METHOD FOR REGENERATION OF NITRATE-AMMONIUM SOLUTION OF REMOVING CADMIUM COATINGS Russian patent published in 2021 - IPC C25F7/02 C25C1/16 C23C22/86 

FIELD: chemical industry.

SUBSTANCE: invention relates to a method for regenerating a nitrate-ammonium solution of removing cadmium coatings from parts by extracting cadmium ions from it using electrochemical treatment at a temperature of 20-45°C in an electrolyzer with a copper cathode and a platinized niobium anode or a platinized titanium anode. The method is characterized by the fact that the electrochemical treatment is carried out in two stages, and at the first stage, cadmium is electrodeposited directly from a nitrate-ammonium solution of removing cadmium coatings in an electrolyzer without separating the cathode and anode spaces at cathode current density of 10-30 A/dm² and anode current density of 2-10 A/dm², and at the second stage, electrodeposition is carried out in a two-chamber electrolyzer with a cation-exchange membrane, in the cathode chamber of which there is a solution of ammonium sulfate with a concentration of 20-50 g/l, and in the anode chamber there is still water, in which the parts are washed after the first stage, while the cathode and anode current density is 2-15 A/dm².

EFFECT: proposed method, in contrast to the known ones, eliminates the formation of liquid waste containing cadmium compounds, reduces energy consumption and equipment costs. It can be carried out on the cadmium plating section without any changes in the arrangement of the baths.

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