Neutralization and utilization method of acidic etching waste liquid

Abstract

The invention provides a neutralization and utilization method of an acidic waste etching solution. The method comprises the following steps: mixing the acidic etching waste liquid with an ammonium bicarbonate solution; in the mixing process, the mixing temperature is controlled to be 40-60 DEG C, the pH value is adjusted to be 3.5-4.5, and slurry is obtained; separating the slurry to obtain copper oxychloride wet crystals and an ammonium chloride crude product solution; carrying out dechlorination treatment on the copper oxychloride wet crystals by using an alkaline solution, and filtering to obtain a copper oxide filter cake and chloride waste liquid; the temperature of the dechlorination treatment is 70-90 DEG C; performing post-treatment on the copper oxide filter cake to obtain copper sulfate; and carrying out precipitation treatment on the ammonium chloride crude product solution to obtain an ammonium chloride finished product solution. Wherein the step S3 and the step S4 have no sequence. According to the method, electroplating-grade copper sulfate and industrial-grade ammonium chloride products are prepared by using ammonium bicarbonate and realizing full utilization of anions and cations in the acidic etching waste liquid.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment in the printed circuit board industry, and specifically relates to a method for neutralizing and utilizing acidic etching waste liquid. Background Art

[0002] As the foundation of the electronic manufacturing industry, the printed circuit board industry generates a large amount of etching waste liquid, mainly including three categories: acidic etching waste liquid, alkaline etching waste liquid, and micro-etching waste liquid. The daily national output is about 4,000 tons. With the improvement of printed circuit board technology and the stricter supervision of ammonia nitrogen in enterprise drainage by the national environmental protection department, most circuit board enterprises have no longer chosen alkaline etching process technology; most of the old production lines using alkaline etching solution as a reagent have also been technically modified and equipped with an online recycling system, and the amount of alkaline etching waste liquid waiting to be treated in the market has decreased significantly.

[0003] Traditional hazardous waste resource utilization enterprises generally use the "treating waste with waste" process route of jointly treating acidic and alkaline etching solutions to treat etching waste liquid to prepare basic copper chloride products and by-product ammonium chloride. When the received alkaline etching solution in the market is insufficient, ammonia water is purchased to maintain the original process production. On the one hand, the addition of ammonia water not only requires additional funds for purchasing auxiliary materials, but its storage in the factory also needs to be managed as an explosive; on the other hand, the general concentration of ammonia water is 18%, and the concentration of ammonium chloride filtrate produced by the original process also drops significantly, and the evaporation cost at the back end increases with the addition of ammonia water.

[0004] When the existing acidic and alkaline etching waste liquid and alkaline etching waste liquid are co-treated, basic copper chloride wet crystals and ammonium chloride solution containing a small amount of copper ions are produced after the neutralization reaction. Ion exchange resin is used to remove copper ions in the ammonium chloride solution, and the ion exchange resin is regenerated by high-acid backwashing, and the treatment facilities are large and the operation is complex.

[0005] When it is difficult to receive alkaline etching solution in the market and the competition among hazardous waste disposal enterprises becomes increasingly fierce, in order to establish a better new process for comprehensive utilization of acidic etching waste liquid, considering from the aspects of auxiliary material purchase, treatment process, and operation convenience, a new process that can produce higher-value products is necessarily required to achieve the process purpose of the original process. Summary of the Invention

[0006] In order to overcome the defects of high cost, complex operation, and low product quality in the existing acidic etching waste liquid treatment process, the present invention provides a method for neutralizing and utilizing acidic etching waste liquid. This method realizes the full utilization of anions and cations in acidic etching waste liquid by using ammonium bicarbonate; ammonium sulfide is used to remove impurity ions in ammonium chloride solution to produce ammonium chloride products. The process of the present invention can make the comprehensive recovery rate of copper reach more than 99.8%, and prepare electroplating-grade copper sulfate and industrial-grade ammonium chloride products.

[0007] The present invention solves the above problems through the following technical solutions:

[0008] The present invention provides a method for neutralizing and utilizing acidic etching waste liquid, which comprises the following steps:

[0009] S1. Mix the acidic etching waste liquid with ammonium bicarbonate solution; during the mixing process, control the mixing temperature at 40 - 60 °C and adjust the pH value to 3.5 - 4.5 to obtain a slurry;

[0010] S2. Separate the slurry to obtain wet cupric oxychloride crystals and a crude ammonium chloride solution;

[0011] S3. Use an alkaline solution to perform dechlorination treatment on the wet cupric oxychloride crystals, and filter to obtain cupric oxide filter cake and chloride waste liquid; the temperature of the dechlorination treatment is 75 - 90 °C;

[0012] Then perform post - treatment on the cupric oxide filter cake to obtain copper sulfate;

[0013] S4. Perform precipitation treatment and filtration on the crude ammonium chloride solution to obtain a finished ammonium chloride solution; the reagent for the precipitation treatment is a saturated ammonium sulfide solution;

[0014] Among them, steps S3 and S4 have no sequence.

[0015] In the present invention, by mixing ammonium bicarbonate with the acidic etching waste liquid, a relatively mild neutralization reaction can occur, avoiding production risks due to violent reactions; moreover, a high copper content can be maintained in the wet cupric oxychloride crystals, and the entrainment of carbonate in the wet cupric oxychloride crystals can also be reduced.

[0016] In step S1 of the present invention, when the pH value during the mixing process is too low, the wet cupric oxychloride crystals in the slurry are difficult to filter, and a large amount of chloride ions will be entrained; when the pH value during the mixing process is too high, the filtration performance of the wet cupric oxychloride crystals in the slurry will be better, but more copper ions will be contained in the crude ammonium chloride solution, increasing the impurity removal cost of the subsequent crude ammonium chloride solution.

[0017] In step S1 of the present invention, the addition amount of the ammonium bicarbonate solution can be determined according to the adjustment of the pH value during the mixing process.

[0018] In some embodiments, in step S1, the mixing method includes: adding the acidic etching waste liquid to the ammonium bicarbonate solution.

[0019] In step S1 of the present invention, when the mixing temperature is too low, the wet cupric oxychloride crystals produced are difficult to filter due to poor crystal form; when the mixing temperature is too high, ammonium bicarbonate tends to decompose, reducing the effect of the neutralization reaction, and also increasing energy consumption.

[0020] In a specific embodiment, in step S1, the temperature of the ammonium bicarbonate solution is 40 to 60 °C, for example, 50 °C.

[0021] In some embodiments, in step S1, the mixing process is carried out under constant temperature conditions.

[0022] In a specific embodiment, in step S1, the ammonium bicarbonate solution is a supersaturated suspension prepared from ammonium bicarbonate solid and a solvent; the solvent includes tap water or the crude ammonium chloride solution in step S2.

[0023] Among them, ammonium bicarbonate is a white crystal that is easily soluble in water, has a slight ammonia smell, and the converted ammonium content is 22.8%. Its unit ammonium procurement cost is 40% lower than that of ammonia water. Compared with ammonia water, it is more convenient for transportation and storage. Its dissolution process in water is a strong endothermic process, and when its solution is slightly acidic, the ammonia smell is significantly reduced.

[0024] In step S1 of the present invention, those skilled in the art should understand that the acidic etching waste liquid is conventional in the art, which contains copper chloride, and the copper ions in the copper chloride need to be recycled.

[0025] In some embodiments, the acidic etching waste liquid specifically refers to a strongly acidic waste liquid produced in the PCB printed circuit board industry, which contains Cu, Cl, Na, and Fe elements.

[0026] In some embodiments, in step S1, the density of the acidic etching waste liquid is 1 to 1.3 g / cm 3 .

[0027] In some embodiments, in step S1, the COD value of the acidic etching waste liquid is 3000 to 15000 ppm.

[0028] In some embodiments, in step S1, the acidity of the acidic etching waste liquid is 1 to 6 mmol / g.

[0029] In step S1 of the present invention, during the mixing process, an alkaline etching waste liquid can also be introduced to replace part of the ammonium bicarbonate solution.

[0030] In some embodiments, in step S2, the separation method includes suction filtration.

[0031] In step S2 of the present invention, the crude ammonium chloride solution will contain copper ions.

[0032] In some embodiments, in step S2, when the copper content in the crude ammonium chloride solution ≥ 1000 ppm, the crude ammonium chloride solution is returned to step S1 to be mixed and reacted with the acidic etching waste liquid.

[0033] In step S2 of the present invention, the residual amount of copper ions in the crude ammonium chloride solution can be preliminarily evaluated by monitoring the color of the crude ammonium chloride solution; when the crude ammonium chloride solution is light blue, the copper content is < 1000 ppm, and when the crude ammonium chloride solution is bluish-purple, the copper content ≥ 1000 ppm.

[0034] In step S3 of the present invention, the dechlorination process converts the wet cupric oxychloride crystals into cupric oxide precipitates and separates copper from chlorine.

[0035] In some embodiments, in step S3, the alkaline solution includes liquid caustic soda.

[0036] In a specific embodiment, the concentration of the liquid caustic soda is 30%, where % refers to the mass ratio of NaOH to the total mass of the liquid caustic soda.

[0037] In a specific embodiment, the mass ratio of the addition amount of the liquid caustic soda to the mass of the wet cupric oxychloride crystals is (0.5 - 0.6):1.

[0038] In some embodiments, in step S3, the temperature of the dechlorination process is 85 - 90 °C.

[0039] In some embodiments, in step S3, the time of the dechlorination process is 20 - 40 min.

[0040] In some embodiments, in step S3, the end-point pH value of the dechlorination process of the wet cupric oxychloride crystals is controlled to be 10 - 12.

[0041] In a specific embodiment, after the pH value of the wet cupric oxychloride crystals reaches the end-point pH value, the reaction is continued for 15 min to completely convert the wet cupric oxychloride crystals.

[0042] In some embodiments, in step S3, after the filtration step, the cupric oxide filter cake is rinsed.

[0043] In some embodiments, in step S3, the post-treatment includes steps of acidolysis treatment, hot filtration, evaporation and concentration crystallization; among them, the post-treatment process satisfies one or more of the following conditions:

[0044] ① The reagent for the acidolysis treatment is a sulfuric acid solution;

[0045] ② The end-point pH value of the acidolysis treatment of the cupric oxide filter cake is controlled to be 4 - 5;

[0046] ③ The temperature of the acidolysis treatment is 60 - 80 °C.

[0047] In a specific embodiment, the source of the sulfuric acid solution can be waste sulfuric acid from a chip enterprise.

[0048] In a specific embodiment, the sulfuric acid solution can be composed of 70% sulfuric acid and water, and the mass ratio of the sulfuric acid to water is 1:(3 - 4).

[0049] In step S3 of the present invention, during the post-treatment process, the concentration of copper ions in the solution at the end of the post-treatment is controlled to be no more than 80 g / L to prevent the precipitation of copper ions due to natural crystallization.

[0050] In step S3 of the present invention, the copper sulfate is an electroplating-grade copper sulfate product.

[0051] In some embodiments, in step S4, the precipitation treatment method includes: immersively dripping the precipitation treatment reagent into the crude ammonium chloride solution.

[0052] In some embodiments, in step S4, the addition amount of the saturated ammonium sulfide solution is 0.5%, where % is the volume ratio of the saturated ammonium sulfide solution to the total volume of the crude ammonium chloride solution.

[0053] In step S4 of the present invention, ammonium sulfide in the saturated ammonium sulfide solution acts as a precipitant to precipitate heavy metal ions.

[0054] In step S4 of the present invention, by using ammonium sulfide to precipitate various residual metal ions in the crude ammonium chloride solution, it is avoided to use ion exchange resin to treat the crude ammonium chloride solution containing a small amount of copper ions. This treatment method is simpler in operation and further reduces the system investment.

[0055] In step S4 of the present invention, through the precipitation treatment, the crude ammonium chloride solution quickly changes from blue to black.

[0056] In some embodiments, in step S4, the precipitation treatment time is 10 - 25 min.

[0057] In step S4 of the present invention, in the filtration process, there is no odor throughout the process, and a nearly colorless and transparent ammonium chloride finished product solution and copper sulfide precipitate are obtained.

[0058] In some embodiments, in step S4, the ammonium chloride finished product solution is successively subjected to evaporation, concentration, and crystallization to obtain ammonium chloride solid.

[0059] In step S4 of the present invention, the ammonium chloride solid is an industrial-grade ammonium chloride product.

[0060] In the present invention, when there is a shortage of alkaline etching waste liquid available in the market for the neutralization and utilization method of the acidic etching waste liquid, it is not necessary to purchase ammonia water externally, and it will not increase the evaporation treatment amount of ammonium chloride solution at the back end of the system, and still can be compatible with the co-treatment requirements of a small amount of alkaline etching waste liquid;

[0061] Based on the common knowledge in the art, the above preferred conditions can be combined arbitrarily to obtain various preferred examples of the present invention.

[0062] The reagents and raw materials used in the present invention are all commercially available.

[0063] The positive and progressive effects of the present invention are as follows:

[0064] 1. In the present invention, ammonium bicarbonate is used to replace the alkaline etching waste liquid and carry out a neutralization reaction with the acidic etching waste liquid, so that the comprehensive recovery rate of copper can reach more than 99.8%, and electroplating-grade copper sulfate and industrial-grade ammonium chloride products can be produced;

[0065] 2. The present invention provides a comprehensive utilization process for the overall resource utilization of cations and anions with wide adaptability, low treatment cost, simple operation process, good operation environment, easily available applied reagents, and high product value for the acidic etching waste liquid. Its resource utilization products are electroplating-grade copper sulfate and national standard ammonium chloride solid, and the discharged wastewater is the condensate of the crystallization evaporation fraction, meeting the requirements for direct discharge to a general sewage treatment station / plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is the process flow diagram of the neutralization and utilization method of the acidic etching waste liquid in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0067] The ammonium salt neutralization and utilization method of the acidic etching waste liquid is further described in detail with examples as shown in the following drawings. The examples do not constitute a limitation to the present invention:

[0068] Table 1 shows the composition and properties of the acidic etching waste liquid in the following Example 1 and Comparative Examples 1-4.

[0069] Table 1

[0070]

[0071] Example 1

[0072] This example provides a neutralization and utilization method for acidic etching waste liquid, Figure 1 It is the process flow diagram of the neutralization and utilization method of the acidic etching waste liquid in this example.

[0073] The neutralization and utilization method of the acidic etching waste liquid includes the following steps:

[0074] S1: Take 1000 g of ammonium bicarbonate solid and place it in a 5 L beaker. After adding water, dissolve it at a constant temperature of 50 °C in a water bath. Slowly add the acidic etching waste liquid to the ammonium bicarbonate solution, and control the mixing temperature at 50 °C. Take an appropriate amount of the reaction slurry with a small beaker and let it stand. Observe that the color of the supernatant turns light blue. At this time, measure the pH of the solution. When the pH shows approximately 4.0, stop adding the acidic etching waste liquid to stop the neutralization reaction and obtain a slurry.

[0075] S2: Let the slurry obtained in step S1 stand for 5 - 10 min, and filter it with a Buchner funnel. Obtain copper oxychloride wet crystals and a crude ammonium chloride solution containing a small amount of copper. The solution is transparent and light blue. This crude ammonium chloride solution can be used as the solvent for dissolving the ammonium bicarbonate solid in step S1.

[0076] S3: Add 0.5 - 0.6 times the mass of 30% liquid caustic soda to the copper oxychloride wet crystals obtained in step S2, heat up to 90 °C and carry out high-temperature conversion for 40 min for dechlorination treatment. Control the end-point pH value of the dechlorination treatment within the range of 10 - 12. Filter while it is hot to obtain a copper oxide filter cake and a sodium chloride waste liquid.

[0077] S4: Wash the copper oxide filter cake obtained above, and acidify and redissolve it at 80 °C with 70% sulfuric acid of equal mass and tap water 4 times the mass of the sulfuric acid. Filter out the insoluble matter while it is hot. Control the pH of the redissolved clear liquid between 4 - 5 by appropriately adding copper oxide mud. Filter to obtain a pure copper sulfate solution and a small amount of acid-insoluble matter. Simply evaporate and concentrate the pure copper sulfate solution to obtain 720 g of copper sulfate product. The sample submission for testing and analysis report is shown in Table 2 below. Table 2 shows the composition of this copper sulfate product.

[0078] Table 2

[0079]

[0080]

[0081] S5: Take 2.5 L of the light blue copper ion-containing crude ammonium chloride solution obtained by filtration in step S2. Use a pipette to immerse and drip 12.5 mL of saturated ammonium sulfide solution prepared into the copper ion-containing crude ammonium chloride solution. Stir appropriately with a glass rod. The solution quickly turns from light blue to a solid suspension with black suspended matter. Continue to stir and react for 25 min. Filter to obtain a small amount of black filter cake as copper sulfide. The filtrate is colorless as the finished ammonium chloride solution. Take the finished ammonium chloride solution for sample analysis as shown in Table 3 below. Table 3 shows the elemental composition of the finished ammonium chloride solution.

[0082] Table 3

[0083]

[0084] S6: Evaporate, concentrate and crystallize the ammonium chloride finished product solution obtained in step S5 to obtain industrial-grade ammonium chloride solid. The sample analysis report of the ammonium chloride solid is shown in Table 4 below, and Table 4 shows the composition of the ammonium chloride solid.

[0085] Table 4

[0086]

[0087]

[0088] As can be seen from Tables 1-4 above, the method of this embodiment can produce electroplating-grade copper sulfate and industrial-grade ammonium chloride products.

[0089] In addition, adopting the above solution can make the comprehensive recovery rate of copper reach more than 99.8%.

[0090] This embodiment provides a comprehensive utilization process for the overall resource utilization of anions and cations with wide adaptability, low treatment cost, simple operation process, good operation environment, easy availability of applied reagents, and high product value for acidic etching waste liquid. Its resource utilization products are electroplating-grade copper sulfate and national standard ammonium chloride solid, and the discharged wastewater is the condensate of the crystallization evaporation fraction, meeting the requirements for direct discharge to a general sewage treatment station / plant.

[0091] Comparative Example 1:

[0092] This comparative example discloses a method for neutralization and utilization of acidic etching waste liquid.

[0093] This comparative example adjusted step S1 of Example 1. Specifically:

[0094] According to the operation steps of Example 1, the water bath environment involved in step S1 was removed. When preparing ammonium bicarbonate, its temperature was lower than 40°C due to the endothermic process; the mixing temperature of the acidic etching waste liquid and the ammonium bicarbonate solution was also lower than 40°C; although the acidic etching waste liquid could still complete the reaction with the ammonium bicarbonate solution, the suspension after the reaction could not be filtered, and the slurry could not be naturally settled and separated.

[0095] Therefore, electroplating-grade copper sulfate and national standard ammonium chloride solid cannot be obtained through the subsequent process of Example 1.

[0096] Comparative Example 2:

[0097] This comparative example discloses a method for neutralization and utilization of acidic etching waste liquid.

[0098] This comparative example adjusted step S1 of Example 1. Specifically:

[0099] According to the operation steps of Example 1, the water bath environment in step S1 was raised to 70°C, and it was found that the entire operation environment was filled with the smell of decomposed ammonia when the acidic etching waste liquid was not added, and the operation environment was extremely poor.

[0100] Due to the too high mixing temperature, ammonium bicarbonate decomposed, seriously affecting the operation environment and reducing the neutralization effect of ammonium bicarbonate.

[0101] Comparative Example 3:

[0102] This comparative example discloses a method for neutralizing and utilizing acidic etching waste liquid.

[0103] This comparative example adjusted steps S1, S2, and S5 of Example 1. Specifically:

[0104] According to the operation process of step S1 in Example 1, the reaction end point of neutralizing acidic etching waste liquid with ammonium bicarbonate was controlled to a pH value of about 5, and the addition of acidic etching waste liquid was stopped;

[0105] According to the operation process of step S2 in Example 1, the supernatant (crude ammonium chloride solution containing a small amount of copper) obtained after suction filtration was sapphire blue; the separation degree of the filter cake and the filtrate was detected, and the residual copper amount in the filtrate was 3400 ppm;

[0106] According to the operation process of step S5 in Example 1, a 4% volume of saturated ammonium sulfide solution was added to remove the surplus metal ions in the sapphire blue ammonium chloride filtrate. Although the color of the filtrate became clear, due to the excessive addition amount of ammonium sulfide, its smell in the solution was very strong, making it difficult to operate and affecting the operation environment.

[0107] Comparative Example 4:

[0108] This comparative example discloses a method for neutralizing and utilizing acidic etching waste liquid.

[0109] This comparative example adjusted step S3 of Example 1. Specifically:

[0110] According to the operation process of step S3 in Example 1, the temperature for raising the temperature of cupric oxychloride added with 30% liquid caustic soda in step S3 was set to 70°C (i.e., the dechlorination treatment temperature), and the reaction was continuously stirred for 1 h. It was found that the slurry was still light blue, and only a small amount of gray appeared. The slurry after conversion was difficult to filter, and the further separation of copper and chlorine could not be achieved. Therefore, electroplating-grade copper sulfate could not be obtained through the subsequent process of Example 1.

[0111] It should be noted that the implementation schemes provided by the present invention are only an optimized way to achieve the effects and do not form a limitation on the invention itself.

[0112] The process objectives, basic principles, main features and advantages of the present invention have been described above. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the claimed invention.

Claims

1. A method for neutralizing and utilizing acidic etching waste liquid, characterized in that: It includes the following steps: S1, mixing the acidic etching waste liquid with the ammonium bicarbonate solution; during the mixing process, controlling the mixing temperature to 40-60° C., and adjusting the pH value to 3.5-4.5 to obtain a slurry; S2, separating the slurry to obtain wet copper oxychloride crystals and a crude ammonium chloride solution; S3, using an alkaline solution to dechlorinate the copper oxychloride wet crystals, filtering to obtain a copper oxide filter cake and a chloride waste liquid; the temperature of the dechlorination treatment is 75-90° C.; The copper oxide filter cake is then post-treated to obtain copper sulfate; S4, subjecting the crude ammonium chloride solution to precipitation treatment and filtration to obtain a finished ammonium chloride solution; the reagent for the precipitation treatment is a saturated ammonium sulfide solution; There is no order of precedence for steps S3 and S4.

2. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, wherein: Step S1 satisfies one or both of the following conditions: ① The mixing method includes: adding the acidic etching waste liquid to the ammonium bicarbonate solution; ② The mixing process is carried out under constant temperature conditions.

3. The neutralization and utilization method of acidic etching waste liquid as claimed in claim 2, characterized in that: Step S1 satisfies one or both of the following conditions: ① The temperature of the ammonium bicarbonate solution is 40-60° C.; ② The ammonium bicarbonate solution is a supersaturated suspension prepared from ammonium bicarbonate solid and a solvent; the solvent includes tap water or the crude ammonium chloride solution in step S2.

4. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, wherein: In step S1, the acidic etching waste liquid satisfies one or more of the following conditions: ① The acidic etching waste liquid is a strong acidic waste liquid containing Cu, Cl, Na and Fe elements produced by the PCB printed circuit board industry; ② The density of the acidic etching waste liquid is 1 to 1.3 g / cm 3 ; ③ The COD value of the acidic etching waste liquid is 3000-15000ppm; ④ The acidity of the acidic etching waste liquid is 1 to 6 mmol / g.

5. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, wherein: In step S2, the separation method includes suction filtration.

6. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, wherein: In step S2, when the copper content in the crude ammonium chloride solution is ≥1000 ppm, the crude ammonium chloride solution is returned to step S1 to be mixed with the acidic etching waste liquid for reaction.

7. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, wherein: Step S3 satisfies one or more of the following conditions: ① The alkaline solution comprises liquid caustic soda; ② The temperature of the dechlorination treatment is 85-90°C; ③ The dechlorination treatment time is 20 to 40 minutes; ④ The endpoint pH value of the dechlorination treatment of the copper oxychloride wet crystals is controlled to be 10 to 12; ⑤ After the filtering step, the copper oxide filter cake is rinsed.

8. The method for neutralizing and utilizing acidic etching waste liquid according to claim 7, wherein: The concentration of the liquid caustic soda is 30%, where % refers to the proportion of the mass of NaOH to the total mass of the liquid caustic soda; The mass ratio of the added amount of the liquid alkali to the wet copper oxychloride crystals is (0.5-0.6):

1.

9. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, wherein: In step S3, the post-treatment includes the steps of acid hydrolysis, hot filtration, evaporation, concentration and crystallization; wherein the post-treatment process satisfies one or more of the following conditions: ① The reagent for the acid hydrolysis treatment is a sulfuric acid solution; ② The endpoint pH value of the acid hydrolysis treatment of the copper oxide filter cake is controlled to be 4 to 5; ③ The temperature of the acid hydrolysis treatment is 60-80°C.

10. The method for neutralizing and utilizing acidic etching waste liquid according to claim 1, characterized in that: Step S4 satisfies one or more of the following conditions: ① The precipitation treatment method includes: adding the precipitation treatment reagent dropwise into the crude ammonium chloride solution in an immersion manner; ② The amount of the saturated ammonium sulfide solution added is 0.5%, where % is the ratio of the volume of the saturated ammonium sulfide solution to the total volume of the crude ammonium chloride solution; ③ The precipitation treatment time is 10 to 25 minutes; ④ The ammonium chloride finished product solution is evaporated, concentrated and crystallized in sequence to obtain ammonium chloride solid.

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