US4818293A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stable slurries comprising powdered activated carbon
Assignee: Veolia WTS USA Inc
•
Filing: 1987-11-20
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Granted: 1989-04-04
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Expires: 2007-11-20
Abstract
Abstract Stable, thixotropic slurries comprising wood-based powdered activated carbon and an effective amount of a polysaccharide suspending agent are disclosed. Such slurries are useful as water clarification and coagulation aids.
Inventors
- 👤 Bruce K. Fillipo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 19:20
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/28; C02F1/283; C02F1/52; C02F1/54
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
44 words
A composition comprising a thixotropic slurry of powdered activated carbon and an effective polysaccharide or modified polysaccharide suspending agent, said powdered activated carbon being prepared by the destructive distillation of a wood precursor, said slurry having a viscosity of about 200-4,000 cps Brookfield RVT.
Claim 2
Dependent Claim
44 words
A composition comprising a thixotropic slurry of powdered activated carbon and an effective polysaccharide or modified polysaccharide suspending agent, said powdered activated carbon being prepared by the destructive distillation of a wood precursor, said slurry having a viscosity of about 200-4,000 cps Brookfield RVT.
Claim 3
Dependent Claim
75 words
A stable slurry composition comprising powdered activated carbon prepared by the destructive distillation of a wood precursor and an effective polysaccharide suspending agent selected from the group consisting of dextran polymer, sodium carboxymethyl cellulose, and hydroxyethyl cellulose; wherein said slurry maintains its thixotropic properties while exhibiting only slight stratification without liquid separation or hard pack sludging following six weeks storage at ambient temperature; said slurry further having a viscosity of about 200-4,000 cps Brookfield RVT.
Claim 4
Dependent Claim
75 words
A stable slurry composition comprising powdered activated carbon prepared by the destructive distillation of a wood precursor and an effective polysaccharide suspending agent selected from the group consisting of dextran polymer, sodium carboxymethyl cellulose, and hydroxyethyl cellulose; wherein said slurry maintains its thixotropic properties while exhibiting only slight stratification without liquid separation or hard pack sludging following six weeks storage at ambient temperature; said slurry further having a viscosity of about 200-4,000 cps Brookfield RVT.
Claim 5
Dependent Claim
16 words
A composition as recited in claim 2 wherein said polysaccharide suspending agent comprises sodium carboxymethyl cellulose.
Claim 6
Dependent Claim
55 words
A composition as recited in claim 3 wherein based on the total weight of said slurry, said powdered activated carbon is present in an amount of from about 1 wt. % to about 50 wt. %; said sodium carboxymethyl cellulose being present in an amount of about 0.025 wt. % to about 5 wt. %.
Claim 7
Dependent Claim
40 words
A composition as recited in claim 4 wherein said powdered activated carbon is present in said slurry in an amount of about 30 wt. %, and said sodium carboxymethyl cellulose being present in an amount of about 0.5 wt. %.
Claim 8
Dependent Claim
77 words
A stable slurry composition comprising about 30 wt. % of the total weight of said slurry powdered activated carbon derived by the destructive distillation of a wood precursor and about 0.5 wt. % of the total weight of said slurry sodium carboxymethyl cellulose haivng a viscosity of about 200-4,000 cps Brookfield RVT said slurry maintaining its thixotropic properties while exhibiting only light stratification without liquid separation or hard pack sludging following six weeks storage at ambient temperature.
Claim 9
Dependent Claim
77 words
A stable slurry composition comprising about 30 wt. % of the total weight of said slurry powdered activated carbon derived by the destructive distillation of a wood precursor and about 0.5 wt. % of the total weight of said slurry sodium carboxymethyl cellulose haivng a viscosity of about 200-4,000 cps Brookfield RVT said slurry maintaining its thixotropic properties while exhibiting only light stratification without liquid separation or hard pack sludging following six weeks storage at ambient temperature.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-03 | 1992-10-03 | 1993-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-03 | 1996-10-03 | 1997-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-03 | 2000-10-03 | 2001-04-04 | $7700.00 | Window Closed / Lapsed |