Abstract
Several modifications of lead anode for zinc electrowinning have been studied. The results are summarized as follows;
(1) By using a Pb-Ag-Ca alloy anode, the bath voltage decreased compared with the conventional Pb-1%Ag anode, and the anode potential decreased with increasing in the content of Ca and Ag in Pb-Ag-Ca anodes.
(2) At the beginning of the electrolysis, the amount of the generated gas on the Pb-0.5%Ag-0.6%Ca anodes was larger than that on Pb-1%Ag anodes and the increase in Ca content in the Pb-Ag-Ca anodes caused a larger gas.
(3) The original microstructural features before electrolysis were investigated with the EPMA. In the Pb-0.9%Ag alloy, the fine particles of Ag-rich phase was found to be homogeneously distributed around the Pb grains. In case of the Pb-0.5%Ag-0.6%Ca alloy, the Ag-rich phase was scattered in the grain boundaries.
The content of Ag in the Ag-rich phase of the Pb-0.5%Ag-0.6%Ca alloy was higher than that in the Pb-1%Ag alloy.
In the Pb-0.8%Ca and Pb-0.5%Ag-0.6%Ca alloy, the CaPb3 phase appeared.
