Method for preferentially extracting lithium and recycling valuable metal from retired ternary lithium battery and application

Abstract

The invention relates to the technical field of retired ternary power battery recovery, and particularly discloses a method for preferentially extracting lithium and recovering valuable metals from a retired ternary lithium battery and application of the method. According to the method, the traditional process is broken through the preferential lithium extraction, and efficient recovery of lithium, Ni, Co and Mn is realized by utilizing'fast-medium-slow 'multi-stage cooperation of a composite reducing agent and accurate adaptation of roasting and leaching parameters, so that the method has the advantages of low cost, high efficiency, low energy consumption and the like, and is suitable for large-scale industrial production. The method is low in energy consumption and environment-friendly, and is applied to resource recycling of the retired ternary lithium battery, and the precursor can be used for reproducing a positive electrode material or used for a catalytic material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of retired ternary power battery recycling, in particular to a method for preferentially extracting lithium and valuable metals from retired ternary lithium batteries and application thereof. BACKGROUND

[0002] Many car models suitable for consumer needs have been launched by enterprises, and the charging and battery replacement infrastructure is constantly improving, so new energy vehicles have made great progress. As the "heart" of electric vehicles, lithium-ion batteries usually experience capacity degradation during use. Once the capacity is lower than 80% of the initial capacity, it cannot meet the normal power demand of electric vehicles. Today, lithium-ion batteries used in early electric vehicles are beginning to face a wave of retirement. According to forecasts, there will be more than 6 million tons of retired lithium-ion batteries worldwide by 2030. These waste lithium batteries contain lithium hexafluorophosphate, organic carbonates, copper, cobalt, nickel, manganese, and other chemicals.

[0003] In summary, in the future for a long period of time, with the certainty of continued high growth in the new energy vehicle market, the amount of waste power lithium batteries is also increasing. Through centralized "harmless" treatment and "resourceful" recycling by professional recycling companies, green recycling can be achieved, turning harm into benefit and achieving both goals. The recycling and utilization of waste power lithium batteries from new energy vehicles is a way to follow the path of sustainable development, and has broad market prospects.

[0004] The recycling of valuable metals from retired lithium batteries and their resource utilization will play a very important role for a long time in the future. Many companies re-manufacture ternary lithium batteries after recycling valuable metals, but the cycle is long. The present application provides a differentiated method from the previous extraction of valuable metals first and lithium last by preferentially extracting Li from retired ternary lithium batteries in a simple and energy-saving way, and then recycling valuable metals. On the one hand, Li2CO3 can be prepared by simple water immersion + carbonate precipitation, and on the other hand, it provides a way for high-value utilization of retired ternary lithium batteries.

[0005] Patent CN112374511A discloses a method for recycling and preparing lithium carbonate and ternary precursors from waste ternary lithium batteries, which uses graphite and a binder as a reducing agent for preferential reduction to extract lithium, and recovers lithium carbonate by carbonation water immersion. After extracting Ni, Co, and Mn with sulfuric acid, the corresponding sulfate precursors are prepared. Compared with this patent, the present application can realize preferential water immersion extraction of Li (which will not affect the extraction of valuable metals) by simple pre-reduction + water immersion, which has obvious technical advantages compared with the traditional method of extracting valuable metals first and then extracting lithium. SUMMARY

[0006] In view of the technical defects in the background art, the present application proposes a method for preferentially extracting lithium and recovering valuable metals from retired ternary lithium batteries and its application, which solves the above technical problems and meets the actual needs. The specific technical scheme is as follows: A method for preferentially extracting lithium and recovering valuable metals from retired ternary lithium batteries, comprising the following steps: (1) Reduction roasting: uniformly mix the positive electrode material powder obtained by treating the retired ternary lithium battery with a reducing precursor, and perform roasting under an air atmosphere to convert lithium in the positive electrode material into a water-soluble lithium compound, and simultaneously convert the valuable metals Ni, Co and Mn into a form that can be leached out by acid; (2) Water leaching of lithium: mix the roasting product obtained in step (1) with water, perform leaching treatment to realize selective extraction of lithium, and then perform solid-liquid separation to obtain a leaching solution rich in lithium and a residue after lithium extraction; (3) Residue activation: performing directional activation treatment on the residue after lithium extraction obtained in step (2); (4) Acid leaching of valuable metals: using a leaching agent to leach the residue after activation in step (3), and performing post-treatment to remove impurities, to realize recovery of Ni, Co and Mn valuable metals.

[0007] As a further technical scheme of the present application, in step (1), the reducing precursor is a mixture of starch, glucose, activated carbon and graphite; when a mixture is used, the mixture is compounded from starch or glucose, activated carbon and graphite in a mass ratio of (0.2-0.6):(0.4-1.2):(0.1-0.4), and the mass ratio of the reducing precursor to the positive electrode material powder is 0.5-3:1.

[0008] As a further technical scheme of the present application, in step (1), the roasting procedure is: first, raise the temperature to 250-350℃ at a rate of 5-10℃ / min, then raise the temperature to 500-800℃ at a rate of 3-8℃ / min, and keep the temperature for 20-60min; the air flow rate is 10-100mL / min.

[0009] As a further technical scheme of the present application, in step (2), a surfactant is further added in the water leaching process, the surfactant is a non-ionic surfactant or an anionic surfactant, and the addition amount is 0.01%-1% of the mass of water; the liquid-solid ratio of the water leaching is 5-30mL / g, the temperature is 15-40℃, and the time is 10-60min.

[0010] As a further technical scheme of the present application, in step (3), the directional activation treatment is washing with a dilute acid solution with a concentration of 0.05-0.1mol / L at 15-60℃ for 5-10min.

[0011] As a further technical solution of the present application, in step (4), the leaching agent is an oxidative organic acid system, which comprises a first organic acid as a main oxidant and a second organic acid as a complexing agent; the first organic acid is peracetic acid, and the second organic acid is a mixed acid of malic acid or tartaric acid and glyoxylic acid, wherein the malic acid or tartaric acid is mixed with the glyoxylic acid at a molar ratio of 1:(1-3); the total amount of the first organic acid and the second organic acid in the leaching solution is at a ratio of 1:1 to 5:1; and the total concentration of the first organic acid and the second organic acid in the leaching solution is 0.5-3.0 mol / L.

[0012] As a further technical solution of the present application, in step (4), the acid leaching of valuable metals is specifically carried out as follows: the activated residue is first mixed with water, and then the second organic acid is slowly added under ultrasonic and stirring conditions; ultrasonic is applied and stirring is continued for 30 min; then the first organic acid is slowly added; after the reaction is completed, sodium hydroxide solution is used to adjust the pH to 4-5; then solid-liquid separation is performed to obtain an oxalate precipitate rich in Ni, Co and Mn; the acid leaching process is carried out under ultrasonic assistance and mechanical stirring; the ultrasonic frequency is 20-40 kHz, and the mechanical stirring speed is 200-500 rpm; the liquid-solid ratio of the acid leaching is 5-50 mL / g; the temperature is 50-70°C; and the total time is 60-120 min. The oxalate precipitate is dissolved in an inorganic acid solution, which is one of hydrochloric acid, sulfuric acid or nitric acid, at a concentration of 0.5-2.0 mol / L, a liquid-solid ratio of 5-20 mL / g and a temperature of 25-60°C for 10-30 min to obtain a pure mixed salt solution rich in Ni, Co and Mn; the solution is filtered to retain the filtrate; 0.5-2.0 mol / L of sodium hydroxide solution is slowly added to the filtrate under stirring to adjust the pH to 6-6.5; and the solution is filtered again to obtain a valuable metal leaching solution.

[0013] As a further technical solution of the present application, the lithium-rich leaching solution obtained in step (2) is concentrated and then added with sodium carbonate to precipitate and prepare battery-grade lithium carbonate; and the valuable metal leaching solution obtained in step (4) is prepared into a Ni-Co-Mn ternary precursor by a coprecipitation method.

[0014] The application of a method for preferentially extracting lithium and recovering valuable metals from retired ternary lithium batteries in the resource recycling of retired ternary lithium batteries.

[0015] As a further technical solution of the present application, the recovered Ni-Co-Mn ternary precursor is used to prepare a lithium ion battery cathode material or a catalytic material.

[0016] The present application has the following beneficial effects: This invention employs a reducing precursor composite formulation and a multi-stage calcination process, enabling controlled reduction of lithium in an air atmosphere. This selectively converts lithium into water-soluble compounds, allowing for efficient lithium extraction via water leaching. This simplifies the process and reduces energy consumption. Meanwhile, valuable metals such as nickel, cobalt, and manganese are converted into acid-soluble forms and, after activation, are leached using an organic acid system, resulting in high recovery rates. This invention avoids the lithium loss problem caused by the prior recovery of valuable metals in traditional processes, improving overall recovery efficiency. Finally, the recovered product has high purity; lithium can be used to produce battery-grade lithium carbonate, and valuable metals can be used to prepare ternary precursors for battery materials or high-value catalytic materials. This achieves high-value utilization of all components, while also being environmentally friendly and offering significant energy-saving and economic benefits. Detailed Implementation

[0017] The embodiments of the present invention will be described below with reference to relevant examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.

[0018] A method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries includes the following steps: (1) Reduction roasting: The cathode material powder obtained by processing retired ternary lithium batteries is uniformly mixed with a reducing precursor and roasted in an air atmosphere to convert lithium in the cathode material into water-soluble lithium compounds, while converting valuable metals Ni, Co and Mn into forms that can be leached by acid. (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water and leached to achieve selective extraction of lithium. Then, solid-liquid separation is performed to obtain lithium-rich leachate and lithium-extracted residue. (3) Residue activation: The lithium extraction residue obtained in step (2) is subjected to targeted activation treatment; (4) Acid leaching of valuable metals: The residue after activation in step (3) is leached with a leaching agent and then post-treated to remove impurities, thereby recovering valuable metals such as Ni, Co and Mn.

[0019] This invention achieves efficient recovery of lithium and valuable metals from retired ternary lithium batteries through a stepwise extraction method, improving overall resource utilization efficiency. It utilizes a reducing precursor and cathode material to be calcined under a specific atmosphere. Through the synergistic effect of multiple reducing agents, lithium is converted into easily water-soluble compounds, while valuable metals are converted into acid-soluble forms. This avoids excessive reduction or sintering of metals at high temperatures and also optimizes the feasibility of subsequent separation steps.

[0020] During the reduction roasting stage, a mixed reducing agent, with starch or glucose as the main reducing agent, rapidly decomposes at low temperatures to produce a highly active carbon source, promoting the reduction reaction and creating pores. Activated carbon provides a stable reducing atmosphere and microporous support, ensuring a smooth and continuous reaction. Graphite acts as a framework at high temperatures, preventing the material from melting and sticking together, thus maintaining the material's loose structure. This synergistic effect allows the roasting process to be carried out controllably in an air atmosphere, ensuring both reduction efficiency and avoiding energy waste.

[0021] The subsequent water leaching lithium extraction step achieved selective lithium extraction. Low-temperature water leaching effectively dissolved water-soluble lithium compounds, while the addition of surfactants further enhanced the leaching effect, ensuring efficient lithium entry into the liquid phase. The residue after lithium extraction was activated with dilute acid to remove surface impurities, creating favorable conditions for the leaching of valuable metals. Finally, an oxidizing organic acid system was used to leach nickel, cobalt, and manganese, where the organic acid acted as both an oxidant and a complexing agent, achieving a gentle yet efficient recovery of valuable metals with extremely high leaching rates.

[0022] Overall, this invention achieves the separation and purification of lithium and valuable metals through seamless integration of steps and reagent synergy. The recovered lithium can be used to prepare battery-grade lithium carbonate, while the valuable metals can be converted into ternary precursors for reuse in the preparation of cathode materials or catalysts. This not only reduces energy consumption and costs in the recycling process but also increases the added value of the products, providing an efficient and environmentally friendly solution for the resource utilization of retired lithium batteries.

[0023] As a further technical solution of the present invention, in step (1), the reducing precursor is a mixture of starch, glucose, activated carbon and graphite; when a mixture is used, the mixture is prepared by compounding starch or glucose, activated carbon and graphite in a mass ratio of (0.2-0.6):(0.4-1.2):(0.1-0.4), and the mass ratio of the reducing precursor to the positive electrode material powder is 0.5~3:1.

[0024] The composite reducing agent is based on a multi-stage reduction system of "fast-medium-slow," and the reduction roasting process is regulated through the synergistic effect of different carbon sources. Specifically, starch or glucose acts as the main reducing agent and pore-forming agent. In the low-temperature stage (300-500℃), it rapidly decomposes and releases highly active carbon sources. The pores formed by its vigorous gas production (such as CO2 and H2O) provide material transport channels for subsequent reactions. At the same time, the strong reducing atmosphere in the early stage promotes the preferential conversion of lithium into water-soluble compounds (such as Li2CO3), avoiding excessive reduction of valuable metals. Starch, due to its higher decomposition temperature (about 350℃) and more continuous gas production, is usually preferred over glucose, although the latter decomposes faster (about 250℃). The main reducing agent accounts for 30%-50% of the total carbon content, which can ensure the reduction intensity in the low-temperature stage and avoid excessive carbon source residue at high temperatures.

[0025] Activated carbon, as a basic reducing agent, maintains a stable reducing atmosphere through a CO / CO2 cycle reaction at moderate temperatures (500-700℃). Its microcrystalline structure provides a continuous carbon source, ensuring complete lithium conversion and the formation of acid-soluble forms of valuable metals (such as NiO and CoO). Simultaneously, the microporous structure (1-2 nm) of activated carbon complements the macropores (10-100 nm) formed by the main reducing agent, increasing the overall porosity of the material and providing mass transfer advantages for subsequent water and acid leaching. Activated carbon accounts for 40%-60% of the total carbon content, balancing reduction efficiency and cost, and avoiding the sintering of excessive activated carbon at high temperatures.

[0026] Graphite serves as both a high-temperature stabilizer and an anti-sintering agent, playing a dual role at temperatures above 700℃. Its layered structure provides a stable carbon source, preventing the reaction from interrupting after the depletion of the low-temperature reducing agent. Simultaneously, the lamellar crystals form a physical isolation layer between particles, effectively inhibiting the melting and bonding of materials at high temperatures. For example, when the temperature exceeds 750℃, the interlayer slippage of graphite can buffer interparticle stress and maintain the integrity of the pore structure. Graphite accounts for 10%-20% of the total carbon content; excessive amounts may lead to carbon residue affecting the efficiency of subsequent acid leaching.

[0027] The total reducing agent to cathode material mass ratio is controlled between 0.5 and 3:1, and needs to be dynamically adjusted according to the calcination temperature. For example, a lower carbon content (0.5:1) is sufficient when calcining at 500℃, while at a high temperature of 800℃, the carbon content needs to be appropriately increased (2:1) to compensate for carbon oxidation loss.

[0028] In practical applications, the following are some examples of possible solutions: The balanced solution (NCM: starch + activated carbon + graphite = 1:1.2) is suitable for medium calcination temperatures of 600-700℃, taking into account pore formation, reduction and anti-sintering performance; the solution that focuses on pore formation (NCM: glucose + activated carbon + graphite = 1:1.0) enhances low-temperature gas production and is suitable for high lithium content cathode materials, but the heating rate needs to be strictly controlled (≤5℃ / min) to avoid local overheating.

[0029] As a further technical solution of the present invention, in step (1), the roasting procedure is as follows: first, the temperature is raised to 250-350℃ at a rate of 5-10℃ / min, then raised to 500-800℃ at a rate of 3-8℃ / min, and kept warm for 20-60min; the air flow rate is 10-100mL / min.

[0030] The calcination process is adapted to the multi-stage reaction characteristics of the composite reducing agent, which are fast-medium-slow. By controlling the heating rate and air flow in stages, the reduction reaction process, the pore structure of the material and the morphology of the target product can be controlled, thus avoiding incomplete lithium conversion or excessive reduction of valuable metals due to reaction imbalance.

[0031] The first stage involves heating from room temperature to 250-350℃ at a moderate heating rate of 5-10℃ / min, primarily targeting the initial reaction characteristics of starch or glucose. This temperature range is the pre-carbonization and dehydration stage for starch (which begins to decompose at approximately 350℃) and glucose (which begins to decompose at approximately 250℃). Too rapid a heating rate would cause these organic compounds to decompose violently and produce gas in a short time, potentially breaking down material aggregates and causing "spraying," thus disrupting the homogeneity of the reaction system. A rate of 5-10℃ / min ensures uniform heating of the materials while allowing sufficient time for the slow removal of adsorbed water and water of crystallization, as well as the initial coking of organic matter, ultimately generating highly reactive amorphous carbon, laying the foundation for subsequent selective lithium conversion. During this stage, the airflow is typically controlled at a low level (e.g., 20-30 mL / min). The presence of a small amount of oxygen helps remove volatiles (such as small-molecule organic compounds) from the materials without triggering violent combustion of the reducing agent, ensuring a gentle and controllable pre-carbonization process.

[0032] The second stage involves further heating from 250-350℃ to 500-800℃, reducing the heating rate to 3-8℃ / min. This roasting process significantly impacts lithium conversion efficiency and the pore structure of the material. Within this temperature range, activated carbon begins to function. Slow heating is necessary to allow the released reducing gases (such as CO) to fully react with the lithium in the cathode material, while simultaneously ensuring continuous gas production from the amorphous carbon generated during pre-carbonization, gradually building a loose pore structure. If the temperature rises too quickly, the rapid escape of gas can lead to pore collapse. The airflow rate needs to be adjusted to 30-50 mL / min at this stage (this needs to be fine-tuned based on the target temperature) to maintain a "controlled combustion" balance. Insufficient flow rate leads to severe agglomeration of the roasted products, affecting subsequent water immersion efficiency. Mechanical ball milling can improve water immersion efficiency, but this increases costs. Excessive flow rate accelerates the oxidation and consumption of activated carbon and amorphous carbon, wasting reducing agent and affecting mass transfer efficiency due to insufficient pore formation. When the temperature reaches 500-800℃, it needs to be held for 20-60 minutes. The time should be adjusted flexibly according to the target temperature. If the temperature is close to 500℃, the holding time can be extended to 50-60 minutes to ensure that lithium can be fully converted into water-soluble Li2CO3. If the temperature is close to 800℃, the holding time can be shortened to 20-30 minutes. At this time, the high temperature can quickly promote the conversion of lithium. Excessive holding time may cause graphite to be over-oxidized and lose its anti-sintering effect.

[0033] In addition, the total air flow rate of 10-100 mL / min needs to be dynamically matched with the temperature stage. Before the temperature rises to 500℃, the flow rate is generally controlled at 10-40 mL / min to avoid premature consumption of the reducing agent. When the temperature exceeds 600℃, if it is necessary to enhance the anti-sintering effect of graphite, the flow rate can be finely adjusted to 40-60 mL / min. A small amount of oxygen can inhibit the melting and bonding between material particles without affecting the stability of the layered structure of graphite. After the entire roasting process is completed, furnace cooling is usually adopted to avoid the thermal stress generated by rapid cooling from damaging the already formed porous structure. If the material structure becomes dense due to improper cooling, the lithium dissolution path will be blocked during subsequent water immersion, directly affecting the lithium extraction efficiency. This is a crucial but often overlooked aspect in the roasting process design.

[0034] As a further technical solution of the present invention, in step (2), a surfactant is added to the water leaching lithium extraction process. The surfactant is a nonionic surfactant or anionic surfactant, and the amount added is 0.01%-1% of the water mass. The liquid-solid ratio of the water leaching lithium extraction is 5-30 mL / g, the temperature is 15-40℃, and the time is 10-60 min.

[0035] Nonionic surfactants (such as Tween and Span series) or anionic surfactants (such as sodium dodecylbenzene sulfonate) do not react with metal ions such as lithium, nickel, cobalt, and manganese in the calcined products, thus avoiding the introduction of new impurities. Their function is to reduce the surface tension between water and the calcined product particles, helping the aqueous solution to penetrate more fully into the porous structure formed by calcination, especially reaching deep into the micropores to contact water-soluble lithium compounds (such as Li₂CO₃), thereby improving lithium dissolution efficiency. The addition amount is set at 0.01%-1% of the water mass because below 0.01%, the surface activity is insufficient to effectively improve the penetration effect; above 1%, not only will it increase costs, but the excess surfactant may also adhere to the residue surface during subsequent solid-liquid separation, affecting the subsequent acid leaching process, and even causing foaming problems during the subsequent purification of the lithium leachate.

[0036] The liquid-to-solid ratio is controlled between 5-30 mL / g, and needs to be flexibly adjusted based on the lithium content in the calcined product. If the lithium content is high, a lower liquid-to-solid ratio (e.g., 5-15 mL / g) can be used to reduce the energy consumption for subsequent lithium leachate concentration and lower production costs. If the lithium content is low, the liquid-to-solid ratio needs to be appropriately increased (e.g., 15-30 mL / g) to ensure that the aqueous solution can fully coat the particles and avoid local lithium concentrations leading to saturation, which would affect the total lithium dissolution rate. The temperature is set at 15-40℃ because the solubility of the water-soluble lithium compounds generated during calcination is sufficient within this temperature range. Low-temperature operation can avoid increased water evaporation due to high temperatures, and also prevent some easily soluble impurities (such as a small amount of soluble salts) from dissolving along with the lithium, ensuring the purity of the lithium leachate. Furthermore, no additional heating equipment is required, reducing energy consumption. The time should be controlled within 10-60 minutes. 10 minutes is sufficient for the dissolution of easily accessible lithium compounds in porous structures. For lithium compounds partially encapsulated inside the particles, the time needs to be extended to 60 minutes to ensure complete dissolution. However, after 60 minutes, the lithium dissolution rate will not improve significantly, which will lead to a decrease in production efficiency and an increase in time costs.

[0037] As a further technical solution of the present invention, in step (3), the directional activation treatment is to wash with a dilute acid solution with a concentration of 0.05-0.1 mol / L at 15-60℃ for 5-10 min.

[0038] Treatment with dilute acid can thoroughly remove lithium residues and impurity layers from the surface of the residue, exposing the acid-soluble forms of valuable metals. It also minimizes premature leaching of valuable metals, creating an efficient reaction interface for subsequent organic acid leaching and improving the recovery rates of Ni, Co, and Mn. The dilute acid concentration should be controlled at 0.05-0.1 mol / L to dissolve residual lithium compounds (such as incompletely leached Li₂CO₃) and small amounts of soluble impurities on the surface of the residue after lithium extraction, while avoiding excessively high concentrations that could lead to the acid-soluble forms of valuable metals (Ni, Co, Mn). Premature dissolution leads to losses. The above concentration range can specifically remove surface obstacles while maintaining the stable existence of valuable metals. The combination of temperature 15-60℃ and time 5-10min further optimizes the activation effect. Low temperature (15-30℃) combined with a longer time (20-30min) is suitable for treating residues with strong impurity adhesion and gently removing impurities. Medium and high temperature (30-60℃) can be shortened to 5-20min, which improves cleaning efficiency by accelerating molecular motion, while avoiding excessive corrosion of the main structure by acid at high temperature.

[0039] As a further technical solution of the present invention, in step (4), the leaching agent is an oxidizing organic acid system, which includes a first organic acid as the main oxidant and a second organic acid as a complexing agent; the first organic acid is peracetic acid, the second organic acid is malic acid or a mixture of tartaric acid and glyoxylic acid, in the second organic acid, malic acid / tartaric acid and glyoxylic acid are mixed in a molar ratio of 1:(1-3), the total molar ratio of the first organic acid and the second organic acid in the leaching liquid phase is 1:1 to 5:1, and the concentration of the total amount of organic acid in the first organic acid and the second organic acid in the leaching liquid phase is 0.5-3.0 mol / L.

[0040] The oxidizing organic acid system achieves gentle and efficient leaching of valuable metals through the synergistic effect of the primary oxidant and complexing agent, while avoiding the introduction of impurities. Peracetic acid is chosen as the primary organic acid because it possesses both weak acidity and oxidizing properties, enabling it to oxidize low-valence elemental metals (Ni / Co) in the calcination residue to Co. 2+ Ni 2+ This is a crucial prerequisite for metal leaching. It should be noted that after roasting, high-valence metals will become low-valence elements, while manganese exists in the form of oxides. Malic acid and other organic acids in the second organic acid form stable complexes with metal ions through their polycarboxyl structure, while providing an acidic environment to dissolve the metal, ensuring the stability of the leachate, and preventing the metal from being over-oxidized and consuming too much oxidant. Meanwhile, glyoxylic acid in the second organic acid is oxidized to oxalic acid, which combines with nickel, cobalt, and manganese ions in the leachate phase to form the corresponding oxalate precipitate.

[0041] Within the molar ratio of the first organic acid to the second organic acid, which is between 1:1 and 5:1, the oxidizing power is insufficient when the ratio is too low (close to 1:1), resulting in incomplete oxidation of elemental Co and limited leaching rate. Conversely, when the ratio is too high (close to 5:1), the complexing agent is relatively insufficient, failing to completely complex the dissolved metal ions, leading to excessive oxidation of the metal. A total concentration range of 0.5-3.0 mol / L avoids both the insufficient leaching kinetics and slow reaction caused by excessively low concentrations, and the increased solution viscosity, decreased mass transfer efficiency, and increased subsequent separation costs caused by excessively high concentrations. Ultimately, this achieves efficient, mild, and economical leaching of valuable metals.

[0042] As a further technical solution of the present invention, in step (4), the specific process of acid leaching of valuable metals is as follows: the activated residue is first mixed with water, and the second organic acid is slowly added under ultrasonic and stirring conditions. The reaction is ultrasonic and continuously stirred for 30 minutes, and then the first organic acid is slowly added. After the reaction is completed, sodium hydroxide solution is used to adjust the pH to 4-5, and then solid-liquid separation is performed to obtain oxalate precipitates rich in Ni, Co and Mn. The acid leaching process is carried out under ultrasonic assistance and mechanical stirring. The ultrasonic frequency is 20-40kHz, the mechanical stirring speed is 200-500rpm, the liquid-solid ratio of the acid leaching is 5-50mL / g, the temperature is 50-70℃, and the total time is 60-120min. The oxalate precipitate is dissolved in an inorganic acid solution, wherein the acid solution is one of hydrochloric acid, sulfuric acid, or nitric acid, with a concentration of 0.5-2.0 mol / L, a solution-to-solid ratio of 5-20 mL / g, a temperature of 25-60℃, and a time of 10-30 min, to obtain a pure mixed salt solution rich in Ni, Co, and Mn. The solution is filtered, and the filtrate is retained. A 0.5-2.0 mol / L sodium hydroxide solution is slowly added to the filtrate while stirring to adjust the pH to 6-6.5. The solution is then filtered a second time to obtain a valuable metal leachate.

[0043] The liquid-to-solid ratio for acid leaching is set at 5-50 mL / g to suit the content of valuable metals in the residue and the reaction requirements of the organic acid system. When the Ni, Co, and Mn content in the residue is high, a lower liquid-to-solid ratio (5-20 mL / g) is used. This ensures sufficient contact between the leaching agent and the metal while reducing the amount of subsequent concentrated leachate. The temperature is controlled at 50-70℃. If the temperature is too low (below 50℃), the oxidizing activity and complexing ability of the organic acid are weak, resulting in a slow metal leaching rate and difficulty in completing the reaction within a reasonable time. If the temperature is too high (above 70℃), the organic acid may volatilize or decompose, destroying the complexing system and reducing the leaching effect while increasing energy consumption.

[0044] In the above acid leaching process, the second organic acid first reacts with the activated residue, mainly with manganese oxides, to generate corresponding manganese ions. These ions are then complexed by the complexing acid in the second organic acid. The reaction of elemental cobalt and nickel is relatively slow. After the addition of the first organic acid, they react with elemental Ni and Co, oxidizing them into their corresponding ions. These ions are then also complexed by the complexing acid in the second organic acid. Simultaneously, glyoxylic acid in the second organic acid is oxidized to oxalic acid, which combines with nickel, cobalt, and manganese ions in the leaching solution to generate corresponding oxalate precipitates. Then, sodium hydroxide solution is used to adjust the pH to 4-5, converting the oxalic acid in the leaching solution that did not participate in the precipitation reaction into oxalate ions, further improving the precipitation efficiency and ensuring more complete precipitation of metal ions. The oxalate precipitate is dissolved and filtered with an inorganic acid solution, and the filtrate is retained. Then, sodium hydroxide solution is used to adjust the pH to 6-6.5 to remove impurity ions such as Fe, Al, and Cu, thereby obtaining a valuable metal leaching solution.

[0045] As a further technical solution of the present invention, the lithium-rich leachate obtained in step (2) is concentrated and then sodium carbonate is added to precipitate and prepare battery-grade lithium carbonate; the valuable metal leachate obtained in step (4) is precipitated again by co-precipitation to prepare Ni, Co and Mn ternary precursors.

[0046] In step (2), the lithium-rich leachate has low impurity content due to the selective extraction of lithium achieved by the previous water leaching. Concentration treatment can effectively increase the lithium-ion concentration, creating suitable conditions for the subsequent precipitation reaction. This avoids insufficient lithium carbonate precipitation due to excessively low lithium concentration and also reduces the amount of sodium carbonate used, thus lowering costs. When adding sodium carbonate, the pH and temperature of the reaction system need to be controlled (usually 60-80℃) so that lithium ions combine with carbonate ions to form lithium carbonate precipitate. Subsequently, filtration and washing remove residual sodium, calcium, and other impurities, meeting the requirements for re-preparing lithium battery cathode materials.

[0047] In the valuable metal leaching solution of step (4), Ni, Co, and Mn ions exist stably in a low valence state. When using the co-precipitation method, sodium hydroxide needs to be added to the leaching solution (to adjust the pH) and the reaction temperature (50-70℃) and stirring rate should be controlled to ensure that the three metal ions precipitate and form Ni-Co-Mn precursors, which can be used to synthesize new ternary cathode materials or converted into catalytic materials after treatment, so as to realize the high-value recycling of retired battery resources.

[0048] This invention also provides an application of a method for preferential lithium extraction and valuable metal extraction from retired ternary lithium batteries in the resource recycling of retired ternary lithium batteries. The recovered Ni, Co, and Mn ternary precursors are used to re-prepare lithium-ion battery cathode materials or to prepare catalytic materials.

[0049] In the field of resource recycling of retired ternary lithium batteries, the application of this method of prioritizing lithium extraction and valuable metal extraction can accurately meet the recycling needs of different types of retired ternary batteries. By prioritizing lithium extraction, lithium loss is reduced, while Ni, Co, and Mn are efficiently recovered. This meets the urgent need of the current new energy industry for the recycling of scarce metal resources. It can alleviate the mining pressure of mineral resources such as lithium and cobalt, and reduce the environmental risks caused by the random disposal of retired batteries. It provides an economical and environmentally friendly technical path for large-scale recycling.

[0050] The recovered Ni, Co, and Mn ternary precursors can be used to re-prepare lithium-ion battery cathode materials. After mixing and sintering with a lithium source (such as lithium carbonate), they can be reduced to ternary cathodes with satisfactory performance, integrating into the closed-loop battery production process and significantly reducing raw material costs. When used to prepare catalytic materials, the metal active sites of Ni, Co, and Mn can be utilized in catalytic oxidation and hydrogenation reactions, offering greater resource recycling advantages compared to traditional catalytic materials and further enhancing the high-value utilization of retired batteries.

[0051] The present invention will be further described below through examples and comparative examples.

[0052] Example 1 (1) Reduction calcination: The NCM523 (LiNi) obtained by processing retired ternary lithium batteries is... 0.5 Co 0.2 Mn 0.3 The positive electrode material powder and the reducing precursor were uniformly mixed. The reducing precursor was a mixture of starch, activated carbon and graphite in a mass ratio of 0.3:0.6:0.3, and the total mass ratio of the reducing precursor to the positive electrode material powder was 1.2:1. After mixing, the mixture was calcined in an air atmosphere. The calcination program was to raise the temperature to 300°C at a rate of 5°C / min, then raise it to 600°C at a rate of 5°C / min, and hold it at 600°C for 40 min. The air flow rate was controlled at 30 mL / min.

[0053] (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water for leaching treatment, wherein sodium dodecylbenzenesulfonate (anionic surfactant) is added as a surfactant, the amount added is 0.05% of the water mass, the liquid-to-solid ratio is 10 mL / g, the leaching temperature is 25℃, and the time is 30 min. (3) Activation of residue: The lithium extraction residue obtained in step (2) is washed at 30°C for 8 min with a dilute sulfuric acid solution of 0.08 mol / L.

[0054] (4) Acid leaching of valuable metals: The activated residue is mixed with water, and the second organic acid is slowly added under ultrasonic and stirring conditions. The reaction is ultrasonic and continuously stirred for 30 min. Then the first organic acid is slowly added. After the reaction is completed, the pH is adjusted to 4.5 using sodium hydroxide solution. The solid and liquid are separated to obtain oxalate precipitate. The second organic acid is a mixture of malic acid and glyoxylic acid (molar ratio 1:2). The total molar ratio of the first organic acid peracetic acid to the second organic acid is 3:1. The total concentration of organic acid is 1.5 mol / L. The acid leaching conditions are: liquid-solid ratio of 20 mL / g, temperature of 60℃, time of 60 min; ultrasonic frequency of 30 kHz, mechanical stirring speed of 300 rpm.

[0055] The oxalate precipitate was dissolved in 1.0 mol / L hydrochloric acid (liquid-to-solid ratio 10 mL / g, temperature 40℃, time 20 min), and filtered to obtain a mixed salt solution. A 1.0 mol / L sodium hydroxide solution was slowly added to the filtrate with stirring to adjust the pH to 6.2, and the solution was filtered a second time to obtain a valuable metal leachate.

[0056] Example 2 (1) Reduction calcination: NCM811 (high nickel content) cathode material powder obtained from the treatment of retired ternary lithium batteries was uniformly mixed with a reducing precursor. The reducing precursor was a compound of glucose, activated carbon, and graphite in a mass ratio of 0.5:1.0:0.3, and the total mass ratio of the reducing precursor to the cathode material powder was 1.5:1. After mixing, the mixture was calcined in an air atmosphere. The calcination program was to raise the temperature to 250°C at a rate of 8°C / min, then raise it to 550°C at a rate of 3°C / min, and hold it at 550°C for 50 min. The air flow rate was controlled at 20 mL / min. (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water for leaching treatment. Tween-80 (nonionic surfactant) is added as a surfactant at a concentration of 0.02% of the water mass. The liquid-to-solid ratio is 15 mL / g, the leaching temperature is 20 °C, and the leaching time is 40 min to achieve selective extraction of lithium. Then, solid-liquid separation is performed to obtain a lithium-rich leachate and lithium-extracted residue.

[0057] (3) Activation of residue: The lithium extraction residue obtained in step (2) is washed at 25°C for 10 min with a dilute hydrochloric acid solution of 0.06 mol / L.

[0058] (4) Acid leaching of valuable metals: The activated residue is mixed with water, and the second organic acid is slowly added under ultrasonic and stirring conditions. The reaction is ultrasonic and continuously stirred for 30 min, and then the first organic acid is slowly added. After the reaction is completed, the pH is adjusted to 4.5 using sodium hydroxide solution. The solid and liquid are separated to obtain oxalate precipitate. The second organic acid is a mixture of malic acid and glyoxylic acid (molar ratio 1:1.5). The total molar ratio of the first organic acid peracetic acid to the second organic acid is 2:1, and the total concentration of organic acid is 1.0 mol / L.

[0059] The acid leaching conditions were as follows: liquid-to-solid ratio of 15 mL / g, temperature of 55℃, time of 90 min; ultrasonic frequency of 25 kHz, and mechanical stirring speed of 400 rpm.

[0060] The oxalate precipitate was dissolved in 0.8 mol / L sulfuric acid (liquid-to-solid ratio 8 mL / g, temperature 35℃, time 15 min), and filtered to obtain a mixed salt solution. A 0.8 mol / L sodium hydroxide solution was slowly added to the filtrate with stirring to adjust the pH to 6.0, and the solution was filtered a second time to obtain a valuable metal leachate.

[0061] Example 3 (1) Reduction calcination: NCM622 cathode material powder obtained from the treatment of retired ternary lithium batteries is uniformly mixed with a reducing precursor. The reducing precursor is a mixture of starch, activated carbon and graphite in a mass ratio of 0.4:1.0:0.4, and the total mass of the reducing precursor is 2.0:1. After mixing, the mixture is calcined in an air atmosphere. The calcination program is to raise the temperature to 350°C at a rate of 10°C / min, then raise the temperature to 750°C at a rate of 8°C / min, and hold at 750°C for 30 min. The air flow rate is controlled at 50 mL / min.

[0062] (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water for leaching treatment. Sodium dodecylbenzenesulfonate (anionic surfactant) is added as a surfactant. The amount added is 0.1% of the water mass. The liquid-solid ratio is 8 mL / g. The leaching temperature is 35℃ and the time is 20 min to achieve selective extraction of lithium. Then, solid-liquid separation is performed to obtain lithium-rich leachate and lithium-extracted residue.

[0063] (3) Activation of residue: The lithium extraction residue obtained in step (2) is washed at 50°C for 5 min with a dilute sulfuric acid solution of 0.1 mol / L.

[0064] (4) Acid leaching of valuable metals: The activated residue is mixed with water, and the second organic acid is slowly added under ultrasonic and stirring conditions. The reaction is ultrasonic and continuously stirred for 30 min, and then the first organic acid is slowly added. After the reaction is completed, the pH is adjusted to 4.5 using sodium hydroxide solution. The solid and liquid are separated to obtain oxalate precipitate. The second organic acid is a mixture of tartaric acid and glyoxylic acid (molar ratio 1:3). The total molar ratio of the first organic acid peracetic acid to the second organic acid is 4:1, and the total concentration of organic acid is 2.0 mol / L.

[0065] The acid leaching conditions were as follows: liquid-to-solid ratio of 30 mL / g, temperature of 65℃, time of 60 min; ultrasonic frequency of 35 kHz, and mechanical stirring speed of 250 rpm.

[0066] The oxalate precipitate was dissolved in 1.5 mol / L hydrochloric acid (liquid-to-solid ratio 15 mL / g, temperature 50℃, time 25 min), and filtered to obtain a mixed salt solution. A 1.5 mol / L sodium hydroxide solution was slowly added to the filtrate with stirring to adjust the pH to 6.4, and the solution was filtered a second time to obtain a valuable metal leachate.

[0067] Example 4 (1) Reduction calcination: NCM111 cathode material powder obtained from the treatment of retired ternary lithium batteries is uniformly mixed with a reducing precursor. The reducing precursor is a mixture of starch, activated carbon and graphite in a mass ratio of 0.2:0.8:0.2, and the total mass of the reducing precursor is 0.8:1 to the mass of the cathode material powder. After mixing, the mixture is calcined in an air atmosphere. The calcination program is to raise the temperature to 300°C at a rate of 5°C / min, then raise the temperature to 500°C at a rate of 4°C / min, and hold at 500°C for 60 min. The air flow rate is controlled at 40 mL / min.

[0068] (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water for leaching treatment without the addition of surfactant. The liquid-to-solid ratio is 25 mL / g, the leaching temperature is 15℃, and the time is 60 min to achieve selective extraction of lithium. Then, solid-liquid separation is performed to obtain lithium-rich leachate and lithium-extracted residue.

[0069] (3) Activation of residue: The lithium extraction residue obtained in step (2) is washed at 20°C for 10 min with a dilute hydrochloric acid solution of 0.05 mol / L.

[0070] (4) Acid leaching of valuable metals: The activated residue was mixed with water, and the second organic acid was slowly added under ultrasonic and stirring conditions. The reaction was ultrasonicated and stirred continuously for 30 min, and then the first organic acid was slowly added. After the reaction was completed, the pH was adjusted to 4.5 using sodium hydroxide solution, and oxalate precipitate was obtained by solid-liquid separation. The second organic acid was a mixture of tartaric acid and glyoxylic acid (molar ratio 1:1), the total molar ratio of the first organic acid peracetic acid to the second organic acid was 1:1, and the total concentration of organic acids was 0.8 mol / L.

[0071] Acid leaching conditions: liquid-to-solid ratio of 10 mL / g, temperature of 50℃, time of 120 min; ultrasonic frequency of 20 kHz, mechanical stirring speed of 500 rpm.

[0072] The oxalate precipitate was dissolved in 0.5 mol / L sulfuric acid (liquid-to-solid ratio 5 mL / g, temperature 25℃, time 30 min), and filtered to obtain a mixed salt solution. A 0.5 mol / L sodium hydroxide solution was slowly added to the filtrate with stirring to adjust the pH to 6.0, and the solution was filtered a second time to obtain a valuable metal leachate.

[0073] Example 5 (1) Reduction calcination: The NCM523 cathode material powder obtained by processing retired ternary lithium batteries is uniformly mixed with a reducing precursor. The reducing precursor is a mixture of starch, activated carbon and graphite in a mass ratio of 0.6:1.2:0.4, and the total mass of the reducing precursor is 3.0:1. After mixing, it is calcined in an air atmosphere. The calcination program is to raise the temperature to 320°C at a rate of 6°C / min, then raise the temperature to 700°C at a rate of 6°C / min, and hold at 700°C for 25 min. The air flow rate is controlled at 100 mL / min.

[0074] (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water for leaching treatment. Sodium dodecylbenzenesulfonate (anionic surfactant) is added as a surfactant. The amount added is 0.5% of the water mass. The liquid-solid ratio is 30 mL / g. The leaching temperature is 40℃ and the time is 10 min to achieve selective extraction of lithium. Then, solid-liquid separation is performed to obtain lithium-rich leachate and lithium-extracted residue.

[0075] (3) Residue activation: The lithium extraction residue obtained in step (2) was washed with a 0.09 mol / L dilute sulfuric acid solution at 40°C for 6 min. (4) Acid leaching of valuable metals: The activated residue was mixed with water, and the second organic acid was slowly added under ultrasonic and stirring conditions. The reaction was ultrasonicated and stirred continuously for 30 min, and then the first organic acid was slowly added. After the reaction was completed, the pH was adjusted to 4.5 using sodium hydroxide solution, and oxalate precipitate was obtained by solid-liquid separation. The second organic acid was a mixture of malic acid and glyoxylic acid (molar ratio 1:2.5), and the total molar ratio of the first organic acid peracetic acid to the second organic acid was 5:1. The total concentration of organic acids was 2.5 mol / L.

[0076] Acid leaching conditions: liquid-to-solid ratio of 40 mL / g, temperature of 70℃, time of 60 min; ultrasonic frequency of 40 kHz, mechanical stirring speed of 200 rpm.

[0077] The oxalate precipitate was dissolved in 2.0 mol / L hydrochloric acid (liquid-to-solid ratio 20 mL / g, temperature 60℃, time 10 min), and filtered to obtain a mixed salt solution. A 2.0 mol / L sodium hydroxide solution was slowly added to the filtrate with stirring to adjust the pH to 6.5, and the solution was filtered a second time to obtain a valuable metal leachate.

[0078] Comparative Example 1 (1) Reduction calcination: NCM523 cathode material powder was used, and the only reducing precursor was starch (mass ratio 1.2:1). No activated carbon or graphite was added. The calcination procedure was the same as in Example 1 (heating to 300°C at 5°C / min, then heating to 600°C at 5°C / min, holding for 40 min, and air flow rate of 30 mL / min).

[0079] (2) Lithium extraction by water leaching: Same as in Example 1 (3) Activation of residue: Same as in Example 1.

[0080] (4) Acid leaching of valuable metals: Same as in Example 1.

[0081] Comparative Example 2 (1) Reduction roasting: Same as in Example 1.

[0082] (2) Lithium extraction by water immersion: No surfactants were added, and other conditions were the same as in Example 1.

[0083] (3) Activation of residue: Same as in Example 1.

[0084] (4) Acid leaching of valuable metals: Same as in Example 1.

[0085] Comparative Example 3 (1) Reduction roasting: Same as in Example 1.

[0086] (2) Lithium extraction by water immersion: Same as in Example 1.

[0087] (3) Residue activation: Same as in Example 1.

[0088] (4) Acid leaching of valuable metals: A conventional inorganic acid system (1.0 mol / L sulfuric acid + 3% hydrogen peroxide by volume as oxidant) was used, with a liquid-to-solid ratio of 20 mL / g, a temperature of 60 °C, and a time of 60 min. The ultrasonic and mechanical stirring conditions were the same as in Example 1. After the reaction, solid-liquid separation was performed directly to obtain a valuable metal leachate without undergoing an oxalate precipitation step.

[0089] Comparative Example 4 (1) Reduction roasting: Same as in Example 1.

[0090] (2) Lithium extraction by water immersion: Same as in Example 1.

[0091] (3) Residue activation: Directional activation treatment is omitted, and acid leaching is carried out directly.

[0092] (4) Acid leaching of valuable metals: Same as in Example 1.

[0093] Comparative Example 5 (1) Reduction calcination: The NCM523 cathode material powder obtained by processing retired ternary lithium batteries is uniformly mixed with a reducing precursor. The reducing precursor is a mixture of starch, activated carbon and graphite in a mass ratio of 0.3:0.6:0.3, and the total mass of the reducing precursor is 1.2:1 to the mass of the cathode material powder. After mixing, the mixture is calcined in an air atmosphere. The calcination program is to heat up to 900℃ at a rate of 10℃ / min and hold at 900℃ for 20min. The air flow rate is controlled at 30mL / min.

[0094] (2) Lithium extraction by water leaching: Same as in Example 1 (3) Residue activation: Same as in Example 1.

[0095] (4) Acid leaching of valuable metals: Same as in Example 1.

[0096] The extraction rates of lithium, nickel, cobalt, and manganese in Examples 1-5 and Comparative Examples 1-5 were tested, and the results are shown in the table below:

[0097] Based on the test results of Examples 1-5, all examples achieved the targets of lithium water leaching rate greater than 95% and Ni / Co / Mn acid leaching rate greater than 99%. Among them, Example 5 achieved the highest lithium extraction rate (98.8%) and valuable metal extraction rate (both close to 99.7%) by using a high proportion of reducing agent (3.0:1), a suitable roasting temperature (700℃), and optimized water leaching and acid leaching conditions. In Example 4, due to the low proportion of reducing agent (0.8:1), the low roasting temperature (500℃), and the absence of surfactant in water leaching, the lithium extraction rate dropped to 96.0%, but by extending the acid leaching time, the valuable metal extraction rate was still maintained above 98.3%.

[0098] Comparative Example 1, using only starch as a single reducing agent, lacked the synergistic effect of multi-stage reduction (fast-medium-slow), resulting in a lithium extraction rate of 90.0% and valuable metal extraction rates both below 96.0%. This demonstrates that the synergistic effect of the composite reducing agent is fundamental to achieving efficient lithium conversion and controlling the speciation of valuable metals. Comparative Example 2, due to water leaching without the addition of surfactants, saw a lithium extraction rate decrease to 94.0%, while the valuable metal extraction rate remained largely unaffected. This indicates that surfactants effectively enhance the dissolution of water-soluble lithium compounds without interfering with the subsequent acid leaching process.

[0099] Comparative Example 3, using a traditional inorganic acid system and omitting the oxalate precipitation purification step, saw the valuable metal extraction rate drop below 98.2%, highlighting the synergistic advantage of the oxidation-complexation in the oxidizing organic acid system and the importance of oxalate precipitation in improving valuable metal separation. Comparative Example 4, omitting residue activation treatment, generally resulted in a decrease in valuable metal extraction rates below 97.2%, verifying the necessity of dilute acid activation to remove surface impurities and expose reactive sites. Comparative Example 5, raising the calcination temperature to 900℃, caused lithium volatilization and valuable metal sintering, resulting in a sharp drop in lithium extraction rate to 85.0% and a valuable metal extraction rate below 91.0%, clarifying that the calcination temperature must be strictly controlled within the 500-800℃ range to avoid damaging recovery efficiency due to high temperatures.

[0100] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries, characterized in that, Includes the following steps: (1) Reduction roasting: The cathode material powder obtained by processing retired ternary lithium batteries is uniformly mixed with a reducing precursor and roasted in an air atmosphere to convert lithium in the cathode material into water-soluble lithium compounds, while converting valuable metals Ni, Co and Mn into forms that can be leached by acid. (2) Lithium extraction by water leaching: The roasted product obtained in step (1) is mixed with water and leached to achieve selective extraction of lithium. Then, solid-liquid separation is performed to obtain lithium-rich leachate and lithium-extracted residue. (3) Residue activation: The lithium extraction residue obtained in step (2) is subjected to targeted activation treatment; (4) Acid leaching of valuable metals: The residue after activation in step (3) is acid leached using a leaching agent and then post-treated to remove impurities, thereby recovering valuable metals such as Ni, Co, and Mn.

2. The method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries according to claim 1, characterized in that, In step (1), the reducing precursor is a mixture of starch, glucose, activated carbon, and graphite; when a mixture is used, the mixture is prepared by compounding starch or glucose, activated carbon, and graphite in a mass ratio of (0.2-0.6):(0.4-1.2):(0.1-0.4), and the mass ratio of the reducing precursor to the cathode material powder is 0.5~3:

1.

3. The method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries according to claim 1 or 2, characterized in that, In step (1), the roasting procedure is as follows: first, the temperature is raised to 250-350℃ at a rate of 5-10℃ / min, then raised to 500-800℃ at a rate of 3-8℃ / min, and held for 20-60min; the air flow rate is 10-100mL / min.

4. The method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries according to claim 1, characterized in that, In step (2), a surfactant is added to the water leaching lithium extraction process. The surfactant is a nonionic surfactant or anionic surfactant, and the amount added is 0.01%-1% of the water mass. The liquid-solid ratio of the water leaching lithium extraction is 5-30 mL / g, the temperature is 15-40℃, and the time is 10-60 min.

5. The method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries according to claim 1, characterized in that, In step (3), the directional activation treatment is to wash with a dilute acid solution with a concentration of 0.05-0.1 mol / L at 15-60℃ for 5-10 min.

6. The method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries according to claim 1, characterized in that, In step (4), the leaching agent is an oxidizing organic acid system, which includes a first organic acid as the main oxidant and a second organic acid as a complexing agent; the first organic acid is peracetic acid, the second organic acid is a mixture of malic acid or tartaric acid and glyoxylic acid, in the second organic acid, malic acid or tartaric acid and glyoxylic acid are mixed in a molar ratio of 1:(1-3), the total molar ratio of the first organic acid and the second organic acid in the leaching liquid phase is 1:1 to 5:1, and the concentration of the total organic acid in the first organic acid and the second organic acid in the leaching liquid phase is 0.5-3.0 mol / L.

7. The method for preferential lithium extraction and valuable metal recovery from retired ternary lithium batteries according to claim 6, characterized in that, In step (4), the specific process of acid leaching of valuable metals is as follows: the activated residue is first mixed with water, and the second organic acid is slowly added under ultrasonic and stirring conditions. The reaction is ultrasonic and continuously stirred for 30 minutes, and then the first organic acid is slowly added. After the reaction is completed, sodium hydroxide solution is used to adjust the pH to 4-5, and then solid-liquid separation is performed to obtain oxalate precipitates rich in Ni, Co and Mn. The acid leaching process is carried out under ultrasonic assistance and mechanical stirring. The ultrasonic frequency is 20-40kHz, the mechanical stirring speed is 200-500rpm, the liquid-solid ratio of the acid leaching is 5-50mL / g, the temperature is 50-70℃, and the total time is 60-120min. The oxalate precipitate is dissolved in an inorganic acid solution, wherein the acid solution is one of hydrochloric acid, sulfuric acid, or nitric acid, with a concentration of 0.5-2.0 mol / L, a solution-to-solid ratio of 5-20 mL / g, a temperature of 25-60℃, and a time of 10-30 min, to obtain a pure mixed salt solution rich in Ni, Co, and Mn. The solution is filtered, and the filtrate is retained. A 0.5-2.0 mol / L sodium hydroxide solution is slowly added to the filtrate while stirring to adjust the pH to 6-6.

5. The solution is then filtered a second time to obtain a valuable metal leachate.

8. The method for preferentially extracting lithium and valuable metals from retired ternary lithium batteries according to claim 1, characterized in that, The lithium-rich leachate obtained in step (2) was concentrated and then precipitated with sodium carbonate to prepare battery-grade lithium carbonate; the valuable metal leachate obtained in step (4) was prepared into a Ni, Co, Mn ternary precursor by co-precipitation.

9. The application of the method as described in any one of claims 1-8 in the resource recycling of retired ternary lithium batteries.

10. The application according to claim 9, characterized in that, The recovered Ni, Co, and Mn ternary precursors are used to re-prepare lithium-ion battery cathode materials or to prepare catalytic materials.

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