Deformations in lead–calcium–tin anodes for copper electrowinning

The objective of this work is the study of mechanical and metallurgical characteristics of various lead–calcium–tin anodes for copper electrowinning, to determine a relationship between properties and distortions during their operation in the cell in order to set quality standards for new anodes that guarantee absence of distortions. The mechanical tests consist of measurement of hardness, σo yield strength between room temperature and 80 °C by means of compression tests, and tensile strength through tensile tests. The metallurgical characterization is aimed at determining the size and shape of the grains. It is observed that the anodes that do not undergo deformation in the cell show throughout the temperature range and during equivalent time of use an average yield stress higher than that of those anodes that undergo deformation. This can be explained by the fact that, in the case of the first anodes, the final temperature of rolling corresponds to cold rolling and, consequently, deformation hardening occurs during their fabrication. The deformed anodes, however, were hot rolled.