Method for recovering metals in nickel cobalt lithium manganate positive plate

Abstract

The invention provides a method for recovering metals in a nickel cobalt lithium manganate positive plate. The method comprises the following steps: pre-treating the nickel cobalt lithium manganate positive plate disassembled from a battery to obtain positive powder; mixing the positive electrode powder and graphite, and performing high-temperature reduction reaction in an inert atmosphere to obtain a reduction product containing lithium carbonate; mixing the reduction product containing lithium carbonate with water, introducing excessive carbon dioxide for reaction, and filtering to obtain filter residues and leachate containing lithium ions; completely dissolving the filter residues in an acid solution, introducing carbon dioxide, ammonia gas and oxygen for reaction, and filtering to obtain ammonia leachate and MnCO3-containing filter residues; mixing the ammonia leaching solution with sulfonated kerosene, and extracting by taking Mextral 54-100 as an extracting agent to obtain a nickel-containing extracting solution and a cobalt-containing ammonia leaching solution; the nickel-containing extraction liquid is subjected to back extraction with H2SO4, and a nickel sulfate solution is obtained; and the cobalt-containing ammonia leachate is subjected to ammonia distillation to evaporate ammonia gas so as to separate out CoCO3. The recovery method can reduce the loss of lithium in recovery, and also can recover various metal ions.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and utilization of lithium-ion batteries, in particular to the recycling and utilization of positive electrode materials, and more particularly to a method for recycling various metals in nickel-cobalt-manganese-lithium positive electrode sheets. Background Art

[0002] With the rapid industrialization of new energy vehicles, their sales will soar, and the number of lithium-ion power batteries will also increase exponentially. At the same time, the environmental pollution problem and the reasonable resource recycling of waste lithium-ion power batteries have become a common concern in the industry and a problem that needs to be solved urgently. Solving this problem is not only conducive to environmental protection, but also conducive to the recycling of resources, and has great practical significance.

[0003] At present, the main materials recovered from waste 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. When recycling positive electrode active materials from waste batteries, there are usually three main steps: first, discharging the waste batteries and disassembling the pole pieces; second, separating the materials in the pole pieces from the current collectors; and third, recycling and utilizing the valuable metals.

[0004] Among them, various solution leaching processes are usually used in the recovery and utilization of valuable metals, such as acid leaching, alkaline leaching, ammonia leaching, etc. Ammonia leaching, as a wet leaching process, is selective for specific ions and has the advantage of better separation effect compared to conventional acid leaching and alkaline leaching processes. However, in the recycling process, if ammonia leaching is used directly on waste positive electrode powder, metallic lithium is often lost in the multi-step process after leaching, resulting in a low Li recovery rate. In addition, for ternary positive electrode materials, Ni and Co will be leached simultaneously in ammonia leaching, and there is a problem of difficulty in separating Ni and Co.

[0005] Therefore, how to separate and recycle the various valuable metals in the ternary positive electrode materials and reduce lithium loss is still a difficult problem that the industry needs to consider. Summary of the invention

[0006] Based on the above problems, the purpose of the present invention is to provide a method for recovering various metals in nickel-cobalt-manganese-lithium positive electrode sheets, which can reduce the loss of lithium during recovery and can also purify and recover various metal ions.

[0007] To achieve the above-mentioned purpose, the present invention provides a method for recovering various metals in a nickel-cobalt-manganese-oxide lithium positive electrode sheet. The method for recovering various metals in a nickel-cobalt-manganese-oxide lithium positive electrode sheet comprises:

[0008] (1) Preparation

[0009] The nickel-cobalt-manganese-oxide lithium positive electrode sheet disassembled from the battery is pre-treated to obtain positive electrode powder;

[0010] (2) Reduction reaction

[0011] The positive electrode powder and graphite are mixed and subjected to high temperature reduction reaction under an inert atmosphere to obtain a reduction product containing lithium carbonate;

[0012] (3) Lithium recovery

[0013] The reduction product containing lithium carbonate is mixed with water and an excess of carbon dioxide is introduced to react, and then filtered to obtain a filter residue and a leaching solution containing lithium ions;

[0014] (4) Ammonia leaching of manganese

[0015] The filter residue is completely dissolved in an acid solution, carbon dioxide, ammonia and oxygen are introduced into the solution for reaction, and then filtered to obtain an ammonia leaching solution and a filter residue containing MnCO3;

[0016] (5) Separation of cobalt and nickel

[0017] The ammonia leachate and sulfonated kerosene are mixed, and extraction is performed using 10 to 35% by volume of Mextral 54-100 as an extractant to obtain a nickel-containing extract and a cobalt-containing ammonia leachate;

[0018] (6) Nickel recovery

[0019] The nickel-containing extract is stripped using H2SO4 to obtain a nickel sulfate solution;

[0020] (7) Cobalt recovery

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

[0022] In the technical solution adopted by the present invention, the positive electrode powder and graphite are subjected to a high-temperature reduction reaction. The reduction effect of the graphite reduces the metals in the nickel-cobalt-manganese-lithium positive electrode sheet, and the final products are Li2CO3, MnO, NiO, CoO, Ni and Co. After mixing with water, Li2CO3 slowly dissolves, but under the action of excess CO2, LiHCO3 is generated and directly dissolved in water, but other metals are insoluble in water. Li can be separated in the form of water leachate by solid-liquid separation, and other metals are obtained in the form of filter residues, thereby separating Li before ammonia leaching, avoiding the loss of Li in subsequent steps. The filter residue is dissolved in an acid solution, and CO2, NH3 and O2 are introduced to react. Ammonia in the reaction system is in the form of NH3·H2O - (NH4)2CO3 exists, 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 a 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 Mextral 54-100 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 it 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 a closed-loop of ammonia utilization. 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 realized.

[0023] As a technical solution of the present invention, the lithium nickel cobalt manganese oxide cathode sheet includes a cathode active material, a binder, and a conductive agent. The chemical formula of the cathode 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 cathode 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 and 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 realize 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, 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. 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 a solvent and coated on a cathode current collector and dried, rolled, etc. to obtain a cathode sheet.

[0035] The method for recovering various metals in the nickel-cobalt-lithium manganese oxide positive electrode sheet of the present invention comprises the following steps.

[0036] (1) Preparation

[0037] The nickel-cobalt-manganese-oxide lithium positive electrode sheets disassembled from the battery are pre-treated to obtain positive electrode powder.

[0038] (2) Reduction reaction

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

[0040] (3) Lithium recovery

[0041] The reduction product containing lithium carbonate is mixed with water and an excess of carbon dioxide is introduced to react, and then filtered to obtain a filter residue and a leaching solution containing lithium ions.

[0042] (4) Ammonia leaching of manganese

[0043] The filter residue is completely dissolved in an acid solution, carbon dioxide, ammonia and oxygen are introduced to react, and then filtered to obtain an ammonia leaching solution and a filter residue containing MnCO3.

[0044] (5) Separation of cobalt and nickel

[0045] The ammonia leaching solution and sulfonated kerosene are mixed, and extraction is performed using Mextral 54-100 as an extractant to obtain a nickel-containing extract and a cobalt-containing ammonia leaching solution.

[0046] (6) Nickel recovery

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

[0048] (7) Cobalt recovery

[0049] The ammonia leaching solution containing cobalt is subjected to an ammonia distillation process to evaporate ammonia, precipitate CoCO3 and recover ammonia.

[0050] Briefly, the recovery process of the method for recovering each metal in the nickel-cobalt-manganese-lithium oxide positive electrode sheet of the present invention is as follows: Figure 1 As shown, waste nickel-cobalt-manganese-lithium-based positive electrode powder and graphite are mixed, reduced and roasted, and then dissolved in water. Carbon dioxide is introduced to obtain lithium bicarbonate filtrate. After acid is added for acid dissolution, carbon dioxide, ammonia and oxygen are introduced for ammonia leaching to obtain manganese carbonate filtrate. Mextral54-100 is used for extraction, the extracted phase is back-extracted to obtain nickel sulfate, and the non-extracted phase is subjected to ammonia distillation to obtain cobalt carbonate, and the ammonia obtained by ammonia distillation can be reused for ammonia leaching.

[0051] Wherein, the pretreatment of the preparation in step (1) includes crushing, organic acid soaking, inorganic acid soaking or inorganic alkali soaking. The crushing can be mechanical crushing or ultrasound-assisted separation. The positive electrode powder obtained by crushing includes positive electrode active material, binder, conductive agent and current collector. This recovery method will cause the positive electrode current collector (aluminum foil) to be crushed and destroyed, resulting in debris, making subsequent separation and material purification and recovery difficult. The solution soaking method of organic acid soaking, inorganic acid soaking or inorganic alkali soaking is to use a solvent to dissolve or disperse, separate the positive electrode active material and the binder and current collector, and the obtained powder is mainly positive electrode active material and conductive agent. The pretreatment is preferably organic acid soaking. During the organic acid soaking process, H + By reacting with the oxide layer on the surface of the positive electrode current collector, the contact interface between the membrane in the electrode sheet (formed by coating the positive electrode active material, the conductive agent and the binder into a slurry and then drying) and the positive electrode current collector can be destroyed, and the electrode material and the current collector can be separated. 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. At the same time, compared with inorganic acids with strong acidity such as sulfuric acid, hydrochloric acid and nitric acid, the acidity of organic acids tends to be mild, and the post-treatment of related waste materials is simpler and the processing cost is lower. In addition, the organic acid remaining in the positive electrode material layer can be converted into carbon material in a high-temperature reduction reaction after acid leaching, so as to achieve recycling.

[0052] In the reduction reaction of step (2), the graphite is the negative electrode powder obtained by pre-treatment of the graphite-based negative electrode sheet disassembled from the battery. Since the graphite in the graphite-based negative electrode sheet disassembled from the battery itself has some stored Li metal, this process also achieves the purpose of recovering Li in the negative electrode. The recovery of graphite in the graphite-based negative electrode sheet can refer to the pulverization, organic acid immersion, inorganic acid immersion or inorganic alkali immersion method in the previous paragraph.

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

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

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

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

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

[0058] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0059] Example 1

[0060] This embodiment is a method for recovering various metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0061] (1) Preparation

[0062] Dismantle the waste ternary battery to obtain the nickel-cobalt-manganese-based lithium positive electrode sheet and the graphite negative electrode sheet, and dry them at 60°C for 10 hours to remove the electrolyte on the surface of the electrode sheet. Soak them in a 10wt.% citric acid aqueous solution until the positive electrode powder or the negative electrode powder is separated from the current collector and dried to obtain the nickel-cobalt-manganese-based lithium positive electrode powder and the graphite negative electrode powder.

[0063] (2) Reduction reaction

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

[0065] (3) Lithium recovery

[0066] The reduction product containing lithium carbonate is mixed with water (liquid-to-solid ratio is 10 L / kg) and an excess of carbon dioxide is introduced (the introduction rate of carbon dioxide is 1.0 L / min, and the introduction time is 3 h) to react, and then the filter residue and the leaching solution containing lithium ions are obtained by filtering.

[0067] (4) Ammonia leaching of manganese

[0068] The filter residue was completely dissolved in hydrochloric acid solution and the pH value of the system was controlled to be 3. The liquid-to-solid ratio of the mixed solution was 12 L / kg. Carbon dioxide, ammonia and oxygen were introduced and reacted at room temperature for 10 hours, and then filtered to obtain ammonia leaching solution and filter residue containing MnCO3.

[0069] (5) Separation of cobalt and nickel

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

[0071] (6) Nickel recovery

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

[0073] (7) Cobalt recovery

[0074] The cobalt-containing ammonia leaching solution is evaporated at 150°C to precipitate CoCO3.

[0075] In this embodiment, lithium, nickel, cobalt and manganese metals are recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate and nickel sulfate, respectively, and the calculated recovery rates are 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 is a method for recovering various metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0078] (1) Preparation

[0079] Dismantle the waste ternary battery to obtain the nickel-cobalt-manganese-based lithium positive electrode sheet and the graphite negative electrode sheet, and dry them at 70°C for 8 hours to remove the electrolyte on the surface of the electrode sheet. Soak them in an aqueous solution of 15wt.% oxalic acid until the positive electrode powder or the negative electrode powder is separated from the current collector and dried to obtain the nickel-cobalt-manganese-based lithium positive electrode powder and the graphite negative electrode powder.

[0080] (2) Reduction reaction

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

[0082] (3) Lithium recovery

[0083] The reduction product containing lithium carbonate was mixed with water (liquid-to-solid ratio of 15 L / kg) and an excess of carbon dioxide was introduced (the introduction rate of carbon dioxide was 0.8 L / min, and the introduction time was 2 h) for reaction, and then the filter residue and the leaching solution containing lithium ions were obtained by filtering.

[0084] (4) Ammonia leaching of manganese

[0085] The filter residue was completely dissolved in hydrochloric acid solution and the pH value of the system was controlled to be 3. The liquid-to-solid ratio of the mixed solution was 10 L / kg. Carbon dioxide, ammonia and oxygen were introduced and reacted at room temperature for 15 hours, and then filtered to obtain ammonia leaching solution and filter residue containing MnCO3.

[0086] (5) Separation of cobalt and nickel

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

[0088] (6) Nickel recovery

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

[0090] (7) Cobalt recovery

[0091] The cobalt-containing ammonia leaching solution is evaporated at 180°C to precipitate CoCO3.

[0092] In this embodiment, lithium, nickel, cobalt and manganese metals are recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate and nickel sulfate, respectively, and the calculated recovery rates are 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 is a method for recovering various metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0095] (1) Preparation

[0096] Dismantle the waste ternary battery to obtain the nickel-cobalt-manganese-based lithium positive electrode sheet and the graphite negative electrode sheet, and dry them at 90°C for 8 hours to remove the electrolyte on the surface of the electrode sheet. Soak them in a 12wt.% citric acid aqueous solution until the positive electrode powder or the negative electrode powder is separated from the current collector and dried to obtain the nickel-cobalt-manganese-based lithium positive electrode powder and the graphite negative electrode powder.

[0097] (2) Reduction reaction

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

[0099] (3) Lithium recovery

[0100] The reduction product containing lithium carbonate was mixed with water (liquid-to-solid ratio of 15 L / kg) and an excess of carbon dioxide was introduced (the introduction rate of carbon dioxide was 0.8 L / min, and the introduction time was 2 h) for reaction, and then the filter residue and the leaching solution containing lithium ions were obtained by filtering.

[0101] (4) Ammonia leaching of manganese

[0102] The filter residue was completely dissolved in hydrochloric acid solution and the pH value of the system was controlled to be 2. The liquid-to-solid ratio of the mixed solution was 10 L / kg. Carbon dioxide, ammonia and oxygen were introduced and reacted at room temperature for 15 hours, and then filtered to obtain ammonia leaching solution and filter residue containing MnCO3.

[0103] (5) Separation of cobalt and nickel

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

[0105] (6) Nickel recovery

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

[0107] (7) Cobalt recovery

[0108] The cobalt-containing ammonia leaching solution is evaporated at 160°C to precipitate CoCO3.

[0109] In this embodiment, lithium, nickel, cobalt and manganese metals are recovered in the form of lithium bicarbonate, manganese carbonate, nickel sulfate and nickel sulfate, respectively, and the calculated recovery rates are 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 is a method for recovering various metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0112] (1) Preparation

[0113] The waste ternary battery was disassembled to obtain the nickel-cobalt-manganese-oxide lithium positive electrode sheet, which was dried at 60°C for 10 hours to remove the electrolyte on the surface of the positive electrode sheet. The positive electrode sheet was soaked in an aqueous solution of 10wt.% citric acid until the positive electrode powder was separated from the positive electrode current collector and dried to obtain the nickel-cobalt-manganese-oxide lithium positive electrode powder.

[0114] (2) Ammonia leaching of manganese

[0115] The nickel cobalt manganese oxide lithium positive electrode powder is completely dissolved in the hydrochloric acid solution and the pH value of the system is controlled to be 3. The liquid-to-solid ratio of the mixed solution is 12L / kg. Carbon dioxide, ammonia and oxygen are introduced and reacted at room temperature for 10 hours, and then filtered to obtain an ammonia leaching solution and a filter residue containing MnCO3.

[0116] (3) Separation of cobalt and nickel

[0117] The ammonia leachate and sulfonated kerosene are mixed, and extraction is performed using Mextral 54-100 with a volume fraction of 25% as an extractant. The extraction phase ratio O / A is 3:1, and the extraction time is 50 minutes to obtain a nickel-containing extract, a cobalt-containing ammonia leachate and a lithium-containing aqueous phase. The aqueous phase and the organic phase are separated to separate lithium from cobalt and nickel.

[0118] (4) Nickel recovery

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

[0120] (5) Cobalt recovery

[0121] The cobalt-containing ammonia leaching solution is evaporated at 150°C to precipitate CoCO3.

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

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for recovering various metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet, characterized in that: include: (1) Preparation The nickel-cobalt-manganese-oxide lithium positive electrode sheet disassembled from the battery is pre-treated to obtain positive electrode powder; (2) Reduction reaction The positive electrode powder and graphite are mixed and subjected to high temperature reduction reaction under an inert atmosphere to obtain a reduction product containing lithium carbonate; (3) Lithium recovery The reduction product containing lithium carbonate is mixed with water and an excess of carbon dioxide is introduced to react, and then filtered to obtain a filter residue and a leaching solution containing lithium ions; (4) Ammonia leaching of manganese The filter residue is completely dissolved in an acid solution, carbon dioxide, ammonia and oxygen are introduced into the solution for reaction, and then filtered to obtain an ammonia leaching solution and a filter residue containing MnCO3; (5) Separation of cobalt and nickel The ammonia leachate and sulfonated kerosene are mixed, and extraction is performed using Mextral 54-100 as an extractant to obtain a nickel-containing extract and a cobalt-containing ammonia leachate; (6) Nickel recovery The nickel-containing extract is stripped using H2SO4 to obtain a nickel sulfate solution; (7) Cobalt recovery The ammonia leaching solution containing cobalt is subjected to an ammonia distillation process to evaporate ammonia, precipitate CoCO3 and recover ammonia.

2. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet 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 metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The pretreatment includes crushing, organic acid soaking, inorganic acid soaking or inorganic alkali soaking.

4. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The graphite is a negative electrode powder obtained by pre-treating a graphite negative electrode sheet disassembled from the battery.

5. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet 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., the time is 2 to 4 hours, and the inert atmosphere includes at least one of nitrogen, helium, neon and argon.

6. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The liquid-to-solid ratio of the reduction product containing lithium carbonate and the water after mixing is 8-20 L / kg, and the introduction rate of the carbon dioxide in the lithium recovery step (3) is 0.5-1.0 L / min, and the introduction time is 1-5 hours.

7. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The liquid-to-solid ratio of the filter residue and the acid solution after mixing is 6-15 L / kg, the acid solution is hydrochloric acid and the pH value of the system is controlled to be 2-4.

8. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The reaction in step (4) of leaching manganese with ammonia is carried out at room temperature and the reaction time is 5 to 20 hours.

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

10. The method for recovering metals in a nickel-cobalt-manganese-lithium oxide positive electrode sheet 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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