anode had a potential to decrease energy consumption and prolong the life span of traditional Pb anode.
Key words: electrochemical deposition; 3D-Pb structure; growth mechanism; oxide layer; anodic potential