Method for recycling lithium from waste batteries by using magnetic nano adsorbent to enrich lithium and prepare lithium carbonate

Abstract

The present application relates to a kind of magnetic nano adsorbent enrichment of waste battery recovery liquid lithium and the method for preparing lithium carbonate, belong to waste battery resource recovery technical field.To waste battery acid leaching recovery liquid, add oxidizing agent, impurity remover, adjust, filter after stirring reaction, obtain pretreatment liquid;The pretreatment liquid is heated and added to magnetic nano adsorbent, stirring adsorption, obtain lithium-loaded adsorbent and adsorption liquid after adsorption;Lithium-loaded adsorbent is added to desorption liquid, and stirring desorption obtains regenerated adsorbent and desorption liquid;Desorption liquid is evaporated and concentrated, and saturated sodium carbonate solution is added, stirring reaction, after standing precipitation, filter, filter cake washing, drying, obtain lithium carbonate;Regenerated adsorbent is washed with deionized water, dry, and be recycled for lithium adsorption step;The present application has high impurity removal rate, high lithium recovery rate, the purity of prepared lithium carbonate is high, reaches battery grade standard, can be directly used in the production of lithium ion battery, realizes the high-value recycling of lithium resources.

Description

Technical Field

[0001] This invention relates to the field of waste battery resource recycling technology, and in particular to a method for enhancing the enrichment of lithium in waste battery recycled liquid and preparing lithium carbonate using magnetic nano-adsorbents. Background Technology

[0002] Lithium-ion batteries are widely used in new energy vehicles, portable electronic devices, and energy storage systems due to their high energy density, long cycle life, and lack of memory effect. With the rapid expansion of the lithium-ion battery market, a large number of used lithium-ion batteries are generated. These used lithium-ion batteries contain not only valuable metals such as cobalt, nickel, and manganese, but also lithium, an important strategic resource. Although its content is lower than that of cobalt and nickel, lithium resources are scarce and unevenly distributed. Therefore, recycling lithium resources from used batteries has significant economic and environmental value.

[0003] Chinese Patent CN119330378A discloses a method for preparing lithium carbonate from cathode material waste liquid, relating to the field of lithium carbonate preparation technology. The method includes the following steps: adding hydrogen peroxide and sulfuric acid to the cathode material waste liquid, separating the solid and liquid phases to obtain a solid mixture of iron phosphate / carbon black and a lithium-containing solution; adding a flocculant to the lithium-containing solution for primary impurity removal, filtering, and then performing a secondary impurity removal through electrostatic descaling, followed by filtration to obtain a lithium-containing purified solution; heating and concentrating the lithium-containing purified solution to obtain a concentrated solution; adding sodium carbonate solution to the concentrated solution to perform a lithium precipitation reaction to obtain crude lithium carbonate and a lithium precipitation mother liquor; mixing the crude lithium carbonate with water to form a slurry, introducing CO2, and performing a hydrogenation reaction under hypergravity conditions; filtering after the reaction to obtain a lithium bicarbonate solution; performing a thermal decomposition reaction on the lithium bicarbonate solution under hypergravity conditions, while simultaneously adding a nucleating agent; after crystal precipitation, filtration to obtain the lithium carbonate product and a crystallization mother liquor.

[0004] Chinese Patent CN119330379A: Provides a method for recovering and preparing lithium carbonate from the calcination ash of waste lithium batteries. The process is simple and has high recovery efficiency. The method for recovering lithium from the calcination ash of waste lithium batteries and preparing lithium carbonate and crude lithium carbonate includes the following steps: dissolving the calcined ash with pure water under ultrasonic conditions, while simultaneously introducing carbon dioxide to obtain a lithium bicarbonate solution; then subjecting the leachate to ultrafiltration to remove impurities and reverse osmosis to concentrate the lithium concentration, followed by vacuum pyrolysis to obtain pure lithium carbonate.

[0005] Existing recycling technologies suffer from problems such as high energy consumption, large equipment investment, easy generation of secondary pollution, and low lithium recovery rate. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents. The operation steps are as follows, in parts by mass: S1 Pretreatment: Add 0.1-0.4 parts of oxidant and 19-31 parts of impurity removal agent to 70-100 parts of waste battery acid leaching recovery solution, adjust the pH to 2-4, stir and react for 1-2 hours, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution is heated to 30-50℃, magnetic nano-adsorbent is added, and adsorption is carried out by stirring for 2-4 hours. The lithium-loaded adsorbent and the adsorbed solution are obtained by separation by magnetic field. S3 Lithium Desorption: Add lithium-loaded adsorbent to the desorption solution, adjust the pH to 8-10, raise the temperature to 40-60℃, stir and desorb for 1-2 hours, and separate the regenerated adsorbent and desorption solution using a magnetic field. S4 Lithium precipitation purification: Evaporate and concentrate the desorption solution to a lithium content of 4.4-6.4 wt%, add saturated sodium carbonate solution, control the temperature at 70-90℃, stir the reaction for 1-3 hours, let it stand to precipitate, filter, wash the filter cake with deionized water and anhydrous ethanol 2-3 times in sequence, and dry it at 100-120℃ for 2-4 hours to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0007] Furthermore, the S1 oxidant is a 20-30 wt% hydrogen peroxide aqueous solution.

[0008] Furthermore, the S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride, with a mass ratio of 5-8:2-3:1.

[0009] Furthermore, the liquid-to-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 50-200:1.

[0010] Furthermore, the S3 desorption solution is a mixed solution of 1.8-8.6 wt% ammonium chloride solution and 15-30 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.2-0.5.

[0011] Furthermore, the liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 20-50:1.

[0012] Furthermore, the volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2-2.4.

[0013] Furthermore, the magnetic field strength of S2 and S3 is 0.1-0.5T, and the separation time is 5-15min.

[0014] Furthermore, the preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 6-12 parts of ferric chloride and 2-6 parts of ferrous sulfate in 300-400 parts of deionized water. Under nitrogen protection, heat to 60-80℃, slowly add 20-30 parts of ammonia water to adjust the pH to 9-11, and stir the reaction for 1-2 hours to obtain Fe3O4 magnetic nuclei. H2: Disperse Fe3O4 magnetic cores in 300-400 parts of N,N-dimethylformamide, add 2-5 parts of 3-aminophenylboronic acid, 0.4-0.7 parts of 4,4'-dialdehyde diphenyl ether, and 0.5-2 parts of p-toluenesulfonic acid, control the stirring speed at 250-350 r / min, heat to 80-90℃ and reflux for 5-8 h, filter, and dry to obtain magnetic nano-adsorbent.

[0015] Furthermore, the mass percentage of the ammonia water is 15-25%.

[0016] The reaction mechanism of the magnetic nano-adsorbent: In the preparation of the magnetic nano-adsorbent, the amino group (-NH2) of 3-aminophenylboronic acid and the aldehyde groups (-CHO) at both ends of 4,4'-dialdehyde diphenyl ether lose water molecules to form C=N (imine bonds), which are then linked to form a three-dimensional network structure polymer. This reaction uses Fe3O4 magnetic core as a substrate, and the generated polymer is attached to the surface of the magnetic core through intermolecular forces to construct a core-shell structure of "Fe3O4 magnetic core + polymer coating". The coating characteristics can be controlled by adjusting the feeding ratio. Technical effect 1. The core value of this reaction lies in the fact that the polymer coating retains the boric acid group (-B(OH)2) of 3-aminophenylboronic acid, which can specifically form a stable four-coordinate complex with lithium ions, achieving selective adsorption of Li⁺. At the same time, relying on the polymer structure containing C=N bonds and a benzene ring skeleton, it ensures that the coating is stable and the magnetic core remains intact during the subsequent adsorption and desorption process, ensuring that the adsorbent can be recycled, and providing key support for the efficient enrichment of lithium in waste battery recycling liquid.

[0017] 2. The process of this invention is short, simple to operate, has a high lithium recovery rate, and produces high-purity lithium carbonate that meets battery-grade standards. It can be directly used in the production of lithium-ion batteries, thus realizing the high-value recycling and utilization of lithium resources.

[0018] 3. The pretreatment process uses a composite impurity removal agent, which has a high impurity removal rate and avoids the impact of impurity ions on the subsequent adsorption and lithium precipitation processes; no toxic or harmful reagents are used in the process, and the wastewater discharge is low, which meets the requirements of green environmental protection. Attached Figure Description

[0019] Figure 1 This is the SEM image of Example 1. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving the intended purpose, the following detailed description of the specific implementation methods and effects of the present invention, in conjunction with embodiments, is provided below.

[0021] 1. Lithium carbonate purity: Tested according to GB / T11075-2013.

[0022] 2. Lithium recovery rate: Calculated by the formula: Lithium recovery rate = (mass of lithium in the product / total mass of lithium in the recovery liquid) × 100%.

[0023] 3. Impurity removal rate: The concentration of impurity ions was detected by inductively coupled plasma atomic emission spectrometry, and the impurity removal rate was calculated. Example 1

[0024] A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.1g of oxidant and 19g of impurity remover to 70g of waste battery acid leaching recovery solution, adjust the pH to 2, stir and react for 1 hour, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution was heated to 30℃, magnetic nano-adsorbent was added, and the mixture was stirred for 2 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 8, the temperature is raised to 40℃, and the desorption is stirred for 1 hour. The regenerated adsorbent and the desorption solution are separated by magnetic field. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 4.4 wt%, saturated sodium carbonate solution was added, the temperature was controlled at 70℃, the reaction was stirred for 1 h, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, and dried at 100℃ for 2 h to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0025] The S1 oxidant is a 20wt% hydrogen peroxide solution.

[0026] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 5:2:1.

[0027] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 50:1.

[0028] The S3 desorption solution is a mixed solution of 1.8 wt% ammonium chloride solution and 15 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.2.

[0029] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 20:1.

[0030] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.

[0031] The magnetic field strength of S2 and S3 is 0.1T, and the separation time is 5min.

[0032] The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 6g of ferric chloride and 2g of ferrous sulfate in 300g of deionized water. Under nitrogen protection, heat to 60℃, slowly add 20g of ammonia to adjust the pH to 9, and stir the reaction for 1h to obtain Fe3O4 magnetic nuclei. H2: Fe3O4 magnetic cores were dispersed in 300g N,N-dimethylformamide, and 2g 3-aminophenylboronic acid, 0.4g 4,4'-dialdehyde diphenyl ether, and 0.5g p-toluenesulfonic acid were added. The stirring speed was controlled at 250r / min, and the mixture was heated to 80℃ and refluxed for 5h. After filtration and drying, magnetic nano-adsorbent was obtained.

[0033] The ammonia solution has a mass percentage of 15%. Example 2

[0034] A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.2g of oxidant and 23g of impurity remover to 80g of waste battery acid leaching recovery solution, adjust the pH to 3, stir and react for 1.5h, filter to remove impurities, and obtain the pretreated solution; S2 Lithium Adsorption: The pretreatment solution was heated to 35℃, magnetic nano-adsorbent was added, and the mixture was stirred for 3 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 9, the temperature is raised to 45℃, and the desorption is carried out by stirring for 1.5 hours. The regenerated adsorbent and the desorption solution are obtained by magnetic field separation. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 5wt%, a saturated sodium carbonate solution was added, the temperature was controlled at 75℃, the reaction was stirred for 2 hours, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, and dried at 105℃ for 3 hours to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0035] The S1 oxidant is a 25wt% hydrogen peroxide aqueous solution.

[0036] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 6:2.5:1.

[0037] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 100:1.

[0038] The S3 desorption solution is a mixed solution of 3.5 wt% ammonium chloride solution and 20 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.3.

[0039] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 30:1.

[0040] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.1.

[0041] The magnetic field strength of S2 and S3 is 0.2T, and the separation time is 10min.

[0042] The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 8g of ferric chloride and 3g of ferrous sulfate in 340g of deionized water. Under nitrogen protection, heat to 65℃, slowly add 23g of ammonia water to adjust the pH to 10, and stir the reaction for 1.5h to obtain Fe3O4 magnetic nuclei. H2: Fe3O4 magnetic cores were dispersed in 340g N,N-dimethylformamide, and 3g 3-aminophenylboronic acid, 0.5g 4,4'-dialdehyde diphenyl ether, and 1g p-toluenesulfonic acid were added. The stirring speed was controlled at 300r / min, and the mixture was heated to 85℃ and refluxed for 6h. After filtration and drying, magnetic nano-adsorbent was obtained.

[0043] The ammonia solution has a mass percentage of 20%. Example 3

[0044] A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.3g of oxidant and 27g of impurity remover to 90g of waste battery acid leaching recovery solution, adjust the pH to 3, stir and react for 1.5h, filter to remove impurities, and obtain the pretreated solution; S2 Lithium Adsorption: The pretreatment solution was heated to 45℃, magnetic nano-adsorbent was added, and the mixture was stirred for 3 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 9, the temperature is raised to 55℃, and the desorption is carried out by stirring for 1.5 hours. The regenerated adsorbent and the desorption solution are obtained by magnetic field separation. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 6wt%, a saturated sodium carbonate solution was added, the temperature was controlled at 85℃, the reaction was stirred for 2h, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed three times with deionized water and anhydrous ethanol, and dried at 115℃ for 3h to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0045] The S1 oxidant is a 25wt% hydrogen peroxide aqueous solution.

[0046] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 7:2:1.

[0047] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 150:1.

[0048] The S3 desorption solution is a mixed solution of 7 wt% ammonium chloride solution and 25 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.4.

[0049] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 40:1.

[0050] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.3.

[0051] The magnetic field strength of S2 and S3 is 0.4T, and the separation time is 10min.

[0052] The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 10g of ferric chloride and 5g of ferrous sulfate in 380g of deionized water. Under nitrogen protection, heat to 75℃, slowly add 28g of ammonia water to adjust the pH to 10, and stir the reaction for 1.5h to obtain Fe3O4 magnetic nuclei. H2: Fe3O4 magnetic cores were dispersed in 380g N,N-dimethylformamide, and 4g 3-aminophenylboronic acid, 0.6g 4,4'-dialdehyde diphenyl ether, and 1.5g p-toluenesulfonic acid were added. The stirring speed was controlled at 300r / min, and the mixture was heated to 85℃ and refluxed for 7h. After filtration and drying, magnetic nano-adsorbent was obtained.

[0053] The ammonia solution has a mass percentage of 20%. Example 4

[0054] A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.4g of oxidant and 31g of impurity remover to 100g of waste battery acid leaching recovery solution, adjust the pH to 4, stir and react for 2 hours, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution was heated to 50℃, magnetic nano-adsorbent was added, and the mixture was stirred for 4 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 10, the temperature is raised to 60℃, and the desorption is stirred for 2 hours. The regenerated adsorbent and desorption solution are obtained by magnetic field separation. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 6.4 wt%, saturated sodium carbonate solution was added, the temperature was controlled at 90℃, the reaction was stirred for 3 hours, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed three times with deionized water and anhydrous ethanol, and dried at 120℃ for 4 hours to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0055] The S1 oxidant is a 30wt% hydrogen peroxide aqueous solution.

[0056] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 8:3:1.

[0057] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 200:1.

[0058] The S3 desorption solution is a mixed solution of 8.6 wt% ammonium chloride solution and 30 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:5.

[0059] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 50:1.

[0060] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.4.

[0061] The magnetic field strength of S2 and S3 is 0.5T, and the separation time is 15min.

[0062] The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 12g of ferric chloride and 6g of ferrous sulfate in 400g of deionized water. Under nitrogen protection, heat to 80℃, slowly add 30g of ammonia water to adjust the pH to 11, and stir the reaction for 2h to obtain Fe3O4 magnetic nuclei. H2: Fe3O4 magnetic cores were dispersed in 400g N,N-dimethylformamide, 5g 3-aminophenylboronic acid, 0.7g 4,4'-dialdehyde diphenyl ether, and 2g p-toluenesulfonic acid were added. The stirring speed was controlled at 350r / min, and the mixture was heated to 90℃ and refluxed for 8h. After filtration and drying, magnetic nano-adsorbent was obtained.

[0063] The ammonia solution has a mass percentage of 25%.

[0064] Comparative Example 1 A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.1g of oxidant and 19g of impurity remover to 70g of waste battery acid leaching recovery solution, adjust the pH to 2, stir and react for 1 hour, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution was heated to 30℃, magnetic nano-adsorbent was added, and the mixture was stirred for 2 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 8, the temperature is raised to 40℃, and the desorption is stirred for 1 hour. The regenerated adsorbent and the desorption solution are separated by magnetic field. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 4.4 wt%, saturated sodium carbonate solution was added, the temperature was controlled at 70℃, the reaction was stirred for 1 h, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, and dried at 100℃ for 2 h to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0065] The S1 oxidant is a 20wt% hydrogen peroxide solution.

[0066] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 5:2:1.

[0067] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 50:1.

[0068] The S3 desorption solution is a mixed solution of 1.8 wt% ammonium chloride solution and 15 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.2.

[0069] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 20:1.

[0070] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.

[0071] The magnetic field strength of S2 and S3 is 0.1T, and the separation time is 5min.

[0072] The preparation method of the magnetic nano-adsorbent is as follows: Dissolve 6g of ferric chloride and 2g of ferrous sulfate in 300g of deionized water. Under nitrogen protection, heat to 60℃, slowly add 20g of ammonia to adjust the pH to 9, and stir the reaction for 1 hour to obtain a magnetic nano-adsorbent.

[0073] The ammonia solution has a mass percentage of 15%.

[0074] Comparative Example 2 A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.1g of oxidant and 19g of impurity remover to 70g of waste battery acid leaching recovery solution, adjust the pH to 2, stir and react for 1 hour, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution was heated to 30℃, magnetic nano-adsorbent was added, and the mixture was stirred for 2 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 8, the temperature is raised to 40℃, and the desorption is stirred for 1 hour. The regenerated adsorbent and the desorption solution are separated by magnetic field. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 4.4 wt%, saturated sodium carbonate solution was added, the temperature was controlled at 70℃, the reaction was stirred for 1 h, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, and dried at 100℃ for 2 h to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0075] The S1 oxidant is a 20wt% hydrogen peroxide solution.

[0076] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 5:2:1.

[0077] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 50:1.

[0078] The S3 desorption solution is a mixed solution of 1.8 wt% ammonium chloride solution and 15 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.2.

[0079] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 20:1.

[0080] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.

[0081] The magnetic field strength of S2 and S3 is 0.1T, and the separation time is 5min.

[0082] The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 6g of ferric chloride and 2g of ferrous sulfate in 300g of deionized water. Under nitrogen protection, heat to 60℃, slowly add 20g of ammonia water to adjust the pH to 9, and stir the reaction for 1h to obtain Fe3O4 magnetic nuclei. H2: Fe3O4 magnetic cores were dispersed in 300g N,N-dimethylformamide, and 0.4g 4,4'-dialdehyde diphenyl ether and 0.5g p-toluenesulfonic acid were added. The stirring speed was controlled at 250r / min, and the mixture was heated to 80℃ and refluxed for 5h. After filtration and drying, magnetic nano-adsorbent was obtained.

[0083] The ammonia solution has a mass percentage of 15%.

[0084] Comparative Example 3 A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps: S1 Pretreatment: Add 0.1g of oxidant and 19g of impurity remover to 70g of waste battery acid leaching recovery solution, adjust the pH to 2, stir and react for 1 hour, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution was heated to 30℃, magnetic nano-adsorbent was added, and the mixture was stirred for 2 hours for adsorption. The lithium-loaded adsorbent and the adsorbed solution were then separated by a magnetic field. S3 Lithium Desorption: The lithium-loaded adsorbent is added to the desorption solution, the pH is adjusted to 8, the temperature is raised to 40℃, and the desorption is stirred for 1 hour. The regenerated adsorbent and the desorption solution are separated by magnetic field. S4 Lithium precipitation purification: The desorption solution was evaporated and concentrated to a lithium content of 4.4 wt%, saturated sodium carbonate solution was added, the temperature was controlled at 70℃, the reaction was stirred for 1 h, the sediment was allowed to stand and precipitate, and then filtered. The filter cake was washed twice with deionized water and anhydrous ethanol, and dried at 100℃ for 2 h to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step.

[0085] The S1 oxidant is a 20wt% hydrogen peroxide solution.

[0086] The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 5:2:1.

[0087] The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 50:1.

[0088] The S3 desorption solution is a mixed solution of 1.8 wt% ammonium chloride solution and 15 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.2.

[0089] The liquid-to-solid ratio of the S3 desorption solution to the adsorbent is 20:1.

[0090] The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2.

[0091] The magnetic field strength of S2 and S3 is 0.1T, and the separation time is 5min.

[0092] The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 6g of ferric chloride and 2g of ferrous sulfate in 300g of deionized water. Under nitrogen protection, heat to 60℃, slowly add 20g of ammonia water to adjust the pH to 9, and stir the reaction for 1h to obtain Fe3O4 magnetic nuclei. H2: Fe3O4 magnetic cores were dispersed in 300g N,N-dimethylformamide, 2g 3-aminophenylboronic acid and 0.5g p-toluenesulfonic acid were added, the stirring speed was controlled at 250r / min, the temperature was raised to 80℃ and refluxed for 5h, filtered and dried to obtain magnetic nano-adsorbent.

[0093] The ammonia solution has a mass percentage of 15%.

[0094] Table 1. Test results of lithium carbonate purity, lithium recovery rate, and impurity removal rate in the specific implementation plan. Lithium carbonate purity (%) Lithium recovery rate (%) Impurity removal rate (%) Example 1 99.69 96.65 99.13 Example 2 99.71 96.69 99.17 Example 3 99.78 96.75 99.22 Example 4 99.82 96.78 99.25 Comparative Example 1 86.92 82.41 84.76 Comparative Example 2 94.66 91.36 94.12 Comparative Example 3 95.43 92.17 94.95 The test data shows that this method significantly outperforms the comparative scheme in terms of lithium carbonate purity, lithium recovery rate, and impurity removal rate. The core advantage stems from the unique design and performance of the magnetic nano-adsorbent. In the preparation of this adsorbent, 3-aminophenylboronic acid and 4,4'-dialdehyde diphenyl ether undergo a Schiff base condensation reaction to form a polymer coating on the surface of the Fe3O4 magnetic core. On one hand, the boric acid groups in the coating can specifically bind to lithium ions, achieving efficient separation of lithium from impurity ions such as cobalt, nickel, and manganese, significantly improving impurity removal rate and lithium selectivity. On the other hand, the polymer structure containing C=N bonds and a benzene ring skeleton endows the coating with good stability. Combined with the increased specific surface area of ​​the three-dimensional network structure, this ensures the adsorbent's stable performance and reusability during cyclic adsorption-desorption, while also increasing lithium adsorption capacity. Ultimately, this leads to a simultaneous increase in lithium recovery rate and lithium carbonate purity, reaching battery-grade standards. This design, based on the construction of a functional adsorbent through a specific monomer condensation reaction, is the key innovation of this method for achieving high-value recycling of lithium resources from waste batteries, balancing efficiency, environmental protection, and economy.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents, comprising the following steps, in parts by mass: S1 Pretreatment: Add 0.1-0.4 parts of oxidant and 19-31 parts of impurity removal agent to 70-100 parts of waste battery acid leaching recovery solution, adjust the pH to 2-4, stir and react for 1-2 hours, filter to remove impurities, and obtain the pretreated solution. S2 Lithium Adsorption: The pretreatment solution is heated to 30-50℃, magnetic nano-adsorbent is added, and adsorption is carried out by stirring for 2-4 hours. The lithium-loaded adsorbent and the adsorbed solution are separated by magnetic field. S3 Lithium Desorption: Add lithium-loaded adsorbent to the desorption solution, adjust the pH to 8-10, raise the temperature to 40-60℃, stir and desorb for 1-2 hours, and separate the regenerated adsorbent and desorption solution using a magnetic field. S4 Lithium precipitation purification: Evaporate and concentrate the desorption solution to a lithium content of 4.4-6.4 wt%, add saturated sodium carbonate solution, control the temperature at 70-90℃, stir the reaction for 1-3 hours, let it stand to precipitate, filter, wash the filter cake with deionized water and anhydrous ethanol 2-3 times in sequence, and dry it at 100-120℃ for 2-4 hours to obtain lithium carbonate. S5 Adsorbent Regeneration: The regenerated adsorbent is washed with deionized water until neutral, vacuum dried, and then recycled for the lithium adsorption step. The magnetic nano-adsorbent is prepared by reacting ferric chloride, ferrous sulfate, ammonia, 3-aminophenylboronic acid, 4,4'-dialdehyde diphenyl ether, and p-toluenesulfonic acid.

2. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The S1 oxidant is a 20-30 wt% hydrogen peroxide aqueous solution.

3. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The S1 impurity remover is a mixture of calcium hydroxide, sodium carbonate and sodium fluoride in a mass ratio of 5-8:2-3:

1.

4. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The liquid-solid ratio of the S2 pretreatment liquid to the magnetic nano-adsorbent is 50-200:

1.

5. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The S3 desorption solution is a mixed solution of 1.8-8.6 wt% ammonium chloride solution and 15-30 wt% ammonia water, wherein the volume ratio of ammonium chloride solution to ammonia water is 1:0.2-0.

5.

6. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The liquid-solid ratio of the S3 desorption solution to the adsorbent is 20-50:

1.

7. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The volume ratio of the S4 eluent after evaporation and concentration to the volume of the saturated sodium carbonate solution is 1:2-2.

4.

8. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The magnetic field strength of S2 and S3 is 0.1-0.5T, and the separation time is 5-15min.

9. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 1, characterized in that: The preparation method of the magnetic nano-adsorbent is as follows: H1: Dissolve 6-12 parts of ferric chloride and 2-6 parts of ferrous sulfate in 300-400 parts of deionized water. Under nitrogen protection, heat to 60-80℃, slowly add 20-30 parts of ammonia water to adjust the pH to 9-11, and stir the reaction for 1-2 hours to obtain Fe3O4 magnetic nuclei. H2: Disperse Fe3O4 magnetic cores in 300-400 parts of N,N-dimethylformamide, add 2-5 parts of 3-aminophenylboronic acid, 0.4-0.7 parts of 4,4'-dialdehyde diphenyl ether, and 0.5-2 parts of p-toluenesulfonic acid, control the stirring speed at 250-350 r / min, heat to 80-90℃ and reflux for 5-8 h, filter, and dry to obtain magnetic nano-adsorbent.

10. The method for enhancing lithium enrichment and preparing lithium carbonate from recycled waste battery liquid using magnetic nano-adsorbents according to claim 9, characterized in that: The mass percentage of the ammonia solution is 15-25%.

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