锌电积用Al基“反三明治”结构复合多孔Pb合金阳极的制备与电化学行为研究

The porous Pb anode prepared previously by applicants could decrease the anodic potential and lead contamination of the cathode product, produce less anode slime as well as reduction of anode metal consumption. Therefore, the porous Pb anode could replace traditional flat anode and serve in the zinc electro-winning industry. However, the mechanical strength and electrical conductivity of porous anode will be a problem..This program puts forward "Anti-Sandwich Structure" composite porous anode with Al core, in order to improve the electric conductivity and mechanical performance of lead-based porous anode. This program also develops and studies the "metal salt electroless plating-metal bath-counter-gravity infiltration" process, to revea the growth kinetics of Pb coatings on Al, and realizes the combination of Pb and AL with low resistance and high strength. Therefore, the high strength and high conductivity of Al and the excellent electrochemical properties of porous Pb could be fully used. Simultaneously, the research method and related theories of the electrochemical behavior of porous Pb anode is established, and the electrochemical behavior of Al-based porous Pb alloy anode is revealed..The program achievements could promote the industrial application of porous Pb alloy anode in Zinc hydrometallurgy, reduce the anode material costs and energy consumption. The project achievements could also be applied in the hydrometallurgical process of other nonferrous metals and the electro-plating industry. Therefore, the energy saving in the nonferrous metal electrodeposition process in sulfuric acid system could be achieved.

申请人前期研究的多孔Pb阳极具有降低阳极电位与阴极锌含Pb量、减少阳极泥与阳极金属用量的优点，有望取代锌电积工业的传统平板阳极。但是，还需要突破多孔Pb阳极机械强度与导电性下降的瓶颈。.本项目提出以金属Al为"反三明治"结构的芯板，研制Al基"反三明治"结构复合多孔Pb阳极，解决多孔Pb阳极强度低和导电性差的问题；提出并研究"熔盐化学镀-金属浴-反重力渗流铸造"工艺，揭示Al表面Pb镀层的生长动力学过程，实现Al与Pb的低阻高强结合，以同时发挥Al基板高强、高电导特性与多孔Pb优异的电化学性能；同时，建立多孔Pb阳极电化学行为研究方法及其相关理论，揭示Al基多孔Pb合金阳极的电化学行为。.项目成果可指导复合多孔Pb合金阳极的在湿法炼锌过程的工业应用，降低阳极原料成本和节约电耗。项目成果还可应用于其它有色金属的湿法提取和电镀工业，实现硫酸体系下有色金属电沉积过程的节能降耗。

为了解决多孔Pb阳极强度低和导电性差的问题，本项目提出了以金属Al为芯板的“反三明治”结构复合多孔阳极，并从阳极的制备工艺、阳极合金成分和结构的优化，以及多孔阳极的电化学性能和应用技术方面开展研究。. 1）研发了Al表面“熔盐化学镀-金属浴”直接镀Pb工艺，确定了化学镀Pb熔盐的主要成分为PbCl2-NaCl-CaCl2，获得了化学镀Pb的优化工艺参数：过热度为60度，Al片浸入时间为2.5min；加入3-4%辅盐SnCl2时，可以获得Al与Pb镀层最大的结合强度（2.1 MPa）；金属浴成分为Pb-Ag，浴温度400度，金属浴时间10s，金属浴次数3。. 2）结合反重力渗流铸造工艺，获得了Al/Pb-Ag夹层平板电极。相较Pb-Ag阳极，Al/Pb-Ag阳极屈服强度和抗拉强度分别提高了77.39%和57.18%，阳极重量减少10.78%。Al芯的加入使得阳极槽电压降低30 mV，电流效率提高约1%，能耗减少约50 kWh/t-Zn。. 3）开发了“反重力渗流法预成型半整体发泡”技术与相关设备，制备了Pb基反三明治结构复合多孔阳极。渗流铸造工业最优条件为：渗流室预热温度300度，熔体温度500度，压力0.06MPa。Pb基复合多孔阳极相较多孔阳极具有更高的机械强度，更高的电导率和更低的阳极电位。对该复合多孔阳极的结构进行了优化，Pb基的厚度为2mm，多孔层孔径为1.25-1.43mm，提出了复合多孔阳极电流分布的分布传输线模型。. 4）优化了多孔Pb阳极服役电解液的Mn2+浓度，当电解液中Mn2+为3g/L时，相较平板阳极，多孔阳极腐蚀速率低51.5%，阴极锌含Pb量低62.7%，吨锌能耗降低52 kWh/t-Zn。开发了多孔阳极表面阳极泥的无损溶蚀技术。在工业现场进行了低锰浓度电解液工业锌电解试验(Mn2+浓度为0.3-0.5g/L)，发现相较平板阳极，多孔阳极可以降低阳极电位85mV，腐蚀速率降低71%，阴极锌中Pb含量降低52.5%，电解电耗降低76kWh/t-Zn。. 项目提供了一种金属基复合多孔Pb阳极，可以降低锌电积工业的能耗，节约阳极原料消耗和成本，减少阳极腐蚀，提高阴极产品质量，具有重要的工业意义。