Paper pulp stickies removal method based on biodegradation

Abstract

The invention relates to the technical field of pulping and papermaking, and discloses a biodegradation-based paper pulp stickies removal method, which comprises the following steps: firstly, analyzing main components of stickies in paper pulp, selecting a corresponding bio-enzyme as a stickies control enzyme according to the main components of the stickies, and then exploring process parameters of the stickies control enzyme on the hydrolysis of the stickies; then adding a stickie control enzyme into the slurry, and controlling process parameters of a hydrolysis reaction system; the stickies are hydrolyzed into water-soluble low-molecular substances through the stickies control enzyme, and the fine particle stickies and the hydrolyzed substances are wrapped and emulsified, so that the fine particle stickies are stable in the system and do not aggregate into large particles; and by utilizing the decomposition and oxidation reactions of the bio-enzyme and the stickies, the stickies and colloid garbage with different compositions in the system are degraded, so that the stickies and colloid garbage are stably dispersed in water and are effectively removed.

Description

Technical Field

[0001] The invention relates to the technical field of pulping and papermaking, and in particular to a method for removing pulp stickies based on biodegradation. Background Art

[0002] At present, waste paper, as an important source of secondary fiber, can not only effectively alleviate the contradiction between the shortage of papermaking fiber raw materials and energy shortage, but also help to alleviate the increasingly serious environmental pollution problem. However, in the process of waste paper recycling, various adhesives, coating adhesives, ink binders and other impurities introduced during the production, processing and use of paper will be released into the pulp water system in large quantities to form adhesives, which will cause serious harm to the normal operation of the paper machine.

[0003] Stickies adhere to and deposit on the press felt, guide rollers or drying cylinder surface and dryer net, and are easily attached to the paper, thus causing paper defects. For example, the dewatering efficiency of the wire section is reduced due to the deposition of stickies, which causes problems such as sticking to the rollers and cylinders during the subsequent paper stripping process in the press and dryer sections, thus causing holes in the paper and forming paper defects. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for removing pulp stickies based on biodegradation, which utilizes reactions such as decomposition and oxidation of biological enzymes with stickies to degrade stickies and colloidal garbage of different compositions in the system, so that they are stably dispersed in water and effectively removed.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A method for removing stickies from pulp based on biodegradation, firstly analyzing the main components of stickies in the pulp, selecting corresponding biological enzymes as stickies-controlling enzymes according to the main components of the stickies, then exploring the process parameters of hydrolysis of stickies by the stickies-controlling enzymes, and then adding the stickies-controlling enzymes to the pulp to control the process parameters of the hydrolysis reaction system; the stickies are hydrolyzed into water-soluble low-molecular substances by the stickies-controlling enzymes, and the fine particle stickies and the hydrolyzed substances are wrapped and emulsified, so that the micro-particle stickies are stable in the system without agglomerating into large particles.

[0006] Optionally, when analyzing the main components of stickies in the pulp, waste pulp from different sections is sampled and analyzed, and the content and main components of the stickies in the waste pulp are determined by performing extraction experiments on the collected stickies.

[0007] Optionally, the process parameters include pH value, temperature, concentration and reaction time of enzyme treatment.

[0008] Optionally, the temperature of the enzyme treatment is between 40°C and 80°C.

[0009] Optionally, the pH value of the enzyme treatment is between 4-6.

[0010] Optionally, the reaction time of the enzyme treatment is 30-90 min.

[0011] Optionally, the stickies-controlling enzyme is esterase, lipase, pectinase, xylanase or modified cellulase.

[0012] Optionally, the concentration of the pulp is 10%-20%, and the concentration of the stickies controlling enzyme is 100-200 g / t.

[0013] Compared with the prior art, the present invention has the following beneficial effects: (1) In the present invention, the decomposition and oxidation reactions of biological enzymes with stickies are used to degrade the stickies and colloidal garbage of different compositions in the system, so that they are stably dispersed in water and effectively removed; (2) In the present invention, by detecting stickies in different types of pulp and paper machine white water in the actual production line of the workshop, the distribution state and distribution law of stickies in the papermaking system are systematically analyzed, and the method of bio-enzyme degradation is adopted, which can effectively control the stickies in the pulp and circulating white water, reduce the viscosity of the stickies, and reduce the impact on the pulp-water system. At the same time, it can improve the problems of sticking to the drying cylinder, paper spots, paper holes and other paper diseases caused by stickies, improve the quality of paper made from waste paper pulp, and finally achieve clean and efficient production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 is a schematic flow chart of a method for removing stickies from pulp according to an embodiment of the present invention; DETAILED DESCRIPTION

[0015] The present invention will now be further described in detail with reference to the accompanying drawings and embodiments. These drawings are simplified schematic diagrams that only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0016] Embodiment 1, as Figure 1 As shown, a method for removing stickies from pulp based on biodegradation, first analyzes the main components of stickies in the pulp, selects corresponding biological enzymes as stickies controlling enzymes according to the main components of stickies, then explores the process parameters of hydrolysis of stickies by the stickies controlling enzyme, and then adds the stickies controlling enzyme to the pulp to control the process parameters of the hydrolysis reaction system.

[0017] According to the main components of the stickies, the stickies control enzyme can be esterase, lipase, pectinase, xylanase or modified cellulase. The stickies are hydrolyzed into water-soluble low-molecular substances by the stickies control enzyme, and the fine particle stickies and the hydrolyzed substances are wrapped and emulsified, so that the fine particle stickies are stable in the system and do not aggregate into large particles, so that they are adsorbed on the fibers and taken out of the system.

[0018] As described above, the decomposition and oxidation reactions of biological enzymes with stickies are used to degrade the stickies and colloidal garbage of different compositions in the system, so that they are stably dispersed in water and effectively removed.

[0019] In order to fully understand the composition of waste paper pulp stickies and analyze the main components of stickies in pulp, waste paper pulp from different work sections is sampled and analyzed, and the content and main components of waste paper pulp stickies are determined by extraction experiments on the collected stickies.

[0020] By testing different types of pulps on the actual production line of the workshop and stickies in the white water of the paper machine, and systematically analyzing the distribution status and distribution pattern of stickies in the papermaking system, the method of bio-enzyme degradation can be used to effectively control stickies in pulp and circulating white water, reduce the viscosity of stickies, and reduce the impact on the pulp-water system. At the same time, it can improve the problems of sticking to the drying cylinder, paper spots, paper holes and other paper diseases caused by stickies, thereby improving the paper quality of waste pulp papermaking and ultimately achieving clean and efficient production.

[0021] Among them, extraction experiments in the papermaking field usually refer to experiments to extract specific substances or remove certain impurities from pulp or related raw materials. Its purpose is to determine the main components of stickies in the pulp in order to select corresponding biological enzymes that can carry out hydrolysis reactions. Commonly used extraction methods include organic solvent extraction, alkaline extraction and water extraction.

[0022] Organic solvent extraction: Organic solvents can selectively dissolve certain components in the pulp. For example, a toluene-ethanol mixed solvent can be used to extract non-polar or weakly polar substances such as resin and fat in the pulp. Because the molecular structure of these organic solvents is similar to that of resin, fat and other substances, according to the principle of "like dissolves like", they can be dissolved from the pulp and separated from other components such as cellulose.

[0023] Alkaline extraction: Generally, alkaline solutions such as sodium hydroxide and potassium hydroxide are used as extractants. Under alkaline conditions, lignin and other components in the pulp will undergo chemical reactions, and some chemical bonds in the lignin molecules will break, making it soluble in water and thus being extracted from the pulp. At the same time, alkaline conditions also help remove some acidic impurities.

[0024] Water extraction: Based on the solubility of certain substances in water, water can be used as an extractant to extract some water-soluble components in pulp, such as sugars, low-molecular organic acids, etc. These water-soluble components dissolve in water under the action of water and are separated from water-insoluble fiber components such as cellulose and hemicellulose.

[0025] Furthermore, process parameters include pH value, temperature, concentration and reaction time of enzyme treatment.

[0026] The hydrolysis reaction usually needs to be carried out within a certain temperature range, generally between 40°C and 80°C. Too high a temperature may lead to enzyme inactivation or pulp performance degradation, while too low a temperature will slow down the reaction rate. The pH value of the reaction system is strictly controlled to be within the optimal catalytic activity range of the selected acid, base or enzyme. For example, the optimal pH value of some enzymes may be between 4 and 6, while alkaline hydrolysis may require the pH value to be controlled at around 10-12.

[0027] The appropriate reaction time is determined according to the content and properties of the stickies, which generally ranges from 30 minutes to several hours. If the reaction time is too short, the stickies will not be completely hydrolyzed; if the reaction time is too long, the pulp fibers may be damaged. Therefore, the enzyme treatment reaction time here is set between 30-90 minutes.

[0028] In addition, taking the commonly used stickies control enzyme as an example, the addition amount is usually 100-200g / t (based on absolute dry pulp). The pulp concentration is generally controlled at about 10%-20% in the pulping stage. In the subsequent processes such as coarse screening, fine screening, flotation, and concentration, the pulp concentration will change. Usually, the pulp concentration after concentration will increase, generally reaching about 20%-40%. The specific concentration needs to be adjusted according to the requirements of the process and equipment.

[0029] If the content of stickies in the pulp is high, the structure of the stickies is complex or difficult to degrade, the enzyme concentration may need to be appropriately increased; conversely, if the content of stickies is low and easy to degrade, a lower enzyme concentration can be used. Pulps from different sources and batches may have different components and properties, and different demands for enzymes. For example, the types and qualities of recycled paper are different, and the types and amounts of stickies contained are different. The enzyme concentration needs to be adjusted according to the actual situation. In addition, if the environmental conditions such as the reaction temperature and pH value are not conducive to the activity of the enzyme, the enzyme concentration may need to be increased to ensure the hydrolysis effect; under suitable environmental conditions, the enzyme concentration can be appropriately reduced.

[0030] Embodiment 2: Based on embodiment 1, the present invention proposes a specific process of a method for removing stickies from pulp.

[0031] Stickies in pulp refer to a type of substance that can cause equipment to stick and affect paper quality during the pulping and papermaking process. Its main components include natural polymer compounds, artificial synthetic polymer compounds and other substances.

[0032] Natural polymer compounds mainly include lignin, hemicellulose and pectin. Lignin has a certain viscosity, especially in high temperature and high humidity environment, it is easy to soften and adhere, which affects the processing of pulp and the quality of paper. Hemicellulose has a certain hydrophilicity and viscosity, and may interact with other substances in pulp to form adhesives. Especially in some mechanical pulps or chemical mechanical pulps, the content of hemicellulose is relatively high, which is more likely to cause adhesive problems. Pectin has high viscosity and gelling properties. During the pulp preparation process, pectin may dissolve from plant fibers and combine with other components to form adhesives, affecting the filtration performance of pulp and the surface quality of paper.

[0033] Synthetic polymer compounds mainly include adhesives, coating polymers, and plastic fragments. In the process of waste paper recycling, due to the wide range of waste paper sources, it may contain various materials that have been used with adhesives, such as tapes, labels, glue, etc. These adhesives have various ingredients, and common ones include acrylic, polyurethane, epoxy resin and other polymer adhesives. They have strong viscosity and are difficult to be completely removed during the pulp processing process. They are easy to form adhesives, causing equipment blockage and paper quality defects.

[0034] Some papers are coated during the production process to improve the surface properties of the paper, such as glossiness and smoothness. Coating agents often contain various polymers, such as styrene-butadiene copolymer (SBR), acrylate copolymers, etc. When these coated papers are recycled and made into pulp, the coating polymers may fall off the surface of the paper and become part of the adhesives, affecting the quality and processing performance of the pulp.

[0035] Waste paper may contain some plastic fragments, such as plastic bags, plastic films, etc. These plastic fragments are difficult to be decomposed or broken into small particles during the pulp processing process. They will flow with the pulp and easily adhere to other substances to form larger adhesive particles, which will have a serious impact on the screening and purification processes of the pulp.

[0036] In addition, other substances include resin acids, fatty acids and their esters. Plant fibers contain a certain amount of fatty acids and their esters, such as palmitic acid, stearic acid, oleic acid, etc. During the pulping process, these fatty acids and their esters may be freed from the fibers and form tiny oil droplets in the pulp system. When these oil droplets aggregate to a certain extent, they will show stickiness and combine with other substances to form adhesives.

[0037] Resin acids are mainly found in coniferous wood, such as rosin acid and pimaric acid. Resin acids are acidic and sticky. If they are not properly handled during pulping, they will dissolve in the water phase and then re-precipitate in subsequent operations, combining with other substances to form adhesives, which will have an adverse effect on the quality of pulp and the production process. For the above-mentioned waste paper pulp containing fatty acids and their esters, the ester bonds of the stickies are decomposed by adding specific enzyme preparations in the pulper, and the temperature is controlled at 55°C, the pH value is 5.5, and the reaction time is 60 minutes. After subsequent pressure screen and centrifugal separation treatment, the removal rate of the stickies reached more than 85%, and the paper defects such as holes and spots were significantly reduced, and the paper's smoothness, strength and other properties were significantly improved.

[0038] Based on the principle of enzyme catalysis, specific enzymes can selectively identify specific chemical bonds in stickies and accelerate their hydrolysis reactions, converting the stickies into water-soluble or more easily removable substances. In this process, the polymers in the stickies undergo hydrolysis reactions under the action of water. For stickies containing hydrolyzable groups such as ester bonds and ether bonds, these chemical bonds will break under acidic conditions, and the polymer chains will be decomposed into smaller molecular fragments.

[0039] In summary, after the stickies in the pulp are treated by the method proposed in the present invention, as the stickies in the pulp water system are reduced, the average daily paper breaks are reduced from 4.1 times to 2.6 times, and the daily paper break time is reduced from 50 min to 32 min; the operating efficiency of the paper machine is improved from 95.1% to 95.6%, an increase of 0.5%, and the annual new production capacity is 1,500 tons; the stickies on the surface of the drying cylinder are reduced, the drying efficiency of the drying cylinder is improved, the average steam consumption of the drying section is reduced from 1.5t / t to 1.44t / t, and the steam consumption per ton of paper is reduced by 0.06 tons; the qualified rate of container board is greater than 98.5%, and the quality meets the requirements of GB / T 13024-2016 "Container Board" for superior products.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0042] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for removing stickies from pulp based on biodegradation, characterized in that: Firstly, the main components of stickies in pulp are analyzed, and the corresponding biological enzyme is selected as the stickies controlling enzyme according to the main components of stickies, and then the process parameters of the hydrolysis of stickies by the stickies controlling enzyme are explored, and then the stickies controlling enzyme is added to the pulp to control the process parameters of the hydrolysis reaction system; the stickies are hydrolyzed into water-soluble low-molecular substances by the stickies controlling enzyme, and the fine particle stickies and the hydrolyzed substances are wrapped and emulsified, so that the micro-particle stickies are stable in the system without agglomerating into large particles.

2. The method for removing stickies from pulp based on biodegradation according to claim 1, characterized in that: When analyzing the main components of stickies in paper pulp, waste paper pulp from different sections is sampled and analyzed, and the content and main components of the stickies in the waste paper pulp are determined by performing extraction experiments on the collected stickies.

3. The method for removing stickies from pulp based on biodegradation according to claim 1, characterized in that: The process parameters include pH value, temperature, concentration and reaction time of enzyme treatment.

4. The method for removing stickies from pulp based on biodegradation according to claim 3, characterized in that: The temperature of the enzyme treatment is between 40°C and 80°C.

5. The method for removing stickies from pulp based on biodegradation according to claim 4, characterized in that: The pH value of the enzyme treatment is between 4-6.

6. The method for removing stickies from pulp based on biodegradation according to claim 5, characterized in that: The reaction time of the enzyme treatment is 30-90 min.

7. The method for removing stickies from pulp based on biodegradation according to claim 1, characterized in that: The stickies-controlling enzyme is esterase, lipase, pectinase, xylanase or modified cellulase.

8. The method for removing stickies from pulp based on biodegradation according to any one of claims 3 to 7, characterized in that: The concentration of the pulp is 10%-20%, and the concentration of the stickies controlling enzyme is 100-200 g / t.

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