Production of a cellulosic fibrous pulp

Abstract

A method for producing a cellulosic fibrous material from a cellulose fibre feedstock, the method including: mechanical pre-treatment of the feedstock to form a fibre furnish having fibres with a fibre length distribution such that at least 90% of the fibres have a length less than about 25 mm; dewatering the fibre furnish to produce a first filtrate and a dewatered fibrous cake having a moisture content less than about 50% (w / w); pulping the dewatered fibrous cake at temperature in the range of 40 to 90°C to produce a pulped fibre furnish with a consistency more than about 3% fibre (w / w); washing the pulped fibre furnish to produce a cellulose fibre cake with a consistency of at least 20% fibre (w / w) and a second filtrate; and refining the cellulose fibre cake in at least one disc refiner to produce the cellulosic fibrous material.

Description

PRODUCTION OF A CELLULOSIC FIBROUS PULPRelated Applications

[0001] This application claims convention priority from Australian patent application 2024902468 filed on 9 August 2024, Australian patent application 2025201496 filed on 28 February 2025 and Australian patent application 2025203078 filed on 30 April 2025, the contents of all of which are incorporated herein by reference.Field of the Invention

[0002] The present invention relates generally to the production of a cellulosic fibrous material suitable for use in, for example, paper and board forming machines for the production of pulp board, box board, linerboard, testliner and the like, and also for vacuum moulding to form packaging items such as food and plant service and supply trays and containers, and protective and positioning packaging for the transport or display of medical, electronic or hardware items, amongst many other types of moulded packaging items. The invention relates to both a method and an apparatus for the production of a cellulosic fibrous material.Background of the Invention

[0003] The following discussion of the background to the invention is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known, or part of the common general knowledge (in any country) as at the priority date of any of the claims. Furthermore, much of the following description is provided in the context of vacuum moulding being the end use of the fibrous material produced by the present invention. However, this is done for ease of description and is not to be regarded as limiting in relation to final uses for the material.

[0004] Herbaceous plants have been relied upon as a feedstock for paper for thousands of years. However, for at least the last century, wood has become the primary fibre source for paper feedstock, and pulping has become by far the major fibre processing technique. Indeed, the demand for pulp over that period of time has given rise to several of the world’s more prominent and controversial environmental and ecological issues.

[0005] It is accepted that the conversion of wood into paper requires the use of heavy-duty industrial processes, typically requiring very large energy inputs, high volumes of process water, and having high waste levels, and generally using chemicals that give rise to difficult and sometimes hazardous disposal and recycling requirements, especially the more toxic pulping chemicals traditionally adopted in paper making processes such as chlorine, hypochlorites, caustic soda, sodium sulfide, sulfurous acid, dextrin, styrene butadiene latex or styrene acrylic, for example. Also, the pulping process, be it chemical or mechanical, is often unable to adequately control the condition and geometry of fibres in the furnish produced, at least to the extent that downstream papermaking processes regard as desirable.

[0006] Thus, there has been a growing interest in developing alternative fibre crops for use in the production of paper products, and alternative technologies to replace wood pulping. One source of cellulosic fibre that has been recognised as a suitable alternative to wood is the banana plant.

[0007] The banana plant is a large perennial herb with tall aerial shoots that arise from swollen, fleshy corms (an underground rhizome). The banana plant’s petioles are arranged spirally in the aerial shoots, and their long overlapping pulvini (basal enlargements) form the outer portion of a stout, trunk-like pseudostem, through the centre of which the terminal inflorescence grows, forming an inner portion often referred to as a core. Higher up, the petioles bend away from the pseudostem and bear large oval blades (leaves) at an oblique angle. When mature, each pseudostem will thus comprise a soft but dense core, surrounded by an outer portion that is tougher but is less dense.

[0008] Commercially planted banana plants typically only have 1 to 2 year lifespans, as banana plants only flower (and produce bananas) once, following which the leaves and pseudostem start to die. This usually requires their removal in some manner, such as by simply being cut down, allowing regrowth of a new pseudostem from the rhizome and the commencement of a new reproductive phase.

[0009] The stalk of a bunch of bananas, scientifically referred to as the peduncle, is also a fibrous structure that serves as the main support for the banana cluster. It originates from a banana plant's pseudostem, which itself is composed of tightly packed leaf sheaths. The peduncle contains vascular tissues, including xylem andphloem, which transport water, nutrients and sugars to the developing bananas. Its structure is reinforced with cellulose and lignin, providing mechanical strength and flexibility to support the weight of the fruit. The stalk also plays a vital role in the plant's reproductive process, as it facilitates the transfer of nutrients and hormones to the bananas during their growth and maturation.

[0010] With annual production by 2022 of about 135 million tonnes of bananas (more than two thirds coming from within India, Brazil, China, Ecuador and the Philippines), it has been recognised that banana pseudostems represent a potentially valuable renewable resource, one which has been traditionally underutilised and historically economically ignored by banana growers. There have thus been numerous attempts to use the pseudostems for the production of paper, due to the beneficial properties and qualities of the fibre in the pseudostems.

[0011] Several attempts have been made to use banana plant refuse (predominantly pseudostems, which includes petioles and cores, but also stalks, leaves, immature inflorescence and unused bananas) in existing or modified paper pulping processes - see United States patent 5,958, 182 for a short summary of some such processes. However, such refuse commonly has an extremely high water and natural latex content and includes numerous resinous and gummy substances that are difficult to handle and process.

[0012] In order to produce workable fibres having desirable characteristics for making paper, it has proven necessary to extract these fluids and, in particular, wash out the latex and other natural resinous substances. This has proven to be technically difficult and has generally made the pulping of banana refuse for the production of paper uneconomic, particularly for bulk paper supplies and for anything other than boutique or artistic papers. It has also generally presented the manufacturers with significant chemical waste disposal issues.

[0013] In Australia, while it has been reported that a good quality paper can be made in low volume by combining and pulping banana fibre and betel nut husk (Areca catechu L.), Australian investigators nonetheless concluded that the yield of banana fibre is too low for extraction in pulping processes to be economical. Indeed, in one Australian report, it was reported that only 1 to 4 oz (28-113 g) of suitable fibre could be obtained from 40 to 80 lbs (18-36 kg) of green pseudostems from a pulpingprocess. Thus, 132 tonnes of green pseudostems would yield only 1 tonne of paper. The conclusion was thus that the pseudostem would have much greater value as organic matter chopped and left in the field to fertilise subsequent crops, which indeed is where the Australian banana growing industry finds itself today.

[0014] There have also been suggestions for the use of banana plants without pulping, such as the mechanical processes described in the applicant’s own International patent publications W02006 / 029469 and WO2010 / 071945. The mechanical processes described in these documents aim to avoid the pulping problem, firstly by generating sheets of fibres directly from the pseudostems of banana plants, and secondly by forming from those sheets a fibre furnish consisting essentially of plant petiole tissue where substantially longitudinally aligned petiole fibres have been cut generally laterally to form fibres with a fibre length distribution such that at least 95% of the fibres have substantially the same predetermined fibre length.

[0015] The present invention seeks to provide a further alternative to the use of wood and to provide an improved method and apparatus for the production of a cellulosic fibrous material suitable for use in, for example, vacuum moulding to form packaging items, but also in paper and board forming machines for the production of pulp board, paper board, box board, linerboard, testliner and the like.Summary of the Invention

[0016] The present invention provides a method for producing a cellulosic fibrous material from a cellulose fibre feedstock, the method including: mechanical pre-treatment of the feedstock to form a fibre furnish having fibres with a fibre length distribution such that at least 90% of the fibres have a length less than about 25 mm; dewatering the fibre furnish to produce a first filtrate and a dewatered fibrous cake having a moisture content less than about 50% (w / w); pulping the dewatered fibrous cake at a temperature in the range of 40 to 90°C to produce a pulped fibre furnish with a consistency more than about 3% fibre (w / w);- washing the pulped fibre furnish to produce a cellulose fibre cake with a consistency of at least 20% fibre (w / w) and a second filtrate; andrefining the cellulose fibre cake in at least one refiner to produce the cellulosic fibrous material.

[0017] In one form of the present invention, an alkalising agent will be added to the pulped fibre furnish prior to washing to achieve a pH of the pulped fibre furnish between about 7.5 and about 8.5, and ideally of about 8.0. The alkalising agent will preferably be sodium bicarbonate, added in an amount in the range of 0.1 % to 2.0% of the dry fibre weight in order to increase the pH to the desired level. Other suitable alkalising agents include sodium carbonate, magnesium carbonate and calcium carbonate.

[0018] In other forms of the present invention, further additives may be added to the cellulosic fibrous material after the refining stage to improve the fibre properties and to assist with enabling different product applications. These further additives may be one or more of the following, added in the ranges indicated for the stated outcomes: a) cationic starch - 0.5% to 2% of the dry fibre weight in order to improve strength, surface finish, fines retention and drainage; b) biodegradable oil / grease / water-resistant additives such as bio-based barrier starches and water-based polymers created from agricultural cellulose - 1 % to 10% of the dry fibre weight in order to enhance moisture, oil and grease resistance; c) sizing agents, ideally natural agents such as starch, gelatin and gum arabic, but also synthetic agents such as alkyl ketene dimer (AKD) and polyvinyl alcohol (PVA) - 0.5% to 5% of the dry fibre weight in order to improve water resistance and printability; and / or d) wet-strength agents, ideally natural agents such as starch, lignin, soy protein and chitosan, but synthetic agents such as polyacrylamide and polyethyleneimine may be suitable in certain applications - 0.5% to 5% of the dry fibre weight in order to maintain fibre bonding and strength in wet conditions.

[0019] The cellulosic fibrous material produced by the inventive method is a material where the non-cellulosic components of the feedstock, such as hemicellulose, lignin, waxes, tannins and pectin have been substantially removed bymechanical means. The removal of these non-cellulosic components is advantageous due to the presence of these components in a product, and particularly on the surface of banana fibres for example, having been found to hinder interfacial bonding between fibres.

[0020] In this respect, the cellulosic fibrous material produced by the method of the present invention has been found to retain preferred physical and mechanical properties of the feedstock, within a relatively narrow size distribution, as will be discussed below. The inventive method also provides the ability to control the surface roughness of fibres in the feedstock, allowing for the tailoring of those fibres to suit different moulding process requirements.

[0021] In a preferred form, the inventive method may incorporate a homogenisation step after the refining in order to further control pulp consistency in the cellulosic fibrous material, if desirable for a subsequent moulding process, to between 0.5% and 1.0% fibre (w / w). In this form, consistency can be tuned to the particular moulding equipment selected and end product attributes targeted. For example, lower consistency will result in less fibre collecting on moulds in suction phases and lighter end products when suction time is held constant.

[0022] In one form, homogenisation may be achieved in a pulp tank utilising a paddle or blade style agitator that constantly mixes the refined pulp in the tank. Water may be added to reduce the pulp consistency and further refined pulp may be added to increase pulp consistency.

[0023] Turning to a description of the feedstock for the method of the present invention, the feedstock is preferably from banana plants in the family Musaceae. Exemplary banana plants within the family Musaceae include the genera Musella, Musa and Enseta. Alternatively, other plants, such as members of the Zingiberales order, especially the Strelitziaceae family could also be used as the feedstock for the method of the present invention. Ideally, the feedstock for the inventive method will be reasonably fresh, preferably having been harvested for no more than up to about 10 days, depending upon weather and soil contamination.

[0024] Although not to be limited thereto, the following description of the present invention will thus predominantly relate to its use with a feedstock in the form of theedible-fruited banana plants, such as those belonging to the species Musa acuminata (such as the well known bananas “Cavendish” and “Lady Finger”), Musa balbisiana, or to the hybrids Musa paradisiaca (often referred to as “plantain”) and Musa sapientum.

[0025] The mechanical pre-treatment of the feedstock ideally forms a fibre furnish having fibres with a fibre length distribution such that at least 90% of the fibres have a length less than about 25 mm. Preferably, the fibre length distribution of the fibre furnish will be such that at least 95% of the fibres have a length less than about 25 mm. More preferably, the fibre length distribution of the fibre furnish will be such that at least 95% of the fibres have a length less than about 20 mm. Most preferably, the fibre length distribution of the fibre furnish will be such that at least 95% of the fibres have a length less than or equal to about 10mm. In preferred forms, at least 98% of the fibres in the fibre furnish will have substantially the same predetermined fibre lengths mentioned above.

[0026] In this respect, it has been found to be advantageous for the efficient functioning of the subsequent refining steps if the length of the fibres in the fibre furnish is controlled to within these preferred ranges. It has also been found that any subsequent moulding of the cellulosic fibrous material produced by the inventive method is easier if the length of the fibres in the fibre furnish is controlled to within these preferred ranges.

[0027] In one form of mechanical pre-treatment, substantially longitudinally aligned petiole fibres may be obtained from plant tissue by a process of cutting disc shaped slices from a pseudostem or a stalk, using either a swinging blade, such as a chaff cutter, or a fibre production unit similar to, but larger than, the disc chipper described in the abovementioned International patent publication WO2010 / 071945, modified so as to be able to accept, for example, a whole pseudostem rather than just sheets from a pseudostem.

[0028] For example, such a modified mechanical pre-treatment apparatus might be able to both shear a pseudostem or a stalk, producing a leaf-like fibre of less than about 15 mm, 10 mm, 5 mm or most preferably equal to or less than 3 mm, and also impact, such as by compressing, crushing or beating those fibres so as to render them more flexible and commence or continue the fibrillation process. Suchapparatus might, for example, utilise a chamber that is able to receive sheared fibres and simultaneously reduce in volume to compress or crush the sheared fibres to produce a desirable (fibril lated) fibre furnish. Additionally, by combining shearing and impact actions, shreds of fibres may be produced which are also partially dewatered by the impact forces.

[0029] In another form of mechanical pre-treatment, fibres may be obtained from pseudostem or stalk tissue by a process of drum chipping. In this form, pseudostems and stalks can be presented perpendicularly to a rotating drum, in line with its central axis, rotating at between about 500 and 3000 RPM. The drum can have two to four blades that pass an anvil at the end of a feed table, resulting in a slicing motion. Ideally, the blades will pass the anvil as close as practicably possible to create a slicing motion without the blades colliding with the anvil, which will typically be less than about 3 mm and ideally between about 0.5 and 1 mm.

[0030] In this form, to improve consistency of fibre cut length, a set of horizontal feed rollers may be used to control the speed of the material entering the drum, which in turn assists to control the chip length and therefore the overall fiber length.

[0031] In one or more of these forms of mechanical pre-treatment, it can be advantageous for there to be fibres of a consistent fibre length in the fibre furnish, such as the fibre length distribution of at least 90% as mentioned above, as all of the alpha cellulose is contained in parallel bundles which run up from the ground to the tip of the plant. Keeping and preserving this natural order while slicing, instead of randomly cutting or grinding or milling, has been found to be beneficial, although not essential, as it can result in a more consistent fibre length and can tend to open the plant structure, which advantageously allows for mere mechanical compression to squeeze plant sap out in the subsequent dewatering process.

[0032] Following the mechanical pre-treatment described above, the fibre furnish produced is subjected to dewatering to produce a first filtrate and a dewatered fibrous cake having a moisture content less than about 50% (w / w).

[0033] In one form, the dewatering preferably occurs in one or more screw press, such as in one screw press in two passes, or in two screw passes in series, either continuously or as a batch process, with the first pass / press ideally removing greaterthan about 50% (w / w) of the moisture, due to gradual compression within the screw press and also due to friction between adjacent fibres and the wall of the screw press. In this form, for the second pass / press, water will ideally be added to the material entering the screw press to assist with the removal of any residual impurities on the surfaces of the fibres, to further assist with the interfacial bonding and mechanical interlocking therebetween, and to then form the dewatered fibrous cake.

[0034] A preferred form of screw press ideally conveys material along the inside of a permeable cylinder, by way of a slowly rotating Archimedean screw, preferably with a tightening pitch where the separation between the flights of the screw progressively decrease within a perforated cylindrical screen. Such a screw press is preferably inclined to the horizontal to assist with the draining of the first filtrate into a sump or the like through the screen perforations.

[0035] A pressure of at least 0.5 kg / cm2is preferred for dewatering, regardless of how many screw press passes / presses are adopted, but it will be appreciated that the determination of the desired pressure is ideally done empirically for different materials and different plant types. This preferred gradual pressurisation, and the subsequent friction between adjacent fibres and surfaces, will preferably be sufficient to separate the fibres to permit fluids to be extracted, without weakening the cell structure or losing the natural attributes of the fibres. It is expected that the preferred pressures for dewatering in a screw press will be in the range of 0.5 kg / cm2to 2.0 kg / cm2.

[0036] Ideally, screen perforations in a preferred form of screw press include a series of staggered elongate, oval-shaped, openings, preferably between 20 mm and 60 mm long, but ideally about 40 mm long, each having a mesh configured as a series of, for example, diamond-shaped perforations formed from flexibly arranged, interlocked wires. In this form, the wires preferably flex during operation, permitting the mesh to extend outwardly to form a generally concave shape during use. In this form, as fibre travels through the screen perforations, the mesh flexes and extends with the diamond-shaped gaps expanding from a width of about 1 mm to a width of about 2 to 2.5 mm.

[0037] The tightening pitch of a preferred screw press is ideally adopted to impart mechanical stress to material during the dewatering. In this respect, it will be notedthat the material input into the dewatering step may be in the form of fibrous chips of substantially equal length, but of varying width and thickness. In this form, the tightening pitch assists in providing a constant mechanical stress that forces the feedstock to work on itself and the outer screen surfaces. Subsequently, the volume of the fibre reduces due to the loss of fluid exiting through the screen slits and the conical configuration of the screw. The continuous action of the fibre chips, the mechanical pressure and the friction between adjacent surfaces maintains the extraction of fluids from the feedstock fibres passing therethrough.

[0038] The preferred geometry of the screw in a preferred screw press is such that relative movement is applied between, as mentioned above, fibres in the material and the walls of the press and the screen, as well as between each other. This interaction ideally separates fibre bundles without reduction of the fibre length. This relative movement creates enough friction to prepare the fibre surface to enable interfacial bonding and to remove any remaining non-cellulosic compounds at the fibre surface, which is preferred in order to prepare the dewatered fibrous cake prior to subsequent steps, to assist those steps to prepare and improve the surface roughness of the fibres, increasing their surface area to maximise interfacial bonds in the final product.

[0039] In another form, the dewatering preferably occurs in one or more crushing mills (such as one, two or three crushing mills), the crushing mills ideally having a series of one top and two bottom horizontal grooved rollers that the fibre furnish from the mechanical pre-treatment passes through. Preferably, the grooves of the top and bottom rollers mesh together to reduce flow of material outside of a targeted compression zone, there ideally being two compression zones for each crushing mill. In this respect, one compression zone will ideally be between the first bottom roller and the top roller, with a second compression zone between the top roller and the second bottom roller.

[0040] Further in relation to preferred forms of crushing mills, a fixed comb (that meshes with the grooves) is preferably secured on the outgoing side of each roller to scrape dewatered fibrous material off the roller, enabling the fibrous material to progress through the mill without becoming stuck to the roller and thus without recirculating on the roller. Additionally, it is advantageous to control a consistent flowof fibre furnish to the input roller of a crushing mill to assist to ensure that consistent maximal compressive forces are achieved, maximising removal of the first filtrate. This can also assist with the separation of bundled fibres, providing the initial release of colloidal material through the compressive forces and movement of the fibres across the compressive surfaces.

[0041] The first filtrate produced in this dewatering is ideally predominantly plant sap, with a chemical composition that will be generally understood by a skilled addressee, with reference to the nature and type of the feedstock used in the method. In general terms, the first filtrate includes organic acids, nutrient elements and growth regulators and, where banana plants provide the feedstock, the organic acid concentrations are relatively high and the components include beneficial compounds like gibberellic acids and cytokines and also more conventional soil improving elements such as nitrogen, phosphorous, potassium, magnesium and calcium. As a by-product of the method of the present invention, this first filtrate is expected to be usable as an organic liquid fertiliser.

[0042] The dewatered fibrous cake produced from dewatering is then subjected to pulping at a temperature in the range of 40 to 90°C, in one form without chemical addition, or in another form with the addition of an alkalising agent such as sodium bicarbonate to achieve a slightly alkaline solution with a pH of between about 7.5 and about 8.5 (and ideally about 8), or in another form with the addition of a pectinolytic enzyme, all ideally to produce a pulped fibre furnish with a consistency more than about 3% fibre (w / w). In preferred forms, the pulping may occur in more than one stage, at either the same temperature or a different temperature in each stage. For example, the temperature may be in the range of 75 to 90°C, or 80 to 90°C, or at about 85°C in one stage, and then may be in the range of 40 to 60°C, or 45 to 50°C, or at about 45°C in a second stage.

[0043] In one form, a tank with an agitator, such as a hydrapulper, will ideally be used to mix the dewatered fibrous cake with fresh water, resulting in a pulp consistency of more than about 3%. In one form, the pulp consistency will ideally be more than about 6%, such as between 6% and 10%. In other forms, the pulp consistency will be more than about 10%, such as between 10% and 14%.

[0044] Heating the pulp to the temperature in the range of 40 to 90°C assists with dissolving sugars and other undesirable components in the fibrous cake and supports the release of the dissolved and colloidal material. The heating has also been found to improve inter-fibre bonding, which results in improved tensile, tearing and burst strength of the fibres. Additionally, the heating improves the distribution of the fibres and reduces clumping in formed end products, assisting in allowing for a higher sheet surface quality and thickness. The heating also tends to increase the receptivity of fibres to refining, which tends to reduce the energy input required in later refining steps.

[0045] Irrespective of the source and type of the feedstock material, after the pulping stage the pulped fibre furnish will ideally have a moisture content greater than about 80% (w / w), preferably greater than about 85% (w / w), more preferably greater than about 90% (w / w), and most preferably greater than about 95% (w / w).

[0046] Water is preferably used as the medium to carry the released dissolved and colloidal material away from the fibre post heat treatment. A lower consistency will improve the ability of the water to carry away the dissolved and colloidal material in the washing phase, however this tends to be at the cost of higher energy inputs required for the heating.

[0047] After pulping, the pulped fibre furnish is washed to produce a cellulose fibre cake with a consistency of at least 20% fibre (w / w), or preferably at least 25% fibre (w / w), or more preferably at least 30% fibre (w / w), and a second filtrate. This washing stage ideally involves separating the fibres from the liquid medium to remove the dissolved and colloidal material from the pulp. This is preferably achieved by passing the pulped fibre furnish from the pulping stage through at least one screw press (ideally of the same general type as described above in relation to dewatering) to produce a fibrous cake.

[0048] The washing stage may be repeated in two or three or more stages to remove additional dissolved and colloidal material if required. In this respect, while any additional washing will further increase the removal of the dissolved and colloidal material from the pulp, this trends to come at the expense of a lower pulp yield.

[0049] With the operation and interaction of the inventive method steps described above, it has been found that there is no essential need for the addition to the dewatering, pulping and washing stages of the more toxic pulping chemicals traditionally adopted in paper making processes, such as chlorine, hypochlorites, caustic soda, sodium sulfide, sulfurous acid, dextrin, styrene butadiene latex or styrene acrylic, for example. Having said that, it will be appreciated that there may be some benefit in using less toxic chemicals in the pulping stage, such as the alkalising agent mentioned above, and / or after the refining stage, such as the cationic starch, sizing agents and the like mentioned above, to assist in fibre preparation.

[0050] By way of further example, the wash stages above can incorporate enzymatic washing using a pectinolytic enzyme (e.g., protopectinase, pectin esterase, hydrolyzing enzymes such as polygalacturonase, polymethylgalacturonase, or cleaving enzyme such as pectin lyase or pectate lyase). In this form, a suitable enzyme preparation may be dosed in the range of 0.01 to 1 .0 % w / w relative to dry pulp. The enzyme preparation will ideally first be dissolved or dispersed in dilution water (such as 10 to 20 g / L) to assist with ensuring even distribution. The pulp slurry - adjusted to consistency ranges previously outlined and pH 6.0 to 7.0 - will ideally be heated to within the range of 40°C to 60°C, and the enzyme solution will ideally be added slowly over 5 to 15 minutes under gentle agitation (50 to 200 rpm) to prevent shear inactivation.

[0051] Once added, the slurry may be held at these conditions for 30 to 120 minutes, allowing the enzyme to hydrolyze pectins, sugars and other non-cellulosic materials. For enhanced removal, an optional two stage wash can follow: such as to allow for an initial enzyme reaction (for 30 to 60 minutes), with a secondary hot water rinse at about 60°C (for 10 to 30 minutes) to flush out solubilized impurities. This enzymatic option can help to achieve effective decontamination at lower temperatures, preserving fibre integrity and reducing energy demand.

[0052] As also mentioned above, following the washing, the cellulose fibre cake moves on to a refining step, conducted in at least one refiner, preferably a disc refiner such as a low consistency disc refiner, being a step where the fibres of the cellulose fibre cake are finally physically modified, essentially by fibrillation and roughening.

[0053] A variety of fibre end-properties can be a direct result of this refining of the cellulose fibre cake. For example, if the fibre length is decreased, the strength and resistance to tearing of the end product produced will decrease, but the surface levelness and smoothness will increase, and the print quality will become better. As the degree of refining is increased, the density, hardness, ink holdout, smoothness, and internal bond strength will increase, but thickness, compressibility, dimensional stability, and porosity will decrease. Complicating matters is the fact that with initial refining, resistance to tearing will increase, due to the enhanced ability of the fibres to bond with each other and resist pulling away, but further refining will work to decrease tearing resistance, as the shortening of the fibres has a deleterious effect on fibre strength. In other words, increased refining will work to shorten fibres, which enhances smoothness and printability, but diminishes strength and resistance to stresses.

[0054] In the present invention, one option is for the cellulose fibre cake produced in the washing to be refined in a high consistency disc refiner, followed thereafter by a low consistency disc refiner, to produce a mouldable cellulosic fibrous material. Of course, and as mentioned above, the refining may only need to be conducted in a single disc refiner, such as a low consistency disc refiner.

[0055] Disc refiners provide flexibility that permits customisation of a fibre processing process, which assists with allowing specific metrics in refining performance to be met, ideally suiting a range of subsequent fibre pulp moulding lines that might use the mouldable cellulosic fibrous material produced by the present invention. Refining energy may range from 150 kW.h / OD tonne to 300 kW.h / OD tonne with the aim of reducing total refining energy and maintaining minimum viable final product attributes in terms of product weight, sheet thickness, surface quality and tensile, tearing and burst strengths.

[0056] A disc refiner typically consists of two vertical discs with serrated or otherwise contoured surfaces. One disc (the “rotor”) rotates clockwise, while the other disc (the “stator”) either remains stationary to provide relative rotation therebetween. Alternatively, two rotor discs may be utilised, rotating in opposite directions to provide the relative rotation. A rotor and stator will ideally have on oneside a "pattern", which might alternately consist of blades (or bars) and crevices (or grooves).

[0057] Cellulose fibre cake may be pumped between the discs of a disc refiner, ideally through an inlet in the centre of one disc. As centrifugal force pushes the fibres out toward the perimeter of the discs, the abrasion experienced between the discs by the fibres tends to delaminate and internally fibri Hate the fibres to the degree desired, increasing the tensile and burst strength of the fibres, improving the fibres flexibility and increasing the relative bonding area between fibres. The space between the discs can be widened or shortened, depending on the extent of refining required.

[0058] With regard to disc refiners, a reference to “consistency” is a reference to a dry weight percentage of a fibre in suspension, with a “low consistency” disc refiner thus being a disc refiner that is configured to operate on a material containing in the order of 1 to 5% fibre, while a high consistency disc refiner is one that is configured to operate on a material containing in the order of 15 to 40% fibre. Therefore, in the form of the invention where high consistency refining is followed by low consistency refining, fresh water will be added to the refined product leaving the high consistency disc refiner before it enters the low consistency refiner in order to alter the moisture content and thus allowing the consistency of the product to be further refined.

[0059] In low and high consistency disc refiners, the process sides of the discs are fitted with metal refining plates which are covered with a variety of raised bars. In a preferred form, a screw type or ribbon type feeder delivers a constant flow of high consistency cake into the centre of the space between the two discs. Refining takes place as the fibres travel outward between the bars of opposite discs as the rotor rotates. In this form, the rotor may be driven by a large motor and a smaller motor may be used to adjust the gap (opening and / or closing) between the plates. In this respect, it will be appreciated that low consistency disc refining tends to be more energy efficient compared to high consistency disc refining, principally due to the different dry fibre content levels operated upon in each, and also due to the configuration of bars and grooves tending to be accordingly tighter and shallower.

[0060] In addition to the inventive method mentioned above, the present invention also provides apparatus for producing a cellulosic fibrous material from a cellulose fibre feedstock, the apparatus including: mechanical pre-treatment apparatus capable of forming a fibre furnish from the feedstock, the fibre furnish having fibres with a fibre length distribution such that at least 90% of the fibres have a length less than about 25 mm; at least one dewatering press for dewatering the fibre furnish to produce a first filtrate and a dewatered fibrous cake having a moisture content less than about 50% (w / w); a pulper for pulping the dewatered fibrous cake at a temperature in the range of 40 to 90°C to produce a pulped fibre furnish with a consistency more than about 3% fibre (w / w); at least one washer for washing the pulped fibre furnish to produce a cellulose fibre cake with a consistency of at least 20% fibre (w / w) and a second filtrate; and at least one refiner to produce the cellulosic fibrous material from the cellulose fibre cake.

[0061] In one form of the present invention, an alkalising agent will be added to the pulper prior to washing to achieve a pH of the pulped fibre furnish between about 7.5 and about 8.5, and ideally of about 8.0. The alkalising agent will preferably be sodium bicarbonate, added in an amount in the range of 0.1 % to 2.0% of the dry fibre weight in order to increase the pH to the desired level. Other suitable alkalising agents include sodium carbonate, magnesium carbonate and calcium carbonate.

[0062] In other forms of the present invention, further additives may be added after the refining stage to improve the fibre properties to assist with enabling different product applications. These further additives may be one or more of the following, added in the ranges indicated for the stated outcomes: a) cationic starch - 0.5% to 2% of the dry fibre weight in order to improve strength, surface finish, fines retention and drainage; b) biodegradable oil / grease / water-resistant additives, such as bio-based barrier starches and water-based polymers created from agricultural cellulose - 1 %to 10% of the dry fibre weight in order to enhance moisture, oil and grease resistance; c) sizing agents, ideally natural agents such as starch, gelatin and gum arabic, but also synthetic agents such as alkyl ketene dimer (AKD) and polyvinyl alcohol (PVA) - 0.5% to 5% of the dry fibre weight in order to improve water resistance and printability; and / or d) wet-strength agents, ideally natural agents such as starch, lignin, soy protein and chitosan, but also synthetic agents such as polyacrylamide and polyethyleneimine may be suitable in certain applications - 0.5% to 5% of the dry fibre weight in order to maintain fibre bonding and strength in wet conditions.

[0063] The apparatus may further include at least one homogenisation tank for re-pulping and homogenisation of the cellulosic fibre material to produce a homogenised cellulosic fibre material with a consistency of less than about 1 % fibre (w / w). The further additives mentioned above that might be added after the refining stage may be added to such a homogenisation tank.

[0064] Finally, it will be appreciated that the cellulosic fibrous material produced by the refining step may subsequently be moulded and dried in a suitable manner and to a suitable extent, depending upon the product output specifications.

[0065] While not wishing to be bound by theory, it is understood that cellulosic fibrous material produced by the present invention will have increased its fibre length by more than about 10%, with the width of the fibre ideally having decreased by more than about 15%, with fibre coarseness ideally having decreased by about 10%. Also, it is understood that the amount of kinked or broken fibres is able to be reduced by the method of the present invention, and the fibre softness tends to be improved compared to the fibres of the original feedstock.

[0066] Advantageously, the method of the present invention provides for a lower cost process, not simply because the preferred feedstock has traditionally been regarded as a waste material, but because the method utilises simple and quick, low energy mechanical steps.Brief Description of the Drawings

[0067] An embodiment will now be described, by way of example only, with reference to exemplary apparatus that can be used to produce the cellulosic fibrous material mentioned above. However, it is to be appreciated that the following description of the accompanying drawings and example only exemplifies one way of putting the present invention into practice. The following description is thus not to be read as limiting the above general description. In the accompanying drawings:

[0068] Figure 1 is a flowsheet that schematically illustrates a preferred embodiment of a method according to the present invention;

[0069] Figures 2(a) and 2(b) are schematic illustrations of a preferred form of screw press for use with the preferred embodiment of Figure 1 ; and

[0070] Figure 3 is a schematic illustration of a preferred form of disc refiner for use with the preferred embodiment of Figure 1 .Detailed Description of the Drawings

[0071] Generally illustrated in the flowsheet of Figure 1 is a preferred embodiment of the method of the present invention, the method including the mechanical pre-treatment of a banana pseudostem feedstock to form a fibre furnish, passing the fibre furnish to a dewatering stage to produce a first filtrate and a dewatered fibrous cake, pulping the dewatered fibrous cake with heat to produce a pulped fibre furnish, washing the pulped fibre furnish to produce a cellulose fibre cake and a second filtrate, and then re-pulping and refining the cellulose fibre cake in a disc refiner to produce a refined pulp. Then, with the addition of some pulp additives to achieve desired water resistance, wet strength and dry strength properties, a cellulosic fibrous material is produced suited to a particular product application. In this embodiment, the cellulosic fibrous material is added to recirculating pulp for homogenisation in coordination with the board or paper production, or vacuum moulding and drying, for the ultimately reguired products.

[0072] Referring to the mechanical pre-treatment stage shown in Figure 1 , in this embodiment this is achieved by drum chipping. Although not illustrated, such drum chipping will be understood by a skilled addressee. In this respect, the banana pseudostems (and also stalks if desired) are presented perpendicularly to a rotatingdrum, in line with its central axis, rotating at between about 500 and 3000 RPM. In this embodiment, the drum has four blades that pass an anvil at the end of a feed table, resulting in a slicing motion. The blades will pass the anvil as close as practicably possible to create the slicing motion without the blades colliding with the anvil, which is between about 0.5 and 1.0mm. A set of horizontal feed rollers are also used to control the speed of the material entering the drum, which in turn assists to control the chip length and therefore the overall fiber length.

[0073] The following table (Table 1 ) illustrates physical and chemical characteristics of ideal fibre furnishes prepared by such a mechanical pre-treatment step.Table 1

[0074] With respect to exemplary operation parameters and conditions for the subsequent method steps of Figure 1 , reference is made to the following:Option 1 : Mechanical Pre-Treatment and Dewatering of PseudostemsBanana Plantation Waste Input 6.5 tonne / hrMechanical Pre-Treatment andDewatering Capacity 6.5 tonne / hrDewatered fibrous biomass output 0.16 tonnes / tonne of wasteFirst (Sap) Filtrate Output 0.84 tonne / tonne wasteOption 2: Mechanical Pre-Treatment and Dewatering of StalksBanana Plantation Waste Input 2.0 tonne / hrMechanical Pre-Treatment andDewatering Capacity 2.0 tonne / hrDewatered fibrous biomass output 0.50 tonnes / tonne of wasteFirst (Sap) Filtrate Output 0.50 tonne / tonne wastePulping with Heat TreatmentPulping Capacity 11 m3 / hrDewatered fibrous biomass input 1.04t / hourConsistency 6% W / WHeating 85 Deg CWashing and Re-PulpingScrew Press Capacity 11 m3 / hrCellulose fibre cake Output 2.2t / hourCellulose fibre cake O.D. Fibre 20% W / WRe-Pulping Consistency 6% W / WRefiningFibre Refining Capacity 9 m3 / hrOven Dry Fibre Input 0.26 tonne / hrInput Consistency 3% W / WWater Input 8.74 m3 / hrOven Dry Fibre Output 0.26 tonne / hrOutput Consistency 3% W / WPulp HomogenisationCapacity 27m3 / hrRefined Pulp Input Volume 9 m3 / hrPulp Input Consistency 3% W / WWater Input (recirculating and fresh) 18 m3 / hr Output Consistency 1 % W / WOption 1 : Exemplary Moulded Product ProductionMoulded Product Production Capacity 10,000 pieces / hrOven Dry Fibre Input 0.26 tonne / hrInput Consistency 1 % W / WTray Weight 25 GramsPrime Yield 96%Option 2: Exemplary Pulp Board Product ProductionProduct Production Capacity 0.25 tonne / hrOven Dry Fibre Input 0.26 tonne / hrInput Consistency 1 % W / WTray Weight 25 GramsPrime Yield 96%

[0075] Turning to a description of preferred forms of apparatus, as mentioned above the dewatering and pulp washing in this embodiment will occur continuously in two screw presses 110 arranged in series, separated by a wash tank, with the combined presses 110 removing greater than about 90% (w / w) of the moisture within the fibre furnish, due to gradual compression within the screw press and also due to friction between adjacent fibres 112 and the perforated wall 114 of the screw press 110 - see description of Figures 2(a) and 2(b) below. Before a second screw press (not shown), water is added in a wash tank (not shown) to the material entering the second screw press to assist with the removal of any residual impurities on the surfaces of the fibres 112, to further assist with the interfacial bonding and mechanical interlocking therebetween and to form the dewatered fibrous cake 116.

[0076] Referring more specifically to Figures 2(a) and 2(b), the screw press 110 of this embodiment conveys the fibre furnish 100 in the form of fibres 112 along the inside of the perforated wall 114 in the form of a permeable cylindrical screen, by way of a slowly-rotating Archimedean screw 118 with a tightening pitch. The screw press 110 includes a sump 120 to assist with the draining of the first filtrate 104, via the screen perforations 130 seen in Figure 2(b).

[0077] In this respect, the screen perforations 130 include a series of staggered elongate, oval-shaped, openings about 40mm long, each having a mesh configured as a series of diamond-shaped perforations formed from flexibly arranged, interlocked wires, such that the wires can flex during operation, permitting the mesh to extend outwardly to form a generally concave shape during use. In this form, as fibre travels through the screen perforations 130, the mesh flexes and extends with the diamond-shaped gaps expanding from a width of about 1 mm to a width of about 2 to 2.5 mm.

[0078] A pressure of at least 0.5 kg / cm2is preferred for the dewatering stage, regardless of how many passes are adopted, but it will be appreciated that the determination of the desired pressure is ideally done empirically for different feedstocks and different plant types. It is expected that the preferred pressures for the dewatering stage will be in the range of 0.5 kg / cm2to 2.0 kg / cm2.

[0079] The tightening pitch of the screw press 110 is adopted to impart mechanical stress to the fibre furnish 100 during the dewatering. In this embodiment, the fibre furnish 100 input into the dewatering stage is in the form of fibrous chips 112 of substantially equal length, but of varying width and thickness. The tightening pitch assists in providing a constant mechanical stress that forces the chips 112 to work on themselves, the screw 118 and the interior of the perforated wall 114. The volume of the fibre chips 112 reduces due to the loss of fluid exiting through the screen perforations 130.

[0080] The first filtrate 104 produced in the dewatering stage is predominantly plant sap, with a chemical composition that will be generally understood by a skilled addressee, with reference to the nature and type of the feedstock used in the method. In general terms, the liquid filtrate includes organic acids, nutrient elements and growth regulators and, where banana plants provide the feedstock, the organic acid concentrations are relatively high and the components include beneficial compounds like gibberellic acids and cytokines and also more conventional soil improving elements such as nitrogen, phosphorous, potassium magnesium and calcium. As a by-product of the method of the present invention, the first filtrate is expected to be usable as an organic liquid fertiliser.

[0081] As mentioned above, the dewatering stage produces a dewatered solid in the form of a dewatered fibrous cake 116 with a moisture content less than about 50% (w / w). At this stage however, the physical characteristics of the fibres in the dewatered fibrous cake 116 are not likely to have been modified from the form of the fibres in the original fibre furnish 100.

[0082] Returning to the flowsheet of Figure 1 , following dewatering, in this embodiment the dewatered fibrous cake 116 is pulped at a temperature in the range of 45 to 90°C, in this embodiment with the addition of the alkalising agent sodium bicarbonate to achieve of pH in the range of about 7.5 to about 8.5, to produce the pulped fibre furnish. In this embodiment, the pulping is conducted in a tank with an agitator, in the form of a hydrapulper, mixed with fresh water, resulting in a pulp consistency of more than 3% fibre (w / w).

[0083] The pulped fibre furnish is then washed to produce a cellulose fibre cake with a consistency of at least 10% fibre (w / w) and a second filtrate. This washing stage involves separating the fibres from the liquid medium to remove the dissolved and colloidal material from the pulp, which is achieved by passing the pulped fibre furnish from the pulping stage through a washer, in this embodiment being a screw press of the same type as described above in relation to the dewatering, to produce the cellulose fibre cake.

[0084] The washed cellulose fibre cake then moves on to the refining stage, being a step where the fibres of the cellulose fibre cake are physically modified. In this embodiment, it has been found to be particularly beneficial if the cellulose fibre cake is refined in a single low consistency disc refiner. However, it is to be appreciated that any suitable number of disc refiners may be used, including one, two, three, four or more, either in series or in parallel to maximise or improve the refining activity occurring, or for other reasons.

[0085] An exemplary disc refiner 140 is shown in Figure 3, consisting of two vertical discs with serrated or otherwise contoured surfaces. One disc (the “rotor” 142) rotates clockwise, while the other disc (the “stator” 144) remains stationary to provide relative rotation therebetween. The rotor 142 and the stator 144 both have on their respective interior sides, and facing each other, a "pattern" which alternately consists of blades (or bars 146) and crevices (or grooves 148).

[0086] The cellulose fibre cake 102 is pumped via inlet 150 by a screw-type feeder 156 to the space 152 between the discs 142,144 of the disc refiner 140, through an inlet 154 in the centre of one disc 142. As centrifugal force pushes the fibres out toward the perimeter of the discs 142,144, the abrasion experienced between the discs 142,144 by the fibres tends to delaminate and internally fibrillate the fibres to the degree desired, increasing the tensile and burst strength of the fibres, improving the fibres flexibility and increasing the relative bonding area between fibres. The space 152 between the discs 142,144 can be widened or shortened, depending on the extent of refining required. The rotor 142 and screwtype feeder 156 are driven by a large motor 158 and a smaller motor 160 may be used to adjust the space 152 (opening and / or closing) between the discs 142,144.

[0087] As mentioned above, the reference to “consistency” is a reference to a dry weight percentage of a fibre in suspension, with a “low consistency” disc refiner thus being a disc refiner that is configured to operate on a material containing in the order of 1 to 5% fibre (w / w), while a high consistency disc refiner is one that is configured to operate on a material containing in the order of 15 to 40% fibre (w / w).

[0088] Subsequently, and again as summarised above, in this embodiment there is also included a homogenisation step after the refining in order to further control pulp consistency in the mouldable cellulosic fibrous material to between 0.5% and 1.0% fibre (w / w). The homogenisation is achieved in a pulp tank utilising a paddle style agitator that constantly mixes the refined pulp in the tank. Water is added to reduce the pulp consistency and further refined pulp is added to increase pulp consistency, as desired.

[0089] In some embodiments, further additives may be added after the refining stage, such as to this homogenisation step, to improve the fibre properties to assist with enabling different product applications. These further additives may be one or more of the following, added in the ranges indicated for the stated outcomes: a) cationic starch - 0.5% to 2% of the dry fibre weight in order to improve strength, surface finish and drainage; b) biodegradable oil / grease / water-resistant additives such as bio-based barrier starches and water-based polymers created from agricultural cellulose - 1 %to 10% of the dry fibre weight in order to enhance moisture, oil and grease resistance; c) sizing agents, ideally natural agents such as starch, gelatin and gum arabic, but also synthetic agents such as alkyl ketene dimer (AKD) and polyvinyl alcohol (PVA) - 0.5% to 5% of the dry fibre weight in order to improve water resistance and printability; and / or d) wet-strength agents, ideally natural agents such as starch, lignin, soy protein and chitosan, but also synthetic agents such as polyacrylamide and polyethyleneimine may be suitable in certain applications - 0.5% to 5% of the dry fibre weight in order to maintain fibre bonding and strength in wet conditions.

[0090] Finally, it will be appreciated that this embodiment has been described by way of example only, and that variations and modifications within the spirit and scope of the invention are also envisaged.

Claims

The claims defining the invention are as follows:1 . A method for producing a cellulosic fibrous material from a cellulose fibre feedstock, the method including:- mechanical pre-treatment of the feedstock to form a fibre furnish having fibres with a fibre length distribution such that at least 90% of the fibres have a length less than about 25 mm;- dewatering the fibre furnish to produce a first filtrate and a dewatered fibrous cake having a moisture content less than about 50% (w / w);- pulping the dewatered fibrous cake at a temperature in the range of 40 to 90°C to produce a pulped fibre furnish with a consistency more than about 3% fibre (w / w);- washing the pulped fibre furnish to produce a cellulose fibre cake with a consistency of at least 20% fibre (w / w) and a second filtrate; and- refining the cellulose fibre cake in at least one refiner to produce the cellulosic fibrous material.

2. A method according to claim 1 , wherein the feedstock is formed from banana plants in the family Musaceae, including the genera Musella, Musa and Enseta.

3. A method according to claim 1 or claim 2, wherein an alkalising agent is added to the pulped fibre furnish prior to washing to achieve a pH of the pulped fibre furnish between about 7.5 and about 8.5, and preferably of about 8.0.

4. A method according to claim 3, wherein the alkalising agent is one or more of sodium bicarbonate, sodium carbonate, magnesium carbonate and calcium carbonate.

5. A method according to claim 3, wherein the alkalising agent is sodium bicarbonate added in an amount in the range of 0.1 % to 2.0% of the dry fibre weight.

6. A method according to any one of claims 1 to 5, wherein the mechanical pretreatment is conducted by drum chipping or swinging-blade / disc chipping.

7. A method according to any one of claims 1 to 6, wherein the fibre length distribution of the fibre furnish produced in the mechanical pre-treatment stepis such that at least 90% of the fibres have a length less than about 25 mm, or more preferably is such that at least 95% of the fibres have a length less than about 25 mm, or most preferably is such that at least 95% of the fibres have a length less than or equal to about 10 mm.

8. A method according to claim 7, wherein at least 98% of the fibres in the fibre furnish will have substantially the same predetermined fibre lengths.

9. A method according to any one of claims 1 to 8, wherein the dewatering occurs in one or more dewatering press, such as in one press in two passes, or in two passes in series, either continuously or as a batch process.

10. A method according to claim 9, wherein the dewatering occurs in two presses, with the first pass removing greater than about 50% (w / w) of the moisture within the fibre furnish.

11. A method according to claim 9 or claim 10, wherein each dewatering press is a screw press that conveys fibre furnish along inside a permeable cylinder, by way of a slowly-rotating screw with a tightening pitch where the separation between flights of the screw progressively decrease, within a perforated cylindrical screen.

12. A method according to claim 8, wherein pressures for the dewatering in a screw press are in the range of 0.5 kg / cm2to 2.0 kg / cm213. A method according to any one of claims 1 to 12, wherein the pulping occurs in more than one stage, at either the same temperature or a different temperature in each stage.

14. A method according to claim 13, wherein the temperature is in the range of 75 to 90°C, or 80 to 90°C, or at about 85°C in one stage, and then is in the range of 40 to 60°C, or 45 to 50°C, or at about 45°C in a second stage.

15. A method according to any one of claims 1 to 14, wherein the pulping occurs in a tank with an agitator, such as a hydrapulper, and includes mixing the dewatered fibrous cake with fresh water, resulting in a pulp consistency of more than about 3%, or more than about 6%, such as between 6% and 10%, or more than about 10%, such as between 10% and 14%16. A method according to any one of claims 1 to 15, wherein the pulped fibre furnish has a moisture content greater than about 80% (w / w), preferably greater than about 85% (w / w), more preferably greater than about 90% (w / w), and most preferably greater than about 95% (w / w).

17. A method according to any one of claims 1 to 16, wherein the pulped fibre furnish is washed by being passed through at least one dewatering press, such as a screw press.

18. A method according to any one of claims 1 to 17, wherein the method includes refining the cellulose fibre cake in one low consistency disc refiner.

19. A method according to claim 18, wherein the disc refiner includes two vertical discs with contoured surfaces, whereby one disc rotates clockwise, while the other either remains stationary or rotates counter-clockwise, and wherein the cellulose fibre cake is pumped between the discs through an inlet in the centre of one disc.

20. A method according to any one of claims 1 to 19, wherein additives are added after the refining stage, the additives being one or more of the following: a) cationic starch - 0.5% to 2% of the dry fibre weight; b) biodegradable oil / grease / water-resistant additives such as bio-based barrier starches and water-based polymers created from agricultural cellulose - 1 % to 10% of the dry fibre weight; c) sizing agents, ideally natural agents such as starch, gelatin and gum arabic, but also synthetic agents such as alkyl ketene dimer (AKD) and polyvinyl alcohol (PVA) - 0.5% to 5% of the dry fibre weight; and / or d) wet-strength agents, ideally natural agents such as starch, lignin, soy protein and chitosan, but also synthetic agents such as polyacrylamide and polyethyleneimine - 0.5% to 5% of the dry fibre weight.

21. A method according to any one of claims 1 to 20, wherein the wash stage includes enzymatic washing using a pectinolytic enzyme preparation, the enzyme preparation including protopectinase, pectin esterase, hydrolyzingenzymes such as polygalacturonase, polymethylgalacturonase, or cleaving enzyme such as pectin lyase or pectate lyase.

22. A method according to claim 21 , wherein the enzyme preparation is dissolved or dispersed in dilution water in the range of 10 to 20 g / L and is then dosed in the range of 0.01 to 1 .0 % w / w relative to dry pulp.

23. A method according to claim 22, wherein the diluted enzyme preparation is added over 5 to 15 minutes under gentle agitation (50 to 200 rpm) and is then held for 30 to 120 minutes allowing the enzyme to hydrolyse pectins, sugars and other non-cellulosic materials.

24. Apparatus for producing a cellulosic fibrous material from a cellulose fibre feedstock, the apparatus including:- mechanical pre-treatment apparatus capable of forming a fibre furnish from the feedstock, the fibre furnish having fibres with a fibre length distribution such that at least 90% of the fibres have a length less than about 25 mm;- at least one dewatering press for dewatering the fibre furnish to produce a first filtrate and a dewatered fibrous cake having a moisture content less than about 50% (w / w);- a pulper for pulping the dewatered fibrous cake at a temperature in the range of 40 to 90°C to produce a pulped fibre furnish with a consistency more than about 3% fibre (w / w);- at least one washer for washing the pulped fibre furnish to produce a cellulose fibre cake with a consistency of at least 20% fibre (w / w) and a second filtrate; and- at least one refiner to produce the cellulosic fibrous material from the cellulose fibre cake.

25. Apparatus according to claim 24, further including at least one homogenisation tank for re-pulping and homogenisation of the cellulosic fibre material to produce a homogenised cellulosic fibre material with a consistency of less than about 1 % fibre (w / w).

26. A cellulosic fibrous material produced by the method of any one of claims 1 to 23.

27. An item formed from the cellulosic fibrous material of claim 26.

28. A filtrate produced by the method of any one of claims 1 to 23.

29. A liquid fertiliser produced from the filtrate of claim 28.

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