A low-cost recovery treatment method for acid etching liquid waste based on ammonia lye neutralization reaction

Abstract

The present application relates to a kind of copper-containing acid etching liquid waste liquid processing method, especially to a kind of acid etching liquid waste liquid low-cost recovery processing method based on ammonia alkali neutralization reaction, using conventional alkali neutralization method to recover and process acid etching liquid waste liquid, and the alkali consumption is higher, and the processing cost is higher.For the above problems, the present application provides a kind of acid etching liquid waste liquid low-cost recovery processing method based on ammonia alkali neutralization reaction, which starts from the evaporation concentration of acid etching liquid waste liquid, to alkali neutralization reaction, filter pressing, micro-pressure reaction, deamination and finally evaporation crystallization etc., each link is carefully designed, ensure the efficiency and stability of the processing process, the present application uses ammonia as alkali neutralization alkali, and the cost is lower, and the ammonia used in the alkali neutralization reaction of the present application is also effectively reused by deamination reaction, significantly reduces the total amount of ammonia used in the processing process, further reduces the recovery processing cost of acid etching liquid waste liquid.

Description

Technical Field

[0001] This invention relates to the field of PCB acid etching solution recycling technology, specifically to a low-cost recycling method for acid etching solution waste liquid based on ammonia-alkali neutralization reaction. Background Technology

[0002] Printed circuit board etching solutions are mainly classified into acidic (HCl—H2O2), alkaline (NH3—NH4Cl), and traditional (HCl—FeCl3) etching solutions. Acidic etching waste mainly contains copper chloride and hydrochloric acid, with a copper content of approximately 160 g / L and a hydrochloric acid content of 100 g / L. The copper is mostly present in the form of CuCl2. In alkaline etching waste, the copper is mainly in the form of Cu(NH3)4. 2+ It exists in a copper-containing form, with a copper content of approximately 120 g / L. If these copper-containing waste liquids are not properly treated, they will not only waste copper resources but also cause serious environmental pollution.

[0003] Conventional alkaline neutralization methods only recover copper ions from acidic etching solutions. The remaining wastewater has a COD ≥ 5000 mg / L, an ammonia nitrogen value ≥ 20000 mg / L, dissolved solids that are a mixture of ammonium chloride and sodium chloride, and the solid products obtained from evaporation are mixed salts. The distilled water has a COD ≥ 400 mg / L, which does not meet the standards for discharge. Therefore, companies need to handle the wastewater themselves or outsource it to professional agencies, resulting in high treatment costs. Furthermore, conventional alkaline neutralization methods use alkalis such as sodium hydroxide, sodium carbonate, and ammonium hydroxide. Calculations show that if 1 ton of copper is recovered when recovering acidic etching solutions using these alkalis, and the remaining salts (sodium chloride, calcium chloride, ammonium chloride, etc.) are separated sequentially through evaporation and crystallization to obtain byproducts, the raw material and energy costs per ton of copper are no less than 11,000 yuan. Moreover, the alkali and washing water used in the recovery process are not recycled; large amounts of alkali and washing water need to be continuously added to the reactor during the process, further increasing the company's recovery costs. Summary of the Invention

[0004] The problem with existing technologies is that conventional alkali neutralization methods for recovering and treating acidic etching solutions require a high amount of alkali, resulting in high costs for waste liquid recovery and treatment. To address these issues, this invention provides a low-cost method for recovering and treating acidic etching solution waste based on an ammonia-alkali neutralization reaction, comprising the following steps:

[0005] (1) First, the acidic etching solution waste liquid is evaporated and concentrated to recover hydrochloric acid. The concentration of copper chloride in the waste liquid is increased to 1.5-2.2 times the original concentration to obtain a concentrated solution.

[0006] (2) Transfer the concentrate to the alkali neutralization reactor, add concentrated ammonia water to convert the divalent copper ions in the concentrate into Cu2(OH)3Cl precipitate, and obtain an alkali neutralization solution. The amount of concentrated ammonia water added is determined according to adjusting the pH of the concentrate to the range of 3.5-5.

[0007] (3) The alkali neutralization solution is filtered, and the filtrate is used as the mother liquor. The solid product obtained is thoroughly washed with pure water and dried to obtain Cu2(OH)3Cl product and product washing solution.

[0008] Preferably, the low-cost recycling and treatment method for acidic etching solution waste liquid based on ammonia-alkali neutralization reaction further includes the following treatment steps:

[0009] (1) The mother liquor obtained in step (3) is filtered to reduce the copper ion content to ≤3g / L, and the filtered mother liquor is obtained.

[0010] (2) Transfer all the product washing liquid and filtrate mother liquor obtained in step (3) to the ion exchange device to remove copper ions, and obtain an ion exchange solution with a copper ion content ≤2mg / L.

[0011] (3) The ion exchange liquid and lime milk are added to the micro-pressure evaporation reactor for a first deammoniation reaction. The amount of lime milk added is determined according to adjusting the pH of the solution to 11-12. After the reaction is completed, the gas phase is separated to obtain dilute ammonia water and high concentration ammonia water respectively. The liquid phase remaining after the first deammoniation is a salt mixture with NH3·H2O mass percentage ≤0.5%.

[0012] (4) After the calcium slag is removed by filtration, the residual liquid phase after primary ammonia removal is fed into the ammonia removal tower along with dilute ammonia water for secondary ammonia removal. The gas phase after ammonia removal is condensed to obtain high-concentration ammonia water. The residual liquid phase after secondary ammonia removal is a deammoniation liquid with a mass percentage of NH3·H2O ≤15 ppm. The deammoniation liquid is then subjected to MVR evaporation and crystallization and single-effect evaporation to obtain sodium chloride crystals and calcium chloride crystals, respectively.

[0013] Preferably, the distilled water produced during the MVR evaporation and crystallization separation to obtain sodium chloride crystals is reused as pure water, with ammonia nitrogen ≤8mg / L and COD ≤500mg / L in the distilled water.

[0014] Preferably, the distilled water produced by single-effect evaporation crystallization is reused as pure water, with ammonia nitrogen ≤8mg / L and COD ≤500mg / L in the distilled water.

[0015] Preferably, the MVR evaporation crystallization process is as follows:

[0016] First-stage evaporation: Using a falling film or forced evaporator, the TDS of the first-stage discharge is 25±5%, the boiling point rise of the obtained first-stage concentrate is 7±5℃, and the absolute vacuum pressure of the first-stage evaporation chamber is 67±20KPa.

[0017] Secondary evaporation: A forced evaporator is used to heat and concentrate the primary concentrate to a TDS of 48±5%. At this point, due to the salting-out effect, the sodium chloride content in the mother liquor will decrease to ≤2%, and sodium chloride crystals out, thus obtaining the secondary concentrate. The vacuum absolute pressure of the secondary evaporation chamber is 35±20 kPa, and the boiling point rise of the secondary concentrate at an absolute pressure of 35 kPa is 25±5℃.

[0018] Preferably, the mass concentration of the lime slurry is 22±5%.

[0019] Preferably, high-concentration ammonia water is recycled as concentrated ammonia water to the alkali neutralization reactor.

[0020] Preferably, the method for single-effect evaporation crystallization is as follows:

[0021] A forced evaporator was used to heat and concentrate the secondary concentrate to a calcium chloride mass content of 70±5% to obtain a tertiary concentrate. After cooling, calcium chloride crystals were obtained. The vacuum absolute pressure of the tertiary evaporation chamber was 101±20 kPa, and the boiling point rise of the tertiary concentrate at an absolute pressure of 101 kPa was 60±5℃.

[0022] Preferably, the mass concentration of the dilute ammonia solution is 1.5-3%.

[0023] Preferably, the mass concentration of the high-concentration ammonia water is 22±5%.

[0024] The present invention has the following beneficial effects:

[0025] (1) This invention can not only efficiently recover copper from waste liquid and convert it into Cu2(OH)3Cl product, realizing the reuse of copper resources and avoiding the waste of copper resources, but also after the copper is recovered, the ammonia water in the waste liquid can be further recovered through the post-processing step and reused in the alkali neutralization reaction, forming a closed-loop treatment system. This resource recycling mode improves the utilization rate of resources. Through evaporation concentration, alkali neutralization and multi-stage crystallization process, the efficient recovery of copper resources is achieved (the purity of the product reaches the first grade of national standard). At the same time, sodium chloride and calcium chloride crystals are separated from the waste liquid as by-products, improving the utilization rate of resources.

[0026] (2) By using ammonia water to replace traditional alkaline agents such as sodium hydroxide and sodium carbonate, and combining it with the recycling design of mother liquor, washing liquid and distilled water, the consumption of raw materials and energy is greatly reduced. According to calculations, the cost of copper recovery per ton is reduced by at least RMB 6,000 compared with conventional methods (the original cost is no less than RMB 11,000 / ton), which significantly improves the economic benefits of enterprises;

[0027] (3) By using micro-pressure evaporation and secondary deammoniation technology, the ammonia nitrogen content in the residual liquid phase after secondary deammoniation is reduced to ≤15ppm (far lower than ≥20000mg / L of conventional methods), and the COD is reduced to ≤500mg / L (≥5000mg / L of conventional methods). This allows the distilled water after subsequent evaporation and crystallization to be directly reused as pure water, and the waste liquid discharge meets environmental protection standards, reducing the risk of secondary pollution.

[0028] (4) This invention innovatively combines ion exchange, MVR evaporation and single-effect evaporation technologies to achieve deep removal of copper ions (≤2mg / L) and fractional crystallization of salts. At the same time, high-concentration ammonia water (22±5%) is obtained through gas phase separation and reused in the alkali neutralization reaction, which significantly improves the process stability and economy.

[0029] (5) All the distilled water produced by the evaporation crystallization process of the present invention is reused as washing water, which effectively reduces the total amount of external pure water used in the entire treatment process. In addition, the ammonia water used in the alkali neutralization reaction of the present invention is also effectively reused through the deammoniation reaction. The ammonia source in the initial reaction comes from alkaline etching solution or purchased ammonia water. In the later stage, ammonia balance is achieved through the deammoniation reaction of ammonium chloride, which solves the problem that the amount of alkaline etching solution is much less than that of acidic etching solution. There is no need to purchase ammonia water, which further reduces the cost of waste liquid treatment. Attached Figure Description

[0030] Figure 1 The present invention presents a low-cost recycling process for acidic etching solution waste liquid based on the ammonia-alkali neutralization reaction.

[0031] Figure 2 Application 2: Process flow diagram for the recycling and treatment of acidic etching solution waste liquid. Detailed Implementation

[0032] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0033] As per the instruction manual Figure 1 The diagram shown is a low-cost recycling process flow chart for acidic etching solution waste liquid based on an ammonia-alkali neutralization reaction, provided in Embodiment 1 of the present invention. The specific scheme is as follows:

[0034] A low-cost method for recycling and treating acidic etching solution waste liquid based on ammonia-alkali neutralization reaction, comprising the following steps:

[0035] (1) First, the acidic etching solution waste liquid is evaporated and concentrated to recover hydrochloric acid. The concentration of copper chloride in the waste liquid is increased to 1.5-2.2 times the original concentration to obtain a concentrated solution.

[0036] (2) Transfer the concentrate to the alkali neutralization reactor, add concentrated ammonia water to convert the divalent copper ions in the concentrate into Cu2(OH)3Cl precipitate, and obtain an alkali neutralization solution. The amount of concentrated ammonia water added is determined according to adjusting the pH of the concentrate to the range of 3.5-5.

[0037] (3) The alkali neutralization solution was filtered by pressure, and the filtrate was used as the mother liquor. The solid product obtained was washed thoroughly with pure water and dried to obtain Cu2(OH)3Cl product and pressure filtrate.

[0038] (4) The mother liquor obtained in step (3) is filtered to reduce the copper ion content to ≤3g / L to obtain the filtered mother liquor; the filtration device used is a three-in-one filtration, washing and drying integrated device or a belt vacuum filter.

[0039] (5) Transfer all the pressure filtration washing liquid and filtration mother liquor obtained in step (3) to the ion exchange device to remove copper ions, and obtain an ion exchange liquid with a copper ion content ≤2mg / L; The brand of the ion exchange resin in the ion exchange device used in this invention is Lanxiao Technology, and the model is lsc-850 resin.

[0040] (6) The ion exchange liquid and lime slurry are added to a micro-pressure evaporation reactor for a primary deammoniation reaction. The amount of lime slurry added is determined according to adjusting the pH of the solution to 11-12. After the reaction, the gas phase is separated to obtain dilute ammonia water and high-concentration ammonia water respectively. The remaining liquid phase after the primary deammoniation is a salt mixture with a mass percentage of NH3·H2O ≤0.5%. The micro-pressure evaporation reactor used for the primary deammoniation reaction is exactly the same as the "ammonium sulfate wastewater MVR evaporation deammoniation treatment device" described in Chinese Utility Model Patent 210419611U. The primary deammoniation process is the same as the process method described in paragraphs

[0098] to

[0111] of the specification of Chinese Utility Model Patent 210419611U. The only difference is that the "ammonium sulfate wastewater" is replaced by the "mixed solution formed by ion exchange liquid and lime slurry" in this invention. After the primary deammoniation reaction, the ammonia water collected in the second ammonia water tank is high-concentration ammonia water, and the ammonia water collected in the total ammonia water tank is dilute ammonia water.

[0041] (7) After the calcium slag is removed by filtration, the residual liquid phase after primary ammonia removal is fed into the ammonia removal tower along with dilute ammonia water for secondary ammonia removal. The gas phase after ammonia removal is condensed to obtain high-concentration ammonia water. The residual liquid phase after secondary ammonia removal is a deammoniation liquid with a mass percentage of NH3·H2O ≤15 ppm. The deammoniation liquid is then subjected to MVR evaporation and crystallization, single-effect evaporation followed by cooling and crystallization, filtration, and drying to obtain sodium chloride crystals and calcium chloride crystals, respectively. The secondary ammonia removal process is carried out according to the system and method described in paragraph

[0034] of the specification of Chinese invention patent CN 114229936 A. The ammonia removal tower in this invention is the distillation tower 1 described in paragraph

[0034] of the specification of Chinese invention patent CN 114229936 A. The difference between this invention and the content described in paragraph

[0034] of the specification of Chinese invention patent CN 114229936 A is that this invention uses "a mixture formed by filtering the residual liquid phase after primary ammonia removal and removing calcium slag and dilute ammonia water" instead of "wastewater with a mass concentration of 2%" described in paragraph

[0034] of the specification of Chinese invention patent CN 114229936 A.

[0042] The distilled water produced during the MVR evaporation and crystallization separation to obtain sodium chloride crystals is reused as pure water, with ammonia nitrogen ≤8mg / L and COD ≤500mg / L in the distilled water.

[0043] The distilled water produced by single-effect evaporation crystallization is reused as pure water, with ammonia nitrogen ≤8mg / L and COD ≤500mg / L in the distilled water.

[0044] The process of MVR evaporation crystallization is as follows:

[0045] First-stage evaporation: Using a falling film or forced evaporator, the TDS of the first-stage discharge is 25±5%, the boiling point rise of the obtained first-stage concentrate is 7±5℃, and the absolute vacuum pressure of the first-stage evaporation chamber is 67±20KPa.

[0046] Secondary evaporation: A forced evaporator is used to heat and concentrate the primary concentrate to a TDS of 48±5%. At this point, due to the salting-out effect, the sodium chloride content in the mother liquor will decrease to ≤2%, and sodium chloride crystals out, thus obtaining the secondary concentrate. The vacuum absolute pressure of the secondary evaporation chamber is 35±20 kPa, and the boiling point rise of the secondary concentrate at an absolute pressure of 35 kPa is 25±5℃.

[0047] The mass concentration of the lime slurry is 22±5%.

[0048] High-concentration ammonia water is recycled as concentrated ammonia water to the alkali neutralization reactor.

[0049] The method for single-effect evaporation crystallization is as follows:

[0050] A forced evaporator was used to heat and concentrate the secondary concentrate to a calcium chloride mass content of 70±5% to obtain a tertiary concentrate. After cooling, calcium chloride crystals were obtained. The vacuum absolute pressure of the tertiary evaporation chamber was 101±20 kPa, and the boiling point rise of the tertiary concentrate at an absolute pressure of 101 kPa was 60±5℃.

[0051] The mass concentration of the dilute ammonia solution is 1.5-3%.

[0052] The mass concentration of the high-concentration ammonia water is 22±5%.

[0053] Application 1

[0054] According to the above processing technology, this invention treats specific acidic etching solution waste liquid, where the density of the acidic etching solution used is 1.28 g / cm³. 3 The COD value was 11285 mg / L, the ammonia nitrogen content was 54.6 mg / L, the mass concentration of copper chloride was 21.954%, the mass concentration of sodium chloride was 8.6763%, and the mass concentration of HCl was 5.866%. Calculations show that to recover 1 ton of copper, the total amount of concentrated ammonia water used is 2.242 tons, the actual amount of calcium hydroxide with a purity of 90% is 1.5 tons, and the total amount of pure water used is (5.66 tons). The total energy and material cost for waste liquid treatment is (0.036) million yuan, and the cost of recovering each ton of copper is (0.36) million yuan. After recovery and treatment, the purity of the obtained calcium chloride is ≥72%, the purity of sodium chloride is ≥95%, and the copper content of Cu2(OH)3Cl is ≥58.3% (meeting national standards).

[0055] Application 2

[0056] Sodium hydroxide is used as the base for the neutralization reaction, and the acidic etching solution in Application 1 is subjected to conventional recovery treatment (as per the instruction manual). Figure 2 (As shown), the specific steps are as follows:

[0057] (1) First, the acidic etching solution waste liquid is evaporated and concentrated to recover hydrochloric acid. The concentration of copper chloride in the waste liquid is increased to 1.5-2.2 times the original concentration to obtain a concentrated solution.

[0058] (2) Transfer the concentrate to the alkali neutralization reactor, add sodium hydroxide, and convert all the divalent copper ions in the concentrate into copper hydroxide precipitate to obtain an alkali neutralization solution;

[0059] (3) The alkali neutralization solution is filtered, and the filtrate is used as the mother liquor for pressure filtration. The solid product obtained is thoroughly washed with pure water and dried to obtain Cu(OH)2 product. The washing liquid is used as the washing liquid for pressure filtration.

[0060] (4) The filter washing liquid and filter mother liquor were transferred to the MVR evaporator crystallizer for evaporation, crystallization, filtration, and drying to obtain sodium chloride. The remaining filtrate was dried at low temperature to obtain dried product. All distilled water obtained from the evaporation process and the low temperature drying process was reused as washing water. The process parameters for the low temperature drying process were: drying at an absolute pressure of 10±5 kPa.

[0061] Calculations show that to recover 1 ton of copper using Application 2, the total amount of 32% sodium hydroxide aqueous solution used is 4.64 tons, and the total amount of pure water used is 5.66 tons. The total cost of waste liquid treatment is ≥0.096 million yuan, and the cost of recovering each ton of copper is 0.96 million yuan. After recovery and treatment, the purity of the obtained sodium chloride is approximately 95%, and the purity of Cu(OH)2 is 100%.

[0062] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A low-cost method for recycling and treating acidic etching solution waste liquid based on ammonia-alkali neutralization reaction, characterized in that, The following processing steps are included: (1) First, the acidic etching solution waste liquid is evaporated and concentrated to recover hydrochloric acid. The concentration of copper chloride in the waste liquid is increased to 1.5-2.2 times the original concentration to obtain a concentrated solution. (2) Transfer the concentrate to the alkali neutralization reactor, add concentrated ammonia water to convert the divalent copper ions in the concentrate into Cu2(OH)3Cl precipitate, and obtain an alkali neutralization solution. The amount of concentrated ammonia water added is determined according to adjusting the pH of the concentrate to the range of 3.5-5. (3) The alkali neutralization solution was filtered, and the filtrate was used as the mother liquor. The solid product obtained was washed thoroughly with pure water and dried to obtain Cu2(OH)3Cl product and product washing solution. (4) The mother liquor obtained in step (3) is filtered to reduce the copper ion content to ≤3g / L, and the filtered mother liquor is obtained. (5) Transfer all the product washing liquid and filtrate mother liquor obtained in step (3) to the ion exchange device to remove copper ions, and obtain an ion exchange solution with a copper ion content ≤2mg / L. (6) Add the ion exchange liquid and lime milk to the micro-pressure evaporation reactor to carry out a primary deammoniation reaction. The amount of lime milk added is determined according to adjusting the pH of the solution to 11-12. After the reaction is completed, the gas phase is separated to obtain dilute ammonia water and high concentration ammonia water respectively. The liquid phase remaining after the primary deammoniation is a salt mixture with a mass percentage of NH3·H2O ≤0.5%. (7) After the calcium slag is removed by filtration, the residual liquid phase after primary ammonia removal is fed into the ammonia removal tower along with dilute ammonia water for secondary ammonia removal. The gas phase after ammonia removal is condensed to obtain high-concentration ammonia water. The residual liquid phase after secondary ammonia removal is a deammoniation liquid with a mass percentage of NH3·H2O ≤15 ppm. The deammoniation liquid is then subjected to MVR evaporation and crystallization and single-effect evaporation to obtain sodium chloride crystals and calcium chloride crystals, respectively. The process of MVR evaporation crystallization is as follows: First-stage evaporation: Using a falling film or forced evaporator, the TDS of the first-stage discharge is 25±5%, the boiling point rise of the obtained first-stage concentrate is 7±5℃, and the absolute vacuum pressure of the first-stage evaporation chamber is 67±20KPa. Secondary evaporation: A forced evaporator is used to heat and concentrate the primary concentrate to a TDS of 48±5%. At this time, due to the salting-out effect, the sodium chloride content in the mother liquor will decrease to ≤2%, and sodium chloride crystals out, thus obtaining the secondary concentrate. The vacuum absolute pressure of the secondary evaporation chamber is 35±20 kPa, and the boiling point rise of the secondary concentrate at an absolute pressure of 35 kPa is 25±5℃. High-concentration ammonia water is recycled as concentrated ammonia water to the alkali neutralization reactor; The method for single-effect evaporation crystallization is as follows: A forced evaporator was used to heat and concentrate the secondary concentrate to a calcium chloride mass content of 70±5% to obtain a tertiary concentrate. After cooling, calcium chloride crystals were obtained. The vacuum absolute pressure of the tertiary evaporation chamber was 101±20 kPa, and the boiling point rise of the tertiary concentrate at an absolute pressure of 101 kPa was 60±5℃.

2. The low-cost recycling and treatment method for acidic etching solution waste liquid based on ammonia-alkali neutralization reaction according to claim 1, characterized in that, The distilled water produced during the MVR evaporation and crystallization separation of sodium chloride crystals is reused as pure water.

3. The low-cost recycling and treatment method for acidic etching solution waste liquid based on ammonia-alkali neutralization reaction according to claim 1, characterized in that, The distilled water produced by single-effect evaporation crystallization is reused as pure water.

4. A low-cost recycling and treatment method for acidic etching solution waste liquid based on ammonia-alkali neutralization reaction according to claim 1, characterized in that, The mass concentration of the lime slurry is 22±5%.

5. A low-cost recycling and treatment method for acidic etching solution waste liquid based on ammonia-alkali neutralization reaction according to claim 1, characterized in that, The mass concentration of the dilute ammonia solution is 1.5-3%.

6. A low-cost recycling and treatment method for acidic etching solution waste liquid based on ammonia-alkali neutralization reaction according to claim 1, characterized in that, The mass concentration of the high-concentration ammonia water is 22±5%.

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