Method for extracting lithium by stripping and coupling organic matter degradation of waste lithium battery

Abstract

The invention belongs to the technical field of resource recycling of waste lithium batteries, and particularly relates to a method for extracting lithium by stripping and coupling organic matter degradation of waste lithium batteries, which comprises the following steps: S1, obtaining a waste lithium iron phosphate positive plate and an organic pollutant aqueous solution; s2, soaking the waste lithium iron phosphate positive plate in an organic acid solution, and stripping to obtain an aluminum foil and a lithium iron phosphate material; s3, adding the lithium iron phosphate material, a complexing agent and an oxidation auxiliary agent into the organic pollutant aqueous solution to obtain a first reaction system, and carrying out a first reaction; after the reaction of the second reaction system is balanced, carrying out solid-liquid separation to obtain filtrate and filter residues, adding a lithium salt precipitator into the filtrate, and filtering to obtain lithium salt and recovering the lithium salt; according to the method, the battery recovery process and the wastewater treatment process are ingeniously coupled, the components of the waste battery material are used as the catalyst, organic pollutants in the environment are degraded, and cooperative treatment of waste and upgrading and recovery of resources are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of resource recycling of waste lithium batteries, and particularly relates to a method for stripping and coupling organic matter degradation to extract lithium from waste lithium batteries. BACKGROUND

[0002] With the rapid development of the new energy automobile industry, a large number of lithium iron phosphate power batteries enter the scrap stage, and their environmental protection treatment and resource recycling have become key problems to be solved. At present, the recycling technologies for waste lithium iron phosphate batteries mainly focus on pyrometallurgy and hydrometallurgy. Pyrometallurgy has high energy consumption, and lithium elements are easy to enter the slag and are difficult to recover, resulting in resource waste. Hydrometallurgy usually uses inorganic acid (such as sulfuric acid and hydrochloric acid) to leach valuable metals in the positive electrode material, but this process has the following defects: aluminum foil corrosion: strong acid will seriously corrode the current collector aluminum foil while dissolving the active material, causing aluminum elements to enter the leaching solution, and subsequent complex purification steps are needed to separate aluminum and lithium, increasing the process cost and complexity; poor selectivity: traditional acid leaching method usually leaches lithium and iron together, and additional steps (such as precipitation and extraction) are needed to separate them, resulting in a long process and large reagent consumption; environmental risk: the wet process itself may produce acid wastewater, and the problem of widely existing organic pollutants (such as microplastics and antibiotics) in the environment cannot be solved, and the synergistic environmental benefits of "waste treatment" cannot be achieved. Persulfate advanced oxidation technology is a new water treatment technology, and the sulfate radicals generated thereby have the advantages of strong oxidation capacity, long half-life and wide pH range, and can be used to degrade difficult-to-treat organic pollutants. However, how to cleverly couple this technology with the battery recycling process to achieve the dual goals of resource recycling and pollution control is still lacking effective solutions.

[0003] Therefore, it is of important practical significance and application value to develop a green recycling new process that can efficiently and selectively extract lithium while synergistically degrading organic pollutants. SUMMARY

[0004] To solve the above technical problems, the application provides a method for stripping and coupling organic matter degradation to extract lithium from waste lithium batteries, which comprises the following steps: S1, obtaining waste lithium iron phosphate positive electrode sheets and an aqueous solution of organic pollutants; S2, soaking the waste lithium iron phosphate positive electrode sheets in an organic acid solution to obtain aluminum foil and lithium iron phosphate material by stripping; S3, adding the lithium iron phosphate material, a complexing agent and an oxidation aid into the organic contaminant aqueous solution to obtain a first reaction system and performing a first reaction, the complexing agent being at least one of disodium ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, nitrilotriacetic acid, ethylenediamine-N,N'-di(o-hydroxyphenylacetic acid), polyacrylic acid, polymaleic acid, polyaspartic acid, the oxidation aid being at least one of persulfate or hydrosulfite; S4, supplementing the oxidation aid and the organic contaminant into the first reaction system to obtain a second reaction system and performing a second reaction; S5, after the second reaction system reaches a reaction equilibrium, performing a solid-liquid separation to obtain a filtrate and a residue, adding a lithium salt precipitant into the filtrate, and after filtering, washing and drying, obtaining a lithium salt and recycling.

[0005] In the step S4, the content of the organic contaminant and the content of lithium ions in the first reaction system are detected, and when the removal rate of the organic contaminant is greater than or equal to 90%, the oxidation aid and the organic contaminant aqueous solution are supplemented into the first reaction system to obtain a second reaction system and perform a second reaction.

[0006] In the step S1, the organic contaminant in the organic contaminant aqueous solution includes at least one of tetracycline hydrochloride, polystyrene, carboxyl-polystyrene, bisphenol A, methylene blue.

[0007] In the step S2, the waste lithium iron phosphate positive plate is soaked in the organic acid solution, and reacts at a temperature of 20-90°C for 10-120 min, the organic acid includes at least one of ascorbic acid, citric acid, tartaric acid, oxalic acid, and the concentration of the organic acid is 0.4-1.2 mol / L.

[0008] In the step S3, the addition amount of the complexing agent is 1%-50% of the mass of the lithium iron phosphate material, the addition amount of the oxidation aid is 0.05%-50% of the mass of the lithium iron phosphate material, the concentration of the organic contaminant aqueous solution is 5-50 mg / L, and the ratio of the volume of the organic contaminant aqueous solution to the mass of the lithium iron phosphate material is 0.2-1 g / L.

[0009] Further, the addition amount of the complexing agent is any one of 1%, 10%, 20%, 30%, 40%, 50% of the mass of the lithium iron phosphate material or a range between any two of them. Further, the addition amount of the oxidation aid is any one of 0.05%, 5%, 10%, 20%, 30%, 40%, 50% of the mass of the lithium iron phosphate material or a range between any two of them. Further, the ratio of the volume of the organic pollutant aqueous solution to the mass of the lithium iron phosphate material is any one of 0.2 g / L, 0.4 g / L, 0.6 g / L, 0.8 g / L, 1 g / L or a range between any two of them.

[0010] In the step S3, the first reaction is stirring the first reaction system at a temperature of 20-60 DEG C for 10-180 min; in the step S4, the second reaction is stirring the second reaction system at a temperature of 20-60 DEG C for 10-180 min.

[0011] In the step S4, the first reaction system is supplemented with the oxidation aid and organic pollutants to obtain a second reaction system and perform a second reaction, and the concentration of the organic pollutants in the second reaction system is the same as that in the first system.

[0012] In the step S5, after the second reaction system reaches reaction equilibrium, solid-liquid separation is performed to obtain a filtrate and a residue, the filtrate is evaporated and concentrated at a temperature of 60-95 DEG C to 1 / 5-2 / 3 of the original volume to obtain a high-concentration lithium-containing solution, the lithium salt precipitant is added to the high-concentration lithium-containing solution, and the reaction is performed at a temperature of 70-95 DEG C for 30-120 min; after the reaction is completed, the lithium salt is obtained after filtration, washing and drying, and is recovered.

[0013] The lithium salt precipitant is at least one of sodium carbonate, sodium phosphate or sodium oxalate.

[0014] In the step S5, the removal rate of the organic pollutants in the filtrate is greater than or equal to 70%, and the recovery rate of lithium elements is greater than or equal to 95%.

[0015] The present application ingeniously couples the battery recycling process with the wastewater treatment process, utilizes the components of the waste battery material as a catalyst to degrade the organic pollutants in the environment, realizes the collaborative treatment of waste and the upgrading and recycling of resources, and due to the presence of the complexing agent, the complex purification steps such as iron removal and aluminum removal, which are essential in the traditional process, are completely omitted, the process flow is significantly shortened, and the reagent consumption and cost are reduced. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0017] The present application provides a method for stripping and coupling organic matter degradation to extract lithium from waste lithium batteries, comprising the following steps: S1, obtaining waste lithium iron phosphate positive plate and organic contaminant aqueous solution; S2, soaking the waste lithium iron phosphate positive plate in an organic acid solution to obtain aluminum foil and lithium iron phosphate material by peeling; In the embodiment of the present application, the waste lithium iron phosphate positive plate after artificial disassembly is placed in an organic acid solution and reacted at a temperature of 20-90°C for 10-120 min. After the reaction is completed, clean aluminum foil, peeled lithium iron phosphate material and organic acid solution are obtained by physical separation. The organic acid solution can be recycled for the next peeling.

[0018] The present application utilizes the mild acidity of the organic acid, which can effectively dissolve the binder and promote the detachment of the lithium iron phosphate material from the aluminum foil, while avoiding the corrosion of strong acid to the aluminum foil, realizing the complete recovery and high value utilization of the aluminum foil.

[0019] The organic acid solution reacts with the waste lithium iron phosphate battery positive material, and the ionic equation of the reaction is as follows: Al2O3+6H+=2Al 3+ +3H2O 2Al+6H + =3H2+2Al 3+ S3, adding the lithium iron phosphate material, a complexing agent and an oxidation aid to the organic contaminant aqueous solution to obtain a first reaction system and perform a first reaction, the complexing agent being at least one of disodium ethylenediaminetetraacetate (EDTA), diethylenetriamine pentaacetic acid (DTPA), nitrilotriacetic acid, ethylenediamine-N,N'-di(ortho-hydroxyphenylacetic acid) (EDDHA), polyacrylic acid (PAA), polymaleic acid (PMA), and polyaspartic acid (PASP), and the oxidation aid being at least one of persulfate or hydrogen persulfate; S4, supplementing the oxidation aid and organic contaminant to the first reaction system to obtain a second reaction system and perform a second reaction; In the present application, the first reaction is stirring the first reaction system at 20-60°C for 10-180 min. After the organic contamination is removed, no solid-liquid separation operation is performed, and the oxidation aid and high-concentration organic contaminant solution are continuously or batchwise supplemented to the reaction system to maintain the oxidation activity of the reaction system and promote the continuous release of lithium ions from the solid phase to the liquid phase. When the lithium leaching rate is greater than or equal to 95%, a one-time solid-liquid separation is performed to obtain a solution enriched with lithium ions and a final waste residue. The solution is subjected to subsequent treatment to recover lithium; only the complexing agent is added once in the initial stage in the entire cyclic reaction process, and no supplement is required subsequently; the present application realizes a certain degree of enrichment of lithium ions in the liquid phase by multiple supplementations of "reaction fuel", and also realizes the continuous removal of organic contamination.

[0020] S5, after the second reaction system reaction equilibrium, solid-liquid separation is carried out, to obtain filtrate and filter residue, lithium salt precipitant is added to the filtrate, and after filtration, washing and drying, lithium salt is obtained and recovered.

[0021] The inventor of the present application found that the stripped lithium iron phosphate material has a unique effect in the complexing agent and oxidizing agent system; Fe 2+ The persulfate can be activated to produce sulfate radicals, which can non-selectively attack and degrade organic pollutants (such as microplastics and antibiotics) in water, and mineralize or degrade them into non-toxic small molecules; the effect of the complexing agent in the system: first, it can form a stable water-soluble complex with the iron ions dissolved in the activation process, which not only greatly promotes the release kinetics of lithium from the crystal lattice, but more importantly, it "locks" the impurity ions such as iron and aluminum in the solution into the complex, preventing them from co-precipitating in the subsequent steps; second, the complexation significantly enhances the degradation efficiency of the system to organic pollutants, achieving deep purification. Therefore, after the reaction is completed, lithium exists in the form of ions in the solution, while impurities such as iron and aluminum are complexed in the liquid phase or fixed in the solid phase residue, and after filtration, a crude lithium-containing solution with extremely high purity and almost no impurities such as iron and aluminum can be directly obtained, laying a solid foundation for the subsequent direct precipitation of high-purity lithium salt.

[0022] The present application creatively utilizes the characteristic that the complexing agent is not consumed in the reaction, and the sufficient amount of the initially added complexing agent can complex the dissolved impurity ions such as iron and aluminum throughout the reaction, thereby ensuring the selective leaching of lithium and the purity of the solution, and there is no need for subsequent replenishment, which significantly reduces the cost of reagents and the complexity of operation.

[0023] The present application drives the reaction to continuously proceed to the right by continuously supplementing the oxidizing agent and pollutants, so that the concentration of lithium ions continuously increases in the same reactor and the same liquid phase, achieving a certain degree of enrichment and creating favorable conditions for the subsequent stage.

[0024] Example 1 S1, 10g of lithium iron phosphate waste is added to a 0.4mol / L ascorbic acid solution, the reaction temperature is 25℃, and 8.8g of lithium iron phosphate and 0.79g of aluminum foil are obtained by separation; S2, 1.0g of lithium iron phosphate in step S1 is taken, 0.10g of sodium persulfate and 0.29g of EDTA are added to 1L of polystyrene (particle size 100nm) solution with a concentration of 15mg / L, and the reaction is carried out at 25℃ for 10min, and the sample is detected, and it is calculated that the removal rate of polystyrene (particle size 100nm) is 94.8% and the leaching rate of lithium is 32.5% at this time; S3, 0.10g of sodium persulfate was added to the solution of step S2, 0.01L of polystyrene (particle size 100nm) with a concentration of 1500mg / L, and the reaction was carried out at 25℃ for 10min. Sampling detection was carried out, and calculation showed that the removal rate of polystyrene (particle size 100nm) was 91% and the leaching rate of lithium was 61.3% at this time; S4, 0.10g of sodium persulfate was added to the solution of step S3, 0.01L of polystyrene (particle size 100nm) with a concentration of 1500mg / L, and the reaction was carried out at 25℃ for 10min. Sampling detection was carried out, and calculation showed that the removal rate of polystyrene (particle size 100nm) was 88.3% and the leaching rate of lithium was 90.4% at this time; S5, 0.10g of sodium persulfate was added to the solution of step S4, 0.01L of polystyrene (particle size 100nm) with a concentration of 1500mg / L, and the reaction was carried out at 25℃ for 10min. Sampling detection was carried out, and calculation showed that the removal rate of polystyrene (particle size 100nm) was 87.8% and the leaching rate of lithium was 98.4% at this time; S6, the solution in step S5 was filtered to obtain a filtrate, the filtrate was heated and concentrated to 1 / 2 of the original volume, sodium carbonate was added, and the reaction was carried out at 85℃ for 60min to obtain a lithium carbonate precipitate.

[0025] Example 2 S1, 10g of lithium iron phosphate waste was added to a 0.8mol / L tartaric acid solution, and the reaction temperature was 50℃. Lithium iron phosphate 8.4g and aluminum foil 0.75g were separated; S2, 1.0g of lithium iron phosphate in step S1 was taken, 0.20g of sodium persulfate and 0.40g of EDTA were added to 1L of methylene blue solution with a concentration of 20mg / L, and the reaction was carried out at 25℃ for 30min. Sampling detection was carried out, and calculation showed that the removal rate of methylene blue was 99.8% and the leaching rate of lithium was 36.4% at this time; S3, 0.20g of sodium persulfate was added to the solution of step S2, 0.01L of methylene blue solution with a concentration of 2000mg / L, and the reaction was carried out at 25℃ for 30min. Sampling detection was carried out, and calculation showed that the removal rate of methylene blue was 98.3% and the leaching rate of lithium was 67.2% at this time; S4, 0.20g of sodium persulfate was added to the solution of step S3, 0.01L of methylene blue solution with a concentration of 2000mg / L, and the reaction was carried out at 25℃ for 30min. Sampling detection was carried out, and calculation showed that the removal rate of methylene blue was 97.4% and the leaching rate of lithium was 97.1% at this time; S5, filtering the solution in step S4 to obtain a filtrate, heating and concentrating the filtrate to 2 / 3 of the original volume, adding sodium phosphate, and reacting at 70°C for 90 min to obtain a lithium phosphate precipitate.

[0026] Example 3 S1, adding 10 g of lithium iron phosphate waste to a 0.6 mol / L ascorbic acid solution, with a reaction temperature of 25°C, and separating to obtain 8.9 g of lithium iron phosphate and 0.77 g of aluminum foil; S2, taking 1 g of lithium iron phosphate from step S1, adding 0.35 g of sodium persulfate and 0.4 g of EDTA to 1 L of a 15 mg / L polystyrene (100 nm particle size) solution, and reacting at 25°C for 20 min, and calculating that the removal rate of the polystyrene (100 nm particle size) at this time is 97.8% and the lithium leaching rate is 48.2%; S3, adding 0.035 g of sodium persulfate and 0.01 L of a 1500 mg / L polystyrene (100 nm particle size) solution to the solution in step S2, and reacting at 25°C for 30 min, and calculating that the removal rate of the polystyrene (100 nm particle size) at this time is 96.8% and the lithium leaching rate is 97.3%; S4, filtering the solution in step S3 to obtain a filtrate, heating and concentrating the filtrate to 1 / 2 of the original volume, adding sodium carbonate, and reacting at 85°C for 60 min to obtain a lithium carbonate precipitate.

[0027] Comparative Example 1 Unlike Example 2, no EDTA was added in step S2, and the removal rate of methylene blue in step S2 was 59.8% and the lithium leaching rate was 35.9%.

[0028] Comparative Example 2 Adding 0.75 g of FeSO4 and 0.10 g of sodium persulfate to 1 L of a 15 mg / L polystyrene (100 nm particle size) solution, and reacting at 25°C for 10 min, and calculating that the removal rate of the polystyrene (100 nm particle size) at this time was 0%.

[0029] Comparative Example 3 Unlike Example 2, the volume of the methylene blue solution added in step S2 was 1 L and the concentration was 100 mg / L, and the removal rate of methylene blue in step S4 was 12% and the lithium leaching rate was 96.7%.

[0030] Comparative Example 4 Different from example 2, the volume of the methylene blue solution added in step S3 and step S4 is 0.1L, the concentration is 5000mg / L, the removal rate of methylene blue in step S4 is 23%, and the leaching rate of lithium is 96.2%.

[0031] Comparative example 5 Different from example 2, only step S2 is performed, the removal rate of methylene blue is 99.8%, and the leaching rate of lithium is 36.4%.

[0032] Comparative example 6 The persulfate is activated by using cobalt sulfate, and 1L of polystyrene solution with a concentration of 20mg / L is added, and the removal rate of polystyrene is 0%.

[0033] The application ingeniously couples the battery recycling process and the wastewater treatment process, utilizes the components of the waste battery materials as catalysts to degrade organic pollutants in the environment, realizes the collaborative treatment of waste and the upgrading and recycling of resources, and completely omits the complex purification steps such as iron removal and aluminum removal which are indispensable in the traditional process due to the presence of the complexing agent, significantly shortens the process flow, and reduces the reagent consumption and cost.

[0034] The above only describes the preferred embodiments of the application, and does not limit the patent scope of the application, and any equivalent structural transformation made according to the application concept or direct / indirect application in other related technical fields is included in the patent protection scope of the application.

Claims

1. A method for extracting lithium from waste lithium batteries by stripping and degrading coupled organic matter, characterized in that, Includes the following steps: S1. Obtain waste lithium iron phosphate cathode sheets and an aqueous solution of organic pollutants; S2. The waste lithium iron phosphate cathode sheet is immersed in an organic acid solution and peeled off to obtain aluminum foil and lithium iron phosphate material; S3. The lithium iron phosphate material, complexing agent, and oxidizing agent are added together to the aqueous solution of the organic pollutant to obtain a first reaction system and carry out a first reaction. The complexing agent is at least one of disodium ethylenediaminetetraacetate, diethylenetriaminepentaacetic acid, aziridine triacetic acid, ethylenediamine-N,N'-di(o-hydroxyphenylacetic acid), polyacrylic acid, polymaleic acid, and polyaspartic acid. The oxidizing agent is at least one of persulfate or peroxymonosulfate. S4. Add the oxidizing agent and organic pollutant to the first reaction system to obtain a second reaction system and carry out the second reaction; S5. After the second reaction system reaches equilibrium, solid-liquid separation is performed to obtain filtrate and filter residue. Lithium salt precipitant is added to the filtrate, and after filtration, washing and drying, lithium salt is obtained and recovered.

2. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, Step S4 further includes: detecting the content of organic pollutants and lithium ions in the first reaction system; when the removal rate of the organic pollutants is greater than or equal to 90%, adding the oxidizing agent and the aqueous solution of the organic pollutants to the first reaction system to obtain a second reaction system and carrying out a second reaction.

3. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, In step S1, the organic pollutants in the aqueous solution include at least one of tetracycline hydrochloride, polystyrene, carboxylated polystyrene, bisphenol A, and methylene blue.

4. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, Specifically, step S2 involves immersing the waste lithium iron phosphate cathode sheet in the organic acid solution and reacting it at a temperature of 20-90°C for 10-120 minutes. The organic acid includes at least one of ascorbic acid, citric acid, tartaric acid, and oxalic acid, and the concentration of the organic acid is 0.4-1.2 mol / L.

5. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, In step S3, the amount of complexing agent added is 1% to 50% of the mass of the lithium iron phosphate material, the amount of oxidizing agent added is 0.05% to 50% of the mass of the lithium iron phosphate material, the concentration of the organic pollutant aqueous solution is 5 to 50 mg / L, and the ratio of the volume of the organic pollutant aqueous solution to the mass of the lithium iron phosphate material is 0.2 to 1 g / L.

6. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, In step S3, the first reaction is: stirring the first reaction system at a temperature of 20~60℃ for 10~180 min; In step S4, the second reaction is: stirring the second reaction system at a temperature of 20~60℃ for 10~180 min.

7. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, In step S4, the oxidizing agent and organic pollutants are added to the first reaction system to obtain a second reaction system and carry out a second reaction. The concentration of organic pollutants in the second reaction system is the same as that in the first system.

8. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, Specifically, step S5 involves the following steps: after the second reaction system reaches equilibrium, solid-liquid separation is performed to obtain filtrate and filter residue. The filtrate is then evaporated and concentrated to 1 / 5 to 2 / 3 of its original volume at a temperature of 60 to 95°C to obtain a high-concentration lithium-containing solution. The lithium salt precipitant is added to the high-concentration lithium-containing solution, and the reaction is carried out at a temperature of 70 to 95°C for 30 to 120 minutes. After the reaction is completed, the lithium salt is obtained by filtration, washing, and drying, and then recovered.

9. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, The lithium salt precipitant is at least one of sodium carbonate, sodium phosphate, or sodium oxalate.

10. The method for lithium extraction from waste lithium batteries by stripping and degrading coupled organic matter according to claim 1, characterized in that, In step S5, the removal rate of organic pollutants in the filtrate is greater than or equal to 70%; the recovery rate of lithium is greater than or equal to 95%.