Method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent

Abstract

The application provides a method for recovering valuable metals in waste lithium battery black powder based on a eutectic solvent, uses a green solvent system composed of a choline / guanidine compound A containing a quaternary ammonium salt structure and an organic carboxylic acid compound B containing two or more carboxyl groups to recover valuable metals in waste lithium battery black powder, realizes preliminary and efficient separation of lithium cobalt manganese and nickel and graphite, recovers cobalt, manganese and lithium from the leaching solution through a step-by-step precipitation method after the lithium cobalt manganese enters the leaching solution, recovers nickel and graphite through acid dissolution separation of the mixture containing nickel and graphite, separates and recovers the mixture of nickel and graphite through subsequent treatment, the leaching conditions are mild, the pollution is small, the cost is low, and the method has good social and economic benefits; the method provided by the application can produce a plurality of high-value products, has the advantages of strong adjustability, high precipitation efficiency, green environmental protection and low cost, and has wide application value in the separation and recovery of valuable metals and graphite resources in battery black powder.

Description

Technical Field

[0001] This invention relates to the field of electrical component technology, and specifically to a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. Background Technology

[0002] Lithium-ion batteries (LIBs) are the primary energy source for new energy vehicles. However, after prolonged use, the structure of their electrode materials deteriorates, leading to performance degradation and eventual retirement. Waste lithium battery black powder (a mixture of positive and negative electrode powder) contains valuable metals such as lithium, nickel, cobalt, and manganese, as well as graphite resources. Recycling and reusing this material not only prevents batteries from causing environmental damage but also alleviates domestic battery resource shortages and reduces production capacity pressure, thus possessing significant economic and environmental value.

[0003] Currently, the recycling process for waste batteries mainly relies on wet extraction. This process involves transferring solid metals from electrode materials into a liquid solution in an acidic or alkaline environment, followed by separation of metal ions from the solution using solvent extraction, chemical precipitation, adsorption, and electrochemical techniques. However, existing technologies struggle to achieve efficient separation of metal elements from graphite when processing black powder, and often focus on the simultaneous separation of elements within the cathode material. This process is not only cumbersome but also prone to metal entrainment losses. Furthermore, current recycling processes often employ strong inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. To enhance the leaching process, large amounts of reducing agents like hydrogen peroxide and sodium hyposulfite are used, generating significant acid fumes that severely corrode equipment and facilities and pose health risks to operators. Therefore, to achieve effective metal leaching and recycling, it is necessary to find greener and more economical alternative solvents.

[0004] In recent years, novel eutectic solvents, as a type of "green solvent," have emerged with advantages such as inexpensive and readily available raw materials, simple preparation, stable physicochemical properties, tunable structural properties, good conductivity, non-volatility, non-flammability, and biodegradability. Furthermore, they exhibit excellent solubility for most metal oxides and are considered promising leaching agents for battery recycling, potentially replacing inorganic and organic acids. However, existing solvent systems have relatively simple compositions, and research on the recovery of lithium-ion battery black powder (a mixture of positive and negative electrode powders) is insufficient. This makes it difficult to achieve the synergistic and efficient separation of valuable metals and graphite, and also presents problems such as long reaction kinetic times and high reaction temperatures. Therefore, it is necessary to explore novel green solvent systems to achieve efficient, clean, and selective recovery of valuable metals and graphite from lithium-ion battery black powder, and to develop highly efficient, environmentally friendly, and economical recycling technologies.

[0005] Therefore, a green method for recycling waste lithium battery black powder is needed. Summary of the Invention

[0006] This invention addresses the efficiency and cleanliness issues in the recycling of waste lithium-ion battery black powder by providing a method for recovering valuable metals from waste lithium-ion battery black powder using a eutectic solvent. This method employs a green solvent system to recover valuable metals from waste lithium-ion battery black powder, achieving preliminary and efficient separation of lithium, cobalt, and manganese from nickel and graphite. After entering the leaching solution, lithium, cobalt, and manganese are recovered from the leaching solution via stepwise precipitation. The mixture containing nickel and graphite is separated and recovered through acid dissolution. The nickel and graphite mixture is further separated and recovered through subsequent processing. The leaching conditions are mild, with low pollution and low cost. The entire process is simple and has good social and economic benefits. The method provided by this invention can produce a variety of high-value products and has advantages such as high adjustability, high precipitation efficiency, environmental friendliness, and low cost. It has broad application value in the separation and recovery of valuable metals and graphite resources from battery black powder.

[0007] This invention provides a method for recovering valuable metals from waste lithium battery black powder using a eutectic solvent, comprising the following steps: S1. After the waste lithium battery is fully discharged, it is disassembled and the black powder is collected. The black powder is heat-treated at 500~600℃ for 0.5~1.5h to remove impurities and obtain lithium battery black powder mixed with nickel cobalt manganese oxide and graphite. S2. A choline / guanidine salt compound A containing a quaternary ammonium salt structure and an organic carboxylic acid compound B containing two or more carboxyl groups are mixed in a molar ratio of 1:10 to 10:1 and heated and stirred at 60 to 120°C for 30 to 120 min to obtain the leaching main agent. Then, 5 to 10 wt% of water or ethanol by mass of the leaching main agent is added for dispersion to obtain a eutectic solvent. S3. Add lithium battery black powder to a eutectic solvent at a solid-liquid ratio of 10~100g / L, stir and leach at 60~120℃ for 10~240min, and centrifuge after leaching to obtain a primary leachate containing lithium cobalt manganese and a mixture containing nickel and graphite. The treatment of the primary leaching solution containing lithium, cobalt, and manganese proceeds to step S4, and the treatment of the mixture containing nickel and graphite proceeds to step S7. S4. Add ammonium oxalate solution to the primary leaching solution containing lithium cobalt manganese to make the pH value 1~3, then leach at 40~60℃ for 30~120min. After leaching, centrifuge to obtain secondary leaching solution containing manganese lithium and cobalt-rich precipitate. Wash the cobalt-rich precipitate with anhydrous ethanol and dry it at 50~80℃, then calcine it at 400~800℃ to obtain cobalt oxide. S5. Add sodium hydroxide to the secondary leaching solution containing lithium manganese to make the pH value 11~12, centrifuge to obtain the tertiary leaching solution containing lithium and the manganese-rich precipitate, wash the manganese-rich precipitate with anhydrous ethanol, dry it at 50~80℃ and then calcine it at 600~1000℃ to obtain manganese oxide. S6. After adding soda ash solution to lithium-containing ternary leaching solution, the solution is evaporated and concentrated to produce lithium carbonate precipitate, which is then washed with anhydrous ethanol and dried to obtain lithium carbonate. S7. Add 0.1~0.5mol / L acid solution to the mixture containing nickel and graphite to dissolve the nickel. Stir and dissolve at 30~80℃ for 30~180min, then centrifuge to obtain graphite and nickel-containing solution. The graphite is washed, dried and directly recycled. Add precipitant to nickel-containing solution and react at 30~80℃ for 60~240min. Separate solid and liquid to obtain nickel-rich precipitate. Wash the nickel-rich precipitate with anhydrous ethanol, dry at 50~80℃, and calcine at 400~800℃ for 1~3h to obtain nickel oxide.

[0008] The present invention discloses a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. In a preferred embodiment, in step S1, the black powder includes positive electrode powder and negative electrode powder. Lithium nickel cobalt manganese oxide is the positive electrode powder, and lithium nickel cobalt manganese oxide is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2; Graphite is the negative electrode powder; Impurities include binders.

[0009] The present invention describes a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. In a preferred embodiment, in step S2, the choline / guanidine salt compound A containing a quaternary ammonium salt structure is at least one of a choline derivative having a quaternary ammonium salt functional group and an inorganic acid salt type guanidine compound. Organic carboxylic acid compound B containing two or more carboxyl groups is at least one of aliphatic dicarboxylic acids and hydroxyaliphatic dicarboxylic acids.

[0010] The method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent described in this invention, as a preferred embodiment, uses choline / guanidine salt compound A containing a quaternary ammonium salt structure as choline chloride, acetamide, or guanidine hydrochloride. Organic carboxylic acid compounds B containing two or more carboxyl groups are oxalic acid, tartaric acid, or citric acid.

[0011] The present invention discloses a method for recovering valuable metals from waste lithium-ion battery black powder based on a eutectic solvent. In a preferred embodiment, the leaching method in step S3 is as follows: a choline / guanidine salt compound A containing a quaternary ammonium salt structure provides a high concentration of chloride ions and a solvent environment; an organic carboxylic acid compound B containing two or more carboxyl groups provides acidity and coordination. During the leaching reaction, the ternary layered structure of lithium nickel cobalt manganese oxide is first destroyed, and the high-valent nickel, cobalt, and manganese are reduced to divalent. Lithium ions preferentially enter the primary leaching solution due to their weak coordination and high solubility. Cobalt and manganese form stable and soluble complexes with chloride ions, which are efficiently leached and retained in the primary leaching solution to obtain a primary leaching solution containing lithium, cobalt, and manganese. Nickel forms a chelate with low solubility with the acid radical and preferentially precipitates to obtain a mixture containing nickel and graphite. In the same system, the separation of graphite and nickel from lithium, cobalt, and manganese is achieved in one step.

[0012] The method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent according to the present invention, as a preferred embodiment, in step S3, the stirring speed during leaching is 200~1000 rpm, the centrifugation speed during centrifugation is 8000~12000 rpm, and the centrifugation time is 5~20 min. In step S3, the leaching efficiency of lithium, cobalt, and manganese is greater than 99%.

[0013] The present invention discloses a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. In a preferred embodiment, in step S4, the molar ratio of ammonium oxalate to cobalt in the primary leaching solution containing lithium cobalt and manganese is 1:(1~1.5), the centrifugation speed is 8000~12000 rpm, the centrifugation time is 5~20 min, and the calcination time is 1~3 h.

[0014] The method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent according to the present invention, as a preferred embodiment, in step S5, the centrifugation speed is 8000~12000 rpm, the centrifugation time is 5~20 min, and the calcination time is 1~3 h.

[0015] The present invention discloses a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. In a preferred embodiment, in step S6, the molar ratio of soda ash to lithium is 1:(1.15~1.2), the evaporation and concentration reaction temperature is 80~100℃, and the reaction time is 30~90min.

[0016] The method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent according to the present invention, as a preferred embodiment, in step S7, the acid solution is one of sulfuric acid and hydrochloric acid or a mixture thereof, with a concentration of 0.5~2 mol / L; Graphite is washed with deionized water, dried at 80-120℃ for 2-6 hours, and then recycled for reuse. The precipitation reaction temperature is 30~80℃, and the reaction time is 60~240min; the precipitant is one or more of sodium hydroxide and oxalic acid.

[0017] In this invention, the black powder is a mixture of positive electrode powder and negative electrode powder. This invention is a method for separating and recovering valuable metals in waste lithium battery black powder based on a novel green eutectic solvent.

[0018] The principle of this invention is as follows: In the novel green solvent system, the main leaching agent is a choline / guanidine salt compound A containing a quaternary ammonium salt structure and an organic carboxylic acid compound B containing two or more carboxyl groups. The co-solvent is water or ethanol. The choline / guanidine salt compound A containing a quaternary ammonium salt structure provides a high concentration of chloride ions and a solvent environment, while the organic carboxylic acid compound B containing two or more carboxyl groups provides acidity and coordination. During the reaction, the layered structure of the ternary material is first destroyed, and the high-valent nickel, cobalt, and manganese are reduced to divalent. Lithium ions preferentially enter the solution due to their weak coordination and high solubility. Cobalt and manganese form stable and soluble complexes with chloride ions, thus being efficiently leached and retained in the liquid phase. Nickel forms chelates with acid radicals with extremely low solubility and preferentially precipitates. Thus, the efficient separation of nickel from lithium, cobalt, and manganese is achieved in one step in the same system.

[0019] The invention provides a method for separating and recycling valuable metals from waste lithium battery black powder, comprising the following steps: S1. Pretreatment of waste lithium battery black powder After the waste lithium battery is fully discharged, it is disassembled and the black powder (a mixture of positive and negative electrode powder) is collected. It is then heat-treated at 500~600℃ for 0.5~1.5h to remove impurities such as binders and obtain lithium battery black powder.

[0020] Lithium battery black powder originates from LiNi-containing compounds 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 Lithium batteries using one or more positive electrode materials in O2 and graphite negative electrode materials.

[0021] S2, Preparation of Eutectic Solvent Weigh out choline / guanidine salt compound A containing quaternary ammonium salt structure and organic carboxylic acid compound B containing two or more carboxyl groups in proportion. Mix the two and heat and stir at 60~120℃ for 30~120min to obtain a uniform and transparent leaching main agent. Then add water or ethanol to disperse it to obtain a solvent.

[0022] The choline / guanidine salt compound A containing a quaternary ammonium salt structure is selected from at least one of choline derivatives with quaternary ammonium salt functional groups and inorganic acid salt type guanidine compounds; the organic carboxylic acid compound B containing two or more carboxyl groups is selected from at least one of aliphatic dicarboxylic acids and hydroxyaliphatic dicarboxylic acids.

[0023] Previous studies on solvent systems have primarily focused on the recovery of metals from single cathode materials, neglecting in-depth research on the synergistic separation of metals and graphite in lithium-ion battery black powder, and the metal separation efficiency needs improvement. To address this issue, this invention develops a novel eutectic solvent system. Experimental data calculations show that this system achieves nearly 100% leaching efficiency for lithium, cobalt, and manganese, while nickel remains in the solid phase along with graphite. This achieves highly efficient separation of lithium, cobalt, and manganese from nickel and graphite, reducing metal entrainment losses and laying the foundation for high-purity recovery of subsequent components.

[0024] Furthermore, the effective components of choline / guanidine salt compounds A containing quaternary ammonium salt structures and organic carboxylic acid compounds B containing two or more carboxyl groups should be controlled in their dosage relationship as novel green solvents. When the molar ratio of compound A to compound B is 1:10 to 10:1, the leaching efficiency for lithium cobalt manganese is high, and effective separation of lithium cobalt manganese from nickel and graphite can be achieved. Preferably, the separation effect is even better when the molar ratio of compound A to compound B is 1:2 to 2:1. For example, the molar ratio of compound A to compound B can be 2:1, 3:2, 1:1, 2:3, 1:2, etc.

[0025] Furthermore, since the leaching main agent formed by compound A and compound B has a high viscosity, it is difficult to handle or separate solids and liquids in the future, and it tends to adhere to the solid mixture. Therefore, during the preparation of the eutectic solvent, a small amount of water or ethanol is added as a co-solvent to improve the fluidity of the leaching main agent and reduce its viscosity. The amount of co-solvent added is 5 to 10 wt% of the mass of the leaching main agent.

[0026] S3. Preliminary separation of lithium, cobalt, and manganese from nickel and graphite in lithium battery black powder. The lithium battery black powder obtained in step S1 is added to the solvent obtained in step S2, with a solid-liquid ratio of 10~100g / L. Then, the mixture is stirred and leached at 80~120℃ for 40~90min. After leaching, the mixture is centrifuged to obtain a primary leachate (containing lithium, cobalt, and manganese) and a mixture containing nickel and graphite. The centrifugation speed is 8000~12000rpm and the centrifugation time is 5~20min.

[0027] For example, the solid-liquid ratio of lithium battery black powder to the novel green solvent can be 10g / L, 15g / L, 20g / L, 25g / L, 30g / L, 35g / L, 40g / L, 45g / L, 50g / L, 55g / L, 60g / L, 65g / L, 70g / L, 75g / L, 80g / L, 85g / L, 90g / L, 95g / L, 100g / L, etc., or any range formed by two points.

[0028] Furthermore, the leaching temperature is 60~120℃ and the leaching time is 10~240min; preferably, the leaching temperature is 80~120℃ and the leaching time is 40~90min.

[0029] Furthermore, the stirring speed during the leaching process is controlled at 200~1000 rpm.

[0030] S4. Selective separation of cobalt from primary leachate Ammonium oxalate solution was added to the primary leachate (pH 1-3) obtained in step S3, with a molar ratio of ammonium oxalate to cobalt of 1:1-1.5. The reaction was carried out at 40-60℃ for 30-120 min. After leaching, the secondary leachate (containing lithium manganese) and cobalt-rich precipitate were obtained by centrifugation at 8000-12000 rpm for 5-20 min. The cobalt-rich precipitate was washed with anhydrous ethanol, dried at 50-80℃, and then calcined to obtain cobalt oxide at 400-800℃ for 1-3 h.

[0031] S5. Selective separation of manganese from secondary leachate Sodium hydroxide was added to the secondary leachate obtained in step S4 to adjust the pH of the solution to 11-12. The solution was then centrifuged to obtain a tertiary leachate (containing lithium) and a manganese-rich precipitate. The centrifugation speed was 8000-12000 rpm, and the centrifugation time was 5-20 min. The manganese-rich precipitate was washed with anhydrous ethanol, dried at 50-80℃, and then calcined to obtain manganese oxide. The calcination temperature was 600-1000℃, and the calcination time was 1-3 h.

[0032] S6. Lithium precipitate in the ternary leaching solution The three leachates obtained in step S5 are evaporated and concentrated, and then a soda ash solution is added to produce a precipitate. The reaction equation is Li⁺ + CO₃²⁻ → Li₂CO₃↓. After washing with anhydrous ethanol and drying, lithium carbonate is obtained. The reaction conditions are: n(Li⁺):n(CO₃²⁻) = 1:1.15~1.2 (molar ratio of soda ash to lithium is 1:1.15~1.2), reaction temperature is 80~100℃, and reaction time is 30~90 min.

[0033] S7. Separation and recovery of nickel-containing and graphite mixtures After obtaining the mixture containing nickel and graphite, it needs to undergo acid dissolution, separation, precipitation, washing, drying, and calcination to finally obtain nickel oxide. Graphite can be directly recycled after washing and drying. The acid solution used for acid dissolution is one or a mixture of sulfuric acid and hydrochloric acid, with a concentration of 0.5~2 mol / L; the dissolution temperature is 30~80℃, and the dissolution time is 30~180 min; the precipitation reaction temperature is 30~80℃, and the reaction time is 60~240 min; the precipitant used for nickel precipitation is one or more of sodium hydroxide and oxalic acid; the washing reagent is anhydrous ethanol; the drying conditions are 50~80℃; and the controlled calcination temperature is 400~800℃, and the calcination time is 1~3 h.

[0034] After obtaining nickel-rich, cobalt-rich, and manganese-rich precipitates, they need to be washed, dried, and calcined to finally obtain nickel oxide, cobalt oxide, and manganese oxide.

[0035] The specific method is as follows: the nickel-containing and graphite mixture obtained in step S3 is added to a 0.1~0.5mol / L acid solution (one of sulfuric acid, hydrochloric acid or a mixture thereof) to dissolve the nickel. The mixture is stirred and dissolved at 30~80℃ for 30~180min. After centrifugation (solid-liquid separation), graphite and nickel-containing solution are obtained. The graphite is washed with deionized water, dried at 80~120℃ for 2~6h, and then recycled. A precipitant is added to the nickel-containing solution, and the mixture is reacted at 30~80℃ for 60~240min. After solid-liquid separation, nickel-rich precipitate is obtained. The nickel-rich precipitate is washed with anhydrous ethanol, dried at 50~80℃, and then calcined at 400~600℃ for 1~3h to obtain nickel oxide.

[0036] The present invention has the following advantages: (1) This invention provides a method for applying a novel green eutectic solvent to recover valuable metals from waste lithium battery black powder. The novel green eutectic solvent contains choline / guanidine salt compounds A with quaternary ammonium salt structures and organic carboxylic acid compounds B with binary or higher carboxyl groups. After mixing, leaching, and solid-liquid separation of the novel green eutectic solvent with lithium battery black powder, the mixture containing nickel and graphite and the leachate (containing lithium cobalt manganese) are collected to achieve efficient separation of lithium cobalt manganese from nickel and graphite. Nickel and graphite remain in the solid phase. Subsequent acid dissolution treatment can achieve the separation and recovery of nickel and graphite. The eutectic solvent system of this invention has the advantages of low leaching temperature (mild conditions), short kinetic time, lithium cobalt manganese leaching efficiency greater than 99%, good separation effect, low entrainment loss of metal elements, low pollution, and low cost. Moreover, the method has flexible and diverse export products and strong adjustability, and has broad application value in the separation and recovery of valuable metals and graphite resources in battery black powder.

[0037] (2) The present invention also provides a method for separating and recycling valuable metals in waste lithium battery black powder. The method uses a stepwise precipitation method on the leachate after preliminary separation to obtain cobalt-rich precipitate, manganese-rich precipitate and lithium-rich precipitate in sequence. The mixture containing nickel and graphite is treated with dilute acid dissolution and precipitation to recover nickel and graphite. Finally, the comprehensive recovery of four metals, nickel, cobalt, manganese and lithium and graphite resources is achieved, showing high recovery efficiency and resource utilization rate. It is expected to be widely used in the field of resource recycling of lithium battery black powder. Attached Figure Description

[0038] Figure 1 A flowchart of a method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent; Figure 2 This is a schematic diagram of nickel precipitation efficiency in Example 1 of a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. Figure 3 This is a schematic diagram of the nickel product characterization results in Example 1 of a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent. Figure 4 XRD pattern of cobalt product in Example 1 of a method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent; Figure 5 XRD pattern of manganese product in Example 1 of a method for recovering valuable metals from waste lithium battery black powder based on eutectic solvent. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1

[0040] like Figure 1 As shown, a method for recovering valuable metals from waste lithium-ion battery black powder based on a eutectic solvent is proposed. This method employs a novel green eutectic solvent system to selectively recover valuable metals from waste lithium-ion battery black powder. The selected green solvent system has the effect of efficiently separating lithium, cobalt, and manganese from nickel and graphite. After entering the leaching solution, lithium, cobalt, and manganese can be recovered by stepwise precipitation. Nickel and graphite are separated and recovered through subsequent dilute acid dissolution treatment. The selected solvent system can achieve high metal leaching and separation efficiency at lower leaching temperatures and shorter leaching times. Furthermore, this method has high recovery efficiency for cobalt, manganese, lithium, nickel, and graphite, strong adjustability, and is environmentally friendly. It has broad application value in the separation and recovery of valuable metals and graphite resources from battery black powder.

[0041] The specific method includes the following steps: S1. Pretreatment of waste lithium battery black powder After the waste lithium battery is fully discharged, it is disassembled and the black powder (a mixture of positive and negative electrode powder) is collected. It is then heat-treated at 550°C for 1 hour to remove impurities such as binders, and lithium battery black powder is obtained.

[0042] Lithium battery black powder originates from LiNi-containing compounds 0.6 Co 0.2 Mn 0.2 Lithium-ion batteries using O2 as the positive electrode material and graphite as the negative electrode material.

[0043] S2. Prepare a mixture of choline chloride and oxalic acid in a molar ratio of 1:1. After mixing, heat and stir at 80°C for 30 minutes to obtain the leaching main agent. Then add 5 wt% of deionized water by mass of the leaching main agent to obtain a eutectic solvent.

[0044] S3. The eutectic solvent and lithium battery black powder are fed into the mixture at a solid-liquid ratio of 20g / L. The mixture is stirred and leached at 100℃ for 60min. The mixture is centrifuged to obtain a primary leaching solution (containing lithium, cobalt, and manganese) and a mixture containing nickel and graphite. The leaching efficiency of lithium, cobalt, and manganese is greater than 99%. The primary leaching solution is processed in step S4, and the mixture containing nickel and graphite is processed in step S7. S4. Add ammonium oxalate solution directly to the primary leachate. The molar ratio of ammonium oxalate to cobalt is 1:1.3. React at 50℃ for 2 hours. Centrifuge to obtain secondary leachate and cobalt-rich precipitate. After washing and drying, the cobalt-rich precipitate is calcined in a muffle furnace at 500℃ for 2 hours with the heating rate controlled at 10℃ / min to obtain cobalt oxide. S5. Add sodium hydroxide to the secondary leachate to adjust the pH of the solution to 12. Centrifuge to separate the tertiary leachate and manganese-rich precipitate. After washing and drying, the manganese-rich precipitate is calcined in a muffle furnace at 800℃ for 2 hours with the heating rate controlled at 10℃ / min to obtain manganese oxide. S6. The leaching solution from the three extractions is evaporated and concentrated, and then a soda ash solution is added to produce lithium carbonate precipitate. The reaction conditions are as follows: the molar ratio of soda ash to lithium is controlled at n(Li). + ): n(CO3) 2- The ratio of 1:1.2 was used, and the mixture was reacted at 90℃ for 60 min. The resulting lithium carbonate precipitate was obtained by washing with anhydrous ethanol and drying.

[0045] S7. Add the mixture containing nickel and graphite to a 0.1 mol / L hydrochloric acid solution, stir and dissolve at 60°C for 60 min, centrifuge to obtain graphite and nickel-containing solution; wash the graphite three times with deionized water, dry at 100°C for 4 h and then recover it; add sodium hydroxide solution to the nickel-containing solution, react at 60°C for 120 min, separate the solid and liquid to obtain nickel-rich precipitate, wash the nickel-rich precipitate three times with anhydrous ethanol, dry at 60°C overnight, and then calcine in a muffle furnace at 500°C for 2 h, controlling the heating rate at 10°C / min to obtain nickel oxide product.

[0046] The above describes the process of comprehensively recycling valuable metals such as nickel, cobalt, manganese, lithium, and graphite resources from lithium battery black powder. The product has good crystallinity and high purity. The obtained metal oxides can not only be used for battery regeneration but also for their respective applications. Graphite can be directly recycled and reused.

[0047] Figures 2-3 The nickel precipitation efficiency and nickel product characterization results are for Example 1. Figure 4 The image shows the XRD pattern of the cobalt product obtained in Example 1. Figure 5 The image shows the XRD pattern of the manganese product obtained in Example 1. Figures 2-5 As can be seen, the precipitation efficiency of this embodiment is relatively high, and the purity of the obtained nickel, cobalt and manganese products is also relatively high. Example 2

[0048] like Figure 1 As shown, a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent is described, and the specific method includes the following steps: S1. Pretreatment of waste lithium battery black powder After the waste lithium battery is fully discharged, it is disassembled and the black powder (a mixture of positive and negative electrode powder) is collected. It is then heat-treated at 550°C for 1 hour to remove impurities such as binders, and lithium battery black powder is obtained.

[0049] Lithium battery black powder originates from LiNi-containing compounds 0.6 Co 0.2 Mn 0.2 Lithium-ion batteries using O2 as the positive electrode material and graphite as the negative electrode material.

[0050] S2. Prepare a mixture of choline chloride and tartaric acid in a molar ratio of 2:3. Heat and stir the mixture at 90°C for 60 minutes to obtain the leaching main agent. Then add 10 wt% of the mass of the leaching main agent of deionized water to obtain a eutectic solvent.

[0051] S3. The eutectic solvent and lithium battery black powder are fed into the mixture at a solid-liquid ratio of 10 g / L. The mixture is stirred and leached at 120°C for 20 min. After centrifugation, a primary leaching solution (containing lithium, cobalt, and manganese) and a mixture containing nickel and graphite are obtained. The leaching efficiency of lithium, cobalt, and manganese is greater than 99%.

[0052] The treatment of the primary leachate proceeds to step S4, and the treatment of the mixture containing nickel and graphite proceeds to step S7. S4. Add ammonium oxalate solution directly to the primary leachate. The molar ratio of ammonium oxalate to cobalt is 1:1.2. React at 55℃ for 2 hours. Centrifuge to obtain secondary leachate and cobalt-rich precipitate. After washing and drying, the cobalt-rich precipitate is calcined in a muffle furnace at 500℃ for 2 hours with the heating rate controlled at 10℃ / min to obtain cobalt oxide.

[0053] S5. Add sodium hydroxide to the secondary leachate to adjust the pH of the solution to 11. Centrifuge to obtain the tertiary leachate and manganese-rich precipitate. After washing and drying, the manganese-rich precipitate is calcined in a muffle furnace at 800℃ for 1 hour, with the heating rate controlled at 10℃ / min, to obtain manganese oxide.

[0054] S6. The leaching solution from the three extractions is evaporated and concentrated, and then a soda ash solution is added to produce lithium carbonate precipitate. The reaction conditions are as follows: the molar ratio of soda ash to lithium is controlled at n(Li). + ): n(CO3) 2- The ratio of 1:1.15 was used, and the reaction was carried out at 90℃ for 90 min. The resulting lithium carbonate precipitate was obtained by washing with anhydrous ethanol and drying.

[0055] S7. Add the mixture of nickel and graphite to a 0.2 mol / L hydrochloric acid solution, stir and dissolve at 50°C for 90 min, centrifuge to obtain graphite and nickel-containing solution; wash the graphite three times with deionized water, dry at 110°C for 3 h and then recover it; add oxalic acid solution to the nickel-containing solution, react at 50°C for 180 min, separate the solid and liquid to obtain nickel-rich precipitate, wash the nickel-rich precipitate three times with anhydrous ethanol, dry at 60°C overnight, and then calcine in a muffle furnace at 500°C for 1 h, controlling the heating rate at 10°C / min to obtain nickel oxide product.

[0056] The above describes the process of comprehensively recycling valuable metals such as nickel, cobalt, manganese, lithium, and graphite resources from lithium battery black powder. The product has good crystallinity and high purity. The obtained metal oxides can not only be used for battery regeneration but also for their respective applications. Graphite can be directly recycled and reused. Example 3

[0057] like Figure 1 As shown, a method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent is described, and the specific method includes the following steps: S1. Pretreatment of waste lithium battery black powder After the waste lithium battery is fully discharged, it is disassembled and the black powder (a mixture of positive and negative electrode powder) is collected. It is then heat-treated at 550°C for 1 hour to remove impurities such as binders, and lithium battery black powder is obtained.

[0058] Lithium battery black powder originates from LiNi-containing compounds 0.6 Co 0.2 Mn 0.2 Lithium-ion batteries using O2 as the positive electrode material and graphite as the negative electrode material.

[0059] S2. Acetamide and tartaric acid are prepared in a molar ratio of 3:2. After mixing, they are heated and stirred at 80°C for 60 minutes to obtain the leaching main agent. Then, 10 wt% of the mass of the leaching main agent is added to deionized water to obtain a eutectic solvent.

[0060] S3. The eutectic solvent and lithium battery black powder were fed into the mixture at a solid-liquid ratio of 20 g / L. The mixture was stirred and leached at 120°C for 60 min. After centrifugation, a primary leachate (containing lithium, cobalt, and manganese) and a mixture containing nickel and graphite were obtained. The leaching efficiency of lithium, cobalt, and manganese was close to 100%. The treatment of the primary leachate proceeds to step S4, and the treatment of the mixture containing nickel and graphite proceeds to step S7. S4. Add ammonium oxalate solution directly to the primary leachate. The molar ratio of ammonium oxalate to cobalt is 1:1.2. React at 50°C for 2 hours. Centrifuge to obtain secondary leachate and cobalt-rich precipitate. After washing and drying, the cobalt-rich precipitate is calcined in a muffle furnace at 500°C for 2 hours with a heating rate of 5°C / min to obtain cobalt oxide.

[0061] S5. Add sodium hydroxide to the secondary leachate to adjust the pH of the solution to 12. Centrifuge to obtain the tertiary leachate and manganese-rich precipitate. After washing and drying, the manganese-rich precipitate is calcined in a muffle furnace at 800℃ for 2 hours with the heating rate controlled at 5℃ / min to obtain manganese oxide.

[0062] S6. The leaching solution from the three extractions is evaporated and concentrated, and then a soda ash solution is added to produce lithium carbonate precipitate. The reaction conditions are as follows: the molar ratio of soda ash to lithium is controlled at n(Li⁺):n(CO₃²⁻) = 1:1.15, and the reaction is carried out at 90℃ for 120 min. The resulting lithium carbonate precipitate is obtained by washing with anhydrous ethanol and drying.

[0063] S7. Add the mixture containing nickel and graphite to a 0.1 mol / L sulfuric acid-hydrochloric acid mixed solution (volume ratio 1:1), stir and dissolve at 70°C for 45 min, centrifuge to obtain graphite and nickel-containing solution; wash the graphite three times with deionized water, dry at 90°C for 5 h and then recover it; add sodium hydroxide solution to the nickel-containing solution, react at 40°C for 200 min, separate the solid and liquid to obtain nickel-rich precipitate, wash the nickel-rich precipitate three times with anhydrous ethanol, dry at 60°C overnight, and then calcine in a muffle furnace at 500°C for 2 h, controlling the heating rate at 5°C / min to obtain nickel oxide product.

[0064] The above describes the process of comprehensively recycling valuable metals such as nickel, cobalt, manganese, lithium, and graphite resources from lithium battery black powder. The product has good crystallinity and high purity. The obtained metal oxides can not only be used for battery regeneration but also for their respective applications. Graphite can be directly recycled and reused.

[0065] The metal recovery results for different leaching processes in Examples 1-3 are summarized in Table 1: Table 1

[0066] Comparative Example 1 Choline chloride and urea were prepared in a molar ratio of 1:1. After mixing, the mixture was heated and stirred at 80°C for 30 minutes to obtain the leaching agent. Then, 5 wt% of deionized water was added to obtain the solvent system.

[0067] The solvent system and the lithium battery black powder obtained in step S1 of Examples 1-3 were fed into the mixture at a solid-liquid ratio of 20 g / L. The mixture was stirred and leached at 100°C for 60 min. The leaching solution and solid mixture were separated by centrifugation. The leaching efficiencies of nickel, cobalt and manganese were 0.16%, 0.19% and 0.13% respectively, and the effective separation of lithium cobalt manganese from nickel and graphite was not achieved.

[0068] Comparative Example 2 Choline chloride and propionic acid were prepared in a molar ratio of 1:1. After mixing, the mixture was heated and stirred at 80°C for 30 minutes to obtain the leaching agent. Then, 5 wt% of deionized water was added to obtain the solvent system.

[0069] The solvent system and the lithium battery black powder obtained in step S1 of Examples 1-3 were fed into the mixture at a solid-liquid ratio of 20 g / L. The mixture was stirred and leached at 100°C for 60 min. The leaching solution and solid mixture were obtained by centrifugation. The leaching efficiencies of nickel, cobalt and manganese were 16.32%, 16.18% and 16.54% respectively. Effective separation of lithium cobalt manganese from nickel and graphite was not achieved.

[0070] Comparative Example 3 Choline chloride and malonic acid were prepared in a molar ratio of 1:1. After mixing, the mixture was heated and stirred at 80°C for 30 minutes to obtain an extractant. Then, 5 wt% of deionized water was added to obtain a solvent system.

[0071] The solvent system and the lithium battery black powder obtained in step S1 of Examples 1-3 were fed into the mixture at a solid-liquid ratio of 20 g / L. The mixture was stirred and leached at 100°C for 60 min. The leaching solution and solid mixture were separated by centrifugation. The leaching efficiencies of nickel, cobalt and manganese were 75.25%, 81.27% and 84.62% respectively. Effective separation of lithium cobalt manganese from nickel and graphite was not achieved.

[0072] Comparative Example 4 Choline chloride and malic acid were mixed in a molar ratio of 1:1 and then heated and stirred at 80°C for 30 minutes to obtain an extractant. Then, 5 wt% of deionized water was added to obtain a solvent system.

[0073] The solvent system and lithium battery black powder were fed into the mixture at a solid-liquid ratio of 20 g / L. The mixture was stirred and leached at 100 °C for 60 min. After centrifugation, the leachate and solid mixture were obtained. The leaching efficiencies of nickel, cobalt and manganese were 95.44%, 95.81% and 94.90% respectively. Effective separation of lithium cobalt manganese from nickel and graphite was not achieved.

[0074] Comparative Example 5 Choline chloride and p-toluenesulfonic acid were mixed at a molar ratio of 1:1 and then heated and stirred at 80°C for 30 min to obtain a leaching agent. Deionized water at 5 wt% of the leaching agent mass was then added to obtain a solvent system. This solvent system and lithium battery black powder were added at a solid-liquid ratio of 20 g / L, and leaching was carried out at 100°C with stirring for 60 min. Centrifugation was then used to separate the leachate and the solid mixture. The leaching efficiencies for nickel, cobalt, and manganese were 99.64%, 99.67%, and 98.85%, respectively, indicating that effective separation of lithium, cobalt, and manganese from nickel and graphite was not achieved.

[0075] None of the above comparative examples achieved selective separation of lithium, cobalt, and manganese from nickel and graphite. They only achieved simultaneous leaching of metal elements in lithium battery black powder to varying degrees or with extremely low leaching efficiency. Compared with the stepwise separation and recovery of the present invention, the separation of metal elements in the comparative examples is more complex and involves more steps. Moreover, the leaching efficiency of cobalt, manganese, and lithium is not complete enough, which leads to low product purity, mutual entrainment between solid samples, and failure to effectively recover graphite resources.

[0076] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent, characterized in that: Includes the following steps: S1. After the waste lithium battery is fully discharged, it is disassembled and the black powder is collected. The black powder is heat-treated at 500~600℃ for 0.5~1.5h to remove impurities and obtain lithium battery black powder mixed with nickel cobalt manganese oxide and graphite. S2. A choline / guanidine salt compound A containing a quaternary ammonium salt structure and an organic carboxylic acid compound B containing two or more carboxyl groups are mixed in a molar ratio of 1:10 to 10:1 and heated and stirred at 60 to 120°C for 30 to 120 min to obtain a leaching main agent. Then, 5 to 10 wt% of water or ethanol by mass of the leaching main agent is added for dispersion to obtain a eutectic solvent. S3. The lithium battery black powder is added to the eutectic solvent at a solid-liquid ratio of 10~100g / L, and stirred and leached at a temperature of 60~120℃ for 10~240min. After leaching, centrifugation is performed to obtain a primary leaching solution containing lithium cobalt and manganese and a mixture containing nickel and graphite. The treatment of the primary leaching solution containing lithium cobalt and manganese proceeds to step S4, and the treatment of the mixture containing nickel and graphite proceeds to step S7. S4. Add ammonium oxalate solution to the primary leaching solution containing lithium cobalt manganese to make the pH value 1~3, and then leach at 40~60℃ for 30~120min. After leaching, centrifuge to obtain a secondary leaching solution containing manganese lithium and a cobalt-rich precipitate. Wash the cobalt-rich precipitate with anhydrous ethanol and dry it at 50~80℃, and then calcine it at 400~800℃ to obtain cobalt oxide. S5. Add sodium hydroxide to the secondary leaching solution containing lithium manganese to make the pH value 11~12, centrifuge to separate the lithium-containing tertiary leaching solution and manganese-rich precipitate, wash the manganese-rich precipitate with anhydrous ethanol, dry it at 50~80℃ and then calcine it at 600~1000℃ to obtain manganese oxide. S6. After adding the soda ash solution to the lithium-containing triple leaching solution, the solution is evaporated and concentrated to produce lithium carbonate precipitate, which is then washed with anhydrous ethanol and dried to obtain lithium carbonate. S7. Add 0.1~0.5mol / L acid solution to the nickel-containing and graphite mixture to dissolve the nickel. Stir and dissolve at 30~80℃ for 30~180min, then centrifuge to obtain graphite and nickel-containing solution. The graphite is washed, dried and directly recycled. Add a precipitant to the nickel-containing solution and react at 30~80℃ for 60~240min. Separate the solid and liquid to obtain nickel-rich precipitate. Wash the nickel-rich precipitate with anhydrous ethanol, dry at 50~80℃, and calcine at 400~800℃ for 1~3h to obtain nickel oxide.

2. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S1, the black powder includes positive electrode powder and negative electrode powder; Lithium nickel cobalt manganese oxide is the positive electrode powder, and lithium nickel cobalt manganese oxide is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 One or more of O2; Graphite is the negative electrode powder; The impurities include binders.

3. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S2, the choline / guanidine salt compound A containing a quaternary ammonium salt structure is at least one of choline derivatives having quaternary ammonium salt functional groups and inorganic acid salt type guanidine compounds; The organic carboxylic acid compound B containing two or more carboxyl groups is at least one of aliphatic dicarboxylic acids and hydroxyaliphatic dicarboxylic acids.

4. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 3, characterized in that: The choline / guanidine salt compound A containing a quaternary ammonium salt structure is choline chloride, acetamide, or guanidine hydrochloride; The organic carboxylic acid compound B containing two or more carboxyl groups is oxalic acid, tartaric acid, or citric acid.

5. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S3, the leaching method is as follows: the choline / guanidine salt compound A containing quaternary ammonium salt structure provides a high concentration of chloride ions and solvent environment, and the organic carboxylic acid compound B containing two or more carboxyl groups provides acidity and coordination. During the leaching reaction, the ternary material layered structure of lithium nickel cobalt manganese oxide is first destroyed and the high-valence nickel, cobalt, and manganese are reduced to divalent. Lithium ions preferentially enter the primary leaching solution due to their weak coordination and high solubility. Cobalt and manganese form stable and soluble complexes with chloride ions, which are efficiently leached and retained in the primary leaching solution to obtain the primary leaching solution containing lithium cobalt manganese. Nickel forms a chelate with low solubility with acid radicals and preferentially precipitates to obtain a mixture containing nickel and graphite. In the same system, the separation of graphite and nickel from lithium, cobalt, and manganese is achieved in one step.

6. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S3, the stirring speed during leaching is 200~1000 rpm, the centrifugation speed during centrifugation is 8000~12000 rpm, and the centrifugation time is 5~20 min; In step S3, the leaching efficiency of lithium, cobalt, and manganese is greater than 99%.

7. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S4, the molar ratio of ammonium oxalate to cobalt in the primary leaching solution containing lithium cobalt manganese is 1:(1~1.5), the centrifugation speed is 8000~12000 rpm, the centrifugation time is 5~20 min, and the calcination time is 1~3 h.

8. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S5, the centrifugation speed is 8000~12000 rpm, the centrifugation time is 5~20 min, and the calcination time is 1~3 h.

9. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S6, the molar ratio of soda ash to lithium is 1:(1.15~1.2), the evaporation and concentration reaction temperature is 80~100℃, and the reaction time is 30~90min.

10. The method for recovering valuable metals from waste lithium battery black powder based on a eutectic solvent according to claim 1, characterized in that: In step S7, the acid solution is one of sulfuric acid and hydrochloric acid or a mixture thereof, with a concentration of 0.5~2 mol / L; Graphite is washed with deionized water, dried at 80-120℃ for 2-6 hours, and then recycled for reuse. The precipitation reaction temperature is 30~80℃, and the reaction time is 60~240min; the precipitant is one or more of sodium hydroxide and oxalic acid.

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