US4138471A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for reducing the polycyclic aromatic hydrocarbon content of carbon black
Assignee: Degussa Engineered Carbons LP
•
Filing: 1977-03-03
•
Granted: 1979-02-06
•
Expires: 1997-03-03
Abstract
Abstract The amount of polycyclic aromatic hydrocarbons on the surface of a carbon black can be reduced below 2 ppb by heat treating the carbon black in a fluidized bed. Dried furnace carbon black pellets are charged in a fluid bed unit and preheated. The pellets are then fluidized with air, with the temperature of the bed between 1150° F and 1850° F for 5 to 40 minutes. The carbon black is then quenched and recovered.
Inventors
- 👤 Trevor G. Lamond
- 👤 John L. Wells
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:45
CPC Classifications
C; C09; C09C; C09C1/00; C09C1/44; C09C1/48; C09C1/56; C09C1/58; C01; C01P; C01P2006/00; C01P2006/12
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
146 words
A method of purifying a furnace black to reduce the level of polycyclic aromatic hydrocarbons to less than 2 micrograms per kilogram of furnace black, comprising the steps of: (a) pelletizing said furnace black with less than 5% of binder so that there is no significant obstruction of the interparticulate spaces of the resulting pellets; (b) charging a fluid bed unit with said furnace black; (c) preheating said furnace black to about 500° F for about 30 minutes; (d) fluidizing said furnace black with a flow of fluid containing at least 10% oxygen selected from the group consisting of air, air mixed with other gases, and combustion gases containing free air; (e) maintaining the temperature of the fluidized bed from 1150° F for a period of time from 5 minutes to 165 minutes to heat treat said furnace black; (f) quenching and recovering said furnace black.
Claim 2
Independent Claim
146 words
A method of purifying a furnace black to reduce the level of polycyclic aromatic hydrocarbons to less than 2 micrograms per kilogram of furnace black, comprising the steps of: (a) pelletizing said furnace black with less than 5% of binder so that there is no significant obstruction of the interparticulate spaces of the resulting pellets; (b) charging a fluid bed unit with said furnace black; (c) preheating said furnace black to about 500° F for about 30 minutes; (d) fluidizing said furnace black with a flow of fluid containing at least 10% oxygen selected from the group consisting of air, air mixed with other gases, and combustion gases containing free air; (e) maintaining the temperature of the fluidized bed from 1150° F for a period of time from 5 minutes to 165 minutes to heat treat said furnace black; (f) quenching and recovering said furnace black.
Claim 3
Dependent Claim
18 words
A method according to claim 1 wherein the time period in step (e) is 5 to 40 minutes.
Claim 4
Dependent Claim
25 words
A method according to claim 1 wherein the binder is selected from the group consisting of molasses, sugar, pitch, lignin, sulfonated lignin and other polymers.
References Cited (Backward Citations)
US2005022A
Cited
US2707672A
Cited
US2707674A
Cited
GB937841A
Cited
US3130133A
Cited
US3993739A
Cited
US4075157A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-05 | 1982-08-07 | 1983-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-05 | 1986-08-07 | 1987-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-05 | 1990-08-07 | 1991-02-06 | $7700.00 | Window Closed / Lapsed |