Methods and systems for recycling used lithium batteries

Abstract

This invention discloses a method and system for recycling waste lithium batteries, including crushing the waste lithium batteries and separating the positive electrode powder; mixing the positive electrode powder with a binder, activator, and water in a preset ratio, and pressing the mixed powder into lumps; placing the lumps in a drying oven to dry for a first preset time; placing the dried lumps in a rotary kiln and calcining them at a preset temperature for a second preset time to obtain activated lumps; cooling the activated lumps in cold water for a third preset time; adding the cooled lumps to a ball mill for wet ball milling to obtain a slurry; and adding sulfuric acid of a preset concentration to the slurry for acid leaching. This waste lithium battery recycling method can improve the activation efficiency of the positive electrode powder from waste lithium batteries, effectively increasing the recycling efficiency while effectively reducing equipment energy consumption.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more particularly to methods and systems for recycling waste lithium batteries. Background Technology

[0002] In recent years, with the rapid development of the global new energy vehicle industry, ternary lithium batteries have become the mainstream power source due to their high energy density and long cycle life. However, the average lifespan of lithium batteries is 5-8 years. It is estimated that by 2030, the annual output of retired power batteries in my country will exceed 3.5 million tons. Retired lithium batteries contain a large number of valuable metal elements, such as nickel, cobalt, and lithium, which have significant recycling value. Therefore, the rational utilization of resources in retired lithium-ion batteries is of great significance for achieving efficient resource recycling and utilization and building a green closed-loop industrial system.

[0003] In the existing lithium battery recycling process, lithium battery powder is first fed into a rotary kiln for high-temperature activation. When using a rotary kiln for activation, due to the small particle size and light weight of the lithium battery powder, 20% to 40% of the powder will be blown out of the rotary kiln. This part of the powder needs to be collected and returned to the rotary kiln for high-temperature activation, resulting in low yield and high energy consumption of high-temperature activation of retired lithium batteries. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method and system for recycling waste lithium batteries. The method for recycling waste lithium batteries can improve the activation efficiency of the positive electrode powder of waste lithium batteries, thereby effectively improving the efficiency of recycling and processing while effectively reducing the energy consumption of the equipment.

[0005] To achieve the above objectives, the present invention aims to provide a method for recycling waste lithium batteries, comprising:

[0006] Waste lithium batteries are crushed and the positive electrode powder is separated.

[0007] The positive electrode powder is mixed with binder, activator and water in a preset ratio, and the mixed powder is pressed into lumps;

[0008] The lumps are placed in a drying oven and dried for a first preset time.

[0009] The dried agglomerates are placed in a rotary kiln and roasted at a preset temperature for a second preset time to obtain activated agglomerates.

[0010] The activated agglomerate was placed in cold water and cooled for a third preset time.

[0011] The cooled lumps are added to a ball mill for wet ball milling to obtain a slurry;

[0012] Acid leaching is performed by adding sulfuric acid of a predetermined concentration to the slurry.

[0013] In some embodiments, the binder includes at least one of syrup and starch.

[0014] In some embodiments, the activator includes at least one of graphite, starch, and activated carbon.

[0015] In some embodiments, the amount of the adhesive ranges from 0 to 10%, the amount of the activator ranges from 0 to 40%, and the amount of water ranges from 0 to 15%.

[0016] In some embodiments, the agglomerate is cylindrical in shape and has a diameter ranging from 10 to 50 mm.

[0017] In some embodiments, the temperature range of the rotary kiln is between 500 and 1000°C, and the firing time is between 0 and 180 minutes.

[0018] In some embodiments, the concentration of sulfuric acid is in the range of 0 to 6 mol / L, the acid leaching time is in the range of 0 to 240 min, the acid leaching temperature is in the range of 50 to 100 °C, and the acid leaching solid-liquid ratio is in the range of 0 to 30:1.

[0019] In some embodiments, the clumps formed during the pressing of the mixed powder into clumps have a perforation in the middle.

[0020] According to another aspect of this application, a waste lithium battery recycling system is further provided, comprising:

[0021] A crushing and sorting unit is used to crush waste lithium batteries and sort out positive electrode powder.

[0022] A pelletizing unit is used to mix the positive electrode powder with a binder, an activator and water in a preset ratio, and press the mixed powder into pellets.

[0023] A drying unit, the drying unit being used to dry the lumps;

[0024] An activation unit is used to place the dried agglomerates in a rotary kiln and calcine them at a preset temperature for a second preset time to obtain activated agglomerates.

[0025] A cooling unit is used to place the activated agglomerate in cold water to cool it for a third preset time.

[0026] A grinding unit is used to wet ball mill the cooled lumps to obtain a slurry;

[0027] An acid leaching unit is used to add sulfuric acid of a preset concentration to the slurry for acid leaching.

[0028] In some embodiments, the waste lithium battery recycling system further includes a punching unit for creating at least one through hole in the agglomerate. Attached Figure Description

[0029] The preferred embodiments will now be described in a clear and easy-to-understand manner, in conjunction with the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of the present invention.

[0030] Figure 1 This is a flowchart of a preferred embodiment of the recycling method for waste lithium batteries of the present invention;

[0031] Figure 2 This is a block diagram of a preferred embodiment of the waste lithium battery recycling system of the present invention. Detailed Implementation

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0033] To keep the drawings concise, each figure only schematically shows the parts relevant to the invention, and these do not represent the actual structure of the product. Furthermore, to facilitate understanding, in some figures, only one of components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0034] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0035] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] refer to Figure 1 This application provides a method for recycling waste lithium batteries. This method improves the activation efficiency of the positive electrode powder from waste lithium batteries, effectively increasing recycling efficiency while reducing equipment energy consumption. Waste lithium batteries can also be described as retired lithium batteries, and this recycling method can be described as a method for recycling retired lithium batteries. The specific steps of the waste lithium battery recycling method are as follows:

[0038] S101: Crushing waste lithium batteries and separating the positive electrode powder;

[0039] S102: Mix the positive electrode powder with binder, activator and water in a preset ratio, and press the mixed powder into lumps;

[0040] S103: Place the agglomerate in a drying oven and dry it for a first preset time;

[0041] S104: The dried agglomerates are placed in a rotary kiln and roasted at a preset temperature for a second preset time to obtain activated agglomerates.

[0042] S105: Place the activated agglomerate in cold water to cool for a third preset time;

[0043] S106: Add the cooled agglomerates to a ball mill for wet ball milling to obtain a slurry;

[0044] S107: Add sulfuric acid of a preset concentration to the slurry for acid leaching.

[0045] In step S101 above, after obtaining the waste batteries, they are first crushed to separate the positive electrode powder. Before crushing the waste lithium batteries, they usually need to be discharged. This discharge can be done using either resistance discharge or brine discharge to eliminate safety hazards. After separating the positive electrode powder from the crushed waste batteries, impurities such as graphite are removed to obtain high-purity positive electrode powder.

[0046] Preferably, the spent lithium battery is a power battery for new energy vehicles. In some modified embodiments, the spent lithium battery can also be a consumer lithium battery or an electric bicycle lithium battery, wherein the consumer lithium battery includes, but is not limited to, mobile phone batteries, laptop batteries, etc.

[0047] Preferably, the waste lithium batteries are ternary lithium batteries. In some modified embodiments, the waste lithium batteries may also be lithium iron phosphate batteries, lithium cobalt oxide batteries, or lithium manganese oxide batteries. The specific category of the waste lithium batteries should not constitute a limitation on this application.

[0048] In step S102 above, the positive electrode powder is mixed with a binder, activator, and water in a preset ratio, and the mixed powder is pressed into briquettes. This fixes the shape of the positive electrode powder, reduces dust, and facilitates loading, unloading, and transportation. In this invention, after the retired lithium battery powder is briquetted, due to the large volume and mass of the briquettes, no unactivated powder is blown out of the rotary kiln during the activation process. The high-strength briquettes formed from the retired lithium battery powder significantly reduce the amount of powder in the rotary kiln, which also effectively reduces ring formation in the rotary kiln. The absence of powder generation during the activation process and the reduction of ring formation in the rotary kiln effectively improve the yield of the retired lithium battery rotary kiln activation process and reduce the energy consumption of the rotary kiln activation process.

[0049] In step S102 above, the binder includes at least one of syrup and starch, meaning that in some embodiments, only syrup can be used as the binder. In some embodiments, only starch can be used as the binder. In some embodiments, a mixture of starch and syrup can be used as a composite binder. Preferably, the starch can be either corn starch or sweet potato starch, and the syrup can be either glucose syrup or maltose syrup. When starch is used as the binder, the gelatinized starch has strong adhesive ability, which facilitates the formation of clumps during the pressing process. When syrup is used as the binder, the syrup has good fluidity, which facilitates mixing with the positive electrode powder, and it has high strength after drying, which can greatly improve the structural strength of the clumps formed by pressing.

[0050] It should also be noted that the syrup and / or starch binder added to the agglomerates in step S102 can pyrolyze and burn at high temperatures during the calcination of the agglomerates in the rotary kiln in step S104, without introducing impurities into the cathode powder, without contaminating the cathode powder, and without affecting the subsequent acid leaching; on the other hand, the syrup and / or starch can also release heat during combustion, which helps to increase the calcination temperature and reduce the energy consumption of the rotary kiln; furthermore, after the pyrolysis and combustion of the syrup and / or starch, micropores and channels will be left in the agglomerates, making the structure of the agglomerates loose, which helps with the cooling in step S105 and the ball milling in step S106.

[0051] Further, in step S102 above, the activator includes at least one of graphite, starch, and activated carbon. During the calcination process in step S104, the activator undergoes a solid-state reaction with the lattice of the cathode material, destroying the stable layered structure or olivine structure of the cathode material, causing lattice distortion, defects, and micropores, and reducing crystallinity; at the same time, it forms acid-soluble active intermediates with metal elements such as lithium, nickel, cobalt, and manganese, thereby significantly improving the wet ball milling efficiency in the subsequent step S106 and the leaching rate in the subsequent acid leaching process in step S107.

[0052] For example, in step S102 above, the amount of the adhesive ranges from 0 to 10%, the amount of the activator ranges from 0 to 40%, and the moisture content ranges from 0 to 15%.

[0053] In step S102 above, the compressed agglomerate is spherical with a diameter ranging from 10 to 50 mm, and the compression pressure is between 5 and 50 MPa. In some modified embodiments, the compressed agglomerate in step S102 may also be cylindrical with a diameter ranging from 10 to 50 mm and a height ranging from 1 to 100 mm. In some embodiments, the compressed agglomerate in step S102 may also be square. The specific shape of the compressed agglomerate should not constitute a limitation on this application.

[0054] In step S103 above, the agglomerates are placed in a drying oven for drying, so that the agglomerates can harden, have a certain structural strength, and be easy to store and transport, and easy to calcinate in the rotary kiln. Preferably, the agglomerates are placed in a forced-air drying oven for drying. In some modified embodiments, the agglomerates can also be placed in an oven for drying.

[0055] In step S104 above, the dried agglomerates are placed in a rotary kiln and calcined at a preset temperature for a second preset time to obtain activated agglomerates. In this step, the high-temperature calcination of the agglomerates can pyrolyze the binders and other organic matter in the agglomerates into gases and release them, effectively preventing organic matter from affecting subsequent acid leaching and metal purity. It can also further remove residual moisture from the agglomerates, making the agglomerates structurally intact and less prone to pulverization, meeting the requirements of subsequent water quenching and ball milling processes. Most importantly, the high temperature causes the cathode powder lattice to distort, increase defects, and reduce crystallinity, destroying the original stable structure, increasing chemical activity, providing a reaction basis for subsequent acid leaching, and providing solid-phase reaction conditions for the activator and cathode powder, allowing the activator to fully diffuse and react, further reducing the difficulty of acid leaching and increasing the metal leaching rate.

[0056] Preferably, in step S104 above, the temperature range of the rotary kiln is between 500 and 1000°C, and the calcination time is between 0 and 180 minutes. During the calcination of the agglomerates in the rotary kiln in step S104, an inert gas needs to be simultaneously introduced into the kiln. This inert gas includes, but is not limited to, nitrogen and / or argon, to isolate the agglomerates from air and prevent oxidation.

[0057] In step S105 above, the activated agglomerates are placed in cold water to cool for a third preset time. The activated agglomerates are placed in cold water to cool, and microcracks are generated in the agglomerates by water quenching and thermal shock, which improves porosity and reactivity, and can quickly cool the agglomerates to stabilize the activated phase, which is convenient for subsequent ball milling and acid leaching.

[0058] Preferably, in step S105 above, the temperature range of the cold water used to cool the agglomerates is between 0 and 20 degrees Celsius, for example, but not limited to 5 to 20 degrees Celsius.

[0059] In step S106 above, ball milling breaks down the water-cooled clumps, significantly reducing particle size and increasing specific surface area. This allows sulfuric acid to fully contact the metal particles in the subsequent acid leaching step, improving the leaching rate and extraction rate. Wet ball milling in an aqueous medium directly disperses the solid material into a uniform and stable slurry, eliminating the need for dry powder re-slurry preparation, simplifying the process, and reducing dust. Furthermore, the mechanical activation generated during ball milling causes lattice distortion and defects in the cathode powder particles, further reducing the difficulty of acid leaching and enhancing reactivity.

[0060] Preferably, in step S106 above, the particle size of the agglomerates is ground to a ratio of 50% to 100% of the material with a particle size of less than 200 mesh by ball milling.

[0061] In step S107 above, sulfuric acid of a preset concentration is added to the slurry produced in step S106 above for acid leaching. The sulfuric acid can react with the cathode powder, transferring valuable metals such as lithium, nickel, cobalt, and manganese from the solid phase to the liquid phase to form soluble sulfates, thereby achieving solid-liquid separation and metal enrichment.

[0062] Preferably, the concentration of sulfuric acid used in step S107 is in the range of 0~6 mol / L, for example but not limited to 2 mol / L, the acid leaching time is in the range of 0~240 min, for example but not limited to 30 min, the acid leaching temperature is in the range of 50~100℃, for example but not limited to 60℃, and the acid leaching solid-liquid ratio is in the range of 0~30:1, for example but not limited to 1:1.

[0063] In some embodiments, in step S102 above, the agglomerates formed during the pressing of the mixed powder into agglomerates have a through hole in the middle. That is, in step S102 above, the positive electrode powder, binder, activator, and water are first mixed in a preset ratio and then pre-pressed into shape, and then a through hole is opened at a preset position to form agglomerates. By opening a through hole at a preset position on the agglomerates, on the one hand, the contact area between the flowing gas and the agglomerates can be increased during air drying in the drying oven in step S103 above, thereby improving the air drying efficiency of the agglomerates; on the other hand, it can facilitate the breaking of the agglomerates into fine particles in the ball milling process in step S106 above.

[0064] Example 1: The nickel, cobalt, manganese, and lithium contents in the lithium-ion battery cathode powder are 12.91%, 15.39%, 6.95%, and 4.47%, respectively, with a graphite content of 17.36%. The content of particles smaller than 0.075 mm in the cathode powder is 83.98%. First, the cathode powder with 10% added moisture is pressed into cylindrical agglomerates with a diameter of 10 mm and a height of 10 mm at a pressure of 10 MPa. The compressive strength of the dry agglomerates is 766 N / a. The temperature in the rotary kiln is 800℃, and nitrogen is introduced for activation for 60 minutes. At this point, the cold compressive strength of the agglomerates reaches 2786 N / a. The activated hot agglomerates are directly cooled in water and then ball-milled to a particle size of less than 200 mesh (100%). The ball-milled slurry was prepared into a 3 mol / L sulfuric acid solution for acid leaching. The leaching time was 120 min, the leaching temperature was 85℃, and the solid-liquid ratio was 10:1. At this time, the leaching rates of nickel, cobalt, manganese, and lithium were 85%, 93%, 98%, and 97%, respectively.

[0065] Example 2: The nickel, cobalt, manganese, and lithium contents in the lithium-ion battery cathode powder are 12.91%, 15.39%, 6.95%, and 4.47%, respectively; the graphite content is 17.36%; and the activated carbon content is 1%. The content of particles smaller than 0.075 mm in the cathode powder is 83.98%. First, the cathode powder with 0% added moisture is pressed into cylindrical agglomerates with a diameter of 10 mm and a height of 10 mm at a pressure of 10 MPa. The compressive strength of the dry agglomerates is 344 N / a. The dry agglomerates are activated in a rotary kiln at 700℃ in a nitrogen atmosphere for 90 minutes. At this point, the cold compressive strength of the agglomerates reaches 1269 N / a. The activated hot agglomerates are directly cooled in water and then ball-milled in a ball mill until 100% of the particles are smaller than 200 mesh. The ball-milled slurry was prepared into a 4 mol / L sulfuric acid solution for acid leaching. The leaching time was 150 min, the leaching temperature was 80℃, and the solid-liquid ratio was 20:1. At this time, the leaching rates of nickel, cobalt, manganese, and lithium were 91%, 94%, 97%, and 96%, respectively.

[0066] Example 3: The nickel, cobalt, manganese, and lithium contents in the lithium-ion battery cathode powder are 12.91%, 15.39%, 6.95%, and 4.47%, respectively, with a graphite content of 17.36%. The content of particles smaller than 0.075 mm in the cathode powder is 78.62%. First, lithium-ion battery black powder with 1.5% syrup is pressed into cylindrical blocks with a diameter of 25 mm and a height of 10 mm at a pressure of 15 MPa. The compressive strength of the dry blocks is 830 N / block. The dry blocks are activated at 650℃ in a nitrogen atmosphere for 120 min, at which point the cold compressive strength of the blocks reaches 2069 N / block. The activated hot blocks are directly cooled in water and then ball-milled to a particle size of less than 200 mesh, with 95% of the particles smaller than 200 mesh. The ball-milled slurry was prepared into a 5 mol / L sulfuric acid solution for acid leaching. The leaching time was 180 min, the leaching temperature was 90℃, and the solid-liquid ratio was 20:1. At this time, the leaching rates of nickel, cobalt, manganese, and lithium were 92%, 95%, 96%, and 99%, respectively.

[0067] refer to Figure 2 According to another aspect of this application, a waste lithium battery recycling system is further provided, including a crushing and sorting unit 10, an agglomeration unit 20, a drying unit 30, an activation unit 40, a cooling unit 50, a grinding unit 60, and an acid leaching unit 70. The crushing and sorting unit 10 is used to crush waste lithium batteries and sort out positive electrode powder. The agglomeration unit 20 is used to mix the positive electrode powder with a binder, an activator, and water in a preset ratio, and press the mixed powder into agglomerates. The drying unit 30 is used to dry the agglomerates. The activation unit 40 is used to place the dried agglomerates in a rotary kiln and calcine them at a preset temperature for a second preset time to obtain activated agglomerates. The cooling unit 50 is used to place the activated agglomerates in cold water to cool them for a third preset time. The grinding unit 60 is used to wet ball mill the cooled agglomerates to obtain a slurry. The acid leaching unit 70 is used to add sulfuric acid of a preset concentration to the slurry for acid leaching. In some embodiments, the waste lithium battery recycling system further includes a punching unit 80 for creating at least one through hole in the agglomerate.

[0068] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are merely examples and do not limit the invention. The advantages of the present invention have been fully and effectively realized. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments; any variations or modifications can be made to the implementation of the present invention without departing from these principles.

Claims

1. A method for recycling waste lithium batteries, characterized in that, include: Waste lithium batteries are crushed and the positive electrode powder is separated. The positive electrode powder is mixed with binder, activator and water in a preset ratio, and the mixed powder is pressed into lumps; The lumps are placed in a drying oven and dried for a first preset time. The dried agglomerates are placed in a rotary kiln and roasted at a preset temperature for a second preset time to obtain activated agglomerates. The activated agglomerate was placed in cold water and cooled for a third preset time. The cooled lumps are added to a ball mill for wet ball milling to obtain a slurry; Acid leaching is performed by adding sulfuric acid of a predetermined concentration to the slurry.

2. The method for recycling waste lithium batteries according to claim 1, characterized in that, The binder includes at least one of syrup and starch.

3. The method for recycling waste batteries according to claim 2, characterized in that, The activator includes at least one of graphite, starch, and activated carbon.

4. The method for recycling waste batteries according to claim 3, characterized in that, The amount of the adhesive ranges from 0 to 10%, the amount of the activator ranges from 0 to 40%, and the amount of water ranges from 0 to 15%.

5. The method for recycling waste batteries according to claim 4, characterized in that, The mass is cylindrical in shape and has a diameter ranging from 10 to 50 mm.

6. The method for recycling waste batteries according to claim 1, characterized in that, The temperature range of the rotary kiln is between 500 and 1000°C, and the firing time is between 0 and 180 minutes.

7. The method for recycling waste lithium batteries according to claim 1, characterized in that, The concentration of sulfuric acid is in the range of 0~6 mol / L, the acid leaching time is in the range of 0~240 min, the acid leaching temperature is in the range of 50~100℃, and the solid-liquid ratio is in the range of 0~30:

1.

8. The method for recycling waste lithium batteries according to claim 1, characterized in that, The agglomerates formed during the process of pressing the mixed powder into lumps have a perforation in the middle.

9. A waste lithium battery recycling system, characterized in that, include: A crushing and sorting unit is used to crush waste lithium batteries and sort out positive electrode powder. A pelletizing unit is used to mix the positive electrode powder with a binder, an activator and water in a preset ratio, and press the mixed powder into pellets. A drying unit, the drying unit being used to dry the lumps; An activation unit is used to place the dried agglomerates in a rotary kiln and calcine them at a preset temperature for a second preset time to obtain activated agglomerates. A cooling unit is used to place the activated agglomerate in cold water to cool it for a third preset time. A grinding unit is used to wet ball mill the cooled lumps to obtain a slurry; An acid leaching unit is used to add sulfuric acid of a preset concentration to the slurry for acid leaching.

10. The waste lithium battery recycling system according to claim 9, characterized in that, The waste lithium battery recycling system further includes a drilling unit, which is used to create at least one through hole in the agglomerate.

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