Clayey barriers

Patent metadata

Field	Value
Publication number	US-9328216-B2
Application number	US-201113817835-A
Country	US
Kind code	B2
Filing date	Aug 24, 2011
Priority date	Aug 27, 2010
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

The present invention relates to improved clayey barriers, such as compacted clay liners or geosynthetic clay liners, which can be used, among other uses, to isolate waste liquids from the environment. More in particular, the present invention relates to clay which is treated with an anionic polymer and is subsequently dehydrated before it is used as a barrier. The latter improved clays are surprisingly well, and for a long term, protected from chemical attack by aggressive electrolyte solutions present in, for example, sea water or waste liquids.

First claim

The invention claimed is:

1. A method of preparing a hydraulic clayey barrier comprising:
a) wetting a clay by mixing the clay with a solution comprising an anionic polymer to obtain a slurry of clay treated with an anionic polymer, and
b) drying the slurry of clay and anionic polymer in order to expel water molecules and adsorb the polymer on the clay surface,
wherein said hydraulic clayey barrier has the following characteristics: a basal spacing d>1,235 nm, a liquid limit LL>122%, a swell index SI>26 ml/2 g, a swell pressure SP>50 kPA, a hydraulic conductivity k to CaCl 2 <3.53 10 −11 m/s and to seawater <6 10 −10 m/S, a chemico-osmotic efficiency ω CaCl2=1 mM >0.29 and/or a diffusion coefficient D(Cl − or Ca 2+ )>2.22 10 −10 m 2 /s.

2. The method of claim 1 , wherein said clay is bentonite and wherein said anionic polymer is sodium carboxymethyl cellulose.

3. The method of claim 1 , wherein said clay is bentonite.

4. The method of claim 1 , wherein said anionic polymer is sodium carboxymethyl cellulose.

5. The method of claim 1 , wherein said clay is mixed with 2% up to 16% by dry weight of said anionic polymer.

6. The method of claim 1 , wherein said drying is undertaken by oven drying the slurries of clay, polymer and water resulting from said mixing a clay with an anionic polymer solution at a temperature higher than 60° C.

7. The method of claim 1 , wherein said hydraulic clayey barrier is ground after said drying said clay treated with an anionic polymer and is rehydrated before use as a hydraulic clayey barrier.

8. The method of claim 1 , wherein said hydraulic clayey barrier is ground after said drying said clay treated with an anionic polymer.

9. The method of claim 1 , wherein said hydraulic clayey barrier is rehydrated before use as a hydraulic clayey barrier.

10. The method of claim 1 , wherein said clay is dredging soil or kaolin.

11. The method of claim 1 , wherein said hydraulic clayey barrier maintains its efficiency for at least 2000 days.

12. The method of claim 1 , wherein said hydraulic clayey barrier is used for isolating waste liquids from the environment.

13. A method of isolating a waste liquid from the environment comprising:
preparing a hydraulic clayey barrier by
a) wetting a clay by mixing the clay with a solution comprising an anionic polymer to obtain a slurry of clay treated with an anionic polymer, and
b) drying the slurry of clay and anionic polymer in order to expel water molecules and adsorb the polymer on the clay surface, wherein said drying is undertaken by oven drying at a temperature higher than 60° C. the slurries of clay, polymer and water resulting from said mixing a clay with an anionic polymer solution; and
containing the waste liquid with a liner comprising said hydraulic clayey barrier, wherein said hydraulic clayey barrier maintains its efficiency for at least 2000 days, thereby isolating the waste liquid from the environment.

14. A method of isolating a waste liquid from the environment comprising containing
the liquid with a liner comprising a hydraulic clayey barrier having the following characteristics: a basal spacing d>1,235 nm, a liquid limit LL>122%, a swell index SI>26 ml/2 g, a swell pressure SP>50 kPA, a hydraulic conductivity k to CaCl 2 <3.53 10 −11 m/s and to seawater <6 10 −10 m/S, a chemico-osmotic efficiency ω CaCl2=1 mM >0.29 and/or a diffusion coefficient D(Cl − or Ca 2+ )>2.22 10 −10 m 2 /s.

Assignees

• Di Emidio Gemmina
• Univ Gent

Inventors

• Di Emidio Gemmina

Classifications

• C08K3/346 Primary

  Clay · CPC title

• E02D31/004

  Sealing liners · CPC title

• C04B28/001

  containing unburned clay (polymer binder - clay mixtures used in well cementing C09K8/44) · CPC title

• B09B1/004 Primary

  Covering of dumping sites · CPC title

• C04B2111/00775

  the composition being used as waste barriers or the like, e.g. compositions used for waste disposal purposes only, but not containing the waste itself · CPC title