DE1571307A1 - Process for the production of graphite - Google Patents

Description

Process for the production of graphite.

The invention relates to a method for producing graphite, especially core graphite.

In recent years, the demand for graphite, which has a higher coefficient of thermal expansion, has been considerable grown. The manufacture of such graphites took place from raw materials of certain origins, and it has become Various types of coke proved unsuitable for the usual process, especially when the .graphite was used for the purposes nuclear energy, such as in gas-cooled reactors should find.

The present invention relates to a method for producing graphite having an increased coefficient of thermal expansion using a variety of starting materials. The invention further relates to a method as possible 'Cteftybit with a high coefficient of thermal expansion, ~ ge paart'mit a low anisotropic ratio * the smaller

as X ₉ HnI is aij & ewinaea. ^, «, K, * ·

'' ■ BADORLGiNAL

It has been found that -hmm * by applying a fresh, carbonized obtained according to an embodiment of the invention Product uses the usual separation and graphitization processes to produce graphite with an increased coefficient of thermal expansion to lead.

According to one embodiment of the invention, a fresh supply is prepared in such a way that a ground carbonized one is produced Product that will be marked below with a carbonaceous binder, such as pitch, mixes in heat, the mixture into shaped products more predetermined Extruded to a size and then subjected to carbonization and graphitization to obtain graphite. During the garboning process the final temperature is preferably something higher than usual (e.g. 95O ° C), and the heating carried out for several weeks.

In order to produce this carbonated product, according to the invention a non-caloined peoh, petroleum or a other residue coke, preferably pure petroleum coke, ground to a predetermined fineness specified below and then hot with a carbonaceous binder, vie pitch or resin, mixed and then put on an expedient Cross-son size pressed. The store made in this way is then fired at an elevated temperature, the finderatura practically identical with respect to of the total storage volume. Since «end-of-term surgery

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differential should therefore be in the carbonized product as low as possible and preferably not above 50 ° G. lie. The carbonized product obtained is then broken to obtain a grist of various particle sizes, which is used to produce the fresh Stock for carbonization and graphitization in order to Production of the graphite according to the invention can be used can.

According to the process of the present invention, graphite is produced by making a fresh stock by mixing in the heat of a cracked carbonized product with a carbonaceous binder such as pitch or resin, extrusion molding the fresh stock of this mixture, and then the shaped product of carbonization and graphitization subjecting to prepare a graphite, wherein the for the manufacture of the fresh stock of the specified mixture carbonized product used a quantity of volatile components of less than 8 wt.% and being prepared in such a way that at At elevated temperature, a carbonizable deformed stock is carbonized, which in turn has been obtained in such a way that a hot mixture of crushed uncalcined coke and a carbonaceous binder has been extruded, and the final temperature of this carbonizable deformed stock during the carbonization practically the same within the entire volume of this carbonizable deformed pre-

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rates is. If the coke used to produce the carbonizable deformed stock has such a degree of fineness that the end graphite has a coefficient of thermal expansion with the grain of less than 3.0 χ 10 ~ / ° C (20-100 ° C), then the invention has Graphite an anisotropic ratio of a coefficient of thermal expansion across the grain to the coefficient of thermal expansion with the grain of less than X, 3x1,

The graphite according to the invention has a specific elec-

-4 tric resistance which is not greater than 12 χ 10 ″ ″ ⁶ / ° C (preferably greater than 5.5 x 10 "/ ⁰ C), and at which the ratio of the thermal expansion coefficient (20 - 100 ° C) across the grain to the thermal expansion coefficient (20 - 100 ° C) with the grain is no greater than 1.3: 1 is.

In the drawing show:

Fig. 1 is a diagram showing the change in thermal

illustrates expansion coefficients with the grain !, jwwm himself the volatile content of the carbonated product Component Changes, and

Fig. 2 is a graph showing the change in the coefficient of thermal expansion verim & ohmulioht with the grain, when the fineness of the starting coke

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changes.

The curves on which the graphs are based experimental values show a ratio of the coefficient of thermal expansion in each case across the "grain to the coefficient of thermal expansion with the grain from 1 to j5.

The curve in Pig. 1 was obtained in the following way:

Sticks with a diameter of 1.9 cm were made from fresh, uncalcined Shell H2OO coke meal, 98 % of which now passed through a sieve with a mesh size of 0.074; the coke meal was mixed by mixing at 160 ° C. with coal tar pitch, which had a softening point of 100 ° C., and the mixture was shaped into rods in a hydraulic extruder, which had a cylinder diameter of 5.72 cm. Groups of 15 * 24 cm long rods with a diameter of 1.9 cm were fired at an hourly temperature increase of 50 ° C up to a final firing temperature between 150 ° and 1000 ° C. Each group was crushed to obtain the filler for a particular deformation. The groups had a volatile content of between 0.3 and 7.0 % . In any case, were

Chopsticks'.

the S crushed and ground until 55 % went through an illegal with a clear Masoheriwoite of 0.074 mm and, as stated above, contributed to the deformation with olnem

BATH ORIGINAL

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100 C softening coal tar pitch bound. The chopsticks were then packed in coke particles and then fired at an hourly temperature increase of 50 ° G to 1000 ° C and finally by heating to 3000 ° C for 3 hours in graphitized a graphite resistance furnace tube. The coefficient of thermal expansion with the grain was measured and graphed entered above the volatile component.

The curve of FIG. 2 was obtained in the following way: Aliquots of fresh, uncalcined H200 coke were comminuted and ground to various particle sizes in such a way that from up to 98 % passed through a sieve with a mesh size of 0.07 mm . The various aliquots were used to prepare powder sticks as described with reference to FIG. They were all fired at a hourly temperature increase of 50 ° C to 1000 ⁰ C (volatiles about 0.8 ^), and then crushed and ground to a flour, so that 55% passes through a sieve having a mesh width of 0.07 * 1- mm went. As indicated with the aid of curve 1, the flour was then bound again into sticks with a diameter of 1.9 cm by means of a coal tar pitch which softened at 100.degree. The sticks were fired at a temperature increase of 50 ° C per hour up to 1000 ° C and then graphed at; '; 000 ° G for 3 hours. The gemesisene, with iem grain lino ar υ thormUJcho iixpnnslonskoeff iiaient was about 'isn Pt ¹ O-liHlt do ·., Üt'ijnrtUn ;! I ph m uiuhtunLolniorbor Koke ε _; ι ..p

70 BATH

entered through a sieve with a clear mesh width of 0.074 mm went.

In the manufacture of the graphite of the invention, the fineness to which the uncalcined coke is ground must be such that it enables the coefficient of thermal expansion (20-100 G) with the grain in the graphite produced from the carbonized product to be equal to or greater than 5.0 x 10 "/ ° C. If the values are greater than 5.5 χ ΙΟ" / C or even 4.0 χ 10 / C are, then the fineness should generally be such that at least 98 % of the coke passes through a sieve with a mesh size of 0.074 mm. This percentage can of course be below 98 % if lower fourths are desired for the coefficient of thermal expansion with the grain, or it can be above 98 * p ; provided that the milled material is not so fine that mixing and extrusion are unduly difficult.

Any binder can be used as a binder, which is suitable for the Production of graphite is known, but for the purposes of nuclear energy a pitch of high purity is preferred, which has the smallest amounts of substances that have a high neutron absorption own.

The volatile part of the carbonized product affects the thermal expansion coefficient of the end product,

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in that higher contents of volatile parts result in higher thermal expansion coefficients. However, the higher the salary of volatile substances, the greater the shrinkage in the manufacture of the finished product and the greater also the difficulty of making a finished product of a certain size. The highest permissible content of volatile Substances in the carbonized product is therefore determined by the size of the final product, but it should be as high as possible to achieve a high final value of the coefficient of thermal expansion. The exact height can be in can be determined in each case by a simple experiment.

The uncalcined coke used as the starting material for the production of the carbonized material should preferably be of high purity. It has surprisingly been found that acicular petroleum coke of high purity, when processed according to the method of the present invention, results in a graphite which has the desired improved properties. Such a high-purity needle petroleum coke, if it is directly subjected to the usual calcination, deformation, carbonization and graphitization, leads to a graphite with physical properties that are different from and less than the properties of the graphite obtained according to the present invention, especially what the Use for nuclear energy is concerned. According to a preferred embodiment of the present invention, a highly pure starting material is used for the production of graphite with the desired properties, so that

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sicfreine special cleaning for the production of atomic graphite superfluous =, precautionary measures are self-evident required. To ensure that contamination of the product does not occur during graphitization. As can be seen from Examples 4 and 5 ^ can

how
other cokes ^ al · © Peohkoks _; rait success can be used for the method of the invention.

The invention is described in the examples? Parts are parts by weight unless otherwise specified is.

example 1

Uncalcined coke, as it is sold by Shell under the designation H 200, was ground in a laboratory Raymond device to a fineness such that 99 % passed through a sieve fabric with a mesh size of 0.07 mm. This flour was then mixed at a temperature of 160 ° C with a coal tar pitch with a melting point of 100 ° 0! the mixture had the following composition:

99 $ of a flour that went through a sieve with a mesh size of QfQ ^ k mm 200 g

Bad luck as a binder @ l 95 &

Oil as lubricant 11 β

& em M $, bqUgu iw-? üq da® hoißo Ooin & seii in ösm ZyMnte

pi Ά ■: '-''- ■: ■ - f ' · I t $ ij.

BAD OBfGfNAL

to a laboratory hydraulic extruder having a cylinder 5.72 cm in diameter with a fitting 1.9 cm in diameter inserted therein. The rods produced with a diameter of 1.9 cm and a length of 15.24 cm were filled in Stahlkasetten which were filled with a fine Kokspackung, and heated to a temperature of 7OO ⁰ C over a period of HStunden. The fired sticks had $ 5.8 volatiles. The fired sticks were then crushed and ground to a flour, 55 % of which went through a sieve fabric with a mesh size of 0.07 mm. The flour was then mixed with pitch melting at 100 ° C at a temperature of 160 ° C? the mixture had the following composition:

Flour, 55 % of which passed through a sieve fabric with a mesh size of 0.074 mm, 200 g

Pitch as a binder 88 g

Oil as a lubricant 8 g

The mixture was in the extruder specified above stranded into chopsticks and the chopsticks were then opened 1000 ° C for a period of 12 hours in one Fired steel case. The burned sticks were then. in a graphite-made resistance furnace

given the tube and heated to 3000 ° C for 3 hours. The graphitized rods had the following measurements determined properties;

- 10 -

"! c, η / Π / 1 / ^r ) 0

BAO

thermal expansion coefficient ^

(20 - 100 C) (in the direction of the grain) 4.10 χ ΙΟ "cm / cm / ° C,

electrical resistance 9 * ^ 8 χ 10 ~ Ohm / cm.

Example 2

It was another set of 15 * 24 cm long rods described with a diameter of 1.9 c ^m in exactly the same manner as in Example 1 except that the final temperature of the first firing at 600 ° G was. This resulted in a volatile material content of 4.7 % in the fired rods. After crushing and grinding to a fineness of 55 %, based on a mesh size of 0.074 mm, rods with a diameter were obtained using the following mixture 1.9 cm extruded:

of the

Flour, 55 % *. 200 g passed through a sieve fabric with a mesh size of 0.074 mm

Pitch, melting point 100 ° C 95 g

Lubricating oil type Gg

After firing auf'lOOO ⁰ 0 and graphitization on 3ooo ⁰ C had the sticks following Eigensohaften:

thermal expansion coefficient r

(20 - 100 C) (in the direction of the grain) 4.40x10 cm / orn / C

-4 electrical resistance 9.32x10 Ohm om.

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Example 3

Uncalcined petroleum coke, which had 8 % volatile constituents, was crushed until 98 % passed through a mesh with a mesh size of 0.074 mm. Ε 70.5% and 29.5% of this Koksmehle coal tar before pe s were fee4A in a Sigma Blade - mixer to a temperature of I65 ⁰ C heated together with a small amount of a known Strangpreßgleitmittels. The mixture obtained was extruded at 100 ° C. to give 91.4 cm long rods with a diameter of 7 * 62 cm. The sticks were then fired to a temperature of 1000 ° C in an oil-fired oven of conventional design.

The carbonized product had a volatile content Substances of 0.8 #j it was crushed and a fineness

1.52 * deB grain achieved with a maximum particle size of tm . 79.6 % of this flour and 20.4 Jt of a coal tar pee, as stated above, were mixed hot and pressed into sticks with a length of 91.4 cm and a diameter of 15.24 cm heated oven of the usual type fired to 730 ° C and then graphitized by heating in a conventional axison oven to about 2,800 ° C. The graphite obtained had the following properties

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Average thermal

Expansion coefficient

(20 - 100 G) (in the direction of the c

Grain) 5.62 χ 10 "cm / cm / ° C

(against the grain) 3 * 93 x 10 "° cm / cm / C

average more specific

Resistance "-4

(in the direction of the grain) 8 * 10 χ 10 ~ ^ 0hm cm

(against the grain) 8.80 c 10 "0hm cm

anisotropic ratio of thermal expansion coefficient

the corn _ι

thermal expansion coefficient in the direction of the grain

For comparison purposes, the same petroleum coke has been used so far caloiniert that it has a volatile content of

had less than 0.5 % , and then ground so far that it had a normal grain fineness with a maximum particle size

1.524 ^menl

size of 4 mm, and the received »in the same As stated above, hot mixed with the same pitch, the mixture extruded, pressed, calcined and graphitized. The graphite obtained had the following properties!

average thermal

Expansio-efficient

; 20 - ΐφ ^ο C) _t -6 / yo

in proportion to the grain) 0.71 x 10 _-6 om / om / ₀ C

[against the grain) f #? 2 χ 10 om / om / C

(iurohiohnifctioifr sp # cifieoher

AgainstAnd ^ "4

(in Rialitiung dee Kornes) 7 #? 9 * 10 h ohm cm

(against this grain) 12.4? χ 10 ohms cm

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⁴ H.

thermal expansion coefficient

anisotropic ratio cient against the grain

thermal expansion coefficient in the direction of the grain

Example 4

Using ordinary pitch coke with a volatile matter content of 4.8 % , rods with a diameter of 1.9 cm were made of green coke powder, 98 % of which passed through a sieve mesh with a mesh size of 0.074 mm, and coal tar pitch. After firing at 1000 ° C., as indicated above, the sticks were comminuted so that a flour was obtained, 55 % of which passed through a sieve fabric with a mesh size of 0.074 mm. From this flour, again using coal tar pitch, sticks with a diameter of 1.9 cm were made, packed in coke particles and heated to 1000 ° C. After Graphitized on 5OOO ⁰ C for j5 hour the graphite had a linear thermal expansion coefficient with the grain of 4.7 x 1 ° ~ / C · However, if the Peohkoks in the usual manner and caloiniert Stäbohen with a Durohmesser 1.9 om were prepared, calcined and graphitized using a flour of the fineness specified above and coal tar pitch, the graphite had a coefficient of thermal expansion linear with the grain of 2.5 x 10 "/ ° C.

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Example 5

In the same way, non-calcined gilsonite carbon, a coke made from natural asphalt, when treated according to the invention, gave rods with a thermal expansion coefficient in the direction of the grain of 4.7 x 10 ~ / ° C when processed in a known manner, a thermal expansion coefficient of 5.9 χ 10 ~ / ⁰ C in the direction of the grain.

Example 6

In a further experiment, graphite was produced on a large scale using uncalcined Shell H200 coke and a green coke meal was used, 98 % of which passed through a sieve mesh with a mesh size of 0.074 mm. The carbonized product had 1.7 % volatiles. Pieces with a length of 91.4 cm and a diameter of 15.24 cm were first produced using the green flour and a coal tar pecb. By mixing and extrusion molding in a known manner. The stock was then fired in a, with ül fired plant up to obtain a final temperature of 775 ⁰ C, then crushed and ground to the filler in the appropriate fineness "for the final forming of blocks having a diameter of 35.56 cm? These blocks were made with the help of a coal tar pitch that was customary for electrodes, burned in an oil-fired furnace and finally graphitized in an eight-ion furnace

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Grain linear thermal expansion coefficient of 5.8x ΙΟ "/ ⁰ C (20 - 100 ° C) and against the grain linear expansion coefficient of 4.15 χ 10 * / ⁰ C (20 - 100 ° C). The ratio of the thermal expansion coefficient transversely to the grain to in the direction of the grain was 1.15

Claims

■ -.16-

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Claims (10)

Claims 1. A process for producing a graphite, in which a fresh (green) supply is produced by hot mixing of a carbonized product with a carbonaceous binder, the mixture is extruded to produce a shaped product and then the shaped product is carbonized and graphitized, characterized in that the stock mixture (green) for the preparation of the fresh used carbonized product has a volatiles content of less than 8 wt.% has and is manufactured in such a way that carbonized a carboxylic! slerbaren deformed stock at an elevated temperature, by Strangverpressen a hot mixture of comminuted uncalculated coke and a carbonaceous binder has been formed, the final temperature of the carbonizable deformed stock being practically the same during its carbonization within the entire volume of this carbonizable deformed stock. 2. The method according to claim 1, characterized in that the degree of fineness of the crushed niohtoaleinierten, for the production of the carbonizable deformed supply ver used coke eo is chosen that the thermal expansion »ioniko coefficient in the direction of the grain of the graphite produced not less than 3.0 χ 10 ' ⁶ / ° C (20 - 100 ° C). •. ' BAD ORSGINAL -17 - 3 »Method according to claim 1 or 2, characterized in that that the punity of the crushed uncalcined coke is such that at least y8. $ through a sieve fabric with a mesh size of 0.074 mm walk. 4. The method according spoke 1, 2 or J5, characterized in that that the final temperature differential of the carbonizable deformed stock is not greater than 50 ° C. 5. The method according to any one of claims 1-4, characterized in that the degree of punity of the crushed uncalcined coke, which is used for the production of the carbonized product, and the volatile content of the carbonized product is chosen so that the graphite as a final product a thermal expansion coefficient in the direction of the grain of \ than 3.5 x 10 ^"6 / ° C more. 6. The method according to claim 5, characterized in that that the Peinheitsgrad and the volatile content is chosen so that the graphite has a thermal expansion coefficient in the direction of the grain that is greater than _ _{6 / O} (20-100 ⁰ C)
4.0 χ 10 ^D / C '. 7. The method of NaOH in any of claims 1-6, gekennzeiohnet characterized in that the binder used for the preparation of the graphite 1st PEOH a high purity because · having a Mindestraenge to Subetaiusen having a neutron absorption höht b ** itien. _ _Αί) qfuGINW- 8. Graphite characterized by an electrical resistance not greater than 12 χ 10 "" '*' ohm cm thermal expansion coefficient (20 - 100 ° C) in Rieh- * -f> et ^na ^ processing of the grain of not less than 3.0 χ 10 "/ C / and at which the ratio of the coefficient of thermal expansion (20-100 ° C) across the grain to the coefficient (20 - 100 ° C) in the direction of the grain is not greater than 1.3: 1. 9. graphite according to claim Ü, characterized by a thermal expansion coefficient (20 - 100 ° C), which is greater than 3.5 xlö'V C. 10. graphite according to claim 9, characterized by an expansion coefficient (20-100 ° C) in the direction of the grain is greater than 4.0 χ 10 / ° C. - 19 - 0Q-9849 / U70