Recovering dissolved metal from waste produced when manufacturing phthalocyanine pigments, etc. by adding strong acid, adding complex to precipitate metal and filtering off precipitate

摘要

Metal dissolved in acidic and/or basic waste from an organic chemical process is recovered by adding a strong acid to adjust and maintain its pH to 0 - 4. Then a complex is added to precipitate the metal and this is allowed to settle. The solution is filtered to produce an acid sludge including the metal and a filtrate with a reduced metal content. Preferred Features: Preferably sulfuric acid is added to reduce the pH to 3 and sodium dimethyldithiocarbamate is added to precipitate the metal. Then a potential <= 150 - 300 mV is applied via a silver/silver chloride electrode. Ferric chloride in the solution assists settling of the precipitate before it is separated using a filter press. The metal recovered is iron, cobalt, nickel or copper.