Method for production of mechanical wood pulp suitable for manufacturing of paper or cardboard

FIELD: textile, paper.

SUBSTANCE: method relates to production of mechanical or chemical-mechanical wood pulp applied as raw material for manufacturing of paper or cardboard, and may be used and pulp and paper industry. According to this method wood pulp is exposed to fibrillation. Produced wood pulp is screened to separate wastes from acceptable materials. At the same time wastes are removed in amount of maximum 60% of overall amount of wood pulp. Wastes and acceptable material are bleached separately. Wastes are bleached with the help of peroxide or peroxy acid. After that bleached wastes are mixed with bleached acceptable material. After combination they are exposed to finishing grinding, at the same time amount of consumed energy makes approximately 10-1000 kW-hr/ton. Finishing grinding is carried out at low concentration. Then wood pulp is batched into paper- or cardboard-making machine. Wastes are bleached in alkaline medium.

EFFECT: improved strength of wood pulp and reduction of energy consumed for grinding.

12 cl, 1 dwg, 1 ex

 

In the present invention according to the preamble of claim 1 of the formula of the invention, a method of obtaining mechanical wood pulp for making paper or paperboard.

According to the proposed method specified wood pulp fibrillary using methods known in the art, and bleach the resulting mass in an alkaline environment.

The use of mechanical pulp made from pulpwood, in particular wood pulp, was the first method of manufacturing paper from wood. Wood pulp was received on drivesnapshot plant with application of crushing stone. Industrial production of this type of wood pulp began in Germany, probably in 1844, However, subsequently to defibrillatory used two sets of rotating knives.

Both methods are used at present time. However, the traditional method of obtaining mechanical wood pulp was modified by including in the processing pressure in order to recover at least part of the energy consumed in grinding wood pulp or definiowanie conducted with predominantly high temperature. At the same time, the increased pressure reduces the consumption of mechanical energy, because the fibre is better distinguished from Dreux is ezine at high temperature. Mechanical wood pulp used for paper manufacturing, bleach. Originally bleaching was performed using compounds of chlorine and sulphur compounds. Subsequently used in new types of bleaching compounds, such as hydrogen peroxide and organic peroxyacids, such as nagarajuna acid and peracetic acid, as suggested, for example, in the description of the patent US 4,793,898.

According to the patent publication FI 68685 bleaching mechanical wood pulp can be carried out using hydrogen peroxide concentration of from 0.2 to 3.0% in the first stage and using organic nagkalat with a concentration of from 0.1 to 5.0% in the second stage. Percent concentration calculated from the dry mass of wood that need to be processed.

In the description of the patent US 4,793,898 proposed bleaching wood pulp with peroxide in conjunction with acetic acid or formic acid, and the amount of peroxide is 20% relative to the weight of dry wood chips. In this case, when the bleaching of birch wood pulp can be obtained permanganate number equal to 20. It is known that the addition of the bleaching solution a small amount, usually salts of Mg or DTPA DTPA (diethylenetriaminepentaacetate) prevents samorost the aspects of the peroxide decomposition.

In the description of the patent US 5,039,377 method, based on the whitening peroxide, according to which use sodium silicate together with a carbonate or bicarbonate of an alkali metal. Sodium silicate is used in the insoluble form, the sodium silicate may be replaced by other silicon-containing compounds capable of ion exchange, such as synthetic zeolites. In this case, the purpose of silicate materials is to prevent premature decomposition of the peroxide caused by heavy metals.

In the description of the patent US 6,743,332 described multi-stage thermomechanical process to obtain wood pulp, in which the wood pulp is bleached using hydrogen peroxide solution and Mg(OH)2and Na2CO3while the fiber suspension is kept in the above solution after the second stage refining at a temperature of from 185 to 160C for from 2 to 180 minutes Recommended amount of peroxide is from 5 to 100 kg per ton of dry pulp.

In addition, in the description of the patent US 4,731,160 recommended to bleach wood pulp with peroxide in the following manner: after the pulping wood pulp separated into two fractions, which include fine fraction and, accordingly, the primary coat is July. Fine fraction bleach separately, as in the case when these two factions bleach together, deteriorating assaileth main faction and because of poor assaumece to whiten teeth this fraction by conventional filtration whitening (bleaching method of displacement) is impossible. The fine fraction is bleached by applying the method according to Fig 1 in the description of the patent, according to which the peroxide solution is injected into the filtered water produced at the last stage. This water is recycled back to the wood mass obtained after extraction in the first stage. The reaction of the bleaching is conducted mainly in conventional bleaching tower.

The present invention is to eliminate the disadvantages inherent in the known technology, and the creation of new convenient from the point of view of industrial production, processing method and bleaching mechanical wood pulp used to manufacture fiber cloths such as cardboard and mainly paper.

According to the present invention, the development and implementation of the method on an industrial scale have been fully implemented in a new way. Under this method of whitening is subjected in particular waste fraction which is separated in the course of sifting wood pulp. Fibers of this fra is of wood pulp are usually rough, that is their flexibility is low and they are difficult to fibrillating. Laboratory sheet, made of wood pulp fraction of this type, has a low density. In addition, its strength is usually low, and the opacity is low due to the small amount of fine particles in the sheet. On the other hand, the sheet surface is very rough.

According to the present invention the wood pulp produced after fibrillatory, sifted to separate waste from acceptable material, while the percentage of separated waste is a maximum of about 60% of the total amount of wood pulp. After that waste bleach separately from acceptable material waste and bleached again mixed with acceptable material.

This method is suitable for the production of mechanical or chemical-mechanical wood pulp, mainly for the production of chemi-thermomechanical pulp (CTMP) and in particular for the production of paper pulp from hardwood or paper pulp, which contains fibers obtained from deciduous trees.

In particular, the solution according to the present invention is characterized by the features set forth in the characterizing part of claim 1 of the claims.

This method provides advantages is that as for bleaching wood pulp and, in particular, to increase strength. At the same time saves a significant amount of energy spent on grinding. Increasing the strength and reducing the energy consumed in grinding is observed when grinding waste, and finishing grinding of finished mechanical wood pulp. Particularly unexpected is the predominant increase in strength achieved at the stage of finishing grinding.

From the literature it is known that the use of alkali effect on the increase of strength and energy consumption in the bleaching of waste. In this regard, made references to the following article Strunk, W. and co-authors: "High-Alkalinity Peroxide Treatment of Groundwood Screen Rejects", ABTCP Congr. Annual Celulose Papel 22nd (Sao Paulo), 511-533, "Treating Groundwood Screen Rejects with Alkaline Peroxide Ups Pulp Value", Pulp Paper 63, No. 11: 99-105, 1989 and "High-Strength Softwood Rejects by Bleaching with Peroxide before Refining", Tappi Ann. Mtg. (Atlanta) Proc: 49-61, 1988.

However, in the known solutions uses large amounts of alkali. In the present invention, on the contrary, unexpectedly found that the use of even small amounts of alkali is saving energy and, thus, what is particularly interesting, is provided the above-mentioned advantage when finishing grinding. Almost in the present invention, the consumption of alkali according to the proposed method does not significantly increased because of the use the of alkali at bleaching waste reduces the amount of alkali, needed elsewhere, especially when bleaching in high concentrations.

Further the present invention is discussed in more detail with the help of detailed explanations and the accompanying drawing, which shows a simplified flow chart of the process according to the present invention (i.e. waste management).

In the method according to the present invention the source of woody material is subjected to defibrillating using known mechanical or chemical-mechanical methods to obtain source material for paper or paperboard. In the method according to the present invention the source of woody material is subjected to defibrillating using known mechanical or chemical-mechanical methods, with the aim of obtaining an acceptable source material, suitable for the production of paper or cardboard. As the wood material can be used wood chips or pulp wood. Received fibrillated wood pulp is bleached in alkaline conditions. However, wood pulp, coming after fibrillatory, first refer to the stage of screening, where it is divided at least into two parts, namely: acceptable material which is sent forth to the stage of bleaching, waste that will be processed in accordance with the present and the attainment. The percentage of separated waste is a maximum of about 60%, preferably a maximum of about 40% of the total amount of wood pulp. However, as a rule, the proportion of disposed wastes is at least 5%, mainly at least about 10%. Waste bleach separately from acceptable material, and then bleached waste mixed with acceptable material.

It should be noted that although in the following explanation aspen is mentioned in the text in several places as a starting material for chemical-mechanical wood pulp, the present invention can also be applied to other wood of the poplar family. In General, for use in the present invention are suitable, among others, the following wood species: poplar trembling (.Tremula), poplar ominously (.Tremuloides), P. balsamea, balsam poplar (.Balsamifera), poplar volatitlity (.Trichocarpa), poplar heterophyllous (.Heterophylla), poplar deltoid (.deltoides) and poplar krupnozubchatye (.grandidentata). Along with various species of poplar especially preferred for the production of chemical mechanical wood pulp are aspen (European aspen, .tremula; poplar ominously. .tremuloides), varieties of aspen, obtained by crossing different species of aspen, the so-called hybrid aspen (for example .tremula tremuloides, .tremula is tremula, .deltoides trichocarpa, .trichocarpa deltoides, P.deltoides nigra, P.maximowiczii trichocarpa) and other varieties, genetically engineered, fiber properties and optical properties which are acceptable for use in the present invention.

Preferably using chemical-mechanical wood pulp with an acceptable distribution of fibers at least 30%, more acceptable, at least 50%, and preferably at least 70% of which is derived from aspen and hybrid aspen or poplar. According to a more preferred implementation variant in the present invention using chemical-thermo-mechanical wood pulp obtained from aspen. At least 20 wt.%. fibers of this wood pulp is included in the fiber fraction with a particle size of <200 mesh. The most acceptable is the use of wood pulp from CTMP aspen, when from 20 to 40 wt.%, preferably from about 25 to 35 wt.% fibers of this wood pulp is included in the fiber fraction with a particle size 28/48 mesh and from 20 to 40 wt.%, preferably from about 25 to 35 wt.%, included in the fiber fraction with a particle size of <200 mesh.

In this case, the numbers 28/48 denote the fraction of fiber, which passes through the wire grid with density weave 28 holes per inch (mesh), but which does not pass through the mesh density weave 48 mesh. This faction with the contains fiber, which give a paper layer, an acceptable bulk and stiffness. Fraction comprising fibers of such size that they pass through the frequent mesh (<200 mesh), provides, in turn, high surface smoothness.

This pulp can be obtained using well-known chemical-mechanical method, which involves several stages of grinding, for example, two stages, with subsequent screening of waste and milling waste. The required distribution of the size of the fibers is achieved by adjusting the interaction data phase.

The above description of the size distribution of the fiber generally refers to wood mass, used for making paper with a weight below 150 g/m2preferably below 100 g/m2(for example, from about 30 to 90 g/m2). The size distribution of the fibers is preferably other paper and paperboard with higher dosing.

In the present invention under the production of chemi-mechanical wood pulp understand the process comprising two stages, namely the stage of the chemical pulping stage and mechanical pulping. Chemical-mechanical methods are CTMP (chemi-thermomechanical) and HMM (chemical and mechanical) methods of pulping. According to the HMM method, the original wood material machining is Laut grinding at normal pressure, whereas according to the CTMP method of mechanical wood pulp receive refiner under pressure. The output HMM method is usually smaller than the output CTMP method (less than 90%). The reason is that in the HMM method, the dosage of the reagents above. In both cases, chemical treatment of wood has traditionally carried out using sodium sulfite (sulfate process), in which deciduous wood can also be treated with sodium hydroxide. In this case, the average dosage of reagents according to the method of CTMP is from about 0 to 4 wt.% sodium sulfite and from 0.1 to 7.0 wt.% sodium hydroxide at a temperature of from about 60 to 120C. According to the HMM method, the dosage of the reagents is from 10 to 15 wt.% sodium sulfite and/or from 4 to 8 wt.% sodium hydroxide (dose calculated with respect to the dry wood or dry wood mass), and the temperature is from 130 to 160C and correspondingly from 50 to 100C.

In chemical-mechanical method, wood chips can also be impregnated with an alkaline peroxide solution (the APMP - alkaline peroxide mechanical pulp - peroxide-alkaline obtaining mechanical wood pulp). Dosage peroxide is usually from 0.1 to 10.0% (based on dry wood weight, kg/tonne of air-dried material kg/t VVM (kg/adt - kg/air-dried tonne)), usually from about 0.5 to 5.0 wt.%. Alkali, for example sodium hydroxide, add recipients who are in the same quantity, that is, from about 0.1 to 10.0 wt.%.

The source material in CTMP method can include only aspen or some other kinds of wood of the poplar family. However, other types of wood, such as hardwood, such as birch, eucalyptus and mixed tropical hardwood or coniferous wood such as spruce or pine, can also be used in this way. According to one implementation options of the use of chemical mechanical wood pulp, which contains at least 5% softwood fibers. In the present invention may use, for example, chemical-mechanical wood pulp, which contains from 70 to 100% of aspen fiber, and from 0 to 30% fiber softwood. The latter can be obtained from one or more species of coniferous wood.

Bulk, strength and stiffness of wood pulp can be increased by adding coniferous wood fibers, especially of spruce fibres. However, the bulk and stiffness of a wood pulp containing only aspen or similar source material, also can be affected by adjusting process parameters CTMP.

Mechanical methods of pulping, i.e. ways of fibrillatory represent the traditional method of obtaining mechanical wood pulp and perfect the p method of obtaining mechanical pulp (groundwood pulp (DDM) and thermomechanical pulp (TMP)), and their modified versions.

Waste treatment can be performed in two ways: waste or beginning of bleach, and then grind their subsequent mixing with acceptable material that constitutes the main part of wood pulp, or, alternatively, waste ground before bleaching. Preferably, the grinding is carried out after bleaching, in this case, saving a large amount of energy required for grinding. In both cases, from 20 to 60%, preferably from 20 to 40% wood pulp is separated as waste after fibrillatory and sifting.

Peroxide or nagkalat used as bleaching reagents as in the bleaching of waste, and at bleaching acceptable material with the waste. Among nagkalat should mention lower alcamovia peroxyacids, especially naturalyou acid, peracetic acid and nadrejenemu acid, and nadseroy acid (acid Caro) and mixtures thereof.

Peracetic acid, which is the most suitable alanovoy peroxyketal, produced by interaction of acetic acid with hydrogen peroxide when a molar ratio of 1:1-1:2 using a small amount of sulfuric acid as a catalyst. Peracetic acid is used either in pure form or as an intermediate connection is in or in distilled form. Typical conditions at the stage of processing with the use of peracetic acid are as follows: dosage peracetic acid from 2 to 40 kg/t dry matter (kg/t ASV) (kg/BDt - kg/bone dry tonne), pH 3 to 8, a temperature of from 50 to 90C and the duration of reaction from 30 minutes to 6 hours If necessary at the stage of processing nagkalat can be used additives, such as magnesium sulfate and/or chelating agent such as EDTA or DTPA, in the amount of from about 0.5 to 3.0 kg/t ASV More preferable conditions that are required in the processing phase, peracetic acid, are as follows: pH from 4.5 to 7, the duration of reaction from 30 to 180 min and a temperature of from 50 to 80C.

Peroxide bleaching, in turn, is carried out using hydrogen peroxide or sodium peroxide. As a rule, in order to stabilize the peroxide for the bleaching solution add sodium silicate and magnesium sulfate. Bleaching is carried out in an alkaline medium, and the pH typically ranges from about 9 to 12 at the initial stage of bleaching. The amount of peroxide is usually from about 0.5 to 10.0%, with even number of 1 to 3% gives good results when whitening. The concentration of the pulp is from about 5 to 40%, and the time when the bleaching is, depending on temperature and concentration, from about 0.1 to 20.0 hours, usually PR is approximately from 0.5 to 4.0 h at a concentration of from 5 to 40%. Peroxide bleaching can increase the degree of whiteness of the pulp according to ISO about 15-20 percentage units.

For bleaching waste alkali, particularly the alkali metal hydroxide, such as sodium hydroxide, dispense the same amount as the peroxide, usually alkali content of approximately from 0.5 to 1.0, preferably from 0.6 to 0.8, the percentage of peroxide. The dosage of alkali used for bleaching, is approximately from 0.2 to 3.0% by weight of the dry pulp. The most suitable dosage of alkali is a maximum of 2.0%, mainly from about 0.1 to 1.5%. Since in the present invention, the total alkali consumption compared with the traditional way is essentially at the same level, usually for bleaching waste use at least 10%but not more than about half of the alkali used in the process of bleaching, mainly, from about 20 to 45 wt.% from the total amount of alkali for bleaching wood pulp.

Waste that bleach separately before mixing with acceptable material is subjected to a finishing grinding. From the point of view of specific consumption of energy, from 15 to 30% of the energy required for grinding is used to grind waste.

After the separate processing of the main part of wood pulp, i.e. acceptable material, and the waste is again unite and usually bleached and washed together. United wood pulp is subjected to bleaching before the specified end of white, as described above, with the use of peroxide or peroxyacids. CTMP way, in particular, involves crushing the dried wood pulp in bales before sending it to the paper or cardboard factory. To optimize production taking into account unforeseen changes that occur when the bleaching waste, finishing grinding is subjected to mixed wood pulp (acceptable material + waste), while energy consumption for grinding range from 10 to 1000 kWh/ton, preferably from 10 to 400 kWh/T. In principle, this finishing grinding may be conducted at any stage after the unification of acceptable material and waste; thus finishing the grinding may be carried out using any method of grinding at high concentration, or method of grinding at low concentration, although by far the most commonly used grinding at low concentration. It is most preferable to carry out finishing grinding, such as the above-mentioned grinding at low concentration, before loading wood pulp in paper or Board machine.

Mixed wood pulp is bleached as described above, to the desired degree of whiteness using peroxide or peroxyacids in an alkaline environment. Under this and the finding at bleaching in high concentration dosage of alkali may be less than the dosage according to the traditional way. Usually the dosage of alkali is from 0.5 to 1.5%. Dosage of peroxide can also be reduced, while the upper limit of dosage may be about 3% (typically from 1.0 to 3.0%).

The total consumption of alkali according to the method (impregnation + whitening in terms of average concentration + treatment/bleaching waste) is about 2 to 4% relative to the tree mass (kg/t VVM), mainly maximum of about 3.5%.

Based on the above, the proposed method is described using the following example of a flowchart of the process. The main stages of the process are processing wood chips, treatment, grinding, screening, waste treatment, bleaching and washing.

In the block diagram of the process position under the numbers 1-12 refer to the following stages of the process and containers:

1. The grinding

2. The capacity to remove latent moisture

3. The primary stage screening

4. Secondary stage screening

5. Waste containers

6. Thickening waste

7. Centrifuge waste

8. Bleaching waste

9. Refining waste

10. Capacity for ground waste

11. Screening waste

12. Centrifugation

A. Processing wood chips

Aspen and some species of spruce are used as starting material in the process of obtaining chemical-mechanical d is evennou mass (STMR - bleached chemi-thermomechanical pulp - bleached chemi-thermomechanical pulp). Spruce wood chips are delivered to the plant in the form of finished chips. Aspen akarat on koreandrama plant with the method of dry debarking. Debarked logs are crushed and sieved chips. The chips are stored in four closed bins for storage of chips.

The chips are first heated in the tank for chips, then stones, sand and other impurities wash away the circulating water. Wash water is separated from the chips in the auger separator.

B. Impregnation

The washed chips are heated by steam in the auger-feeder, which is under pressure. After that, the chips are subjected to strong compression and then give it to swell to increase the absorption of the reactants.

Wrasman

The impregnated chips are sent to one - or two-stage refining process under pressure. After grinding wood pulp is sent to the vessel to remove latent moisture.

G. Screening

After mechanical pulping wood pulp still contains not fully defibrinirovanna fragments and splinters. Separate them from the pulp during the multistage process of sifting and then sent to the stage of waste treatment.

D. waste management

Waste management is shown in figure 1. The impregnated chips are sent to stage grinding 1, after which the wood pulp is pumped to the stage is to remove latent moisture 2. Next, the wood pulp at a concentration of from 1.4 to 1.8% is pumped to the 3 primary screening stage (P-stage), where the flow of acceptable material serves a pump of a disc filter. Waste with P-stage 3 always pumped in accordance with the type of processed wood or screening 4 secondary phase (In-phase)or in waste containers 5. The volumetric ratio of waste on the U-phase is determined by the type of processed wood and state of the process and is in the range from 25 to 40%. Acceptable material with In-phase sifting served in the flow of wood pulp, going on a disk filter, and the waste from the In-phase screening serves 4 pump waste containers 5. On the In-phase volumetric ratio of waste varies from 47 to 57% depending on the process state.

For thickening pulp from waste containers, wood pulp is pumped to the stage 6 thickening of waste that can be done, for example, on the sieve. Before bleaching waste wood pulp is washed with water and remove water from it using waste compactors 7. After presses for waste wood pulp at a concentration of from 28 to 38% is directed through the mixer reagents in the tower 8 for bleaching waste. In a mixer add reagents reagents for bleaching, alkali and peroxide and/or peroxidase.

After bleaching revenue mass is subjected to grinding on stage 9 of the grinding waste. From stage 9 of the grinding waste wood pulp is directed into the container 10 for the waste ground, where wood pulp is pumped to the stage of sifting waste 11. Acceptable material after sieving waste sent to the same thread as acceptable material after sieving 3 P-stage, and waste sent to centrifugation 12. When sifting waste bulk waste ratio is from 20 to 35% depending on the type of processed wood. Acceptable material after centrifugation 12 is pumped into waste containers 5, after which they again undergo a complete cycle of processing waste. Waste after centrifugation 12 is removed from the process. Waste after separation of waste (from 30 to 60% of the flow of wood pulp) newly admitted to waste containers 5, after which they again undergo a complete cycle of processing waste.

That is, Bleaching and washing

Wood pulp is washed by dilution of its circulating water, which is cleaner, and push-UPS on screw presses on the first stage of leaching. During the two-stage bleaching process, in addition to the bleaching of waste, carry out the bleaching of wood pulp with peroxide. The first whitening carried out at a concentration of about 12% (whitening at an average concentration), and the second whitening - at a concentration of about 30% (whitening prirodna concentration). Between bleaching stages has a second stage leaching is carried out on the double wire presses. The application of chemicals is optimized, because the bleaching in terms of the average concentration of hydrogen peroxide usually do not add. Instead, the flushing is performed with the use of wash water from the second stage of bleaching, containing residual peroxide.

For bleaching should three-stage washing process. This washing is carried out in countercurrent mode, i.e. the washing water act and subsequent leaching. After the fourth stage of leaching wood pulp is diluted with pure condensate formed during the evaporation, to the state average concentrations and sent to the storage pool.

J. Drying and packing in bales of wood pulp

Pressed wood pulp sent from the basin for storage on two lines Aeropostale drying, which comprises two stages. Wood pulp is subjected to flocculating and then served in a stream of hot air. After that, the wood pulp is sent through the airflow in the cooling cyclone, where the dried wood pulp, in turn, is directed to devices for forming bales.

During the above process were obtained the results shown in the following example. It should be noted that the properties of wood change who I am depending on the time of year, geographical area, how do the trees, and latitude. It is obvious to a person skilled in this field. Therefore, it is necessary to take into account when analyzing the table below, despite the fact that the two full-scale experimental batch consisted of trees, the felling area, which were located as closely as possible to each other and were as close as possible.

The volumetric amount of waste at
time 26.9.200419.10.2004
Obtaining wood pulp:
Impregnation
NaOH, kg/t VVM22
Oxidized green liquor, kg/t VVM66
DTPA, kg/t VVM0.60.8
Grinding: line 1 SRE MW/t VVM 1.591.66
line 21.771.64
Screening:
DTPA in the capacity to remove
hidden moisture, kg/t VVM0.60.8
Waste%vol.3538
(at a volume ratio equal to 35%, the ratio of waste to wood weight ranges from 40 to 45% depending on the concentration at the inlet and the feed stream)
Whitening with a median concentration of
NaOH, kg/t VVM11
Bleaching at high concentration
H2O2kg/t VVM3728
NaOH1912
MgSO42,51
Waste management:
H2O2kg/t VVM012
NaOH012
MgSO400,03
Separate grinding of waste
RJ 1 MWh/t VVM0,640,29
RJ 2 MWh/t VVM0,680,39
the screening waste3528
The total amount of NaOH, kg/t VVM2732
Properties measured during the test sheet made from wood pulp obtained:
Sagasti*
(CFS - Canadian Standard Freeness), ml10100
Bulk, cm3/g2.001.86
Benzene, ml/min435254
Resistance, tensile strength, Nm/g31.238.3
Hardness tensile kNm/g4.17 5.08
The rate of strain energy, j/g0.310.43
Energy relations fibers
by Scott bond, j/m2177188
White ISO %83.281.5
Opacity, %81.780.8
The properties sheet, made from wood pulp subjected to finishing the grinding refiner low consistency with specific energy consumption of 60 kWh/t VVM (refiner is a laboratory conical refiner "Voith-Sulzer")
Sagasti*
(CFS - Canadian Standard Freeness), ml8470
Bulk, cm /g1.841.72
Benzene, ml/min246106
Resistance, tensile strength, Nm/g37.046.2
The rate of strain energy, j/g0.410.56
Energy relations fibers
by Scott bond, j/m2215252
White ISO %82.981.4
Opacity, %81.780.4
(*) indicates that other typical properties were so close to each other that they are not worth mentioning in comparison.

The comparison shows that the smoothness on Bentsen test sheets, projectors, is prepared from the resulting pulp, especially from wood pulp subjected to finishing grinding, and stretch resistance and energy ties fibers were significantly improved. In General, it can be noted that the properties of wood treated by the method according to the present invention, have been improved by using a non-obvious way at the stage of finishing grinding when compared from the point of view of energy consumption, at the stage of finishing grinding. At the same time the amount of energy expended when grinding waste during the production of wood pulp by a known method, is reduced by about half. One of the features that may not be shown in the course of this comparison, it is obvious to experts in this field, is that the amount of waste may vary due to natural causes. Therefore, if changes occur in the way described above, the quality of wood pulp and, thus, the quality of the final paper is significantly improved and the differences in quality are aligned.

In the above example used a wood mixture containing 85% aspen and 15% spruce.

A similar method is also suitable for the production of refined mechanical pulp, wood pulp or chemical-mechanical refined wood pulp from spruce or processing, carried out under pressure.

This example also shows that the total consumption of alkali according to the present invention is essentially remains the same. In this example according to the present invention, the average is 3.2% (kg/t VVM), while the amount of alkali used in the traditional way, is 2.7% (kg/t VVM).

1. Method for the production of mechanical or chemical-mechanical wood pulp used as raw material for paper or paperboard according to which the wood pulp is subjected to fibrillating, the original material is wood chips or wood, and fibrillated wood pulp is bleached in alkaline medium, characterized in that after fibrillatory wood pulp is screened to separate the waste from the acceptable materiala, as waste is separated to a maximum of 60% of total wood pulp, waste bleach separately from acceptable material, and then bleached waste mixed with acceptable material.

2. The method according to claim 1, characterized in that the waste is subjected to grinding before mixing with acceptable material, which forms the main part of the wood pulp.

3. The method according to claim 1, characterized in that the waste is subjected to grinding before bleaching.

4. The method according to claims 1 to 3, characterized in that from about 20 to 40% wood pulp is separated in the waste when asked after fibrillatory and sifting.

5. The method according to claims 1 to 3, characterized in that the waste is bleached with peroxide or percolate.

6. The method according to any one of claims 1 to 3, characterized in that bleached waste separately separately subjected to grinding before mixing with acceptable material.

7. The method according to claim 6, characterized in that from the point of view of specific energy consumption from 15 to 30% of the electricity required for grinding is used to grind waste.

8. The method according to any one of claims 1 to 3 or 7, characterized in that the main part of the wood pulp and waste unite after their separate handle and put together finishing grinding, the number of expended energy is about 10 to 1000 kW-h/t, mainly from 10 to 400 kWh/so

9. The method according to claim 8, characterized in that the finishing grinding is a grinding at low concentration.

10. The method of claim 8, wherein the wood pulp after finishing grinding is metered into the paper or Board machine.

11. The method according to any one of claims 1 to 3, 7, 9 or 10, characterized in that the waste is bleached in alkaline medium, the number used for the bleaching of alkali is from 10 to 50 wt.%, mainly, from about 20 to 45 wt.% in relation to the total number of wood pulp, which should be subjected to bleaching.

12. The method according to lubas claims 1 to 3, 7, 9 or 10, characterized in that the total consumption of alkali, according to this method, approximately 2 to 4% relative to the amount of wood mass (kg/t VVM), mainly maximum of about 3.5%.



 

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2 cl, 1 tbl

FIELD: textile, paper.

SUBSTANCE: method is referred to bleached wood pulp production from hardwood chips for their further use in different compositions for paper and cardboard production. Chipped wood is impregnated with alkali solution of sodium sulfite. Spent impregnating solution is then removed. Chipped wood is milled in two stages. In between components are treated by alkali solution of hydrogen peroxide at weight concentration 14-18% and final pH=9.5-10.0. Following the second stage of milling, pulp is dissolved to concentration 3.0-5.0% and cured during 30-60 minutes to pH=7.5-8.0. Pulp is chemically treated by alkali solution of hydrogen peroxide between milling stages at 75-85°C during 15-20 minutes.

EFFECT: decrease of chemicals consumption for impregnation and improvement of mechanical and optical properties of target product.

2 cl, 1 tbl, 4 ex

FIELD: paper-and-pulp industry.

SUBSTANCE: cellulose delignification process comprises alkali treatment, delignification with hydrogen peroxide with sodium hydroxide and sodium silicate additive, and acid treatment. Alkali treatment consumes 0.5% hydrogen peroxide and 2.0% sodium hydroxide based on the weight of absolutely dry cellulose and is conducted for 2.0-2.5 h at 60-90°C. Acid treatment of delignified product is accomplished with aqueous hydrochloric acid, which is consumed in amount 1.0% based on the weight of absolutely dry fibers, while treatment is conducted for 30-60 min at ambient temperature.

EFFECT: enhanced economical efficiency without loss cellulose characteristics.

2 tbl, 11 ex

FIELD: pulp-and-paper industry.

SUBSTANCE: unbleached sulfate cellulose obtained from hardwood is subjected oxygen-alkali delignification, after which treated with chlorine dioxide in presence of oxyethylidenediphosphonic acid and then consecutively hydrogen peroxide and chlorine dioxide solutions. Process may be used in production of bleached fibrous intermediates.

EFFECT: increased whiteness and strength characteristics of cellulose and improved environmental safety of bleaching process.

2 cl, 1 tbl

FIELD: pulp-and-paper industry, in particular method for pulp whitening.

SUBSTANCE: pulp mass with concentration of 5-10 % after oxygen-alkaline treatment in step I is treated with sulfuric acid in consumption of 5 % based on dry cellulose mass and pH 2.6-3.0. In step II peroxide treatment is carried out in alkali consumption of 1.0-1.3 % based on dry cellulose mass, and in step III pulp is treated with chlorine dioxide in consumption of 1.0-1.6 % based on dry cellulose mass at 70°C.

EFFECT: pulp with increased whiteness.

1 tbl, 17 ex

FIELD: pulp-and-paper industry, in particular method for PULP whitening.

SUBSTANCE: craft pulp mass with concentration of 2.5-5.0 % after oxygen-alkaline treatment is treated with potassium permanganate in consumption of 0.01-0.1 % based on dry cellulose at 40-80°C and pH 1.6-3.0 or with sulfuric acid solution in consumption of 1.0-1.5 % at 90°C for 30 min. In steps II and IV cellulose with concentration of 10 % is treated with hydrogen peroxide in consumption of 2 % based on mass of dry cellulose for 120 min at 80-90°C and pH 9.5-10.5 wherein consumption of sodium alkali and sodium silicate is 1.3 % and 2.5 %, respectively. In step III cellulose is treated with potassium permanganate in consumption of 0.01-0.4 % under step I conditions.

EFFECT: reduced consumption of whitening agents.

1 tbl, 9 ex

The invention relates to the production of cellulose and can be used to produce bleached pulp without using chlorine-containing reagents

The invention relates to macrocyclic metal complex ligands, used as catalysts for the oxidative bleaching

FIELD: chemistry.

SUBSTANCE: method involves a) chemical treatment of substance containing lignocellulose through an oxidative system which contains at least one non-enzymatic oxidising agent and an activator at pH ranging from approximately 2 to approximately 6.5 and b) mechanical treatment of the substance containing lignocellulose during a period time sufficient for obtaining high alpha-cellulose pulp, where the lignocellulose-containing substance is chemically treated before and/or during any stage for mechanical treatment, and where the lignocellulose-containing substance is not chemically treated at pH ranging from approximately 11.5 to approximately 14 between stages a) and b).

EFFECT: reduced energy consumption, simplification of the method without need for considerable capital investments and improved quality of the end product.

15 cl, 8 dwg, 6 ex, 6 tbl

FIELD: textile, paper.

SUBSTANCE: invention relates to a method of producing wood pulp. The method involves introduction and treatment of the raw material at the first stage of the treatment to produce wood pulp. The wood pulp pH for this procedure is between 9 and 11 at the stage of the method whereat the first suspension of the method is arranged. The first suspension of the method continues for at least 0.5 hour. The wood pulp is sorted to receive the first sorted mass and the first sorting waste. The first sorting waste is ozonised whose pH at the beginning of ozonisation is between 9 and 11. The ozonised first sorting waste at the second stage is purified in a way to have at least a part of it to go into the second sorted mass. The sorted masses are combined. The wood pulp produced in accordance with the method is used to produce paper products.

EFFECT: low energy consumption, prevention of corrosion of the operating units.

8 cl, 5 dwg, 4 ex

FIELD: textiles; paper.

SUBSTANCE: method refers to production of pulp from flax raw material and can be used in the paper-pulp industry for producing of pulp for chemical processing as well as for example of cotton wool, paper and cardboad. The method is realised by means of consequent simultaneous tillage and purification of flax-cuke or flax straw, washing and cutting of the material. Then it is soaked, processed in a thermochemical way, washed through and bleached. Then it is washed again, wrung and dried. Following thermomechanic processing of the pulp containing material it is possible to perform maturation in the alkaline solution.

EFFECT: efficiency increase of method of producing of pulp from flax raw material with high degree of chaff.

2 cl, 1 tbl, 12 ex

FIELD: textiles, paper.

SUBSTANCE: method refers to producing of semichemical pulp from flax raw material and is meant for example for producing of stabilising additives, technical types of paper and cardboard, as well as for producing of pulp for chemical processing and production of cotton wool. The method is realised by means of consequent simultaneous tillage and purification of flax-cuke or flax straw, washing and cutting of the material. Then it is soaked, processed in a thermomechanic way, washed through, wrung and dried. Following thermomechanic processing of the pulp containing material they perform maturation in the alkaline solution.

EFFECT: efficiency increase of method of producing of semichemical pulp from flax raw material with high degree of chaff.

2 cl, 2 tbl, 12 ex

FIELD: textile, paper.

SUBSTANCE: method is referred to bleached wood pulp production from hardwood chips for their further use in different compositions for paper and cardboard production. Chipped wood is impregnated with alkali solution of sodium sulfite. Spent impregnating solution is then removed. Chipped wood is milled in two stages. In between components are treated by alkali solution of hydrogen peroxide at weight concentration 14-18% and final pH=9.5-10.0. Following the second stage of milling, pulp is dissolved to concentration 3.0-5.0% and cured during 30-60 minutes to pH=7.5-8.0. Pulp is chemically treated by alkali solution of hydrogen peroxide between milling stages at 75-85°C during 15-20 minutes.

EFFECT: decrease of chemicals consumption for impregnation and improvement of mechanical and optical properties of target product.

2 cl, 1 tbl, 4 ex

FIELD: paper-and-pulp industry.

SUBSTANCE: process of invention is intended for use in paper-and-pulp industry, e.g. in manufacture if paper and cardboard, and is implemented as follows. Jute fibers are impregnated for 5-15 min with alkali solution containing NaOH and Na2CO3 (1:1) at common N2O consumption 2-4% based on the weight of absolutely dry raw material at temperature 90-120°C. Treated raw material in hot state is transferred together with reagent solution into heated grinding barrels of centrifugal grinding apparatus and ground therein to grinding degree ˜60 degrees of Shopper-Riegler.

EFFECT: increased yield and mechanical strength of intermediate product and reduced environmental pollution.

FIELD: paper-and-pulp industry.

SUBSTANCE: foliferous wood chips are thermally treated by way of steaming to 100-120°C, after which sodium hydroxide solution in amount corresponding to 3.5-4.0% Na2O is added to thermally treated chips and simultaneously chips are introduced to zone operated at 150-160°C, wherein chips are held for 20 min and then passed to hot-grinding apparatus to be repeatedly ground and finally subjected to double-step sorting. Method can be applied in manufacture of paper and cardboard, especially corrugated cardboard.

EFFECT: increased output of desired product and improved quality of ready-to-be-processed pulp.

1 tbl, 4 ex

The invention relates to the pulp and paper industry, in particular to methods of producing bleached chemi-thermomechanical pulp for making paper of various kinds

The invention relates to the field of pulp and paper industry and can find application in the manufacture of bleached wood pulp from deciduous or coniferous wood chips for subsequent use in various compositions for the manufacture of paper and cardboard products

FIELD: paper-and-pulp industry.

SUBSTANCE: foliferous wood chips are thermally treated by way of steaming to 100-120°C, after which sodium hydroxide solution in amount corresponding to 3.5-4.0% Na2O is added to thermally treated chips and simultaneously chips are introduced to zone operated at 150-160°C, wherein chips are held for 20 min and then passed to hot-grinding apparatus to be repeatedly ground and finally subjected to double-step sorting. Method can be applied in manufacture of paper and cardboard, especially corrugated cardboard.

EFFECT: increased output of desired product and improved quality of ready-to-be-processed pulp.

1 tbl, 4 ex

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