A method for the co-treatment of chemical copper waste liquid and browning waste liquid

Abstract

This invention discloses a method for the co-treatment of chemical copper waste liquid and browning waste liquid, comprising the following steps: mixing browning waste liquid and chemical copper waste liquid from the circuit board manufacturing process to obtain a mixed waste liquid; adding stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 4-5; then adding ferrous sulfate to the mixed waste liquid to induce a Fenton oxidation reaction; after Fenton oxidation, continuing to add stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 9-11, and stirring evenly to convert copper ions in the mixed waste liquid into copper hydroxide precipitate; finally, performing pressure filtration treatment on the mixed waste liquid to separate qualified wastewater and copper-containing precipitate. This invention utilizes the characteristics of both chemical copper waste liquid and browning waste liquid to treat both types of waste liquid simultaneously, and the treatment process only requires the addition of ferrous sulfate, resulting in low cost and a short and simple processing flow.

Description

Technical Field

[0001] This invention relates to the field of waste liquid treatment technology in the process of circuit board manufacturing, specifically to a method for the synergistic treatment of chemical copper waste liquid and browning waste liquid. Background Technology

[0002] The main pollutant in the wastewater discharged by the printed circuit board (PCB) industry, including traditional single-sided, double-sided, multilayer, high-density interconnect boards, and packaging boards, is Cu. 2+ It mainly consists of heavy metal ions and recalcitrant organic matter. It contains Cu. 2+ The wastewater mainly includes: EDTA-copper wastewater discharged from the PTH (chemical copper) line, ammonia-copper wastewater discharged from the etching line, and low-copper-containing wastewater discharged from the pretreatment process. Among these, the heavy metal copper in the EDTA-Cu wastewater and ammonia-copper wastewater exists in a complexed state and has high chemical stability. The copper contaminants can only be removed by breaking down the complexes. Other types of low-copper-containing wastewater can be directly removed by simple alkaline precipitation.

[0003] Chemical copper plating is an important process in the circuit board industry. Chemical copper plating wastewater is mainly an aqueous solution containing soluble copper salts, complexing agents, reducing agents, pH adjusters, and other trace additives. Existing technology CN112479458B discloses a method for treating chemical copper plating wastewater. First, a reducing agent is added to replace the copper. Then, hydrogen peroxide is added for Fenton oxidation to decompose other organic matter besides EDTA. Next, ferric ion solution and sodium ion solution are added to synthesize sodium ferric ethylenediaminetetraacetate. This method can simultaneously recover copper ions and EDTA complexing agents from the chemical copper plating wastewater. However, this method involves many chemicals, resulting in high costs. The recovered material is only a small amount of low-value copper powder and complexing agents. Furthermore, the wastewater is treated to meet discharge standards in a single step, and the treated liquid can be discharged without further treatment at a wastewater treatment plant. This does not utilize the existing wastewater treatment capacity effectively and increases treatment costs. Another example is the treatment method for wastewater containing complexed copper in existing technology CN103183421A, which cannot remove complexing agents and other organic matter from the wastewater.

[0004] Browning is a process for bonding inner-layer copper to polymer materials in multilayer printed circuits. This process generates browning waste liquid, which mainly contains high concentrations of sulfuric acid, hydrogen peroxide, polyethylene glycol, organic copper micro-etching agents (such as azoles and pyrrole compounds), and organic hydrogen peroxide stabilizers (such as EDTA, benzenesulfonic acid, and thioglycolic acid). The waste liquid also contains a large amount of dissolved copper ions, and its chemical oxygen demand (COD) is generally between (5-6) × 10⁴ mg / L. Existing technology CN A method for treating brown wastewater disclosed in patent 110294546B involves: first, adding an alkaline substance to the brown wastewater to adjust its pH to 6-8, and stirring to allow the silanes in the wastewater to fully hydrolyze; then, continuing to add alkaline substances to adjust the pH to greater than 8.5, and stirring again to generate a precipitate; next, adding flocculants and coagulants, allowing the mixture to settle and separate, and then filtering to obtain filter residue and filtrate, thus completing the treatment of the brown wastewater. This method also involves the addition of a large amount of chemical substances, increasing treatment costs. Furthermore, since the wastewater is treated to meet discharge standards in a single step and does not require further treatment at a wastewater treatment plant, it does not fully utilize the existing wastewater treatment capacity and increases overall costs. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides a method for the co-treatment of chemical copper waste liquid and browning waste liquid. This method utilizes the characteristics of both chemical copper waste liquid and browning waste liquid to treat both types of waste liquid simultaneously. Furthermore, the treatment process only requires the addition of ferrous sulfate, resulting in low cost and a short and simple processing flow.

[0006] To address the aforementioned technical problems, this invention provides a method for the co-treatment of chemical copper waste liquid and browning waste liquid, comprising the following steps:

[0007] S1. Mix the browning waste liquid and chemical copper waste liquid from the circuit board production process to obtain a mixed waste liquid;

[0008] S2. Add the film stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 4-5;

[0009] S3. Then, ferrous sulfate is added to the mixed waste liquid to allow the mixed waste liquid to undergo Fenton oxidation reaction.

[0010] S4. After Fenton oxidation, continue to add stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 9-11, and stir evenly to convert the copper ions in the mixed waste liquid into copper hydroxide precipitate.

[0011] S5. Finally, the mixed waste liquid is subjected to pressure filtration to separate qualified wastewater and copper-containing filter residue.

[0012] Furthermore, in step S1, the volume ratio of browning waste liquid to chemical copper waste liquid in the mixed waste liquid is 2 to 5:1.

[0013] Furthermore, in steps S2 and S4, the defilming waste liquid is a sodium hydroxide solution with a mass percentage concentration of 3%.

[0014] Furthermore, in step S3, after adding ferrous sulfate, the content of ferrous sulfate in the mixed waste liquid is 10-20 mL / L.

[0015] Furthermore, in step S3, the waste liquid is continuously stirred during the Fenton oxidation reaction.

[0016] Furthermore, in step S3, ferrous sulfate is added to the mixed waste liquid, and the mixture is stirred for 2 hours to carry out the Fenton oxidation reaction.

[0017] Furthermore, in step S4, the stirring time is 30 minutes.

[0018] Furthermore, after step S5, the following steps are also included:

[0019] S6. Inject the qualified wastewater into the complex wastewater treatment system of the sewage treatment plant for further treatment until it meets the discharge standards before discharging.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] In this invention, the characteristics of both chemical copper waste liquid and browning waste liquid are utilized. The two are mixed, and the sulfuric acid and hydrogen peroxide in the browning waste liquid react with the sodium hydroxide in the chemical copper waste liquid. After adjusting the pH to 4-5 by adding stripping waste liquid, ferrous sulfate is added as a catalyst to induce a Fenton oxidation reaction in the mixed waste liquid. This reaction reduces organic matter such as complexing agents, reducing agents, and silane coupling agents in the waste liquid. Then, by adding stripping waste liquid again, the pH of the mixed waste liquid is adjusted to 9-11. At this pH, hydroxide ions in the stripping waste liquid react with copper and iron ions in the mixed waste liquid to form metal precipitates, achieving the purpose of removing and extracting copper ions from the waste liquid. Finally, the precipitates and waste liquid are separated by pressure filtration, bringing the treated waste liquid to the receiving level of a wastewater treatment plant. This treatment method can treat two types of waste liquid simultaneously, and the process only requires the addition of ferrous sulfate, resulting in low cost and a short and simple processing flow.

[0022] Secondly, the waste liquid after pressure filtration (i.e. qualified wastewater) is injected into the complexed wastewater treatment system of the sewage treatment plant for further treatment, either separately or mixed with other wastewater for further treatment until it meets the discharge standards before being discharged. This fully utilizes the existing sewage treatment capacity and further reduces the cost of waste liquid treatment.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Detailed Implementation

[0024] To better understand the technical content of this invention, the technical solution of this invention will be further introduced and explained below in conjunction with specific embodiments.

[0025] Example 1

[0026] This embodiment illustrates a method for the co-treatment of chemical copper waste liquid and browning waste liquid, which includes the following steps:

[0027] a. First, collect the browning waste liquid, chemical copper waste liquid, and film stripping waste liquid from the circuit board production process. Both the browning waste liquid and the chemical copper waste liquid are acidic waste liquids, while the film stripping waste liquid is an alkaline waste liquid.

[0028] b. Mix the browning waste liquid and the chemical copper waste liquid from the circuit board production process to obtain a mixed waste liquid.

[0029] In the above example, taking a multilayer board with an average of 4.5 layers in actual production as an example, the volume ratio of browning waste liquid to chemical copper waste liquid in the mixed waste liquid is 3:1.

[0030] In other embodiments, the volume ratio of browning waste liquid to chemical copper waste liquid in the mixed waste liquid can be 2 to 5:1, depending on the number of layers in other actual multilayer boards produced.

[0031] c. Add the film stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 4.5, as shown in Table 1 below. At this time, the initial COD value of the mixed waste liquid is measured to be 23 g / L.

[0032] In addition, the pH value of the mixed waste liquid can be adjusted to 4-5 according to actual needs.

[0033] In the above, the film stripping waste liquid is a sodium hydroxide solution with a mass percentage concentration of 3%.

[0034] d. Then, ferrous sulfate was added to the mixed waste liquid. Ferrous sulfate acts as a Fenton oxidation catalyst to enable the mixed waste liquid to undergo Fenton oxidation reaction. As shown in Table 1 below, the COD value of the mixed waste liquid after the Fenton oxidation reaction was measured to be 5.02 g / L.

[0035] In the above process, the mixed waste liquid is stirred continuously during the Fenton oxidation reaction. Preferably, ferrous sulfate is added to the mixed waste liquid, and the mixture is stirred for 2 hours before the Fenton oxidation reaction is carried out. That is, the Fenton oxidation reaction takes 2 hours.

[0036] In the above, the addition of ferrous sulfate makes the ferrous sulfate content in the mixed waste liquid 15 mL / L.

[0037] In other embodiments, ferrous sulfate may be added to make the ferrous sulfate content in the mixed waste liquid 10-20 mL / L, depending on other actual needs.

[0038] e. After Fenton oxidation is completed, continue to add stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 9-11, and stir evenly so that the copper ions in the mixed waste liquid are converted into copper hydroxide precipitate. Here, at this pH value, the hydroxide ions in the stripping waste liquid react with the copper and iron ions in the mixed waste liquid to form metal precipitates (i.e., copper hydroxide and iron hydroxide precipitates), thereby achieving the purpose of removing and extracting copper ions from the waste liquid.

[0039] In the above, the stirring time is 30 minutes.

[0040] In the above, the film stripping waste liquid is a sodium hydroxide solution with a mass percentage concentration of 3%.

[0041] f. After the above steps, the mixed wastewater contains sludge and metal precipitates. At this point, there is no need to separate the liquid and sludge by sedimentation. The mixed wastewater is directly subjected to pressure filtration to separate the filtrate and copper-containing filter residue. The copper-containing filter residue is recovered and sold, and the filtrate is qualified wastewater. As shown in Table 1 below, the COD value of the filtrate was measured to be 3 g / L. Compared with the initial COD value, the COD value decreased by 20 g / L, that is, the treatment efficiency of this method reached 87%.

[0042] g. Inject the qualified wastewater into the complexed wastewater treatment system of the sewage treatment plant for further treatment, or mix it with other wastewater for further treatment until it meets the discharge standards before discharge; the complexed wastewater treatment system is the existing sewage treatment system, which will not be described in detail here.

[0043] Table 1 shows the COD values ​​measured after each step of the treatment of the mixed waste liquid:

[0044]

[0045] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for the co-treatment of chemical copper waste liquid and brown leaching waste liquid, characterized in that, Includes the following steps: S1. The browning waste liquid and the chemical copper waste liquid from the circuit board production process are mixed to obtain a mixed waste liquid; the volume ratio of the browning waste liquid to the chemical copper waste liquid in the mixed waste liquid is 2 to 5:

1. S2. Add the film stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 4-5; S3. Then, ferrous sulfate is added to the mixed waste liquid to allow it to undergo Fenton oxidation. After adding ferrous sulfate, the ferrous sulfate content in the mixed waste liquid is 10-20 mL / L. S4. After Fenton oxidation, continue to add stripping waste liquid to the mixed waste liquid to adjust the pH value of the mixed waste liquid to 9-11, and stir evenly to convert the copper ions in the mixed waste liquid into copper hydroxide precipitate. S5. Finally, the mixed waste liquid is subjected to pressure filtration to separate qualified wastewater and copper-containing filter residue.

2. The method for co-treatment of chemical copper waste liquid and browning waste liquid according to claim 1, characterized in that, In steps S2 and S4, the defilming waste liquid is a sodium hydroxide solution with a mass percentage concentration of 3%.

3. The method for co-treatment of chemical copper waste liquid and browning waste liquid according to claim 1, characterized in that, In step S3, the waste liquid is continuously stirred during the Fenton oxidation reaction.

4. The method for co-treatment of chemical copper waste liquid and browning waste liquid according to claim 3, characterized in that, In step S3, ferrous sulfate is added to the mixed waste liquid, and the mixture is stirred for 2 hours to carry out the Fenton oxidation reaction.

5. The method for co-treatment of chemical copper waste liquid and browning waste liquid according to claim 1, characterized in that, In step S4, the stirring time is 30 minutes.

6. The method for co-treating chemical copper waste liquid and browning waste liquid according to any one of claims 1-5, characterized in that, Step S5 is followed by the following steps: S6. Inject the qualified wastewater into the complex wastewater treatment system of the sewage treatment plant for further treatment until it meets the discharge standards before discharging.

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