CN117550594A - Purification method of high-purity graphite - Google Patents
Purification method of high-purity graphite Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 147
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 112
- 239000010439 graphite Substances 0.000 title claims abstract description 112
- 238000000034 method Methods 0.000 title claims abstract description 76
- 238000000746 purification Methods 0.000 title claims abstract description 36
- 239000002253 acid Substances 0.000 claims abstract description 64
- 239000003513 alkali Substances 0.000 claims abstract description 63
- 238000005406 washing Methods 0.000 claims abstract description 54
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 41
- 238000002386 leaching Methods 0.000 claims abstract description 34
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 34
- 230000004927 fusion Effects 0.000 claims abstract description 26
- 239000012265 solid product Substances 0.000 claims abstract description 25
- 238000001035 drying Methods 0.000 claims abstract description 13
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 239000007788 liquid Substances 0.000 claims abstract description 4
- 238000010438 heat treatment Methods 0.000 claims description 30
- 239000000047 product Substances 0.000 claims description 26
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 239000002002 slurry Substances 0.000 claims description 22
- 239000002994 raw material Substances 0.000 claims description 18
- 238000002844 melting Methods 0.000 claims description 15
- 230000008018 melting Effects 0.000 claims description 15
- 230000008878 coupling Effects 0.000 claims description 14
- 238000010168 coupling process Methods 0.000 claims description 14
- 238000005859 coupling reaction Methods 0.000 claims description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 12
- 238000002156 mixing Methods 0.000 claims description 9
- 238000009792 diffusion process Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- 238000013019 agitation Methods 0.000 claims description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 2
- 239000006185 dispersion Substances 0.000 claims description 2
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 2
- 239000000243 solution Substances 0.000 claims 5
- 239000012670 alkaline solution Substances 0.000 claims 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 abstract description 20
- 239000002585 base Substances 0.000 abstract description 11
- 238000003756 stirring Methods 0.000 abstract description 8
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 abstract description 5
- 229910017604 nitric acid Inorganic materials 0.000 abstract description 5
- 239000002699 waste material Substances 0.000 abstract description 4
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 abstract description 3
- 229910002651 NO3 Inorganic materials 0.000 abstract description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052731 fluorine Inorganic materials 0.000 abstract description 3
- 239000011737 fluorine Substances 0.000 abstract description 3
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 16
- 230000008569 process Effects 0.000 description 16
- 239000012535 impurity Substances 0.000 description 13
- 239000000463 material Substances 0.000 description 8
- 238000005188 flotation Methods 0.000 description 5
- 230000007935 neutral effect Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000010907 mechanical stirring Methods 0.000 description 4
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 238000005265 energy consumption Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007123 defense Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000007499 fusion processing Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000012264 purified product Substances 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- QZPSXPBJTPJTSZ-UHFFFAOYSA-N aqua regia Chemical compound Cl.O[N+]([O-])=O QZPSXPBJTPJTSZ-UHFFFAOYSA-N 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000013401 experimental design Methods 0.000 description 1
- 239000002783 friction material Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000003566 sealing material Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052604 silicate mineral Inorganic materials 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Classifications
-
- 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
Landscapes
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Inorganic Chemistry (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
The invention discloses a purification method of high-purity graphite, which comprises the steps of adding an alkali solution into high-carbon graphite with fixed carbon content of more than 94%, stirring, drying, and then placing into a muffle furnace for high-temperature alkali fusion; cooling, scattering and washing the alkali fusion with a furnace after the alkali fusion is finished, and collecting a solid product I; preparing a strong acid solution which does not contain hydrofluoric acid and nitric acid, and placing the solid product I in the solution for acid leaching under certain conditions; and washing and drying after the acid leaching is finished to obtain the high-purity graphite. The purification method of the invention does not contain hydrofluoric acid and nitric acid, so that the waste residues and waste liquid do not contain fluorine or nitrate, is environment-friendly, meets the ecological environment-friendly requirement, greatly reduces the acid-base consumption and water consumption in the purification process, reduces the production cost, has wide application prospect, and is suitable for industrial popularization.
Description
Technical Field
The invention belongs to the field of graphite purification, and particularly relates to a method for purifying high-purity graphite by fluorine-free and nitrate-free alkali melt acid leaching.
Background
Graphite is an allotrope of carbon, is a gray black opaque solid, has stable chemical property, is corrosion-resistant, and is not easy to react with agents such as acid, alkali and the like. In the prior art, graphite can be used for producing refractory materials, conductive materials, wear-resistant materials, lubricants, high-temperature-resistant sealing materials, corrosion-resistant materials, heat insulation materials, adsorption materials, friction materials, radiation-proof materials and the like, and the materials are widely applied to metallurgy, petrochemical industry, mechanical industry, electronic industry, nuclear industry, national defense and the like. However, in fields including high-end equipment manufacturing, new energy, new materials, nuclear power, aerospace, military industry and the like, high-purity graphite with a fixed carbon content of 99.95% or more is required, and becomes a key raw material of the emerging industry. Therefore, the purification preparation of high purity graphite is one of the research hotspots in the field.
The graphite purification is a complex physical and chemical process, and the purification methods in the prior art mainly comprise a flotation method, a hydrofluoric acid method, a chloridizing roasting method, a high-temperature method and an alkali acid method.
Flotation method: the method has the greatest advantages that the energy consumption and the reagent consumption are the least in all purification schemes, and the cost is the lowest, but silicate minerals and compounds of elements such as potassium, calcium, sodium, magnesium, aluminum and the like which are mixed in graphite flakes in a superfine state cannot be dissociated by a grinding method, and the method is unfavorable for protecting the graphite flakes. Thus, flotation is the primary means of graphite purification, and other methods must be used to obtain high carbon graphite with carbon content above 99%.
Hydrofluoric acid method: the main process is that graphite and hydrofluoric acid are mixed, the hydrofluoric acid reacts with impurities for a period of time to generate soluble substances or volatile matters, the impurities are removed by washing, and the purified graphite is obtained after dehydration and drying. The hydrofluoric acid method for purifying graphite has the advantages of simple process flow, high product grade, relatively low cost and small influence on the performance of graphite products. However, hydrofluoric acid is extremely toxic, and has to have safety protection measures in the use process, and the generated wastewater can be discharged outwards after being treated, otherwise, the environment is seriously polluted.
Chloridizing roasting method: mixing graphite and a certain reducing agent, roasting at high temperature in specific equipment and atmosphere, and converting valuable metals in the materials into gas phase or condensed phase metal chlorides which are separated from the rest components, so that the graphite is purified. Impurities in graphite can be decomposed into oxides with higher melting point under the high temperature condition, such as SiO 2 、Al 2 O 3 、Fe 2 O 3 CaO, mgO. After chlorine is introduced into the oxides at a certain temperature and in an atmosphere, the metal oxides react with the chlorine to generate chlorides with lower melting points, so that the chlorides can be gasified and escaped at a lower temperature to realize separation from graphite, and the graphite is purified. The chloridizing roasting method has the advantages of energy saving and high purification efficiency>98 percent) and high recovery rate, but also has the problems of chlorine toxicity, serious corrosiveness, serious environmental pollution and the like.
High-temperature purification method: the melting point of graphite is 3850+/-50 ℃, is one of substances with the highest melting boiling point in nature, and is far higher than the boiling point of impurity silicate. And (3) placing graphite into a graphitized graphite crucible by utilizing the difference of melting boiling points of the graphite, and heating to 2700 ℃ by utilizing specific instrument equipment under a certain atmosphere to gasify impurities and escape from the graphite so as to achieve the effect of purification. The technology can purify graphite to more than 99.995%. The quality of the graphite product purified by the high-temperature method is high, which is the biggest characteristic of the high-temperature method, but the method has high energy consumption and extremely high equipment requirement, and only the graphite applied to the high-tech fields of national defense, aerospace, nuclear industry and the like is purified by the method.
Alkali acid method: comprises two reaction processes: an alkali fusion process and an acid leaching process; the alkali fusion process is to utilize alkali in a fusion state and acidic impurities in graphite to carry out chemical reaction under a high temperature condition, especially silicon-containing impurities (such as silicate, aluminosilicate, quartz and the like) to generate soluble salt, and then to wash and remove the impurities, so that the purity of the graphite is improved; the basic principle of the acid leaching process is that acid is utilized to react with metal oxide impurities, the impurities do not react with alkali in the alkali melting process, so that the metal oxide is converted into soluble salt, then the soluble salt is separated from graphite by washing, and the graphite purification effect is better through the combination of alkali melting and acid leaching. The alkali acid method is limited by the fatal problems of difficult removal of colloidal substances such as sodium silicate, silicic acid and the like, poor product quality, instability and the like in the alkali melting and alkali dissolution processes, and has not been widely applied, so how to further promote the method is one of the research and development directions of the technicians in the field. For example, chinese patent application CN114212788A discloses a graphite purification process and graphite, and the purification process of the method adopts an alkaline acid method purification process to obtain a high purity graphite product meeting the requirements, but the method comprises two-stage acid treatment, one-stage alkali treatment and three-stage cleaning, and has the advantages of longer process flow, and larger acid-alkali consumption and water washing consumption. The Chinese patent application CN103449425A discloses a method for preparing high-purity graphite by purifying high-carbon natural crystalline flake graphite by an alkali acid-complexing method, which is based on an alkali acid method purification process comprising alkali fusion, aqua regia dissolution, alkali dissolution, synergistic complexing and other processes, and a high-purity graphite product meeting the requirements is obtained, but the process is multiple, the flow is long, the acid-base consumption and the washing water consumption are high, and nitric acid is contained. The Chinese patent application CN115490230A discloses a graphite high-efficiency alkali acid method purification system and process, which comprises a raw material mixing unit, a graphite alkali melting unit and a chemical purification-washing-dehydration unit which are sequentially connected, so that the problem of high-efficiency continuous production in the purification process of the graphite alkali acid method is solved; however, the method can obtain the high-purity graphite with the fixed carbon content of 99.95 percent only by carrying out water-washing desilication, acid-leaching purification and water-washing impurity removal reaction for a plurality of times, and has the advantages of longer process flow and higher cost.
Therefore, a purification method of high-purity graphite is developed to avoid generating fluorine and nitrate impurities, greatly reduce acid-base consumption and water consumption, save cost and obviously have positive practical significance.
Disclosure of Invention
The invention aims to provide a purification method of high-purity graphite. So as to avoid generating fluorine and nitrate impurities and obtain a high-purity graphite product with fixed carbon content of more than 99.95 percent.
In order to achieve the above purpose, the invention adopts the following technical scheme: the purification method of the high-purity graphite comprises the following steps:
(1) Uniformly mixing a graphite raw material with an alkali solution, drying, and then carrying out alkali fusion;
the temperature range of the alkali fusion is 700-800 ℃, and the alkali fusion time is 1-3 hours;
(2) Cooling and scattering after alkali melting is finished, then performing ultrasonic-heating coupling washing, and collecting after washing to obtain a solid product I;
the ultrasonic-heating coupled washing comprises the following steps: (a) Adding water into the scattered alkali fusion product, and regulating the slurry to 10-30wt% of concentration to obtain slurry; (b) Heating the slurry to 80-100 ℃, and placing the slurry in an ultrasonic diffusion sound field for washing for 10-50 min; (c) Filtering the slurry subjected to ultrasonic washing to obtain a solid product; washing the solid product to neutrality to obtain the solid product I;
(3) Adding acid liquor into the solid product I obtained in the step (2), and carrying out ultrasonic-heating coupling acid leaching;
(4) And washing and drying after the acid leaching is finished to obtain the high-purity graphite.
In the above, the graphite raw material may include flake graphite flotation concentrate, spheroidal graphite, aphanitic graphite flotation concentrate, aphanitic graphite, artificial graphite, etc.; preferably crystalline flake graphite having a D50 of 50 to 150 microns. The fixed carbon content of the graphite starting material is preferably greater than 94%.
The temperature range of the alkali fusion is preferably 720-780 ℃, and the alkali fusion time is 1-2 hours; more preferably 750 ℃.
Preferably, the alkali solution in the step (1) is selected from one or more of sodium hydroxide solution, potassium hydroxide solution and sodium carbonate solution; the mass ratio of the alkali in the alkali solution to the graphite in the graphite raw material is 0.25-1: 1. more preferably 0.25 to 0.5:1.
the alkali solution is preferably sodium hydroxide solution, and the mass concentration is 40-80%.
Preferably, in the step (b) of the step (2), the frequency of the ultrasonic diffuse sound field is 20-40 kHz, and the intensity is 90-360W.
Preferably, the acid solution in the step (3) is hydrochloric acid and/or sulfuric acid. The acid solution of the present invention does not include hydrofluoric acid and nitric acid. Preferably, the mass concentration of the acid solution is 10-20%.
Preferably, the mass ratio of the acid in the acid solution in the step (3) to the graphite in the graphite raw material is 0.3-1: 1. more preferably 0.3 to 0.5:1.
preferably, the ultrasonic-heating coupled acid leaching in the step (3) comprises the following steps: (A) Adding acid liquor into the solid product I to prepare slurry with uniform dispersion; (B) Heating the slurry to 60-90 ℃, and placing the slurry in an ultrasonic diffusion sound field for acid leaching for 2-6 h. The frequency of the ultrasonic diffusion sound field is 20-40 kHz, and the intensity is 90-360W.
Preferably, the washing in step (4) is mechanical agitation washing. The stirring speed is 1000-2000 r/min.
Preferably, the fixed carbon content of the high purity graphite is 99.95% or more.
Preferably, the graphite raw material in the step (1) is flake graphite.
Preferably, the fixed carbon content of the crystalline flake graphite is 94-95.5%.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
1. the invention develops a method for purifying fluorine-free and nitrate-free high-purity graphite, which adopts raw materials without hydrofluoric acid and nitric acid, so that waste residues and waste liquid of the method are fluorine-free and nitrate-free, are environment-friendly, meet the ecological environment-friendly requirement, and have positive practical significance at present with higher and higher environment-friendly requirement.
2. The purification method comprises the steps of one-stage mixed alkali melting, one-stage acid leaching and two-stage washing, has less working procedures and low energy consumption, and particularly has extremely low acid-base consumption and water consumption, thus having lower cost and higher economic value.
3. The two-stage enhanced washing and the one-stage enhanced acid leaching in the invention improve the purification effect, make up for the negative influence caused by the reduction of the types and the consumption of acid liquor and alkali liquor, and finally obtain the high-purity graphite; experiments prove that the fixed carbon content of the finally obtained graphite product exceeds 99.95 percent, and simultaneously, the acid-base consumption and the water consumption in the purification process are greatly reduced, the production cost is low, and the method is suitable for industrial popularization.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that some drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a process flow diagram of example 1 of the present invention.
FIG. 2 is a schematic diagram of an ultrasonic-heating coupled acid leaching apparatus in example 1 of the present invention.
Wherein: 1. a water bath kettle; 2. an ultrasonic probe; 3. an ultrasonic transducer; 4. an ultrasonic regulator.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
Referring to fig. 1, a method for purifying high purity graphite comprises the following steps: weighing 100g of high-carbon flake graphite with a fixed carbon content of 95.46% and a D50 of 100 microns, mixing a proper amount of water and 25g of NaOH, uniformly stirring, drying, and then placing in a muffle furnace for high-temperature alkali melting, wherein the alkali melting temperature is 750 ℃ and the alkali melting time is 1h;
cooling along with a furnace, scattering, performing ultrasonic-heating coupling washing after the alkali melting is completed, and collecting a solid product I;
preparing a strong acid solution with the mass concentration of 20% by taking 30g of concentrated hydrochloric acid, and placing a solid product I in the strong acid solution for ultrasonic-heating coupling acid leaching;
washing in a mechanical stirring device with the stirring speed of 2000r/min after acid leaching is finished, filtering and drying after washing water is neutral, and obtaining the high-purity crystalline flake graphite with the fixed carbon content of 99.961%.
The steps of the ultrasonic-heating coupling washing are as follows: (a) Adding clear water, and pulping the scattered alkali fusion product until the concentration is 20wt%; (b) heating the slurry to 80 ℃; (c) Placing the slurry with constant temperature of 80 ℃ into an ultrasonic diffusion sound field with the frequency of 20kHz and the intensity of 360W for washing for 30min; (d) Filtering the slurry subjected to ultrasonic washing to obtain a solid product; (e) Washing the solid product in step (d) to neutrality of washing water, and collecting the solid product I.
Referring to fig. 2, the steps of the ultrasonic-heating coupled acid leaching are as follows: (i) Adding a proper amount of water into the alkali fusion product to prepare uniformly dispersed slurry; (ii) Placing the beaker with the uniformly dispersed slurry in a water bath kettle 1, heating to 60 ℃, and keeping the temperature constant in the subsequent ultrasonic washing process; (iii) Placing the ultrasonic probe 2 at a position about 1cm below the surface of the slurry liquid, and fixing the ultrasonic transducer 3; (iv) The ultrasonic intensity (ultrasonic frequency was 20kHz, ultrasonic intensity was 180W) and the washing time (4 h) were set, and the ultrasonic regulator 4 was turned on to perform ultrasonic washing.
Comparative example 1
This comparative example is substantially the same as example 1, with the only difference that: the alkali fusion product is not washed by ultrasonic-heating coupling, but is washed to be neutral by clean water. Finally, the crystalline flake graphite with the fixed carbon content of 99.811 percent is obtained.
Comparative example 2
This comparative example is substantially the same as example 1, with the only difference that: the solid product I is not subjected to ultrasonic-heating coupling acid leaching, but is subjected to acid leaching for 4 hours in a standing state. Finally, the crystalline flake graphite with the fixed carbon content of 99.907 percent is obtained.
Comparative example 3
This comparative example is substantially the same as example 1, with the only difference that: after the acid leaching is finished, the washing is not carried out by mechanical stirring, but clear water is washed until the washing water is neutral. Finally, the crystalline flake graphite with the fixed carbon content of 99.953 percent is obtained.
The purified products prepared in example 1 and comparative examples 1, 2 and 3 were subjected to a fixed carbon content test, and the acid, base and water consumption during the purification of examples and comparative examples were counted, and the results are shown in table 1.
TABLE 1
| Example 1 | Comparative example 1 | Comparative example 2 | Comparative example 3 | |
| Fixed carbon content (%) | 99.981 | 99.811 | 99.907 | 99.953 |
| NaOH consumption (kg/t) | 250 | 250 | 250 | 250 |
| HCl consumption (kg/t) | 300 | 300 | 300 | 300 |
| Consumption of water (m) 3 /t) | 18 | 35 | 25 | 22 |
As can be seen from Table 1, the fixed carbon content of the graphite product obtained by the purification of example 1 exceeds 99.95%, reaching 99.961%; the fixed carbon content of the purified graphite products prepared in comparative example 1 and comparative example 2 does not reach the high-purity graphite standard of 99.95%; the purified graphite product prepared in comparative example 3 (without mechanical agitation washing after acid leaching) had a fixed carbon content exceeding 99.95%, but had a greatly increased water consumption and a slightly reduced fixed carbon content.
The alkali fusion product of the comparative example 1 is not subjected to ultrasonic-heating coupling washing, so that the water consumption is obviously increased, and the fixed carbon content of the product is obviously reduced. The solid product I of comparative example 2 was not subjected to ultrasonic-heating coupled acid leaching, the water consumption was increased, and the fixed carbon content of the product was reduced.
It follows that ultrasonic-heating coupled washing and ultrasonic-heating coupled pickling of the alkali fusion product are key processes to ensure low water consumption and high fixed carbon content.
Example 2
The purification method of the high-purity graphite comprises the following steps: weighing 100g of high-carbon spherical graphite with a fixed carbon content of 95.23% and a D50 of 17 micrometers, mixing a proper amount of water and 25g of NaOH, uniformly stirring, drying, placing in a muffle furnace, carrying out high-temperature alkali fusion at a temperature of 750 ℃ for 2 hours, cooling along with the furnace, scattering, and carrying out ultrasonic-heating coupling washing (the specific process parameters are that the pulp mixing concentration of an alkali fusion product is 20wt%, the washing temperature is 90 ℃, the ultrasonic frequency is 20kHz, the ultrasonic intensity is 360W and the washing time is 40 min) after the alkali fusion is completed, and collecting a solid product I;
preparing a strong acid solution with the mass concentration of 20% by taking 40g of concentrated hydrochloric acid, and placing a solid product I in the strong acid solution for ultrasonic-heating coupling acid leaching (the process steps are the same as those of the embodiment 1, and specific process parameters are that the acid leaching temperature is 60 ℃, the ultrasonic frequency is 20kHz, the ultrasonic intensity is 180W, and the acid leaching time is 6 hours); washing in a mechanical stirring device with the stirring speed of 2000r/min after acid leaching is finished, filtering and drying after washing water is neutral, and obtaining the high-purity spherical graphite with the fixed carbon content of 99.983%.
Example 3
The purification method of the high-purity graphite comprises the following steps: weighing 100g of high-carbon aphanitic graphite with a fixed carbon content of 94.07% and a D50 of 0.7 micrometer, mixing a proper amount of water and 50g of NaOH, stirring uniformly, drying, adding into a muffle furnace, carrying out high-temperature alkali fusion at a temperature of 750 ℃ for 2 hours, cooling, scattering and ultrasonic-heating coupling washing along with the furnace after the alkali fusion is finished (the specific technological parameters are that the pulp mixing concentration of an alkali fusion product is 10wt%, the washing temperature is 80 ℃, the ultrasonic frequency is 20kHz, the ultrasonic intensity is 360W and the washing time is 50 min), and collecting a solid product I;
preparing a strong acid solution with the mass concentration of 20% by taking 30g of concentrated hydrochloric acid, and placing a solid product I in the strong acid solution for ultrasonic-heating coupling acid leaching (the process steps are the same as those of the embodiment 1, and specific process parameters are that the acid leaching temperature is 90 ℃, the ultrasonic frequency is 20kHz, the ultrasonic intensity is 180W, and the acid leaching time is 4 hours); washing in a mechanical stirring device with the stirring speed of 2000r/min after acid leaching is finished, filtering and drying after washing water is neutral, and obtaining the high-purity graphite with the fixed carbon content of 99.956%.
The purified products prepared in examples 1 to 3 were each subjected to a fixed carbon content test, and the acid, base, water consumption during purification was counted, and the results are shown in table 2.
TABLE 2
| Example 1 | Example 2 | Example 3 | |
| Raw material D50 | 100 | 17 | 0.7 |
| Fixed carbon content (%) | 99.981 | 99.963 | 99.956 |
| NaOH consumption (kg/t) | 250 | 250 | 500 |
| HCl consumption (kg/t) | 300 | 400 | 300 |
| Consumption of water (m) 3 /t) | 18 | 20 | 30 |
As can be seen from Table 2, the graphite products prepared in example 1, example 2 and example 3 have a fixed carbon content of 99.95% or more. However, from the aspect of material consumption, the granularity of the raw material of the embodiment 1 is larger, and the acid-base consumption and the water consumption are lower; example 2 the particle size of the raw material is reduced, and the acid-base consumption and the water consumption are both increased; example 3 the particle size of the raw material was further reduced and the acid-base consumption and water consumption were both significantly increased. Therefore, on the premise of ensuring that the fixed carbon content of the purified graphite product reaches the standard, the granularity of the raw material has obvious influence on the acid-base consumption and the water consumption in the purification process. In addition, the granularity of the raw materials can influence the purity of the final graphite product, and in certain fields, when the high-purity graphite product is needed, the selection of the high-carbon flake graphite with large granularity has more remarkable effect,
it should be noted that, the preferred purification process conditions in the above embodiments are obtained based on a large number of exploratory experiments and scientific experimental designs of univariate and orthogonal experiments, but the present invention is not limited to the specific details in the above embodiments, and various simple modifications can be made to the technical solutions of the present invention within the scope of the technical concept of the present invention, and all the simple modifications fall within the scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The purification method of the high-purity graphite is characterized by comprising the following steps of:
(1) Uniformly mixing a graphite raw material with an alkali solution, drying, and then carrying out alkali fusion;
the temperature range of the alkali fusion is 700-800 ℃, and the alkali fusion time is 1-3 hours;
(2) Cooling and scattering after alkali melting is finished, then performing ultrasonic-heating coupling washing, and collecting after washing to obtain a solid product I;
the ultrasonic-heating coupled washing comprises the following steps: (a) Adding water into the scattered alkali fusion product, and regulating the slurry to 10-30wt% of concentration to obtain slurry; (b) Heating the slurry to 80-100 ℃, and placing the slurry in an ultrasonic diffusion sound field for washing for 10-50 min; (c) Filtering the slurry subjected to ultrasonic washing to obtain a solid product; washing the solid product to neutrality to obtain the solid product I;
(3) Adding acid liquor into the solid product I obtained in the step (2), and carrying out ultrasonic-heating coupling acid leaching;
(4) And washing and drying after the acid leaching is finished to obtain the high-purity graphite.
2. The method for purifying high purity graphite according to claim 1, wherein the alkaline solution in step (1) is one or more selected from the group consisting of sodium hydroxide solution, potassium hydroxide solution, and sodium carbonate solution; the mass ratio of the alkali in the alkali solution to the graphite in the graphite raw material is 0.25-1: 1.
3. the method for purifying high purity graphite according to claim 1, wherein in the step (b) of the step (2), the ultrasonic diffuse sound field has a frequency of 20 to 40kHz and an intensity of 90 to 360W.
4. The method for purifying high purity graphite according to claim 1, wherein the acid liquid in the step (3) is hydrochloric acid and/or sulfuric acid.
5. The method for purifying high purity graphite according to claim 1, wherein the mass ratio of the acid in the acid solution in the step (3) to the graphite in the graphite raw material is 0.3 to 1:1.
6. the method for purifying high purity graphite according to claim 1, wherein the ultrasonic-heating coupled acid leaching in step (3) comprises the steps of: (A) Adding acid liquor into the solid product I to prepare slurry with uniform dispersion; (B) Heating the slurry to 60-90 ℃, and placing the slurry in an ultrasonic diffusion sound field for acid leaching for 2-6 h.
7. The method for purifying high purity graphite according to claim 1, wherein the washing in step (4) is mechanical agitation washing.
8. The method for purifying high purity graphite according to claim 1, wherein the fixed carbon content of the high purity graphite is 99.95% or more.
9. The method for purifying high purity graphite according to claim 1, wherein the graphite raw material in step (1) is flake graphite.
10. The method for purifying high purity graphite according to claim 9, wherein the fixed carbon content of the flake graphite is 94 to 95.5%.
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| CN117819541A (en) * | 2024-03-04 | 2024-04-05 | 矿冶科技集团有限公司 | Method for purifying graphite by high-temperature drying-free raw materials and simple acid-base method |
| CN117819541B (en) * | 2024-03-04 | 2024-06-04 | 矿冶科技集团有限公司 | Method for purifying graphite by high-temperature drying-free raw materials and simple acid-base method |
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| CN117819541A (en) * | 2024-03-04 | 2024-04-05 | 矿冶科技集团有限公司 | Method for purifying graphite by high-temperature drying-free raw materials and simple acid-base method |
| CN117819541B (en) * | 2024-03-04 | 2024-06-04 | 矿冶科技集团有限公司 | Method for purifying graphite by high-temperature drying-free raw materials and simple acid-base method |
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