A method and device for recovering positive electrode material from lithium battery slurry

Abstract

The present invention discloses a method and device for recovering positive electrode materials from lithium battery slurry. The method comprises the following steps: shredding waste materials, adding solvent, and obtaining a first slurry after bubble crushing; screening through a discharge hole; overflow crushing the first slurry whose size is smaller than the diameter of the discharge hole step by step to obtain a second slurry; obtaining a filter cake and a filtrate after flocculation and filter pressing; and obtaining a positive electrode material after drying, crushing, and pyrolysis of the filter cake. The method can realize continuous and large-scale processing of waste lithium battery slurry, simplifying the slurry recovery process. The positive electrode material and the solvent are effectively separated and recycled, reducing the recycling cost. The whole process is environmentally friendly and energy-saving, and is convenient for the later processing of the positive electrode powder. The total content of Ni, Co, Mn, and Li metals in the recovered positive electrode powder is more than 50%, which has great recycling value.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery recycling, and in particular relates to a method and a device for recycling positive electrode materials from lithium battery slurry. Background Art

[0002] In the preparation process of nickel-cobalt-manganese ternary lithium-ion batteries, the positive electrode sheet is made by coating a slurry made of lithium nickel-cobalt-manganese oxide as the positive electrode active material on the current collector. In this process, waste slurry is inevitably generated. Its components include NMP (N-methylpyrrolidone), water, conductive agent, positive electrode material and polyvinylidene fluoride (PVDF), etc., as well as foreign objects such as slurry packaging plastic bags, rags and gloves. Because the positive electrode materials in the waste slurry contain Ni, Co, and Mn metals, the waste slurry has great recyclable value. In addition, during the long-term storage of the waste slurry, the waste slurry is prone to agglomeration, which makes it difficult to recover the slurry. If the waste slurry is not handled properly, it will not only cause a waste of resources, but also cause environmental pollution and pose a huge safety hazard.

[0003] Currently, the primary method for treating waste slurry from lithium battery coating is incineration. The specific process involves placing the waste slurry into an incinerator for combustion and pyrolysis, producing slag and a large amount of exhaust gas. This exhaust gas is then treated to meet emission standards. This method removes organic matter, and the slag produced can be directly leached. However, the entire process produces exhaust gases such as nitrogen oxides, carbon oxides, and hydrogen fluoride, which require treatment before discharge. This process is stressful, and the material is prone to agglomeration and sticking to the walls during incineration, making it difficult for barreled materials to enter the incinerator.

[0004] Therefore, it is of great significance to provide a method that can effectively recycle waste slurry and reduce tail gas emissions. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is:

[0006] Provided is a method for recovering positive electrode material from lithium battery slurry.

[0007] The method effectively separates and recycles the cathode material and solvent, and can reduce tail gas emissions. The total content of Ni, Co, Mn, and Li metals in the cathode powder recovered by the present invention is above 50%, which has great economic benefits.

[0008] The second technical problem to be solved by the present invention is:

[0009] Provided is a device for recycling positive electrode materials using the method.

[0010] In order to solve the first technical problem, the technical solution adopted by the present invention is:

[0011] Method for recovering positive electrode material from lithium battery slurry,

[0012] The following steps are involved:

[0013] The waste material is shredded, a solvent is added, and the bubbles are broken to obtain a first slurry;

[0014] Screening is performed through the discharge hole;

[0015] The first slurry having a size smaller than the diameter of the discharge hole is overflow-crushed step by step to obtain a second slurry;

[0016] After flocculation and solid-liquid separation, the solid phase is collected;

[0017] The solid phase is dried, crushed and pyrolyzed to obtain the positive electrode material.

[0018] The waste materials include waste pulp containing foreign matter such as plastics and cloth strips.

[0019] According to one embodiment of the present invention, the step-by-step overflow crushing includes conveying the first slurry whose size is smaller than the discharge hole into the matching first-level slurry pool, further crushing it through the bubble drum in the crushing area of ​​the first-level slurry pool, and carrying the overflow fine particle slurry into the next-level crushing area by the solvent, and again undergoing bubble crushing in the next-level crushing area. After multiple overflow crushing, a slurry that meets the requirements is obtained and then enters the next process.

[0020] According to one embodiment of the present invention, the volume of the waste is 1000 to 2000 L. The present invention can process large quantities of waste.

[0021] According to one embodiment of the present invention, the solvent includes at least one of N-methylpyrrolidone, propylene glycol methyl ether acetate, and propylene glycol methyl ether.

[0022] According to one embodiment of the present invention, the volume of the solvent is 1000-2000L.

[0023] According to one embodiment of the present invention, the pressure for the bubble collapse is 0.4-0.8 MPa.

[0024] The bubble crushing process can peel off the waste slurry adhered to the foreign matter and preliminarily crush the waste slurry. The bubble crushing process can also split the larger air bubbles to form bubbles with smaller diameters, thereby increasing the contact area between the air and the slurry.

[0025] According to one embodiment of the present invention, after screening through the discharge hole, the slurry and foreign matter with a size larger than the discharge hole are left on the conveyor belt, and the first slurry with a size smaller than the diameter of the discharge hole is overflow-crushed step by step.

[0026] According to one embodiment of the present invention, before the flocculation step, the prepared flocculant is first mixed with the second slurry, and the solid and liquid in the second slurry are separated by stirring and dispersion.

[0027] According to one embodiment of the present invention, the flocculant is ferric sulfate or a mixture of ferric sulfate and cationic PAM, and the volume ratio between the slurry and the flocculant is 1000:5-20.

[0028] According to one embodiment of the present invention, the stirring speed during the stirring and dispersing is 20 to 50 r / min, the dispersing speed is 1000 to 1600 r / min, and the dispersing time is 10 to 30 min.

[0029] By dispersing, stirring and flocculating the slurry and then performing filter pressing, the moisture content in the filter cake can be reduced, and the sticking and agglomeration phenomena during the drying process can be alleviated.

[0030] According to one embodiment of the present invention, the filter pressing includes extrusion filter pressing.

[0031] According to one embodiment of the present invention, the filtration pressure is 0.2 to 0.5 MPa, and the filtration time is 10 to 30 minutes.

[0032] According to one embodiment of the present invention, the method further comprises recovering the solvent in the liquid phase obtained after solid-liquid separation to obtain a first waste liquid, and the first waste liquid is used to prepare a flocculant.

[0033] According to one embodiment of the present invention, the filter cake obtained by the method has a low moisture content and is not easy to clog the filter screen; the filter cake has a low solvent content, which avoids excessive solvent content, resulting in combustion during the subsequent high-temperature calcination process, generating a large amount of nitrogen oxides and carbon oxides to pollute the environment.

[0034] According to one embodiment of the present invention, the filter cake is dried and crushed to obtain a powdery material, which increases the pyrolysis contact area of ​​the next process and improves the pyrolysis effect.

[0035] According to one embodiment of the present invention, the drying process is divided into two stages: the first stage is performed at a temperature of 100-160°C for 0.5-2 hours; the second stage is performed at a temperature of 160-220°C for 2-6 hours. The waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0036] The two-stage drying reduces wall sticking and caking by gradually increasing the temperature, thereby extending the maintenance period of the equipment.

[0037] According to one embodiment of the present invention, the volatilized gas during the drying is condensed and distilled, and the solvent is separated to obtain a second waste liquid, and the second waste liquid is used to prepare a flocculant.

[0038] The solvent generated during the filtration and drying process can be purified by distillation to achieve solvent recycling, and the wastewater generated after distillation can also be recycled in the preparation of the flocculant solution, achieving cyclic recycling. The distillation is preferably rectification, and the solvent is preferably NMP solution.

[0039] According to one embodiment of the present invention, more than 98% of NMP can be separated and recovered during the slurry filtration and filter cake double-cone vacuum drying stages. The recovered NMP is sold to a certain concentration through atmospheric distillation to generate revenue. Only less than 2% of the NMP enters the heat treatment stage, greatly reducing the burden of tail gas treatment, and the recovered powder fully meets the requirements of the leaching process.

[0040] According to one embodiment of the present invention, the pyrolysis includes multiple stages of pyrolysis, preferably four stages of pyrolysis, the first stage pyrolysis temperature is 300-360°C, the second stage pyrolysis temperature is 400-600°C, the third stage pyrolysis temperature is 400-600°C, and the fourth stage pyrolysis temperature is 260-320°C.

[0041] According to one embodiment of the present invention, the four-stage pyrolysis is first performed at 300-360°C to volatilize the residual NMP and moisture in the crushed powder, and then pyrolyzed at 400-600°C to pyrolyze the conductive agent, PVDF, etc. contained in the filter residue to remove the conductive agent and PVDF.

[0042] This step-by-step heating process reduces NMP decomposition during the pyrolysis process, thereby reducing tail gas production and allowing for NMP recycling, saving costs. Furthermore, this pyrolysis method effectively reduces agglomeration, ensuring a thorough pyrolysis process, effectively removing impurities from the cathode powder, and improving the purity of the recovered cathode powder.

[0043] According to one embodiment of the present invention, the four-stage pyrolysis can avoid the volatilization of lithium, thereby effectively recovering lithium.

[0044] The pyrolysis can remove residual solvent and moisture in the powdery material and polyvinylidene fluoride (PVDF) and conductive agent originally contained in the waste material.

[0045] According to one embodiment of the present invention, the solid content of the second slurry is 20% to 40%.

[0046] During the slurry recovery process, the solid content has a greater impact on production capacity. If the solid content is too low, the slurry will contain more liquid, resulting in less filter cake each time the filter is pressed; if the solid content is too high, the flocculation and dispersion effect will be poor, and the solid-liquid separation will not be obvious. During the filter press, the liquid cannot be effectively separated from the solid, resulting in a high water content in the filter cake, which will cause sticking to the wall, agglomeration, long drying time, high energy consumption, and low production efficiency during drying.

[0047] After the waste slurry containing foreign matter such as plastic and cloth is shredded, the foreign matter is separated from the waste slurry through a bubble drum, and the waste slurry is preliminarily crushed. Then, through step-by-step overflow and bubble crushing dispersion, the solid content and particle size of the prepared slurry can be effectively controlled, so that the solid content of the slurry is maintained between 20% and 40%, ensuring the subsequent flocculation and filtration effects, and ensuring production capacity.

[0048] This method enables continuous, large-scale processing of waste lithium battery slurry, simplifying the slurry recovery process. It also effectively separates and recycles the positive electrode material and solvent, reducing recycling costs. The entire process is environmentally friendly and energy-efficient, facilitating subsequent processing of the positive electrode powder. The recovered positive electrode powder contains a total Ni, Co, Mn, and Li metal content exceeding 50%, demonstrating significant recycling value. NMP is a preferred solvent.

[0049] In order to solve the second technical problem, the technical solution adopted by the present invention is:

[0050] A device for recovering positive electrode materials using the method described above,

[0051] It includes a first crusher, a bubble crusher, a stirring kettle, a filter press, a double-cone drying device, a distillation tower, a second crusher and a pyrolysis furnace connected in sequence;

[0052] A preparation tank is connected between the stirring kettle and the distillation tower;

[0053] A condensing device is connected between the double-cone drying device and the distillation tower;

[0054] The distillation tower is connected to a liquid storage tank;

[0055] The pyrolysis furnace is connected to tail gas treatment equipment.

[0056] According to one embodiment of the present invention, the first crusher is a double-shaft shredder, and the second crusher is a double-shaft shredder.

[0057] According to one embodiment of the present invention, two temperature zones are provided in the double-cone drying equipment.

[0058] According to one embodiment of the present invention, the pyrolysis furnace is a multi-stage heating rotary kiln.

[0059] According to one embodiment of the present invention, the discharge end of the first crusher is connected to the feed end of the bubble crusher through a conveyor, and the conveyor is used to convey the waste pulp shredded by the first crusher to the bubble crusher. The conveyor is arranged to be inclined upward from the discharge end of the first crusher to the feed end of the bubble crusher, and a number of partitions are evenly spaced on the conveyor belt on the conveyor to prevent the shredded pulp from slipping during the conveying process.

[0060] According to one embodiment of the present invention, the preparation tank is used to prepare the flocculant solution.

[0061] According to one embodiment of the present invention, the bubble crusher includes a conveyor belt, a cleaning area, a crushing area and a slurry pool;

[0062] One end of the conveyor belt is located below the discharge port of the first crusher, and the other end is located at the discharge port of the bubble crusher;

[0063] The conveyor belt passing through the cleaning area is provided with a plurality of discharge holes, and the first slurry dropped from the discharge holes enters the cleaning area below the discharge holes.

[0064] According to one embodiment of the present invention, equidistant partitions are provided on the conveyor belt to prevent the crushed pulp from sliding during transportation, and the conveyor belt is circulated by a motor and a chain.

[0065] According to one embodiment of the present invention, a bubble drum is provided at the bottom of the bubble crusher, and a plurality of discharge holes are opened on the conveyor belt. The cleaned slurry falls from the conveyor belt through the discharge holes into the cleaning area below the conveyor belt, and then falls into the slurry pool. The cleaned rags, plastics, etc. are transported to the outlet through the conveyor belt and fall into the slag collection bucket.

[0066] One of the technical solutions has at least one of the following advantages or beneficial effects:

[0067] 1. After the waste slurry containing foreign matter such as plastic and cloth is shredded, the foreign matter is separated from the waste slurry through a bubble drum, and the waste slurry is preliminarily crushed. Then, through step-by-step overflow and bubble crushing dispersion, the solid content and particle size of the prepared slurry can be effectively controlled, so that the solid content of the slurry is maintained between 20% and 40%, ensuring the subsequent flocculation and filter pressing effects, and ensuring production capacity;

[0068] 2. The method utilizes multi-stage pyrolysis, which reduces solvent decomposition during the pyrolysis process, thereby reducing tail gas generation and allowing for solvent recycling, saving costs. Furthermore, multi-stage pyrolysis effectively reduces pyrolysis agglomeration, ensuring full pyrolysis and effectively removing impurities from the cathode powder, thereby improving the purity of the recovered cathode powder.

[0069] 3. In the method, more than 98% of the solvent can be separated and recovered during the slurry filtration and filter cake double-cone vacuum drying stages. The recovered solvent is then distilled at atmospheric pressure to a certain concentration and can be sold to generate revenue. Only less than 2% of the solvent enters the heat treatment stage, significantly reducing the burden of tail gas treatment. The recovered powder fully meets the requirements of the leaching process.

[0070] 4. The method enables continuous, large-scale processing of waste lithium battery slurry, simplifying the slurry recovery process. It also effectively separates and recycles the positive electrode material and solvent, reducing recycling costs. The entire process is environmentally friendly and energy-efficient, facilitating subsequent processing of the positive electrode powder. The recovered positive electrode powder contains a total Ni, Co, Mn, and Li metal content exceeding 50%, demonstrating significant recycling value. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0072] Figure 1 This is a process flow chart of the method for recovering positive electrode material from lithium battery slurry in Example 1.

[0073] Figure 2 This is a structural diagram of the device for recovering positive electrode materials in Example 5.

[0074] Figure 3 Example 5 Bubble breaker structure diagram.

[0075] Reference numerals:

[0076] 100-first crusher, 200-bubble crusher, 210-cleaning area, 220-conveyor belt, 230-slurry pool, 240-crushing area, 250-overflow plate, 260-slag collection barrel, 300-mixing kettle, 400-preparation tank, 500-filter press, 600-condensation equipment, 700-double-cone drying equipment, 800-distillation tower, 900-liquid storage tank, 1000-second crusher, 1100-exhaust gas treatment equipment, 1200-pyrolysis furnace, 1300-packaging machine. DETAILED DESCRIPTION

[0077] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions.

[0078] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0079] In the description of the present invention, if there are descriptions of first, second, third, etc., they are only used to distinguish technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0080] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0081] In the description of the present invention, it should be noted that, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meaning of the terms in the present invention based on the specific content of the technical solution.

[0082] The NMP solution with a concentration of 70% to 90% in the embodiment is a mixed solvent of NMP and water.

[0083] Example 1

[0084] A method for recovering positive electrode material from lithium battery slurry comprises the following steps:

[0085] S1: Take 1000L of waste pulp containing foreign matter such as plastic and cloth and shred it in a double-shaft shredder, with the A-shaft shredding speed of 15r / min and the B-shaft shredding speed of 25r / min;

[0086] S2: The shredded waste pulp is mixed with 2000L of 70% to 85% NMP solution, and then bubble crushing is performed at a bubble crushing pressure of 0.4Mpa to peel off the waste pulp adhering to the foreign matter and crush the waste pulp, and then further crush it through step-by-step overflow;

[0087] S3: Using ferric sulfate as a flocculant, the volume ratio of slurry to flocculant was 1000:5, and the dispersion stirring flocculation was carried out, wherein the stirring speed was 20 r / min, the dispersion speed was 1000 r / min, and the dispersion time was 30 min;

[0088] S4: The flocculated slurry is squeezed and filtered for 30 minutes at a filter pressure of 0.2 MPa to obtain a filter cake and a filtrate. The filtrate is a mixed solution of NMP and water. The NMP and wastewater are separated by distillation. The wastewater is used as recycled water and mixed with a flocculant to prepare a flocculant solution.

[0089] S5: Dry the filter cake in two stages to obtain a solid dry material. The first stage is dried at 100°C for 2 hours, and the second stage is dried at 160°C for 6 hours.

[0090] S6: crushing the block solid dry material to obtain powdery material to increase the pyrolysis contact area;

[0091] S7: Pyrolysis of the powdered material is performed using a four-stage pyrolysis process, with the first stage pyrolysis temperature at 300°C, the second stage pyrolysis temperature at 400°C, the third stage pyrolysis temperature at 400°C, and the fourth stage pyrolysis temperature at 260°C to obtain a finished powder material. Waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0092] S8: Packing the obtained finished powder material.

[0093] Example 2

[0094] A method for recovering positive electrode material from lithium battery slurry comprises the following steps:

[0095] S1: Take 2000L of waste pulp containing foreign matter such as plastic and cloth and shred it in a double-shaft shredder, with the A-shaft shredding speed at 25r / min and the B-shaft shredding speed at 15r / min;

[0096] S2: The shredded waste pulp is mixed with 1000L of 70% to 90% NMP solution, and then subjected to bubble crushing at a bubble crushing pressure of 0.8 MPa to peel off the waste pulp adhering to the foreign matter and crush the waste pulp. The waste pulp is then further crushed into pulp of the required size and solid content through step-by-step overflow crushing;

[0097] S3: using ferric sulfate as a flocculant, dispersing and stirring flocculation was performed with a volume ratio of slurry to flocculant of 1000:20, wherein the stirring speed was 50 r / min, the dispersion speed was 1600 r / min, and the dispersion time was 10 min;

[0098] S4: The flocculated slurry is squeezed and filtered for 10 minutes at a filter pressure of 0.5 MPa to obtain a filter cake and a filtrate. The filtrate is a mixed solution of NMP and water. The NMP and wastewater are separated by distillation. The wastewater is used as recycled water and mixed with a flocculant to prepare a flocculant solution.

[0099] S5: Dry the filter cake in two stages to obtain a solid dry material. The first stage is dried at 160°C for 0.5 h, and the second stage is dried at 220°C for 2 h.

[0100] S6: crushing the dried filter cake to obtain powdery material to increase the pyrolysis contact area;

[0101] S7: Pyrolysis of the powdered material is performed using a four-stage pyrolysis process, with the first stage pyrolysis temperature at 360°C, the second stage pyrolysis temperature at 600°C, the third stage pyrolysis temperature at 600°C, and the fourth stage pyrolysis temperature at 320°C to obtain a finished powder material. Waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0102] S8: Packing the obtained finished powder material.

[0103] Example 3

[0104] A method for recovering positive electrode material from lithium battery slurry comprises the following steps:

[0105] S1: Take 1500L of waste pulp containing foreign matter such as plastic and cloth and shred it in a double-shaft shredder, with the A-shaft shredding speed at 20r / min and the B-shaft shredding speed at 20r / min;

[0106] S2: The shredded waste pulp is mixed with 1500L of 70% to 85% NMP solution, and then subjected to bubble crushing at a bubble crushing pressure of 0.6 MPa to remove the waste pulp adhering to the foreign matter and crush the waste pulp. The waste pulp is then further crushed into slurry with the required size and solid content through step-by-step overflow crushing;

[0107] S3: using ferric sulfate as a flocculant, dispersing and stirring flocculation was performed with a volume ratio of slurry to flocculant of 1000:10, wherein the stirring speed was 30 r / min, the dispersion speed was 1300 r / min, and the dispersion time was 20 min;

[0108] S4: The flocculated slurry is squeezed and filtered for 20 minutes at a filter pressure of 0.3 MPa to obtain a filter cake and a filtrate. The filtrate is a mixed solution of NMP and water. The NMP and wastewater are separated by distillation. The wastewater is used as recycled water and mixed with a flocculant to prepare a flocculant solution.

[0109] S5: Dry the filter cake in two stages to obtain a solid dry material. The first stage is dried at a temperature of 130°C for 1.5 hours, and the second stage is dried at a temperature of 180°C for 5 hours to reduce the moisture content of the filter cake.

[0110] S6: crushing the block solid dry material to obtain powdery material to increase the pyrolysis contact area;

[0111] S7: Pyrolysis of the powdered material is performed using a four-stage pyrolysis process, with the first stage pyrolysis temperature at 320°C, the second stage pyrolysis temperature at 450°C, the third stage pyrolysis temperature at 450°C, and the fourth stage pyrolysis temperature at 280°C to obtain a finished powder material. Waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0112] S8: Packing the obtained finished powder material.

[0113] Example 4

[0114] A method for recovering positive electrode material from lithium battery slurry comprises the following steps:

[0115] S1: 1800L of waste pulp containing foreign matter such as plastic and cloth was shredded in a double-shaft shredder, with the A-shaft shredding speed at 22r / min and the B-shaft shredding speed at 20r / min.

[0116] S2: The shredded waste pulp is mixed with 1200L of 70% to 90% NMP solution, and then bubble crushing is performed at a bubble crushing pressure of 0.5 MPa to remove the waste pulp adhering to the foreign matter from the foreign matter and crush the waste pulp. The waste pulp is then further crushed into slurry with the required size and solid content through step-by-step overflow crushing;

[0117] S3: Using ferric sulfate and cationic PAM as flocculants, the volume ratio of slurry to flocculant was 1000:15, and the dispersion stirring flocculation was carried out, wherein the stirring speed was 40 r / min, the dispersion speed was 1500 r / min, and the dispersion time was 10 min;

[0118] S4: The flocculated slurry is squeezed and filtered for 25 minutes at a filter pressure of 0.4 MPa to obtain a filter cake and a filtrate. The filtrate is a mixed solution of NMP and water. The NMP and wastewater are separated by distillation. The wastewater is used as recycled water and mixed with a flocculant to prepare a flocculant solution.

[0119] S5: Dry the filter cake in two stages to obtain a solid dry material. The first stage is dried at 140°C for 1 hour, and the second stage is dried at 200°C for 4 hours.

[0120] S6: crushing the block solid dry material to obtain powdery material to increase the pyrolysis area;

[0121] S7: Pyrolysis the powdered material using four stages of pyrolysis, with the first stage at 350°C, the second stage at 500°C, the third stage at 500°C, and the fourth stage at 300°C to obtain a finished powder material. Waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0122] S8: Packing the obtained finished powder material.

[0123] Example 5

[0124] The device for recovering the positive electrode material comprises:

[0125] A first crusher 100 for shredding foreign matter such as plastic and cloth, wherein the first crusher 100 is a double-shaft shredder;

[0126] The bubble crusher 200 has a double-shaft shredder discharge end connected to the bubble crusher 200 feed end via a conveyor. The conveyor is used to convey the waste pulp shredded by the shredder into the bubble crusher 200. The conveyor is arranged upwardly and tilted from the double-shaft shredder discharge end to the bubble crusher 200 feed end. A plurality of partitions are evenly spaced on the conveyor belt to prevent the shredded pulp from slipping during the conveying process.

[0127] The bubble breaker 200 includes a conveyor belt 220 for conveying shredded pulp, a pulp cleaning device, and a pulp pool 230 located below the conveyor belt 220;

[0128] One end of the conveyor belt 220 is located below the shredder discharge port, and the other end extends upward at a certain angle to the slurry cleaning device discharge port. Equidistant partitions are provided on the conveyor belt 220 to prevent the crushed slurry from slipping during transportation.

[0129] The conveyor belt 220 is circulated by a motor and a chain, and at least a portion of the conveyor belt 220 is located in the slurry cleaning device;

[0130] A bubble drum is provided at the bottom of the bubble crusher 200, and a plurality of discharge holes are provided on the conveyor belt 220. The cleaned slurry falls from the conveyor belt 220 through the discharge holes into the cleaning area 210 below the conveyor belt 220, and then falls into the slurry pool 230. The cleaned rags, plastics, etc. are transported to the outlet through the conveyor belt 220 and fall into the slag collection bucket 260.

[0131] The equipment used in the step-by-step overflow crushing step is as follows:

[0132] A plurality of overflow plates 250 are provided in the slurry pool 230. The overflow plates 250 divide the slurry pool 230 into a plurality of crushing zones 240. A bubble drum is installed in each crushing zone 240.

[0133] An overflow port for slurry overflow is left between the overflow plate 250 and the top of the slurry pool 230. The height of the overflow plate 250 arranged from the feed end to the discharge end of the slurry pool 230 gradually decreases, so that the waste slurry is separated from foreign matter and the waste slurry is gradually crushed into slurry of a size and solid content that meets the requirements;

[0134] A stirring tank 300 connected to the bubble crusher 200, with a buffer tank provided between the bubble crusher 200 and the stirring tank 300;

[0135] The stirring tank 300 is used for dispersion and stirring to fully flocculate the solid components in the slurry and achieve preliminary solid-liquid separation;

[0136] A preparation tank 400 connected to the stirring tank 300 is used to prepare a flocculant solution;

[0137] The filter press 500 is connected to the stirring tank 300, and the filter press 500 is used to squeeze and filter the flocculated slurry to obtain a filter cake and a filtrate, and the filtrate is a mixed solution of NMP and water;

[0138] The double cone drying device 700 is connected to the filter press 500. The double cone drying device 700 adopts a two-stage gradual temperature increase drying method to dry the filter cake to obtain a block of solid dry material, reduce its moisture content, and reduce the phenomenon of sticking to the wall and agglomeration;

[0139] The condensing device 600 connected to the double cone drying device 700 is used to condense the NMP and water vapor generated during the drying process;

[0140] The second crusher 1000 connected to the double-cone drying device 700 is used to crush the dried solid block material into powdery material to increase the pyrolysis contact area;

[0141] The pyrolysis furnace 1200 pyrolyzes the crushed powdered material to remove impurities such as adhesives and conductive agents to obtain finished powder materials. The tail gas generated during the pyrolysis process is treated by the tail gas treatment equipment 1100 connected to the pyrolysis furnace 1200 and then discharged. The pyrolysis furnace 1200 is a multi-stage heating rotary kiln. The material is pyrolyzed by gradually increasing the temperature to reduce the generation of tail gas, lower the ignition loss rate, and reduce wall sticking and agglomeration.

[0142] The packaging machine 1300 is used to package the prepared finished powder material.

[0143] The process also includes a distillation tower 800, the feed end of which is connected to the filter press 500 and the condensing device 600. The wastewater and NMP solution during the filtration process and after condensation enter the distillation tower 800 for purification and separation of the NMP solution and water. The top of the distillation tower 800 is connected to the preparation tank 400. The separated and purified water enters the preparation tank 400 as recycled water to prepare the flocculant solution. The bottom of the distillation tower 800 is connected to the liquid storage tank 900, which is used to store the NMP solution after distillation and purification.

[0144] Comparative Example 1

[0145] Method for recovering positive electrode material from lithium battery slurry,

[0146] The following steps are involved:

[0147] S1: Take 500L of waste pulp containing foreign matter such as plastic and cloth and shred it in a double-shaft shredder. The speed of the A-shaft shredder is 15r / min and the speed of the B-shaft shredder is 25r / min.

[0148] S2: The shredded waste pulp is mixed with 2500L of 70% to 85% NMP solution, and then bubble crushing is performed at a bubble crushing pressure of 0.4Mpa to peel off the waste pulp adhering to the foreign matter and crush the waste pulp, and then further crush it through step-by-step overflow;

[0149] S3: Using ferric sulfate as a flocculant, the volume ratio of slurry to flocculant was 1000:5, and the dispersion stirring flocculation was carried out, wherein the stirring speed was 20 r / min, the dispersion speed was 1000 r / min, and the dispersion time was 30 min;

[0150] S4: The flocculated slurry is squeezed and filtered for 30 minutes at a filter pressure of 0.2 MPa to obtain a filter cake and a filtrate. The filtrate is an aqueous NMP solution. The NMP and wastewater are separated by distillation. The wastewater is used as recycled water and mixed with a flocculant to prepare a flocculant solution.

[0151] S5: Dry the filter cake in two stages to obtain a solid dry material. The first stage is dried at 100°C for 2 hours, and the second stage is dried at 160°C for 6 hours.

[0152] S6: crushing the block solid dry material to obtain powdery material to increase the pyrolysis contact area;

[0153] S7: Pyrolysis of the powdered material is performed using a four-stage pyrolysis process, with the first stage pyrolysis temperature at 300°C, the second stage pyrolysis temperature at 400°C, the third stage pyrolysis temperature at 400°C, and the fourth stage pyrolysis temperature at 260°C to obtain a finished powder material. Waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0154] S8: Packing the obtained finished powder material.

[0155] Comparative Example 2

[0156] A method for recovering positive electrode material from lithium battery slurry comprises the following steps:

[0157] S1: Take 2500L of waste pulp containing foreign matter such as plastic and cloth and shred it in a double-shaft shredder, with the A-shaft shredding speed at 25r / min and the B-shaft shredding speed at 15r / min;

[0158] S2: The shredded waste pulp is mixed with 500L of 70% to 90% NMP solution, and then subjected to bubble crushing at a bubble crushing pressure of 0.8 MPa to peel off the waste pulp adhering to the foreign matter and crush the waste pulp. The waste pulp is then further crushed into slurry with the required size and solid content through step-by-step overflow crushing;

[0159] S3: using ferric sulfate as a flocculant, dispersing and stirring flocculation was performed with a volume ratio of slurry to flocculant of 1000:20, wherein the stirring speed was 50 r / min, the dispersion speed was 1600 r / min, and the dispersion time was 10 min;

[0160] S4: The flocculated slurry is squeezed and filtered for 10 minutes at a filter pressure of 0.5 MPa to obtain a filter cake and a filtrate. The filtrate is an aqueous NMP solution. The NMP and wastewater are separated by distillation. The wastewater is used as recycled water and mixed with a flocculant to prepare a flocculant solution.

[0161] S5: Dry the filter cake in two stages to obtain a solid dry material. The first stage is dried at 160°C for 0.5 h, and the second stage is dried at 220°C for 2 h.

[0162] S6: crushing the dried filter cake to obtain powdery material to increase the pyrolysis contact area;

[0163] S7: Pyrolysis of the powdered material is performed using a four-stage pyrolysis process, with the first stage pyrolysis temperature at 360°C, the second stage pyrolysis temperature at 600°C, the third stage pyrolysis temperature at 600°C, and the fourth stage pyrolysis temperature at 320°C to obtain a finished powder material. Waste gas generated during the pyrolysis process is discharged after exhaust gas treatment.

[0164] S8: Packing the obtained finished powder material.

[0165] Performance testing:

[0166] The finished powder materials obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were tested, and the test results are shown in Table 1.

[0167] Table 1 Parameters of recycled materials in Examples 1 to 4

[0168]

[0169]

[0170] in:

[0171] ① Solid content - the ratio of the solid content in the slurry obtained after washing and dispersion in step S2 to the total amount of slurry;

[0172] ② Moisture content - the ratio of the liquid content in the filter cake to the total amount of filter cake after filtration;

[0173] ③ Loss on ignition rate - the loss rate of the material after drying compared to before drying;

[0174] ④ Wall sticking rate after drying - the ratio of wall sticking amount after drying to the total material;

[0175] ⑤ Loss on ignition rate - the loss rate of the material after pyrolysis compared to before pyrolysis;

[0176] ⑥ Wall adhesion rate after pyrolysis - the ratio of wall adhesion after pyrolysis to the total material;

[0177] ⑦ Agglomeration after pyrolysis - Observe with naked eyes whether the material in the pyrolysis furnace is agglomerated after pyrolysis;

[0178] ⑧Ni, Co, Mn, Ni content - refers to the content of Ni, Co, Mn, and Li in the positive electrode powder obtained after pyrolysis.

[0179] The contents of Ni, Co, Mn and Ni were detected by inductively coupled plasma optical emission spectrometry (IPC-OES).

[0180] As can be seen from Table 1, the solid content of the slurry after washing and dispersion in Examples 1 to 4 is between 20% and 40%, which can ensure the subsequent flocculation and filter pressing effects while ensuring production capacity; the moisture content is controlled between 20% and 30%, which can reduce the wall sticking and caking phenomena that occur during the drying process, and control the drying time to avoid energy consumption caused by excessive drying time; the loss on ignition is controlled below 4%, and the loss on ignition is controlled below 3%, indicating that the loss on ignition and loss on ignition are both small, less tail gas is generated during the pyrolysis process, and the pyrolysis is relatively sufficient.

[0181] In addition, in the prior art, direct incineration is used to treat waste, and the direct incineration loss rate is 8.5-11.2%.

[0182] The total content of Ni, Co, Mn and Li metals in the positive electrode powder obtained after pyrolysis is above 50%, indicating a good recycling effect and great recycling value.

[0183] The above are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for recovering positive electrode material from lithium battery slurry, characterized in that: The following steps are involved: The waste is shredded, a solvent is added, and the bubbles are broken to obtain a first slurry; Screening is performed through the discharge hole; The first slurry having a size smaller than the diameter of the discharge hole is overflow-crushed step by step to obtain a second slurry; The second slurry is mixed with a flocculant, and after stirring, dispersing, flocculating, and solid-liquid separation, a solid phase portion is collected; The solid phase is dried, crushed, and pyrolyzed to obtain the positive electrode material; The solid content of the second slurry is 20% to 40%; The pyrolysis includes multiple stages of pyrolysis, the first stage pyrolysis temperature is 300-360°C, the second stage pyrolysis temperature is 400-600°C, the third stage pyrolysis temperature is 400-600°C, and the fourth stage pyrolysis temperature is 260-320°C; The pressure of bubble breaking is 0.4-0.8Mpa; During the flocculation process, the volume ratio between the second slurry and the flocculant is 1000:5-20; The stirring speed during the stirring and dispersing is 20 to 50 r / min, the dispersing speed is 1000 to 1600 r / min, and the dispersing time is 10 to 30 min; The drying is divided into two stages, the first stage has a drying temperature of 100-160° C. and a drying time of 0.5-2 hours; the second stage has a drying temperature of 160-220° C. and a drying time of 2-6 hours.

2. The method according to claim 1, characterized in that: The solvent includes at least one of N-methylpyrrolidone, propylene glycol methyl ether acetate, and propylene glycol methyl ether.

3. The method according to claim 1, characterized in that: The method further comprises recovering the solvent in the liquid phase obtained after solid-liquid separation to obtain a first waste liquid, and the first waste liquid is used to prepare a flocculant.

4. The method according to claim 3, characterized in that: The volatilized gas during the drying is condensed and distilled to separate the solvent to obtain a second waste liquid, which is used to prepare a flocculant.

5. A device for recovering positive electrode materials using the method according to any one of claims 1 to 4, characterized in that: It comprises a first crusher (100), a bubble crusher (200), a stirring kettle (300), a filter press (500), a double cone drying device (700), a distillation tower (800), a second crusher (1000) and a pyrolysis furnace (1200) which are connected in sequence; The bubble crusher (200) comprises a conveyor belt (220), a cleaning area (210), a crushing area (240) and a slurry pool (230); One end of the conveyor belt (220) is located below the discharge port of the first crusher (100), and the other end is located at the discharge port of the bubble crusher (200); The conveyor belt (220) passing through the cleaning area (210) is provided with a plurality of discharge holes, and the first slurry falling from the discharge holes enters the cleaning area (210) below the discharge holes and then falls into the slurry pool (230); The bubble crusher (200) is provided with a bubble drum at the bottom; A plurality of overflow plates (250) are arranged in the slurry pool (230), and the overflow plates (250) divide the slurry pool (230) into a plurality of crushing zones (240), and a bubble drum is installed in each crushing zone (240); An overflow port for slurry overflow is left between the overflow plate (250) and the top of the slurry pool (230), and the height of the overflow plate (250) arranged from the feed end to the discharge end of the slurry pool (230) gradually decreases.

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