Method for recovering and separating graphite and valuable metals in waste batteries

Abstract

The invention relates to the technical field of recovery of graphite and valuable metals in waste batteries, in particular to a method for recovering and separating graphite and valuable metals in waste batteries, so that high-efficiency, high-purity and low-cost recovery of graphite and valuable metals is realized, and effective resource utilization of the waste batteries is improved. The invention discloses a method for recycling and separating graphite and valuable metals in a waste battery. The method comprises the following steps: mixing plastic with a graphite material to be recycled; soaking the mixture with an oxidizing agent solution and an alkaline solution; carrying out pyrolysis on the soaked mixture; washing the pyrolyzed product with water; introducing carbon dioxide into the washed alkaline aqueous phase solution to prepare lithium carbonate; carrying out acid leaching treatment on the oil phase solution and the graphite pyrolysis product; adjusting the pH value of the acidic aqueous phase solution subjected to acid leaching treatment; carrying out extraction, back extraction and evaporative crystallization on the cobalt salt and the nickel salt in the water-phase solution after pH adjustment; and sintering the oil-phase graphite to prepare the carbon-coated graphite material.

Description

Technical Field

[0001] This application relates to the field of graphite and valuable metal recycling technology in waste batteries, and in particular to a method for recycling and separating graphite and valuable metals in waste batteries. Background Technology

[0002] With the development of battery technology and the increasing level of electricity consumption, the demand and production of batteries have increased significantly, which will inevitably generate a large number of waste batteries.

[0003] Currently, people are focusing on how to recycle graphite from waste batteries. Graphite also contains a small amount of valuable metals. In related technologies, there are problems such as low recovery rate, complex process and high cost when recycling valuable metals from graphite.

[0004] Therefore, how to achieve efficient, high-purity, and low-cost recycling of graphite and valuable metals has become an urgent technical problem to be solved. Summary of the Invention

[0005] Based on this, some embodiments of this application provide a method for recycling and separating graphite and valuable metals from waste batteries, so as to achieve high-efficiency, high-purity and low-cost recycling of graphite and valuable metals, and improve the effective utilization of waste batteries as resources.

[0006] In a first aspect, a method for recycling and separating graphite and valuable metals from waste batteries is provided, comprising:

[0007] Provide plastics and recycled graphite material; wherein the recycled graphite material contains graphite, organic binders and valuable metals;

[0008] The plastic is mixed with the graphite material to be recycled to obtain a mixture;

[0009] The mixture is soaked in an oxidizing agent solution and an alkaline solution in sequence to oxidize the plastic and dissolve the valuable metals in the graphite to be recycled.

[0010] The soaked mixture is pyrolyzed to decompose the oxidized plastic into an oily solvent;

[0011] The pyrolysis products were washed with water and separated to obtain an alkaline aqueous solution, an oil solution, and graphite pyrolysis products, respectively.

[0012] Lithium carbonate is prepared by passing carbon dioxide into an alkaline aqueous solution.

[0013] The oil phase solution and graphite pyrolysis products were subjected to acid leaching treatment, and after phase separation, an acidic aqueous phase solution and an oil phase graphite were obtained.

[0014] The pH value of the acidic aqueous solution is adjusted to remove other valuable metal ions except for nickel and cobalt from the acidic aqueous solution, resulting in a first aqueous solution of cobalt salt and nickel salt.

[0015] Cobalt and nickel salts in the first aqueous solution were extracted and back-extracted sequentially using phosphonic acid extractant and sulfuric acid, and the second aqueous solution obtained after back-extraction was evaporated and crystallized to obtain cobalt sulfate and nickel sulfate.

[0016] Carbon-coated graphite materials are prepared by sintering oil-phase graphite under a protective atmosphere.

[0017] By adding plastic to the graphite to be recycled, and utilizing the characteristic that plastic can form an oily solvent through pyrolysis, the organic binder in the mixture can be dissolved, thus separating the binder from the graphite. Then, taking advantage of the immiscibility of the aqueous and oil phase solutions, lithium salts in the graphite can be dissolved in an alkaline aqueous solution. Passing carbon dioxide into the alkaline aqueous solution further separates the lithium ions. Subsequently, acid leaching of the oil phase solution and graphite pyrolysis products dissolves other valuable metal ions besides lithium ions. Utilizing the different precipitation order of valuable metal ions at different pH values, the acidic aqueous solution obtained after acid leaching can also remove other metal ions besides nickel and cobalt. Valuable metal ions are precipitated, thus separating cobalt and nickel salts. Then, by sequentially extracting and back-extracting the cobalt and nickel salts in the first aqueous solution using phosphonic acid extractants and sulfuric acid, aqueous solutions of cobalt sulfate and nickel sulfate are obtained. Further evaporation and crystallization yield high-purity cobalt sulfate and nickel sulfate, achieving the recovery and separation of cobalt and nickel salts. Simultaneously, by sintering the acid-leached oil-phase graphite, the oil-phase substances in the graphite are carbonized and coated onto the sintered graphite product, and the voids generated in the sintered graphite product are repaired. This improves the graphite recovery efficiency and the overall graphitization degree of the graphite, achieving effective resource utilization of graphite and enabling high-efficiency, high-purity, and low-cost recovery of valuable metals from graphite materials.

[0018] Optionally, the plastic satisfies at least one of the following conditions:

[0019] (1) The plastic is waste plastic;

[0020] (2) The particle size of the plastic is 100 mesh to 500 mesh;

[0021] (3) Plastics include at least one of polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA);

[0022] (4) The mass percentage of plastic in the mixture is 0.5% to 5%.

[0023] When the plastic is waste plastic, it can be recycled and reused, and graphite can be effectively utilized as a resource, thus achieving co-management of waste. When the plastic particle size is 100-500 mesh, it is easy for the plastic to be fully mixed with the graphite to be recycled, and it can improve the subsequent soaking and oxidation effects.

[0024] Optionally, the oxidant solution satisfies at least one of the following conditions:

[0025] (1) The oxidizing agent in the oxidizing agent solution includes at least one of sodium persulfate, hydrogen peroxide and sodium perchlorate;

[0026] (2) The mass concentration of the oxidant solution is 5%~30%;

[0027] (3) The soaking temperature of the oxidant solution is 20℃~30℃ and the soaking time is 15 min~60 min.

[0028] At least one of sodium persulfate, hydrogen peroxide, and sodium perchlorate is selected as the oxidant. When these oxidants react with plastics, they can cause the carbon chains in the plastics to break, thereby accelerating the decomposition of the plastics into oily solvents.

[0029] Optionally, the alkaline solution satisfies at least one of the following conditions:

[0030] (1) The base in the alkaline solution includes at least one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide;

[0031] (2) The concentration of the alkaline solution is 1 mol / L ~ 3 mol / L;

[0032] (3) The solid-liquid mass ratio for soaking in alkaline solution is 1:(2~5);

[0033] (4) The soaking temperature of the alkaline solution is 30℃~90℃ and the soaking time is 30min~120min.

[0034] Optionally, the pyrolysis temperature is 250℃~350℃, the pressure is 5MPa~10MPa, and the time is 10min~30min. By controlling the pyrolysis temperature and pressure, the plastic can be converted into an oily solvent.

[0035] Optionally, the mass ratio of water used for washing to the pyrolysis products is 1:(10~25). This can improve the washing effect, allowing lithium ions to be washed into the alkaline aqueous phase solution as much as possible in the alkaline solution.

[0036] Optionally, the molar amount of carbon dioxide introduced is 5 to 20 times the molar amount of lithium ions in the alkaline aqueous solution; and / or,

[0037] After introducing carbon dioxide, the recovery and separation method further includes: heating the alkaline aqueous solution after introducing carbon dioxide to prepare lithium carbonate; optionally, the heating temperature is 60℃~90℃ and the time is 30min~60min.

[0038] By controlling the amount of carbon dioxide introduced to be 5 to 20 times the molar amount of lithium in the alkaline aqueous solution, lithium ions in the alkaline aqueous solution can be converted into lithium carbonate and precipitated, thereby improving the recovery rate and purity of lithium ions.

[0039] Optionally, the acid leaching treatment satisfies at least one of the following conditions:

[0040] (1) The acid used in the acid leaching treatment includes at least one of sulfuric acid and hydrochloric acid;

[0041] (2) The concentration of the acid solution used in the acid leaching treatment is 10%~30% by mass;

[0042] (3) The liquid-to-solid mass ratio for acid leaching is 1:(5~15);

[0043] (4) The temperature of acid leaching treatment is 70℃~90℃ and the time is 30min~180min.

[0044] Optionally, the pH of the acidic aqueous solution is adjusted to remove other valuable metal ions besides nickel and cobalt from the acidic aqueous solution, resulting in a first aqueous solution of cobalt and nickel salts, comprising:

[0045] An alkaline substance is added to the acidic aqueous solution to adjust the pH value of the acidic aqueous solution to 4.5~5.0, so that other valuable metal ions in the acidic aqueous solution, except for nickel and cobalt, can be removed by precipitation in the form of hydroxides.

[0046] When the pH of the acidic aqueous solution is adjusted to 4.5-5.0, the copper, iron, manganese and aluminum ions in the acidic aqueous solution are converted into copper hydroxide, iron hydroxide, manganese hydroxide and aluminum hydroxide precipitates, respectively, thereby removing the copper, iron, manganese and aluminum ions, while retaining nickel ions and cobalt ions.

[0047] Optionally, the alkaline substance includes at least one of sodium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0048] Optionally, the sintering temperature is 600℃~1000℃, the pressure is 30 MPa~50 MPa, and the time is 10h~40h. Through high-temperature and high-pressure oxygen-free sintering, oil phase substances can be converted into amorphous carbon to coat the graphite pyrolysis products and fill the voids in the graphite pyrolysis products, thereby repairing the graphite and improving the overall graphitization degree of the graphite.

[0049] Compared with related technologies, this application has at least the following beneficial technical effects:

[0050] By adding plastic to the graphite to be recycled, and utilizing the characteristic that plastic can form an oily solvent through pyrolysis, the organic binder in the mixture can be dissolved, thus separating the binder from the graphite. Then, taking advantage of the immiscibility of the aqueous and oil phase solutions, lithium salts in the graphite can be dissolved in an alkaline aqueous solution. Passing carbon dioxide into the alkaline aqueous solution further separates the lithium ions. Subsequently, acid leaching of the oil phase solution and graphite pyrolysis products dissolves other valuable metals besides lithium ions. Utilizing the different precipitation order of valuable metal ions at different pH values, other metals besides nickel and cobalt can be extracted from the acidic aqueous solution obtained after acid leaching. Valuable metal ions are precipitated, thus separating cobalt and nickel salts. Next, the cobalt and nickel salts in the first aqueous solution are extracted and back-extracted sequentially using phosphonic acid extractants and sulfuric acid to obtain aqueous solutions of cobalt sulfate and nickel sulfate. These solutions are then obtained through evaporation and crystallization, yielding high-purity cobalt sulfate and nickel sulfate, thus achieving the recovery and separation of cobalt and nickel salts. Simultaneously, by sintering the acid-leached oil-phase graphite, the oil-phase substances in the graphite are carbonized and coated onto the sintered graphite product, and voids generated in the sintered product are repaired. This improves graphite recovery efficiency and overall graphitization, enabling the efficient resource utilization of graphite and achieving high-efficiency, high-purity, and low-cost recovery of valuable metals from graphite materials. Attached Figure Description

[0051] Figure 1 This is a schematic flowchart illustrating a method for recycling graphite and valuable metals from waste batteries, provided in an embodiment of this application. Detailed Implementation

[0052] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0054] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0056] In this application, "at least one" means any one, any two, or more of the listed items.

[0057] In this application, the terms "combinations thereof," "any combination thereof," and "any combination thereof" as used include all suitable combinations of any two or more of the listed items.

[0058] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0059] In this application, numerical ranges are involved, and unless otherwise specified, the two endpoints of the numerical range are included.

[0060] In this application, unless otherwise specified, percentage concentrations refer to final concentrations. The final concentration refers to the percentage of the added component in the system after its addition.

[0061] In this application, temperature parameters are involved. Unless otherwise specified, both isothermal processing and processing within a certain temperature range are permitted. The isothermal processing allows temperature fluctuations within the precision range controlled by the instrument.

[0062] To address the issue of material scaling and blockage at the throat of the venturi tube in related technologies, the specific implementation method of this application is described as follows:

[0063] Firstly, some embodiments of this application provide a method for recycling and separating graphite and valuable metals from waste batteries, such as... Figure 1As shown, the recycling and separation method includes the following steps S10~S19:

[0064] S10. Provide plastic and recycled graphite material; wherein the recycled graphite material contains graphite, organic binder and valuable metals;

[0065] The graphite material to be recycled can be obtained by dismantling, crushing, color sorting, gravity sorting, and screening of waste batteries. Graphite comes from the negative electrode material, and valuable metals come from the positive electrode material and other metal materials. Taking the waste battery as a lithium-ion battery as an example, valuable metals can include lithium, copper, aluminum, nickel, cobalt, iron, manganese and other metal materials, which can exist in ionic form or in elemental form. The organic binder comes from the positive electrode material and the negative electrode material.

[0066] Plastics are synthetic polymer compounds, which are a general term for materials that can flow and solidify during processing. They are mainly composed of resin and are supplemented with one or more additives such as plasticizers, fillers, lubricants and colorants.

[0067] S11. Mix the plastic with the graphite material to be recycled to obtain a mixture;

[0068] The plastic can be crushed to facilitate thorough mixing with the graphite material to be recycled.

[0069] S12. The mixture is soaked in an oxidizing agent solution and an alkaline solution in sequence to oxidize the plastic and dissolve the valuable metals in the graphite to be recycled.

[0070] In this process, the plastic is oxidized to facilitate subsequent pyrolysis.

[0071] Valuable metals in the graphite to be recycled can exist in the form of metal salts or in the form of elemental metals. For example, lithium, nickel, cobalt, iron, and manganese usually exist in the form of metal salts, while copper and aluminum exist in elemental form. When soaking in an alkaline solution, lithium salts in these metal salts can exist in the aqueous solution in ionic form, which facilitates the subsequent separation of lithium salts from graphite under alkaline conditions.

[0072] S13. Pyrolyze the soaked mixture to decompose the oxidized plastic into an oily solvent;

[0073] The oxidized plastic can be easily transformed into a small-molecule oily substance through pyrolysis, which can be used as an oil phase solvent.

[0074] S14. The pyrolysis products are washed with water and separated to obtain an alkaline aqueous solution, an oil solution and graphite pyrolysis products, respectively.

[0075] When the pyrolysis products are washed with water, lithium ions can leach out of the graphite under the dissolving action of the alkaline solution, thus obtaining an alkaline aqueous solution. According to the principle of water-oil separation, the alkaline aqueous solution, the oil solution, and the graphite pyrolysis products can be separated. Among them, the graphite pyrolysis products are solids and float on the surface of the oil solution.

[0076] S15. Carbon dioxide is introduced into an alkaline aqueous solution to prepare lithium carbonate;

[0077] When carbon dioxide is introduced into an alkaline aqueous solution, lithium ions react with carbon dioxide to form lithium bicarbonate, which can then be heated to generate lithium carbonate, thus separating the lithium ions.

[0078] S16. The oil phase solution and graphite pyrolysis products are subjected to acid leaching treatment, and after phase separation, an acidic aqueous phase solution and an oil phase graphite are obtained.

[0079] Acid leaching can leach valuable metals other than lithium from the oil phase solution and graphite pyrolysis products into an acidic aqueous phase solution, thereby separating the valuable metals other than lithium from the oil phase substances and graphite.

[0080] S17. Adjust the pH value of the acidic aqueous solution to remove other valuable metal ions except nickel and cobalt from the acidic aqueous solution, and obtain the first aqueous solution of cobalt salt and nickel salt.

[0081] By utilizing the different precipitation rates of nickel hydroxide and cobalt hydroxide with hydroxides of other valuable metals besides nickel and cobalt in acidic aqueous solutions at different pH values, other valuable metal ions besides nickel and cobalt in acidic aqueous solutions can be precipitated first, thereby separating other valuable metal ions besides nickel and cobalt from cobalt salts and nickel salts in acidic aqueous solutions.

[0082] S18. Cobalt salt and nickel salt in the first aqueous solution are extracted and back-extracted sequentially using phosphonic acid extractant and sulfuric acid, and the second aqueous solution obtained after back-extraction is evaporated and crystallized to obtain cobalt sulfate and nickel sulfate.

[0083] Phosphonic acid extractants are oil-soluble extractants that can chelate with metal ions. By using this phosphonic acid extractant to coordinate with cobalt and nickel salts in the first aqueous solution, cobalt and nickel ions can be extracted into an oily solvent. Then, sulfuric acid is used to back-extract the cobalt and nickel ions in the oily solvent to obtain cobalt sulfate and nickel sulfate solutions. Finally, cobalt sulfate and nickel sulfate are obtained by evaporation and crystallization.

[0084] S19. Under a protective atmosphere, oil-phase graphite is sintered to prepare carbon-coated graphite materials.

[0085] By sintering the acid-leached oil-phase graphite, the oil-phase substances in the oil-phase graphite are carbonized and coated on the graphite sintering product, and the voids generated in the graphite sintering product are repaired, which can improve the graphite recovery efficiency and the overall graphitization degree of graphite.

[0086] In the method for recycling and separating graphite and valuable metals from waste batteries provided in this application embodiment, plastic is added to the graphite material to be recycled. Taking advantage of the characteristic that plastic can form an oily solvent through pyrolysis, this oily solvent dissolves the organic binder in the mixture, thus separating the binder from the graphite. Then, utilizing the immiscibility of the aqueous and oil phase solutions, lithium salts in the graphite material to be recycled can be dissolved in an alkaline aqueous solution. By passing carbon dioxide into the alkaline aqueous solution, lithium ions can be separated. Subsequently, by acid leaching the oil phase solution and graphite pyrolysis products, other valuable metal ions besides lithium ions can be dissolved. Utilizing the different precipitation order of valuable metal ions at different pH values, the acid leaching process can further extract these valuable metal ions. Valuable metal ions other than nickel and cobalt in the aqueous solution are precipitated, thus separating cobalt and nickel salts. Then, by sequentially extracting and back-extracting the cobalt and nickel salts in the first aqueous solution using phosphonic acid extractants and sulfuric acid, aqueous solutions of cobalt sulfate and nickel sulfate are obtained. Further evaporation and crystallization yield high-purity cobalt sulfate and nickel sulfate, achieving the recovery and separation of cobalt and nickel salts. Simultaneously, by sintering the acid-leached oil-phase graphite, the oil phase substances in the graphite are carbonized and coated onto the sintered graphite product, and the voids generated in the sintered graphite product are repaired. This improves the graphite recovery efficiency and the overall graphitization degree of graphite, achieving effective resource utilization of graphite and enabling high-efficiency, high-purity, and low-cost recovery of valuable metals from graphite materials.

[0087] In some embodiments, the plastic is waste plastic. Waste plastic can be the scraps of synthetic polymers, or any synthetic polymers that have been used and eventually phased out or replaced in civilian, industrial, or other applications.

[0088] Waste plastics can be considered white pollutants, as they are non-degradable in the environment and cause serious environmental pollution.

[0089] In these embodiments, waste plastics can be recycled and reused, and graphite can be effectively utilized as a resource, thus achieving co-governance of waste.

[0090] In some embodiments, in S11 above, the particle size of the plastic can be 100 mesh to 500 mesh, which facilitates thorough mixing of the plastic with the graphite to be recycled and can improve the subsequent soaking and oxidation effects.

[0091] In some embodiments, the plastic includes at least one of polyethylene (PE), polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), and polymethyl methacrylate (PMMA).

[0092] In some embodiments, the plastic accounts for 0.5% to 5% of the mass of the mixture.

[0093] In some embodiments, in S12 above, the oxidant in the oxidant solution includes at least one of sodium persulfate, hydrogen peroxide, and sodium perchlorate.

[0094] In these embodiments, when these oxidants react with the plastic, they can cause the carbon chains in the plastic to break down, thereby accelerating the decomposition of the plastic into an oily solvent.

[0095] In some embodiments, the mass concentration of the oxidant solution is 5% to 30%.

[0096] In some embodiments, the immersion temperature of the oxidant solution is 20°C to 30°C, and the immersion time is 15 min to 60 min.

[0097] In some embodiments, in S12 above, the alkali in the alkaline solution includes at least one of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0098] In some embodiments, the concentration of the alkaline solution is 1 mol / L to 3 mol / L.

[0099] In some embodiments, the solid-liquid mass ratio during alkaline solution immersion is 1:(2~5).

[0100] In some embodiments, the immersion temperature of the alkaline solution is 30°C to 90°C, and the immersion time is 30 min to 120 min.

[0101] In some embodiments, in S13 above, the pyrolysis temperature is 250°C to 350°C, the pressure is 5 MPa to 10 MPa, and the time is 10 min to 30 min.

[0102] In these embodiments, by controlling the temperature and pressure of pyrolysis, plastics can be converted into an oily solvent.

[0103] In some embodiments, in S14 above, the mass ratio of water used for washing to the pyrolysis product can be 1:(10~25). This can improve the washing effect, allowing lithium ions to be washed into the alkaline aqueous phase solution as much as possible in the alkaline solution.

[0104] In some embodiments, in S15 above, the molar amount of carbon dioxide introduced is 5 to 20 times the molar amount of lithium ions in the alkaline aqueous solution.

[0105] In these embodiments, lithium ions in the alkaline aqueous solution can be converted into lithium carbonate and precipitated, thereby improving the recovery rate and purity of lithium ions.

[0106] In some embodiments, after introducing carbon dioxide, the recovery and separation method further includes heating the alkaline aqueous solution after introducing carbon dioxide to prepare lithium carbonate.

[0107] In some embodiments, the heating temperature is 60°C to 90°C and the heating time is 30 min to 60 min.

[0108] In some embodiments, the acid used in the acid leaching treatment in S16 above includes at least one of sulfuric acid and hydrochloric acid.

[0109] In some embodiments, the acid solution used in the acid leaching treatment has a mass concentration of 10-30%.

[0110] In some embodiments, the liquid-to-solid mass ratio of the acid leaching treatment is 1:(5~15).

[0111] In some embodiments, the acid leaching treatment is performed at a temperature of 70°C to 90°C for a time of 30 min to 180 min.

[0112] In some embodiments, in S17 above, adjusting the pH of the acidic aqueous solution to remove valuable metal ions other than nickel and cobalt from the acidic aqueous solution to obtain a first aqueous solution of cobalt and nickel salts includes:

[0113] An alkaline substance is added to the acidic aqueous solution to adjust the pH value of the acidic aqueous solution to 4.5~5.0, so that other valuable metal ions in the acidic aqueous solution, except for nickel and cobalt, can be removed by precipitation in the form of hydroxides.

[0114] In these embodiments, when the pH of the acidic aqueous solution is adjusted to 4.5-5.0, the copper, iron, manganese and aluminum ions in the acidic aqueous solution are converted into copper hydroxide, iron hydroxide, manganese hydroxide and aluminum hydroxide precipitates, respectively, thereby removing the copper, iron, manganese and aluminum ions while retaining nickel ions and cobalt ions.

[0115] In some embodiments, the alkaline substance includes at least one of sodium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

[0116] In some embodiments, in S18 above, the phosphonic acid extractant may be selected from at least one of C272 and P507.

[0117] In some embodiments, in S18 above, evaporation can be reduced pressure evaporation, with a temperature of 90°C to 110°C and a pressure of -0.4 to -0.6 MPa.

[0118] In some embodiments, in the above S19, the sintering temperature can be 600℃~1000℃, the pressure can be 30 MPa~50 MPa, and the time can be 10 h~40 h.

[0119] In these embodiments, by high-temperature and high-pressure oxygen-free sintering, oil phase substances can be converted into amorphous carbon to coat the graphite pyrolysis products and fill the voids in the graphite pyrolysis products, thereby repairing the graphite and improving the overall graphitization degree of the graphite.

[0120] The specific implementation methods of this application have been described above. In order to objectively illustrate the technical effects produced by this application, the following examples and comparative examples will be used to describe them.

[0121] In the following examples and comparative examples, all raw materials were commercially available, and to maintain the reliability of the experiments, the raw materials used in the following examples and comparative examples had the same physical and chemical parameters or underwent the same treatment.

[0122] In the following examples and comparative examples, the graphite and waste plastics from the waste batteries used were obtained through commercial purchases.

[0123] The metal composition and content of the graphite material to be recycled in the waste battery are shown in Table 1 below.

[0124] Table 1

[0125]

[0126] The waste plastics are at least one of PP, PE, PET, PC and PMMA, and the inorganic chemicals used are all standard chemicals.

[0127] Example 1

[0128] Example 1 provides a method for recycling and separating graphite and valuable metals from waste batteries, the steps of which are as follows:

[0129] (1) Grind the waste PE plastic and waste battery graphite material thoroughly to form material A, wherein the particle size of the ground waste PE plastic is 150 mesh and the mass ratio of waste PE plastic in material A is 0.5%. The well-mixed material is placed in a 10% hydrogen peroxide solution and soaked at room temperature (20℃) for 15 min. After separation, it is placed in a 1 mol / L sodium hydroxide solution and soaked at 30℃ for 60 min. The solid-liquid mass ratio of the soaking solution is 1:2.

[0130] (2) The material soaked in hydrogen peroxide solution and sodium hydroxide solution is put into a high-pressure pyrolysis furnace for pyrolysis. The pyrolysis temperature is 250℃, the pressure is 5MPa, and the time is 10min.

[0131] (3) The pyrolyzed material is washed with water, wherein the mass ratio of water to the pyrolyzed material is 1:10, to obtain an alkaline aqueous solution, an oil solution and graphite. After separating the aqueous phase from other substances, carbon dioxide is introduced into the aqueous phase, and the molar amount of carbon dioxide is 5 times the molar amount of lithium ions in the water to obtain a lithium-containing aqueous solution. The lithium-containing aqueous solution is heated at 60°C for 60 min and filtered to obtain battery-grade lithium carbonate.

[0132] (4) The oil phase solution and graphite are leached with sulfuric acid solution, wherein the mass concentration of sulfuric acid solution is 20%, the mass ratio of sulfuric acid solution to material A is 1:5, the leaching temperature is 70℃, and the leaching time is 30min. The acidic aqueous phase solution and the upper oil phase graphite are obtained after phase separation of the substances after acid leaching.

[0133] (5) After adjusting the pH of the acidic aqueous solution to 4.5 with sodium hydroxide, a small amount of aluminum, manganese, iron and copper hydroxide slag is obtained. The aqueous solution after separating the aluminum, manganese, iron and copper hydroxide slag is extracted with C272 and P507, then back-extracted with sulfuric acid, and then evaporated and crystallized to obtain battery-grade cobalt sulfate and battery-grade nickel sulfate.

[0134] (6) Under nitrogen protection, the oil phase graphite separated in step (4) is sintered in a high-pressure pyrolysis furnace at a temperature of 700°C, a pressure of 30 MPa, and a time of 10 h to recover high-grade graphite and petrochemical fuel.

[0135] Calculations show that in this embodiment, the recovery rate of cobalt ions is 96.5%, and the recovery rate of nickel ions is 97.2%. The purity of both is above 99.5%. The purity of the lithium carbonate product is above 99.5%, and the lithium ion recovery rate is 95.1%. The purity of the graphite is above 99%, and the recovery rate is 97.2%.

[0136] Example 2

[0137] (1) Grind waste PP plastic and waste battery graphite material are thoroughly mixed to form material A, wherein the particle size of the ground waste PP plastic is 200 mesh, and the mass ratio of waste PP plastic in material A is 0.5%. The well-mixed material is immersed in a 15% sodium persulfate solution at room temperature (20°C) for 30 min. After separation, it is immersed in a 1.5 mol / L potassium hydroxide solution at 40°C for 50 min, with a solid-liquid mass ratio of 1:2.5.

[0138] (2) The material after being soaked in sodium sulfate solution and potassium hydroxide solution is put into a high-pressure pyrolysis furnace for pyrolysis. The pyrolysis temperature is 250℃, the pressure is 5MPa, and the time is 15min.

[0139] (3) The pyrolyzed material is washed with water, wherein the mass ratio of water to material is 1:20, to obtain an alkaline aqueous solution, an oil solution and graphite. After separating the aqueous phase from other substances, carbon dioxide is introduced into the aqueous phase, and the molar amount of carbon dioxide is 15 times the molar amount of lithium ions in the water to obtain a lithium-containing aqueous solution. The lithium-containing aqueous solution is heated at 80°C for 20 minutes and filtered to obtain battery-grade lithium carbonate.

[0140] (4) The oil phase solution and graphite are leached with hydrochloric acid solution, wherein the mass concentration of hydrochloric acid solution is 25%, the mass ratio of hydrochloric acid solution to material A is 1:8, the leaching temperature is 70℃, and the time is 50min. The acidic aqueous phase solution and the upper oil phase graphite are obtained after phase separation of the acid leaching material.

[0141] (5) After adjusting the pH of the acidic aqueous solution to 4.7 with potassium hydroxide, a small amount of aluminum, manganese, iron and copper hydroxide slag is obtained. The aqueous solution after separating the aluminum, manganese, iron and copper hydroxide slag is extracted with C272 and P507, then back-extracted with sulfuric acid, and then evaporated and crystallized to obtain battery-grade cobalt sulfate and battery-grade nickel sulfate.

[0142] (6) Under nitrogen protection, the oil phase graphite separated in step (4) is sintered in a high-pressure pyrolysis furnace at a temperature of 750°C, a pressure of 35 MPa, and a time of 15 h to recover high-grade graphite and petrochemical fuel.

[0143] Calculations show that in this embodiment, the recovery rate of cobalt ions is 96.8%, and the recovery rate of nickel ions is 97.5%. The purity of both is above 99.5%. The purity of the lithium carbonate product is above 99.5%, and the lithium ion recovery rate is 96.2%. The purity of the graphite is above 99%, and the recovery rate is 97.5%.

[0144] Example 3

[0145] (1) Grind the waste PC plastic and waste battery graphite material thoroughly to form material A, wherein the particle size of the ground waste PC plastic is 250 mesh and the mass ratio of waste PC plastic in material A is 1.5%. The well-mixed material is placed in a 20% potassium persulfate solution and soaked at room temperature (25℃) for 40 min. After separation, it is placed in a 2 mol / L sodium hydroxide solution and soaked at 50℃ for 40 min. The solid-liquid mass ratio of the soaking solution is 1:3.

[0146] (2) The material soaked in potassium sulfate solution and sodium hydroxide solution is put into a high-pressure pyrolysis furnace for pyrolysis. The pyrolysis temperature is 300℃, the pressure is 5Mpa, and the time is 20min.

[0147] (3) The pyrolyzed material is washed with water, wherein the mass ratio of water to material is 1:25, to obtain an alkaline aqueous solution, an oil solution and graphite. After separating the aqueous phase from other substances, carbon dioxide is introduced into the aqueous phase, and the molar amount of carbon dioxide is 20 times the molar amount of lithium ions in the water to obtain a lithium-containing aqueous solution. The lithium-containing aqueous solution is heated at 90°C for 30 min and filtered to obtain battery-grade lithium carbonate.

[0148] (4) The oil phase solution and graphite are leached with hydrochloric acid solution, wherein the mass concentration of hydrochloric acid solution is 30%, the mass ratio of hydrochloric acid solution to material A is 1:10, the leaching temperature is 80℃, and the time is 100min. The acidic aqueous phase solution and the upper oil phase graphite are obtained after phase separation of the acid leaching material.

[0149] (5) After adjusting the pH of the acidic aqueous solution to 5.0 with sodium carbonate, a small amount of aluminum, manganese, iron and copper hydroxide slag is obtained. The aqueous solution after separating the aluminum, manganese, iron and copper hydroxide slag is extracted with C272 and P507, then back-extracted with sulfuric acid, and then evaporated and crystallized to obtain battery-grade cobalt sulfate and battery-grade nickel sulfate.

[0150] (6) Under nitrogen protection, the oil phase graphite separated in step (4) is sintered in a high-pressure pyrolysis furnace at a temperature of 800°C, a pressure of 40 MPa, and a time of 20 h to recover high-grade graphite and petrochemical fuel.

[0151] Calculations show that in this embodiment, the recovery rate of cobalt ions is 97.2%, and the recovery rate of nickel ions is 98.1%, with purity exceeding 99.5%. The purity of the lithium carbonate product is above 99.5%, and the lithium ion recovery rate is 96.8%. The purity of the graphite is above 99%, and the recovery rate is 97.9%.

[0152] Example 4

[0153] (1) Grind waste PET plastic and waste battery graphite material are thoroughly mixed to form material A, wherein the particle size of the ground waste PET plastic is 250 mesh and the mass ratio of waste PET plastic in material A is 3%. The well-mixed material is immersed in a 20% sodium perchlorate solution at room temperature (30°C) for 60 min. After separation, it is immersed in a 3 mol / L sodium carbonate solution at 90°C for 120 min, with a solid-liquid mass ratio of 1:4.

[0154] (2) The material soaked in sodium perchlorate solution and sodium carbonate solution is put into a high-pressure pyrolysis furnace for pyrolysis. The pyrolysis temperature is 350℃, the pressure is 5MPa, and the time is 20min.

[0155] (3) The pyrolyzed material is washed with water, wherein the mass ratio of water to material is 1:25, to obtain an alkaline aqueous solution, an oil solution and graphite. After separating the aqueous phase from other substances, carbon dioxide is introduced into the aqueous phase, and the molar amount of carbon dioxide is 20 times the molar amount of lithium ions in the water to obtain a lithium-containing aqueous solution. The lithium-containing aqueous solution is heated at 90°C for 30 min and filtered to obtain battery-grade lithium carbonate.

[0156] (4) The oil phase solution and graphite are leached with sulfuric acid solution, wherein the mass concentration of sulfuric acid solution is 30%, the mass ratio of sulfuric acid solution to material A is 1:15, the leaching temperature is 90℃, and the time is 180min. The acidic aqueous phase solution and the upper oil phase graphite are obtained after phase separation of the substances after acid leaching.

[0157] (5) After adjusting the pH of the acidic aqueous solution to 5.0 with sodium bicarbonate, a small amount of aluminum, manganese, iron and copper hydroxide slag is obtained. The aqueous solution after separating the aluminum, manganese, iron and copper hydroxide slag is extracted with C272 and P507, then back-extracted with sulfuric acid, and then evaporated and crystallized to obtain battery-grade cobalt sulfate and battery-grade nickel sulfate.

[0158] (6) Under nitrogen protection, the oil phase graphite separated in step (4) is sintered in a high-pressure pyrolysis furnace at a temperature of 800°C, a pressure of 40 MPa, and a time of 20 h to recover high-grade graphite and petrochemical fuel.

[0159] Calculations show that in this embodiment, the recovery rate of cobalt ions is 97.5%, and the recovery rate of nickel ions is 98.3%. The purity of both is above 99.5%. The purity of the lithium carbonate product is above 99.5%, and the lithium ion recovery rate is 97.1%. The purity of the graphite is above 99%, and the recovery rate is 98.6%.

[0160] Comparative Example 1

[0161] The method for recycling and separating graphite and valuable metals from waste batteries provided in Comparative Example 1 is basically the same as the method for recycling and separating graphite and valuable metals from waste batteries provided in Example 1, except that:

[0162] No waste plastic is added in step (1), and steps (2) and (6) are removed.

[0163] Calculations show that in this comparative example, the recovery rate of cobalt ions was 77.2%, the recovery rate of nickel ions was 78.1%, and the recovery rate of lithium ions was 76.8%. The purity of graphite was 85%, and the recovery rate was 82.3%.

[0164] As can be seen, Example 1 of this application can effectively improve the recovery rate and purity of valuable metals and graphite compared with Comparative Example 1.

[0165] Comparative Example 2

[0166] The method for recycling and separating graphite and valuable metals from waste batteries provided in Comparative Example 2 is basically the same as the method for recycling and separating graphite and valuable metals from waste batteries provided in Example 1, except that:

[0167] No oxidant or alkaline solution is added during soaking in step (1).

[0168] Calculations show that the recovery rate of cobalt ions in this comparative example is 87.2%, the recovery rate of nickel ions is 88.1%, and the recovery rate of lithium ions is 26.8%. The purity of graphite is 90%, and the recovery rate is 92.3%.

[0169] As can be seen, compared with Comparative Example 2, the addition of oxidant in Example 1 of this application can accelerate the decomposition of waste plastics and organic binders, and facilitate the separation of lithium ions from graphite, thereby improving the recovery rate and purity of valuable metals and graphite, especially the recovery rate and purity of lithium ions are greatly improved.

[0170] Comparative Example 3

[0171] The method for recycling and separating graphite and valuable metals from waste batteries provided in Comparative Example 3 is basically the same as the method for recycling and separating graphite and valuable metals from waste batteries provided in Example 1, except that:

[0172] The sulfuric acid leaching treatment in step (4) is not performed.

[0173] Calculations show that the recovery rate of cobalt ions in this comparative example is 27.2%, the recovery rate of nickel ions is 38.1%, and the recovery rate of lithium ions is 95.8%. The purity of graphite is 67%, and the recovery rate is 85.3%.

[0174] As can be seen, compared with Comparative Example 3, the addition of the acid leaching step in Example 1 of this application can dissolve valuable metals from graphite and oil phase solutions as much as possible, thereby improving the recovery rate and purity of graphite and valuable metals, and improving the separation accuracy.

[0175] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0176] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for recycling and separating graphite and valuable metals from waste batteries, characterized in that, include: The invention provides plastic and graphite material to be recycled; wherein the graphite material to be recycled contains graphite, organic binder and valuable metals; The plastic is mixed with the graphite to be recycled to obtain a mixture; The mixture is soaked in an oxidizing agent solution and an alkaline solution in sequence to oxidize the plastic and dissolve the valuable metals in the graphite to be recycled. The soaked mixture is then pyrolyzed to decompose the oxidized plastic into an oily solvent. The pyrolysis products were washed with water and separated to obtain an alkaline aqueous solution, an oil solution, and graphite pyrolysis products, respectively. Lithium carbonate is prepared by passing carbon dioxide into the alkaline aqueous solution. The oil phase solution and the graphite pyrolysis product are subjected to acid leaching treatment, and after phase separation, an acidic aqueous phase solution and an oil phase graphite are obtained. The pH value of the acidic aqueous solution is adjusted to remove other valuable metal ions besides nickel and cobalt from the acidic aqueous solution, resulting in a first aqueous solution of cobalt salt and nickel salt. The cobalt and nickel salts in the first aqueous solution were extracted and back-extracted sequentially using phosphonic acid extractant and sulfuric acid, and the second aqueous solution obtained after back-extraction was evaporated and crystallized to obtain cobalt sulfate and nickel sulfate. The oil-phase graphite is sintered under a protective atmosphere to prepare carbon-coated graphite material.

2. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The plastic satisfies at least one of the following conditions: (1) The plastic is waste plastic; (2) The particle size of the plastic is 100 mesh to 500 mesh; (3) The plastic includes at least one of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate and polymethyl methacrylate; (4) The plastic accounts for 0.5% to 5% of the mass of the mixture.

3. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The oxidant solution satisfies at least one of the following conditions: (1) The oxidant in the oxidant solution includes at least one of sodium persulfate, hydrogen peroxide and sodium perchlorate; (2) The mass concentration of the oxidant solution is 5%~30%; (3) The immersion temperature of the oxidant solution is 20℃~30℃ and the time is 15 min~60 min.

4. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The alkaline solution satisfies at least one of the following conditions: (1) The alkali in the alkaline solution includes at least one of sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide; (2) The concentration of the alkaline solution is 1 mol / L to 3 mol / L; (3) The solid-liquid mass ratio of the alkaline solution soaking is 1:(2~5); (4) The soaking temperature of the alkaline solution is 30℃~90℃ and the soaking time is 30 min~120 min.

5. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The pyrolysis temperature is 250℃~350℃, the pressure is 5MPa~10MPa, and the time is 10min~30min.

6. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The mass ratio of water used for washing to the pyrolysis product is 1:(10~25).

7. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The molar amount of carbon dioxide introduced is 5 to 20 times the molar amount of lithium ions in the alkaline aqueous solution; and / or, After introducing carbon dioxide, the recovery and separation method further includes heating the alkaline aqueous solution after introducing the carbon dioxide to prepare lithium carbonate; optionally, the heating temperature is 60℃~90℃ and the time is 30 min~60 min.

8. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The acid leaching treatment satisfies at least one of the following conditions: (1) The acid used in the acid leaching treatment includes at least one of sulfuric acid and hydrochloric acid; (2) The mass concentration of the acid solution used in the acid leaching treatment is 10%~30%; (3) The liquid-to-solid mass ratio of the acid leaching treatment is 1:(5~15); (4) The acid leaching treatment is performed at a temperature of 70℃~90℃ for a time of 30 min~180 min.

9. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The pH value of the acidic aqueous solution is adjusted to remove valuable metal ions other than nickel and cobalt from the acidic aqueous solution, resulting in a first aqueous solution of cobalt and nickel salts, comprising: An alkaline substance is added to the acidic aqueous solution to adjust the pH value of the acidic aqueous solution to 4.5~5.0, so that other valuable metal ions in the acidic aqueous solution, except for nickel and cobalt, are removed by precipitation in the form of hydroxides. Optionally, the alkaline substance includes at least one of sodium bicarbonate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide.

10. The method for recycling and separating graphite and valuable metals from waste batteries according to claim 1, characterized in that, The sintering temperature is 600℃~1000℃, the pressure is 30 MPa~50 MPa, and the time is 10h~40h.

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