4n or more high purity graphite and continuous gas phase production method and applications thereof

Abstract

The present application belongs to the field of graphite purification, and particularly relates to a continuous gas phase preparation method of 4N or more high-purity graphite. The graphite raw material is pre-processed in a first stage under atmosphere A and temperature T1 to obtain a first-stage material. The atmosphere A is an oxidizing atmosphere, and the temperature T1 is 400-600 DEG C. The first-stage material and a synergistic additive are mixed and placed in an atmosphere furnace, pre-processed in a second stage under atmosphere B and temperature T2 to obtain a second-stage material. Then, the atmosphere of the atmosphere furnace is switched to atmosphere C, and the third-stage processing is carried out under temperature T3 and positive pressure to obtain 4N or more high-purity graphite. The synergistic additive contains chloride and fluoride, the atmosphere B is a low-oxygen atmosphere with an oxygen content of less than 10v%, the temperature T2 is 900-1200 DEG C, the atmosphere C is a functional gas containing at least one of chlorine, fluorine and halogenated hydrocarbon, and the temperature T3 is 1300-1700 DEG C. The method can obtain graphite with high purity, excellent graphitization degree and tap density at a high carbon yield.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of waste graphite regeneration, and particularly relates to the field of super-pure graphite preparation. BACKGROUND

[0002] Graphite is a strategic resource, and has a wide range of applications in the fields of semiconductors, new energy, metallurgy, aerospace, refractory materials, nuclear energy and the like due to its excellent electrical conductivity, thermal conductivity, lubricity, high-temperature resistance and corrosion resistance. The higher the purity of graphite, the better its performance, and the more widely it is applied in high-tech industries. At present, with the development of the industry, a large amount of waste graphite is retired from the above-mentioned fields year by year. Due to high impurity content and damaged microstructure, it is difficult to directly reuse in specific fields. Therefore, there is an urgent need to develop new methods for purifying waste graphite.

[0003] For graphite purification, the current mainstream methods are acid-base wet method and heat treatment impurity removal, etc. For example, the Chinese patent document with the publication number CN113675492A discloses a method for recycling graphite material from waste lithium-ion batteries, which specifically records that the waste graphite is pre-activated by using a strong base, and then the graphite is reactivated by microwave treatment to obtain the graphite material. The Chinese patent document with the publication number CN117096485A discloses a method for selectively separating graphite from waste battery black powder, which comprises the following steps: the waste battery black powder containing graphite and positive active material is slurried with water to obtain a slurry, O3 is blown into the slurry and subjected to first-stage modification treatment under light irradiation with a wavelength of 100-160 nm, then a modifier is added for second-stage modification treatment, and finally a foaming agent is added for flotation treatment; graphite concentrate and positive active material flotation tailings are obtained. For another example, the Chinese patent document with the publication number CN118198570A discloses a high-rate regenerated graphite negative material and a preparation method and application thereof, which specifically records that the waste graphite negative sheet is cleaned with dimethyl carbonate, dried, and subjected to knocking to separate the waste graphite from the copper foil to obtain the recycled graphite; the recycled graphite is subjected to medium-high temperature calcination to obtain the purified graphite.

[0004] In summary, the existing waste graphite treatment methods mainly regenerate the waste graphite into negative materials, and it is difficult to obtain 4N or more high-purity graphite by using the treatment ideas and methods, and in addition, a large amount of three wastes is also easily produced. SUMMARY

[0005] In view of the problem that the existing waste graphite material recycling process is difficult to obtain super-high-purity graphite, the application provides a preparation method of 4N or more high-purity graphite, which aims to prepare 4N or more high-purity graphite suitable for higher application requirements.

[0006] The second object of the application is to provide 4N or more high-purity graphite prepared by the preparation method.

[0007] The third object of the present application is to provide the application of the 4N high purity graphite.

[0008] The existing waste graphite wet method has long process, large wastewater output, low purification efficiency and effect, and low carbon yield, and it is difficult to obtain 4N high purity graphite stably, and in addition, the existing purification method can easily damage the graphitization degree and tap density of graphite. In view of this problem, the present application provides the following scheme after in-depth research:

[0009] A continuous gas phase preparation method of 4N high purity graphite, the graphite raw material is pretreated in atmosphere A and temperature T1 to obtain a first-stage material; the atmosphere A is an oxidizing atmosphere; the temperature T1 is 400-600 DEG C;

[0010] Mixing the first-stage material and the synergistic aid, and then placing it in an atmosphere furnace, and pretreating it in atmosphere B and temperature T2 to obtain a second-stage material; then switching the atmosphere in the atmosphere furnace to atmosphere C and treating it in temperature T3 and positive pressure to obtain 4N high purity graphite;

[0011] The synergistic aid contains chloride and fluoride, the atmosphere B is a low-oxygen atmosphere with oxygen content below 10v%; the temperature T2 is 900-1200 DEG C;

[0012] The atmosphere C is a functional gas containing at least one of chlorine, fluorine and halogenated hydrocarbon, and the temperature T3 is 1300-1700 DEG C.

[0013] The present application provides a continuous variable gas phase purification graphite idea, which realizes the deep purification of graphite based on the whole atmosphere treatment mode, and can obtain high carbon yield, high purity graphite with purity above 4N, good tap density and graphitization degree, and the present application can avoid a large amount of three wastes.

[0014] In the present application, the graphite raw material is a graphite raw material with a graphite content of 95wt.% or more;

[0015] In the present application, the graphite raw material includes waste graphite material separated from waste batteries and waste semiconductors.

[0016] In the present application, the atmosphere A is an atmosphere containing at least one of oxygen, ozone, carbon monoxide, and water, preferably an oxygen / water mixed gas, and more preferably an oxygen / water mixed gas with a volume ratio of 1:0.5-2. The present application shows that the use of the oxygen / water mixed gas for the first-stage treatment helps to further combine and synergize with the subsequent gas-phase treatment process, helps to further optimize the interlayer and surface of the graphite, helps to improve the purification effect of the graphite, and is conducive to obtaining graphite with high graphitization degree and tap density.

[0017] In the present application, the temperature T1 can be 430-580℃.

[0018] In the present application, the treatment time of the first-stage treatment is 5-12h, and can be further 6-8h.

[0019] In the present application, after the first-stage treatment, the product can be subjected to a crushing treatment, for example, crushing to D50 not higher than 50μm, and can be further 25-45μm.

[0020] In the present application, the mixture of the one-stage material and the synergistic aid is placed in an atmosphere furnace, subjected to a second-stage heat preservation at the atmosphere B and the temperature T2, and then the atmosphere is switched to the atmosphere C and subjected to a third-stage heat preservation treatment at the temperature T3.

[0021] In the present application, the chloride in the synergistic aid includes one or more of sodium chloride, potassium chloride, lithium chloride, choline chloride, ammonium chloride, tetrapropylammonium chloride, methylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, octadecyltrimethylammonium chloride, and thienyl ethyl ammonium chloride.

[0022] In the present application, the fluoride includes one or more of fluorophosphoric acid, hexafluorophosphoric acid, sodium hexafluorophosphate, ammonium hexafluorophosphate, sodium monofluorophosphate, potassium hexafluorophosphate, lithium hexafluorophosphate, lithium difluorophosphate, hexafluorophosphoric acid, and methylamine hexafluorophosphate.

[0023] In the present application, the weight fraction of the chloride in the synergistic aid is 0.2-5 parts, and can be further 1-3 parts; and the weight fraction of the fluoride is 0.1-20 parts, and can be further 1-2 parts.

[0024] In the present application, the synergistic aid further contains a boron-containing aid, which is one or more of boron oxide, o-benzenesulfonic acid boron, boron trichloride, boron carbide, triethyl boron, boron trichloride, iron boride, magnesium boride, cobalt boride, nickel boride, potassium triethyl borohydride, sodium fluoroborate, fluoroboric acid, ammonium fluoroborate, potassium fluoroborate, lithium tetrafluoroborate, imidazole tetrafluoroborate, and nitro tetrafluoroboric acid.

[0025] The research of the application also shows that the synergistic aid containing the boron aid can further strengthen the purification effect of the graphite, and help to obtain the ultrahigh-purity graphite with more than 6N and more optimal graphitization degree and tap density.

[0026] In the application, the weight part of the boron aid in the synergistic aid is less than or equal to 2 parts, and further is 0.5-2 parts.

[0027] In the application, the weight ratio of the first-stage material to the synergistic aid is 100:0.1-10, and further is 100:0.5-2.

[0028] In the application, the atmosphere B is air or oxygen diluted by a dilution gas; wherein the dilution gas includes at least one of nitrogen and inert gas.

[0029] In the application, the oxygen content of the atmosphere B is 2-5%.

[0030] In the application, T2 can further be 950-1150℃.

[0031] In the application, the time of the second-stage treatment is 5-10h.

[0032] In the application, the second-stage material is subjected to the pressurized treatment under the atmosphere C and the temperature T3, which helps to synergistically strengthen the purification effect of the graphite, and further helps to optimize the physical and chemical structure and the carbon yield, and helps to obtain the ultrahigh-purity graphite with excellent tap density and graphitization degree.

[0033] In the application, the halogenated hydrocarbon in the atmosphere C is 2-3 halogen-substituted methane or 3-5 halogen-substituted ethane. The halogen at least includes F, and further selectively includes Cl.

[0034] In addition to containing the functional gas, the dilution gas is also allowed to exist, and the dilution gas includes at least one of nitrogen and inert gas.

[0035] In the application, the content of the functional gas in the atmosphere C can be 0.002-1%, and further can be 0.01-0.1%.

[0036] In the application, the positive pressure of the third-stage treatment stage is above 1.5atm (atm refers to standard atmospheric pressure), and is preferably 1.5atm-5atm.

[0037] Preferably, the time of the third-stage treatment is 8-12h.

[0038] In the application, after the third-stage treatment is completed, the atmosphere in the atmosphere furnace is switched to the atmosphere D, and then the fourth-stage treatment is performed at the temperature T4 to obtain the ultrahigh-purity graphite with more than 6N.

[0039] The research of the application also shows that, on the basis of the three-stage gas phase treatment, further combining the fourth-stage gas phase treatment and the joint control of temperature and atmosphere can further strengthen the purification effect, and help to further obtain ultra-high purity graphite.

[0040] In the application, the atmosphere D is an atmosphere containing F-containing hydrocarbon gas;

[0041] The temperature T4 is 2600-3000 ℃;

[0042] Preferably, in the atmosphere D, the F-containing hydrocarbon gas is at least a C1-C3 alkane with F and at least one H not being substituted by halogen; the halogen includes F and / or Cl;

[0043] Further, the F-containing hydrocarbon gas is a gas of formula 1;

[0044]

[0045] In formula 1, at least one of R1-R3 is H or a H-containing substituent, and the remaining substituents are halogen, halogen-substituted methylene or halogen-substituted methylene; the halogen is Cl or F. Further, the F-containing hydrocarbon gas is methane or ethane with 1-2 C-H not being substituted by halogen.

[0046] In the atmosphere D, in addition to the F-containing hydrocarbon gas, a dilution gas is also included, the dilution gas including at least one of nitrogen and inert gas. In the atmosphere D, the content of the F-containing hydrocarbon gas is not particularly required, for example, it can be 0.001-0.1 v%, and further can be 0.002-0.005 v%.

[0047] Preferably, the time of the fourth-stage treatment is 12-24 h, and further is 15-20 h.

[0048] The application also includes the 4N or more high-purity graphite prepared by the preparation method.

[0049] The application also provides an application of the 4N or more high-purity graphite prepared by the preparation method, which is used to prepare at least one of high-purity silicon-carbon, nuclear graphite, high-purity silicon carbide and fluorinated graphite.

[0050] In the application, the high-purity graphite can be used to prepare products in higher-purity graphite application scenarios based on existing conventional means.

[0051] The application also provides a product containing the 4N or more high-purity graphite prepared by the preparation method or made of the high-purity graphite.

[0052] Beneficial effects:

[0053] The present application provides a continuous variable gas preparation of high purity graphite, which is through the combination of the first segment to the third segment of the three segment gas phase treatment process, further combined with the atmosphere and temperature parameters of each gas phase treatment, so as to realize the synergy, and the deep purification of graphite can be realized based on the full atmosphere treatment method, and high purity graphite with a purity of 4N or more can be obtained. In addition, the method of the present application can avoid a large amount of three wastes. The present application research also shows that the further combined control of the atmosphere of the first segment treatment, the boron-containing additive and the fourth segment gas phase treatment process can further strengthen the purification effect of graphite.

[0054] The process of the present application is a pure gas phase process, without wastewater, and the waste gas is easy to treat. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 SEM image of the graphite raw material before the treatment of Example 1;

[0056] Figure 2 SEM image of the high purity graphite after the treatment of Example 1 Step Three;

[0057] Figure 3 SEM image of the high purity graphite after the treatment of Example 1 Step Four;

[0058] Figure 4 XRD image of the high purity graphite after the treatment of Example 1 Step Four. DETAILED DESCRIPTION

[0059] The specific steps of the present application are illustrated by the following examples, and it should be understood that these examples are only for illustrating the present application, and do not limit the scope of the present application in any way. Various processes and methods not described in detail in the present application are conventional methods known in the art.

[0060] The graphite raw material of the present application can be any raw material mainly containing graphite, for example, it can be waste graphite recovered from waste batteries.

[0061] In the present application, the graphite content in the waste graphite is not particularly required, but considering the treatment efficiency and effect, it is further preferred to be 95wt.% or more, and further can be 98±1wt.%. In the following cases, as a typical example that can be implemented, the selected graphite raw material refers to the graphite material recovered from waste lithium ion batteries and semiconductor industry, and the graphite purity is 98.2±0.2wt.%.

[0062] The optional waste graphite purification step in the present application includes:

[0063] Step one: Put the graphite raw material into the atmosphere furnace, and introduce the atmosphere A and perform the first stage treatment at temperature T1. Then take out the material and perform the crushing treatment to obtain the first stage material;

[0064] Step two: After mixing the first stage material with the additive uniformly, put it into the atmosphere furnace, introduce the atmosphere B, and perform the second stage treatment by temperature programming to T2 and holding.

[0065] Step three: Then switch the gas in the atmosphere furnace to the atmosphere C, continuously perform the temperature programming to T3, and perform the third stage treatment by pressure holding to obtain the third stage material.

[0066] Optionally, the process further comprises step four: after step three, switch the gas to the atmosphere D, restore the system to the normal pressure, continuously perform the temperature programming to T4, hold, and naturally cool to room temperature to obtain the ultra-high purity graphite.

[0067] The gas A in step one is one or more of oxygen, ozone, carbon monoxide, and water, and is preferably the oxygen / water mixed gas containing water vapor. The pretreatment temperature in step one is 400-600℃, and the holding time is 5-12h. The particle size D50 of the crushed material in step one is not higher than 50μm.

[0068] The additive in step two is the chloride, the fluorine-containing additive, and optionally the boron-containing additive.

[0069] The chloride can be one or more of sodium chloride, potassium chloride, lithium chloride, choline chloride, ammonium chloride, tetrapropylammonium chloride, methylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, octadecyltrimethylammonium chloride, and thienyl ethyl ammonium chloride.

[0070] The fluorine-containing additive can be one or more of fluorophosphoric acid, hexafluorophosphoric acid, sodium hexafluorophosphate, ammonium hexafluorophosphate, sodium monofluorophosphate, potassium hexafluorophosphate, lithium hexafluorophosphate, lithium difluorophosphate, hexafluorophosphoric acid nitrogen, and methylamine hexafluorophosphate.

[0071] The boron-containing additive can be one or more of boron oxide, o-benzene boronic acid boron, boron trichloride, boron carbide, triethyl boron, boron trichloride, iron boride, magnesium boride, cobalt boride, nickel boride, triethyl potassium borohydride, sodium fluoroborate, fluoroboric acid, ammonium fluoroborate, potassium fluoroborate, lithium tetrafluoroborate, imidazole tetrafluoroborate, and nitro tetrafluoroborate.

[0072] In step two, the mass ratio of the first stage material to the chloride is 100:0.2-5, the mass ratio of the first stage material to the fluorine-containing additive is 100:0.1-2, and the mass ratio of the first stage material to the boron-containing additive is 100:0.5-2.

[0073] The temperature increasing rate in step two is 2-10℃ / min, the atmosphere B is a mixture of oxygen and inert gas (nitrogen, argon, helium or one or more of them), wherein the volume fraction of oxygen is 2-5%; the holding temperature is 900-1200℃, and the holding time is 5-10h.

[0074] In step three, the atmosphere C is one or more of chlorine, fluorine and halogenated hydrocarbon, with a volume fraction of 0.002-1%, and the rest is inert gas; the temperature increasing rate is 2-5℃ / min, the system pressure is 1.2-3atm, the holding temperature is 1300-1700℃, and the holding time is 8-12h.

[0075] In step four, the atmosphere D is F-containing hydrocarbon gas, with a volume fraction of 0.001-0.01%, and the rest is inert gas; the temperature increasing rate is 2-5℃ / min, the holding temperature is 2600-3000℃, and the holding time is 12-24h.

[0076] The following are specific embodiments:

[0077] Example 1

[0078] Step one: put the graphite raw material into an atmosphere furnace, introduce gas A (oxygen in this case) and hold at temperature T1 (450±10℃ in this case) for 8h, then crush to D50 of 30.5μm to obtain a first-stage material;

[0079] Step two: mix the first-stage material with an additive uniformly, then put into an atmosphere furnace, introduce gas B (3v% oxygen-Ar mixed gas), and increase the temperature to T2 (1000℃±20℃) at a rate of 5℃ / min, and hold for 8h; the additive includes chloride (choline chloride) and fluoride (fluorophosphoric acid) at a weight ratio of 1:1; the weight ratio of the first-stage material and the additive is 100:0.5;

[0080] Step three: after the treatment in step two, switch the atmosphere to gas C (0.01v% F2-Ar mixed gas), increase the temperature to T3 (1400℃±20℃) at a rate of 5℃ / min, and hold for 10h under a pressure of 2atm; obtain a third-stage material;

[0081] Step four: after step three, switch the atmosphere to gas D (0.005v% formula A -Ar mixed gas), and restore the pressure in the atmosphere furnace to normal pressure, increase the temperature to T4 (2700℃±50℃) at a rate of 5℃ / min, and hold for 20h; naturally cool to room temperature to obtain ultra-high purity graphite.

[0082] In the present application, the graphite purity of the three-section material is 99.994% (4N grade), and the purity of the ultra-high purity graphite of step four is 99.99992% (6N grade). The further effects of the prepared graphite are shown in Table 1.

[0083] Example 2

[0084] Compared with Example 1, the difference is only that the conditions of step one are changed, and the experimental groups are as follows:

[0085] Group A: atmosphere A is water vapor atmosphere;

[0086] Group B: atmosphere A is water vapor-oxygen mixed gas with a volume ratio of 1:1;

[0087] Group C: temperature T1 is 550℃±10℃, the holding time is 6h, and the D50 of the broken material after holding is 41.5μm.

[0088] The other operations and parameters are the same as those of Example 1.

[0089] Example 3

[0090] Compared with Example 1, the difference is only that the conditions of step two are changed, and the experimental groups are as follows:

[0091] Group A: the chloride in the auxiliary agent is sodium chloride, the fluoride is hexafluorophosphoric acid; the weight ratio of chloride and fluoride is 2:1; the weight ratio of the first section material and the auxiliary agent is 100:1;

[0092] Group B: the auxiliary agent also contains a boron-containing auxiliary agent (boron oxide), wherein the weight ratio of chloride, fluoride, and boron-containing auxiliary agent is 1:1:1; the weight ratio of the first section material and the auxiliary agent is 100:0.5;

[0093] Group C: the auxiliary agent includes tetraethylammonium chloride (chloride), sodium fluoroborate (boron compound), and potassium hexafluorophosphate (fluoride) with a mass ratio of 1:1:1.

[0094] Group D: atmosphere B is 4% oxygen-Ar atmosphere, wherein the temperature T2 is (1100℃±20℃), and the holding time is 6h;

[0095] The other operations and parameters are the same as those of Example 1.

[0096] Example 4

[0097] Compared with Example 1, the difference is only that the conditions of step three are changed, and the experimental groups are as follows:

[0098] Group A: atmosphere C is 0.1v% chlorine-Ar mixed gas, T3 is 1500±20℃, the holding pressure is 3atm, and the holding time is 5h;

[0099] Group B: atmosphere C is 0.05v% halogenated hydrocarbon (mixture of formula A-Ar gas, and T3 is 1600±20℃, holding pressure is 2atm, holding time is 6h;

[0100] Other operations and parameters are the same as example 1.

[0101] Example 5

[0102] Compared with example 1, the only difference is that the condition of step four is changed, and the experimental groups are respectively:

[0103] Step four: after step three, the atmosphere is switched to gas D (0.003v% mixture of formula B-Ar gas), and the pressure in the atmosphere furnace is restored to normal pressure, and the temperature is raised to T4 (2800℃±50℃) at a rate of 4℃ / min and held for 15h; naturally cooled to room temperature to obtain ultra-high purity graphite.

[0104] Comparative example 1

[0105] Compared with example 1, the only difference is that step one is missing, and the graphite raw material is directly used as the raw material for step two and subsequent processing. Other operations and parameters are the same as example 1.

[0106] Comparative example 2

[0107] Compared with example 1, the only difference is that in step two, the additive is missing. Other operations and parameters are the same as example 1.

[0108] Comparative example 3

[0109] Compared with example 1, the only difference is that in step two, the additive is a single chloride, and the amount of additive and other conditions are the same as example 1. Other operations and parameters are the same as example 1.

[0110] Comparative example 4

[0111] Compared with example 1, the only difference is that in step two, the additive is a single fluoride, and the amount of additive and other conditions are the same as example 1. Other operations and parameters are the same as example 1.

[0112] Comparative example 5

[0113] Compared with example 1, the only difference is that step three is missing. Other operations and parameters are the same as example 1.

[0114] Comparative example 6

[0115] Compared with example 1, the only difference is that in step three, the pressure in the processing stage is normal pressure. Other operations and parameters are the same as example 1.

[0116] The results of each example are shown in Table 1;​

[0117] Table 1

[0118]

[0119] The results of each comparative example are shown in Table 2

[0120] Table 2

[0121]

[0122] From Table 1 and Table 2, it can be seen that in each of the embodiments of the present application, 6N-grade ultra-high purity graphite can be obtained, and not only that, it also takes into account the high carbon yield, high graphitization purity and tap density which are difficult to achieve in the industry.

Claims

1. A continuous gas-phase preparation method for high-purity graphite with a purity of 4N or higher, characterized in that, The graphite raw material is pre-treated in atmosphere A and temperature T1 to obtain a first-stage material; the atmosphere A is an oxidizing atmosphere; the temperature T1 is 430~580℃; the atmosphere A contains at least one of oxygen, ozone, carbon monoxide and water; the graphite raw material has a graphite content of more than 95wt.%. After mixing the first-stage material and synergistic additives, the mixture is placed in an atmosphere furnace and pre-treated in atmosphere B at temperature T2 to obtain the second-stage material. Then, the atmosphere of the atmosphere furnace is switched to atmosphere C and treated in the third stage at temperature T3 and positive pressure to obtain high-purity graphite with 4N or higher. The synergistic agent comprises chloride and fluoride; the atmosphere B is a low-oxygen atmosphere with an oxygen content of less than 10v%; and the temperature T2 is 900~1200℃. In the aforementioned synergistic agent, the chloride includes one or more of sodium chloride, potassium chloride, lithium chloride, choline chloride, ammonium chloride, tetrapropylammonium chloride, methylammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, octadecyltrimethylammonium chloride, and thiophene ethylammonium chloride; the fluoride includes one or more of fluorophosphate, hexafluorophosphate, sodium hexafluorophosphate, ammonium hexafluorophosphate, sodium monofluorophosphate, potassium hexafluorophosphate, lithium hexafluorophosphate, lithium difluorophosphate, nitrogen hexafluorophosphate, and methylamine hexafluorophosphate. In the synergistic additive, the chloride is present in parts by weight of 0.2 to 5 parts, and the fluoride is present in parts by weight of 0.1 to 20 parts; Atmosphere B is air or oxygen diluted with a dilution gas; wherein the dilution gas includes at least one of nitrogen and an inert gas; the oxygen content of atmosphere B is 2-5%; The atmosphere C is a functional gas containing at least one of chlorine, fluorine, and halogenated hydrocarbons, and the temperature T3 is 1300~1700℃; In the atmosphere C, the halohydrocarbon is methane with 2 to 3 halogen substitutions or ethane with 3 to 5 halogen substitutions; the halogens include at least F and selectively include Cl. In atmosphere C, the content of functional gas is 0.002~1%.

2. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The graphite raw materials include waste graphite materials separated from waste batteries and waste semiconductors.

3. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, Atmosphere A is an oxygen / water mixture.

4. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The processing time for the first stage is 5-12 hours.

5. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The synergistic agent also includes a boron-containing agent.

6. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 5, characterized in that, The boron-containing additive is one or more of the following: boron oxide, boron o-phenylborate, boron trichloride, boron carbide, triethylboron, boron trichloride, iron boride, magnesium boride, cobalt boride, nickel boride, potassium triethylboroide, sodium fluoroborate, fluoroboric acid, ammonium fluoroborate, potassium fluoroborate, lithium tetrafluoroborate, imidazole tetrafluoroborate, and nitric tetrafluoroborate.

7. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 5, characterized in that, In the synergistic additives, the weight parts of boron-containing additives are less than or equal to 2 parts.

8. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 7, characterized in that, In the synergistic additives, the boron-containing additives account for 0.5 to 2 parts by weight.

9. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The weight ratio of primary material to synergistic additive is 100:0.1~10.

10. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The second stage of processing takes 5-10 hours.

11. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The positive pressure in the third treatment stage is above 1.5 atm.

12. The continuous gas-phase preparation method of high-purity graphite with a purity of 4N or higher as described in claim 11, characterized in that, The positive pressure in the third treatment stage is 1.5 atm to 5 atm.

13. The continuous gas-phase preparation method for high-purity graphite of 4N or higher as described in claim 1, characterized in that, The third stage of processing takes 8-12 hours.

14. The continuous gas-phase preparation method of high-purity graphite with a purity of 4N or higher as described in any one of claims 1 to 13, characterized in that, After the third stage of processing is completed, the process also includes switching the atmosphere in the atmosphere furnace to atmosphere D, and then performing the fourth stage of processing at temperature T4 to obtain ultra-high purity graphite with a purity of 6N or higher. The atmosphere D is an atmosphere containing hydrocarbon gases containing F; The temperature T4 is 2600~3000℃.

15. The continuous gas-phase preparation method of high-purity graphite with a purity of 4N or higher as described in claim 14, characterized in that, In the atmosphere D, the F-containing hydrocarbon gas is a C1-C3 alkane containing at least F and at least one H that is not substituted by a halogen; the halogen includes F and / or Cl.

16. The continuous gas-phase preparation method of high-purity graphite with a purity of 4N or higher as described in claim 14, characterized in that, The processing time for the fourth stage is 12-24 hours.

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