DD215324A1 - PROCESS FOR PRODUCING ELECTRODE COKE - Google Patents

Abstract

The invention relates to the preparation of a good graphitizable coke electrode from products of thermal-hydroprocessing of crude lignite coal. By extraction by means of aromatic solvents, chlorinated hydrocarbons and / or carbon disulfide and / or by anti-insulating treatment, a feedstock for coking is produced from the vacuum distillation residue of coal liquefaction. The electrode coke produced therefrom by known processes is distinguished by a low ash, sulfur and volatile content and by a high purity.

Description

Process for the production of electrode coke Field of application of the invention

The invention relates to a usable for the production of high-quality electrode coke and derived from the thermal-hydrogenating treatment of lignite raw materials and a process for its preparation.

Characteristic of the known technical solutions

The necessary to produce high quality ^(graphite electrodes Elektrodenkoks is obtained by thermal treatment of coal tar, petroleum and Braunkohlenteer- product fractions and / or residues thereof according to a variety of methods.

It is known that the quality of the electrode coke and of the graphite electrodes produced therefrom is decisively determined by the material composition of the feedstock used for the coking.

The ever increasing demands on the quality of the graphite electrodes for electrothermal and electrochemical processes cause high quality requirements placed on the raw material for producing such electrodes

such as 'ash and sulfur content, graphitizability, thermal dilatation and resistivity,'

Such raw materials are primarily distillate fractions and residues of oil processing 'or Petrolchemie and tars of coal coking and brown coal smoldering, which are preferably worked up to pitches and subjected in certain cases before the actual coking of a thermal or hydrothermal pre-treatment.

Favorable compounds for the formation of highly anisotropic coke structures are primarily higher-condensed aromatics of the anthracene, tetracenes, pentacene and hexacene type with few and short side chains already present in these products or formed by thermal or hydrothermal treatment.

The cokes produced by different coking processes from raw materials with a high content of aromatics described above are characterized by good graphitization, high anisotropy, low electrical resistance and low thermal dilatation.

It is known that the coking raw materials and the nature of their pretreatment are responsible for achieving the required high quality parameters.

It has been proven that lignite and brown coal tar pitches produce cokes of lower anisotropy than cokes produced from coal tar or petroleum products. This difference is due to the fact that in the lignite tars the compounds which give the desired anisotropic Koksstruktür the coking, only a small proportion are available.

For this reason, there has been no lack of attempts in the past to win products with the highest possible content of so-called coke formers. Good coke-formers are highly aromatic vacuum distillate fractions with a high proportion of highly condensed aromatics of the anthracene type and homologues with short-chain alkyl substituents.

Since lignite coal tar have these Köksbildner only to a small extent, it is possible to bring about a structural change in the direction of the highly condensed aromatics by a thermal treatment, as it is the splitting Teerdestillätion. Since these feeds are produced only with great equipment and technological effort, u. a. lignite liquefaction products were also tested for their suitability.

In the process of catalytic high-pressure hydrogenation or in other lignite liquefaction processes, which preferably take place at temperatures between 350 to 500 ⁰ C and hydrogen pressures of 5 to 30 MPa, caused by the degradation of the structure of macromolecules of lignite and by accompanying polymerization and Pplykondensationsreaktionen the low molecular weight or unsaturated Intermediate compounds in the liquefaction product distillates and residues which are low in higher-boiling aromatics.

Said distillates and residues, however, contain a series of higher molecular weight compounds which are unsuitable for coking with the aim of producing a coke with a high degree of graphitization and high fibro-needle anisotropy. Thus, coal liquefaction products of lignite for the production of said quality cokes are only to be considered suitable. If it is possible to remove the interfering compounds from the product.

Object of the invention

The object of the invention is to obtain a coking raw material from products of the thermal-hydrogenating treatment of Riohb.rako coal, from which a high-quality coke of an electrode can be prepared from the well-known coking process. *

Explanation of the WeSens of the invention

It is an object of the invention to obtain a coking feed product by solvent extraction from lignite liquefaction products or from their residues, from which a qualitative electrode coke can be produced by known coking processes.

It has been found that by a solvent extraction of vacuum residues from lignite liquefaction products using aromatic solvents of the benzene series, chlorinated hydrocarbons such as carbon tetrachloride, chloroform and carbon disulfide or by partial precipitation of undesirable matter components with an antisolvent characterized by a Watson factor of at least 9.75, preferably at least 11 is characterized as paraffins and isoparaffins in the low and middle C range, cyclohexane, naphthene or benzene paraffinic side chains can be obtained with a raw material which gives an electrode coke with good graphitization, high anisotropy and low electrical resistance on coking.

The vacuum residue of the brown coal liquefaction product NIIT an initial boiling point of about 360 ⁰ C, after industrially common extraction method preferably respectively with benzene, toluene and extracted by the Critical Solvent deashing process or

Lummus deashing process or another known extraction method or process; be worked up by treatment with one of the aforementioned Antisolvents. The proportion of coke-forming substance groups depends on the petrographic composition of the lignite used in the liquefaction process, the given process parameters and on the thermal load during the post-processing of the vacuum residue.

Taking these factors into consideration, approximately 60 to 90 % of the vacuum residue is recovered as extract and coking ingredient.

The coking was carried out in a usual laboratory carbonization bubble with an average yield of 70% and a structure with high anisotropic content of low ash, low sulfur, low volatile content and high purity.

By means of the process according to the invention, it is possible to produce high-quality starting materials for producing high-quality electrode cokes from residues of brown coal refining products, which are difficult to access for other material use.

embodiments

Reference to the following embodiments, the inventive method will be explained.

example 1

The vacuum residue of a coal liquefaction product, initial boiling point 360 C ₁ , was diluted with ten times the amount.

Denden benzene when extracted three times, the benzene extract was purified by distilling the extraction solvent benzene, a black brown solid (softening point 82 ⁰ C, 0.16% ash content) obtained. This mass was measured in a laboratory

3 '

coking bubble (V *> 2000 cm) coked at a pressure of 0.5 MPa, wherein heated to 320 ⁰ C at a rate of 10 ° C / min and then to 580 ° 0 at a rate of 2 C / min and then this temperature was kept for over 18 hours.

From 200 g of coke feed produced 140 g of coke (70 % yield), the recovered coke is characterized by the following quality indicators:

, ν 'green coke -

ash Wt .-% ._: -: 0.23 sulfur Ma.-SS - - ": 0.53 fugitive Ma. -as : 3.94 true density g / cm : 1.40 calcined coke ... true density, 3 ^; g / cm : 1.96 electrical conductivity - 2 S, mm : 126 Example 2

An atmospheric residue (boiling point 300 ⁰ C) was mixed with 20% η-hexane at room temperature and the mixture allowed to stand for 30 min. Subsequently, the precipitated solid was separated by centrifugation. The centrifugate was subjected to vacuum distillation to 400 ⁰ C.

The vacuum residue obtained had an ash content of less than 0.2% by mass and a solidification point of 78 ° C. It was coked under the conditions given in Example 1. The coke obtained in this case corresponded to the quality indexes listed in Example 1.

Claims (1)

invention claim Process for the preparation of a readily graphitizable electrode coke from products of the hydro-hydroprocessing of crude lignite, characterized in that the coking stock is a product from a vacuum distillation residue of the coal liquefaction by extraction with aromatic solvents, chlorinated hydrocarbons and carbon disulphide and / or by antisolvent treatment with a paraffinic, naphthenic or alkylaromatic
Solvent-derived product is used.