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CN-121990828-A - Preparation method of isostatic graphite with superfine structure

CN121990828ACN 121990828 ACN121990828 ACN 121990828ACN-121990828-A

Abstract

The invention provides a preparation method of ultra-fine structure isostatic graphite, belongs to the technical field of isostatic graphite preparation, and aims to solve the technical problems that graphene dispersion efficiency is low and agglomeration is easy to occur in the existing one-step mixing process, so that product reliability is affected. The method comprises the following steps of S1, preparing aggregate, S2, mixing in a gradient mode, namely adding graphene accounting for 1% -3% of the total weight of the basic aggregate into the basic aggregate, mixing the basic aggregate and all the graphene by adopting a gradient mixing method, premixing the basic aggregate accounting for 40% -60% of the total weight to prepare master batch, and finally mixing the master batch and the rest of the basic aggregate to obtain the composite reinforced aggregate, S3, kneading, S4, compacting, S5, isostatic compaction, S6, roasting, S7 and graphitizing. The invention adopts a gradient mixing method, is favorable for fully playing the reinforcing role of the graphene, and effectively solves the problems that the graphene is easy to agglomerate and difficult to uniformly disperse in micron powder by a stepwise dilution mechanism.

Inventors

  • QI QI
  • ZHANG SHIYUE
  • LUO BAOBAO
  • DENG JI

Assignees

  • 四川瑞得鼎欣新材料有限公司

Dates

Publication Date
20260508
Application Date
20260403

Claims (10)

  1. 1. The preparation method of the isostatic pressing graphite with the superfine structure is characterized by comprising the following steps of: step S1, aggregate preparation, namely mixing petroleum coke or pitch coke semicoke superfine powder a with the average particle size of 2-5 mu m with calcined powder or graphite powder b with the average particle size of 2-5 mu m according to the weight ratio of (0.8-1.2) to obtain basic aggregate; step S2, gradient mixing, namely adding graphene accounting for 1% -3% of the total weight of the basic aggregate, and mixing by adopting a gradient mixing method; The gradient mixing method comprises the following steps: S21, premixing 40% -60% of basic aggregate and all graphene to prepare master batch; step S22, finally mixing the master batch with the rest of basic aggregate to obtain composite reinforced aggregate; Step S3, kneading, namely adding coal pitch into the composite reinforced aggregate as a binder, wherein the softening point of the coal pitch is 110-190 ℃, and kneading at a certain temperature to obtain paste; Step S4, pressing powder, namely cooling and crushing the paste, and grinding the paste to obtain paste powder with the average particle size of 15-45 mu m; Step S5, isostatic compaction, namely filling the paste powder into a rubber mold, and maintaining the pressure for 5-15 minutes under the isostatic pressure of 120-160MPa to obtain a green body; step S6, roasting, namely carbonizing the green body in an oxygen-isolated environment; and S7, graphitizing, namely placing the carbonized product into a graphitizing furnace for graphitizing treatment.
  2. 2. The method for preparing ultra-fine structure isostatic graphite according to claim 1, wherein in the step S3, nano nickel catalyst accounting for 0.1% -1% of the weight of the coal pitch is pre-dispersed in the coal pitch, and the coal pitch is kneaded in a kneader for 0.5-1.5 hours at a temperature of 180-260 ℃ to obtain the catalytic paste.
  3. 3. The method for producing ultra-fine structure isostatic graphite as claimed in claim 1, wherein in step S4, the grinding and sphericizing treatment is performed by air flow vortex grinding to obtain near-spherical paste powder with tap density increased by 15% or more than that of the paste before crushing.
  4. 4. The method for preparing the ultra-fine structure isostatic graphite according to claim 1, wherein the roasting process of the step S6 is a segmented catalytic roasting, and specifically comprises the steps of firstly heating to 500-600 ℃ at a rate of 2-5 ℃ per minute and keeping the temperature for 30-60 minutes, and then heating to 900-1100 ℃ at a rate of 1-3 ℃ per minute to finish final carbonization.
  5. 5. The method for preparing ultra-fine structure isostatic graphite according to claim 1, wherein in the step S7, after the carbonized product is placed in a graphitizing furnace, the graphitizing treatment is performed by heating to 2600-3000 ℃ at a rate of 8-20 ℃ per min under the protection of inert gas, when the temperature reaches above 1800 ℃, halogen-containing gas is pulse-fed into the furnace, the pulse frequency is 2-5 times per minute, until the temperature reaches 2500 ℃.
  6. 6. The method for preparing the ultra-fine structure isostatic graphite according to claim 1, wherein the step S1 and the step S2 are completed by an integrated mixing device, and the using method of the integrated mixing device comprises the following steps: Step a, feeding, namely loading powder a into a first raw material cavity, loading ultrafine powder b into a second raw material cavity, and loading graphene into a storage bin of a feeding mechanism; Step b, preparing basic aggregate, namely controlling powder a and powder b to be fed into a mixing cavity alternately or simultaneously, and starting a first stirring mechanism to mix so as to prepare the basic aggregate; C, preparing master batch, namely transferring 40% -60% of basic aggregate to a second mixing bin, simultaneously putting all graphene into the second mixing bin by a feeding mechanism, and starting a second stirring mechanism to prepare the master batch; And d, final mixing, namely putting the rest basic aggregate into a second mixing bin, and finally mixing with the master batch to output the composite reinforced aggregate.
  7. 7. The method for preparing ultra-fine structural isostatic graphite according to claim 6, wherein in the step c, 40% -60% of the basic aggregate is transferred to the second mixing bin by a continuous mode or a batch processing mode: the continuous mode is that a discharging hole of a mixing cavity and a discharging hole of a material guiding bin are kept open, the material guiding bin synchronously receives aggregate from the mixing cavity and discharges the aggregate to a second material mixing bin in the rotating process, and when the discharging amount of the mixing cavity reaches 40% -60% of the initial capacity of the mixing cavity, the discharging hole of the mixing cavity is closed; The batch treatment mode is that a discharging hole of a mixing cavity is firstly opened, a discharging hole of a material guiding bin is closed, after the material guiding bin collects aggregate to 40% -60% of the total amount of the aggregate, the discharging hole is closed, the discharging hole is opened, and the aggregate is discharged into a second material mixing bin through rotation of the material guiding bin.
  8. 8. The method for preparing ultra-fine structured isostatic graphite according to claim 1, wherein the steps S1 and S2 are completed by an integrated mixing device comprising: The raw material bin comprises a first raw material cavity for storing superfine powder a and a second raw material cavity for storing superfine powder b; The first material mixing bin is arranged below the material mixing bin, and the interior of the material mixing bin is divided into a central cavity and a plurality of mixing cavities surrounding the central cavity through a circular partition plate and a plurality of radial partition plates; The first stirring mechanism is arranged in the first mixing bin; the material guiding bin is rotatably arranged between the first material mixing bin and the supporting table, a transverse plate is arranged in the material guiding bin, and a round hole which can be overlapped with a discharge hole of the first material mixing bin is formed in the transverse plate; the second mixing bin is arranged below the guide bin, and a feed inlet of the second mixing bin is communicated with the guide bin; The second stirring mechanism is arranged in the second mixing bin; and the material adding mechanism is communicated with the second mixing bin and is used for adding graphene into the second mixing bin.
  9. 9. The method for preparing the ultra-fine structure isostatic pressing graphite according to claim 8, wherein the method comprises the following steps: a material sensing device for sensing the material quantity is arranged in the mixing cavity or the material guiding bin; And/or two blanking channels are arranged on the supporting table, the upper ends of the blanking channels can be overlapped with the blanking openings at the bottom of the guide bin, the lower ends of the blanking channels are respectively communicated with the feeding openings of the second mixing bin, and a plugging piece for controlling the on-off of blanking is movably arranged in the blanking channels; and/or a round baffle plate is arranged in the guide bin, a plurality of groups of first stirring assemblies are arranged on the round baffle plate, and the first stirring assemblies are used for secondarily mixing aggregate in the guide bin; and/or a temperature control device is arranged on the first mixing bin.
  10. 10. The method for preparing ultra-fine structured isostatic graphite according to claim 8, wherein the feeding mechanism comprises: the storage bin is used for storing graphene; One end of the material conveying box is communicated with the second mixing bin, the inner space is formed by an upper end cylindrical cavity and a lower end cylindrical cavity which are coaxially arranged and have different diameters, and the upper end cylindrical cavity is communicated with the material storage bin; the first piston is arranged in the cylindrical cavity at the upper end of the material conveying box; One end of the connecting rod is connected with the first piston, and the other end of the connecting rod extends downwards and penetrates through the lower end cylindrical cavity; the adjusting box is connected with one end of the material conveying box, which is far away from the storage bin, and the inner parts of the adjusting box and the material conveying box are communicated through a connecting hole; the second piston is arranged in the regulating box; One end of the rod body is rotationally connected with the second piston, and the other end of the rod body penetrates through the outer part of the adjusting box.

Description

Preparation method of isostatic graphite with superfine structure Technical Field The invention relates to the technical field of isostatic pressing graphite preparation, in particular to a preparation method of superfine structure isostatic pressing graphite. Background The isostatic graphite is a high-density isotropic graphite material obtained by taking petroleum coke or asphalt coke as a raw material, calcining, crushing and grinding the raw material, mixing and kneading the raw material with melted bonding asphalt at a certain temperature to obtain paste, and then carrying out secondary grinding, isostatic compaction, roasting, dipping, graphitization and other processes. Graphene is considered one of the most desirable enhancers because of its unique properties. However, how to uniformly disperse graphene in aggregate powder such as micron-sized petroleum coke, asphalt coke and the like faces a great technical challenge, which severely restricts the full play of the reinforcing effect thereof. At present, most of the adopted mixing processes are a one-step direct mixing method, namely, graphene and all aggregates are put into mixing equipment at one time for mechanical stirring. On the one hand, the method has a single mixing flow, cannot realize step-by-step homogenization from macroscopic to microscopic, and often requires extremely long mixing time for pursuing uniformity, so that the production efficiency is low. On the other hand, when graphene and aggregate are mixed in a conventional one-step manner, uncontrollable agglomeration is easy to occur, and agglomerates which are difficult to disperse are formed, and the agglomerates cannot play a role in reinforcement, but become stress concentration points, so that the reliability of a graphite product is seriously deteriorated. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a preparation method of ultra-fine structure isostatic graphite, which aims to solve the problems that graphene in the existing one-step mixing is low in dispersion efficiency and easy to agglomerate, so that the reliability of a product is affected. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: the preparation method of the isostatic graphite with the superfine structure comprises the following steps: step S1, aggregate preparation, namely mixing petroleum coke or pitch coke semicoke superfine powder a with the average particle size of 2-5 mu m with calcined powder or graphite powder b with the average particle size of 2-5 mu m according to the weight ratio of (0.8-1.2) to obtain basic aggregate; step S2, gradient mixing, namely adding graphene accounting for 1% -3% of the total weight of the basic aggregate, and mixing by adopting a gradient mixing method; The gradient mixing method comprises the following steps: S21, premixing 40% -60% of basic aggregate and all graphene to prepare master batch; step S22, finally mixing the master batch with the rest of basic aggregate to obtain composite reinforced aggregate; Step S3, kneading, namely adding coal pitch into the composite reinforced aggregate as a binder, wherein the softening point of the coal pitch is 110-190 ℃, and kneading at a certain temperature to obtain paste; Step S4, pressing powder, namely cooling and crushing the paste, and grinding the paste to obtain paste powder with the average particle size of 15-45 mu m; Step S5, isostatic compaction, namely filling the paste powder into a rubber mold, and maintaining the pressure for 5-15 minutes under the isostatic pressure of 120-160MPa to obtain a green body; step S6, roasting, namely carbonizing the green body in an oxygen-isolated environment; and S7, graphitizing, namely placing the carbonized product into a graphitizing furnace for graphitizing treatment. According to the invention, a gradient mixing method is adopted, namely, about half of basic aggregate and all graphene are premixed to prepare master batch, and then final mixing is carried out, so that the dispersion is more uniform, the enhancement effect of the graphene is fully exerted, and the problems that the graphene is easy to agglomerate and difficult to uniformly disperse in micron powder are effectively solved through a stepwise dilution mechanism. Optionally, in the step S3, nano nickel catalyst accounting for 0.1% -1% of the weight of the coal pitch is pre-dispersed in the coal pitch, and the coal pitch is kneaded in a kneader for 0.5-1.5 hours at the temperature of 180-260 ℃ to obtain the catalytic paste. Optionally, the particle size of the nano nickel catalyst is 20-100 nm, and the nano nickel catalyst is uniformly dispersed in coal tar pitch preheated to liquid state by ultrasonic oscillation for more than 30 minutes. The nano nickel catalyst is introduced in the kneading stage, so that the coal pitch can be catalyzed to be converted into more ordered carbon structures in the subsequent carbonization pro