Process for dewatering microfibrillated cellulose

Patent metadata

Field	Value
Publication number	US-2016265160-A1
Application number	US-201415034290-A
Country	US
Kind code	A1
Filing date	Nov 5, 2014
Priority date	Nov 7, 2013
Publication date	Sep 15, 2016
Grant date	—

Abstract

The present invention relates to a process for dewatering a slurry comprising a microfibrillated cellulose wherein the process comprises the following steps of providing a slurry comprising a microfibrillated cellulose and a liquid, subjecting the slurry to a first mechanical pressure in order to dewater the slurry, and subjecting the slurry to a second mechanical pressure which second pressure is higher than the first pressure.

First claim

1 . Process for dewatering a slurry comprising a nanofibrillated polysaccharide wherein the process comprises the following steps:
providing a slurry comprising a nanofibrillated polysaccharide and a liquid, subjecting the slurry to a first mechanical pressure in order to dewater the slurry, and subjecting the slurry to a second mechanical pressure which second pressure is higher than the first pressure.

2 . The process according to claim 1 wherein the process further comprises the step of subjecting the slurry to a third mechanical pressure which third pressure is higher than the second pressure.

3 . The process according to claim 1 , wherein the slurry is conducted between two wires before the slurry is subjected to the first mechanical pressure.

4 . The process according to claim 1 , wherein the slurry is subjected to the first and second mechanical pressure by conducting the slurry through a wedge gap.

5 . The process according to claim 1 , wherein the slurry is subjected to the first and second pressure by conducting the slurry over a roll having a first roll diameter.

6 . The process according to claim 5 wherein the slurry is subjected to the second mechanical pressure by conducting the slurry over a roll having a second roll diameter said second roll diameter being smaller than the first roll diameter.

7 . The process according to claim 6 wherein the slurry is conducted over more than one roll having a second roll diameter.

8 . The process according to claim 1 , wherein the slurry is subjected to the first and, second mechanical pressure by conducting the slurry to a decanter-centrifuge.

9 . The process according to claim 1 , wherein the slurry is subjected to the second mechanical pressure by conducting the slurry to a screw press.

10 . The process according to claim 1 , wherein the dry content of the slurry comprising a nanofibrillated polysaccharide before the dewatering is about 0.1-10% by weight.

11 . The process according to claim 1 , wherein the dry content of the dewatered slurry comprising a nanofibrillated polysaccharide is about 1-50% by weight.

12 . The process according to claim 1 , wherein the nanofibrillated polysaccharide is microfibrillated cellulose.

Assignees

• Stora Enso Oyj

Inventors

• Nousiainen Laura
• Kostiainen Petteri
• Saarinen Petteri
• Nordström Jan-Erik

Classifications

• D21C9/007

  by mechanical or physical means · CPC title

• D21C9/18 Primary

  De-watering (de-watering in general F26B); {Elimination of cooking or pulp-treating liquors from the pulp}(D21C9/002, D21C9/02 take precedence; paper-making machines D21F; strainers in digesters D21C7/00; presses in general B30B) · CPC title

• F26B13/28

  for applying pressure; for brushing; for wiping · CPC title

• D21C9/06

  in filters {; Washing of concentrated pulp, e.g. pulp mats, on filtering surfaces} · CPC title

• D21F3/00

  Press section of machines for making continuous webs of paper · CPC title