CN-117509633-B - Purification method of crystalline graphite

Abstract

The invention discloses a purification method of crystalline graphite, which belongs to the technical field of graphite purification, wherein a mixture of crystalline graphite with carbon content more than 82% and fluoride salt is pretreated, sodium chloride, a dispersing agent and deionized water are added into the pretreated mixture of crystalline graphite and fluoride salt, then the mixture is dried again to obtain a viscous mixture, heat treatment is carried out under inert atmosphere, and high-carbon crystalline graphite can be obtained after water washing. Directly adding hydrochloric acid and deionized water into the mixture after heat treatment, heating and stirring, filtering to separate graphite after the reaction is finished, recycling waste liquid, repeatedly washing the separated graphite with water, filtering, drying and crushing to obtain the high-carbon crystalline graphite with the carbon content higher than 99%. The high-carbon crystalline graphite obtained by the invention has the moisture content of not more than 0.5% and the ash content of not more than 0.7%, and the finished product can be applied to electromagnetic shielding materials, antistatic materials, conductive materials, corrosion resistant materials, lubricants, fireproof materials and the like.

Inventors

• GUO SHOUWU
• Zi Fenggao
• LIU YI
• ZHANG YUMO
• Jia Qiqi
• WANG XIAOFEI
• ZHANG LIFENG

Assignees

• 西安时代烯科新能源科技有限公司
• 陕西科技大学

Dates

Publication Date

20260512

Application Date

20231206

Claims (6)

1. 1. The purification method of the crystalline graphite is characterized by comprising the following steps of: Firstly, uniformly mixing fluoride salt and deionized water, then mixing with crystalline graphite, thermally drying, adding a dispersing agent and sodium chloride, grinding, adding deionized water, performing ultrasonic treatment, thermally drying again to be sticky, and performing heat treatment, water washing and alcohol washing to obtain high-carbon crystalline graphite, wherein the dispersing agent is ammonium chloride or polyvinyl alcohol; Or after heat treatment, adding deionized water and hydrochloric acid, heating and stirring, repeatedly washing with water, filtering and drying to obtain high-carbon crystalline graphite with carbon content more than 99%; The mass of the sodium chloride is 39-48.5% of that of the fluoride salt, and the fluoride salt is lithium fluoride or sodium fluoride; the temperature of the heat treatment is 630-837 ℃, the heat treatment is carried out in inert atmosphere, and the time of the heat treatment is 2.5-5.5 h.
2. 2. The method for purifying crystalline graphite according to claim 1, wherein the mass ratio of deionized water to hydrochloric acid to crystalline graphite is 100 (12-60): 3-10.06).
3. 3. The method for purifying crystalline graphite according to claim 1, wherein the temperature of the heating and stirring is 60 to 80 ℃.
4. 4. The method for purifying crystalline graphite according to claim 1, wherein the heating and stirring time is 4 to 10 hours.
5. 5. The method for purifying crystalline graphite according to claim 1, wherein the mass ratio of the fluoride salt to the crystalline graphite is (0.0057-0.0285): 0.029-0.043.
6. 6. The method for purifying crystalline graphite according to claim 1, wherein the mass of the dispersant is 1.0% to 12.7% of the mass of the crystalline graphite.

Description

Purification method of crystalline graphite Technical Field The invention belongs to the technical field of graphite purification, and particularly relates to a purification method of crystalline graphite. Background The natural graphite can be classified into crystalline graphite and aphanitic graphite, and the crystalline graphite in the natural graphite resources has the characteristics of wide distribution, large ratio and high reserve, and the crystalline graphite is basically required to have high carbon and high purity in the application of multiple fields. The current purification method using crystalline graphite as raw material is mainly hydrofluoric acid method, alkali acid method, chloridizing roasting method and high temperature method. These purification methods generally have carbon contents of over 99%, and although they can meet the purity requirement of 99%, they have certain disadvantages. The reagent-fluohydric acid used in the hydrofluoric acid method has strong toxicity and strong corrosiveness, a large amount of the reagent-fluohydric acid is used with higher danger, meanwhile, because of the strong corrosiveness of hydrofluoric acid, the production equipment is extremely demanding, and the generated wastewater is also highly corrosive, so that the advantage of low cost of the method is greatly reduced due to environmental protection investment, the defect of the chloridizing roasting method is obvious, the used chlorine has strong toxicity, the strong corrosiveness and the tail gas need to be properly treated, so that the method is difficult to be applied on a large scale, and the carbon content of the graphite purified by the high-temperature method can reach more than 99.995 percent, but the energy consumption is extremely high, and the high-temperature furnace needs to be specially designed and constructed, so that the cost is extremely high. The alkaline acid method is the most widely applied method in China at present, but the method is used for purifying the graphite, has high graphite loss rate, large energy consumption and long reaction time, so the cost is high, and in addition, the method is limited to improve the purity of the graphite material, and the main reason is poor dispersity of the graphite in a liquid phase environment. Aiming at the technical problems of strong corrosion, high energy consumption and high cost of the existing purification method of crystalline graphite, a new purification method of crystalline graphite with low cost, simple process and low pollution and the carbon content of the finished product being higher than 99 percent is urgently needed to be found, so that the production safety is improved and the economic benefit is improved. Disclosure of Invention In order to overcome the defects in the prior art, the invention aims to provide a purification method of crystalline graphite, so as to solve the technical problems of strong corrosion, high energy consumption and high cost of the existing purification method of crystalline graphite. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the invention discloses a purification method of crystalline graphite, which comprises the following steps: firstly mixing fluoride salt, deionized water and crystalline graphite, thermally drying, adding a dispersing agent and sodium chloride, grinding, adding deionized water, carrying out ultrasonic treatment, thermally drying again to be sticky, and carrying out heat treatment, water washing and alcohol washing to obtain the high-carbon crystalline graphite. Preferably, after heat treatment, deionized water and hydrochloric acid are added, heated and stirred, repeatedly washed with water, filtered and dried to obtain the high-carbon crystalline graphite with carbon content more than 99%. Further preferably, the mass ratio of deionized water to hydrochloric acid to crystalline graphite is 100 (12-60) to 3-10.06. Further preferably, the temperature of the heating and stirring is 60-80 ℃. Further preferably, the heating and stirring time is 4 to 10 hours. Preferably, the mass ratio of fluoride salt to crystalline graphite is (0.0057-0.0285): 0.029-0.043. Preferably, the mass of the dispersing agent is 1.0% -12.7% of that of the crystalline graphite, and the dispersing agent is ammonium salt or polyvinyl alcohol. Preferably, the mass of sodium chloride is 39% -48.5% of the mass of the fluoride salt. Preferably, the heat treatment is carried out for a period of time of 2.5 to 5.5 hours. Preferably, the heat treatment is carried out at a temperature of 630-837 ℃ under an inert atmosphere. Compared with the prior art, the invention has the following beneficial effects: The invention discloses a purification method of crystalline graphite, which comprises the steps of mixing fluoride salt, deionized water and crystalline graphite, removing metal oxides such as aluminum oxide, calcium oxide and the like in the c