Abstract: A method for controlling the electro-deposition of metal from an aqueous electrolyte containing two organic polarizing agents is disclosed. The method requires measuring the nucleation overpotential, the plating overpotential, and the difference between these potentials. By relating these measurements to predetermined values, optimum process control can be obtained by changing the concentration of the various organic polarizing agents in the process electrolyte.

Abstract: A method and apparatus for effecting periodic current reversal in metal electro-deposition processes are disclosed. By using a circuit in which the current always flows in the same direction through a filter reactor, regardless of the current flow through the electro-deposition cell, faster reversal switching times are obtained. The overshoot and AC ripple encountered on current reversal are also decreased.

Abstract: Improvements in the bipolar refining of lead are described, comprising maintaining a high current density controlled at a value such that the anode overvoltage will not exceed the value at which impurities dissolve and which is related to the internal resistance of the cell, together with periodic reversal of the polarity of the current applied to the electrodes. These improvements result in improved cell efficiency and in the formation of strong, coherent lead deposits which are easily stripped by mechanical means.

Abstract: A method and apparatus for controlling a process for the electrodeposition of metals using electrolyte containing concentrations of impurities and addition agents that affect polarization. The method and apparatus include a test circuit comprising a test cell, a sample of electrolyte, a moving cathode, an anode and a reference electrode immersed in said sample, a constant current source and measuring means electrically connected to the electrodes. A controlled low current is applied to the electrodes in the test cell to measure the activation overpotential between the cathode and the reference electrode. The activation overpotential is measured at the point of inchoate deposition of the metal and is related to the concentration of impurities and polarization affecting agents in the sample. The processes for the purification of electrolyte and the electrodeposition of metals are subsequently adjusted in relation to the measured value of the activation overpotential to obtain optimum metal deposition.

Abstract: A method is disclosed for controlling a process for the recovery of zinc from zinc sulfate electrowinning solutions containing concentrations of impurities. The disclosed method includes the steps of establishing a test circuit comprising a test cell, a sample of electrowinning solution, a cathode, an anode and a reference electrode immersed in said sample, a variable voltage source and measuring means electrically connected to the electrodes. A potential is applied to the electrodes in the test cell to obtain a predetermined potential between the cathode and the reference electrode. The potential is decreased from the predetermined value at substantially zero current, the decreasing potential is measured, and the decreasing of the potential is terminated at a value corresponding to the point at which zinc starts to deposit on the cathode and the measured electrode current density increases rapidly from a value of substantially zero for further small decreases in potential.

Abstract: A process for the electrorefining of lead from lead bullion using an aqueous electrolyte containing lead fluosilicate and hydrofluosilicic acid contained in an electrolytic cell, which comprises interposing in the cell between an anode and a cathode one or more electrically unconnected lead bullion bipolar electrodes, allowing electrolysis to proceed to deposit refined lead and recovering said refined lead.