METHODE ET DISPOSITIF DE CONTROLE DE RECUPERATION DU ZINC DES BAINS D'ELECTROLYSE

ABSTRACT OF THE DISCLOSUREA method is disclosed for controlling a process for the recoveryor zinc from zinc sulfate electrowinning solutions containing concentrationsof impurities. The disclosed method includes the steps or establishing atest circuit comprising a test cell, a sample or electrowinning solution, acathode, an anode and a reference electrode immersed in said sample, a vari-able voltage source and measuring means electrically connected to the elec-trodes. A potential is applied to the electrodes in the test cell to obtaina predetermined potential between the cathode and the reference electrode.The potential is decreased from the predetermined value at substantiallyzero current, the decreasing potential is measured, and the decreasing ofthe potential is terminated at a value corresponding to the point at whichzinc starts to deposit on the cathode and the measured electrode currentdensity increases rapidly from a value or substantially zero for furthersmall decreases in potential. The activation over-potential is determinedand is related to the concentration of impurities in the sample, whereuponthe process for the recovery of zinc is adjusted to obtain optimum zinc re-covery.