CS197708B1 - Material for preparing electrode coke - Google Patents

Description

Electrode coke is currently produced in the form of so-called kerosene coke, mainly by delayed coking of high-boiling, or completely undistinguishable proportions of crude oil or fractions from its processing. It can also be produced from petrochemical by-products of petroleum fractions, for example pyrolysis oil, which is the most boiling and undistinguishable portion of the by-products of pyrolysis olefin production. In particular, pyrolysis oil is suitable for the preparation of coke for a number of applications in the field of artificial carbon. The disadvantage of pyrolysis oil and, ultimately, most petroleum raw materials is the relatively high sulfur content, which makes it impossible to produce low-sulfur coke, which is practically universally and particularly prospectively usable. Another drawback of pyrolysis oil is its structure; It is poor in polycondensated aromatic compounds, which does not allow both the economic yield of coke and the coke obtained for many applications has low strength and other unsuitable properties. In addition to kerosene coke, pitch coke produced by delayed or high-temperature carbonization of coal pitch is used for the production of anodes for the electrolytic production of aluminum. Coal pitch as an explicitly polycyclic feedstock has the potential to produce coke with a high content of anisotropic carbon. Coal pitch also has a low sulfur content, an average of 0.6% by weight. The chemical structure of the sulfur compounds in the coal pitch enables their thermal decomposition, thus reducing the sulfur content during carbonization. Therefore, pitch coke contains not more than 0.4% by weight of sulfur. However, coal pitch production is far from sufficient to meet the needs of low-sulfur coke for all electrode carbon consumption sectors.

The solution for producing low-sulfur coke for all areas of its consumption is possible by using the raw material for the preparation of the electrode coke according to the invention. It is an object of the present invention to use a mixture of pyrolysis oil having a distillation beginning of 160 to 220 ° C and coal pitch for the production of electrode coke to reduce sulfur content and increase coke yield. The ratio of the two components may vary with respect to the purity and strength of the coke; a higher proportion of pitch in the raw material reduces the total sulfur content of the coke and increases its strength.

The use of the raw material according to the invention makes it possible to obtain an electrode coke which meets the requirements of all fields of artificial carbon consumption. It is due to its chemical purity, i.e. its low sulfur content and its very low content of accompanying substances, in particular iron, calcium, vanadium, zinc, silicon, boron, titanium, and its physical purity, i.e. the isotropic to anisotropic crystallographic form of carbon. At the same time, the use of the raw material according to the invention achieves a higher coke yield than from the individual raw materials in separate coking, thus achieving a better utilization of the raw material, since the interaction of pyrolysis oil and coal pitch increases their coking properties. The analytical finding of coke according to DIN 51720 is 8.22% by weight for the pyrolysis oil sample and 40.80% by weight for the coal pitch. In a 9: 1 mixture of pyrolysis oil and coal pitch, the coke yield is 12.80% by weight, at an 8: 2 ratio of 17.25% by weight and at a 7: 3 ratio of 20.44% by weight of coke. In proportion to these analytical findings, coke yield is also achieved in controlled laboratory coking.

A practical embodiment of the process for preparing an electrode coke with controllable properties from a raw material according to the present invention results from the following examples.

Example 1

Pyrolysis oil with a sulfur content of 0.85% by weight was carbonized in a delayed coking laboratory apparatus at 530 ° C and a holding time of 16 hours, yielding coke in a yield of 18.3% by weight per feedstock. The sulfur content of the coke was 1.2% by weight. Under the same conditions, the coal pitch with a softening point of 70.1 ° C with a sulfur content of 0.52% by weight was carbonized and a coke was obtained in a yield of 52% by weight per feedstock. The sulfur content of the coke was 0.31% by weight.

Example 2

A mixture of 90% by weight of pyrolysis oil and 10% by weight of bituminous pitch was carbonized under the same conditions as in Example 1 and coke was obtained in a yield of 23.8% by weight more than that produced by the conversion of Example 1. The sulfur content of the coke was 0.98 % by weight.

Example 3

A mixture of 80% by weight of pyrolysis oil and 20% by weight of bituminous pitch was carbonized under the same conditions as in Example 1 and coke was obtained in a yield of 28.8% by weight of the feedstock, i.e. 15.2% by weight more than the conversion The sulfur content of the coke was 0.76% by weight.

Example 4

A mixture of 70% by weight of pyrolysis oil and 30% by weight of coal pitch was carbonized under the same conditions as in Example 1 and coke was obtained in a yield of 33.6% by weight of the feedstock, i.e. 18.3% by weight, more than expected. The sulfur content of the coke was 0.61% by weight.

Claims (1)

PftEDMĚT Raw material for the preparation of an electrode coke with a reduced sulfur content and an increased coke yield, characterized in that it consists of a mixture of pyrolysis of lysis oil with a distillation beginning of 160 to 220 ° C and coal tar pitch.