A method for recovering metal from nickel-containing waste liquid

Abstract

The present application relates to the technical field of waste liquid treatment, and specifically discloses a method for recovering metal from nickel-containing waste liquid. A method for recovering metal from nickel-containing waste liquid includes A, pretreatment stage: filtering the nickel-containing waste liquid, removing large particle impurities and suspended matter, and then adjusting the pH value of the filtrate to 3.0-5.0 to form a stable nickel-containing solution; B, complex reaction and solid-liquid separation: adding enhanced sodium β-alanine to the nickel-containing solution after adjusting the pH value, stirring the reaction for 2-3 hours and then standing for 24 hours to obtain a stable complex, and then centrifuging the complex to obtain a complex solid; C, pyrolysis and reduction reaction: placing the complex solid in a heating furnace under the protection of an inert gas, performing a pyrolysis reaction, generating nickel oxide and volatile gases, and after the pyrolysis is completed, passing a reducing agent for heating and pressurization reaction to obtain metallic nickel powder. The method of the present application can efficiently and low-costly recover nickel in nickel-containing waste liquid.

Description

Technical Field

[0001] The present application relates to the technical field of waste liquid treatment, and more specifically, to a method for recovering metal from nickel-containing waste liquid. Background Art

[0002] In the field of environmental protection and resource recovery, the treatment of nickel-containing waste liquid has always been an important and challenging topic. With the increase of industrial activities, a large amount of nickel-containing waste liquid is discharged into the environment, which not only causes a waste of resources, but also poses a serious threat to the environment. Therefore, it is of great significance to develop efficient and environmentally friendly nickel-containing waste liquid recovery technology.

[0003] In the related art, nickel recovery technology using ion exchange resin has gradually attracted attention. This method allows nickel-containing waste liquid to pass through a column loaded with ion exchange resin, and uses the ions on the resin to exchange with the nickel ions in the waste liquid, thereby achieving nickel recovery.

[0004] However, although the ion exchange method has high recovery efficiency and purity in theory, it faces many challenges in practical application. First, the regeneration process of ion exchange resin is complicated and energy-intensive, which increases the processing cost. Secondly, as the processing volume increases, the exchange capacity of the resin will gradually decrease, requiring frequent replacement or regeneration, which reduces the processing efficiency. In addition, for nickel-containing waste liquid with high concentration or complex composition, the treatment effect of the ion exchange method is often unsatisfactory and it is difficult to achieve an ideal recovery rate.

[0005] In view of the above-mentioned shortcomings of the ion exchange method in treating nickel-containing waste liquid, this application proposes a new recovery method, which adopts an innovative treatment strategy combining chemistry and physics, and provides a more economical and effective solution for the treatment and recovery of nickel-containing waste liquid. Summary of the invention

[0006] In order to efficiently and cost-effectively recover nickel from nickel-containing waste liquid, the present application provides a method for recovering metal from nickel-containing waste liquid.

[0007] The present application provides a method for recovering nickel-containing waste liquid metal using the following technical solution:

[0008] A method for recovering metal from nickel-containing waste liquid comprises the following steps:

[0009] A. Pretreatment stage: Filter the nickel-containing waste liquid to remove large particle impurities and suspended matter, and then adjust the pH value of the filtrate to 3.0-5.0 to form a stable nickel-containing solution;

[0010] B. Complexation reaction and solid-liquid separation: adding enhanced sodium β-alanine to the nickel-containing solution after adjusting the pH value, stirring the solution for 2-3 hours and then standing it for 24 hours to obtain a stable complex, and then centrifuging the complex to obtain a complex solid;

[0011] C. Pyrolysis and reduction reaction: The complex solid is placed in a heating furnace under the protection of an inert gas to undergo a pyrolysis reaction to generate nickel oxide and volatile gases. After the pyrolysis is completed, a reducing agent is introduced to undergo a heating and pressurizing reaction to obtain metallic nickel powder.

[0012] By adopting the above technical scheme, firstly, in the pretreatment stage, large particles of impurities and suspended solids in the waste liquid are effectively removed by filtering and adjusting the pH value, and the existence form of nickel ions is stabilized, providing a good foundation for subsequent treatment. This step not only improves the treatment efficiency, but also reduces the interference factors that may be generated in the subsequent steps, which helps to improve the recovery accuracy. In the complexation reaction and solid-liquid separation stage, the enhanced sodium β-alanine is used to form a stable complex with nickel ions, which realizes the efficient enrichment and separation of nickel ions, creating favorable conditions for the subsequent pyrolysis and reduction reactions. The unique complexation ability of the enhanced sodium β-alanine significantly improves the recovery efficiency of nickel ions. The enhanced sodium β-alanine forms a strong coordination bond with nickel ions through the highly active functional groups in its molecules. This coordination effect enables the nickel ions to be effectively transferred from the waste liquid to the complex, realizing the efficient enrichment of nickel. Compared with traditional ion exchange resins, the enhanced sodium β-alanine has higher selectivity and complexation ability, and can more thoroughly remove nickel ions from the waste liquid, thereby improving the recovery accuracy. In addition, its complex is easy to separate and transform in subsequent treatment, which further simplifies the process flow and reduces the treatment cost.

[0013] Optionally, in step B, the amount of the fortified sodium β-alanine added is: 0.05-0.1 kg of fortified sodium β-alanine per kilogram of nickel-containing waste liquid.

[0014] By adopting the above technical solution, the amount of enhanced sodium β-alaninate added directly affects the degree of its complexation reaction with nickel ions. An appropriate amount of enhanced sodium β-alaninate can fully coordinate with the nickel ions in the waste liquid to form a stable complex, thereby achieving efficient enrichment of nickel ions. If the amount added is insufficient, some nickel ions cannot be complexed, resulting in a decrease in the recovery rate; if the amount added is too much, the excess enhanced sodium β-alaninate not only increases the cost, but may also have an adverse effect on subsequent treatment. The above dosage range ensures the full progress of the complexation reaction, and precise control helps to improve recovery efficiency and economic benefits.

[0015] Optionally, the reinforced sodium β-alaninate is obtained by grafting sodium β-alaninate monomer onto a polycarbonate matrix.

[0016] By adopting the above technical solution, the polycarbonate matrix provides a stable support structure for sodium β-alaninate, preventing it from decomposing or losing during the treatment process. At the same time, the grafting reaction introduces new functional groups and enhances the activity of the original functional groups, further improving the complexing ability and selectivity of sodium β-alaninate. This stable complexing agent can more effectively extract nickel ions from waste liquid, which is beneficial to improve the recovery efficiency and recovery effect of nickel.

[0017] Optionally, the fortified sodium β-alanine is prepared by the following method:

[0018] S1, washing the polycarbonate particles with deionized water, and then soaking them in an etching solution, and then taking out the polycarbonate particles, washing them with acetone, and drying them for later use;

[0019] S2. Place the pretreated polycarbonate in a reactor, add dimethyl sulfoxide, then add sodium β-alanine and a silane coupling agent, heat to 100-105° C., stir and react for 20-25 hours, and after the reaction is completed, filter, wash and dry to obtain reinforced sodium β-alanine.

[0020] Optionally, the etching solution in S1 is toluenesulfonic acid.

[0021] Optionally, the specific ratio of the raw materials in step S2 is: for every 100 grams of pretreated polycarbonate particles, 50-70 mL of dimethyl sulfoxide is added, followed by 5-10 g of sodium β-alanine and 0.5-1.0 g of a silane coupling agent.

[0022] By adopting the above technical solution, the etching solution treatment in the pretreatment step can change the surface properties of the polycarbonate matrix and increase its reactivity; dimethyl sulfoxide as a solvent promotes the dissolution and dispersion of the reactants; the addition of sodium β-alanine and silane coupling agent fixes the sodium β-alanine monomer on the polycarbonate matrix through a grafting reaction. These steps work together to make the prepared reinforced sodium β-alanine have excellent complexing properties.

[0023] Optionally, the reducing agent in step C includes any one of H2 and CO.

[0024] By adopting the above technical solution, H2 and CO can react with nickel oxide to generate metallic nickel and water vapor or carbon dioxide. These reduction reactions are usually carried out under heating and pressurization conditions to ensure the reaction rate and conversion rate. Selecting a suitable reducing agent is crucial to controlling the reaction conditions and optimizing the recovery effect. The use of the above gas reducing agent has the advantages of low cost, small dosage, good reduction effect and sufficient reaction.

[0025] Optionally, the temperature of the pyrolysis reaction is 400-600°C.

[0026] By adopting the above technical solution and carrying out the pyrolysis reaction within the above temperature range, the organic components in the complex can be decomposed to generate volatile gases, and the nickel ions can be oxidized to nickel oxide. This step is the key prerequisite for the subsequent reduction reaction to generate metallic nickel powder. By using the above pyrolysis temperature, the reaction conditions can be optimized, and the recovery efficiency and product quality can be improved.

[0027] In summary, this application has the following beneficial effects:

[0028] 1. Since the pretreatment stage of the recovery method of the present application effectively removes large particle impurities and suspended solids in the waste liquid by filtering and adjusting the pH value, and at the same time stabilizes the existence form of nickel ions, it provides a good foundation for subsequent treatment. This step not only improves the processing efficiency, but also reduces the interference factors that may be generated in the subsequent steps, which helps to improve the recovery accuracy. In the complexation reaction and solid-liquid separation stage, the enhanced sodium β-alanine is used to form a stable complex with nickel ions, which realizes the efficient enrichment and separation of nickel ions, creates favorable conditions for the subsequent pyrolysis and reduction reactions, and strengthens the unique complexing ability of sodium β-alanine, which significantly improves the recovery efficiency of nickel ions. Strengthening sodium β-alanine forms a strong coordination bond with nickel ions through the highly active functional groups in its molecules. This coordination effect enables nickel ions to be effectively transferred from the waste liquid to the complex, thereby realizing efficient enrichment of nickel. Compared with traditional ion exchange resins, enhanced sodium β-alanine has higher selectivity and complexing ability, and can more thoroughly remove nickel ions in waste liquid, thereby improving recovery accuracy. In addition, its complex is easy to separate and transform in subsequent treatment, which further simplifies the process flow and reduces the treatment cost.

[0029] 2. In the present application, the reinforced sodium β-alaninate is obtained by grafting the sodium β-alaninate monomer onto a polycarbonate matrix, and the polycarbonate matrix provides a stable support structure for the sodium β-alaninate to prevent it from decomposing or losing during the treatment process. At the same time, the grafting reaction introduces new functional groups and enhances the activity of the original functional groups, further improving the complexing ability and selectivity of the reinforced sodium β-alaninate. This stable complexing agent can more effectively extract nickel ions from waste liquid, which is conducive to improving the recovery efficiency and recovery effect of nickel. DETAILED DESCRIPTION

[0030] The present application is further described in detail below with reference to the embodiments.

[0031] The nickel-containing waste liquid used in this embodiment is the nickel-plating waste liquid generated in the electroplating process in the same section, and its composition is shown in Table 1:

[0032] Table 1 Composition of nickel-containing wastewater

[0033]

[0034] According to the above nickel-containing waste liquid composition table, the molar mass of nickel in nickel sulfate (NiSO4·6H2O) is 58.69 g / mol, the molar concentration of nickel sulfate is 0.066857 mol / L, and the mass concentration is 17.5734 g / L.

[0035] The mass of nickel per liter of waste liquid is:

[0036] m(Ni)=n (Ni) ×M (Ni) =0.066857mol / L×58.69g / mol=3.9241g / L

[0037] Assuming that the density of nickel-containing waste liquid is equal to that of water, the mass of nickel in each kg of waste liquid is:

[0038] m(Ni)=3.9241g / L×1L=3.9241g

[0039] Therefore, theoretically, there are 3.9241 g of nickel metal in every kg of waste liquid.

[0040] Preparation Example of Enhanced Sodium β-Alanine

[0041] Preparation Example 1

[0042] Strengthened sodium β-alanine, which is prepared by the following method:

[0043] S1. Pretreatment of polycarbonate substrate: 100 g of polycarbonate particles were washed with deionized water, and then added into benzoic acid to ensure that the particles were completely immersed. The particles were soaked for 24 hours. After the soaking, the polycarbonate particles were taken out, washed with acetone, and then dried in a vacuum drying oven to constant weight for later use.

[0044] S2. Place the pretreated polycarbonate in a reactor with a stirring device, add 60 mL of dimethyl sulfoxide, then add 8 g of sodium β-alanine and 0.8 g of silane coupling agent, heat to 102°C, stir and react for 24 hours, filter after the reaction, collect the solid product, and wash it alternately with ethanol and deionized water several times, place the washed solid product in a vacuum drying oven, and dry it at 60°C to constant weight to obtain reinforced sodium β-alanine.

[0045] Preparation Example 2

[0046] Strengthened sodium β-alanine, which is prepared by the following method:

[0047] S1. Pretreatment of polycarbonate substrate: 100 g of polycarbonate particles were washed with deionized water, and then added into benzoic acid to ensure that the particles were completely immersed. The particles were soaked for 24 hours. After the soaking, the polycarbonate particles were taken out, washed with acetone, and then dried in a vacuum drying oven to constant weight for later use.

[0048] S2. Place the pretreated polycarbonate in a reactor with a stirring device, add 50 mL of dimethyl sulfoxide, then add 5 g of sodium β-alanine and 0.5 g of silane coupling agent, heat to 100°C, stir and react for 20 hours, filter after the reaction, collect the solid product, and wash it alternately with ethanol and deionized water several times, place the washed solid product in a vacuum drying oven, and dry it at 60°C to constant weight to obtain reinforced sodium β-alanine.

[0049] Preparation Example 3

[0050] Strengthened sodium β-alanine, which is prepared by the following method:

[0051] S1. Pretreatment of polycarbonate substrate: 100 g of polycarbonate particles were washed with deionized water, and then added into benzoic acid to ensure that the particles were completely immersed. The particles were soaked for 24 hours. After the soaking, the polycarbonate particles were taken out, washed with acetone, and then dried in a vacuum drying oven to constant weight for later use.

[0052] S2. Place the pretreated polycarbonate in a reactor with a stirring device, add 70 mL of dimethyl sulfoxide, then add 10 g of sodium β-alanine and 1.0 g of silane coupling agent, heat to 105°C, stir and react for 25 hours, filter after the reaction, collect the solid product, and wash it alternately with ethanol and deionized water several times, place the washed solid product in a vacuum drying oven, and dry it at 60°C to constant weight to obtain reinforced sodium β-alanine.

[0053] Preparation Example 4

[0054] The preparation method of reinforced sodium β-alanine is different from that of Preparation Example 3 in that an equal amount of polyvinyl chloride is used instead of polycarbonate as a raw material.

[0055] Preparation Example 5

[0056] The preparation method of reinforced sodium β-alanine is different from that of Preparation Example 3 in that an equal amount of polyurethane is used instead of polycarbonate as a raw material.

[0057] Example

[0058] Example 1

[0059] A method for recovering metal from nickel-containing waste liquid comprises the following steps:

[0060] A. Pretreatment stage: Take 10kg of nickel-containing waste liquid and filter it through a filter with a pore size of 0.5mm to remove large particles of impurities and suspended matter, and then use dilute sulfuric acid to adjust the pH value of the filtrate to 4.0 to form a stable nickel-containing solution.

[0061] B. Complexation reaction and solid-liquid separation: 0.7 kg of enhanced sodium β-alanine was added to the nickel-containing solution after adjusting the pH value, stirred for reaction for 2.5 hours, and then allowed to stand for 24 hours to form a stable complex, which was centrifuged to obtain a complex solid. The enhanced sodium β-alanine was selected from the enhanced sodium β-alanine prepared in Preparation Example 1.

[0062] C. Pyrolysis and reduction reaction: The complex solid is placed in a heating furnace under nitrogen protection, heated to 500°C, and subjected to pyrolysis reaction for 2 hours to generate nickel oxide and volatile gas. After the pyrolysis is completed, H2 is introduced as a reducing agent, the temperature is maintained at 500°C and the pressure is increased to 2MPa in the heating furnace, and the reduction reaction is carried out for 4 hours to obtain metallic nickel powder.

[0063] Example 2

[0064] A method for recovering metal from nickel-containing waste liquid comprises the following steps:

[0065] A. Pretreatment stage: Take 10kg of nickel-containing waste liquid and filter it through a filter with a pore size of 0.5mm to remove large particles of impurities and suspended matter, and then use dilute sulfuric acid to adjust the pH value of the filtrate to 3.0 to form a stable nickel-containing solution.

[0066] B. Complexation reaction and solid-liquid separation: 0.5 kg of enhanced sodium β-alanine was added to the nickel-containing solution after adjusting the pH value, stirred for reaction for 3 hours, and then allowed to stand for 24 hours to form a stable complex, which was centrifuged to obtain a complex solid. The enhanced sodium β-alanine was selected from the enhanced sodium β-alanine prepared in Preparation Example 2.

[0067] C. Pyrolysis and reduction reaction: The complex solid is placed in a heating furnace under nitrogen protection, heated to 600°C, and subjected to pyrolysis reaction for 2 hours to generate nickel oxide and volatile gas. After the pyrolysis is completed, H2 is introduced as a reducing agent, the temperature is maintained at 500°C and the pressure is increased to 2MPa in the heating furnace, and a reduction reaction is carried out for 4 hours to obtain metallic nickel powder.

[0068] Example 3

[0069] A method for recovering metal from nickel-containing waste liquid comprises the following steps:

[0070] A. Pretreatment stage: Take 10kg of nickel-containing waste liquid and filter it through a filter with a pore size of 0.5mm to remove large particles of impurities and suspended matter, and then use dilute sulfuric acid to adjust the pH value of the filtrate to 5.0 to form a stable nickel-containing solution.

[0071] B. Complexation reaction and solid-liquid separation: 1.0 kg of enhanced sodium β-alanine was added to the nickel-containing solution after adjusting the pH value, stirred for reaction for 3 hours, and then allowed to stand for 24 hours to form a stable complex, which was centrifuged to obtain a complex solid. The enhanced sodium β-alanine was selected from the enhanced sodium β-alanine prepared in Preparation Example 3.

[0072] C. Pyrolysis and reduction reaction: The complex solid is placed in a heating furnace under nitrogen protection, heated to 400°C, and subjected to pyrolysis reaction for 2 hours to generate nickel oxide and volatile gas. After the pyrolysis is completed, CO is introduced as a reducing agent, the temperature is maintained at 500°C and the pressure is increased to 2 MPa in the heating furnace, and a reduction reaction is carried out for 4 hours to obtain metallic nickel powder.

[0073] Comparative Example

[0074] Comparative Example 1

[0075] A method for recovering metal from nickel-containing waste liquid, which differs from Example 3 in that in step B, sodium alginate is used instead of enhanced sodium β-alanine as a complexing agent to participate in the reaction.

[0076] Comparative Example 2

[0077] A method for recovering metal from nickel-containing waste liquid, which differs from Example 3 in that in step B, the enhanced sodium β-alanine prepared in Preparation Example 4 is used as a complexing agent to participate in the reaction.

[0078] Comparative Example 3

[0079] A method for recovering metal from nickel-containing waste liquid, which differs from Example 3 in that in step B, the enhanced sodium β-alanine prepared in Preparation Example 5 is used as a complexing agent to participate in the reaction.

[0080] Performance testing

[0081] According to the above nickel-containing waste liquid composition table, the molar mass of nickel in nickel sulfate (NiSO4·6H2O) is 58.69 g / mol, the molar concentration of nickel sulfate is 0.066857 mol / L, and the mass concentration is 17.5734 g / L.

[0082] The mass of nickel per liter of waste liquid is:

[0083] m(Ni)=n (Ni) ×M (Ni) =0.066857mol / L×58.69g / mol=3.9241g / L

[0084] Assuming that the density of nickel-containing waste liquid is equal to that of water, the mass of nickel in each kg of waste liquid is:

[0085] m(Ni)=3.9241g / L×1L=3.9241g

[0086] Therefore, theoretically, there are 3.9241 g of nickel metal in every kg of waste liquid.

[0087] The metal nickel powder recovered in the above Examples 1-3 and Comparative Examples 1-3 was weighed respectively, and the results are shown in Table 2. According to the above waste liquid composition table and calculation process, theoretically, 39.241 g of metal nickel powder should be recovered from 10 kg of nickel-containing waste liquid in this Example and the Comparative Example.

[0088] Table 2 The mass of the metal nickel powder recovered in Examples 1-3 and Comparative Examples 1-3

[0089] project Metal nickel powder mass (g) Recovery rate (%) Example 1 38.32 97.65 Example 2 37.96 96.74 Example 3 38.95 99.26 Comparative Example 1 18.32 46.69 Comparative Example 2 21.52 54.84 Comparative Example 3 20.06 51.12

[0090] According to the contents and test results of the above embodiments and comparative examples, the following data analysis and description are performed:

[0091] Examples 1-3 all use enhanced sodium β-alaninate (polycarbonate matrix) as a complexing agent, and carry out metal recovery of nickel-containing waste liquid under different reaction conditions. From the results, the recovery rates of metallic nickel powder are all high, 97.65%, 96.74% and 99.26% respectively, indicating that the use of enhanced sodium β-alaninate (polycarbonate matrix) as a complexing agent has good stability and high efficiency in the treatment of nickel-containing waste liquid.

[0092] Comparative Example 1 uses sodium alginate instead of reinforced sodium β-alaninate as a complexing agent. The results show that the recovery rate of metallic nickel powder dropped significantly to 46.69%, which is much lower than the recovery rate of the embodiment. This shows that the effect of sodium alginate in complexing nickel ions is far inferior to that of reinforced sodium β-alaninate (polycarbonate matrix), which may be due to the weak binding ability of its molecular structure with nickel ions.

[0093] Comparative Examples 2 and 3 respectively used the reinforced sodium β-alaninate prepared in Preparation Example 4 (polyvinyl chloride matrix) and Preparation Example 5 (polyurethane matrix) as complexing agents. Although their recovery rates (54.84% and 51.12%) were higher than those in Comparative Example 1, they were still significantly lower than those in the Examples. This indicates that the polycarbonate matrix plays a key role in the preparation of reinforced sodium β-alaninate, which may be related to its specific physical and chemical properties, so that the polycarbonate-based reinforced sodium β-alaninate has higher efficiency and stability when complexing nickel ions.

[0094] Strengthening sodium β-alaninate (polycarbonate matrix) has a strong binding ability with nickel ions, and can form a stable complex in nickel-containing waste liquid, thereby improving the recovery rate of nickel ions. This advantage has been fully verified in Examples 1-3, and the recovery rates are close to or exceed 96%. The polycarbonate matrix may be strengthened by a specific chemical or physical action during the preparation process to treat sodium β-alaninate, so that its stability in nickel-containing waste liquid is significantly improved. This stability not only helps to improve the complexing efficiency, but also reduces the decomposition or failure of the complex in the subsequent treatment process. Compared to other complexing agents (such as sodium alginate or reinforced sodium β-alaninate prepared by different matrices), polycarbonate-based reinforced sodium β-alaninate shows a higher recovery rate in the treatment of nickel-containing waste liquid. This means that in practical applications, the use of this complexing agent can more effectively recover the nickel metal resources in the waste liquid, reducing resource waste and environmental pollution.

[0095] In summary, the use of reinforced sodium β-alanine (polycarbonate matrix) as a complexing agent in the recovery of nickel-containing waste liquid metals has significant advantages, including efficient complexing effect, good stability and high recovery rate. These advantages make the complexing agent have broad application prospects in the field of nickel-containing waste liquid treatment.

[0096] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for recovering metal from nickel-containing waste liquid, characterized in that: The steps include: A. Pretreatment stage: Filter the nickel-containing waste liquid to remove large particle impurities and suspended matter, and then adjust the pH value of the filtrate to 3.0-5.0 to form a stable nickel-containing solution; B. Complexation reaction and solid-liquid separation: adding enhanced sodium β-alanine to the nickel-containing solution after adjusting the pH value, stirring for reaction for 2-3 hours and then standing for 24 hours to obtain a stable complex, and then centrifuging the complex to obtain a complex solid; the enhanced sodium β-alanine is obtained by grafting sodium β-alanine monomer onto a polycarbonate matrix; C. Pyrolysis and reduction reaction: The complex solid is placed in a heating furnace under the protection of an inert gas to undergo a pyrolysis reaction to generate nickel oxide and volatile gases. After the pyrolysis is completed, a reducing agent is introduced to undergo a heating and pressurizing reaction to obtain metallic nickel powder.

2. A method for recovering metal from nickel-containing waste liquid according to claim 1, characterized in that: In the step B, the amount of the fortified sodium β-alanine added is: 0.05-0.1 kg of fortified sodium β-alanine is added to each kilogram of nickel-containing waste liquid.

3. A method for recovering metal from nickel-containing waste liquid according to claim 1, characterized in that: The fortified sodium β-alanine is prepared by the following method: S1, washing the polycarbonate particles with deionized water, and then soaking them in an etching solution, and then taking out the polycarbonate particles, washing them with acetone, and drying them for later use; S2. Place the pretreated polycarbonate in a reactor, add dimethyl sulfoxide, then add sodium β-alanine and a silane coupling agent, heat to 100-105° C., stir and react for 20-25 hours, and after the reaction is completed, filter, wash and dry to obtain reinforced sodium β-alanine.

4. A method for recovering metal from nickel-containing waste liquid according to claim 3, characterized in that: The etching solution in S1 is toluenesulfonic acid.

5. A method for recovering metal from nickel-containing waste liquid according to claim 3, characterized in that: The specific ratio of the raw materials in step S2 is: for every 100 grams of pretreated polycarbonate particles, 50-70 mL of dimethyl sulfoxide is added, followed by 5-10 g of sodium β-alanine and 0.5-1.0 g of a silane coupling agent.

6. A method for recovering metal from nickel-containing waste liquid according to claim 1, characterized in that: The reducing agent in step C includes any one of H2 and CO.

7. A method for recovering metal from nickel-containing waste liquid according to claim 1, characterized in that: The temperature of the pyrolysis reaction is 400-600°C.

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