Manufacturing process for rigid cellulose products

Abstract

1. A process for producing a rigid cellulosic product from raw fibrous industrial waste, comprising: (a) providing or producing pulped industrial waste cellulose fibers derived from raw fibrous industrial waste; (b) enzymatically treating the pulped industrial waste cellulose fibers to produce enzyme-treated industrial waste cellulose fibers; (c) compressing the enzyme-treated industrial waste cellulose fibers to produce compressed fibers; and (d) drying the compressed fibers to form a rigid cellulosic product.

Description

[Technical Field]

[0001] The present invention relates to a process for producing rigid cellulosic products from raw fibrous industrial waste. Specifically, the present invention relates to the enzymatic treatment of industrial waste cellulosic fibers and the subsequent processing of the enzymatically treated fibers to produce fire-retardant rigid cellulosic products, such as boards, and the fire-retardant rigid cellulosic products. [Background technology]

[0002] Industrial waste is defined as non-reusable waste, and therefore cannot be reused or repurposed (or recycled) to produce other useful products, or it would otherwise be, for example, deposited in landfills or incinerated, with the associated negative environmental impacts and costs. The present invention focuses on the reuse of cellulose fibers from said industrial waste to obtain rigid cellulose products with mechanical properties suitable for use, for example, as building boards.

[0003] Cellulose fibers are considered non-reusable if at least one of the following characteristics applies: - average fiber length less than 5 mm, - average fiber thickness less than 0.1 mm, - The proportion of fines (or fine components / fines) in the cellulosic waste is greater than 10% by mass (fines are defined as the smallest components in the cellulose fiber fraction that can pass through a pore with a diameter of 76 micrometers [SCAN. Mechanical and chemical pulps - Fines content. Standard CM 66:052005]), or - Cellulose fibers are mixed with other compounds that cause recycling complications (these other compounds include inorganic fillers, synthetic compounds, and material impurities).

[0004] Waste paper and waste cardboard can be effectively recycled if they contain low levels of adhesives, inks, water-resistant resins, and other additives. Examples of these water-resistant resins and additives include alkyl ketene dimers, alkenyl succinic anhydrides, epichlorohydrin, melamine, urea-formaldehyde, polymines, styrene, dextrins, or other polymers that improve certain material properties (i.e., polyurethane, vinyl, and acrylic adhesives improve mechanical properties).

[0005] However, when waste paper and cardboard contain large amounts of these additives, the recycling costs and the quality of the resulting cellulosic products can be significantly affected, requiring additional processing steps and / or increasing the consumption of additives or energy during processing of the cellulosic material.

[0006] The paper and cellulose manufacturing industries also generate large amounts of industrial waste, including what is called primary sludge, a liquid containing cellulosic material that is considered non-recyclable as defined by the characteristics described above. This sludge is considered a discharge that carries significant environmental liability for the producer, but Applicant has discovered that this can be mitigated by appropriate treatment, including, for example, enzymatic treatment to produce cellulosic products such as building boards. It will be understood that the starting cellulosic fibers for papermaking can be any fiber, wood, or fiber derived from other plants, including, for example, fast-growing species such as miscanthus.

[0007] Primary sludge is composed of approximately 40-90% by weight of cellulose fiber and approximately 10-60% by weight of inorganic fillers. These inorganic fillers are added during the papermaking process to improve the properties of the paper. The raw cellulose material obtained from primary sludge described in this invention is characterized by a large amount of fines, exceeding 15% of the cellulose fiber. Fines are small particles composed of cellulose, but due to their size, they do not have the shape of fibers. This peculiarity means that the raw cellulose material used in the method of this invention cannot be used to manufacture paper or other products that require good mechanical properties, because the edges do not provide mechanical bonding. The above-mentioned peculiarities of this raw cellulose material make it very difficult to obtain products that require low-humidity, low-pressure, and low-temperature processes.

[0008] Another source of industrial waste that meets the above characteristics of fibers is cellulosic fiber residue streams or sludge from the textile industry, where the presence of, for example, different types of cellulosic fibers and plastic mixtures makes it difficult to reuse or recycle these residues.

[0009] Another source of industrial waste that meets the above fiber characteristics but is not a residual stream from paper or textile (or fiber / textile) manufacturing plants is construction waste cellulose fiber, e.g., cardboard recovered when recycling gypsum board. Gypsum-based recovery processes separate the gypsum from the paper through mechanical crushing and subsequent dry double pressing, resulting in a finished product with the same properties as natural gypsum. The recovered gypsum powder is 97.6% pure and virtually paper-free. While the gypsum by-product can be recycled, the cellulose fiber is typically incinerated without being used to form useful products.

[0010] A further source of industrial waste that meets the above characteristics of fiber is post-consumer vegetable or plant-based waste, such as miscanthus, which has been used in consumer products and is considered unsuitable for forming useful products. Summary of the Invention [Problem to be solved by the invention]

[0011] Applicant has discovered that by appropriate processing, including enzyme treatment of fibers and processing of those treated fibers, cellulose fibers derived from previously non-recyclable industrial waste can ultimately be used to produce useful cellulose products, such as building boards, that have the environmental benefits associated with reusing material that would otherwise end up in landfills, and importantly, provide cellulose products that perform at or above the performance of products derived from other cellulose fibers or cellulose products obtained using alternative processes that have a greater negative environmental impact.

[0012] It is also important that the building board exhibits good fire reaction properties that meet regulatory requirements without adversely affecting the base properties of the board such as mechanical strength, moisture resistance, etc., and that the board retains its environmental qualifications.

[0013] Although there are commercially available chemical additives with flame reaction properties that can be used to improve this property in medium density fiberboard, these additives are either not sufficiently compatible with the sludge and therefore have limited effectiveness in improving flame reaction or are not environmentally friendly. [Means for solving the problem]

[0014] Thus, according to the present invention, there is provided a process for producing rigid cellulose products from raw fibrous industrial waste, the process comprising: (a) providing or producing pulped post-industrial cellulose fibers from raw fibrous post-industrial waste; (b) enzymatically treating the pulped post-industrial cellulosic fibers to produce enzyme-treated post-industrial cellulosic fibers; (c) compressing the enzyme-treated industrial waste cellulose fibers to form compressed fibers; and (d) drying the compressed fibers to form a rigid cellulosic product, said rigid cellulosic product having a fire classification of at least Class C when tested according to European Standard EN 13501-1.

[0015] Advantageously, the process of the present invention produces flame-retardant rigid cellulose products using a proportion of raw fibrous cellulose material from industrial processes, such as those for the production of paper, cardboard, textiles or building materials, or from other waste sources where the residual cellulose material cannot be reused for the reasons defined in the fiber characteristics above, and which is low quality fibrous cellulose material, mainly comprising fibers that are typically shorter than 5 mm, and / or brittle fibers, and / or recycled fibers that are typically partially bound with impurities and therefore have a reduced ability to bind with other cellulose fibers.

[0016] Advantageously, the rigid cellulosic products of the present invention are not only sustainably produced, but also meet a fire classification of at least Class C without adversely affecting the base properties of the board.

[0017] Without enzyme treatment, industrial waste cellulose fibers, such as primary sludge from the paper industry, cannot be reused to make useful cellulose products without the use of resins or adhesives because the fibers are too short to impart sufficient mechanical properties to the board.

[0018] Preferably, the process further comprises the step of selecting the amount of post-industrial cellulose fibers such that the calcium carbonate content of the post-industrial cellulose fibers compared to the weight of the rigid cellulose product is sufficient to obtain a rigid cellulose product having a fire classification of at least Class C when tested according to European Standard EN 13501-1. More preferably, the rigid cellulose board has a calcium carbonate content of more than 7 wt%, preferably more than 7 wt% and less than 50 wt%, more preferably more than 7 wt% and less than 35 wt%, compared to the weight of the rigid cellulose product.

[0019] Advantageously, the amount of post-industrial cellulose fibre is selected so that the calcium carbonate content is sufficient to obtain a rigid cellulose product having a fire classification of at least Class C.

[0020] Preferably, the process method further comprises the step of adding a flame retardant to the post-industrial cellulosic fibers, preferably an expandable volcanic mineral, more preferably vermiculite or perlite, to further improve flame retardancy beyond that achievable by relying solely on calcium carbonate content.

[0021] Preferably, the expansive volcanic mineral is added in an amount sufficient to have an expansive volcanic mineral content of greater than 5 wt.% dry mass relative to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested according to European Standard EN 13501-1.

[0022] Preferably, the source of post-industrial cellulose fibres is selected to be free of calcium carbonate, for example textile sludge residues from the textile manufacturing industry or construction waste cellulose fibres, and the process further comprises the step of adding a flame retardant, preferably aluminium hydroxide, to the non-calcium carbonate containing industrial waste cellulosic fibres.

[0023] Preferably, aluminium hydroxide is added to the calcium carbonate-free waste cellulose fibres in a sufficient amount so that the rigid cellulose product has an aluminium hydroxide content of greater than 15 wt.% dry mass relative to the weight of the rigid cellulose product to provide a rigid cellulose product having a fire classification of Class B when tested according to European Standard EN 13501-1.

[0024] Preferably, the step of producing pulped post-industrial cellulose fibers comprises pulping raw fibrous post-industrial cellulose fibers.

[0025] Preferably, the process further comprises the step of diluting the raw fibrous industrial waste with water before or during pulping.

[0026] Alternatively, however, the raw fibrous industrial waste may not require a separate pulping step prior to enzymatic treatment and can be supplied as already pulped fibres, i.e. fibres sufficiently individualised to be substantially free of agglomerates (which if left untreated would result in ineffective enzymatic treatment, reduced distribution of the forming fibres and a non-uniform final product). The already pulped fibre supply can be the direct output from an industrial plant, preferably a supply of sludge output from a plant for producing paper or textiles.

[0027] The pulped fibers supplied can be supplied directly to the process for producing a rigid cellulosic product from the sludge output via a conduit to the sludge output, or indirectly to the process for producing a rigid cellulosic product via an intermediate storage tank.

[0028] By raw fibrous cellulosic material is meant material that is composed primarily of fibers made from cellulose and other vegetable compounds that are capable of forming bonds with other cellulosic fibers.

[0029] The enzymatic process increases the number of free hydroxyls in the fibers, allowing the industrial waste fibers to cross-link and bond with other non-industrial fibers and / or each other to produce cellulosic products such as building boards or panels with sufficient mechanical properties for the intended end use.

[0030] Preferably, the raw fibrous industrial waste comprises fibers having one or more of the following: 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%.

[0031] Preferably, the post-industrial fibres are derived from one or more of primary sludge obtained from the paper industry or sludge residues from the textile manufacturing industry.

[0032] Post-industrial fiber means fiber obtained from an industrial process, such as papermaking, cardboard manufacturing, or textile manufacturing, to produce paper, cardboard, or textile products, or from any industrial process in which the cellulosic fiber is not considered reusable to form a useful cellulosic product. Discarded or recycled cardboard is not considered post-industrial waste.

[0033] In the present invention, the terms primary sludge and sewage sludge can be used interchangeably.

[0034] Preferably, the process further comprises the step of diluting the raw fibrous industrial waste with water before or during pulping.

[0035] Preferably, the step of enzymatically treating the pulped post-industrial cellulosic fibers to produce enzyme-treated post-industrial cellulosic fibers includes maintaining a moisture content greater than 80% during the enzyme treatment.

[0036] Preferably, the step of enzymatically treating the pulped post-industrial cellulosic fibers to produce enzyme-treated post-industrial cellulosic fibers includes maintaining a moisture content greater than 90% during the enzyme treatment.

[0037] Preferably, the step of maintaining the moisture content at greater than 80% during enzyme treatment comprises maintaining the moisture content at greater than 80% to 99%, more preferably greater than 80% to 95% during enzyme treatment.

[0038] Preferably, the step of diluting the enzyme-treated industrial waste fiber to obtain diluted enzyme-treated industrial waste fiber having a moisture content of greater than 90% comprises diluting to ensure that the moisture content remains greater than 90% and less than 99%, preferably greater than 95% and less than 99%.

[0039] Preferably, the raw fibrous cellulosic material from industrial waste does not contain large particles or clusters greater than 5 mm, since such particles or clusters have reduced or no ability to form bonds with other cellulosic fibers. Depending on the type of raw fibrous cellulosic material, a particle size reducer, such as a crusher or shredder, can be used prior to pulping to reduce particle size or remove particles or clusters. For example, materials that are difficult to pulp without size reduction, such as miscanthus or textile waste, may require this additional particle size reduction step.

[0040] Alternatively, the raw fibrous cellulosic material can include larger particles or clusters greater than 5 mm, provided that they can be dissolved or broken down during pulping into smaller particles or clusters smaller than 5 mm, or fibers of any length. Examples of large soluble or breakable particles or clusters can be, for example, cardboard or sludge lumps.

[0041] Preferably, the step of enzymatically treating the industrial waste cellulose fibers includes adding one or more enzymes to the industrial waste cellulose fibers for one or more of smoothing the fibers, removing radicals from the outside of the fibers, and increasing the specific surface area of ​​the fibers.

[0042] Preferably, the step of enzymatically treating the industrial waste cellulose fibers comprises one or more of the following: -Maintaining the pH of the pulped fiber between 5 and 9; - maintaining the temperature during the enzymatic treatment of step (b) above 40°C, preferably above 40°C and below 70°C; - adding one or more enzymes selected from the group of xylanases, laccases and cellulases, - Adding 0.05% to 0.5% of enzymes based on the dry weight of industrial waste cellulose fiber; - treating industrial waste cellulose fibres with an enzyme for a period of more than 5 minutes, preferably more than 5 minutes but less than 60 minutes.

[0043] The applicant has recognized that for industrial cellulose waste, an enzymatic treatment process is important not only for fiber fibrillation, but also for cleaning the fiber surface using xylanase and laccase enzymes. Xylanase enzymes attack hemicellulose and promote extraction of the surface layer of the cellulose fiber, thereby eliminating impurities that may be carried by various additives or residues from the process prior to the generation of residues. Laccase enzymes also help remove impurities, primarily lignin, that interfere with pulping.

[0044] The present applicant has also discovered that the presence of fines can hinder the processing of diluted cellulose industrial waste fibers. For example, fines reduce the dewatering ability of enzyme-treated industrial waste cellulose fibers when they are compressed to produce compressed fibers. The conversion of fines to glucose aids in dewatering, but it is a process that must be controlled because larger cellulose fibers can produce more fines. Therefore, to control this conversion process in industrial waste pulp, it is necessary to control the enzyme treatment time and enzyme concentration.

[0045] Preferably, the process further comprises: (a) providing or producing a raw fibrous cellulosic material, preferably one of virgin cellulosic fibers or waste cellulosic fibers, preferably pulped non-industrial waste cellulosic fibers derived from waste cardboard; (b) enzymatically treating the pulped non-industrial cellulosic fiber waste; (c) combining the enzyme-treated non-industrial waste cellulosic fibers with the enzyme-treated industrial waste cellulosic fibers; (d) compressing the enzyme-treated non-industrial waste cellulose fibers combined with the enzyme-treated industrial waste cellulose fibers; and (e) drying the compressed industrial and non-industrial waste cellulose fibers to form a rigid cellulose product.

[0046] Preferably, the step of producing pulped non-industrial waste cellulosic fibers comprises pulping a raw fibrous cellulosic material.

[0047] Alternatively, however, the raw fibrous non-industrial waste cellulosic waste may not require a separate pulping step prior to enzymatic treatment and may be supplied as already pulped fibers, i.e., fibers sufficiently individualized to be substantially free of agglomerates. Such a supply may be the direct output from a non-industrial plant, preferably the pulped output from a cardboard manufacturing plant.

[0048] The supplied pulped fibers can be supplied directly to the process for producing rigid cellulosic products from the pulped output from the corrugated board manufacturing plant via a conduit to the pulped output, or indirectly to the process for producing rigid cellulosic products via an intermediate storage tank.

[0049] Preferably, the step of enzymatically treating the pulped non-industrial waste cellulose fibers to produce enzyme-treated non-industrial waste cellulose fibers includes maintaining a moisture content of greater than 80% during the enzyme treatment.

[0050] Preferably, the step of enzymatically treating the pulped non-industrial waste cellulose fibers to produce enzyme-treated non-industrial waste cellulose fibers includes maintaining a moisture content of greater than 90% during the enzyme treatment.

[0051] Preferably, the step of maintaining the moisture content of the non-industrial waste cellulose fiber at greater than 80% during the enzyme treatment includes maintaining the moisture content during the enzyme treatment at greater than 80% to 99%, more preferably greater than 80% to 95%.

[0052] Preferably, the step of diluting the enzyme-treated non-industrial waste fiber to obtain diluted enzyme-treated non-industrial waste fiber having a moisture content of greater than 90% includes diluting to ensure that the moisture content remains greater than 90% and less than 99%, preferably greater than 95% and less than 99%.

[0053] Processes that maintain moisture content above 80% during enzymatic treatment of post-industrial and non-industrial fibers define the so-called wet process.

[0054] Alternatively, the process includes maintaining the moisture content of the post-industrial and non-industrial fibers between 20% and 80% during enzyme treatment, defining a semi-dry process.

[0055] Preferably, the raw fibrous post-industrial cellulosic material and the raw fibrous non-industrial waste cellulosic material are pulped independently of each other.

[0056] Preferably, the step of enzymatically treating the non-industrial waste cellulosic fibers comprises one or more of the following: -Maintaining the pH of the pulped fiber between 5 and 9; - maintaining the temperature during the enzymatic treatment of step (b) above 40°C, preferably above 40°C and below 70°C; - adding one or more enzymes selected from the group of xylanases, laccases and cellulases, - Adding 0.05% to 0.5% of enzymes based on the dry weight of industrial waste cellulose fiber; - Enzymatic treatment of industrial waste cellulose fibres for a period of more than 5 minutes, preferably more than 10 minutes and less than 90 minutes.

[0057] Preferably, the industrial waste cellulose fibers and the non-industrial waste cellulose fibers are enzyme treated independently of each other.

[0058] Preferably, the post-industrial cellulosic fibers and the non-industrial cellulosic fibers are washed to remove contaminants independently of each other.

[0059] Preferably, the step of providing post-industrial cellulose fiber includes providing at least two sources of post-industrial cellulose fiber, each source of post-industrial cellulose fiber being pulped independently of one another and enzyme-treated independently of one another.

[0060] Preferably, the post-industrial cellulose fibers and the non-industrial cellulose fibers are combined and mixed in a dilution step.

[0061] Preferably, the step of compressing the enzyme-treated industrial waste cellulose fibers and / or non-industrial waste cellulose fibers to form a rigid cellulose product is one of molding, preferably injection molding, or pressing in a molding unit and / or between drums to form a partially wet cellulose product.

[0062] Preferably, the step of compressing the enzyme-treated post-industrial cellulose waste fibers and / or non-industrial cellulose waste fibers to form a partially moist cellulose product comprises pressing the enzyme-treated post-industrial cellulose waste fibers and / or non-industrial cellulose waste fibers in a forming unit to obtain a partially moist cellulose-based product having a moisture content preferably greater than 40% and less than 80%, preferably greater than 40% and less than 70%.

[0063] Preferably, the step of pressing the enzyme-treated industrial waste cellulose fibers and / or non-industrial waste cellulose fibers in a forming unit comprises: (a) providing a forming unit having a mold defined by an outer wall having upper and lower open ends, and upper and lower plates configured to seal the open upper and lower ends, respectively, to hold the enzyme-treated industrial waste cellulose fibers and / or non-industrial waste cellulose fibers within the mold; (b) introducing enzyme-treated industrial waste cellulose fibers and / or non-industrial waste cellulose fibers into a mold; and (c) moving the upper plate relative to the lower plate, preferably using a mechanical screw, to compress the enzyme-treated and / or cellulose fibers between the upper and lower plates.

[0064] Preferably, a filter belt is provided between the lower plate and the mold, and the lower surface of the enzyme-treated industrial waste cellulose fibers and / or non-industrial waste cellulose fibers is in contact with the filter belt.

[0065] Preferably, the filter belt is porous enough to substantially retain the treated fiber solids with (or within) the mold and allow at least a portion of the moisture to pass through, preferably the filter having a porosity rating of 400 to 500 cubic feet per meter.

[0066] Preferably, a vacuum is applied to one or both of the upper and lower plates to remove water from the enzyme-treated industrial and / or non-industrial waste cellulosic fibers.

[0067] Preferably, the step of introducing the enzyme-treated post-industrial and / or non-industrial waste fibers into the mould comprises introducing the enzyme-treated post-industrial and / or cellulosic waste fibers through openings in the outer wall.

[0068] Preferably, the step of compressing the diluted enzyme-treated and pulped industrial and / or non-industrial cellulosic waste fibers to form a rigid cellulosic product preferably includes or further includes pressing between drums to obtain a partially moist cellulosic product having a moisture content of greater than 40% and less than 80%, preferably less than 70%.

[0069] Preferably, the step of drying the compressed fibers to form a rigid cellulosic product comprises introducing the partially moistened cellulosic product into a drying tunnel to reduce the moisture content, preferably at a temperature of less than 140°C, to preferably reduce the moisture content to less than 40%, more preferably less than 30%, and most preferably less than 25%.

[0070] Preferably, the step of drying the compressed fibers to form a rigid cellulosic product further comprises introducing the compressed and partially dried fibers into a hot plates press to reduce the moisture content, preferably to less than 20%.

[0071] Preferably, the hot plate press comprises an upper plate and a lower plate, both plates configured to allow steam generated from water present in the partially moistened cellulose product to escape from the partially moistened cellulose product, and preferably both plates comprise a mesh-like structure or are porous.

[0072] Preferably, the temperature of the upper and lower plates of the hot plate (or hot plate pressure) is maintained above 60°C and up to 200°C.

[0073] Preferably, pressure is applied to the partially wet cellulosic product in a first and second stage.

[0074] Preferably, in the first stage, 2 kg / cm 2 A pressure of less than 1000 psi is applied.

[0075] Preferably, in the second stage, the density is 0.5 kg / cm to obtain a rigid cellulose product having the required density or thickness, preferably having a moisture content of less than 20%. 2 A pressure exceeding

[0076] Preferably, the process is a continuous process.

[0077] Preferably, the raw fibrous industrial waste material contains other compounds such as inorganic compounds and / or other impurities.

[0078] Preferably the rigid cellulosic product is a board, preferably a building board.

[0079] Preferably, the board has one or more of the following characteristics: - at least 20% by weight of post-industrial fibers compared to the weight of the final rigid cellulose product; -3mm~22mm thickness, - internal bond strength of at least 0.1 MPa, a flexural strength of at least 4 MPa, and -At least 400kg / m 3 density.

[0080] Preferably, the process further comprises adding a flame retardant, preferably aluminum hydroxide or an expansive volcanic mineral, preferably vermiculite, to the non-industrial waste cellulosic fibre, preferably waste cardboard.

[0081] Preferably, the step of adding the flame retardant occurs after the step of enzymatically treating the pulped non-industrial waste cellulose fibers, and more preferably before the step of combining the enzyme-treated, pulped industrial waste cellulose fibers with the non-industrial waste cellulose fibers.

[0082] Preferably, aluminum hydroxide is added to the non-industrial waste cellulose fibers in an amount sufficient to provide the rigid cellulose product with an aluminum hydroxide content of greater than 15 wt% by dry mass compared to the weight of the rigid cellulose product, to provide the rigid cellulose product with a fire classification of Class B when tested in accordance with European Standard EN 13501-1.

[0083] Preferably, the expansive volcanic mineral is added to the non-industrial waste cellulose fibers in an amount sufficient to have an expansive volcanic mineral content of greater than 5 wt% dry mass compared to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested in accordance with European Standard EN 13501-1.

[0084] Preferably, the step of compressing the enzyme-treated industrial waste and / or non-industrial waste cellulose fibers comprises depositing a plurality of distinct layers of the enzyme-treated industrial waste and / or non-industrial waste cellulose fibers in a forming unit and pressing the plurality of distinct layers to produce a multi-layered partially wet cellulose product, wherein the distinct layers may comprise industrial or non-industrial waste cellulose fibers and have different or the same flame retardant in each of the distinct layers.

[0085] Preferably, depositing a plurality of different layers of enzyme-treated industrial and / or non-industrial waste cellulose fibers in the forming unit includes depositing an upper outer layer comprising a flame retardant, preferably one of aluminum hydroxide or an expansive volcanic mineral, and / or a lower outer layer comprising a flame retardant, preferably one of aluminum hydroxide or an expansive volcanic mineral.

[0086] Preferably, depositing a plurality of distinct layers of enzyme-treated industrial waste and / or non-industrial waste cellulose fibers in the forming unit includes depositing an intermediate layer of enzyme-treated industrial waste and / or non-industrial waste cellulose fibers that does not contain a flame retardant between the upper outer layers.

[0087] Preferably, the non-industrial waste cellulose fibers are one or more of any cellulose fibers not derived from raw fibrous industrial waste, more preferably virgin cellulose fibers, preferably wood or plant fibers, more preferably miscanthus fibers, or preferably waste paper or waste cardboard fibers, preferably OCC fibers.

[0088] Preferably, the non-industrial waste cellulose fibers are any cellulose fibers not derived from raw fibrous industrial waste, more preferably virgin cellulose fibers, preferably wood or plant fibers, more preferably miscanthus fibers, or preferably waste paper or waste cardboard fibers, preferably OCC fibers.

[0089] Preferably, the cellulose fibers are 100% waste cardboard fibers, and in this case, the process further comprises adding a flame retardant, preferably aluminum hydroxide, to the waste cardboard fibers, preferably adding the flame retardant after step (b) of enzymatically treating the waste cardboard fibers.

[0090] Preferably, the process does not include the step of adding a binder, glue or adhesive to bind the fibers together.

[0091] Preferably, the rigid cellulose product comprises a proportion of rejected rigid cellulose product.

[0092] Preferably, the process further comprises adding the rejected rigid cellulosic product to a step of diluting or pulping or enzymatically treating industrial or non-industrial waste cellulosic fiber.

[0093] Preferably, the combined industrial waste cellulose fibers and non-industrial waste cellulose fibers comprise at least 20 wt %, preferably 20-80 wt %, preferably 30-70 wt %, preferably 40-60 wt % industrial waste cellulose fibers, and the remainder of the combined industrial waste cellulose fibers and non-industrial waste cellulose fibers is cellulose fiber.

[0094] According to another aspect of the present invention, there is provided a rigid cellulosic product comprising one or both of enzyme-treated post-industrial cellulosic fibers and enzyme-treated non-industrial waste cellulosic fibers.

[0095] Preferably, the rigid cellulosic product does not contain binders, adhesives or tackifiers to bind the fibers together.

[0096] Preferably, the rigid cellulose product has a calcium carbonate content of more than 7 wt%, preferably less than 50%, more preferably less than 35 wt%, relative to the weight of the rigid cellulose product.

[0097] Preferably, the rigid cellulosic product comprises a flame retardant.

[0098] Preferably, the flame retardant is aluminum hydroxide and the product has an aluminum hydroxide content of greater than 15 wt% dry mass compared to the weight of the rigid cellulosic product.

[0099] Preferably, the flame retardant is an intumescent volcanic mineral and the product has an intumescent volcanic mineral content of more than 5 wt% dry mass compared to the weight of the rigid cellulosic product.

[0100] Preferably, the rigid cellulosic product comprises a plurality of compressed overlapping or structural layers, at least one of the layers comprising a flame retardant.

[0101] Preferably, at least one of the plurality of compressed overlapping layers is flame retardant-free.

[0102] Preferably, the plurality of compressed overlapping layers includes an upper outer layer and a lower outer layer, and the upper and / or lower outer layer includes a flame retardant.

[0103] Preferably, the intermediate layer between the upper and lower outer layers does not contain a flame retardant.

[0104] Preferably, the post-industrial cellulosic fibers are derived from primary sludge obtained from the paper industry.

[0105] Preferably, the non-industrial waste cellulosic fibers are derived from waste cardboard.

[0106] Preferably, the rigid cellulose product comprises 20-80 wt%, preferably 30-70 wt%, preferably 40-60 wt% post-industrial cellulose fibers, with the remainder of the combined post-industrial and non-industrial cellulose fibers being non-industrial cellulose fibers.

[0107] Preferably, the expansive volcanic mineral is collected in one of the upper or lower outer regions of the rigid cellulose board, and the aluminum hydroxide is collected in the other of the upper or lower outer regions of the rigid cellulose board.

[0108] Preferably, the expansive volcanic mineral is collected in one of the upper or lower outer regions of the rigid cellulose board, and the aluminum hydroxide is collected in the other of the upper or lower outer regions of the rigid cellulose board.

[0109] Preferably, the rigid cellulose product has one or more of the following properties: - at least 20% by weight of post-industrial fibers compared to the weight of the final rigid cellulose product; -3mm~22mm thickness, - internal bond strength of at least 0.1 MPa, a flexural strength of at least 4 MPa, and -At least 400kg / m 3 density.

[0110] According to another aspect of the present invention, there is provided a process for producing rigid cellulose products from raw fibrous industrial waste, comprising the steps of: (a) providing or producing raw fibrous industrial waste, preferably pulped post-industrial cellulose fibers derived from sludge from the waste paper industry; (b) enzymatically treating the pulped post-industrial cellulosic fibers to produce enzyme-treated post-industrial cellulosic fibers; (c) providing or producing a raw fibrous non-industrial waste cellulosic material, preferably one of virgin cellulosic fiber or waste cellulosic fiber, preferably pulped non-industrial waste cellulosic fiber derived from waste cardboard; (d) enzymatically treating the pulped non-industrial cellulosic fiber waste; (e) maintaining the moisture content of industrial waste fibers and non-industrial waste fibers during enzyme treatment above 80% to define a wet process; (f) combining the enzyme-treated non-industrial waste cellulosic fiber with enzyme-treated non-industrial waste cellulosic fiber; (g) compressing the enzyme-treated non-industrial waste cellulose fibers combined with the enzyme-treated industrial waste cellulose fibers; and (h) drying the compressed industrial and non-industrial waste cellulose fibers to form a rigid cellulose product; Here, the rigid cellulose product has a fire classification of at least class C when tested in accordance with European Standard EN 13501-1.

[0111] According to another aspect of the present invention, there is provided a process for producing rigid cellulose products from raw fibrous industrial waste, comprising the steps of: (a) providing or producing raw fibrous industrial waste, preferably pulped post-industrial cellulose fibers derived from sludge from the waste paper industry; (b) enzymatically treating the pulped post-industrial cellulosic fibers to produce enzyme-treated post-industrial cellulosic fibers; (c) providing or producing a raw fibrous non-industrial waste cellulosic material, preferably one of virgin cellulosic fiber or waste cellulosic fiber, preferably pulped non-industrial waste cellulosic fiber derived from waste cardboard; (d) enzymatically treating the pulped non-industrial cellulosic fiber waste; (e) maintaining the moisture content of the industrial waste fiber and non-industrial waste fiber during the enzyme treatment at 20% to 80% to define a semi-dry process; (f) combining the enzyme-treated non-industrial waste cellulosic fiber with enzyme-treated non-industrial waste cellulosic fiber; (g) compressing the enzyme-treated non-industrial waste cellulose fibers combined with the enzyme-treated industrial waste cellulose fibers; and (h) drying the compressed industrial waste cellulose fibers and non-industrial waste cellulose fibers to form a rigid cellulose product; Here, the rigid cellulose product has a fire classification of at least class C when tested in accordance with European Standard EN 13501-1.

[0112] Preferably, the process further comprises the step of selecting the amount of post-industrial cellulose fibres such that the calcium carbonate content of the post-industrial cellulose fibres compared to the weight of the rigid cellulose product is sufficient to obtain a rigid cellulose product having a fire classification of at least Class C when tested according to European Standard EN 13501-1.

[0113] Preferably, the calcium carbonate content is greater than 7 wt.%, preferably greater than 7 wt.% and less than 50 wt.%, more preferably greater than 7 wt.% and less than 35 wt.%, relative to the weight of the rigid cellulose product.

[0114] Preferably, the process further comprises the step of adding a fire retardant, preferably an intumescent volcanic mineral, preferably vermiculite, to the post-industrial cellulose fibers.

[0115] Preferably, the expansive volcanic mineral is added in an amount sufficient so that the rigid cellulose product has an expansive volcanic mineral content of more than 5 wt% dry mass compared to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested in accordance with European Standard EN 13501-1.

[0116] Preferably, the post-industrial cellulose fibers do not contain calcium carbonate, preferably the post-industrial cellulose fibers are textile sludge residues from the textile manufacturing industry or construction waste cellulose fibers, and the process further comprises the step of adding a flame retardant, preferably aluminum hydroxide, to the post-industrial cellulose fibers.

[0117] Preferably, aluminum hydroxide is added to the waste industrial cellulose fibers in an amount sufficient to provide the rigid cellulose product with an aluminum hydroxide content of more than 15 wt% by dry mass compared to the weight of the rigid cellulose product, to provide the rigid cellulose product with a fire classification of Class B when tested in accordance with European Standard EN 13501-1.

[0118] Preferably, the process further comprises the step of adding a flame retardant, preferably aluminum hydroxide or an expansive volcanic mineral, preferably vermiculite, to the non-industrial waste cellulose fibre, preferably waste cardboard.

[0119] Preferably, the step of adding the flame retardant occurs after the step of enzyme treating the pulped non-industrial waste cellulose fiber and before the step of combining the enzyme-treated pulped industrial waste cellulose fiber and the non-industrial waste cellulose fiber.

[0120] Preferably, the expansive volcanic mineral is added to the non-industrial waste cellulose fibers in a sufficient amount so that the rigid cellulose product has an expansive volcanic mineral content of more than 5 wt% dry mass compared to the weight of the rigid cellulose product to provide a rigid cellulose product having a fire classification of Class B when tested in accordance with European Standard EN 13501-1.

[0121] Preferably, aluminum hydroxide is added to the non-industrial waste cellulose fibers in an amount sufficient to provide the rigid cellulose product with an aluminum hydroxide content of greater than 15 wt% dry mass compared to the weight of the rigid cellulose product to provide a rigid cellulose product with a fire classification of Class B when tested in accordance with European Standard EN 13501-1. [Brief explanation of the drawings]

[0122] The present invention will now be described with reference to the following Figures 1 to 20, Tables 1 to 4, and Examples 1 to 24: [Figure 1] FIG. 1 is a schematic diagram of the process of the present invention. [Figure 2] FIG. 2 is a cross-sectional front view of a forming unit used in the process of the present invention prior to injection of pulp. [Figure 3] 3 is a side cross-sectional view of the forming unit of FIG. 2 prior to injection of pulp. [Figure 4] 4 is a cross-sectional front view of the forming unit of FIG. 1 after injection of pulp; [Figure 5] FIG. 5 is a cross-sectional plan view of the forming unit of FIG. 1 after pulp injection (with the top plate removed for clarity). [Figure 6-18] 6-18 are schematic cross-sectional views of alternative rigid cellulose boards. [Figure 19] FIG. 19 is a schematic diagram of an embodiment of an enzyme treatment system adapted to apply the proposed method to obtain different fractions of dry treated cellulosic material. [Figure 20] FIG. 20 is a schematic diagram of the system of FIG. 19, but also including a product forming station for producing a layered rigid cellulosic product. DETAILED DESCRIPTION OF THE INVENTION

[0123] References to moisture content are percentages by weight and further refer to the percentage of water compared to the amount of solids, for example, 80% moisture content includes 20% solids.

[0124] References to percentage ratios of industrial and non-industrial materials mean the dry weight of that material compared to the total dry weight of the industrial and non-industrial materials.

[0125] Example 1 Referring to Figure 1 and Table 1, raw fibrous non-industrial waste cellulosic material A is provided in the form of waste cardboard, specifically old corrugated cardboard (OCC), and raw fibrous industrial waste cellulosic material B is provided in the form of raw papermaking sludge, i.e., primary sludge from the papermaking industry.

[0126] In this example, the raw fiber content is 50% sludge and 50% OCC (both measured by dry weight), it will be understood that the sludge content can be up to 100% with the remainder being OCC, for example, 70% sludge and 30% OCC.

[0127] The sludge and OCC are diluted, pulped, and enzymatically treated independently as described below.

[0128] <OCC treatment> First, warm water at 60 °C is pumped into the pulper P1.

[0129] Next, the OCC is loaded into the pulper P1 and stirred in water for at least 8 minutes to individualize and improve the fiber distribution in the OCC before adding the enzyme, generating pulped OCC. If necessary, water is added to the OCC in the pulper P1 to ensure a moisture content of 95%. In another embodiment, OCC having a moisture content exceeding 95% can be supplied, in which case water is removed or more solids are added to establish a moisture content of 95% in this embodiment. Individualization means a process of dispersing the fibers aggregated in the raw material OCC.

[0130] Next, enzymes in the form of xylanase, laccase, and cellulase are added to the diluted and pulped OCC fibers in the pulper P1 and stirred or agitated for at least 5 minutes and up to 90 minutes (depending on the pulping device) to produce pulped and enzymatically treated OCC having a moisture content maintained above 90% and about 95% in this embodiment.

[0131] The enzyme is preferably liquid or dissolved in liquid and added to the pulped OCC waste fibers. The enzyme added is preferably selected to smooth the fibers, remove radicals from the outside of the fibers, and increase the specific surface area of the fibers. These effects can be obtained, for example, by different combinations of the following enzymes: Xylanase, laccase, cellulase, and / or combinations thereof.

[0132] During the enzymatic treatment, the pH of the pulped fibers is maintained at 5 - 9.

[0133] The temperature of the pulped fiber is maintained above 40°C, preferably between 40°C and 70°C, to improve enzyme treatment. In this example, the temperature of the pulped fiber is maintained at 60°C.

[0134] The total amount of enzyme added is 0.05% to 1% of the dry weight of OCC fiber.

[0135] Alkyl ketene dimer (AKD) is added to the pulped and enzyme-treated OCC fiber as part of the water treatment additive in T2B. The amount of AKD added is less than 15% by weight of the OCC. After adding the AKD, the agitator continues to run for about 4 minutes.

[0136] Optionally, the diluted, pulped, enzyme-treated OCC content of pulper P1 is then subjected to a washing process by being transferred via sieving tank P2 to tank T1, where contaminants such as plastic, wood, or metal having a size larger than 6 mm are removed in a first washing stage, and further contaminants smaller than 6 mm (and therefore not removed in the first washing stage) but heavier than the aforementioned contaminants are removed in a second washing stage using a hydrocyclone. Examples of such smaller but heavier contaminants include staples, crystals, and sand.

[0137] The OCC pulp produced independently in tank T1 is then transferred to tank T2B, and the stirrer is started. The OCC pulp is diluted to a moisture content of 97%.

[0138] <Sludge treatment> The above dilution, pulping, and enzyme treatment steps are repeated with the sludge in pulper P1 (after the pulped, diluted, and enzyme-treated OCC is removed), except that the enzyme treatment stage requires more than 5 minutes but less than 60 minutes, and the enzyme concentration is 0.05% to 0.5% based on the dry weight of the sludge fibers. The enzyme treatment time and concentration are approximately 50% less for the sludge fibers compared to the OCC fibers.

[0139] In an alternative embodiment, the sludge can be pulped in a different pulper that is not the same as the pulper used for dilution, pulping, and enzyme treatment of the OCC.

[0140] Optionally, the pulped and enzyme-treated sludge contents of pulper P1 are washed according to the same process as described above for OCC.

[0141] The sludge pulp produced independently in tank T1 (either before or after the OCC pulp is produced) is then transferred to tank T2A, the stirrer is started, and the sludge pulp is diluted to a moisture content of 97%.

[0142] It will be appreciated that the OCC and sludge are independently pulped and enzymatically treated in steps (a) and (b) above, i.e., the OCC is pulped and enzymatically treated and transferred to tank T1, and then the sludge is independently pulped and enzymatically treated and transferred to tank T1. Furthermore, the sludge and OCC are independently subjected to a two-stage washing process by being sieved in screening tank P2 and washed in tank T1.

[0143] An aluminum hydroxide flame retardant (also called a fire retardant) in the form of aluminum hydroxide is added to the OCC pulp in tank T2B, which is then circulated within tank T2B.

[0144] 50% of the sludge pulp in Tank T2A and 50% of the flame retardant added OCC pulp in Tank T2B are then transferred to Tank T3 where they are combined and agitated.

[0145] Further additives such as odor powder, biocides, and inks / dyes are added to the combined sludge and OCC pulp in tank T3.

[0146] If necessary, the combined sludge and OCC pulp is further diluted by adding more water to ensure a moisture content greater than 90%.

[0147] <Formation> Referring to the forming unit 10 of Figures 2-5, the combined sludge and OCC pulp 11 is compressed as follows:

[0148] Forming unit 10 includes a rectangular mold 12 defined by an outer wall 14 having an open upper end 16 and an open lower end 18. Outer wall 14 includes a plurality of openings 20 distributed along each long side of outer wall 14, through which the combined sludge and OCC pulp 11 is injected, as described below. The distribution and number of openings can be varied to ensure even distribution of pulp 11 within mold 12. This is important because it allows for control of the density and thickness of the final rigid cellulosic product.

[0149] The forming unit 10 further includes an upper plate 22 and a lower plate 24, the upper plate 22 being movable relative to the lower plate 24 via a mechanical screw system 26 driven by an electric motor (not shown).

[0150] The upper plate 22 and the lower plate 24 have a compartmentalized structure that functions as a box in which the water extracted from the pulp 11 can be temporarily stored.

[0151] A PET transport filter belt 28 is disposed between the lower plate 24 and the mold 12 and sealingly engages the outer wall 14 of the mold 12 to retain the pulp 11 within the mold 12. The filter belt 28 has sufficient porosity to substantially retain the solids content of the processed fibers along with the mold and to allow at least a portion of the moisture content to pass through, in this embodiment having a porosity of 400-500 cubic feet per meter, sufficient to allow extraction of water from the pulp 11 while simultaneously avoiding the undesirable extraction of cellulosic fibers from the pulp 11.

[0152] In operation, the combined sludge and OCC pulp 11 is poured into the mold 12 of the forming unit 10 through the opening 20. The pulp 11 is held horizontally by the outer wall 14 and vertically by the filter belt 28 (FIGS. 2 and 3).

[0153] Once the desired amount of pulp 11 has been introduced into the mold 12, the dewatering process begins by applying a vacuum to the lower plate 24 to extract water from the pulp 11 through the filter belt 28. The extracted water is deposited inside the lower plate 24. Alternatively, the water can be extracted by gravity without applying a vacuum.

[0154] At the same time that water is extracted from the pulp 11, the upper plate 22 is lowered via a mechanical screw system into contact with the pulp 11 and applies pressure according to the required product density (Figure 4). As the upper plate 22 presses the pulp 11 against the lower plate 24, a vacuum is applied to the upper plate 22, extracting more water from the pulp 11 through the upper plate 22, where it is deposited. Alternatively, instead of applying a vacuum, a positive pressure can be applied to the interior of the mold.

[0155] Once a sufficient amount of water has been removed from the pulp 11, a partially wet cellulose product in the form of a board is formed, typically having a moisture content greater than 40% and less than 80%, and the partially wet cellulose board can be removed from the forming unit 10.

[0156] The partially wet cellulose board is removed from the forming unit 10 by first raising the top plate 22 to its starting position (FIG. 2), lifting the mold 12 off the filter belt 28, and then starting the transport filter belt 28 to move the partially wet cellulose board to a transfer unit (not shown), where it undergoes an optional compression step in the form of press rollers or drums to squeeze any remaining water out of the wet, partially wet cellulose board and further reduce the moisture content, typically from less than 70% to about 40%.

[0157] In an alternative embodiment, the combined pulp 11 can be compressed between press rollers to form a partially wet cellulose board without requiring forming in the forming unit 10 .

[0158] <Drying> The partially wet cellulose board is dried in two stages as follows:

[0159] In the first drying stage, the board is introduced into a convection drying tunnel, where it moves on a belt at a speed of 0.04-0.05 m / min and remains at a temperature of 120°C for 4-5 hours.

[0160] When the boards leave the drying tunnel, they have a moisture content of 20-30%.

[0161] In the second drying stage, the board is removed from the drying tunnel and placed between two plates of a hot plate press.

[0162] The hot plate press includes an upper hot press plate and a lower hot press plate, both of which are configured to allow steam generated from water present in the partially moistened cellulose board to escape when the board is heated. In this example, both the upper and lower plates have a mesh-like structure that allows steam to escape. Alternatively, the plates can be made of a porous material or can include micro-perforations.

[0163] The top and bottom plates of the hot plate press are maintained at a temperature of greater than 60°C and up to 200°C during pressing.

[0164] In the first press drying stage, 2 kg / cm 2 During this first stage, the board is placed in contact with the press hotplate and heated by conduction. The pressure applied during this first stage depends on the required final board density, but can be as low as 2 kg / cm. 2 In this first stage, the board achieves a moisture content of less than 50%.

[0165] In the second press drying stage, the pressure is adjusted to 0.5 kg / cm to obtain a rigid cellulose product with the required density or thickness. 2 In the second press drying stage, the board is less compressible due to its lower moisture content, so the maximum pressure that can be applied to the board is not as limited as in the first press drying stage.

[0166] After the second stage, the rigid cellulose board has a moisture content of about 20%.

[0167] In this embodiment, the partially wet cellulose board is transferred from the forming unit via press rollers and a drying tunnel to the hot plate press. In an alternative embodiment, the partially wet cellulose board can be transferred directly from the forming unit to the hot plate press without the need for a drying tunnel.

[0168] After exiting the hot plate press, the board is allowed to cool on the mesh-covered support for at least 30 minutes to allow residual water vapor to evaporate from both sides of the board.

[0169] In the above example, the partially wet cellulose board undergoes a first drying stage in a drying tunnel. In an alternative example, a single stage drying process is possible, requiring only the use of a drying tunnel or hot plate press.

[0170] Alternative drying techniques such as radio or microwave frequency drying, infrared drying, or direct conduction drying are envisioned.

[0171] It is noted that the boards produced have the properties defined in Table 1 and in particular achieve a Class B fire classification (SBI) when the boards are tested according to European Standard EN 13501-1.

[0172] In an alternative example, no aluminum hydroxide flame retardant is added to the pulped, enzyme-treated OCC. Instead, the amount of calcium carbonate in the sludge is high enough, in this example about 10% by weight of the final board, to achieve a Class C fire classification (SBI) when tested according to European Standard EN 13501-1, as opposed to the Class B fire classification (SBI) of Example 1.

[0173] To ensure the calcium carbonate content is sufficient to achieve Class C, the calcium carbonate content of the raw sludge is measured for each batch before the fibers are compressed, and the measured calcium carbonate content is compared to a lookup standard that correlates the calcium carbonate content of the sludge with the expected calcium carbonate content of the rigid cellulose product based on the percentage of sludge in the final product. If the calcium carbonate content is too low, it is adjusted to ensure that it is sufficient to achieve Class C fire classification (SBI), i.e., greater than 7 wt% and less than 50 wt% compared to the weight of the final board. Adjusting the calcium carbonate level is accomplished by adjusting the ratio of OCC to sludge.

[0174] Calcium carbonate content is measured by calcining a known weight of sludge sample, then comparing the weight of ash (from the calcination) to the total dry weight of the sludge sample to obtain the ash percentage. Typically, the ash percentage is an accurate indication (to within 95%) of the calcium carbonate content.

[0175] Other than the fire classification, the final board properties of the Class C evaluation board are 5 to 10% higher than the final board properties of the Class B evaluation board of Example 1.

[0176] In this alternative example, in contrast to Example 1, the pulped and enzyme-treated sludge and the pulped and enzyme-treated OCC are not separately sieved in sieving tank P2 and washed in tank T1, but are combined and then subjected to a two-stage washing process.

[0177] <Example 2> Other than the differences shown in Table 1, the process of Example 2 is identical to Example 1, except that the mixture content is 60% waste paper sludge and 40% OCC.

[0178] The boards produced have the properties defined in Table 1.

[0179] Example 3 Other than the differences shown in Table 1, the process of Example 3 is identical to Example 1, except that the content of the mixture includes 50% OCC plus 50% industrial waste in the form of miscanthus fiber.

[0180] The boards produced have the properties defined in Table 1.

[0181] Example 4 Other than the differences shown in Table 1, the process of Example 4 is identical to Example 3, except that the content of the mixture includes 100% non-industrial waste in the form of plant fiber, in this example Miscanthus fiber.

[0182] The boards produced have the properties defined in Table 1.

[0183] <Example 5> Other than the differences shown in Table 1, the process of Example 5 is identical to Example 3, except that the content of the mixture includes 100% non-industrial waste in the form of OCC.

[0184] The boards produced have the properties defined in Table 1.

[0185] Example 6 Other than the differences shown in Table 1, the process of Example 6 is identical to Examples 1 and 3, except that the content of the mixture includes 50% OCC plus 50% textile sludge, i.e., industrial waste in the form of sludge derived from the textile processing industry.

[0186] The boards produced have the properties defined in Table 1.

[0187] Example 7 Other than the differences shown in Table 1, the process of Example 7 is identical to Example 6, except that the content of the mixture contains 100% industrial waste in the form of textile sludge, i.e., the mixture does not contain non-industrial waste such as OCC.

[0188] Instead of adding aluminum hydroxide to the OCC (which does not exist), an alternative fire retardant, vermiculite, is added to the sludge to achieve a Class B fire classification (SBI) when tested according to European standard EN 13501-1. The boards produced have the properties defined in Table 1.

[0189] Alternatively, aluminum hydroxide can be added to the textile sludge instead of vermiculite.

[0190] Example 8 Other than the differences shown in Table 1, the process of Example 8 is identical to Example 6, except that the textile sludge contains a mixture of organic and synthetic fibers that have shorter fibers and do not form hydrogen bonds.

[0191] The boards produced have the properties defined in Table 1.

[0192] Example 9 Other than the differences shown in Table 1, the process of Example 9 is identical to Example 7, except that the textile sludge contains a mixture of organic and synthetic fibers that have shorter fibers and do not form hydrogen bonds.

[0193] The boards produced have the properties defined in Table 1.

[0194] Example 10 Other than the differences shown in Table 1, the process of Example 10 is identical to Examples 1, 3, and 6, except that the mixture content includes 50% OCC plus 50% industrial waste in the form of construction waste (calcium sulfate) as opposed to paper sludge.

[0195] The boards produced have the properties defined in Table 1.

[0196] Example 11 Other than the differences shown in Table 1, the process of Example 11 is identical to Example 10, except that the content of the mixture includes 100% industrial waste in the form of construction waste (calcium sulfate).

[0197] Instead of adding aluminum hydroxide to OCC (which does not exist), an alternative fire retardant, vermiculite, is added to construction waste to achieve a Class B fire classification (SBI) when tested according to European standard EN 13501-1.

[0198] The boards produced have the properties defined in Table 1.

[0199] Alternatively, aluminum hydroxide can be added to the textile sludge instead of vermiculite.

[0200] In Examples 4, 5, 7, 9, and 11 above, there is only a single cellulosic fiber source (industrial or non-industrial waste), and therefore there is no need to wash that single fiber source independently or combine it with another cellulosic fiber source, as is the case in Examples 1, 2, 3, 6, 8, and 10 (industrial and non-industrial waste).

[0201] In the above Examples 1-11, a flame retardant in the form of aluminum hydroxide is added to the OCC to achieve a Class B rating. In an alternative example, instead of or in addition to adding aluminum hydroxide to the OCC, an expansive volcanic mineral such as vermiculite or perlite can be added to the OCC to achieve a Class B rating for each of the above Examples 1-11.

[0202] In the above examples and alternatives, a flame retardant in the form of aluminum hydroxide or expansive volcanic minerals is added to OCC (non-industrial waste cellulosic material) to achieve a Class B rating. In alternative examples, expansive volcanic minerals may be added to industrial waste cellulosic material instead of or in addition to the non-industrial waste cellulosic material to achieve a Class B rating.

[0203] In the above examples, aluminum hydroxide is added to the OCC. In examples where the post-industrial cellulosic material is not paper sludge, i.e., does not contain calcium carbonate, e.g., textile or construction waste, aluminum hydroxide can be added to the post-industrial cellulosic material instead of, or in addition to, adding aluminum hydroxide to the OCC.

[0204] In the above examples and alternatives, vermiculite and / or aluminum hydroxide are added as fire retardants. In alternatives, the amount of calcium carbonate in the paper sludge is high enough to achieve a Class C rating (as described in connection with the alternative in Example 1). Other than fire classification, the final board properties of the Class C boards of the alternatives in Examples 2-11 are 5-10% higher than the final board properties of the Class B boards in Examples 2-11.

[0205] In these alternative examples where no flame retardant is added, in contrast to Examples 2 to 11, the pulped and enzyme-treated industrial waste, i.e., sludge (from textile or paper processing), miscanthus, or construction waste, and the pulped and enzyme-treated non-industrial waste, i.e., OCC, are not separately sieved in sieving tank P2 and washed in tank T1, but are combined and then subjected to a two-stage washing process: sieving in sieving tank P2 and washing in tank T1.

[0206] Example 12 Other than the differences shown in Table 2, the process of Example 12 is identical to the alternative of Example 1 without the addition of flame retardant, resulting in a Class C rating as a result of the calcium carbonate content in the sludge being greater than 7 wt%, 10 wt% in this example.

[0207] The boards produced have the properties defined in Table 2.

[0208] Example 13 Other than the differences noted in Table 2, the process of Example 13 is identical to Example 12, except that the board contains 100% papermaking sludge. A Class C rating results from a calcium carbonate content in the sludge greater than 7 wt%, which in this example is 10 wt%.

[0209] Example 14 Other than the differences shown in Table 3, the process of Example 14 is identical to Example 1, except that the board has both vermiculite and aluminum hydroxide added as a fire retardant, as opposed to only aluminum hydroxide.

[0210] The boards produced had the properties defined in Table 3 and the structure shown in FIG.

[0211] The board of Example 14 is made by the process described in connection with Example 1, except that vermiculite is added to the sludge and aluminum hydroxide is added to the OCC. The sludge and OCC are processed independently in pulper P1 before the vermiculite-containing sludge and aluminum hydroxide-containing OCC are then combined in tank T3.

[0212] After formation and drying, an upper outer region 112 of the board comprises vermiculite and a lower outer region 114 of the board comprises aluminum hydroxide, since vermiculite has a lower density than aluminum hydroxide, giving both the upper and lower outer regions a Class B fire retardant classification (FIG. 6).

[0213] Example 15 Example 15 is identical to Example 14, except that only OCC fibers are used.

[0214] The manufactured board has the structure shown in FIG.

[0215] It will be appreciated that both the upper outer region 212 and the lower outer region 214 of the board contain aluminum hydroxide, imparting a Class B flame retardant classification to both the upper and lower outer regions.

[0216] Example 16 The board of Example 16 was manufactured by the process described below and is shown in FIG.

[0217] The process for making the board of Example 16 is identical to the process described above in Example 15, except that different boards are treated and formed with different compositions and then bonded together to form a layered structure comprising an intermediate layer 316 of enzyme-treated OCC fiber between upper and lower outer layers 312 and 314 of OCC fiber containing aluminum hydroxide.

[0218] The upper and lower outer layers 312, 314 of the board contain aluminum hydroxide, giving both the upper and lower outer layers a Class B flame retardant classification. It will be understood that the dotted lines in Figures 6 and 7 represent areas where the flame retardant has migrated, while in Figure 8 the solid (or hard) lines represent the structural layer that results from forming rigid boards having different compositions and then gluing these rigid boards together to create the structural layer.

[0219] In an alternative to Example 16, the intermediate layer between the upper and lower outer layers can comprise industrial waste, such as sludge, or a combination of non-industrial waste in the form of OCC and industrial waste (not shown).

[0220] In a further alternative to Example 16, the upper and lower outer layers can comprise industrial waste, such as sludge, with added vermiculite, and the middle layer comprises industrial and / or non-industrial waste (FIG. 9).

[0221] In a further alternative to Example 16, the upper and lower outer layers can comprise non-industrial waste, such as OCC, with added aluminum hydroxide, and the middle layer comprises industrial and / or non-industrial waste (FIG. 10).

[0222] Example 17 In Figure 11, Example 17 is identical to Example 14 (Figure 6), except that the industrial waste cellulose fibers are derived from primary sludge obtained from the textile manufacturing industry, which does not contain calcium carbonate, and therefore aluminum hydroxide can be added to the sludge as a substitute for vermiculite. This is in contrast to cellulose fibers derived from primary sludge obtained from the paper industry, where aluminum hydroxide cannot be added to calcium carbonate-containing sludge. It will be understood that the region between the upper and lower regions can contain any combination of OCC and textile sludge, OCC alone, or sludge alone.

[0223] Example 18 In Figure 12, Example 18 is identical to Example 16 (Figure 9), except that the industrial waste cellulose fibers are derived from primary sludge obtained from the textile manufacturing industry, which does not contain calcium carbonate, and therefore aluminum hydroxide can be added to the sludge as a substitute for vermiculite. This is in contrast to cellulose fibers derived from primary sludge obtained from the paper industry, where aluminum hydroxide cannot be added to calcium carbonate-containing sludge. It will be understood that the layers between the top and bottom layers can contain any combination of OCC and textile sludge, or only OCC.

[0224] <Examples 19 to 24> Examples 1-18 above, and alternatives thereof, describe processes in which the moisture content is maintained above 80% during the enzymatic treatment of industrial waste and non-industrial waste cellulose fibers. In alternative Examples 19-24, provided in Table 4, the process is as described in connection with Examples 1-18 above, except as set forth in Table 4, and in particular, the process is a semi-dry process in which a moisture content of 20% to 80% by weight (and thus less than 80% by weight) based on the total amount of cellulose fiber is maintained during the enzymatic treatment of industrial waste and non-industrial waste cellulose fibers.

[0225] The boards produced have the properties defined in Table 4, and in particular have a Class C fire rating as a result of the calcium carbonate content in the sludge exceeding 7 wt%.

[0226] In Examples 19-24, the industrial cellulose fibers are derived from paper sludge. In alternative examples, the industrial cellulose fibers may be derived from textiles or construction waste, as described in connection with Examples 1-18.

[0227] Similarly, to obtain a Class B fire rating, aluminum hydroxide and / or vermiculite are added to cellulose fibers in a semi-dry enzyme treatment process similar to that described in connection with the wet enzyme treatment process of Examples 1-18.

[0228] FIG. 13 corresponds to the rigid board of FIG. 6 except that the aluminum hydroxide and vermiculite are distributed evenly throughout the board due to the lower moisture content below 80% compared to boards produced by processes where the moisture content remains above 80% during enzymatic treatment of industrial and non-industrial waste cellulose fibers, with more of the aluminum hydroxide migrating to the lower outer region and the vermiculite migrating to the upper outer region.

[0229] FIG. 14 corresponds to the rigid board of FIG. 7 except that the aluminum hydroxide is more evenly distributed throughout the board due to the lower moisture content below 80% compared to boards produced by processes where the moisture content remains above 80% during enzymatic treatment of industrial and non-industrial waste cellulose fibers and more of the aluminum hydroxide migrates to the lower outer region.

[0230] One advantage of having a moisture content of less than 80% during enzyme treatment is that rigid cellulose boards can be formed into individual layers by depositing different compositions of raw materials and flame retardants and forming those different compositions to form boards with structural layers. Examples of such layered rigid boards are shown in Figures 15-18, where, except for the lower moisture content during enzyme treatment and deposition of the individual layers in the forming unit, the compositions of the individual layers are produced in the same manner as described above in connection with Examples 1-18. Figures 15-18 show examples of various combinations of industrial (sludge) and non-industrial (OCC) layers with either aluminum hydroxide or vermiculite in one or both of the top and bottom outer layers.

[0231] Figures 15-18 show the top, middle and bottom outer layers. Alternatively, the middle layer may not be necessary and the board may include only the top and bottom outer layers.

[0232] An alternative semi-dry process used to manufacture the boards described in Examples 19-24 above and the examples and alternatives of Figures 13-18 is described below.

[0233] The process shown in FIG. 19 includes an agitator 420 that integrates an enzyme applicator 410, a dryer 430 that integrates a trommel screener, and a screener 440.

[0234] FIG. 20 shows a similar embodiment, but further including a product forming device 450 fed by dosing devices 461, 462, 463 after the screener 440.

[0235] There are multiple paste or granular material conveyors, such as conveyor belts or screw conveyors, connecting the work stations to transport the cellulosic material through the proposed enzyme treatment system.

[0236] Raw fibrous cellulosic material 401, at least a portion of which is derived from industrial waste, e.g., sewage or primary sludge from the paper or processing industry and / or non-industrial waste such as waste corrugated cardboard (OCC), is fed to an agitator 420, where enzymes similar to those described in connection with the wet process of Examples 1-18 are added and mixed therein by a plurality of active stirring elements 421, allowing enzymatic treatment to occur within the agitator 420 for a specified period of time.

[0237] Active mixing elements 421 are parallel rotating blades housed within mixer 420 .

[0238] Enzyme applicator 410 includes a plurality of spray nozzles housed in agitator 420 and facing the top surface of raw fibrous cellulosic material 401 contained in agitator 420. The spray nozzles are supplied with liquid enzyme or a liquid aqueous solution of enzyme stored in a separated pile, and additional water may also be supplied.

[0239] The control unit 415 can, for example, adjust the amount of each enzyme added to the raw fibrous cellulosic material 401 in response to measuring the particular composition of the raw fibrous cellulosic material 401 being treated.

[0240] Once the enzyme is added, the moisture content of the raw fibrous cellulosic material 401 is between 20% and 80% to obtain sufficient fluidity for stirring with minimal moisture content. The water content of the added enzyme can be adjusted, or additional water can be added to the raw fibrous cellulosic material 401, for example, through a spray nozzle.

[0241] The fluidity of the raw fibrous cellulose material 401 and / or its moisture content are preferably measured or estimated from other measurements, for example from the energy consumption of the motor that powers the active stirring element 421 or by analysis of a sample.

[0242] The control unit 415 can automatically adjust the composition of the enzymes added to the raw fibrous cellulosic material 401, and / or the exact amount of water added to the raw fibrous cellulosic material 401, for example to add additional water, and / or the operating parameters of the agitator 420, which can be, for example, the movement velocity of the active agitating element 421 and / or the heater 423 that heats the raw fibrous cellulosic material 401 contained in the agitator 420.

[0243] The mixer 420 includes an mixer inlet at its top for introducing the raw fibrous cellulosic material 401 and an mixer outlet 422 at its bottom for extracting the treated cellulosic material, which is then transferred to the dryer 430 and screener 440.

[0244] Other alternative embodiments of the agitator 420 are also contemplated. For example, the agitator 420 can be a horizontal, rotating, hollow drum having an agitator inlet at one end and an agitator outlet 422 at the opposite end, with the active mixing elements being blades attached to the inside of the wall of the rotating drum configured not only for mixing but also for pushing the raw fibrous cellulosic material through the agitator 420 from the agitator inlet to the agitator outlet 422, where it spends a specified amount of time within the agitator 420. This embodiment allows for a continuous flow treatment process of the raw fibrous cellulosic material 401 within the agitator 420.

[0245] The trommel screener described above combines a dryer 430 and a screener 440 and comprises a rotating horizontal hollow drum containing a plurality of continuous meshes integrated into the wall of the rotating horizontal hollow drum.

[0246] Enzymatically treated material having a moisture content of 20% to 80% is introduced into the trommel screener through one end, and air heated by heater 431 is blown through a rotating horizontal hollow drum while the drum rotates to reduce the moisture content and produce treated cellulosic material having a moisture content of less than 20%.

[0247] Successive meshes have increasingly larger sized holes for screening different fractions 402, 403, 404 of dried, processed cellulosic material having different fiber lengths.

[0248] These fractions 402, 403, 404 have a moisture content of less than 20% and can therefore be stored in a simple manner for future use or used immediately.

[0249] One proposed use of the dried and processed cellulose material is the production of a rigid cellulose product, or more preferably a layered or structural layered rigid cellulose product 409 made from overlapping layers 405, 406, 407 of different fractions or layers 402, 403, 404 within a product forming apparatus 460.

[0250] The product forming apparatus 460 comprises a conveyor belt that passes between two opposing compression drums.

[0251] A plurality of successive application heads of dosing devices 461, 462, 463 face the conveyor belt. A first application head 461 deposits on the conveyor belt a front layer 405 of controlled thickness of the layered rigid cellulose product 409 to be produced, this layer being made of portions 402 of dried cellulose material 402, 403, 404. Successive application heads 462, 463 deposit additional layers 406, 407 of controlled thickness of the layered rigid cellulose product 409 to be produced on top of the front layer 405.

[0252] As the overlapping layers 405, 406, 407 pass between the compression drums, the layers are compressed and heated by the compression drums to produce a stratified rigid cellulosic product 409, in this case a flat, rigid board.

[0253] More complex shapes can be obtained by using a mold or press as the product forming device 450. In these cases, the mold, press, or application head 461, 462, 463 can be moved in a controlled manner to produce a deposit of overlapping layers covering the entire surface of the mold prior to closing the mold and applying pressure and heat.

[0254] One or more of fractions 402, 403, and 404 can be mixed with additives, such as flame retardants, as described above in connection with Examples 1-24, to provide particular layers with improved flame retardancy. For example, different layers can have different flame retardants, or layers, such as the middle layer, can be flame retardant-free. Examples of such boards that can be produced are the same as those shown in Figures 15-18.

[0255] The above examples describe boards having a combination of industrial and non-industrial waste, such as waste cardboard and a different industrial sludge source, as well as examples of a single fiber source only, such as waste cardboard or a different industrial sludge source. In alternative examples, the board can have a combination of only industrial waste, such as a mixture of paper sludge and fiber sludge.

[0256] In the above example, the final thickness of the rigid board is 12 mm. In another embodiment, the final thickness can be varied between 3 and 22 mm by varying the weight of solids introduced into the forming unit. It will be understood that boards of different thicknesses will require different drying regimes.

[0257] In the above example, the process is not continuous, specifically, the transfer of the partially wet board from the forming unit to the transfer unit and then to the drying tunnel and hot plate press is a manual process. In an alternative example, the process from initial pulping to drying of the board can be a continuous process.

[0258] It will be understood that the above forming and drying process and apparatus is not limited to mixtures of industrial and non-industrial waste, but may be applied to any cellulosic fiber source, either a single fiber source or a mixture of fiber sources.

[0259] In the above examples, the raw fibrous industrial waste and non-industrial cellulosic material are pulped, formed, and dried before being enzymatically treated. Alternatively, either or both of the raw fibrous industrial waste and non-industrial cellulosic material waste can be supplied as already pulped fibers without requiring a separate pulping step before enzymatic treatment. Such a supply can be a direct output from a non-industrial plant, such as a pulped output from a waste cardboard production plant, and / or a direct output from an industrial plant, preferably a pulped output from a paper plant. Such a supply can be a direct supply from industrial and non-industrial plants, where a plant integrating a paper and / or cardboard production plant with a process for producing a rigid cellulosic product is envisioned. Alternatively, the plants need not be integrated, and the pulped output can be stored before being supplied or transferred to a process for producing a rigid cellulosic product.

[0260] TIFF2026507241000002.tif202114

[0261] TIFF2026507241000003.tif88169

[0262] TIFF2026507241000004.tif86169

[0263] TIFF2026507241000005.tif86169

Claims

1. 1. A process for producing rigid cellulosic products from raw fibrous industrial waste, comprising: (i) providing or producing pulped post-industrial cellulose fibers from raw fibrous post-industrial waste; (j) enzymatically treating the pulped post-industrial cellulosic fibers to produce enzyme-treated post-industrial cellulosic fibers; (k) compressing the enzyme-treated industrial waste cellulose fibers to form compressed fibers; and (l) drying the compressed fibers to form a rigid cellulosic product, wherein the rigid cellulosic product has a fire classification of at least Class C when tested according to European Standard EN 13501-1.

2. 10. The process of claim 1, further comprising the step of selecting an amount of post-industrial cellulose fiber such that the calcium carbonate content of the post-industrial cellulose fiber compared to the weight of the rigid cellulose product is sufficient to obtain a rigid cellulose product having a fire classification of at least Class C when tested according to European Standard EN 13501-1.

3. 3. The process of claim 2, wherein the rigid cellulose board has a calcium carbonate content of more than 7 wt.%, preferably more than 7 wt.% and less than 50 wt.%, more preferably more than 7 wt.% and less than 35 wt.%, relative to the weight of the rigid cellulose product.

4. The process according to any one of claims 1 to 3, further comprising the step of adding a fire retardant, preferably an expansive volcanic mineral, preferably vermiculite, to said post-industrial cellulose fibres.

5. 5. The process of claim 4, wherein the expansive volcanic mineral is added in an amount sufficient to provide the rigid cellulose product with an expansive volcanic mineral content of more than 5 wt. % dry mass compared to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested according to European Standard EN 13501-1.

6. 6. The process according to any one of claims 1 to 5, wherein the post-industrial cellulose fibers do not contain calcium carbonate, preferably the post-industrial cellulose fibers are textile sludge residues from the textile manufacturing industry or construction waste cellulose fibers, and the process further comprises the step of adding a fire retardant, preferably aluminium hydroxide, to the post-industrial cellulose fibers.

7. 7. The method of claim 6, wherein the aluminum hydroxide is added to the industrial waste cellulose fibers in an amount sufficient to have an aluminum hydroxide content of greater than 15 wt. % dry mass compared to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested according to European Standard EN 13501-1.

8. (a) providing or producing a raw fibrous non-industrial waste cellulosic material, preferably one of virgin cellulosic fiber or waste cellulosic fiber, preferably pulped non-industrial waste cellulosic fiber derived from waste cardboard; (b) enzymatically treating the pulped non-industrial waste cellulose fibers; (c) combining the enzyme-treated non-industrial waste cellulose fibers with the enzyme-treated non-industrial waste cellulose fibers; (d) compressing the enzyme-treated industrial waste cellulose fibers combined with the enzyme-treated non-industrial waste cellulose fibers; and (e) drying the compressed industrial and non-industrial waste cellulose fibers to form a rigid cellulose product. The process of any one of claims 1 to 7, further comprising:

9. 9. The process of claim 8, wherein the process further comprises adding a flame retardant, preferably aluminum hydroxide or an expansive volcanic mineral, preferably vermiculite, to the non-industrial waste cellulose fibers, preferably waste cardboard.

10. 10. The process of claim 9, wherein the step of adding a flame retardant occurs after the step of enzyme treating the pulped non-industrial waste cellulose fiber and before the step of combining the enzyme-treated pulped industrial waste cellulose fiber with the non-industrial waste cellulose fiber.

11. 11. The process of claim 9 or 10, wherein the aluminum hydroxide is added to the non-industrial waste cellulose fibers in an amount sufficient to have an aluminum hydroxide content of greater than 15 wt. % dry mass compared to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested according to European Standard EN 13501-1.

12. 12. The process of any one of claims 9 to 11, wherein the expansive volcanic mineral is added in an amount sufficient to have an expansive volcanic mineral content of more than 5 wt% dry mass compared to the weight of the rigid cellulose product to provide the rigid cellulose product with a fire classification of Class B when tested according to European Standard EN 13501-1.

13. 13. The process according to any one of claims 1 to 12, wherein the raw fibrous industrial waste comprises fibers having 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 of more than 10%.

14. The process of any one of claims 1 to 13, wherein the industrial waste fibres are derived from one or more of primary sludge obtained from the paper industry or sludge residues from the textile manufacturing industry.

15. The process of any one of claims 4 to 14, wherein an upper outer region or layer and / or a lower outer region or layer of the rigid cellulosic product comprises the flame retardant.

16. 16. The process of any one of claims 1 to 15, wherein the step of compressing the diluted enzyme-treated industrial waste and / or non-industrial cellulose fibers to form a rigid cellulosic product is one of molding, preferably injection molding, or pressing in a forming unit and / or between drums to form a partially wet cellulosic product.

17. 17. The process of claim 16, wherein the step of compressing the enzyme-treated industrial waste and / or non-industrial waste cellulose fibers comprises depositing multiple distinct layers of enzyme-treated industrial waste and / or non-industrial waste cellulose fibers in the forming unit and pressing the multiple distinct layers to produce a multi-layered partially wet cellulose product.

18. 18. The process of claim 17 when dependent on claim 16, wherein the step of depositing multiple different layers of enzyme-treated industrial waste and / or non-industrial waste cellulose fibers in the forming unit includes the step of depositing an upper outer layer comprising the flame retardant, preferably one of aluminum hydroxide or an expansive volcanic mineral, and / or a lower outer layer comprising the flame retardant, preferably one of aluminum hydroxide or an expansive volcanic mineral.

19. 20. The process of claim 18, wherein the step of depositing multiple distinct layers of enzyme-treated post-industrial and / or non-industrial waste cellulose fibers in the forming unit includes depositing an intermediate layer of enzyme-treated post-industrial and / or non-industrial waste cellulose fibers that does not contain flame retardants between the upper outer layers.

20. A process according to any one of the preceding claims, wherein the rigid cellulosic product is a board, preferably a building board.

21. 21. The process of claim 20, wherein the board has one or more of the following characteristics: - at least 20% by weight of post-industrial fibers compared to the weight of the final rigid cellulose product; - thickness between 3 mm and 22 mm, an internal bond strength of at least 0.1 MPa, a bending strength of at least 4 MPa, and at least 400 kg / m ３ density.

22. 22. The process of claim 2 or any one of claims 2 to 21 when dependent on claim 2, wherein the method further comprises measuring the calcium carbonate content of the combined enzyme-treated post-industrial and / or non-industrial waste fibers before compressing the fibers, and checking the measured calcium carbonate content with a standard that correlates the calcium carbonate content of the combined enzyme-treated post-industrial and / or non-industrial waste fibers with the expected calcium carbonate content of the rigid cellulosic product before compressing the fibers.

23. 23. The process of claim 8 or any one of claims 8 to 22 when dependent on claim 8, wherein the non-industrial waste cellulose fibres are one of virgin cellulose fibres, preferably wood or plant fibres, more preferably miscanthus fibres, or preferably waste paper or waste cardboard fibres, preferably OCC fibres.

24. 24. The method of any one of claims 1 to 23, which does not include the step of adding a binder, adhesive or sticking agent to bind the cellulose fibers together.

25. 25. The process of claim 8 or any one of claims 8 to 24, wherein the combined industrial and non-industrial waste cellulose fibers comprise at least 20 wt%, preferably 20-80 wt%, preferably 30-70 wt%, preferably 40-60 wt% industrial waste cellulose fibers, the remainder of the combined industrial and cellulose fibers being non-industrial waste cellulose fibers.

26. 26. The process of any one of claims 1 to 25, wherein the moisture content during the enzyme treatment of the industrial waste fibers and / or non-industrial waste fibers is maintained above 80% to define a wet process.

27. 26. The process according to any one of claims 1 to 25, wherein the moisture content during the enzyme treatment of the industrial waste fibres and / or non-industrial waste fibres is maintained between 20% and 80% to define a semi-dry process.

28. 1. A rigid cellulose product comprising one or both of enzyme-treated industrial waste cellulose fibers and enzyme-treated non-industrial waste cellulose fibers, wherein the rigid cellulose product has a fire classification of at least Class C when tested according to European Standard EN 13501-1.

29. 30. The rigid cellulosic product of claim 28, which does not include any binders, adhesives or stickies to bind the cellulosic fibers together.

30. 30. The rigid cellulosic product of claim 28 or 29, comprising a flame retardant.

31. 31. The rigid cellulosic product of claim 30, wherein the flame retardant comprises aluminum hydroxide at a content of more than 15 wt% dry mass compared to the weight of the rigid cellulosic product.

32. 32. The rigid cellulose product according to any one of claims 28 to 31, having a calcium carbonate content of more than 7 wt%, preferably less than 50%, more preferably less than 35 wt%, relative to the weight of the rigid cellulose product.

33. 33. The rigid cellulosic product according to any one of claims 28 to 32, wherein the flame retardant comprises an expansive volcanic mineral at a content of more than 5 wt% of the dry mass compared to the weight of the rigid cellulosic product.

34. 34. The rigid cellulosic product of any one of claims 28 to 33, wherein the post-industrial cellulosic fibers are derived from primary sludge obtained from a paper plant.

35. 35. The rigid cellulosic product of any one of claims 28 to 34, wherein the non-industrial waste cellulosic fibers are derived from waste cardboard.

36. 34. The rigid cellulosic product of any one of claims 28 to 33, comprising a plurality of compressed overlapping layers, at least one of said layers comprising said flame retardant.

37. 37. The rigid cellulosic product of claim 36, wherein at least one of said layers is free of said flame retardant.

38. 38. The rigid cellulosic product of claim 36 or 37, wherein the plurality of compressed overlapping layers comprises an upper outer layer and a lower outer layer, and the upper and / or lower outer layer comprises the flame retardant.

39. 39. The rigid cellulosic product of claim 38 when dependent on claim 37, wherein an intermediate layer between the upper and lower outer layers does not contain the flame retardant.

40. 40. The rigid cellulose product of any one of claims 28 to 39, wherein the product has one or more of the following properties: - at least 20% by weight of post-industrial fibers compared to the weight of the final rigid cellulose product; - thickness between 3 mm and 22 mm, an internal bond strength of at least 0.1 MPa, a bending strength of at least 4 MPa, and at least 400 kg / m ３ density.

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