METHOD OF RECOVERY OF HYDROCHLORIC ACID FROM USED ETCHING SOLUTIONS Russian patent published in 1996 - IPC

FIELD: electrochemical etching. SUBSTANCE: invention refers to method of recovery of hydrochloric acid from used etching solutions containing high precentage of _FeCl and organic surface-active substances in addition to unused etching acid HCl and FeCl 12

. Method consists in preliminary cleaning of used etching solution from impurities of organic substances, in electrochemical oxidization of bivalent iron into trivalent one which is conducted in electrolyzer under action of monatomic chlorine released on anode, in subsequent concentration of solution and hydrolysis of FeCl ₃ which is performed with 6-10-fold excess of quantity of water as compared with stoichiometric quantity to produce hydrochloric acid with concentration from 20 to 30 per cent by mass which is directed later for production purpose. EFFECT: production of hydrochloric acid of specified concentration directly at stage of hydrolysis with subsequent return of it into industry. 6 cl, 1 dwg, 1 tbl