A method for conditioning a feedstock for producing coal-tar pitch-based needle coke

Abstract

The present application belongs to the technical field of high-quality needle coke, and particularly relates to a method for modulating raw materials for producing coal-based needle coke. The method comprises the following steps: (1) removing high-activity substances by thermal modification; and (2) removing high-activity substances by temperature variation and sedimentation. The needle coke prepared by the method has the following properties: quinoline insoluble (QI) is ≯0.02%, toluene insoluble (TI) is 10-15%, and density is 1.10-1.21 g / cm 3 The present application removes high-activity substances affecting coke quality by recombination and modification of components of raw materials and separation, and provides a material system with suitable viscosity, stable reactivity, and large flexibility of liquid-phase carbonization operation. The needle coke obtained by the present application has more fibers and domains under an optical microscope than traditional needle coke, and has large size, high crystallinity, and complete crystal lattice, and has superior performance.

Description

Technical Field

[0001] This invention belongs to the technical field of high-quality needle coke preparation of advanced carbon materials, specifically relating to a method for modulating raw materials for producing coal-based needle coke, specifically a method for modulating the components of coal-based needle coke raw materials. Background Technology

[0002] Needle coke is a new type of carbon material developed with the research of carbonaceous mesophase. Due to its high mechanical strength, large bulk density and true density, low coefficient of thermal expansion and low resistivity, it is widely used in industries such as high-power and ultra-high-power electrodes and lithium-ion power battery anode materials.

[0003] The production of needle coke mainly includes three steps: raw material pretreatment, coking, and calcination. The quality of raw material pretreatment directly determines the final product quality. Currently, raw material pretreatment methods mainly include flash evaporation modification, solvent extraction, sedimentation, and centrifugation. The goal is to reduce the content of large-molecule quinoline insolubles that affect mesophase coagulation and growth in the raw material to below 0.1%. To achieve this goal and produce mesophases with excellent optical structure, good development, and uniaxial orientation order, various processes have been developed. For example, Chinese patents CN20151014481 and CN 113637493 A use extraction to separate bitumen into segments, which are then re-blended to prepare high-quality needle coke. Chinese patent CN 112812796 A uses additives to improve the aromaticity of the raw material, preparing raw materials for producing high-quality needle coke. Both of these methods are complex and time-consuming, and may generate secondary quinoline insolubles during the process, making subsequent liquid-phase carbonization difficult and increasing the cost of additive recovery and treatment. The most economical and effective way is to use simple chemical and physical methods to pre-treat raw materials and remove substances that hinder the formation, development, and orderly evolution of the intermediate phase structure. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing raw materials for producing coal-based needle coke, which removes highly active substances from coal tar pitch through thermal reforming and variable-temperature sedimentation to produce high-quality needle coke raw materials.

[0005] The technical solution of this invention is as follows:

[0006] A method for preparing raw materials for producing coal-based needle coke specifically includes the following steps:

[0007] (1) Thermal modification to remove highly active substances

[0008] ① Coal tar pitch is hot-modified at 380-420℃ under normal pressure for 30-120 minutes with a stirring speed of 250-400 rpm. After the hot modification is completed, the temperature is allowed to cool naturally to ≤200℃. The condensed oil is then returned to the masterbatch, stirred evenly, and allowed to settle.

[0009] ② After mixing the above-treated raw materials with the mixed solvent at a mass ratio of 1:1 to 1.15, let them settle in a water bath at 80 to 82°C to remove the slag phase;

[0010] ③ The raw materials treated above are subjected to atmospheric distillation to remove the solvent, and the final temperature at the bottom of the column reaches 350-360℃;

[0011] ④ The needle coke obtained through the above steps is used to prepare the concentrate: quinoline insoluble matter (QI): ≤0.05%, toluene insoluble matter (TI): 15-22%, density: 1.11-1.25 g / cm³ 3 (100℃);

[0012] (2) Temperature-controlled sedimentation to remove highly reactive substances

[0013] ① After mixing the refined asphalt obtained in step (1) with the mixed solvent at a mass ratio of 1:1.24 to 1.26, let it stand in a water bath at 40 to 60°C to remove the heavy phase;

[0014] ② The raw materials treated above are subjected to atmospheric distillation to remove the solvent, and the final temperature at the bottom of the column reaches 330-350℃;

[0015] ③ The needle coke obtained through the above steps is used to prepare the concentrate: quinoline insoluble matter (QI): ≤0.02%, toluene insoluble matter (TI): 10-15%, density: 1.10-1.21 g / cm³ 3 (100℃).

[0016] Furthermore, in step (1), the softening point of coal tar pitch in step ① is 35-40℃; QI ≯3%.

[0017] Furthermore, in step (1) ①, the heating rate is: ≤320℃, 10~20℃ / min, >320℃, ≯2℃ / min.

[0018] Furthermore, the thermal modification temperature in step (1) ① is 395-405℃.

[0019] Furthermore, in step (1) ②, the mixed solvent is aliphatic hydrocarbon: aromatic hydrocarbon = 0.85~1:1wt%.

[0020] Furthermore, in step (1) ②, the mixture is allowed to settle for 3-5 hours.

[0021] Furthermore, in step (2) ①, the mixed solvent is aliphatic hydrocarbon: aromatic hydrocarbon = 0.85~1:1wt%.

[0022] Furthermore, in step (2), ① the water bath is left to stand for 2-4 hours. Detailed description of the invention:

[0024] A method for preparing raw materials for producing coal-based needle coke specifically includes the following steps:

[0025] (1) Thermal modification to remove highly active substances

[0026] ① Coal tar pitch (softening point: 35~40℃; QI≯3%) is hot-modified at 380~420℃ under normal pressure for 30~120min, with a stirring speed of 250~400rpm; heating rate: ≤320℃, 10~20℃ / min, >320℃, ≯2℃ / min; after the hot modification is completed, wait for the temperature to cool naturally to ≯200℃, return the condensed oil to the masterbatch, stir evenly, and then let it settle.

[0027] ② After mixing the above-treated raw materials with a mixed solvent (aliphatic hydrocarbons: aromatic hydrocarbons = 0.85~1:1wt%) at a mass ratio of 1:1~1.15, let it stand in a water bath at 80~82℃ for 3~5 hours to settle, and then remove the slag phase; the aliphatic hydrocarbons and aromatic hydrocarbons are conventional solvents used in this operation in the art.

[0028] ③ The raw materials treated above are subjected to atmospheric distillation to remove the solvent, and the final temperature at the top of the column reaches 350-360℃;

[0029] ④ The needle coke obtained through the above steps is used to prepare the concentrate: quinoline insoluble matter (QI): ≤0.05%, toluene insoluble matter (TI): 15-22%, density: 1.11-1.25 g / cm³ 3 (100℃);

[0030] (2) Temperature-controlled sedimentation to remove highly reactive substances

[0031] ① After mixing refined asphalt (QI ≯ 0.05%) with a mixed solvent (aliphatic hydrocarbon: aromatic hydrocarbon = 0.85~1:1wt%) at a mass ratio of 1:1.24~1.26, the mixture is allowed to stand in a water bath at 40~60℃ for 2~4h to remove the heavy phase; the aliphatic hydrocarbon and aromatic hydrocarbon are conventional solvents used in this operation in the art.

[0032] ② The raw materials treated above are subjected to atmospheric distillation to remove the solvent, and the final temperature at the bottom of the column reaches 330-350℃;

[0033] ③ The needle coke obtained through the above steps is used to prepare the concentrate: quinoline insoluble matter (QI): ≤0.02%, toluene insoluble matter (TI): 10-15%, density: 1.10-1.21 g / cm³3 (100℃);

[0034] Beneficial technical effects

[0035] This invention starts with the raw materials themselves, reorganizes, modifies, and segments the raw material components, removes highly reactive substances that affect coke quality, and provides a material system with suitable viscosity, stable reactivity, and high flexibility in liquid-phase carbonization operation. The refined material obtained by this invention produces needle coke products that, under an optical microscope, have more fibers and larger sizes than traditional products, and also have higher crystallinity, more complete crystal lattice, and superior performance. Detailed Implementation

[0036] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0037]

Example 1

[0038] The embodiment of this invention: thermal modification of raw materials combined with two-step sedimentation purification:

[0039] Coal tar pitch (softening point: 35-40℃; QI ≯3%) was thermally modified at 395-405℃ for 60 min. Specific reaction conditions included a stirring speed of 250-400 rpm and a heating rate of 10-20℃ / min for ≤320℃ and ≯2℃ / min for >320℃. After thermal modification, the temperature was allowed to cool naturally to ≯200℃. The condensed oil was then returned to the masterbatch, stirred evenly, and allowed to settle.

[0040] After mixing the above-treated raw materials with solvent, let them settle in a water bath at 80-82℃ for 3-5 hours to remove the slag phase; the obtained light phase is subjected to atmospheric distillation to remove the solvent and obtain the first-step purified asphalt. The distillation conditions are: the final temperature at the top of the column reaches 350-360℃; the first-step purified asphalt is mixed with solvent and stirred until homogeneous, and then let it stand in a water bath at 40-60℃ for 2-4 hours to remove the heavy phase;

[0041] The obtained secondary light phase was subjected to atmospheric distillation to remove the solvent. The distillation conditions were: a final temperature of 330–350℃ at the bottom of the column. The resulting material was refined pitch, which is a high-quality raw material for preparing needle coke (referred to as refined material one). The main technical parameters of raw material one are: quinoline insolubles (QI): undetectable (0%), toluene insolubles (TI): 10–15%, density: 1.10–1.21 g / cm³. 3 (100℃);

[0042]

Example 2

[0043] To demonstrate the advanced nature of the thermal reforming technology in this technical solution, a comparative experiment was conducted on coal tar pitch raw materials that did not undergo thermal reforming treatment:

[0044] After mixing the untreated coal tar pitch with the solvent, the mixture is allowed to settle in a water bath at 80–82°C for 3–5 hours to remove the slag phase. The resulting light phase is then subjected to atmospheric distillation to remove the solvent, yielding the first-stage purified pitch. The distillation conditions are: a final temperature of 350–360°C at the top of the column. The first-stage purified pitch is then mixed with the solvent and stirred until homogeneous. After settling in a water bath at 40–60°C for 2–4 hours, the heavy phase is removed.

[0045] The obtained secondary light phase was subjected to atmospheric distillation to remove the solvent. The distillation conditions were: a final temperature of 330–350℃ at the bottom of the column. The resulting material was refined asphalt (referred to as refined feedstock 2). The main technical parameters of feedstock 2 were: quinoline insolubles (QI): ≤0.02%, toluene insolubles (TI): 7-8%, and density: 1.15–1.25 g / cm³. 3 (100℃); [Example 3]

[0046] To demonstrate the superiority of the medium-heat reforming combined with two-step sedimentation purification technology in this technical solution, a comparative experiment was conducted using existing one-step purification technology for thermally reformed coal tar pitch raw materials:

[0047] Coal tar pitch (softening point: 35-40℃; QI ≯3%) was thermally modified at 395-405℃ for 60 min. Specific reaction conditions included a stirring speed of 250-400 rpm and a heating rate of 10-20℃ / min for ≤320℃ and ≯2℃ / min for >320℃. After thermal modification, the temperature was allowed to cool naturally to ≯200℃. The condensed oil was then returned to the masterbatch, stirred evenly, and allowed to settle.

[0048] After mixing the above-treated raw materials with solvent, the mixture is allowed to settle in a water bath at 80-82℃ for 3-5 hours to remove the slag phase. The resulting light phase is then subjected to atmospheric distillation to remove the solvent and obtain the first step of purified asphalt. The distillation conditions are: the final temperature at the top of the column reaches 350-360℃.

[0049] The resulting light phase was subjected to atmospheric distillation to remove the solvent. The distillation conditions were: a final temperature of 330–350°C at the bottom of the column. The resulting material was primary refined pitch (referred to as refined feedstock 3). The main technical parameters of feedstock 3 were: quinoline insolubles (QI): 0.05–0.10%, toluene insolubles (TI): 12–15%, and density: 1.11–1.21 g / cm³. 3 (100℃);

[0050] Needle coke was prepared by liquid-phase carbonization of the above three raw materials, and optical microstructure and CTE analysis were performed. The results are as follows:

[0051]

[0052] Of course, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Any modifications or variations of the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A method for preparing raw materials for producing coal-based needle coke, characterized in that: Specifically, the steps include the following: (1) Thermal modification to remove highly active substances ① Coal tar pitch is hot-modified at 380~420℃ under normal pressure for 30~120min with a stirring speed of 250~400rpm; after the hot modification is completed, the temperature is allowed to cool naturally to ≤200℃, and the condensed oil is returned to the masterbatch, stirred evenly, and then allowed to settle. ② After mixing the above-treated raw materials with the mixed solvent at a mass ratio of 1:1~1.15, let them settle in a water bath at 80~82℃ to remove the slag phase; ③The raw material after removing the slag phase is subjected to atmospheric distillation to remove the solvent, and the final temperature at the bottom of the column reaches 350~360℃; ④ The refined asphalt obtained through the above steps has the following composition: quinoline insolubles (QI): ≤0.05%, toluene insolubles (TI): 15~22%, and density: 1.11~1.25 g / cm³. 3 100℃; (2) Temperature-dependent sedimentation to remove highly reactive substances ① After mixing the refined asphalt obtained in step (1) with the mixed solvent at a mass ratio of 1:1.24~1.26, let it stand in a water bath at 40~60℃ to remove the heavy phase; ②The raw material after removing the heavy phase is subjected to atmospheric distillation to remove the solvent, and the final temperature at the bottom of the column reaches 330~350℃; ③ The needle coke obtained through the above steps is used to prepare the concentrate: quinoline insoluble matter (QI): ≤0.02%, toluene insoluble matter (TI): 10~15%, density: 1.10~1.21 g / cm³ 3 100℃; In step (1) ②, the mixed solvent is aliphatic hydrocarbon: aromatic hydrocarbon = 0.85~1:1, by mass. In step (2), the mixed solvent in ① is aliphatic hydrocarbon: aromatic hydrocarbon = 0.85~1:1, by mass.

2. The method for preparing raw materials for producing coal-series needle coke according to claim 1, characterized in that: The softening point of coal tar pitch in step (1) is 35~40℃; QI≯3%.

3. The method for preparing raw materials for producing coal-series needle coke according to claim 1, characterized in that: In step (1), the heating rate in ① is: ≤320℃, 10~20℃ / min; >320℃, ≯2℃ / min.

4. The method for preparing raw materials for producing coal-series needle coke according to claim 1, characterized in that: In step (1), the thermal reforming temperature is 395-405℃.

5. The method for preparing raw materials for producing coal-series needle coke according to claim 1, characterized in that: In step (1) ②, allow the mixture to settle for 3-5 hours.

6. The method for preparing raw materials for producing coal-series needle coke according to claim 1, characterized in that: In step (2), ① the water bath is left to stand for 2-4 hours.

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