EP0177981B1 - Process for making high-power graphite electrodes - Google Patents
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- EP0177981B1 EP0177981B1 EP85200993A EP85200993A EP0177981B1 EP 0177981 B1 EP0177981 B1 EP 0177981B1 EP 85200993 A EP85200993 A EP 85200993A EP 85200993 A EP85200993 A EP 85200993A EP 0177981 B1 EP0177981 B1 EP 0177981B1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B7/00—Heating by electric discharge
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- H05B7/08—Electrodes non-consumable
- H05B7/085—Electrodes non-consumable mainly consisting of carbon
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- the invention relates to a method for producing high-performance graphite electrodes for the production of electrical steel from anisotropic needle coke using an electrode binder by mixing the components, shaping the green electrode, firing and graphitizing the electrode.
- the quality of graphite electrodes is determined by physical parameters such.
- Modern high-performance electrodes are characterized, among other things, by a high specific current load.
- extreme specific current loads are only achieved if the graphite material has a particularly high electrical conductivity with the appropriate strength.
- the initial coke quality had to be improved; So-called needle cokes with a very low coefficient of thermal expansion (CTE) of less than 1 - 10-6K- 1 have been developed.
- Pretreated coal tar pitch has proven to be a particularly suitable raw material for such needle coke with a low coefficient of thermal expansion.
- coal tar pitch needle coke electrodes show a stronger puffing, which cannot be significantly inhibited by Fe 2 0 3 .
- this patent application describes a method to minimize the puffing of graphite electrodes from pitch needle coke without the additional use of inhibiting agents.
- this application places particular emphasis on an extremely low-ash electrode coke, which also has a specifically set degree of crystalline orientation.
- the crystalline degree of orientation of the coke is achieved through the selection of suitable raw materials and a coking process adapted to the raw material.
- the irreversible deformation ( ⁇ I / I 0 ) of standard pitch needle cokes is reduced with optimized needle cokes from 0.9% to less than 0.2% (measured in the longitudinal direction).
- the object was therefore to develop a process for producing high-performance graphite electrodes from anisotropic needle cokes using an electrode binder by mixing the two components, shaping the green electrode, firing and graphitizing the electrode, in which the properties of the needle coke are fully utilized so that a graphite electrode with optimal properties is obtained.
- This object is achieved in that 70 to 80 parts by weight of an anisotropic needle coke with 20 to 30 parts by weight of the binder, which has an atomic C / H ratio - the quinoline-insoluble of a maximum of 3: 1, an ash value of 0 , 1 wt .-% or less and has a softening point of 80 to 120 ° C, are mixed homogeneously.
- High-performance graphite electrodes are usually made from anisotropic filler coke and a largely isotropically coking binder. Therefore, a fired electrode body consists morphologically of two phases with different crystallinity. This results in divergent physical properties that lead to opposite effects at the phase interfaces.
- anisotropic filler cokes preferably coal tar pitch needle coke
- anisotropically coking binders to give shaped electrodes.
- the puffing behavior is also effectively improved. The more the puffing tendency of an anisotropic coke, the more pronounced is the puffing-damping effect of an anisotropic ash-free binder coke in the electrode body.
- An anisotropic binder coke structure in the electrode body improves the electrical conductivity and the modulus of elasticity with approximately the same breaking strength.
- the anisotropically coking binder preferably with 0.01 to 0.1% by weight of ash, is preferably produced in the usual way solely from coal tar pitch.
- the ash removal is carried out by methods known per se, such as centrifuging, separating, filtering or promoter-accelerated settling (settling) at elevated temperature.
- Aromatic petro- or carbo-derived hydrocarbon fractions can be added to the coal tar pitch to facilitate the separation of the ash formers.
- Another important requirement for an anisotropically coking binder is the atomic C / H ratio of the quinoline-insoluble (QI). It should be in the range of 2.3: 1 to 3.0 1. Higher C / H ratios lead to isotropic binder cokes.
- the C / H ratio in the binder is preferably 1.85: 1 to 2.04: 1 with a QI content of preferably 10 to 20% by weight.
- Three needle cokes with different degrees of pre-orientation and for comparison an isotropic pitch coke are processed according to the invention with an anisotropically coking electrode binder and for comparison with a conventional isotropically coking electrode binder in a known manner to shaped body pastes and converted into fired electrodes.
- the analysis data of the electrodes graphitized under the same conditions clearly show the advantages of electrode production in the combination of puffing coke with anisotropically coking binder.
- the characteristics of the coke are shown in Table 1.
- the binders used are characterized in Table 2.
- the pastes produced according to the recipe given in Table 3 are extruded into green shaped bodies by known technology and fired under identical conditions at 1000 ° C. and then graphitized to 2800 ° C.
- the important characteristics of the fired electrodes are shown in the upper part of Table 4, the characteristics of the graphitized electrodes are in the lower part of Table 4.
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Description
Die Erfindung bezieht sich auf ein Verfahren zur Herstellung von Hochleistungs-Graphitelektroden für die Elektrostahlerzeugung aus anisotropen Nadelkoksen unter Verwendung eines Elektrodenbindemittels durch Mischen der Komponenten, Formen der grünen Elektrode, Brennen und Graphitieren der Elektrode.The invention relates to a method for producing high-performance graphite electrodes for the production of electrical steel from anisotropic needle coke using an electrode binder by mixing the components, shaping the green electrode, firing and graphitizing the electrode.
Die Qualität von Graphitelektroden wird durch physikalische Meßgrößen wie z. B. Wärmeausdehnungskoeffizient, spezifische elektrische und Wärmeleitfähigkeit, Aschewert, Spurenelemente und Dichte charakterisiert.The quality of graphite electrodes is determined by physical parameters such. B. Characterized thermal expansion coefficient, specific electrical and thermal conductivity, ash value, trace elements and density.
Moderne Hochleistungselektroden zeichnen sich u. a. durch eine hohe spezifische Strombelastung aus. Extreme spezifische Strombelastungen werden jedoch nur erreicht, wenn das Graphitmaterial bei entsprechender Festigkeiteine besonders hohe elektrische Leitfähigkeit besitzt. Um die Graphitelektrode weniger empfindlich gegen die im Betrieb unvermeidbaren großen radialen Temperaturgradienten zu machen, mußte die anfängliche Koksqualität verbessert werden ; es wurden sogenannte Nadeikokse mit sehr geringem Wärmeausdehnungskoeffizienten (CTE) von weniger als 1 - 10-6K-1 entwickelt. Als besonders geeigneter Rohstoff für derartige Nadelkokse mit niedrigem Wärmeausdehnungskoeffizienten hat sich vorbehandeltes Steinkohlenteerpech erwiesen.Modern high-performance electrodes are characterized, among other things, by a high specific current load. However, extreme specific current loads are only achieved if the graphite material has a particularly high electrical conductivity with the appropriate strength. In order to make the graphite electrode less sensitive to the large radial temperature gradients which are unavoidable in operation, the initial coke quality had to be improved; So-called needle cokes with a very low coefficient of thermal expansion (CTE) of less than 1 - 10-6K- 1 have been developed. Pretreated coal tar pitch has proven to be a particularly suitable raw material for such needle coke with a low coefficient of thermal expansion.
Aus diesem Rohstoff können in Verbindung mit einem geeigneten Verkokungsverfahren (DE-OS 30 35 593) Nadelkokse mit bisher nicht erreichtem niedrigen CTE erhalten werden. So konnte der CTE von Graphittormkörpern von bisher eingesetztem hochwertigen Petrol-Nadelkoks im Temperaturbereich 20-200 °C um 0,7 x 10―6K―1 durch Verwendung von hochwertigen Pech-Nadelkoksen auf 0,1 x 10―6K―1 verringert werden. Die großtechnische Verwendung von Nadelkoksen besonders auf der Basis von Steinkohlenteerpech als Graphitelektrodenrohstoff wird jedoch wegen einer negativen Begleiteigenschaft, des « Puffing •, beeinträchtigt.In conjunction with a suitable coking process (DE-OS 30 35 593), needle coke with a previously unattained low CTE can be obtained from this raw material. The CTE of graphite bodies from previously used high-quality petroleum needle coke in the temperature range 20-200 ° C was reduced by 0.7 x 10― 6 K― 1 to 0.1 x 10― 6 K― 1 by using high-quality pitch needle cokes will. However, the large-scale use of needle coke, particularly based on coal tar pitch as a graphite electrode raw material, is impaired because of a negative accompanying property, “puffing”.
Technisch erzeugte Nadelkokse durchlaufen während einer Hochtemperaturbehandlung bis ca. 3000°C die Modifikationsänderung vom gebrannten Kohlenstoffkörper zum Elektrographit. Dabei erfahen sie neben der reversiblen Verformung infolge Wärmeausdehnung auch eine irreversible Längenänderung, die bis zu 4,5 % betragen kann, das sogenannte Puffing.Technically produced needle coke undergoes the modification change from the burned carbon body to electrographite during a high temperature treatment up to approx. 3000 ° C. In addition to the reversible deformation due to thermal expansion, they also experience an irreversible change in length, which can be up to 4.5%, known as puffing.
Durch das Puffing werden die wichtigsten physikalischen Kenngrößen einer Graphitelektrode wie z. B. die Dichte und davon abhängig auch die elektrische und die Wärmeleitfähigkeit sowie die mechanische Festigkeit nachteilig verändert.By puffing the most important physical parameters of a graphite electrode such. B. the density and depending on it, the electrical and thermal conductivity and the mechanical strength disadvantageously changed.
Das Puffing bei Petroi- wie bei Pech-Nadelkoksen tritt in unterschiedlichem Maße auf.Puffing in petroi and pitch needle cokes occurs to different degrees.
Für die bisher zu Elektrographit verarbeiteten petrostämmigen Nadelkokse ist bekannt, daß die irreversible Volumenvergrößerung mit dem Schwefelgehalt im kalzinierten Koks korrelierbar ist. Durch die Zugabe von z. B. Eisenoxid bei der Herstellung der Formkörperpaste ist das Puffing weitgehend inhibierbar.For the petro-stemmed needle coke processed up to now to electrographite, it is known that the irreversible volume increase can be correlated with the sulfur content in the calcined coke. By adding z. B. iron oxide in the manufacture of the molding paste, the puffing is largely inhibitable.
Dieser Zusammenhang gilt jedoch nicht in gleichem Maße für die ebenfalls als Rohstoff für Elektrographit einsatzfähigen Steinkohlenteerpech-Nadelkokse. Bei gleichem Schwefelgehalt zeigen Steinkohlenteerpech-Nadelkoks-Elektroden ein stärkeres Puffing, das sich durch Fe203 nicht signifikant inhibieren läßt.However, this connection does not apply to the same extent for the hard coal tar pitch coke that can also be used as a raw material for electrographite. With the same sulfur content, coal tar pitch needle coke electrodes show a stronger puffing, which cannot be significantly inhibited by
In den Preprints der « 16th Biennial Conference of Carbon (S. 595-596) wird ein Verfahren beschrieben, Puffing an Petrol- und Steinkohlenteerpech-Nadelkoks-Formkörpern durch Zugabe von 1-2 % Cr203 zu inhibieren. Dieses Verfahren ist wirtschaftlich kaum realisierbar.In the preprints of the “ 1 6th Biennial Conference of Carbon (pp. 595-596) a method is described to inhibit puffing on petroleum and coal tar pitch coke moldings by adding 1-2%
Alle übrigen bekannten Verfahren zur Puffing-Inhibierung von Graphitelektroden verwenden ebenfalls anorganische Inhibierungsmittel, vorzugsweise Oxide.All other known methods for puffing inhibition of graphite electrodes also use inorganic inhibitors, preferably oxides.
Dabei geht man von der Vorstellung aus, daß sich neben den im Petrolkoks hauptsächlich vorkommenden Schwefelverbindungen auch weitere bisher unbekannte Einlagerungsverbindungen bei Erreichen individueller Zersetzungstemperaturen spontan in gasförmige Komponenten umwandeln und einen inneren Überdruck in den Kokspartikeln verursachen, der die Kristallebenen des Kohlenstoffs irreversibel auseinandertreibt. Beim Zusatz von Inhibierungsmitteln bilden sich intermediäre Phasen, die im puffinggefährdeten Temperaturbereich beständig sind.One starts from the idea that, in addition to the sulfur compounds mainly found in petroleum coke, other previously unknown intercalation compounds spontaneously convert into gaseous components when individual decomposition temperatures are reached and cause an internal overpressure in the coke particles that irreversibly disperses the crystal levels of the carbon. When inhibitors are added, intermediate phases are formed that are stable in the temperature range at risk of puffing.
Durch die bekannte Art der chemischen Puffing-inhibierung wird aber der Aschewert des Elektrographits unerwünscht erhöht.However, the ash value of electrographite is undesirably increased by the known type of chemical puffing inhibition.
Im Gegensatz dazu wird in dieser Patentanmeldung eine Methode beschrieben, das Puffing von Graphitelektroden aus Pech-Nadelkoks ohne zusätzliche Verwendung von Inhibierungsmitteln zu minimieren.In contrast, this patent application describes a method to minimize the puffing of graphite electrodes from pitch needle coke without the additional use of inhibiting agents.
Im Gegensatz zu den bekannten Verfahren wird in dieser Anmeldung besonderer Wert auf einen extrem aschearmen Elektrodenkoks gelegt, der außerdem einen gezielt eingestellten kristallinen Orientierungsgrad aufweist. Der kristalline Orientierungsgrad des Kokses wird erreicht durch die Auswahl geeigneter Rohstoffe und ein dem Rohstoff angepaßtes Verkokungsverfahren. Die irreversible Verformung (ΔI/I0) von Standard-Pech-Nadelkoksen verringert sich bei optimierten Nadelkoksen von 0,9 % auf weniger als 0,2 % (in Längsrichtung gemessen).In contrast to the known methods, this application places particular emphasis on an extremely low-ash electrode coke, which also has a specifically set degree of crystalline orientation. The crystalline degree of orientation of the coke is achieved through the selection of suitable raw materials and a coking process adapted to the raw material. The irreversible deformation (ΔI / I 0 ) of standard pitch needle cokes is reduced with optimized needle cokes from 0.9% to less than 0.2% (measured in the longitudinal direction).
Mit der Entwicklung von hochwertigen Kokstypen allein wird jedoch das in den Rohstoffen liegende Qualitätspotential noch nicht voll genutzt.However, the development of high-quality coke types alone does not fully utilize the quality potential in the raw materials.
Es bestand daher die Aufgabe, ein Verfahren zur Herstellung von Hochleistungsgraphitelektroden aus anisotropen Nadelkoksen unter Verwendung eines Elektrodenbindemittels durch Mischen der beiden Komponenten, Formen der grünen Elektrode, Brennen und Graphitieren der Elektrode zu entwickeln, bei dem die Eigenschaften der Nadelkokse voll genutzt werden, so daß eine Graphitelektrode mit optimalen Eigenschaften erhalten wird.The object was therefore to develop a process for producing high-performance graphite electrodes from anisotropic needle cokes using an electrode binder by mixing the two components, shaping the green electrode, firing and graphitizing the electrode, in which the properties of the needle coke are fully utilized so that a graphite electrode with optimal properties is obtained.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß 70 bis 80 Gew.-Teile eines anisotropen Nadelkokses mit 20 bis 30 Gew.-Teilen des Bindemittels, welches ein atomares C/H-Verhältnis - des Chinolinunlöslichen von maximal 3 : 1, einen Aschewert von 0,1 Gew.-% oder weniger und einen Erweichungspunkt von 80 bis 120 °C aufweist, homogen gemischt werden.This object is achieved in that 70 to 80 parts by weight of an anisotropic needle coke with 20 to 30 parts by weight of the binder, which has an atomic C / H ratio - the quinoline-insoluble of a maximum of 3: 1, an ash value of 0 , 1 wt .-% or less and has a softening point of 80 to 120 ° C, are mixed homogeneously.
Hochleistungsgraphitelektroden werden üblicherweise aus anisotropem Füllerkoks und einem weitgehend isotrop verkokenden Bindemittel hergestellt. Daher besteht ein gebrannter Elektrodenkörper morphologisch aus zwei Phasen mit unterschiedlicher Kristallinität. Hieraus resultieren divergierende physikalische Eigenschaften, die an den Phasengrenzflächen zu gegenläufigen Effekten führen.High-performance graphite electrodes are usually made from anisotropic filler coke and a largely isotropically coking binder. Therefore, a fired electrode body consists morphologically of two phases with different crystallinity. This results in divergent physical properties that lead to opposite effects at the phase interfaces.
Bereits während des Brennprozesses ergeben sich unterschiedliche Wärmedehnungen zwischen Füller- und Binderkoks, die zu Relativbewegungen führen, die Riß- und Ablöseerscheinungen zur Folge haben. Wegen des normalerweise höheren Grades an Spurenbestandteilen sind Elektrodenbinder Fremdatomemittenten, die vor und während der Brennphase vorzugsweise in das anisotrope Füllerkorn diffundieren. Bei der nachfolgenden thermischen Umwandlung des aus zwei unterschiedlichen Kristallphasen bestehenden Kohlenstoffkörpers in Graphit ist die Rekristallisation im höher vororientierten Füllerkoks früher abgeschlossen als im isotropen Binderkoks. Bereits umgewandelte Füllerkoksbereiche sind der bei höheren Temperaturen erfolgenden Fremdatomdiffusion ausgesetzt und zeigen irreversibles Puffing. Verwendet man an Stelle der bisher gebräuchlichen Petrol-Nadelkokse einen besser vororientierten Steinkohlenteerpech-Nadelkoks, werden die beschriebenen Effekte vor allem durch die früher abgeschlossene Graphitierung des Füllerkokses noch verstärkt.Already during the firing process, there are different thermal expansions between filler and binder coke, which lead to relative movements that cause cracking and peeling. Because of the normally higher level of trace components, electrode binders are foreign atom emitters, which diffuse into the anisotropic filler grain preferably before and during the firing phase. In the subsequent thermal conversion of the carbon body consisting of two different crystal phases into graphite, the recrystallization in the more pre-oriented filler coke is completed earlier than in the isotropic binder coke. Filler coke areas that have already been converted are exposed to foreign atom diffusion at higher temperatures and show irreversible puffing. If, instead of the previously used petroleum needle coke, a better pre-oriented coal tar pitch needle coke is used, the effects described are enhanced, above all, by the graphitization of the filler coke, which was completed earlier.
Verbesserte morphologische Eigenschaften des polykristallinen Kohlenstoffkörpers werden überraschenderweise erreicht, wenn anisotrope Füllerkokse, vorzugsweise Steinkohlenteerpech-Nadelkokse, mit weitgehend aschefreien, ebenfalls anisotrop verkokenden Bindemitteln zu Elektroden-Formkörpern verarbeitet werden. Neben anderen meßbaren Kenngrößen wird auch das Puffingverhalten wirksam verbessert. Je stärker die Puffingneigung eines anisotropen Kokses, um so ausgeprägter ist die puffingdämpfende Wirkung eines ebenfalls anisotropen aschefreien Binderkokses im Elektrodenkörper.Improved morphological properties of the polycrystalline carbon body are surprisingly achieved if anisotropic filler cokes, preferably coal tar pitch needle coke, are processed with largely ash-free, likewise anisotropically coking binders to give shaped electrodes. In addition to other measurable parameters, the puffing behavior is also effectively improved. The more the puffing tendency of an anisotropic coke, the more pronounced is the puffing-damping effect of an anisotropic ash-free binder coke in the electrode body.
Korreliert man die mittlere wahre Dichte p des bei 1 300 °C kalzinierten Füllerkokses mit dem Anteil der irreversiblen Verformung 01/lo beim Graphitieren der Elektrode, so findet man zwei charakteristische Kurvenverläufe in Abhängigkeit von der Kristallmodifikation des Bindemittelkokses, wie in Fig. 1 dargestellt.Correlating the mean true density p of the filler coke calcined at 1300 ° C with the proportion of irreversible deformation 01 / l o when graphitizing the electrode reveals two characteristic curves depending on the crystal modification of the binder coke, as shown in Fig. 1 .
Durch ein anisotropes Binderkoksgefüge im Elektrodenkörper werden bei etwa gleicher Bruchfestigkeit die elektrische Leitfähigkeit und der E-Modul verbessert.An anisotropic binder coke structure in the electrode body improves the electrical conductivity and the modulus of elasticity with approximately the same breaking strength.
Das anisotrop verkokende Bindemittel mit vorzugsweise 0,01 bis 0,1 Gew.% Asche wird in üblicher Weise vorzugsweise allein aus Steinkohlenteerpech hergestellt. Die Entaschung erfolgt dabei durch an sich bekannte Verfahren wie Zentrifugieren, Separieren, Filtrieren oder promotorbeschleunigtes Absitzenlassen (Settlen) bei erhöhter Temperatur. Hierbei können dem Steinkohlenteerpech aromatische petro- oder carbostämmige Kohlenwasserstofffraktionen zugesetzt werden, um die Abtrennung der Aschebildner zu erleichtern.The anisotropically coking binder, preferably with 0.01 to 0.1% by weight of ash, is preferably produced in the usual way solely from coal tar pitch. The ash removal is carried out by methods known per se, such as centrifuging, separating, filtering or promoter-accelerated settling (settling) at elevated temperature. Aromatic petro- or carbo-derived hydrocarbon fractions can be added to the coal tar pitch to facilitate the separation of the ash formers.
Eine weitere wichtige Voraussetzung für ein anisotrop verkokendes Bindemittel ist das atomare C/H-Verhältnis des Chinolinunlöslichen (QI). Es sollte im Bereich von 2,3 : 1 bis 3,0 1 liegen. Höhere C/H-Verhältnisse führen zu isotropen Bindemittelkoksen.Another important requirement for an anisotropically coking binder is the atomic C / H ratio of the quinoline-insoluble (QI). It should be in the range of 2.3: 1 to 3.0 1. Higher C / H ratios lead to isotropic binder cokes.
Das C/H-Verhältnis im Bindemittel beträgt vorzugsweise 1,85 : 1 bis 2,04 : 1 bei einem QI-Gehalt von vorzugsweise 10 bis 20 Gew.%.The C / H ratio in the binder is preferably 1.85: 1 to 2.04: 1 with a QI content of preferably 10 to 20% by weight.
Die Erfindung wird anhand der nachfolgenden Beispiele näher erläutert, ohne darauf beschränkt zu sein.The invention is explained in more detail with reference to the following examples, without being restricted thereto.
Drei Nadelkokse mit unterschiedlichem kristallinen Vororientierungsgrad und zum Vergleich ein isotroper Pechkoks werden erfindungsgemäß mit einem anisotrop verkokenden Elektrodenbindemittel und zum Vergleich mit einem herkömmlichen isotrop verkokenden Elektrodenbindemittel in bekannter Weise zu Formkörperpasten verarbeitet und in gebrannte Elektroden überführt. An den Analysendaten der unter gleichen Bedingungen graphitierten Elektroden werden die Vorteile der Elektrodenfertigung in der Kombination von puffenden Koksen mit anisotrop verkokendem Binder deutlich erkennbar.Three needle cokes with different degrees of pre-orientation and for comparison an isotropic pitch coke are processed according to the invention with an anisotropically coking electrode binder and for comparison with a conventional isotropically coking electrode binder in a known manner to shaped body pastes and converted into fired electrodes. The analysis data of the electrodes graphitized under the same conditions clearly show the advantages of electrode production in the combination of puffing coke with anisotropically coking binder.
Die Kenndaten der Kokse sind in Tabelle 1 wiedergegeben. in Tabelle 2 werden die verwendeten Bindemittel charakterisiert. Die gemäß der in Tabelle 3 angegebenen Rezeptur hergestellten Pasten werden nach bekannter Technik zu grünen Formkörpern extrudiert und unter identischen Bedingungen bei 1 000°C gebrannt und anschließend bis 2800°C graphitiert. Die wichtigen Kenndaten der gebrannten Elektroden sind im oberen Teil der Tabelle 4 enthalten, die Kenndaten der graphitierten Elektroden stehen im unteren Teil der Tabelle 4.
Ein Vergleich der Beispiele 1 und 2, 3 und 4 sowie 5 und 6 zeigt deutlich den Einfluß des anisotrop verkokenden Bindemittels auf das Puffing-Verhalten der Elektrode beim Graphitieren. In allen Fällen verringert sich das Puffing vor allem in Längsrichtung um mehr als 70 %. Bei den Nadelkoksen aus Steinkohlenteerpech nimmt das Puffing senkrecht (quer) zur Längsachse der Elektrode um etwa 30 % ab. Bei der Verwendung von Petrolkoks ist dieser Effekt geringer. Gleichzeitig werden die übrigen Kenndaten der Elektrode verbessert. Bei der Verwendung eines isotropen Pechkokses für die Elektrodenherstellung hingegen wirkt sich ein anisotrop verkokendes Bindemittel negativ auf die mechanischen Eigenschaften der Elektrode aus.A comparison of Examples 1 and 2, 3 and 4 and 5 and 6 clearly shows the influence of the anisotropically coking binder on the puffing behavior of the electrode when graphitizing. In all cases, puffing is reduced by more than 70%, especially in the longitudinal direction. With needle coke made from coal tar pitch, the puffing decreases perpendicularly (transversely) to the longitudinal axis of the electrode by about 30%. This effect is less when using petroleum coke. At the same time, the remaining characteristics of the electrode are improved. When using an isotropic pitch coke for the manufacture of electrodes, however, an anisotropically coking binder has a negative effect on the mechanical properties of the electrode.
Hieraus ergibt sich, daß überraschenderweise die Verwendung eines anisotrop verkokenden Bindemittels insbesondere in Verbindung mit Steinkohlenteerpech-Nadelkoksen zur Herstellung von Hochleistungs-Graphitelektroden zu einer Verbesserung der Elektrodeneigenschaften und zu einer Verminderung des Puffing führt.It follows from this that, surprisingly, the use of an anisotropically coking binder, in particular in connection with coal tar pitch needle cokes for the production of high-performance graphite electrodes, leads to an improvement in the electrode properties and to a reduction in puffing.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19843432887 DE3432887A1 (en) | 1984-09-07 | 1984-09-07 | METHOD FOR PRODUCING HIGH-PERFORMANCE GRAPHITE ELECTRODES |
| DE3432887 | 1984-09-07 |
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| Publication Number | Publication Date |
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| EP0177981A1 EP0177981A1 (en) | 1986-04-16 |
| EP0177981B1 true EP0177981B1 (en) | 1988-11-09 |
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| AT515982B1 (en) * | 2014-07-02 | 2018-03-15 | Hubweber Gerhard | Process and plant for the production of carbon bodies |
| CN107840328B (en) * | 2017-11-22 | 2019-10-25 | 大同新成新材料股份有限公司 | A kind of isostatic pressing formed graphite and its production method |
| CN114133753A (en) * | 2021-10-13 | 2022-03-04 | 大同宇林德石墨新材料股份有限公司 | Preparation process of graphite electrode joint bolt |
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| AT196135B (en) * | 1953-04-24 | 1958-02-25 | Vaw Ver Aluminium Werke Ag | Process for the production of continuous electrodes for electric furnaces, in particular for the melt flow electrolysis of aluminum, and carbon blocks for the process |
| AT199383B (en) * | 1956-01-24 | 1958-08-25 | Aluminium Ind Ag | Self-baking, continuous anode for aluminum electrolytic furnaces and processes for their manufacture |
| AT229054B (en) * | 1959-12-03 | 1963-08-26 | Farbwerke Hoechst Aktiengesellschaft Vormals Meister Lucius & Bruening | |
| DE3035593C2 (en) * | 1980-09-20 | 1982-08-26 | Rütgerswerke AG, 6000 Frankfurt | Process for coking high-boiling, aromatic hydrocarbon mixtures to carbon materials with consistent properties |
-
1984
- 1984-09-07 DE DE19843432887 patent/DE3432887A1/en not_active Withdrawn
-
1985
- 1985-06-24 EP EP85200993A patent/EP0177981B1/en not_active Expired
- 1985-06-24 DE DE8585200993T patent/DE3566209D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0177981A1 (en) | 1986-04-16 |
| DE3432887A1 (en) | 1986-03-20 |
| DE3566209D1 (en) | 1988-12-15 |
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