Processes for processing non-wood raw materials

Abstract

Methods for pretreating non-wood raw materials, particularly empty fruit bunch (EFB)5 raw materials, and pulps obtained using these methods are described.

Description

Technical Field

[0001] The present invention provides a method for pretreating a non-wood raw material, particularly an empty fruit bunch (EFB) raw material which is a waste formed after extraction of palm oil, wherein the pretreated non-wood raw material is for use in the production of paper or textile material grade pulp for applications in industries such as printing and writing paper, tissue paper, paperboard, and fashionable clothing later.

Background Art

[0002] Coupled with the shortage of wood raw materials for the global pulp and paper industry, the increasing importance of environmental sustainability means that the focus has shifted to finding alternative non-wood raw material sources. The same can be said for the fiber industry, which has a trend towards using renewable raw materials in fiber production.

[0003] Examples of non-wood raw materials that provide interesting alternatives to wood raw materials include oil palm empty fruit bunch (EFB) fiber, bamboo, kenaf, wheat / rice straw, coconut coir, and bagasse.

[0004] The oil palm (elaeis guineensus) typically grows in Southeast Asian countries such as Indonesia, Malaysia, and Thailand and is an important source of vegetable oil, specifically palm oil. Various biomasses are generated during the extraction of palm oil. One of the most abundant biomasses generated is the empty fruit bunch (EFB) fiber produced by the first step of the oil extraction process in which fruits and nuts are removed from the fruit bunch. The amount of EFB generated has been increasing year by year, and in 2015 alone, more than 30 million tons were generated in Indonesia alone. This presents an environmental problem in itself because this waste is often simply left to rot, attracting rodents.

[0005] EFB possesses several properties that make it interesting as a raw material for pulp—it has a high cellulose fiber content and a low lignin content, making it similar to hardwood fibers and usable to provide high-quality paper and regenerated cellulose. A process is known in which EFB is used as a raw material and then subjected to steaming to produce chemical pulp, thereby making it possible to produce paper and regenerated cellulose, such as viscose, modal, lyocell, and other artificial cellulose (MMC) fibers.

[0006] EFB and other non-wood materials are promising alternatives to wood in both the papermaking and textile industries. However, a problem with these raw materials is the presence of impurities, which cause problems with either processing or the quality of the final product. This means that when using EFB and other non-wood materials as raw materials, the digestion process must be adapted to include pretreatment steps to remove these impurities. Particularly problematic impurities include oil (in the form of fatty acids), silica, ash, and other non-process elements (NPEs). While it has been possible to develop processes to effectively remove oil, ash residue, and NPEs, the removal of silica has proven difficult.

[0007] While the removal of silica from non-wood raw materials in general is difficult, it is particularly challenging to remove silica from EFB (Earth Fiber) raw materials. Research on EFB has revealed that it has a specific structure consisting of silica deposits embedded within the fibers (see Figure 1), and these silica deposits are thought to contribute to the strength and rigidity of EFB (see also Law et al., (2007) Bioresources 2(3), 351-362). However, as mentioned above, the presence of silica in pulp mills is undesirable for several reasons, specifically due to recovery problems, poor product quality, and damage to machinery resulting from silica deposition during processing. Therefore, methods for pre-treating EFB raw materials to remove silica are being studied. To date, pretreatment methods have included physical, chemical, and biological treatments, such as washing with water, acid treatment, sonication, fungal / enzymatic treatment, and alkaline treatment (Agusta et al., (2018) Journal of Japan Tappo 6, 641-49, Tye et al. (2013) Procedia Environmental Sciences 20, 328-335, Farah et al., 2014, BioResource 9(1), 938-951, Nik et al., (208) MCRJ Special Issue 4(2), 117-128, Zawati et al., (2015) Wood Research 60(1), 157-166, Harsono et al., (2015) Journal of Wood Science 62, 55-73, Rusdan (2002) Oil Palm Bulletin See also 44,19-24), Rusdan et al.,(2018) Journal of Tropical Forest Science 19(3),121-126, Bahrin et al.,(2012) Biorescources 7(2),1784-1801, and Isroi et al.,Molecules 17(12),14995-15002).

[0008] Any pretreatment process must balance the removal of impurities, in this example silica clumps, with the damage caused to the EFB raw material by the pretreatment process. Most of these pretreatments are described in the context of producing sugars for either bioethanol production, furfural production, or chemical pulp production. In contrast, the present invention relates primarily to a process for producing artificial cellulose fibers (regenerated cellulose), such as viscose, for the textile industry, which are significantly affected not only by the presence of silica but also by any fiber damage sustained during previous processing steps. Thus, although known processes can remove sufficient silica for their intended end use, the remaining silica levels are still too high to be acceptable for the textile industry of regenerated cellulose fibers.

[0009] Therefore, it is clear that a pretreatment process is needed to remove high levels of silica without damaging the non-wood raw materials, which will ultimately be used in fiber manufacturing. [Overview of the Initiative]

[0010] In response to this, the inventors identified a pretreatment process that is effective in removing silica lumps from non-wood raw materials while avoiding significant damage to the cellulosic components of the raw materials.

[0011] More specifically, the present invention relates to a method for pre-treating non-wood raw materials, (a) Washing non-wood raw materials; (b) bringing the washed non-wood material into contact with an acid solution; and (c) Contact the washed non-wood raw materials with an alkaline solution. The present invention provides a method that includes an additional cleaning step (d) between step (b) and step (c).

[0012] Conveniently, the inventors have found that by performing steps (a), (b), (c), and (d), this pretreatment process yields a raw material that is virtually silica-free while maintaining its structural integrity and minimizing damage to the cellulosic components of the raw material. More specifically, the inventors have found that, surprisingly, it is possible to effectively remove the problematic silica clumps from the raw material fibers by combining a series of steps, each performed under conditions mild enough to avoid undesirable structural damage. This is particularly surprising given the previous understanding in industry that removing these silica clumps requires extreme and / or harsh conditions.

[0013] Furthermore, the pretreatment method of the present invention can be easily incorporated into existing wood flour / crushed chip plants, organosolves, and soda or kraft pulp mills. It is particularly advantageous for use in integrated pulp mills, i.e., plants where all processes from raw materials to finished products are carried out, because reactants from the later stages of the process can be reused in the pretreatment method, especially in step (b). This improves efficiency and minimizes waste.

[0014] The present invention further provides dissolved pulp (DP) derived from non-wood raw materials, particularly from non-wood empty fruit bunches (EFB), having a silica content of less than approximately 80 ppm. Conveniently, the low level of silica present in the DP means that it can later be processed into regenerated cellulose fibers for the textile industry to produce high-quality products. In particular, if silica is still present in the DP, problems with cellulose dissolution will arise, and the spinneret used to draw fibers from the DP later will become clogged.

[0015] The present invention further provides kraft pulp (KP) derived from non-wood raw materials, particularly non-wood empty fruit bunch (EFB) raw materials, having a silica content of less than approximately 600 ppm. Conveniently, the low level of silica present in the KP means that it can subsequently be processed into paper products without damaging the digester used. In particular, if silica is still present in the KP, it can lead to its accumulation (i.e., sandy deposits) in the digester, which can not only damage the machine but also result in holes in the final product. KP produced by the method described herein is not plagued by these problems.

[0016] The inventors have found that DP and KP obtained from raw materials pretreated according to the method of the present invention have equivalent or better quality than DP and KP obtained using conventional wood raw materials. Furthermore, they can be obtained in comparable yields. [Modes for carrying out the invention]

[0017] The pretreatment method of the present invention can be used with various non-wood raw materials. In this regard, the term "non-wood raw material" is used herein to refer to any raw material that is plant-based but does not originate from a wood source. Examples of suitable non-wood raw materials include oil palm empty fruit bunches (EFB), bamboo, bagasse, kenaf, coconut coil, and wheat / rice straw. Preferably, the non-wood raw material is an EFB raw material or a bamboo raw material. Most preferably, the wood raw material is an EFB raw material.

[0018] The term "non-processed element (NPE)" is used herein to refer to metals containing undesirable inorganic impurities other than silica and ash, such as iron and calcium.

[0019] The first step of the pretreatment process of the present invention is a step (a) of washing the non-wood material. This washing step is included first for the purpose of removing residual oil from the non-wood material. Washing may be carried out using either water and / or steam. Preferably, the washing step (a) is carried out at a temperature in the range of 80°C to 100°C. It will be noted that when water is used at the lower end of this temperature range in the washing step (a), a mixture of water and steam is present, while at the upper end of the temperature range, only steam is present. During step (a) of the method of the present invention, it is preferable to mechanically agitate the non-wood material, preferably by gentle mechanical agitation. It is preferable to agitate the non-wood material to a very slight degree, such as that which can be achieved by passing the non-wood material through a screw conveyor. Those skilled in the art will be familiar with screw conveyors, an example of which is shown in Figure 11.

[0020] Prior to step (a) of the method of the present invention, the non-wood raw material may be subjected to a standard industrial process, such as shredding. When the non-wood raw material is shredded, the resulting fibers are preferably in the range of about 5 mm to about 100 mm in length.

[0021] After the initial washing step (a), the washed non-wood raw material is brought into contact with an acid solution in step (b) of the method. Contacting the non-wood raw material with acid reduces the content of any residual metal impurities. This is particularly effective in removing iron and calcium residues from the raw material. Furthermore, although we do not wish to dwell on theory, this acid treatment step is also considered to be extremely important in the process of removing silica from the supply raw material. As mentioned earlier, non-wood raw materials, especially EFB raw materials, have a structure in which silica clumps are embedded on the surface of the fibers. Contacting the fibers with acid causes the fibers to shrink, which in turn initiates a process of removing the silica clumps.

[0022] The acid solution contains an acid and water. Any acid may be used to form the acid solution. Preferably, the acid used is selected from the group consisting of sulfuric acid, hydrochloric acid, aqueous chlorine dioxide, and mixtures thereof. As will be described later, pulp mills typically include a bleaching process. An advantage of the pretreatment method of the present invention is that the acid used in step (b) of the pretreatment method can be provided by the acid used in the bleaching process that is reused as is in step (b) of the pretreatment method, as a result of which the efficiency can be improved and the generation of waste and costs can be minimized.

[0023] The acid solution in step (b) contains the acid at a concentration in the range of about 0.2 to 5.0%. This ensures that the acid solution is concentrated enough to shrink the fibers of the non-wood raw material to facilitate the removal of silica impurities, but is dilute enough to minimize undesirable damage to the raw material, especially the cellulose in the raw material.

[0024] Preferably, step (b) is carried out in the pH range of 1 to 3.

[0025] Step (b) is generally carried out at a temperature in the range of about 80°C to about 100°C. It is preferred to carry out step (b) at an elevated temperature. This is because it increases the rate at which step (b) proceeds and also improves the efficiency of the process.

[0026] If the non-wood raw material from step (a) is washed at an elevated temperature as described above, step (b) can also be carried out at an elevated temperature (i.e., a temperature in the range of about 80 to about 100°C), thereby avoiding the need to include a step of cooling the washed non-wood raw material before step (b), and improving the overall process efficiency.

[0027] Step (b) is carried out for a time sufficient to cause shrinkage of the fibers. Preferably, step (b) has a duration in the range of about 30 to about 60 minutes. The extent to which step (b) proceeds can be measured and monitored by measuring the impurities to be removed, particularly the ash residue, NPE and silica content. At the end of step (b), typically, the silica content will have decreased slightly while the ash residue and NPE will have been removed almost completely. A person skilled in the art will be familiar with suitable quality measurements.

[0028] In step (c) of the method of the present invention, the washed non-wood raw material is contacted with an alkaline solution. Contacting the raw material with the alkaline solution further serves to remove silica impurities. More specifically, contacting the raw material with the alkaline solution results in the swelling of the fibers that contributes to the removal of silica from the raw material.

[0029] Step (c) is carried out after step (a) but may be carried out either before or after step (b). In one method according to the present invention, step (c) is carried out before step (b). In an alternative method according to the present invention, step (c) is carried out after step (b). Preferably, step (c) is carried out after step (b). This is advantageous because, as will be described in more detail later, the non-wood raw material is cooked to form pulp after the pretreatment. The preferred cooking step is carried out under alkaline conditions, so if the pretreatment method ends with an alkaline step, it is already at a pH suitable for the cooking step, and thus the need for an additional neutralization step is avoided.

[0030] It is a combination of step (b) and step (c), which causes the non-wood raw material to shrink and swell respectively, leading to the effective removal of silica impurities.

[0031] The alkaline solution used in step (c) contains alkali and water. Any alkali may be used to form the alkaline solution, but preferably the alkali is sodium hydroxide. Sodium hydroxide is preferred because, as described above, it is used immediately after the pretreatment in the subsequent steaming step. Using the same alkali in step (c) improves the overall process efficiency.

[0032] The alkaline solution in process (c) contains alkali at a concentration ranging from approximately 0.2% to approximately 5.0%. This ensures that the alkaline solution is concentrated enough to swell the non-wood raw material fibers to facilitate the removal of silica impurities, but dilute enough to minimize undesirable damage to the raw material, particularly the cellulose in the raw material.

[0033] Preferably, step (c) is carried out in a pH range of 12 to 14.

[0034] Process (c) is generally carried out at a temperature in the range of approximately 80°C to 100°C. It is preferable to carry out process (c) at a higher temperature because this increases the rate at which process (b) proceeds and improves the efficiency of the process.

[0035] If the non-wood raw materials from process (a) are washed at the elevated temperature described above, then carrying out process (c) at a similar elevated temperature (i.e., a temperature in the range of approximately 80 to 100°C) eliminates the need to include a step to cool the washed non-wood raw materials before process (c), thereby improving the overall process efficiency.

[0036] Step (c) is carried out for a sufficient amount of time to cause the fibers to expand. Preferably, step (c) has a duration ranging from about 30 to about 60 minutes. The extent to which step (c) has progressed can be measured and monitored by measuring the amount of silica remaining in the feed material. At the end of step (c), the silica content will typically be significantly reduced. Those skilled in the art will be familiar with suitable quality measurements.

[0037] The pretreatment method of the present invention includes a further washing step, step (d), between steps (b) and (c), regardless of the order in which steps (b) and (c) are performed. This washing step is included primarily for the purpose of removing metal and silica (typically fine silica) impurities that have been removed from the non-wood fibers as a result of earlier steps performed. The washing in step (d) may be carried out using either water and / or steam. Preferably, washing step (d) is carried out at a temperature in the range of 80°C to 100°C. It will be noted that if water is used at the lower end of this temperature range in washing step (d), a mixture of water and steam will be present, while at the upper end of the temperature range, only steam will be present. During step (a) of the method of the present invention, it is preferable to mechanically agitate the non-wood material, preferably by gentle mechanical stirring. It is preferable to agitate the non-wood material to a very slight degree, such as that which can be achieved by passing the non-wood material through a screw conveyor. Those skilled in the art will be familiar with screw conveyors, an example of which is shown in Figure 11.

[0038] The method of the present invention may include a further washing step (e) after whichever of step (b) or step (c) is performed last. If present, this additional washing step is included primarily for the purpose of removing silica impurities. Washing step (e) may be performed using either water and / or steam. Preferably, washing step (e) is performed at a temperature in the range of 80°C to 100°C. It will be noted that if water is used at the lower end of this temperature range in washing step (e), a mixture of water and steam will be present, while at the upper end of the temperature range, only steam will be present. During step (a) of the method of the present invention, it is preferable to mechanically agitate the non-wood material, preferably by gentle mechanical stirring. It is preferable to agitate the non-wood material to a very slight degree, such as that which can be achieved by passing the non-wood material through a screw conveyor. Those skilled in the art will be familiar with screw conveyors, an example of which is shown in Figure 11.

[0039] At the point of being subjected to the pretreatment method of the present invention, the non-wood raw material is suitable for further processing to form pulp, which can then serve as a raw material for paper, or as a raw material in the production of regenerated cellulose, such as viscose, modal, lyocell, or other MMC fibers.

[0040] The method of the present invention can be carried out using standard equipment found in a standard pulp mill, which will be familiar to those skilled in the art. In particular, the pretreatment method of the present invention is useful in integrated pulp mills, so that materials, such as acids used in the bleaching process, can be reused in the pretreatment method of the present invention.

[0041] Before further processing, the non-wood raw material may be formed into a bale. Alternatively, before further processing, the non-wood raw material may be pelletized.

[0042] Those skilled in the art will be familiar with suitable methods for converting pre-treated non-wood raw materials into pulp. In particular, there are two common methods used for steaming the raw materials: the sulfate (kraft) process and the pre-hydrolysis (PH) kraft process.

[0043] In the krafting process, pre-treated non-wood raw materials are mixed with a high-temperature mixture known as "white liquor," which contains water, sodium hydroxide, and sodium sulfite. Anthraquinone may be added as an accelerator to improve yield. During this process, lignin present in the raw materials is broken down and dissolved in the alkali. The remaining solid pulp, known as "brown pulp," can be recovered in a state ready for further processing. The lignin fraction, the small fraction of carbohydrates, and the mixed liquid ("black liquor") containing sodium sulfate, sodium carbonate, and other inorganic salts can be removed and subsequently incinerated to provide energy that is returned to the steaming process.

[0044] The "brown pulp" obtained in the kraft process is typically bleached to produce pulp with high brightness. Several different bleaching processes can be used, and those skilled in the art will be familiar with them. One example of a suitable bleaching process is chlorine-free (ECF) bleaching, in which the brown pulp is sequentially contacted with monopersulfuric acid (which can be produced by mixing sulfuric acid and hydrogen peroxide), chlorine dioxide, hydrogen peroxide, and chlorine dioxide. Another example of a suitable bleaching process is totally chlorine-free (TCF) bleaching, in which the brown pulp is subjected to bleaching with ozone and hydrogen peroxide. More specifically, TCF typically involves four or five different steps, both of which include treatment with chelating agents, as well as several bleaching steps, such as bleaching with oxygen, alkaline extraction with hydrogen peroxide addition, peracetic acid bleaching, and / or hydrogen peroxide bleaching with or without oxygen. TCF bleaching has the advantage of not using any chlorine and therefore not producing any chlorine-containing by-products. The quality of pre-treated non-wood raw materials obtained by the method of the present invention means that less energy is required in the bleaching process.

[0045] An advantage of the pretreatment method of the present invention is that the acid used in such bleaching processes can be returned to step (b) of the pretreatment method and reused, thus reducing the amount of acid required in the overall process and reducing waste.

[0046] In the PH Kraft process, non-wood raw materials are first subjected to an aqueous autohydrolysis process to remove hemicellulose and some lignin. This is then steamed under alkaline conditions (Kraft steaming) to remove most of the lignin and any remaining small fractions of hemicellulose. A final multi-stage bleaching process (e.g., ECF bleaching or TCF bleaching) is performed to improve the brightness of the final pulp. Anthraquinones may be included as accelerators to improve yield in the PH Kraft process.

[0047] Preferably, the pre-treated non-wood material obtained by the method of the present invention is steamed using a PH Kraft process.

[0048] In both steaming methods, the quality of the resulting pulp can be controlled by varying several parameters, specifically the H factor, P factor, kappa number, and effective alkali percentage. More specifically, by controlling these parameters, it is possible to control whether the resulting pulp becomes dissolved pulp (DP) or kraft pulp (KP).

[0049] Dissolved pulp (DP) is a high-grade, pure cellulose pulp with high brightness, a uniform molecular weight distribution, and an open-pore structure, which makes it highly reactive. DP is typically used in the production of regenerated cellulose.

[0050] Kraft pulp (KP) is a type of pulp that contains both cellulose and hemicellulose. KP is typically used in the manufacture of paper.

[0051] As those skilled in the art will recognize, these parameters have standard definitions. The H factor is a kinetic model of the rate of deligninization and depends on both temperature and time. The P factor depends on time and temperature in an aqueous medium. The kappa number is a measure of process integrity and indicates the amount of lignin remaining in the pulp; it is measured as the amount of standard potassium permanganate solution that the pulp will consume. The effective alkali % is the total concentration of alkali components other than carbonates present in the reactants, measured by titrating a sample of white liquor with a strong acid according to the procedure presented in SCAN-N-30.

[0052] Table 1 below shows examples of suitable parameter ranges for obtaining DP and KP. [Table 1]

[0053] As a result of the pretreatment method of the present invention using non-wood raw materials, the present invention provides DP and KP having a very low impurity content.

[0054] Surprisingly, it was also found that when non-wood raw materials were treated according to the method of the present invention before steaming, the required steaming time was shortened. This means that less energy is required for the steaming process. Furthermore, it was found that non-wood raw materials treated according to the method of the present invention required less bleaching. Moreover, as can be seen in Figure 10, the amount of bleaching chemicals required in subsequent bleaching of non-wood raw materials treated according to the method of the present invention was significantly reduced, and in particular, when the non-wood raw material is an EFB raw material, the amount of chemicals consumed was almost halved.

[0055] In particular, the DP and KP obtained using the pretreatment method of the present invention satisfy the standards shown in Table 2 below. [Table 2]

[0056] The low silica content of the DP obtained using the method of the present invention is particularly remarkable considering the previous problems encountered in attempts to remove silica from non-wood raw materials. This is especially true when the non-wood raw material is EFB raw material.

[0057] In this regard, the present invention provides a dissolved pulp derived from non-wood raw materials having a silica content of less than about 80 ppm.

[0058] The silica content may be determined according to the method presented in standard Tappi T211-om-07.

[0059] Alternatively, or furthermore, dissolved pulp derived from non-wood raw materials has an Fe content of approximately 10 ppm or less.

[0060] The iron (Fe) content can be determined according to the method presented in standard Tappi T618-cm-01.

[0061] Alternatively, or furthermore, dissolved pulp derived from non-wood raw materials has a Ca content of approximately 75 ppm or less.

[0062] The calcium content may be determined according to the method presented in standard Tappi T618-cm-01.

[0063] The presence of Fe and / or Ca impurities in DP is undesirable because it affects subsequent processes that dissolve cellulose, ultimately leading to the need to increase the amount of chemicals used in such processes.

[0064] Alternatively, or furthermore, dissolved pulp derived from non-wood raw materials has an ash content of approximately 0.12% by weight or less.

[0065] The ash content may be determined according to the method presented in standard Tappi T322-om-07.

[0066] The present invention further provides kraft pulp derived from non-wood raw materials having a silica content of less than approximately 600 ppm.

[0067] Alternatively, or furthermore, kraft pulp derived from non-wood raw materials has an ash content of approximately 0.35% or less.

[0068] In particular, the present invention provides dissolved pulp derived from non-wood empty fruit clusters (EFB) having a silica content of less than approximately 80 ppm.

[0069] Alternatively, or furthermore, dissolved pulp derived from non-wood EFB has an Fe content of approximately 10 ppm or less.

[0070] Alternatively, or furthermore, dissolved pulp derived from non-wood EFB has a Ca content of approximately 75 ppm or less.

[0071] Alternatively, or furthermore, dissolved pulp derived from non-wood EFB has an ash content of approximately 0.12% or less.

[0072] The present invention further provides kraft pulp derived from non-wood empty fruit bunches (EFB) having a silica content of less than approximately 600 ppm.

[0073] Alternatively, or furthermore, kraft pulp derived from non-wood empty fruit bunches (EFB) has an ash content of approximately 0.35% or less.

[0074] The DP of the present invention has high luminance. Luminance is a measure of the amount of incident light reflected from the pulp under specified conditions, as measured by the method presented in the standard Tappi T525-om-06. The DP of the present invention preferably has a luminance (ISO) of about 90% or more.

[0075] The KP of the present invention has high luminance. Luminance is a measure of the amount of incident light reflected from the pulp under specified conditions, as measured by the method presented in the standard Tappi T525-om-06. The KP of the present invention preferably has a luminance (ISO) of about 90% or more.

[0076] The soluble pulp obtained by the method of the present invention can be further processed to yield regenerated cellulose. The term "regenerated cellulose" is used herein to describe a category of materials produced by converting natural cellulose from non-wood raw materials into soluble cellulose derivatives, which are then regenerated to typically form either fibers or films. Those skilled in the art will be familiar with the techniques for processing soluble pulp to form regenerated cellulose. The first step in this further processing is typically the conversion of the soluble pulp into a cellulose dope. If the final product is a viscose textile fiber, the next step typically involves subjecting the cellulose dope to sulfidation in the presence of CS2 and sodium hydroxide. If the final product is a lyocell textile fiber, the cellulose dope typically involves subjecting it to an N-methylmorpholine N-oxide (NMMO) reaction. In either case, the products of the subsequent steps can be extruded from a spinneret and regenerated to form desired artificial fibers, such as viscose and / or lyocell textile fibers. It is also possible to produce other artificial cellulose (MMC) fibers, which are an attractive option in the textile industry. This is because, compared to cotton, for example, it can be manufactured using significantly less water, and the resulting material is highly breathable.

[0077] The kraft pulp obtained by the method of the present invention can be further processed to produce paper products. Those skilled in the art will be familiar with the techniques for forming paper products from pulp. In particular, the process typically involves suspending the pulp in water, then flattening it mechanically, drying it, and cutting it to form sheets and rolls.

[0078] The present invention will now be described in more detail with reference to the following figures and examples, which are not intended to limit the scope of the claims. [Brief explanation of the drawing]

[0079] [Figure 1]Figure 1 shows the location of silica clumps within the EFB fibers. [Figure 2] Figure 2 is a block diagram illustrating the pretreatment method of the present invention. [Figure 3(a)] Figure 3(a) shows the silica content of non-wood EFB raw materials before and after pretreatment by the method of the present invention, in comparison with the prior art. [Figure 3(b)] Figure 3(b) shows the silica content of non-wood bamboo raw materials before and after pretreatment by the method of the present invention, in comparison with the prior art. [Figure 4(a)] Figure 4(a) shows the ash content of non-wood EFB raw materials before and after pretreatment by the method of the present invention, in comparison with the prior art. [Figure 4(b)] Figure 4(b) shows the ash content of non-wood bamboo raw materials before and after pretreatment by the method of the present invention, in comparison with the prior art. [Figure 5] Figure 5 shows the silica content of non-wood EFB raw materials and non-wood bamboo raw materials before and after the pretreatment method of the present invention. [Figure 6] Figure 6 is an image of non-wood EFB KP manufactured by the method of the present invention. [Figure 7] Figure 7 shows an image of non-wood EFB DP manufactured by the method of the present invention. [Figure 8] Figure 8 is a block diagram illustrating a process for manufacturing paper products, including the pretreatment method of the present invention. [Figure 9(a)] Figure 9(a) is a block diagram illustrating a process for producing viscose, including the pretreatment of the present invention. [Figure 9(b)] Figure 9(b) is a block diagram illustrating a process for producing lyocell, including the pretreatment described in the present invention. [Figure 10] Figure 10 shows the consumption of chlorine dioxide (ClO2) during the ECF bleaching process performed on EFB raw materials treated according to the method of the present invention, in contrast to broadleaf trees, specifically acacia crassicarpa (ACRA), Eucalyptus pellita (EPEL), and Eucalyptus hybrid (EHYB). [Figure 11] Figure 11 shows a screw-type conveyor that can be used in the method of the present invention to move non-wood raw materials from one stage to another. [Figure 12] Figure 12 shows the date and time when the raw material was changed from standard wood raw material to mixed EFB / wood raw material in Example 3. [Figure 13] Figure 13 shows the productivity (H factor) of the factory where the raw material was changed from wood chips to mixed EFB / wood chips during the test described in Example 3. [Figure 14] Figure 14 shows the amount of oxygen consumed during bleaching in the factory described in Example 3. [Figure 15] Figure 15 shows the amount of alkali used during bleaching in the factory described in Example 3. [Figure 16] Figure 16 shows the silica content of bleached kraft pulp obtained from the mixed raw materials described in Example 3. [Figure 17] Figure 17 shows the stain / count of bleached kraft pulp obtained from the mixed raw materials described in Example 3. [Examples]

[0080] Example 1 - Non-wood EFB raw material Approximately 100 kg of non-wood EFB, processed to exclude kernels, palm seeds, and mud, was obtained from Asian Agri (RGE Palm Oil Business). This EFB raw material, with fiber lengths ranging from 5 to 100 mm, was then passed through a shredder and washing machine.

[0081] The silica and ash residue content of non-wood EFB was measured according to Tappi T618-cm-01. The results are shown in Figures 3(a) and 4(a).

[0082] Next, the non-wood EFB material was washed in a drum washing machine using a mixture of water and steam at a temperature in the range of 80-100°C. The EFB material was moved to the next processing step by a screw conveyor (which provided some mechanical agitation). The washing process was carried out for a continuous period of 30-60 minutes. The washed EFB material was then passed through a container containing an acid solution at a temperature in the range of 80-100°C with a sufficient bath ratio (7-10) and a pH in the range of 1-3. After 30-60 minutes, the EFB material was removed from the acid container and passed through a drum washing machine, which washed it using a mixture of water and steam at a temperature in the range of 80-100°C. After 30-60 minutes, the washed and acid-treated EFB material was passed through a container containing an alkaline solution at a temperature in the range of 80-100°C with a sufficient bath ratio (7-10) and a pH in the range of 12-14. After 30-60 minutes, the EFB was removed from the container with alkali and passed through a drum washing machine using a mixture of water and steam at a temperature in the range of 80-100°C. The pre-treated EFB material was then moved to the next process by a screw conveyor (which provided some mechanical agitation).

[0083] The silica and ash residue content of the pre-treated EFB raw materials was measured according to Tappi T618-cm-01, and the results are shown in Figures 3(a) and 4(b).

[0084] The pre-treated EFB raw materials were then steamed under pre-hydrolysis kraft (P factor 1000-1300) / kraft for both DP and KP. Available alkali was used in amounts ranging from 15-20%, with H factors in the range of approximately 100-300 (see Table 1). Target specifications for chemical pulp (DP and KP), as presented in Table 2, were achieved.

[0085] Example 2 - Non-wood bamboo raw material Approximately 5 kg of non-woody bamboo sheath was shredded and passed through a mesh sieve with a size of 7-13 mm to form bamboo chips of a standard particle size.

[0086] The silica and ash residue content of non-wood bamboo was measured according to Tappi T618-cm-01. The results are shown in Figures 3(b) and 4(b).

[0087] Next, the non-wood bamboo material was washed in a drum washing machine using a mixture of water and steam at a temperature in the range of 80-100°C. The bamboo material was then moved to the next processing step by a conveyor belt. The washing process was carried out for a continuous period of 30-60 minutes. The washed bamboo material was then passed through a container containing an acid solution at a temperature in the range of 80-100°C with a pH in the range of 1-3 and a sufficient bath ratio (4-7). After 30-60 minutes, the bamboo material was removed from the acid container and passed through a drum washing machine that washed it using a mixture of water and steam at a temperature in the range of 80-100°C. After 30-60 minutes, the washed and acid-treated bamboo material was passed through a container containing an alkaline solution at a temperature in the range of 80-100°C with a pH in the range of 12-14 and a sufficient bath ratio (4-7). After 30-60 minutes, the bamboo material was removed from the alkaline container and passed through a drum washing machine using a mixture of water and steam at a temperature in the range of 80-100°C. The pre-treated bamboo material was then moved to the next process via a conveyor belt.

[0088] The silica and ash residue content of the pre-treated bamboo raw material was measured according to Tappi T618-cm-01, and the results are shown in Figures 3(b) and 4(b).

[0089] Pre-treated bamboo raw materials were then steamed under pre-hydrolysis kraft (P factor 500-800) / kraft for both DP and KP. Available alkali was used in amounts ranging from 15-20%, with an H factor in the range of approximately 500-700. The target specifications for chemical pulp (DP and KP), as presented in Table 2 above, were achieved.

[0090] Example 3 - EFB Raw Material Factory Test In an operational plant processing 35 tons of raw materials per day, standard wood raw materials were replaced with mixed wood raw materials containing 5-10% by weight of EFB raw materials. Various products were measured and monitored, as summarized below. Processes supplied with the mixed EFB raw materials included the pretreatment method of the present invention.

[0091] Figure 12 shows the point at which the feed was changed to include 5-10% by weight of EFB material. As can be seen from Figure 13, when the feed was changed to mixed EFB material, higher steam productivity was observed at the same level of alkali filling and kappa number (evidence of a lower H factor). Referring to Figures 14 and 15, it is also clear that the consumption of chemicals in the bleaching process was reduced - both oxygen and alkali filling were reduced, and the total amount of ClO2 filling was also reduced (47.3 kg for pure wood material compared to 46.2 kg for mixed EFB / wood material).

[0092] In addition to these reductions in both chemical consumption and energy requirements, it was fortunately found that the quality of the final bleached pulp was maintained. Specifically, the resulting pulp had the following characteristics: [Table 3]

[0093] The final product in the factory test described in Example 3 was a paper product. Surprisingly, when the raw material was changed from pure wood to a mixture of EFB and wood, and the process included the pretreatment method of the present invention, the final paper product exhibited excellent properties, specifically a tensile strength of 70 Nm / g and 1.39 cm². 3 It was found to have a bulk density of 1 / g. The paper also demonstrated high performance in both drainage and operability.

[0094] Overall, by replacing the wood raw material with a mixed EFB / wood raw material and incorporating the pretreatment method of the present invention, it was possible to manufacture a product with the required excellent properties while reducing energy consumption by approximately 10%.

[0095] Exemplary Embodiments The present invention is further described by reference to exemplary embodiments numbered below.

[0096] 1. A method for pre-treating non-wood raw materials, (a) Washing the non-wood raw material; (b) bringing the washed non-wood material into contact with an acid solution; and (c) Contacting the washed non-wood material with an alkaline solution. The method comprising, wherein the method includes an additional cleaning step (d) between step (b) and step (c).

[0097] 2. The method according to Embodiment 1, wherein step (b) is performed before step (c).

[0098] 3. The method according to Embodiment 1, wherein step (c) is performed before step (b).

[0099] 4. The method of any prior embodiment, wherein in step (a), the non-wood material is washed using water and / or steam.

[0100] 5. The method of any prior embodiment, wherein step (a) is carried out at a temperature in the range of 80 to 100°C.

[0101] 6. The method of any prior embodiment, wherein in step (a), the non-wood raw material is passed through a screw-type conveyor.

[0102] 7. The method according to any prior embodiment, wherein in step (b), the washed non-wood material is in contact with the acid solution at a temperature in the range of 80 to 100°C for a continuous period of 30 to 60 minutes.

[0103] 8. The method of any prior embodiment, wherein in step (b), the pH is in the range of 1 to 3.

[0104] 9. The method of any prior embodiment, wherein in step (b), the acid solution comprises an acid selected from the group consisting of sulfuric acid, hydrochloric acid, aqueous solutions of chlorine dioxide, and mixtures thereof.

[0105] 10. The method according to any prior embodiment, wherein in step (b), the acid solution contains the acid at a concentration of about 0.2 to about 5%.

[0106] 11. The method according to any one of Embodiments 1 to 9, wherein in step (b), the acid solution includes an acid solution reused from a step in which dissolved pulp (DP) and / or kraft pulp (KP) are bleached.

[0107] 12. The method according to Embodiment 11, wherein in step (b), the acid solution contains recycled acid at a concentration of about 0.2 to about 5%.

[0108] 13. The method according to any prior embodiment, wherein in step (d), the non-wood material is washed using water and / or steam.

[0109] 14. The method of any prior embodiment, wherein step (d) is carried out at a temperature in the range of 80 to 100°C.

[0110] 15. The method according to any prior embodiment, wherein in step (d), the non-wood raw material is passed through a screw-type conveyor.

[0111] 16. The method according to any prior embodiment, wherein in step (c), the washed non-wood material is in contact with the alkaline solution at a temperature in the range of 80 to 100°C for a continuous period of 30 to 60 minutes.

[0112] 17. The method of any prior embodiment, wherein in step (c), the pH is in the range of 12 to 14.

[0113] 18. The method of any prior embodiment, wherein in step (c), the alkaline solution contains sodium hydroxide.

[0114] 19. The method according to Embodiment 18, wherein in step (c), the alkaline solution contains sodium hydroxide at a concentration of about 0.2 to about 5%.

[0115] 20. (e) Wash the product obtained after steps (a) to (d). A method of any prior embodiment, further including the method of any prior embodiment.

[0116] 21. The method according to Embodiment 20, wherein in step (e), the product is washed with water and / or steam.

[0117] 22. The method according to Embodiment 20 or Embodiment 21, wherein step (e) is carried out at a temperature in the range of 80 to 100°C.

[0118] 23. The method according to any one of embodiments 20 to 22, wherein in step (e), the non-wood raw material is passed through a screw-type conveyor.

[0119] 24. The method according to any prior embodiment, wherein the non-wood raw material is a non-wood empty fruit cluster (EFB).

[0120] 25. A method for producing dissolved pulp (DP) from non-wood raw materials, (i) Pre-treating the non-wood raw material using the method described in any one of Embodiments 1 to 24; and (ii) Steaming the pre-treated non-wood raw material to produce DP. The method, including the method described above.

[0121] 26. A method for producing kraft pulp (KP) from non-wood raw materials, (i) Pre-treating the non-wood raw material using the method described in any one of Embodiments 1 to 24; and (ii) Steaming the pre-treated non-wood raw materials to produce KP. The method, including the method described above.

[0122] 27. The method according to Embodiment 25 or Embodiment 26, wherein the non-wood raw material is a non-wood empty fruit cluster (EFB).

[0123] 28. The method according to Embodiment 25 or Embodiment 27, further comprising a step of bleaching the DP obtained in step (ii).

[0124] 29. The method according to Embodiment 26 or Embodiment 27, further comprising a step of bleaching the KP obtained in step (ii).

[0125] 30. The method according to Embodiment 28 or Embodiment 29, wherein the bleaching step is an chlorine-free (ECF) bleaching step.

[0126] 31. The bleaching process described above is (iii) Treat the DP sequentially with monopersulfuric acid, chlorine dioxide, hydrogen peroxide, and chlorine dioxide. The method according to embodiment 30, including the method described above.

[0127] 32. The method according to Embodiment 28 or Embodiment 29, wherein the bleaching step is a completely chlorine-free (TCF) bleaching step.

[0128] 33. The method according to any one of embodiments 28 to 32, wherein the acid from the bleaching step is reused in step (b) of the pretreatment step (i).

[0129] 34. The method according to Embodiments 26, 27, or 29-33, wherein the KP is converted into a paper product.

[0130] 35. The method according to Embodiments 25, 27, 28 or 30-33, wherein the DP is converted to regenerated cellulose.

[0131] 36. The method according to Embodiment 35, wherein the regenerated cellulose is selected from the group consisting of viscose fibers, modal fibers, lyocell, and MCC fibers.

[0132] 37. Dissolved pulp that can be obtained by the method described in any one of Embodiments 25, 27, 28 or 30-33.

[0133] 38. Kraft pulp that can be obtained by the method described in any one of Embodiments 26, 27, or 29-33.

[0134] 39. Dissolved pulp derived from non-wood raw materials with a silica content of less than approximately 80 ppm.

[0135] 40. A dissolved pulp according to Embodiment 37 or Embodiment 39, having an Fe content of approximately 10 ppm or less.

[0136] 41. A dissolved pulp according to any one of Embodiments 37, 39, or 40, having a Ca content of approximately 75 ppm or less.

[0137] 42. A dissolved pulp according to Embodiment 37 or any one of Embodiments 39 to 41, having an ash content of approximately 0.12% or less.

[0138] 43. Dissolved pulp derived from non-wood EFB, as described in Embodiment 37 or any one of Embodiments 39 to 42.

[0139] 44. Kraft pulp derived from non-wood raw materials with a silica content of less than approximately 600 ppm.

[0140] 45. Kraft pulp according to Embodiment 38 or Embodiment 44, having an ash content of approximately 0.35% or less.

[0141] 46. ​​Kraft pulp derived from non-wood EFB, as described in any one of Embodiments 38, 44, or 45.

[0142] 47. Use of dissolved pulp (DP) according to Embodiment 37 or Embodiments 39-43 in the production of cellulose fibers.

[0143] 48. Use of kraft pulp (KP) as described in Embodiment 38 or Embodiments 44-46 in the manufacture of paper.

Claims

1. A method for pre-treating non-wood empty fruit bunch (EFB) raw material, which provides a non-wood raw material suitable for steaming for the production of soluble pulp (DP) or kraft pulp (KP), (a) Washing the non-wood empty fruit cluster (EFB) raw material; (b) Contacting the washed nonwood empty fruit cluster (EFB) material with an acid solution at a temperature in the range of 80 to 100°C for a continuous period of 30 to 60 minutes; and (c) The washed non-wood empty fruit cluster (EFB) raw material is brought into contact with an alkaline solution at a temperature in the range of 80 to 100°C for a continuous period of 30 to 60 minutes. Includes, The method includes an additional cleaning step (d) between step (b) and step (c), Process (b) is performed before process (c), The aforementioned method.

2. The method according to claim 1, wherein in step (a), the non-wood empty fruit cluster (EFB) raw material is washed using water and / or steam.

3. The method according to claim 1, wherein in step (d), the non-wood empty fruit cluster (EFB) raw material is washed using water and / or steam.

4. (e) Wash the product obtained after steps (a) to (d). The method according to claim 1, further comprising:

5. A method for producing dissolved pulp (DP) from non-wood empty fruit bunches (EFB) raw materials, (i) Pre-treating the non-wood empty fruit cluster (EFB) raw material using the method described in any one of claims 1 to 4; and (ii) Steaming the pre-treated non-wood empty fruit cluster (EFB) raw material to produce DP. The method, including the method described above.

6. A method for producing kraft pulp (KP) from non-wood empty fruit bunches (EFB) raw materials, (i) Pre-treating the non-wood empty fruit cluster (EFB) raw material using the method described in any one of claims 1 to 4; and (ii) Steaming the pre-treated non-wood empty fruit cluster (EFB) raw material to produce KP. The method, including the method described above.

7. Dissolved pulp derived from non-wood empty fruit bunches (EFB) with a silica content of less than 80 ppm.

8. The dissolved pulp according to claim 7, having an Fe content of 10 ppm or less.

9. The dissolved pulp according to claim 7 or 8, having a Ca content of 75 ppm or less.

10. The dissolved pulp according to claim 7 or 8, having an ash content of 0.12% or less.

11. Kraft pulp derived from non-wood empty fruit bunches (EFB) with a silica content of less than 600 ppm.

12. The kraft pulp according to claim 11, having an ash content of 0.35% by weight or less.

13. Use of dissolved pulp (DP) according to claim 7 or 8 in the production of cellulose fibers.

14. Use of kraft pulp (KP) according to claim 11 or claim 12 in the manufacture of paper.

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