GB2068922A - Reutilisation of graphite foil offcuts - Google Patents
Reutilisation of graphite foil offcuts Download PDFInfo
- Publication number
- GB2068922A GB2068922A GB8100669A GB8100669A GB2068922A GB 2068922 A GB2068922 A GB 2068922A GB 8100669 A GB8100669 A GB 8100669A GB 8100669 A GB8100669 A GB 8100669A GB 2068922 A GB2068922 A GB 2068922A
- Authority
- GB
- United Kingdom
- Prior art keywords
- graphite
- foil
- liquid
- particles
- reutilisation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 239000010439 graphite Substances 0.000 title claims abstract description 50
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 50
- 239000011888 foil Substances 0.000 title claims abstract description 35
- 239000002245 particle Substances 0.000 claims abstract description 33
- 239000007788 liquid Substances 0.000 claims abstract description 26
- 238000003801 milling Methods 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims abstract description 4
- 239000000047 product Substances 0.000 claims description 19
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 15
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000007795 chemical reaction product Substances 0.000 claims description 4
- 239000003153 chemical reaction reagent Substances 0.000 claims 1
- 230000006835 compression Effects 0.000 abstract description 3
- 238000007906 compression Methods 0.000 abstract description 3
- 239000011236 particulate material Substances 0.000 abstract 1
- 150000001875 compounds Chemical class 0.000 description 4
- 230000002687 intercalation Effects 0.000 description 4
- 238000009830 intercalation Methods 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 3
- 238000009835 boiling Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 1
- 230000035508 accumulation Effects 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-M hydrogensulfate Chemical compound OS([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-M 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000001117 sulphuric acid Substances 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 238000007669 thermal treatment Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/18—Sealings between relatively-moving surfaces with stuffing-boxes for elastic or plastic packings
- F16J15/20—Packing materials therefor
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
- C04B35/536—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite based on expanded graphite or complexed graphite
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Ceramic Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Carbon And Carbon Compounds (AREA)
- Sealing Material Composition (AREA)
Abstract
Graphite foil which has been produced by compression of expanded graphite particles is converted to a particulate material which can be compressed together to form a reconstituted graphite product of adequate resistance to pressure for it to be commercially useful, by milling the graphite foil, immersing the milled material in a liquid medium and removing the liquid in the form of one or more vapour phase products.
Description
SPECIFICATION
Reutilisation of graphite foil material
This invention relates to a process for the preparation for reutilisation of graphite foils, more especially off-cuts which are obtained in the manufacture of graphite foils.
Graphite foils are thin structures of high flexibility in which graphite particles adhere together. To produce such foils, graphite particles with a good structural arrangement, for example natural graphite flakes are contacted with a medium forming intercalation compounds with graphite and the graphite intercalation compound thus formed is destroyed by rapid heating. On thermal destruction of the intercalation compounds, the graphite particles expand in cushion fashion in a direction perpendicular to the layer planes thereof. Depending on the type of graphite used, the intercalation compound formed and the speed of heating, the volume increase can amount to more than one hundred times the original volume.The expanded graphite particles produced possess irregular contours and may be pressed or rolled together to form thin foils without use of any binder, the particles interlocking with each other to form the foils.
Oxidising agents, for example concentrated nitric acid or hydrogen peroxide, may be used to contact graphite particles in the production of expanded graphite particles. When in contact with an oxidising agent and sulphuric acid, graphite forms for example graphite hydrogen sulphate which is washed to remove surplus acid and is then heated for a few seconds at a temperature in the range of from 600 to 10000C.The expanded graphite particles are rolled together to form thin foils whose thickness usually amounts to from 0.3 to 1.0 mm which indicates that the graphite foils are pressed together almost to the original thickness. This means that when using the foils, for example when cutting out or stamping bands and rings for packings and seals, the waste cuttings which are produced generally exhibit the properties of the starting graphite particles.Hence, only foils or other shaped products which possess very low strength such that they are of no commercial value may be produced from milled off-cuts.
According to the present invention, there is provided a process of preparing, for reutilisation, graphite foil which has been produced by compressing together expanded graphite particles, which comprises milling the foil, immersing the milled foil in a liquid medium or in a number of liquid media used sequentially and removing the liquid or liquids in the form of one or more vapour phase products.
This invention makes it possible to produce commercially usable shaped products, especially graphite foils, from accumulations of previously expanded graphite particles without the need to use any special binder. The shaped products are flexible but possess sufficient strength for many valuable uses.
The particles in the product produced by milling
off-cuts of graphite foil produced by compressing
together previously expanded graphite particles
are in general of plate form with a thickness
corresponding substantially to the original foil
thickness. The width of the particles in the plane
of the plate is preferably from 1 to 5 mm and
although a greater proportion of over and under
size particles hardly affects the capacity of the
milled product for working-up, it may be necessary
under special conditions to separate off coarse
grained constituent parts by sieving. Pin disc mills
are especially suitable for use in the milling and
comminution of foil-form graphite.
A particularly suitable liquid in which the milled
product is dipped is water. However ail liquids and liquid mixtures which possess a comparatively low boiling point, for example organic solvents or acids,
may be used when carrying out the process of the invention. The milled product is immersed in this liquid, left for a few minutes in the liquid and the major part of the remaining liquid is separated off by decanting or filtration. The moist milled product is warmed, perhaps in a drying chamber, to a temperature above te boiling point of the liquid used. Water behaves particularly conveniently since arrangements for the purification of the waste vapour, namely steam, can be dispensed with.In another process, the milled product is immersed in turn in liquids which react with one another with evolution of heat to form gaseous reaction products, with the liquids and reaction products thereof being completely volatilised so that no additional heating of the liquid impregnated milled product is necessary in this case. Aqueous solutions of hydrogen peroxide and hydrazine may be used for this purpose.
Graphite particles regenerated by the process of this invention for use in the production of graphite foils of adequate strength exhibit a high plasticity and flexibility and can be formed into graphite foils and other bodies, for example sealing rings, in the same way as expanded graphite, that is without the addition of a binder.
This surprising result is possibly attributable to the fact that when the milled product is immersed in liquid, the liquid diffuses into residual chambers or pores made accessible through milling. On account of increasing vapour pressure therewithin, the particles then expand. When heated the expansion which occurs is essentially less than with the above described process for the production of expanded graphite and the volume of the particles increases by only up to about five times, usually up to two times, which is apparently adequate in the production of binder-free flexible graphite bodies.
Sealing rings may be produced from the regenerated graphite particles by compression of a heap of particles in a press die; the bulk density of the rings produced is essentially a function of the applied pressure. For bulk densities of 0.5, 1 and 1.5 g/cm3, pressures of about 1.5, 4 and 30 MPa are necessary. Regenerated particles behave particularly well in the production of flat seals, for example by the procedure of German
Offenlegungsschrift No. 251 8351, in which expanded graphite particles are pressed or rolled on a support and undergo a form locking combination.
The following examples illustrate this invention:
EXAMPLE 1
The waste which accumulated on stamping of flat seals from graphite foils, was milled by means of a pin disc mill and 200 g of the milled product, none of the particles of which was less than 4 mm across and a heap of which particles had a bulk density of about 0.2 g/cm3, was contacted with 400 g of water. After a contacting time of 15 minutes, the wet heap was heated to 3000C within about 1 minute. The bulk density of the heaped product obtained after the thermal treatment was about 0.1 g/cm3, indicating that the volume of the individual particles had on average doubled.
EXAMPLE 2
100 g of graphite foils milled as in Example 1 were covered with 100 g of a 10% aqueous solution of hydrogen peroxide and after a period of 5 minutes, the moist milled product was heated within about 2 minutes to 3000C. The bulk density of the heap produced amounted to 0.07 g/cm3, indicating that the particle volume had on average increased 2.5 timers.
EXAMPLE 3
100 g of graphite foils milled as in Example 1 were covered with a 20% aqueous solution of hydrogen peroxide followed, after complete adsorption of the hydrogen peroxide solution by the graphite particles, by a 20% aqueous solution of hydrazine. The temperature of the milled foils increased rapidly through the exothermic reaction of hydrogen peroxide and hydrazine to above the boiling point of water which was given off as steam from the heaped material together with the other gaseous reaction products of hydrogen peroxide and hydrazine. The resulting heap bulk density amounted to 0.045 g/l, indicating that the mean particle volume had increased approximately by a factor of 4.
After each of the foregoing Examples, cubic bodies were produced from the treated particles.
Moreover in a comparative test, cubic bodies were produced simply by compressing the immediate product of milling graphite foil off-cuts. The cubes all had an edge length of 26 mm and a bulk density of 1.0 g/cm3. The compression strength of the cubes was as follows:
without treatment 12.5 N/mm2
after Example 1 15.5 N/mm2
after Example 2 18.0 N/mm2
after Example 3 24.0 N/mm2
Claims (10)
1. A process of preparing, for reutilisation, graphite foil which has been produced by compressing together expanded graphite particles, which comprises milling the foil, immersing the milled foil in a liquid medium or in a number of liquid media used sequentially and removing the liquid or liquids in the form of one or more vapour phase products.
2. A process as claimed in claim 1, wherein the graphite foil is off-cut material from the stamping of graphite seals.
3. A process as claimed in claim 1 or 2, wherein the graphite foil is milled to a particle size of from 1 to 5 mm.
4. A process as claimed in any one of the preceding claims, wherein the liquid medium is water.
5. A process as claimed in any one of claims 1 to 3, wherein the milled foil is sequentially immersed in liquid reagents which react together exothermally to an extent such that said liquid media and reaction products thereof are completely volatilised.
6. A process as claimed in claim 5, wherein said liquid media are aqueous solutions of hydrogen peroxide and hydrazine.
7. A process for preparing for reutilisation graphite foil, substantially as described in any one of the foregoing Examples 1 to 3.
8. Graphite foil which has been prepared for reutilisation by the process claimed in any one of the preceding claims.
9. A shaped product which has been prepared by compressing together particles of graphite produced by the process claimed in any one of the preceding claims.
10. A shaped product as claimed in claim 9, which is a flat seal.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19803004574 DE3004574A1 (en) | 1980-02-08 | 1980-02-08 | METHOD FOR REGENERATING GRAPHITE FILM |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2068922A true GB2068922A (en) | 1981-08-19 |
Family
ID=6094022
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8100669A Withdrawn GB2068922A (en) | 1980-02-08 | 1981-01-09 | Reutilisation of graphite foil offcuts |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3004574A1 (en) |
| FR (1) | FR2475532A1 (en) |
| GB (1) | GB2068922A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2524956A1 (en) * | 1982-04-07 | 1983-10-14 | Waertsilae Oy Ab | VALVE WITH SEALED COVER |
| EP0117989A1 (en) * | 1983-02-24 | 1984-09-12 | Gray Tool Company | Fire resistant connections embodying heat transfer means |
| US4777083A (en) * | 1984-12-27 | 1988-10-11 | Kureha Kagaku Kogyo Kabushiki Kaisha | Carbon article comprising pieces of carbonaceous material bonded with one another and process for producing the same |
| EP1348240A2 (en) * | 2000-11-30 | 2003-10-01 | Graftech Inc. | Catalyst support material for fuel cell |
| WO2004087572A1 (en) * | 2003-03-31 | 2004-10-14 | Young Woo Shin | Manufacturing method of expanded graphite products |
| CN100491241C (en) * | 2003-03-31 | 2009-05-27 | 辛荣雨 | Manufacturing method of expanded graphite products |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4794043A (en) * | 1985-04-30 | 1988-12-27 | Kureha Kagaku Kogyo Kabushiki Kaisha | Carbon product comprising carbonaceous materials joined together, said carbon product for electrode substrate of fuel cells and process for production thereof |
-
1980
- 1980-02-08 DE DE19803004574 patent/DE3004574A1/en not_active Withdrawn
- 1980-11-26 FR FR8025107A patent/FR2475532A1/en active Granted
-
1981
- 1981-01-09 GB GB8100669A patent/GB2068922A/en not_active Withdrawn
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2524956A1 (en) * | 1982-04-07 | 1983-10-14 | Waertsilae Oy Ab | VALVE WITH SEALED COVER |
| EP0117989A1 (en) * | 1983-02-24 | 1984-09-12 | Gray Tool Company | Fire resistant connections embodying heat transfer means |
| US4777083A (en) * | 1984-12-27 | 1988-10-11 | Kureha Kagaku Kogyo Kabushiki Kaisha | Carbon article comprising pieces of carbonaceous material bonded with one another and process for producing the same |
| EP1348240A2 (en) * | 2000-11-30 | 2003-10-01 | Graftech Inc. | Catalyst support material for fuel cell |
| EP1348240A4 (en) * | 2000-11-30 | 2007-10-03 | Graftech Inc | Catalyst support material for fuel cell |
| WO2004087572A1 (en) * | 2003-03-31 | 2004-10-14 | Young Woo Shin | Manufacturing method of expanded graphite products |
| GB2414232A (en) * | 2003-03-31 | 2005-11-23 | Young Woo Shin | Manufacturing method of expanded graphite products |
| GB2414232B (en) * | 2003-03-31 | 2007-08-01 | Young Woo Shin | Manufacturing method of expanded graphite products |
| CN100491241C (en) * | 2003-03-31 | 2009-05-27 | 辛荣雨 | Manufacturing method of expanded graphite products |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2475532A1 (en) | 1981-08-14 |
| DE3004574A1 (en) | 1981-08-13 |
| FR2475532B3 (en) | 1983-09-09 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |