Extraction of copper from waste etching liquid in chloride system circuit board

Abstract

The extraction of copper from waste etching solution of circuit boards in chloride system includes: a electrolysis device containing a electrolytic vessel divided into cathode region and anode region by diafragm material, addition of waste etching solution into the cathode region, addition of chloride salts and elementary substance or compound accessory ingredient which reacts with chlorine as conducting medium, deposition of copper on the cathode and reaction of accessory ingredient with chlorine to form stable chloride in the anode region. Because the individual electrolytic vessel is divided into cathode region and anode region by slightly permeable diafragm, the electrodeposition of copper will progress equably in a large range of cathode current density, corresponding reactions of chlorine from electrolysis with added Mg, Al, Zn, Fe etc. will also occurs in the anode region avoiding the emission of chlorine above the anode.

Description

technical field [0001] The invention relates to a method for extracting copper, in particular to a method for extracting copper by electrodeposition from waste etching solution of circuit boards in a chloride system. Background technique [0002] The non-renewable waste etching solution of the chloride system circuit board contains about 100g to 120g of copper per liter. Only Guangdong Province produces about 5,000 tons of copper in this type of waste etching solution every month. The copper is recycled for recycling Utilization has very significant economic value, and in the existing method for extracting copper in the waste etching solution of this chloride system circuit board, it is mainly in the electrolyzer that is separated into cathode area and anode area by diaphragm material, The anode terminal and the cathode terminal are respectively connected to the positive terminal and the negative terminal of the DC output power supply. After the circuit is connected, the was...

AI Technical Summary

Problems solved by technology

[0002] The non-renewable waste etching solution of the chloride system circuit board contains about 100g to 120g of copper per liter. Only Guangdong Province produces about 5,000 tons of copper in this type of waste etching solution every month. The copper is recycled for recycling Utilization has very significant economic value, and in the existing method for extracting copper in the waste etching solution of this chloride system circuit board, it is mainly in the electrolyzer that is separated into cathode area and anode area by diaphragm material, The anode terminal and the cathode terminal are respectively connected to the positive terminal and the negative terminal of the DC output power supply. After the circuit is connected, the waste etching solution in the electrolytic cell is electrolyzed. At the initial stage of electrification, the amount of copper deposited on the cathode is very small. After a long period of time, after the temperature of the waste etching solution is significantly increased due to the Joule heating effect, the copper precipitation speed at the cathode is accelerated until the copper in the waste etching solution is almost completely precipitated. At this time, if it is assumed that the copper ions in the waste etching solution are all The divalent valence state exists, and its Faraday DC efficiency is below 70%. At the same time, the corresponding chlorine gas is precipitated on the anode. According to theoretical calculations, every 100kg of copper electrodeposited, 111.6kg of copper is deposited on the anode. Chlorine gas has a standard volume of 35.26m 3 , to properly handle such a large amount of chlorine without causing secondary pollution to the environment is a very costly investment, and there is also the problem of waste liquid treatment

To address these problems, Chinese patent application ZL97121340.2 discloses a regenerated CuCl 2 The device and method of etchant are mainly carried out in two electrolytic tanks, the first electrolytic tank reduces divalent copper to monovalent copper, and the second electrolytic tank reduces monovalent copper to copper. At the same time, it must also add a solution of higher concentration of monovalent copper ions to the anode area of ​​the two electrolytic cells at the same time to maintain the anode reaction of the oxidation of monovalent copper to divalent copper, and at the same time it needs to fill nitrogen above the cathode area (N 2 ) to prevent the oxidation of monovalent copper into divalent copper, add 10 to 25 ppm of electroplating additives to the cathode area, although it can easily obtain copper chloride (CuCl 2 ) regeneration solution to make CuCl 2 The etchant can be recycled and avoid the generation of toxic waste gas chlorine, but it is only for CuCl 2 The etchant is regenerated, and the non-renewable waste etching solution cannot be processed, so the metal copper cannot be recycled, and the waste etching solution always exists in the regeneration treatment, which makes the expensive and scarce metal copper a waste

At the same time, Chinese patent ZL00117945.4 discloses a method and system for recovering and removing copper from liquids, which is mainly for the treatment of microetches of sulfate systems containing various organic complexing agents. Oxygen is precipitated in the treatment of the system without the problem of toxic chlorine gas treatment, that is to say, it only solves the micro-etching agent of the sulfate system for treatment, and at the same time, the patent application mainly deals with the micro-etching of the sulfate system in the anode agent, its di-copper ions or monovalent copper ions are deposited on the cathode by passing through the cationic membrane, which invisibly reduces the direct current Faraday efficiency and greatly increases the cost of treatment

Images