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CN-121988529-A - Miniature negative pressure separation system for graphite material super-crushing process

CN121988529ACN 121988529 ACN121988529 ACN 121988529ACN-121988529-A

Abstract

The invention discloses a miniature negative pressure separation system for a graphite material super-crushing process, which comprises the steps of firstly carrying out ultrasonic pre-dispersion on super-crushed graphite powder under the protection of inert gas to dissociate agglomerated particles to form uniform suspension powder cloud; and then sealing feeding between the normal pressure region and the negative pressure grading region is realized through a spiral airlock mechanism. Under the negative pressure environment, powder sequentially passes through coarse separation of a speed-increasing channel, fractionation of a rotational flow field and dispersion conditioning under the action of an electrostatic field to form a stable gas-solid two-phase system suitable for fine screening. The fine grading part adopts a multi-layer ceramic membrane filtering structure to cut off the particle size of submicron and nanometer powder, and realizes periodic regeneration of the membrane surface through a pulse back-blowing device so as to maintain the continuous stability of the filtering flux. The system realizes closed-loop control of atmosphere through negative pressure air extraction and oxygen content monitoring, so that the whole process is operated under the condition of low oxygen, and graphite powder with different particle size grades such as coarse powder, medium powder, fine powder and nano powder is obtained.

Inventors

  • DING HONGWEI
  • Ding Shuangwei
  • Yuan Zhixiao
  • LUO XIAOQING

Assignees

  • 上海亿鼎技术(集团)有限公司

Dates

Publication Date
20260508
Application Date
20260209

Claims (10)

  1. 1. A separation method of a miniature negative pressure separation system for a graphite material super-crushing process is characterized by comprising the following steps: (1) Under the protection of inert gas, pre-dispersing the graphite powder subjected to super-crushing treatment to dissociate agglomerated particles and form a gas-solid two-phase system capable of being stably transported; (2) The pre-dispersed graphite powder is guided into a negative pressure classification space from a normal pressure area in a sealing way through an airlock feeding mechanism; (3) In the negative pressure classification space, aiming at different separation stages, respectively applying a negative pressure state and a flow field condition matched with a separation mechanism of the stage, and sequentially carrying out coarse separation, classification separation and fine separation on graphite powder, so that different particle size graphite particles obtain different flow-following behaviors in the corresponding stages; (4) Performing dispersion conditioning treatment on the graphite powder in a selected particle size range between fractionation and fine separation to inhibit secondary agglomeration of submicron particles before entering the fine separation; (5) According to the running state of the fine separation unit, desorption and recovery are carried out on the attached or deposited graphite powder, and the stability of the negative pressure environment is synchronously maintained; (6) And performing closed-loop regulation and control on the pressure state and the atmosphere composition in the separation process, so that the graphite powder is subjected to multistage separation in a low-oxygen negative pressure environment, and graphite coarse powder, medium powder, fine powder and/or nano-scale graphite powder classified according to particle size intervals are obtained.
  2. 2. The micro negative pressure separation system according to claim 1 is used for a graphite material super-pulverizing process, and is characterized in that in the step (1), inert gas is introduced into the sealed pre-dispersion cavity, and the graphite powder is deagglomerated by adopting an ultrasonic vibration mode, so that the graphite powder is converted into a uniformly dispersed suspension state from an agglomerated state.
  3. 3. The micro negative pressure separation system according to claim 1, wherein in the step (2), the airlock feeding mechanism comprises a normal pressure area communicated with the pre-dispersion cavity, a negative pressure area communicated with the negative pressure classifying space and a rotating impeller structure arranged between the normal pressure area and the negative pressure area, the rotating impeller structure passes through the normal pressure area and the negative pressure area in sequence through the impeller cavity, and the impeller cavity bearing graphite powder is transferred into the negative pressure area from the normal pressure area to realize sealed feeding and prevent external air from flowing backwards.
  4. 4. The micro negative pressure separation system according to claim 1, wherein the coarse separation in the step (3) is achieved by mixing graphite powder with inert gas into an acceleration channel, the flow channel structure of the acceleration channel is used for increasing the gas flow speed and changing the flow line, so that large particles or coarse particles which are not sufficiently crushed deviate from the main gas flow under the inertia effect, and the coarse particles are led into a coarse powder collecting channel.
  5. 5. The micro negative pressure separation system according to claim 1, wherein the classification process in the step (3) is implemented by forming a rotational flow or a vortex flow field in the classification cavity, so that the roughly separated graphite powder is split in the rotational flow field according to the differences of particle size, density and motion track, the particles with larger particle size move outwards under the centrifugal force and are guided out as medium powder or coarse powder, and the particles with smaller particle size enter the fine separation area along with the central flow or the rising main air flow.
  6. 6. The micro negative pressure separation system according to claim 1, wherein the fine separation in the step (3) comprises an electrostatic dispersion link and a membrane separation link, wherein the electrostatic dispersion link applies a high voltage electrostatic field to a local area of the classification cavity to charge the surface of submicron graphite particles so as to weaken the adhesion between particles and cavity walls; and in the membrane separation step, the gas-solid two phases after electrostatic dispersion are led into a membrane separation unit, so that graphite particles smaller than a preset cut-off particle size and inert gas penetrate through a filter membrane, and the graphite particles larger than the cut-off particle size are trapped and collected as target fine powder or nano-scale graphite powder.
  7. 7. The micro negative pressure separation system according to claim 1, wherein the desorption and recovery in the step (4) are achieved by reversely introducing a pulse gas flow to the hierarchical structure or the membrane surface, the pulse gas flow is formed by inert gas, the pulse gas flow acts on the surface attached with graphite powder in a periodically short-time high-pressure form, and the graphite powder is peeled and guided into the corresponding powder collecting cavity.
  8. 8. The micro negative pressure separation system according to claim 1 is used for a graphite material super-crushing process, and is characterized in that the pressure adjustment in the step (5) is realized by a multi-stage air extractor, the pressure in the negative pressure grading space is controlled within a preset negative pressure range, and the extraction amount is adjusted according to the change of the grading working condition, so that the pressure fluctuation is reduced, and the stability of the gas-solid two-phase flow field is ensured.
  9. 9. The micro negative pressure separation system according to claim 1, wherein the atmosphere adjustment in the step (5) is performed by setting an atmosphere monitoring device to detect the oxygen content in the negative pressure classification space in real time, and is linked with an inert gas supply device, and when the detected oxygen content exceeds a preset threshold value, inert gas is automatically supplied, so that the oxygen content in the negative pressure classification space is maintained below the threshold value, and oxidation of graphite powder is inhibited.
  10. 10. The micro negative pressure separation system according to claim 1 is used for a graphite material super-crushing process, and is characterized in that graphite powder obtained through coarse separation, classification separation and fine separation is respectively used as graphite coarse powder, graphite middling powder, graphite fine powder and nano-scale graphite powder to be led into different collecting channels for classification storage according to different particle size ranges for classification utilization of different subsequent application scenes.

Description

Miniature negative pressure separation system for graphite material super-crushing process Technical Field The invention relates to the technical field of fine processing of powder materials, in particular to a miniature negative pressure separation system for a graphite material super-crushing process. Background After the super-crushing treatment, the particle size of the graphite material can enter the range from micron to submicron. The superfine powder is extremely easy to agglomerate and adsorb moisture or oxygen molecules in the air, and is highly sensitive to air flow disturbance in the transportation and classification process, so that how to realize high-precision classification on the premise of keeping the stable powder structure in actual industrial production is always one of the key problems in the field of graphite fine processing. The conventional classification equipment mainly comprises a cyclone classifier, an air classifier, a mechanical screening device and the like, wherein the basic requirements can be met when common micron-sized powder is processed by the classification equipment, but certain limitations exist when the classification equipment faces ultra-crushed graphite powder. Firstly, the specific surface area of the superfine graphite powder is large, the surface energy is high, and the adhesion and agglomeration phenomenon between particles are easy to generate. Under the high-speed air flow or strong turbulence environment, the agglomerates are easy to reform, so that the particle size distribution of the powder is widened, and the classification precision is reduced. Secondly, graphite itself is more prone to surface oxidation in an oxygen environment, and particularly the activity of the exposed fresh crystal faces after super-crushing is higher. The traditional open type grading equipment is difficult to provide a controllable low-oxygen environment, the oxidation degree of powder is increased in the grading process, and the powder is unfavorable for the performance maintenance in the fields of conductive materials, energy storage or high-end lubrication and the like. In addition, the existing classification equipment generally depends on normal pressure or micro-positive pressure conditions, and although the process is simple, the entry of external air is difficult to avoid, so that the fluctuation of atmosphere components is obvious. For ultrafine powder sensitive to oxygen content, it is difficult to ensure a stable processing environment. Meanwhile, the problem that powder is easy to adsorb, adhere to the wall surface or block the filter element occurs in the long-term operation of the part of hierarchical structure, the continuous stability of the equipment is affected, and the maintenance cost is increased. Under the continuous operation condition, the superfine powder is easy to cause secondary agglomeration through repeated collision or repeated circulation in the classifier, so that the classification efficiency is reduced. For nano-scale graphite powder, the traditional classification mode is difficult to accurately intercept and collect due to the extremely small particle size and extremely weak inertia, so that the yield of the ultrafine powder with high added value is low. In addition, in the membrane classification or filtration link, because the powder layer is continuously accumulated, if effective membrane surface regeneration measures are not available, the filtration resistance is easily increased, the processing capacity is easily reduced, and even the system is stopped. Therefore, there is an urgent need for a micro negative pressure separation system for a graphite material super-pulverizing process to solve the above problems. Disclosure of Invention The invention aims to solve the technical problems in the background art, and provides a separation method of a miniature negative pressure separation system for a graphite material super-crushing process, which comprises the following steps: (1) Under the protection of inert gas, pre-dispersing the graphite powder subjected to super-crushing treatment to dissociate agglomerated particles and form a gas-solid two-phase system capable of being stably transported; (2) The pre-dispersed graphite powder is guided into a negative pressure classification space from a normal pressure area in a sealing way through an airlock feeding mechanism; (3) In the negative pressure classification space, aiming at different separation stages, respectively applying a negative pressure state and a flow field condition matched with a separation mechanism of the stage, and sequentially carrying out coarse separation, classification separation and fine separation on graphite powder, so that different particle size graphite particles obtain different flow-following behaviors in the corresponding stages; (4) Performing dispersion conditioning treatment on the graphite powder in a selected particle size range between fractionatio