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

PURPOSE: A method for recovering dissolved metals in wastewater effluent from synthesization process of phthalocyanine pigments is provided. CONSTITUTION: 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. Preferably sulfuric acid is added to reduce the pH to 3 and sodium dimethyl dithiocarbamate is added to precipitate the metal. Then a potential ranging from 150 to 300mV 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.