CA1236789A - Low volatile binder pitch - Google Patents
Low volatile binder pitchInfo
- Publication number
- CA1236789A CA1236789A CA000471711A CA471711A CA1236789A CA 1236789 A CA1236789 A CA 1236789A CA 000471711 A CA000471711 A CA 000471711A CA 471711 A CA471711 A CA 471711A CA 1236789 A CA1236789 A CA 1236789A
- Authority
- CA
- Canada
- Prior art keywords
- pitch
- distillation
- binder pitch
- softening point
- distillate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- C10C1/04—Working-up tar by distillation
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Working-Up Tar And Pitch (AREA)
Abstract
ABSTRACT
LOW VOLATILE BINDER PITCH
A low volatile binder pitch for making Soderberg electrodes having a softening point of 130 to 140 C
as defined according to ASTM D-3104. This pitch which has low carcinogenic fume emission, has preferably a quinoline insoluble content of 10-14%, and an ash content of less than 0.3%.
A method of preparing the pitch consists in vacuum distilling a coal tar material having less than 5% Q.I.
and not more than 0.1% ash, to collect at first a distillate and maintain said distillation until the vapour temperature of the distillate to be collected is at least over 350°C, stopping said distillation and then collecting the residue of said distillation to produce the binder pitch having a softening point of 130° to 140°C.
LOW VOLATILE BINDER PITCH
A low volatile binder pitch for making Soderberg electrodes having a softening point of 130 to 140 C
as defined according to ASTM D-3104. This pitch which has low carcinogenic fume emission, has preferably a quinoline insoluble content of 10-14%, and an ash content of less than 0.3%.
A method of preparing the pitch consists in vacuum distilling a coal tar material having less than 5% Q.I.
and not more than 0.1% ash, to collect at first a distillate and maintain said distillation until the vapour temperature of the distillate to be collected is at least over 350°C, stopping said distillation and then collecting the residue of said distillation to produce the binder pitch having a softening point of 130° to 140°C.
Description
iL~3~
This invention relates to a new low volatile binder pitch. More particularly, this invention relates to a new coal tar binder pitch for Soderberg electrodes for making aluminum, meeting governmental regulations, restricting carcinogenic components and to a method of makin~ same.
BACKGROUND O~ TH~: INVENTION
Coal tar binder pitches having a softening point of 100-110C are well known and are generally used as a paste in conjunction with coke Eiller. That paste moves down a reservoir for the electrode paste which gradually forms a liquid and then carbonize to form a coked carbon electrode which comes in contact with the liquid aluminum on one side, the other side being carbon tray forming the second electrode. During coking of the conventional binder pitch, fumes are elimited and contain substances which could be considered carcinogenic.
The~problem was such that in order to comply with government regulations, a highly sophisticated ventilation and scrubbing system was required, rendering the Soderberg system obsolete, because of prohibitive costs.
Also known is the Sumitomo process using pitches havinc3 soEtening point in the order of 120-125C, where there is less fumes but the problem associated with carcinoc~enics emission still prevails.
The invention is directed to a new pitch which is particularly suitable for Soderberg electrodes and which helps to meet government fume emission control regula-tions, and which though having a high softening point, is still not too viscous to move down into the electrode reservoir.
,,~4~v ~ ~3~t7~
~ roadly stated, the invention is directed to a low volatile coal tar binder pitch having a low carcinogenic fume emission meeting governmental regulations. This low volatile binder pitch which is particularly suitable for makiny Soderberg electrodes, has a softening point of L30~140C and preferably l32C or: above, as deEined according to the ASTMD-310~ method. :[n a particular elnbodiment the binder pitch has a quinoline insoluble conterlt oE lO-1~ and an ash content less than 0.3%.
A method of making the sarne is also contemplated which consists in collecting that fraction of regular tar which boils over 350C. By so doing applicant has unexpectedly been able to remove by distillation, that fraction of the tar which contains a substantial portion of the carcinogenic substances which have been found to be present in the benzene soluble part of the condensable portion of the fume, and thereby has been able to reduce the prohibitively costly pollution control equipment that would have been required otherwise, and thereby preventing the costly Soderberg apparatus becoming obsolete.
In a particular embodiment, the method involves preparing low volatile binder pitch for making Soderberg electrodes by vacuum distilling a coal tar material having :less than 5~ ~.I. and not more than 0.1~ ash, to collect at Eirst a distillate and maintain said distillation until the vapour temperature of the distillate to be collected is at least over 360C, stopping said distillation and then collecting the residue of said distillation to produce the binder pitch having a softening point of 130 to 1~0C.
In order to obtain the suitable binder pitch, the distillation of the coal tar is carried over 350 C under normal pressure, generally up to 360-400C range, at a temperature within that range which yield the desired softening point 130-140C of the pitch, preferably 132C or over. Within that pitch, other components are adjlJsted to meet the characteristics necessary for making electrocles. For instance, since a larger fraction of the 1~ distillate is collected as the pitch (or residue) a larger proportion of the pitch is quinoline insoluble, and so for ashes. In order to achieve the necessary proportions, an adjustment in composition of the coal tar has to be made generaly before distallation by reducing of ashes and of a portion of quinoline insolubles. Blending of various pitches may also be made. In order to ease distillation and to reduce side reactions at these high temperatures, the distillation is conveniently carried out under reduced pressure.
The following will now serve to illustrate embodi-mants of our invention:
EXAMPLE l Over ~L,000 gallons of a tar feed having ~.3%
cluinoline insoluble, 7.8% xylene insoluble and a specific Z5 gravity at 15.5 C of 1.182 was vacuum distilled in a distilling column having 27 actual plate numbers into a distillate up to 390C. The top of the column was maintairled under a vacuum of 60 mm of Hg. The residue namely the pitch was 39.7% of the tar feed, 6003% having been removed as distillate.
The pitch had a quinol;ne insoluble of 10.7%, benzene 3~3 insoluble of 32.1%, ash content of .12~.
Equiviscous temperature was: 5:203.2 10:192.1 1000:141.2 The softening point was 137.1C, and the cooking value 67.5%. All the tests were made accordiny to the ASTM
tnelthods; the softeniny point accordiny to ASTM D-3104.
This pitch, when compared with the reyular conventional 1~ Soderbery binder pitch provided more than 30% reduction in carcinoyenic fume content.
E XAMPLE_ 2 In Example 2, the feed tar had a quinoline insoluble (Q.I.) content of 4.8%, was vacuum distilled under 100 mm of Hy with a final distillation temperature of 358 C
yielding a pitch of 37.1%, having a softening point of 13~.2C, Q.I. of 12.5~, a coking value of 67.4%, an ash content of 0.08%. The carcinogenic content of the pitch fumes was reduced by over 30% when compared with conventional Soderberg binder pitches having a softening point of 100-110C, thereby satisfying governmental regulations.
SAMPLE A
As a comparison, a Sumitomo type of pitch was prepared, the vacuum distillation was carried at 90 mm of ~Ig with a final distillation temperature of 348C
yielding a pitch of 39.3% having a softening point of 126.5C, a Q.I. of 8.7~, an ash content of 0.12~ and a cokiny value of 62.5%. The carcinogenic content of the pitch fumes was not reduced sufficiently to meet governmental regulations.
~3~7~
A feed tar having a Q.I. content of 408%, was vacuum distilled under 100 mm of Hg with a final distillation temperature of 370C, yielding a pitch of 37%, having a softening point of 171.4C. This pitch was blended with a pitch obtained from vacuum distillation of under 100 ~m of Hg with a final distillation temperature of 355 C, with a pitch yield of 48.1%, the pitc}l having a softening point of 95C. The resulting pitch so blended yielded a softening point of 131C. The Q.I. content was 11.6%
and a coking value of 64.6%. On trial, the carcinogenic content of the pitch fumes was reduced by over 30% when compared with conventional Soderberg binder pitches having a softening point of 100-110C, thereby satisfying governmental regulations.
SAMPEE B
A conventional Soderberg pitch was produced in a 4,000 gallon distillation pot with direct gas heating, the ultimate distillation temperature was under 350C at standard pressure. The tar had a Q.I. content of 7.8%.
The resulting point had a softening point of 101.1C, with a Q.I. content of 0.26%, with a coking value of 62.1~. The resulting pitch when heated to 400 C
similarly to previous experiments, produced fumes which contain over 30% higher carcinogenics than described in the previous Examples 1 to 3.
The above described procedure can be subject to a great variety of modifications which will be evident to those skilled in the art and which fall within the scope of the appended claims.
This invention relates to a new low volatile binder pitch. More particularly, this invention relates to a new coal tar binder pitch for Soderberg electrodes for making aluminum, meeting governmental regulations, restricting carcinogenic components and to a method of makin~ same.
BACKGROUND O~ TH~: INVENTION
Coal tar binder pitches having a softening point of 100-110C are well known and are generally used as a paste in conjunction with coke Eiller. That paste moves down a reservoir for the electrode paste which gradually forms a liquid and then carbonize to form a coked carbon electrode which comes in contact with the liquid aluminum on one side, the other side being carbon tray forming the second electrode. During coking of the conventional binder pitch, fumes are elimited and contain substances which could be considered carcinogenic.
The~problem was such that in order to comply with government regulations, a highly sophisticated ventilation and scrubbing system was required, rendering the Soderberg system obsolete, because of prohibitive costs.
Also known is the Sumitomo process using pitches havinc3 soEtening point in the order of 120-125C, where there is less fumes but the problem associated with carcinoc~enics emission still prevails.
The invention is directed to a new pitch which is particularly suitable for Soderberg electrodes and which helps to meet government fume emission control regula-tions, and which though having a high softening point, is still not too viscous to move down into the electrode reservoir.
,,~4~v ~ ~3~t7~
~ roadly stated, the invention is directed to a low volatile coal tar binder pitch having a low carcinogenic fume emission meeting governmental regulations. This low volatile binder pitch which is particularly suitable for makiny Soderberg electrodes, has a softening point of L30~140C and preferably l32C or: above, as deEined according to the ASTMD-310~ method. :[n a particular elnbodiment the binder pitch has a quinoline insoluble conterlt oE lO-1~ and an ash content less than 0.3%.
A method of making the sarne is also contemplated which consists in collecting that fraction of regular tar which boils over 350C. By so doing applicant has unexpectedly been able to remove by distillation, that fraction of the tar which contains a substantial portion of the carcinogenic substances which have been found to be present in the benzene soluble part of the condensable portion of the fume, and thereby has been able to reduce the prohibitively costly pollution control equipment that would have been required otherwise, and thereby preventing the costly Soderberg apparatus becoming obsolete.
In a particular embodiment, the method involves preparing low volatile binder pitch for making Soderberg electrodes by vacuum distilling a coal tar material having :less than 5~ ~.I. and not more than 0.1~ ash, to collect at Eirst a distillate and maintain said distillation until the vapour temperature of the distillate to be collected is at least over 360C, stopping said distillation and then collecting the residue of said distillation to produce the binder pitch having a softening point of 130 to 1~0C.
In order to obtain the suitable binder pitch, the distillation of the coal tar is carried over 350 C under normal pressure, generally up to 360-400C range, at a temperature within that range which yield the desired softening point 130-140C of the pitch, preferably 132C or over. Within that pitch, other components are adjlJsted to meet the characteristics necessary for making electrocles. For instance, since a larger fraction of the 1~ distillate is collected as the pitch (or residue) a larger proportion of the pitch is quinoline insoluble, and so for ashes. In order to achieve the necessary proportions, an adjustment in composition of the coal tar has to be made generaly before distallation by reducing of ashes and of a portion of quinoline insolubles. Blending of various pitches may also be made. In order to ease distillation and to reduce side reactions at these high temperatures, the distillation is conveniently carried out under reduced pressure.
The following will now serve to illustrate embodi-mants of our invention:
EXAMPLE l Over ~L,000 gallons of a tar feed having ~.3%
cluinoline insoluble, 7.8% xylene insoluble and a specific Z5 gravity at 15.5 C of 1.182 was vacuum distilled in a distilling column having 27 actual plate numbers into a distillate up to 390C. The top of the column was maintairled under a vacuum of 60 mm of Hg. The residue namely the pitch was 39.7% of the tar feed, 6003% having been removed as distillate.
The pitch had a quinol;ne insoluble of 10.7%, benzene 3~3 insoluble of 32.1%, ash content of .12~.
Equiviscous temperature was: 5:203.2 10:192.1 1000:141.2 The softening point was 137.1C, and the cooking value 67.5%. All the tests were made accordiny to the ASTM
tnelthods; the softeniny point accordiny to ASTM D-3104.
This pitch, when compared with the reyular conventional 1~ Soderbery binder pitch provided more than 30% reduction in carcinoyenic fume content.
E XAMPLE_ 2 In Example 2, the feed tar had a quinoline insoluble (Q.I.) content of 4.8%, was vacuum distilled under 100 mm of Hy with a final distillation temperature of 358 C
yielding a pitch of 37.1%, having a softening point of 13~.2C, Q.I. of 12.5~, a coking value of 67.4%, an ash content of 0.08%. The carcinogenic content of the pitch fumes was reduced by over 30% when compared with conventional Soderberg binder pitches having a softening point of 100-110C, thereby satisfying governmental regulations.
SAMPLE A
As a comparison, a Sumitomo type of pitch was prepared, the vacuum distillation was carried at 90 mm of ~Ig with a final distillation temperature of 348C
yielding a pitch of 39.3% having a softening point of 126.5C, a Q.I. of 8.7~, an ash content of 0.12~ and a cokiny value of 62.5%. The carcinogenic content of the pitch fumes was not reduced sufficiently to meet governmental regulations.
~3~7~
A feed tar having a Q.I. content of 408%, was vacuum distilled under 100 mm of Hg with a final distillation temperature of 370C, yielding a pitch of 37%, having a softening point of 171.4C. This pitch was blended with a pitch obtained from vacuum distillation of under 100 ~m of Hg with a final distillation temperature of 355 C, with a pitch yield of 48.1%, the pitc}l having a softening point of 95C. The resulting pitch so blended yielded a softening point of 131C. The Q.I. content was 11.6%
and a coking value of 64.6%. On trial, the carcinogenic content of the pitch fumes was reduced by over 30% when compared with conventional Soderberg binder pitches having a softening point of 100-110C, thereby satisfying governmental regulations.
SAMPEE B
A conventional Soderberg pitch was produced in a 4,000 gallon distillation pot with direct gas heating, the ultimate distillation temperature was under 350C at standard pressure. The tar had a Q.I. content of 7.8%.
The resulting point had a softening point of 101.1C, with a Q.I. content of 0.26%, with a coking value of 62.1~. The resulting pitch when heated to 400 C
similarly to previous experiments, produced fumes which contain over 30% higher carcinogenics than described in the previous Examples 1 to 3.
The above described procedure can be subject to a great variety of modifications which will be evident to those skilled in the art and which fall within the scope of the appended claims.
Claims (4)
1. A low volatile binder pitch for making Soderberg electrodes, having a softening point of 130° to 140°C
as defined according to ASTM D-3104, said pitch having low carcinogenic fume emission.
as defined according to ASTM D-3104, said pitch having low carcinogenic fume emission.
2. The binder pitch as defined in claim 1 having a quinoline insoluble content of 10-14%, and ash content less than 0.3%.
3. A method to prepare a low volatile binder pitch having low carcinogenic fume for making Soderberg electrodes by vacuum distilling a coal tar material having less than 5% Q.I. and not more than 0.1% ash, to collect at first a distillate and maintain said distillation until the vapour temperature of the distillate to be collected is at least over 350 C, stopping said distillation, then collecting the residue of said distillation to produce the binder pitch having a softening point of 130° to 140°C.
4. The method as defined in claim 3 wherein said vapour temperature of the distillate to be collected is between 360° and 400°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471711A CA1236789A (en) | 1985-01-08 | 1985-01-08 | Low volatile binder pitch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000471711A CA1236789A (en) | 1985-01-08 | 1985-01-08 | Low volatile binder pitch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1236789A true CA1236789A (en) | 1988-05-17 |
Family
ID=4129537
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000471711A Expired CA1236789A (en) | 1985-01-08 | 1985-01-08 | Low volatile binder pitch |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1236789A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0510315A1 (en) * | 1991-04-20 | 1992-10-28 | Rütgerswerke Aktiengesellschaft | Coaltar pitch, preparation and use thereof |
| US8580105B2 (en) | 2008-03-05 | 2013-11-12 | Saint-Gobain do Brasil Produtos Industriais e para Construção Ltda. | Development process of an ecological binder system for refractories mixes |
-
1985
- 1985-01-08 CA CA000471711A patent/CA1236789A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0510315A1 (en) * | 1991-04-20 | 1992-10-28 | Rütgerswerke Aktiengesellschaft | Coaltar pitch, preparation and use thereof |
| US5262043A (en) * | 1991-04-20 | 1993-11-16 | Rutgerswerke Ag | Coal tar pitch and the preparation and use thereof |
| US8580105B2 (en) | 2008-03-05 | 2013-11-12 | Saint-Gobain do Brasil Produtos Industriais e para Construção Ltda. | Development process of an ecological binder system for refractories mixes |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |