Method for Separating the Main Components of Lignocellulosic Materials

• US 20090062523A1
• Filed: 04/18/2006
• Published: 03/05/2009
• Est. Priority Date: 04/18/2005
• Status: Active Grant

• Current Assignee: Cerefi Oy
• Original Assignee: Cerefi Oy
• Inventors: Malkki, Yrjo
• Granted Patent: US 8,956,502 B2
• Time in Patent Office: Days
• US Class Current: 536/56
• CPC Class Codes: C08H 8/00 Macromolecular compounds derived from lignocellulosic materials pretreatment thereof B27N
• CPC Class Codes: D21B 1/12 by wet methods, by the use of steam beaters D21D1/00
• CPC Class Codes: D21C 1/06 with alkaline reacting compounds

Abstract

The objective of this invention is a method for separating cellulosic fibres, hemicellulose and lignin from parts of plants containing these, such as stems, leaves and seed coats or hulls of cereal, oilseed, fibre or grassy plants. After appropriate pre-treatments the material is heated in an alkaline solution at lower temperatures than used in the traditional cellulose manufacturing. After this heat treatment, the fibrous and other undissolved materials are separated from the solution and subsequently ground in wet condition, using preferably chafing treatments. For improving the separation, surface active substances can be included in the alkaline heat treatment solution.

Claims

1. A method of fractionating a lignocellulosic material or a material obtained therefrom, characterized in that it comprises the steps of:

heating the material in an alkaline solution of a pH above 9.0 at a temperature below the glass transition temperature of the hemicellulose-lignin complex,

draining the material to obtain a heat-treated wet material, and

subjecting the heat-treated wet material of a pH above 9.0 to grinding.

2. A method according to claim 1 , characterized in that the alkaline solution contains sodium hydroxide or potassium hydroxide and may contain constituents recovered from the process liquids.

3. A method according to claim 1 or 2, characterized in that the alkaline solution contains one or several surface active substances.

4. A method according to claim 3, characterized in that the surface active substance is an anion active compound.

5. A method according to claim 3, characterized in that the surface active substance is a non-ionic substance.

6. A method according to claim 3, characterized in that the surface active substance is an ampholytic compound.

7. A method according to claim 1, characterized in that the alkaline solution consists of sodium and/or potassium hydroxide and, optionally one or more surface active agents and/or constituents recovered and circulated in the process.

8. A method according to claim 1, characterized in that the heat treatment is less than 6 hours.

9. A method according to claim 1, characterized in that the grinding is performed by using a chafing mode of operation.

10. A method according to claim 7, characterized in that after the heat treatment and draining an amount of water is added to the material subjected to grinding for improving the efficiency of grinding.

11. A method according to claim 1, characterized in that the heat-treated wet material obtained by draining is subjected to grinding directly, without any intermediate treatment.

12. A method according to claim 7, characterized in that the main part of the cellulosic fibres are not broken.

13. A method according to claim 7, characterized in that the silica crystals or needles of the material remain intact.

14. A method according to claim 1, characterized in that the lignocellulosic material to be treated is the hull or bran fraction obtained in the treatment of cereal grains.

15. A method according to claim 1, characterized in that the lignocellulosic material to be treated is straw, stems or other parts of cereal, oilseed, fibre or grassy plants.

16. A method of fractionating a lignocellulosic material or material obtained therefrom, comprising the steps of:

heating the material in an alkaline solution of a pH above 9.0 at a temperature below 130°

C.,

draining the material to obtain a heat-treated wet material, and

subjecting the heat-treated wet material of a pH above 9.0 to mechanical separation or grinding, to obtain separated cellulosic fibres substantially free of hemicellulose and lignin.

17. A method according to claim 16, characterized in that the material is heated at a temperature below 120°

C., preferably at 90-110°

C.