Processing method of artificial graphite sieve loading material

Abstract

The invention relates to a processing method of artificial graphite sieve loading materials. The method comprises the following steps: (1) rough crushing: putting the artificial graphite sieve loading materials into a jaw type rough crushing machine for rough crushing; (2) screening: carrying out ultrasonic vibration screening on the coarsely crushed material by using a 10-50-mesh screen to obtain an oversize material and an undersize material; and (3) grading is conducted, specifically, the undersize materials are placed in a grading machine to be graded, and equipment parameters are as follows: the fan frequency is 25-32 Hz, the feeding frequency is 4-10 Hz, and the grading frequency is 4-8 Hz. According to the method provided by the invention, high-hardness resistance materials and artificial graphite products mixed in the production process of the artificial graphite negative electrode are efficiently separated, industrialization is easy to realize, the utilization rate of raw materials can be increased, and the production cost is reduced. The obtained negative electrode material can meet the application requirements of mainstream lithium ion batteries in the aspects of granularity, specific surface area, specific capacity and first coulombic efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of negative electrode materials for lithium ion batteries, and in particular to a method for processing material on an artificial graphite screen. Background Art

[0002] In the production process of graphite negative electrode for lithium-ion batteries, the finished graphite material collected after the graphitization process may introduce substances that do not meet the target product index requirements due to reasons such as broken crucibles and material agglomeration, and needs to be further processed through screening and demagnetization processes. Among them, after the screening process, the residual material on the vibrating screen (called "screened material") contains a large amount of resistor material and agglomerated graphitized material, which is generally difficult to effectively separate and reuse.

[0003] To this end, a new material rapid processing process is designed. In the process of rough crushing of the screen material, the resistor material can play the role of grinding beads due to its high hardness, promoting the grinding and crushing of the agglomerated graphite powder, and then quickly screened in the subsequent small mesh screening process. After vibration screening, the residual material on the screen and the material under the screen are collected separately, and the material under the screen is graded to obtain qualified artificial graphite products. The main component of the residual material on the screen is the resistor material, which can be further used as a recarburizer, so that the material can be fully recycled and reused.

[0004] CN115924906A discloses a method for processing graphite sieve material, comprising the following steps: (1) kneading the graphite sieve material to obtain material A; (2) screening the material A for the first time, taking the sieve material, dispersing and depolymerizing it with a disperser to obtain material B, wherein the speed of the disperser is 100-400r / min, and the time for dispersion and depolymerization is 10-90min; (3) screening the material B for the second time to obtain the sieve material with a suitable particle size. Although this scheme can reuse the graphite sieve material and avoid the damage to the material surface morphology during the processing process as much as possible, the preparation process of this scheme is complicated, the preparation cost is high, and the increase in separation difficulty caused by the mixing of a large amount of resistor materials in the actual production process is not considered.

[0005] CN115814921A discloses a method for processing and utilizing the oversize material by a rod-pin grinding and grading process. This solution has little damage to the external morphology of the material, and the oversize material after treatment has a complete crystal form, meets the national standard, and is applied to the negative electrode material of lithium-ion batteries, with a high discharge specific capacity and initial efficiency. However, the oversize material processed by the method only targets large particles that are bonded together due to physical agglomeration, and does not take into account the increased difficulty of separation caused by the mixing of a large amount of resistor materials in the actual production process. Summary of the invention

[0006] Technical Purpose

[0007] The present invention aims to solve at least one defect existing in the prior art. For this purpose, the technical problem solved by the present invention is to provide a method for recycling the artificial graphite screen oversize material, which can effectively solve the problems of high difficulty in separating the resistance material and artificial graphite in the screen oversize material and high process cost, and the obtained negative electrode product can meet the application requirements of lithium-ion batteries in terms of particle size, specific surface area, specific capacity and first Coulomb efficiency.

[0008] Technical solution

[0009] To achieve the above object, the present invention provides a method for treating artificial graphite screen oversize material, and the method includes the following steps:

[0010] (1) Coarse crushing: placing the artificial graphite screen oversize material in a jaw coarse crusher for coarse crushing;

[0011] (2) Screening: using a 10-50 mesh screen to ultrasonically vibrate and screen the material after coarse crushing to obtain oversize material and undersize material;

[0012] (3) Classification: placing the undersize material in a classifier for classification, and the equipment parameters are: the fan frequency is 25-32 Hz, the feeding frequency is 4-10 Hz, and the classification frequency is 4-8 Hz.

[0013] In a specific embodiment, the artificial graphite screen oversize material in step (1) is the oversize residue after sieving and graphitization.

[0014] In a specific embodiment, D100 of the artificial graphite screen oversize material in step (1) is ≤ 3 cm.

[0015] In a specific embodiment, the coke raw material of the artificial graphite in step (1) is one or several of petroleum coke, needle coke, and pitch coke.

[0016] In a specific embodiment, the artificial graphite screen oversize material in step (1) includes a mixture of artificial graphite primary particles, artificial graphite secondary coating products, and resistance material.

[0017] In a specific embodiment, the mesh number of the screen in step (2) is 10-25 meshes, preferably 10-20 meshes, and more preferably 18 meshes.

[0018] In a specific embodiment, the method further includes: collecting the oversize material in step (2), and the collected oversize material can be further used as a carbon additive.

[0019] In a specific embodiment, the fan frequency in step (3) is 28-30 Hz, the feeding frequency is 5-8 Hz, and the classification frequency is 5-6 Hz.

[0020] In the specific implementation manner, the feeding frequency in step (3) is 5 Hz, and the classification frequency is 5 Hz.

[0021] Beneficial effects

[0022] The raw materials used in the present invention are the oversize materials after graphitization in the production process of artificial graphite, which mainly consist of large particle substances physically agglomerated and bonded together and resistance materials. These mixtures are recycled, and the material cost is low.

[0023] The oversize materials after graphitization are roughly broken in a jaw crusher. In this process, the resistance materials have high hardness themselves and can act as grinding beads to directly grind and break the agglomerated graphite powder. And the simple rough breaking process has basically no influence on the surface morphology of graphite, which is beneficial to ensuring the maintenance of the electrochemical performance of the artificial graphite product.

[0024] The materials after rough breaking are screened with a small mesh number, which avoids the problem that the screen with a large mesh number is easily damaged. At the same time, it is beneficial to greatly improve the production capacity and reduce the cost. After vibrating sieving, the residual materials on the screen and the materials under the screen are collected separately. At this time, the residual materials on the screen can be sold as a carbon additive to reduce the enterprise operation cost.

[0025] The materials under the screen are placed in a classifier for classification, and the obtained artificial graphite products show excellent electrochemical performance and can be sold equivalent to the original products.

[0026] The production method provided by the present invention realizes the efficient separation of the relatively hard resistance materials mixed in the production process of the artificial graphite negative electrode and the artificial graphite products, is easy to realize industrialization, can improve the utilization rate of raw materials, and reduce the production cost. The obtained negative electrode material can meet the application requirements of mainstream lithium-ion batteries in terms of particle size, specific surface area, specific capacity, and first Coulomb efficiency. Description of the drawings

[0027] Figure 1 FIG. is the SEM image of the materials after the oversize materials of artificial graphite based on petroleum coke are processed by the method of the present invention in Example 1.

[0028] Figure 2 FIG. is the SEM image of the materials after the oversize materials of artificial graphite based on pre-calcined needle coke are processed by the method of the present invention in Example 2.

[0029] Figure 3 FIG. is the SEM image of the materials after the oversize materials of artificial graphite based on post-calcined needle coke are processed by the method of the present invention in Example 3. Specific implementation manner

[0030] The present invention will be further described below in conjunction with the embodiments.

[0031] Materials and instruments:

[0032] Jaw Crusher: Dingli PE250*100

[0033] Ultrasonic Vibration Screen: Chaofeng CF-CXZS-106

[0034] Attritor: Zhengyuan Powder LHJ

[0035] Classifier: Zhengyuan Powder LHB

[0036] Laser Particle Size Analyzer: Malvern Mastersizer 3000

[0037] Specific Surface Area: Anton Paar, Model NOVA800

[0038] Method:

[0039] The particle size test is carried out according to Appendix A of GB / T 24533-2019.

[0040] The specific surface area is measured according to GB / T 19587.

[0041] Example 1

[0042] Recycling method of oversize material of artificial graphite sieve, including steps:

[0043] Coarse Crushing: Using the oversize material after graphitization of artificial graphite based on petroleum coke as raw material A (the particle size D100 of raw material A ≤ 3 cm), and placing raw material A in a jaw crusher for coarse crushing.

[0044] Screening: The material after coarse crushing is ultrasonically vibration screened using a 18-mesh sieve; the residual oversize material is collected and can be further used as a carburizer.

[0045] Classification: The undersize material obtained by screening is placed in a Zhengyuan Powder LHB type classifier for classification. The equipment parameters are: fan frequency 30 Hz, feeding frequency 5 Hz, classification frequency 5 Hz. The required particle size of the finished product obtained from raw material A is: D50: 15 ± 1 μm, D100: ≤ 52 μm. The comprehensive recovery rate of oversize material recycling in this example is 75%, and the product morphology is shown in Figure 1 .

[0046] Example 2

[0047] The difference between Example 2 and Example 1 is that in the coarse crushing step, the raw material is changed to the oversize material after graphitization based on pre-calcined needle coke (denoted as raw material B, the particle size D100 of raw material B ≤ 3 cm). The required particle size of the final finished product is: D50: 12.5 ± 1 μm, D100: ≤ 45 μm. Other steps and processes are the same as those in Example 1. The comprehensive recovery rate is 78%, and the product morphology is shown in Figure 2 .

[0048] Example 3

[0049] The difference between Example 3 and Example 1 is that in the rough breaking step, the raw material is changed to the oversize material after graphitization based on calcined needle coke (denoted as raw material C, and the particle size D100 of raw material C ≤ 3 cm). The required particle size of the final product obtained is: D50: 12 ± 1 μm, D100: ≤ 52 μm. Other steps and processes are the same as those in Example 1, and the overall yield is 75%. The product morphology is shown in Figure 3 .

[0050] Example 4

[0051] The difference between Example 4 and Example 1 is that in the classification step, the classification frequency is changed to 9 Hz. Other steps and processes are the same as those in Example 1. The overall yield is 68%.

[0052] Example 5

[0053] The difference between Example 5 and Example 1 is that in the classification step, the fan frequency is changed to 34 Hz. Other steps and processes are the same as those in Example 1. The overall yield is 80%.

[0054] Comparative Example 1

[0055] Rough breaking: Place raw material A in a jaw crusher for rough breaking.

[0056] Screening: The material after rough breaking is subjected to ultrasonic vibration screening using a 18-mesh screen.

[0057] Fine grinding: Place the undersize material obtained by screening in a Zhengyuan Powder LHJ type mill for fine grinding. The equipment parameters are: main machine frequency is 19 Hz, fan frequency is 25 - 27 Hz, feeding frequency is 5 - 8 Hz, I classification frequency is 5 - 12 Hz, and II classification frequency is 51 Hz. Collect the material obtained after fine grinding, and its particle size is D50 = 9 - 15 μm, D100 = 100 - 700 μm.

[0058] Comparative Example 2

[0059] Rough breaking: Place raw material A in a jaw crusher for rough breaking.

[0060] Screening: The material after rough breaking is subjected to ultrasonic vibration screening using a 300 - 500-mesh screen.

[0061] Fine grinding: Place the undersize material obtained by screening in a Zhengyuan Powder LHJ type mill for fine grinding. The equipment parameters are: main machine frequency is 19 Hz, fan frequency is 25 - 27 Hz, feeding frequency is 5 - 8 Hz, I classification frequency is 5 - 12 Hz, and II classification frequency is 51 Hz. Collect the material obtained after fine grinding, and its particle size is D50 = 14.34 μm, D100 = 32.83 μm. The overall yield of this comparative example is 72%.

[0062] Comparative Example 3

[0063] The difference between Comparative Example 3 and Example 1 is that the mesh number of the sieve is changed to 300 - 500 meshes in the screening step, and the other steps and processes are the same as those in Example 1. The material obtained after classification is collected, and its particle size is D50 = 14.94 μm and D100 = 33.52 μm. The overall yield of this comparative example is 51%.

[0064] Comparative Example 4

[0065] The difference between Comparative Example 4 and Example 1 is that screening is not carried out after coarse crushing, and the other steps and processes are the same as those in Example 1. The material obtained after classification is collected, and its particle size is D50 = 12 - 16 μm and D100 = 100 - 300 μm. The overall yield of this comparative example is 45%.

[0066] Electrochemical performance test

[0067] For the artificial graphite anode materials with qualified particle size after being processed by the above examples, they are respectively mixed with acetylene black conductive agent and sodium carboxymethyl cellulose (CMC) binder in a weight ratio of 93:3:4 to form a slurry, and then coated on a copper foil to prepare an anode sheet. After drying, it is used as the anode. The electrolyte is obtained by dissolving 1 mol / L LiPF6 in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) with a ratio of 1:1 (w / w), and a lithium sheet is used as the counter electrode / reference electrode to assemble a lithium-ion battery for performance testing.

[0068] The test method is as follows: The electrical performance of the anode material is tested using a LANHE multi-channel battery test system, etc. The charge-discharge voltage is 0.01 - 2.0 V, and the charge-discharge rate is 0.1 C. The first discharge capacity and the first Coulombic efficiency are tested, and the results are shown in Table 1 below.

[0069] Table 1 Physical property indexes and electrochemical performance parameter table

[0070]

[0071] As can be seen from Table 1, by comparing Examples 1 - 5, for different types of graphitized products, the production methods of Examples 1 - 3 of the present invention are equally applicable, with complete crystal forms, qualified particle sizes, and electrochemical performance parameters meeting the production requirements (discharge capacity ≥ 345 mAh / g, first Coulombic efficiency ≥ 94%).

[0072] By comparing Example 1 and Comparative Example 1, it can be seen that if the third screening step is changed to fine grinding, since the resistor material with relatively high hardness still exists after screening, no matter how the parameters of the fine grinding equipment are adjusted, the particle size index of the obtained sample is always unqualified. Therefore, the solution of the coarse crushing - screening - fine grinding route to improve the comprehensive utilization rate of large particles in the oversize material is not feasible.

[0073] By comparing Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that using a sieve mesh with a large mesh number can screen out most of the resistor materials with relatively high hardness, so that qualified particle size artificial graphite products can be obtained in the subsequent fine grinding process, solving the problems that occurred in Comparative Example 1. However, sieve meshes with large mesh numbers are often prone to damage during the production process and have low production efficiency, which is not conducive to the goals of cost reduction and production capacity improvement.

[0074] By comparing Example 1 and Comparative Example 3, it can be seen that although replacing the sieve mesh with a large mesh number in the screening process can still obtain artificial graphite products with qualified particle size, its yield will be significantly reduced. It can be seen that choosing a sieve mesh with a smaller mesh number in the example is more conducive to improving the yield, saving costs, and is conducive to popularization and application.

[0075] By comparing Example 1 and Comparative Example 4, it can be seen that without screening after the raw material is coarsely crushed, the resistor material with relatively high hardness still exists and cannot be separated during classification, ultimately resulting in an unqualified D100 particle size index. Therefore, the screening step is indispensable.

[0076] The present invention is not limited to the above preferred embodiments, and various forms of transformation and improvement can also be carried out within the spirit defined by the claims and the specification of the present invention, which can solve the same technical problems and achieve the expected technical effects, so they will not be repeated. All solutions that can be directly or associatively thought of by those of ordinary skill in the art from the content disclosed in the present invention, as long as they are within the spirit defined by the claims, also belong to the protection scope of the present invention.

Claims

1. A processing method for feeding artificial graphite sieving materials, the method comprising the following steps: (1) Coarse crushing: Placing the artificial graphite sieving materials in a jaw coarse crusher for coarse crushing; (2) Screening: Using a 10 - 50 mesh sieve to perform ultrasonic vibration screening on the materials after coarse crushing to obtain over - sieve materials and under - sieve materials; (3) Classification: Placing the under - sieve materials in a classifier for classification, and the equipment parameters are: the fan frequency is 25 - 32 Hz, the feeding frequency is 4 - 10 Hz, and the classification frequency is 4 - 8 Hz.

2. The method according to claim 1, wherein, The artificial graphite sieving materials in step (1) are the residual over - sieve materials after graphitization that have passed through a sieve.

3. The method according to claim 1, wherein, The D100 of the artificial graphite sieving materials in step (1) is ≤ 3 cm.

4. The method according to claim 1, wherein The coke raw materials of the artificial graphite in step (1) are one or several of petroleum coke, needle coke, and pitch coke.

5. The method according to claim 1, wherein, The artificial graphite sieving materials in step (1) include a mixture of artificial graphite primary particles, artificial graphite secondary coating products, and resistance materials.

6. The method according to claim 1, wherein, The sieve mesh number in step (2) is 10 - 25 meshes.

7. The method according to claim 6, wherein, The sieve mesh number in step (2) is 10 - 20 meshes.

8. The method according to claim 6, wherein The sieve mesh number in step (2) is 18 meshes.

9. The method according to claim 1, wherein The method further includes: collecting the over - sieve materials in step (2), and the collected over - sieve materials are further used as a carbon - increasing agent.

10. The method according to claim 1, wherein, The fan frequency in step (3) is 28 - 30 Hz, the feeding frequency is 5 - 8 Hz, and the classification frequency is 5 - 6 Hz.

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