| 摘要 |
PURPOSE:To recover a high-purity divalent Cu ion chelating agent from chemical Cu plating waste liquor by making the waste liquor strongly alkaline, adding slaked lime to dissociate Cu-chelate bond and precipitate Cu ions as copper hydroxide and copper carbonate, filtering the liquor, and making the filtrate acidic. CONSTITUTION:Chemical Cu plating waste liquor contains divalent Cu ions, a divalent Cu ion chelating agent, a divalent Cu ion reducing agent, etc., so caustic soda is first added to adjust the liquor to strong alkalinity of pH>=11. Ca(OH)2 such as slaked lime is then added in excess of the contained Cu ions to convert Cu-EDTA bond into Ca-EDTA bond by dissociation, and copper hydroxide and unreacted Ca(OH)2 precipitated are filtered. The filtrate is adjusted to 4-5pH with acid to dissociate the Ca-EDTA bond and precipitate CaSO4, which is then filtered. The filtrate is further adjusted to 1.5-2pH to precipitate EDTA, and the EDTA is recovered by filtration. The EDTA-free filtrate is neutralized to 7pH with caustic soda and drained. |
