Short-process valuable metal recovery method for retired ternary lithium battery

Abstract

The invention provides a short-process valuable metal recovery method for a decommissioned ternary lithium battery, and relates to the technical field of recovery treatment of decommissioned lithium batteries, and the short-process valuable metal recovery method comprises the following steps: S1, disassembling and crushing the decommissioned ternary lithium battery, and directly pyrolyzing the decommissioned ternary lithium battery; s2, performing physical sorting on the pyrolyzed battery material to realize positive and negative electrode powder separation; s3, extracting lithium by adopting CO2 micro-nano bubble reinforced water leaching to obtain battery-grade lithium carbonate; s4, selective stepped leaching of manganese, nickel and cobalt is achieved; step S5, obtaining a nickel-cobalt-manganese mixed precipitate; and step S6, carrying out acid leaching on the nickel-cobalt-manganese mixed precipitate, removing impurities, and adjusting components to prepare the ternary precursor. The method has the advantages of short flow, low cost, low reagent dosage, low energy consumption, high valuable metal recovery rate and the like, and an effective solution can be provided for green recovery of the retired ternary lithium battery.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and processing of retired lithium batteries, and in particular to a method for recycling valuable metals from retired ternary lithium batteries in a short process. Background Art

[0002] With the rapid development of my country's new energy vehicle industry, more and more retired ternary lithium-ion power batteries will be produced in the future. The large amount of toxic and harmful substances contained in retired nickel-cobalt-manganese ternary lithium-ion batteries will cause serious harm to the environment and human health. In addition, retired lithium-ion batteries contain rich valuable metals, which can be used as important secondary resources. In order to realize the recycling of valuable metal resources and reduce the adverse effects of solid waste on the environment, the recycling of retired lithium-ion batteries has received widespread attention.

[0003] In recent years, the combined pyrometallurgical and hydrometallurgical processes for recovering valuable metals in lithium-ion batteries have attracted more and more attention. For example, patent CN106129511A mixes the positive electrode material of lithium-ion batteries with solid carbon reducing agents such as lignite for reduction roasting, and introduces carbon dioxide into the roasted product for water leaching to obtain a lithium bicarbonate solution. After evaporation and crystallization, the lithium carbonate product is obtained. The leached residue is acid-leached or ammonia-leached, and then extracted and purified to recover nickel, cobalt and manganese. This method uses solid carbon sources such as lignite as reducing agents, and the amount of reducing agent is large. In addition, impurities in the reducing agent will also affect the quality of nickel, cobalt, manganese products and graphite.

[0004] In terms of the recovery of nickel, cobalt and manganese, some scholars have proposed the use of synchronous extraction to extract nickel, cobalt and manganese in the solution into the organic phase, and then obtain a nickel, cobalt and manganese sulfate solution after back extraction with sulfuric acid. However, this method requires the deep removal of impurities in the solution before extraction, which is obviously very difficult. Patent CN202011113765 uses saponified P507 to perform multi-stage synchronous extraction on the solution after impurity removal, back-extracts with acid after phase separation, and then adds nickel, cobalt and manganese salts to the back-extracted solution to adjust the ratio of nickel, cobalt and manganese to prepare a ternary material precursor. However, extraction with P507 requires multi-stage extraction, washing, back-extraction and backwashing, which makes the recovery process complicated and cumbersome. In summary, there is an urgent need to develop a short-process method for efficiently and economically treating waste ternary lithium-ion batteries to prepare lithium carbonate and precursors. Summary of the invention

[0005] The present invention aims to solve the problems existing in the prior art and provides a method for economically and efficiently recovering waste ternary lithium batteries to prepare battery-grade lithium carbonate and ternary precursors. To achieve this purpose, the specific technical scheme adopted by the present invention is as follows:

[0006] A method for recovering valuable metals from retired ternary lithium batteries in a short process, comprising:

[0007] Step S1, after the retired ternary lithium battery is disassembled and crushed, it is directly pyrolyzed, and the waste gas produced by the pyrolysis is discharged after rapid cooling and alkali spraying; the present invention can utilize the reducing organic matter in the waste battery through direct pyrolysis in an oxygen-deficient pyrolysis atmosphere, and directly reduce the positive electrode material into lithium carbonate, MnO and metallic nickel and cobalt, thereby combining the traditional low-temperature pyrolysis + black powder reduction roasting into one step.

[0008] Step S2, the battery material after pyrolysis is physically sorted to separate the black powder (i.e., the positive and negative electrode mixed powder) from the copper foil and the aluminum foil;

[0009] Step S3, reacting the black powder with the aqueous solution, and simultaneously introducing CO2 micro-nano bubbles produced by a micro-nano bubble generator to achieve selective enhanced leaching of lithium, and obtaining a lithium-containing leachate and lithium-extracting slag after filtration, and heating and evaporating the lithium-containing leachate after defluorination to obtain battery-grade lithium carbonate; the present invention can increase the reaction speed and improve the utilization rate of CO2 gas by adding CO2 micro-nano bubbles.

[0010] Step S4, the lithium slag is leached with a mixed solution of ammonia water-ammonium salt under air isolation or inert gas protection to achieve selective leaching of manganese and obtain a manganese leachate; the manganese material is then leached with oxidized ammonia to extract nickel and cobalt to obtain a nickel and cobalt leachate, and the nickel and cobalt ammonia leaching system is the same as that of manganese leaching; if the nickel-cobalt-manganese slag is directly leached with an ammonia solution, oxygen must be introduced, so that manganese will form manganese dioxide and cannot be leached. The present invention first uses anaerobic conditions to leach manganese, and nickel and cobalt exist in a single form and will not leach under anaerobic conditions, so they need to be subsequently leached under oxygenated conditions, and in a subsequent step, they are combined with the previously leached manganese solution to form a nickel-cobalt-manganese mixed ammonia solution.

[0011] Step S5, mixing the manganese leaching solution with the nickel and cobalt leaching solutions, adding an appropriate amount of a reducing agent for reaction, and then heating and evaporating to obtain a nickel-cobalt-manganese mixed precipitate, and adding the evaporated ammonia gas to the evaporated mother liquor after condensation and collection, and recycling it as a leaching agent; when recycled as a leaching agent, it can be used for leaching manganese or for leaching nickel and cobalt;

[0012] Step S6, acid leaching the nickel-cobalt-manganese mixed precipitate, using sulfide precipitation to remove a small amount of copper impurities in the acid leaching solution, adding manganese sulfate, nickel sulfate, and cobalt sulfate to adjust the composition, and directly preparing a ternary precursor.

[0013] Furthermore, in step S1, the pyrolysis temperature is 400-600°C, and the reaction time is 1-3 hours. If the reaction temperature is too low, the reduction of the positive electrode material will be insufficient, and the subsequent recovery rate of lithium, nickel, cobalt, and manganese will be reduced; if the reaction temperature is too high, the aluminum foil will become soft and powdery, affecting the separation effect of aluminum and positive electrode powder in the screening and separation process.

[0014] Further, in step S3, the immersion reaction time is 20 to 60 minutes, the liquid-solid ratio is 2:1 to 10:1 mL / g, the CO2 injection amount is 0.1 to 2 L / min·L solution, and the micro-nano bubble size is 50nm to 20μm. After pyrolysis, lithium exists in the form of lithium carbonate, manganese is manganous oxide, nickel and cobalt are metals, and CO2 immersion can be used to convert lithium carbonate into lithium bicarbonate that is easy to immerse in water, while nickel, cobalt, manganese and other metal impurities will not be leached. The impurities in the immersion liquid are only a small amount of fluorine, so lithium carbonate products can be prepared after fluorine removal; the main components of lithium slag are manganous oxide, metallic nickel and cobalt. The present invention can significantly reduce the immersion reaction time and CO2 injection amount by selecting micro-nano bubbles of such size.

[0015] Furthermore, in the manganese leaching process described in step S4, the ammonia concentration in the leaching agent is 2-6 mol / L, the ammonium salt concentration is 1-5 mol / L, the leaching time is 20-90 min, the liquid-solid ratio is 2:1-10:1 mL / g, the leaching temperature is 10-50 ° C, and the oxygen content of the system is less than 1%; the ammonia concentration in the leaching agent of the oxidative ammonia leaching process of nickel and cobalt is 2-8 mol / L, the ammonium salt concentration is 1-5 mol / L, the leaching time is 1-6 hours, the liquid-solid ratio is 2:1-20:1 mL / g, the leaching temperature is 10-60 ° C, and the oxidant used is one of air, oxygen, hydrogen peroxide, and ozone.

[0016] Furthermore, the reducing agent used in step S5 is one of carbon monoxide, sodium sulfite and hydrazine hydrate, and the molar amount of the reducing agent added is 0.6 to 5 times the molar amount of cobalt in the mixed solution.

[0017] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0018] (1) Directly pyrolyze the retired lithium batteries after simple crushing, and use the separator and reducing organic matter in the battery to reduce and transform the positive electrode material without adding an external reducing agent. The pyrolysis process volatilizes the electrolyte, binder, etc. into the gas phase, thereby combining the traditional low-temperature pyrolysis process with the reduction roasting of black powder into one step, reducing the energy consumption of the process;

[0019] (2) CO2 micro-nano bubbles are used to achieve efficient and selective leaching of lithium during water leaching, with fast reaction speed, high lithium recovery rate and high CO2 utilization rate during lithium extraction;

[0020] (3) Ammonia selective extraction of manganese and nickel and cobalt are carried out under an anaerobic system. The ammonia leaching system has high selectivity and low impurity leaching rate. The purification process is greatly simplified and the extraction process is deleted, achieving low-cost and short-process recovery of valuable metals;

[0021] (4) The ammonia solution of nickel, cobalt and manganese is reduced and evaporated to obtain a mixed precipitate of nickel, cobalt and manganese, which can then be directly prepared into a ternary precursor after acid leaching and copper removal. The evaporated ammonia gas is condensed and collected and then added to the evaporated mother liquor for recycling as a leaching agent. No salt-containing wastewater is produced, which greatly reduces the cost of wastewater treatment. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is described below.

[0023] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0024] In the embodiments of the present invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are consistent.

[0025] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, they are described in detail below in conjunction with specific embodiments.

[0026] Example 1

[0027] The retired ternary battery is disassembled after discharge, mechanically crushed into flakes, pyrolyzed at 400℃ for 1 hour, and the waste gas produced by pyrolysis is quenched, absorbed with alkaline solution and then discharged. The pyrolyzed material is screened, and 20g of the screened powder is leached with 100mL of water at 50℃ for 60 minutes, and CO2 micro-nano bubbles produced by a micro-nano bubble generator are introduced at the same time, with a gas flow rate of 20mL / min and a micro-nano bubble diameter of 50nm~1μm. After the reaction is completed, it is filtered to obtain a lithium-containing water leaching solution and water leaching residue. After detection and calculation, it is found that the leaching rate of lithium reaches 94.2%, and the leaching rates of nickel, cobalt and manganese are 0.65%, 0.08% and 0.12% respectively. Calcium salt is added to the lithium-containing water leaching solution, and fluorine-containing precipitate and lithium-containing filtrate are filtered. The lithium-containing filtrate is evaporated and crystallized to obtain a lithium carbonate product. The water leaching residue is added to a mixed solution of 6mol / L ammonia water and 1mol / L ammonium carbonate, and selectively and preferentially extracts manganese under air-tight conditions, with a reaction time of 90min, a reaction temperature of 10℃, and a liquid-solid ratio of 2:1mL / g. After the reaction, the manganese-containing leaching solution and manganese-extracting residue are filtered to obtain a manganese-containing leaching solution, with a manganese leaching rate of 95.2%, and almost no nickel and cobalt are leached. The manganese-extracting residue is introduced into air at a flow rate of 500mL / min for oxidative ammonia leaching, with an ammonia leaching temperature of 60℃ and a time of 6 hours. At a liquid-solid ratio of 20:1mL / g, it is added to an ammonia leaching agent containing 5mol / L ammonium carbonate and 2mol / L ammonia water, and filtered to obtain a solution containing cobalt and nickel. The leaching rates of nickel and cobalt are both above 98%. The cobalt- and nickel-containing solution obtained by filtration is mixed with the manganese-containing leaching solution and placed in a closed autoclave, and sodium sulfite is added in an amount of 0.6 times the molar amount of cobalt in the mixed solution. After the reaction is completed, it is filtered to directly obtain a mixed precipitate of cobalt carbonate, nickel carbonate, and manganese carbonate. The evaporated ammonia gas is condensed and collected and added to the evaporation mother liquor for recycling as a leaching agent. The nickel-cobalt-manganese precipitate is acid-leached with sulfuric acid, and a mixed solution containing nickel-cobalt-manganese sulfate is obtained after filtration. A certain amount of sulfide is added thereto to remove copper impurities. The molar ratio of nickel, cobalt, and manganese in the nickel-cobalt-manganese salt solution is adjusted to 1:1:1 by adding pure reagents of nickel sulfate, cobalt sulfate, and manganese sulfate. Ammonia solution is added to prepare the NCM111 positive electrode material precursor in the reactor.

[0028] Comparative Example 1

[0029] The retired ternary battery is disassembled after discharge, mechanically crushed into flake materials, pyrolyzed at 400°C for 1 hour, and the waste gas produced by pyrolysis is quenched, absorbed with alkaline solution and then discharged. The pyrolyzed material is screened, and 20g of the screened powder is leached with 100mL of water at 50°C for 60 minutes, and CO2 gas is introduced at the same time, with a gas flow rate of 20mL / min and a bubble diameter greater than 20μm. After the reaction is completed, it is filtered to obtain a lithium-containing water leaching solution and water leaching residue. After detection and calculation, the leaching rate of lithium reaches 78.5%, and the leaching rates of nickel, cobalt and manganese are 1.35%, 0.38% and 0.79% respectively. It can be seen that compared with micro-nano bubbles, the bubble size is larger when conventional CO2 gas is introduced for water leaching, which makes it difficult to achieve a high leaching rate of lithium under the same leaching time and gas flow rate, resulting in the loss of lithium resources.

[0030] Example 2

[0031] The retired ternary battery is immersed in a salt solution and then discharged and disassembled, mechanically crushed into flake materials, pyrolyzed at 600°C for 3 hours, and the waste gas produced by pyrolysis is quenched and absorbed with alkali solution. After absorption, the gas is emptied. The pyrolyzed material is screened, 50g of the screened powder is taken and stirred with 200mL of water at 20°C for leaching for 20 minutes, and CO2 micro-nano bubbles produced by a micro-nano bubble generator are introduced at the same time. The gas flow rate is 20mL / min and the bubble size is controlled at 1 μm~20μm. After the reaction is completed, the lithium-containing water leaching solution and water leaching residue are obtained by solid-liquid separation. After detection and calculation, the lithium leaching rate reaches 95.3%, and nickel, cobalt and manganese are not leached. Calcium salt is added to the lithium-containing water leaching solution, and fluorine-containing precipitate and lithium-containing filtrate are filtered. The lithium-containing filtrate is evaporated and crystallized to obtain lithium carbonate products. The water leaching residue was added to a mixed solution of 2mol / L ammonia water and 3mol / L ammonium sulfate, and selectively extracted manganese in an air-tight condition. The reaction time was 20min, the reaction temperature was 50℃, and the liquid-solid ratio was 10:1 mL / g. After the reaction, the manganese-containing leaching solution and manganese-extracting slag were filtered to obtain the manganese leaching rate of 96.2%, and nickel and cobalt were not leached. The manganese-extracting slag was added to an ammonia leaching agent containing 1mol / L ammonium sulfate and 8mol / L ammonia water at a liquid-solid ratio of 2:1 mL / g, and air was introduced at a flow rate of 1L / min to perform oxidative ammonia leaching. The ammonia leaching temperature was 10℃, the time was 1 hour, and the solution containing cobalt and nickel was filtered. The leaching rates of each valuable element were analyzed to be 98.37% for cobalt and 98.85% for nickel. The cobalt- and nickel-containing solution obtained by filtration is mixed with the manganese-containing leaching solution and placed in a closed autoclave, and carbon monoxide 5 times the molar amount of cobalt in the mixed solution is added. After the reaction is completed, the solid-liquid separation is performed to directly obtain an oxidized mixed precipitate of nickel, cobalt and manganese. The evaporated ammonia gas is condensed and collected and added to the evaporated mother liquor for recycling as a leaching agent. A sufficient amount of sulfuric acid is used for acid leaching, and a mixed solution containing nickel, cobalt and manganese sulfate is obtained after filtration. Sulfide is added thereto to remove copper impurities, and the molar ratio of nickel, cobalt and manganese in the nickel, cobalt and manganese salt solution is adjusted to 8:1:1 by adding pure reagents of nickel sulfate, cobalt sulfate and manganese sulfate, and an ammonia solution is added to prepare the NCM811 positive electrode material precursor in the reactor.

[0032] Example 3

[0033] The retired ternary battery is disassembled after discharge, mechanically crushed into flakes, pyrolyzed at 500℃ for 2 hours, and the waste gas produced by pyrolysis is quenched, absorbed with alkaline solution and then discharged. The pyrolyzed material is screened, 10g of the screened powder is taken and leached with 100mL of water at 30℃ for 45 minutes, and CO2 micro-nano bubbles produced by the micro-nano bubble generator are introduced at the same time, the gas flow rate is 20mL / min, and the bubble size is controlled at 1μm~10μm. After the reaction is completed, the lithium-containing water leaching liquid and water leaching residue are obtained by solid-liquid separation. After detection and calculation, the lithium leaching rate reaches 96.5%, and nickel, cobalt and manganese are not leached. Calcium salt is added to the lithium-containing water leaching liquid, and fluorine-containing precipitate and lithium-containing filtrate are filtered. The lithium-containing filtrate is evaporated and crystallized to obtain lithium carbonate product. The water leaching residue was added to a mixed solution of 4mol / L ammonia water and 5mol / L ammonium bicarbonate, and selectively extracted manganese in an air-tight condition. The reaction time was 40min, the reaction temperature was 30℃, and the liquid-solid ratio was 5:1 mL / g. After the leaching, the manganese-containing leaching solution and manganese-extracting slag were filtered out. The manganese leaching rate reached 97.2%, and the nickel and cobalt leaching rates were only 1.4% and 1.8% at this time. The manganese-extracting slag was added to an ammonia leaching agent containing 4mol / L ammonium bicarbonate and 5mol / L ammonia water at a liquid-solid ratio of 10:1 mL / g, and air was introduced at a flow rate of 200mL / min for oxidative ammonia leaching. The ammonia leaching temperature was 40℃, the time was 4 hours, and the solution containing cobalt and nickel was filtered out. The leaching rates of each valuable element were analyzed to be 98.64% for cobalt and 98.05% for nickel. The cobalt- and nickel-containing solution obtained by filtration is mixed with the manganese-containing leaching solution and placed in a closed autoclave, and hydrazine hydrate 5 times the molar amount of cobalt in the mixed solution is added. After stirring, the solid and liquid are separated to directly obtain a mixed precipitate of cobalt carbonate, nickel carbonate, and manganese carbonate. The evaporated ammonia gas is condensed and collected and added to the evaporation mother liquor for recycling as a leaching agent. The nickel-cobalt-manganese precipitate is acid-leached with sulfuric acid, and a mixed solution containing nickel-cobalt-manganese sulfate is obtained after filtration. A certain amount of sulfide is added to remove copper impurities, and the molar ratio of nickel-cobalt-manganese in the nickel-cobalt-manganese salt solution is adjusted to 5:2:3 by adding pure reagents of nickel sulfate, cobalt sulfate, and manganese sulfate. Ammonia solution is added to prepare the NCM523 positive electrode material precursor in the reactor.

[0034] Example 4

[0035] The retired ternary battery is disassembled after discharge, mechanically crushed into flake materials, pyrolyzed at 400℃ for 4 hours, and the waste gas produced by pyrolysis is quenched, absorbed with alkaline solution and then discharged. The pyrolyzed material is screened, 50g of the screened powder is taken and 100mL of water is stirred and leached at 20℃ for 20 minutes, and CO2 micro-nano bubbles produced by the micro-nano bubble generator are introduced at the same time, the gas flow rate is 20mL / min, and the bubble size is controlled at 20μm. After the reaction is completed, the lithium-containing water leaching liquid and water leaching residue are obtained by solid-liquid separation. After detection and calculation, the lithium leaching rate reaches 94.2%, and nickel, cobalt and manganese are not leached. Calcium salt is added to the lithium-containing water leaching liquid, and fluoride salt precipitate and lithium-containing filtrate are filtered. The lithium-containing filtrate is evaporated and crystallized to obtain lithium carbonate product. The water leaching residue is added to a mixed solution of 2mol / L ammonia water and 5mol / L ammonium bisulfate, and selectively and preferentially extracts manganese under air-tight conditions, with a reaction time of 20min, a reaction temperature of 50℃, and a liquid-solid ratio of 8:1 mL / g. After the reaction, the manganese-containing leaching solution and manganese-extracting slag are filtered to obtain a manganese leaching solution with a manganese leaching rate of 97.7%, and nickel and cobalt are not leached at this time; the manganese-extracting slag is added to an ammonia leaching agent containing 4mol / L ammonium bisulfate and 6mol / L ammonia water at a liquid-solid ratio of 2:1 mL / g, and air is introduced at a flow rate of 600mL / min for oxidative ammonia leaching, with an ammonia leaching temperature of 10℃ and a time of 1 hour, and a solution containing cobalt and nickel is obtained by filtration. The leaching rates of each valuable element are analyzed to be 98.54% for cobalt and 98.75% for nickel. The cobalt- and nickel-containing solution obtained by filtration is mixed with the manganese-containing leaching solution and placed in a closed autoclave, and sodium sulfite is added in an amount of 5 times the molar amount of cobalt in the mixed solution. After stirring, the solid and liquid are separated to directly obtain an oxidized mixed precipitate of nickel, cobalt and manganese. The evaporated ammonia gas is condensed and collected and added to the evaporation mother liquor for recycling as a leaching agent. The nickel, cobalt and manganese precipitate is acid-leached with sulfuric acid, and a mixed solution containing nickel, cobalt and manganese sulfate is obtained after filtration. A certain amount of cobalt sulfide is added to remove copper impurities, and the molar ratio of nickel, cobalt and manganese in the nickel, cobalt and manganese salt solution is adjusted to 6:2:2 by adding pure reagents of nickel sulfate, cobalt sulfate and manganese sulfate. Ammonia solution is added to prepare the NCM622 positive electrode material precursor in the reactor.

[0036] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for recovering valuable metals from retired ternary lithium batteries in a short process, characterized in that: include: Step S1, the retired ternary lithium battery is directly pyrolyzed after being disassembled and crushed, and the waste gas produced by the pyrolysis is discharged after rapid cooling and alkali spraying; Step S2, the battery material after pyrolysis is physically sorted to separate the black powder from the copper foil and the aluminum foil; Step S3, reacting the black powder with the aqueous solution, and introducing CO2 micro-nano bubbles at the same time to achieve selective enhanced leaching of lithium, and obtaining a lithium-containing leachate and lithium-extracting slag after filtration, and heating and evaporating the lithium-containing leachate after defluorination to obtain battery-grade lithium carbonate; Step S4, leaching the lithium slag with a mixed solution of ammonia water and ammonium salt under air isolation or inert gas protection to achieve selective leaching of manganese, thereby obtaining a manganese leaching solution and a manganese extraction material; the manganese extraction material is then leached with ammonia oxide to extract nickel and cobalt, and the nickel and cobalt ammonia leaching system is the same as that of manganese leaching; Step S5, mixing the manganese leaching solution with the nickel and cobalt leaching solutions, adding an appropriate amount of reducing agent for reaction, and heating and evaporating to obtain a nickel-cobalt-manganese mixed precipitate, and condensing and collecting the evaporated ammonia gas and adding it to the evaporated mother liquor for recycling as a leaching agent; Step S6, acid leaching the nickel-cobalt-manganese mixed precipitate, using sulfide precipitation to remove a small amount of copper impurities in the acid leaching solution, adding manganese sulfate, nickel sulfate, and cobalt sulfate to adjust the composition, and directly preparing a ternary precursor.

2. The method according to claim 1, characterized in that In step S1, the pyrolysis temperature is 400-600° C., and the reaction time is 1-3 hours.

3. The method according to claim 1, characterized in that In step S3, the water immersion reaction time is 20 to 60 minutes, the liquid-solid ratio is 2:1 to 10:1 mL / g, the CO2 introduction amount is 0.1 to 2 L / min·L solution, and the micro-nano bubble size is 50 nm to 20 μm.

4. The method according to claim 1, characterized in that In the manganese leaching process described in step S4, the ammonia concentration in the leaching agent is 2-6 mol / L, the ammonium salt concentration is 1-5 mol / L, the leaching time is 20-90 min, the liquid-solid ratio is 2:1-10:1 mL / g, the leaching temperature is 10-50° C., and the oxygen content of the system is less than 1%.

5. The method according to claim 1, characterized in that In step S4, the concentration of ammonia water in the leaching agent of the oxidative ammonia leaching process of nickel and cobalt is 2-8 mol / L, the concentration of ammonium salt is 1-5 mol / L, the leaching time is 1-6 hours, the liquid-solid ratio is 2:1-20:1 mL / g, the leaching temperature is 10-60°C, and the oxidant used is one of air, oxygen, hydrogen peroxide, and ozone.

6. The method according to claim 1, characterized in that The reducing agent used in step S5 is one of carbon monoxide, sodium sulfite and hydrazine hydrate, and the molar amount of the reducing agent added is 0.6 to 5 times the molar amount of cobalt in the mixed solution.