Process for dewatering microfibrillated cellulose

Patent metadata

Field	Value
Publication number	US-10240289-B2
Application number	US-201415034290-A
Country	US
Kind code	B2
Filing date	Nov 5, 2014
Priority date	Nov 7, 2013
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

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

The invention claimed is:

1. A process for dewatering a slurry comprising a microfibrillated cellulose by only subjecting the slurry to a mechanical pressure, without significant hornification of the microfibrillated cellulose, wherein the process comprises the following steps:
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.

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 microfibrillated cellulose before the dewatering is 0.1-10% by weight.

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

Assignees

• Stora Enso Oyj

Inventors

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

Classifications

• D21H11/18

  Highly hydrated, swollen or fibrillatable fibres · CPC title

• D21F3/00

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

• D21D1/20

  Methods of refining · CPC title

• C08B15/02

  Oxycellulose; Hydrocellulose; {Cellulosehydrate, e.g. microcrystalline cellulose} · CPC title

• B01D33/00

  Filters with filtering elements which move during the filtering operation (filters comprising loose filtering material moving or fluidised during filtration B01D24/28 - B01D24/36; centrifuges B04B) · CPC title