Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
  • C10C1/00—Working-up tar
  • C10C1/005—Working-up tar by mixing two or more coaltar fractions
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
  • C04B35/52—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite
  • C04B35/528—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite obtained from carbonaceous particles with or without other non-organic components
  • C04B35/532—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbon, e.g. graphite obtained from carbonaceous particles with or without other non-organic components containing a carbonisable binder

Definitions

• ABSTRACT OF THE DISCLOSURE Dissolving a coal tar pitch in an aromatic rich oil fraction containing naphthalene and its homologs as its main ingredients and having a boiling range of 200 to 300 C., in a weight ratio pitch to oil fraction of 1:1 to 1:4 to produce a suspension; separating the solid content from the suspension; distilling 01f said oil fraction from the filtrate at such a sump temperature and with such time of stay for the pitch forming the sump product of the distillation column that the content of fi-resins is increased without forming of additional a-resins.
• the object of the present invention is to provide a process for producing a pitch for electrodes which can be easily graphitized, as well as yield graphite electrodes having satisfactory mechanical strength.
• pitches having a high amount of a constituent of p-resins (defined as substances which are insoluble in benzene but are soluble in anthracene oil) form a strong framework of carbon during coking and-in addition to this-the B-resins-like the rat-resins, yield a high share to the coking residue of the pitch.
• p-resins defined as substances which are insoluble in benzene but are soluble in anthracene oil
• anthracene-oil has the disadvantage that its boiling range is extremely close to that of the pitch so that the exact separation of the solvent from the pitch solution is difficult; on the one hand, the solvent becomes pitchlike to a certain extent and on the other hand certain parts of it distill already off so that the pitch characteristics have changed after distilling off of the anthracene-oil in a uncontrolled manner.
• oil fractions with a boiling range of 200 to 300 C., preferably 220 to 250 C. containing naphthalene and its homologs as its main ingredients for separating the u-resins.
• these oil fractions may be used in comparatively low amounts, generally in a small excess and preferably in a ratio (pitchzoil fraction) of from 1:1 to 1:4, more preferably about 1:2.
• the suspension can easily be filtered and about of the undesired a-resins are separated off by the filtration.
• Particularly preferred oil fractions are those obtained from the residual oils of benzine pyrolysis to ethylene; such oil fractions have a lower viscosity than corresponding fractions from coal tar.
• the subject matter of this invention is a process for producing an electrode pitch which can be easily graphitized and is characterized by the following steps: A coal tar pitch is dissolved in an aromatic rich oil fraction of a boiling range of 200 to 300 C., preferably 220 to 250 C.
• the weight ratio of pitch to said oil fraction being from 1:1 to 1:4 preferably about 1:2; the resulting suspension is filtered in the heat or separated; theadded oil fraction is distilled off again at such a sump temperature and with such a time of stay for the pitch forming the sump product of the distillation column that the B-resin content in said pitch is increased without forming additional a-resins.
• the coal tar pitch used is a pitch obtained by continuous flash distillation of coking tars from the Ruhr-area the sump temperature at which the formation of [Si-resins occurs is 300 to 400 C. preferably 320 to 360 C., the time of stay is 0.25 to 5 hours preferably 1 to 2 hours.
• the B-resins of the charged pitch the portion of which lies generally between 15 and 20% may be increased by 25-50% or more to produce an easily graphitizable electrode pitch having a fl-resin content of more than 24%, e.g. about 26%.
• the coking residues of the obtained electrode pitches are higher than 50% (according to Conradson). On coking a firm carbon framework is obtained.
• Graphite electrodes manufactured from these pitches have in addition to good electrical and thermal properties a high mechanical strength.
• the present process can be applied also to thermally after-treated coal tar pitches which are used as electrode pitches for non-graphitized carbon electrodes e.g. for aluminiu m smelting.
• these pitches are treated according to the process of invention also up to 90% of the undesired a-resins are removed.
• the additional formation of fl-resins takes place in small amount only since in the case of these thermally treated electrode pitches the condensation process has already partially taken place.
• these pitches have before being subjected to the process of invention, already got a fi-resins content of more than 20% it is easy to obtain at the end electrode pitches containing more than 24% of Q-resins. It is true, of course, that a small decrease of the coking residue occurs.
• Example I 5000 parts by weight coal tar pitch obtained by continuous flash distillation, were dissolved in 10,000 parts by weight of a residual oil fraction, rich in aromatics of the benzine pyrolyse to ethylene and the suspension thus obtained at 80 C. to 100 C. sucked off over a vacuum filter.
• the coal tar pitch had the following characteristics:
• the oil fraction rich in aromatic had the following properties:
• Example II In a manner analogous to Example I, another coaltar pitch also prepared by continuous flash distillation was dissolved in the ratio 1:2 in the described oil fraction rich in aromatic, the resulting suspension was filtered and the oil distilled, so that a sump temperature of 320 C. was more than 2 hours maintained.
• the properties of the charged and of the pitch obtained in a yield of 83% were as follows:
• the amount of the anthracene-insoluble has been reduced by 90% and the amount of fi-resins more than 50% increased.
• Example III Special Pitch electrode charged pitch Softening point (K.-S.), 0.... 83. 0 84. 5 Benzolinsoluble, percent 25. 4 25. 6 Anthraceneoil-insoluble, percent. 9.1 1. 3 fi-Resins, percent 16. 3 24. 3 Coking residue (Conradson), percent 53. 9 53. 2
• This treatment reduced the content of substances insoluble in anthraceneoil by about 85% and increased the fi-resins content by 50%.
• Example IV As described in Example I a normal electrode pitch obtained by thermal aftertreatment of a coal tar pitch was dissolved in a aromatic rich oil-fraction in the weight ratio of 1:2 and the suspension thus obtained was filtered and the oil distilled off in a manner that the sump temperature was maintained at 360 C. for 2 hours.
• the properties of the charged pitch and the yield of 85 produced itch were:
• the pitch to solvent weight ratio being at least 1:1
• the filtration is carried out at 80-110 C.
• distillation is carried out at 0.13 atmospheres and reaches a final sump temperature of 320-360 C.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Ceramic Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Structural Engineering (AREA)
• Working-Up Tar And Pitch (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5789448

Family Applications (1)

Country Status (6)

Cited By (10)

• 1970
  • 1970-11-30 DE DE19702058751 patent/DE2058751A1/de active Pending
• 1971
  • 1971-09-23 ES ES395371A patent/ES395371A1/es not_active Expired
  • 1971-09-27 NL NLAANVRAGE7113231,A patent/NL171466C/xx not_active IP Right Cessation
  • 1971-11-08 GB GB5178971A patent/GB1357159A/en not_active Expired
  • 1971-11-17 US US00199774A patent/US3761387A/en not_active Expired - Lifetime
  • 1971-11-30 FR FR7142943A patent/FR2116183A5/fr not_active Expired

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