Study of precipitation hardening in lead calcium tin anodes for copper electrowinning

A suitable yield stress for Pb anodes with 0·07%Ca and 1·3%Sn of 6 mm thickness for copper electrowinning is achieved by means of deformation and precipitation hardening processes, their useful life being dependent on this yield stress. The objective of the present work was to optimise the precipitation hardening, by finding the best cooling conditions for the anodes in the moulds and the optimum hot rolling temperature. The results show that increasing the cooling rate of ingots beyond the rate of natural cooling enhances the precipitation hardening. At least 45 days of aging are necessary to reach stable conditions for the precipitation hardening, with precipitates formation as CaSn 3 . The hot rolling temperature does not have a significant effect on the precipitation hardening of the anodes.