US4528098A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Screw driven sludge thickeners
Assignee: D'etudes De Recherches Et De Productions D'agents Chimiques - Erpac SA
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Filing: 1984-01-26
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Granted: 1985-07-09
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Expires: 2004-01-26
Abstract
Abstract An apparatus for removing liquid from a solid suspension includes a screw conveyor in a housing having a suspension inlet, a liquid outlet and a separate outlet for the thickened solids. To increase the thickening effect, the faces of the screw threads are coated or treated to cause the coefficient of friction of the front, thrust faces to be higher than that of the rear faces. The coefficients can also be varied longitudinally, either continuously or in stages.
Inventors
- 👤 Georges M. Treyssac
- 👤 Robert Morawek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:51
CPC Classifications
B; B30; B30B; B30B9/00; B30B9/02; B30B9/12; B30B9/121; B01; B01D; B01D21/00; B01D21/24; B01D21/245; B30B9/18
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
91 words
An apparatus for thickening a suspension of solid particles in a liquid such as a sludge comprising a cylindrical enclosure; a rotary endless screw extending longitudinally in said enclosure, said enclosure having an inlet for suspension to be thickened, a first outlet for thickened suspension near the front end of said screw and a second outlet for liquid separated during the thickening; and means on said screw for causing a higher coefficient of friction on the front, thrust faces of the threads of said screw than on the rear faces thereof.
Claim 2
Independent Claim
91 words
An apparatus for thickening a suspension of solid particles in a liquid such as a sludge comprising a cylindrical enclosure; a rotary endless screw extending longitudinally in said enclosure, said enclosure having an inlet for suspension to be thickened, a first outlet for thickened suspension near the front end of said screw and a second outlet for liquid separated during the thickening; and means on said screw for causing a higher coefficient of friction on the front, thrust faces of the threads of said screw than on the rear faces thereof.
Claim 3
Dependent Claim
33 words
Apparatus according to claim 1 wherein said friction coefficient on said thrust faces varies along the length of said screw and increases from the rear end to the front end of said screw.
Claim 4
Dependent Claim
13 words
Apparatus according to claim 2, wherein said friction coefficient varies in successive stages.
Claim 5
Dependent Claim
36 words
Apparatus according to claim 3, wherein the friction coefficient of the rear faces of the threads varies along the length of said screw and decreases from the rear end to the front end of said screw.
Claim 6
Dependent Claim
35 words
Apparatus according to claim 4, wherein said friction coefficient of the rear faces of the threads varies in successive stages corresponding to the variation of the friction coefficient of the thrust faces of the threads.
References Cited (Backward Citations)
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Cited
US3550526A
Cited
US3624729A
Cited
US3585924A
Cited
JPS5551000A
Cited
US4380496A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-07-08 | 1989-01-07 | 1989-07-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-07-08 | 1993-01-07 | 1993-07-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-07-08 | 1997-01-07 | 1997-07-09 | $7700.00 | Window Closed / Lapsed |