DE2620827A1 - Cellulose prodn. for newsprint mfr. from bagasse - by preliminary pith removal before storage and pulping - Google Patents

Abstract

Recovery of cellulose for newsprint mfr. from bagasse involves (a) preliminary moist removal of pith; (b) moist storage, opt. with the addn. of preservative and/or microbe cultures; (c) wet removal of pitch, opt. with addn. of chemicals, which (partly) remove the colouring matter present; (d) pulping to cellulose by the neutral sulphite process or another fibre-preserving and fibre-selective process, e.g. thermomechanical pulping; (e) completion of pulping by a mechanical hot pulping process; (f) washing, sorting and thickening and (g) opt. subjecting to a peroxide bleach. Pref. stage (b) is carried out by the Ritter process and (e) in a double disc refiner. The waste liquor form (d) is thickened or burnt and/or the chemicals it contains are recovered. The treated fibres can be used alone for newsprint mfr. Bacterial degradation during storage, irreversible cornification caused by drying, loss of whiteness and the formation of insol. colouring matter during storage are avoided. The fibres retain their strength, even on bleaching and material losses are minimised.

Description

Process for the production of newsprint

Bagasse The invention relates to a method for the production of Newsprint, in particular a method for making a for the newsprint production of suitable pulp from sugar cane bagasse.

In the course of the rising standard of living in the viable In some countries, pulp and paper production from sugar cane bagasse is particularly popular steadily gaining importance in those countries where the raw material wood is scarce or does not exist at all, and in which sugar cane waste is often the only represent vegetable raw material available in larger quantities0 at The increasing need for information of the population comes in the context of this development the possibility of producing newsprint from sugar cane bagasse, a paramount importance toO According to its use as an information carrier for mass media, low manufacturing and processing costs are the first Demands that are made of a newsprint 0 The special position this mass printing medium has led to the fact that nowadays newsprint is only can be produced economically on the largest and fastest paper machines As a starting material for the production of newsprint are almost exclusively Holziasstoff from coniferous wood used, which for the most part from the on mechanically shredded and inexpensively obtainable with high yield, but No wood pulp showing particularly high strength and to a lesser extent made of stronger, chemically digested, but more expensive wood pulp than such additive which improves the running properties on the processing machines come unbleached sulphite or bisulphite pulp as well as semi-bleached sulphate pulp in question0 Other fibrous materials, such as chemical ground or semi-pulp, are used used far less often.

Due to the scarcity of raw materials, the aim has been for the production of newsprint customary pulp, as in the case of the present Invention, to be replaced by another, this exchange is only possible, if the new fiber material has properties that affect its processing mentioned large-scale plants for the production of newsprint at the highest speeds allow, and if it results in a newsprint, which in terms of runnability (Runability) and print quality (Printability) meet the requirements of modern rotary printing machines both in letterpress and offset printing 0 The new fiber must therefore be in the highly developed framework of known processing technologies Allow to be inserted, For the assessment of the suitability of a fiber material for the production of newsprint is next to its drainability and that related to a certain drainability mechanical properties such as tear length, elongation, tear resistance and folding resistance in particular the initial wet strength a measure that the critical point of the transition the wet web between the press section and dryer section of the paper machine Other properties that can only be described in a purely qualitative manner can also be of of decisive importance for the processability of a fiber material on a high-speed one Be a paper machine, so zO Bo is not allowed to stick the still wet paper web on the pressure rollers tend0 With regard to the later properties of the newsprint the whiteness and opacity of the fiber used are important.

Usual property values for a known fiber mixture for Newsprint, which is made from about 80% white spruce wood and about 20 Softwood pulp made from spruce or pine have a grind of 30 - 400 SR in the following areas: Tear length: 3000 - 5000 m Initial wet strength: 30 to 60 g (medium) 60 "80 g (good) 80" 100 g (very good) These Among other things, property values are required in order to convert a fiber material into a up to about 10 m wide paper web at a production speed of up to 1000 m / min on a modern newsprint machine to a paper with a basis weight of about 55 g / m² to be able to process. However, describe the values given the preparation of a fiber material for its processing is by no means complete.

calculating property measurements on the finished newsprint soft, due to further additions of substances and the machine conditions, from the measured values of the raw fiber. Typical property values for newsprint are in the following ranges: Whiteness: 67 to 60% MgO (Elrepho) density: 0.5 up to 0.6 g / om tear length: 2500 to 4500 m tear propagation: 30 to 60 cmp / cm bursting strength: 1.0 to 1.5 kp / cm2 The final assessment of the suitability of newsprint for its ultimate purpose, however, it is only possible to determine the running properties on the basis of it by the printing press and based on the print result. The newspaper Printing speeds customary for letterpress printing are now between 8 and 10 m / sec paper web speed.

In particular, the work of tearing is important because the tears in the printing press, preferably due to the tearing of lateral tears sind0 Should a fiber material obtained from sugar cane bagasse for the production of newsprint are used, it must meet the specified quality characteristics.

The production of paper pulp from sugar cane bagasse has been going on since carried out commercially for several years (see Atchison "Utilization ro £ Sugar Cane Bagasse in the Pulp and Paper Industry "in Paper Trade Journal 1952) o Processes are used that are similar to those used in wood pulp production are largely analogous. Special features arise when processing bagasse among other things by the required demarking, since the in the sugar cane stalks The marrow cells contained therein are unsuitable for pulp production Fiber content of sugar cane bagasse pulp obtained according to known analogy processes is successfully used in a wide variety of paper types, but preferably bleached Cellulose processed into medium-fine and fine writing and printing papers.

Although experts are of the opinion that the morphological structure of the sugar cane stalk with suitable processing one for the manufacture of Newsprint would have to produce suitable pulp, it has not yet been possible to Commercial production of newsprint from 100% bagasse fiber (see Pulp and Paper International June 1972, p. 70).

However, ee has not lacked in numerous efforts and attempts. In Pulp and Paper International, May 1972 5. 58, Tetlow describes a process known as the Cusi process. Another procedure is below known as the Peadco-Villavicencio process (see Pulp and Paper International January 1972, pp. 41 and 42).

Both known methods represent further developments of the aforementioned Analogy process for the production of Bagaese pulps for fine papers. However, with this method that has become known, it is not yet possible to produce a raw fibrous material for newsprint paper to be produced economically, the alone is obtained from bagasse and meets all the requirements mentioned above, it is in large-scale trials, a high proportion of the pulp for newsprint, namely to essentially replace the wood pulp with a bagasse fiber material; However, the aim of all developments and of the present invention is to produce a fiber material for newsprint, which can only consist of bagasse0 This is of particular importance for most of the wood-poor developing countries, because even small amounts of softwood pulp are added to the newsprint pulp require considerable foreign exchange requirements for import, The Peadco-Villavicencio method (Tappi CA Report No. 40, 1971, pages 137 ff) consists essentially of the following Process stages: a) Bagasse storage by any known method; b) two-stage demarking, consisting of moisture demolition and wet cleaning; c) pre-hydrolysis with water at 805 atm and 1750 C; d) Using digestion at pH 8 of 1 o / o sodium silicate and 2% sodium bisulfite at 175 ° C; e) washing, sorting, Clean and drain using any known method. One bleaching stage is not scheduled. The sodium silicate added during the digestion should act as oxidizing agents. The yield should be 80, calculated on an absolutely dry basis (atro), debarked bagasse fiber.

The Cusi procedure consists of the following procedural steps: a) Bagasse storage without further details; Bagasse drying is sometimes recommended; b) demarking without further details; c) Two-stage digestion, consisting of one Impregnation stage and a boiling using mild digestion conditions; d) separation of the pulp fibers into two fractions; e) intensive mechanical treatment the fiber fraction with a lower degree of digestion and subsequent remixing with the fiber fraction of high degree of digestion; and f) intensive bleaching with 10% Sodium hypochlorite, These two methods have the following disadvantages: Both Process is a two-stage digestion used, the high investment for the Makes digestion system necessary .; the pre-hydrolysis in the Peadco process takes place under uncontrolled conditions and can be due to changing process parameters lead to different results; the oxidation claimed in the Peadco process the lignin through the sodium silicate contradicts all chemical knowledge; it is known that all large-scale trials for the production of newsprint after the Peadco procedure was unsuccessful0 The Cusi procedure initially delivers a rather dark cellulose which is subjected to intensive bleaching must, resulting in high material losses and problems in removing the chlorine-containing Brings sewage with it. Since the organic mother is predominantly in the bleaching stage is detached, it is questionable whether a chemical recovery the cooking chemicals are possible and economical by means of lye incineration; after The Cusi process achieves a pulp yield that is up to .15% below that is the subject of the present invention; both with the Cusi method and with the mechanical pulp strength achieved is insufficient in the Peadco process; the tearing length is between 3000 and 5000 m, the work of tearing only 30 to 70 cmp / cm; based on literature reviews (see Zo Bo Pulp and Paper International, January 1972, pages 41 et seq.) So far it was neither according to the Cusi method nor according to the Peadco method possible to produce newsprint from 100 Vo bagasse fiber with both processes considerable amounts of long fiber pulp had to be added.

In contrast, according to the method of the present invention Newsprint can be made from bagasse alone.

In order to be able to extract a pulp from bagasse, as the only one Fiber raw material is suitable for the production of newsprint, it is necessary to those inherent in the portions of the sugar cane stalk that are suitable for processing to preserve the most favorable properties in pulp production as completely as possible0 With the known methods, a fiber damage can neither in the preprocess nor in the The digestion process and in particular cannot be avoided in the bleaching process0 causes for a loss of quality you can start with the type of delivery of the raw bagasse and begin their storage and until the last step of bleaching z be looking for.

The bagasse is moist during delivery and storage due to their residual sugar content, which can be around 2 ffi0, a bacterial one Decomposition and thus a loss of strength of the fibers exposed. The bacterial Decomposition in wet storage can be achieved by various measures (zO B0 can be reduced by adding black liquor, adding propionic acid etcO), however, in these cases too, losses in quality and quantity have to be accepted will. But drying of the raw material also has an effect, apart from that associated costs as well as the risk of fire and dust, as a result of oxidative surface hornification detrimental to the fiber strengths that can be achieved later 0 In the event of unsuitable storage Bagasse also carries the risk that the dyes contained in the raw material be converted into certain gray-green to deep dark brown dye components, which can no longer be lightened in the subsequent cooking process. In this The trap can only be caused by an expensive bleaching process, which is usually fiber-damaging the loss of whiteness can be compensated for again before the actual fiber bloom does not have to add to the strength of the pulp and the manufacturing costs as far as possible from the mark that increases the consumption of chemicals through the use of additional chemicals Bagasse to be removed.

This is not the case with pulps for other types of paper Dimensions required. However, since the marrow cells in the raw material are partially fixed to the If fibers adhere, mechanical energy must be used to separate them0 This but can cause simultaneous mechanical damage to the fibers to be protected. It is therefore important to maintain optimal conditions for demolishing.

According to the different density across the cross-section one In sugar cane stalks, the fiber material is made up of a wide variety of cells Structure and chemical resistance0 This would prevent damage to any Avoid using different chemical pulping conditions for the different fibers Require fiber types. Such a procedure is practically impossible and technically impossible very expensive, it is therefore a matter of using a digestion process whose mild conditions are suitable for this purpose, a pulp as a mixture of components of different degrees of digestion to produce9 which in the type of a known mixture of pulp, high-yield cellulose and normal pulp, Unsuitable cooking chemicals, such as the sulphate process, can help to stabilize the dark color complexes, which then only can be removed again with a sharp, fiber-damaging bleach.

It is therefore necessary to adjust the brightness of the fiber material up to End of the pulp boil so largely to maintain or even increase that one subsequent bleaching is unnecessary or, if necessary, with such gentle bleaching Bleach chemicals can be carried out that there is no further fiber damage Thus, the most important object of this invention is to obtain a paper pulp Made of bagasse fiber, which has properties that make it suitable for use as a Make the sole fiber raw material suitable for the production of newsprint.

Another object of the invention is a method of manufacture of newsprint made from bagasse, the process steps of which are selected in such a way that that bacterial decomposition of the bagasse is avoided during storage, that the bagasse fibers do not suffer irreversible keratinization by drying that there is no loss of whiteness of the bagasse fibers and the formation of more or less insoluble 'dye components avoided during storage and digestion that the inherent strength properties of the bagasse fiber after digestion are also preserved in the bleach, and that the material losses during the whole Process of bagasse processing can be kept to a minimum.

This goal is achieved according to the invention with a method which characterized in that a) the raw bagasse is subjected to a damp pre-marking is, b) the previously demarked bagasse is stored moist, with chemicals if necessary and / or microbial cultures are added, c) the bagasse after the wet storage is fed to a wet demarking, with chemicals being added if necessary, which at least partially remove the dyes contained in the bagasse, d) the bagasse thus pretreated is subjected to a digestion through which using the neutral sulphite process (NSC process) or another fiber-friendly process and fiber-selective processes, such as thermomechanical defibration, to pulp is digested, with additional auxiliary chemicals being added if necessary, which the remaining accompanying material to the digested bagasse pulp withdraw, e) the digestion carried out in stage (d) by mechanical hot fiberization is supplemented, f) the digested bagasse pulp washed, sorted and thickened is, and g) this prepared pulp, optionally a peroxide bleach is subjected in the presence of NaOH and optionally a stabilizer.

Carrying out a pre-demarking before the bagasse is stored in humid conditions has the advantage of removing a significant portion of the park in which there is also residual sugar, which counteracts the susceptibility of the stored bagasse bacterial attack is reduced and a considerable saving in possible preservatives can also be achieved 0 Due to the increased removal of residual sugar, ground Avoid discoloration 0 Damp demarking is the first process step since the flexibility of the fibers is retained, there is hardly any damage to the fibers mechanical action With wet pre-demarking, up to 2/3 of the in of the bagasse existing marks are removed 0 A further removal in this stage of the process would require excessive mechanical processing and is therefore reserved for the subsequent two procedural stages0 For Known devices can be used for moisture demarking.

The preliminary demarking is followed by a moist storage, as a preservative organic acids and salts can optionally be used for moist storage will.

They can be added continuously or discontinuously, As additives, for example, monosodium maleate, disodium citrate or aluminum monoacetate phosphate can be used to serve.

The preservation of moist storage has proven to be particularly advantageous Bagasse proven by microbial cultures. Preservation of this kind is called Ritter method known (GB-PS 497 960, GB-PS 497 982, US-PS 2 960 444).

In this process, bacterial strains, preferably lactic acid bacteria, take over the successive formation of organic acids with simultaneous consumption of the remaining amount of sugar as a food substance, the small organisms that thrive in this climate constrict the habitat of foreign cultures that limited the targeted generation of a Acid balance would prevent. At the same time begins in the present of the organic acids, a pre-digestion of the bagasse and a breakdown of the vegetable pigments. The Ritter process thus offers protection for the bagasse against rotting, avoiding it Discoloration of the fiber, supports the detachment of the remaining pulp and initiates pre-digestion of the fiber by mild acid hydrolysis according to the invention can be a preservation by organic acids and salts with a preservation or where a pre-digestion by microbial cultures are combined0 Under certain circumstances but can also include the addition of acids or salts, or microbial cultures be waived.

The wet demarking of the bagasse following the wet storage takes place by hydraulic shear forces in aqueous suspension.

Known hydraulic pulpers can be used for this, in which an aqueous dilution of about 1: 5 to 1:10 is used0 In the wet demarking, the rest is in the manner according to the invention during the Storage of pre-loosened pulp in a gentle way from the constantly moist State of supple fiber bundles loosened.

In a particular embodiment of the method according to the invention Extractive chemicals are added during wet demarking which coloring substances contained in the fiber material are removed0 As such Chemicals come e.g. Bo soda or phosphates in question.

Neutral sulfite is preferred for the actual fiber digestion (NSSC) method using sodium sulfite and sodium carbonate was applied. Cooking can be done in discontinuous or continuous digesters known design. The ratio of cooking liquor to fumigation should, however should be kept as high as possible0 Exemplary values for a continuous Digestion in a horizontal tube digester with conveyor screws are: Use of chemicals: 14 ß Na2S03 and 4% Na2C03, based on absolutely dry, demarked bagasse; Cooking liquor concentration: 160 g / l Na2SO3 and 50 g / l Na2CO3.

Cooking conditions: 20-45 min at 170-175 ° C.

During the cooking process can extract or. dispersing effect Chemicals are added to make dyes, resins and waxes from the pulp to remove.

Polyphosphates, for example, can serve as such substances.

In addition to NSSC digestion, other digestion methods are also suitable, which have a similarly gentle effect on the fiber. Under these procedures is in particular the thermal mechanical defibration, also thermomechanical "Schliff" called, to be mentioned.

If it is necessary for economic or ecological reasons is, the inventive method with a waste liquor incineration and / or a recovery of the digestion chemicals can be combined.

Because the digestion during boiling does not go as far as complete defibering is carried out, the boiling is followed by mechanical hot defibration, preferably in a known double disc refiner.

Further processing, i.e. washing, sorting, cleaning and The unbleached pulp is thickened in a conventional manner.

Peroxide bleaching carried out with H 2 O 2 and NaOH can be used greatly increase the whiteness of the pulp without any loss of strength in the fiber. pre-condition however, the preceding process steps which avoid dye formation are required for this. The peroxide bleach also offers the advantage that it only has a slight effect Amount of organic matter dissolved from the pulp and therefore an increased waste water pollution will avoid. Since the bleaching can be done in one stage, it is also necessary limited equipment effort.

The bleaching is carried out in a medium containing 0.5-10 hydrogen peroxide (100% by weight), preferably 1-5% hydrogen peroxide based on dry cellulose contains.

The amount of NaOH to use depends on the kappa number of the unbleached one Pulp and is generally 1-5% by weight, based on dry pulp.

In the case of a pulp that contains significant amounts of heavy metal ions, such as e.g. contains copper, iron, manganese, cobalt etc., the addition of a peroxide stabilizer can be used to be required. Suitable stabilizers are, for example, sodium silicate in an amount from 1-10% by weight, preferably 1-5% by weight, based on dry pulp, or such Substances that form complexes with these heavy metal ions. Examples of this are polyaminocarboxylic acids and their alkali salts, e.g.

Ethylenediaminetetraacetic acid, diethylenetiaminepentaacetic acid, Nitrilotriacetic acid; Polyoxyearboxylic acids, e.g.

Gluconic acid, tartaric acid, citric acid and polymeric oxycarboxylic acids. Of these complex-forming substances, about 0.05 to 1% by weight are generally based on dry pulp.

Due to the process sequence according to the invention with its several process stages The goal is to be able to adapt to the special requirements of the invention achieved in an optimal manner.

Through the sequence of moisture demarking, moisture storage and The pulp does not need wet demarking until it is actually broken down to become and is therefore not exposed to harmful keratinization.

Moist pre-demarking before storage reduces the risk of bacterial attack without the demarking has to be carried out so far that the fiber material mechanically damaged in the process. The application of moist storage according to the knight's method preserves the bagasse, loosens the remaining pulp, prevents the formation of difficult to remove color complexes and leads to a gentle pre-hydrolysis of the fiber material a. In the wet demarking, the rest, e.g. through the Ritter storage, are already removed loosened pulp, fines and solubles, components harmful to the cooking process, possibly removed with the addition of suitable chemicals.

Only when using the raw material prepared in this way can the gentle and selective action of the NSSC digestion come fully into effect0 Even the self If necessary, subsequent peroxide bleaching can only be optimized in this way Effect can be increased that in all preliminary stages of the process the formation of staining substances that are difficult to remove are avoided 0 peroxide bleaching is prevented further losses in yield and fiber damage, as is the case with chlorine-hypochlorite bleaching are common, and also contributes to higher whiteness stability and one better initial wet strength.

Important economic advantages of the process according to the invention can still be seen in the fact that the process provides optimal preconditions for chemical recovery because the yield is in a range that has enough organic matter to waste liquor incineration gt antierto The problem of NSSC recovery today is as to be considered technically solved0 On the other hand, the final yield is in view of the high achievable qualities relatively high, so that a high raw material utilization is present In the following, the method according to the invention is based on an exemplary embodiment explained in detail: Embodiment The raw bagasse coming from the sugar factory with 50% moisture is demolished in a demolishing machine of the hammer mill type. The separating market share should not exceed 2/3 of the existing TWark, to avoid mechanical damage to the fiber. In a subsequent mixing unit will the previously canceled bagasse with a Ritter bacterial culture intimately mixed and stacked in the storage area. Impregnation with the Specially grown cultures will require preservation over a longer period of time (1 - 1 1/2 years) achieved.

The stored bagasse from the pile becomes a further demining stage This demarking takes place in an aqueous medium in a demarking drum The storage has resulted in a significant loosening of the cell associations of the marrow, and the marrow can be easily separated and removed without mechanical effort. In this demarking stage the oa. 70410 of the remaining brand removed. That for The material at hand is very uniform and of good quality in all respects Fiber quality. In order to get the dry content of the bagasse necessary for the cooking process Reach the bagasse in a dewatering press of excess water freed The dry content of the bagasse going to the cooker should be 30 - 35% 0.

The bagasse is fed to the continuous cooking unit Via an allocation device, in which at the same time the necessary for the cooking Chemicals are added. The digestion takes place according to the neutral sulphite process0 The required chemicals are added in an aqueous solution. The concentration is 160 g / l Na2S03 and 50 g / l Na2C03. The one required for normal digestion The amount of chemicals is 14% Na2SO3 and 4% Na2C03, based on absolutely dry Bagasse. The cooking time is 20 to 40 minutes at a temperature of 170 to 1750 C. The pH during cooking is around 9-9.5. Following the continuous During the cooking process, hot defibration takes place in a double-disc grinding unit. The food to be cooked is defibrated very gently and evenly after it has been separated the remaining cooking liquid and then Washing takes place further mechanical processing, which results in cleaning by means of sieve and centrifugal sorters The loss of rejects is due to the good starting quality of the raw material very low, approx. 2 tons of steam (12 atmospheres) are required for the boil O The yield, based on absolutely dry (atro) demarked feedstock, is 70 - 75 %.

The mechanical cleaning, which takes place in a higher dilution, This is followed by washing and dewatering, which is based on approx. 10 - 15% 0 fiber Dewatered pulp is stored in a stacking chute0 From here it takes place even deduction for a second cleaning stage (if this is necessary), and then after dehydration in a peroxide bleaching stage at higher temperature lightened.

For bleaching in high consistency (6-1L%) the chemicals used are 1.5% H202, 3 ß NaOH and 374 sodium silicate, calculated on dry cellulose.The pH value during the bleaching process is 11, the temperature depending on the bleaching speed between 50 and 700 C0 The steam requirement for bleaching is approx. 0.5 t / t atro pulp0 After bleaching, the pulp can either be fed directly to the paper mill or after dewatering on dewatering machines in arch form or after dewatering in screw presses, belt presses or vacuum filters Form or pressed into bales are fed to further processing. The pulp obtained from the process has the following strength values: Grinding time (min) 5 8 11 Grind degree (° SR) 33 42 49 Basis weight (g / m²) 81 80 80 Thickness (mm) 0.123 0.115 0.112 Volume weight (g / cm³) 0.66 0.70 0.71 Breaking load (kp) 8.7 9.7 10.3 Elongation at break (%) 3.9 4.1 4.5 Tearing length (km) 7.13 8.05 8.62 Work on tearing (cmg / cm) abs. 135 142 132 rel. 166 177 166 Bursting resistance (kp / cm²) abs. 3.8 3.30 3.59 rel. 3.78 4.11 4.50 Newsprint produced from it gives the following strength values: Comparison of the physical properties of test newsprint produced according to various methods taken from (TAPPI CA Report, No. 40, p. 137 ff) Properties of the invention Cusi1) Pedaco2) procedure Long fiber additive 0 no information 0 + 5% clay Basis weight g / cm² 52 51.3 52.0 Volume weight g / cm³ 0.61 0.57 - Burst pressure kp / cm² abs. 1.43 1.20 0.70 rel. 2.75 2.35 1.35 Tearing work cmp / cm abs. 43 36 35 rel. 83 70 67 Breaking load kp 4.33 3.82 3.0 Tear length m 5550 4950 3850 Whiteness 61 62.0 55 Opacity 92 74.5 90 1) Trial production San Cristobal 2) Trial production Paramonga

Claims (1)

Claims le method for the production of pulp from bagasse for the production of newsprint, characterized in that (a) the raw bagasse is subjected to wet pre-demarking, (b) the pre-demarked bagasse is stored moist, where appropriate preservatives and / or microbial cultures can be added, (c) the bagasse after the wet storage of a wet discharge is supplied, where appropriate chemicals are added which the in the dyes contained in the bagasse at least partially remove them, (d) the Bagasse pretreated in this way is subjected to a digestion through which it according to the neutral sulphite process (NSSC process) or another fiber-friendly and fiber-selective processes, such as thermal mechanical defibration, to pulp is digested, with additional auxiliary chemicals being added if necessary, which the remaining accompanying material to the digested bagasse pulp withdraw, (e) the digestion carried out in stage (d) by mechanical hot fiberization is supplemented, (f) the digested bagasse pulp washed, sorted and thickened and (g) this prepared pulp, optionally peroxide bleaching is subject0 2, method according to claim 1, characterized in that in Stage (g) with hydrogen peroxide with the addition of. Caustic soda, sodium silicate and, if necessary, other stabilizers is bleached. 3. The method according to claim 1 or 2, characterized in that the waste liquor from the pulp boiling in stage (d) is thickened and burned and / or the digestion chemicals contained therein are recovered. 4. The method according to any one of claims 1 to 3, characterized in that that in step (b) the preservatives are added continuously. 5. The method according to any one of claims 1 - 4, characterized in that that the Ritter method is used for step (b) of claims 1-5, characterized in that in stage (b) as a preservative organic acids or salts can be used. Method according to one of the claims 1 - 6, characterized in that the stage (e) in a double-disc refiner wird0 8. The method according to claim 2, characterized in that the Bleach is carried out in a medium containing 0.5-106 hydrogen peroxide (100% by weight), preferably t - 5 ffi hydrogen peroxide, based on dry Pulp. 9. The method according to claim 2, characterized in that the bleach with the addition of 0.5-10. preferably z - 5 wt.% NaOH, based on dry Pulp. 10. The method according to claim 2, characterized in that the bleach with the addition of 1-10% by weight sodium silicate or 0.05-1% by weight of one with Heavy metal ion complexing compound is carried out as a stabilizer.