Production process of high-performance negative electrode coke

Abstract

The invention provides a high-performance negative electrode coke production process, and belongs to the technical field of negative electrode material production processes, and the high-performance negative electrode coke production process comprises the following steps: mixing solvent oil and maltha raw materials according to a solvent ratio of 0.9-1.2: 1, mixing the solvent oil and the maltha raw materials, carrying out settling separation through a settling tank to produce light-phase oil, heating the light-phase oil through a heating furnace, and feeding the light-phase oil into a light-phase tower, refined asphalt is produced from the tower bottom; heating the refined asphalt, fractionating in a fractionating tower, and producing coker oil from the bottom of the fractionating tower; the method comprises the following steps: heating coking oil, feeding the heated coking oil into a coke tower, and carrying out variable-temperature variable-pressure operation in a coking process to generate high-performance negative coke; by strictly controlling the solvent ratio and the ester-aromatic ratio, QI in the raw material can be efficiently removed, it is ensured that the QI content of the obtained refined asphalt is not larger than 0.1%, the softening point is controlled to be 35-50 DEG C, the heating furnace outlet temperature, the coke tower top pressure, the recycle ratio and the total feeding time are accurately controlled, variable-temperature and variable-pressure operation is implemented, and the optimal mesophase development environment is constructed; the grinding, graphitization and electricity storage properties of the negative electrode coke are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of negative electrode material production process, and particularly relates to a production process of high-performance negative electrode coke. BACKGROUND

[0002] As the core component of new energy vehicles, energy storage systems and consumer electronic products, the market demand for lithium ion batteries is growing. The negative electrode material is a key component of lithium ion batteries, which directly affects the energy density, cycle life and safety performance of the battery. Among the many negative electrode materials, artificial graphite occupies a dominant position in the market due to its excellent comprehensive performance. As a necessary precursor for producing high-end artificial graphite, the quality of high-performance negative electrode coke is crucial, and it is usually required to have low ash content, low thermal expansion coefficient, high true density and appropriate texture to ensure that the final negative electrode material has good electrical conductivity and structural stability.

[0003] At present, commercial high-performance negative electrode coke is mainly produced by delayed coking process using petroleum-based raw materials; however, the source and price of petroleum-based raw materials are significantly affected by international political and economic fluctuations, which poses challenges in terms of supply security and cost control. In contrast, coal-based raw materials, which are more widely available and stable, are considered an ideal alternative raw material. However, there are two major technical bottlenecks in producing high-performance negative electrode coke from coal tar pitch using traditional processes: first, the environmental purification effect of raw material pretreatment is not good, and the quinoline insoluble QI, which is rich in coal tar pitch, is a key harmful impurity that affects the quality of negative electrode coke. If QI is not completely removed, it will cause the ash content of the final product to increase and the graphitization performance to deteriorate; second, there is no negative electrode coke delayed coking process route and conditions, making the regulation of the delayed coking process not precise enough. The ideal microstructure required for negative electrode coke depends on the perfect generation and development of "mesophase" in the liquid phase carbonization process. However, in traditional processes, most of which are electrode coke production processes, the parameter control is not precise, leading to uncontrollable merging and growth of mesophase spherules. This results in unstable performance of the produced negative electrode coke in terms of true density, thermal expansion coefficient, grindability index, specific capacity, and initial efficiency, which often cannot meet the stringent requirements of high-end lithium battery negative electrode materials, limiting its application in the market. SUMMARY

[0004] Based on the above technical problems, the purpose of the present application is to provide a production process of high-performance negative electrode coke, which can efficiently remove QI from the raw material by strictly controlling the solvent ratio and the aliphatic-aromatic ratio, ensuring that the QI content of the obtained refined pitch is not more than 0.1%, and the softening point is controlled at 35-50℃ according to the properties of different raw materials. By precisely controlling the outlet temperature of the heating furnace, the top pressure of the coke drum, the circulation ratio and the total feeding time, and implementing variable temperature and variable pressure operation, the best mesophase development environment is constructed, thereby improving the graphitization performance of the negative electrode coke.

[0005] The specific technical scheme is: A production process of high-performance negative electrode coke, comprising the following steps: S1: pretreatment, mixing solvent oil with soft pitch raw material at a solvent ratio of 0.9-1.2:1, after mixing, the light phase oil produced by the settlement tank is heated by the heating furnace and then enters the light phase tower, and the refined pitch at the bottom of the tower is output, wherein the softening point of the refined pitch is 35-50℃, and the quinoline insoluble content is required to be not more than 0.1%; S2: delayed coking, heating the refined pitch and then entering the fractionating tower, the coking light oil is produced at the top of the tower, the coking heavy oil is produced in the middle, and the coking oil is produced at the bottom; S3: coking, heating the coking oil and then sending it into the coke tower, the process index range is specifically: the outlet temperature of the heating furnace is 470-505℃, the pressure at the top of the coke tower is 0.25-0.35MPa, the reaction is carried out under the condition of a circulation ratio of 0.7-1.2, the total feeding time of the coke tower is 30-36 hours, and the temperature and pressure are changed during the coking process, and the high-performance negative electrode coke is generated; Wherein, the solvent oil includes two kinds of solvents, aliphatic hydrocarbon and aromatic hydrocarbon, and the ratio of aliphatic hydrocarbon to aromatic hydrocarbon is 0.9:1-1.5:1.

[0006] In addition, the production process of high-performance negative electrode coke in the above technical solution provided by the present application can also have the following additional technical features: In the above technical solution, in step S2, the coking heavy oil is divided into three parts, the first part enters the product tank as a product, the second part returns to the fractionating tower, and the third part enters the coke tower as a quenching oil.

[0007] In the above technical solution, the settlement separation includes: the mixed material is settled in the settlement tank, and the light phase oil and the heavy phase oil are separated; the light phase oil is heated by the light phase heating furnace and then sent into the light phase tower, the solvent oil at the top of the light phase tower is refluxed into the solvent oil tank, the refined pitch at the bottom is output and sent for coking; the heavy phase oil is heated by the heavy phase heating furnace and then sent into the heavy phase tower, the solvent oil at the top of the heavy phase tower is refluxed into the solvent oil tank, the anthracene oil is produced in the middle, and the heavy phase pitch is produced at the bottom.

[0008] In the above technical solution, the high-performance negative electrode coke has a Hardgrove grindability index of 75-85%, a true density of 1.39-1.41g / cm 3 , a volatile matter of 4-6%, an ash content of 0.01-0.05%, a thermal expansion coefficient of 1.0-1.2× 10 -6 / ℃, a specific discharge capacity of 355-360mAh / g, and a first efficiency of 95-96%.

[0009] In the above technical solution, two coke towers are provided, and the tower cutting operation is carried out once every 30-36 hours.

[0010] The production process of the high-performance negative electrode coke of the present application has the following beneficial effects compared with the prior art: 1. By mixing solvent oil with soft pitch raw materials at a solvent ratio of 0.9-1.2:1 and controlling the aliphatic-aromatic ratio of aliphatic hydrocarbons and aromatic hydrocarbons in the solvent to be 0.9:1-1.5:1, high-efficiency selective separation of the soft pitch raw materials is achieved, which can accurately remove quinoline insoluble QI harmful to the performance of the negative electrode, ensure that the QI content of the obtained refined pitch is not more than 0.1%, and control the softening point of the refined pitch to be 35-50℃ according to the properties of different raw materials, thereby ensuring the high purity and ideal reactivity of the subsequent coking raw materials at the source, solving the problems of large quality fluctuation and high QI content of the refined pitch in the traditional process, making the entire negative electrode coke production process stable and controllable, and greatly reducing the quality risk in the production process.

[0011] 2. By synergistically controlling the outlet temperature of the heating furnace, the top pressure of the coke drum, the circulation ratio and the total feeding time, and implementing variable temperature and variable pressure operation, an intermediate phase development environment is constructed, and the precise control of the parameter system makes the fusion and growth process of the intermediate phase small globules in the liquid phase carbonization process accurate, effectively promotes the formation of the streamlined and anisotropic coke body structure, and improves the graphitization performance of the coke body, so that the final product meets the high-standard requirements of a Hardgrove grindability index of 75-85%, a true density of 1.39-1.41g / cm 3 , a volatile matter content of 4-6%, an ash content of 0.01-0.05%, a thermal expansion coefficient of 1.0-1.2x10 -6 / ℃, a specific capacity of 355-360mAh / g, and a first efficiency of 95-96%, which fully meets the performance requirements of high-end lithium battery negative electrode materials. BRIEF DESCRIPTION OF DRAWINGS

[0012] Fig. 1 is a flow chart of the coking process of the negative electrode coke of the present application; Fig. 2 is a flow chart of the pretreatment process of the present application; Fig. 3 is a microstructure polarized light detection diagram of a high-performance negative electrode coke of the present application; DETAILED DESCRIPTION

[0013] The present application will be further described below in conjunction with specific implementation examples and the accompanying Figs. 1-3 The present application will be further described below in conjunction with specific implementation examples and the accompanying

[0014] A production process of a high-performance negative electrode coke, which specifically includes the following process flow: S1: Pretreatment, after the soft pitch raw material is stirred by circulation, it is heated by a heat exchanger and then enters a settling tank, and solvent oil is added in the settling tank in proportion, wherein the solvent ratio of the solvent oil to the soft pitch raw material is 0.9-1.2:1; after the settling separation, light phase oil is produced at the top of the settling tank, heated by a light phase heating furnace and then enters a light phase tower, the recoverable solvent oil is produced at the top of the light phase tower and then flows back to the solvent oil tank, refined pitch is produced at the bottom of the light phase tower and then enters a product tank, wherein the softening point of the refined pitch is 35-50℃ according to the properties of the raw material, and the quinoline insoluble content is not more than 0.1%; heavy phase oil is produced at the bottom of the settling tank, heated by a heavy phase heating furnace and then enters a heavy phase tower, the recoverable solvent oil is produced at the top of the heavy phase tower and then flows back to the solvent oil tank, anthracene oil is produced in the middle of the heavy phase tower and then enters the product tank, and heavy phase pitch is produced at the bottom of the heavy phase tower and then enters the product tank; wherein the discharge ratio of the light phase oil and the heavy phase oil is 8:2.

[0015] S2: Delayed coking, the refined pitch produced in the pretreatment process enters the heating furnace of the delayed coking process through a raw material pump, is heated, and then enters a fractionating tower for fractionation, coking light oil is produced at the top of the fractionating tower and then enters a product tank after being condensed and cooled; coking heavy oil is produced in the middle of the fractionating tower, the coking middle oil is divided into three parts, the first part enters the product tank as a product, the second part returns to the fractionating tower, and the third part enters a coke tower as a quenching oil; coking oil is produced at the bottom of the fractionating tower; S3: Coking, the coking oil produced at the bottom of the fractionating tower enters the heating furnace through a coking oil pump, is further heated, and then is sent to a coke tower, coking is formed in the coke tower to form green coke, coking oil gas is produced at the top of the coke tower and then returns to the fractionating tower, and the green coke in the coke tower is cooled and then is cut by high-pressure water and is discharged through the bottom of the coke tower; wherein the outlet temperature of the heating furnace is 470-505℃, the top pressure of the coke tower is 0.25-0.35MPa, the reaction is carried out under the conditions of a circulation ratio of 0.7-1.2, the total feeding time of the coke tower is 30-36 hours, and temperature and pressure are changed during the coking process to generate high-performance negative electrode coke; wherein the solvent oil includes two kinds of solvents, i.e., aliphatic hydrocarbons and aromatic hydrocarbons, and the ratio of the aliphatic hydrocarbons to the aromatic hydrocarbons is 0.9:1-1.5:1.

[0016] By the above method, the soft pitch raw material is mixed with solvent oil at a solvent ratio of 0.9-1.2:1, and the ratio of aliphatic hydrocarbon to aromatic hydrocarbon in the solvent is controlled to be 0.9:1-1.5:1, thereby realizing efficient and selective separation of the soft pitch raw material, accurately removing the quinoline insoluble QI harmful to the negative electrode performance in the raw material, ensuring that the QI content of the obtained refined pitch is not more than 0.1%, and the softening point is stabilized at 35-50 DEG C, thereby ensuring the high purity and ideal reactivity of the subsequent coking raw material at the source, solving the problems of large quality fluctuation and high QI content of the refined pitch in the traditional process, making the entire negative electrode coke production process stable and controllable, and greatly reducing the quality risk in the production process.

[0017] By synergistically controlling the outlet temperature of the heating furnace, the top pressure of the coke tower, the circulation ratio and the total feeding time, and implementing variable temperature and variable pressure operation, the mesophase development environment is constructed, and the precise control of the parameters system makes the fusion and growth process of the mesophase small globules in the liquid phase carbonization process be accurately controlled, effectively promotes the formation of the streamline and anisotropic coke body structure, and improves the graphitization performance of the coke body, so that the final product meets the high standard requirements of a Hardgrove grindability index of 75-85%, a true density of 1.39-1.41 g / cm 3 , a volatile content of 4-6%, an ash content of 0.01-0.05%, a thermal expansion coefficient of 1.0-1.2*10 -6 / ℃, a specific capacity of 355-360 mAh / g, and a first efficiency of 95-96%, and fully meets the performance requirements of high-end lithium battery negative electrode materials.

[0018] Specifically, the variable temperature and variable pressure are core requirements of the operation, and the generation of high-performance negative electrode coke is realized by strictly controlling the heating furnace outlet temperature control curve and the coke tower pressure control curve.

[0019] In the embodiment of the present application, the Hardgrove grindability index of the high-performance negative electrode coke is 75-85%, the true density is 1.39-1.41 g / cm 3 , the volatile content is 4-6%, the ash content is 0.01-0.05%, the thermal expansion coefficient is 1.0-1.2*10 -6 / ℃, the specific capacity is 355-360 mAh / g, and the first efficiency is 95-96%.

[0020] The key indicators of the negative electrode coke produced by the process, such as ash content, true density, volatile content, low thermal expansion coefficient, etc., can meet the production requirements of high-end artificial graphite negative electrode materials, and the cumbersome subsequent purification treatment steps are omitted, thereby shortening the process flow.

[0021] In the embodiment of the present application, two coke towers are provided, and the tower cutting operation is performed once every 36 hours.

[0022] In the description of the application, the term "a plurality of" refers to two or more, unless otherwise expressly specified, and the terms "upper", "lower", and the like, indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application; the terms "connected", "mounted", "fixed" and the like should be understood broadly, for example, "connected" can be fixed connection, can also be detachable connection, or integral connection; can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0023] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A production process for high-performance negative electrode coke, characterized in that, Includes the following steps: S1: Pretreatment, solvent oil and soft asphalt raw material are mixed at a solvent ratio of 0.9-1.2:

1. After the solvent oil and soft asphalt raw material are mixed, the light phase oil produced after sedimentation separation in a settling tank is heated in a heating furnace and then enters a light phase tower. Refined asphalt is produced at the bottom of the tower. The softening point of the refined asphalt is 35-50℃, and the quinoline insoluble content is required to be no more than 0.1%. S2: Delayed coking, the refined asphalt is heated and then fractionated in a fractionation tower. Light coking oil is produced at the top of the fractionation tower, heavy coking oil is produced in the middle, and coking oil is produced at the bottom. S3: Coking. Coking oil is heated and fed into the coking tower. The specific process parameters are as follows: the outlet temperature of the heating furnace is 470-505℃, the top pressure of the coking tower is 0.25-0.35MPa, and the circulation ratio is 0.7-1.

2. The total feeding time of the coking tower is 30-36 hours. Temperature and pressure changes are performed during the coking process to produce high-performance negative electrode coke. The solvent oil includes two types of solvents: aliphatic hydrocarbons and aromatic hydrocarbons, with the ratio of aliphatic hydrocarbons to aromatic hydrocarbons ranging from 0.9:1 to 1.5:

1.

2. The production process of a high-performance negative electrode coke according to claim 1, characterized in that, In step S2, the coking heavy oil is divided into three parts: the first part enters the product tank as a product, the second part is returned to the fractionation tower, and the third part enters the coking tower as quench oil.

3. The production process of a high-performance negative electrode coke according to claim 1, characterized in that, The sedimentation separation includes: The mixed materials are settled in a settling tank to separate the light phase oil and heavy phase oil; The light phase oil is heated in a light phase heater and then fed into a light phase tower. The solvent oil produced at the top of the light phase tower is returned to the solvent oil tank, and the refined asphalt produced at the bottom of the tower is sent to coking. After being heated in a heavy phase heater, the heavy phase oil is fed into a heavy phase tower. The solvent oil produced at the top of the heavy phase tower is returned to the solvent oil tank, anthracene oil is produced in the middle of the tower, and heavy phase pitch is produced at the bottom of the tower.

4. The production process of a high-performance negative electrode coke according to claim 1, characterized in that, The high-performance negative electrode coke has a Hastelloy abrasiveness index of 75-85% and a true density of 1.39-1.41 g / cm³. 3 Volatile matter 4-6%, ash content 0.01-0.05%, coefficient of thermal expansion 1.0-1.2 × 10⁻⁶ -6 / ℃, the coin cell capacity is 355-360mAh / g, and the first efficiency is 95-96%.

5. The production process of a high-performance negative electrode coke according to claim 1, characterized in that, There are two coking towers, and a tower-switching operation is performed every 30-36 hours.

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