The copper-containing etching waste liquid generated in PCB production includes acidic etching waste liquid and alkaline etching waste liquid. At present, the main treatment methods for alkaline copper-containing etching waste liquid include chemical precipitation method, liquid membrane separation method, electrolysis method, and solvent extraction.
Modern wet copper smelting mainly refers to the leaching-extraction-electrowinning method. Extraction is the key step in modern wet copper smelting. The copper ore is treated with sulfuric acid or ammonia to obtain an acidic or alkaline leachate containing metal ions. By selecting a suitable extractant and utilizing the complexation between the extractant and the metal ions, the metal ions in the aqueous phase enter the organic phase, and After further stripping, metal ions are regenerated and metallic copper is deposited.
Throughout the industrial process, extractants are key factors. At present, in the hydrometallurgical extraction of copper from non-ferrous metals and the regeneration and recovery of copper from etching solutions, extraction agents have been widely used, which uses the difference in distribution coefficient K between copper and impurity elements to achieve the separation of copper and impurity elements. The main chemical equation is: 2RH+Cu2+=CuR2+2H+ (RH represents the extraction agent).
The extraction agent for extracting copper from alkaline aqueous solution can use an extraction agent whose main components are β-diketone and diluent sulfonated kerosene. β-diketone is very weakly acidic and has very little solubility in alkaline solution, so it is often used In alkaline solution or ammonia solution, copper is extracted through liquid-liquid ion exchange, and β-diketone has the advantages of high selectivity and repeated use, so it is widely used in copper hydrometallurgy and alkaline etching solution regeneration. It is often used to selectively extract Cu2+ in reuse systems. Sulfonated kerosene, also known as No. 260 solvent oil, is made from sulfonated kerosene. This product is characterized by a uniform and slow evaporation rate and low aromatic hydrocarbon content. It has no odor, no residue when evaporated, and is not easily oxidized by heat. It is the most common diluent.