CN113998696B - Impurity removing method for high-purity graphite - Google Patents
Impurity removing method for high-purity graphite Download PDFInfo
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- CN113998696B CN113998696B CN202111503411.9A CN202111503411A CN113998696B CN 113998696 B CN113998696 B CN 113998696B CN 202111503411 A CN202111503411 A CN 202111503411A CN 113998696 B CN113998696 B CN 113998696B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/20—Graphite
- C01B32/21—After-treatment
- C01B32/215—Purification; Recovery or purification of graphite formed in iron making, e.g. kish graphite
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
- B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
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- General Life Sciences & Earth Sciences (AREA)
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- Environmental & Geological Engineering (AREA)
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- Carbon And Carbon Compounds (AREA)
Abstract
The invention relates to a method for removing impurities from high-purity graphite, which comprises the following operation processes: adding an iron powder carrier into the graphite powder, and maintaining the graphitization temperature at 2500-3000 ℃ for 15-50 hours under the protection of inert gas; primarily removing magnetic metal impurities by magnetic attraction; adding water, stirring, standing for layering, and removing slag at the bottom; then carrying out acid washing, water washing and filtering purification. According to the method, boron carbide generated in the graphitization process reaction is removed through the reducibility of iron, and the graphite impurity removal method is optimized.
Description
Technical Field
The invention relates to a preparation method of high-purity graphite powder, in particular to a method for removing impurities from high-purity graphite.
Background
The current development of high-tech fields and international trade has higher and higher requirements on the quality of graphite, and the graphite with small particles and high purity is urgently needed.
The impurities in the graphite are removed by the method generally: and the graphitization temperature is increased, and the graphitization time is prolonged. The graphitization temperature is raised to about 3000 ℃ and maintained for 15-50 hours, ash content can be reduced to below 0.07%, boron (B) content can be reduced to 0.5PPm, and low boiling impurities such as Si, ca, al, mg and the like are volatilized.
The impurities in graphite are more troublesome to handle as refractory metals, which form high melting point carbides, such as boron carbide (B 4 C) A. The invention relates to a method for producing a fibre-reinforced plastic composite Boron carbide (B) 4 C) The melting point was 2350 ℃, but even when heated to 3500 ℃, boron carbide did not boil, boron formed a stable substitutional solid solution in the graphite structure, and was difficult to remove.
Disclosure of Invention
The present invention aims to solve the above problems and provide an improved method for removing impurities from high purity graphite, which removes extremely harmful impurities such as boron carbide.
In order to solve the problems, the invention adopts the following technical scheme:
the impurity removing method for the high-purity graphite comprises the following operation processes:
(1) Adding an iron powder carrier into the graphite powder, and maintaining the graphitization temperature at 2500-3000 ℃ for 15-60 hours under the protection of inert gas;
(2) After preliminary grading, magnetic metal impurities are preliminarily removed through magnetic attraction;
(3) Adding water, stirring, standing for layering, and removing slag at the bottom;
(4) The graphite powder after preliminary impurity removal is subjected to acid washing, filter pressing, drying and magnetic attraction to remove impurities;
(4) Refining and grading graphite powder for multiple times;
(5) Removing impurities from the finally obtained graphite fine powder by magnetic attraction, and sieving;
the iron powder carrier is iron powder with silicon dioxide coated on the surface.
Further, the preparation method of the iron powder carrier comprises the following operation processes: iron powder and SiO under the protection of inert gas 2 Mixing, ball milling to make the surface of iron powder coated with SiO 2 。
The working principle of the invention is as follows:
boric acid or boric anhydride is mixed in graphite, and under the conditions of high temperature and argon protection, the carbon black reduces the boric acid or boric anhydride into boron carbide, and the reaction is as follows: 7C+4H 3 BO 3 =B 4 C+6H 2 O+6CO；7C+2B 2 O 3 =B 4 C+6co. B formed by the reaction 4 C is reduced by iron, which reacts as: 3B 4 C+4fe+high temperature=4fe 4 B 3 +3C. Fe produced by the reaction 4 B 3 And the unreacted iron powder carrier is removed by magnetic attraction.
The invention has the beneficial effects that:
the method removes boron carbide generated by the graphitization reaction through the reducibility of iron;
the iron powder carrier is helpful for the iron powder not to be directly oxidized in the reaction process;
(3) The silicon dioxide coated on the surface of the iron powder plays a role in protecting the reducibility of the iron powder, and the separated silicon dioxide can be removed by standing and layering after the iron participates in the reaction.
Description of the embodiments
The following detailed description of the preferred embodiments of the invention is provided to enable those skilled in the art to more readily understand the advantages and features of the invention and to make a clear and concise definition of the scope of the invention.
Detailed description of the preferred embodiments
The impurity removing method for the high-purity graphite comprises the following operation processes:
(1) The graphite raw material is refined, the purity of the selected graphite raw material is not lower than 85 percent, and the turbine rotating speed is set to 2500-3000r/min and the classifying time is 15-60s by an air flow refining classifying method of an air flow vortex split refiner.
(2) Adding an iron powder carrier into the graphite powder, and maintaining the graphitization temperature at 2500-3000 ℃ for 15-50 hours under the protection of inert gas nitrogen. Under the protection of inert gas, the iron powder and graphite are not oxidized by air, and the reducibility of the iron removes boron carbide generated by the reaction in the graphitization process. During this graphitization, low boiling impurities such as Si, ca, al, mg and the like have all volatilized.
(3) Adding water into the material tank, stirring, standing for layering, and removing slag at the bottom, wherein silicon dioxide is mainly removed.
(4) After preliminary classification, the material is subjected to preliminary removal of magnetic metal impurities by a permanent magnet machine, and Fe generated in the reaction process can be removed in the process 4 B 3 And an unreacted iron powder carrier.
(5) And (3) carrying out acid washing, filter pressing by a plate-and-frame filter press, adding water and stirring on the graphite powder subjected to primary classification, carrying out filter pressing by the plate-and-frame filter press again, drying at 150-200 ℃, carrying out magnetic attraction to remove impurities, and mixing again. The specific operation is as follows:
putting graphite into a dissolution tank, adding an eluent, wherein the mass of each component in the eluent is 38kg of sulfuric acid (the concentration of sulfuric acid is 98%), 2kg of nitric acid (the concentration of nitric acid is 98%), 38kg of hydrochloric acid (the concentration of hydrochloric acid is 31%), 22kg of hydrofluoric acid (the concentration of hydrofluoric acid is 41%), and then adding 110L of pure water; the mass fraction ratio of the graphite powder to the eluent is 1:2; adjusting the temperature of the dissolving tank to 100-120 ℃ and reacting for 24 hours; then the graphite solution is subjected to filter pressing through a filter press; and adding purified water into wet materials after filter pressing for washing and mixing, carrying out filter pressing again through a filter press, conveying the graphite after filter pressing to a flash evaporation dryer for drying, and carrying out magnetic attraction impurity removal after drying.
(5) Refining the primarily-classified fine graphite powder by an airflow vortex split refiner and classifying by a cyclone separator; the rotating speed of the airflow vortex split refiner is set to 2500-3000r/min, and the refining time is 30-60s; the particle size of graphite powder separated by the cyclone separator is 2-60 mu m. Refining in a third air flow vortex split refiner, wherein the rotating speed is set to 2500-3000r/min, and the refining time is 30-60s; the particle size of graphite powder separated by the cyclone separator is 1.5-40 mu m.
(6) And finally, carrying out double adsorption impurity removal on the obtained graphite fine powder by an electromagnet and a permanent magnet, and then sieving with a 325-mesh sieve.
The water content in the finally prepared high-purity graphite is not more than 0.1%, and the carbon content of the graphite is not less than 99.999%.
Second embodiment
The iron powder carrier refers to iron powder with silicon dioxide coated on the surface. The specific manufacturing process of the iron powder carrier comprises the following steps:
iron powder and SiO 2 Mixing according to a mass ratio of 1:5, wherein SiO is contained in the raw materials 2 A large amount of SiO can be ensured 2 Fully wrap the iron powder.
Under the protection of nitrogen, the surface of the iron powder is coated with SiO by a ball milling method 2 。
Will wrap SiO by magnetic attraction 2 The iron powder carrier is separated out to obtain the pure iron powder carrier used in the graphitization reaction process.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that the above-described embodiments and descriptions are only preferred embodiments of the present invention, and that the present invention is not limited to the above-described preferred embodiments, but is capable of various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications fall within the scope of the present invention as hereinafter claimed.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (2)
1. The impurity removing method for the high-purity graphite comprises the following operation processes:
(1) Adding an iron powder carrier into the graphite powder, and maintaining the graphitization temperature at 2500-3000 ℃ for 15-60 hours under the protection of inert gas;
(2) After preliminary grading, magnetic metal impurities are preliminarily removed through magnetic attraction;
(3) Adding water, stirring, standing for layering, and removing slag at the bottom;
(4) The graphite powder after preliminary impurity removal is subjected to acid washing, filter pressing, drying and magnetic attraction to remove impurities;
(5) Refining and grading graphite powder for multiple times;
(6) Removing impurities from the finally obtained graphite fine powder by magnetic attraction, and sieving;
the iron powder carrier is iron powder with silicon dioxide coated on the surface.
2. The method for removing impurities from high purity graphite according to claim 1, wherein the method for preparing the iron powder carrier comprises the following operation steps: iron powder and SiO under the protection of inert gas 2 Mixing, ball milling to make the surface of iron powder coated with SiO 2 。
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| CN202111503411.9A CN113998696B (en) | 2021-12-10 | 2021-12-10 | Impurity removing method for high-purity graphite |
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| CN113998696B true CN113998696B (en) | 2023-09-26 |
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| CN116425152B (en) * | 2023-04-24 | 2024-05-10 | 昆明理工大学 | Method for preparing high-purity graphite by iron adding refining |
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| WO2003006373A1 (en) * | 2001-07-09 | 2003-01-23 | Showa Denko K.K. | Graphite fine powder, and production method and use thereof |
| JP2003020418A (en) * | 2001-07-09 | 2003-01-24 | Showa Denko Kk | Fine graphite powder, method for producing the same and use thereof |
| RU2581336C1 (en) * | 2014-09-29 | 2016-04-20 | Федеральное государственное бюджетное учреждение науки Институт механики Уральского отделения Российской академии наук | Method for surface alloying of iron-carbon alloy ingots |
| CN109292769A (en) * | 2018-11-23 | 2019-02-01 | 湖南顶立科技有限公司 | A kind of high purity graphite powder and preparation method thereof |
| CN111439750A (en) * | 2020-04-09 | 2020-07-24 | 营口博田材料科技有限公司 | Preparation and purification method of high-purity graphite |
| CN112408382A (en) * | 2020-11-19 | 2021-02-26 | 萝北瑞喆烯碳新材料有限公司 | Preparation method of high-sphericity graphite powder |
| JP2021175703A (en) * | 2020-04-27 | 2021-11-04 | 東洋インキＳｃホールディングス株式会社 | Boron-containing carbon material, resin composition and conductive membrane |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11192792B2 (en) * | 2017-03-14 | 2021-12-07 | Bwt Llc | Boronizing powder compositions for improved boride layer quality in oil country tubular goods and other metal articles |
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Patent Citations (7)
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| WO2003006373A1 (en) * | 2001-07-09 | 2003-01-23 | Showa Denko K.K. | Graphite fine powder, and production method and use thereof |
| JP2003020418A (en) * | 2001-07-09 | 2003-01-24 | Showa Denko Kk | Fine graphite powder, method for producing the same and use thereof |
| RU2581336C1 (en) * | 2014-09-29 | 2016-04-20 | Федеральное государственное бюджетное учреждение науки Институт механики Уральского отделения Российской академии наук | Method for surface alloying of iron-carbon alloy ingots |
| CN109292769A (en) * | 2018-11-23 | 2019-02-01 | 湖南顶立科技有限公司 | A kind of high purity graphite powder and preparation method thereof |
| CN111439750A (en) * | 2020-04-09 | 2020-07-24 | 营口博田材料科技有限公司 | Preparation and purification method of high-purity graphite |
| JP2021175703A (en) * | 2020-04-27 | 2021-11-04 | 東洋インキＳｃホールディングス株式会社 | Boron-containing carbon material, resin composition and conductive membrane |
| CN112408382A (en) * | 2020-11-19 | 2021-02-26 | 萝北瑞喆烯碳新材料有限公司 | Preparation method of high-sphericity graphite powder |
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