BR-112021018001-B1 - PROCESS FOR THE PRODUCTION OF AGGLOMERATED LIGNIN

BR112021018001B1BR 112021018001 B1BR112021018001 B1BR 112021018001B1BR-112021018001-B1

Abstract

PROCESS FOR PRODUCING AND USING AGGLOMERATED LIGNIN. The present invention relates to and is directed to a process for producing agglomerated lignin with a controlled particle size distribution. The agglomerated lignin is essentially dust-free in such a way that the risk of dust explosion is greatly reduced.

Inventors

Dimitri Areskogh

Assignees

STORA ENSO OYJ

Dates

Publication Date: 20260310
Application Date: 20200311
Priority Date: 20190314

Claims (4)

1. Process for producing agglomerated lignin with a controlled particle size distribution, characterized in that it comprises the steps of: a) lignin compaction, wherein lignin having a moisture content of 1% by weight to 45% by weight is agglomerated by roller compaction, wherein the rollers have cavities and the depth of each cavity used in roller compaction is from 0.1 mm to 10 mm; b) subjecting the compacted lignin from step (a) to a grinding step; followed by: c) a sieving step, wherein the product of step (b) is subjected to sieving to remove particles having a particle size below 100 μm, to produce a final agglomerated lignin with a controlled particle size distribution in which the particle size distribution is regulated by the mesh size of the sieving screens used in the sieving step; and wherein less than 10% by weight of the particles retained after step (c) have a particle size below 100 μm.
2. Process according to claim 1, characterized in that the lignin is agglomerated without the addition of any additives.
3. Process, according to any one of claims 1 to 2, characterized in that the depth of each cavity used in roller compaction in step (a) is from 1 mm to 5 mm.
4. A process according to any one of claims 1 to 3, characterized in that the sieving is carried out in more than one stage, using at least two sieving screens with different screen mesh openings.

Description

Field of invention [0001] The present invention is directed to a process for producing agglomerated lignin with a controlled particle size distribution. The agglomerated lignin is essentially dust-free in such a way that the risk of dust explosion is greatly reduced. Technical overview [0002] Lignin, an aromatic polymer, is a major constituent, for example, in wood, being the most abundant carbon source on Earth, second only to cellulose. In recent years, with the development and commercialization of technologies to extract lignin in a highly purified, solid, and particularized form from the pulp production process, it has attracted significant attention as a possible renewable substitute for primarily aromatic chemical precursors currently sourced from the petrochemical industry. [0003] Lignin has been extensively investigated as a suitable substitute for phenol during the production of phenol-formaldehyde binders for the production of panel boards such as plywood, hardboard, medium-density fiberboard or particleboard. [0004] It is preferable to use a lignin product with a minimum moisture content to avoid bringing unnecessary additional water into the process. However, handling lignin with a minimum moisture content of 0% - 50% (by weight) presents several serious problems. Among these is that lignin forms dust clouds during any type of handling. These dust clouds can further lead to dust explosions when a sufficiently high concentration of combustible material is suspended in the air. [0005] Consequently, there is a need for a method to process lignin in such a way that the risk of dust explosion can be greatly reduced. [0006] Several attempts to apply lignin roller compactor processing are known. Russian patents numbers RU 2197389 and RU 2307033, and US patent applications numbers US 2010/0218420 and US 2010/154296, describe processes for producing briquettes where lignin is a component in the final briquette composition. In the processes described therein, lignin is used as a liquid or solid binder to bind the various components together in such a way as to generate briquettes. The end use of these briquettes is in the technical field of energy generation. Summary of the invention [0007] The present invention provides a solution to one or more of the problems of the prior art. A particular advantage of the process in accordance with the present invention is that the dust-forming fines are reduced to such an extent that no risk of dust explosion exists. [0008] The present invention is directed to a process for producing agglomerated lignin with a controlled particle size distribution, comprising the steps of: a) lignin compaction, wherein lignin having a moisture content from 1% by weight to 45% by weight is agglomerated by means of roller compaction, wherein the rollers have cavities and wherein the depth of each cavity used in roller compaction is from 0.1 mm to 10 mm; b) subjecting the compacted lignin from step (a) to a grinding step; followed by: c) a sieving step, wherein the product of step (b) is subjected to sieving to remove particles having a particle size below 100 μm, to produce a final agglomerated lignin with a controlled particle size distribution in which the particle size distribution is regulated by the mesh opening of the sieving screens used in the sieving step; and wherein less than 10% by weight of the particles retained after step (c) have a particle size below 100 μm. [0009] Compaction in accordance with the present invention is preferably carried out without the addition of any additives to the material to be compacted. In the context of the present invention, an additive is a substance that is added to the process to improve adhesion between lignin particles. Consequently, additives are substances that are added but are not present in the lignin that is the starting material in step (a). Consequently, neither moisture, such as water, nor other components already present in the lignin that is the starting material in step (a) are considered additives in the context of the present invention. [0010] The present invention is also directed to the use of agglomerated lignin having a controlled particle size distribution obtained as the product of step (c). For example, lignin can be used as an intermediate in chemical synthesis processes, such as in the production of binders. Detailed description [0011] It is intended throughout the present description that the term “lignin” shall encompass any type of lignin, for example, lignin originating from hardwood, softwood or annual (seasonal) plants. Preferably, the lignin is an alkaline lignin generated, for example, in the Kraft process. Preferably, the lignin has been purified or isolated before being used in the process in accordance with the present invention. The lignin may be isolated from black liquor and optionally further purified before being used in the process in accordance with the present invention. The purification is typic