EP4423333A1

EP4423333A1 - A method for producing a chemi-thermomechanical fibrous pulp from non-wood plant raw materials and an automated line for producing said pulp by said method

Info

Publication number: EP4423333A1
Application number: EP23718697.8A
Authority: EP
Inventors: Valentyn FRECHKA
Original assignee: Releaf Paper France Sas
Current assignee: Releaf Paper France Sas
Priority date: 2022-03-23
Filing date: 2023-03-22
Publication date: 2024-09-04

Abstract

A method for producing a chemi-thermomechanical fibrous pulp from non-wood plant raw materials, the method comprises steps of preliminary preparing leaves, chemi-thermomechanical treating the preliminary prepared raw materials, grinding a semi-fibrous and partially delignified pulp to produce the chemi-thermomechanical fibrous pulp, wherein the preliminary preparation of the initial raw materials further comprises pressing shredded leaves, plasticizing and softing of the preliminary prepared leaves is performed by their mechanical rubbing and treating with a pressurized heated vapor, delignifying of the plasticized and soft raw materials is performed by their pressurized mixing at a pressure of at least 3.5 atms at a temperature from 70 to 120°C in a presence of an alkali metal hydroxide or in a form of a solution or an aerosol having an alkali concentration of 3% at most, and the grinding is performed in a presence of acetic acid of a concentration of 3% at most.

Description

A METHOD FOR PRODUCING A CHEMI-THERMOMECHANICAL FIBROUS PULP FROM NON-WOOD PLANT RAW MATERIALS AND AN AUTOMATED LINE FOR PRODUCING SAID PULP BY SAID METHOD

The invention relates to a field of cellulose, in particular, to a technology for treating plants leaf biowaste followed by prpducing a chemi-thermomechanical fibrous pulp that is suitable for manufacturing, e.g., paper products, as well as to a line for producing said fibrous pulp.

The chemi-thermomechanical fibrous pulp is a semi-finished product for paper manufacturing and comprises a set of lignin-free cellulose fibers which are able to be bound to each other and usually obtained from a wood by a chemical or a mechanical method. The cellulose fibers are released from the wood by destroying or dissolving non-qellulose components by means of a chemical or a mechanical treatment. Lignin becomes soluble, a portion of hemicelluloses is hydrolyzed, formed oligo- and monosaccharides are dissolved, and a nondissolved remainder comprises a cellulose fiber which is then filtered and modified in a certain way. Lately, a considerable focus is given to minimization of deforestation for the paper manufacturing needs, as well as to minimization of waste products emissions after treatment of lignocellulose raw materials.

It is known that trees and other woody plants are not a single source of the fibers for manufacturing paper products. There are numerous annual and perennial plants having leaves comprising fibers of a sufficient rigidity and length to manufacture the paper of a suitable quality.

Fallen leaves of these plants are usually burnt or become tp decay. One of main advantages of these fiber sources is that they are considered by the field of the art as environmentally friendly alternatives to the wood, are annually renewable and form in large volumes. However, the development of the non-wood fiber industry is still not so available as the wood fibers due to the fact that the non-wood cellulose usually is more expensive than the wood one. Besides, the treatment of leaves is usually complicated by using sulfur-containing reagents or highly alkali solutions, thereby decreasing the fiber yield (10-20%), causing its shortening and destruction.

A number of methods for producing a non-wood cellulose is known. For example, patent US9950858 relates to manufacturing of a cellulose material from a tobacco. This invention provides tobacco-derived paper products, packaging materials and containers for tobacco products, as well as other consumable and food products. In particular, it discloses a fibrous material that comprises at least 10% of dry weight percent of fibers derived from a plant of the Nicotiana species, as well as a method for producing such a fibrous material, the method is based on treating different tobacco portions with sodium hydroxide of 24% concentration and at a temperature of 160°C.

Patent document GB2283989 discloses a possible production of a fibrous pulp from banana leaves using an alkali process and relates to manufacturing an unbleached cellulose. This technology involves using a banana leaves biomass at the following treatment conditions: caustic soda 12% (NaOH), maximum temperature 150°C, duration of 3 hours.

A drawback of this method is the use of a significant number of the alkali solvent of a high concentration. Besides, the long treatment at this high temperature and at this solvent concentration decreases the fiber quality, namely, its rigidity, thereby shortening the fiber "life time" during next treatments in order to produce products therefrom.

Patent document CN104674353 discloses a method for producing a long-fiber cellulose from pineapple leaves by refine treatment of a biomass, the method comprises, firstly, ultrasonic pre-treatment of the fibers; then - treatment for expansion of the fibers which is performed with special chemical reagents; after expansion, a chemical treatment is performed; and degumming, shredding and drying of the pineapple leaves fiber are performed at the end of the method.

High costs for the ultrasonic treatment of the raw materials represent a main drawback of this method. Besides, the disclosed method does not allow to remove large molecules of a lignin encrustrator, thereby making the fiber breakable and non-resistant against UV-rays.

The closest prior art of the claimed invention is a method for manufacturing a paper from leaves which is disclosed by patent document KR20150085179, the method is based on a fiber extraction technology by subjecting the leaves to organic solvents. According to the disclosed technology, the leaves are subjected to steps of cleaning, shredding, fiber removal by centrifugation of the shredded mixture that is mixed with the solvent in order to separate a pigment from the main fiber. A pigment separation solution may comprise acetone methyl ether, ethyl ether, diethyl ether, hexane and palm oil. Drawbacks of this method are as follows:

- high price of the solvents;

- high toxicity level of the solvents which requires to provide special working conditions at an industrial site;

- low ability of the solvents to dissolve lignin polymers which decreases a mechanical rigidity of the fiber;

- complex disposal or processing of leaves treatment liquid products.

Therefore, an objective of the claimed invention is to provide a method and an automated line for producing a chemi-thermomechanical fibrous pulp from non-wood vegetable raw materials of various types (delicate group and stable group of the raw materials) which are intended to achieve a technical effect of producing the chemi-thermomechanical fibrous pulp that could be suitable for manufacturing paper products of a certain purpose in an environmentally friendly way, at a maximum performance and at minimum costs.

The objective is achieved by providing a method for producing a chemi- thermomechanical fibrous pulp from non-wood plant raw materials, the method comprises steps of: preliminary preparing leaves comprising at least separating the leaves from inclusions devoid of plant fibers and shredding the separated raw materials, chemi-thermomechanical treating the preliminary prepared raw materials comprising at least plasticizing thereof and delignifying the plasticized raw materials to produce a semi-fibrous and partially delignified pulp, grinding the semi-fibrous and partially delignified pulp to produce the chemi- thermomechanical fibrous pulp, wherein the preliminary preparation of the initial raw materials further comprises pressing the shredded leaves, the plasticizing of the preliminary prepared leaves is performed by their mechanical rubbing and treating with a pressurized heated vapor, the delignifying of the plasticized raw materials is performed by their pressurized mixing at a pressure of at least 3.5 atms at a temperature from 70 to 120°C in a presence of an alkali metal hydroxide or in a form of a solution or an aerosol having an alkali concentration of 3% at most, and the grinding is performed in a presence of acetic acid of a concentration of 3% at most.

The non-wood raw materials, preferably, fallen leaves, are biowaste generated at cities, parks or other green areas. Preferably, these leaves are annual portions of the plants, so useful portions of the leave are very sensitive to mechanical treatment and, particularly, they may be seriously damaged during the processing. This results in a strong shortening of the fallen leaves fibers at a long-term chemical and mechanical treatment. Thus, the leaves fibers are too short for manufacturing the paper, since they lose mutual binding properties which is crucial for providing a rigidity of the paper. The claimed method is particularly adapted to produce the chemi- thermomechanical fibrous pulp from the non-wood plant raw materials and avoids said damaging and shortening of the fibers.

These cellulose production conditions provide its softness, rigidity and fibers integrity. The cleaned fiber pulp may be used to form paper products of various purposes from 100% fibers or in a composition along with processed fibers of wastepaper grades MS-5B, MS-8V, MS-3A, MS- 2A etc.

The claimed method allows to produce the fiber at optimal conditions which helps to maintain the fiber integrity, to separate most of encrusting components and to increase the yield up to 42%.

Use of water in the method is minimized: firstly, no traditional fiber cooking that requires much water is performed; secondly, the treatment of the raw materials mainly utilizes vapor that saturates the biomass so that it becomes pourable, but not liquid; thirdly, the grinding step utilizes acetic acid, while lignin is precipitated and less water is required to wash it. Therefore, the water consumption is about 15 times less as compared to the traditional field of art.

The claimed method consists of a minimum number of steps, requires a minimum number of equipment units, minimizes a number of steps for increasing and decreasing the pulp concentration; minimizes a number of the required pulp washing steps; minimizes a number of pH changes. Besides, the method avoids use of toxic agents or rear chemical agents. Instead, it is characterized by using weak alkalis and acids, i.e., non-toxic solvents, low price, thereby allowing to restore all internal drains. Therefore, the claimed method is environmentally friendly and cost- effective.

Preferably, the claimed method is characterized by producing the fibrous pulp having characteristic values such as a grinding degree of 28 Shopper-Rigler degrees (°RS), pH of 8, fiber length from 0.7 to 1.2 mm, fiber diameter from 28 to 32 nm, brown kraft color, ash content of 11%.

The word combination "fibrous pulp" is interchangeably used herein with such terms as semi-fibrous pulp, fibrous semi-finished product and semi-cellulose.

Preferably, the used non-wood plant raw materials include autumn fallen tree leaves, bushes fallen leaves, shrub fallen leaves, a leaf portion of temperate climate annual plants, modified forms of the leaves such as, e.g., needles, as well as a leaf-stem portion of the plants having a curly growth way, fresh plant leaves of a waste nature, and fallen leaves of tropical equatorial plants, namely, fallen leaves of tropical equatorial trees, fallen leaves of tropical equatorial bushes, fallen leaves of tropical equatorial shrubs, modified forms of the leaves such as, e.g., water storing leaves, spines, as well as a leaf-stem portion of plants having a curly growth way, fresh plant leaves of a waste nature. The leaves may have any color scheme, structure, humidity, contamination degree, decomposition degree, size, origin and formation source.

Preferably, the separation of the leaves comprises dividing them into groups, including at least a delicate group and a stable group.

The delicate group (LPG-001) mainly refers to temperate climate leaves, since they mainly act to maintain photosynthesis and gas exchange within a short period of the year (7 months). Their structure is very fragile, since they lack any rigid trophic tissues which could comprise a fiber similar to, e.g., fibers in a bast. Thus, the technological treatment process of these leaves comprises a strong mechanical treatment and a long alkali treatment at ultra-high temperatures in order to preserve the integrity of the fibers and a maximum pulp yield.

Most of the delicate group plants (LPG-001) include the following temperate climate plants: Betula borysthenica Klokov, Betula pendula Roth., Ulmus minor, Fagus sylvatica L., Fagus orientalis, Ulmaceae, Salix L., Alnus incana, Aesculus hippocastanum, Carpinus betulus L, Quercus robur L.,Quercus rubra (Quercus borealis), Catalpa bignonioides Walt., Castanea sativa, Acer platanoides L., Acer campestre, Tilia platyphyllos, Populus tremula L., Platanus, Rhus L., Populus nigra L., Fraxinus, Prunus cerasus L., Juglans regia L, Morus, Pinus sylvestris L., Acacia, Paulownia, Paulownia fortunei, Paulownia elongata, Paulownia Cion in Vitro 112, Citrus sinensis, Citrus reticulata, Diospyros, Ficus, Acer saccharum Marsh., Vitaceae, Humulus L., Ginkgo, Ginkgo biloba, Robinia pseudoacacia, Tectona grandis, Shorea robusta, Humulus L., Reynoutria japonica, Lycopersicon, Vitis, Juglans regia, Corylus avellana, Castanea, Castanea Sativa, Ameldnchier, Ma I us, Rhus.

The strong group (SPG-002) mainly refers to tropical equatorial climate leaves, since in view of the climatic conditions, in particularly, a moisture regime and a long warm period of the year, fibers of these leaves are longer, have more branched lignin fractions and a greater mechanical rigidity degree as compared to the temperate climate leaves. In order to produce the fibrous pulp, firstly, encrustrators, lignin, xylan and other compounds must be removed from this group which is possible to perform at more aggressive pressure, temperature and alkalinity conditions,

Most of the stable group plants (SPG-0Q2) include the following tropical equatorial climate plants: Cocos nucifera, Roystonea altissima (Mill.) H.E. Moore, Roystonea borinquena O.F.Cook, Roystonea dunlapiana P.H.Allen, Roystonea lenis Leon, Roystonea maisiana (L.H.Bailey) Zona, Sabal causiarum (O.F.Cook) ex Becc., Saba! domingensis Becc., Sabal etonia Swingle ex Nash, Sabal gretherae HJ.Quero.R., Phoenix acaulis Roxb., Phoenix andamanensis S.Barrow, Phoenix atlantica A.Chev., Phoenix canariensis Chabaud, Phoenix dactylifera L. typus, Phoenix loureiroi Kunth, Phoenix paludosa, Bismarckia, Livistoneae, Ananas comosus var. bracteatus, Ananas comosus var. comosus, Ananas comosus var. erectifolius, Aloe vera, Salacca zalacca.

The conditions of the claimed method are used in the treatment of both delicate and stable groups of leaves.

Preferably, the preliminary preparation of the initial raw materials further comprises washing thereof and inactivating living microorganisms therein followed by drying and shredding the separated raw materials.

Also, the pressing of the shredded raw materials, preferably, comprises granulating or briquetting or baling thereof.

The chemi-thermomechanical fibrous pulp may be subjected to the grinding at a high concentration and/or subjected to the grinding at a low concentration.

Therewith, after the fibrous pulp is ground, it is subjected to vibration sorting to sort out non-defibrated particles of the pulp followed by thickening of the pulp.

Besides, the objective is achieved by providing an automated line for producing the hemi- thermomechanical fibrous pulp by the claimed method, the line comprises an initial raw materials preliminary preparation unit, a chemi-thermomechanical unit, a grinding unit which are arranged in series in a moving direction of the raw materials, wherein the initial raw materials preliminary preparation unit comprises at least a separation tool to separate the initial raw materials from inclusions devoid of plant fibers, a raw materials shredder and a raw materials pressing tool, the chemi-thermomechanical unit comprises at least a sealed thermomechanical screw disperser that is equipped with a pressurized vapor feeding tool, a high-pressure chemi- thermomechanical chamber that is configured to change a temperature and a pressure and that is equipped with a feeding tool for feeding an alkali metal hydroxide or a solution thereof in a form of an aerosol, a high concentration defibrating device, the grinding unit comprises at least a high concentration hydro pulper that is equipped with an acetic acid feeding tool, and at least one refiner, and an outlet of the sealed thermomechanical screw disperser is coupled to an inlet of the high-pressure chemi-thermomechanical chamber, while an outlet of the high concentration defibrating device is coupled to an inlet of the high concentration hydro pulper.

Said line is configured to perform the claimed method for producing the chemi- thermomechanical fibrous pulp from the non-wood raw materials, thereby providing all advantages of the claimed method.

Preferably, the initial raw materials preliminary preparation unit further comprises a washing basin that is equipped with a bactericidal solution feeding tool and a dryer, while the washing basin and the dryer are arranged in series and coupled between each other, wherein an outlet of said separation tool is coupled to the washing basin, while an outlet of the dryer is coupled to said shredder.

Besides, the shredded raw materials pressing tool is preferably made as a granulator or as a briquetting press or as a baling press.

According to one of preferable embodiments, the grinding unit comprises a high concentration refiner and a low concentration refiner which are arranged in series.

The grinding unit may further comprise a vibration sorting platform that is arranged after the refiner and equipped with a water spraying tool for spraying the water onto the platform.

Besides, the grinding unit may further comprise a pulp thickener that is arranged after the vibration sorting platform.

The claimed invention will be explained hereinafter with the following Figure:

Fig. illustrates a scheme of the preferable embodiment of the automated line for producing the chemi-thermomechanical fibrous pulp by the present inventive method.

This Figure illustrates a scheme of the preferable embodiment of the automated line for producing the chemi-thermomechanical fibrous pulp by the present inventive method. Said line comprises three main units: an initial raw materials preliminary preparation unit 1, a chemi- thermomechanical unit 2 and a grinding unit 3. As it can be seen from the Figure, the preliminary preparation unit comprises the following devices which are arranged in series and coupled between each other: a raw materials separation tool made as a drum separator 4, a washing basin 5, a convection tunnel dryer 6, a shredder 7 and a shredded raw materials pressing tool made as a granulator 8. Having passed through the granulator 8, the raw materials may pass to a warehouse 9 or to a working hopper 10 wherefrom they are fed to the chemi-thermomechanical unit 2. The latter comprises the following devices which are arranged in series and coupled between each other: a screw mixer conveyor 11, a sealed thermomechanical screw disperser 12 that is equipped with a pressurized vapor feeding tool, a high-pressure chemi-thermomechanical chamber 13 and a high concentration defibrating device 14. In turn, the latter grinding unit 3 comprises the following devices which are arranged in series and coupled between each other: a high concentration hydro pulper 15, two refiners 16 and 17, a vibration sorting platform 18 and a pulp thickener 19.

In order to study parameters of the product which may be produced by the claimed method, as well as to explain parameters of said method, the latter was performed in laboratory conditions as follows.

A fallen leaves mixture was firstly separated from branches, debris, sand and dirt by washing it with a running water, and then dried to obtain a constant humidity and shredded. A weighed amount of the ram materials for process imitation was 1000 g.

The prepared dry leaves were loaded into a laboratory autoclave provided with an electrical heating element, where they were kept for 45 minutes at a pressure of 2 atms and at a controlled temperature of at least 100°C with a hydromodule of 1:5. This process provided a hydrothermal impregnation of the leaves and provided them with plasticity properties: some temperature-instable molecules transited into a soluble phase, resins became more pourable, while proteins denaturated. This step was performed to prepare the raw materials for impregnation them with an alkali solution.

The preliminary prepared raw materials were multiply passed through a laboratory rolling machine having a slit size from 0.2 to 1 mm in order to squish/soften said raw materials and to make them more prepared for producing the fiber.

Then, the pulp was washed and loaded into a non-sealed screw mixer with a heating function of up to 100°C, whereto a delignifying alkali solution was fed. The pulp was stirred constantly, rubbed by a high pressure that was created upon pumping of the pulp in a rotation direction of a screw shaft. This process lasted for 30 minutes. During this period of time, the soft and swollen raw materials were absorbing the active alkali which resulted in a partial delignification and freeing of the fiber being suitable for the paper production.

The delignified raw materials were loaded into a laboratory hydrobeater having a bottom rotor, where the raw materials at the pulp concentration of 8% were subjected to disintegration and partial defibration for 5 minutes. Then, a 3% acetic acid solution was added to the raw materials, and the defibration process lasted for 5 minutes more. At this step, the integral lignin was precipitated, the fiber gained properties which defined its further grinding and paper manufacturing ability, pH of the medium was 6, and the fiber was clearing.

The partially defibrated raw materials devoid of most of the lignin content were washed and subjected to a final defibration at a laboratory hollander according to ISO 5264-1, TAPPI T 200m, T 205m, SCAN C 25, CPPA C.2 standards. The average defibration duration was 15 minutes, while a load onto the rotor was applied by a 500 g kettlebell. This mode allowed to achieve the pulp grinding degree of 25°RS and to maintain the fibers integrity. The grinding was terminated by washing, thickening and drying the fiber. The obtained fiber samples were preliminary dehydrated by pressing and drying in a drying cabinet at a temperature of 95°C (203°F) during 3 hours and then they were analyzed.

Table 1 shows results of the research of a component composition of the initial leaves mixture. Cellulose is the main component of the leaves, and its content in some of the samples was determined at the level of 48.8%. The lignin content was 27%. This lignin/cellulose ratio is peculiar to annual plants. Initial swelling and softening of the pulp and further alkali chemi- thermomechanical treatment resulted in destruction of intermolecular ether bonds which were cross-linked by hemicelluloses and lignin, but it took place gradually and without damaging the fiber structure.

Table 1. Results of the research of a component composition of the initial leaves mixture

Tables 2 provides results of the average diameter of the obtained fibers before and after the chemi-thermomechanical treatment of the initial raw materials in various conditions, as well as in aggressive conditions of the leaves treatment without steaming and rolling and at the high alkali and acid concentration. After the alkali treatment, it was observed that organic substances comprised in the initial raw materials were actively dissolved, and it already started at low temperatures upon contact of the raw materials with the alkali solution. During the reaction, the solution was actively stained in brown color which is peculiar for the lignin dissolution.

Table 2. - Average diameter of the produced fibers

This vulnerability of the fiber of the leaves to the treatment conditions without any preliminary preparation is associated with the fact that the leaf structure is very loose, since it has a high parenchymal tissue content, and when the leaf is saturated with moisture and performs its function, it has high rigidity and elasticity. After falling, the moisture is evaporated, cell structures are encrustrated by lignin, compressed and become breakable. If the alkali solution or a mechanical force or a temperature suddenly acts on this pulp, the internal pressure of cornified cells and interstructural elements will be disrupted in a non-uniform fashion and it will lead to a breakage of the fiber along with the encrustrators.

Several treatment options of the leaves were defined which depend on whether they related to the delicate group or to the stable group, and these treatment options are provided below.

Example 1.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 70°C to 80°C during 2 hours and at the alkali concentration of 3%.

Example 2.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 75°C to 85°C during 2 hours and at the alkali concentration of 3%.

Example 3.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 90°C to 100°C during 2 hours and at the alkali concentration of 3%. Example 4.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 70°C to 80°C during 2 hours and at the alkali concentration of 2%.

Example 5.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 75°C to 85°C during 2 hours and at the alkali concentration of 2%.

Example 6.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 90°C to 100°C during 2 hours and at the alkali concentration of 2%.

Example 7.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 70°C to 80°C during 3 hours and at the alkali concentration of 1%.

Example 8.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 75°C to 85°C during 3 hours and at the alkali concentration of 1%.

Example 9.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature from 90°C to 100°C during 3 hours and at the alkali concentration of 1%.

Example 10.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature of 110°C during 1.5 hours, and at the alkali concentration of 3% and at the pressure of 3.5 atms.

Example 11.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature of 120°C during 1.5 hours, and at the alkali concentration of 3% and at the pressure of 4.5 atms.

Example 12.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature of 110°C during 2 hours, and at the alkali concentration pf 2% and at the pressure of 3.5 atms.

Example 13.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature of 120°C during 2 hours, and at the alkali concentration pf 2% and at the pressure of 4.5 atms.

Example 14.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature of 110°C during 2 hours, and at the alkali concentration of 1% and at the pressure of 3.5 atms.

Example 15.

The preliminary prepared raw materials of the delicate group were treated according to the claimed method at the temperature of 120°C during 2 hours, and at the alkali concentration of 1% and at the pressure of 4.5 atms.

Example 16.

The preliminary prepared raw materials of the delicate group were treated by soaking the leaves in a hot water and by mechanical rolling of the softened pulp, while performing a cold extraction of the fiber at the alkali concentration of 1% and during 2 hours. Example 17.

The leaves mixture of the delicate group was treated by soaking the leaves in a hot water and by mechanical rolling of the softened pulp, while performing a cold extraction of the fiber at the alkali concentration of 2% and during 2 hours.

Example 18.

The preliminary prepared raw materials of the delicate group were treated by soaking the leaves in a hot water and by mechanical rolling of the softened pulp, while performing a cold extraction of the fiber at the alkali concentration of 3% and during 2 hours.

Example 19.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 70°C to 80°C during 2 hours and at the alkali concentration of 3%.

Example 20.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 75°C to 85°C during 2 hours and at the alkali concentration of 3%.

Example 21.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 90°C to 100°C during 2 hours and at the alkali concentration of 3%.

Example 22.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 70°C to 80°C during 2 hours and at the alkali concentration of 2%.

Example 23.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 75°C to 85°C during 2 hours and at the alkali concentration of 2%.

Example 24.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 90°C to 100°C during 2 hours and at the alkali concentration of 2%.

Example 25.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 70°C to 80°C during 3 hours and at the alkali concentration of 1%.

Example 26.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 75°C to 85°C during 3 hours and at the alkali concentration of 1%.

Example 27.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature from 90°C to 100°C during 3 hours and at the alkali concentration of 1%.

Example 28.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature of 110°C during 1.5 hours, and at the alkali concentration of 3% and at the pressure of 3.5 atms.

Example 29.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature of 120°C during 1.5 hours, and at the alkali concentration of 3% and at the pressure of 4.5 atms. Example 30.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature of 110°C during 2 hours, and at the alkali concentration of 2% and at the pressure of 3.5 atms.

Example 31.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature of 110°C during 2 hours, and at the alkali concentration of 1% and at the pressure of 3.5 atms.

Example 32.

The preliminary prepared raw materials of the stable group were treated according to the claimed method at the temperature of 120°C during 2 hours, and at the alkali concentration of 1% and at the pressure of 4.5 atms.

In order to establish the quality of the produced fiber, a number of paper manufacturing tests was conducted, and the paper was analyzed to evaluate physical and mechanical parameters thereof.

A paper sample made of 100% fiber and in a mixture with a MS-5B brand wastepaper at various ratios was cast from the fiber produced by the above-mentioned methods. The casting was performed at a D-47809 paper machine having an inclined 36.4 cm wide grid table and an open head box at a rolling rate of 2.15 m per min.

After casting, drying and cutting the samples, the paper was tested to evaluate physical and mechanical parameters thereof.

Table 4 shows results of the paper product tests, namely, for the paper made of the fallen leaves mixture and made of the same mixture together with the MS-5B brand wastepaper. The tests were conducted according to the following standards: BDS EN ISO 536: 2020 Paper and cardboard - Determination of grammage of 1 m² of the paper (ISO 536: 2019); BDS EN ISO 534: 2012 Paper and cardboard - Determination of thickness, density and specific volume (ISO 534: 2011); B ISO 535: 2014 Paper and cardboard - Determination of bursting strength (ISO 2758: 2014); ISO 1974: 2012 Paper - Determination of tearing resistance by the Elmendorf method; BDS ISO 1924-3: 2011 Paper and cardboard - Elongation rate (100 mm per min); ISO 5636-5: 2013 Paper and cardboard - Determination of air permeance (middle range) - Part 5: Gurley method.

Table 4. Physical and mechanical parameters of the paper

According to the testing results of the paper laboratory samples as shown in the Table 3, it can be concluded that the physical and mechanical parameters of the paper made of 100% vegetable biowaste are satisfying.

When the pulp grinding degree was 28°RS, the weight of 1 m² of the paper of 98 g/m² and the thickness of 0.35 mm were achieved, which is greater than the standard. Probably, it might be caused by the high dimension of the fibers. The destruction force in the machine direction in the dry condition is 21% lower than the standard average value, while the destruction force in the transverse direction is in line with the standard. The bursting strength index is greater than the standard. The air permeability of the paper is greater than the standard, since the fiber has the low grinding degree. It should be noted that in order to provide testing purity, all test paper samples were not sized, i.e., all the parameters may be greatly improved by supplementing the paper pulp with fillers which improve the mechanical properties of the paper, e.g., alkyl ketene dimer (AKD) or starches.

According to the technology process as imitated in the laboratory conditions, it was confirmed that it is possible to use the plant organic material of the non-wood origin in manufacturing paper products having satisfying parameters.

The claimed line operates as follows.

The leaves are pre-processed by the initial raw materials preliminary preparation unit 1 according to the scheme (see the Fig.). The leaves delivered to a facility landfill are fed to the drum separator 4, where they are purged with air flows through perforations, thereby removing sand, stones, heavy non-plant inclusions or light fractions, e.g., polyethylene. Since the drum separator 4 is equipped with internal ribs and arranged at an angle, then as it rotates clockwise, the leaves move towards the upper section of the separator 4, thereby unloading to the washing basin 5. The basin 5 is filled with the bactericidal solution for inactivation of living microorganisms. Owing to the water circulation and to the bubble-type agitation, the leaves are moved towards a front section of the basin 5, where they are caught by a grid vibration conveyor that moves through a pneumatic dehydrator and then through the convection tunnel dryer 6. The leaves may be delivered in both dry and wet states, but it must be washed anyway to remove any dirt, bacteria, fungal spores, as well as dried in order to allow their long-term storage. After the leaves are dried, they are shredded by the shredded 7 to obtain a particle size from 1 to 2 cm. The shredded leaves mass is poured into a collection hopper, wherefrom it is fed to the granulator 8 by the screw conveyor. Since the leaves have a low bulk density, the granulation process allows to increase this parameter. A cylindrical granule having a diameter of 1 cm and a length of 2 cm or a briquette having dimensions of 2x2 cm may be produced depending on the type of the raw materials. Then, depending on the manufacturing needs, a redistribution is performed, so one part is packed into big-bag containers, while another part is loaded to the next unit by the screw conveyor.

This step is performed to obtain raw materials which would be maximum selective for cost-effective storage, transportation and further process.

The, the dry granulated leaf mass is fed to the sealed thermomechanical screw disperser 12 through the screw mixer-conveyor 11. The screw disperser is made as a cylindrical horizontal chamber having a screw shaft that has a smaller pitch towards unloading of the mass resulting in that the mass, during its output, is at the very high pressure so it is easy to be rubbed. The pressurized water vapor is fed to the disperser at the high temperature. The main purpose of this step is to provide the leaves with elasticity, swelling and more homogeneous. Since this process is provided in the wet medium and at the high temperature, a part of the organic molecules will be dissolved, the proteins will be denaturated etc., thereby making the further treatment of the leaves easier.

After being pushed out by the pressure and rotation movements, the plasticized and soft leaves are forwarded to the chemi-thermomechanical chamber 13 at the high-pressure conditions. A sodium hydroxide aerosol is fed to said chamber, and the leaves are actively stirred, saturated with the alkali, thereby resulting in degradation of most of the compounds and in transition of lignin into the soluble phase. Due to formation of a condensate, the pulp which is already semi-fibrous is thoroughly washed to remove lignin. The alkali in the form of aerosol is fed to the chamber via nozzles, pH of the process is about 12, the active alkali concentration is 3%, the hydro module is 1:3, the operation temperature is from 105 to 120°C, the pressure is from 3.5 to 4.5 atms.

According to the same operation principle of the thermomechanical screw disperser, the raw materials are unloaded into the high concentration defibrating device 14. The defibrating device 14 cleaves cellulose fibrils, thereby making the fiber finer. Owing to the strong plasticity of the biomass and to the lack of encrustrators therein, the fiber is not so breakable as before and is easy to be cleaved.

This step is performed to produce a high yield fibrous pulp that is easy to grind.

The grinding is performed by the unit 3 according to Fig. As the fibers sizes are decreased together with the water flow, the already fibrous pulp passes via a grinding disc of the high concentration defibrating device 14 and pumped to the high concentration hydro pulper 15 which the 3% acetic acid solution is fed to. The purpose of this step is to precipitate the integral lignin, to align the pH value and to compress the cellulose fibrils. Beating is performed for 15 minutes, and then the fibrous pulp, by its own weight, is poured into the basin wherefrom it is distributed between the first and second order refiners 16 and 17 respectively. At this step, the pulp grinding degree is already from 15 to 22°RS. Since the leaves have a very fragile structure, the grinding mode at the refiners may be performed in several ways:

- both refiners are involved, the concentration is high at the first refiner, while it is low at the second refiner,

- only one refiner is involved, high concentration, short grinding time,

- only one refiner is involved, low concentration, short grinding time,

- only one refiner is involved, low concentration, long grinding time.

The refiners 16 and 17 enable to adjust a fitting closure degree which affects the time period for passage of the pulp though the refiner which, in turn, affects the further grinding degree. The optimal grinding degree in this method is 28°RS.

Since it is possible, at the previous steps, that there will be some particles in the biomass which were not cleaved into the fibers, a screening at the vibration sorting platform 17 is performed after all the production steps by spraying the water in order to provide a better separation of the fiber from the non-fiber inclusions. By performing the screening step at this particular point, rather than after the alkali treatment step, decreases material losses.

Nevertheless, the screening may be performed at several steps depending on the raw materials as well as on the quality and economical requirements. After the screening is performed, the 100% fibrous pulp is fed to the pulp thickener 19 followed by its distribution to a paper products manufacturing facility. As per examination results, said method is characterized by the following values of resources consumption to produce 1 ton of the pulp:

Table No. 5 - values of resources consumption to produce 1 ton of the pulp The produce chemi-thermomechanical fibrous pulp is suitable for manufacturing, e.g., paper products, in particular, calendered kraft paper (70-170 g/m²), non-calendered kraft paper (70-420 g/m²), paper bags, multilayered cardboard, corrugated cardboard having 3, 5, 8 layers followed by processing it into corrugated packaging, egg carton-type cast packaging produced by a vacuum casting method, egg boxes, logistical packaging, floor insulation lining (2.5-10 mm), bulk insulation, seedling and plant packaging, decorative materials and fillers, fibrous polymer foam, biocomposite fiber-based materials produced from leaves and bioplastics, biopolyurethanes.

Therefore, the method and the automated line for producing the chemi- thermomechanical fibrous pulp from non-wood plant raw materials of various types (delicate group and stable group of the raw materials) have been provided, and they are intended to achieve the technical effect of producing the chemi-thermomechanical fibrous pulp that is suitable for manufacturing paper products of the certain purpose in the environmentally friendly way, at the maximum performance and minimum costs.

Claims

1. A method for producing a chemi-thermomechanical fibrous pulp from non-wood plant raw materials, the method comprises steps of: preliminary preparing leaves comprising at least separating the leaves from inclusions devoid of plant fibers and shredding the separated raw materials, chemi-thermomechanical treating the preliminary prepared raw materials comprising at least plasticizing, softing thereof and delignifying the plasticized raw materials to produce a semi- fibrous and partially delignified pulp, grinding the semi-fibrous and partially delignified pulp to produce the chemi- thermomechanical fibrous pulp, wherein the preliminary preparation of the initial raw materials further comprises pressing the shredded leaves, the plasticizing and softing of the preliminary prepared leaves is performed by their mechanical rubbing and treating with a pressurized heated vapor, the delignifying of the plasticized and soft raw materials is performed by their pressurized mixing at a pressure of at least 3.5 atms at a temperature from 70 to 120°C in a presence of an alkali metal hydroxide or in a form of a solution or an aerosol having an alkali concentration of 3% at most, and the grinding is performed in a presence of acetic acid of a concentration of 3% at most.

2. The method according to claim 1, wherein the separation of the leaves comprises dividing them into groups, including at least a delicate group and a stable group.

3. The method according to claim 1, wherein the preliminary preparation of the initial raw materials further comprises washing thereof and inactivating living microorganisms therein followed by drying and shredding the separated raw materials.

4. The method according to claim 1, wherein the pressing of the shredded raw materials comprises granulating or briquetting or baling thereof.

5. The method according to claim 1, wherein the chemi-thermomechanical fibrous pulp is subjected to the grinding at a high concentration and/or subjected to the grinding at a low concentration.

6. The method according to claim 1, wherein after the fibrous pulp is ground, it is subjected to vibration sorting to sort out non-defibrated particles of the pulp followed by thickening of the pulp.

7. An automated line for producing a chemi-thermomechanical pulp by the method according to claim 1, the line comprises below-mentioned components which are arranged in series in a moving direction of raw materials: an initial raw materials preliminary preparation unit, a chemi-thermomechanical unit, a grinding unit, wherein the initial raw materials preliminary preparation unit comprises at least: a separation tool to separate the initial raw materials from inclusions devoid of plant fibers, a raw materials shredder and a raw materials pressing tool, the chemi-thermomechanical unit comprises at least: a sealed thermomechanical screw disperser that is equipped with a pressurized vapor feeding tool, a high-pressure chemi-thermomechanical chamber that is configured to change a temperature and a pressure and that is equipped with a feeding tool for feeding an alkali metal hydroxide or a solution thereof in a form of an aerosol, a high concentration defibrating device, the grinding unit comprises at least: a high concentration hydro pulper that is equipped with an acetic acid feeding tool, and at least one refiner, and an outlet of the sealed thermomechanical screw disperser is coupled to an inlet of the high-pressure chemi-thermomechanical chamber, while an outlet of the high concentration defibrating device is coupled to an inlet of the high concentration hydro pulper.

8. The line according to claim 7, wherein the initial raw materials preliminary preparation unit further comprises a washing basin that is equipped with a bactericidal solution feeding tool and a dryer, while the washing basin and the dryer are arranged in series and coupled between each other, and an outlet of said separation tool is coupled to the washing basin, while an outlet of the dryer is coupled to said shredder.

9. The line according to claim 7, wherein the shredded raw materials pressing tool is made as a granulator or as a briquetting press or as a baling press.

10. The line according to claim 7, wherein the grinding unit comprises a high concentration refiner and a low concentration refiner which are arranged in series.

11. The line according to claim 7, wherein the grinding unit further comprises a vibration sorting platform that is arranged after the refiner and equipped with a water spraying tool for spraying the water onto the platform.

12. The line according to claim 7, wherein the grinding unit further comprises a pulp thickener that is arranged after the vibration sorting platform.