Preparation process of carbon micro-powder graphitized particles and carbon micro-powder graphitized particles

Abstract

The invention provides a preparation process of carbon micro-powder graphitized particles and the carbon micro-powder graphitized particles. The preparation process of the carbon micro-powder graphitized particles comprises the following steps: pre-treating a carbon source to obtain carbon micro-powder; mixing and pressing the carbon micro powder, a dry powder additive, an acidifying agent and a liquid additive to prepare carbon microspheres; and drying and baking the carbon microspheres to obtain carbon micro-powder particles, and then carbonizing and graphitizing the carbon micro-powder particles to obtain carbon micro-powder graphitized particles. According to the preparation process disclosed by the invention, the carbon microspheres, the carbon micro-powder particles and the carbon micro-powder graphitized particles with certain strength can be prepared so as to prevent the particles from being flushed away during subsequent vertical continuous graphitization, and the mass of impurities with high melting point and high boiling point contained in the prepared carbon micro-powder particles can be effectively reduced through micro-acidification treatment; the eutectic point of the impurities is reduced through the blend, so that the high-melting-point impurities are effectively prevented from being enriched, coked and hardened in the graphitization furnace; in addition, the obtained carbon micro-powder graphitized particles are easy to scatter and do not need to be crushed and ground.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon materials, in particular to a precursor of negative electrode material, and more particularly to a preparation process of carbon micro-powder graphitized particles and the carbon micro-powder graphitized particles. BACKGROUND

[0002] In the artificial graphite negative electrode material industry, in order to overcome the disadvantages of long process cycle and high energy consumption of the intermittent graphitization process such as Acheson furnace, internal string furnace or compartment furnace, vertical continuous graphitization process and equipment have become one of the popular research and development directions.

[0003] However, the vertical continuous graphitization process requires that the charging material be in the form of particles, not powder, otherwise the high-volatile-point impurities in the furnace will gasify and overflow, causing the carbon micro-powder to be washed away, and when the gas overflow channel is not smooth, a furnace explosion accident may occur. Therefore, the existing technology mainly uses cassava powder plus water or corn starch plus PVA water-based glue to stew in one pot to make the carbon micro-powder into particles. However, the carbonized cassava powder and corn starch have no strength, and PVA has a characteristic that between 100℃ and 300℃, it will undergo glass transition and become brittle, resulting in the carbon micro-powder particles having the defect of low strength. The existing technology usually increases the amount of PVA binder to compensate for this defect, but this causes the obtained graphitized particles to have high strength, which needs to be crushed and ground later, resulting in the final material having a rough surface, low tap density and low product quality.

[0004] In addition, the high-melting-point and high-volatile-point impurities such as Fe2O3, Fe, CaO, SiO2, CaSiO4, Cr, Co, Ni, etc. in the carbon micro-powder are enriched and caked on the coke plate in the vertical graphitization furnace, which also poses a safety hazard of pressure build-up and furnace explosion. At the same time, a large amount of gas will overflow at high temperature, causing the loss of carbon micro-powder being washed away.

[0005] Therefore, it is necessary to provide a preparation process of carbon micro-powder graphitized particles and the carbon micro-powder graphitized particles to overcome the above-mentioned defects and safety hazards of the existing technology, and to achieve the industrialization implementation of the vertical continuous graphitization process. SUMMARY

[0006] In view of the above problems, the purpose of the present application is to provide a preparation process of carbon micro-powder graphitized particles and the carbon micro-powder graphitized particles, which can produce carbon micro-powder particles with certain strength to prevent them from being washed away during subsequent vertical continuous graphitization, and the carbon micro-powder particles produced by the process contain less high-melting-point and high-volatile-point impurities, avoiding the enrichment and caking of high-melting-point and high-volatile-point impurities on the coke plate in the graphitization furnace. In addition, the obtained carbon micro-powder graphitized particles are easy to break apart and do not need to be crushed and ground.

[0007] To achieve the above-mentioned purpose, the present application provides a preparation process of carbon micro-powder graphitized particles, comprising:

[0008] (I) pre-treating the carbon source to obtain carbon micro-powder;

[0009] (II) mixing and compressing the carbon micro-powder and dry powder additives, acidifying agent and liquid additives to obtain carbon micro-spheres;

[0010] (III) drying and baking the carbon micro-spheres to obtain carbon micro-powder particles;

[0011] (IV) carbonizing and graphitizing the carbon micro-powder particles to obtain carbon micro-powder graphitized particles.

[0012] The technical solution adopted in the present application has at least the following technical effects.

[0013] (1) The dry powder additives and carbon micro-powder are kneaded into a certain strength after compression by using the adhesion of the liquid additives, and the dry powder additives are uniformly dispersed and adhered to the surface of the carbon micro-powder under the action of the liquid additives and acidifying agent to provide initial strength to the compressed carbon micro-spheres (the free-fall anti-breaking strength can be 400mm to 1000mm), and then the dry powder additives are further improved by subsequent drying and baking, and the free-fall anti-breaking strength of the carbon micro-powder particles can be further improved to 500mm to 1300mm, and finally the free-fall anti-breaking strength of the carbon micro-powder graphitized particles obtained by carbonization and graphitization is 350mm to 950mm. In addition, the dry powder additives have high fluidity after melting and can fill into the pores, pits or grooves of the carbon micro-powder, so that the carbon micro-powder has a smoother appearance. The carbon micro-powder particles have a certain free-fall anti-breaking strength, which can not only ensure that they are not easily washed away by the overflow gas even when they enter the vertical continuous graphitization equipment, but also can avoid the rough surface of the material caused by excessive strength during subsequent processing. In addition, the liquid additives not only provide adhesion strength to the carbon micro-powder particles, but also form a low-melting-point eutectic body with high-melting-point impurities in the carbon micro-powder, which can avoid the accumulation and hardening of high-melting-point impurities in the furnace during graphitization, so as to achieve the industrialization of the continuous graphitization process.

[0014] (2) Adding acidifying agent can react with high melting point and high volatile point metal elements and metal compound impurities in carbon powder, and convert them into low melting point and low boiling point metal elements and metal compounds (such as converting Fe2O3 with melting point of 1565℃ and boiling point of 3414℃ and metal Fe with boiling point of 2750℃ into FeCl3 with melting point of 306℃ and boiling point of 319℃, CaO into CaCl2, Cr, Co, Ni into CrCl3, CoCl2, NiCl3 respectively), so that low temperature impurity removal can be carried out through subsequent low temperature baking, and high melting point and high volatile point metal elements and metal compound impurities can be prevented from being enriched and caked in the subsequent graphitization furnace. In addition, the amount of high temperature gas generated during high temperature graphitization of high melting point and high volatile point metal elements and metal compound impurities and the consumption of carbon source in carbon powder by high melting point and high volatile point metal elements and metal compound impurities can also be reduced.

[0015] As a technical solution of the present application, the carbon source includes coke-based powder and / or graphite powder.

[0016] As a technical solution of the present application, the coke-based powder includes one or more of needle coke, petroleum calcined coke, petroleum green coke, petroleum semi-calcined coke, pitch coke, anthracite and biomass charcoal.

[0017] As a technical solution of the present application, the graphite powder includes at least one of flake graphite, microcrystalline graphite and spherical graphite.

[0018] As a technical solution of the present application, the carbon powder is mixed with the dry powder additive first and then mixed with the liquid additive.

[0019] As a technical solution of the present application, the dry powder additive includes at least one of resin powder, polysaccharide powder, glue powder and inorganic salt powder.

[0020] As a technical solution of the present application, the dry powder additive includes 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.

[0021] As a technical solution of the present application, the dry powder additive includes resin powder and glue powder.

[0022] As a technical solution of the present application, the dry powder additive includes phenolic resin, pitch, redispersible glue powder and polyvinyl alcohol glue powder.

[0023] As a technical solution of the present application, the liquid additive includes at least one of resin glue, inorganic salt solution and solvent.

[0024] As one technical solution of the present invention, 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.

[0025] As one technical solution of the present invention, the liquid additive includes an inorganic salt solution and water.

[0026] As one technical solution of the present invention, the acidifying agent includes liquid acidifying agents and / or solid acidifying agents.

[0027] As one technical solution of the present invention, 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.

[0028] As a technical solution of the present invention, the solid acidifying agent includes at least one of tartaric acid powder, citric acid powder and oxalic acid powder.

[0029] As a technical solution of the present invention, the liquid acidifier is added after mixing the dry powder additive and before mixing the liquid additive.

[0030] As a technical solution of the present invention, the liquid acidifier is first mixed with the liquid additive and then mixed together with the dry powder additive.

[0031] As a technical solution of the present invention, the solid acidifier is first mixed with the dry powder additive before being added to the carbon micro powder.

[0032] As a technical solution of the present invention, the carbon micro powder is mixed sequentially with the dry powder additive, the solid acidifier, and the liquid additive.

[0033] As a technical solution of the present invention, the liquid acidifier is added by spraying, and the spraying speed is from 0.5 kg / min to 10.0 kg / min.

[0034] As one technical solution of the present invention, the median particle size of the carbon source is 5 μm to 25 μm.

[0035] As one technical solution of the present invention, the carbon source has a carbon content ≥80 wt.%.

[0036] As one technical solution of the present invention, the volatile matter content of the carbon source is 0.1% to 15.0%.

[0037] As one technical solution of the present invention, the sulfur content of the carbon source is 1.0% to 3.0%.

[0038] As a technical scheme of the present application, the mass ratio of the carbon micro-powder and the dry powder additive is 100:1-8.

[0039] As a technical scheme of the present application, the amount of the acidifier is controlled to make the acidity value of the carbon micro-powder be 5.5-6.9.

[0040] As a technical scheme of the present application, the mass ratio of the carbon micro-powder and the liquid additive is 50-100:6-25.

[0041] As a technical scheme of the present application, the particle size distribution of the dry powder additive is 0.01 μm-100.00 μm.

[0042] As a technical scheme of the present application, the mixing of the carbon micro-powder and the dry powder additive is carried out by using a mixer, the stirring speed of the dry powder mixer is 30 r / min-200 r / min, and the stirring time is 2 min-15 min.

[0043] As a technical scheme of the present application, the mixing of the carbon micro-powder and the dry powder additive is carried out by using a mixer, the mixer includes a screw belt mixer, a single-cone double-screw mixer, a horizontal plough mixer or a rubber sand mixer, the liquid additive is added by using a spraying type, and the spraying speed is 0.5 kg / min-10.0 kg / min.

[0044] As a technical scheme of the present application, the mixing speed after adding the liquid additive is 60 r / min-300 r / min, and the mixing time is 3 min-8 min.

[0045] As a technical scheme of the present application, the pretreatment includes crushing the carbon source to a particle size of 0.01 mm-5.00 mm, and then grinding to obtain the carbon micro-powder with a particle size of 5 μm-20 μm.

[0046] As a technical scheme of the present application, 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-35 mm, the buffering pressure is -0.001 kPa--30.0 kPa, the buffering time is 10 min-30 min, and the pressure of the ball press is 4.5 MPa-9.5 MPa.

[0047] As a technical scheme of the present application, the carbon micro-spheres are first dried at 30 ℃-105 ℃, and then baked at 95-105 ℃-280-300 ℃ to obtain the carbon micro-powder particles with a water content of 0.01 wt.% or less.

[0048] The second aspect of the present application provides the carbon micro-powder graphitized particles prepared by the preparation process of the aforementioned micro-powder graphitized particles, wherein the free-fall anti-crushing strength value of the carbon micro-powder graphitized particles is set to 400mm to 1000mm.

[0049] The third aspect of the present application provides the carbon micro-powder graphitized particles prepared by the preparation process of the aforementioned micro-powder graphitized particles, wherein the free-fall anti-crushing strength value of the carbon micro-powder graphitized particles is set to 500mm to 1300mm.

[0050] The fourth aspect of the present application provides the carbon micro-powder graphitized particles prepared by the preparation process of the aforementioned micro-powder graphitized particles, wherein the free-fall anti-crushing strength value of the carbon micro-powder graphitized particles is set to 350mm to 950mm.

[0051] As a technical solution of the present application, the free-fall anti-crushing strength value is obtained by testing the limit height value of the particles keeping intact and not crushing through free fall. DETAILED DESCRIPTION

[0052] The present application provides a preparation process of carbon micro-powder graphitized particles and carbon micro-powder graphitized particles. The free-fall anti-crushing strength value of the carbon micro-powder graphitized particles is 350mm to 950mm, which can be but not limited to 150mm, 180mm, 200mm, 250mm, 300mm, 350mm. The carbon micro-powder graphitized particles with this strength are beneficial to the processing and manufacturing of the negative electrode sheet in the later stage.

[0053] The present application provides a preparation process of carbon micro-powder graphitized particles, which comprises steps (I), (II), (III) and (IV).

[0054] The step (1) comprises pre-treating the carbon source to obtain carbon micropowder. The carbon source comprises coke powder and / or graphite powder. The coke powder comprises one or more of needle coke, petroleum calcined coke, petroleum green coke, petroleum semi-calcined coke, pitch coke, anthracite and biomass charcoal. Of course, the carbon source can also comprise more than the above-mentioned substances. The graphite powder comprises 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, which can be but is not limited to 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 22 μm, 24 μm or 25 μm. The carbon content of the carbon source is ≥ 80 wt.%, which can be 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.% or ≥ 96.33 wt.%. The volatile matter of the carbon source is 0.1% to 15.0%, which can be 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% or 15.0%. The sulfur content of the carbon source is 1.0% to 3.0%, which can be but is not limited to 1.0%, 1.5%, 2.0%, 2.5% or 3.0%.

[0055] The pre-treatment comprises crushing the carbon source to a particle size of 0.01 mm to 5.00 mm and then 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 or 20 μm. The carbon source can be one or a mixture of multiple types. The carbon sources are mixed uniformly so that the particle size, volatile matter, carbon content and impurity content tend to be consistent, facilitating the adjustment of the crushing and grinding parameters to obtain uniform carbon micropowder. The uniform carbon micropowder has consistent characteristics, which is beneficial to the stable adjustment of the additives and the production of carbon microspheres with stable quality. The carbon microspheres with stable quality do not have fluctuations in the strength of the carbon particles, which can prevent the low-strength carbon microspheres from being easily broken and pulverized, thus preventing the subsequent drying, baking and carbonization from being carried out smoothly. The high-strength carbon microspheres cannot be easily dispersed after graphitization, and need to be broken and ground, which can cause rough surface, low tap density and large specific surface area of the product.

[0056] The uniform carbon source is continuously and automatically fed into a pulverizer, and is pulverized to a particle size of 0.01 mm to 5.00 mm, which can be, but is not limited to, 0.01 mm, 0.05 mm, 0.10 mm, 0.5 mm, 1.00 mm, 2.00 mm, 3.00 mm, 4.00 mm, or 5.00 mm. Pulverization that is too fine can result in too-fine carbon powder produced by grinding, and a low qualified product rate, while pulverization that is too coarse can result in too-large carbon powder particles, and low grinding and powder production efficiency. The pulverized carbon source is then ground and formed into carbon powder of a particle size required for a rear-end product. The carbon powder has a relatively smooth surface, and is similar to millet or to sesame or to an olive-like spherical carbon powder. Compared with irregular carbon powder with a rough surface, the carbon powder of this structure has a larger tap density and a smaller specific surface area, and the obtained negative electrode material has a higher volume specific energy.

[0057] Step (two) includes mixing the carbon powder and the dry powder additive, the acidifying agent, and the liquid additive, and pressing to obtain carbon microspheres.

[0058] In the process, the carbon powder is first mixed with the dry powder additive, and then mixed with the liquid additive. The dry powder additive is first mixed, and then the liquid additive is mixed, so that the components are uniformly dispersed in the kneaded state.

[0059] Further, the mass ratio of the carbon micro powder and the dry powder additive is 100:1-8, which can be but is not limited to 100:1, 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, or 100:8. The particle size distribution of the dry powder additive is 0.01 μm to 100.00 μm, which can 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, or 100.00 μm. The mixing of the carbon micro powder and the dry powder additive is performed by a mixer, which includes a screw belt mixer, a single-cone double-screw mixer, a horizontal plough mixer, or a mortar mixer. As an example, the mixer is a single-cone double-screw mixer resistant to an acid with a PH value of 1 or more. The carbon micro powder and the dry powder additive are fed into a dry-wet mixer under a micro-negative pressure condition while being stirred, and the mixing chamber is closed after the feeding is completed to uniformly dry mix the materials, which is conducive to the rapid mixing of the materials. The stirring speed of the dry powder mixer is 30 r / min to 200 r / min, which 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 min to 15 min, which can be but is not limited to 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, 12 min, 13 min, or 15 min.

[0060] The dry powder additive includes at least one of a resin powder, a polysaccharide powder, a glue powder, and an inorganic salt powder. The dry powder additive includes at least two of a phenolic resin glue powder, a modified urea-formaldehyde resin glue powder, an asphalt powder, an alpha starch, a sugar powder, a cellulose powder, a redispersible glue powder, a polyvinyl alcohol glue powder, a latex powder, sodium silicate, calcium chloride, ferric chloride, ferrous chloride, and aluminum phosphate. As an example, the dry powder additive includes a resin powder and a glue powder, and further includes a phenolic resin, an asphalt, a redispersible glue powder, and a polyvinyl alcohol glue powder. The phenolic resin and the asphalt do not undergo glassification and embrittlement when being baked, and the strength of the carbon micro powder particles is improved by heat setting. The polyvinyl alcohol glue powder can make the kneaded carbon microspheres with a certain free-fall anti-breaking strength and viscosity value to ensure the pressing quality and the smooth operation of the pressing process. The redispersible glue powder has water-reducing and adhesive properties, and can appropriately reduce the water consumption, ensure the strength of the kneaded carbon microspheres, and improve the drying efficiency and reduce the drying energy consumption.

[0061] The carbon powder contains, in addition to the main component carbon element, impurities such as Fe2O3, Fe, CaO, SiO2, CaSiO4, etc. with high melting point and high evaporation point, as shown in Table 1. These metal elements and compound impurities with high melting point and high evaporation point not only cause coking in the vertical graphitization furnace, but also pose a safety hazard to the pressure relief spray furnace, and also react with carbon in the carbon powder to cause carbon loss, as shown in the following formula.

[0062] 2Fe2O3+3C=4Fe+3CO2↑

[0063] Table 1: Component content of carbon powder

[0064]

[0065] By adding the acidifying agent, the metal elements and compound impurities with high melting point and high evaporation point can be converted into metal elements and compound impurities with low melting point and low boiling point, such as converting Fe2O3 with a melting point of 1565°C and a boiling point of 3414°C and metal Fe with a boiling point of 2750°C into FeCl3 with a melting point of 306°C and a boiling point of 319°C, and converting CaO into CaCl2. By adding the acidifying agent before mixing with the liquid additive, the metal elements and compound impurities with low melting point and low boiling point generated in the carbon powder can be uniformly dispersed in the liquid additive, so as to be uniformly distributed on the surface of the carbon powder, which is beneficial to subsequent low-temperature impurity removal.

[0066] The amount of the acidifying agent added is controlled to make the acidity value of the carbon powder be 5.5 to 6.9, which can be but is 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, 6.9. The slight acidification with an acidity value of 5.5 to 6.9 is to convert the impurities with high melting point and high evaporation point in the carbon powder into impurities with low melting point and low evaporation point with a very small amount of acid.

[0067] The acidifying agent includes a liquid acidifying agent and / or a solid acidifying agent. The liquid acidifying agent includes at least one of nitric acid, hydrochloric acid, acrylic acid, a tartaric acid solution, a citric acid solution, and a glycolic acid solution. If the acidifying agent is a liquid acidifying agent, the liquid acidifying agent is added after the dry powder additive is mixed, before the liquid additive is mixed, or the liquid acidifying agent is mixed with the liquid additive first and then added together after the dry powder additive is mixed. The liquid acidifying agent is added by spraying, and the spraying speed is 0.5 kg / min to 10.0 kg / min, which can 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, 10.0 kg / min. If the acidifying agent is a solid acidifying agent, the solid acidifying agent includes at least one of a tartaric acid powder, a citric acid powder, and a glycolic acid powder. The solid acidifying agent is mixed with the dry powder additive first and then added together into the carbon micro-powder before the liquid additive is mixed, or the carbon micro-powder is sequentially mixed with the dry powder additive, the solid acidifying agent, and the liquid additive.

[0068] The mass ratio of the carbon micro-powder and the liquid additive is 50-100:6-25, which can be 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, 100:25. The liquid additive includes at least one of a resin glue, an inorganic salt solution, and a solvent. The resin glue includes at least one of a urea-formaldehyde resin glue, an epoxy resin glue, a phenolic resin glue, a liquid asphalt glue, and a latex glue. The inorganic salt solution includes at least one of a water glass, a calcium chloride solution, an iron chloride solution, and a ferrous chloride solution. The solvent includes at least two of water, ethanol, methanol, acetone, xylene, dipropylene glycol dimethyl ether, ethylene glycol monomethyl ether, and propylene glycol methyl ether. The liquid additive includes the inorganic salt solution and water, which not only can improve the strength but also can form a blend with high-melting-point impurities such as SiO2 and CaSiO4 in the carbon micro-powder, thereby reducing the melting point of the impurities and eliminating the safety hazards of pressure accumulation and spouting caused by the high-melting-point impurities in the vertical graphitization furnace.

[0069] The liquid additive is added by spraying, and the spraying speed is 0.5 kg / min to 10.0 kg / min, which can 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, 10.0 kg / min. The nozzle can be installed on the mixer, and 1 to 8 nozzles can be installed on the mixer. The spraying addition is conducive to uniform mixing of the components. The mixing speed of the mixer after adding the liquid additive is 60 r / min to 300 r / min, which can be but is 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, 300 r / min. The mixing time is 3 min to 8 min, which can be but is not limited to 3 min, 4 min, 5 min, 6 min, 7 min, 8 min.

[0070] The pressing includes first buffering the mixed material and then pressing the ball in the ball press 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, or 35 mm. The particle size of the carbon microspheres should not be single, which is not conducive to the adjustment of the furnace resistance of the vertical continuous graphitization process. At the same time, the particle size distribution should not be too large, which can easily cause the deviation of the downward movement speed of the particles in the vertical graphitization furnace to be too large, resulting in unstable product graphitization degree index. Therefore, as an example, the carbon microspheres can include a combination of carbon microspheres with multiple particle sizes, such as first carbon microspheres with a particle size of 5 mm to 10 mm, second carbon microspheres with a particle size of 10 mm to 20 mm, third carbon microspheres with a particle size of 20 mm to 30 mm, and fourth carbon microspheres with a particle size of 30 mm to 35 mm. The proportion of the first, second, third, and fourth carbon microspheres is 10-60:30-80:20-60:0-30. The mixed material is buffered and buffered, and the buffering pressure is controlled at -0.001 kPa to -30.0 kPa, which can be, 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, or -30.0 kPa. The buffering time is 10 min to 30 min, and the buffering time should not be too long, otherwise it will cause liquid evaporation, material drying, and affect the ball quality. Negative pressure is used during buffering, so that the gas in the pores or grooves of the carbon micro-powder is discharged, the pores or grooves are infiltrated and fully contacted with the additives, the coating and bonding quality are improved. In addition, the micro-negative pressure buffering material is beneficial to improve the bulk density of the material, the density of the ball, and the bonding strength between the micro-powder. In addition, most of the gas between the carbon micro-powder is removed, which is beneficial to improve the density and initial strength of the carbon micro-powder. The buffered material is sent into the ball press for ball pressing, and the ball pressing pressure is 4.5 MPa to 9.5 MPa, which is a continuous pressing method without pressure holding. The pressure can be, but is not limited to, 4.5 MPa, 5.0 MPa, 5.5 MPa, 6.0 MPa, 6.5 MPa, 7.0 MPa, 7.5 MPa, 8.0 MPa, 8.5 MPa, or 9.5 MPa. The ball pressing pressure should not be too small, otherwise it is difficult to form a compact carbon microsphere, and similarly, the pressure should not be too large, otherwise it is difficult to disperse the particles obtained by subsequent graphitization, which brings adverse effects on the product appearance and tap density. The free-fall breaking strength value of the pressed carbon microspheres is 400 mm to 1000 mm, which can be, but is not limited to, 400 mm, 500 mm, 600 mm, 700 mm, or 1000 mm. The determination method of the free-fall breaking strength value is as follows.

[0071] (1) Place the test device, which is composed of a base, a support rod, and a particle placement rack. The base is made of a 10mm thick x 100mm x 100mm steel plate. The support rod is made of a 8mm diameter x 1500mm long steel pipe. The steel pipe is connected to the steel plate vertically through threads, and the steel pipe is marked with a scale from 0mm to 1800mm from the upper surface of the steel plate. The particle placement rack is provided with a particle placement ring, and the bottom of the particle placement ring is provided with a horizontally movable support piece. The particle placement ring can move up and down on the support rod and be fixed to the support rod by screws.

[0072] (2) Place the particles, fix the particle placement ring to the selected height, and tighten. Place the support piece directly below the particle placement ring, and then place the complete particles into the particle placement ring and on the support piece;

[0073] (3) Free fall operation, move the support piece to the left or right, and the particles on the support piece fall freely and hit the upper surface of the base.

[0074] (4) View the state of the free-falling particles to evaluate the free-falling particle breakage resistance value. When testing at each lower limit height, the free-falling particles are complete and not broken, and when testing at each high limit height +1mm, the free-falling particles are not complete and have broken, which is considered to be qualified. For example, the free-falling breakage resistance value of carbon microspheres at 400mm is that the compressed carbon spheres are allowed to fall freely at 400mm, and then observed for breakage. If not broken, it indicates that the breakage resistance value is at least 400mm, and if broken, it indicates that the breakage resistance value of the carbon microspheres is lower than the minimum value of 400mm, which is considered unqualified.

[0075] The detection method is simple and fast, and can fully meet the needs of continuous graphitization process particle quality monitoring and control.

[0076] The step (three) comprises drying and baking the carbon microspheres to obtain the carbon micro-powder particles. The carbon microspheres are dried at 30-105°C and then baked at a gradient temperature of 95-105°C to 280-300°C to obtain the carbon micro-powder particles with a water content of 0.01 wt.% or less. The baking can be performed by one-time heating to the gradient temperature of 95-105°C to 280-300°C, or by stepwise heating to the gradient temperature of 95-105°C to 280-300°C. The gradient baking temperature can be, but is not limited to, 95-280°C, 95-300°C, 100-280°C, 105-280°C, 105-290°C, 105-300°C. The gradient baking can make the thermosetting component and the hot-melt component in the carbon microspheres melt and solidify, which is beneficial to the formation of stable structure of the particles, maintains good micro-powder morphology and mechanical strength of the particles, and improves the stability, safety and product quality of subsequent graphitization. The free-fall breaking strength value of the carbon micro-powder particles provided by the present application is 500-1300 mm, which can be, but is not limited to, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, 1100 mm, 1200 mm, 1300 mm. The carbon micro-powder particles provided by the present application have a certain strength as described above, which can prevent the carbon micro-powder from being washed away during subsequent vertical continuous graphitization, and can avoid the enrichment and caking of high-melting-point and high-volatile-point impurities in the graphitization furnace.

[0077] The step (four) comprises carbonizing and graphitizing the carbon micro-powder particles to obtain carbon micro-powder graphitized particles. The carbonization and graphitization can be performed by an integrated continuous process. The volatile gas generated during the carbonization process and the gasification overflow during the graphitization purification can realize a micro-positive pressure oxygen isolation system at the top of the furnace, without the need to introduce a large amount of inert gas for oxygen isolation protection, which can reduce the equipment investment and operating cost, especially avoiding the introduction of a large amount of N2, and eliminating the investment and operating cost of denitration. The carbonization treatment temperature is 500-2200°C, which can be, but is not limited to, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, 2100°C, 2200°C. The carbonization treatment time is 2-20 h, which can be, but is not limited to, 2 h, 4 h, 10 h, 14 h, 15 h, 16 h, 18 h, 20 h.

[0078] The graphitization temperature is 2200-3300°C, which can be but is not limited to 2200°C, 2300°C, 2400°C, 2500°C, 2600°C, 2700°C, 2800°C, 2900°C, 3000°C, 3100°C, 3200°C, 3300°C. The continuous graphitization time is 6-36h, which can be but is not limited to 6h, 10h, 13h, 16h, 20h, 24h, 28h, 32h, 36h.

[0079] To better illustrate the purpose, technical solutions and beneficial effects of the present application, the present application will be further described below in conjunction with specific examples. It should be noted that the following implementation of the method is a further explanation of the present application and should not be regarded as a limitation of the present application.

[0080] Example 1

[0081] The present embodiment is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0082] (I) Petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1% is continuously and automatically fed into a crusher after mixing to be crushed into carbon source particles with a maximum particle size of 5mm. The carbon source particles are directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a median particle size of 15μm and a round surface.

[0083] (II) Carbon micro-powder, pitch powder (particle size of 10.00μm), re-dispersible rubber powder (particle size of 80.00μm), polyvinyl alcohol 1788 rubber powder (particle size of 100.00μm) and polyvinyl alcohol 2488 rubber powder (particle size of 100.00μm) are mixed in a screw mixer at a mass ratio of 100:3:0.3:0.2:1.3. 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 value of the mixture is 6.1. Then 20wt.% calcium chloride aqueous solution is added while stirring at a speed of 5.5kg / min (the mass ratio of carbon micro-powder and 20wt.% calcium chloride aqueous solution is 95:25). The mixture is mixed at a speed of 200r / min for 5min and then fed into a buffer bin for matting and buffering. The pressure in the buffer bin is -30.0Pa and the buffering time is 15min. The matted material is fed into a ball press machine to be pressed into carbon micro-spheres with a particle size of 25mm at a pressure of 9.0MPa. The free-fall breakage resistance of the carbon micro-spheres is tested, and the free-fall breakage resistance value is 543mm.

[0084] (III) The carbon micro-spheres are first dried at 55°C for 1h, then baked at 120°C for 1h and heated to 250°C for baking until the water content is 0.01wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles is tested, and the free-fall breakage resistance value is 1200mm.

[0085] (iv) carbon micro-powder particles were carbonized at 1500°C for 2h and then graphitized at 3000°C for 6h to obtain carbon micro-powder graphitized particles. The carbon micro-powder graphitized particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 865mm, the impurity content was 0.001wt%, there was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 95.1%.

[0086] Example 2

[0087] This embodiment is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0088] (i) petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1% was mixed and then continuously and automatically fed into a pulverizer to be pulverized into carbon source particles with a maximum particle size of 5mm. The carbon source particles were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a median particle size of 15μm and a round surface.

[0089] (ii) carbon micro-powder, pitch powder (particle size of 10.00μm), phenolic resin powder (particle size of 20.00μm), polyvinyl alcohol 1788 glue powder (particle size of 100.00μm), and polyvinyl alcohol 2488 glue powder (particle size of 100.00μm) were mixed in a screw mixer at a mass ratio of 100:1.8:0.3:0.3:1.2. The stirring speed of the mixture was 100r / min, the stirring time was 10min, hydrochloric acid was sprayed at a speed of 5.0kg / min until the acidity value of the mixture was 6.1, 20wt.% calcium chloride aqueous solution was added by spraying at a speed of 5.5kg / min while stirring (the mass ratio of carbon micro-powder and calcium chloride aqueous solution was 85:25), and the mixture was uniformly mixed at a speed of 200r / min for 5min. The material was then fed into a buffer bin for steaming and buffering. The pressure in the buffer bin was -30.0Pa, and the buffering time was 15min. The steamed material was fed into a ball press machine at 9.0MPa to obtain carbon microspheres with a particle size of 25mm. The carbon microspheres were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 450mm.

[0090] (iii) the carbon microspheres were first dried at 55°C for 1h, then baked at 120°C for 1h, and then heated to 250°C for baking until the water content was 0.01wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 901mm.

[0091] (Three) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 1075 mm.

[0092] Example 3

[0093] This embodiment is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0094] (One) Petroleum green oil coke with 6.1% volatile matter and 1.0% sulfur content was mixed and then continuously and automatically fed into a crusher to be crushed into carbon source particles with a maximum particle size of 5 mm. The carbon source particles were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0095] (Two) Carbon micro-powder: phenolic resin (particle size 20.00 μm): alpha corn starch were mixed in a spiral ribbon mixer at a mass ratio of 100:4:3, the stirring speed of mixing was 100 r / min, the stirring time was 10 min, hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1, 20 wt.% calcium chloride aqueous solution was sprayed at a speed of 5.5 kg / min while stirring, the mixture was mixed at a speed of 200 r / min for 5 min, and then the material was fed into a buffer bin for steaming and buffering. The pressure in the buffer bin was -30.0 Pa, the buffering time was 15 min, the steamed and buffered material was fed into a ball press at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm, which were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 595 mm.

[0096] (Three) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 1075 mm.

[0097] (Four) The carbon micro-powder particles were carbonized at 1500°C for 2 h and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles, which were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 805 mm, the impurity content was 0.001 wt.%, there was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 92.5%.

[0098] Example 4

[0099] This embodiment is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0100] (I) The needle coke with volatile matter of 0.2% and sulfur content of 2.1% and flake graphite were mixed in a weight ratio of 7:3 and 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a smooth surface and a median particle size of 15 μm.

[0101] (II) The carbon micro-powder, phenolic resin (particle size of 20.00 μm), α-tapioca powder (particle size of 90.00 μm), and polyvinyl alcohol (particle size of 90.00 μm) were mixed in a mass ratio of 100:3:2:1 in a ribbon mixer at a stirring speed of 100 r / min for 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1. Then, 20 wt.% calcium chloride aqueous solution was added by spraying while stirring at a speed of 5.5 kg / min (the mass ratio of the carbon micro-powder and the 20% calcium chloride aqueous solution was 95:25). The mixture was mixed at a speed of 200 r / min for 5 min, and then the mixture was fed into a buffer bin for steaming and buffering. The pressure in the buffer bin was -30.0 Pa, and the buffering time was 15 min. The steamed and buffered mixture was fed into a ball press to be pressed into carbon micro-spheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon micro-spheres was tested, and the free-fall breakage resistance value was 889 mm.

[0102] (III) The carbon micro-spheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.%. The carbon micro-powder particles were obtained. The free-fall breakage resistance of the carbon micro-powder particles was tested, and the free-fall breakage resistance value was 1285 mm.

[0103] (IV) The carbon micro-powder particles were carbonized at 1500°C for 2 h, and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested, and the free-fall breakage resistance value was 864 mm. The impurity content was 0.001 wt.%. There was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 93.0%.

[0104] Example 5

[0105] The present embodiment is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0106] (I) The needle coke with volatile matter of 0.2% and sulfur content of 2.1% and flake graphite were mixed in a weight ratio of 7:3 and 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a smooth surface and a median particle size of 15 μm.

[0107] (ii) The carbon micro-powder, phenol formaldehyde resin (particle size 20.00 μm) and polyvinyl alcohol 2488 (particle size 90.00 μm) were mixed in a ribbon blender at a mass ratio of 100:4:1. The mixing speed was 100 r / min and the mixing time was 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 5.6. Then 20 wt.% calcium chloride aqueous solution was sprayed at a speed of 5.5 kg / min while stirring. The mass ratio of the carbon micro-powder and the 20 wt.% calcium chloride aqueous solution was 95:25. The mixture was mixed at a speed of 200 r / min for 5 min and then was sent to a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa and the buffering time was 15 min. The tempered material was sent to a ball press machine to be pressed into carbon micro-spheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon micro-spheres was tested and the value was 455 mm.

[0108] (iii) The carbon micro-spheres were first dried at 55 °C for 1 h, then were baked at 120 °C for 1 h and were baked at 250 °C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles was tested and the value was 1130 mm.

[0109] (iv) The carbon micro-powder particles were carbonized at 1500 °C for 2 h and then were graphitized at 3000 °C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested and the value was 875 mm. The impurity content was 0.001 wt.% and there was no coking in the graphitization furnace. The graphitization degree value was 93.5%.

[0110] Example 6

[0111] This example is a process for preparing carbon micro-powder particles, which comprises the following steps.

[0112] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was continuously and automatically sent to a pulverizer after mixing to be pulverized into carbon source particles with a maximum particle size of 5 mm. The carbon source particles were directly and continuously sent to a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0113] (ii) Carbon microspheres were prepared by mixing carbon micro powder, pitch powder (particle size 10.00 μm), redispersible rubber powder (particle size 80.00 μm) and polyvinyl alcohol 2488 rubber powder (particle size 100.00 μm) in a mass ratio of 100:3:0.3:1.0 in a ribbon mixer at a stirring speed of 100 r / min for 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1. Then, 20 wt.% calcium chloride aqueous solution was sprayed at a speed of 5.5 kg / min while stirring. The mixture was mixed at a speed of 200 r / min for 5 min, and then was sent to a buffer bin for curing and buffering. The pressure in the buffer bin was -30.0 Pa, and the curing time was 15 min. The cured material was sent to a ball press machine to form carbon microspheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon microspheres was tested, and the value was 475 mm.

[0114] (iii) The carbon microspheres were dried at 55°C for 1 h, and then were baked at 120°C for 1 h and heated to 250°C for baking until the water content was 0.01 wt.% to obtain carbon micro powder particles. The free-fall breakage resistance of the carbon micro powder particles was tested, and the value was 1045 mm.

[0115] (iv) The carbon micro powder particles were carbonized at 1500°C for 2 h, and then were graphitized at 3000°C for 6 h to obtain carbon micro powder graphitized particles. The free-fall breakage resistance of the carbon micro powder graphitized particles was tested, and the value was 770 mm. The impurity content was 0.001 wt.%, and there was no coking in the graphitization furnace. The graphitization degree value was 95.3%.

[0116] Example 7

[0117] This example is a process for preparing carbon micro powder particles, which comprises the following steps.

[0118] (i) Petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was continuously and automatically sent to a pulverizer after mixing to obtain carbon source particles with a maximum particle size of 5 mm. The carbon source particles were directly and continuously sent to a grinding granulator to obtain carbon micro powder with a round surface and a median particle size of 15 μm.

[0119] (ii) The carbon micro-powder, pitch powder (particle size 10.00 μm), redispersible rubber powder (particle size 80.00 μm), and polyvinyl alcohol 1788 rubber powder (particle size 100.00 μm) were mixed in a ribbon blender at a mass ratio of 100:3:0.3:1.0. The mixing speed was 100 r / min, and the mixing time was 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1. Then, 20 wt.% calcium chloride aqueous solution was sprayed at a speed of 5.5 kg / min while stirring. The mixture was mixed at a speed of 200 r / min for 5 min, and then the material was sent to a buffer bin for curing and buffering. The pressure in the buffer bin was -30.0 Pa, and the buffering time was 15 min. The cured material was sent to a ball press machine to be pressed into carbon microspheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon microspheres was tested, and the value was 471 mm.

[0120] (iii) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and finally baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles was tested, and the value was 1039 mm.

[0121] (iv) The carbon micro-powder particles were carbonized at 1500°C for 2 h and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested, and the value was 765 mm. The impurity content was 0.001 wt.%, there was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 95.3%.

[0122] Example 8

[0123] This example is a preparation process of carbon micro-powder particles, which includes the following steps.

[0124] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0125] (ii) The carbon micro-powder, phenol formaldehyde resin (particle size 30.00 μm), pitch powder (particle size 20.00 μm), re-dispersible rubber powder (particle size 95.00 μm), and polyvinyl alcohol rubber powder 2488 rubber powder (particle size 85.00 μm) are mixed in a ribbon blender 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 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 micro-powder to calcium chloride aqueous solution is 95:25) is added while stirring at a speed of 5.5 kg / min. The mixture is mixed at a speed of 200 r / min for 5 min, and then the material is sent to a buffer bin for tempering and buffering. The pressure in the buffer bin is -30.0 Pa, and the buffering time is 15 min. The tempered material is sent to a ball press machine to be pressed into carbon micro-spheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon micro-spheres is tested, and the value is 510 mm.

[0126] (iii) The carbon micro-spheres are first dried at 55 °C for 1 h, then baked at 120 °C for 1 h, and then baked at 250 °C until the water content is 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles is tested, and the value is 875 mm.

[0127] (iv) The carbon micro-powder particles are carbonized at 1500 °C for 2 h, and then graphitized at 3000 °C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles is tested, and the value is 630 mm. The impurity content is 0.001 wt.%, there is no coking phenomenon in the graphitization furnace, and the graphitization degree value is 94.7%.

[0128] Example 9

[0129] This example is a process for preparing carbon micro-powder particles, which includes the following steps.

[0130] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% is continuously and automatically fed into a pulverizer after batching to obtain carbon source particles with a maximum particle size of 5 mm. The carbon source particles are directly and continuously fed into a grinding granulator to obtain carbon micro-powder with a round surface and a median particle size of 15 μm.

[0131] (ii) The carbon micro-powder: modified urea-formaldehyde resin (particle size 45.00 μm): corn starch (particle size 10.00 μm) were mixed in a ribbon blender at a mass ratio of 100:4:4, the stirring speed was 100 r / min, the stirring time was 10 min, 5.0 kg / min of hydrochloric acid was sprayed to the mixture until the acidity value was 6.1, then 5.5 kg / min of 20 wt.% calcium chloride aqueous solution (mass ratio of carbon micro-powder and 20 wt.% calcium chloride aqueous solution was 95:25) was sprayed while stirring, the mixture was stirred at 200 r / min for 5 min, then the material was sent to a buffer bin for steaming and buffering, the pressure in the buffer bin was -30.0 Pa, the buffering time was 15 min, the steamed material was sent to a ball press at 9.0 MPa to obtain carbon micro-spheres with a particle size of 25 mm, the free-fall breakage resistance value of the carbon micro-spheres was 800 mm.

[0132] (iii) The carbon micro-spheres were first dried at 55 °C for 1 h, then baked at 120 °C for 1 h, and then baked at 250 °C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were subjected to free-fall breakage resistance test, and the free-fall breakage resistance value was 1160 mm.

[0133] (iv) The carbon micro-powder particles were carbonized at 1500 °C for 2 h, and then graphitized at 3000 °C for 6 h to obtain carbon micro-powder graphitized particles. The carbon micro-powder graphitized particles were subjected to free-fall breakage resistance test, and the free-fall breakage resistance value was 837 mm, the impurity content was 0.002 wt.%, there was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 92.0%.

[0134] Example 10

[0135] The present embodiment is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0136] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0137] (ii) The carbon micro-powder: phenolic resin (particle size 20.00 μm): corn starch (particle size 10.00 μm) were mixed in a ribbon blender at a mass ratio of 100:4:4, the stirring speed was 100 r / min, and the stirring time was 10 min. The citric acid solution (mass ratio of carbon micro-powder: 5% citric acid solution was 100:1, and the amount of citric acid solution was enough to make the acidity of the mixture 5.6) and 20 wt.% calcium chloride aqueous solution (mass ratio of carbon micro-powder and 20 wt.% calcium chloride aqueous solution was 95:23) were mixed first, and then sprayed into the ribbon blender at a speed of 5.5 kg / min. The mixture was mixed at a speed of 200 r / min for 5 min, and then sent to a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa, the buffering time was 15 min, and the tempered material was sent to a ball press machine to be pressed into carbon micro-spheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon micro-spheres was tested, and the value was 801 mm.

[0138] (iii) The carbon micro-spheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles was tested, and the value was 1163 mm.

[0139] (iv) The carbon micro-powder particles were carbonized at 1500°C for 2 h, and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested, and the value was 839 mm. The impurity content was 0.002 wt.%, there was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 92.1%.

[0140] Example 11

[0141] This example is a process for preparing carbon micro-powder particles, which includes the following steps.

[0142] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0143] (ii) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and finally baked at 250°C until the water content was 0.01 wt.%. The carbon micro-powder particles were obtained. The free-fall breakage resistance of the carbon micro-powder particles was tested, and the value of the free-fall breakage resistance was 1297 mm.

[0144] (iii) The carbon micro-powder particles were carbonized at 1500°C for 2 h, and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested, and the value of the free-fall breakage resistance was 945 mm. The impurity content was 0.002 wt.%. No coking occurred in the graphitization furnace. The graphitized particles did not need to be crushed and ground. The graphitization degree value was 95.0%.

[0145] (iv) The carbon micro-powder graphitized particles were obtained by the process of the present embodiment. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested, and the value of the free-fall breakage resistance was 945 mm. The impurity content was 0.002 wt.%. No coking occurred in the graphitization furnace. The graphitized particles did not need to be crushed and ground. The graphitization degree value was 95.0%.

[0146] Example 12

[0147] The present embodiment is a process for preparing carbon micro-powder particles, which includes the following steps.

[0148] (i) Petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was continuously and automatically fed into a crusher after batching to obtain carbon source particles with a maximum particle size of 5 mm. The carbon source particles were directly and continuously fed into a grinding granulator to obtain carbon micro-powder with a round surface and a median particle size of 15 μm.

[0149] (ii) The carbon micro-powder, phenol formaldehyde resin (particle size 20 μm), and polyvinyl alcohol 2488 (particle size 90 μm) were mixed in a ribbon blender at a mass ratio of 100:3:1. The mixing speed was 100 r / min, and the mixing time was 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity of the mixture was 6.1. Then, 15 wt.% calcium chloride solution was sprayed at a speed of 5.5 kg / min while stirring. The mixture was mixed at a speed of 200 r / min for 5 min, and then the material was sent to a buffer bin for curing and buffering. The pressure in the buffer bin was -30.0 Pa, and the buffering time was 15 min. The cured material was sent to a ball press machine to be pressed into carbon microspheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon microspheres was tested, and the value was 453 mm.

[0150] (iii) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles was tested, and the value was 997 mm.

[0151] (iv) The carbon micro-powder particles were carbonized at 1500°C for 2 h, and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested, and the value was 719 mm. The impurity content was 0.001 wt.%, and no coking occurred in the graphitization furnace. The graphitization degree value was 94.0%.

[0152] Example 13

[0153] This example is a process for preparing carbon micro-powder particles, which includes the following steps.

[0154] (i) Petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0155] (ii) The carbon micro-powder, phenol formaldehyde resin (particle size 30.00 μm), pitch (particle size 20.00 μm), redispersible rubber powder (particle size 15.00 μm) and vinyl alcohol rubber powder (particle size 15.00 μm) were mixed in a ribbon blender at a mass ratio of 100:1:1:1:1. The mixing speed was 100 r / min and the mixing time was 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1. Then 15 wt.% calcium chloride solution was added while stirring at a speed of 5.5 kg / min (mass ratio of carbon micro-powder and 15 wt.% calcium chloride solution 95:20). The mixture was mixed at a speed of 200 r / min for 5 min and then sent to a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa and the buffering time was 15 min. The tempered material was sent to a ball press to form carbon micro-spheres with a particle size of 25 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon micro-spheres was 597 mm.

[0156] (iii) The carbon micro-spheres were first dried at 55 °C for 1 h, then baked at 120 °C for 1 h and heated to 250 °C for baking until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance of the carbon micro-powder particles was 993 mm.

[0157] (iv) The carbon micro-powder particles were carbonized at 1500 °C for 2 h and then graphitized at 3000 °C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was 708 mm, the impurity content was 0.001 wt.% and no coking occurred in the graphitization furnace. The graphitization degree was 94.5%.

[0158] Example 14

[0159] This example is a process for preparing carbon micro-powder particles, which comprises the following steps.

[0160] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was continuously and automatically fed into a pulverizer after batching to obtain carbon source particles with a maximum particle size of 4.5 mm. The carbon source particles were directly and continuously fed into a grinding granulator to obtain carbon micro-powder with a round surface and a median particle size of 10 μm.

[0161] (ii) Carbon micro-powder and phenolic resin (particle size 20.00 μm) + polyvinyl alcohol glue powder (particle size 75.00 μm) + calcium chloride powder (particle size 80.00 μm) were mixed in a ribbon mixer at a mass ratio of 100:1:0.5:3.5. The stirring speed was 100 r / min and the stirring time was 10 min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1. Then 25% solid content liquid asphalt glue (mass ratio of carbon micro-powder and liquid asphalt glue 80:18) was added while stirring at a speed of 5.5 kg / min. The mixture was mixed at a speed of 200 r / min for 5 min and then sent to a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa and the buffering time was 10 min. The tempered material was sent to a ball press machine to be pressed into carbon microspheres with a particle size of 20 mm at a pressure of 9.0 MPa. The free-fall breakage resistance of the carbon microspheres was tested and the value was 829 mm.

[0162] (iii) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h and heated to 250°C for baking until the water content was 0.01 wt.%. The carbon micro-powder particles were obtained. The free-fall breakage resistance of the carbon micro-powder particles was tested and the value was 1219 mm.

[0163] (iv) The carbon micro-powder particles were carbonized at 1500°C for 2 h and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance of the carbon micro-powder graphitized particles was tested and the value was 903 mm. The impurity content was 0.002 wt.%. There was no coking phenomenon in the graphitization furnace and the graphitization degree value was 95.5%.

[0164] Example 15

[0165] This example is a process for preparing carbon micro-powder particles, which comprises the following steps.

[0166] (i) Petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0167] (ii) The carbon micro-powder, phenol formaldehyde resin (particle size 20.00 μm) and calcium chloride powder were mixed in a single-cone double-screw mixer at a mass ratio of 100:4:2, the stirring speed was 120 r / min, the stirring time was 15 min, hydrochloric acid was sprayed at a speed of 8.0 kg / min until the acidity of the mixture was 6.1, then liquid asphalt glue with a solid content of 10% was sprayed at a speed of 7.5 kg / min while stirring, the mixture was mixed at a speed of 230 r / min for 8 min, and then the material was sent to a buffer bin for tempering and buffering, the pressure in the buffer bin was -20.0 Pa, the buffering time was 15 min, the tempered material was sent to a ball press machine at 9.0 MPa to obtain carbon microspheres with a particle size of 5 mm to 10 mm accounting for 15%, a particle size of 10 mm to 20 mm accounting for 30%, and a particle size of 20 mm to 30 mm accounting for 55%, and the free-fall breakage resistance value of the carbon microspheres was 407 mm.

[0168] (iii) The carbon microspheres were first dried at 80°C for 1 h, then baked at 120°C for 2 h, and then baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were subjected to free-fall breakage resistance testing, and the free-fall breakage resistance value was 1189 mm.

[0169] (iv) The carbon micro-powder particles were carbonized at 1700°C for 1.5 h and then graphitized at 3100°C for 5 h to obtain carbon micro-powder graphitized particles. The carbon micro-powder graphitized particles were subjected to free-fall breakage resistance testing, and the free-fall breakage resistance value was 891 mm, the impurity content was 0.001 wt.%, there was no coking phenomenon in the graphitization furnace, and the graphitization degree value was 94.0%.

[0170] Comparative Example 1

[0171] This comparative example is a preparation process of carbon micro-powder particles, which includes the following steps.

[0172] (i) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0173] (ii) The carbon micro-powder was mixed in a ribbon blender, and then 38% solid content organic solvent liquid pitch glue (mass ratio of carbon micro-powder and organic solvent liquid pitch glue was 80:20) was sprayed and mixed 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 bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa, the buffering time was 15 min, and the tempered material was sent to a ball press to be pressed at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free-fall breakage resistance value of the carbon microspheres was 1093 mm.

[0174] (iii) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.%. The obtained carbon micro-powder particles were subjected to free-fall breakage resistance test, and the free-fall breakage resistance value was 1752 mm.

[0175] (iv) The carbon micro-powder particles were carbonized at 1500°C for 2 h, and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The carbon micro-powder graphitized particles were subjected to free-fall breakage resistance test, and the free-fall breakage resistance value was 1473 mm. The impurity content was 0.049 wt.%, and the graphitization degree value was 95.0%. The enrichment and coking of high-melting-point impurities occurred in the graphitization heat treatment furnace.

[0176] Comparative Example 2

[0177] This comparative example is a preparation process of carbon micro-powder particles, which includes the following steps.

[0178] (i) Petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then 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 were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0179] (ii) The carbon micro-powder and phenolic resin glue (solid content was 35%) were mixed in a ribbon blender at a mass ratio of 80:20. After mixing at a speed of 200 r / min for 5 min, the material was sent to a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa, the buffering time was 15 min, and the tempered material was sent to a ball press to be pressed at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free-fall breakage resistance value of the carbon microspheres was 1012 mm.

[0180] (Three) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and finally baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The prepared carbon micro-powder particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 1675 mm. The particle strength was extremely high after drying and baking.

[0181] (Four) The carbon micro-powder particles were carbonized at 1500°C for 2 h, and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The prepared carbon micro-powder graphitized particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 1355 mm, the impurity content was 0.045 wt.%, and the graphitization degree value was 91.6%. The enrichment and coking of high-melting-point impurities occurred in the graphitization heat treatment furnace.

[0182] Comparative Example 3

[0183] This comparative example is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0184] (One) The petroleum calcined coke with 0.2% volatile matter and 2.1% sulfur content was mixed and then continuously and automatically fed into a crusher to crush the carbon source particles to a maximum particle size of 5 mm. The carbon source particles were directly and continuously fed into a grinding granulator to grind the carbon micro-powder with a smooth surface and a median particle size of 15 μm.

[0185] (Two) The carbon micro-powder was mixed in a screw belt mixer at a stirring speed of 100 r / min. Hydrochloric acid was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1. Then, 30% solid content emulsified liquid asphalt glue was added at a speed of 5.5 kg / min while stirring. The mixture was mixed at a speed of 200 r / min for 5 min, and then the material was fed into a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa, and the buffering time was 15 min. The tempered material was fed into a ball press at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The carbon microspheres were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 857 mm.

[0186] (Three) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and finally baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The prepared carbon micro-powder particles were subjected to free-fall anti-crushing strength test, and the free-fall anti-crushing strength value was 1352 mm.

[0187] (Three) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then heated to 250°C for baking until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were tested for free-fall breakage resistance, and the free-fall breakage resistance value was 1593 mm.

[0188] Comparative Example 4

[0189] The present comparative example is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0190] (One) The petroleum calcined coke with a volatile content of 0.2% and a sulfur content of 2.1% was mixed and then continuously and automatically fed into a crusher to be crushed into carbon source particles with a maximum particle size of 5 mm. The carbon source particles were directly and continuously fed into a grinding granulator to be ground into carbon micro-powder with a round surface and a median particle size of 15 μm.

[0191] (Two) The carbon micro-powder, phenolic resin powder (particle size 20.00 μm), and α-tapioca powder were mixed in a ribbon mixer at a mass ratio of 100:1:4, the stirring speed was 100 r / min, and the stirring time was 10 min. 0.01 mol of hydrochloric acid aqueous solution was sprayed at a speed of 5.0 kg / min until the acidity value of the mixture was 6.1 and the water content of the carbon micro-powder was 20%. The mixture was mixed at a speed of 200 r / min for 5 min, and then the material was fed into a buffer bin for steaming and buffering. The pressure in the buffer bin was -30.0 Pa, and the buffering time was 15 min. The steamed and buffered material was fed into a ball press machine at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The carbon microspheres were tested for free-fall breakage resistance, and the free-fall breakage resistance value was 983 mm.

[0192] (Three) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then heated to 250°C for baking until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The carbon micro-powder particles were tested for free-fall breakage resistance, and the free-fall breakage resistance value was 1593 mm.

[0193] (Four) The carbon micro-powder particles were carbonized at 1500°C for 2 h and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The carbon micro-powder graphitized particles were tested for free-fall breakage resistance, and the free-fall breakage resistance value was 1327 mm, the impurity content was 0.001 wt.%, and the graphitization degree value was 91.1%. The enrichment and coking of high-melting-point impurities occurred in the graphitization heat treatment furnace.

[0194] Comparative Example 5

[0195] The present comparative example is a preparation process of carbon micro-powder particles, which comprises the following steps.

[0196] (I) The petroleum calcined coke with volatile matter of 0.2% and sulfur content of 2.1% was continuously and automatically fed into a crusher after mixing to crush the carbon source particles to a maximum particle size of 5 mm. The carbon source particles were directly and continuously fed into a grinding granulator to grind the carbon micro-powder with a smooth surface and a median particle size of 15 μm.

[0197] (II) The carbon micro-powder and phenolic resin (particle size of 20.00 μm) were mixed in a ribbon mixer at a mass ratio of 100:4, the stirring speed was 100 r / min, the stirring time was 10 min, and the 30% solid content emulsified liquid asphalt glue (mass ratio of carbon micro-powder and emulsified liquid asphalt glue was 90:22) was sprayed and stirred at a speed of 5.5 kg / min. After mixing at a speed of 200 r / min for 5 min, the material was fed into a buffer bin for tempering and buffering. The pressure in the buffer bin was -30.0 Pa, the buffering time was 15 min, and the tempered material was fed into a ball press machine at 9.0 MPa to obtain carbon microspheres with a particle size of 25 mm. The free-fall breakage resistance value of the carbon microspheres was 987 mm.

[0198] (III) The carbon microspheres were first dried at 55°C for 1 h, then baked at 120°C for 1 h, and then baked at 250°C until the water content was 0.01 wt.% to obtain carbon micro-powder particles. The free-fall breakage resistance value of the prepared carbon micro-powder particles was 1879 mm.

[0199] (IV) The carbon micro-powder particles were carbonized at 1500°C for 2 h and then graphitized at 3000°C for 6 h to obtain carbon micro-powder graphitized particles. The free-fall breakage resistance value of the prepared carbon micro-powder graphitized particles was 1633 mm, the impurity content was 0.047 wt.%, and the graphitization degree value was 92.9%. The high-melting-point impurities were enriched and coked in the graphitization heat treatment furnace.

[0200] The performance parameters of the carbon micro-powder graphitized particles of Examples 1 to 15 and Comparative Examples 1 to 5 are shown in Table 2.

[0201] Table 2 Performance of carbon micro-powder graphitized particles of Examples 1 to 15 and Comparative Examples 1 to 5

[0202]

[0203] By comparing the embodiments 1 to 15 and the comparative examples 1 to 5 of the present application, it can be seen that the free fall breaking strength of the graphitized particles of the carbon micro-powder prepared by the production process of the present application is 350mm to 950mm, and the total content of the metal elements and metal compound impurities is ≤0.002wt.%. This is because the production process of the present application uses the adhesion of the liquid additive to first make the dry powder additive and the carbon micro-powder into a kneaded state with a certain strength after pressing, and the dry powder additive is uniformly dispersed on the surface of the carbon micro-powder under the action of the liquid additive and the acidifying agent, and then the dry powder additive is further improved in the anti-breaking strength to 500mm to 1300mm after being heated and roasted, and the carbon micro-powder graphitized particles can maintain a suitable free fall breaking strength value. The addition of the acidifying agent can react with the high-melting-point and high-volatility metal elements and metal compound impurities in the carbon micro-powder to convert them into low-melting-point and low-boiling-point compounds, which can be removed by volatilization under low-temperature conditions. The acidifying agent is best hydrochloric acid.

[0204] By comparing the comparative example 1 and the examples 6 to 8, it can be seen that the dry powder additive is a mixture of resin powder and glue powder, and especially when the phenolic resin, pitch, redispersible glue powder and polyvinyl alcohol glue powder are mixed, the performance is better, which may be due to some synergistic effect between the four. By comparing the comparative example 1 and the examples 15, it can be seen that the liquid additive is an inorganic salt solution, and especially when it is used in combination with the dry powder additive (a mixture of resin powder and glue powder), the performance is better.

[0205] By comparing the comparative example 1 and the example 2, it can be seen that the dry powder additive, the redispersible glue powder, has a certain water-reducing effect, which can reduce the amount of water-based liquid additive, improve the density of the pressed ball and the free fall breaking strength of the particles. Compared with the example 1, in the comparative example 1, only liquid pitch glue is used, the initial viscosity is high, the particles will soften during the heating and roasting process due to the heat melting of the pitch, and there is a certain adhesion. Moreover, the strength of the graphitized particles is too high, which needs to be crushed and ground, affecting the yield and performance of the product (which is caused by the excessive amount of pitch added). And there is no hydrochloric acid and calcium chloride in the example 1, the impurity content of the graphitized product is high, and the enrichment and coking phenomenon of high-melting-point impurities occurs in the graphitization heat treatment furnace.

[0206] Compared with the example 1, the comparative example 2 uses only phenolic resin glue, and the strength of the graphitized particles is too high, which needs to be crushed and ground, affecting the yield and performance of the product. And there is no hydrochloric acid and calcium chloride in the example 1, the impurity content of the graphitized product is high, and the enrichment and coking phenomenon of high-melting-point impurities occurs in the graphitization heat treatment furnace.

[0207] Compared with Example 1, the initial viscosity of Comparative Example 3 is high, the particles are softened with the hot melting of the asphalt during the drying and baking process, and there is a certain adhesion, the strength of the graphitized particles is too high, and the product yield and performance are affected (which is caused by the too high amount of added emulsified asphalt). Moreover, there is no calcium chloride in Example 1, and the enrichment and coking of high-melting-point impurities occur in the graphitization heat treatment furnace.

[0208] Compared with Example 1, Comparative Example 4 does not add liquid additive calcium chloride, and the enrichment and coking of high-melting-point impurities occur in the graphitization heat treatment furnace.

[0209] Compared with Example 1, Comparative Example 5 does not add acidifier, and the graphitized product contains a high amount of impurities; and does not add calcium chloride, and the enrichment and coking of high-melting-point impurities occur in the graphitization heat treatment furnace.

[0210] As can be seen from Example 1 and Comparative Examples 1 to 5, the asphalt additive is beneficial to obtain a product with a higher graphitization degree, and the hard carbon additives such as phenolic resin and α cassava powder will cause the graphitization degree of the product to decrease.

[0211] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, it is not limited to the examples listed in the embodiments. Those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present 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 powder graphitized particle prepared by the preparation process of carbon fine powder graphitized particles 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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