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CN-121974338-A - High-purity graphite powder and preparation method thereof

CN121974338ACN 121974338 ACN121974338 ACN 121974338ACN-121974338-A

Abstract

The invention provides high-purity graphite powder and a preparation method thereof. The preparation method comprises the steps of mixing alkali liquor, graphite and a surfactant, performing gradient microwave treatment, separating a solid product after the reaction is finished to obtain alkali-treated graphite, mixing the alkali-treated graphite with the acid liquor, heating for acid treatment, separating the solid product after the reaction is finished to obtain high-purity graphite powder, wherein the mass ratio of the graphite to the surfactant is 1 (0.001-0.1), and the gradient microwave treatment comprises a first microwave treatment stage, a second microwave treatment stage and a third microwave treatment stage. According to the invention, through the synergistic effect of echelon microwave-assisted alkali treatment and ultraviolet light catalytic acid treatment, the dual aims of accurate impurity removal and graphite structure protection can be realized, and finally the high-purity graphite powder with high fixed carbon content can be prepared at a lower temperature in a shorter time.

Inventors

  • WANG JIONGHUI
  • JIA WENLI
  • HUANG DONGMEI

Assignees

  • 五矿勘查开发有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (13)

  1. 1. The preparation method of the high-purity graphite powder is characterized by comprising the following steps: S1, mixing alkali liquor, graphite and a surfactant, and performing echelon microwave treatment; S2, mixing the alkali treated graphite with acid liquor, and heating to perform acid treatment; wherein the mass ratio of the graphite to the surfactant is 1 (0.001-0.1); the mass ratio of the alkali liquor to the graphite is (0.5-10): 1; the mass ratio of the acid liquor to the alkali treated graphite is (0.5-20): 1; The echelon microwave treatment comprises a first microwave treatment stage, a second microwave treatment stage and a third microwave treatment stage, wherein the reaction temperature of the first microwave treatment stage is 20-80 ℃, the reaction temperature of the second microwave treatment stage is 80-150 ℃, and the reaction temperature of the third microwave treatment stage is 150-600 ℃.
  2. 2. The method for preparing high purity graphite powder according to claim 1, wherein the reaction time of the first microwave treatment stage is 10-60 min, the reaction time of the second microwave treatment stage is 10-60 min, and the reaction time of the third microwave treatment stage is 15-60 min.
  3. 3. The method for preparing high purity graphite powder according to claim 1, wherein in step S2, the heating is performed at a temperature of 40 to 90 ℃ for a time of 30 to 300 min.
  4. 4. A method for producing high purity graphite powder according to claim 1 or 3, wherein in step S2, the heating for the acid treatment is performed under ultraviolet light irradiation having a wavelength of 200 to 400 nm and an optical power density of 50 to 200 mW/cm 2 .
  5. 5. The method for preparing high purity graphite powder according to claim 1, wherein the alkali in the alkali solution has a mass fraction of 10% -80%.
  6. 6. The method for preparing high purity graphite powder according to claim 1, wherein the concentration of the acid solution is 0.5-20 mol/L.
  7. 7. The method for preparing high purity graphite powder according to claim 1 or 6, wherein the acid solution comprises HNO 3 solution or a mixed solution of HNO 3 and HCl.
  8. 8. The method of producing high purity graphite powder according to claim 7, wherein the molar ratio of HNO 3 to HCl in the mixed solution of HNO 3 and HCl is (1-10): 1.
  9. 9. The method for preparing high purity graphite powder according to claim 1, wherein in step S1, the graphite is natural graphite having a fixed carbon content of 90% -95%.
  10. 10. The method for preparing high purity graphite powder according to claim 1, wherein the surfactant comprises one or a combination of two or more of cetyltrimethylammonium bromide, polyethylene glycol and polyvinylpyrrolidone.
  11. 11. The method for preparing high purity graphite powder according to claim 1, wherein the alkali treated graphite has a static water contact angle of less than 70 °.
  12. 12. A high-purity graphite powder is characterized in that, the high-purity graphite powder is prepared by the preparation method of the high-purity graphite powder in any one of claims 1-11.
  13. 13. The high purity graphite powder of claim 12, wherein the high purity graphite powder has a fixed carbon content of 99.84% or more and an ash content of 0.14% or less.

Description

High-purity graphite powder and preparation method thereof Technical Field The invention belongs to the technical field of high-purity graphite preparation, and particularly relates to high-purity graphite powder and a preparation method thereof. Background Graphite is widely applied to high-end industrial fields such as new energy sources, semiconductors and the like due to excellent electrical conductivity, thermal conductivity and chemical stability, and high purity with fixed carbon content of more than or equal to 99.9% is a key precondition for playing core performances. The main graphite purifying method in industry is an alkali acid method, the principle is that acid oxide impurities (such as SiO 2、Al2O3) are removed through alkali treatment, then metal impurities (such as Fe, ca and Mg) are removed through acid treatment, but the prior art has the following technical defects that the alkali treatment stage adopts a high-temperature alkali fusion method of 500-800 ℃, the reaction time is long, the energy consumption is high, the sintering collapse of pi-pi conjugated structures between graphite layers is easy to cause, the crystal integrity is damaged, the contact between strong alkali and graphite particles is uneven due to external heating, the incomplete reaction of the acid oxide impurities is easy to cause, and the acid treatment stage depends on conventional acid systems such as nitric acid, hydrochloric acid and the like. Wherein, hydrochloric acid mainly relies on H + to remove most metal oxides, and nitric acid relies on the synergistic effect of H + and strong oxidizing acid ions thereof to remove metal impurities. However, the process needs to react for several hours at 60-100 ℃, and the passivation film on the surface of the metal impurity is difficult to break through due to the limited overall oxidation capability and dissolution selectivity of the conventional acid system, so that the residual quantity of the metal impurity is high, the fixed carbon content is difficult to break through 99.9%, and meanwhile, the acid liquid volatilization (such as NO 2 gas) is aggravated by high-temperature reaction, so that the environment is polluted, and the acid consumption is increased. Therefore, there is a need to develop a new process for purifying graphite with low energy consumption, short time and high purity, so as to achieve the dual purposes of efficient removal of impurities and protection of graphite structure. Disclosure of Invention In order to solve the technical problems, the invention aims to provide high-purity graphite powder and a preparation method thereof. The high-purity graphite powder has the characteristics of high fixed carbon content and low ash content, and can maintain a good morphology structure. In order to achieve the above object, the present invention provides a method for preparing high purity graphite powder, wherein the method comprises: S1, mixing alkali liquor, graphite and a surfactant, and performing echelon microwave treatment; S2, mixing the alkali treated graphite with acid liquor, and heating to perform acid treatment; Wherein the mass ratio of the graphite to the surfactant is 1 (0.001-0.1), the mass ratio of the alkali liquor to the graphite is 1 (0.5-10), and the mass ratio of the acid liquor to the alkali treated graphite is 1 (0.5-20); The echelon microwave treatment comprises a first microwave treatment stage, a second microwave treatment stage and a third microwave treatment stage, wherein the reaction temperature of the first microwave treatment stage is 20-80 ℃, the reaction temperature of the second microwave treatment stage is 80-150 ℃, and the reaction temperature of the third microwave treatment stage is 150-600 ℃. In the above preparation method, the mass ratio of the graphite to the surfactant is preferably 1 (0.001-0.05), more preferably 1 (0.001-0.01). According to a specific embodiment of the present invention, it is preferable that the reaction time of the first microwave treatment stage is 10 to 60min, the reaction time of the second microwave treatment stage is 10 to 60min, and the reaction time of the third microwave treatment stage is 15 to 60 min. In the above preparation method, preferably, the reaction temperature of the first microwave treatment stage is 40-80 ℃ and the reaction time is 10-40 min, the reaction temperature of the second microwave treatment stage is 100-150 ℃ and the reaction time is 10-40 min, and the reaction temperature of the third microwave treatment stage is 200-400 ℃ and the reaction time is 15-40 min. More preferably, the reaction temperature of the first microwave treatment stage is 50-80 ℃, the reaction time is 10-20 min ℃, the reaction temperature of the second microwave treatment stage is 120-150 ℃, the reaction time is 15-30 min, and the reaction temperature of the third microwave treatment stage is 300-350 ℃ and the reaction time is 15-25 min. According to a specific embodiment of the present inve