Recovery of metal from solution
AssigneeEastman Kodak Company
InventorsNicholas J. Dartnell, Christopher B. Rider
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Abstract
Recovery of silver from a photographic fixer solution in an electrolytic cell is controlled so as to maintain a high current efficiency whilst minimizing unwanted side effects. The difference between plating voltages when operating at two different current levels is monitored, and the plating current adjusted in response to detection of a maximum of said differences. Such control allows the cell to be operated continually at high current efficiency in response to changing chemical conditions within the cell.
Claims13
A method of controlling the recovery of metal from solution in an electrolytic cell containing a cathode and an anode by deposition onto the cathode thereof as a plating current flows through the cell between the cathode and the anode under the action of a plating voltage thereacross, comprising the steps of:
- repeatedly monitoring (a) the difference between voltages measured across the cathode and anode at a first current level and at a second current level, or (b) the difference between currents flowing between the cathode and anode at a first voltage level and at a second voltage level;
- and modifying said plating voltage and/or plating current in response to change in said difference arising from variation in the concentration of metal in the solution, thereby to control recovery of the metal from the solution.
An apparatus for controlling recovery of metal from solution, wherein the solution is contained in an electrolytic cell having an anode and a cathode, wherein the metal is arranged to be deposited onto the cathode as a plating current flows through the cell between the cathode and the anode under the action of a plating voltage thereacross, comprising means for repeatedly monitoring (a) the difference between voltages measured across the cathode and anode at a first current level and at a second current level, or (b) the difference between currents flowing between the cathode and anode at a first voltage level and at a second voltage level;
- means for modifying said plating voltage and/or plating current in response to said difference;
- and means for controlling operation of the monitoring means and the modifying means.
Dependencies are inferred from the claim text.