PROCEDURE OF REGENERATION OF SULFATE CHROMIUM PLATING ELECTROLYTE Russian patent published in 2003 - IPC

FIELD: technology of electrodeposition processes used in mechanical engineering and electronic industry. SUBSTANCE: technical result of invention lies in integration of operations of electrolyte acidic correction and removal of cation of reagent, in increased scattering power and current efficiency with simultaneous reduction of consumption of chromium anhydride and operational voltage across baths. Procedure includes injection of calculated amount of salts of phosphoric acid, precipitation of phosphates of impurities at temperature of 20-25 C, their separation from electrolyte and correction of composition of refined electrolyte. Oxides or hydroxides of metals forming precipitate together with ion SO2-4

are dissolved in electrolyte before injection of phosphates or simultaneously with them, phosphates are precipitated at pH 1.2-1.4 and temperature of 20-25 C, composition of refined electrolyte is corrected by addition of sulfuric acid to it to obtain weight concentrations CrO₃:H₂SO₄ in solution as 100:1, later sulfate residue is separated, ions of trivalent chromium are oxidized to obtain hexavalent chromium in the amount equivalent to 1.0-2.0 per cent by mass of quantity of CrO₃ before regeneration or after it in refined electrolyte. EFFECT: raised efficiency of procedure.