Method for recycling and high-value utilization of electronic waste acid solution

Abstract

The application belongs to the technical field of comprehensive utilization of electronic waste acid liquid, and particularly relates to a method for high-value recycling of electronic waste acid liquid. The method comprises the following steps: first, neutralizing the electronic waste acid liquid with ammonia water to obtain ammonium dihydrogen phosphate, or reacting with iron salt or ferrous salt to prepare iron phosphate, and then cooling and suction filtering to obtain a solid product; then, the filtrate is chemically adsorbed with melamine derivative adsorbent to contain molybdenum compounds, and then suction filtering to obtain high-value high-purity molybdenum-containing compounds. The adsorbent can be repeatedly used for multiple times, thereby saving the process cost. The valuable phosphoric acid and molybdenum compounds in the electronic waste acid liquid are efficiently converted and extracted, and the waste of important chemical resources is reduced. The technology not only solves the increasingly serious electronic waste acid liquid pollution problem from the source, but also turns waste into treasure, increases the economic benefits of the society and enterprises, and has a green and sustainable application prospect.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization technology of electronic waste acid, specifically a method for high-value recycling and utilization of electronic waste acid. Background Technology

[0002] With the rapid development of my country's electronics industry, electronic manufacturing enterprises generate a large amount of waste acid from the processing of electronic components. Since 2012, the volume of industrial etching waste liquid in my country has maintained continuous growth. The main types of electronic waste acid include waste sulfuric acid, waste nitric acid, waste phosphoric acid, and waste hydrofluoric acid. Phosphoric acid is a very important chemical raw material. Electronic-grade phosphoric acid, due to its ultra-high purity, is widely used in wet etching and wet cleaning processes in the microelectronics industry, such as large-screen LCD displays and integrated circuits. The phosphoric acid content in etching waste liquid is very high (reaching 50%-65%). Direct discharge of waste acid not only seriously pollutes the environment but also causes a serious waste of resources. Phosphorus resources are mainly used in the fertilizer and power battery industries. Especially in the last decade or so, with the rapid development of electric vehicles in my country, lithium iron phosphate is used as the positive electrode in lithium battery production, making phosphorus resources increasingly scarce. The phosphoric acid in the aforementioned waste acid can be used as a supplementary raw material for lithium battery production. This significantly saves on the mining of non-renewable phosphorus resources, reduces waste and environmental pollution, achieving two goals at once.

[0003] In addition, etching waste liquid also contains a large number of metal ions. Currently, the main methods for treating this type of electronic waste acid liquid include the following: 1. Neutralization and precipitation method Generally, lime, carbide slag, and Ca(OH)2 are used to neutralize the pickling wastewater, generating calcium phosphate or other phosphate precipitates, increasing the pH of the wastewater, precipitating heavy metal ions, and separating the wastewater and sludge through solid-liquid separation. This method is simple to operate, but has significant drawbacks: it consumes large amounts of alkaline reagents, resulting in high treatment costs; it generates large amounts of hazardous solid waste (sludge), increasing the burden of subsequent disposal; it cannot achieve resource recovery of phosphoric acid, leading to a waste of phosphorus resources; and molybdenum is mixed into the sludge during neutralization, making further extraction difficult, often requiring stockpiling, which not only occupies a large amount of land but may also cause serious secondary pollution to groundwater resources. 2. Evaporation and Concentration Method Some dilute acid is recovered by heating and evaporating the water in waste acid. This method is extremely energy-intensive, and the release of volatile acids (such as nitric acid) during evaporation causes secondary pollution. At the same time, as the concentration of phosphoric acid increases, changes in the solubility of impurity metal ions (including molybdenum) may lead to scaling and clogging of the equipment. The phosphoric acid obtained after evaporation has low purity and is difficult to reuse directly in the production of high-end electronic-grade phosphoric acid. 3. Solvent extraction method Organic extractants (such as tributyl phosphate, trialkylamine, etc.) are used to selectively extract phosphoric acid or molybdenum. This method has good separation effect, but it has problems such as large organic solvent loss, easy emulsification of the extractant leading to phase separation difficulties, complex process flow, high equipment investment, and potential secondary pollution from organic residues in the raffinate. 4. Ion exchange method Anion exchange resins are used to adsorb molybdate or phosphate ions. This method is suitable for the deep purification of low-concentration solutions, but for high-concentration, high-ionic-strength electronic waste acid, the resin is easily saturated and susceptible to high-valence ion contamination, requiring frequent regeneration and resulting in low treatment efficiency, making large-scale industrial application difficult.

[0004] Therefore, developing a method that can efficiently convert and utilize phosphoric acid (to prepare high-value-added phosphoric acid products) from electronic waste acid and simultaneously extract molybdenum is of great significance for environmental protection, resource recycling economy, and industrial application prospects. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a method for the high-value recycling and utilization of electronic waste acid, aiming to turn waste into treasure, increase economic benefits, and solve the increasingly serious problem of waste acid discharge. This method achieves the conversion and utilization of phosphoric acid in waste acid by neutralizing ammonia water to obtain ammonium dihydrogen phosphate or reacting it with ferric or ferrous salts to prepare ferric phosphate. After crystallization and separation of the phosphate product, the molybdenum-containing compounds in the filtrate are subjected to efficient chemical adsorption with melamine derivative adsorbents and desorption with alkaline solution to obtain high-purity molybdenum-containing compounds.

[0006] To achieve the above-mentioned objectives, the specific technical solution adopted by this invention is as follows: A method for high-value recycling and utilization of electronic waste acid includes the following steps: S1: Add ammonia to the electronic waste acid liquid for neutralization to obtain a neutralized liquid; then cool and filter the neutralized liquid to obtain ammonium dihydrogen phosphate crystals and molybdenum-containing filtrate; or react the electronic waste acid liquid with ferric salts or ferrous salts, and then let it stand and filter to obtain solid iron phosphate and molybdenum-containing filtrate. S2: The molybdenum-containing filtrate obtained in S1 is chemically adsorbed using a melamine derivative adsorbent. After stirring, adsorption, cooling, filtration and washing, an adsorbent filter cake containing molybdenum compounds is obtained. S3: Add the molybdenum-containing adsorbent filter cake obtained in S2 to deionized water and mix well. Add alkaline solution to adjust the pH and stir to desorb. After filtration and washing, a high-purity molybdenum-containing compound filtrate is obtained, which is a high-value, high-purity molybdenum-containing compound. This achieves the separation of molybdenum-containing compounds from waste acid.

[0007] In a preferred embodiment of this application, in S1 of the method for high-value recycling of electronic waste acid, the pH is adjusted to 2-4, more preferably 3-4, during ammonia neutralization.

[0008] As a preferred embodiment of this application, in S1 of the method for high-value recycling of electronic waste acid, the neutralization liquid is gradually cooled in two stages: first, it is cooled to 30-35°C, and second, it is cooled to 10-15°C. The ammonium dihydrogen phosphate crystals precipitated in the two stages are separated by filtration, and finally, the obtained ammonium dihydrogen phosphate crystals are combined.

[0009] As a preferred embodiment of this application, in S1 of the method for high-value recycling of electronic waste acid, ferric salt or ferrous salt refers to soluble ferric salt or soluble ferrous salt, or sparingly soluble ferric salt or ferrous salt that can undergo a phase reaction to generate soluble ferric salt or soluble ferrous salt; specifically including ferric sulfate, ferric nitrate, ferrous sulfate, ferric hydroxide, ferrous hydroxide, ferrous carbonate, and ferrous oxalate, etc.

[0010] As a preferred embodiment of this application, in S1 of the method for high-value recycling of electronic waste acid, the temperature at which the electronic waste acid reacts with ferric salts or ferrous salts is 60-90°C, more preferably 65-80°C; the time is 1-3 h, more preferably 1.5-2 h; and the time for standing at room temperature is 2-6 h, more preferably 4-5 h.

[0011] As a preferred embodiment of this application, in S2 of the method for high-value recycling of electronic waste acid, the melamine derivative adsorbent includes melamine, alkyl-substituted melamine, melamine strong acid salt, melamine-formaldehyde resin cured product, melamine etherified resin cured product, and melamine alcoholamine derivatives, etc.

[0012] As a preferred embodiment of this application, in S2 of the method for high-value recycling of electronic waste acid, the melamine derivative adsorbent includes, but is not limited to, methyl melamine, benzomelamine, melamine sulfate, melamine phosphate, and hexamethylol melamine.

[0013] In a preferred embodiment of this application, in S2 of the method for high-value recycling of electronic waste acid, the temperature for stirring and adsorption is 60-80℃, more preferably 60-70℃; and the adsorption time is 4-7 h, more preferably 5-6 h.

[0014] In a preferred embodiment of this application, in step S3 of the method for high-value recycling of electronic waste acid, the alkaline solution includes inorganic alkaline compounds and organic alkaline compounds; the pH value is adjusted to 10-12.

[0015] In a preferred embodiment of this application, in S3 of the method for high-value recycling of electronic waste acid, the temperature for stirring desorption is 40-70°C, more preferably 55-65°C; and the time for stirring desorption is 2-6 h, more preferably 2.5-4 h.

[0016] In a preferred embodiment of this application, in S3 of the method for high-value recycling of electronic waste acid, the alkaline solution includes sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium methoxide, sodium methoxide, sodium tert-butoxide, and potassium tert-butoxide.

[0017] As a preferred embodiment of this application, any of the above methods, relative to the total amount of molybdenum in the electronic waste acid, achieves an adsorption rate of more than 90% and a desorption rate of more than 85% for molybdenum.

[0018] The working principle of this invention is: Melamine derivative adsorbents contain a 1,3,5-triazine ring and three amino groups (-NH2) in their molecular structure. The nitrogen atoms on the triazine ring and amino groups possess lone pairs of electrons, which can act as electron donors to coordinate with the empty orbitals of metal ions, forming coordinate bonds. This coordination interaction falls under the category of chemisorption, and its adsorption capacity is much greater than that of porous materials through physical adsorption. Therefore, melamine derivative adsorbent molecules can form stable melamine derivative-metal complexes with metal ions. Multiple nitrogen atoms in the molecule can coordinate with a single metal ion to form a cyclic chelate structure, resulting in strong adsorption stability. The more amino groups in the molecule, the more metal ions are coordinated, and the better the adsorption effect. Different derivatives have different substituent groups (e.g., methyl, hydroxymethyl), which affects the melting point and water solubility of the molecule. This affects the contact opportunity between the adsorbent and the metal ions, thus affecting the adsorption capacity of the metal ions. Since melamine derivatives have relatively poor water solubility, the resulting complexes also have low water solubility, thus achieving efficient separation and purification of metal ions from the liquid phase.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: (I) This invention achieves the complete conversion and utilization of phosphoric acid in waste acid liquid. The resulting ammonium dihydrogen phosphate can be used as agricultural fertilizer, or the resulting iron phosphate can be used in new energy batteries and other industries, with considerable economic value. At the same time, it avoids the resource waste and high energy consumption caused by the traditional lime neutralization method and vacuum distillation method for separating phosphoric acid, and has the advantages of simple process, low energy consumption and environmental protection.

[0020] (II) This invention simultaneously utilizes a chemical adsorption-desorption process with melamine derivative adsorbents to efficiently extract high-value molybdenum from waste acid; the molybdenum adsorption rate and desorption rate are greater than 90% and 85%, respectively. Furthermore, the adsorbent can be reused multiple times, achieving the recycling of both the metal element and the adsorbent. Compared to traditional methods for separating metal ions, such as precipitation and ion exchange, this method offers advantages such as high separation efficiency, simple process, low cost, and environmental friendliness.

[0021] (III) Through this invention, not only is the pollution of the environment caused by the discharge of waste acid reduced, but the waste acid is also turned into a valuable resource, reducing the waste of resources and bringing good economic and social benefits. Detailed Implementation

[0022] A method for high-value recycling and utilization of electronic waste acid includes the following steps: S1: The first method for utilizing phosphoric acid in waste acid is through neutralization with ammonia water, converting it into ammonium dihydrogen phosphate. The pH is adjusted, followed by cooling, crystallization, filtration, and drying to obtain ammonium dihydrogen phosphate crystals. The second method is to react it with ferric or ferrous salts to obtain ferric phosphate. This is followed by reaction, settling, filtration, washing, and drying to obtain solid ferric phosphate.

[0023] S2: The molybdenum-containing compounds in the S1 filtrate are chemically adsorbed using a melamine derivative adsorbent. After stirring, adsorption, cooling, filtration, and washing, an adsorbent filter cake containing molybdenum compounds is obtained.

[0024] S3: Add deionized water to the filter cake and mix well. Add alkaline solution to adjust the pH and stir to desorb. After filtration and washing, obtain a high-purity filtrate containing molybdenum compounds.

[0025] In the above methods, melamine derivative adsorbents showed an adsorption rate of over 90% for molybdenum, while alkaline desorbents achieved a desorption rate of over 85%. Furthermore, the adsorbents can be reused multiple times, saving on process costs. Ultimately, the complete conversion of phosphoric acid and the efficient separation of molybdenum-containing compounds from electronic waste acid were achieved, demonstrating significant potential for widespread application.

[0026] Furthermore, in the first method for converting phosphoric acid to ammonium dihydrogen phosphate in waste acid, ammonia water is used for neutralization to adjust the pH to 2-4, preferably 3-4.

[0027] Furthermore, in the first method of converting phosphoric acid into ammonium dihydrogen phosphate in waste acid, the neutralization liquid is gradually cooled to 30-35℃ and 10-15℃ in two stages. The crystals precipitated in the two stages are separated by vacuum filtration and then combined.

[0028] Furthermore, in the second method of obtaining ferric phosphate by reacting phosphoric acid in waste acid with ferric or ferrous salts, the ferric or ferrous salts refer to soluble ferric or ferrous salts, or sparingly soluble ferric or ferrous salts that can undergo a phase-change reaction to generate soluble ferric or ferrous salts; among them, soluble ferric or ferrous salts include ferric sulfate, ferric nitrate, and ferrous sulfate, and sparingly soluble ferric or ferrous salts that can undergo a phase-change reaction to generate these soluble ferric or ferrous salts include: ferric hydroxide, ferrous hydroxide, ferrous carbonate, and ferrous oxalate, etc.

[0029] Furthermore, in the second method of obtaining ferric phosphate by reacting phosphoric acid in waste acid with ferric or ferrous salts, the reaction is carried out with stirring at 60-90°C, preferably 65-80°C.

[0030] Furthermore, in the second method of obtaining ferric phosphate by reacting phosphoric acid in waste acid with ferric or ferrous salts, the reaction time is 1-3 h, preferably 1.5-2 h; after the reaction, the mixture is left to stand at room temperature for 2-6 h, preferably 4-5 h.

[0031] Furthermore, in the method for adsorbing molybdenum-containing compounds using melamine derivative adsorbents, the melamine derivative adsorbents include: melamine, alkyl-substituted melamine, strong melamine salts, melamine-formaldehyde resin cured products, melamine etherified resin cured products, and melamine alcoholamine derivatives, etc. Examples include: melamine, methyl melamine, benzoyl melamine, melamine sulfate, melamine phosphate, and hexamethylol melamine, but not limited to the above-mentioned melamine derivative adsorbents.

[0032] Furthermore, in the method for adsorbing molybdenum-containing compounds using melamine derivative adsorbents, adsorption is carried out by stirring at 60-80℃, preferably 60-70℃; the adsorption time is 4-7 h, preferably 5-6 h.

[0033] Furthermore, in the method for desorbing molybdenum-containing compounds using melamine derivative adsorbents, the desorbent is an alkaline compound, including inorganic and organic alkaline compounds, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium methoxide, sodium methoxide, sodium tert-butoxide, potassium tert-butoxide, etc.; the alkaline compound adjusts the pH of the filtrate to 10-12.

[0034] Furthermore, in the method for desorbing molybdenum-containing compounds using melamine derivative adsorbents, desorption is carried out by stirring at 40-70°C, preferably 55-65°C; the desorption time is 2-6 h, preferably 2.5-4 h.

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] In this invention, some conventional operating equipment, devices and components have been omitted or only briefly described.

[0039] Unless otherwise specified in the examples, the conditions shall be performed according to the standard conditions or the conditions recommended by the manufacturer.

[0040] In this application, all percentages not explicitly stated represent weight percentages, and all ratios are mass ratios.

[0041] The components of the electronic waste acid solution were characterized by XRF and ICP, and are listed in Table 1. Table 1. Composition of Electronic Waste Acid:

[0042] Example 1: A method for high-value recycling and utilization of electronic waste acid includes the following steps: S1: Weigh 3240 g of electronic waste acid into a 5 L beaker, then place the beaker in an ice-water bath. Slowly add 27% ammonia solution to the beaker for neutralization, stirring constantly to dissipate heat and adjust the pH to 3. When the temperature of the neutralized solution drops to 35℃, a large amount of crystals precipitate, and the mixture is filtered to obtain a filter cake and filtrate. The filtrate is then cooled to 10℃, crystals precipitate again, and a second filtration is performed to obtain another filter cake and filtrate. The two filter cakes are combined, weighing 3169 g, and then dried under reduced pressure at 80℃. The two filtrates are mixed to obtain a molybdenum-containing filtrate. The molybdenum-containing filtrate is heated to 60℃, and a small amount of the filtrate is tested for molybdenum content using ICP (the same applies below).

[0043] S2: Weigh 15.2 g of melamine (0.12 mol) into a 2 L beaker, and add 500 g of the molybdenum-containing filtrate from S1 at 60℃. Then, place the beaker in a 70℃ water bath and stir for 6 hours. After cooling and filtration, rinse the adhered material and filter cake with deionized water. Mix the resulting filtrate thoroughly, weigh it, and take a sample to test the molybdenum content.

[0044] S3: Place the filter cake obtained in S2 into a 1 L beaker, add 550 g of deionized water and mix well. Then add a small amount of 20% NaOH solution to adjust the pH to 11. Next, place the beaker in a 55℃ water bath and stir for 3 h. After cooling, filter by suction, and then rinse the adhering material and filter cake with deionized water. Mix the resulting filtrate well, weigh it, and take a sample to test the molybdenum content.

[0045] Example 2 A method for high-value recycling and utilization of electronic waste acid includes the following steps: S1: Weigh 3240 g of electronic waste acid into a 5 L beaker, then place the beaker in an ice-water bath. Slowly add 27% ammonia solution to the beaker for neutralization, stirring constantly to dissipate heat and adjust the pH to 3. When the temperature of the neutralized solution drops to 35℃, a large amount of crystals precipitate, and then filter. Freeze the filtrate at 10℃ to precipitate more crystals, and then perform a second filtration. The combined weight of the two filter cakes is 3169 g, which is then dried under reduced pressure at 80℃. After mixing the filtrate, a molybdenum-containing filtrate is obtained. Heat the molybdenum-containing filtrate to 60℃, and take a small amount of the filtrate to test the molybdenum content.

[0046] S2: Weigh 26.9 g of melamine phosphate (0.12 mol) into a 2 L beaker, and add 500 g of the molybdenum-containing filtrate from S1 at 60℃. Place the beaker in a 65℃ water bath and stir for 5 h, then cool and filter. Rinse the adhering material and filter cake with deionized water. Mix the resulting filtrate thoroughly, weigh it, and take a sample to test the molybdenum content.

[0047] S3: Place the filter cake from S2 into a 1 L beaker, add 550 g of deionized water and mix well. Then add a small amount of 10% KOH solution to adjust the pH to 12. Place the beaker in a 65℃ water bath and stir for 5 h. After cooling, filter by suction, and then rinse the adhering material and filter cake with deionized water. Mix the resulting filtrate well, weigh it, and take a sample to test the molybdenum content.

[0048] Example 3 A method for high-value recycling and utilization of electronic waste acid includes the following steps: S1: Weigh 400g (1mol) of anhydrous ferric sulfate and place it in a 2 L flask. Add 1000g of deionized water to dissolve the ferric sulfate. Then add 318g of electronic waste acid (containing 2mol of phosphoric acid), and stir the mixture at 90℃ for 3 h to obtain a white turbid liquid. Let the turbid liquid stand at room temperature for 5 h, filter it, and obtain a filter cake and a molybdenum-containing filtrate. Wash the filter cake until neutral, dry it, and obtain white ferric phosphate. Weigh the molybdenum-containing filtrate, heat it to 60℃, and take a sample to test the molybdenum content.

[0049] S2: Weigh 14.8 g of melamine (0.12 mol) into a 2 L beaker, then add 500 g of the molybdenum-containing filtrate from S1 at 60℃. Place the beaker in a 60℃ water bath and stir for 4 hours, then cool and filter. Wash the adhering material and filter cake with deionized water. Mix the resulting filtrate thoroughly, weigh it, and take a sample to test the molybdenum content.

[0050] S3: Place the filter cake from S2 into a 1L beaker, add 550 g of deionized water and mix well. Then add a small amount of 30% Na2CO3 solution to adjust the pH to 11. Place the beaker in a 65℃ water bath and stir for 3 hours. After cooling, filter by suction, and then wash the adhering material and filter cake with deionized water. Mix the resulting filtrate well, weigh it, and take a sample to test the molybdenum content.

[0051] Example 4 A method for high-value recycling and utilization of electronic waste acid includes the following steps: S1: Weigh 400g (1mol) of anhydrous ferric sulfate and place it in a 2 L flask. Add 1000g of deionized water to dissolve the ferric sulfate. Then add 318g of electronic waste acid (containing 2mol of phosphoric acid), and stir the mixture at 90℃ for 3 h to obtain a white turbid liquid. Let the turbid liquid stand at room temperature for 5 h, filter it, and obtain a filter cake and a molybdenum-containing filtrate. Wash the filter cake until neutral, dry it, and obtain white ferric phosphate. Weigh the molybdenum-containing filtrate, heat it to 60℃, and take a sample to test the molybdenum content.

[0052] S2: Weigh 30.8 g of melamine alcohol amine derivative (formula weight 256 g / mol, 0.12 mol) into a 2 L beaker, and add 500 g of the molybdenum-containing filtrate from S1 at 60℃. Place the beaker in a 65℃ water bath and stir for 5 h, then cool and filter. Wash the adhering material and filter cake with deionized water. Mix the resulting filtrate thoroughly, weigh it, and take a sample to test the molybdenum content.

[0053] S3: Place the filter cake from S2 into a 1 L beaker, add 550 g of deionized water and mix well. Then add a small amount of 20% NaOH solution to adjust the pH to 12. Place the beaker in a 60℃ water bath and stir for 4 h. After cooling, filter by suction, and then wash the adhering material and filter cake with deionized water. Mix the resulting filtrate well, weigh it, and take a sample to test the molybdenum content.

[0054] The adsorption and desorption rates of molybdenum by the melamine derivative adsorbents in the above embodiments are listed in Table 2.

[0055] Table 2. Adsorption and desorption rates of molybdenum by different melamine derivative adsorbents.

[0056] Note: Adsorption rate and desorption rate are both relative to the total amount of molybdenum in the raw material.

[0057] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0058] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A method for high-value recycling and utilization of electronic waste acid, characterized in that, Includes the following steps: S1: Add ammonia to the electronic waste acid liquid for neutralization to obtain a neutralized liquid; then cool and filter the neutralized liquid to obtain ammonium dihydrogen phosphate crystals and molybdenum-containing filtrate; or react the electronic waste acid liquid with ferric salts or ferrous salts, and after settling and filtration, obtain solid iron phosphate and molybdenum-containing filtrate. S2: The molybdenum-containing filtrate obtained in S1 is chemically adsorbed using a melamine derivative adsorbent. After stirring, adsorption, cooling, filtration and washing, an adsorbent filter cake containing molybdenum compounds is obtained. S3: Add the molybdenum-containing adsorbent filter cake obtained in S2 to deionized water and mix well. Add alkaline solution to adjust the pH and stir to desorb. After filtration and washing, obtain the desorbed high-purity molybdenum-containing compound filtrate.

2. The method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S1, when ammonia water is neutralized, the pH is adjusted to 2-4. The neutralized solution is gradually cooled in two stages: first to 30-35℃ and then to 10-15℃. The ammonium dihydrogen phosphate crystals precipitated in the two stages are separated by vacuum filtration, and finally the obtained ammonium dihydrogen phosphate crystals are combined.

3. The method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S1, ferric salts or ferrous salts include ferric sulfate, ferric nitrate, ferrous sulfate, ferric hydroxide, ferrous hydroxide, ferrous carbonate, and ferrous oxalate; the temperature for the reaction between the electronic waste acid and the ferric salts or ferrous salts is 60-90℃, and the time is 1-3 h; the time for standing at room temperature is 2-6 h.

4. The method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S2, melamine derivative adsorbents include melamine, alkyl-substituted melamine, melamine strong acid salts, melamine-formaldehyde resin cured products, melamine etherified resin cured products, and melamine alcoholamine derivatives.

5. The method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S2, the melamine derivative adsorbents include methyl melamine, benzomelamine, melamine sulfate, melamine phosphate, and hexamethylol melamine.

6. A method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S2, the temperature for stirring and adsorption is 60-80℃; the adsorption time is 4-7 h.

7. The method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S3, the alkaline solution includes inorganic alkaline compounds and organic alkaline compounds; the pH value is adjusted to 10-12.

8. A method for high-value recycling of electronic waste acid liquid according to claim 1, characterized in that: In S3, the temperature for stirring desorption is 40-70℃; the time for stirring desorption is 2-6 h.

9. The method for high-value recycling of electronic waste acid liquid according to claim 7, characterized in that: In S3, the alkaline solution includes sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, potassium methoxide, sodium methoxide, sodium tert-butoxide, and potassium tert-butoxide.

10. The method according to any one of claims 1-9, characterized in that: Compared to the total amount of molybdenum in the electronic waste acid, this method achieves an adsorption rate of over 90% and a desorption rate of over 85% for molybdenum.

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