Method for comprehensive utilization of waste liquid from brown oxidation of circuit board

Abstract

The application discloses a kind of brown waste liquid comprehensive utilization method of circuit board, belong to brown waste liquid processing method technical field, including the pretreatment of brown waste liquid at room temperature, depth purification brown waste liquid, electrolytic deposition recovery cathode copper, four steps of collaborative acidification treatment ink waste liquid recovery ink slag;The method does not need heating, does not use strong oxidant potassium permanganate, sodium chlorate under the condition of electrolytic recovery high-quality cathode copper plate, avoids the risk of environmental pollution in the secondary treatment process of traditional brown waste liquid, electrolytic deposition recovery copper causes fire and leakage chlorine, while collaborative treatment ink waste liquid, saves a lot of sulfuric acid and liquid alkali consumption, reduces carbon emission, with good economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the technical field of browning waste liquid treatment methods, and in particular to a method for the comprehensive utilization of browning waste liquid from circuit boards. Background Technology

[0002] In people's lives, all automatically controlled products, from spaceships, airplanes, high-speed trains, cars, and ships to computers, mobile phones, and even pedometers carried by many people, require circuit boards (PCBs) for transmission to achieve automatic control. PCBs are the supporting structure for electronic product components and the most basic hardware carrier in today's information society. The PCB industry is a pillar industry of China's electronic information industry, with its growth rate increasing at the same rate as the entire electronic information industry. Especially with the advent of the 5G era, the Internet of Things, new energy vehicles, and smart home appliances have placed higher demands on PCB manufacturing technology. For example, there is an increasing demand for multi-layer precision circuit boards. The lamination process is an indispensable step in multi-layer circuit board manufacturing, and the surface browning treatment before lamination is even more crucial. The purpose of browning treatment is to form a surface passivation barrier layer so that the copper surface does not react with the resin during lamination to produce moisture, or to prevent the copper surface from being attacked, resulting in insufficient interlayer bonding and delamination. During the oxidation process, the contact surface area between the copper and resin is also increased, resulting in good bonding strength after lamination. The common browning process involves pickling → degreasing → activation → browning. Browning is a chemical copper etching reaction. As production progresses, the copper ion concentration in the browning solution continuously increases. When the copper ion concentration exceeds a certain limit (generally 25-35 g / L), the excessive copper ions cause quality problems such as a whitening of the browned copper surface and uneven color. At this point, the browning tank must be replenished with new browning solution to keep the copper ion concentration below 35 g / L. Simultaneously, waste liquid is discharged from the browning tank, forming browning waste liquid. Furthermore, the browning tank requires regular thorough cleaning and solution replacement, resulting in a large amount of browning waste liquid. According to industry data, manufacturing 10,000 square meters of circuit boards generates 4-5 tons of browning waste liquid. With China's annual circuit board production exceeding 1 billion square meters, it is estimated that the circuit board industry generates over 500,000 tons of browning waste liquid annually. Browning waste liquid contains large amounts of sulfuric acid, hydrogen peroxide, alkanolamines, alcohol ethers, thiazoles, and benzene ring organic compounds, classifying it as hazardous waste. Improper disposal poses a significant risk of environmental pollution. Currently, the main treatment method involves circuit board manufacturers transporting the waste liquid to qualified hazardous waste disposal companies for treatment. These companies then process the collected browning waste liquid using the Fenton process, generating large amounts of copper- and iron-containing sludge. This process is not only wasteful and energy-intensive, but also poses a risk of secondary environmental pollution from the solid waste generated. A small number of circuit board companies also use sodium hypochlorite oxidation to break down large molecular organic compounds, followed by electrolytic deposition to recover copper. However, the recovered copper is a mixture of copper powder and chemicals, resulting in a low selling price. Furthermore, the electrolytic deposition of copper in the browning waste liquid carries the risk of short circuits and fires (there have been numerous cases of fires caused by the electrolysis of browning waste liquid in the circuit board industry).

[0003] The ink wastewater generated during circuit board manufacturing mainly refers to the wastewater from the developing and stripping processes. This wastewater contains a large amount of photosensitive film and solder resist residue, and is alkaline, with a pH value generally between 11 and 13. The organic pollutant content is very high, typically ranging from 8000 to 10000 mg / L. The main component of the ink wastewater is organic acid salts formed from hydroxyl-containing resins under alkaline conditions, and these hydroxyl-containing resins are not easily soluble in acidic solutions. Current technologies typically use sulfuric acid to acidify the ink wastewater generated during developing and stripping, followed by solid-liquid separation to obtain ink residue and wastewater with reduced organic pollutants. However, using concentrated sulfuric acid presents problems such as operational safety and high wastewater treatment costs. Summary of the Invention

[0004] This invention provides a method for the comprehensive utilization of PCB browning waste liquid. This method achieves the safe recovery of high-quality metallic copper from PCB browning waste liquid while simultaneously treating ink waste liquid. This method has good environmental and economic benefits. The technical content of this invention is as follows:

[0005] The purpose of this invention is to provide a method for the comprehensive utilization of circuit board browning waste liquid, the technology of which includes the following steps:

[0006] Step 1, room temperature complexation treatment of browning waste liquid: Under room temperature conditions, add 5-10 kg / (1000L browning waste liquid) of composite catalyst to the browning waste liquid, stir and react for 2-5 hours to obtain the first browning waste liquid;

[0007] Step 2, Deep purification treatment of the first browning waste liquid: Slowly add 2-5 kg / (1000L browning waste liquid) of deep purification agent to the first browning waste liquid obtained in Step 1 to reduce the content of organic pollutants, filter and discard the supernatant to obtain the second browning waste liquid.

[0008] Step 3, Electrolytic recovery of cathode copper from the second browning waste liquid: After transferring the second browning waste liquid obtained in step 2 into the electrolytic cell, add 0.1-0.5 kg / (1000L browning waste liquid) of electrolytic additive. Adjust the current density according to the change of copper ion concentration to electrolyze and recover cathode copper. When the copper ion concentration in the electrolyte drops to below 2 g / L, discharge the electrolyte to obtain copper-poor browning waste liquid.

[0009] Step 4, co-processing ink waste liquid: Add the copper-poor browning waste liquid obtained in step 3 to the ink waste liquid and stir to obtain a mixed liquid. Control the amount of ink waste liquid added so that the pH value of the mixed liquid is 2-3. Then use a centrifuge to separate the solid and liquid to obtain ink residue and comprehensive wastewater.

[0010] In some embodiments of the present invention, the composite catalyst in step one of the above-mentioned method for comprehensive utilization of circuit board browning waste liquid includes manganese oxide, iron oxide and aluminum oxide.

[0011] In some embodiments of the present invention, the composite catalyst in the above-mentioned method for comprehensive utilization of circuit board browning waste liquid includes manganese dioxide, ferric oxide and aluminum oxide.

[0012] In some embodiments of the present invention, in the above-mentioned method for comprehensive utilization of circuit board browning waste liquid, the composite catalyst comprises 50-70 parts by weight of manganese dioxide, 10-30 parts by weight of ferric oxide and 10-30 parts by weight of aluminum oxide.

[0013] In some embodiments of the present invention, the deep purification agent in step two of the above-mentioned method for comprehensive utilization of circuit board browning waste liquid is barium chloride.

[0014] In some embodiments of the present invention, the electrolytic additive in step three of the above-mentioned method for comprehensive utilization of circuit board browning waste liquid is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt.

[0015] In some embodiments of the present invention, the amount of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt added is 0.1%-0.5% of the weight of the browning waste liquid.

[0016] In some embodiments of the present invention, the weight ratio of the epichlorohydrin dimethyl polymer to the polymeric quaternary ammonium salt is (1.5-3.5):1.

[0017] In some embodiments of the present invention, in the above-mentioned method for comprehensive utilization of circuit board browning waste liquid, the current density in step three is 50-200 A / m. 2 .

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention discloses a method for the comprehensive utilization of circuit board browning waste liquid, comprising four steps: pretreatment of browning waste liquid at room temperature, deep purification of browning waste liquid, electrolytic deposition to recover cathode copper, and synergistic acidification treatment of ink waste liquid to recover ink residue. This method electrolytically recovers high-quality cathode copper plates without heating or using strong oxidants such as potassium permanganate and sodium chlorate, avoiding the environmental pollution and the risks of fire and chlorine leakage caused by electrolytic deposition and recovery of copper in traditional secondary treatment of browning waste liquid. At the same time, the synergistic treatment of ink waste liquid saves a large amount of sulfuric acid and liquid alkali consumption, reduces carbon emissions, and has good economic and environmental benefits. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 This is a flowchart of a method for the comprehensive utilization of browning waste liquid from circuit boards according to the present invention. Detailed Implementation

[0022] A method for comprehensive utilization of circuit board browning waste liquid includes the following steps:

[0023] Step 1, Room Temperature Complex Decomposition Treatment of Browning Waste Liquid: Under room temperature conditions (10-30℃), 5-10 kg / (1000L browning waste liquid) of composite catalyst is added to the browning waste liquid, and the mixture is stirred and reacted for 2-5 hours to obtain the first browning waste liquid. Preferably, the composite catalyst of this invention includes manganese oxide, iron oxide, and aluminum oxide. To enable efficient catalytic decomposition of complexes such as hydrogen peroxide in the browning waste liquid under room temperature conditions, the composite catalyst of this invention further includes manganese dioxide, ferric oxide, and aluminum oxide. Even further, the composite catalyst includes 50-70 parts by weight of manganese dioxide, 10-30 parts by weight of ferric oxide, and 10-30 parts by weight of aluminum oxide.

[0024] Step Two, Deep Purification Treatment of the First Browning Waste Liquid: Slowly add 2-5 kg / (1000L) of deep purification agent to the first browning waste liquid obtained in Step One to reduce the content of organic pollutants. Filter and discard the supernatant to obtain the second browning waste liquid. The main purpose of this step is to remove organic matter from the first browning waste liquid, reducing organic pollutants so that copper ions can be successfully electrolytically deposited on the cathode plate. If organic pollutants are not reduced and organic matter is not removed, the monovalent copper ions generated during electrolysis will form a black precipitate with the organic matter in the waste liquid and adsorb onto the anode and cathode plates, increasing resistance and preventing the electrolysis of high-quality cathode copper plates. Preferably, the deep purification agent of this invention is barium chloride. Through extensive experimental testing, the applicant has found that barium chloride aqueous solution can form a co-precipitate with sulfate ions and organic matter-benzotriazine (methylbenzotriazine) in the browning waste liquid. After solid-liquid separation, during the electrolytic deposition of the second browning waste liquid after solid-liquid separation, no black substance will be produced on the cathode, forming a red copper surface.

[0025] Step 3, Electrolytic recovery of cathode copper from the second browning waste liquid: After transferring the second browning waste liquid obtained in Step 2 into an electrolytic cell, add 0.1-0.5 kg / (1000L browning waste liquid) of electrolytic additive. Adjust the current density according to the change in copper ion concentration to electrolytically recover cathode copper. When the copper ion concentration in the electrolyte drops below 2 g / L, discharge the electrolyte to obtain copper-poor browning waste liquid. Preferably, the electrolytic additive of this invention is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt. The amount of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt added is 0.1%-0.5% of the weight of the browning waste liquid; the weight ratio of epichlorohydrin dimethyl polymer to polymeric quaternary ammonium salt is (1.5-3.5):1; and the current density of this invention is 50-200 A / m. 2 The electrolytic additive is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt, which makes the electrolytic cathode copper smoother and purer. It can also shield the residual BTA in the browning waste liquid and prevent BTA from forming black precipitates with cuprous ions and adhering to the cathode copper surface, causing the cathode copper to easily delaminate and fall off with low purity. Compared with ordinary additives, a mixture of polyether and alkyl sulfonic acid, it has significant advantages.

[0026] Step 4, co-processing ink waste liquid: The copper-poor browning waste liquid obtained in step 3 is added to the ink waste liquid and stirred to obtain a mixed liquid. The amount of ink waste liquid added is controlled so that the pH value of the mixed liquid is 2-3. Then, a centrifuge is used for solid-liquid separation to obtain ink residue and comprehensive wastewater. The comprehensive wastewater of this invention can be directly discharged to a comprehensive sewage treatment plant for deep purification treatment and discharge in compliance with standards.

[0027] The above method pretreats the browning wastewater at room temperature. The pretreatment process removes complexing agents and organic matter from the browning wastewater without the use of strong oxidants, allowing the electrolytic deposition recovery of cathode copper to proceed normally. The recovered cathode copper is of high quality (content >99%). After reducing the copper ions in the browning wastewater through electrolytic deposition, an electrolytic solution with an acidity of 1-3 mol / L (mainly composed of sulfuric acid) is obtained. The electrolytic solution is used to neutralize and treat the ink wastewater. Then, the ink residue and combined wastewater are separated by centrifugation. The wastewater can be further treated in a comprehensive sewage treatment plant to meet standards. This method achieves the goal of safely recovering high-quality metallic copper from the browning wastewater of circuit boards while simultaneously treating the ink wastewater. This method has good environmental and economic benefits.

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] The technical solutions provided by the various embodiments of the present invention are described in detail below with reference to the accompanying drawings. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply.

[0030] Example 1

[0031] like Figure 1 The method for comprehensive utilization of circuit board browning waste liquid includes the following steps:

[0032] Step 1, room temperature complexation treatment of browning waste liquid: At room temperature (10-30℃), add 5kg of composite catalyst to 1000L of browning waste liquid, stir the reaction until no more bubbles emerge from the reaction vessel, stop stirring to obtain the first browning waste liquid, the stirring time is 2h;

[0033] Step 2, Deep purification treatment of the first browning waste liquid: Slowly add 2 kg of deep purification agent to the first browning waste liquid obtained in Step 1, stir and react to carry out deep purification treatment, filter and discard the supernatant to obtain the second browning waste liquid.

[0034] Step 3, Electrolytic recovery of cathode copper from the second browning waste liquid: After transferring the second browning waste liquid obtained in Step 2 into the electrolytic cell, add 0.1 kg / (1000 L of browning waste liquid) of electrolytic additive. The electrolytic additive is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt, and the amount of the mixture added is 0.1% of the weight of the browning waste liquid; the weight ratio of epichlorohydrin dimethyl polymer to polymeric quaternary ammonium salt is 3.5:1, and the current density is 50 A / m. 2 Under certain conditions, the cathode copper is recovered by electrolytic deposition of metallic copper. Once the copper ion concentration in the electrolyte drops below 2 g / L, the electrolyte is discharged to obtain copper-poor browning waste liquid.

[0035] Step 4, co-processing ink waste liquid: The copper-poor browning waste liquid obtained in Step 3 is added to the ink waste liquid and stirred to obtain a mixed liquid. The amount of ink waste liquid added is controlled so that the pH value of the mixed liquid is 2. Then, solid-liquid separation is performed using a centrifuge to obtain ink residue and comprehensive wastewater. The data of browning waste liquid, wastewater after co-processing ink waste liquid, and cathode copper electrolytically deposited are shown in Table 1.

[0036] Example 2

[0037] like Figure 1 The method for comprehensive utilization of circuit board browning waste liquid includes the following steps:

[0038] Step 1, room temperature complexation treatment of browning waste liquid: Under room temperature conditions (10-30℃), add 8kg of composite catalyst to 1000L of browning waste liquid, stir the reaction until no more bubbles emerge from the reaction vessel, stop stirring to obtain the first browning waste liquid, the stirring time is 3h;

[0039] Step 2, Deep purification treatment of the first browning waste liquid: Slowly add 4 kg of deep purification agent to the first browning waste liquid obtained in Step 1, stir and react to carry out deep purification treatment, filter and discard the supernatant to obtain the second browning waste liquid.

[0040] Step 3: Electrolytic recovery of cathode copper from the second browning waste liquid: After transferring the second browning waste liquid obtained in Step 2 into the electrolytic cell, 0.3 kg of electrolytic additive is added. The electrolytic additive is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt, and the amount of the mixture added is 0.5% of the weight of the browning waste liquid; the weight ratio of epichlorohydrin dimethyl polymer to polymeric quaternary ammonium salt is 1.5:1, and the current density is 125 A / m. 2 Under certain conditions, the cathode copper is recovered by electrolytic deposition of metallic copper. Once the copper ion concentration in the electrolyte drops below 1 g / L, the electrolyte is discharged to obtain copper-poor browning waste liquid.

[0041] Step 4, co-processing ink waste liquid: The copper-poor browning waste liquid obtained in Step 3 is added to the ink waste liquid and stirred to obtain a mixed liquid. The amount of ink waste liquid added is controlled so that the pH value of the mixed liquid is 2.5. Then, solid-liquid separation is performed using a centrifuge to obtain ink residue and comprehensive wastewater. The data of browning waste liquid, wastewater after co-processing ink waste liquid, and cathode copper electrolytically deposited are shown in Table 1.

[0042] Example 3

[0043] like Figure 1 The method for comprehensive utilization of circuit board browning waste liquid includes the following steps:

[0044] Step 1, room temperature complexation treatment of browning waste liquid: Under room temperature conditions (10-30℃), add 10kg of composite catalyst to 1000L of browning waste liquid, stir the reaction until no more bubbles emerge from the reaction vessel, stop stirring to obtain the first browning waste liquid, the stirring time is 5h;

[0045] Step 2, Deep purification treatment of the first browning waste liquid: Slowly add 5 kg of deep purification agent to the first browning waste liquid obtained in Step 1, stir and react to carry out deep purification treatment, filter and discard the supernatant to obtain the second browning waste liquid.

[0046] Step 3, Electrolytic recovery of cathode copper from the second browning waste liquid: After transferring the second browning waste liquid obtained in Step 2 into the electrolytic cell, 0.5 kg of electrolytic additive is added. The electrolytic additive is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt, and the amount of the mixture added is 0.3% of the weight of the browning waste liquid; the weight ratio of epichlorohydrin dimethyl polymer to polymeric quaternary ammonium salt is 2:1, and the current density is 200 A / m. 2 Under certain conditions, the cathode copper is recovered by electrolytic deposition of metallic copper. Once the copper ion concentration in the electrolyte drops below 1.5 g / L, the electrolyte is discharged to obtain copper-poor browning waste liquid.

[0047] Step 4, co-processing ink waste liquid: The copper-poor browning waste liquid obtained in Step 3 is added to the ink waste liquid and stirred to obtain a mixed liquid. The amount of ink waste liquid added is controlled so that the pH value of the mixed liquid is 3. Then, solid-liquid separation is performed using a centrifuge to obtain ink residue and comprehensive wastewater. The data of browning waste liquid, wastewater after co-processing ink waste liquid, and cathode copper electrolytically deposited are shown in Table 1.

[0048] Table 1

[0049]

[0050] As can be seen from the table above, the cathode copper content recovered in Examples 1-3 is all above 99%, and the organic pollutants in the ink wastewater are reduced from 15,000-25,000 mg / L to below 6,000 mg / L, which can meet the influent index requirements of the integrated wastewater treatment plant.

[0051] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for comprehensive utilization of circuit board browning waste liquid, characterized in that, Includes the following steps: Step 1, room temperature complexation treatment of browning waste liquid: Under room temperature conditions, add 5-10 kg / (1000L browning waste liquid) of composite catalyst to the browning waste liquid, stir and react for 2-5 hours to obtain the first browning waste liquid; Step 2, Deep purification treatment of the first browning waste liquid: Slowly add 2-5 kg / (1000L browning waste liquid) of deep purification agent to the first browning waste liquid obtained in Step 1 to reduce the content of organic pollutants, filter and discard the supernatant to obtain the second browning waste liquid. Step 3, Electrolytic recovery of cathode copper from the second browning waste liquid: After transferring the second browning waste liquid obtained in step 2 into the electrolytic cell, add 0.1-0.5 kg / (1000L browning waste liquid) of electrolytic additive. Adjust the current density according to the change of copper ion concentration to electrolyze and recover cathode copper. When the copper ion concentration in the electrolyte drops to below 2 g / L, discharge the electrolyte to obtain copper-poor browning waste liquid. Step 4, co-processing ink waste liquid: Add the copper-poor browning waste liquid obtained in step 3 to the ink waste liquid and stir to obtain a mixed liquid. Control the amount of ink waste liquid added so that the pH value of the mixed liquid is 2-3. Then use a centrifuge to separate the solid and liquid to obtain ink residue and comprehensive wastewater. The composite catalyst comprises, by weight, 50-70 parts manganese dioxide, 10-30 parts ferric oxide and 10-30 parts aluminum oxide; The deep purification agent in step two is barium chloride.

2. The method for comprehensive utilization of circuit board browning waste liquid according to claim 1, characterized in that, The electrolytic additive in step three is a mixture of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt.

3. The method for comprehensive utilization of circuit board browning waste liquid according to claim 2, characterized in that, The amount of epichlorohydrin dimethyl polymer and polymeric quaternary ammonium salt added is 0.1%-0.5% of the weight of the browning waste liquid.

4. The method for comprehensive utilization of circuit board browning waste liquid according to claim 3, characterized in that, The weight ratio of the epichlorohydrin dimethyl polymer to the polymeric quaternary ammonium salt is (1.5-3.5):

1.

5. The method for comprehensive utilization of circuit board browning waste liquid according to claim 1, characterized in that, The current density in step three is 50-200 A / m. 2 .

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