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1. (WO1983001263) PROCEDE AMELIORE DE LAVAGE PAR DEPLACEMENT DE MILIEUX POREUX
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS

1. In a process for separating a liquid from an insoluble material which includes the steps of thickening said insoluble material by draining excess liquid therefrom while retaining the material in a porous formation on a porous support means and displacing a substantial portion of the solution remaining in the insoluble porous material after thickening from said material by injecting a wash solution into said material, without substantially disturbing said porous formation of the retained material, the improvement, comprising:
reducing the mobility of said wash solution in the porous formation of the insoluble material with respect to the mobility of said liquid originally retained in the porous insoluble material,
wherein the mobility of said solution with respect to said porous formation is proportional to the permeability of the porous formation to the solution and inversely proportional to the viscosity of said solution.
2. The process of claim 1, wherein: reducing the mobility of said wash solution is accomplished by increasing its viscosity relative to said liquid to be displaced.
3. The process of claim 2, wherein: the viscosity of said solution is increased by reducing the temperature of said wash solution, thereby reducing its mobility relative to said liquid to be displaced.
4. The process of claim 2, wherein: the viscosity of said wash solution is increased by adding starch to said solution, thereby reducing the mobility of said solution relative to said liquid to be displaced.
5. The process of claim 1, wherein: reducing the mobility of said wash solution is accomplished by reducing the effective permeability of said solution with respect to the porous formation of insoluble material by adding a polymer to said solution.
6. The process of claim 1, wherein: reducing the mobility of said wash solution is accomplished by adding liquid-soluble polymers thereto, said polymers characterized by their hydrating ability at very low concentrations.
7. The process of claim 6, wherein: the mobility of the wash solution is adjusted by adding said polymer in an amount such that the ratio

of wash solution mobility to the mobility of the solution to be displaced is about 0.05-2.0.
8. The process of claim 6, wherein: the mobility of wash solution is adjusted by adding said polymer in an amount such that the mobility ratio is about 0.2-1.0.
9. The process of claim 6, wherein: said mobility reducing polymers are one or more homo or copolymers of ethylene oxide, acrylamide, vinyl pyprolidone, acrylic acid, methacrylic acid, the Na, K, Li and amine salts of car boxy methyl cellulose, maleic acid, Na, K, Li and amine salts of alginic acid.
10. The process of claim 9, wherein: the mobility of the wash solution is adjusted by said polymer having a molecular weight of greater than 1 million.
11. The process of claim 6, wherein: said mobility reducing polymers are one or more homo or copolymers of acrylamide, acrylic acid, carboxymethylene or deacetylated chitin.
12. An improved process for displacement washing of pulp substantially free of soluble contaminants, wherein said pulp is first thickened and retained on a porous supporting means, comprising:
preparing a wash solution, in which the fiber is insoluble and having a concentration therein of said contaminants to be removed less than that of the pulp to be washed;
adjusting the apparent, effective mobility of said wash solution so that it is less than the mobility of the solution to be recovered, wherein the mobility of said solution is proportional to the permeability of the pulp with respect to said solution and inversely proportional to the viscosity of said solution; and
injecting the pulp with said wash solution, wherein the solution containing the dissolved solids is preferentially displaced.
13. The process of claim 12 wherein the solution to be displaced is spent cooking liquor from a pulping process.
14. The process of claim 12 wherein the soluble contaminants of the solution to be displaced are dissolved solids from the bleaching of pulp.
15. The process of claim 12 wherein the mobility of the wash solution is adjusted by adding a high molecular weight polymer that is soluble in the wash solution solvent.
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16. The process of claim 15 wherein said polymers are one or more homo or copolymers of ethylene oxide, acrylamide, vinyl pyprolidone, acrylic acid, methacrylic acid, or Na, K, LI and amine salts of carboxy-m ethyl cellulose.
17. The process of claim 16 wherein the high molecular weight polymer has a molecular weight greater than 1 million.
18. The process of claim 12 wherein the resulting ratio of the mobility of the wash solution to that of the solution to be displaced is about

0.05-2.0.
19. The process of claim 12 wherein the ratio of the mobility of the wash solution to that of the solution to be displaced is about 0.2-1.0.
20. The process of claim 12 wherein said polymer is added in an amount of 2-50 ppm to the wash solution.
21. The process of claim 20 wherein said polymer is polyacryl-amide, carboxypolymethylene, or deacetylated chitin.
22. An improved process for recovering processing chemicals from wood pulp retained in solution with the pulp after the pulp has been thickened, by displacement washing of said pulp, the improvement, comprising:
preparing a wash solution, said solution having a lower concentration of the chemicals to be displaced than that initially retained with said pulp;
adding to said solution a polymer having a molecular weight greater than 1 million, in an amount of about 2-50 ppm, wherein said polymer is polyacrylamide, carboxypolymethylene, or deacetylated chitin;
injecting into said pulp said wash solution; and
recovering said wash solution containind said chemicals.
23. The process of claim 22 wherein said displacement wash solution is employed on rotary cylinder vacuum washers.
24. The process of claim 22 wherein said displacement wash solutions is employed in a ring diffuser washer.