Method for dissolving broken copper powder in copper chloride solution to absorb chlorine
By dissolving copper powder in copper chloride solution, using an ORP meter and a specific gravity controller to detect the status, and combining chemical reaction and separation technology, the problems of excessive chlorine emissions and low purity of copper powder were solved, efficient chlorine recovery and copper powder utilization were achieved, and environmental protection costs were reduced.
Patent Information
- Application Number
- CN202510830662.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-20
- Publication Date
- 2025-10-10
AI Technical Summary
During the manufacturing process of printed circuit boards, the emission concentration of chlorine exceeds the standard and existing methods are difficult to recycle efficiently, resulting in high environmental costs. In addition, the copper powder produced by electrolysis is of low purity and has low recycling value.
Dissolve crushed copper powder in copper chloride solution, detect the solution state with an ORP meter and specific gravity controller, absorb chlorine gas through chemical reaction, and recover high-purity copper ions through cooling crystallization and centrifugal separation, thus achieving efficient absorption of chlorine gas and efficient utilization of copper powder.
The efficient recovery of chlorine and the high-value utilization of low-purity copper powder are achieved, which reduces environmental protection costs and improves the chlorine recovery effect.
Smart Images
Figure CN120754680A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of printed circuit board manufacturing, in particular to a method for dissolving crushed copper powder in a copper chloride solution to absorb chlorine. Background Art
[0002] In the manufacturing process of printed circuit boards (PCBs), chlorine (Cl2) is one of the key by-products of the etching process. When an acidic etching solution (such as the CuCl2 system) or an alkaline etching solution (such as the NH3 / H2O2 system) is used to remove the copper layer in the non-circuit area of the copper clad board surface, copper undergoes an oxidation-reduction reaction with the chloride ions in the etching solution to generate free chlorine gas. For example, the reaction in the CuCl2 etching solution is: 2CuCl2+Cu→3CuCl2, and then CuCl2 further decomposes under acidic conditions to produce Cl2 gas. This process releases approximately 0.5-1.2 cubic meters of chlorine gas for every square meter of double-sided board etched, and its concentration can reach 500-2000ppm, far exceeding the occupational exposure limit (MAC=1mg / m 3 ).
[0003] In the acidic etching solution copper recovery process, a diaphragm separates the etching solution into a positive and negative chambers. The electrolyte in the positive chamber releases chlorine gas due to the oxidation of the positive electrode, while the negative chamber deposits copper plates and some copper powder. The copper powder produced by electrolysis is easily oxidized in the air, resulting in low purity and a significant reduction in its recycling value.
[0004] Both processes are equipped with a caustic solution spray tower (NaOH concentration 10-15%) for final purification of the exhaust gas, ensuring that the emission concentration is below 5ppm. To ensure the emission concentration is below 5ppm, the caustic solution pH value is manually tested and the NaOH concentration is regularly added to maintain 10-15%.
[0005] In response to the defects of the existing technology, this patent provides a method for dissolving crushed copper powder in a copper chloride solution to absorb chlorine. Summary of the Invention
[0006] The present invention aims to provide a method for dissolving copper powder in a copper chloride solution to absorb chlorine, so as to solve the problems in the above-mentioned background technology.
[0007] To achieve the above object, the present invention provides the following technical solution: a method for dissolving copper powder in a copper chloride solution to absorb chlorine, comprising the following steps:
[0008] S1, introducing chlorine gas generated by the electrolytic cylinder or etching machine into a chlorine absorption tower and dissolving it in a CuCl2-CuCl absorption solution;
[0009] S2, the dissolving tank and the chlorine absorption tower keep circulating, and an ORP meter is set in the chlorine absorption tower. When the ORP value rises to the set value after the absorption liquid absorbs chlorine, the ORP meter signal output controls the addition of copper powder into the dissolving tank;
[0010] S3, a specific gravity controller is provided in the dissolving tank to detect the specific gravity of the CuCl2-CuCl solution. When the specific gravity of the CuCl2-CuCl solution rises to the set value, the high-concentration CuCl2 solution is output;
[0011] S4, the high concentration CuCl2 solution is cooled and crystallized, and centrifuged to obtain CuCl2 crystals. The low concentration CuCl2 solution after separation is continuously recycled to the chlorine absorption tower, and the above steps are repeated.
[0012] Preferably, the chemical reaction in the chlorine absorption tower is 2Cu + +Cl2=2Cu 2+ +Cl - .
[0013] Preferably, the set value of the orp is set to 550mv.
[0014] Preferably, the chemical reaction occurring in the dissolving tank is 2Cu 2+ +Cu=3Cu + .
[0015] Preferably, the setting value of the specific gravity controller is 1.22.
[0016] Preferably, the parameters of the high concentration CuCl2 solution in S3 are:
[0017] The specific gravity is 1.20-1.22, and the copper ion concentration is 120g / L-130g / L.
[0018] Preferably, the parameters of the low concentration CuCl2 solution in S4 are:
[0019] The specific gravity is 1.10-1.12, and the copper ion concentration is 60-80g / L.
[0020] The present invention has at least the following beneficial effects:
[0021] (1) The present invention provides a method for dissolving copper powder in a copper chloride solution to absorb chlorine. The material used is copper powder with low recycling value and purity, which is not only energy-saving and environmentally friendly, but also low-cost;
[0022] (2) The present invention provides a method for dissolving crushed copper powder in a cupric chloride solution to absorb chlorine. The method utilizes the chemical reaction principle of cuprous ions and chlorine to treat the chlorine generated by electrolytic copper recovery and etching machines, thereby greatly improving the chlorine recovery effect. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION
[0024] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.
[0025] like Figure 1 As shown in the figure, the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching solution copper recovery process is absorbed by the chlorine absorption tower. The absorption solution of the chlorine absorption tower is CuCl2-CuCl solution (Cu ion concentration is 60-130g / L). The chemical reaction in the chlorine absorption tower is 2Cu + +Cl2=2Cu 2+ +Cl - The dissolving tank and the chlorine absorption tower keep in circulation. The absorption tower is equipped with an ORP meter to detect the ORP value of the CuCl2-CuCl solution. When the CuCl2-CuCl solution absorbs chlorine and the ORP value rises to the set value, the ORP value is set to 550mv. The ORP meter signal output controls the addition of crushed copper powder into the dissolving tank. The chemical reaction in the dissolving tank is 2Cu 2+ +Cu=3Cu + A specific gravity controller is provided in the dissolving cylinder to detect the specific gravity of the CuCl2-CuCl solution (specific gravity is 1.10-1.22). The specific gravity continues to rise as the absorption of chlorine and the dissolution of crushed copper powder continue. When the specific gravity of the CuCl2-CuCl solution rises to the set value (specific gravity setting value is 1.22), the output of high-concentration CuCl2 solution is controlled. The high-concentration CuCl2 solution (specific gravity 1.20-1.22, copper ion concentration 120g / L-130g / L) is cooled and crystallized. After centrifugal separation, the low-concentration CuCl2 solution (specific gravity 1.10-1.12, copper ion 60-80g / L) is continuously reused in the chlorine absorption tower, and CuCl2 crystals are recovered.
[0026] Based on the above technical solutions, the present invention provides the following partial embodiments:
[0027] Example 1
[0028] The specific gravity (relative density) of the CuCl2-CuCl solution in the chlorine absorption tower was 1.05, the copper ion content was 27.19 g / L, and the orp value was 385 mv. The chlorine absorption tower was started to absorb the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching liquid copper recovery process, and the chlorine gas concentration at the outlet of the chlorine absorption tower was recorded.
[0029] Example 2
[0030] The specific gravity (relative density) of the CuCl2-CuCl solution in the chlorine absorption tower was 1.05, the copper ion content was 27.19 g / L, and the orp value was 594 mv. The chlorine absorption tower was started to absorb the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching liquid copper recovery process, and the chlorine gas concentration at the outlet of the chlorine absorption tower was recorded.
[0031] Example 3
[0032] The specific gravity (relative density) of the CuCl2-CuCl solution in the chlorine absorption tower was 1.11, the copper ion content was 69.90 g / L, and the orp value was 378 mv. The chlorine absorption tower was started to absorb the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching liquid copper recovery process, and the chlorine gas concentration at the outlet of the chlorine absorption tower was recorded.
[0033] Example 4
[0034] The specific gravity (relative density) of the CuCl2-CuCl solution in the chlorine absorption tower was 1.11, the copper ion content was 69.90 g / L, and the orp value was 604 mv. The chlorine absorption tower was started to absorb the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching liquid copper recovery process, and the chlorine gas concentration at the outlet of the chlorine absorption tower was recorded.
[0035] Example 5
[0036] The specific gravity (relative density) of the CuCl2-CuCl solution in the chlorine absorption tower was 1.21, the copper ion content was 133.45 g / L, and the orp value was 382 mv. The chlorine absorption tower was started to absorb the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching liquid copper recovery process, and the chlorine gas concentration at the outlet of the chlorine absorption tower was recorded.
[0037] Example 6
[0038] The specific gravity (relative density) of the CuCl2-CuCl solution in the chlorine absorption tower was 1.21, the copper ion content was 133.45 g / L, and the orp value was 598 mv. The chlorine absorption tower was started to absorb the chlorine gas from the electrolytic cylinder and the acid etching machine in the acid etching liquid copper recovery process, and the chlorine gas concentration at the outlet of the chlorine absorption tower was recorded.
[0039] The chlorine gas concentration at the outlet of the chlorine absorption tower recorded in the above Examples 1-6 is as follows:
[0040]
[0041]
[0042] Comparing Example 1 with Example 2, Comparing Example 3 with Example 4, and Comparing Example 5 with Example 6, it can be seen that the ORP value of the CuCl2-CuCl solution has a great influence on the chlorine treatment of the chlorine absorption tower. When the ORP value is higher than 590mv, the outlet chlorine concentration is above 2800ppm.
[0043] By comparing Example 1, Example 3 and Example 6, it can be seen that under the condition of the same ORP value, the higher the copper ion content, the better the chlorine treatment effect.
[0044] In the above Examples 1-6, when the etching machine and the electrolytic cylinder are working, the chlorine absorption tower is turned on to absorb chlorine, and the copper chloride solution in the chlorine absorption tower and the copper chloride solution in the crushed copper powder dissolving tank are kept in a circulating state using a pump. The absorption tower is equipped with an ORP meter. When the ORP value of the copper chloride solution in the absorption tower is higher than the set value of 550mv, the ORP meter outputs a signal to control the addition of crushed copper powder into the dissolving tank and turn on the dissolving tank stirring device; when the ORP value is lower than 350mv, the addition of crushed copper powder is stopped. The crushed copper powder dissolving tank is equipped with a hydrometer. When the specific gravity of the copper chloride solution in the dissolving tank is higher than the set value of 1.22, the hydrometer outputs a signal to control the pump to work, pumping the low-concentration copper chloride solution from the concentrated cooling crystallization-centrifugal separation device into the dissolving tank, and the high-concentration copper chloride solution overflows from the overflow port to the concentrated cooling crystallization-centrifugal separation device. After being processed by the concentration cooling crystallization-centrifugal separation device, the high-concentration copper chloride changes from a specific gravity of 1.20-1.22 and a copper ion concentration of 120g / L-130g / L to a specific gravity of 1.10-1.12 and a copper ion concentration of 60-80g / L; the low-concentration solution is output back to the system for reuse, and the cooled and separated copper chloride crystals are output as a by-product.
[0045] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.
[0046] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.
Claims
1. A method for dissolving copper powder in a copper chloride solution to absorb chlorine, characterized in that: The following steps are involved: S1, introducing chlorine gas generated by the electrolytic cylinder or etching machine into a chlorine absorption tower and dissolving it in a CuCl2-CuCl absorption solution; S2, the dissolving tank and the chlorine absorption tower keep circulating, and an ORP meter is set in the chlorine absorption tower. When the ORP value rises to the set value after the absorption liquid absorbs chlorine, the ORP meter signal output controls the addition of copper powder into the dissolving tank; S3, a specific gravity controller is provided in the dissolving tank to detect the specific gravity of the CuCl2-CuCl solution. When the specific gravity of the CuCl2-CuCl solution rises to the set value, the high-concentration CuCl2 solution is output; S4, the high concentration CuCl2 solution is cooled and crystallized, and centrifuged to obtain CuCl2 crystals. The low concentration CuCl2 solution after separation is continuously recycled to the chlorine absorption tower, and the above steps are repeated.
2. A method for dissolving copper scraps in a copper chloride solution to absorb chlorine according to claim 1, characterized in that: The chemical reaction in the chlorine absorption tower is 2Cu + +Cl2=2Cu 2+ +Cl - .
3. A method for dissolving copper scraps in a copper chloride solution to absorb chlorine according to claim 1, characterized in that: The set value of the orp is set to 550mv.
4. A method for dissolving copper scraps in a copper chloride solution to absorb chlorine according to claim 1, characterized in that: The chemical reaction in the dissolving tank is 2Cu 2+ +Cu=3Cu + .
5. A method for dissolving copper scraps in a copper chloride solution to absorb chlorine according to claim 1, characterized in that: The set value of the specific gravity controller is 1.
22.
6. A method for dissolving copper scrap powder in a copper chloride solution to absorb chlorine according to claim 1, characterized in that: The parameters of the high concentration CuCl2 solution in S3 are: The specific gravity is 1.20-1.22, and the copper ion concentration is 120g / L-130g / L.
7. A method for dissolving copper scrap powder in a cupric chloride solution to absorb chlorine according to claim 1, characterized in that: The parameters of the low concentration CuCl2 solution in S4 are: The specific gravity is 1.10-1.12, and the copper ion concentration is 60-80g / L.