CN105883780B - A kind of method for preparing high-purity crystalline flake graphite - Google Patents
A kind of method for preparing high-purity crystalline flake graphite Download PDFInfo
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- CN105883780B CN105883780B CN201510930224.7A CN201510930224A CN105883780B CN 105883780 B CN105883780 B CN 105883780B CN 201510930224 A CN201510930224 A CN 201510930224A CN 105883780 B CN105883780 B CN 105883780B
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Abstract
The invention discloses a kind of method of purification of high-purity crystalline flake graphite, using graphite powder of the carbon content more than 90% as raw material powder, it is added to together with watery hydrochloric acid in reactor, heating stirring, dipping 2~3 hours, then with quality is 1:2.8~3 sodium hydroxide solution is added in reactor together, and heating is stirred simultaneously, impregnation；Then it is 100 in mass ratio by crude product two and sodium chloride：1~5 proportioning mixing, is then dried, and is transferred to graphite crucible, under the protection of pressure-fired nitrogen, is warming up to 1,000 1200 DEG C, is incubated 1 3h, naturally cools to room temperature, then is warming up to 2200~2600 DEG C, is incubated 6~10min, is obtained final high-purity crystalline flake graphite.The crystalline flake graphite of phosphorus content 90% can be purified to 99.9933 99.9955% or so by purifying technique of the present invention, greatly improve the technology content and application of crystalline flake graphite.
Description
Technical field
The present invention relates to a kind of method for purifying crystalline flake graphite.
Technical background
The phosphorus content of natural scale (crystalloid) graphite is 70%-90%, up to 99.9%, because it is shaped as squamous,
Therefore claim crystalline flake graphite.Crystalline flake graphite is high compared with cryptocrystalline (earthy) graphite phosphorus content, ash content is few, conductive, heat conduction, antioxygenic property are good
It is very extensive etc. application, and most common lithium cell cathode material at present.Therefore, the prospect of exploitation purification crystalline flake graphite
It is boundless.The crystalline flake graphite purification technique of environmental protection and energy saving will significantly lift China's graphite industry deep process technology level, make
China's crystalline flake graphite Industry Foundation research and development ability, production technology etc. are China's graphite green wood close to or up international most advanced level
Expect that industrial strategy sexual development provides important support.Crystalline flake graphite purifies, and has chemical method, a high temperature venting method, but for general technology,
Both complicated equipment, cost height be present, substantial pollution is caused to environment.
It is concentrated mainly at present for the purifying technique of crystalline flake graphite, Feng Qiyun etc. is fixed using the purification of high-temperature alkali calcination method
The aphanitic graphite powder of carbon content 85.60%, the results showed that carbon content is fixed after purification up to 97.86%.Li little Bo etc. is used
Acid-base method (high-temperature melting method) has carried out purifying research to aphanitic graphite, the results showed that carbon content is fixed in raw ore is
The graphite products that it is 97.65% for fixed carbon content that 79.82% cryptocrystalline, which is purified, test repeatability is good, and product quality is steady
It is fixed.It is but also relatively difficult at present when purity needs further to improve.
The content of the invention
It is an object of the invention to provide a kind of technique for purifying high-purity crystalline flake graphite, by the technique by the pure of crystalline flake graphite
Degree brings up to 99.9933% or so by 90%, efficiently solves the purification problem of high-purity crystalline flake graphite.The technique of the present invention
Including：
1) using graphite powder of the carbon content more than 90% as raw material powder, it is added in reactor, is heated to together with watery hydrochloric acid
50-60 DEG C, while be stirred, impregnation 2~3 hours, with centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried
It is dry, obtain crude product one；Described raw material powder and the mass ratio of watery hydrochloric acid are 1：2.5~3；
2) crude product one is added in reactor together with sodium hydroxide solution, concentration of sodium hydroxide solution be 2.5~
The quality of 3mol/L, crude product one and sodium hydroxide is 1:2.8~3,50-60 DEG C is heated to, while be stirred, impregnation
2-3 hours, with centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dries, obtain crude product two；
3) sodium chloride is first dissolved as the aqueous solution that concentration is 50~55%, crude product two and sodium chloride is then pressed into quality
Than for 100：1~5 proportioning mixing, then dries to obtain crude product three；
4) crude product three is transferred to graphite crucible, be placed in reacting furnace, pressure-fired, under nitrogen protection, be warming up to 1000-
1200 DEG C, 1-3h is incubated, room temperature is naturally cooled to, obtains crude product four；
5) crude product four is loaded into graphite crucible, inserted in reacting furnace, be warming up to 2200~2600 DEG C, insulation 6~
10min, obtain final high-purity crystalline flake graphite.
The granularity of the graphite powder is 30~40 μm.
The effect of 1000-1200 DEG C of heat treatment includes：(1) a part of impurity is removed；(2) this temperature range sodium chloride with
Impurity in graphite forms chelate, reduces the boiling point of metal oxide, it is volatilized at 2200-2600 DEG C.
The impurity removed between 1000 DEG C of heat treatment mainly includes：Sulphur, nitrogen and oxygen.
The impurity removed between heat treatment mainly includes：Iron, lead, aluminium, sodium, silicon, zinc, arsenic, chromium, copper, manganese, magnesium, molybdenum, vanadium,
Cobalt, potassium, nickel, phosphorus, cadmium, tin, barium, calcium and ash content.
The purity of the purificant being made up of sodium-chloride water solution, wherein sodium chloride is 99.5 Nacls, analyzes pure salt (%),
Solvent is distilled water.
1000 DEG C of heat treatment steps：Sample after mixing to be inserted in heat-treatment furnace, regulation heating rate is 5 DEG C/min,
1000 DEG C are warming up under nitrogen atmosphere protection, soaking time 1-3h, sample cools to room temperature with the furnace.At 2200-2600 DEG C of heat
Manage step：Sample after previous step is heat-treated is inserted in continuous horizontal type high temperature graphitization stove, soaking time 6-10min,
Released with stove and naturally cool to room temperature.
This technique for preparing high-purity crystalline flake graphite of the present invention need not be passed through chlorine or freon, so required
Equipment is simple, and cost is low, and this technique does not pollute to environment, is that a kind of to be easily achieved preparing for industrialized production high-purity
The inventive method of crystalline flake graphite.Using purifying technique involved in the present invention, can effectively by the purity of crystalline flake graphite by
90% or so brings up to 99.9933-99.9955% or so.The process of the present invention can be used for industrial production and prepare height
Pure crystalline flake graphite, so as to solve problem prepared by China's high-purity crystalline flake graphite production.
Brief description of the drawings
Fig. 1 crystalline flake graphite purifying technique SEM image results figures；
Fig. 2 are graphite powder XRD material phase analysis figures before purification；
Fig. 3 are graphite powder XRD material phase analysis figures after purification.
Embodiment
The present invention is further described below with reference to specific embodiment.It is it will be appreciated by those skilled in the art that following
Exemplified embodiment is only used for explaining that the present invention makes any restrictions not for it.Such as：Each step described below
Rapid order is simultaneously not exclusive and unmodifiable, as long as it meets normal logical order and can implement the present invention.
Embodiment 1
Crystalline graphite powder is added in reactor together with watery hydrochloric acid, is heated to 50-60 DEG C, while be stirred, soak
Stain reacts 2-3 hours.Using centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product is molten with sodium hydroxide
Liquid is added in reactor together, is heated to 50-60 DEG C, while is stirred, impregnation 2-3 hours.Will using centrifuge
Separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product and sodium-chloride water solution are pressed 99:1 proportioning mixes, and inserts heat
Handle in reacting furnace, heating rate be 5 DEG C/min, and nitrogen does protection gas, and system is warming up to 1000 DEG C, insulation 1-3h, sample with
Stove is cooled to room temperature taking-up；Sample after previous step is handled inserts the continuous horizontal type pyrographite that in-furnace temperature is 2200 DEG C
Change in stove, soaking time 6-10min, released with stove and naturally cool to room temperature.Crystalline flake graphite purity after the PROCESS FOR TREATMENT
For：99.942%.
Embodiment 2
Crystalline graphite powder is added in reactor together with watery hydrochloric acid, is heated to 50-60 DEG C, while be stirred, soak
Stain reacts 2-3 hours.Using centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product is molten with sodium hydroxide
Liquid is added in reactor together, is heated to 50-60 DEG C, while is stirred, impregnation 2-3 hours.Will using centrifuge
Separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product and sodium-chloride water solution are pressed 97:3 proportioning mixes, and inserts heat
Handle in reacting furnace, heating rate be 5 DEG C/min, and nitrogen does protection gas, and system is warming up to 1000 DEG C, insulation 1-3h, sample with
Stove is cooled to room temperature taking-up；Sample after previous step is handled inserts the continuous horizontal type pyrographite that in-furnace temperature is 2200 DEG C
Change in stove, soaking time 6-10min, released with stove and naturally cool to room temperature.Crystalline flake graphite purity after the PROCESS FOR TREATMENT
For：99.966%.
Embodiment 3
Crystalline graphite powder is added in reactor together with watery hydrochloric acid, is heated to 50-60 DEG C, while be stirred, soak
Stain reacts 2-3 hours.Using centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product is molten with sodium hydroxide
Liquid is added in reactor together, is heated to 50-60 DEG C, while is stirred, impregnation 2-3 hours.Will using centrifuge
Separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product and sodium-chloride water solution are pressed 95:5 proportioning mixes, and inserts heat
Handle in reacting furnace, heating rate be 5 DEG C/min, and nitrogen does protection gas, and system is warming up to 1000 DEG C, insulation 1-3h, sample with
Stove is cooled to room temperature taking-up；Sample after previous step is handled inserts the continuous horizontal type pyrographite that in-furnace temperature is 2200 DEG C
Change in stove, soaking time 6-10min, released with stove and naturally cool to room temperature.Crystalline flake graphite purity after the PROCESS FOR TREATMENT
For：99.910%.
Embodiment 4
Crystalline graphite powder is added in reactor together with watery hydrochloric acid, is heated to 50-60 DEG C, while be stirred, soak
Stain reacts 2-3 hours.Using centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product is molten with sodium hydroxide
Liquid is added in reactor together, is heated to 50-60 DEG C, while is stirred, impregnation 2-3 hours.Will using centrifuge
Separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product and sodium-chloride water solution are pressed 99:1 proportioning mixes, and inserts heat
Handle in reacting furnace, heating rate be 5 DEG C/min, and nitrogen does protection gas, and system is warming up to 1000 DEG C, insulation 1-3h, sample with
Stove is cooled to room temperature taking-up；Sample after previous step is handled inserts the continuous horizontal type pyrographite that in-furnace temperature is 2600 DEG C
Change in stove, soaking time 6-10min, released with stove and naturally cool to room temperature.Crystalline flake graphite purity after the PROCESS FOR TREATMENT
For:99.9933%.
Embodiment 5
Crystalline graphite powder is added in reactor together with watery hydrochloric acid, is heated to 50-60 DEG C, while be stirred, soak
Stain reacts 2-3 hours.Using centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product is molten with sodium hydroxide
Liquid is added in reactor together, is heated to 50-60 DEG C, while is stirred, impregnation 2-3 hours.Will using centrifuge
Separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product and sodium-chloride water solution are pressed 97:3 proportioning mixes, and inserts heat
Handle in reacting furnace, heating rate be 5 DEG C/min, and nitrogen does protection gas, and system is warming up to 1000 DEG C, insulation 1-3h, sample with
Stove is cooled to room temperature taking-up；Sample after previous step is handled inserts the continuous horizontal type pyrographite that in-furnace temperature is 2600 DEG C
Change in stove, soaking time 6-10min, released with stove and naturally cool to room temperature.Crystalline flake graphite purity after the PROCESS FOR TREATMENT
For:99.9955%.
Embodiment 6
Crystalline graphite powder is added in reactor together with watery hydrochloric acid, is heated to 50-60 DEG C, while be stirred, soak
Stain reacts 2-3 hours.Using centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product is molten with sodium hydroxide
Liquid is added in reactor together, is heated to 50-60 DEG C, while is stirred, impregnation 2-3 hours.Will using centrifuge
Separation of solid and liquid, filter cake is washed to neutrality, dried.Crude product and sodium-chloride water solution are pressed 95:5 proportioning mixes, and inserts heat
Handle in reacting furnace, heating rate be 5 DEG C/min, and nitrogen does protection gas, and system is warming up to 1000 DEG C, insulation 1-3h, sample with
Stove is cooled to room temperature taking-up；Sample after previous step is handled inserts the continuous horizontal type pyrographite that in-furnace temperature is 2600 DEG C
Change in stove, soaking time 6-10min, released with stove and naturally cool to room temperature.Crystalline flake graphite purity after the PROCESS FOR TREATMENT
For:99.9912%.
Fig. 1 is crystalline flake graphite purifying technique SEM image results.A, b, c are respectively 90% original powder of fixed carbon content in figure
Last pattern, NaCl melting coated graphite powder after powder morphology and high temperature purification after graphite powder pattern, by scheme a can be seen that squama
Piece graphite wafer type is sheet, and crystalline size is about 10 to 50 microns.Scheme b in crystalline flake graphite melting coat sodium chloride after,
Habit becomes more round and smooth, and sodium chloride is coated on graphite particle surface so that graphite particle surface shows brilliant white.Figure
C is the graphite powder after 2800 DEG C of high temperature purifications, and after high temperature purification, graphite powder degree of graphitization improves, and graphite platelet structure is brighter
Aobvious, simultaneously because impurity component vaporization is overflowed, graphite Powder Particle Size slightly reduces.It is impurity during high temperature purification to scheme d, e, f, g
Several typical ways separated out among from graphite flake layer, figure d show anti-with carbon during impurity element (predominantly Si and Fe) high temperature
Carbide should be formed, while is gradually separated out from graphite platelet structure, the crystalline substance as shown in figure e is then formed on graphite particle surface
Body structure, while there are some impurity to be separated out in the form of carbide nanometer line.It is miscellaneous in the higher region of impurity content as schemed shown in f
Prime element (Si, Fe, Ti, O etc.) reacts with neighbouring carbon so that pit occurs in graphite powder particle surface.Graphite in Fig. 1 (g)
There are many spherical particles in powder particles surface, and particle surface has some micropores, mainly impurity element and sodium chloride pyroreaction
The chloride formed afterwards is in gaseous form caused by indigenous graphite particle top layer.
Fig. 2 is graphite powder XRD material phase analysis figures before purification.Major impurity is in 90% fixation carbon content graphite powder before purification
CaAlSi phases, common this silicate are anorthite, AlZr high temperature alloys phase and AlZrSi ternary phases.In addition, also
There are some micro pig iron ore deposits (FeSiC), the stable phase that the element such as Fe3C, SiC and carbon silicon zirconium is formed.
Fig. 3 is the graphite composite powder XRD that purity is 99.9955% carbon content after purifying.As seen from the figure, by 2800
DEG C, after the purification of 3%NaCl techniques, for (002), (004) diffraction maximum for graphite crystal, peak intensity significantly increases, explanation
Crystal structure of graphite is more complete, and crystallinity is higher, i.e., degree of graphitization is higher.To with impurities phase for, many diffraction maximums disappear
Lose, illustrate in purification process, these impurity gasify volatilization in high temperature.
Claims (4)
1. a kind of high-purity crystalline flake graphite purifying technique, it is characterised in that comprise the following steps：
1) using graphite powder of the carbon content more than 90% as raw material powder, it is added to together with watery hydrochloric acid in reactor, is heated to 50-60
DEG C, while it is stirred, impregnation 2~3 hours, with centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dries, obtains
To crude product one；Described raw material powder and the mass ratio of watery hydrochloric acid are 1：2.5~3；
2) crude product one is added in reactor together with sodium hydroxide solution, concentration of sodium hydroxide solution is 2.5~3mol/
The mass ratio of L, crude product one and sodium hydroxide is 1:2.8~3,50-60 DEG C is heated to, while be stirred, impregnation 2-3
Hour, with centrifuge by separation of solid and liquid, filter cake is washed to neutrality, dries, obtains crude product two；
3) sodium chloride is first dissolved as the aqueous solution that concentration is 50~55%, is then in mass ratio with sodium chloride by crude product two
100：1~5 proportioning mixing, then dries to obtain crude product three；
4) crude product three is transferred to graphite crucible, be placed in reacting furnace, pressure-fired, under nitrogen protection, be warming up to 1000-1200
DEG C, 1-3h is incubated, room temperature is naturally cooled to, obtains crude product four；
5) crude product four is loaded into graphite crucible, inserted in reacting furnace, be warming up to 2200~2600 DEG C, be incubated 6~10min, obtain
To final high-purity crystalline flake graphite.
2. high-purity crystalline flake graphite purifying technique according to claim 1, it is characterized in that：The granularity of the graphite powder be 30~
40μm。
3. high-purity crystalline flake graphite purifying technique according to claim 1, it is characterised in that：Step 1) the watery hydrochloric acid it is dense
Spend for 1.5~2mol/L.
4. high-purity crystalline flake graphite purifying technique according to claim 1, it is characterised in that：During the centrifuge separation of solid and liquid
Rotating speed be 10000~12000r/min.
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| CN108101049B (en) * | 2017-02-27 | 2020-04-17 | 苏州鼎烯聚材纳米科技有限公司 | Production process of high-temperature ablation resistant graphite nano powder |
| CN108163850B (en) * | 2017-12-22 | 2021-07-13 | 郑州中南杰特超硬材料有限公司 | Preparation method of carbon source for synthesizing large-scale polycrystalline diamond |
| CN109336104A (en) * | 2018-11-23 | 2019-02-15 | 北京航空航天大学 | A kind of low temperature graphite purification method |
| CN111751311B (en) * | 2020-07-03 | 2021-09-28 | 中南大学 | Preparation method of graphite material for oxygen-nitrogen-hydrogen analyzer |
| CN112700902A (en) * | 2020-11-20 | 2021-04-23 | 中核北方核燃料元件有限公司 | Method for treating waste graphite crucible |
| CN112473560B (en) * | 2020-12-01 | 2022-11-01 | 四川久纳新材料有限公司 | Method for improving diamond conversion rate in production of polycrystalline diamond by explosion method |
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