A recycling process for waste ternary lithium battery positive electrode material

Abstract

The application discloses the technical field of resource utilization of waste lithium batteries and discloses a waste ternary lithium battery positive electrode material recovery process. The waste positive electrode sheet is subjected to drying, crushing, stripping, sorting, magnetic separation and grinding treatment to obtain a positive electrode powder; sulfuric acid and hydrogen peroxide are used for reduction leaching, the obtained leaching liquid is subjected to phosphonated starch chelate microsphere segmented adjustment of pH and adsorption and impurity removal to obtain a leaching liquid from which impurities are removed; ammonia water and sodium hydroxide are added under nitrogen protection, nickel, cobalt and manganese are co-precipitated to form a composite hydroxide, the precipitation mother liquor is concentrated and lithium is precipitated by adding sodium carbonate to obtain lithium carbonate. The application has the advantages of high impurity removal selectivity, high metal recovery rate, high product purity and easy separation of the adsorption material.

Description

Technical Field

[0001] This invention belongs to the field of waste lithium battery resource utilization technology, specifically involving a recycling process for the cathode material of waste ternary lithium batteries. Background Technology

[0002] With the rapid development of new energy vehicles, portable electronic devices, and energy storage systems, the production and use of ternary lithium batteries have continued to expand, resulting in a year-on-year increase in the amount of waste ternary lithium batteries. Waste ternary lithium battery cathode materials contain valuable metal resources such as nickel, cobalt, manganese, and lithium. Direct landfilling, incineration, or improper dismantling not only wastes these valuable metal resources but also risks causing soil, water, and air pollution due to electrolyte residues, heavy metal migration, and the decomposition of fluorine-containing substances. Therefore, efficient, clean, and selective recycling of waste ternary lithium battery cathode materials has become an important research direction in the fields of resource recycling and environmental protection. Existing recycling technologies mainly include pyrometallurgy, hydrometallurgy, and a combination of both. Pyrometallurgy typically requires high reaction temperatures and significant energy consumption, and elements such as lithium easily enter the slag, increasing the difficulty of subsequent separation. Hydrometallurgy, with its advantages of mild reaction conditions, high metal leaching rates, and easily controllable product composition, has gradually become an important technical route for recycling waste ternary lithium battery cathode materials.

[0003] Existing wet recycling processes typically involve first crushing and screening waste cathode sheets, then leaching the active material using inorganic acids and reducing agents to introduce nickel, cobalt, manganese, and lithium into the solution. Subsequently, impurities such as iron, aluminum, and copper are removed through chemical precipitation, solvent extraction, ion exchange, or adsorption, and nickel-cobalt-manganese composite products and lithium salts are further recovered. However, waste cathode sheets often contain aluminum foil, conductive agents, binders, and impurities such as iron and copper introduced during dismantling. If pretreatment is insufficient, these impurities can enter the leaching system along with the cathode powder, leading to a complex composition of the leachate. Traditional stepwise pH adjustment methods for impurity removal, while simple, are prone to co-precipitation losses of nickel, cobalt, and manganese, and impurity ions may be carried into the target product during precipitation, reducing the purity of subsequent nickel-cobalt-manganese composite hydroxides. Solvent extraction offers some separation selectivity, but often involves organic extractants and diluents, resulting in long processes, high reagent consumption, emulsification, and organic phase loss. Ordinary ion exchange resins or natural polymer adsorbents may have drawbacks in acidic leachates, such as insufficient adsorption capacity, limited functional group types, poor mechanical stability, and difficulty in solid-liquid separation, making it difficult to achieve both selective removal of impurities and low-loss recovery of nickel, cobalt, and manganese.

[0004] Furthermore, the co-precipitation process of nickel, cobalt, and manganese is highly sensitive to reaction temperature, pH, complexation conditions, and atmosphere. Excessive local alkalinity or uneven metal ion release can easily lead to imbalances in particle nucleation and growth, resulting in composite hydroxides exhibiting problems such as compositional segregation, uneven particle size distribution, or high impurity content. The mother liquor after co-precipitation still contains a high concentration of lithium ions, as well as sodium salts, sulfates, and residual complexing components. Directly adding carbonates for lithium precipitation may result in insufficient lithium concentration, impurity co-precipitation, or improper temperature control, leading to a decrease in lithium carbonate yield and purity. Therefore, existing technologies still need to address issues such as insufficient separation of active materials from metal current collectors in the cathode sheet, difficulty in selectively removing various impurities from the acid leaching solution, significant losses of nickel, cobalt, and manganese during impurity removal, insufficient stability and separation performance of adsorbent materials, and the difficulty in continuously and efficiently recovering nickel, cobalt, manganese, and lithium. To improve the resource utilization level of spent ternary lithium battery cathode materials, it is necessary to develop a recovery process that can enhance pretreatment, improve leaching efficiency, selectively remove impurities, and sequentially obtain high-purity nickel-cobalt-manganese composite hydroxides and lithium carbonate. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a recycling process for waste ternary lithium battery cathode materials.

[0006] This invention provides a recycling process for cathode materials from waste ternary lithium batteries, comprising the following steps:

[0007] S1. By weight, dry the waste ternary lithium battery positive electrode sheet to obtain the dried positive electrode sheet; cut 95-105 parts of the dried positive electrode sheet, crush it by impact and peel it by friction, and then screen, sort and magnetically separate it in sequence, grind and sieve it to obtain waste ternary positive electrode powder.

[0008] S2. Add 95-105 parts of waste ternary cathode powder to 1000-1100 parts of sulfuric acid solution and stir at 60-70℃; add 60-100 parts of hydrogen peroxide solution and stir to leach; after leaching, cool and filter to obtain leachate and leaching residue; wash the leaching residue with deionized water to obtain washing solution; combine the washing solution and leachate to obtain ternary metal leachate;

[0009] S3. Adjust the pH of the ternary metal leaching solution to 3.2-3.6 with sodium hydroxide solution, add 15.0-30.0 parts of phosphonate-modified starch-grafted iminodiacetic acid microspheres, and stir; continue to add sodium hydroxide solution, adjust the pH to 3.8-4.2, stir, and filter to obtain a purified leaching solution and impurity-loaded microspheres; add the impurity-loaded microspheres to sulfuric acid solution and stir, perform solid-liquid separation to obtain an desorption solution; electrolyze the desorption solution to obtain copper and the electrolyzed solution; add hydrogen peroxide solution to the electrolyzed solution, stir, adjust the pH, and separate iron and aluminum; return the resulting solution containing trace amounts of nickel, cobalt, and manganese to S2;

[0010] S4. Under nitrogen protection, heat the impurity-removing leachate, add ammonia water, then add sodium hydroxide solution, adjust the pH, stir the reaction, age, and filter to obtain filter cake and precipitate mother liquor; wash the filter cake with deionized water and dry to obtain nickel-cobalt-manganese composite hydroxide; heat the precipitate mother liquor, evaporate and concentrate, add sodium carbonate solution, stir the reaction, age, and filter to obtain lithium carbonate filter cake; wash the lithium carbonate filter cake with deionized water at 90-95℃ and dry.

[0011] In this invention, waste ternary lithium battery cathode sheets are dried to remove moisture and residual electrolyte solvent, reducing the plasticity of the binder and decreasing material adhesion and agglomeration. Shearing, impact crushing, and friction peeling cause the cathode active material and the current collector interface to be subjected to shearing, impact, and friction simultaneously, thus peeling them apart. Screening, sorting, and magnetic separation remove current collector fragments, magnetic impurities, and inactive components based on differences in particle size, density, and magnetic properties. Grinding and sieving increase the specific surface area and shorten the leaching mass transfer path, resulting in waste ternary cathode powder. After waste ternary cathode powder enters the sulfuric acid solution, hydrogen ions attack the oxygen in the layered oxide lattice, gradually disintegrating the crystal structure. Lithium, nickel, cobalt, and manganese enter the liquid phase in ionic form. Incompletely removed aluminum and copper foil fragments, along with iron and trace amounts of calcium, magnesium, and zinc brought in by the raw materials, also partially dissolve and coexist in the liquid phase. Hydrogen peroxide solution acts as a reducing agent, reducing high-valence cobalt and manganese to divalent states, eliminating insoluble high-valence oxides, and increasing the leaching rate and extraction efficiency. After leaching, solid-liquid separation is achieved through cooling and filtration. The leaching residue is washed with deionized water to recover metal ions trapped in its pores. The washing liquid and leaching filtrate are combined to form a lithium-containing nickel-cobalt-manganese leaching solution. The pH of the lithium-containing nickel-cobalt-manganese leaching solution is increased in stages using sodium hydroxide solution, which reduces the competitive occupation of hydrogen ions on the coordinating groups of phosphonic starch-grafted iminodiacetic acid microspheres, causing the carboxyl and phosphonic acid groups to gradually dissociate into coordinated states. Iron, aluminum, and copper ions have high charge density and large hydrolysis constants. In this pH range, they form multidentate chelate rings with nitrogen atoms of iminodiacetic acid groups and oxygen atoms of carboxyl groups, and coordinate with oxygen atoms of phosphonic acid groups. The stability constant of their complexes is significantly higher than that of nickel, cobalt, and manganese. Segmented adjustment makes the adsorption process gradual, avoiding excessive local alkalinity that would cause nickel, cobalt, and manganese to hydrolyze and coprecipitate or be embedded. After filtration, impurities are removed from the system with the impurity-loaded microspheres, resulting in a purified leachate. When the microspheres are eluted with dilute sulfuric acid, high concentrations of hydrogen ions reoccupy the coordination sites of carboxyl, phosphonic acid, and imino nitrogen groups, causing the chelate rings to disintegrate. Iron, aluminum, copper, and small amounts of co-adsorbed nickel, cobalt, and manganese are desorbed into the desorption solution. The coordination groups of the microspheres are restored and can be recycled. Copper in the desorption solution is recovered as elemental form through electrodeposition or displacement. The pH of the remaining solution is adjusted to allow iron and aluminum to precipitate as hydroxides and be discharged. The clarified solution containing trace amounts of nickel, cobalt, and manganese is returned to the leaching process, allowing the valuable metals lost through co-adsorption to re-enter the system. Nitrogen protection inhibits the oxidation of divalent manganese by oxygen and the absorption of carbon dioxide by the alkaline system. Ammonia reacts with nickel, cobalt, and manganese ions to form reversibly dissociating ammonium complex ions, reducing the instantaneous concentration of free metal ions and alleviating local supersaturation when sodium hydroxide solution is added, thus matching the nucleation and growth rates. As pH increases and hydroxide concentration increases, the ammonium complex ions gradually dissociate and release metal ions under the constraint of hydroxide solubility product. The three ions co-precipitate with hydroxide ions, and after aging, the particles become dense and the composition is uniformly distributed, yielding a nickel-cobalt-manganese composite hydroxide.Under alkaline conditions, lithium ions do not form hydroxide precipitates but remain in the mother liquor. Heating and evaporation concentration increase their concentration. After adding sodium carbonate solution, lithium carbonate with low solubility is generated. The solubility of lithium carbonate decreases with increasing temperature. Precipitation, aging and filtration under heating conditions can reduce re-dissolution losses. The resulting lithium carbonate filter cake is washed with deionized water to remove soluble salts adhering to the surface and then dried, realizing the stepwise recovery of nickel, cobalt, manganese and lithium.

[0012] According to a preferred embodiment of the present invention, in step S1, the drying temperature is 120-150°C; the drying time is 1-2 hours; and the drying absolute pressure is 1-5 kPa.

[0013] According to a preferred embodiment of the present invention, in step S2, the concentration of the sulfuric acid solution is 2.0-2.2 mol / L; the stirring and leaching time is 60-120 min; and the mass fraction of the hydrogen peroxide solution is 30%.

[0014] According to a preferred embodiment of the present invention, in step S3, after adding phosphonate-modified starch-grafted iminodiacetic acid microspheres, the stirring time is 30-60 min, and after adjusting the pH to 3.8-4.2, the stirring time is continued for 30-60 min.

[0015] According to a preferred embodiment of the present invention, in step S4, the impurity-removing leachate is heated to 50-60°C; sodium hydroxide solution is added to adjust the pH to 11.0-11.5; the precipitate mother liquor is heated to 85-95°C; after adding sodium carbonate solution, the reaction is stirred for 60-120 min, and the aging time is 2-4 h.

[0016] According to a preferred embodiment of the present invention, the preparation steps of the phosphonate-modified starch-grafted iminodiacetic acid microspheres include:

[0017] A1. By weight, 100.0-110.0 parts of corn starch were added to 900-1100 parts of deionized water and stirred to gelatinize at 80-85℃. After cooling to 40-45℃, 8.0-14.0 parts of sodium trimetaphosphate were added, and the pH was adjusted to 10.8-11.5 with sodium hydroxide solution to obtain an aqueous starch phase. 2500-3200 parts of liquid paraffin and 60.0-90.0 parts of dehydrated sorbitan monooleate were added to a reactor and stirred at 40-45℃. The aqueous starch phase was then added to the reactor, and the reaction was continued with stirring to obtain a reaction product. The reaction product was allowed to stand and separate into layers, then filtered to obtain a solid product. The solid product was washed successively with petroleum ether, anhydrous ethanol, and deionized water, and the pH was adjusted to 6.5-7.0 with hydrochloric acid solution. The product was then vacuum dried at 50-60℃ and sieved to obtain phosphate-crosslinked corn starch microspheres.

[0018] A2. Add 95.0-105.0 parts of phosphate-crosslinked corn starch microspheres to 300-400 parts of deionized water, add 12.0-16.0 parts of sodium hydroxide, and stir at 25-35℃; add 25.0-35.0 parts of epichlorohydrin dropwise, and react at 35-45℃ to obtain an activated reaction product; filter the activated reaction product to obtain activated microspheres; wash the activated microspheres with deionized water, and then add them to a grafting solution composed of 60.0-80.0 parts of ethylenediamine and 350-450 parts of deionized water, adjust the pH to 10.0-10.8 with hydrochloric acid, and react at 60-70℃; distill under reduced pressure, filter, and obtain a solid product; wash the solid product successively with deionized water and anhydrous ethanol, and dry under vacuum at 50-60℃ to obtain ethylenediamine-grafted crosslinked starch microspheres;

[0019] A3. Add 95.0-105.0 parts of ethylenediamine-grafted cross-linked starch microspheres to 400-500 parts of deionized water, stir at 35-40℃, and adjust the pH to 10.0-10.8 with 20% sodium hydroxide solution to obtain a mixture; add 55.0-75.0 parts of sodium chloroacetate to 100-150 parts of deionized water, stir to obtain a sodium chloroacetate solution; add the sodium chloroacetate solution to the mixture in two portions, maintaining the pH at 10.0-10.8 with 20% sodium hydroxide solution after each addition, and stir the reaction at 55-65℃ to obtain a reaction product; cool the reaction product to 25-30℃, adjust the pH to 5.0-5.5 with 10% hydrochloric acid solution, filter to obtain a solid product; wash the solid product with deionized water, and vacuum dry at 50-60℃ to obtain iminodiacetic acid-grafted starch microspheres;

[0020] A4. Add 95.0-105.0 parts of iminodiacetic acid-grafted starch microspheres to 450-550 parts of deionized water, stir and disperse, add 25.0-40.0 parts of phosphorous acid, and adjust the pH to 0.5-1.0 with 31% hydrochloric acid solution; under nitrogen protection, heat to 65-75℃ to obtain a reaction solution; add 10.0-15.0 parts of paraformaldehyde to 80-120 parts of deionized water to obtain a paraformaldehyde dispersion; add the paraformaldehyde dispersion dropwise to the reaction solution, stir and react at 65-75℃ to obtain a reaction product; cool the reaction product to 30-35℃, adjust the pH to 5.5-6.5 with 10% sodium hydroxide solution, filter, and obtain a solid product; wash the solid product with deionized water, vacuum dry at 50-60℃, and sieve to obtain phosphonated starch-grafted iminodiacetic acid microspheres.

[0021] In this invention, the preparation mechanism of the phosphonate-coated starch-grafted iminodiacetic acid microspheres is as follows: Corn starch is gelatinized by heating in deionized water, causing the internal hydrogen bond network of the particles to disintegrate, the molecular chains to unfold, and the accessibility of hydroxyl groups and reactivity to increase. After adjusting the system to alkalinity with sodium hydroxide solution, some hydroxyl groups dissociate into more nucleophilic alkoxides, which attack the phosphorus atoms of the cyclic trimetaphosphate group of sodium trimetaphosphate, causing the cyclic structure to open and form phosphate ester bonds with the starch molecular chains; the same phosphorus atom then condenses with the hydroxyl groups of adjacent molecular chains, establishing phosphate ester crosslinking bridges between chains to form a three-dimensional network framework. Liquid paraffin is used as the continuous phase, and dehydrated sorbitan monooleate is adsorbed at the oil-water interface and reduces the interfacial tension, dispersing and stabilizing the starch aqueous phase into droplets, so that the crosslinking is confined to the inside of the droplets, resulting in phosphate ester crosslinked corn starch microspheres with a narrow particle size distribution. Petroleum ether is used to remove residual liquid paraffin from the surface, anhydrous ethanol is used to remove dehydrated sorbitan monooleate, and deionized water is used to wash away unreacted sodium trimetaphosphate and soluble byproducts. Hydrochloric acid solution is used to neutralize residual alkali to terminate crosslinking and inhibit alkaline hydrolysis of phosphate ester bonds. The hydroxyl groups of the phosphate-crosslinked corn starch microspheres dissociate again under the action of sodium hydroxide, nucleophilically opening the epoxy group of epichlorohydrin to generate a chlorohydrin structure linked by an ether bond. This chlorohydrin undergoes dehydrochlorination and re-closes the ring in an alkaline medium, generating epoxy groups on the surface and within the pores of the microspheres, thus activating the microspheres. The primary amino group of ethylenediamine undergoes nucleophilic addition to the epoxy group to open the ring, covalently linking one end to the microsphere to form a secondary amino group, while the other end retains the free primary amino group, yielding ethylenediamine-grafted crosslinked starch microspheres. Under alkaline conditions, the nitrogen atom of the free primary amino group attacks the methylene carbon of sodium chloroacetate, causing the chloride ion to leave, and two carboxyl methyl groups are sequentially introduced onto the nitrogen. The acid released from the reaction is neutralized by sodium hydroxide solution to maintain alkalinity and prevent protonation deactivation of the amino group, thereby constructing an iminodiacetic acid group on the terminal nitrogen, resulting in iminodiacetic acid-grafted starch microspheres. In a strongly acidic medium, paraformaldehyde depolymerizes to formaldehyde, which condenses and dehydrates with an uncarboxylated secondary amino group to generate a methylene ammonium ion. Under these conditions, phosphorous acid is mainly in the form of a four-coordinated HP(O)(OH)2, whose phosphorus center is nucleophilic, attacking the positive center of the methylene carbon of the methylene ammonium ion to directly form a carbon-phosphorus bond. After deprotonation, a phosphonic acid methyl group is introduced onto the secondary amino group, resulting in phosphonic starch-grafted iminodiacetic acid microspheres. The phosphate ester crosslinking framework provides mechanical strength and acid resistance, the iminodiacetic acid group provides nitrogen-oxygen multidentate chelating sites, and the phosphonic acid group provides oxygen-containing coordination sites in strongly acidic environments.

[0022] According to a preferred embodiment of the present invention, in step A1, the stirring and gelatinization time at 80-85°C is 30-45 min, and the stirring time at 40-45°C is 4-6 h.

[0023] According to a preferred embodiment of the present invention, in step A2, the reaction time at 35-45°C is 4-6 hours, and the reaction time at 60-70°C is 6-10 hours.

[0024] According to a preferred embodiment of the present invention, in step A3, the temperature of vacuum drying is 50-60°C.

[0025] According to a preferred embodiment of the present invention, in step A4, the stirring reaction time at 65-75°C is 8-12 hours.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) This invention sequentially processes waste ternary lithium battery cathode sheets through drying, shearing, impact crushing, friction peeling, sieving, sorting, magnetic separation, grinding, and sieving to fully separate the cathode active material from the current collector, reducing the entry of metal fragments, magnetic impurities, and inactive components into the subsequent processing system, thereby obtaining waste ternary cathode powder with relatively uniform particle size. The synergistic leaching using sulfuric acid solution and hydrogen peroxide solution promotes lattice destruction of the cathode material and the dissolution of lithium, nickel, cobalt, and manganese, increasing the leaching degree of valuable metals. After washing the leaching filter residue with deionized water, the washing liquid is combined with the leaching filtrate to recover soluble metal components entrained on the surface and in the pores of the leaching filter residue, reducing the loss of valuable metals during filtration and washing, and improving the integrity of valuable metal recovery in the ternary metal leaching solution.

[0028] (2) This invention uses phosphonate-coated starch-grafted iminodiacetic acid microspheres to adsorb and remove impurities from ternary metal leachates. The spatial cross-linked framework formed by the phosphate-crosslinked corn starch microspheres can improve the mechanical strength, acid resistance, and solid-liquid separation performance of the phosphonate-coated starch-grafted iminodiacetic acid microspheres; the iminodiacetic acid groups have a nitrogen-oxygen polydentate coordination structure, and the phosphonate groups have multiple oxygen-containing coordination sites, which can synergistically complex and adsorb iron, aluminum, and copper ions. The pH of the ternary metal leachate is adjusted in stages using sodium hydroxide solution, which can gradually reduce the competition of hydrogen ions for coordination sites, so that the adsorption process of impurity ions proceeds smoothly and reduces the hydrolysis precipitation, entrainment loss, and non-selective adsorption of nickel, cobalt, and manganese caused by excessive local alkalinity. The impurity-loaded microspheres can be separated from the liquid phase by filtration, which is beneficial to improving the purity of the impurity-removed leachate and reducing the impurity content in the subsequent nickel-cobalt-manganese composite hydroxide.

[0029] (3) In this invention, ammonia and sodium hydroxide solution are used to co-precipitate the impurity-removing leachate under nitrogen protection. Ammonia can regulate the release rate of nickel, cobalt, and manganese ions through complexation, and slow down the local supersaturation caused by the addition of sodium hydroxide solution, so that the nucleation and crystal growth of the precipitate are more uniform. Nitrogen protection can reduce the adverse effects of manganese ion oxidation and external gas entering the alkaline reaction system, which is conducive to obtaining nickel-cobalt-manganese composite hydroxide with uniform composition and low impurity content. Lithium ions are mainly retained in the precipitate mother liquor. After heating and evaporation concentration, sodium carbonate solution is added to increase the lithium ion concentration and promote the formation of lithium carbonate filter cake. Stirring reaction, aging and filtration under heating can reduce the re-dissolution loss of lithium carbonate filter cake. This invention realizes the stepwise recovery of nickel, cobalt, manganese and lithium, and has the technical effects of less loss of valuable metals, better impurity removal effect, higher purity of recovered products and better process continuity. Detailed Implementation

[0030] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0031] Example 1

[0032] This embodiment provides a recycling process for the cathode material of waste ternary lithium batteries, including the following steps:

[0033] S1. Take the same batch of waste ternary lithium battery positive electrode sheets that have completed safe discharge and dismantling. Spread the waste ternary lithium battery positive electrode sheets flat on a stainless steel tray in a vacuum drying oven and dry them at 135℃ and 3kPa absolute pressure for 1.5h. After drying, cool them to 25℃ in a desiccator to obtain the dried positive electrode sheets. Weigh 100.0g of the dried positive electrode sheets and cut them into sheets with a side length of 10mm. Add the sheets to an impact crusher and crush them at 3000r / min for 3min. Then transfer them to a friction peeling device and peel them at 800r / min for 10min. Pass the resulting material through a 2mm sieve. The powder is then collected through a 0.25mm sieve. The powder is then subjected to air separation at a feed rate of 100g / min and an airflow velocity of 12m / s to remove lightweight membrane fragments and plastic fragments. Magnetic separation is then performed under a magnetic field strength of 0.30T to remove magnetic impurities. The magnetically separated powder is then ground at 400r / min for 20min and passed through a 75μm sieve to obtain waste ternary cathode powder. Several batches of dried cathode sheets are processed in parallel under the above conditions. The waste ternary cathode powder obtained from each batch is combined and mixed evenly. 100.0g of waste ternary cathode powder is weighed for use in step S2.

[0034] S2. Add 100.0g of waste ternary cathode powder to an acid-resistant reactor equipped with a mechanical stirrer, thermometer, dripping device, and condenser. Add 1050.0g of 2.1mol / L sulfuric acid solution, stir at 400r / min and heat to 65℃, then pre-stir at 65℃ and 400r / min for 20min. Add 80.0g of 30% hydrogen peroxide solution to the reactor at a uniform rate over 30min, maintaining the system temperature at 65℃ and controlling the feeding rate during the addition process. To avoid excessive foaming, after the feed was completed, the mixture was stirred and leached at 65℃ and 400r / min for 90min. After leaching, heating was stopped, and the reaction product was cooled to 25℃ and then filtered to obtain the leaching filtrate and leaching residue. The leaching residue was washed three times with deionized water, using 100.0g of deionized water each time. Each time, the leaching residue and deionized water were stirred and mixed for 10min and then filtered. The washing liquid was collected separately. The three washing liquids and the leaching filtrate were combined and stirred at 300r / min for 20min to obtain the ternary metal leaching solution.

[0035] S3. Transfer the ternary metal leaching solution to a reactor equipped with a mechanical stirrer and a pH electrode. Stir at 25℃ and 300 rpm, add 278.0 g of 30% sodium hydroxide solution dropwise, and adjust the pH to 3.4 as the endpoint. After reaching the endpoint, continue stirring for 10 min. Add 22.5 g of phosphonated starch-grafted iminodiacetic acid microspheres, and stir at 25℃ and 300 rpm for 45 min. Continue adding 18.0 g of 30% sodium hydroxide solution dropwise, adjusting the pH to 4.0 as the endpoint. At the endpoint, after reaching the adjustment endpoint, stirring was continued for 45 min at 25℃ and 300 r / min. Filtering was performed using a 20 μm pore size membrane to obtain a purified leachate and impurity-loaded microspheres. The impurity-loaded microspheres were added to 225.0 g of a 1.5 mol / L sulfuric acid solution, and the mixture was stirred and desorbed for 60 min at 25℃ and 300 r / min. Solid-liquid separation was performed using a 20 μm pore size membrane to obtain the desorbed solution. The desorbed solution was transferred to an electrolytic cell, with a titanium plate as the cathode and a coated titanium plate as the anode, and the electrolysis was performed at 30℃ and a current density of 200 A / m. 2 Under certain conditions, the copper ion concentration in the solution is reduced to below 0.05 g / L, and the cathode copper is recovered. 4.0 g of a 30% hydrogen peroxide solution is added to the electrowinning solution, and the mixture is stirred at 40°C and 300 r / min for 30 min to oxidize ferrous ions to ferric ions. Then, a 30% sodium hydroxide solution is added dropwise, and the pH is adjusted to 5.0. The mixture is stirred at 40°C and 300 r / min for 30 min, aged for 1 h, filtered, and the iron and aluminum slag is separated. The resulting filtrate, containing trace amounts of nickel, cobalt, and manganese, is returned to step S2 and reused as part of the deionized water for leaching.

[0036] S4. Transfer the purified leachate to a reactor equipped with a mechanical stirrer, thermometer, pH electrode, dripping device, and nitrogen protection device. Purge the reactor with nitrogen at a flow rate of 100 mL / min for 30 min to displace the air. While continuously purging with nitrogen, raise the temperature of the purified leachate to 55°C. Add 120.0 g of 25% ammonia solution and stir at 55°C and 400 r / min for 30 min. Add a 30% sodium hydroxide solution to the reactor at a uniform rate over 120 min. Add 320.0 g of 30% sodium hydroxide solution, adjusting the pH to 11.25 as the endpoint. Maintain the system temperature at 55℃ and the stirring speed at 500 r / min during the addition process. After addition, stir the mixture at 55℃, 500 r / min, and under nitrogen protection for 90 min. Then reduce the stirring speed to 100 r / min and age at 55℃ for 3 h. After aging, filter to obtain a filter cake and mother liquor. Wash the filter cake three times with deionized water, using 150.0 g of deionized water each time. After each 10-minute stirring and washing cycle, the mixture was filtered. The washed filter cake was dried at 105℃ for 12 hours and then cooled to 25℃ to obtain nickel-cobalt-manganese composite hydroxide. The mother liquor was transferred to an alkali-resistant evaporation reactor, stirred at 300 r / min, and heated to 90℃. The mixture was then evaporated and concentrated at 90℃ to a total mass of 450.0 g. 300.0 g of a 20% sodium carbonate solution was preheated to 90℃ and added uniformly to the concentrated mother liquor over 60 minutes, maintaining the temperature at 90℃ and stirring throughout the addition process. The stirring speed was 400 r / min. After the feeding was completed, the mixture was stirred at 90℃ and 400 r / min for 90 min. The stirring speed was then reduced to 100 r / min, and the mixture was aged at 90℃ for 3 h. After aging, the material temperature was kept not lower than 85℃ and the mixture was filtered to obtain lithium carbonate filter cake. The lithium carbonate filter cake was washed twice with deionized water at 92.5℃, using 50.0 g of deionized water each time. The mixture was filtered immediately after each wash. The washed lithium carbonate filter cake was dried at 120℃ for 6 h and then cooled to 25℃ to obtain lithium carbonate.

[0037] Preparation steps of phosphonate-modified starch grafted with iminodiacetic acid microspheres:

[0038] A1. Add 105.0g of corn starch to 1000.0g of deionized water and stir at 300r / min for 20min. Heat to 82.5℃ and stir at 300r / min for 40min to gelatinize. Cool to 42.5℃, add 11.0g of sodium trimetaphosphate, and stir at 300r / min for 10min. Add 25.5g of 20% sodium hydroxide solution dropwise, adjusting the pH to 11.15 as the endpoint to obtain the starch aqueous phase. Add 2850.0g of liquid paraffin and 75.0g of sorbitan monooleate to a reactor equipped with a mechanical stirrer, thermometer, and condenser. Stir at 500r / min for 20min at 42.5℃. Add the starch aqueous phase uniformly to the reactor over 30min, maintaining the temperature at 42.5℃ and the stirring speed at 500r / min during the addition process. After the addition is complete, maintain the temperature at 42.5℃. The reaction was stirred at 500 r / min for 5 h to obtain the reaction product. The reaction product was cooled to 25 °C, allowed to stand for 1 h, and the upper liquid paraffin layer was removed and then filtered to obtain the solid product. The solid product was washed three times with petroleum ether (500 g each time), then three times with anhydrous ethanol (400 g each time), and then five times with deionized water (500 g each time). The washed solid product was added to 500 g of deionized water and stirred at 300 r / min to disperse it. 24.6 g of 10% hydrochloric acid solution was added dropwise, and the pH was adjusted to 6.75 as the endpoint. The mixture was stirred for 20 min and then filtered. The obtained solid product was placed in a vacuum drying oven and dried at 55 °C and 10 kPa for 12 h. After cooling to 25 °C, it was ground and passed through a 150 μm sieve to obtain phosphate cross-linked corn starch microspheres.

[0039] A2. Add 100.0g of phosphate-crosslinked corn starch microspheres to 350.0g of deionized water and stir and disperse at 30℃ and 300r / min for 30min. Add 14.0g of sodium hydroxide and continue stirring at 30℃ and 300r / min for 30min. Add 30.0g of epichlorohydrin dropwise to the reaction system at a uniform rate over 30min, controlling the system temperature not to exceed 35℃ during the dropwise addition. After the dropwise addition is completed, raise the temperature to 40℃ and react at 40℃ and 400r / min for 5h to obtain the activated reaction product. Cool the activated reaction product to 25℃ and filter immediately to obtain activated microspheres. Wash the activated microspheres quickly four times with 300.0g of deionized water each time, stirring and dispersing for 3min each time, and then filter immediately. Add 70.0g of ethylenediamine to 400.0g of deionized water and stir at 300r / min for 10min. Add 145.0 g of 20% hydrochloric acid dropwise, adjusting the pH to 10.4 as the endpoint to obtain the grafting solution. Immediately add the activated microspheres to the grafting solution and stir and disperse at 25℃ and 300 r / min for 20 min. Then raise the temperature to 65℃ and react at 65℃ and 400 r / min for 8 h. After the reaction is complete, cool to 55℃ and distill under reduced pressure at 55℃ and 20 kPa until the mass of the reaction system is reduced to 55% of the mass before distillation. Stop the distillation, cool to 25℃, and filter to obtain the solid product. Wash the solid product 5 times with deionized water (400.0 g each time) and then wash twice with anhydrous ethanol (300.0 g each time). Dry the washed solid product under vacuum at 55℃ and 10 kPa for 12 h to obtain ethylenediamine-grafted cross-linked starch microspheres.

[0040] A3. 100.0g of ethylenediamine-grafted cross-linked starch microspheres were added to 450.0g of deionized water and stirred at 37.5℃ and 300r / min for 30min. 9.0g of 20% sodium hydroxide solution was added dropwise, and the pH was adjusted to 10.4 as the endpoint to obtain a mixed solution. 65.0g of sodium chloroacetate was added to 125.0g of deionized water and stirred at 25℃ and 300r / min until completely dissolved, yielding 190.0g of sodium chloroacetate solution. The sodium chloroacetate solution was divided into two equal portions of 95.0g each. The first portion of sodium chloroacetate solution was added to the mixed solution at a uniform rate over 30min, with 20% sodium hydroxide solution added dropwise during the addition process to maintain the pH at 10.0. After the addition was complete, the temperature was raised to 60℃ and stirred at 400r / min for 4h. The second portion of sodium chloroacetate solution was added to the mixed solution. Sodium hydroxide solution was added to the reaction system at a uniform rate over 30 min. During the addition process, 20% sodium hydroxide solution was added dropwise to maintain the pH of the system at 10.0. After the addition was completed, the reaction was stirred at 60℃ and 400 r / min for 4 h to obtain the reaction product. The reaction product was cooled to 27.5℃, and 42.0 g of 10% hydrochloric acid solution was added dropwise. The pH was adjusted to 5.25 as the endpoint. The mixture was stirred at 300 r / min for 30 min and then filtered to obtain a solid product. The solid product was washed 6 times with deionized water, using 400.0 g of deionized water each time. Each time, the mixture was stirred and dispersed for 10 min before being filtered until the pH of the final washing solution was 7.0. The washed solid product was vacuum dried at 55℃ and 10 kPa for 12 h to obtain iminodiacetic acid-grafted starch microspheres.

[0041] A4. Add 100.0g of iminodiacetic acid-grafted starch microspheres to 500.0g of deionized water and stir at 25℃ and 300r / min for 30min. Add 32.5g of phosphorous acid and continue stirring for 20min. Add 10.6g of 31% hydrochloric acid solution dropwise, adjusting the pH to 0.75 as the endpoint. Purge the reactor with nitrogen gas at a flow rate of 100mL / min for 30min to replace the air in the reactor. While continuously purging nitrogen gas, raise the temperature to 70℃ to obtain the reaction solution. Add 12.5g of paraformaldehyde to 100.0g of deionized water and stir at 60℃ and 300r / min for 30min to obtain a paraformaldehyde dispersion. Add the paraformaldehyde dispersion dropwise to the reaction solution at a uniform rate over 60min, maintaining the temperature at 70℃ and the stirring speed at 400r / min during the dropwise addition. After the addition was completed, the mixture was stirred for 10 h at 70℃, 400 r / min and nitrogen protection to obtain the reaction product. The reaction product was cooled to 32.5℃, and 340.0 g of 10% sodium hydroxide solution was added dropwise. The pH was adjusted to 6.0 as the endpoint. The mixture was stirred for 30 min at 300 r / min and then filtered to obtain a solid product. The solid product was washed 6 times with deionized water, using 400.0 g of deionized water each time. The mixture was stirred and dispersed for 10 min each time and then filtered until the pH of the final washing solution was 7.0. The washed solid product was vacuum dried at 55℃ and 10 kPa for 12 h, cooled to 25℃, ground and passed through sieves with pore sizes of 150 μm and 75 μm in sequence. The fraction with a particle size of 75-150 μm was collected to obtain phosphonate-modified starch-grafted iminodiacetic acid microspheres.

[0042] Example 2

[0043] The difference between this embodiment and Embodiment 1 is that this embodiment provides a recycling process for waste ternary lithium battery cathode materials, including the following steps:

[0044] S1. Spread the same batch of waste ternary lithium battery positive electrode sheets in a vacuum drying oven and dry them at 120℃ and 1kPa absolute pressure for 1 hour, then cool them to 25℃. Weigh 95.0g of the dried positive electrode sheets, cut them into sheets with a side length of 10mm, crush them by impact at 3000r / min for 3min, then rub them at 800r / min for 10min, and then sieve them through sieves with apertures of 2mm and 0.25mm. Perform air separation under an airflow velocity of 12m / s, and then perform magnetic separation under a magnetic field strength of 0.30T. Grind the magnetically separated powder at 400r / min for 20min and then pass it through a sieve with an aperture of 75μm. Repeat this process for several batches of dried positive electrode sheets under the same conditions, combine the resulting powders and mix them evenly. Weigh 95.0g of the waste ternary positive electrode powder for step S2.

[0045] S2. Add 95.0g of waste ternary cathode powder to 1000.0g of 2.0mol / L sulfuric acid solution, pre-stir at 60℃ and 400r / min for 20min, add 60.0g of 30% hydrogen peroxide solution at a uniform rate over 30min, and stir and leach at 60℃ and 400r / min for 60min; cool the reaction product to 25℃ and filter to obtain leachate and leach residue; wash the leach residue three times with deionized water, using 100.0g of deionized water each time, stirring and washing for 10min each time, combine the washing liquid and leachate and stir for 20min to obtain ternary metal leachate;

[0046] S3. Add 245.0 g of 30% sodium hydroxide solution dropwise to the ternary metal leaching solution at 25℃ and 300 r / min, adjusting the pH to 3.2 as the endpoint. Add 15.0 g of phosphonate-modified starch-grafted iminodiacetic acid microspheres and stir at 25℃ and 300 r / min for 30 min. Continue adding 15.0 g of 30% sodium hydroxide solution dropwise, adjusting the pH to 3.8 as the endpoint, and continue stirring at 25℃ and 300 r / min for 30 min. Filter to obtain the purified leaching solution and the impurity-loaded microspheres. Add the impurity-loaded microspheres to 150.0 g of 1.0 mol / L sulfuric acid solution and stir at 25℃ and 300 r / min for 45 min to desorb the impurities. Separate the solid and liquid phases to obtain the desorbed solution. Heat the desorbed solution at 30℃ and a current density of 200 A / m. 2 Under certain conditions, the copper ion concentration is reduced to below 0.05 g / L, and the cathode copper is recovered. The electrowinning solution is then added to 3.0 g of 30% hydrogen peroxide solution and stirred at 40°C for 30 min. A 30% sodium hydroxide solution is then added dropwise, with pH adjusted to 5.0 as the endpoint. After stirring for 30 min, the solution is aged for 1 h, filtered, and the iron and aluminum slag is separated. The resulting filtrate, containing trace amounts of nickel, cobalt, and manganese, is returned to step S2 for reuse.

[0047] S4. Nitrogen gas is introduced into the impurity-removing leachate at a flow rate of 100 mL / min for 30 min. Under nitrogen protection, the leachate is heated to 50℃, and 110.0 g of 25% ammonia solution is added. The mixture is stirred at 50℃ and 400 r / min for 30 min. 280.0 g of 30% sodium hydroxide solution is added dropwise over 120 min, with the pH adjusted to 11.0 as the endpoint. The mixture is stirred and reacted at 50℃ and 500 r / min for another 90 min, followed by aging at 50℃ and 100 r / min for 3 h. After filtration, the filter cake is washed three times with deionized water, using 150.0 g of water each time. Deionized water was dried at 105℃ for 12 hours to obtain nickel-cobalt-manganese composite hydroxide. The mother liquor of the precipitate was heated to 85℃ and evaporated and concentrated to 450.0 g. 280.0 g of sodium carbonate solution with a mass fraction of 20% was preheated to 85℃ and added to the concentrated mother liquor of the precipitate within 60 min. The mixture was stirred at 85℃ and 400 r / min for 60 min and then aged at 85℃ and 100 r / min for 2 hours. The material temperature was kept not lower than 85℃ and the mixture was filtered. The resulting lithium carbonate filter cake was washed twice with deionized water at 90℃, using 50.0 g of deionized water each time, and dried at 120℃ for 6 hours to obtain lithium carbonate.

[0048] Preparation steps of phosphonate-modified starch grafted with iminodiacetic acid microspheres:

[0049] A1. Add 100.0g of corn starch to 900.0g of deionized water and stir at 300r / min for 20min. Heat to 80℃ and stir at 300r / min for 30min to gelatinize. Cool to 40℃, add 8.0g of sodium tripolyphosphate, and stir at 300r / min for 10min. Add 21.0g of 20% sodium hydroxide solution dropwise, adjusting the pH to 10.8 as the endpoint to obtain the starch aqueous phase. Add 2500.0g of liquid paraffin and 60.0g of dehydrated sorbitan monooleate to the reactor and stir at 40℃ and 500r / min for 20min. Add the starch aqueous phase uniformly over 30min. After the addition is complete, stir at 40℃ and 500r / min... The reaction was stirred for another 4 hours. The reaction product was cooled to 25°C, allowed to stand for 1 hour, and the upper liquid paraffin layer was removed and then filtered. The obtained solid product was washed three times with petroleum ether (500 g each time), then three times with anhydrous ethanol (400 g each time), and then five times with deionized water (500 g each time). The washed solid product was added to 500 g of deionized water, and 20.2 g of 10% hydrochloric acid solution was added dropwise. The pH was adjusted to 6.5 as the endpoint. The mixture was stirred for 20 minutes and then filtered. The solid product was vacuum dried at 50°C and 10 kPa for 12 hours, ground, and passed through a 150 μm sieve to obtain phosphate cross-linked corn starch microspheres.

[0050] A2. Add 95.0g of phosphate-crosslinked corn starch microspheres to 300.0g of deionized water and stir and disperse at 25℃ and 300r / min for 30min. Add 12.0g of sodium hydroxide and continue stirring for 30min. Add 25.0g of epichlorohydrin dropwise over 30min at a uniform rate. After the addition is complete, raise the temperature to 35℃ and react at 35℃ and 400r / min for 4h. Cool the activated reaction product to 25℃ and filter immediately. Wash the obtained activated microspheres quickly with deionized water 4 times, using 300.0g of deionized water each time. Add 60.0g of ethylenediamine to 350.0g of deionized water and add 125.0g of 20% hydrochloric acid dropwise, adjusting the pH to 10. 0 was used as the adjustment endpoint to obtain the grafting solution; the activated microspheres were immediately added to the grafting solution and stirred at 25℃ and 300 r / min for 20 min, then heated to 60℃ and reacted at 60℃ and 400 r / min for 6 h; after the reaction was completed, the mixture was distilled under reduced pressure at 50℃ and 20 kPa until the mass of the reaction system decreased to 55% of the mass before reduced pressure distillation, cooled to 25℃ and filtered; the solid product was washed 5 times with deionized water (400.0 g of deionized water each time) and then washed twice with anhydrous ethanol (300.0 g of anhydrous ethanol each time); the solid product was vacuum dried at 50℃ and 10 kPa for 12 h to obtain ethylenediamine-grafted cross-linked starch microspheres;

[0051] A3. Add 95.0g of ethylenediamine-grafted cross-linked starch microspheres to 400.0g of deionized water and stir and disperse at 35℃ and 300r / min for 30min. Add 8.0g of 20% sodium hydroxide solution dropwise, adjusting the pH to 10.0 as the endpoint to obtain a mixed solution. Add 55.0g of sodium chloroacetate to 100.0g of deionized water and stir until completely dissolved to obtain 155.0g of sodium chloroacetate solution. Divide the sodium chloroacetate solution into two equal portions, 77.5g each. Add the first portion of sodium chloroacetate solution to the mixed solution within 30min, while simultaneously adding 47.0g of 20% sodium hydroxide solution dropwise to maintain the pH of the system at 10.0. The addition is then complete. The temperature was then raised to 55℃, and the reaction was carried out at 55℃ and 400 r / min for 4 h. The second sodium chloroacetate solution was added to the reaction system over 30 min, while 48.0 g of 20% sodium hydroxide solution was added dropwise to maintain the pH of the system at 10.0. After the addition was completed, the reaction was continued at 55℃ and 400 r / min for 4 h. The reaction product was cooled to 25℃, and 35.0 g of 10% hydrochloric acid solution was added dropwise, with pH adjusted to 5.0 as the endpoint. The mixture was stirred for 30 min and then filtered. The solid product was washed 6 times with deionized water, using 400.0 g of deionized water each time, and then vacuum dried at 50℃ and 10 kPa for 12 h to obtain iminodiacetic acid-grafted starch microspheres.

[0052] A4. Add 95.0 g of iminodiacetic acid-grafted starch microspheres to 450.0 g of deionized water, stir and disperse at 25℃ and 300 r / min for 30 min, add 25.0 g of phosphorous acid, and dropwise add 8.1 g of 31% hydrochloric acid solution, adjusting the pH to 0.5 as the endpoint; purge with nitrogen gas at a flow rate of 100 mL / min for 30 min, and heat to 65℃ under nitrogen protection to obtain the reaction solution; add 10.0 g of paraformaldehyde to 80.0 g of deionized water, stir at 60℃ and 300 r / min for 30 min to obtain a paraformaldehyde dispersion; add paraformaldehyde... The aldehyde dispersion was added dropwise to the reaction solution at a uniform rate over 60 min, and the reaction was stirred for 8 h at 65 °C, 400 r / min and under nitrogen protection. The reaction product was cooled to 30 °C, and 260.0 g of 10% sodium hydroxide solution was added dropwise. The pH was adjusted to 5.5 as the endpoint, and the mixture was stirred for 30 min and then filtered. The solid product was washed 6 times with 400.0 g of deionized water each time, and then vacuum dried at 50 °C and 10 kPa for 12 h. The product was then ground and sieved, and the fraction with a particle size of 75-150 μm was collected to obtain phosphonate-modified starch-grafted iminodiacetic acid microspheres.

[0053] Example 3

[0054] The difference between this embodiment and Embodiment 1 is that this embodiment provides a recycling process for waste ternary lithium battery cathode materials, including the following steps:

[0055] S1. Spread the same batch of waste ternary lithium battery positive electrode sheets in a vacuum drying oven and dry them for 2 hours at 150°C and 5 kPa absolute pressure, then cool them to 25°C. Weigh 105.0 g of the dried positive electrode sheets, cut them into sheets with a side length of 10 mm, crush them by impact at 3000 r / min for 3 min, then rub them at 800 r / min for 10 min, and pass them through sieves with apertures of 2 mm and 0.25 mm in sequence. Perform air separation under an airflow velocity of 12 m / s, and then perform magnetic separation under a magnetic field strength of 0.30 T. Grind the magnetically separated powder at 400 r / min for 20 min and pass it through a sieve with an aperture of 75 μm. Perform parallel processing of several batches of dried positive electrode sheets under the same conditions, combine the resulting powders and mix them evenly. Weigh 105.0 g of the waste ternary positive electrode powder for step S2.

[0056] S2. Add 105.0g of waste ternary cathode powder to 1100.0g of 2.2mol / L sulfuric acid solution, and pre-stir at 70℃ and 400r / min for 20min. Add 100.0g of 30% hydrogen peroxide solution at a uniform rate over 30min, and stir and leach at 70℃ and 400r / min for 120min. Cool the reaction product to 25℃ and filter to obtain leachate and leach residue. Wash the leach residue with deionized water 3 times, using 100.0g of deionized water each time, and stir and wash for 10min each time. Combine the washing liquid and leachate and stir for 20min to obtain ternary metal leachate.

[0057] S3. Add 315.0 g of 30% sodium hydroxide solution (by mass) to the ternary metal leaching solution at 25℃ and 300 r / min, adjusting the pH to 3.6 as the endpoint. Add 30.0 g of phosphonate-modified starch-grafted iminodiacetic acid microspheres and stir at 25℃ and 300 r / min for 60 min. Continue adding 22.0 g of 30% sodium hydroxide solution (by mass), adjusting the pH to 4.2 as the endpoint, and continue stirring at 25℃ and 300 r / min for 60 min. Filter to obtain a purified leaching solution and impurity-loaded microspheres. Add the impurity-loaded microspheres to 300.0 g of 2.0 mol / L sulfuric acid solution and stir at 25℃ and 300 r / min for 75 min to desorb the impurities. Separate the solid and liquid phases to obtain the desorbed solution. Heat the desorbed solution at 30℃ and a current density of 200 A / m. 2 Under certain conditions, the copper ion concentration is reduced to below 0.05 g / L, and the cathode copper is recovered. The electrowinning solution is then added to 5.0 g of 30% hydrogen peroxide solution and stirred at 40°C for 30 min. A 30% sodium hydroxide solution is added dropwise, and the pH is adjusted to 5.0 as the endpoint. After stirring for 30 min, the solution is aged for 1 h, filtered, and the iron and aluminum slag is separated. The resulting filtrate, containing trace amounts of nickel, cobalt, and manganese, is returned to step S2 for reuse.

[0058] S4. Nitrogen gas is introduced into the impurity-removing leachate at a flow rate of 100 mL / min for 30 min. Under nitrogen protection, the leachate is heated to 60℃, and 130.0 g of 25% ammonia solution is added. The mixture is stirred at 60℃ and 400 r / min for 30 min. 360.0 g of 30% sodium hydroxide solution is added dropwise over 120 min, and the pH is adjusted to 11.5 as the endpoint. The mixture is stirred and reacted at 60℃ and 500 r / min for another 90 min, followed by aging at 60℃ and 100 r / min for 3 h. After filtration, the filter cake is washed three times with deionized water, using 150.0 g of water each time. Deionized water was dried at 105℃ for 12 hours to obtain nickel-cobalt-manganese composite hydroxide. The mother liquor of the precipitate was heated to 95℃ and evaporated and concentrated to 450.0 g. 320.0 g of sodium carbonate solution with a mass fraction of 20% was preheated to 95℃ and added to the concentrated mother liquor of the precipitate within 60 min. The mixture was stirred and reacted at 95℃ and 400 r / min for 120 min, and then aged at 95℃ and 100 r / min for 4 hours. The material temperature was kept not lower than 90℃ and the mixture was filtered. The resulting lithium carbonate filter cake was washed twice with 50.0 g of deionized water at 95℃ each time and dried at 120℃ for 6 hours to obtain lithium carbonate.

[0059] Preparation steps of phosphonate-modified starch grafted with iminodiacetic acid microspheres:

[0060] A1. Add 110.0g of corn starch to 1100.0g of deionized water, stir and disperse at 300r / min for 20min, heat to 85℃, stir and gelatinize at 85℃ and 300r / min for 45min, cool to 45℃, add 14.0g of sodium trimetaphosphate, stir at 300r / min for 10min, add 30.2g of 20% sodium hydroxide solution dropwise, and adjust the pH to 11.5 as the endpoint to obtain the starch aqueous phase; add 3200.0g of liquid paraffin and 90.0g of dehydrated sorbitan monooleate to the reactor, stir at 45℃ and 500r / min for 20min, add the starch aqueous phase uniformly to the reactor over 30min, and after the addition is complete, heat at 45℃. The reaction was stirred at 500 r / min for 6 h. The reaction product was cooled to 25 °C, allowed to stand for 1 h, and the upper liquid paraffin layer was removed and then filtered. The solid product was washed three times with petroleum ether (500 g each time), three times with anhydrous ethanol (400 g each time), and five times with deionized water (500 g each time). The solid product was added to 500 g of deionized water, and 29.8 g of 10% hydrochloric acid solution was added dropwise. The pH was adjusted to 7.0 as the endpoint. The mixture was stirred for 20 min and then filtered. The product was vacuum dried at 60 °C and 10 kPa for 12 h. The mixture was then ground and passed through a 150 μm sieve to obtain phosphate ester cross-linked corn starch microspheres.

[0061] A2. Add 105.0g of phosphate-crosslinked corn starch microspheres to 400.0g of deionized water and stir at 35℃ and 300r / min for 30min. Add 16.0g of sodium hydroxide and continue stirring for 30min. Add 35.0g of epichlorohydrin dropwise over 30min. After the addition is complete, react at 45℃ and 400r / min for 6h. Cool the activated reaction product to 25℃ and filter immediately. Wash the activated microspheres quickly four times with 300.0g of deionized water each time. Add 80.0g of ethylenediamine to 450.0g of deionized water and add 165.0g of 20% hydrochloric acid dropwise, adjusting the pH to 10.8. As the endpoint adjustment, the grafting solution was obtained. Activated microspheres were added to the grafting solution and stirred at 25℃ and 300 r / min for 20 min. The temperature was then raised to 70℃ and reacted at 70℃ and 400 r / min for 10 h. After the reaction, the mixture was distilled under reduced pressure at 60℃ and 20 kPa until the mass of the reaction system decreased to 55% of its initial mass before distillation. The mixture was then cooled to 25℃ and filtered. The solid product was washed five times with deionized water (400 g each time) and twice with anhydrous ethanol (300 g each time). It was then vacuum dried at 60℃ and 10 kPa for 12 h to obtain ethylenediamine-grafted cross-linked starch microspheres.

[0062] A3. Add 105.0g of ethylenediamine-grafted cross-linked starch microspheres to 500.0g of deionized water and stir and disperse at 40℃ and 300r / min for 30min. Add 11.0g of 20% sodium hydroxide solution dropwise, adjusting the pH to 10.8 as the endpoint to obtain a mixed solution. Add 75.0g of sodium chloroacetate to 150.0g of deionized water and stir until completely dissolved to obtain 225.0g of sodium chloroacetate solution. Divide the sodium chloroacetate solution into two equal portions, 112.5g each. Add the first portion of sodium chloroacetate solution to the mixed solution within 30min, while simultaneously adding 20% ​​sodium hydroxide solution dropwise to maintain the pH of the system at 10.4. The addition is then complete. The temperature was then raised to 65℃, and the reaction was carried out at 65℃ and 400 r / min for 4 h. The second sodium chloroacetate solution was added to the reaction system within 30 min, and 65.0 g of 20% sodium hydroxide solution was added dropwise to maintain the pH of the system at 10.4. After the addition was completed, the reaction was continued at 65℃ and 400 r / min for 4 h. The reaction product was cooled to 30℃, and 50.0 g of 10% hydrochloric acid solution was added dropwise. The pH was adjusted to 5.5 as the endpoint. After stirring for 30 min, the mixture was filtered. The solid product was washed 6 times with deionized water, using 400.0 g of deionized water each time, and then vacuum dried at 60℃ and 10 kPa for 12 h to obtain iminodiacetic acid-grafted starch microspheres.

[0063] A4. Add 105.0 g of iminodiacetic acid-grafted starch microspheres to 550.0 g of deionized water, stir and disperse at 25℃ and 300 r / min for 30 min, add 40.0 g of phosphorous acid, and dropwise add 13.2 g of 31% hydrochloric acid solution, adjusting the pH to 1.0 as the endpoint; purge with nitrogen gas at a flow rate of 100 mL / min for 30 min, and heat to 75℃ under nitrogen protection to obtain the reaction solution; add 15.0 g of paraformaldehyde to 120.0 g of deionized water, stir at 60℃ and 300 r / min for 30 min to obtain a paraformaldehyde dispersion; add the poly... Formaldehyde dispersion was added dropwise to the reaction solution at a uniform rate over 60 min, and the reaction was stirred for 12 h at 75 °C, 400 r / min and under nitrogen protection. The reaction product was cooled to 35 °C, and 420.0 g of 10% sodium hydroxide solution was added dropwise, with pH adjusted to 6.5 as the endpoint. After stirring for 30 min, the mixture was filtered. The solid product was washed 6 times with deionized water, using 400.0 g of deionized water each time, and vacuum dried for 12 h at 60 °C and 10 kPa absolute pressure. The product was then ground and sieved, and the fraction with a particle size of 75-150 μm was collected to obtain phosphonate-modified starch-grafted iminodiacetic acid microspheres.

[0064] Comparative Example 1

[0065] The difference between this comparative example and Example 1 is that step A4 is omitted, and the 22.5g iminodiacetic acid-grafted starch microspheres obtained in step A3 are directly used in step S3 to replace the 22.5g phosphonated starch-grafted iminodiacetic acid microspheres. The rest is the same as in Example 1.

[0066] Comparative Example 2

[0067] The difference between this comparative example and Example 1 is that step A3 is omitted; the 100.0g ethylenediamine-grafted cross-linked starch microspheres obtained in step A2 are subjected to phosphonation treatment according to step A4 of Example 1, except that 100.0g iminodiacetic acid-grafted starch microspheres are replaced with 100.0g ethylenediamine-grafted cross-linked starch microspheres to obtain phosphonated ethylenediamine-grafted cross-linked starch microspheres; in step S3, 22.5g phosphonated starch-grafted iminodiacetic acid microspheres are replaced with 22.5g phosphonated ethylenediamine-grafted cross-linked starch microspheres, and the rest is the same as in Example 1.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 1 is that steps A2, A3, and A4 are omitted. The 22.5g of phosphate cross-linked corn starch microspheres obtained in step A1 are directly used in step S3 to replace the 22.5g of phosphonate-modified starch grafted iminodiacetic acid microspheres. The rest is the same as in Example 1.

[0070] A series of standardized tests were conducted on the recycling processes of waste ternary lithium battery cathode materials described in Examples 1-3 and Comparative Examples 1-3.

[0071] The same batch of waste ternary lithium battery cathode sheets were processed according to the processes described in Examples 1-3 and Comparative Examples 1-3, respectively. Each group underwent three parallel tests independently, and the arithmetic mean of the three test results was taken as the final result. Waste ternary cathode powder was collected before the start of step S2, ternary metal leachate was collected after the end of step S2 and after the washing solutions were combined, impurity-removed leachate was collected after the end of step S3 and after the filtration, and nickel-cobalt-manganese composite hydroxide and lithium carbonate were collected after the end of step S4. Before sampling the liquid samples, they were stirred at 25°C and 300 r / min for 10 min, and the actual total volume of the liquid samples at 25°C was recorded. After the solid samples were mixed evenly, the fractions were reduced using the quartering method. When testing the lithium, nickel, cobalt, manganese, iron, aluminum and copper content in the waste ternary cathode powder, the waste ternary cathode powder was ground to a particle size of no more than 0.25 mm, 0.1000 g of the sample was weighed and placed in a microwave digestion vessel, 10.0 mL of a mixed acid formed by mixing hydrochloric acid and nitric acid in a volume ratio of 3:1 was added, and the mixture was sealed and then microwave digested. After digestion, the solution was cooled to 25°C and transferred to a 200 mL volumetric flask. It was then diluted to volume with deionized water and mixed thoroughly. After filtration, 5.00 mL of the filtrate was transferred to another 200 mL volumetric flask, and 8.0 mL of nitric acid solution (1:1 volume ratio) was added. The solution was then diluted to volume with deionized water and mixed thoroughly. The concentrations of each element were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). The volume fraction of nitric acid in both the standard solution and the test solution was adjusted to 2%. Simultaneously, reagent blanks and parallel sample tests were performed. For the ternary metal leaching solution and the impurity-removed leaching solution, 1.00 mL of the well-mixed liquid sample was transferred to a 100 mL volumetric flask, 2.0 mL of nitric acid was added, and the solution was diluted to volume with deionized water. If the concentrations of nickel, cobalt, and manganese exceeded the calibration curve range, further stepwise dilution was performed. The concentrations of lithium, nickel, cobalt, manganese, iron, aluminum, and copper were determined using ICP-AES. The mass of each element in the liquid phase was calculated by multiplying the measured concentration by the corresponding total liquid volume.

[0072] The overall leaching rate of nickel, cobalt, and manganese is calculated by dividing the sum of the masses of nickel, cobalt, and manganese in the ternary metal leachate by the sum of the masses of nickel, cobalt, and manganese in the waste ternary cathode powder, and then multiplying by 100%.

[0073] The comprehensive removal rate of iron, aluminum and copper is calculated by dividing the difference between the sum of the masses of iron, aluminum and copper in the ternary metal leachate and the sum of the masses of iron, aluminum and copper in the impurity removal leachate by the sum of the masses of iron, aluminum and copper in the ternary metal leachate and then multiplying by 100%.

[0074] The nickel, cobalt, and manganese retention rates are calculated by dividing the sum of the masses of nickel, cobalt, and manganese in the impurity-removing leaching solution by the sum of the masses of nickel, cobalt, and manganese in the ternary metal leaching solution, and then multiplying by 100%.

[0075] For the testing of nickel-cobalt-manganese composite hydroxide, the sample was dried at 105℃ for 2 hours, cooled to 25℃ in a desiccator, and 0.2000g of the sample was weighed and placed in a beaker. 10.0mL of hydrochloric acid and 2.0mL of nitric acid were added, a watch glass was covered, and the sample was heated at low temperature until it was completely dissolved. After cooling, the sample was transferred to a 100mL volumetric flask, diluted to volume with deionized water, and mixed well. An appropriate amount of the test solution was taken and the contents of nickel, cobalt, manganese, iron, aluminum, and copper were determined by inductively coupled plasma atomic emission spectrometry. The determination of iron, aluminum, and copper adopted the calibration range and matrix matching method consistent with the impurity analysis of the nickel-cobalt-manganese ternary precursor. The total impurity content of the nickel-cobalt-manganese composite hydroxide was the sum of the contents of iron, aluminum, and copper, and the unit was mg / kg.

[0076] The comprehensive recovery rate of nickel, cobalt, and manganese is calculated by multiplying the dried mass of the obtained nickel-cobalt-manganese composite hydroxide by the sum of the mass fractions of nickel, cobalt, and manganese therein, dividing by the sum of the mass fractions of nickel, cobalt, and manganese in the waste ternary cathode powder, and then multiplying by 100%.

[0077] The comprehensive lithium recovery rate is calculated by multiplying the dried mass of lithium carbonate, the measured mass fraction of lithium carbonate, and the theoretical mass fraction of lithium in lithium carbonate (18.79%), dividing by the mass of lithium in the waste ternary cathode powder, and then multiplying by 100%. For inductively coupled plasma atomic emission spectrometry (ICP-AES) tests, at least 5 concentration points are used to establish calibration curves, the correlation coefficient of the calibration curves is not less than 0.999, the concentration of the analyte in the blank sample should be lower than the method detection limit, and the relative deviation of parallel test results should not be greater than 2.0%.

[0078] For lithium carbonate purity testing, the lithium carbonate sample was dried at 255℃ for 2 hours, then cooled to 25℃ in a desiccator. 0.5000g of the sample was weighed and placed in a 150mL beaker, and 50.0mL of pre-boiled and sealed deionized water was added. The pH composite electrode and burette head were immersed in the solution, and stirring was started. Dynamic potentiometric titration was performed using a standard hydrochloric acid solution of approximately 0.50mol / L, calibrated with anhydrous sodium carbonate. 20.0mL of the standard hydrochloric acid solution was added first, and the mixture was stirred for 30s. Titration continued until a significant jump in potential was observed. The volume of the standard hydrochloric acid solution consumed was recorded. A blank test was also performed simultaneously. Each sample was measured twice in parallel. The mass fraction of lithium carbonate was calculated based on the volume of the standard hydrochloric acid solution consumed after deducting the blank value, the actual concentration of the standard hydrochloric acid solution, and the sample mass.

[0079] The performance test data above are shown in Table 1.

[0080] Table 1 Performance Test Results

[0081]

[0082] As can be seen from the above, the comprehensive leaching rates of nickel, cobalt, and manganese in Examples 1-3 were 98.82%, 96.68%, and 99.21%, respectively, indicating that within the specified range of sulfuric acid solution concentration, hydrogen peroxide solution dosage, leaching temperature, and leaching time, sufficient leaching of nickel, cobalt, and manganese in waste ternary cathode powder could be achieved. The comprehensive leaching rates of nickel, cobalt, and manganese in Comparative Examples 1-3 were 98.76-98.85%, which were close to those in Example 1. This is because Comparative Examples 1-3 only changed the impurity removal material used in step S3, without changing the pretreatment and leaching conditions in steps S1 and S2. This indicates that the difference in subsequent performance between the examples and the comparative examples mainly stems from the difference in the functional group structure of the impurity removal material, rather than from the difference in the degree of leaching.

[0083] The comprehensive removal rates of iron, aluminum, and copper in Examples 1-3 reached 95.72-98.91%, which were significantly higher than those of Comparative Example 1 (89.84%), Comparative Example 2 (81.26%), and Comparative Example 3 (62.18%). Among them, Comparative Example 1, which was not modified with phosphonic acid, had a comprehensive removal rate of iron, aluminum, and copper that was 8.51 percentage points lower than that of Example 1. This indicates that the oxygen-containing coordination sites provided by the phosphonic acid groups can enhance the complexation and adsorption of iron, aluminum, and copper impurity ions by phosphonic starch-grafted iminodiacetic acid microspheres.

[0084] Comparative Example 2, which was not modified by iminodiacetic acid grafting, had a 17.09 percentage point lower overall removal rate of iron, aluminum, and copper compared to Example 1, indicating that the nitrogen-oxygen polydentate coordination structure of the iminodiacetic acid group plays an important role in the selective capture of impurity ions.

[0085] Comparative Example 3, which only used phosphate-crosslinked corn starch microspheres, showed a 36.17 percentage point decrease in the overall removal rate of iron, aluminum, and copper compared to Example 1. This indicates that the phosphate-crosslinked corn starch microspheres mainly play a role in structural support and solid-liquid separation. Without iminodiacetic acid groups and phosphonic acid groups, it is difficult to obtain sufficient selective impurity removal capabilities.

[0086] Examples 1-3, while improving the removal rates of iron, aluminum, and copper, still achieved nickel, cobalt, and manganese retention rates of 98.06-98.81%, higher than the 96.43-97.94% of Comparative Examples 1-3. This indicates that the combination of phosphonate-coated starch-grafted iminodiacetic acid microspheres and segmented pH adjustment can preferentially complex impurity ions while reducing non-selective adsorption, hydrolysis precipitation, and filtration entrainment losses of nickel, cobalt, and manganese. This solves the problem of difficulty in achieving both impurity removal rate and valuable metal retention rate in existing precipitation and impurity removal processes.

[0087] The total impurity content of the nickel-cobalt-manganese composite hydroxides obtained in Examples 1-3 was only 315-860 mg / kg, which was significantly lower than that of Comparative Example 1 (1980 mg / kg), Comparative Example 2 (3650 mg / kg), and Comparative Example 3 (7420 mg / kg). Among them, Example 3 reduced the impurity content by 7105 mg / kg compared with Comparative Example 3. This shows that the thorough removal of iron, aluminum, and copper before co-precipitation can effectively reduce the co-precipitation, adsorption, and encapsulation of impurity ions during the formation of nickel-cobalt-manganese composite hydroxides, thus solving the problem of high impurity content and limited subsequent utilization of nickel-cobalt-manganese composite hydroxides obtained by existing processes.

[0088] The overall recovery rates of nickel, cobalt, and manganese in Examples 1-3 were 95.41-96.36%, which were higher than those in Comparative Examples 1-3 (93.62-94.60%). This indicates that the iminodiacetic acid grafting modification and phosphonic acid modification did not come at the cost of significantly increasing the loss of nickel, cobalt, and manganese, but rather improved the overall recovery effect of nickel, cobalt, and manganese by increasing the selectivity of impurity removal.

[0089] The overall lithium recovery rate of Examples 1-3 reached 90.31-93.22%, and the lithium carbonate purity reached 98.96-99.46%, both higher than those of Comparative Examples 1-3. This indicates that reducing the iron, aluminum, and copper content in the impurity removal leachate and precipitation mother liquor can reduce the entrainment loss of lithium during impurity hydrolysis precipitation, nickel-cobalt-manganese co-precipitation, and subsequent filtration and washing processes, and reduce the interference of impurity salts on the precipitation and crystallization purification process of lithium carbonate.

[0090] In summary, this invention provides a stable microsphere framework by cross-linking corn starch microspheres with phosphate esters, forms a synergistic coordination structure through iminodiacetic acid groups and phosphonic acid groups, and combines segmented pH adjustment, ammonia complexation co-precipitation, heating and concentration of the precipitate mother liquor, lithium precipitation with sodium carbonate solution, and high-temperature deionized water washing to achieve highly efficient and selective removal of iron, aluminum, and copper, low-loss retention of nickel, cobalt, and manganese, reduced impurity content in nickel-cobalt-manganese composite hydroxides, and improved lithium recovery rate and lithium carbonate purity. This solves the technical problems of insufficient impurity removal selectivity, large loss of valuable metals, low purity of recovered products, and poor comprehensive recovery effect of nickel, cobalt, manganese, and lithium in existing wet recycling processes for waste ternary lithium battery cathode materials.

Claims

1. A recycling process for cathode materials from waste ternary lithium batteries, characterized in that, Includes the following steps: S1. By weight, dry the waste ternary lithium battery positive electrode sheet to obtain the dried positive electrode sheet; cut 95-105 parts of the dried positive electrode sheet, crush it by impact and peel it by friction, and then screen, sort and magnetically separate it in sequence, grind and sieve it to obtain waste ternary positive electrode powder. S2. Add 95-105 parts of waste ternary cathode powder to 1000-1100 parts of sulfuric acid solution and stir at 60-70℃; add 60-100 parts of hydrogen peroxide solution and stir to leach; after leaching, cool and filter to obtain leachate and leaching residue; wash the leaching residue with deionized water to obtain washing solution; combine the washing solution and leachate to obtain ternary metal leachate; S3. Adjust the pH of the ternary metal leaching solution to 3.2-3.6 with sodium hydroxide solution, add 15.0-30.0 parts of phosphonate-modified starch-grafted iminodiacetic acid microspheres, and stir; continue to add sodium hydroxide solution, adjust the pH to 3.8-4.2, stir, and filter to obtain a purified leaching solution and impurity-loaded microspheres; add the impurity-loaded microspheres to sulfuric acid solution and stir, perform solid-liquid separation to obtain an desorption solution; electrolyze the desorption solution to obtain copper and the electrolyzed solution; add hydrogen peroxide solution to the electrolyzed solution, stir, adjust the pH, and separate iron and aluminum; return the resulting solution containing trace amounts of nickel, cobalt, and manganese to S2; S4. Under nitrogen protection, the impurity-removing leachate is heated, ammonia water is added, followed by sodium hydroxide solution to adjust the pH, the reaction is stirred, aged, and filtered to obtain filter cake and precipitate mother liquor; the filter cake is washed with deionized water and dried to obtain nickel-cobalt-manganese composite hydroxide; the precipitate mother liquor is heated, evaporated and concentrated, sodium carbonate solution is added, the reaction is stirred, aged, and filtered to obtain lithium carbonate filter cake; the lithium carbonate filter cake is washed with deionized water and dried.

2. The recycling process for waste ternary lithium battery cathode materials according to claim 1, characterized in that, In step S1, the drying temperature is 120-150℃; the drying time is 1-2 hours.

3. The recycling process for waste ternary lithium battery cathode materials according to claim 1, characterized in that, In step S2, the concentration of the sulfuric acid solution is 2.0-2.2 mol / L; the stirring and leaching time is 60-120 min; and the mass fraction of the hydrogen peroxide solution is 30%.

4. The recycling process for waste ternary lithium battery cathode materials according to claim 1, characterized in that, In step S3, after adding phosphonate-modified starch-grafted iminodiacetic acid microspheres, the stirring time is 30-60 min. After adjusting the pH to 3.8-4.2, the stirring time is continued for another 30-60 min.

5. The recycling process for waste ternary lithium battery cathode materials according to claim 1, characterized in that, In step S4, the impurity-removing leachate is heated to 50-60℃; sodium hydroxide solution is added to adjust the pH to 11.0-11.5; the precipitate mother liquor is heated to 85-95℃; after adding sodium carbonate solution, the reaction is stirred for 60-120 min and aged for 2-4 h.

6. The recycling process for waste ternary lithium battery cathode materials according to any one of claims 1-5, characterized in that, The preparation steps of the phosphonate-modified starch-grafted iminodiacetic acid microspheres include: A1. By weight, 100.0-110.0 parts of corn starch were added to 900-1100 parts of deionized water and stirred to gelatinize at 80-85℃. After cooling to 40-45℃, 8.0-14.0 parts of sodium trimetaphosphate were added, and the pH was adjusted to 10.8-11.5 with sodium hydroxide solution to obtain an aqueous starch phase. 2500-3200 parts of liquid paraffin and 60.0-90.0 parts of dehydrated sorbitan monooleate were added to a reactor and stirred at 40-45℃. The aqueous starch phase was then added to the reactor, and the reaction was continued with stirring to obtain a reaction product. The reaction product was allowed to stand and separate into layers, then filtered to obtain a solid product. The solid product was washed successively with petroleum ether, anhydrous ethanol, and deionized water, and the pH was adjusted to 6.5-7.0 with hydrochloric acid solution. The product was then vacuum dried at 50-60℃ and sieved to obtain phosphate-crosslinked corn starch microspheres. A2. Add 95.0-105.0 parts of phosphate-crosslinked corn starch microspheres to 300-400 parts of deionized water, add 12.0-16.0 parts of sodium hydroxide, and stir at 25-35℃; add 25.0-35.0 parts of epichlorohydrin dropwise, and react at 35-45℃ to obtain an activated reaction product; filter the activated reaction product to obtain activated microspheres; wash the activated microspheres with deionized water, and then add them to a grafting solution composed of 60.0-80.0 parts of ethylenediamine and 350-450 parts of deionized water, adjust the pH to 10.0-10.8 with hydrochloric acid, and react at 60-70℃; distill under reduced pressure, filter, and obtain a solid product; wash the solid product successively with deionized water and anhydrous ethanol, and dry under vacuum at 50-60℃ to obtain ethylenediamine-grafted crosslinked starch microspheres; A3. Add 95.0-105.0 parts of ethylenediamine-grafted cross-linked starch microspheres to 400-500 parts of deionized water, stir at 35-40℃, and adjust the pH to 10.0-10.8 with sodium hydroxide solution to obtain a mixed solution; add 55.0-75.0 parts of sodium chloroacetate to 100-150 parts of deionized water, stir to obtain a sodium chloroacetate solution; mix the sodium chloroacetate solution and the mixed solution, stir and react at 55-65℃ to obtain a reaction product; cool the reaction product to 25-30℃, adjust the pH to 5.0-5.5 with hydrochloric acid, filter to obtain a solid product; wash the solid product with deionized water, and vacuum dry to obtain iminodiacetic acid-grafted starch microspheres; A4. Add 95.0-105.0 parts of iminodiacetic acid-grafted starch microspheres to 450-550 parts of deionized water, stir and disperse, add 25.0-40.0 parts of phosphorous acid, and adjust the pH to 0.5-1.0 with hydrochloric acid; under nitrogen protection, heat to 65-75℃ to obtain a reaction solution; add 10.0-15.0 parts of paraformaldehyde to 80-120 parts of deionized water to obtain a paraformaldehyde dispersion; mix the paraformaldehyde dispersion with the reaction solution, stir and react at 65-75℃ to obtain a reaction product; cool the reaction product to 30-35℃, adjust the pH to 5.5-6.5 with sodium hydroxide solution, filter, and obtain a solid product; wash the solid product with deionized water, vacuum dry at 50-60℃, and sieve.

7. The recycling process for waste ternary lithium battery cathode materials according to claim 6, characterized in that, In step A1, the stirring and gelatinization time is 30-45 minutes at 80-85℃, and the stirring time is 4-6 hours at 40-45℃.

8. The recycling process for waste ternary lithium battery cathode materials according to claim 6, characterized in that, In step A2, the reaction time is 4-6 hours at 35-45℃ and 6-10 hours at 60-70℃.

9. The recycling process for waste ternary lithium battery cathode materials according to claim 6, characterized in that, In step A3, the vacuum drying temperature is 50-60℃.

10. The recycling process for waste ternary lithium battery cathode materials according to claim 6, characterized in that, In step A4, the reaction is stirred at 65-75℃ for 8-12 hours.

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