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US4818293A Expired / Lapsed US ⏱️ 0.0 years remaining

Stable slurries comprising powdered activated carbon

Assignee: Veolia WTS USA Inc
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Filing: 1987-11-20
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Granted: 1989-04-04
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Expires: 2007-11-20
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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.

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

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