PROCESS OF RECOVERY OF IRON-COPPER-CHLORIDE PICKLING SOLUTION Russian patent published in 1999 - IPC

FIELD: manufacture of printed circuit boards by etching. SUBSTANCE: process of electrochemical recovery of iron-copper-chloride pickling solution consists in preliminary treatment of catholyte that amounts to 10-25% of solution volume brought out for recovery with hydrochloric hydrazine in amount of 350-400 g per 1.0 kg of etched copper. In this case concentration of potassium chloride in starting pickling solution is reduced to 120-130 g/l to avoid precipitation of double salt CuClCuCl•2KCl2KCl. After electrolytic recovery of copper with cathode density of current 8-10 A/sq.dm catholyte is mixed with due portion of solution fed for recovery in anode space where iron chlorine is oxidized to chloride iron with anolyte agitation with the aid of air bubbling. EFFECT: decreased energy consumption thanks to diminished voltage across electrodes and increased cathode current yield.