DE3034359A1 - Process for producing high-density,high-strength carbon and graphite material - Google Patents

Description

DR. A. VAN DER WERTH DR. FRANZ LEDERER R. F. MEYER-ROXLAU

DlPL-ING. (1934-1974-. DIPL-CHEM. DIPL-ING.

8000 MONKS 80 LUCILE-GRAHN-STHASSE

TELEPHONE: (089) 472947 TELEX: 524624 LEATHER D TELEGR: LEOERERPATENT

October 3, 19 78025

MARUZEN PETROCHEMICAL CO., LTD. 25-10, Hacchobori 2-Chome, Chuo-ku, Tokyo 104, Japan

Process for the production of carbon and graphite materials of high density and high

strength

The invention relates to a method of making high density carbon and graphite materials and Strength from fresh coke as a raw material.

Heretofore, ordinary carbon materials have been produced through a series of steps, including pulverizing a burnt coke obtained by burning a fresh coke usually at 1200 to 1300 ^° C., adding a binder such as pitch and the like to the pulverized coke, kneading the Mixing, re-pulverizing, molding and baking was obtained. In such a process, however, a significant proportion of the pitch binder used, for example an amount greater than one third of the total amount used, is decomposed and evaporated during baking, so that the remaining carbonaceous materials tend to contract as the baking temperature increases. As a result, the thus obtained baked carbon

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materials have a number of pores and thus cannot possibly be sufficiently compacted. Usually the bulk density of graphitized carbon materials is about 1.70 to 1.75 g / cm ³ or less.

Further, in order to obtain carbon and graphite materials of higher bulk density, it is common practice to impregnate a once-baked shaped body (hereinafter referred to as first-baked material) with a molten pitch under reduced pressure and then pressurize the pitch into the pores of the material to fill and to deposit therein and then ^{to bake the impregnated material again at a temperature above 1000 0} C in order to convert the material into carbon. This procedure usually requires repeating the baking and pitch impregnation several times. The first baking temperature is determined so that the carbonaceous materials originating from the pitch binder come into full contact with a large amount of pitch of the subsequent pitch impregnation step and are impregnated. In general, a temperature of at least 750, usually about 800 ⁰ C, for the first baking step is required. In the case of the production of graphite materials for nuclear reactors, a temperature of about 1300 ^° C. can be used for the first baking.

As mentioned above, the previous methods of manufacturing high density carbon and graphite materials are not only complicated but also uneconomical in terms of energy due to the necessity of repeating high temperature baking and pitch impregnation several times. Furthermore, these methods are also unsatisfactory in that they can only produce graphite materials with a bulk density of at most 1.85 g / cm ³ without sufficient strength.

Recently, there is a new method of making high density carbon and graphite materials from a fresh one

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303A359

Coke or other carbonaceous materials of certain special properties have been developed as a starting material without the use of a binder, i.e. by utilizing the self-sintering property of the starting material (JA B, 53-18359 and JA A, 50-74281). Such a self-sintering process is of great practical value, as laborious or expensive steps, such as the incorporation of a binder pitch, Impregnation with pitch and the like. Can be omitted. However, there are still some disadvantages in the self-sintering process to improve, since the choice of carbonaceous raw materials, the conditions for the production of the molding are limited to a certain extent, due to the fact that the bonding between the fine particles of the carbonaceous raw material is not by a binder takes place, but by sintering at the points of contact between the particles themselves, and that a sufficient high density of the sintered material is not always reflected in its strength, as expected. Furthermore, like with some Applications require a higher strength of the sintered material.

The object of the invention is to provide a method for producing carbon and graphite materials that are higher Have strength than those already proposed Self-sintering processes have been made using any type of fresh, usually readily available, coke like the commercial one, is used as the raw material and which makes carbon and graphite materials of such high quality are very simple and easy to manufacture compared to conventional processes starting from a burnt coke. Another aim of the invention is to provide an economical process for the production of graphite materials of very high purity, which can be used as materials for semiconductors and nuclear reactor cores suitable, whereby a fresh coke of high purity is used as fresh starting coke and "a cleaning agent

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action ", which is essentially the case with conventional methods is not required.

These and other objects, advantages and features of the invention will become apparent from the following description.

In general, the invention provides a method for producing carbon materials of high density and strength, in which a finely powdered fresh coke, which is sintered during baking without melting, alone or in combination with a binder pitch under pressure, forms the shaped body in a first baking stage baked at a temperature of 450 to 700 ^° C., the baked material is impregnated with a pitch under pressure and the material so impregnated is baked in a second baking stage at high temperature in the usual way to convert the material into carbon.

The invention also leads to a method of production of graphite materials of high density and high strength, in which the carbon materials thus produced in the usual manner are graphitized.

The starting material to be used according to the invention is any type of fresh coke that sinters without melting during baking, such as fresh petroleum coke and fresh coal pitch coke as commercially available. Of course, carbon and graphite materials of higher quality by using a fresh coke of higher purity and careful handling can be obtained.

According to the invention, the fresh starting coke is made with a pulverizer of the type of abrasion, type of impact, etc. * pulverized The average particle size of the pulverized powder of fresh coke may be 20 μm or below and preferably 10 µm or below.

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_ CS ' _

The pulverized fresh coke powder has self-sintering properties and can be used as such, i.e. without the addition of a binder pitch, for the production of the carbonaceous compounds according to the invention Materials of high density and strength are used. Becomes a fresh coke with a low volatile content Material, i.e. about 7% or less, as starting material used, however, a small amount of binder pitch should be incorporated to avoid possible breakdown avoiding the shaped body during the pitch impregnation stage due to insufficient strength of the first baked material, this is due to the self-sintering properties of the starting material not suffice. Similarly, incorporating a small amount of binder pitch into a fresh coke is beneficial with higher volatile matter content the achievement of more homogeneous carbon materials · In any case, the The amount of binder pitch to be incorporated is much lower than that in the conventional processes that are carried out by a fired Run out of coke, necessary to get a satisfactory result. According to the invention, the amount of binder pitch is incorporated per 100 parts of fresh starting coke is, about 3 to 15, preferably about 5 to 10 parts for a fresh, low volatile coke Material and about 0.16, preferably about 2-4 parts for a fresh coke with a high volatile content Material, while in the known processes which start from a burnt coke, the amount of per 100 parts of the binder pitch incorporated into fresh starting coke is usually about 25 to 40 parts. It is of course clear that the amount of binder pitch to be incorporated depends on the starting material, the particle size, the molding pressure and other conditions varies.

The molded body thus obtained is subjected to a first baking and then impregnated with a pitch. As mentioned above, the temperature for the first jaws 450 to 700 ° C, preferably 500 to 650 ⁰ C. over 700 ⁰ C is found, no further

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Improvement in the strength of the resulting carbon material due to the impregnation of the pitch, but the strength tends to decrease in spite of the increase in the amount of the pitch used for impregnation. Below 450 ^° C., on the other hand, the decomposition of the volatile materials contained in the fresh starting coke is not sufficient to achieve a sufficiently high bond strength between the coke particles through self-bonding, so the first baked material may break apart in the pitch impregnation stage. Long baking, for example more than 48 hours, which is undesirable, is required to prevent the material from thus breaking apart.

For the Pechimprägnierstufe for erstgebackene material according to the conventional methods, starting from a fired coke, had the first baking step at a temperature of at least 750, usually 800 ⁰ G, take place. In such conventional processes, it was believed that the higher the first baking temperature, the higher the amount of pitch impregnated into the material, and thus the higher the density of the resulting carbon material. In contrast, it has now been found that the novel process, starting from a fresh coke, carbon materials having a high strength can be obtained satisfactorily if the first baking step at a temperature of 450 to 700, preferably 500 bi * s 65O ⁰ C, is carried out, which is much lower than in the first baking stage in the conventional process. Viewed from the prior art pitch impregnation technique, this is unexpected and of great technical importance. :

The reason why carbon materials are so high Strength can be obtained according to the invention, regardless the use of such a low temperature for the first baking stage is not yet clear, but the following reason is suspected:

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When baking the compression-molded body from fine powders Frischkoks decomposition begins volatile materials contained in the Frischkoks at a temperature around 35O ⁰ C, and the rapid weight loss of the molded body to listen at a temperature of about 600 to 650 ⁰ C. On the other hand, due to the compactness of the molding, the volume contraction of the molding slowly begins at around 450 ^° C., which is around 100 ^° C. above the start of the decomposition of volatile materials, and becomes predominant ^{from around 500 up to around 1000 ° C.} There is therefore a considerable temperature difference between the weight loss and the volume contraction that has occurred. Therefore, at the lower temperatures to 500 ⁰ C, the porosity of the material is high, which also makes the amount of the einimprägnierten pitch relatively high. At a temperature above 600 ⁰ C, the porosity decreases gradually due to the contraction of the molded body from, thus also decreases the amount of einimprägnierten pitch. Over 700 ⁰ C, the amount of einimprägnierten pitch rises again, possibly because the respective coke particles constituting the shaped body, are contracted considerably, despite the decrease in the contraction of the total volume of the molding, hence the porosity increases again. In the case of carrying out the first baking step at a temperature above 700 ⁰ C, however, a large amount of the then einimprägnierten pitch carbonized and learns after the second baking stage, a considerable volume contraction, in which the mold body itself undergoes less contraction, so that many pores and defects in the produced carbon materials remain. Conversely, if the first baking step at a temperature below 700 ⁰ C, in particular around 500 ⁰ C is carried out according to the invention / the mold body itself does not experience a significant contraction in the first baking stage, but in the second baking stage, in the charred the einimprägnierte pitch and at the same time considerably contracted will. Therefore, it is possible to obtain carbon materials of high strength, are chosen by the first .. Baking temperature 450 to 700 ⁰ C, then in spite of the

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impregnated relatively lower pitch content than in the case of using a higher first baking temperature. Further, at such a low temperature in the first baking stage, ie below 700 ⁰ C, in particular around 500 ⁰ C, the thermal decomposition of the fresh Ausgangskokses still incomplete, where still a considerable amount of substances remain organic nature. So it is positively expected that in the second baking stage fine particles of fresh coke, which sinter, but still have a substantial amount of substances of an organic nature, can form strong bonds with the impregnated, currently charring pitch.

It can thus be determined that in a process in which a finely powdered fresh coke is compression-molded into a shaped body and the latter is subjected to a first baking, a pitch impregnation and then a second baking, the first jacket temperature, which is advantageously used to increase the influence of the impregnation, is that the lower than the temperature at which the rapid change the volume contraction of the shaped body is completed, and that in which the porosity of the shaped body due to the Temperature difference between the thermal decomposition and the volume contraction that has occurred is increased, and that in which the thermal decomposition of the fresh starting coke has not yet been completed and is an essential one Amount of substances of organic nature still remaining should be.

Pitch to be used for impregnation may be coal tar pitch, asphalt pitch, "ethylene" tar pitch, and the like. It can with be diluted with a diluent such as a tar.

The temperature at which the impregnation takes place can be so be chosen that the viscosity of the pitch is low enough that the molten pitch sufficiently into the pores of the

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can penetrate first-baked material, and can also be chosen so that the decomposition and the evaporation or volatilization of the pitch itself is prevented. Thus the temperature for example, 200 C. If the pitch used is substantially soluble in a diluent such as in the case of "ethylene" -Teerpech, it may be diluted with a diluent and used to 250 ⁰ to impregnate at a lower temperature of about 100 ⁰ C. will.

The first-baked material thus impregnated can be subjected to a second baking, which, if necessary, is followed by graphitization in a conventional manner according to the prior art. According to the invention, the second baking stage is usually carried out at a temperature over 1000 ⁰ C., for example at 1200 to 1400 ⁰ usually C. The Graphitierstufe carried out at a temperature of 2400-3000 ⁰ C, but for some applications of the resulting graphite materials may have a lower temperature be used, to cause partial graphitization.

According to the invention, the material costs are low, since each type Usually available fresh coke can be used as a starting material, i.e. the use of certain special Fresh coke or · other carbonaceous material, which is a special. Treatment is not necessary. The method according to the invention is also advantageous over the prior art in that first baking temperature is low and only one pitch impregnation step is required for carbon and graphite materials high density, high strength, good oxidation and chemical resistance and low specific resistance to manufacture.

If the method according to the invention is applied to a fresh petroleum coke particularly high purity used as the starting material, high purity graphite materials can be obtained which

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H-

are suitable for applications that require extremely high purity, e.g. for the manufacture of semiconductors and nuclear reactor cores. In the prior art a "purification treatment" had for preparing graphite materials such high purity during the Graphitierstufe take place, including chlorine, fluorine, or fluorinated (halo) hydrocarbon (Freon) gas held in at a temperature of 2500 ⁰ C or higher Graphitizing furnace is introduced in order to convert such small impurities as metals, which form the ash content of carbon materials, into their halides and to evaporate them and thus remove them from the graphite materials formed. Such cleaning treatment is expensive and increases the cost of the product. On the other hand, according to the present invention, graphite materials of high purity can be obtained very economically by selecting an appropriate raw material without applying such "cleaning treatment".

A preferred embodiment of the invention for producing graphite materials of high purity comprises pulverizing a fresh high-purity petroleum coke with an ash content of less than 500 ppm, molding the pulverized fresh coke under pressure without incorporating any binder pitches, first baking the shaped body at a low temperature of 450 to 700 ° C, impregnating the material with a pitch erstgebackenen high purity second baking the impregnated pitch material at a high temperature more than 1200 ⁰ C, preferably more than 1300 ⁰ C, and graphitizing the second baked material. The graphitization can be carried out in a conventional manner by embedding the second baked material in a packing powder. The packing powder used comes from the same fresh petroleum coke .. of high purity as that which is used as the starting material for the process, namely by burning the fresh

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Coke and finely pulverizing the burnt coke. According to the method according to the invention, graphite materials high density and strength and such a high purity that the ash content is below 20 ppm and the boron content is 0.1 to 0.2 ppm, can be produced in a very economical manner.

The fresh high purity petroleum coke with an ash content below 500 ppm, which is the preferred starting material for the Embodiment of the method according to the invention is useful, can be one by delayed coking of a heavy petroleum residue with very low levels of impurities other than hydrocarbons is obtained, such as E.g. pyrolysis tar, which is produced as a by-product in the pyrolysis of naphtha, kerosene, gas oil etc. for the purpose of ethylene production (hereinafter referred to as ethylene tar) is obtained, as well as one that is produced by mild pyrolysis of a heavy petroleum residue with a fairly large amount of impurities for polycondensation of the impurity-rich ingredients Formation of a pitch, obtained by removing the pitch and delaying coking of the remaining heavy oil. A special one a preferred embodiment of the latter process is described in US Pat. No. 4,177,133.

In the aforementioned embodiment of the invention in which the production of graphite materials of high purity is intended, a pitch and used for impregnation should be used A burnt coke used as a packing powder in graphitization can also be of high purity. As an impregnating one Pitch is particularly preferably a pyrolysis tar pitch used as a by-product in the pyrolysis of Naphtha, kerosene, gas oil etc. for the purpose of ethylene production is obtained. As the packing powder used in the graphitization step, a finely pulverized powder is preferably burned Coke used / obtained by burning a fresh

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- νί -

see high purity petroleum coke as the raw material is to be used for the method according to the invention.

The following examples further illustrate the invention.

example 1

100 parts of fresh petroleum coke having a volatile matter content of 14.7%, quinoline solubles of 12.6% and H / W of 0.62 were mixed with 25 to 35 parts of water, and the mixture was pulverized in a pan mill pulverizer to achieve an average particle diameter of 6.5 µm. The pulverized mixture was compression-molded under a pressure of 981 bar (1000 kg / cm ² ) into a molded article 3 cm in diameter and 3 cm in height. The body was embedded in a coke powder, heated at 30 ° C / hr, and baked at a temperature of 400 to 900 ⁰ C.

The baked body (the erstgebackene material) was placed into a a coal tar pitch having a softening point of 87 ° C containing pressure vessel gradually to 250 ⁰ C under a vacuum from 1333 to 2666 Pa (10 - 20 mm Hg) and maintained at this Temperature and a pressure of 9.81 bar (10 kg / cm ² ) held for 1 hour in order to impregnate it with the pitch. Then the impregnated material was ^{baked at 1400 °} C. in the same manner as in the first baking to obtain the second baked material. This was then graphitized at 2400 ⁰ C.

The physical properties of second-baked material and the graphitic material are shown in Table 1 '■ play back anything: give. For comparison, Table 1 also shows the physical properties of the second baked material and the graphitized material, obtained after the same process steps, with the exception of the omission of the pitch impregnation step, as well as those of a commercially available graphitized product.

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Table 1

sample 1st bathing temperature
rature
( ⁰ C) 1. Back
time
(H) Pitch impregnation
renal amount
(Wt .-%) Bulk density
of the second
baked ma
terials
(g / an ³ ) Graphitized material (2400 ⁰ C) Shore
hardness Bending
sturdiness
(kg / cm ² ) spec .Wi
the state
(μΩση) Breaking apart during pitch impregnation no bad luck impregnation 1.92 1.98 86 890 2390 1 400 48 Schütt
density
(g / cm ³ ) 13.3 1.84 1.92 76 900 2210 2 450 48 11.5 1.83 1.91 75 890 2150 3 500 12th 10.1 1.82 1.89 75 800 2270 4th 550 3 8.4 1.82 1.88 73 670 2290 5 600 3 6.6 ' 1.83 1.88 73 700 2300 6th 650 3 5.6 1.78 1.83 62 550 2360 7th 700 3 11.9 1.67 1.82 58 350 3040 8th 900 3 1.85 550 9 trade
usual
product

Example 2

The same fresh petroleum coke as in Example 1 was pulverized to an average particle diameter of 3.4 µm as there was. The pulverized coke was rubber molded under a pressure of 981 bar (1000 kg / cm ² ) into a molded body of 17.5 × 10.5 × 4.0 cm. The shaped body was ^{baked for 3 h at 550 0} C, impregnated with pitch, baked again and then graphitized as in Example 1, with the exception that the temperature rise in the first and second baking stage was 7.5 ° C / h and the time for the pitch impregnation was 5 hours.

The bulk density and flexural strength of the second baked material and the graphitized material are in Table 2 specified. For comparison, Table 2 also shows the results of a reference example in which the same Procedural steps were repeated as above, with the exception that the pitch impregnation was omitted.

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Table 2

Pitch impregnator
crowd
(Wt .-%) Bulk density
of the second
baked ma
terials (g / cm ³ ) graphitized material
(2600 ⁰ C) Flexural strength
speed
(kg / cm ² ) according to the invention 12.0 1, 87 Bulk density
(g / cm ³ ) 900 Reference example no bad luck
impregnation 1, 76 1.95 490 1, 90

-O · CO

Example 3

The same fresh petroleum coke as in Example 1 was pulverized in an impact pulverizer to have an average particle diameter of 4.5 µm. The pulverized coke was formed under a pressure of 490 bar (500 kg / cm ² ), 981 bar (1000 kg / cm ² ) or 1962 bar (2000 kg / cm ² ) to form a molded body each 3 cm in diameter and 3 cm in height compression molded. The shaped body was baked, impregnated with pitch, baked again and then ^{graphitized at 2200 °} C. as in Example 1, with the exception that the first baking took place ^{at 550 ° C. for 3 hours.}

The physical properties of the second baked material and the graphitized material are shown in Table 3:

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Table 3

sample Porm printing
bar (kg / cm ² ) Pitch impregnation
renal amount
(Wt .-%) Bulk density
of; second baked
kerien material
(g / an ³ ) Graphitized material (2200 ⁰ C) Shore
hardness Flexural strength
speed
(kg / cm ² ) spec. Contrary
was standing
(μΩαπ) 1 490 (500) 33.4 ' 1.69 Schütt
density
(g / cm ³ ) 79 570 2,420 2 981 (1000) * 27.8 1.75 1.76 79 640 2,160 3 1962 (2000) 24.2 1.73 1.80 75 720 2,200 1.84

Example 4

100 parts of a fresh petroleum coke with a volatile material content of 14.5% were mixed with 4 parts of a coal tar pitch with a softening point of 87 ⁰ C and the mixture in a pan mill pulverizer in the presence of 26 to 30 parts of water to an average Particle diameter of 4.4 μm pulverized. The pulverized mixture was molded into a molded article of 17.5 × 10.5 × 4.0 cm by rubber pressing under a pressure of 981 bar (1000 kg / cm ^2).

The shaped body was baked a first time, impregnated with pitch, baked a second time and then ^{graphitized at 2500 °} C. as in example 2.

The physical properties of the second baked material and the graphitized material shows, Table 4:

Table 4

Pitch impregnation
amount of eggs
(Wt .-%) Bulk density,
of the second
bake ma ^ *
terials
(g / an ³ ) Graphitized material (2500 ⁰ C) Bending
sturdiness
(kg / an ² ) spec. Contrary
was standing
(μΩ on) 12.0 1.88 Bulk density
(g / an ³ ) 980 2,400 1.96

Example 5

A fresh petroleum coke with a volatile matter content of 6.8% became an average in a ball mill Particle diameter of 4.5 μm pulverized. 100 parts of the powdered Cokes became homogeneous with TO parts of a coal tar pitch

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with a softening point of 87 ⁰ C mixed. The mixture was molded and the molding was baked a first time, impregnated with pitch, baked a second time and then graphitized as in Example 1, with the exception that the first baking took place ^{at 550 ° C. for 6 hours.}

The physical properties of the graphitized material Table 5 shows.

For comparison, these are the test results obtained by repeating the above procedure except for no pitch addition also listed:

Table 5

Added
Amount of bad luck
(Wt .-%) Pitch impregnation
crowd
(Wt .-%) Graphitized material (2400 ⁰ C) Shore
hardness Flexural strength
(kg / cm ² ) Broken during pitch impregnation 10 9.7 Bulk density
(g / cm ³ ). 63 650 0 1.86

Example 6

A fresh petroleum coke with a volatile material content of 14.5% was pulverized dry in a pan mill pulverizer without the addition of water to an average particle diameter of 5.6 μm. The pulverized coke was sieved to remove coarse particles of 35 mesh + (JIS), and the fine powder was made into a molded article 14 cm in diameter and 16 cm in height ^{under a pressure of 981 bar (1000 kg / cm 2)}

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rubber compression molded. The molded body was 3 h gebakken at 600 ⁰ C, to which he put into a a coal tar pitch having a softening point of 87 ⁰ C-containing pressure vessel, gradually under a vacuum from 1333 to 2666 Pa (10 to 20 mm Hg) and maintained at this Temperature was maintained under a pressure of 19.62 bar (20 kg / cm ² ) for 8 hours to impregnate it with the pitch. The material impregnated with pitch in this way was baked a second time and then ^{graphitized at 2800 °} C. as in example 1.

The physical properties of the graphitized material are listed in Table 6:

Table 6

Bad luck-
Impregnation
crowd
(Wt .-%) Graphitized material (2800 ° C) Shore
hardness Flexural strength
speed
(kg / cm ² ) specific opposition
was standing
(μΩ cm) 24.5 Bulk density
(g / an ³ ) 72 480 1,150 1.88

The graphitized material was cut into a 4 cm cube test sample. ^{The sample was heated to 1000 °} C. for 10 minutes in an electric furnace and immediately poured into cold water in order to determine the thermal shock resistance. As a result, no change in appearance and strength was found.

Example 7 '['"''"' ^J ''"■" ^!: - ^: * - ■■ "■''-■■■' ■ '■ / r. · ■■■. ■,; -. ;... ,, ~ ■■ · ■, ..., _.

The same fresh petroleum coke as in Example 5 was pulverized as there to an average particle diameter of 6.1 μm. The pulverized coke was

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sieves to give a finely divided fraction with an average particle diameter of 2.9 μm in a yield of about 30%. This portion was molded by rubber pressing under a pressure of 245.25 bar (250 kg / cm ² ). This shaped body was baked a first time, impregnated with pitch, baked a second time and then graphitized as in Example 5, with the exception that the time for the pitch impregnation was 12 hours. The properties of the graphitized material are shown in Table 7:

Table 7

Pitch impregnation
crowd
(Wt .-%) Graphitized material (2400 ⁰ C) Schütt
density
(g / cm ³ ) Shore
hardness Flexural strength
speed
(kg / cm ² ) spec. resistance
(μΩ cm) 43.1 ' 1.85 73 820 1230

The graphitized material was cut into a test electrode of 2.5 × 2.5 × 5 cm for an electrical discharge machining test. Alloy steel to be used for molds was used as the material to be machined. In this machining test, the alloy steel material was machined into a recess 12 mm deep in the bottom. The processing took place _; under relatively weakly erosive conditions, ie the polarity of the electrode was positive, both times, the "switch-on time" and the "switch-off time" were 50 με and the peak current was 23 A. "After the test, the decrease in length of the electrode was 0.0% and the Roughness of the machined surface

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about 7 μΐη (in the case where a graphite material is first-class Of the commercial product was used as the test electrode in the same discharge machining test as above, the decrease in length was the electrode 2.3 to 3.8% and the surface roughness 8 to 15 μπι).

Example 8

A pyrolysis tar (naphtha-ethylene tar), which was obtained as a by-product in the pyrolysis of naphtha for the production of ethylene, was distilled in order ^{to remove light fractions with a boiling point below 250 °} C. and a heavy residue with a specific gravity of 1.139 and a Conradson coke residue of 12.8%. The heavy residue was coked in a coking drum at a temperature of 440 ^° C. under a pressure of 8.83 bar (9 kg / cm ² ) for 24 hours, after which steam was blown in for 3 hours. The fresh petroleum coke thus obtained had a volatile matter content of 11.9% and was used as a raw material for the production of carbon and graphite materials. Thus, the fresh coke was ground in a pan mill pulverizer for 2 hours, and a fines of 65 mesh (JIS) was obtained. This portion was compression-molded by applying hydrostatic pressure under a pressure of 981 bar (1000 kg / cm ² ) to give a fresh shaped body 12 cm in diameter and 12 cm in height. The molded body was subjected to a first baking at various temperatures ranging from 400 to 900 ⁰ C, whereby the temperature rise in the baking atmosphere 15 ° C / h between room temperature and 360 ⁰ C, 10 ° C / h from 360 to 400 ⁰ C, 3 ° C / h is between 400 and 6ÖÖ ° C, and after the required temperature has been reached>^; it was held for the required time. After cooling, the sintered material would be removed from the oven and impregnated with ethylene tar pitch at 220 ° C under an overpressure of 19.62 bar (20 kg / cm ² G) for 8 h in the usual way. Ethylene tar pitch was produced by using naphtha-ethylene

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Tar was distilled to remove light fractions with a boiling point below 330 ^° C., and had a softening point (ring and ball method) of 130 ^° C. and a solid carbon content of 55.3%. The impregnated with pitch so erstgebackene material was also a second jaws subjected to a temperature of 1300 ⁰ C. The temperature rise in the second baking was the same as in the first baking up to 400 ⁰ C, 3 ° C / h from 400 to 750 ⁰ C, 20 ⁰ C / h from 750 to 900 ⁰ C and 50 ° C / h between 900 and 1300 ⁰ C and at 1300 ⁰ C the baking was continued for 3 h. The resulting second baked material was embedded in a packing powder which was obtained by burning the same fresh petroleum coke as used as the starting material at 1300 ^° C. and graphitized by heating in a graphitizing furnace up to 2800 ^° C. by direct passage of an electric current. The relationships between the first baking temperature and the pitch impregnation amount and the properties of the second baked material and graphitized material are shown in Table 8. Table 9 shows the content of impurities, and the properties of the fresh starting petroleum coke and the graphitized material obtained at the shoulder, wherein the first baking at 55O ⁰ C was carried out, in comparison with those typical graphite materials such as those available ^r commercially intended for the manufacture of nuclear reactors and semiconductors.

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Baking conditions time
(H) Table 8 ■
Bulk density
of the second
baked ma
terials graphitized material (2800 ⁰ C) Flexural strength
speed
(kg / cm ² ) temperature
( ⁰ C) 48 - Bulk density - 400 48
12th Pitch impregnator
crowd
(Wt .-%) 1.81
1.78 - 470
490 450
500 5
3
3 at the.Pech-Im
impregnation zer
broke 1, 78
1.77
1.77 1, 87
1, 86 480
470
450 550
600
650 3 24.2
24, 5 1.76 1.85
1, 84
1, 84 440
i U> O
ο · ■ ->
CO ί " 700 3
I.
I. 23.8
22.0
20.3 · ■ 1/72
i 1, 83 380 1 / OOAO 900 : 18.5. 1.78 ; 23.8

table

properties Shore
hardness i Bend
firm
speed
(kg / cm ² ) spec.Wi
the state
(μΩ cm) salary of impurities (ppm) Fe Ni V Cu I. Schütt
density ash B. example - 65 0.5 1.3 0.4 Initial
Petroleum coke 68 480 1200 300 0.23 1.2 <1, 0 1.8 0.5 Graphitized.
material .
1, 86 <20 0.18 commercially available
Graphite material - 230 900 45 0.5 0.1 - for nuclear reactors 1.82 ; 410
490 _{ 1080
1150 200 , 0.50 - - : _; at
for semiconductors C
BJ 1.73
1.85 120 : 0.20
1.0

Example 9

A heavy residue oil having a specific gravity of 1/0913, a Conradson coke residue of 6.6% and a sulfur content of 0.65% was used as a coke feed, which was obtained by removing solid materials from a sludge oil produced by catalytic flow cracking of gas oil, desulphurisation of the oil and distillation of the desulphurised oil to remove light fractions with a boiling point below 250 ^° C. in order to obtain the heavy residual oil. The coking feed material was passed through a stainless steel tube with an inner diameter of 4 mm and a length of 20 m which was heated to 430 ^{° C. under an overpressure of about 4 bar (4 kg / cm 2 G).} The residence time of the feed material in the stainless steel tube was s about 230 that. The stainless steel tube leaving the feed material was introduced directly into an operating under atmospheric pressure at 450 ⁰ C high temperature flash evaporation tower where a pitch from the bottom of the tower with a residence time of about 10 was removed min continuously , while the overhead fraction leads to distillates including gas to gas oil fractions. and a heavy, over 300 ⁰ C boiling residue was fractionated. The heavy residue thus obtained was introduced into a coking drum, where at 435 ° C under a pressure of 8.83 bar (9 kg / cm ² G) 28 coked delayed h and then was blown for 3 hours at 440 ⁰ C steam. A fresh petroleum coke with a volatile matter content of 9.4% was thus obtained. The coke yield was 52.3% by weight, based on the heavy residue used.

The fresh petroleum coke thus obtained was ground in an impact mill to an average particle size of 65 µm and then further pulverized in a pan mill pulverizer for 60 minutes. The powdered fresh coke was then sieved to recover the 65 mesh portion, and this was in

1306 11/0040

a mold by pressing under a pressure of 981 bar (1000 kg / cm ² ) into a molded body of 20 12 χ 6 cm. The shaped body was baked a first time, impregnated with pitch, baked a second time and then graphitized as in Example 8. The pitch impregnation amount was 21.9% by weight based on the first baked material. The size of the graphitized material was 17.5 by 10.4 by 5.2 cm. The properties and levels of impurities in the graphitized material are shown in Table 10:

Table 10

Schütt
density Shore
hardness Bend
firm
speed
(kg / cm ² ) Spec.
Contrary
was standing
(μΩ cm) Content of impurities (ppm) B. Fe Ni V Cu 1.82 67 430 1320 ash 0.11 0.8 <1.0 2.5 0.3 <20

Example 10

A mixture of Middle Eastern crude oils was desulphurized directly to a desulphurized oil with a sulfur content of 0.32%, a specific gravity of 0.9188 and a Conradson coke residue of 3.9%. The desulphurized oil was passed through a stainless steel pipe with a diameter of 4 mm and a length of 20 m to 430 ^° C. at an excess pressure of 4 bar (4 kg / cm ² G). The residence time of the oil in the stainless steel tube was s about 230th Then, the held oil directly into a flash evaporator distillation column under atmospheric pressure at 430 ⁰ C, is introduced, in which a pitch from the bottom in an amount of 17.8 parts by weight % and an overhead distillate as in Example 9 was withdrawn. The overhead distillate was fractionated to give a heavy residual oil with a boiling point above 350 ° C

■■ '. · ■■■ ■' ■ ■■ '■■■ - ■■■ ·. · "£.! -. · ■■■

obtainable in an amount of 59.3% by weight. The difficult return

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stand oil was at a temperature of 460 ⁰ C and a pressure of 8.83 bar (9 kg / cm ^a) 18 h to a fresh coke having a volatile content of 14.3% in 20.8 wt .-% yield delayed coking. In this case there was no steam treatment. The fresh coke was pulverized in a mill equipped with a classifier to make the average particle diameter 4.4 μm, and the pulverized coke was made fresh ^{by hydrostatic pressing under a pressure of 981 bar (1000 kg / cm 2)} Molded body with a diameter of 12 cm and a height of 12 cm. The fresh molding was baked a first time, impregnated with pitch; baked a second time and then graphitized as in Examples 8 and 9. The properties and contents of impurities in the graphitized material are shown in Table 11;

Table 11

!
Schütt
density Shore
hardness Bend
firm
speed
(kg / cm ² ) spec.
Contrary
was standing
(μΩ cm) Content of impurities (ppm) B. Fe Ni V Cu 1.78 64 380; 1150 ash 0.23 0.9 <1.0 4.5 1/0 <20

The carbon material (the second baked material) and the Graphite material (the graphitized material) made in accordance with the present invention are extremely high density and high strength. Therefore, the carbon material can be used as a material for the Machine manufacturing, especially used as a material for sliding parts and for electrodes for electrolysis, while the graphite material is as wide as a material for machine manufacturing and metallurgical products, such as Melting crucible, as well as material for electrodes for electrical

130611/0040

cal discharge machining, semiconductors and nuclear reactor cores can be used. In particular the graphite materials high purity with low ash content are useful as materials for semiconductors and nuclear reactor cores, the one must meet strict standards.

130611/0040

Claims (15)

Claims 1. A method for producing a high density and high strength carbon material, characterized in that a finely powdered fresh coke which sinters in baking without melting, alone or in combination with a binder pitch under pressure, the molded body a first time at a Temperature of 450 to 700 ⁰ C baked, the baked material is impregnated with a pitch under pressure and the material so impregnated is baked a second time at high temperature in the usual way to convert the material into carbon. 2. The method according to claim 1, characterized in that it is carried out at a first baking temperature from 500 to 650 ⁰ C ^r ". 3. The method of claim 1 or 2, characterized in that it is carried out at a second baking temperature of at least 1000 ⁰ C. 4. The method according to any one of claims 1 to 3, characterized in that that the binder pitch in an amount less than 15 parts by weight per 100 parts by weight of the fresh starting coke is incorporated. 130611/0040 -X- 5. A method for producing a graphite material of high density and high strength, characterized in that a finely pulverized fresh coke which sinters during baking without melting, alone or in combination with a binder pitch under pressure, the molded body a first time at a Temperature of 450 to 700 ⁰ C, the baked material is impregnated with a pitch under pressure, the material so impregnated is baked in a second baking stage at high temperature in the usual way to char the material and the charred material is graphitized in the usual way. 6. The method according to claim 5, characterized in that it is carried out for a first baking temperature from 500 to 650 ⁰ C. 7. The method according to claim 5 or 6, characterized in that it is carried out for a second baking temperature of at least 1000 ⁰ C. 8. The method according to any one of claims 5 to 7, characterized in that that the binder pitch in an amount of less than 15 parts by weight per 100 parts by weight of the fresh starting coke is incorporated. 9. The method according to any one of claims 5 to 8, characterized in that graphitization is carried out ^{at a temperature of 2400 to 3000 0 C.} 10. A method for producing a graphite material of high purity, characterized in that a fresh petroleum coke high purity is finely pulverized with an ash content of less than 500 ppm, the pulverized Coke alone, without the addition of a binder pitch, formed under pressure, the shaped body in a first baking stage 130611/0040 baked at a temperature of 450-700 ⁰ C, the baked material with a pitch high purity under pressure impregnated, cooked, the material thus impregnated in a second baking step at a temperature above 1200 ⁰ C and the baked material in a conventional manner in a packing powder that is graphitized a fine powder from a burnt coke obtained from a fresh, high-purity petroleum coke with an ash content of less than 500 ppm. 11. The method according to claim 10, characterized in that it is carried out at a first baking temperature of 500 to 65O ⁰ C. 12. The method according to claim 10 or 11, characterized in that it is carried out at a second baking temperature of over 1300 ⁰ C. 13. The method according to any one of claims 10 to 12, characterized in that graphitization is carried out ^{at a temperature of 2400 to 3000 0 C.} 14. Made of high density and high strength carbon material according to the method according to claim 1. 15. Graphite material of high density and high strength produced by the method according to claim 5. 1 * 6. Graphite material of high purity produced by the process according to claim 10. 6S £ $ 8 OS 130611/00 AQ