Abstract
The effects of varying periods of open-circuit on the performance (operating potential, corrosion rate, scale and mud generation) of lead-silver alloy anodes in electrolytes containing 170 g/L sulfuric acid in the absence and presence of manganese ions were evaluated in a series of long term (56 days) tests. Anodes were initially supplied with current for three days and then open circuited for periods of three, six or twelve hours. Current was then re-applied for three days and the process repeated. These on-off cycles were repeated up to five times. After the last on-off cycle, cells were supplied continuously with current for the remaining period. Operation of anodes in acid only under these conditions resulted in decreased anode potentials compared to normal continuous current operation. However, addition of 5g/L manganese to the electrolyte produced results which showed no effect of periodic interruption on the operating potential, increased the corrosion rate slightly, reduced the rate of production of cell mud and reduced the rate of formation of anode scale. A possible correlation between the degree of adherence of anode scale, corrosion rate and mud generation rate are discussed as is the practical implications of reapplication of current after an interruption.