Regeneration of phosphatizing bath overflow or rinse water involves passage through a weakly acidic ion-exchanger followed by a second weakly acidic ion-exchanger, a strongly acidic ion-exchanger or a reverse osmosis apparatus

摘要

Following passage of zinc-, manganese- and nickel-containing overflow and/or rinse water from use of an acid aqueous phosphatizing solution through a 15%-neutralized weakly acid ion-exchanger so as to adjust the pH to 2.5-6, the overflow and/or rinse water is then passed through either a second weakly acidic ion-exchanger whose acid groups are 50-100% neutralized by alkali metal ions or a strongly acidic ion-exchanger or a reverse osmosis apparatus. Working up of zinc-, manganese- and nickel-containing aqueous solutions comprising overflow and/or rinse water from use of an acid aqueous phosphatizing solution containing phosphate ((PO4)3-), zinc, manganese and nickel ions at 3- 50, 0.2-3, 0.1-3 and 0.01-2.5 g/l respectively and optionally also other ions and/or an accelerator involves passage over a 15%-neutralized weakly acid ion-exchanger to give a pH of 2.5-6 and is followed by passage through either (1) a second weakly acidic ion-exchanger whose acid groups are 50-100% neutralized by alkali metal ions; (2) a strongly acidic ion-exchanger; or (3) a reverse osmosis apparatus.