Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
  • D21C1/02—Pretreatment of the finely-divided materials before digesting with water or steam
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
  • D21C1/04—Pretreatment of the finely-divided materials before digesting with acid reacting compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials

Definitions

• the present invention provides methods for pre-treating non-wood feedstock, in particular, empty fruit bunch (EFB) feedstock, a waste product formed after the extraction of palm oil, wherein the pre-treated non-wood feedstock is for subsequent use in producing paper or textile grade pulps for application in industries such as printing writing paper, tissue paper, paper board and fashion garments.
• EFB empty fruit bunch
• non-wood feedstocks which provide interesting replacements to wood feedstocks include oil palm empty fruit bunch (EFB) fibers, bamboo, kenaf, wheat/rice straw, coconut coil and bagasse.
• EFB oil palm empty fruit bunch
• Oil palm (elaeis guineensus ), which is typically grown in Southeast Asian countries such as Indonesia, Malyasia and Thailand, is an important source of vegetable oil, specifically palm oil.
• Various biomass is produced during the extraction of palm oil.
• One of the most abundant biomasses produced is Empty Fruit Bunches (EFB) fibers, produced by the first step in the oil extraction process wherein the fruit and nuts are stripped from the fruit bunches.
• EFB generation is increasing year on year and in 2015 alone, over 30 million tonnes was produced in Indonesia alone. This, in itself, presents an environmental issue as often this waste is simply left to rot and attract rodents.
• EFB has a number of properties which make it of interest as a raw material for pulp - it has a high cellulose fiber content and a low lignin content, it resembles hardwood fibers and can be used to provide paper and regenerated cellulose of a high quality.
• Processes are known in which EFB is used as a raw material which is then subjected to cooking in order to produce chemical pulps from which it is then possible to produce paper and regenerated cellulose, e.g. viscose, modal, lyocell and other man-made cellulose (MMC) fibers.
• MMC man-made cellulose
• pre treatment methods have included physical, chemical and biological treatments, for example, washing with water, treatment with acid, ultrasonic treatment, fungal/enzyme treatment and treatment with alkali (see Agusta et al., (2016) Journal of Japan Tappo 6, 641-49; Tye et al.
• any pre-treatment process it is necessary to balance the removal of the impurity, in this case, silica bodies, against the damage caused to the EFB feedstock by the pre-treatment process.
• the majority of these pre-treatments have been described in the context of a producing either sugar for bioethanol production, the production of furfural or the production of chemical pulps.
• the present invention is primarily concerned with processes for producing man-made cellulosic fibers (regenerated cellulose) for the textiles industry, such as viscose, which are particularly sensitive to both the presence of silica and any fiber damage incurred during earlier processing steps.
• the present inventors have identified pre-treatment processes which are effective in removing silica bodies from non-wood feedstock, while avoiding causing significant damage to the cellulosic component of the feedstock.
• the present invention provides a method for pre-treating non-wood feedstock comprising:
• the inventors have found that by carrying out the steps (a), (b), (c) and (d) this pre-treatment process results in a feedstock which contains very little silica while retaining its structural integrity and minimising damage to the cellulosic component of the feedstock.
• the inventors have surprisingly found that by combining a series of steps, each of which is carried out under conditions which are sufficiently mild to avoid unwanted structural damage, it is possible to remove effectively problematic silica bodies from the fibers of the feedstock. This is particularly surprising given the previous understanding in the industry that extreme and/or harsh conditions are required in order to remove these silica bodies.
• the pre-treatment method of the present invention can be incorporated easily into existing saw dust/pin chip mills, organosolv and soda or kraft pulp mills. It is particularly advantageous for use in an integrated pulp mill i.e a mill in which the complete process from feedstock to end product is performed, because reactants from later stages in the process can be recycled back into the pre-treatment method, in particular step (b). This improves efficiency and minimises waste.
• the present invention further provides Dissolving Pulp (DP) derived from non-wood feedstock, in particular non-wood empty fruit bunch (EFB) feedstock, which has a silica content of less than about 80 ppm.
• DP Dissolving Pulp
• EFB non-wood empty fruit bunch
• the low levels of silica present in the DP mean that it can be subsequently processed into regenerated cellulose fibers for use in the textiles industry to produce a high quality product.
• silica is still present in the DP, it will cause issues with cellulose dissolution and clog the spinnerets which are subsequently used to draw the DP into fibers.
• the present invention yet further provides Kraft Pulp (KP) derived from non-wood feedstock, in particular non-wood empty fruit bunch (EFB) feedstock, which has a silica content of less than about 600 ppm.
• KP Kraft Pulp
• EFB non-wood empty fruit bunch
• the low levels of silica present in the KP mean that it can be subsequently processed into paper products without damaging the pulping machinery used.
• silica is still present in the KP, it can lead to its deposition in the pulping machinery (i.e. sand deposits) which, as well as potentially damaging the machinery, can also lead to holes in the end product.
• the KP produced by the methods described herein does not suffer from these problems.
• the inventors have found that the DP and KP obtained from feedstock which has been pre treated according to the methods of the present invention has a quality which is equivalent to or better than that obtained using conventional wood feedstocks. It can also be obtained in a comparable yield.
• non-wood feedstock is used herein to describe any feedstock which is plant-based but which has not been derived from a wood source.
• suitable non-wood feedstock include oil palm empty fruit bunches (EFB), bamboo, bagasse, kenaf, coconut coil and wheat/rice straw.
• EFB oil palm empty fruit bunches
• bamboo bamboo
• bagasse kenaf
• coconut coil kenaf
• wheat/rice straw a feedstock which is plant-based but which has not been derived from a wood source.
• suitable non-wood feedstock include oil palm empty fruit bunches (EFB), bamboo, bagasse, kenaf, coconut coil and wheat/rice straw.
• EFB feedstock oil palm empty fruit bunches
• bamboo bagasse
• kenaf kenaf
• coconut coil kenaf
• wheat/rice straw kenaf
• the non-wood feedstock is EFB feedstock or bamboo feedstock.
• the non-wood feedstock is EFB feedstock.
• NPE Non-Process Element
• the first step in the pre-treatment process of the present invention is step (a) in which the non wood feedstock is washed.
• This washing step is included first for the purpose of removing residual oils from the non-wood feedstock. Washing may be carried out using either water and/or steam.
• washing step (a) is performed at a temperature in the range from 80°C to 100°C. Where water is used in washing step (a), at the lower end of this temperature range, it will be appreciated that a mixture of water and steam is present, while at the upper end of the temperature range, steam is present.
• the non-wood feedstock is mechanically agitated, preferably by gentle mechanical agitation, during step (a) of the method of the present invention.
• the non-wood feedstock is agitated only to a small degree, such as that which may be achieved by passing the non-wood feedstock through a screw-type conveyor.
• the non-wood feedstock may have been subjected to process steps which are standard in the industry, for example shredding.
• process steps which are standard in the industry, for example shredding.
• the non-wood feedstock is shredded, preferably the resulting fibers have a length in the range from about 5 mm to about 100mm.
• the washed non-wood feedstock is contacted with an acid solution in step (b) of the method.
• Contacting the non-wood feedstock with acid reduces the content of any residual metal impurities. In particular, it is effective in removing iron and calcium residues from the feedstock.
• this acid treatment step is also crucial in the process of removing silica from the feedstock.
• non-wood feedstock in particular EFB feedstock, has a structure in which silica bodies are embedded in the surfaces of the fibers. Contacting the fibers with acid causes the fibers to shrink, which in turn, starts a process of displacing the silica bodies.
• the acid solution comprises an acid and water. Any acid may be used to form the acid solution.
• the acid used is selected from the group consisting of sulfuric acid, hydrochloric acid, a solution of chlorine dioxide in water and mixtures thereof.
• a pulp mill typically includes a bleaching step.
• An advantage of the pre-treatment method of the present invention is that the acid used in step (b) of the pre-treatment method can be provided by acid used in a bleaching step being recycled directly into step (b) of the pre-treatment method, thus improving efficiency, minimising waste and cost production.
• the acid is included in the acid solution of step (b) at a concentration in the range from about 0.2 to 5.0%. This ensures that the acid solution is sufficiently concentrated that the fibers of the non-wood feedstock shrink to facilitate removal of silica impurities but is dilute enough that unwanted damage to the feedstock, in particular to the cellulose in the feedstock, is minimised.
• step (b) is carried out at pH in the range from 1 to 3.
• Step (b) is generally carried out at a temperature in the range from about 80°C to about 100°C.
• step (b) it is preferable to perform step (b) at an elevated temperature because it increases the speed with which step (b) proceeds and so the efficiency of the process.
• step (b) also performing step (b) at an elevated temperature (i.e. a temperature in the range from about 80 to about 100°) improves efficiencies in the overall process as it avoids the need to include a step before step (b) in which the washed non-wood feed stock is cooled.
• Step (b) is carried out for a time sufficient to achieve shrinkage of the fibers.
• step (b) has a duration in the range from about 30 to about 60 minutes.
• the extent to which step (b) has proceeded can be monitored by measuring the content of the impurities which are to be removed, specifically ash residue, NPEs and silica. At the end of step (b), typically the silica content will have reduced by a small amount, while ash residue and NPEs will have been almost completely removed. A person skilled in the art will be familiar with suitable quality measurements.
• step (c) of the method of the present invention the washed non-wood feedstock is contacted with an alkali solution.
• Contacting the feedstock with an alkali solution further assists in the removal of silica impurities. More specifically, contacting the feedstock with an alkali solution causes the fibers to swell which contributes towards removal of the silica from the feedstock.
• Step (c) is carried out after step (a) and may be performed either before or after step (b).
• step (c) is performed before step (b).
• step (c) is performed after step (b).
• step (c) is performed after step (b).
• step (c) is performed after step (b). This is advantageous because, as will be described in more detail later, after pre-treatment, the non-wood feedstock is cooked to form a pulp.
• a preferred cooking step is performed under alkaline conditions and hence, if the pre treatment method finishes with an alkaline step, it is already at a pH which is appropriate for the cooking step and thus the need for an additional neutralization step is avoided.
• steps (b) and (c) which shrink and swell the fibers of the non-wood feedstock, respectively, which leads to effective removal of silica impurities.
• the alkali solution used in step (c) comprises an alkali and water. Any alkali may be used to form the alkali solution but preferably the alkali is sodium hydroxide. Sodium hydroxide is preferred because, as described above, it is also used in the later cooking step described above directly after pre-treatment. By using the same alkali in step (c), the overall process efficiency is improved.
• the alkali is included in the alkali solution of step (c) at a concentration in the range from about 0.2 to about 5.0%. This ensures that the alkali solution is sufficiently concentrated that the fibers of the non-wood feedstock swell to facilitate removal of silica impurities but is dilute enough that unwanted damage to the feedstock, in particular cellulose in the feedstock, is minimised.
• step (c) is carried out at a pH in the range from 12 to 14.
• Step (c) is generally carried out at a temperature in the range from about 80°C to about 100°C.
• step (c) it is preferable to perform step (c) at an elevated temperature because it increases the speed with which step (b) proceeds and so the efficiency of the process.
• step (c) is performed at an elevated temperature (i.e. a temperature in the range from about 80 to about 100°) improves efficiencies in the overall process as it avoids the need to include a step before step (c) in which the washed non-wood feed stock is cooled.
• Step (c) is carried out for a time sufficient to achieve swelling of the fibers.
• step (c) has a duration in the range from about 30 to about 60 minutes.
• the extent to which step (c) has proceeded can be monitored by measuring the content of silica which remains in the feedstock. At the end of step (c), typically the silica content will have reduced significantly. A person skilled in the art will be familiar with suitable quality measurements.
• the pre-treatment method of the present invention includes a further washing step, step (d), between steps (b) and (c), irrespective of the order in which steps (b) and (c) are performed.
• This washing step is included for the primary purpose of removing metal and silica (typically fine silica) impurities which have been displaced from the non-wood fibers as a consequence of the earlier steps which have been performed.
• the washing of step (d) may be carried out using either water and/or steam.
• washing step (d) is performed at a temperature in the range from 80°C to 100°C.
• the non-wood feedstock is mechanically agitated, preferably by gentle mechanical agitation, during step (a) of the method of the present invention.
• the non-wood feedstock is agitated only to a small degree, such as that which may be achieved by passing the non-wood feedstock through a screw-type conveyor.
• the skilled person will be familiar with screw-type conveyors, an example of which is shown in Figure 11 .
• the method of the present invention may include a further washing step (e) after whichever of step (b) or step (c) is performed last.
• this additional washing step is included for the primary purpose of removing silica impurities.
• the washing of step (e) may be carried out using either water and/or steam.
• washing step (e) is performed at a temperature in the range from 80°C to 100°C.
• water is used in washing step (e)
• at the lower end of this temperature range it will be appreciated that a mixture of water and steam is present, while at the upper end of the temperature range, steam is present.
• the non-wood feedstock is mechanically agitated, preferably by gentle mechanical agitation, during step (a) of the method of the present invention.
• the non-wood feedstock is agitated only to a small degree, such as that which may be achieved by passing the non-wood feedstock through a screw-type conveyor.
• a screw-type conveyor The skilled person will be familiar with screw-type conveyors, an example of which is shown in Figure 11 .
• the non-wood feedstock is suitable for further processing to form a pulp which can then, in turn, serve as a raw material for either paper or in the production of regenerated cellulose, for example viscose, modal, lyocell or other MMC fibers.
• the methods of the present invention can be carried out using standard apparatus found in standard pulp mills with which the person skilled in the art will be familiar.
• the pre treatment method of the present invention is useful in an integrated pulp mill so that materials e.g. acid which is used in a bleaching step can be recycled into the pre-treatment methods of the present inventions.
• the non-wood feedstock may be formed into bales. Alternatively, prior to further processing, the non-wood feedstock may be pelletized.
• a person skilled in the art will be familiar with suitable methods for converting the pre-treated non-wood feedstock into pulp.
• suitable methods for cooking the feedstock specifically a sulfate (Kraft) process and a pre-hydrolysis (PH) kraft process.
• the pre-treated non-wood feedstock is mixed with a hot mixture, known as “white liquor” which comprises water, sodium hydroxide and sodium sulfite.
• white liquor which comprises water, sodium hydroxide and sodium sulfite.
• Anthraquinone may be included as an accelerant to improve yields.
• lignin present in the feedstock are broken down and dissolved in the alkali.
• the remaining solid pulp, known as “brown stock” can be collected ready to be subjected to further processing steps.
• the combined liquids (the “black liquor”) which contain lignin fragments, a small fraction of carbohydrates, sodium sulfate, sodium carbonate and other inorganic salts, can be removed and then burned to provide energy which is fed back into the cooking process.
• the “brown pulp” obtained in the Kraft process is typically bleached in order to provide a pulp which has a high brightness.
• a suitable bleaching process is Elemental Chlorine Free (ECF) bleaching in which the brown pulp is contacted sequentially with peroxymonosulfuric acid (which can be produced by mixing sulfuric acid and hydrogen peroxide), chlorine dioxide, hydrogen peroxide and chlorine dioxide.
• ECF Elemental Chlorine Free
• TCF Total Chlorine Free
• TCF typically includes four or five different stages including both treatment with chelating agent and several bleaching stages 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 that no chlorine is used and so no chlorine-containing byproducts are generated.
• the quality of the pre-treated non-wood feedstock obtained by the method of the present invention means that less energy is required in the bleaching step.
• An advantage of the pre-treatment method of the present invention is that the acid used in such a bleaching step can be recycled back into step (b) of the pre-treatment method, thus reducing the amount of acid required for the overall process and reducing waste.
• the non-wood feedstock is first subjected to a water-based auto hydrolysis process which removes hemicelluloses and some lignin. It is then cooked (kraft cooking) under alkaline conditions to remove the majority of lignin and a small fraction of remaining hemicellulose.
• Final multi-stage bleaching steps e.g. ECF bleaching or TCF bleaching
• Anthraquinone can be included as an accelerant to improve yields in a PH kraft process.
• the pre-treated non-wood feedstock obtained from the method of the present invention is cooked using a PH Kraft process.
• the quality of the pulp which is obtained can be controlled by varying several parameters, specifically the H-factor, the P-factor, the Kappa number and Active Alkali%.
• H-factor the H-factor
• P-factor the P-factor
• KP Kraft Pulp
• Dissolving Pulp (DP) is a high grade pure cellulosic pulp which has a high level of brightness, a uniform molecular weight distribution and an open pore structure, rendering it highly reactive.
• DP is typically used in the production of regenerated cellulose.
• Kraft Pulp is a pulp which contains both cellulose and hemicellulose. KP is typically used in the production of paper.
• the H-factor is a kinetic model for the rate of delignification and depends on both temperature and time.
• the P-factor depends on the time and the temperature in a water-based medium.
• the Kappa number is a measure of the completeness of the process and gives an indication of the amount of lignin which remains in the pulp; it is measured as the amount of standard potassium permanganate solution that the pulp will consume.
• the Active Alkali % is the total concentration of alkaline constituents, except carbonates, present in the reaction as determined by titration of a sample of the white liquor with strong acid according to the procedure which is set out in SCAN-N-30.
• the present invention provides DP and KP which has a very low impurity content.
• the DP and KP obtained using the pre-treatment method of the present invention meets the specifications as set out in Table 2 below.
• the low silica content of the DP obtained using the methods of the present invention is particularly surprising given the previous issues which have been encountered in attempts to remove silica from a non-wood feedstock. This is particularly the case where the non-wood feedstock is EFB feedstock.
• the present invention provides dissolving pulp derived from non-wood feedstock which has a silica content of less than about 80 ppm.
• Silica content can be determined according to the method set out in standard Tappi T 211 -om- 07.
• the dissolving pulp derived from non-wood feedstock has a Fe content of about 10ppm or less.
• Iron (Fe) content can be determined according to the method set out in standard Tappi T618- cm-01 .
• the dissolving pulp derived from non-wood feedstock has a Ca content of about 75 ppm or less.
• Calcium content can be determined according to the method set out in standard Tappi T618- cm-01 .
• the dissolving pulp derived from non-wood feedstock has an ash content of about 0.12% by weight or less.
• the ash content can be determined according to the method set out in standard Tappi T322- om-07.
• the present invention further provides kraft pulp derived from non-wood feedstock which has a silica content of less than about 600 ppm.
• the kraft pulp derived from non-wood feedstock has an ash content of about 0.35% or less.
• the present invention provides dissolving pulp derived from non-wood empty fruit bunch (EFB) which has a silica content of less than about 80 ppm.
• EFB non-wood empty fruit bunch
• the dissolving pulp derived from non-wood EFB has a Fe content of about 10ppm or less.
• the dissolving pulp derived from non-wood EFB has a Ca content of about 75 ppm or less.
• the dissolving pulp derived from non-wood EFB has an ash content of about 0.12% or less.
• the present invention further provides kraft pulp derived from non-wood empty fruit bunch (EFB) which has a silica content of less than about 600 ppm.
• the kraft pulp derived from non-wood empty fruit bunch (EFB) has an ash content of about 0.35% or less.
• the DP of the present invention has a high brightness. Brightness is a measure of the amount of incident light reflected from the pulp under specified conditions as measured by the method set out in standard Tappi T525-om-06.
• the DP of the present invention preferably has a Brightness (ISO) of about 90% or greater.
• the KP of the present invention has a high brightness. Brightness is a measure of the amount of incident light reflected from the pulp under specified conditions as measured by the method set out in standard Tappi T525-om-06.
• the KP of the present invention preferably has a Brightness (ISO) of about 90% or greater.
• the dissolving pulp obtained by the methods of the present invention may be further processed to provide regenerated cellulose.
• regenerated cellulose is used herein to describe a class of materials manufactured by the conversion of natural cellulose from a non-wood feedstock, to a soluble cellulosic derivative and subsequent regeneration, typically forming either a fiber or a film.
• a person skilled in the art will be familiar with techniques for processing dissolving pulp to form regenerated cellulose.
• a first step in this further processing is typically to convert the dissolving pulp into cellulose dope. Where the end product is viscose textile fibers, in a next step, the cellulose dope is typically subjected to a xanthation in the presence of CS2 and sodium hydroxide.
• the cellulose dope is typically subjected to a N-methylmorpholine N-oxide (NMMO) reaction.
• NMMO N-methylmorpholine N-oxide
• the product of the subsequent step can be extruded through spinnerets and regenerated to form the desired man-made fibers, e.g. viscose and/or lyocell textile fibers.
• MMC man-made cellulose
• the kraft pulp obtained by the methods of the present invention may be further processed to provide paper products.
• the person skilled in the art will be familiar with techniques for forming a paper product from pulp. In particular, processes typically involve suspending the pulp in water and then machinery to flatten, dry and cut to form sheets and rolls.
• Figure 1 is an illustration of the position of silica bodies within an EFB fiber
• Figure 2 is a block diagram illustrating a pre-treatment method of the present invention
• Figure 3(a) shows the silica content of non-wood EFB feedstock before and after the pre treatment according to the method of the present invention and as compared to prior art techniques;
• Figure 3(b) shows the silica content of non-wood bamboo feedstock before and after the pre treatment according to the method of the present invention and as compared to prior art techniques;
• Figure 4(a) shows the ash content of non-wood EFB feedstock before and after pre-treatment according to the method of the present invention and as compared to prior art techniques
• Figure 4(b) shows the ash content of non-wood bamboo feedstock before and after pre treatment according to the method of the present invention and as compared to prior art techniques
• Figure 5 shows the silica contents of a non-wood EFB feedstock and a non-wood bamboo feedstock before and after the pre-treatment methods of the present invention
• Figure 6 is an image of non-wood EFB KP produced by the method of the present invention
• Figure 7 is an image of non-wood EFB DP produced by the method of the present invention
• Figure 8 is a block diagram illustrating a process for producing paper products which includes the pre-treatment method of the present invention.
• Figures 9(a) is a block diagram illustrating a process for producing viscose which includes the pre-treatment of the present invention.
• Figure 9(b) is a block diagram illustrating a process for producing lyocell which includes the pre treatment of the present invention.
• Figure 10 shows the consumption of chlorine dioxide (CIO2) during an ECF bleaching process performed on EFB feedstock treated according to the methods of the present invention as compared to hardwoods, specifically acacia crassicarpa (ACRA), Eucalyptus pellita (EPEL), Eucalyptus hybrid (EHYB);
• ACRA acacia crassicarpa
• EPEL Eucalyptus pellita
• EHYB Eucalyptus hybrid
• Figure 11 shows a screw-type conveyor which may be used to move the non-wood feedstock from one stage to another in the method of the present invention
• Figure 12 shows the dates and times at which the feedstock was changed from a standard wood feedstock to a mixed EFB/wood feedstock in Example 3;
• Figure 13 illustrates the productivity (H-factor) of the mill where the feedstock is changed from wood chip to mixed EFB/wood chip during the trial described in Example 3;
• Figure 14 shows the oxygen charge consumed during bleaching in the mill described in Example 3
• Figure 15 shows the alkali charge consumed during bleaching in the mill described in Example 3
• Figure 16 shows the silica content of bleached kraft pulps obtained from the mixed feedstock as described in Example 3.
• Figure 17 illustrates the dirt spot/count of bleached kraft pulps obtained from the mixed feedstock as described in Example 3.
• Example 1 non-wood EFB feedstock
• EFB feedstock having a fiber length in the range from 5 to 100mm.
• the non-wood EFB feedstock was then washed using a mixture of water and steam at a temperature in the range from 80 to 100°C in a drum washer.
• the EFB feedstock was moved towards the next treatment step by screw conveyor (which provides a small degree of mechanical agitation).
• the washing step was carried out for a duration of 30 to 60 mins.
• the washed EFB feedstock was then passed to a vessel which contained-acid solution in sufficient liquor ratio (7 to 10) having a pH in the range from 1 to 3 and at a temperature in the range from 80 to 100°C.
• the EFB feedstock was removed from the acid-containing vessel and passed to a drum washer where it was washed using a mixture of water and steam at a temperature in the range from 80 to 100°C.
• the washed and acid- treated EFB feedstock was passed to a vessel which contained alkali solution in sufficient liquor ratio (7 to 10) having a pH in the range from 12 to 14 and at a temperature in the range from 80 to 100°C.
• the EFB was removed from the alkali-containing vessel and passed to a drum washer where it was washed using a mixture of water and steam at a temperature in the range from 80 to 100°C.
• the pre-treated EFB feedstock was moved toward the next step by a screw conveyor (which provides a small degree of mechanical agitation).
• the silica and ash residue contents of the pre-treated EFB feedstock were measured according to Tappi T618-cm-01 and are illustrated in Figures 3(a) and 4(b).
• the pre-treated EFB feedstock was then cooked under prehydrolysis kraft (P- factor 1000 to 1300)/kraft for both DP and KP. Active alkali was used in an amount in the range from 15 to 20% and the H factor was in the range from about 100 to 300 (see Table 1).
• the target specifications for chemical pulps (DP & KP), as set out in Table 2 were achieved.
• Example 2 non-wood bamboo feedstock
• the non-wood bamboo feedstock was then washed using a mixture of water and steam at a temperature in the range from 80 to 100°C in a drum washer.
• the bamboo feedstock was moved towards the next treatment step by a conveyor belt.
• the washing step was carried out for a duration of 30 to 60 mins.
• the washed bamboo feedstock was then passed to a vessel which contained acid solution in sufficient liquor ratio (4 to 7) having a pH in the range from 1 to 3 and at a temperature in the range from 80 to 100°C.
• the bamboo feedstock was removed from the acid-containing vessel and passed to a drum washer where it was washed using a mixture of water and steam at a temperature in the range from 80 to 100°C.
• the washed and acid-treated bamboo feedstock was passed to a vessel which contained alkali solution in sufficient liquor ratio (4 to 7) having a pH in the range from 12 to 14 and at a temperature in the range from 80 to 100°C.
• the bamboo feedstock was removed from the alkali-containing vessel and passed to a drum washer where it was washed using a mixture of water and steam at a temperature in the range from 80 to 100°C.
• the pre-treated bamboo feedstock was moved toward the next step by a conveyor belt.
• silica and ash residue contents of the pre-treated bamboo feedstock were measured according to Tappi T618-cm-01 and are illustrated in Figures 3(b) and 4(b).
• the pre-treated bamboo feedstock was then cooked under prehydrolysis kraft (P- factor 500 to 800)/ kraft for both DP and KP. Active alkali was used in an amount in the range from 15 to 20 % and the H factor was in the range from about 500 to 700.
• the target specification for chemical pulps (DP & KP), as set out in Table 2 earlier was achieved.
• Example 3 - EFB feedstock Mill trial
• Standard wood feedstock was replaced with a mixed wood feedstock comprising 5 to 10% by weight EFB feedstock in a running mill which processes 35 tonnes of feedstock per day.
• Various outputs were monitored as summarised below.
• the process to which the mixed EFB feedstock was subjected included the pre-treatment method of the present invention.
• Figure 12 illustrates the point at which the feedstock was altered to comprise 5 to 10% by weight of EFB feedstock. It is clear from Figure 13 that a higher cooking productivity (as evidenced by a lower H-factor) was observed for the same level of alkali charge and kappa number where the feed was changed to a mixed EFB feedstock. With reference to Figures 14 and 15, it is also clear that the consumption of chemicals in the bleaching step was reduced - both the oxygen and alkali charges were reduced and the total charge of CIO2 was also reduced (47.3 kg for pure wood feedstock vs. 46.2kg for mixed EFB/wood feedstock).
• the pulps obtained had the following properties:
• the end product in the mill trial described in Example 3 was a paper product. Where the feedstock was changed from pure wood to a mixture of EFB and wood and the process included the pre-treatment method of the present invention, it was surprisingly found that the end paper product had excellent properties, specifically a tensile strength of 70 Nm/g and a bulk density of 1 .39 cm 3 /g. The paper also demonstrated high performance in both drainability and runnability.
• a method for pre-treating non-wood feedstock comprising:
• step (b) is performed before step (c).
• step (c) is performed before step (b).
• step (a) the non-wood feedstock is washed using water and/or steam.
• step (a) is performed at a temperature in the range from 80 to 100°C.
• step (a) the non-wood feedstock is passed through a screw-type conveyor.
• step (b) the washed non wood feedstock is contacted with the acid solution at a temperature in the range from 80 to 100°C for a duration of 30 to 60 minutes.
• step (b) the pH is in the range from 1 to 3.
• step (b) comprises an acid selected from the group consisting of sulfuric acid, hydrochloric acid, a solution of chlorine dioxide in water and mixtures thereof.
• step (b) comprises acid at a concentration of about 0.2 to about 5%.
• step (b) comprises an acid solution which has been recycled from a step in which dissolving pulp (DP) and/or kraft pulp (KP) has been bleached.
• DP dissolving pulp
• KP kraft pulp
• step (b) the acid solution comprises recycled acid at a concentration of about 0.2 to about 5%.
• step (d) the non-wood feedstock is washed using water and/or steam.
• step (d) is performed at a temperature in the range from 80 to 100°C.
• step (d) the non-wood feedstock is passed through a screw-type conveyor.
• step (c) the washed non wood feedstock is contacted with the alkali solution at a temperature in the range from 80 to 100°C for a duration of 30 to 60 minutes.
• step (c) the pH is in the range from 12 to 14.
• step (c) the alkali solution comprises sodium hydroxide.
• step (c) the alkali solution comprises sodium hydroxide at a concentration of about 0.2 to about 5%.
• step (e) A method according to embodiment 20, wherein in step (e), the product is washed with water and/or steam. 22. A method according to embodiment 20 or embodiment 21 , wherein step (e) is performed at a temperature in the range from 80 to 100°C.
• step (e) the non wood feedstock is passed through a screw-type conveyor.
• non-wood feedstock is non-wood empty fruit bunch (EFB).
• EFB non-wood empty fruit bunch
• a method for producing dissolving pulp (DP) from non-wood feedstock comprising:
• a method for producing kraft pulp (KP) from non-wood feedstock comprising:
• ECF Elemental Chlorine Free
• a method according to embodiment 30, wherein the bleaching step comprises:
• TCF Total Chlorine Free
• regenerated cellulose is selected from the group consisting of viscose fibers, modal fibers, lyocell and MCC fibers.
• Kraft pulp obtainable by the method as defined in any one of embodiments 26, 27 or 29 to 33.
• Kraft pulp derived from non-wood feedstock which has a silica content of less than about 600 ppm.
• Kraft pulp according to embodiment 38 or 44 which has an ash content of about 0.35% or less.

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• 2022
  • 2022-05-03 WO PCT/SG2022/050268 patent/WO2022235212A1/en active Application Filing
  • 2022-05-03 EP EP22722911.9A patent/EP4334525A1/de active Pending
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