Methods for recovering various metals from lithium nickel cobalt manganese oxide cathode plates

Abstract

This invention provides a method for recovering various metals from lithium nickel cobalt manganese oxide (LCO) cathode sheets, comprising: pre-treating LCO cathode sheets disassembled from batteries to obtain cathode powder; mixing the cathode powder with graphite and performing a high-temperature reduction reaction under an inert atmosphere to obtain a lithium carbonate-containing reduction product; mixing the lithium carbonate-containing reduction product with water and reacting it by introducing excess carbon dioxide, followed by filtration to obtain filter residue and a lithium ion-containing leachate; completely dissolving the filter residue in an acid solution, reacting it by introducing carbon dioxide, ammonia, and oxygen, followed by filtration to obtain an ammonia leachate and a MnCO3-containing filter residue; mixing the ammonia leachate with sulfonated kerosene and extracting it using Mextral 54-100 as the extractant to obtain a nickel-containing extract and a cobalt-containing ammonia leachate; back-extracting the nickel-containing extract using H2SO4 to obtain a nickel sulfate solution; and evaporating the ammonia from the cobalt-containing ammonia leachate using an ammonia distillation process to precipitate CoCO3. This recovery method can reduce lithium loss during recovery and can also recover various metal ions.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery recycling and utilization technology, particularly to the recycling and utilization of cathode materials, and even more particularly to methods for recycling various metals in lithium nickel cobalt manganese oxide cathode sheets. Background Technology

[0002] With the rapid industrialization of new energy vehicles, their sales will surge, and the number of lithium-ion power batteries in use will also increase exponentially. At the same time, the environmental pollution caused by waste lithium-ion power batteries and the issue of their rational resource recycling have become pressing problems of widespread concern in the industry. Solving these problems will not only benefit environmental protection but also promote resource recycling, thus having significant practical implications.

[0003] Currently, the main materials recycled from spent lithium-ion batteries are negative electrode current collectors (commonly copper foil), positive electrode current collectors (commonly aluminum foil), positive electrode active materials, and negative electrode active materials. The recycling of positive electrode active materials from spent batteries typically involves three main steps: first, discharging the spent batteries and disassembling them to remove the electrodes; second, separating the materials from the current collectors; and third, recycling and utilizing valuable metals.

[0004] In the recycling and utilization of valuable metals, various solution leaching processes are commonly used, such as acid leaching, alkaline leaching, and ammonia leaching. Ammonia leaching, as a wet leaching process, has the advantage of better separation efficiency for specific ions compared to conventional acid and alkaline leaching processes due to its selectivity. However, in recycling processes, if ammonia leaching is used directly on waste cathode powder, lithium metal is often lost in subsequent processing steps, resulting in a low Li recovery rate. Furthermore, for ternary cathode materials, Ni and Co are leached simultaneously in ammonia leaching, presenting difficulties in separating Ni and Co.

[0005] Therefore, how to separate and recycle the valuable metals of ternary cathode materials and reduce lithium loss remains a difficult problem that the industry needs to consider. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide a method for recovering various metals in lithium nickel cobalt manganese oxide cathode sheets. This recovery method can reduce the loss of lithium in the recovery process and can also purify and recover various metal ions.

[0007] To achieve the above objectives, this invention provides a method for recovering various metals from lithium nickel cobalt manganese oxide cathode sheets. The method for recovering various metals from lithium nickel cobalt manganese oxide cathode sheets includes:

[0008] (1) Material preparation

[0009] The lithium nickel cobalt manganese oxide cathode sheet removed from the battery is pretreated to obtain cathode powder;

[0010] (2) Reduction reaction

[0011] The cathode powder and graphite were mixed and subjected to a high-temperature reduction reaction under an inert atmosphere to obtain a lithium carbonate-containing reduction product.

[0012] (3) Lithium recovery

[0013] The lithium carbonate-containing reduction product was mixed with water and reacted by passing excess carbon dioxide through it. The mixture was then filtered to obtain filter residue and a lithium ion-containing leachate.

[0014] (4) Manganese leached from ammonia

[0015] The filter residue was completely dissolved in an acid solution, and after reacting with carbon dioxide, ammonia and oxygen, it was filtered to obtain an ammonia leachate and a filter residue containing MnCO3.

[0016] (5) Separation of cobalt and nickel

[0017] The ammonia leachate and sulfonated kerosene were mixed and extracted with Mextral 54-100 at a volume fraction of 10-35% to obtain a nickel-containing extract and a cobalt-containing ammonia leachate.

[0018] (6) Recycling nickel

[0019] The nickel-containing extract was back-extracted using H2SO4 to obtain a nickel sulfate solution;

[0020] (7) Cobalt recycling

[0021] The cobalt-containing ammonia leaching solution is subjected to an ammonia distillation process to evaporate the ammonia gas, precipitate CoCO3, and recover the ammonia gas.

[0022] In this invention, the cathode powder and graphite undergo a high-temperature reduction reaction. The reduction of graphite reduces the metals in the lithium nickel cobalt manganese oxide cathode, resulting in Li₂CO₃, MnO, NiO, CoO, Ni, and Co. Upon mixing with water, Li₂CO₃ slowly dissolves, but under the action of excess CO₂, it generates LiHCO₃, which dissolves directly in water. The other metals are insoluble in water. Through solid-liquid separation, Li is separated as an aqueous leachate, while the other metals are obtained as filter residue. This allows Li to be separated before ammonia leaching, avoiding loss in subsequent steps. The filter residue is dissolved in an acid solution, and CO₂, NH₃, and O₂ are introduced to initiate the reaction. Ammonia in the reaction system is converted to NH₃·H₂O. - Ni exists in the form of (NH4)2CO3, and dissolved Ni 2+ and oxidized Co 3+Complex with ammonia to form [Ni(NH3)6] 2+ and [Co(NH3)6] 3+ dissolve in the system in the form of complex ions. Since Mn 2 + does not complex with ammonia and directly reacts with CO3 2- to form MnCO3 precipitate. Through solid-liquid separation, Mn metal can be separated from the ammonia leaching solution in the form of MnCO3 filter residue. Through the extraction reaction with Mextral54-100 extractant, the "H" on the enol hydroxyl group of the extractant exchanges with Ni, and the "O" on the carbonyl group complexes with Ni to form a stronger complex form. Therefore, Ni in the ammonia leaching solution will be extracted into the extractant, thus separating from Co in the ammonia leaching solution. Through the back-extraction with H2SO4, a nickel sulfate solution can be obtained to separate and recover nickel. NH3 is evaporated through the ammonia distillation process, and Co in the ammonia leaching solution containing Co precipitates in the form of CoCO3 crystals. The evaporated NH3 can be recycled to the ammonia leaching step, thus realizing the closed-loop utilization of ammonia. Therefore, through the above process, the separation and purification of Li, Ni, Co, and Mn in the waste lithium nickel cobalt manganese oxide cathode sheet are achieved.

[0023] As a technical solution of the present invention, the lithium nickel cobalt manganese oxide cathode sheet includes a positive electrode active material, a binder, and a conductive agent. The chemical formula of the positive electrode active material is LiNi x Co y Mn z M (1-x-y-z) O2, where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF, and the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

[0024] As a technical solution of the present invention, the pretreatment includes crushing, soaking with organic acid, soaking with inorganic acid, or soaking with inorganic base.

[0025] As a technical solution of the present invention, the graphite is the negative electrode powder obtained by pretreating the graphite-based negative electrode sheet disassembled from the battery.

[0026] As a technical solution of the present invention, the weight ratio of the positive electrode powder to the graphite is 3 - 9:1. The temperature of the high-temperature reduction reaction is 600 - 800 °C, and the time is 2 - 4 h. The inert atmosphere includes at least one of nitrogen, helium, neon, and argon.

[0027] As a technical solution of the present invention, the liquid-solid ratio after mixing the lithium carbonate-containing reduction product with the water is 8-20 L / kg, and the feeding rate of the carbon dioxide in the recovery of lithium in step (3) is 0.5-1.0 L / min, and the feeding time is 1-5 h.

[0028] As a technical solution of the present invention, it is characterized in that the liquid-solid ratio after mixing the filter residue with the acid solution is 6-15 L / kg, the acid solution is hydrochloric acid, and the pH value of the system is controlled to be 2-4.

[0029] As a technical solution of the present invention, in the ammonia leaching of manganese in step (4), the reaction is carried out at room temperature and the reaction time is 5-20 h.

[0030] As a technical solution of the present invention, the extraction phase ratio O / A of the extraction is 2-4:1, the extraction time is 20-60 min, and the volume fraction of Mextral 54-100 is 10-35%.

[0031] As a technical solution of the present invention, the concentration of H2SO4 is 10-30 g / L, and the temperature of the ammonia distillation process is 120-180 °C. Description of the Drawings

[0032] Figure 1 It is a flow chart of the method for recovering each metal in the lithium nickel cobalt manganese oxide-based cathode sheet of the present invention. Detailed Embodiments

[0033] The present invention provides a method for recovering each metal in a lithium nickel cobalt manganese oxide-based cathode sheet, which can achieve the separation and purification of Li, Ni, Co and Mn.

[0034] The lithium nickel cobalt manganese oxide-based cathode sheet of the present invention refers to a cathode sheet containing a lithium nickel cobalt manganese oxide-based cathode active material. The lithium nickel cobalt manganese oxide-based cathode sheet includes a cathode active material, a binder and a conductive agent. The cathode active material includes a lithium nickel cobalt manganese oxide-based cathode active material, and its chemical formula is LiNi x Co y Mn z M (1-x-y-z) O2, wherein M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF. The conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube and graphene. The mass ratio of the cathode active material, the binder and the conductive agent can be but is not limited to 85-98:0.5-3.0:0.5-3.0. The cathode active material, the binder and the conductive agent are made into a slurry by using a solvent and coated on the cathode current collector and dried, rolled, etc. to obtain the cathode sheet.

[0035] The method for recovering various metals in the lithium nickel cobalt manganese oxide cathode of the present invention includes the following steps.

[0036] (1) Material preparation

[0037] The lithium nickel cobalt manganese oxide cathode sheet removed from the battery is pretreated to obtain cathode powder.

[0038] (2) Reduction reaction

[0039] The cathode powder and graphite were mixed and subjected to a high-temperature reduction reaction under an inert atmosphere to obtain a lithium carbonate-containing reduction product.

[0040] (3) Lithium recovery

[0041] The lithium carbonate reduction product was mixed with water and reacted by passing excess carbon dioxide through the mixture. The mixture was then filtered to obtain filter residue and a lithium ion-containing leachate.

[0042] (4) Manganese leached from ammonia

[0043] The filter residue was completely dissolved in an acid solution, and carbon dioxide, ammonia and oxygen were introduced to react. After filtration, ammonia leachate and filter residue containing MnCO3 were obtained.

[0044] (5) Separation of cobalt and nickel

[0045] The ammonia leachate and sulfonated kerosene were mixed and extracted with Mextral 54-100 as the extractant to obtain a nickel-containing extract and a cobalt-containing ammonia leachate.

[0046] (6) Recycling nickel

[0047] The nickel-containing extract was back-extracted using H2SO4 to obtain a nickel sulfate solution.

[0048] (7) Cobalt recycling

[0049] The ammonia gas in the cobalt-containing ammonia leaching solution is evaporated by ammonia distillation to precipitate CoCO3 and recover the ammonia gas.

[0050] Briefly, the recovery process of the method for recovering various metals in the lithium nickel cobalt manganese oxide cathode of the present invention is as follows: Figure 1 As shown, waste nickel-cobalt-manganese lithium oxide cathode powder is mixed with graphite, reduced and roasted, and then dissolved in water. Carbon dioxide is passed through to obtain lithium bicarbonate filtrate. After acid dissolution, carbon dioxide, ammonia and oxygen are passed through to leach ammonia to obtain manganese carbonate filter residue. Mextral 54-100 is used for extraction. The extracted phase is back-extracted to obtain nickel sulfate, and the non-extracted phase is distilled with ammonia to obtain cobalt carbonate. The ammonia obtained from the ammonia distillation can be reused for ammonia leaching.

[0051] The pretreatment of materials in step (1) includes crushing, organic acid soaking, inorganic acid soaking, or inorganic alkali soaking. Crushing can be mechanical crushing or ultrasonic-assisted separation. The positive electrode powder obtained by crushing includes positive electrode active material, binder, conductive agent, and current collector. This recycling method will cause the positive electrode current collector (aluminum foil) to be crushed and destroyed, generating debris, which will make subsequent separation and material purification and recovery difficult. The solution soaking method of organic acid soaking, inorganic acid soaking, or inorganic alkali soaking uses a solvent to dissolve or disperse the positive electrode active material, binder, and current collector. The obtained powder is mainly positive electrode active material and conductive agent. The preferred pretreatment is organic acid soaking. During the organic acid soaking process, H + Reacting with the oxide layer on the surface of the positive electrode current collector, the contact interface between the film (formed by coating and drying a slurry of positive electrode active material, conductive agent, and binder) and the positive electrode current collector can be disrupted, achieving separation of the electrode material from the current collector. The organic acid can be, but is not limited to, at least one of tartaric acid, oxalic acid, malic acid, citric acid, acetic acid, ascorbic acid, and benzoic acid. Furthermore, compared to strongly acidic inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, organic acids are milder, making the post-treatment of related waste simpler and less costly. Additionally, the organic acids remaining in the positive electrode material layer after acid leaching can be converted into carbon materials through a high-temperature reduction reaction, enabling recycling.

[0052] In step (2) the reduction reaction, the graphite is the negative electrode powder obtained by pre-processing graphite-based negative electrode sheets disassembled from the battery. Since the graphite in the graphite-based negative electrode sheets disassembled from the battery itself contains some stored Li metal, this process also achieves the purpose of recovering Li from the negative electrode. The recovery of graphite in the graphite-based negative electrode sheets can refer to the crushing, organic acid soaking, inorganic acid soaking, or inorganic alkali soaking methods described in the previous section.

[0053] In the high-temperature reduction reaction, the weight ratio of cathode powder to graphite is 3–9:1. For example, the weight ratio can be, but is not limited to, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or 9:1. The temperature of the high-temperature reduction reaction is 600–800℃. For example, it can be, but is not limited to, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃, 760℃, 780℃, or 800℃. The time of the high-temperature reduction reaction is 2–4 hours. For example, it can be, but is not limited to, 2 hours, 3 hours, or 4 hours. The inert atmosphere includes at least one of nitrogen, helium, neon, and argon. In the high-temperature reduction reaction, carbonaceous materials can be sintered and converted into carbon, thus accelerating the reduction reaction.

[0054] In step (3) lithium recovery, the liquid-to-solid ratio of the lithium carbonate reduction product mixed with water is 8–20 L / kg. For example, the liquid-to-solid ratio can be, but is not limited to, 8 L / kg, 10 L / kg, 12 L / kg, 14 L / kg, 16 L / kg, 18 L / kg, or 20 L / kg. The carbon dioxide introduction rate is 0.5–1.0 L / min. For example, the introduction rate can be, but is not limited to, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, or 1.0 L / min. The carbon dioxide introduction time is 1–5 h. For example, the introduction time can be, but is not limited to, 1 h, 2 h, 3 h, 4 h, or 5 h.

[0055] In step (4) of manganese leaching with ammonia, the liquid-to-solid ratio of the mixture of filter residue and acid solution is 6–15 L / kg. For example, the liquid-to-solid ratio can be, but is not limited to, 6 L / kg, 7 L / kg, 8 L / kg, 9 L / kg, 10 L / kg, 11 L / kg, 12 L / kg, 13 L / kg, 14 L / kg, or 15 L / kg. The carbon dioxide introduction rate is 0.5–1.0 L / min. For example, the introduction rate can be, but is not limited to, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.8 L / min, 0.9 L / min, or 1.0 L / min. The acid solution is hydrochloric acid, and the pH of the system is controlled to be 2–4. Ammonia leaching is carried out at room temperature, and the reaction time is 5–20 h. For example, the ammonia leaching time can be, but is not limited to, 5 h, 7 h, 9 h, 10 h, 12 h, 14 h, 16 h, 18 h, or 20 h. Sufficient amounts of carbon dioxide, ammonia, and oxygen are required to ensure a complete reaction.

[0056] In step (5) for separating cobalt and nickel, the extraction ratio (O / A) is 2–4:1, but not limited to 2:1, 3:1, or 4:1. The extraction time is 20–60 min, but not limited to 20, 25, 30, 35, 40, 45, 50, 55, or 60 min. The volume fraction of Mextral 54-100 is 10–35%, but not limited to 10%, 15%, 20%, 25%, 30%, or 35%.

[0057] In step (6) of nickel recovery, the concentration of H2SO4 is 10-30 g / L. For example, the concentration of H2SO4 can be, but is not limited to, 10 g / L, 15 g / L, 20 g / L, 25 g / L, or 30 g / L. The temperature of the ammonia distillation process is 120-180℃. For example, the temperature can be, but is not limited to, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃, or 180℃.

[0058] To better illustrate the purpose, technical solution, and beneficial effects of this invention, the invention will be further described below with reference to specific embodiments. It should be noted that the methods described below are further explanations of this invention and should not be construed as limiting it.

[0059] Example 1

[0060] This embodiment describes a method for recovering various metals from lithium nickel cobalt manganese oxide cathode sheets, and the steps are as follows.

[0061] (1) Material preparation

[0062] A discarded ternary lithium battery was disassembled to obtain lithium nickel cobalt manganese oxide positive electrode sheets and graphite negative electrode sheets. Both were dried at 60°C for 10 hours to remove the electrolyte from the electrode surface. The electrodes were then soaked in a 10 wt.% citric acid aqueous solution until the positive or negative electrode powder detached from the current collector. The resulting powders were then dried to obtain lithium nickel cobalt manganese oxide positive electrode powder and graphite negative electrode powder.

[0063] (2) Reduction reaction

[0064] The positive electrode powder and the negative electrode powder (weight ratio 6:1) were mixed and subjected to a high-temperature reduction reaction at 750°C for 3 hours under a nitrogen atmosphere to obtain a lithium carbonate-containing reduction product.

[0065] (3) Lithium recovery

[0066] The lithium carbonate reduction product was mixed with water (liquid-to-solid ratio of 10 L / kg) and then an excess of carbon dioxide was introduced (carbon dioxide introduction rate of 1.0 L / min, introduction time of 3 h) to react. The mixture was then filtered to obtain filter residue and lithium ion-containing leachate.

[0067] (4) Manganese leached from ammonia

[0068] The filter residue was completely dissolved in hydrochloric acid solution while controlling the pH of the system to 3. The liquid-to-solid ratio of the mixed solution was 12 L / kg. Carbon dioxide, ammonia, and oxygen were introduced and the reaction was carried out at room temperature for 10 h. After filtration, ammonia leachate and filter residue containing MnCO3 were obtained.

[0069] (5) Separation of cobalt and nickel

[0070] The ammonia leachate and sulfonated kerosene were mixed and extracted with 25% Mextral 54-100 by volume as the extractant. The extraction ratio O / A was 3:1 and the extraction time was 50 min to obtain a nickel-containing extract and a cobalt-containing ammonia leachate.

[0071] (6) Recycling nickel

[0072] The nickel-containing extract was back-extracted with 20 g / L H2SO4 to obtain a nickel sulfate solution.

[0073] (7) Cobalt recycling

[0074] CoCO3 is produced by evaporating ammonia gas from a cobalt-containing ammonia leachate at 150°C.

[0075] In this embodiment, lithium, nickel, cobalt, and manganese metals were recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate, and nickel sulfate, respectively, and the calculated recovery rates were 97.6%, 94.2%, 91.6%, and 95.6%, respectively, indicating that the recovery rates of lithium, nickel, cobalt, and manganese obtained by the recovery method of the present invention are relatively high.

[0076] Example 2

[0077] This embodiment describes a method for recovering various metals from lithium nickel cobalt manganese oxide cathode sheets, and the steps are as follows.

[0078] (1) Material preparation

[0079] A discarded ternary lithium battery was disassembled to obtain lithium nickel cobalt manganese oxide positive electrode sheets and graphite negative electrode sheets. Both were dried at 70°C for 8 hours to remove the electrolyte from the electrode surface. The electrodes were then soaked in a 15 wt.% oxalic acid aqueous solution until the positive or negative electrode powder detached from the current collector. The resulting powders were then dried to obtain lithium nickel cobalt manganese oxide positive electrode powder and graphite negative electrode powder.

[0080] (2) Reduction reaction

[0081] The positive electrode powder and the negative electrode powder (weight ratio 8:1) were mixed and subjected to a high-temperature reduction reaction at 650°C for 4 hours under a nitrogen atmosphere to obtain a lithium carbonate-containing reduction product.

[0082] (3) Lithium recovery

[0083] The lithium carbonate reduction product was mixed with water (liquid-to-solid ratio of 15 L / kg) and then an excess of carbon dioxide was introduced (carbon dioxide introduction rate of 0.8 L / min, introduction time of 2 h) to react. The mixture was then filtered to obtain filter residue and lithium ion-containing leachate.

[0084] (4) Manganese leached from ammonia

[0085] The filter residue was completely dissolved in hydrochloric acid solution while controlling the pH of the system to 3. The liquid-to-solid ratio of the mixed solution was 10 L / kg. Carbon dioxide, ammonia, and oxygen were introduced and the reaction was carried out at room temperature for 15 h. After filtration, ammonia leachate and filter residue containing MnCO3 were obtained.

[0086] (5) Separation of cobalt and nickel

[0087] The ammonia leachate and sulfonated kerosene were mixed and extracted with 30% Mextral 54-100 by volume as the extractant. The extraction ratio O / A was 4:1 and the extraction time was 35 min to obtain a nickel-containing extract and a cobalt-containing ammonia leachate.

[0088] (6) Recycling nickel

[0089] The nickel-containing extract was back-extracted with H2SO4 at a concentration of 25 g / L to obtain a nickel sulfate solution.

[0090] (7) Cobalt recycling

[0091] CoCO3 is produced by evaporating ammonia gas from a cobalt-containing ammonia leachate at 180°C.

[0092] In this embodiment, lithium, nickel, cobalt, and manganese metals were recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate, and nickel sulfate, respectively, and the calculated recovery rates were 95.6%, 93.2%, 92.1%, and 94.1%, respectively, indicating that the recovery rates of lithium, nickel, cobalt, and manganese obtained by the recovery method of the present invention are relatively high.

[0093] Example 3

[0094] This embodiment describes a method for recovering various metals from lithium nickel cobalt manganese oxide cathode sheets, and the steps are as follows.

[0095] (1) Material preparation

[0096] A discarded ternary lithium battery was disassembled to obtain lithium nickel cobalt manganese oxide positive electrode sheets and graphite negative electrode sheets. Both were dried at 90°C for 8 hours to remove the electrolyte from the electrode surface. The electrodes were then soaked in a 12 wt.% citric acid aqueous solution until the positive or negative electrode powder detached from the current collector and dried to obtain lithium nickel cobalt manganese oxide positive electrode powder and graphite negative electrode powder, respectively.

[0097] (2) Reduction reaction

[0098] The positive electrode powder and the negative electrode powder (weight ratio 8:1) were mixed and subjected to a high-temperature reduction reaction at 700°C for 4 hours under a nitrogen atmosphere to obtain a lithium carbonate-containing reduction product.

[0099] (3) Lithium recovery

[0100] The lithium carbonate reduction product was mixed with water (liquid-to-solid ratio of 15 L / kg) and then an excess of carbon dioxide was introduced (carbon dioxide introduction rate of 0.8 L / min, introduction time of 2 h) to react. The mixture was then filtered to obtain filter residue and lithium ion-containing leachate.

[0101] (4) Manganese leached from ammonia

[0102] The filter residue was completely dissolved in hydrochloric acid solution while controlling the pH of the system to 2. The liquid-to-solid ratio of the mixed solution was 10 L / kg. Carbon dioxide, ammonia, and oxygen were introduced and the reaction was carried out at room temperature for 15 h. After filtration, ammonia leachate and filter residue containing MnCO3 were obtained.

[0103] (5) Separation of cobalt and nickel

[0104] The ammonia leachate and sulfonated kerosene were mixed and extracted with 30% Mextral 54-100 by volume as the extractant. The extraction ratio O / A was 4:1 and the extraction time was 60 min to obtain a nickel-containing extract and a cobalt-containing ammonia leachate.

[0105] (6) Recycling nickel

[0106] The nickel-containing extract was back-extracted with H2SO4 at a concentration of 25 g / L to obtain a nickel sulfate solution.

[0107] (7) Cobalt recycling

[0108] CoCO3 is produced by evaporating ammonia gas from a cobalt-containing ammonia leachate at 160°C.

[0109] In this embodiment, lithium, nickel, cobalt, and manganese metals were recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate, and nickel sulfate, respectively, and the calculated recovery rates were 96.6%, 93.2%, 93.6%, and 96.0%, respectively, indicating that the recovery rates of lithium, nickel, cobalt, and manganese obtained by the recovery method of the present invention are relatively high.

[0110] Comparative Example 1

[0111] This comparative example demonstrates a method for recovering various metals from lithium nickel cobalt manganese oxide cathode sheets, and the steps are as follows.

[0112] (1) Material preparation

[0113] Lithium nickel cobalt manganese oxide (NiCoMnO) cathode sheets were disassembled from a waste ternary battery and dried at 60°C for 10 hours to remove the electrolyte from the surface of the cathode sheets. The cathode powder was then soaked in a 10 wt.% citric acid aqueous solution until it detached from the cathode current collector and dried to obtain NiCoMnO cumulonic acid (NiCoMnO) cathode powder.

[0114] (2) Manganese leached from ammonia

[0115] The lithium nickel cobalt manganese oxide cathode powder was completely dissolved in hydrochloric acid solution with the pH value of the system controlled at 3. The liquid-to-solid ratio of the mixed solution was 12 L / kg. Carbon dioxide, ammonia and oxygen were introduced and the reaction was carried out at room temperature for 10 h. After filtration, ammonia leachate and filter residue containing MnCO3 were obtained.

[0116] (3) Separation of cobalt and nickel

[0117] Ammonia leachate and sulfonated kerosene were mixed and extracted with 25% Mextral 54-100 by volume as the extractant. The extraction ratio O / A was 3:1 and the extraction time was 50 min to obtain a nickel-containing extract, a cobalt-containing ammonia leachate, and a lithium-containing aqueous phase. Lithium could be separated from cobalt and nickel by separating the aqueous phase and the organic phase.

[0118] (4) Recycling nickel

[0119] The nickel-containing extract was back-extracted with 20 g / L H2SO4 to obtain a nickel sulfate solution.

[0120] (5) Cobalt recycling

[0121] CoCO3 is produced by evaporating ammonia gas from a cobalt-containing ammonia leachate at 150°C.

[0122] In this comparative example, lithium, nickel, cobalt, and manganese metals were recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate, and nickel sulfate, respectively, and the calculated recovery rates were 81.5%, 91.6%, 92.5%, and 96.7%, respectively. This indicates that the lithium recovery rate obtained by the recovery method of this invention is not high. This is because some lithium will precipitate out in the form of Li2CO3 in step (2), resulting in a large loss.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for recovering various metals from a lithium nickel cobalt manganese oxide cathode, characterized in that, include: (1) Material preparation The lithium nickel cobalt manganese oxide cathode sheet removed from the battery is pre-treated to obtain cathode powder; (2) Reduction reaction The cathode powder and graphite were mixed and subjected to a high-temperature reduction reaction under an inert atmosphere to obtain a lithium carbonate-containing reduction product. (3) Lithium recovery The lithium carbonate-containing reduction product was mixed with water and reacted by passing excess carbon dioxide through it. The mixture was then filtered to obtain filter residue and a lithium ion-containing leachate. (4) Manganese leached from ammonia The filter residue was completely dissolved in an acid solution, and carbon dioxide, ammonia and oxygen were introduced to react. After filtration, ammonia leachate and filter residue containing MnCO3 were obtained. (5) Separation of cobalt and nickel The ammonia leachate and sulfonated kerosene were mixed and extracted with Mextral 54-100 as the extractant to obtain a nickel-containing extract and a cobalt-containing ammonia leachate. (6) Recycling nickel The nickel-containing extract was back-extracted using H2SO4 to obtain a nickel sulfate solution; (7) Cobalt recycling The cobalt-containing ammonia leaching solution is subjected to an ammonia distillation process to evaporate the ammonia gas, precipitate CoCO3, and recover the ammonia gas.

2. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The lithium nickel cobalt manganese oxide-based positive electrode sheet includes a positive electrode active material, a binder, and a conductive agent. The chemical formula of the positive electrode active material is LiNi x Co y Mn z M (1-x-y-z) O2, where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z ≤ 1. The binder includes PVDF, and the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

3. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The pretreatment includes crushing, soaking in organic acid, soaking in inorganic acid, or soaking in inorganic alkali.

4. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The graphite is negative electrode powder obtained by pre-processing graphite-based negative electrode sheets disassembled from the battery.

5. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The weight ratio of the positive electrode powder to the graphite is 3 to 9:1, the temperature of the high-temperature reduction reaction is 600 to 800°C, and the time is 2 to 4 hours. The inert atmosphere includes at least one of nitrogen, helium, neon, and argon.

6. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The liquid-to-solid ratio of the lithium carbonate reduction product mixed with the water is 8-20 L / kg. The carbon dioxide in the lithium recovery process in step (3) is introduced at a rate of 0.5-1.0 L / min for 1-5 h.

7. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The liquid-to-solid ratio of the mixture of the filter residue and the acid solution is 6-15 L / kg, and the acid solution is hydrochloric acid with the pH value of the system controlled at 2-4.

8. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The reaction in step (4) of ammonia leaching manganese is carried out at room temperature for 5 to 20 hours.

9. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The extraction ratio O / A is 2-4:1, the extraction time is 20-60 min, and the volume fraction of Mextral 54-100 is 10-35%.

10. The method for recovering various metals from a lithium nickel cobalt manganese oxide cathode according to claim 1, characterized in that, The concentration of H2SO4 is 10–30 g / L, and the temperature of the ammonia distillation process is 120–180 °C.

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