Bergwerksverband Gmbh

Hellmut Kokot

Ingo Romey

Georg Kolling

Coal tar pitch is liquified at temperature of from about 135.degree. C. to 280.degree. C. The liquid coal tar pitch is filtered through a sieve with apertures from about 100 to 220 .mu.m and with a closed surface area of at least 75 percent of the total sieve surface under pressures of from about 2 to 10 bar until a filter cake of a height of from about 40 to 80 mm forms above the sieve for separating ash, soot and quinoline insoluble particles from the liquid. Then the filtrate obtained is subjected to a coking process. The needle cokes resulting in accordance with the invention provide excellent materials for the production of graphite electrodes.

Method for the production of needle coke

A process is provided for purifying filter-clogging coal tar residue of the type obtained by low-temperature carbonization of coal. Such coal tar residues include viscous organic coal tar constituents, particulate solid impurities and liquid water. Applicants' process includes the step of heating coal at 450.degree.-700.degree. C. at least substantially in the absence of air to thereby decompose the coal to products including coal tar, the coal tar being of the type containing liquid water, particulate solid impurities, and viscous organic coal tar constituents including light oils, the light oils incidentally combining with the liquid water to produce a filter-clogging emulsion. The thus-formed coal tar is then heated to a temperature above the boiling point of water and sufficiently high to thereby distill off substantially all of the water and the light oils to thereby obtain an intermediate product which is substantially free from the presence of liquid water and light oil constituents which in combination form a filter-clogging emulsion. Finally, the intermediate product is subsequently filtered to thereby separate the particulate solid impurities from the undistilled viscous constituents of the coal tar.

Purifying filter-clogging coal tar formed from low-temperature coal

Coal-tar pitch is heated to a temperature which is at least 100.degree. C above its softening point but below its decomposition temperature and is mixed with a filter aid, such as kieselghur or activated carbon prior to filtering the pitch at at least the preheat temperature so as to remove ashes, soot and heavy metals therefrom. The thus-purified pitch is then coked. In this manner, it is possible to obtain high-quality, anisotropic acicular coke which is readily convertible into graphite.

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Essen, Germany

Hellmut Kokot