Method for recycling valuable metal from waste NCM ternary positive electrode material and application

Abstract

The invention provides a method for recycling valuable metal from a waste NCM ternary positive electrode material and application, and belongs to the technical field of recycling of waste lithium ion batteries. The glycine, the malonic acid and the water are mixed and then subjected to heat treatment, so that the glycine and the malonic acid can improve the stability of a mixed acid solution through intermolecular acting forces such as hydrogen bonds, and the leaching effect of metal ions during acid leaching is improved; according to the method, after the leaching liquid and the leaching residues are separated, the leaching liquid is subjected to high-temperature treatment, and lithium manganate is obtained. The method comprises the following steps: calcining the leaching residues, and carrying out high-temperature treatment on nickel hydrogen malonate and cobalt hydrogen malonate in the leaching residues to obtain a cobalt oxide and nickel oxide mixture; the result of the embodiment shows that the valuable metal can be efficiently recycled from the waste NCM ternary positive electrode material, the recycling rate of lithium, nickel, cobalt and manganese is close to 100%, and the separation degree of lithium manganese and nickel cobalt is good.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling waste lithium-ion batteries, and in particular to a method and application of recycling valuable metals from waste NCM ternary cathode materials. Background Art

[0002] With the popularity of electric vehicles and the widespread use of lithium-ion batteries, the number of waste lithium-ion batteries has increased rapidly. x Co y Mn z O2(NCM) is an important component of the positive electrode material of lithium-ion batteries. It contains valuable metals such as lithium, nickel, cobalt and manganese, which have great recycling potential and reuse value.

[0003] Traditional methods for recovering valuable metals in NCM include pyrolysis and wet recovery. Pyrolysis has problems such as high energy consumption; wet recovery requires the use of acid and alkali reagents, which has problems such as secondary pollution. Therefore, it is particularly important to develop efficient and environmentally friendly recovery technologies. As a safe and inexpensive solvent, organic acid is considered to be a green alternative to the traditional acid leaching method in the recovery of lithium-ion battery positive electrode materials. However, the existing acid leaching method using organic acid as a solvent is to selectively or completely leach the metal elements in the battery positive electrode material, and then obtain metal elements, metal compounds and positive electrode materials through extraction, precipitation, replacement and distillation. This process requires strict process parameter control. Although metal products can be recovered, the processing and recovery process is often accompanied by problems such as secondary pollution, high leaching solution requirements, low product purity, high production costs and complex process flows.

[0004] Therefore, there is an urgent need to provide a method for efficiently leaching and effectively recovering valuable metals from waste NCM ternary positive electrode materials. Summary of the invention

[0005] The purpose of the present invention is to provide a method and application for efficiently leaching and effectively recovering valuable metals in waste NCM ternary positive electrode materials.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for recovering valuable metals from waste NCM ternary cathode materials, comprising the following steps:

[0008] (1) mixing glycine, malonic acid, and water and then heat-treating the mixture to obtain a mixed acid solution;

[0009] (2) mixing the mixed acid solution obtained in step (1) with the waste ternary lithium battery positive electrode material, and performing acid leaching to obtain a leachate and a leach residue;

[0010] (3) The leaching solution obtained in the step (2) is sequentially dried and first calcined to obtain lithium manganate;

[0011] (4) The leaching residue obtained in the step (2) is secondarily calcined to obtain a mixture of nickel oxide and cobalt oxide.

[0012] Preferably, the molar ratio of glycine to malonic acid in the step (1) is 1:(1 - 4).

[0013] Preferably, the mass of water in the step (1) accounts for 20 - 40% of the total mass of glycine, malonic acid and water.

[0014] Preferably, the temperature of the heat treatment in the step (1) is 60 - 80°C; the time of the heat treatment is 30 - 120 min.

[0015] Preferably, the ratio of the mass of the spent ternary lithium battery cathode material to the volume of the mixed acid solution in the step (2) is (40 - 50) g:1 L.

[0016] Preferably, the temperature of the acid leaching in the step (2) is 80 - 120°C; the time of the acid leaching is 60 - 120 min.

[0017] Preferably, the temperature of the drying in the step (3) is 100 - 120°C; the time of the drying is 6 - 10 h.

[0018] Preferably, the temperature of the first calcination in the step (3) is 400 - 800°C; the time of the first calcination is 6 - 10 h.

[0019] Preferably, the temperature of the second calcination in the step (4) is 400 - 800°C; the time of the second calcination is 6 - 10 h.

[0020] The present invention also provides an application of a metal oxide as a PMS catalyst for degrading organic wastewater, and the metal oxide is a mixture of nickel oxide and cobalt oxide obtained by the method according to the above technical solution.

[0021] The present invention provides a method for recovering valuable metals from waste NCM ternary cathode materials, comprising the following steps: glycine, malonic acid and water are mixed and then subjected to heat treatment to obtain a mixed acid solution; the mixed acid solution is mixed with the waste ternary lithium battery cathode material for acid leaching to obtain a leachate and a leach residue; the leachate is sequentially dried and first calcined to obtain lithium manganate; the leach residue is secondarily calcined to obtain a mixture of nickel oxide and cobalt oxide. By mixing glycine, malonic acid and water and then performing heat treatment, the present invention can enable glycine and malonic acid to combine through intermolecular forces such as hydrogen bonds, improve the stability of the mixed acid solution, and thus enhance the leaching effect of metal ions during acid leaching; the present invention uses the mixed acid solution to acid-leach the waste ternary lithium battery cathode material, and the protons contained in malonic acid and glycine act as oxygen acceptors to enable efficient metal leaching; among them, malonic acid has the ability to specifically bind to nickel and cobalt ions. During the nickel-cobalt precipitation separation process, the ionization of malonic acid is divided into two steps. In the first step, hydrogen malonate is mainly ionized, and in the second step, a small amount of malonate is ionized. Hydrogen malonate and malonate will compete for the coordination complexation of nickel and cobalt. Therefore, increasing the concentration of malonic acid itself is used to reduce the overall pH of the solution to inhibit the second-step ionization, promote the combination of nickel and cobalt with hydrogen malonate, and thus precipitate nickel hydrogen malonate and cobalt hydrogen malonate; the amino group contained in glycine acts as a complexing ligand, and glycine forms a more stable complex with manganese ions and is stably dissolved in the leachate. Therefore, manganese ions will not precipitate; and the combination of lithium ions with malonic acid and glycine are all water-soluble lithium salts, so they exist in the leachate in a stable ionic state. Therefore, by using the mixed acid solution to acid-leach the waste ternary lithium battery cathode material, the present invention can enable lithium and manganese to form in the leachate and nickel and cobalt to form in the leach residue. After separating the leachate and the leach residue, the present invention can remove the solvent in the leachate by drying the leachate, so that lithium manganate is obtained when the solid is first calcined. The present invention secondarily calcines the leach residue, and nickel hydrogen malonate and cobalt hydrogen malonate in the leach residue decompose during the second calcination to obtain a mixture of cobalt oxide and nickel oxide. The results of the examples show that the method provided by the present invention can efficiently recover valuable metals from waste NCM ternary cathode materials, and the recovery rates of lithium, nickel, cobalt and manganese are close to 100%, and there is a good separation degree between lithium-manganese and nickel-cobalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the leaching rate of each metal ion in the leachate obtained by the methods of Examples 1-4 and Comparative Examples 1-2 of the present invention;

[0023] Figure 2 is the XRD pattern of the waste NCM811 ternary lithium battery cathode material used in Example 1 of the present invention and the prepared leach residue;

[0024] Figure 3 is the XRD pattern of the black powder obtained in step (3) of Example 4 of the present invention;

[0025] Figure 4 XRD pattern of the solid obtained in step (4) of Example 4 of the present invention;

[0026] Figure 5 Leaching rates of various metal ions in the leachate obtained by the methods of Examples 4-6 and Comparative Examples 3-7 of the present invention;

[0027] Figure 6 Leaching rates of various metal ions in the leachate obtained by the methods of Examples 4, 7 and Comparative Examples 8-9 of the present invention;

[0028] Figure 7 Analysis diagram of the degradation kinetics of the nickel oxide and cobalt oxide mixture prepared by the present invention. Detailed implementation mode

[0029] The present invention provides a method for recovering valuable metals from waste NCM ternary cathode materials, comprising the following steps:

[0030] (1) Mix glycine, malonic acid and water and then perform heat treatment to obtain a mixed acid solution;

[0031] (2) Mix the mixed acid solution obtained in step (1) with the waste ternary lithium battery cathode material and perform acid leaching to obtain a leachate and a leaching residue;

[0032] (3) Sequentially dry and perform the first calcination on the leachate obtained in step (2) to obtain lithium manganate;

[0033] (4) Perform the second calcination on the leaching residue obtained in step (2) to obtain a nickel oxide and cobalt oxide mixture.

[0034] In the present invention, unless otherwise specified, the chemical reagents used in the present invention are all commercially available products well-known to those skilled in the art.

[0035] The present invention mixes glycine, malonic acid and water and then performs heat treatment to obtain a mixed acid solution.

[0036] In the present invention, the molar ratio of glycine to malonic acid is preferably 1:(1-4). As an implementation mode of the present invention, the molar ratio of glycine to malonic acid can be 1:1, 1:2, 1:3 or 1:4. The present invention uses glycine and malonic acid to prepare a mixed acid, and the protons contained in malonic acid and glycine act as oxygen acceptors to enable efficient leaching of metals.

[0037] In the present invention, the mass of water preferably accounts for 20-40% of the total mass of glycine, malonic acid and water. As an embodiment of the present invention, the mass of water may account for 20%, 25%, 30%, 35% or 40% of the total mass of glycine, malonic acid and water. By controlling the mass of water within the above range in the present invention, an appropriate acid concentration can be obtained for the mixed acid solution, improving the efficiency of acid leaching.

[0038] The present invention has no special limitation on the method of mixing glycine, malonic acid and water. A conventional mixing method can be used to mix the three evenly.

[0039] In the present invention, the temperature of the heat treatment is 60-80°C. As an embodiment of the present invention, the temperature of the heat treatment may be 60°C, 65°C, 70°C, 75°C or 80°C. In the present invention, the time of the heat treatment is preferably 30-120 min. As an embodiment of the present invention, the time of the heat treatment may be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min or 120 min. In the present invention, the heat treatment is preferably carried out under stirring. The present invention has no special limitation on the rotation speed of the stirring, as long as it can promote the uniform mixing of glycine, malonic acid and water during the heat treatment. Through the heat treatment in the present invention, the two organic acids, glycine and malonic acid, can be well miscible, and the mixed acid solution can be made more stable through intermolecular forces such as hydrogen bonds.

[0040] After obtaining the mixed acid solution, the present invention mixes the mixed acid solution with the spent ternary lithium battery cathode material and carries out acid leaching to obtain a leaching solution and leaching residues.

[0041] The present invention has no special limitation on the source of the spent ternary lithium battery cathode material, and any conventional spent ternary lithium battery cathode material can be used. In the examples of the present invention, the spent ternary lithium battery cathode material is preferably a spent NCM811 ternary cathode material; the molar ratio of nickel element, cobalt element and manganese element in the NCM811 ternary cathode material can be 8:1:1.

[0042] In the present invention, the mass ratio of the cathode material of the waste ternary lithium battery to the volume of the mixed acid solution is preferably (40 - 50) g: 1 L. As an embodiment of the present invention, the mass ratio of the cathode material of the waste ternary lithium battery to the volume of the mixed acid solution can be 40 g: 1 L, 45 g: 1 L or 50 g: 1 L. By controlling the mass ratio of the cathode material of the waste ternary lithium battery to the volume of the mixed acid solution within the above range, the cathode material of the waste ternary lithium battery can be fully dispersed in the mixed acid solution, improving the leaching effect of metals during acid leaching.

[0043] The present invention has no special limitation on the method of mixing the mixed acid solution and the cathode material of the waste ternary lithium battery, and it is only necessary to mix the two evenly.

[0044] In the present invention, the temperature of the acid leaching is preferably 80 - 120 °C. As an embodiment of the present invention, the temperature of the acid leaching can be 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C or 120 °C. In the present invention, the time of the acid leaching is preferably 60 - 120 min. As an embodiment of the present invention, the time of the acid leaching can be 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min or 120 min. By carrying out the acid leaching at the above temperature and time, the metal ions can be fully leached, and nickel and cobalt ions can combine with malonic acid and glycine to form nickel hydrogen malonate and cobalt hydrogen malonate, fully converting nickel and cobalt ions into precipitates.

[0045] In the present invention, the acid leaching is preferably carried out under stirring, and the rotation speed of the stirring is preferably 200 - 600 r / min, more preferably 400 r / min. By stirring in the present invention, mass transfer can be promoted, enabling the cathode material of the waste ternary lithium battery to fully contact with the mixed acid solution.

[0046] The present invention preferably filters the mixture obtained from the acid leaching to obtain a leaching solution and leaching residue. The present invention has no special limitation on the filtering method, and a conventional filtering method can be used as long as solid-liquid separation can be achieved sufficiently.

[0047] After obtaining the leaching solution and leaching residue, the present invention sequentially dries and first calcines the leaching solution to obtain lithium manganate.

[0048] In the present invention, the temperature of the drying is preferably 100 - 120 °C, more preferably 110 - 120 °C; the time of the drying is preferably 6 - 10 h, more preferably 8 - 9 h. By drying at the above temperature in the present invention, the solvent in the leaching solution can be evaporated.

[0049] In the present invention, the temperature of the first calcination is preferably 400 - 800 °C. As an embodiment of the present invention, the temperature of the first calcination can be 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C or 800 °C. In the present invention, the time of the first calcination is preferably 6 - 10 h. As an embodiment of the present invention, the time of the first calcination can be 6 h, 7 h, 8 h, 9 h or 10 h. Through the first calcination, the present invention can decompose the acidic compounds in the solid obtained by drying and convert metal ions into lithium manganate.

[0050] In the present invention, the temperature of the second calcination is preferably 400 - 800 °C. As an embodiment of the present invention, the temperature of the second calcination can be 400 °C, 450 °C, 500 °C, 550 °C, 600 °C, 650 °C, 700 °C, 750 °C or 800 °C. In the present invention, the time of the second calcination is preferably 6 - 10 h. As an embodiment of the present invention, the time of the second calcination can be 6 h, 7 h, 8 h, 9 h or 10 h. Through the second calcination, the present invention can decompose the residual acidic compounds in the filter residue to obtain a mixture of nickel oxide and cobalt oxide.

[0051] The method provided by the present invention uses a mixed acid solution obtained by mixing glycine and malonic acid to leach the cathode material of waste ternary lithium batteries, converting nickel ions and cobalt ions into precipitates and separating them from the leachate. By subjecting the leachate to the first calcination, lithium manganate is obtained. The present invention subjects the leach residue to the second calcination to obtain a mixture of cobalt oxide and nickel oxide from nickel hydrogen malonate and cobalt hydrogen malonate in the leach residue.

[0052] The present invention also provides an application of a metal oxide as a PMS catalyst for degrading organic wastewater, and the metal oxide is a mixture of nickel oxide and cobalt oxide obtained by the method described in the above technical solution.

[0053] The mixture of cobalt oxide and nickel oxide obtained by the method described in the above technical solution of the present invention can be used as a PMS catalyst.

[0054] In the present invention, the organic pollutants in the organic wastewater preferably include one or more of bisphenol A, 4-chlorophenol, phenol and carbamazepine. The present invention uses the mixture of nickel oxide and cobalt oxide as a catalyst and has an excellent catalytic effect on the degradation of the above-mentioned various organic pollutants.

[0055] In the present invention, the concentration of the organic pollutants in the organic wastewater is preferably 0.01 - 0.03 mol / L, and more preferably 0.02 mol / L.

[0056] In the present invention, the mass ratio of the PMS catalyst to the volume of the organic wastewater is preferably (0.03 - 0.06) g : (10 - 50) mL, more preferably 0.05 g : 50 mL. The PMS catalyst provided by the present invention is a mixture of nickel oxide and cobalt oxide obtained by the method described in the above technical solution, which has high activity and can have an excellent catalytic degradation effect on the organic wastewater when added in a small amount. The present invention has no special limitation on the mass ratio of nickel oxide and cobalt oxide in the mixture of nickel oxide and cobalt oxide. The main components of the mixture obtained by the above technical solution are nickel oxide and cobalt oxide, and both can be used as catalysts for degrading organic wastewater.

[0057] In the present invention, the method for applying the metal oxide as a PMS catalyst to degrade organic wastewater is preferably to mix the metal oxide with the organic wastewater and carry out a degradation reaction to obtain the degraded wastewater.

[0058] In the present invention, the degradation reaction is preferably carried out at room temperature. In the present invention, the time of the degradation reaction is preferably 40 - 80 min, more preferably 60 min. Under the above temperature and time, the present invention can fully degrade the organic pollutants in the organic wastewater.

[0059] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0060] Example 1

[0061] A method for recycling valuable metals from waste NCM ternary cathode materials, the steps are as follows:

[0062] (1) After mixing glycine, malonic acid and water, heat and stir at 80 °C for 120 min for heat treatment to obtain a mixed acid solution;

[0063] Among them, the molar ratio of glycine to malonic acid is 1 : 4, and the mass of water accounts for 30% of the total mass of glycine, malonic acid and water;

[0064] (2) Mix the mass of the waste NCM811 ternary lithium battery cathode material with the volume of the mixed acid solution obtained in step (1) at a ratio of 50 g : 1 L, and carry out acid leaching by stirring at a speed of 400 r / min at a temperature of 80 °C for 60 min, and then filter to obtain a leachate and a leach residue;

[0065] (3) Dry the leachate obtained in the step (2) at 105 °C for 8 h, and then calcine the obtained solid at 800 °C for the first time for 10 h to obtain a black powder, which is lithium manganate;

[0066] (4) Calcinate the leaching residue obtained in the step (2) at 450 °C for the second time for 4 h to obtain a solid, which is a mixture of nickel oxide and cobalt oxide.

[0067] Example 2

[0068] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 1 in that the acid leaching temperature in step (2) is 90 °C. The remaining steps and parameters are the same as those in Example 1.

[0069] Example 3

[0070] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 1 in that the acid leaching temperature in step (2) is 100 °C. The remaining steps and parameters are the same as those in Example 1.

[0071] Example 4

[0072] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 1 in that the acid leaching temperature in step (2) is 120 °C. The remaining steps and parameters are the same as those in Example 1.

[0073] Comparative Example 1

[0074] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 1 in that the acid leaching temperature in step (2) is 60 °C. The remaining steps and parameters are the same as those in Example 1.

[0075] Comparative Example 2

[0076] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 1 in that the acid leaching temperature in step (2) is 70 °C. The remaining steps and parameters are the same as those in Example 1.

[0077] Test Example 1

[0078] Use an atomic absorption spectrometer to test the leachates obtained by the methods of Examples 1 to 4 and Comparative Examples 1 to 2 respectively, and obtain the leaching rates of various metal ions in the leachates as Figure 1 shown. From Figure 1It can be seen that when the acid leaching temperature is 80 - 120 °C, lithium is leached almost 100%; when it is 80 - 90 °C, manganese is leached almost 100%; when it is 90 - 120 °C, the leaching rate of manganese reaches over 80%. While at 80 - 120 °C, nickel and cobalt are hardly leached (below 10%). Thus, it can be seen that the method provided by the present invention can make lithium and manganese enter the leaching solution through acid leaching and be separated from nickel and cobalt by precipitation.

[0079] The XRD patterns of the used waste NCM811 ternary lithium battery cathode material and the prepared leaching residue in Example 1 are as Figure 2 shown. In Figure 2 , PDF87 - 1562 is the standard card of lithium nickel cobalt oxide, PDF24 - 1642 is the standard card of nickel hydrogen malonate dihydrate, PDF24 - 1838 is the standard card of cobalt hydrogen malonate dihydrate, and Leach residue refers to the leaching residue. From Figure 2 it can be seen that the phase composition of the characteristic peaks of the waste NCM811 ternary lithium battery cathode material used in the present invention is mainly oxides of lithium, nickel, cobalt and manganese, and the phase composition of the characteristic peaks of the prepared leaching residue is nickel hydrogen malonate dihydrate and cobalt hydrogen malonate dihydrate. This indicates that the main existing forms of the leaching residue prepared by the present invention are insoluble nickel hydrogen malonate dihydrate and cobalt hydrogen malonate dihydrate.

[0080] The XRD pattern of the black powder obtained in step (3) of Example 4 is as Figure 3 shown. In Figure 3 , PDF#27 - 1252 is the standard card of Li2MnO3. From Figure 3 it can be seen that after the leaching solution is dried and first calcined, the main phase of the material is lithium manganate, which indicates that acid leaching can well separate lithium, manganese, nickel and cobalt.

[0081] The XRD pattern of the solid obtained in step (4) of Example 4 is as Figure 4 shown. In Figure 4 , PDF#70 - 1849 and PDF#89 - 7313 are the standard cards of Ni and NiO respectively. Since the used powder is high - nickel and cobalt - poor powder (NCM811), and the cobalt peak and nickel peak in the phase are highly coincident, and the phase of cobalt is not matched in the result, which belongs to a reasonable range.

[0082] Example 5

[0083] A method for recycling valuable metals from waste NCM ternary cathode materials is different from Example 4 in that the acid leaching time in step (2) is 90 min. The remaining steps and parameters are the same as those in Example 4.

[0084] Example 6

[0085] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the acid leaching time in step (2) is 120 min. The remaining steps and parameters are the same as those in Example 4.

[0086] Comparative Example 3

[0087] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the acid leaching time in step (2) is 5 min. The remaining steps and parameters are the same as those in Example 4.

[0088] Comparative Example 4

[0089] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the acid leaching time in step (2) is 10 min. The remaining steps and parameters are the same as those in Example 4.

[0090] Comparative Example 5

[0091] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the acid leaching time in step (2) is 20 min. The remaining steps and parameters are the same as those in Example 4. [[ID=,20]]

[0092] Comparative Example 6

[0093] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the acid leaching time in step (2) is 30 min. The remaining steps and parameters are the same as those in Example 4.

[0094] Comparative Example 7

[0095] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the acid leaching time in step (2) is 45 min. The remaining steps and parameters are the same as those in Example 4.

[0096] Test Example 2

[0097] The leachates obtained by the methods of Examples 4 to 6 and Comparative Examples 3 to 7 were tested using an atomic absorption spectrometer, and the leaching rates of various metal ions in the leachates were as Figure 5 shown. It can be seen from Figure 5 that when the acid leaching time is 60 - 120 min, lithium and manganese are almost 100% leached, while nickel (leaching rate is about 2%) and cobalt (leaching rate is about 2%) are hardly leached. Thus, it can be seen that the method provided by the present invention can make lithium and manganese enter the leachate through acid leaching and precipitate and separate from nickel and cobalt.

[0098] Example 7

[0099] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the mass of the waste NCM811 ternary lithium battery cathode material in step (2) and the volume of the mixed acid solution obtained in step (1) are in the ratio of 40 g:1 L. The remaining steps and parameters are the same as those in Example 4.

[0100] Comparative Example 8

[0101] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the mass of the waste NCM811 ternary lithium battery cathode material in step (2) and the volume of the mixed acid solution obtained in step (1) are in the ratio of 20 g:1 L. The remaining steps and parameters are the same as those in Example 4.

[0102] Comparative Example 9

[0103] A method for recovering valuable metals from waste NCM ternary cathode materials, which is different from Example 4 in that the mass of the waste NCM811 ternary lithium battery cathode material in step (2) and the volume of the mixed acid solution obtained in step (1) are in the ratio of 30 g:1 L. The remaining steps and parameters are the same as those in Example 4.

[0104] Test Example 3

[0105] An atomic absorption spectrometer was used to test the leachates obtained by the methods of Example 4, 7 and Comparative Examples 8-9, and the leaching rates of various metal ions in the leachates were as Figure 6 shown. From Figure 6 it can be seen that when the mass of the waste NCM811 ternary lithium battery cathode material and the volume of the mixed acid solution obtained in step (1) are in the ratio of 40 g:1 L and 50 g:1 L, lithium is leached almost 100%, the leaching of manganese reaches more than 75%, while nickel and cobalt are hardly leached (nickel 1.8%, cobalt 2.0%). It can be seen from this that the method provided by the present invention can make lithium and manganese enter the leachate through acid leaching and precipitate and separate from nickel and cobalt.

[0106] Application Example 1

[0107] After mixing 0.05 g of the nickel oxide and cobalt oxide mixture prepared in Example 4, 10 mmol / L of PMS and 50 mL of a bisphenol A solution with a concentration of 1 mmol / L, the mixture was degraded at 25 °C for 60 min. The results obtained were as Figure 7 shown. From Figure 7 it can be seen that the pollutants can be completely removed in 30 min and the catalytic degradation process conforms to pseudo-first-order kinetics, and the first-order kinetic constant is 0.1305 min -1 , which indicates that the recovered nickel oxide and cobalt oxide mixture can be used as a nickel-cobalt catalyst and exhibits good catalytic efficiency.

[0108] As can be seen from the above results, the method provided by the present invention can efficiently recover valuable metals from waste NCM ternary cathode materials. The recovery rates of nickel, cobalt, manganese and lithium are close to 100%. It can effectively recover valuable metals in waste NCM ternary cathode materials, and the obtained mixture of nickel oxide and cobalt oxide can be used as a nickel-cobalt catalyst, showing good catalytic efficiency.

[0109] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for recovering valuable metals from waste NCM ternary cathode materials, comprising the following steps: (1) Mix glycine, malonic acid and water and then perform heat treatment to obtain a mixed acid solution; (2) Mix the mixed acid solution obtained in step (1) with the waste ternary lithium battery cathode material and perform acid leaching to obtain a leachate and a leach residue; (3) Sequentially dry and perform the first calcination on the leachate obtained in step (2) to obtain lithium manganate; (4) Perform the second calcination on the leach residue obtained in step (2) to obtain a mixture of nickel oxide and cobalt oxide.

2. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that, In step (1), the molar ratio of glycine to malonic acid is 1:(1-4).

3. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that In step (1), the mass of water accounts for 20-40% of the total mass of glycine, malonic acid and water.

4. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that, In step (1), the heat treatment temperature is 60-80 °C; the heat treatment time is 30-120 min.

5. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that, In step (2), the mass ratio of the waste ternary lithium battery cathode material to the volume of the mixed acid solution is (40-50) g:1 L.

6. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that, In step (2), the acid leaching temperature is 80-120 °C; the acid leaching time is 60-120 min.

7. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, wherein, In step (3), the drying temperature is 100-120 °C; the drying time is 6-10 h.

8. The method for recycling valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that, In step (3), the first calcination temperature is 400-800 °C; the first calcination time is 6-10 h.

9. The method for recovering valuable metals from waste NCM ternary cathode materials according to claim 1, characterized in that, In step (4), the second calcination temperature is 400-800 °C; the second calcination time is 6-10 h.

10. Application of a metal oxide as a PMS catalyst for degrading organic wastewater, wherein the metal oxide is a mixture of nickel oxide and cobalt oxide obtained by the method according to any one of claims 1-9.

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