CN111362263A

CN111362263A - Preparation method of high-purity graphite material

Info

Publication number: CN111362263A
Application number: CN202010263795.0A
Authority: CN
Inventors: 吴雷
Original assignee: Foshan Ruizhijin Zhihui Technology Co ltd
Current assignee: Foshan Ruizhijin Zhihui Technology Co ltd
Priority date: 2020-04-07
Filing date: 2020-04-07
Publication date: 2020-07-03

Abstract

A preparation method of a high-purity graphite material relates to the technical field of graphite material preparation; it comprises the following steps: 1. taking raw material graphite, introducing the raw material graphite into an intermittent graphite purification device, and carrying out heat preservation treatment for 0.5-2.0h under the temperature condition of 900-1600 ℃ to obtain a solid product; the temperature is preferably 1400-1600 ℃; 2. continuously heating the solid product obtained by the treatment in the step 1, and carrying out heat preservation treatment at a certain temperature of 1800-2100 ℃ for 1-3 h to obtain high-purity graphite; the temperature is preferably 2000-. According to the preparation method of the high-purity graphite material, the purification method is adopted, so that the energy consumption of high-purity graphite in unit yield can be reduced, the production efficiency is improved, the production cost is reduced, and the pressure for treating tail gas in the later period is low.

Description

Preparation method of high-purity graphite material

Technical Field

The invention relates to the technical field of graphite material preparation, in particular to a preparation method of a high-purity graphite material.

Background

Graphite is an allotrope of carbon, has characteristics of good electrical conductivity and thermal conductivity, excellent chemical stability and the like, graphite with a carbon content of 99.9% or more is called high-purity graphite, and the higher the purity of graphite, the higher the application value, for example, graphite is used as a negative electrode material of a lithium battery, a neutron absorber of a high-temperature nuclear reactor, a heating body of a semiconductor single crystal furnace and an optical fiber drawing furnace, and the like, and is widely applied to industrial fields of metallurgy, chemical industry, aerospace, electronics, machinery, nuclear energy and the like. The impurities contained in the graphite are mainly silicate minerals such as potassium, sodium, magnesium, iron, calcium, aluminum and the like, and the conventional method for producing high-purity graphite at home and abroad is usually a hydrofluoric acid method, an acid-base method, a chlorination roasting method and a high-temperature method. The hydrofluoric acid method has simple process flow and low cost, but has high corrosion to equipment and high environmental protection treatment pressure; the acid-base method has the advantages of less investment, strong applicability and low cost, but has the defects of large energy consumption, long process flow, serious corrosion to equipment, difficult treatment of wastewater pollution and the like; the chlorination roasting method has high efficiency, high recovery rate and low energy consumption, but the chlorine generated by the reaction has corrosivity and toxicity and seriously pollutes the environment; the high-temperature method has the main advantages that the method can produce over 99.99 percent of ultra-pure graphite, but has large energy consumption, high requirements on equipment performance and high production cost, and limits the popularization and application of the process to a certain extent. Therefore, the realization of high cost performance and low environmental pollution is the main development direction of the graphite purification technology.

Disclosure of Invention

The invention aims to provide a preparation method of a high-purity graphite material, which can reduce the purification temperature of a high-temperature method and the heat insulation requirement of a graphite purification furnace, aiming at the defects and the defects of the prior art.

In order to achieve the purpose, the invention adopts the technical scheme that: a preparation method of a high-purity graphite material comprises the following steps:

1. taking raw material graphite, introducing the raw material graphite into an intermittent graphite purification device, and carrying out heat preservation treatment for 0.5-2.0h under the temperature condition of 900-1600 ℃ to obtain a solid product; the temperature is preferably 1400-1600 ℃;

2. continuously heating the solid product obtained by the treatment in the step 1, and carrying out heat preservation treatment at a certain temperature of 1800-2100 ℃ for 1-3 h to obtain high-purity graphite; the temperature is preferably 2000-.

Further, the carbon content of the raw material graphite is 92-99%, and further, the carbon content is 92-95%.

Further, during the temperature rising process of the step 1 and the step 2, halogen-containing gas is introduced into the device.

Further, the halogen-containing gas in the step 1 at the temperature of 900-1600 ℃ is a mixed gas of carbon tetrachloride, freon and chlorine; the halogen-containing gas is preferably chlorine at the temperature of 1800 ℃ and 2100 ℃ in step 2.

Further, the gas flow rate in the step 1 and the step 2 is controlled to be 0.5-2.5m3/h, wherein the gas flow rate is the gas flow rate introduced into the inner cavity of the purification device per cubic meter.

The invention has the following beneficial effects: according to the preparation method of the high-purity graphite material, the purification method is adopted, the energy consumption of high-purity graphite in unit yield can be reduced, the production efficiency is improved, the production cost is reduced, the pressure for tail gas treatment in the later period is low, and the high-purity graphite material with the purity of more than 99.99 percent can be obtained; in particular industrial fields, such as semiconductor sintering, single crystal pulling or fiber drawing processes, it is required that the impurity content in the graphite heating body used should not exceed several tens ppm. Therefore, the graphite with the purity of more than 99.99 percent provided by the invention has extremely high application value. Compared with the prior art, the preparation method of the high-purity graphite provided by the invention can reduce the purification temperature of a high-temperature method and the heat insulation requirement on a graphite purification furnace, creates conditions for industrial production of the high-purity graphite, and has great practical popularization value.

Drawings

FIG. 1 is a flow chart of the preparation of the present invention.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Example 1

1. Taking natural graphite concentrate ground to the particle size of 150-200 mu m and containing 92-96% of carbon, vacuumizing at room temperature-900 ℃, heating at the speed of 10-20 ℃/min, introducing nitrogen for protection when the temperature reaches 900 ℃, continuously heating at the speed of 10 ℃/min at 900 ℃ (in the process, the temperature is controlled to be below 1600 ℃), simultaneously introducing halogen-containing mixed gas, and preserving the heat at 1480 ℃ for 0.5h to obtain a solid product; the gas flow rate of the halogen-containing mixed gas in the process is as follows: 1m 3/h.

2. And continuously heating the obtained solid product in a graphite purification device, introducing halogen-containing mixed gas to 2000 ℃, and keeping the temperature for 1h, wherein the heating rate is 2-5 ℃/min, and the gas flow rate is 2m 3/h.

Detection shows that the carbon content of the graphite treated in the first step is 99%, and the carbon content of the graphite treated in the second step is 99.99%.

Example 2

1. Taking a molded graphite sample with the carbon content of 98% and the sample size of 20 x 50 x 500mm, vacuumizing at room temperature-900 ℃, and heating at the speed of 15 ℃/min; introducing nitrogen for protection when the temperature reaches 900 ℃, continuously heating at the temperature of 900-1600 ℃ at the speed of 5 ℃/min, simultaneously introducing halogen-containing mixed gas, and preserving the heat at the temperature of 1500 ℃ for 1h to obtain a solid product; in the process, the gas flow rate of the halogen-containing mixed gas is 1m 3/h;

2. and (3) continuously heating the solid product obtained in the step one to 2100 ℃ in a graphite purification device at the speed of 2-5 ℃/min, simultaneously introducing halogen-containing mixed gas, and keeping the temperature for 2h, wherein the gas flow rate in the process is 2m 3/h.

Detection shows that the carbon content of the graphite treated in the first step is 99.5%, and the carbon content of the graphite treated in the second step is 99.999%.

Example 3

1. Taking an isostatic pressing graphite sample with the carbon content of 99% and the sample size of 20 x 50 x 500mm, vacuumizing at room temperature to 900 ℃, and heating at the speed of 15 ℃/min; introducing nitrogen for protection when the temperature reaches 900 ℃, continuously heating at the temperature of 900-1600 ℃ at the speed of 5 ℃/min, simultaneously introducing halogen-containing mixed gas, and preserving the heat at 1600 ℃ for 1h to obtain a solid product; the flow rate of the halogen-containing mixed gas is 1.5m 3/h;

2. and continuously heating the obtained solid product to 2200 ℃ in a graphite purification device at the speed of 2-5 ℃/min, simultaneously introducing halogen-containing mixed gas, and keeping the temperature for 1h, wherein the gas flow rate in the process is 2m 3/h.

Detection shows that the carbon content of the graphite treated in the first step is 99.9%, and the carbon content of the graphite treated in the second step is 99.999%.

In the above 3 embodiments, in order to ensure effective and sufficient removal of impurities in the graphite raw material, a halogen-containing gas was introduced into the apparatus during the temperature raising process.

The introduction of the halogen-containing gas means that the gas containing halogen elements, such as carbon tetrachloride, freon, chlorine, fluorine gas, etc., is continuously introduced during the purification process in the present embodiment; under the conditions of 900-1600 ℃ in the step 1, the halogen-containing gas is a mixed gas of carbon tetrachloride, freon and chlorine; the halogen-containing gas is preferably chlorine at the temperature of 1800-2100 ℃ in step 2, and the gas flow rate of 3 examples in the embodiment is controlled to be 0.5-2.5m 3/h; the gas flow rate refers to the gas flow rate introduced into the inner cavity of the purification device per cubic meter.

The foregoing shows and describes the general principles and features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The preparation method of the high-purity graphite material is characterized by comprising the following steps of:

(1) taking raw material graphite, introducing the raw material graphite into an intermittent graphite purification device, and carrying out heat preservation treatment for 0.5-2.0h under the temperature condition of 900-1600 ℃ to obtain a solid product; the temperature is preferably 1400-1600 ℃;

(2) continuously heating the solid product obtained by the treatment in the step 1, and carrying out heat preservation treatment at a certain temperature of 1800-2100 ℃ for 1-3 h to obtain high-purity graphite; the temperature is preferably 2000-.

2. The method for preparing a high-purity graphite material according to claim 1, wherein: the carbon content of the raw material graphite is 92-99%, and further, the carbon content is 92-95%.

3. The method for preparing a high-purity graphite material according to claim 1, wherein: and (3) introducing halogen-containing gas into the device in the heating process of the step (1) and the step (2).

4. The method for preparing a high-purity graphite material according to claim 1, wherein: the halogen-containing gas in the step (1) is a mixed gas of carbon tetrachloride, freon and chlorine at 900-1600 ℃; the halogen-containing gas is preferably chlorine gas at the temperature of 1800 ℃ and 2100 ℃ in step (2).

5. The method for preparing a high-purity graphite material according to claim 1, wherein: step (1) and step (2) control the gas flow to be 0.5-2.5m3/h, wherein the gas flow is the gas flow introduced into the inner cavity of the purification device per cubic meter.