Preparation process for graphitized carbon micropowder particles, and graphitized carbon micropowder particles

Abstract

A preparation process for graphitized carbon micropowder particles, and graphitized carbon micropowder particles. The preparation process for graphitized carbon micropowder particles comprises: pretreating a carbon source, so as to obtain a carbon micropowder; mixing the carbon micropowder with a dry-powder additive, an acidifier and a liquid additive, and pressing same, so as to obtain carbon microspheres; and drying and baking the carbon microspheres to obtain carbon micropowder particles, and then carbonizing and graphitizing the carbon micropowder particles, so as to obtain graphitized carbon micropowder particles. The preparation process of the present application can prepare carbon microspheres, carbon micropowder particles and graphitized carbon micropowder particles having a certain strength, so as to prevent same from being flushed away during subsequent vertical continuous graphitization. Moreover, in the present application, the amount of impurities having a high melting point and a high boiling point in the prepared carbon micropowder particles can be effectively reduced by means of a micro-acidification treatment; and the co-melting point of the impurities is reduced by means of a blend, thereby effectively avoiding the enrichment, coking and hardening of the impurities having a high melting point in a graphitization furnace. In addition, the obtained graphitized carbon micropowder particles are easy to scatter, without being crushed and ground.

Description

Preparation process of graphitized carbon micropowder particles and graphitized carbon micropowder particles Technical Field

[0001] This application relates to the field of carbon materials technology, particularly to precursors for anode materials, and even more so to the preparation process of graphitized carbon micropowder particles and the graphitized carbon micropowder particles themselves. Background Technology

[0002] In the artificial graphite anode material industry, in order to overcome the drawbacks of intermittent graphitization processes such as long cycles and high energy consumption, such as Atchison furnaces, internal string furnaces or box furnaces, vertical continuous graphitization processes and equipment have become one of the popular research and development directions.

[0003] However, the vertical continuous graphitization process requires the feed material to be granular, not powdery. Otherwise, high-volatile impurities in the furnace will vaporize and overflow, washing away the carbon micropowder. If the gas overflow channel is blocked, a furnace blowout accident may occur. To address this, existing technologies mainly use a one-pot method of mixing cassava flour with water or corn starch with PVA hydrosol to granulate the carbon micropowder. However, neither cassava flour nor corn starch has strength after carbonization, and PVA has a characteristic of vitrification and embrittlement between 100℃ and 300℃, resulting in low strength granules made from carbon micropowder. Existing technologies typically compensate for this defect by increasing the amount of PVA binder, but this leads to excessively high strength graphitized granules, requiring subsequent crushing and grinding, resulting in a rough surface, reduced tap density, and low product quality in the final material.

[0004] In addition, impurities such as Fe2O3, Fe, CaO, SiO2, CaSiO4, Cr, Co, and Ni, which have high melting and high volatility points, accumulate and clump together in the carbon micropowder within the vertical graphitization furnace, posing a safety hazard of furnace pressure buildup. Furthermore, the high temperature can cause a significant amount of gas to escape, resulting in the loss of carbon micropowder due to being washed away.

[0005] Therefore, it is necessary to provide a preparation process for graphitized carbon micropowder particles and the graphitized carbon micropowder particles themselves, in order to overcome the above-mentioned defects and safety hazards existing in the prior art and achieve the industrialization of the vertical continuous graphitization process.

[0006] Application content

[0007] In view of the above problems, the purpose of this application is to provide a preparation process for graphitized carbon micropowder particles and the resulting carbon micropowder graphitized particles. This preparation process can produce carbon micropowder particles with a certain strength to prevent them from being washed away during subsequent vertical continuous graphitization. Furthermore, the carbon micropowder particles produced by this process contain fewer high-melting-point and high-volatility-point impurities, avoiding the accumulation and caking of these impurities in the graphitization furnace. In addition, the obtained carbon micropowder graphitized particles are easily dispersed and do not require crushing or grinding.

[0008] To achieve the above objectives, this application provides a process for preparing graphitized carbon micropowder particles, comprising:

[0009] (i) Carbon source is pretreated to obtain carbon micro powder;

[0010] (ii) The carbon micro powder is mixed with dry powder additives, acidifiers and liquid additives and pressed to obtain carbon microspheres;

[0011] (iii) The carbon microspheres are dried and baked to obtain carbon micro powder particles;

[0012] (iv) The carbon micro powder particles are carbonized and graphitized to obtain carbon micro powder graphitized particles.

[0013] The technical solution adopted in this application has at least the following technical effects.

[0014] (1) By utilizing the adhesive properties of liquid additives, dry powder additives and carbon micropowders can be kneaded together to form a kneaded state with a certain strength after pressing. Under the action of liquid additives and acidifiers, the dry powder additives are evenly dispersed and adhered on the surface of carbon micropowders, providing initial strength to the pressed carbon microspheres (this free-fall fracture resistance can be 400mm to 1000mm). After subsequent drying and baking, the hot melting and thermosetting of dry powder additives can further improve the free-fall fracture resistance of carbon micropowder particles to 500mm to 1300mm. Finally, after carbonization and graphitization, the free-fall fracture resistance of the graphitized carbon micropowder particles is 350mm to 950mm. In addition, the high fluidity of the dry powder additives after hot melting allows them to fill the pores, pits, or grooves of carbon micropowders, giving the carbon micropowders a more rounded appearance. Carbon microparticles possess a certain degree of resistance to breakage under free fall, ensuring they are not easily washed away even when exposed to overflowing gases in a vertical continuous graphitization system, resulting in a low powder loss rate. This also prevents excessive strength from causing surface roughness during subsequent processing. Furthermore, liquid additives not only provide binding strength to the carbon microparticles, but some substances can also blend with high-melting-point impurities in the carbon microparticles to form low-melting-point eutectics. This avoids the risk of high-melting-point impurities accumulating and forming coke caking within the furnace during graphitization, thus enabling the industrial-scale implementation of the vertical continuous graphitization process.

[0015] (2) Adding an acidifying agent can react with high-melting-point and high-volatility-point metallic elements and metallic compound impurities in carbon micropowder, transforming them into low-melting-point and low-boiling-point metallic elements and metallic compounds (e.g., converting Fe2O3 with a melting point of 1565℃ and a boiling point of 3414℃ and metallic Fe with a boiling point of 2750℃ into FeCl3 with a melting point of 306℃ and a boiling point of 319℃, converting CaO into CaCl2, and converting Cr, Co, and Ni into CrCl3, CoCl2, and NiCl3, respectively). This allows for low-temperature impurity removal through subsequent low-temperature baking, preventing the accumulation and coking of high-melting-point and high-volatility-point metallic elements and metallic compounds in the graphitization furnace. Furthermore, it can reduce the amount of high-temperature gas generated during high-temperature graphitization and the consumption of carbon source in the carbon micropowder by these impurities.

[0016] As one technical solution of this application, the carbon source includes coke powder and / or graphite powder.

[0017] As a technical solution of this application, the coke powder includes one or more of needle coke, calcined petroleum coke, raw petroleum coke, semi-calcined petroleum coke, pitch coke, anthracite, and biochar.

[0018] As one technical solution of this application, the graphite powder includes at least one of flake graphite, microcrystalline graphite and spherical graphite.

[0019] As one technical solution of this application, the carbon micropowder is first mixed with the dry powder additive and then mixed with the liquid additive.

[0020] As a technical solution of this application, the dry powder additive includes at least one of resin powder, polysaccharide powder, adhesive powder and inorganic salt powder.

[0021] As one technical solution of this application, the dry powder additive includes at least two of the following: phenolic resin powder, modified urea-formaldehyde resin powder, asphalt powder, α-starch, sugar powder, cellulose powder, redispersible adhesive powder, polyvinyl alcohol powder, latex powder, sodium silicate, calcium chloride, ferric chloride, ferrous chloride, and aluminum phosphate.

[0022] As one technical solution of this application, the dry powder additive includes resin powder and adhesive powder.

[0023] As one technical solution of this application, the dry powder additive includes phenolic resin, asphalt, redispersible polymer powder and polyvinyl alcohol polymer powder.

[0024] As one technical solution of this application, the liquid additive includes at least one of resin glue, inorganic salt solution and solvent.

[0025] As a technical solution of this application, the liquid additive includes at least two of urea-formaldehyde resin adhesive, epoxy resin adhesive, phenolic resin adhesive, liquid asphalt adhesive, latex, water glass, calcium chloride solution, ferric chloride solution, ferrous chloride solution, water, ethanol, methanol, acetone, xylene, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether, and propylene glycol methyl ether.

[0026] As one technical solution of this application, the liquid additive includes an inorganic salt solution and water.

[0027] As one technical solution of this application, the acidifier includes a liquid acidifier and / or a solid acidifier.

[0028] As a technical solution of this application, the liquid acidifying agent includes at least one of nitric acid, hydrochloric acid, acrylic acid, tartaric acid solution, citric acid solution and oxalic acid solution.

[0029] As a technical solution of this application, the solid acidifying agent includes at least one of tartaric acid powder, citric acid powder and oxalic acid powder.

[0030] As a technical solution of this application, the liquid acidifier is added after mixing the dry powder additive and before mixing the liquid additive.

[0031] As a technical solution of this application, the liquid acidifier is first mixed with the liquid additive and then mixed together with the dry powder additive.

[0032] As a technical solution of this application, the solid acidifier is first mixed with the dry powder additive before being added to the carbon micro powder.

[0033] As a technical solution of this application, the carbon micro powder is mixed sequentially with the dry powder additive, the solid acidifier, and the liquid additive.

[0034] As one technical solution of this application, the liquid acidifier is added by spraying, and the spraying speed is from 0.5 kg / min to 10.0 kg / min.

[0035] As one technical solution of this application, the median particle size of the carbon source is 5 μm to 25 μm.

[0036] As one technical solution of this application, the carbon source has a carbon content of ≥80 wt.%.

[0037] As one technical solution of this application, the volatile matter content of the carbon source is 0.1% to 15.0%.

[0038] As one technical solution of this application, the sulfur content of the carbon source is 1.0% to 3.0%.

[0039] As one technical solution of this application, the mass ratio of the carbon micro powder to the dry powder additive is 100:1 to 8.

[0040] As a technical solution of this application, the amount of acidifier added is controlled so that the acidity value of the carbon micropowder is 5.5 to 6.9.

[0041] As one technical solution of this application, the mass ratio of the carbon micro powder to the liquid additive is 50-100:6-25.

[0042] As one technical solution of this application, the particle size distribution of the dry powder additive is from 0.01 μm to 100.00 μm.

[0043] As a technical solution of this application, the carbon micro powder and the dry powder additive are mixed using a mixer. The mixing speed of the dry powder mixer is 30 r / min to 200 r / min, and the mixing time is 2 min to 15 min.

[0044] As one technical solution of this application, the carbon micro powder and the dry powder additive are mixed using a mixer, which includes a ribbon mixer, a single cone double spiral mixer, a horizontal plow mixer, or mortar. As another technical solution of this application, the liquid additive is added by spraying, and the spraying speed is 0.5 kg / min to 10.0 kg / min.

[0045] As one technical solution of this application, the mixing speed after adding the liquid additive is 60 r / min to 300 r / min, and the mixing time is 3 min to 8 min.

[0046] As a technical solution of this application, the pretreatment includes crushing the carbon source to a particle size of 0.01 mm to 5.00 mm and then grinding it to obtain carbon micro powder with a particle size of 5 μm to 20 μm.

[0047] As a technical solution of this application, the pressing includes first buffering the mixed materials and then pressing them into briquetting machines to obtain carbon microspheres with a particle size of 5 mm to 35 mm. The buffering pressure is -0.001 kPa to -30.0 kPa, the buffering time is 10 min to 30 min, and the pressure of the briquetting machine is 4.5 MPa to 9.5 MPa.

[0048] As a technical solution of this application, the carbon microspheres are first dried at 30°C to 105°C, and then baked at 95°C to 280°C to 300°C to obtain carbon micropowder particles with a moisture content of less than 0.01 wt.%.

[0049] The second aspect of this application provides carbon micro-graphitized particles prepared by the aforementioned preparation process of micro-graphitized particles, wherein the free fall fracture resistance value of the carbon microspheres is set to 400 mm to 1000 mm.

[0050] The third aspect of this application provides carbon micro-graphitized particles prepared by the aforementioned preparation process of micro-graphitized particles, wherein the free fall fracture resistance value of the carbon micro-powder particles obtained by drying and baking is set to 500 mm to 1300 mm.

[0051] The fourth aspect of this application provides carbon micronized graphitized particles prepared by the aforementioned preparation process of micronized graphitized particles, wherein the free fall fracture resistance value of the carbon micronized graphitized particles is set to 350 mm to 950 mm.

[0052] As a technical solution of this application, the free fall fracture resistance value is obtained by testing the limit height value of the particle that remains intact and unbroken after free fall. Detailed Implementation

[0053] This application provides a preparation process for graphitized carbon micropowder particles and the graphitized carbon micropowder particles themselves. The free-fall fracture resistance value of the graphitized carbon micropowder particles is 350 mm to 950 mm, and can be, but is not limited to, 150 mm, 180 mm, 200 mm, 250 mm, 300 mm, and 350 mm. Graphitized carbon micropowder particles with this strength are beneficial for the subsequent processing and fabrication of negative electrode sheets.

[0054] The carbon microparticle preparation process provided in this application includes steps (i), (ii), (iii) and (iv).

[0055] Step (i) includes pretreating the carbon source to obtain carbon micropowder. The carbon source includes coke powder and / or graphite powder. Coke powder includes one or more of needle coke, calcined petroleum coke, raw petroleum coke, semi-calcined petroleum coke, pitch coke, anthracite, and biochar. Of course, the carbon source may not only include the above-mentioned substances. Graphite powder includes at least one of flake graphite, microcrystalline graphite, and spherical graphite. The median particle size of the carbon source is 5 μm to 25 μm, and may be, but is not limited to, 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 22 μm, 24 μm, and 25 μm. The carbon source has a carbon content ≥80 wt.%, which may include, but is not limited to, ≥80 wt.%, ≥81 wt.%, ≥82 wt.%, ≥83 wt.%, ≥84 wt.%, ≥85 wt.%, ≥86 wt.%, ≥87 wt.%, ≥88 wt.%, ≥89 wt.%, and ≥96.33 wt.%. The volatile matter content of the carbon source is 0.1% to 15.0%, which may include, but is not limited to, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 6.0%, 8.0%, 10.0%, 12.0%, 14.0%, and 15.0%. The sulfur content of the carbon source is 1.0% to 3.0%, which may include, but is not limited to, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%.

[0056] The pretreatment process involves pulverizing the carbon source to a particle size of 0.01 mm to 5.00 mm, followed by grinding to obtain carbon micropowder with a particle size of 5 μm to 20 μm. The particle size of the obtained carbon micropowder can be, but is not limited to, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, and 20 μm. The carbon source can be a single source or a mixture of multiple sources. The carbon sources are mixed uniformly to ensure consistent particle size, volatile matter, and carbon or impurity content, facilitating the control of pulverization and grinding parameters to obtain uniform carbon micropowder. Uniform carbon micropowder, with largely consistent properties, facilitates the stable control of additives and allows for the pressing of carbon microspheres with stable quality. Stable carbon microspheres will not exhibit fluctuations in carbon particle strength, preventing low-strength carbon microspheres from easily breaking and pulverizing, which would hinder subsequent drying, baking, carbonization, and graphitization. On the other hand, carbon microspheres with excessively high strength will not disintegrate after graphitization and will require further crushing and grinding, resulting in undesirable outcomes such as rough product surface, low compaction density, and excessively large specific surface area.

[0057] The uniformly mixed carbon source is continuously and automatically fed into a pulverizer, where it is pulverized to a particle size of 0.01mm to 5.00mm. Particle sizes can be, but are not limited to, 0.01mm, 0.05mm, 0.10mm, 0.5mm, 1.00mm, 2.00mm, 3.00mm, 4.00mm, and 5.00mm. Pulverizing too finely results in excessively fine carbon micropowder, leading to a low yield rate. Pulverizing too coarsely results in excessively large carbon micropowder particles, causing low grinding efficiency. The pulverized carbon source is then ground and shaped into carbon micropowder of the required particle size for the final product. This carbon micropowder has a relatively rounded surface, resembling millet, sesame seeds, or olives, resulting in a spherical shape. Compared to irregularly shaped carbon micropowder with a rough surface, this structure results in a higher tap density and smaller specific surface area, leading to a higher volumetric energy density in the resulting anode material.

[0058] Step (II) involves mixing carbon micropowder with dry powder additives, acidifiers, and liquid additives and pressing them to obtain carbon microspheres.

[0059] In this process, carbon micropowder is first mixed with dry powder additives and then with liquid additives. Only by mixing the dry powder additives first and then the liquid additives can a kneaded state with uniformly dispersed components be obtained.

[0060] Furthermore, the mass ratio of carbon micro powder to dry powder additive is 100:1 to 8, and may be, but is not limited to, 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, and 100:8. The particle size distribution of the dry powder additive is 0.01 μm to 100.00 μm, and may be, but is not limited to, 0.01 μm, 0.10 μm, 1.00 μm, 10.00 μm, 20.00 μm, 30.00 μm, 40.00 μm, 50.00 μm, 60.00 μm, 70.00 μm, 80.00 μm, 90.00 μm, and 100.00 μm. The carbon micro powder and dry powder additives are mixed using a mixer, which may include a ribbon mixer, a single-cone double-spiral mixer, a horizontal plow mixer, or a mortar mixer. As an example, a single-cone double-spiral mixer with a pH value ≥ 1 is selected. The carbon micro powder and dry powder additives are fed into a wet / dry mixer under slight negative pressure while being stirred. After feeding, the mixing chamber is sealed and the mixture is dry-mixed evenly, which facilitates rapid and uniform mixing of the materials. The stirring speed of the dry powder mixer is from 30 r / min to 200 r / min, and can be, but is not limited to, 30 r / min, 50 r / min, 70 r / min, 90 r / min, 100 r / min, 120 r / min, 140 r / min, 160 r / min, 180 r / min, or 200 r / min. The stirring time is 2 to 15 minutes, and can be, but is not limited to, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 12 minutes, 13 minutes, and 15 minutes.

[0061] Dry powder additives include at least one of resin powder, polysaccharide powder, adhesive powder, and inorganic salt powder. Specifically, dry powder additives include at least two of phenolic resin adhesive powder, modified urea-formaldehyde resin adhesive powder, asphalt powder, α-starch, sugar powder, cellulose powder, redispersible adhesive powder, polyvinyl alcohol adhesive powder, latex powder, sodium silicate, calcium chloride, ferric chloride, ferrous chloride, and aluminum phosphate. As an example, dry powder additives include resin powder and adhesive powder; more specifically, dry powder additives include phenolic resin, asphalt, redispersible adhesive powder, and polyvinyl alcohol adhesive powder. The phenolic resin and asphalt do not vitrify or become brittle during baking, and their thermosetting properties improve the strength of the carbon microparticles. The polyvinyl alcohol adhesive powder enables the kneaded carbon microspheres formed with liquid additives to possess a certain free-fall fracture resistance strength and viscosity value to ensure pressing quality and smooth operation of the pressing process. The redispersible adhesive powder has water-reducing and binding properties, ensuring the strength of the kneaded carbon microspheres and improving drying efficiency and reducing drying energy consumption by appropriately reducing water consumption.

[0062] Besides carbon as its main component, carbon micropowder also contains impurities with high melting and high volatility, such as Fe2O3, Fe, CaO, SiO2, and CaSiO4, as shown in Table 1. These high-melting-point and high-volatility-point metallic elements and compounds not only accumulate and form coke and caking in the vertical graphitization furnace, posing a safety hazard of pressure injection, but also react with the carbon in the carbon micropowder, causing carbon loss, as shown in the following equation: 2Fe2O3 + 3C = 4Fe + 3CO2↑

[0063] Table 1. Composition and content of carbon micro powder

[0064] The addition of an acidifying agent can cause high-melting-point and high-volatility-point metallic elements and metallic compound impurities to react and transform into low-melting-point and low-boiling-point metallic elements and metallic compounds. For example, Fe₂O₃ with a melting point of 1565℃ and a boiling point of 3414℃ and metallic Fe with a boiling point of 2750℃ can be converted into FeCl₃ with a melting point of 306℃ and a boiling point of 319℃, and CaO can be converted into CaCl₂. Adding the acidifying agent before mixing with the liquid additive can uniformly disperse the low-melting-point and low-boiling-point metallic elements and metallic compounds generated in the carbon micropowder in the liquid additive, thus ensuring uniform distribution on the surface of the carbon micropowder, which is beneficial for subsequent low-temperature impurity removal.

[0065] The amount of acidifying agent added is controlled to achieve an acidity value of 5.5 to 6.9 for the carbon micropowder, but not limited to 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, and 6.9. This slight acidification (acidity value of 5.5 to 6.9) aims to convert high-melting-point and high-volatility-point impurities in the carbon micropowder into low-melting-point and low-volatility-point impurities using a very small amount of acid.

[0066] Acidifying agents include liquid acidifying agents and / or solid acidifying agents. Liquid acidifying agents include at least one selected from nitric acid, hydrochloric acid, acrylic acid, tartaric acid solution, citric acid solution, and oxalic acid solution. If the acidifying agent is a liquid acidifying agent, it is added after mixing the dry powder additive and before mixing the liquid additive, or the liquid acidifying agent is mixed with the liquid additive first and then mixed together after adding the dry powder additive. The liquid acidifying agent is added by spraying, and the spraying speed is from 0.5 kg / min to 10.0 kg / min, and may be, but is not limited to, 0.5 kg / min, 1.0 kg / min, 1.5 kg / min, 2.5 kg / min, 3.5 kg / min, 4.5 kg / min, 5.5 kg / min, 6.5 kg / min, 7.5 kg / min, 8.5 kg / min, 9.5 kg / min, and 10.0 kg / min. If the acidifier is a solid acidifier, it includes at least one of tartaric acid powder, citric acid powder, and oxalic acid powder. The solid acidifier is mixed with the dry powder additive before being added to the carbon micro powder, or the carbon micro powder is mixed with the dry powder additive, the solid acidifier, and the liquid additive in sequence.

[0067] The mass ratio of carbon micropowder to liquid additive is 50–100:6–25, and may include, but is not limited to, 50:6, 50:10, 50:15, 50:20, 50:25, 65:6, 65:10, 65:15, 65:20, 65:25, 80:6, 80:10, 80:15, 80:20, 80:25, 100:6, 100:10, 100:15, 100:20, and 100:25. The liquid additive includes at least one of resin adhesive, inorganic salt solution, and solvent. The resin adhesive includes at least one of urea-formaldehyde resin adhesive, epoxy resin adhesive, phenolic resin adhesive, liquid asphalt adhesive, and latex. The inorganic salt solution includes at least one of water glass, calcium chloride solution, ferric chloride solution, and ferrous chloride solution. The solvent includes at least two of the following: water, ethanol, methanol, acetone, xylene, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether, and propylene glycol methyl ether. The liquid additive includes an inorganic salt solution and water. The inorganic salt solution not only improves strength but also forms blends with high-melting-point impurities such as SiO2 and CaSiO4 in the carbon micropowder, thereby lowering the melting point of the impurities and eliminating the safety hazards of coke caking and pressure buildup in the vertical graphitization furnace caused by high-melting-point impurities.

[0068] The liquid additive is added via spraying at a rate ranging from 0.5 kg / min to 10.0 kg / min, including but not limited to 0.5 kg / min, 1.0 kg / min, 1.5 kg / min, 2.5 kg / min, 3.5 kg / min, 4.5 kg / min, 5.5 kg / min, 6.5 kg / min, 7.5 kg / min, 8.5 kg / min, 9.5 kg / min, and 10.0 kg / min. The nozzle can be mounted on a mixer, which can have 1 to 8 nozzles. Spraying facilitates uniform mixing of the components. After adding the liquid additive, the mixing speed of the mixer is 60 r / min to 300 r / min, but not limited to 60 r / min, 80 r / min, 100 r / min, 120 r / min, 150 r / min, 180 r / min, 200 r / min, 220 r / min, 240 r / min, 260 r / min, 280 r / min, and 300 r / min. The mixing time is 3 min to 8 min, but not limited to 3 min, 4 min, 5 min, 6 min, 7 min, and 8 min.

[0069] The pressing process involves first buffering the mixed materials and then pressing them into briquetting machines to obtain carbon microspheres with a particle size of 5 mm to 35 mm. The particle size can be, but is not limited to, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, and 35 mm. The particle size of carbon microspheres should not be uniform, as this is not conducive to adjusting the furnace resistance in the vertical continuous graphitization process. At the same time, the particle size distribution should not be too large, as this can easily cause excessive deviation in the downward movement speed of particles in the vertical graphitization furnace, resulting in unstable graphitization degree indicators of the product. Therefore, as an example, carbon microspheres may include a combination of carbon microspheres with multiple particle sizes, such as the first carbon microsphere having a particle size of 5mm to 10mm, the second carbon microsphere having a particle size of 10mm to 20mm, the third carbon microsphere having a particle size of 20mm to 30mm, and the fourth carbon microsphere having a particle size of 30mm to 35mm, and the ratio of the first carbon microsphere, the second carbon microsphere, the third carbon microsphere, and the fourth carbon microsphere is 10~60:30~80:20~60:0~30. The mixed materials are then subjected to a buffering and caching process. The caching pressure is controlled between -0.001 kPa and -30.0 kPa, but is not limited to -0.001 kPa, -0.01 kPa, -0.10 kPa, -1.0 kPa, -5.0 kPa, -10.0 kPa, -15.0 kPa, -20.0 kPa, -25.0 kPa, and -30.0 kPa. The caching time is 10 to 30 minutes. The caching time should not be too long, otherwise it will lead to liquid evaporation and material drying, affecting the quality of the briquettes. Negative pressure is used during caching, allowing gas to escape from the pores or grooves of the carbon micropowder. The additives penetrate and fully wet the pores or grooves, improving the coating and bonding quality. Furthermore, micro-negative pressure caching helps improve the bulk density of the material, the compactness of the briquettes, and the bonding strength between the micropowder particles. In addition, most of the gas between the carbon micropowder particles is extracted, which helps to improve the density and initial strength of the carbon micropowder. The prepared material is fed into a briquetting machine for briquetting. The briquetting pressure is 4.5MPa to 9.5MPa, using a continuous pressing method without pressure holding. The pressure can be, but is not limited to, 4.5MPa, 5.0MPa, 5.5MPa, 6.0MPa, 6.5MPa, 7.0MPa, 7.5MPa, 8.0MPa, 8.5MPa, and 9.5MPa. The briquetting pressure should not be too low, otherwise it will be difficult to form compact carbon microspheres. Similarly, the pressure should not be too high, otherwise it will be difficult to disperse the particles obtained by subsequent graphitization, which will have an adverse effect on the appearance and tap density of the product. The free-fall crushing strength of the pressed carbon microspheres is 400mm to 1000mm, but is not limited to 400mm, 500mm, 600mm, 700mm, and up to 1000mm. The method for determining the free-fall fracture resistance value is as follows.

[0070] (1) The testing apparatus consists of a base, a support rod, and a particle placement frame. The base is a 10mm thick × 100mm × 100mm steel plate. The support rod is a steel pipe with a diameter of 8mm and a length of 1500mm. The steel pipe is vertically connected to the steel plate by threads, and the steel pipe is marked with a scale from 0mm to 1800mm from the top of the steel plate. The particle placement frame has a particle placement ring, and the bottom of the particle placement ring has a horizontally movable support plate. The particle placement ring can move freely up and down on the support rod and is fixed to the support rod by screws.

[0071] (2) Place the particles, fix the particle placement ring to the selected height, and tighten it. Place the tray directly below the particle placement ring, and then place the complete particles into the particle placement ring and onto the tray;

[0072] (3) Free fall operation: move the tray to the left or right, and the particles on the tray will fall freely and collide with the upper surface of the base.

[0073] (4) Check the results of the free fall of the particles to evaluate the free fall resistance strength value of the particles. For each lower limit height test, the particles should be intact and unbroken during free fall. Simultaneously, for each upper limit height +1mm test, the particles should be incomplete and broken during free fall. For example, the 400mm free fall resistance strength value of carbon microspheres is determined by allowing the compressed carbon microspheres to fall freely at 400mm and observing whether they break. If they do not break, it indicates that the particle is qualified, and its resistance strength value is at least 400mm. If it breaks, it means that the carbon microsphere's resistance strength value is lower than the minimum requirement of 400mm, and it is judged as unqualified.

[0074] This detection method is simple and fast to operate, and can fully meet the needs of particle quality monitoring and control in continuous graphitization processes.

[0075] Step (iii) includes drying and baking the carbon microspheres to obtain carbon micropowder particles. The carbon microspheres are first dried at 30°C to 105°C, and then baked at a gradient temperature of 95–105°C to 280–300°C to obtain carbon micropowder particles with a moisture content of less than 0.01 wt.%. The baking can be performed by raising the temperature to the gradient temperature of 95–105°C to 280–300°C in one go, or by raising the temperature to the gradient temperature of 95–105°C to 280–300°C in stages. The gradient baking temperature can be, but is not limited to, 95°C–280°C, 95°C–300°C, 100°C–280°C, 105°C–280°C, 105°C–290°C, or 105°C–300°C. Gradient baking allows the thermosetting and fusible components in the carbon microspheres to melt and solidify, facilitating the formation of a stable particle structure, maintaining good micro-powder morphology and particle mechanical strength, and improving the stability, safety, and product quality of subsequent graphitization. The free-fall fracture resistance of the carbon micro-powder particles provided in this application is 500 mm to 1300 mm, but can be, but is not limited to, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm, 1200 mm, and 1300 mm. The carbon micro-powder particles provided in this application possess a certain strength, preventing the carbon micro-powder from being washed away during subsequent vertical continuous graphitization, and avoiding the accumulation and caking of high-melting-point and high-volatility-point impurities in the graphitization furnace.

[0076] Step (iv) involves carbonizing and graphitizing carbon micropowder particles to obtain graphitized carbon micropowder particles. Carbonization and graphitization can be performed using an integrated continuous process. A slightly positive pressure self-oxygen-isolating system at the furnace top can be achieved through the volatile gases generated during carbonization and the gaseous substances overflowing from graphitization purification. This eliminates the need for introducing large amounts of inert gas for oxygen isolation, reducing equipment investment and operating costs, especially avoiding the introduction of large amounts of N2, thus eliminating the investment and operating costs of denitrification. The carbonization temperature is from 500℃ to 2200℃, but can be, but is not limited to, 500℃, 600℃, 700℃, 800℃, 900℃, 1000℃, 1100℃, 1200℃, 1300℃, 1400℃, 1500℃, 1600℃, 1700℃, 1800℃, 1900℃, 2000℃, 2100℃, and 2200℃. The carbonization time is 2 hours to 20 hours, but can be, but is not limited to, 2 hours, 4 hours, 10 hours, 14 hours, 15 hours, 16 hours, 18 hours, and 20 hours.

[0077] The graphitization temperature is between 2200℃ and 3300℃, but can be, but is not limited to, 2200℃, 2300℃, 2400℃, 2500℃, 2600℃, 2700℃, 2800℃, 2900℃, 3000℃, 3100℃, 3200℃, and 3300℃. The continuous graphitization time is between 6h and 36h, but can be, but is not limited to, 6h, 10h, 13h, 16h, 20h, 24h, 28h, 32h, and 36h.

[0078] To better illustrate the purpose, technical solution, and beneficial effects of this application, the following detailed description will be provided in conjunction with specific embodiments. It should be noted that the methods described below are further explanations of this application and should not be construed as limiting its scope.

[0079] Example 1

[0080] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0081] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0082] (II) Carbon micro powder: asphalt powder (particle size 10.00μm): redispersible polymer powder (particle size 80.00μm): polyvinyl alcohol 1788 polymer powder (particle size 100.00μm): polyvinyl alcohol 2488 polymer powder (particle size 100.00μm) at a mass ratio of 100:3:0.3:0.2:1.3 are mixed in a ribbon mixer at a stirring speed of 100 r / min for 10 min. Hydrochloric acid is sprayed at a rate of 5.0 kg / min until the acidity of the mixture reaches 6.1, and then further sprayed at 5.5 kg / min. While spraying and stirring, 20wt.% calcium chloride aqueous solution (mass ratio of carbon micropowder to 20wt.% calcium chloride aqueous solution is 95:25) is added. After mixing at 200r / min for 5min, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0Pa and the buffering time is 15min. The curing material is then sent to a briquetting machine to be briquetized at 9.0MPa to obtain carbon microspheres with a particle size of 25mm. The free fall crushing strength test shows that the free fall crushing strength value is 543mm.

[0083] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1200 mm.

[0084] (iv) Carbon micro powder particles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon micro powder particles. The obtained graphitized carbon micro powder particles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 865 mm, the impurity content was 0.001 wt%, there was no coking in the graphitization furnace, and the degree of graphitization was 95.1%.

[0085] Example 2

[0086] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0087] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0088] (II) The carbon micro powder, asphalt powder (particle size 10.00μm), phenolic resin powder (particle size 20.00μm), polyvinyl alcohol 1788 adhesive powder (particle size 100.00μm), and polyvinyl alcohol 2488 adhesive powder (particle size 100.00μm) are mixed in a ribbon mixer at a mass ratio of 100:1.8:0.3:0.3:1.2. The mixing speed is 100r / min, and the mixing time is 10min. Hydrochloric acid is sprayed at a rate of 5.0kg / min until the acidity of the mixture reaches 6.1. A 20wt.% calcium chloride aqueous solution (mass ratio of carbon micropowder to calcium chloride aqueous solution is 85:25) was added while spraying and stirring at a speed of 5.5 kg / min. After mixing at a speed of 200 r / min for 5 min, the material was sent to a buffer silo for curing and buffering. The pressure inside the buffer silo was -30.0 Pa, and the buffering time was 15 min. The curing material was then sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test showed that the free fall crushing strength value was 450 mm.

[0089] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 901 mm.

[0090] (iv) Carbon micro powder particles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon micro powder particles. The obtained graphitized carbon micro powder particles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 648 mm, the impurity content was 0.001 wt.%, the graphitization degree was 95.0%, and there was no coking in the graphitization furnace.

[0091] Example 3

[0092] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0093] (i) After mixing and batching petroleum raw coke with 6.1% volatile matter and 1.0% sulfur content, it is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a rounded surface.

[0094] (II) Carbon micropowder, phenolic resin (particle size 20.00 μm), and α-corn starch are mixed in a ribbon mixer at a mass ratio of 100:4:3. The mixing speed is 100 r / min and the mixing time is 10 min. Hydrochloric acid is sprayed at a speed of 5.0 kg / min until the acidity of the mixture is 6.1. Then, 20 wt.% calcium chloride aqueous solution (mass ratio of carbon micropowder to 20 wt.% calcium chloride aqueous solution is 95:25) is sprayed at a speed of 5.5 kg / min while stirring. The mixture is mixed at a speed of 200 r / min for 5 min. After mixing, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 15 min. The curing material is sent to a briquetting machine for briquetting at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 595 mm.

[0095] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1075 mm.

[0096] (iv) The graphitized carbon micropowder particles obtained by carbonizing carbon micropowder particles at 1500℃ for 2 hours and then graphitizing them at 3000℃ for 6 hours were subjected to a free fall fracture resistance test. The free fall fracture resistance value was 805 mm, the impurity content was 0.001 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 92.5%.

[0097] Example 4

[0098] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0099] (i) Needle coke with volatile matter of 0.2% and sulfur content of 2.1% and flake graphite are mixed in batches at a weight ratio of 7:3 and continuously fed into a pulverizer to be pulverized to carbon source particles with a maximum particle size of 5mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground to obtain carbon micro powder with a median particle size of 15μm and a smooth surface.

[0100] (II) The carbon micro powder, phenolic resin (particle size 20.00 μm), α-cassava flour (particle size 90.00 μm), and polyvinyl alcohol (particle size 90.00 μm) are mixed in a ribbon mixer at a mass ratio of 100:3:2:1. The mixing speed is 100 r / min, and the mixing time is 10 min. Hydrochloric acid is sprayed at a rate of 5.0 kg / min until the acidity of the mixture reaches 6.1. Then, 20 g of hydrochloric acid is sprayed at a rate of 5.5 kg / min while stirring. A wt.% calcium chloride aqueous solution (the mass ratio of carbon micropowder to 20% calcium chloride aqueous solution is 95:25) is mixed at a speed of 200 r / min for 5 min to achieve uniform mixing. The material is then fed into a buffer silo for curing and buffering. The pressure inside the buffer silo is -30.0 Pa, and the buffering time is 15 min. The curing material is then fed into a briquetting machine and briquetting at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 889 mm.

[0101] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1285 mm.

[0102] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 864 mm. The impurity content was 0.001 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 93.0%.

[0103] Example 5

[0104] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0105] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0106] (II) Carbon micropowder, phenolic resin (particle size 20.00μm), and polyvinyl alcohol 2488 (particle size 90.00μm) are mixed in a ribbon mixer at a mass ratio of 100:4:1. The mixing speed is 100r / min and the mixing time is 10min. Hydrochloric acid is sprayed at a speed of 5.0kg / min until the acidity of the mixture is 5.6. Then, 20wt.% calcium chloride aqueous solution (mass ratio of carbon micropowder to 20wt.% calcium chloride aqueous solution is 95:25) is sprayed at a speed of 5.5kg / min while stirring. The mixture is mixed at a speed of 200r / min for 5min. After mixing, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0Pa and the buffering time is 15min. The curing material is sent to a briquetting machine for briquetting at 9.0MPa to obtain carbon microspheres with a particle size of 25mm. The free fall crushing strength test shows that the free fall crushing strength value is 455mm.

[0107] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1130 mm.

[0108] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test. The free fall fracture resistance value was 875 mm, the impurity content was 0.001 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 93.5%.

[0109] Example 6

[0110] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0111] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0112] (II) The carbon micro powder, asphalt powder (particle size 10.00μm), redispersible polymer powder (particle size 80.00μm), and polyvinyl alcohol 2488 polymer powder (particle size 100.00μm) are mixed in a ribbon mixer at a mass ratio of 100:3:0.3:1.0. The mixing speed is 100r / min, and the mixing time is 10min. Hydrochloric acid is sprayed at a rate of 5.0kg / min until the acidity of the mixture reaches 6.1, and then sprayed at a rate of 5.5kg / min while stirring. Add 20 wt.% calcium chloride aqueous solution (the mass ratio of carbon micropowder to 20 wt.% calcium chloride aqueous solution is 95:25), mix at 200 r / min for 5 min to achieve uniform mixing, and then send the material into a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa, and the buffering time is 15 min. The curing material is then sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. After a free fall crushing strength test, the free fall crushing strength value is 475 mm.

[0113] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1045 mm.

[0114] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 770 mm, the impurity content was 0.001 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 95.3%.

[0115] Example 7

[0116] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0117] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0118] (II) The carbon micro powder, asphalt powder (particle size 10.00μm), redispersible polymer powder (particle size 80.00μm), and polyvinyl alcohol 1788 polymer powder (particle size 100.00μm) are mixed in a ribbon mixer at a mass ratio of 100:3:0.3:1.0. The mixing speed is 100r / min, and the mixing time is 10min. Hydrochloric acid is sprayed at a rate of 5.0kg / min until the acidity of the mixture reaches 6.1, and then sprayed at a rate of 5.5kg / min while stirring. Add 20 wt.% calcium chloride aqueous solution (the mass ratio of carbon micropowder to 20 wt.% calcium chloride aqueous solution is 95:25), mix at 200 r / min for 5 min to achieve uniform mixing, and then send the material into a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa, and the buffering time is 15 min. The curing material is then sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. After a free fall crushing strength test, the free fall crushing strength value is 471 mm.

[0119] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1039 mm.

[0120] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 765 mm. The impurity content was 0.001 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 95.3%.

[0121] Example 8

[0122] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0123] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0124] (II) The carbon micro powder, phenolic resin (particle size 30.00 μm), asphalt powder (particle size 20.00 μm), redispersible polymer powder (particle size 95.00 μm), and polyvinyl alcohol 2488 polymer powder (particle size 85.00 μm) are mixed in a ribbon mixer at a mass ratio of 100:1:1:0.5:1. The mixing speed is 100 r / min, and the mixing time is 10 min. Hydrochloric acid is sprayed at a rate of 5.0 kg / min until the acidity of the mixture reaches 6.1. Then, hydrochloric acid is sprayed at a rate of 5.5 kg / min. While spraying and stirring, 20 wt.% calcium chloride aqueous solution (mass ratio of carbon micropowder to calcium chloride aqueous solution is 95:25) is added. After mixing at 200 r / min for 5 min, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa, and the buffering time is 15 min. The curing material is then sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 510 mm.

[0125] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 875 mm.

[0126] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test. The free fall fracture resistance value was 630 mm, the impurity content was 0.001 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 94.7%.

[0127] Example 9

[0128] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0129] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0130] (II) Carbon micropowder, modified urea-formaldehyde resin (particle size 45.00μm), and corn starch (particle size 10.00μm) are mixed in a ribbon mixer at a mass ratio of 100:4:4. The mixing speed is 100r / min and the mixing time is 10min. Hydrochloric acid is sprayed at a speed of 5.0kg / min until the acidity of the mixture is 6.1. Then, 20wt.% calcium chloride aqueous solution (mass ratio of carbon micropowder to 20wt.% calcium chloride aqueous solution is 95:25) is sprayed at a speed of 5.5kg / min while stirring. The mixture is mixed at a speed of 200r / min for 5min. After mixing, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0Pa and the buffering time is 15min. The curing material is sent to a briquetting machine for briquetting at 9.0MPa to obtain carbon microspheres with a particle size of 25mm. The free fall crushing strength test shows that the free fall crushing strength value is 800mm.

[0131] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1160 mm.

[0132] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 837 mm, the impurity content was 0.002 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 92.0%.

[0133] Example 10

[0134] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0135] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0136] (II) Carbon micro powder, phenolic resin (particle size 20.00 μm), and corn starch (particle size 10.00 μm) are mixed in a ribbon mixer at a mass ratio of 100:4:4. The mixing speed is 100 r / min, and the mixing time is 10 min. Citric acid solution (carbon micro powder: 5% citric acid solution mass ratio 100:1, the amount of citric acid solution is enough to make the acidity of the mixture 5.6) and 20 wt.% calcium chloride aqueous solution (carbon micro powder and 20 wt.% calcium chloride aqueous solution) are added. The liquid (mass ratio of 95:23) is first mixed, then sprayed into the ribbon mixer at a speed of 5.5 kg / min, and mixed at a speed of 200 r / min for 5 minutes. After mixing, the material is sent to the buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa, and the buffering time is 15 minutes. The curing material is sent to the briquetting machine for briquetting at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. After free fall crushing strength test, its free fall crushing strength value is 801 mm.

[0137] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1163 mm.

[0138] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 839 mm. The impurity content was 0.002 wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 92.1%.

[0139] Example 11

[0140] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0141] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0142] (II) First, mix citric acid powder (the amount of citric acid should be sufficient to achieve an acidity value of 5.8 in the mixture) and phenolic resin (particle size 20.00 μm) + calcium chloride powder (particle size 80.00 μm), with a mass ratio of carbon micropowder and phenolic resin + calcium chloride powder of 100:2:3. Then, mix this mixture with the carbon micropowder in a ribbon mixer at a stirring speed of 100 r / min for 10 min. Finally, spray 20 wt.% of the mixture at a speed of 5.5 kg / min. Liquid asphalt adhesive with a solid content (mass ratio of carbon micropowder to liquid asphalt adhesive of 90:23) was mixed at a speed of 200 r / min for 5 min to achieve uniformity. The material was then fed into a buffer silo for curing and buffering. The pressure inside the buffer silo was -30.0 Pa, and the buffering time was 15 min. The curing material was then fed into a briquetting machine and briquetting at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test showed that the free fall crushing strength value was 766 mm.

[0143] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1297 mm.

[0144] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 945 mm. The impurity content was 0.002 wt.%, and no coking was observed in the graphitization furnace. The graphitized particles did not require crushing or grinding, and the degree of graphitization was 95.0%.

[0145] Example 12

[0146] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0147] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0148] (II) Carbon micropowder, phenolic resin (particle size 20μm), and polyvinyl alcohol 2488 (particle size 90μm) are mixed in a ribbon mixer at a mass ratio of 100:3:1. The mixing speed is 100r / min and the mixing time is 10min. Hydrochloric acid is sprayed at a speed of 5.0kg / min until the acidity of the mixture is 6.1. Then, 15wt.% calcium chloride solution (mass ratio of carbon micropowder to 15wt.% calcium chloride solution is 95:25) is sprayed at a speed of 5.5kg / min while stirring. The mixture is mixed at a speed of 200r / min for 5min. After mixing, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0Pa and the buffering time is 15min. The curing material is sent to a briquetting machine for briquetting at 9.0MPa to obtain carbon microspheres with a particle size of 25mm. The free fall crushing strength test shows that the free fall crushing strength value is 453mm.

[0149] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 997 mm.

[0150] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 719 mm. The impurity content was 0.001 wt.%, no coking was observed in the graphitization furnace, and the degree of graphitization was 94.0%.

[0151] Example 13

[0152] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0153] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0154] (II) Carbon micro powder, phenolic resin (particle size 30.00 μm), asphalt (particle size 20.00 μm), redispersible polymer powder (particle size 15.00 μm), and vinyl alcohol polymer powder (particle size 15.00 μm) are mixed in a ribbon mixer at a mass ratio of 100:1:1:1:1. The mixing speed is 100 r / min, and the mixing time is 10 min. Hydrochloric acid is sprayed at a rate of 5.0 kg / min until the acidity of the mixture reaches 6.1, and then sprayed at a rate of 5.5 kg / min while stirring. Add 15wt.% calcium chloride solution while stirring (the mass ratio of carbon micropowder to 15wt.% calcium chloride solution added while stirring is 95:20). Mix at 200r / min for 5min until homogeneous. Then, send the material into a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0Pa and the buffering time is 15min. The curing material is then sent to a briquetting machine to be briquetized at 9.0MPa to obtain carbon microspheres with a particle size of 25mm. The free fall crushing strength test shows that the free fall crushing strength value is 597mm.

[0155] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 993 mm.

[0156] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 708 mm. The impurity content was 0.001 wt.%, no coking was observed in the graphitization furnace, and the degree of graphitization was 94.5%.

[0157] Example 14

[0158] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0159] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 4.5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 10 μm and a smooth surface.

[0160] (II) Carbon micro powder and phenolic resin (particle size 20.00 μm) + polyvinyl alcohol powder (particle size 75.00 μm) + calcium chloride powder (particle size 80.00 μm) are mixed in a ribbon mixer at a mass ratio of 100:1:0.5:3.5. The mixing speed is 100 r / min and the mixing time is 10 min. Hydrochloric acid is sprayed at a rate of 5.0 kg / min until the acidity of the mixture is 6.1, and then sprayed at a rate of 5.5 kg / min while stirring. Add 25% solid content liquid asphalt adhesive (mass ratio of carbon micro powder to liquid asphalt adhesive is 80:18) to the mixing side, mix at 200 r / min for 5 min to mix evenly, and then send the material into the buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 10 min. The curing material is sent into the briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 20 mm. After free fall crushing strength test, its free fall crushing strength value is 829 mm.

[0161] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1219 mm.

[0162] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 903 mm, the impurity content was 0.002 wt.%, no coking was observed in the graphitization furnace, and the degree of graphitization was 95.5%.

[0163] Example 15

[0164] This embodiment describes a process for preparing carbon micropowder particles, which includes the following steps.

[0165] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0166] (II) Carbon micropowder, phenolic resin (particle size 20.00 μm), and calcium chloride powder are mixed in a single-cone double-spiral mixer at a mass ratio of 100:4:2. The mixing speed is 120 r / min, and the mixing time is 15 min. Hydrochloric acid is sprayed at a rate of 8.0 kg / min until the acidity of the mixture reaches 6.1. Then, liquid asphalt adhesive with a solid content of 10% (mass ratio of carbon micropowder to liquid asphalt adhesive is 90:20) is sprayed at a rate of 7.5 kg / min while stirring. The mixture is then sprayed at 230 r / min. After mixing at a speed of / min for 8 minutes, the material is sent to a buffer silo for curing and buffering. The pressure inside the buffer silo is -20.0Pa, and the buffering time is 15 minutes. The curing material is then sent to a briquetting machine at 9.0MPa for briquetting. The resulting carbon microspheres have a particle size of 5mm to 10mm, accounting for 15%, a particle size of 10mm to 20mm, accounting for 30%, and a particle size of 20mm to 30mm, accounting for 55%. The free fall crushing strength test shows that the free fall crushing strength value is 407mm.

[0167] (III) The carbon microspheres were first dried at 80℃ for 1 hour, then baked at 120℃ for 2 hours, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1189 mm.

[0168] (iv) Carbon microparticles were carbonized at 1700℃ for 1.5h and then graphitized at 3100℃ for 5h to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 891mm, the impurity content was 0.001wt.%, there was no coking in the graphitization furnace, and the degree of graphitization was 94.0%.

[0169] Comparative Example 1

[0170] This comparative example illustrates the preparation process of a type of carbon microparticle, which includes the following steps.

[0171] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0172] (II) The carbon micro powder is mixed in a ribbon mixer, and then 38% organic solvent liquid asphalt adhesive (mass ratio of carbon micro powder to organic solvent liquid asphalt adhesive is 80:20) is sprayed at a speed of 5.5 kg / min while stirring. After mixing at a speed of 200 r / min for 5 min, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 15 min. The curing material is sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 1093 mm.

[0173] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1752 mm.

[0174] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 1473 mm, the impurity content was 0.049 wt.%, and the graphitization degree was 95.0%. High melting point impurities were enriched and coked in the graphitization heat treatment furnace.

[0175] Comparative Example 2

[0176] This comparative example illustrates the preparation process of a type of carbon microparticle, which includes the following steps.

[0177] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0178] (II) Carbon micro powder and phenolic resin adhesive (solid content of 35%) are mixed in a ribbon mixer at a mass ratio of 80:20. After mixing at a speed of 200 r / min for 5 min, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 15 min. The curing material is sent to a briquetting machine for briquetting at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 1012 mm.

[0179] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01wt.% to obtain carbon micro powder particles. The obtained carbon micro powder particles were subjected to free fall crushing strength test, and the free fall crushing strength value was 1675mm. The particles had extremely high strength after drying and baking.

[0180] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 1355 mm, the impurity content was 0.045 wt.%, and the graphitization degree was 91.6%. High melting point impurities were enriched and coked in the graphitization heat treatment furnace.

[0181] Comparative Example 3

[0182] This comparative example illustrates the preparation process of a type of carbon microparticle, which includes the following steps.

[0183] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0184] (II) The carbon micropowder is mixed in a ribbon mixer at a stirring speed of 100 r / min. Hydrochloric acid is sprayed at a speed of 5.0 kg / min until the acidity of the mixture is 6.1. Then, 30% solid content emulsified liquid asphalt adhesive (mass ratio of carbon micropowder to emulsified liquid asphalt adhesive is 90:20) is sprayed at a speed of 5.5 kg / min while stirring. After mixing at a speed of 200 r / min for 5 minutes, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 15 minutes. The curing material is sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 857 mm.

[0185] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1352 mm.

[0186] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 991 mm, the impurity content was 0.001 wt.%, and the graphitization degree was 95.0%. High melting point impurities were enriched and coked in the graphitization heat treatment furnace.

[0187] Comparative Example 4

[0188] This comparative example illustrates the preparation process of a type of carbon microparticle, which includes the following steps.

[0189] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0190] (II) Carbon micro powder, phenolic resin powder (particle size 20.00 μm) and α-cassava flour are mixed in a ribbon mixer at a mass ratio of 100:1:4. The mixing speed is 100 r / min and the mixing time is 10 min. 0.01 mol hydrochloric acid aqueous solution is sprayed at a speed of 5.0 kg / min until the acidity of the mixture is 6.1 and the moisture content of the carbon micro powder is 20%. After mixing at a speed of 200 r / min for 5 min, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 15 min. The curing material is sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 983 mm.

[0191] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1593 mm.

[0192] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 1327 mm, the impurity content was 0.001 wt.%, and the graphitization degree was 91.1%. High melting point impurities were enriched and coked in the graphitization heat treatment furnace.

[0193] Comparative Example 5

[0194] This comparative example illustrates the preparation process of a type of carbon microparticle, which includes the following steps.

[0195] (i) After mixing and batching petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1%, the coke is continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles are then directly and continuously fed into a grinding granulator to be ground into carbon micro powder with a median particle size of 15 μm and a smooth surface.

[0196] (II) Carbon micro powder and phenolic resin (particle size 20.00 μm) are mixed in a ribbon mixer at a mass ratio of 100:4. The mixing speed is 100 r / min and the mixing time is 10 min. 30% solid content emulsified liquid asphalt adhesive (mass ratio of carbon micro powder to emulsified liquid asphalt adhesive is 90:22) is sprayed at a speed of 5.5 kg / min while stirring. After mixing at a speed of 200 r / min for 5 min, the material is sent to a buffer silo for curing and buffering. The pressure in the buffer silo is -30.0 Pa and the buffering time is 15 min. The curing material is sent to a briquetting machine to be briquetized at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free fall crushing strength test shows that the free fall crushing strength value is 987 mm.

[0197] (III) The carbon microspheres were first dried at 55℃ for 1 hour, then baked at 120℃ for 1 hour, and then heated to 250℃ and baked until the moisture content was 0.01 wt.% to obtain carbon micropowder particles. The obtained carbon micropowder particles were subjected to a free fall fracture resistance test, and the free fall fracture resistance value was 1879 mm.

[0198] (iv) Carbon microparticles were carbonized at 1500℃ for 2 hours and then graphitized at 3000℃ for 6 hours to obtain graphitized carbon microparticles. The obtained graphitized carbon microparticles were subjected to free fall fracture resistance test. The free fall fracture resistance value was 1633 mm, the impurity content was 0.047 wt.%, and the graphitization degree was 92.9%. High melting point impurities were enriched and coked in the graphitization heat treatment furnace.

[0199] The performance parameters of the carbon micropowder graphitized particles of Examples 1 to 15 and Comparative Examples 1 to 5 are shown in Table 2.

[0200] Table 2 shows the performance of carbon micronized graphitized particles in Examples 1 to 15 and Comparative Examples 1 to 5.

[0201] A comparison of Examples 1 to 15 and Comparative Examples 1 to 5 of this application shows that the free-fall fracture strength of the graphitized carbon micropowder particles prepared by the process of this application is 350 mm to 950 mm, and the total content of metal elemental and metal compound impurities is ≤0.002 wt.%. This is because the production process of this application utilizes the adhesive properties of liquid additives to first form a kneaded state with a certain strength between the dry powder additives and carbon micropowder after pressing. Under the action of liquid additives and acidifiers, the dry powder additives are evenly dispersed on the surface of the carbon micropowder. After subsequent drying and baking, the thermal melting of the dry powder additives can further improve the fracture strength to 500 mm to 1300 mm. The graphitized carbon micropowder particles obtained after carbonization and graphitization can maintain a suitable free-fall fracture strength value. The addition of acidifiers can react with the high melting point and high volatility point metal elemental and metal compound impurities in the carbon micropowder, transforming them into low melting point and low boiling point compounds, which can be volatilized and removed under low temperature conditions. Hydrochloric acid is the best acidifier.

[0202] Comparative studies of Examples 1 and 6-8 show that the dry powder additive, a mixture of resin powder and adhesive powder, especially a mixture of phenolic resin, asphalt, redispersible adhesive powder, and polyvinyl alcohol adhesive powder, exhibits superior performance. This may be due to synergistic effects among the four components. Comparative studies of Examples 1 to 15 show that the liquid additive, an inorganic salt solution, performs even better when used in combination with the dry powder additive (a mixture of resin powder and adhesive powder).

[0203] Comparing Examples 1 and 2, it is evident that the dry powder additive redispersible polymer powder has a certain water-reducing effect, which can reduce the amount of water-based liquid additives, improve the density of the briquettes, and increase the free-fall crushing strength of the particles. Compared to Example 1, Comparative Example 1, due to the use of only liquid asphalt adhesive, has a high initial viscosity, and the particles soften as the asphalt melts during the drying and baking process, exhibiting some adhesion. Furthermore, the graphitized particles have excessively high strength, requiring crushing and grinding, which affects the product yield and performance (likely due to excessive asphalt content). Additionally, the absence of hydrochloric acid and calcium chloride in Example 1 results in a higher impurity content in the graphitized product, leading to the accumulation and coking of high-melting-point impurities in the graphitization heat treatment furnace.

[0204] Compared to Example 1, Comparative Example 2 used phenolic resin adhesive alone, resulting in excessively high strength graphitized particles that required crushing and grinding, affecting product yield and performance. Furthermore, the absence of hydrochloric acid and calcium chloride in Example 1 led to higher impurity content in the graphitized product, resulting in the accumulation and coking of high-melting-point impurities in the graphitization heat treatment furnace.

[0205] Compared to Example 1, Comparative Example 3, which used emulsified liquid asphalt adhesive alone, had a high initial viscosity. During the drying and baking process, the particles softened as the asphalt melted, and there was some adhesion. The graphitized particles had excessively high strength, requiring crushing and grinding, which affected the product yield and performance (likely due to the excessive amount of emulsified asphalt added). Furthermore, it lacked the calcium chloride found in Example 1, and high-melting-point impurities accumulated and coked in the graphitization heat treatment furnace.

[0206] Compared with Example 1, Comparative Example 4 did not add liquid additive calcium chloride, and the graphitization heat treatment furnace showed enrichment and coking of high melting point impurities.

[0207] Compared with Example 1, Comparative Example 5 did not add an acidifying agent, and the graphitized product had a higher impurity content; without the addition of calcium chloride, high-melting-point impurities were enriched and coked in the graphitization heat treatment furnace.

[0208] As can be seen from Example 1 and Comparative Examples 1 to 5, asphalt additives are beneficial for obtaining products with higher graphitization, while hard carbon additives such as phenolic resin and α-cassava flour will cause a decrease in the graphitization of the product.

[0209] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A process for the preparation of graphitized particles of carbon fines, characterized in that, The application comprises the following steps: (1) treating the carbon source to obtain carbon micro-powder; (2) mixing the carbon micro-powder with dry powder additives, acidifying agent and liquid additives and then compressing to obtain carbon micro-spheres; (3) drying and baking the carbon micro-spheres to obtain carbon micro-powder particles; (4) carbonizing and graphitizing the carbon micro-powder particles to obtain carbon micro-powder graphitized particles.

2. The process for preparing graphitized particles of carbon fines according to claim 1, characterized in that, The carbon micro-powder is mixed with the dry powder additives first and then mixed with the liquid additives.

3. The process for preparing graphitized particles of carbon fines according to claim 2, characterized in that, Any one of the following features (I) to (VII) is included: (I) the dry powder additives include at least one of resin powder, polysaccharide powder, glue powder and inorganic salt powder; (II) the dry powder additives include at least two of phenolic resin glue powder, modified urea-formaldehyde resin glue powder, pitch powder, alpha starch, sugar powder, cellulose powder, redispersible glue powder, polyvinyl alcohol glue powder, latex powder, sodium silicate, calcium chloride, ferric chloride, ferrous chloride and aluminum phosphate; (III) the dry powder additives include resin powder and glue powder; (IV) the dry powder additives include phenolic resin, pitch, redispersible glue powder and polyvinyl alcohol glue powder; (V) the liquid additives include at least one of resin glue, inorganic salt solution and solvent; (VI) the liquid additives include at least two of urea-formaldehyde resin glue, epoxy resin glue, phenolic resin glue, liquid pitch glue, latex, water glass, calcium chloride solution, ferric chloride solution, ferrous chloride solution, water, ethanol, methanol, acetone, xylene, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether and propylene glycol methyl ether; (VII) the liquid additives include inorganic salt solution and water.

4. The process for preparing graphitized particles of carbon fines according to claim 1, characterized in that, The acidifying agent includes liquid acidifying agent and / or solid acidifying agent.

5. The process for preparing graphitized particles of carbon fines according to claim 4, characterized in that, Any one of the following features ① to ⑦ is included: ① the liquid acidifying agent includes at least one of nitric acid, hydrochloric acid, acrylic acid, tartaric acid solution, citric acid solution and oxalic acid solution; ② the solid acidifying agent includes at least one of tartaric acid powder, citric acid powder and oxalic acid powder; ③ the liquid acidifying agent is added after mixing the dry powder additives and before mixing the liquid additives; ④ the liquid acidifying agent is mixed with the liquid additives first and then added together after mixing the dry powder additives; ⑤ the solid acidifying agent is mixed with the dry powder additives first and then added together into the carbon micro-powder before mixing the liquid additives; ⑥ the carbon micro-powder is mixed with the dry powder additives, the solid acidifying agent and the liquid additives in sequence; ⑦ the liquid acidifying agent is added by spraying, and the spraying speed is 0.5 kg / min to 10.0 kg / min.

6. The process for preparing graphitized particles of carbon fines according to claim 1, characterized in that, At least one of the following features (1) to (13) is included: (1) the volatile content of the carbon source is 0.1% to 15.0%; (2) the sulfur content of the carbon source is 0.05% to 3.0%; (3) the mass ratio of the carbon micro-powder to the dry powder additives is 100:1~8; (4) the amount of the acidifying agent is controlled to make the acidity value of the carbon micro-powder be 5.5 to 6.9; (5) the mass ratio of the carbon micro-powder to the liquid additives is 50~100:6~25; (6) the particle size distribution of the dry powder additives is 0.01 μm to 100.00 μm; (7) the mixing of the carbon micro-powder and the dry powder additive is performed using a mixer, the stirring speed of the dry powder mixer is 30 r / min to 200 r / min, and the stirring time is 2 min to 15 min; (8) the mixing of the carbon micro-powder and the dry powder additive is performed using a mixer, the mixer includes a screw ribbon mixer, a single-cone double-screw mixer, a horizontal plough mixer, or a rubber sand mixer; (9) the liquid additive is added using a spraying method, and the spraying speed is 0.5 kg / min to 10.0 kg / min; (10) the mixing speed after the addition of the liquid additive is 60 r / min to 300 r / min, and the mixing time is 3 min to 8 min; (11) the pre-treatment includes crushing the carbon source to a particle size of 0.01 mm to 5.00 mm, and then grinding to obtain the carbon micro-powder with a particle size of 5 μm to 20 μm; (12) the pressing includes first buffering the mixed material, and then pressing the material in a ball press to obtain the carbon micro-spheres with a particle size of 5 mm to 35 mm, the buffering pressure is -0.001 kPa to -30.0 kPa, the buffering time is 10 min to 30 min, and the pressure of the ball press is 4.5 MPa to 9.5 MPa; (13) the carbon micro-spheres are first dried at 30 °C to 105 °C, and then baked at 95-105 °C to 280-300 °C to obtain the carbon micro-powder particles with a water content of 0.01 wt.% or less.

7. The carbon-fine-graphitized-particle prepared by the production process of carbon-fine-graphitized-particle according to claim 1, characterized by, The initial free-fall anti-crushing strength value of the carbon micro-spheres is 400 mm to 1000 mm.

8. The carbon-fine-graphitized-particle prepared by the production process of carbon-fine-graphitized-particle according to claim 1, characterized by, The free-fall anti-crushing strength value of the carbon micro-powder particles is 500 mm to 1300 mm.

9. The carbon-fine-graphitized-particle prepared by the production process of carbon-fine-graphitized-particle according to claim 1, characterized by, The free-fall anti-crushing strength value of the carbon micro-powder graphitized particles is 350 mm to 950 mm.

10. The carbon-fine-graphitized-particle prepared by the production process of carbon-fine-graphitized-particle according to any one of claims 7 to 9, characterized by, The free-fall anti-crushing strength value is obtained by testing the limit height value of the particles that remain intact and do not break after free-fall.

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