Recycling method of positive plate of waste lithium ion battery

Abstract

The invention relates to a method for recycling a positive plate of a waste lithium ion battery. The recycling method comprises the following steps: (1) crushing the positive plate of the waste lithium ion battery to obtain positive mixed powder; (2) carrying out aluminothermic reduction roasting on the positive electrode mixed powder to obtain a first roasted product, and carrying out first leaching to obtain first leached residues and a lithium-rich solution; (3) the first leaching residues are mixed with a second leaching agent, second leaching is carried out, second leaching liquid and second leaching residues are obtained, and the second leaching liquid comprises a lithium-containing solution; and (4) the second leaching residues and a transformation agent are mixed and roasted, a second roasting product is obtained, third leaching is conducted on the second roasting product through a third leaching agent, an aluminum-containing compound is obtained, and a nickel-cobalt-manganese solution is obtained through recycling. According to the recycling method adopting the stepped selective leaching process, the recycling rate of valuable metal and the purity of nickel-cobalt-manganese products are improved, and the flow of the recycling process is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery material recycling, and particularly to a method for recycling waste lithium ion battery positive electrode sheets. Background Art

[0002] In recent years, with the rapid development of the new energy industry, the recycling of retired power batteries has attracted much attention, among which the recycling of valuable metals in retired power batteries has received great attention. The existing power battery recycling mainly focuses on pretreatment, extraction of valuable metals, and control of secondary pollution. In the research of pretreatment, problems such as removal of organic pollutants, separation of the positive electrode material from the current collector, and enrichment of valuable metals need to be solved. The main process methods used are discharging, disassembling, pyrolysis, crushing, and screening. After the above processes, battery black powder rich in positive and negative electrodes is obtained. In terms of the extraction of valuable metals, the battery black powder is acid-leached, precipitated to remove impurities, and separated by extraction to recover nickel, cobalt, and manganese elements respectively, and then lithium elements are recovered from the raffinate wastewater. The existing recycling technologies usually have problems such as low separation efficiency, high energy consumption, poor selectivity of metal extraction, complicated process flow, and large amounts of three wastes emissions, which seriously hinder the healthy and rapid development of China's power battery recycling industry. Therefore, the development of a short-process and high-selectivity power battery recycling process has attracted great attention.

[0003] The valuable metals in lithium ion batteries are mainly concentrated on the positive electrode material. The positive electrode material is generally prepared by coating on an aluminum foil current collector and applied to the process of battery assembly. In order to achieve short-process recycling of valuable metals, researchers have developed methods for short-range recycling of valuable metals directly from the positive electrode sheets. This method mainly focuses on separating the positive electrode material from the aluminum foil current collector, and the separated positive electrode material is then subjected to traditional wet leaching. In the positive electrode sheet, the aluminum foil has reducibility, and the positive electrode material has oxidability. The idea of using the reducibility of the aluminum foil and the oxidability of the positive electrode material to recycle valuable metals has gradually attracted attention.

[0004] The prior art CN111206151A discloses a method for recovering valuable metals in the positive electrode sheet of a ternary lithium-ion power battery. This method utilizes the reducibility of aluminum and the characteristics that cobalt, nickel, and manganese in the positive electrode sheet are all high-valent oxides, and adopts the aluminothermic reduction method to directly recover cobalt, nickel, and manganese in the positive electrode sheet. The reduced metal ingot is a cobalt-nickel-manganese alloy, and the slag is separated by ball milling and water leaching to recover lithium and aluminum. The prior art CN111663042A discloses a method for recovering valuable metals in waste lithium-ion batteries. This method performs a melting reaction on the positive electrode sheet and a flux of waste lithium-ion batteries under anaerobic conditions, separates the molten slag, and cools the melt to obtain; the positive electrode sheet includes a positive electrode active material and an aluminum current collector, and the positive electrode active material is at least one of lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium manganese oxide, and lithium-rich manganese-based ternary materials. Among them, the positive electrode sheet and the flux are subjected to a melting reaction under anaerobic conditions at 1000-1500°C, and after the reaction, molten slag and a cobalt-nickel-manganese alloy are obtained; after the molten slag is acid-leached to extract lithium to prepare lithium carbonate, an aluminum hydroxide product is obtained by an alkali leaching process.

[0005] However, the aluminothermic reduction process used in the above prior art is prone to generate a refractory lithium metaaluminate (LiAlO 2 ) phase, resulting in low lithium recovery efficiency and increased recovery difficulty; moreover, the recovered nickel-cobalt-manganese product is an alloy with low product purity and cannot be directly used for the re-preparation of battery materials; in addition, the above prior art fails to achieve the stepwise selective leaching of lithium and transition metals, resulting in a long metal recovery process flow and low recovery rate.

[0006] Therefore, aiming at the above-mentioned defects existing in the prior art, providing a recovery method that can improve the recovery rates of lithium, nickel, and cobalt in the positive electrode sheet of waste lithium-ion batteries, improve the purity of nickel-cobalt-manganese products, and shorten the process flow is an urgent technical problem to be solved at present. Summary of the Invention

[0007] To solve the above technical problems, the purpose of the present invention is to provide a method for recovering the positive electrode sheet of waste lithium-ion batteries. In the recovery method provided by the present invention, the continuous two-stage leaching adopted solves the problem of difficult leaching of lithium metaaluminate in the aluminothermic reduction roasting product, improves the leaching rate of lithium, and the transformation roasting combined with the leaching process adopted realizes the selective leaching of nickel, cobalt, and manganese elements, and a nickel-cobalt-manganese solution with high purity and high recovery rate is recovered. The stepwise selective leaching process adopted by the present invention also effectively shortens the process flow of valuable metal recovery.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a method for recovering the positive electrode sheet of waste lithium-ion batteries, and the recovery method includes the following steps:

[0010] (1) Crush the spent lithium-ion battery cathode to obtain a cathode mixed powder; the cathode mixed powder includes at least the crushed aluminum foil and lithium nickel cobalt manganese oxide cathode material;

[0011] (2) Perform aluminothermic reduction roasting on the cathode mixed powder to obtain a first roasted product, the first roasted product includes lithium oxide, lithium meta-aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide; perform a first leaching on the first roasted product with a first leaching agent to obtain a first leached residue and a recovered lithium-rich solution;

[0012] (3) Mix the first leached residue with a second leaching agent and perform a second leaching to obtain a second leachate and a second leached residue, the second leachate includes a lithium-containing solution;

[0013] (4) Mix the second leached residue with a transformation agent, roast to obtain a second roasted product, perform a third leaching on the second roasted product with a third leaching agent to obtain an aluminum-containing compound and a recovered nickel cobalt manganese solution.

[0014] The present invention uses a first leaching process to leach the lithium oxide in the second roasted product obtained by aluminothermic reduction roasting of the cathode mixed powder, and a recovered lithium-rich solution is obtained. The lithium-rich solution can be used to prepare lithium salts; then, a second leaching process is continuously used to selectively leach the lithium in the lithium meta-aluminate of the second roasted product to obtain a lithium-containing solution; then, the manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide in the second leached residue remaining after lithium extraction are transformed into nickel cobalt manganese metal salts that are easily soluble in water under roasting conditions with a transformation agent, and then a nickel cobalt manganese solution is prepared through a third leaching process, which can be directly used for the preparation of ternary precursor cathode materials.

[0015] The recycling method of the spent lithium-ion battery cathode provided by the present invention, on the one hand, through a continuous two-stage leaching process, can solve the problem that the lithium element in the lithium meta-aluminate phase in the aluminothermic reduction roasting product is difficult to leach, thereby greatly improving the leaching rate of the lithium element in the spent lithium-ion battery cathode; on the other hand, through the roasting process with a transformation agent, the related substances of nickel, cobalt and manganese in the leached residue are converted into nickel cobalt manganese metal salts that are easily soluble in water, and then combined with the leaching process, the selective leaching of nickel, cobalt and manganese elements in the spent lithium-ion cathode is realized, the leaching rate of nickel, cobalt and manganese elements is increased, and the obtained nickel cobalt manganese solution can be directly used for the re-preparation of ternary precursor materials; in addition, the stepwise selective leaching process of valuable metals adopted by the present invention can shorten the recovery process of valuable metals while improving the recovery rate of valuable metals.

[0016] Preferably, after the crushing in step (1), the particle size of the positive electrode mixed powder is below 0.2 mm, such as 0.2 mm, 0.18 mm, 0.16 mm, 0.14 mm, 0.12 mm, 0.10 mm, 0.08 mm or 0.06 mm, etc.

[0017] Preferably, the positive electrode mixed powder further comprises any one or a combination of two of the crushed binder or conductive agent.

[0018] In addition to the crushed aluminum foil and lithium nickel cobalt manganese oxide positive electrode material in the positive electrode mixed powder of the present invention, other substances such as the binder and conductive agent present in the positive electrode sheet are also included. These substances will decompose and volatilize during the aluminothermic reduction roasting process, and the impact on the subsequent valuable metal recovery process can be ignored.

[0019] Preferably, the temperature of the aluminothermic reduction roasting in step (2) is 450 - 650 °C, such as 450 °C, 475 °C, 450 °C, 500 °C, 525 °C, 550 °C, 575 °C, 600 °C, 625 °C or 650 °C, etc.

[0020] Preferably, the aluminothermic reduction roasting in step (2) is carried out in a nitrogen atmosphere or an inert atmosphere.

[0021] Preferably, the time of the aluminothermic reduction roasting in step (2) is 5 - 60 min, such as 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, etc.

[0022] Preferably, the second leaching solution obtained in step (3) is returned to step (2) for use as the first leaching agent.

[0023] The second leaching solution obtained in the present invention can be returned to step (2) for use as the first leaching solution, reducing the consumption of water and the discharge of wastewater in the subsequent recovery process.

[0024] Preferably, the first leaching agent in step (2) comprises water and / or the second leaching agent obtained in step (3).

[0025] In the first recycling process of the present invention, water is used as the first leaching agent to leach lithium oxide in the first calcined product, while other calcined products remain solid, thereby achieving selective leaching of lithium elements. In the subsequent recycling process, in the lithium-containing solution of the second leaching solution obtained in step (3), it can be returned to step (2) as the first leaching agent to dissolve and leach lithium oxide in the first calcined product. At this time, the lithium elements in the second leaching solution and the lithium elements of the lithium oxide in the leached first calcined product are recycled together, so that a lithium-rich solution with a higher lithium concentration is recovered at step (2). At the same time, replacing water used in the first recycling process as the leaching agent reduces the use of water resources and saves energy. In the same recycling process, the first leaching residue obtained in step (2) is mixed and leached with the second leaching agent to obtain the second leaching solution again. The obtained second leaching solution can continue to be returned to step (2) as the first leaching agent to leach the first calcined product in the next recycling process, and so on until the last recycling process, that is, after the recycling of the waste lithium-ion battery cathode sheet is complete, the lithium-containing solution of the second leaching solution obtained in step (3) and the lithium-rich solution obtained in step (2) are recycled together to prepare a lithium salt solution for the preparation of lithium salt products. This process improves the recovery rate of metallic lithium in the cathode sheet while reducing the additional water used as the leaching agent, reducing energy consumption and wastewater discharge.

[0026] Preferably, the solid-liquid ratio of the first calcined product and the first leaching agent in step (2) is 50 - 300 g / L, such as 50 g / L, 100 g / L, 150 g / L, 200 g / L, 250 g / L or 300 g / L, etc.

[0027] In the present invention, if the solid-liquid ratio of the first calcined product and the first leaching agent is too high and the addition amount of the first leaching agent is relatively too low, then the lithium oxide in the first calcined product cannot be effectively leached, and the leaching rate of lithium elements decreases; if the solid-liquid ratio of the two is too low and the addition amount of the first leaching agent is relatively too high, then the lithium concentration in the leaching solution is low, a large amount of the first leaching agent is wasted, and the operation process of subsequent lithium salt recovery is increased.

[0028] Preferably, the temperature of the first leaching in step (2) is 20 - 60 °C, such as 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C or 60 °C, etc.

[0029] Preferably, the time of the first leaching in step (2) is 5 - 60 min, such as 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, etc.

[0030] Preferably, solid-liquid separation is carried out after the first leaching in step (2).

[0031] Preferably, the first leaching residue in step (2) includes lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0032] Preferably, the lithium-rich solution in step (2) is used to prepare lithium salt products.

[0033] In the present invention, the lithium-rich solution obtained in step (2) can adopt a concentration process for the recycling of lithium salts.

[0034] Preferably, the second leaching agent in step (3) includes a first acidic reagent.

[0035] Preferably, the acid in the first acidic reagent includes any one or at least two combinations of sulfuric acid, citric acid, formic acid, or acetic acid.

[0036] Preferably, the concentration of hydrogen ions in the second leaching agent in step (3) is 0.1 - 2 mol / L, such as 0.1 mol / L, 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, or 2.0 mol / L, etc.

[0037] In the present invention, regulating the concentration of hydrogen ions in the second leaching agent aims to avoid too high a concentration of hydrogen ions, which causes the remaining metals in the first leaching residue to be leached, resulting in a decrease in the purity of the leached lithium product; on the other hand, to avoid too low a concentration of hydrogen ions, which causes the lithium metaaluminate in the first leaching residue to not be effectively leached, resulting in a decrease in the leaching rate of lithium elements in the spent lithium-ion battery cathode sheet.

[0038] Preferably, the solid-liquid ratio of the first leaching residue and the second leaching agent in step (3) is 50 - 500 g / L, such as 50 g / L, 100 g / L, 150 g / L, 200 g / L, 250 g / L, 300 g / L, 350 g / L, 400 g / L, 450 g / L, or 500 g / L, etc.

[0039] Preferably, the second leaching in step (3) is carried out by heating under closed conditions.

[0040] Preferably, the pressure of the second leaching in step (3) is 0.3 - 4 MPa, such as 0.3 MPa, 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, or 4 MPa, etc.

[0041] Preferably, the temperature of the second leaching in step (3) is 160 - 240 °C, such as 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C or 240 °C, etc.

[0042] The second leaching provided by the present invention can be carried out in a high-pressure reactor. The reactor containing the mixed solution is placed under heating conditions to leach lithium metaaluminate in the first leaching residue, realizing the selective leaching of lithium elements in the lithium metaaluminate phase and further improving the leaching rate of lithium elements in the spent battery cathode sheet. If the temperature of the second leaching is too low, the lithium elements in the lithium metaaluminate phase cannot be effectively leached, resulting in a decrease in the leaching rate of lithium elements in the cathode sheet. If the temperature of the second leaching is too high, it will lead to high reaction energy consumption and increase the process cost.

[0043] Preferably, the time of the second leaching in step (3) is 30 - 240 min, such as 30 min, 60 min, 90 min, 120 min, 150 min, 180 min, 210 min or 240 min, etc.

[0044] Preferably, solid-liquid separation is carried out after the second leaching in step (3).

[0045] Preferably, the second leaching residue in step (3) includes manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and alumina.

[0046] Preferably, the transformation agent in step (4) includes any one or a combination of at least two of ammonium sulfate, ammonium bisulfate or ammonium chloride.

[0047] Preferably, the mass ratio of the second leaching residue to the transformation agent in step (4) is (0.5 - 1.5):1, such as 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, etc.

[0048] In the present invention, if the mass ratio of the second leaching residue to the transformation agent is too high and the addition amount of the transformation agent is relatively too low, it will result in the inability to convert all manganese oxide, cobalt oxide, nickel oxide, elemental nickel and elemental cobalt in the second leaching residue into soluble manganese salts, nickel salts and cobalt salts, thus leading to a decrease in the recovery rate of nickel, cobalt and manganese elements in the spent lithium-ion battery cathode sheet. If the mass ratio of the second leaching residue to the transformation agent is too low and the addition amount of the transformation agent is relatively too high, it will lead to an increase in raw material consumption and may also lead to an increase in the leaching rate of aluminum elements, resulting in a decrease in the purity of the recovered nickel-cobalt-manganese solution.

[0049] Preferably, the temperature of the roasting in step (4) is 500 - 800 °C, such as 500 °C, 520 °C, 540 °C, 560 °C, 580 °C, 600 °C, 620 °C, 640 °C, 660 °C, 680 °C, 700 °C, 720 °C, 740 °C, 760 °C, 780 °C or 800 °C, etc.

[0050] In the present invention, if the temperature of the transformation roasting is too low, it will cause the products containing manganese, nickel and cobalt in the second leaching residue to not be effectively converted into soluble manganese salts, nickel salts and cobalt salts, resulting in a decrease in the recovery rate of nickel, cobalt and manganese elements in the spent lithium-ion battery cathode sheet; if the temperature of the transformation roasting is too high, the manganese salts, nickel salts and cobalt salts after transformation will decompose into insoluble nickel, cobalt and manganese oxides at high temperature, resulting in a decrease in the recovery rate of nickel, cobalt and manganese elements.

[0051] Preferably, the roasting time in step (4) is 15 - 120 min, such as 15 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, etc.

[0052] Preferably, the third leaching agent in step (4) includes any one of a second acidic reagent or water.

[0053] Preferably, the second acidic reagent includes any one or at least two combinations of a sulfuric acid solution, a hydrochloric acid solution or a nitric acid solution.

[0054] Preferably, the concentration of hydrogen ions in the second acidic reagent is 0 - 0.5 mol / L, and 0 is not included, such as 0.05 mol / L, 0.10 mol / L, 0.15 mol / L, 0.20 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.40 mol / L, 0.45 mol / L or 0.50 mol / L, etc.

[0055] The present invention regulates the concentration of hydrogen ions in the second acidic reagent to avoid the leaching of alumina in the second roasting product due to too high a concentration of hydrogen ions in the second acidic reagent, resulting in a decrease in the purity of the obtained nickel-cobalt-manganese solution.

[0056] Preferably, the solid-liquid ratio of the second roasting product and the third leaching agent in step (4) is 50 - 300 g / L, such as 50 g / L, 100 g / L, 150 g / L, 200 g / L, 250 g / L or 300 g / L, etc.

[0057] Preferably, the temperature of the third leaching in step (4) is 20 - 60 °C, such as 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C or 60 °C, etc.

[0058] Preferably, the time of the third leaching in step (4) is 5 - 120 min, such as 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min or 120 min, etc.

[0059] Preferably, solid-liquid separation is carried out after the third leaching in step (4).

[0060] Preferably, the aluminum-containing compound obtained in step (4) includes aluminum oxide.

[0061] As a preferred technical solution of the present invention, the recovery method includes the following steps:

[0062] S1. Crushing the spent lithium-ion battery cathode to a particle size of the powder below 0.2 mm to obtain a cathode mixed powder; the cathode mixed powder includes at least the crushed aluminum foil and lithium nickel cobalt manganese oxide cathode material.

[0063] S2. Carrying out aluminothermic reduction roasting on the cathode mixed powder for 5 - 60 min under the protection of a nitrogen atmosphere or an inert atmosphere, the temperature of the aluminothermic reduction roasting is 450 - 650 °C, to obtain a first roasted product, the first roasted product includes lithium oxide, lithium meta-aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide.

[0064] S3. Using a first leaching agent to carry out first leaching on the first roasted product at a solid-liquid ratio of 50 - 300 g / L for 5 - 60 min, the temperature of the first leaching is 20 - 60 °C, and then through solid-liquid separation, a first leaching residue and a lithium-rich solution are obtained, the first leaching residue includes lithium meta-aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide; the lithium-rich solution is used to prepare lithium salt products.

[0065] S4. Mix the first leaching residue with a second leaching agent at a solid-liquid ratio of 50 - 500 g / L. The second leaching agent consists of a first acidic reagent with a hydrogen ion concentration of 0.1 - 2 mol / L. Place the product after the first mixing under airtight conditions for a second leaching for 30 - 240 min. The temperature of the second leaching is 160 - 240 °C, and the pressure of the second leaching is 0.3 - 4 MPa. Then, perform solid-liquid separation to obtain a second leaching solution and a second leaching residue. The second leaching solution includes a lithium-containing solution, and the second leaching solution is returned to step S3 for use as the first leaching agent; the obtained second leaching residue includes manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0066] S5. Mix the second leaching residue with a transformation agent at a mass ratio of (0.5 - 1.5):1 for a second mixing. Then, calcine the product after the second mixing at a temperature of 500 - 800 °C for 15 - 120 min to obtain a second calcined product. Perform a third leaching on the second calcined product with a third leaching agent at a solid-liquid ratio of 50 - 300 g / L for 5 - 120 min. The temperature of the third leaching is 20 - 60 °C, and the third leaching agent includes any one of a second acidic reagent or water. The hydrogen ion concentration in the second acidic reagent is 0 - 0.5 mol / L and does not include 0, to obtain an aluminum-containing compound and a recovered nickel-cobalt-manganese solution.

[0067] It should be noted that obtaining the waste lithium-ion battery cathode sheets from waste lithium-ion batteries is a conventional technical solution, and any processing method that can be obtained within a reasonable range by those skilled in the art is applicable to the present invention.

[0068] Exemplarily, the present invention provides a method for processing waste lithium-ion battery cathode sheets from waste lithium-ion batteries. The processing method includes: discharging the lithium-ion battery, and then disassembling the discharged battery to obtain the waste lithium-ion battery cathode sheets.

[0069] In addition, the cathode material containing lithium nickel cobalt manganese oxide is selected for the lithium-ion battery cathode sheet of the present invention, specifically referring to ternary battery materials with different proportions of nickel, cobalt, and manganese, such as LiNi 0.3 Co 0.3 Mn 0.3 O 2 (NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) or LiNi 0.8 Co0.1 Mn 0.1 O 2 (NCM811), etc.

[0070] Compared with the prior art, the present invention has at least the following beneficial effects:

[0071] The recycling method of the waste lithium-ion battery cathode sheet provided by the present invention, on the one hand, through a continuous two-stage leaching process, can solve the problem that the lithium element in the lithium meta-aluminate phase in the aluminothermic reduction roasting product is difficult to leach, thereby greatly improving the leaching rate of the lithium element in the waste lithium-ion battery cathode sheet; on the other hand, through the roasting process under a transformation agent, the related substances of nickel, cobalt, and manganese in the leaching residue are converted into nickel, cobalt, and manganese metal salts that are easily soluble in water, and then combined with the leaching process, the selective leaching of nickel, cobalt, and manganese elements in the waste lithium-ion cathode sheet is realized, the leaching rate of nickel, cobalt, and manganese elements is increased, and the obtained nickel, cobalt, and manganese solution can be directly used for the re-preparation of ternary precursor materials; in addition, the stepwise selective leaching process of valuable metals adopted by the present invention can shorten the recovery process of valuable metals while improving the recovery rate of valuable metals. Description of the Drawings

[0072] Figure 1 is the process flow diagram of the recycling method of the waste lithium-ion battery cathode sheet provided by the present invention. Detailed Embodiments

[0073] The technical solution of the present invention will be further described below with reference to the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0074] In a specific embodiment, the present invention uses the cathode sheet obtained after the retired waste lithium-ion battery is crushed and disassembled or the cathode sheet waste generated during the battery production process.

[0075] The contents of the main metal elements in the waste lithium-ion battery cathode sheets in the following examples and comparative examples are as follows: the content of Li element is 6.15 wt%, the content of Ni element is 18.32 wt%, the content of Co element is 18.65 wt%, the content of Mn element is 17.57 wt%, and the content of Al element is 8.81 wt%.

[0076] Example 1

[0077] This example provides a recycling method for waste lithium-ion battery cathode sheets. The specific process flow diagram is as Figure 1 shown and includes the following steps:

[0078] S1. Crush the spent lithium-ion battery cathode into powder with a particle size of less than 0.2 mm to obtain a cathode mixed powder; the cathode mixed powder includes at least the crushed aluminum foil and lithium nickel cobalt manganese oxide cathode material.

[0079] S2. Carry out aluminothermic reduction roasting on the cathode mixed powder obtained in step S1 for 5 min under the protection of a nitrogen atmosphere. The temperature of the aluminothermic reduction roasting is 650 °C to obtain a first roasted product. The first roasted product includes lithium oxide, lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0080] S3. Use deionized water as the first leaching agent for the first roasted product obtained in step S2 for 60 min at a solid-liquid ratio of 50 g / L. The temperature of the first leaching is 60 °C. Then, after solid-liquid separation, a first leaching residue and a lithium-rich solution are obtained. The first leaching residue includes lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide. Among them, in step S3, the leaching rate of only the lithium element recovered from the spent lithium-ion battery cathode is 62%, the leaching rate of nickel, cobalt, and manganese elements is less than 0.1%, and the leaching rate of aluminum element is 0.01%.

[0081] S4. Mix the first leaching residue obtained in step S3 with a sulfuric acid solution at a solid-liquid ratio of 50 g / L. The concentration of hydrogen ions in the sulfuric acid solution is 0.2 mol / L. Carry out a second leaching on the product after the first mixing in a closed high-pressure reactor at a temperature of 240 °C for 30 min. The pressure of the second leaching is 4 MPa. Then, after solid-liquid separation, a second leaching solution and a second leaching residue are obtained. The second leaching solution includes a lithium-containing solution, and the second leaching solution is returned to step S3 for use as the first leaching agent; the obtained second leaching residue includes manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0082] S5. Mix the second leaching residue obtained in step S4 with ammonium sulfate at a mass ratio of 1.5:1. Then, roast the product after the second mixing at a temperature of 500 °C for 120 min to obtain a second roasted product. Carry out a third leaching on the second roasted product with a sulfuric acid solution at a solid-liquid ratio of 50 g / L for 120 min. The temperature of the third leaching is 20 °C, and the concentration of hydrogen ions in the sulfuric acid solution is 0.2 mol / L to obtain aluminum oxide and a recovered nickel-cobalt-manganese solution.

[0083] Example 2

[0084] This example provides a method for recycling spent lithium-ion battery cathodes. The specific process schematic diagram is as Figure 1 shown, including the following steps:

[0085] S1. Crush the spent lithium-ion battery cathode into powder with a particle size of less than 0.2 mm to obtain a cathode mixed powder; the cathode mixed powder includes at least the crushed aluminum foil and lithium nickel cobalt manganese oxide cathode material.

[0086] S2. Carry out aluminothermic reduction roasting on the cathode mixed powder obtained in step S1 for 60 min under the protection of a nitrogen atmosphere. The temperature of the aluminothermic reduction roasting is 450 °C to obtain a first roasted product. The first roasted product includes lithium oxide, lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0087] S3. Use deionized water as the first leaching agent for the first roasted product obtained in step S2 for 60 min at a solid-liquid ratio of 300 g / L. The temperature of the first leaching is 60 °C. Then, after solid-liquid separation, a first leaching residue and a lithium-rich solution are obtained. The first leaching residue includes lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide. Among them, in step S3, the leaching rate of only the lithium element recovered from the spent lithium-ion battery cathode is 58.90%, the leaching rate of nickel, cobalt, and manganese elements is less than 0.1%, and the leaching rate of aluminum element is 0.70%.

[0088] S4. Mix the first leaching residue obtained in step S3 with a sulfuric acid solution at a solid-liquid ratio of 300 g / L. The concentration of hydrogen ions in the sulfuric acid solution is 2 mol / L. Carry out the second leaching on the product after the first mixing in a closed high-pressure reactor at a temperature of 160 °C for 240 min. The pressure of the second leaching is 0.3 MPa. Then, after solid-liquid separation, a second leaching solution and a second leaching residue are obtained. The second leaching solution includes a lithium-containing solution, and the second leaching solution is returned to step S3 for use as the first leaching agent; the obtained second leaching residue includes manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0089] S5. Mix the second leaching residue obtained in step S4 with ammonium sulfate at a mass ratio of 1.5:1. Then, roast the product after the second mixing at a temperature of 800 °C for 15 min to obtain a second roasted product. Carry out the third leaching on the second roasted product with a hydrochloric acid solution at a solid-liquid ratio of 300 g / L for 120 min. The temperature of the third leaching is 60 °C, and the concentration of hydrogen ions in the hydrochloric acid solution is 0.5 mol / L to obtain aluminum oxide and a recovered nickel-cobalt-manganese solution.

[0090] Example 3

[0091] This example provides a method for recycling spent lithium-ion battery cathodes. The specific process schematic diagram is as Figure 1 shown, including the following steps:

[0092] S1. Crush the waste lithium-ion battery cathode into powder with a particle size of less than 0.15 mm to obtain a cathode mixed powder; the cathode mixed powder includes at least the crushed aluminum foil and lithium nickel cobalt manganese oxide cathode material.

[0093] S2. Carry out aluminothermic reduction roasting on the cathode mixed powder obtained in step S1 for 30 min under the protection of a nitrogen atmosphere. The temperature of the aluminothermic reduction roasting is 550 °C to obtain a first roasted product. The first roasted product includes lithium oxide, lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0094] S3. Use deionized water as the first leaching agent for the first leaching of the first roasted product obtained in step S2 at a solid-liquid ratio of 200 g / L for 5 min. The temperature of the first leaching is 20 °C. Then, after solid-liquid separation, a first leaching residue and a lithium-rich solution are obtained. The first leaching residue includes lithium metaaluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0095] S4. Mix the first leaching residue obtained in step S3 with a sulfuric acid solution at a solid-liquid ratio of 500 g / L. The concentration of hydrogen ions in the sulfuric acid solution is 0.5 mol / L. Carry out the second leaching on the product after the first mixing in a closed high-pressure reactor at a temperature of 200 °C for 100 min. The pressure of the second leaching is 1.6 MPa. Then, after solid-liquid separation, a second leaching solution and a second leaching residue are obtained. The second leaching solution includes a lithium-containing solution, and the second leaching solution is returned to step S3 for use as the first leaching agent; the obtained second leaching residue includes manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt, and aluminum oxide.

[0096] S5. Mix the second leaching residue obtained in step S4 with ammonium bisulfate at a mass ratio of 0.5:1. Then, roast the product after the second mixing at a temperature of 600 °C for 80 min to obtain a second roasted product. Carry out the third leaching on the second roasted product with water at a solid-liquid ratio of 200 g / L for 80 min. The temperature of the third leaching is 40 °C to obtain aluminum oxide and a recovered nickel cobalt manganese solution.

[0097] Example 4

[0098] The difference between this example and Example 1 is only that: in the method for recycling waste lithium-ion battery cathodes provided in this example, in step S3, the first roasted product and deionized water are subjected to the first leaching at a solid-liquid ratio of 350 g / L. The rest of the content is the same as that in Example 1.

[0099] Example 5

[0100] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S3, the first calcination product and deionized water are subjected to the first leaching at a solid-liquid ratio of 30 g / L. The rest of the content is the same as that of Embodiment 1.

[0101] Embodiment 6

[0102] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S4, the concentration of hydrogen ions in the sulfuric acid solution is 3 mol / L. The rest of the content is the same as that of Embodiment 1.

[0103] Embodiment 7

[0104] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S4, the temperature of the second leaching is 150 °C. The rest of the content is the same as that of Embodiment 1.

[0105] Embodiment 8

[0106] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S5, the second leaching residue and ammonium sulfate are subjected to the second mixing at a mass ratio of 2:1. The rest of the content is the same as that of Embodiment 1.

[0107] Embodiment 9

[0108] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S5, the second leaching residue and ammonium sulfate are subjected to the second mixing at a mass ratio of 0.2:1. The rest of the content is the same as that of Embodiment 1.

[0109] Embodiment 10

[0110] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S5, the temperature of the calcination is 450 °C. The rest of the content is the same as that of Embodiment 1.

[0111] Embodiment 11

[0112] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the positive electrode sheet of waste lithium-ion batteries provided in this embodiment, in step S5, the temperature of the calcination is 850 °C. The rest of the content is the same as that of Embodiment 1.

[0113] Embodiment 12

[0114] The difference between this embodiment and Embodiment 1 is only that: in the method for recycling the spent lithium-ion battery cathode sheet provided in this embodiment, the concentration of hydrogen ions in the sulfuric acid solution in step S5 is 1 mol / L. The rest of the content is the same as that in Embodiment 1.

[0115] Comparative Example 1

[0116] The difference between this comparative example and Embodiment 1 is only that: in the method for recycling the spent lithium-ion battery cathode sheet provided in this comparative example, all the processes in step S4 are omitted, and the first leaching residue obtained in step S3 is directly mixed with ammonium sulfate in step S5 for the second time. The rest of the content is the same as that in Embodiment 1.

[0117] Comparative Example 2

[0118] The difference between this comparative example and Embodiment 1 is only that: in the method for recycling the spent lithium-ion battery cathode sheet provided in this comparative example, the transformation roasting of step S5 with ammonium sulfate is omitted, and the second leaching residue is directly leached with sulfuric acid solution for the third time. The rest of the content is the same as that in Embodiment 1.

[0119] During the processes of the methods for recycling the spent lithium-ion battery cathode sheets provided in Embodiments 1-12 and Comparative Examples 1-2, the contents of lithium, nickel, cobalt, manganese, and aluminum elements in the positive electrode mixed powder are detected by ICP (inductively coupled plasma), and the contents of lithium, nickel, cobalt, manganese, and aluminum elements in the lithium-rich solution, lithium-containing solution, first leaching residue, second leaching residue, nickel-cobalt-manganese solution, and alumina obtained during the recycling process are detected by ICP. Calculate the leaching rates of lithium, nickel, cobalt, manganese, and aluminum elements in the total lithium salt solution composed of the finally recycled lithium-rich solution and lithium-containing solution, as well as the leaching rates of nickel, cobalt, manganese, and aluminum elements in the finally recycled nickel-cobalt-manganese solution. The calculation formula is:

[0120] L i =C i V / (mw i )×100%, where L i represents the leaching rate of metal i (Li, Ni, Co, Mn, Al), %; C i represents the concentration of metal i (Li, Ni, Co, Mn, Al) in the corresponding recycled solution, g / L; V represents the volume of the corresponding solution, ml; m represents the mass of the positive electrode mixed powder, g; w i represents the mass fraction of metal i (Li, Ni, Co, Mn, Al) in the positive electrode mixed powder, %.

[0121] The test results are shown in Table 1.

[0122] Table 1

[0123]

[0124] It can be seen from the test results that:

[0125] (1) It can be seen from Examples 1 to 3 that in the recovery method provided by the present invention, the continuous two-stage leaching adopted solves the problem that lithium meta-aluminate in the aluminothermic reduction roasting product is difficult to leach, improves the leaching rate of lithium, and the transformation roasting combined with the leaching process adopted realizes the selective leaching of nickel, cobalt and manganese elements, and a nickel-cobalt-manganese solution with high purity and high recovery rate is obtained. The cascade selective leaching process adopted by the present invention also effectively shortens the process flow of valuable metal recovery.

[0126] (2) It can be seen from the comparison between Example 1 and Examples 4-5 that if the solid-liquid ratio of the first roasting product to water is too high and the addition amount of the first leaching agent water is relatively too low in the present invention, the lithium oxide in the first roasting product cannot be effectively leached, and the leaching rate of lithium element decreases; if the solid-liquid ratio of the two is too low and the addition amount of water is relatively too high, the lithium concentration in the leaching solution is low and a large amount of water is wasted.

[0127] (3) It can be seen from the comparison between Example 1 and Example 6 that if the hydrogen ion concentration of the acidic reagent mixed with the first leaching residue is too high in the present invention, the metal elements other than lithium in the first leaching residue will be leached, resulting in a decrease in the purity of the recovered lithium salt solution.

[0128] (4) It can be seen from the comparison between Example 1 and Example 7 that if the temperature of the second leaching is too low in the present invention, the lithium element in the lithium meta-aluminate phase cannot be effectively leached, thereby reducing the leaching rate of lithium element in the positive electrode sheet.

[0129] (5) It can be seen from the comparison between Example 1 and Examples 8-9 that if the mass ratio of the second leaching residue to the transforming agent is too high and the addition amount of the transforming agent is relatively too low in the present invention, all of the manganese oxide, cobalt oxide, nickel oxide, elemental nickel and elemental cobalt in the second leaching residue cannot be converted into soluble manganese salts, nickel salts and cobalt salts, resulting in a decrease in the leaching rate of nickel, cobalt and manganese elements in the waste lithium ion battery positive electrode sheet; if the mass ratio of the second leaching residue to the transforming agent is too low and the addition amount of the transforming agent is relatively too high, excessive aluminum will be leached, affecting the purity of the nickel-cobalt-manganese solution.

[0130] (6) It can be seen from the comparison between Example 1 and Examples 10 - 11 that if the temperature of the conversion roasting in the present invention is too low, it will cause the cobalt-containing products of manganese and nickel in the second leaching residue to not be effectively converted into soluble manganese salts, nickel salts and cobalt salts, resulting in a decrease in the leaching rate of nickel, cobalt and manganese elements in the waste lithium-ion battery cathode sheet; if the temperature of the conversion roasting is too high, the manganese salts, nickel salts and cobalt salts will decompose into oxides, and the leaching rate of nickel, cobalt and manganese elements in the leaching solution will decrease.

[0131] (7) It can be seen from the comparison between Example 1 and Example 12 that the concentration of hydrogen ions in the sulfuric acid solution in step S5 of the present invention is too high, resulting in the leaching of alumina in the second roasting product, so that the obtained nickel-cobalt-manganese solution contains leached aluminum ions, and further reducing the purity of the nickel-cobalt-manganese solution.

[0132] (8) It can be seen from the comparison between Example 1 and Comparative Example 1 that if the second leaching process of the waste lithium-ion battery cathode sheet in step S4 of the present invention is omitted, the leaching rate of lithium element will decrease significantly.

[0133] (9) It can be seen from the comparison between Example 1 and Comparative Example 2 that if the conversion roasting with ammonium sulfate in step S5 of the present invention is omitted, the leaching rate of nickel, cobalt and manganese will decrease significantly.

[0134] In summary, for the recovery method of the waste lithium-ion battery cathode sheet provided by the present invention, on the one hand, through the continuous two-stage leaching process, the problem that the lithium element in the lithium metaaluminate phase in the aluminothermic reduction roasting product is difficult to leach can be solved, thus greatly improving the leaching rate of the lithium element in the waste lithium-ion battery cathode sheet; on the other hand, through the roasting process with a conversion agent, the related substances of nickel, cobalt and manganese in the leaching residue are converted into nickel-cobalt-manganese metal salts that are easily soluble in water, and then combined with the leaching process to realize the selective leaching of nickel, cobalt and manganese elements in the waste lithium-ion cathode sheet, improving the leaching rate of nickel, cobalt and manganese elements. The obtained nickel-cobalt-manganese solution can be directly used for the re-preparation of ternary precursor materials; in addition, the stepwise selective leaching process of valuable metals adopted by the present invention can improve the recovery rate of valuable metals while shortening the recovery process of valuable metals and reducing waste emissions.

[0135] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for recycling waste lithium-ion battery positive plates, characterized in that: The recovery method comprises the following steps: (1) crushing the positive electrode sheets of waste lithium-ion batteries to obtain a positive electrode mixed powder; the positive electrode mixed powder at least includes the crushed aluminum foil and nickel cobalt manganese oxide lithium positive electrode material; (2) subjecting the positive electrode mixed powder to aluminothermic reduction roasting to obtain a first roasting product, wherein the first roasting product comprises lithium oxide, lithium aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide; subjecting the first roasting product to a first leaching agent for a first leaching to obtain a first leaching residue and recovering a lithium-rich solution; (3) mixing the first leaching residue with a second leaching agent, and performing a second leaching to obtain a second leaching solution and a second leaching residue, wherein the second leaching solution comprises a lithium-containing solution; (4) mixing the second leaching residue with a transformation agent, roasting to obtain a second roasting product, and subjecting the second roasting product to a third leaching with a third leaching agent to obtain an aluminum-containing compound and recovering a nickel-cobalt-manganese solution.

2. The recycling method according to claim 1, characterized in that: After the crushing in step (1), the particle size of the positive electrode mixed powder is less than 0.2 mm; Preferably, the temperature of the aluminothermic reduction roasting in step (2) is 450-650°C; Preferably, the aluminothermic reduction roasting in step (2) is carried out under a nitrogen atmosphere or an inert atmosphere; Preferably, the time of the aluminothermic reduction roasting in step (2) is 5-60 min.

3. The recovery method according to claim 1 or 2, characterized in that: The second leaching solution obtained in step (3) is returned to step (2) and used as the first leaching agent; Preferably, the first leaching agent in step (2) comprises water and / or the second leaching solution obtained in step (3); Preferably, in step (2), the solid-liquid ratio of the first calcined product and the first leaching agent is 50-300 g / L; Preferably, the temperature of the first leaching in step (2) is 20-60°C; Preferably, the first leaching time in step (2) is 5-60 min.

4. The recycling method according to any one of claims 1 to 3, characterized in that: Step (2) after the first leaching, solid-liquid separation is also performed; Preferably, the first leaching residue in step (2) comprises lithium aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide.

5. The recycling method according to any one of claims 1 to 4, characterized in that: Step (3) the second leaching agent includes a first acidic reagent; Preferably, the acid in the first acidic reagent includes any one or a combination of at least two of sulfuric acid, citric acid, formic acid or acetic acid; Preferably, in step (3), the concentration of hydrogen ions in the second leaching agent is 0.1-2 mol / L; Preferably, in step (3), the solid-to-liquid ratio of the first leaching residue to the second leaching agent is 50-500 g / L.

6. The recycling method according to any one of claims 1 to 5, characterized in that: Step (3) the second leaching is carried out by heating under closed conditions; Preferably, the pressure of the second leaching in step (3) is 0.3-4 MPa; Preferably, the temperature of the second leaching in step (3) is 160-240°C; Preferably, the second leaching time in step (3) is 30-240 min.

7. The recycling method according to any one of claims 1 to 6, characterized in that: Step (3) after the second leaching, solid-liquid separation is also performed; Preferably, the second leaching residue in step (3) comprises manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide.

8. The recycling method according to any one of claims 1 to 7, characterized in that: The transformation agent in step (4) includes any one of ammonium sulfate, ammonium bisulfate or ammonium chloride, or a combination of at least two thereof; Preferably, in step (4), the mass ratio of the second leaching residue to the transformation agent is (0.5-1.5):1; Preferably, the calcination temperature in step (4) is 500-800°C; Preferably, the calcination time in step (4) is 15-120 min.

9. The recycling method according to any one of claims 1 to 8, characterized in that: The third leaching agent in step (4) includes any one of the second acidic reagent or water; Preferably, the second acidic reagent comprises any one or a combination of at least two of a sulfuric acid solution, a hydrochloric acid solution or a nitric acid solution; Preferably, the concentration of hydrogen ions in the second acidic reagent is 0-0.5 mol / L, excluding 0; Preferably, in step (4), the solid-to-liquid ratio of the second roasted product to the third leaching agent is 50-300 g / L; Preferably, the temperature of the third leaching in step (4) is 20-60°C; Preferably, the third leaching time in step (4) is 5-120 min; Preferably, solid-liquid separation is also performed after the third leaching in step (4); Preferably, the aluminum-containing compound obtained in step (4) comprises aluminum oxide.

10. The recycling method according to any one of claims 1 to 9, characterized in that: The recovery method comprises the following steps: S1. Crushing the waste lithium-ion battery positive electrode sheets to a powder particle size of less than 0.2 mm to obtain a positive electrode mixed powder; the positive electrode mixed powder comprises at least crushed aluminum foil and nickel cobalt manganese oxide positive electrode material; S2. The positive electrode mixed powder is subjected to aluminothermic reduction calcination for 5-60 min under the protection of a nitrogen atmosphere or an inert atmosphere, wherein the aluminothermic reduction calcination temperature is 450-650 ° C to obtain a first calcined product, wherein the first calcined product includes lithium oxide, lithium aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide; S3. The first calcined product is subjected to a first leaching for 5-60 min using a first leaching agent at a solid-liquid ratio of 50-300 g / L, the first leaching temperature is 20-60° C., and then solid-liquid separation is performed to obtain a first leaching residue and a lithium-rich solution, wherein the first leaching residue comprises lithium aluminate, manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide; the lithium-rich solution is used to prepare a lithium salt product; S4. The first leaching residue is first mixed with a second leaching agent at a solid-liquid ratio of 50-500 g / L, wherein the second leaching agent is composed of a first acidic reagent having a hydrogen ion concentration of 0.1-2 mol / L, and the product after the first mixing is placed in a closed condition for a second leaching for 30-240 min, wherein the temperature of the second leaching is 160-240° C., and the pressure of the second leaching is 0.3-4 MPa, followed by solid-liquid separation to obtain a second leaching solution and a second leaching residue, wherein the second leaching solution includes a lithium-containing solution, and the second leaching solution is returned to step S3 and used as the first leaching agent; the obtained second leaching residue includes manganese oxide, cobalt oxide, nickel oxide, elemental nickel, elemental cobalt and aluminum oxide; S5. The second leaching residue and the transformation agent are mixed for the second time at a mass ratio of (0.5-1.5): 1, and then the second mixed product is roasted at a temperature of 500-800° C. for 15-120 min to obtain a second roasted product, and the second roasted product is subjected to a third leaching agent for 5-120 min at a solid-liquid ratio of 50-300 g / L, the temperature of the third leaching is 20-60° C., the third leaching agent includes any one of a second acidic reagent or water, the concentration of hydrogen ions in the second acidic reagent is 0-0.5 mol / L, and does not include 0, to obtain an aluminum-containing compound and recover a nickel-cobalt-manganese solution.

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