Pitch from coal tar pitch, method of its production, as well as

Details Pitch from coal tar pitch, method of its production, as well as Pitch from coal tar pitch, method of its production, as well as

1989-08-03

1992-07-07

Myers, Helane

Mineral oils: processes and products

Asphalts, tars, pitches and resins; making, treating and...

208 22, 208 42, 208 44, C10G 100, C10C 300

Patent

active

051280213

DESCRIPTION:

BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national phase of PCT/EP88/00031 filed Jan. 16, 1988 and based upon German national application P 37 02 720.4 filed Jan. 30, 1987 under the International Convention.


FIELD OF THE INVENTION

The present invention relates to a pitch material made from coal tar pitch, to a method of producing the pitch and to different applications of such pitch.


BACKGROUND OF THE INVENTION

In the previous state of the art coal tar pitch has been treated e.g. by distillation, solvents, air blowing or cross-linking reactions in order to give a pitch material having a softening point between 70.degree. to 150.degree. C. Such pitch material serves as a binder for high-grade carbonaceous products, e.g. electrodes, carbon brushes and the like as well as molded shapes of high mechanical strength which--after subsequent thermal treatment of the carbonized material--are appropriate for manufacturing graphites. One drawback is, however, that the molded shapes obtained from the previous type of pitch material after an initial thermal treatment step are of relatively low density and have to be subjected to several impregnation treatments and recarbonizations to improve this density.


OBJECT OF THE INVENTION

The objective of the invention is to provide a pitch material which can be made from coal tar pitch and a method of producing same, with a view to manufacturing high-grade carbonaceous products without the necessity of additional treatment steps--or at least requiring fewer treatment steps than with the previous state of the art--the improved pitch material being moreover suitable for use as an impregnation agent and, finally, as a high-grade binder.


SUMMARY OF THE INVENTION

This object is achieved with a coal tar pitch-based material characterized by the following parameters: the Kramer-Sarnow (KS) measurement,
Thanks to the surprisingly high softening point (for a coal tar pitch) in the range from 200.degree. to 300.degree. C. (KS) the material exhibits excellent treatment properties with no risk whatsoever of premature carbonization or thermal degradation.
The new pitch material surprisingly yields quite a high amount of coke, too,--between 80 to >90%--which is an extremely favorable feature for pitch material from coal tar pitch since it gives a coke of higher density and, if further treated, also a denser graphite, all of those treatments using fewer treatment steps and shorter retention times than previously.
The novel-type pitch material is produced by a sequence of steps wherein 10% solids, e.g. ash, coal particles, quinoline-insolubles (primary .alpha.-resins), and exhibiting a softening points of <100.degree. C. is used as the starting material, similar--is added to the starting material, discharging a dry filter cake and exhibiting gaps sized between 50 to 150 .mu.m and the temperature range from above 300.degree. C. to about 425.degree. C. and at .ltoreq.10 mbar pressure.
The pitch material can be produced from the usual type of coal tar pitch whose softening point is below 100.degree. C. and which may contain between 1 and 10% solids, by freeing the starting material from most of its solids (which may be constituted of ash, coal particles and quinoline-insolubles (primary .beta.-resins)) in a candle filter where, as the case may be, filtration agents are added. The thus pre-purified pitch is, surprisingly, suitable for smooth transformation into the novel-type pitch material in thin-layer evaporators at a vacuum of .ltoreq.10 mbar and at above 300.degree. C. The pitch material is obtained as a concentrate.
Another striking feature is that the by-products cracked in the form of distillates have excellent features which make them especially suitable for use as an aggregate to tars, pitches and oils.
Alternatively, process feature C) (filtration) may be varied in that a disk filter with a secondary treatment step is used.
Another variant of process feature C) (filtration) is that a drum filter for dry cake discharge is used.
When opting for the t

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