ENZYMATIC TREATMENT METHOD AND SYSTEM FOR FIBROUS CELLULOSIC MATERIAL AND RIGID CELLULOSIC PRODUCT

Abstract

Enzymatic treatment method and system for fibrous cellulosic material and rigid cellulosic product, wherein the method comprises introduction of raw fibrous cellulosic material (1) in a stirrer (20); enzymatic treatment of the raw fibrous cellulosic material (1) for a specific period of time to obtain a treated cellulosic material, said enzymatic treatment including the addition of enzymes (11, 12, 13, 14) to the raw fibrous cellulosic material and the uniform distribution of said enzymes in the raw fibrous cellulosic material by stirring; drying the treated cellulosic material; wherein at least a proportion of the raw fibrous cellulosic material is derived from industrial waste.

Claims

1. Enzymatic treatment method for fibrous cellulosic material comprising the steps of introduction of raw fibrous cellulosic material (1) in a stirrer (20); enzymatic treatment of the raw fibrous cellulosic material (1) for a specific period of time to obtain a treated cellulosic material, said enzymatic treatment including the addition of enzymes (11, 12, 13, 14) to the raw fibrous cellulosic material and the uniform distribution of said enzymes in the raw fibrous cellulosic material by stirring; drying the treated cellulosic material; wherein at least a proportion of the raw fibrous cellulosic material is derived from industrial waste.

2. The enzymatic treatment method of claim 1 wherein the raw fibrous cellulosic material derived from industrial waste has fibers having one or more of an average length of less than 5 mm, preferably less than 2 mm, and/or an average width of less than 0.1 mm, and/or a mass percentage of fines greater than 10%.

3. (canceled)

4. The enzymatic treatment method of claim 1, wherein the industrial waste is one or more of primary sludge obtained from the paper production industry, preferably with fibers having an average length of less than 5 mm, most preferably less than 2 mm, residues from the textile production industry, or cellulosic construction waste.

5. The enzymatic treatment method of claim 1, wherein the raw fibrous cellulosic material has a water content comprised between 20% and 80% by weight with respect to the total amount of raw fibrous cellulosic material after the addition of the enzymes (11, 12, 13, 14) and the water content is maintained within said range during the enzymatic treatment.

6. (canceled)

7. (canceled)

8. (canceled)

9. The enzymatic treatment method according to claim 1, wherein the added enzymes (11, 12, 13, 14) are selected to smooth the fibers, to remove radicals from the outside of the fibers and to increase the specific surface area of the fibers and/or comprise xylanase, laccase, cellulase and/or combinations thereof.

10. The enzymatic treatment method according to claim 1, wherein: the raw fibrous cellulosic material (1), during the enzymatic treatment, is maintained with a pH comprised between 5 and 9 and/or with a temperature comprised between 40? C. and 70? C.; and/or the enzymatic treatment is produced within the stirrer (20) and wherein the specific period of time is comprised between 15 and 60 minutes; and/or the dried treated cellulosic material (2, 3, 4) has a water content below 50%, preferably below 20%.

11. (canceled)

12. (canceled)

13. The enzymatic treatment method according to claim 6, wherein the dried treated cellulosic material (2, 3, 4) is screened and separated in different fractions (2, 3, 4) by fiber sizes during the drying step, or during the drying step by a trommel screen or after the drying step.

14. The enzymatic treatment method according to claim 1, wherein the dried treated cellulosic material is screened to produce an inorganic fraction separate from the remainder of the dried treated cellulosic material.

15. A method of forming a rigid cellulosic product comprising the steps of: applying the enzymatic treatment method of any preceding claim to fibrous cellulosic material, and compressing, preferably one of moulding, preferably injection moulding, or pressing in a press or between drums, and heating the cellulosic material to form a rigid cellulosic product.

16. (canceled)

17. The method of forming a rigid cellulosic product according to claim 15, wherein the method is a continuous method.

18. The method of forming a rigid cellulosic product according to claim 15 wherein different cellulosic material fractions (2, 3, 4), with different fiber lengths, are deposited in overlapped layers (5, 6, 7), compressed and heated in a product former (50) including a mold, a press or a conveyor passing between compression drums, producing a rigid stratified cellulosic product (9).

19. The method of forming a rigid cellulosic product according to claim 18, wherein additives (8) or adhesive-free additives (8) are mixed with at least one of the cellulosic material fractions (2, 3, 4) constitutive of the rigid stratified cellulosic product (9); the additives (8) or adhesive-free additives (8) not being present in other cellulosic material fractions (2, 3, 4) constitutive of the same rigid stratified cellulosic product (9), or the additives (8) or adhesive-free additives (8) being present in other cellulosic material fractions (2, 3, 4) constitutive of the same rigid stratified cellulosic product (9) and being the same or different from the additives (8) or the adhesive-free additives (8) mixed with other cellulosic material fractions (2, 3, 4) constitutive of the same rigid stratified cellulosic product (9).

20. The method of forming a rigid cellulosic product according to claim 15, wherein different cellulosic material fractions are deposited in overlapped layers, compressed and heated in a product former (50) including a mold, a press or a conveyor passing between compression drums, producing a rigid stratified cellulosic product (9), wherein at least one of the overlapped layers defining an external surface layer of the rigid cellulosic product comprises at least a proportion of the inorganic fraction.

21. (canceled)

22. (canceled)

23. A rigid cellulosic product comprising compressed enzyme-treated fibrous cellulosic material derived from industrial waste, preferably wherein at least 20% of the enzyme-treated fibrous cellulosic material is derived from industrial waste.

24. The rigid cellulosic product according to claim 23, comprising multiple compressed overlapped layers (5, 6, 7), each layer (5, 6, 7) being made of cellulosic material with different fiber lengths than the adjacent layers (5, 6, 7), preferably wherein at least one of the layers (5, 6, 7) includes additives (8) or adhesive-free additives (8) that are different from the additives (8) or adhesive-free additives (8) included in the other layers (5, 6, 7) preferably wherein at least one of the layers (5, 6, 7) has a density that is different from the other layers (5, 6, 7).

25. (canceled)

26. (canceled)

27. The rigid cellulosic product according to claim 23, wherein the enzyme-treated fibrous cellulosic material is produced by the method of any one of claims 1 to 14.

28. The rigid cellulosic product according to claim 23 wherein the enzyme-treated fibrous cellulosic material is substantially lignin free.

29. (canceled)

30. (canceled)

31. (canceled)

32. (canceled)

Description

BRIEF DESCRIPTION OF THE FIGURES

[0132] The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and non-limitative manner, in which:

[0133] FIG. 1 shows a schematic view of an embodiment of the enzymatic treatment system adapted to apply the proposed method for obtaining different fractions of the dried treated cellulosic material;

[0134] FIG. 2 shows the same enzymatic treatment system shown on FIG. 1 but also including a product former station for producing a stratified rigid cellulosic product.

DETAILED DESCRIPTION OF AN EMBODIMENT

[0135] The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be used in an illustrative and not limitative way.

[0136] The enzymatic treatment system shown on FIG. 1 includes, in succession, the following working stations: a stirrer 20 which integrates an enzyme applicator 10, a dryer 30 and a screener 40 integrated in a trommel screener.

[0137] FIG. 2 shows a similar embodiment but further including a product former 50 feed by a dosing device 61, 62, 63 after the screener 40.

[0138] Multiple paste or granular material conveyors, such as conveyor belts or screw conveyors, connecting working stations to transfer the cellulosic material through the proposed enzymatic treatment system.

[0139] A raw fibrous cellulosic material 1, at least a proportion of which is derived from industrial waste, for example sewage or primary sludge from the paper manufacturing industry and/or waste from the cellulosic manufacturing industry, is fed into the stirrer 20 where the enzymes 11, 12, 13, 14 are added and mixed thereon by multiple active stirring elements 21, producing the enzymatic treatment within the stirrer 20 during a specific period of time.

[0140] In this embodiment the active stirrer elements 21 are parallel rotative blades contained in the stirrer 20.

[0141] According to this embodiment the enzyme applicator 10 comprises multiple spray nozzles contained in the stirrer 20, facing the upper surface of the raw fibrous cellulosic material 1 contained in the stirrer 20. The spray nozzles are fed, with liquid enzymes 11, 12, 13, 14, or with liquid water solutions of enzymes 11, 12, 13, 14 stored in separated deposits, it can also be fed with additional water.

[0142] A control unit 15 can regulate the amount of each enzyme 11, 12, 13, 14 added to the raw fibrous cellulosic material 1, for example in response to a measurement of the specific composition of the raw fibrous cellulosic material 1 to be treated.

[0143] The water content of the raw fibrous cellulosic material 1, once the enzymes 11, 12, 13 and 14 have been added, shall be comprised of between 20% and 80% to obtain a sufficient flowability for stirring the minimal water content. The water contained in the added enzymes 11, 12, 13, 14 can be adjusted, or additional water can be added to the raw fibrous cellulosic material 1, for example through the spray nozzles.

[0144] The flowability of the raw fibrous cellulosic material 1 and/or its water content is preferably measured or deduced from other measurements, for example from the energy consumption of the motor actuating the active stirring elements 21, or by an analysis of a sample.

[0145] The control unit 15 can automatically adjust the composition of the enzymes 11, 12, 13, 14 added to the raw fibrous cellulosic material 1, and/or the exact amount of water added to the raw fibrous cellulosic material 1 for example adding additional water, and/or operational parameters of the stirrer 20. Said operational parameters can be, for example, the movement velocity of the active stirring elements 21 and/or a heater 23 which heats the raw fibrous cellulosic material 1 contained in the stirrer 20.

[0146] According to this embodiment, the stirrer 20 includes a stirrer inlet on its top for the introduction of the raw fibrous cellulosic material 1, and a stirrer outlet 22 on the bottom for the extraction of the treated cellulosic material, which is then transferred to the dryer 30 and screener 40.

[0147] Other alternative embodiments of the stirrer 20 are also contemplated. For example the stirrer can be an horizontal rotative hollow drum with the stirrer inlet on one end and the stirrer outlet 22 on the opposite end, wherein the active stirring elements are blades attached to the inner side of the walls of the rotative drum and are configured not only for stirring but also for pushing the raw fibrous cellulosic material through the stirrer 20 from the stirrer inlet to the stirrer outlet 22 spending the specified period of time within the stirrer 20. This embodiment allows a continuous flow treatment process of the raw fibrous cellulosic material 1 in the stirrer 20.

[0148] The above mentioned trommel screener integrates the dryer 30 and the screener 40 and comprises of a rotative horizontal hollow drum including multiple successive meshes integrated into the walls of the rotative horizontal hollow drum.

[0149] The treated cellulosic material, with a water content comprised of between 20% and 80%, is introduced into the trommel screener through one end, and also air heated by a heater 31 is blown through the rotative horizontal hollow drum while the drum rotates, reducing the water content to produce treated cellulosic materials with water content below 20%.

[0150] The successive meshes have increasingly larger sized holes for screening different fractions 2, 3, 4 of the dried treated cellulosic material of increasingly longer fibers.

[0151] Those fractions 2, 3, 4, due to its water content is lower than 20% and can be stored for future use in a simple manner, or can be used immediately.

[0152] One proposed use of the dried treated cellulosic material is the production of a rigid cellulosic product, or more preferably a stratified rigid cellulosic product 9 made of overlapped layers 5, 6, 7 of different fractions 2, 3, 4 in a product former 60.

[0153] According to the embodiment shown on FIG. 2, the product former 60 comprises a conveyor belt passing between two opposed compression drums.

[0154] Multiple successive application heads 61, 62, 62, constitutive of a dosing device 61, 62, 63, are facing said conveyor belt. The first application head 61 deposits a front layer 5 of a controlled thickness of the stratified rigid cellulosic product 9 to be produced on the conveyor belt, the layer being made of a fraction 2 of the dried treated cellulosic material 2, 3, 4. Successive application heads 62, 63 deposit additional layers 6, 7 of controlled thicknesses of the stratified rigid cellulosic product 9 to be produced on top of the front layer 5.

[0155] When said overlapped layers 5, 6, 7 pass between the compression drums, they are compressed and heated by the compression drums, producing the stratified rigid cellulosic product 9, in this case as a flat panel.

[0156] More complex shapes can be obtained by using a mold or a press as a product former 50. In those cases the mold, the press, or the application heads 61, 62, 63 can be moved in a controlled manner to produce a deposition of the overlapped layers covering the entire surface of the mold, previous to the closing of the mold and the application of the pressure and heat.

[0157] One or several of the fractions 2, 3, 4 can be mixed with an additive 8 or an adhesive-free additive 8 previous to its deposition onto the product former 50 to provide this specific layer with some improved features.

[0158] It will be understood that the present invention enables the use of fibres otherwise considered unusable to produce a new rigid cellulosic product. For fibres derived from primary sludge from the paper production industry, there is no possibility to reuse/recycle the fibres as the fibres contained by the sludge have short lengths, under 5 mm or shorter still below 2 mm. Moreover, primary sludge also includes high percentages of inorganic charges which reduces the mechanical properties. Prior to the screen aspect of the present invention, there was no way to efficiently separate inorganic charges from cellulosic fibers to enable subsequent use of those fibres.

[0159] In the case of textile industrial waste, the reason why previously there is no possibility to reuse them is different to fibres derived from primary sludge, and relates to the difficulty of disgregating or separating the mixed compositions of fibres found in textiles to subsequently re-use those fibres in new textile production.

[0160] Several examples of cellulosic products obtained with the proposed method are described below.

Example 1

[0161] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 75% (measured in dry weight) of industrial waste in the form of sewage sludge from the paper manufacturing industry and 25% (measured in dry weight) of waste cardboard.

[0162] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is mixed with additives and used to produce a rigid cellulosic product with a density of 1,17 g/cm.sup.3 in the form of a 13,62 mm thick panel.

[0163] The additive used is an acrylic binder which is a cross linkable, low formaldehyde binder (<100 ppm free formaldehyde in the product) commercialized under the name of PRIMAL ECO-15 R Acrylic binder.

[0164] The obtained panel has a flexural strength of 23.7 MPa.

Example 2

[0165] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 75% (measured in dry weight) industrial waste in the form of sewage sludge from the paper manufacturing industry and 25% (measured in dry weight) from waste cardboard.

[0166] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is mixed with additives and used to produce a rigid cellulosic product with a density of 1,14 g/cm.sup.3 in the form of a 6,6 mm thick panel.

[0167] The additive used is an acrylic binder which is a cross linkable, low formaldehyde binder (<100 ppm free formaldehyde in the product) commercialized under the name of PRIMAL ECO-15 R Acrylic binder.

[0168] The obtained panel has a flexural strength of 16.5 MPa.

Example 3

[0169] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 75% (measured in dry weight) industrial waste in the form of sewage sludge from paper manufacturing industry and 25% (measured in dry weight) of waste cardboard.

[0170] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is mixed with additives and used to produce a rigid cellulosic product with a density of 1,23 g/cm.sup.3 in the form of a 13,62 mm thick panel.

[0171] The additive used is an acrylic binder which is a cross linkable, low formaldehyde binder (<100 ppm free formaldehyde in the product) commercialized under the name of PRIMAL ECO-R Acrylic binder.

[0172] The obtained panel has a flexural strength of 26.7 MPa.

[0173] It will be understood that the obtained panel of Example 3 has a higher forming pressure compared to the panel of Example 1, resulting in a panel of higher density and mechanical properties such as flexural strength.

Example 4

[0174] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 75% (measured in dry weight) industrial waste in the form of sewage sludge from the paper manufacturing industry and 25% (measured in dry weight) from waste cardboard.

[0175] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is used, without additives, to produce a rigid cellulosic product with a density of 0,89 g/cm.sup.3 in the form of a 16,3 mm thick panel.

Example 5

[0176] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 50% (measured in dry weight) of sewage sludge from the paper manufacturing industry and 50% (measured in dry weight) from waste cardboard.

[0177] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is used, without additives, to produce a rigid cellulosic product with a density of 1,03 g/cm.sup.3 in the form of a 8,7 mm thick panel.

[0178] The obtained panel has a flexural strength of 15.8 MPa.

Example 6

[0179] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises only industrial waste in the form of sewage sludge from the paper manufacturing industry.

[0180] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is mixed with additives and used to produce a rigid cellulosic product with a density of 0,79 g/cm.sup.3 in the form of a 13,79 mm thick panel.

[0181] The additive used is an ecologic acrylic binder-based resin.

[0182] The obtained panel has a flexural strength of 27.4 MPa.

Example 7

[0183] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 30% cellulosic residue (measured in dry weight) from the textile manufacturing industry and 70% (measured in dry weight) from waste cardboard.

[0184] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is used without additives, to produce a rigid cellulosic product with a density of 0.79 g/cm.sup.3 in the form of a 11 mm thick panel.

[0185] The obtained panel has a flexural strength of 17.6 MPa.

Example 8

[0186] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 90% (measured in dry weight) of sewage sludge from the paper manufacturing industry and 10% (measured in dry weight) from triturated (or ground or powdered) rigid cellulosic product of the present invention, that is, recycling cellulosic product to use as the cellulosic material in the enzyme treatment process to produce new cellulosic product.

[0187] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is mixed with additives and used to produce a rigid cellulosic product with a density of 0.98 g/cm.sup.3 in the form of a 13 mm thick panel.

[0188] The additive used is an ecologic acrylic binder-based resin.

[0189] The obtained panel has a flexural strength of 29.7 MPa.

Example 9

[0190] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 100% (measured in dry weight) from triturated (or ground or powdered) rigid cellulosic product of the present invention, that is, the new cellulosic product is fully derived from recycled cellulosic product. Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is used to produce a rigid cellulosic product with a density of 0.96 g/cm.sup.3 in the form of a 9.5 mm thick panel.

[0191] The obtained panel has a flexural strength of 18.6 MPa.

Example 10

[0192] The raw fibrous cellulosic material 1 introduced in the stirrer 20 comprises 20% (measured in dry weight) industrial waste in the form of sewage sludge from the paper manufacturing industry and 80% (measured in dry weight) from waste cardboard.

[0193] Once the enzymatic treatment and the drying process have been completed, the resulting dried treated cellulosic material is used to produce a rigid cellulosic product with a density of 0.690 g/cm.sup.3 in the form of a 12 mm thick panel.

[0194] The obtained panel has a flexural strength of 15.4 MPa.

[0195] It will be understood that various parts of one embodiment of the invention can be freely combined with other parts described in other embodiments, even if this combination is not explicitly described, provided that such combination is within the scope of the claims and that there is no harm in such combination.