Method for preparing copper oxide from PCB acidic etching waste liquid

Abstract

The invention relates to a method for preparing copper oxide from PCB (printed circuit board) acidic waste etching liquid, in particular to the field of secondary utilization of waste etching liquid, and the method comprises the following steps: performing electrodialysis on the PCB acidic waste etching liquid to obtain recycled acid and low-acid waste etching liquid; the method comprises the following steps: mixing the low-acid etching waste liquid with alkali liquor, carrying out a neutralization decomposition reaction, and carrying out solid-liquid separation to obtain a copper oxide product; the operating temperature of electrodialysis is less than or equal to 35 DEG C. According to the method provided by the invention, the waste liquid is subjected to electrodialysis, most hydrochloric acid in the waste liquid is transferred to the concentration chamber of the electrodialysis equipment, the acidity of the waste liquid is reduced, the dosage of sodium hydroxide in the subsequent neutralization process can be reduced, and meanwhile, the hydrochloric acid solution of the cathode is used as a byproduct and can be reused for etching a production line and neutralizing the prepared copper oxide later; the copper plating solution can be sold as a product or applied to a circuit board copper plating process, so that high-efficiency and low-cost recycling of the copper element is realized.

Description

Technical Field

[0001] The invention relates to the field of secondary utilization of etching waste liquid, and in particular to a method for preparing copper oxide from PCB acidic etching waste liquid. Background Art

[0002] At present, the technology for preparing copper oxide from acidic etching waste liquid is to directly add sodium hydroxide solution to the waste liquid for neutralization. Due to the high concentration of hydrochloric acid in the etching waste liquid, a large amount of sodium hydroxide is used, which is costly.

[0003] For example, CN102303892A discloses a process for preparing copper oxide from an acidic etching solution: it comprises (1) adjusting the acidic etching solution to a pH of 10-13 with sodium hydroxide or potassium hydroxide, and the method further comprises the step (2) transferring the etching solution after step (1) into a stainless steel reactor lined with polytetrafluoroethylene, adding pure water to 70%-80% of the total volume of the reactor, and hydrothermally synthesizing at 120°C-200°C for 2-10h; after the reaction is completed, the reaction is naturally cooled to room temperature, the material at the bottom of the reactor is collected, and the copper oxide is successively washed with deionized water, washed with alcohol, and dried to obtain the copper oxide. This scheme adopts a hydrothermal synthesis method to prepare copper oxide from an acidic etching solution, and the obtained copper oxide has high purity, high activity, and uniform particle size.

[0004] There is also a similar technology that separates hydrochloric acid from the etching waste liquid by means of evaporation and crystallization, and then performs subsequent treatment. However, evaporation and crystallization have high energy consumption, high safety risks, and low hydrochloric acid recovery efficiency. For example, CN207877867U discloses a device for recovering hydrochloric acid and preparing copper sulfate from acidic etching waste liquid, which belongs to the field of waste liquid recovery and treatment in the electronics industry. The acidic etching waste liquid is separated into dilute hydrochloric acid and copper chloride crystals by multi-effect evaporation and crystallization, and then copper chloride is reacted with concentrated sulfuric acid to form copper sulfate and hydrogen chloride gas through a sulfonation reaction. The dilute hydrochloric acid separated by multi-effect evaporation and crystallization is used to absorb the hydrogen chloride gas produced by the reaction to produce a hydrochloric acid product with a hydrogen chloride content of 31%; after crystallization and recrystallization of copper sulfate, pure copper sulfate pentahydrate crystals are obtained, and the sulfuric acid-containing mother liquor produced during the sulfonation reaction is concentrated and then re-participated in the sulfonation reaction. This solution can recycle high-concentration pure hydrochloric acid and produce high-purity copper sulfate pentahydrate through recrystallization. No three wastes are generated during operation. The generated liquids, gases and solids are all made into products. The waste liquid is completely treated, the product conversion rate is high, and the operation is safe and stable.

[0005] In summary, when treating acidic copper-containing etching waste liquid, there are still defects such as low copper recovery rate and high recovery cost. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing copper oxide from PCB acidic etching waste liquid, so as to solve the defects of low copper recovery rate and high recovery cost when the acidic copper-containing etching waste liquid is treated.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing copper oxide from PCB acid etching waste liquid, the method comprising:

[0009] The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid;

[0010] The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and then a copper oxide product is obtained by solid-liquid separation;

[0011] The operating temperature of the electrodialysis is ≤35°C.

[0012] The method provided by the present invention subjects the waste liquid to electrodialysis, and most of the hydrochloric acid in the waste liquid is transferred to the concentration chamber of the electrodialysis equipment, so that the acidity of the waste liquid is reduced, and the amount of sodium hydroxide used in the subsequent neutralization process can be reduced. At the same time, the hydrochloric acid solution at the cathode is utilized as a by-product and can be reused in the etching production line. The copper oxide prepared by subsequent neutralization can be sold as a product or used in the copper electroplating process of the circuit board, thereby realizing efficient and low-cost recycling of the copper element.

[0013] As a preferred technical solution of the present invention, the membrane used in the electrodialysis includes a cationic membrane.

[0014] As a preferred technical solution of the present invention, the operating temperature of the electrodialysis is 23-35°C.

[0015] As a preferred technical solution of the present invention, the current density of the electrodialysis is 450-550A / m 2 .

[0016] As a preferred technical solution of the present invention, the temperature of the alkali solution in the mixture of the low-acid etching waste liquid and the alkali solution is 70-75°C.

[0017] As a preferred technical solution of the present invention, the concentration of the alkali solution is 4-5 mol / L.

[0018] As a preferred technical solution of the present invention, the end point of the mixing is when the pH value of the material is 10-14.

[0019] As a preferred technical solution of the present invention, the temperature of the neutralization decomposition reaction is ≥70°C.

[0020] As a preferred technical solution of the present invention, the time of the neutralization and decomposition reaction is ≥ 1h.

[0021] As a preferred technical solution of the present invention, the solid-liquid separation method includes one of pressure filtration, suction filtration or centrifugal separation.

[0022] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0023] (1) The concentration of hydrochloric acid in the etching waste liquid is reduced by pretreatment with electrodialysis technology, the amount of sodium hydroxide used in the neutralization process is reduced, and the production cost is reduced. Most of the hydrochloric acid in the acidic etching waste liquid is transferred to the concentration chamber through electrodialysis. This part of the hydrochloric acid by-product can be reused in the etching production line, further reducing the overall cost.

[0024] (2) Reduce the concentration of hydrochloric acid in the waste liquid, make the neutralization treatment operation safer, reduce the salinity of the neutralization filtrate, and be more environmentally friendly. The electrodialysis equipment operates at room temperature and has low power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a flow chart of a method for preparing copper oxide from PCB acid etching waste liquid.

[0026] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0027] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0028] This embodiment provides a method for preparing copper oxide from PCB acid etching waste liquid, the process is as follows Figure 1 As shown, the method includes:

[0029] The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid;

[0030] The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and then a copper oxide product is obtained by solid-liquid separation;

[0031] The operating temperature of the electrodialysis is ≤35°C.

[0032] Wherein, the membrane used in the electrodialysis comprises a cationic membrane.

[0033] In the present invention, the hydrochloric acid concentration of the etching waste liquid stock solution is exemplarily 1.8-3.0 mol / L, such as a two-liquid acid etching solution, the main components of which are: Cl - 250-290g / L, Cu 2+ 120-140g / L, H +1.5-3.0mol / L, the rest is Na + ; Single liquid acid etching solution, the main components are: Cl - 180-220g / L, Cu 2+ 90-110g / L, H + 0.5-1.5mol / L, the rest

[0034] In the present invention, the cationic membrane used can be a commercially available common cationic membrane, or a cationic membrane synthesized using existing technology. Commercially available products include the homogeneous membrane A81 produced by Jinqiu Environmental Protection Water Treatment Co., Ltd., the EDI special cationic membrane A31, and the heterogeneous cationic membrane produced by Shanghua Water Treatment Materials Co., Ltd.

[0035] Wherein, the operating temperature of the electrodialysis is 23-35°C, for example, it can be 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0036] Wherein, the current density of the electrodialysis is 450-550A / m 2 , for example, it can be 450A / m 2 、460A / m 2 、470A / m 2 、480A / m 2 、490A / m 2 , 500A / m 2 、510A / m 2 、520A / m 2 、530A / m 2 、540A / m 2 or 550A / m 2 The above values ​​are not limited to the above values. Other values ​​not listed in the above values ​​also meet the requirements.

[0037] In the present invention, the electrodialysis is to fill the desalination chamber of the electrodialysis cell and the desalination liquid collection cylinder with etching waste liquid, and at the same time fill the concentration chamber of the electrodialysis cell and the concentrated liquid collection cylinder with pure water, and the rectifier is powered on to work. When the hydrochloric acid concentration of the desalination liquid is lower than 0.1 mol / L, the automatic adding system will add acidic etching waste liquid to the desalination liquid collection cylinder, and discharge the low-acidity etching waste liquid to the liquid storage barrel. When the hydrochloric acid concentration of the concentrated solution is higher than 6 mol / L, pure water is automatically added to the concentrated solution collection cylinder, and high-concentration hydrochloric acid is discharged to the hydrochloric acid collection barrel, that is, hydrochloric acid ≥ 6 mol / L is recovered.

[0038] During the electrodialysis process, although H + 、Na +, Cu 2+ Under the action of electric field force, all cations can penetrate the cationic membrane, but due to different affinities with effective groups in the ion membrane (such as carboxyl, sulfonic acid, hydroxyl and other negative groups) and differences in the radius of the ions themselves, different cations have different degrees of difficulty in penetrating the ion membrane. + The penetration is the strongest, Na + Secondly, Cu 2+ The weakest. By utilizing the difference in permeability, the hydrochloric acid in the etching solution can be effectively separated. This difference in permeability is determined by the characteristics of the cations in the solution, and there is no mandatory requirement for the selective permeability of the cationic membrane.

[0039] The hydrochloric acid solution separated by electrodialysis concentration contains a small amount of Na + , Cu 2+ The working temperature of electrodialysis is 15-35℃. If the temperature is too low, the etching waste liquid in the desalination chamber is prone to crystallization; if the temperature is too high, the cationic membrane will + 、Na + , Cu 2+ The penetration selectivity will be significantly reduced, and the volatilization of hydrochloric acid in the concentration chamber will be aggravated. When the temperature is 23-35℃, H + Transmittance>94%, Cu 2+ Transmittance <2%.

[0040] In the present invention, the low-acid etching waste liquid obtained by electrodialysis refers to a solution having a hydrochloric acid concentration of ≤0.1 mol / L.

[0041] In the present invention, the mixing method of the low-acid etching waste liquid and the alkaline solution includes direct mixing or segmented adding and mixing, wherein the segmented adding and mixing can avoid the situation of violent splashing during the reaction process.

[0042] Among them, the temperature of the alkali solution in the mixture of the low-acid etching waste liquid and the alkali solution is 70-75°C, for example, it can be 70°C, 71°C, 72°C, 73°C, 74°C or 75°C, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0043] In the present invention, the temperature of the alkali solution and the mixing method of the alkali solution with the copper-containing solution are controlled to ensure that the newly generated copper hydroxide is quickly decomposed into copper oxide and water. If the copper hydroxide has formed a stable precipitate, its decomposition reaction is very slow, and there is no obvious reaction even if the temperature is raised to 100°C.

[0044] Wherein, the concentration of the alkali solution is 4-5mol / L, for example, it can be 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, 4mol / L, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0045] In the present invention, the alkali solution used includes sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, etc., or an organic base can also be used, but it is necessary to ensure that the copper oxide product can be obtained.

[0046] The end point of the mixing is that the pH value of the material is 10-14, for example, it can be 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5 or 14, but is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0047] Wherein, the temperature of the neutralization decomposition reaction is ≥70°C, for example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 130°C or 150°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0048] The neutralization and decomposition reaction time is ≥1 h, for example, 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0049] In the present invention, the solid-liquid separation method can be selected from common solid-liquid separation methods such as filter pressing, suction filtration, centrifugal separation, etc. The solid-liquid separation process can be accompanied by a cleaning operation to achieve solid-liquid separation and purify the copper oxide product at the same time.

[0050] The product obtained by solid-liquid separation can be dried and other operations can be performed according to needs.

[0051] Further, in order to illustrate the good preparation effect that can be achieved by the method for preparing copper oxide from PCB acid etching waste liquid provided by the present invention, an actual example is used for illustration, as follows:

[0052] Example 1

[0053] This embodiment provides a method for preparing copper oxide from PCB acid etching waste liquid, the method comprising:

[0054] In this embodiment, the main components of the PCB acid etching waste liquid used include: Cl -270g / L,Cu 2+ 130g / L, H + 2mol / L, the rest is Na + .

[0055] The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid;

[0056] The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and a copper oxide product is obtained by solid-liquid separation;

[0057] The operating temperature of the electrodialysis is 25°C; the membrane used in the electrodialysis is a cationic membrane (homogeneous membrane A81); the current density of the electrodialysis is 500A / m 2 ;

[0058] During the process of adding the low-acid etching waste liquid to the alkali solution, the temperature of the alkali solution is 72°C; the concentration of the alkali solution is 4.5 mol / L; the end point of the mixing is that the pH value of the material is 12; the temperature of the neutralization decomposition reaction is 100°C; and the time of the neutralization decomposition reaction is 2h.

[0059] Example 2

[0060] This embodiment provides a method for preparing copper oxide from PCB acid etching waste liquid, the method comprising:

[0061] In this embodiment, the main components of the PCB acid etching waste liquid used include: Cl - 250g / L,Cu 2+ 140g / L, H + 1.5mol / L, the rest is Na + .

[0062] The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid;

[0063] The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and a copper oxide product is obtained by solid-liquid separation;

[0064] The operating temperature of the electrodialysis is 30°C; the membrane used in the electrodialysis is a cationic membrane (cationic membrane A31); the current density of the electrodialysis is 525A / m 2 ;

[0065] The temperature of the alkali solution during the process of adding the low-acid etching waste liquid to the alkali solution is 74° C.; the concentration of the alkali solution is 4.8 mol / L; the end point of the mixing is that the pH value of the material is 13;

[0066] The temperature of the neutralization decomposition reaction is 90° C.; the time of the neutralization decomposition reaction is 3 hours.

[0067] Example 3

[0068] This embodiment provides a method for preparing copper oxide from PCB acid etching waste liquid, the method comprising:

[0069] In this embodiment, the main components of the PCB acid etching waste liquid used include: Cl - 250g / L,Cu 2+ 120g / L, H + 3.0mol / L, the rest is Na + .

[0070] The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid;

[0071] The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and a copper oxide product is obtained by solid-liquid separation;

[0072] The operating temperature of the electrodialysis is 35°C; the membrane used in the electrodialysis is a cationic membrane (homogeneous membrane A81); the current density of the electrodialysis is 450A / m 2 ;

[0073] The temperature of the alkali solution during the process of adding the low-acid etching waste liquid to the alkali solution is 75° C.; the concentration of the alkali solution is 5 mol / L; the end point of the mixing is that the pH value of the material is 14;

[0074] The temperature of the neutralization decomposition reaction is 80° C.; the time of the neutralization decomposition reaction is 1 hour.

[0075] Example 4

[0076] This embodiment provides a method for preparing copper oxide from PCB acid etching waste liquid, the method comprising:

[0077] In this embodiment, the main components of the PCB acid etching waste liquid used include: Cl - 200g / L,Cu 2+ 100g / L, H + 1mol / L, the rest

[0078] The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid;

[0079] The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and a copper oxide product is obtained by solid-liquid separation;

[0080] The operating temperature of the electrodialysis is 23°C; the membrane used in the electrodialysis is a cationic membrane (cationic membrane A31); the current density of the electrodialysis is 550A / m 2 ;

[0081] The temperature of the alkali solution during the process of adding the low-acid etching waste liquid to the alkali solution is 70° C.; the concentration of the alkali solution is 4 mol / L; the end point of the mixing is that the pH value of the material is 10;

[0082] The temperature of the neutralization decomposition reaction is 70° C.; the time of the neutralization decomposition reaction is 1.5 h.

[0083] Example 5

[0084] The only difference from Example 1 is that the operating temperature of the electrodialysis is 50°C.

[0085] Example 6

[0086] The only difference from Example 1 is that the operating temperature of the electrodialysis is 10°C.

[0087] Example 7

[0088] The only difference from Example 1 is that the temperature of the alkali solution is 50° C. during the process of adding the low-acid etching waste liquid into the alkali solution.

[0089] Example 8

[0090] The only difference from Example 1 is that the temperature of the alkali solution is 100° C. during the process of adding the low-acid etching waste liquid into the alkali solution.

[0091] Example 9

[0092] The only difference from Example 11 is that the neutralization decomposition reaction is not carried out.

[0093] Example 10

[0094] The only difference from Example 1 is that the temperature of the neutralization decomposition reaction is 50°C.

[0095] Embodiment 11

[0096] The only difference from Example 1 is that the pH value of the material in the neutralization decomposition reaction is 9.

[0097] The recovery index analysis was performed on the products obtained in the examples, and the results are shown in Table 1 below.

[0098] Table 1

[0099]

[0100]

[0101] As shown in Table 1, in the solution provided by the present invention, it can be seen from Examples 1-6 that the higher the temperature, the higher the H +The lower the penetration rate, the more obvious the effect is when the temperature is higher than 35℃. When the temperature is too low, the etching waste liquid in the desalination chamber is prone to crystallization. Therefore, under the premise of not forming crystals, electrodialysis should be carried out at a lower temperature as much as possible, and 23℃-35℃ is the ideal operating temperature.

[0102] It can be seen from Examples 7-11 that during the neutralization process, the temperature of the liquid caustic soda has a decisive influence on the purity of copper oxide, and the temperature of the liquid caustic soda should be maintained above 70° C. A pH value of the neutralization material lower than 10, a low neutralization decomposition reaction temperature, and a short neutralization decomposition reaction time will also reduce the purity of copper oxide.

[0103] It is stated that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0104] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0105] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0106] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing copper oxide from PCB acid etching waste liquid, characterized in that: The method comprises: The PCB acidic etching waste liquid is subjected to electrodialysis to obtain recovered acid and low-acid etching waste liquid; The low-acid etching waste liquid and the alkali solution are mixed and then subjected to a neutralization and decomposition reaction, and then a copper oxide product is obtained by solid-liquid separation; The operating temperature of the electrodialysis is ≤35°C.

2. The method according to claim 1, characterized in that The membrane used in the electrodialysis comprises a cationic membrane.

3. The method according to claim 1, characterized in that The operating temperature of the electrodialysis is 23-35°C.

4. The method according to claim 1, characterized in that The current density of the electrodialysis is 450-550A / m 2 .

5. The method according to claim 1, characterized in that The temperature of the alkali solution in the mixture of the low-acid etching waste liquid and the alkali solution is 70-75°C.

6. The method according to claim 1, characterized in that The concentration of the alkali solution is 4-5 mol / L.

7. The method according to claim 1, characterized in that The end point of the mixing is when the pH value of the material is 10-14.

8. The method according to claim 1, characterized in that The temperature of the neutralization decomposition reaction is ≥70°C.

9. The method according to claim 1, characterized in that The neutralization and decomposition reaction time is ≥1h.

10. The method according to claim 1, characterized in that The solid-liquid separation method includes one of pressure filtration, suction filtration or centrifugal separation.

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