Optimal operational conditions during production of lead-calcium-tin anodes for improve their mechanical properties.

Previous works have shown that a minimum yield strength sigma(0) of 58 MPa for lead-calcium-tin anodes of 6 mm thickness and a nominal composition of 0.7% Ca and 1.3% Sn are required to avoid early deformations and distortions during their operation in copper electrowinning cell. This sigma(0) value for the anodes is associated with a terminal cold rolling process and a further precipitation hardening prior to their installation in the electrowinning cells. The objectives of the present work are to determine the alloy recrystallization temperature according to Ca and Sn contents, the maximum cold rolling temperature and the aging time required to obtain the desired mechanical quality. The results indicate that recrystallization temperature ranges between 120 and 150 degrees C, according to the anode composition. To reach the desired deformation and precipitation hardening and consequently a yield strength of 58 MPa, the maximum cold rolling temperature is 45 degrees C and the minimum aging time, 30 days.