A production process for preparing viscose filaments from recycled pulp

Abstract

This invention discloses a production process for preparing viscose filaments from recycled pulp, belonging to the field of viscose filament production. Specifically, recycled pulp is used as the viscose raw material, and through specific controlled conditions, impurities such as non-biological chemical fibers, pigments, and metal ions are effectively removed from the recycled pulp. Simultaneously, by limiting the product indicators in each process, the process meets spinning requirements, achieving waste utilization, reducing emissions, ensuring the stability and sustainability of the viscose filament production process, and meeting the needs of large-scale production.

Description

Technical Field

[0001] This invention relates to a production process for viscose filaments, and more particularly to a production process for preparing viscose filaments using recycled pulp, belonging to the field of viscose filament production. Background Technology

[0002] The raw materials for viscose filament production mainly include dissolving pulps such as wood pulp, bamboo pulp, and cotton pulp, which makes the viscose filament production process have a huge demand for natural wood, bamboo, and cotton. Currently, the idea is to use pulp (also known as "recycled pulp") made from waste cotton / wood cellulose products or cut scraps as raw materials for viscose filament production, thus realizing waste utilization and turning waste into treasure.

[0003] However, recycled pulp differs significantly from traditional natural wood / bamboo / cotton pulp. For example, recycled pulp contains impurities such as insoluble dead fibers (i.e., non-biobased chemical fibers). After xanthation, viscose microscopy reveals that recycled pulp contains an average of about 30 more fibers / g than natural wood pulp, severely impacting viscose filtration performance. Recycled pulp also has higher pigment content, higher ash content, and iron content that is 50-300% higher than natural pulp. This accelerates the degradation of alkali cellulose, affecting the xanthation reaction and subsequent filtration. Therefore, under current filament production processes, suitable production conditions are not available.

[0004] The existing technology "CN108589293A A Method for Regenerating Silk" discloses the recycling of a large amount of silk scraps cut from textile enterprises, followed by reprocessing to recreate silk products. However, it is mainly applicable to the processing of scraps from the silk production process, and the recycled product is viscose staple fiber. "CN204644527U" aims to provide a waste viscose recycling system. While it fills the technological gap in existing waste adhesive recycling schemes that cannot reuse waste adhesive for viscose filament production, it involves directly adding filtered waste adhesive to normal viscose and then into a large-scale viscose production system for viscose filament production.

[0005] Therefore, there is an urgent need for a stable and sustainable production process for preparing viscose filaments using recycled pulp as raw material. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing technologies and proposes a production process for preparing viscose filaments from recycled pulp. In this technical solution, recycled pulp is used as the viscose raw material. Through specific controlled conditions, non-biological chemical fibers, pigments, metal ions, and other impurities in the recycled pulp are effectively removed. Simultaneously, by limiting the product indicators in each process, the spinning requirements are met, achieving waste utilization, reducing emissions, ensuring the stability and sustainability of the viscose filament production process, and meeting the needs of large-scale production.

[0007] To achieve the above technical objectives, the following technical solution is proposed: The primary objective of this technical solution is to propose a production process for preparing viscose filaments from recycled pulp, comprising the following steps: 1) Impregnation: The purchased recycled pulp is impregnated for 45-60 minutes under the conditions of an alkaline solution concentration of 200-230 g / L and a temperature of 40-50℃, and the pulp concentration is controlled at 3.5-4.2%; 2) Pressing: The soaked pulp is fed into a press to press and obtain alkali cellulose and pressing alkali liquor. The alkali cellulose content is controlled at 26-36% and the viscosity is 5.5-6.5 mpa.s to ensure the performance of subsequent xanthation reaction and the viscosity and filtration performance of the viscose. The obtained pressing alkali solution is transported to a nanofiltration membrane system to obtain filtered alkali solution and concentrated solution. The hemicellulose content in the nanofiltration alkali solution is controlled to be ≤4g / L and is reused in the impregnation process. The nanofiltration concentrated solution is used to neutralize the acidic wastewater generated in the spinning and refining processes, realizing the closed-loop utilization of waste alkali solution (nanofiltration alkali solution). 3) Aging: The obtained alkali cellulose is fed into a bidirectional spiral aging machine for depolymerization. The temperature inside the bidirectional spiral aging machine is controlled at 35-40℃, the humidity at 45-60%, and the temperature of the alkali cellulose conveying air at 15-20℃. The cellulose is oxidized and degraded in the alkaline medium until the degree of polymerization meets the process requirements, which is the basis for subsequent xanthation, dissolution, and filtration. 4) Xanthation: The depolymerized alkali cellulose is metered and then fed into the xanthation machine. The initial xanthation temperature is controlled at 27-30℃, and the duration is 50-60 minutes. Then, the xanthation reaction temperature is controlled at 28-30℃. The stirring speed in the xanthation machine is controlled using the following program: For the first 0-10 minutes, control the rotation speed to 7-12 r / min. 10-60 minutes, control the rotation speed of the second stage to 3-6 r / min; For 60-70 minutes, control the rotation speed in the third stage to be 10-15 r / min; 70-85 minutes, control the speed of the fourth stage to 16-20 r / min; Matching different rotation speeds at different process stages can improve xanthation uniformity and viscose filtration performance, yielding cellulose xanthate. The amount of CS2 added is 29.5-32% of the weight of cellulose methyl ester; so that alkali cellulose and CS2 can react fully to generate cellulose xanthate. 5) Dissolution: The cellulose xanthate is introduced into the dissolution tank and coarsely ground in the coarse grinder (i.e., the first dissolution). Then, it is transported by the transfer pump to the fine grinder (pressure ≥10mpa) for fine grinding (i.e., the second dissolution). After heat exchange, it is put back into the dissolution tank for dissolution (i.e., the second dissolution). The total time for the second dissolution is controlled to be 100-150min to obtain the adhesive solution. 6) Curing: After curing and filtering the viscose solution, continuous degassing is performed by spraying with room temperature air to obtain the spinning adhesive; Among them, filtration removes impurities such as trapped cellulose gel particles and dust; The waste adhesive solution generated during the filtration process shall be treated as follows: Add 60-70% demineralized water and 10-15% 45g / L sodium hydroxide solution to the waste adhesive solution to control the alkali content in the waste adhesive solution to 4-6%; then, use centrifugation to separate the solid and liquid, and obtain a concentrated solution with a total solid content of less than 40%, which is directly used to neutralize the acidic wastewater generated in viscose fiber production (spinning and refining processes); the resulting dilute alkali solution is directly used in the xanthation process, realizing the closed-loop recycling of waste adhesive solution; 7) Spinning: The spinning adhesive is introduced into a spinning machine and spun to obtain viscose filaments; a static mixer is used for spinning. Alternatively, the obtained spinning adhesive can be mixed with conventional viscose (wood pulp, etc.) at a ratio of 1-99% and then spun; or the spinning adhesive obtained in step 6) can be spun directly.

[0008] Furthermore, the production process for preparing viscose filaments from recycled pulp includes: first impregnation, first pressing, second impregnation, second pressing, aging, xanthation, dissolution, maturation and spinning, wherein the first impregnation process generates alkali cellulose, dissolves most of the hemicellulose, and causes the cellulose to absorb alkali and swell, which is beneficial for pressing; and the cellulose is depolymerized and some pigments are removed. The second impregnation process cleans the alkali cellulose containing hemicellulose, and dissolves the hemicellulose again to remove pigments.

[0009] The second objective of this technical solution is to provide a production system for preparing viscose filaments from recycled pulp, comprising: an impregnation tank, a press, an aging machine, a xanthation machine, a dissolving tank, a maturation tank, a filtration device, a defoaming machine, and a spinning machine, wherein the outlet of the pressing alkali solution of the press is connected to a nanofiltration membrane system, the outlet of the alkali solution filtered by the nanofiltration membrane system is connected to the impregnation tank, and the outlet of the concentrated solution of the nanofiltration membrane system is connected to an acidic wastewater treatment system. The aging machine is a bidirectional spiral aging machine, which includes an aging drum and discharge ports located on opposite sides of the aging drum. Each discharge port is fitted with a spiral feeder, and a weighing hopper is located behind the spiral feeder. The weighing hopper is located in front of the yellowing machine. The dissolving tank is equipped with a coarse grinder. The outlet of the dissolving tank is connected to the inlet of the maturation tank by a conveying pipe. The conveying pipe is equipped with a conveying pump, a fine grinder, and a heat exchanger. The conveying pump is located in front of the fine grinder and the heat exchanger is located behind the fine grinder. In addition, the conveying pipe is connected to the circulation port of the dissolving tank through a circulation pipe, which is located behind the heat exchanger. The waste adhesive outlet of the filtration device is connected to a waste adhesive recovery tank, which is connected to a demineralized water inlet pipe and a sodium hydroxide solution inlet pipe; the outlet of the waste adhesive recovery tank is connected to a centrifuge, the outlet of the centrifuge concentrate is connected to an acidic wastewater treatment system, and the outlet of the centrifuge dilute alkali solution is connected to a xanthation machine. The degassing machine is connected to an air jet unit; A continuous pathway for preparing viscose filaments using recycled pulp is formed between the impregnation tank, press, bidirectional spiral aging machine, xanthation machine, dissolving tank, maturation tank, filtration device, defoaming machine and spinning machine. The press, nanofiltration membrane system, impregnation tank, and acidic wastewater treatment system form a continuous pathway for the recovery and reuse of press alkali liquor; The filtration device, waste adhesive recovery tank, centrifuge, acidic wastewater treatment system and xanthation machine form a continuous pathway for the recycling and reuse of waste adhesive.

[0010] Preferably, a recovery slurry storage tank is provided on the front side of the impregnation tank. The impregnation tank includes a first impregnation tank and a second impregnation tank. The press includes a first press and a second press. The inlet of the first impregnation tank is connected to the outlet of the recovery slurry storage tank. The outlet of the first impregnation tank is connected to the inlet of the first press. The outlet of the first press is connected to the inlet of the second impregnation tank. The outlet of the second impregnation tank is connected to the inlet of the second press. The outlet of the second press is connected to the inlet of the aging machine. The alkali outlet of the first press is connected to the nanofiltration membrane system, the alkali outlet of the second press is connected to the alkali filter (180 mesh), and the filtrate outlet of the alkali filter is connected to the first impregnation tank. This setup improves the impregnation and pressing effect of materials made from recycled pulp, thereby improving the quality of depolymerization and ensuring the performance of subsequent xanthation reactions, viscose viscosity, and filtration performance.

[0011] Preferably, a pulp pump is installed between the impregnation tank and the press to smoothly and stably transport the pulp treated in the impregnation tank to the press, thereby ensuring the sustainability of viscose filament preparation using recycled pulp as raw material.

[0012] Preferably, there are two porridge pumps, which are connected in parallel.

[0013] Preferably, a spinning solution storage tank is provided between the defoamer and the spinning machine, the outlet of the defoamer is connected to the inlet of the spinning solution storage tank, and the outlet of the spinning solution storage tank is connected to the inlet of the spinning machine.

[0014] In this technical solution, depending on actual needs, corresponding regulating valves can be installed on the corresponding delivery pipes, and detectors, such as temperature sensors, can be installed on the corresponding equipment. The "normal temperature" in this technical solution refers to a temperature of 15-25℃.

[0015] The positional relationships such as "front side of workstation", "rear side of workstation", "above", and "between" involved in this technical solution are defined according to the actual usage conditions and are common terms in this technical field, as well as common terms used by those skilled in the art in actual use.

[0016] In the description of this technical solution, it should be noted that, unless otherwise explicitly specified and limited, the terms "setting" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] The beneficial effects of adopting this technical solution are as follows: I. This invention uses recycled pulp as viscose raw material and, through specific controlled conditions, effectively removes impurities such as non-biological chemical fibers, pigments, and metal ions from the recycled pulp (e.g., the impregnation and filtration processes solve the problem of impurities in the recycled pulp; the impregnation process removes β-fibers, γ-fibers, and some ash that affect viscose fiber production; in addition, the filtration process removes ash, swollen but undissolved fibers, insoluble dead fibers, and non-biological cellulose fibers from the pulp). Simultaneously, by limiting the product indicators in each process, it meets spinning requirements and enables mass production of viscose filaments. Furthermore, the filament indicators meet the national superior product standard (GB / T13758-2008), achieving waste utilization, reducing emissions, ensuring the stability and sustainability of the viscose filament production process, and meeting the requirements for large-scale production. Second, this invention enables the use of "recycled pulp" as a raw material for viscose production, reducing the environmental protection costs of waste glue treatment in the viscose fiber industry by 50%. This is an inevitable trend in the development of a circular economy in the viscose fiber industry and an important manifestation of sustainable development, circular economy development, and clean production. The innovative recycled pulp process technology applied to viscose filament is an important means of solving the problem of raw materials for virgin wood pulp and paper pulp, and is beneficial to the protection of the natural environment. Third, this invention not only uses recycled pulp as raw material to produce viscose filament, but also uses simple and mature technology to treat the pressing alkali liquor and waste glue liquor generated in the production process, and then directly reuses them in this spinning process, reducing emissions and realizing a circular economy. IV. In the production system of the invention, a continuous pathway for preparing viscose using recycled slurry as raw material is formed between the recycled slurry storage tank, impregnation tank, press, aging machine, xanthation machine, dissolving tank, maturation tank, filtration device, degassing machine, and viscose temporary storage tank. A continuous pathway for recycling and reusing nanofiltration alkali is formed between the press, nanofiltration membrane system, impregnation tank, and acidic wastewater treatment system. A continuous pathway for recycling and reusing waste viscose is formed between the filtration device, waste viscose recovery tank, centrifuge, acidic wastewater treatment system, and xanthation machine. Thus, not only is recycled slurry used as viscose raw material, but the produced... The viscose produced meets the requirements for spinning (e.g., producing viscose filaments with filament indicators meeting the national superior product standard (GB / T13758-2008)), realizes waste utilization, reduces emissions, ensures the stability and sustainability of viscose production processes, and meets the needs of large-scale production. Furthermore, it is an important means of solving the problem of raw materials for virgin wood pulp and paper pulp, which is beneficial to the protection of the natural environment. Moreover, the pressing alkali liquor and waste viscose liquor generated in the viscose preparation process can be directly recycled into this spinning process after simple and mature technical treatment, reducing emissions and achieving a circular economy. V. In the production system of the invention, the degassing machine is connected to an air jet unit. Compared with the existing vacuum steam degassing technology, it can not only effectively reduce energy consumption (for example, when producing 1 ton of viscose solution, it can save 42 kg of steam), but also increase the temperature difference inside the degassing machine by about ℃, which improves the stability of the subsequent spinning process. VI. In the production system of the invention, the acidic wastewater treatment system is connected to the acidic wastewater outlet of the spinning machine, and / or the acidic wastewater treatment system is connected to the acidic wastewater outlet of the refining machine. That is, the acidic wastewater generated in the spinning process and / or refining process is discharged to the acidic wastewater treatment system, and then neutralized by nanofiltration concentrate, so as to realize the recycling and reuse of pressing alkali, that is, to improve the environmental protection of viscose production. Attached Figure Description

[0018] Figure 1 This is a structural block diagram (I) of the present invention; Figure 2 This is a structural block diagram (II) of the present invention; Figure 3 This is a process flow diagram related to the present invention; Figure 4 This is a schematic diagram of the aging machine in this invention (right view); Figure 5 This is a schematic diagram of the structure of the impregnation tank in this invention; Figure 6 This is a schematic diagram (top view) of the structure of the impregnation tank in this invention; Figure 7 This is a photograph of the actual product in Example 9; Figure 8 This is a physical image of the product in Example 10 (I). Figure 9 This is a physical image of the product in Example 10 (II); In the diagram, 1. Impregnation tank, 101. First impregnation tank, 102. Second impregnation tank; 2. Press, 201. First press, 202. Second press; 3. Bidirectional screw aging machine, 31. Aging drum, 32. Discharge port, 33. Screw feeder; 4. Yellowing machine; 5. Dissolving tank, 51. Coarse grinder; 6. Maturation tank; 7. Filtration device; 8. Defoamer; 9. Recycled slurry storage tank; 10. Nanofiltration membrane system; 11. Acidic wastewater treatment system; 12. Waste adhesive recovery tank; 13. Demineralized water inlet. 14. Sodium hydroxide solution inlet pipe; 15. Centrifuge; 16. Air jet unit; 17. Adhesive storage tank; 18. Pulp pump; 19. Weighing hopper; 20. Circulation pipe; 21. Transfer pump; 22. Fine grinder; 23. Heat exchanger; 24. Alkali filter; 25. Outer tank; 251. Pulp feeding port; 252. Alkali inlet; 26. Inner tank; 27. Stirring mechanism; 271. Stirring shaft; 272. Moving blade; 273. Downward pressing blade; 28. Alkali inlet pipe; 29. ​​Stationary blade. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 This embodiment proposes a production process for preparing viscose filaments from recycled pulp, including the following steps: 1) Impregnation: The purchased recycled pulp is impregnated for 45 minutes under the conditions of an alkaline solution concentration of 200g / L and a temperature of 40℃, and the pulp concentration is controlled at 3.5%; 2) Pressing: The soaked pulp is fed into a press to press and obtain alkali cellulose and pressing alkali liquor. The alkali cellulose is controlled to have a methyl cellulose content of 26% and a viscosity of 5.5 mPa·s to ensure the performance of subsequent xanthation reaction and the viscosity and filtration performance of the viscose. The obtained pressing alkali solution is transported to a nanofiltration membrane system to obtain filtered alkali solution and concentrated solution. The hemicellulose content in the nanofiltration alkali solution is controlled to be ≤4g / L and is reused in the impregnation process. The nanofiltration concentrated solution is used to neutralize the acidic wastewater generated in the spinning and refining processes, realizing the closed-loop utilization of waste alkali solution (nanofiltration alkali solution). 3) Aging: The obtained alkali cellulose is fed into a bidirectional spiral aging machine for depolymerization. The temperature inside the bidirectional spiral aging machine is controlled at 35°C, the humidity at 45%, and the temperature of the alkali cellulose conveying air at 15°C. The cellulose is oxidized and degraded in the alkaline medium until the degree of polymerization meets the process requirements, which is the basis for subsequent xanthation, dissolution, and filtration. 4) Xanthation: The depolymerized alkali cellulose is metered and then fed into the xanthation machine. The initial xanthation temperature is controlled at 27℃ for 60 minutes; then, the xanthation reaction temperature is controlled at 28℃; and the stirring speed in the xanthation machine is controlled using the following program: From 0 to 10 minutes, control the rotation speed of the first stage to 7 r / min; 10-60 minutes, control the rotation speed of the second stage to 3 r / min; For 60-70 minutes, control the rotation speed in the third stage to 10 r / min; From 70 to 85 minutes, control the rotation speed of the fourth stage at 16 r / min. Matching different rotation speeds at different process stages can improve xanthation uniformity and viscose filtration performance, yielding cellulose xanthate. The amount of CS2 added is 29.5% of the weight of cellulose methyl ester; this allows alkali cellulose to react fully with CS2 to generate cellulose xanthate. 5) Dissolution: The cellulose xanthate is introduced into the dissolution tank and coarsely ground in the coarse grinder (i.e., the first dissolution). Then, it is transported by the transfer pump to the fine grinder (pressure ≥10mpa) for fine grinding (i.e., the second dissolution). After heat exchange, it is put back into the dissolution tank for dissolution (i.e., the second dissolution). The total time for the second dissolution is controlled to be 100min to obtain the adhesive solution. 6) Curing: After curing and filtering the viscose solution, continuous degassing is performed by spraying with room temperature air to obtain the spinning adhesive; Among them, filtration removes impurities such as cellulose gel particles and dust; ambient temperature air injection, compared with the existing vacuum steam degassing technology, can not only effectively reduce energy consumption (for example, when producing 1 ton of viscose solution, it can save 42 kg of steam), but also increase the temperature difference inside the degassing machine by about ℃, which improves the stability of subsequent spinning processes. The waste adhesive solution generated during the filtration process shall be treated as follows: Add 60% demineralized water and 10% 45g / L sodium hydroxide solution to the waste adhesive solution to control the alkali content in the waste adhesive solution to 4%; then, use centrifugation to separate the solid and liquid, and obtain a concentrated solution with a total solid content of less than 40%, which is directly used to neutralize the acidic wastewater generated in viscose fiber production (spinning and refining processes); the resulting dilute alkali solution is directly used in the xanthation process, realizing the closed-loop recycling of waste adhesive solution; 7) Spinning: The spinning adhesive is introduced into the spinning machine and spun to obtain viscose filaments; a static mixer is used for spinning. Alternatively, the obtained spinning adhesive can be mixed with conventional viscose (wood pulp, etc.) at a ratio of 1:99, and then spun.

[0021] Example 2 This embodiment proposes a production process for preparing viscose filaments from recycled pulp, including the following steps: 1) Impregnation: The purchased recycled pulp was impregnated for 60 minutes under the conditions of an alkaline solution concentration of 230 g / L and a temperature of 50°C, and the pulp concentration was controlled at 4.2%; 2) Pressing: The soaked pulp is fed into a press to press and obtain alkali cellulose and pressing alkali liquor. The alkali cellulose is controlled to have a cellulose content of 36% and a viscosity of 6.5 mpa.s to ensure the performance of subsequent xanthation reaction and the viscosity and filtration performance of the viscose. The obtained pressing alkali solution is transported to a nanofiltration membrane system to obtain filtered alkali solution and concentrated solution. The hemicellulose content in the nanofiltration alkali solution is controlled to be ≤4g / L and is reused in the impregnation process. The nanofiltration concentrated solution is used to neutralize the acidic wastewater generated in the spinning and refining processes, realizing the closed-loop utilization of waste alkali solution (nanofiltration alkali solution). 3) Aging: The obtained alkali cellulose is fed into a bidirectional spiral aging machine for depolymerization. The temperature inside the bidirectional spiral aging machine is controlled at 40℃, the humidity at 60%, and the temperature of the alkali cellulose conveying air at 20℃. The cellulose is oxidized and degraded in the alkaline medium until the degree of polymerization meets the process requirements, which is the basis for subsequent xanthation, dissolution, and filtration. 4) Xanthation: The depolymerized alkali cellulose is metered and then fed into the xanthation machine. The initial xanthation temperature is controlled at 30℃ for 50 minutes. The xanthation reaction temperature is then controlled at 30℃. The stirring speed in the xanthation machine is controlled using the following program: From 0 to 10 minutes, control the rotation speed of the first stage to 12 r / min; 10-60 minutes, control the rotation speed of the second stage to 6 r / min; For 60-70 minutes, control the rotation speed in the third stage to 15 r / min; 70-85 minutes, control the speed of the fourth stage to 20 r / min Matching different rotation speeds at different process stages can improve xanthation uniformity and viscose filtration performance, yielding cellulose xanthate. The amount of CS2 added is 32% of the weight of cellulose methyl ester; this allows alkali cellulose to react fully with CS2 to generate cellulose xanthate. 5) Dissolution: The cellulose xanthate is introduced into the dissolution tank and coarsely ground in the coarse grinder (i.e., the first dissolution). Then, it is transported by the transfer pump to the fine grinder (pressure ≥10mpa) for fine grinding (i.e., the second dissolution). After heat exchange, it is put back into the dissolution tank for dissolution (i.e., the second dissolution). The total time for the second dissolution is controlled to be 150min to obtain the adhesive solution. 6) Curing: After curing and filtering the viscose solution, continuous degassing is performed by spraying with room temperature air to obtain the spinning adhesive; Among them, filtration removes impurities such as cellulose gel particles and dust; ambient temperature air injection, compared with the existing vacuum steam degassing technology, can not only effectively reduce energy consumption (for example, when producing 1 ton of viscose solution, it can save 42 kg of steam), but also increase the temperature difference inside the degassing machine by about ℃, which improves the stability of subsequent spinning processes. The waste adhesive solution generated during the filtration process shall be treated as follows: Add 70% demineralized water and 15% 45g / L sodium hydroxide solution to the waste adhesive solution to control the alkali content in the waste adhesive solution to 6%; then, use centrifugation to separate the solid and liquid, and obtain a concentrated solution with a total solid content of less than 40%, which is directly used to neutralize the acidic wastewater generated in viscose fiber production (spinning and refining processes); the resulting dilute alkali solution is directly used in the xanthation process, realizing the closed-loop recycling of waste adhesive solution; 7) Spinning: The spinning adhesive is introduced into the spinning machine and spun to obtain viscose filaments; a static mixer is used for spinning. Alternatively, the obtained spinning adhesive can be mixed with conventional viscose (wood pulp, etc.) at a ratio of 99:1, and then spun.

[0022] Example 3 This embodiment proposes a production process for preparing viscose filaments from recycled pulp, including the following steps: 1) Impregnation: The purchased recycled pulp was impregnated for 48 minutes under the conditions of an alkaline solution concentration of 210 g / L and a temperature of 42°C, and the pulp concentration was controlled at 3.7%; 2) Pressing: The soaked pulp is fed into a press to press and obtain alkali cellulose and pressing alkali liquor. The alkali cellulose is controlled to have a cellulose content of 30% and a viscosity of 5.8 mpa.s to ensure the performance of subsequent xanthation reaction and the viscosity and filtration performance of the viscose. The obtained pressing alkali solution is transported to a nanofiltration membrane system to obtain filtered alkali solution and concentrated solution. The hemicellulose content in the nanofiltration alkali solution is controlled to be ≤4g / L and is reused in the impregnation process. The nanofiltration concentrated solution is used to neutralize the acidic wastewater generated in the spinning and refining processes, realizing the closed-loop utilization of waste alkali solution (nanofiltration alkali solution). 3) Aging: The obtained alkali cellulose is fed into a bidirectional spiral aging machine for depolymerization. The temperature inside the bidirectional spiral aging machine is controlled at 37°C, the humidity at 48%, and the temperature of the alkali cellulose conveying air at 17°C. The cellulose is oxidized and degraded in the alkaline medium until the degree of polymerization meets the process requirements, which is the basis for subsequent xanthation, dissolution, and filtration. 4) Xanthation: The depolymerized alkali cellulose is metered and then fed into the xanthation machine. The initial xanthation temperature is controlled at 28℃ for 54 minutes; then, the xanthation reaction temperature is controlled at 29℃; and the stirring speed in the xanthation machine is controlled using the following program: From 0 to 10 minutes, control the rotation speed of the first stage to 10 r / min; 10-60 minutes, control the rotation speed of the second stage to 4 r / min; For 60-70 minutes, control the rotation speed in the third stage to 12 r / min; From 70 to 85 minutes, control the rotation speed of the fourth stage at 17 r / min. Matching different rotation speeds at different process stages can improve xanthation uniformity and viscose filtration performance, yielding cellulose xanthate. The amount of CS2 added is 30.5% of the weight of cellulose methyl ester; this allows alkali cellulose to react fully with CS2 to generate cellulose xanthate. 5) Dissolution: The cellulose xanthate is introduced into the dissolution tank and coarsely ground in the coarse grinder (i.e., the first dissolution). Then, it is transported by the transfer pump to the fine grinder (pressure ≥10mpa) for fine grinding (i.e., the second dissolution). After heat exchange, it is put back into the dissolution tank for dissolution (i.e., the second dissolution). The total time for the second dissolution is controlled to be 100-150min to obtain the adhesive solution. 6) Curing: After curing and filtering the viscose solution, continuous degassing is performed by spraying with room temperature air to obtain the spinning adhesive; Among them, filtration removes impurities such as cellulose gel particles and dust; ambient temperature air injection, compared with the existing vacuum steam degassing technology, can not only effectively reduce energy consumption (for example, when producing 1 ton of viscose solution, it can save 42 kg of steam), but also increase the temperature difference inside the degassing machine by about ℃, which improves the stability of subsequent spinning processes. The waste adhesive solution generated during the filtration process shall be treated as follows: Add 66% demineralized water and 11% sodium hydroxide solution (45 g / L) to the waste adhesive solution to control the alkali content in the waste adhesive solution to 4.5%. Then, use centrifugation to separate the solid and liquid components to obtain a concentrated solution with a total solid content of less than 40%, which is directly used to neutralize the acidic wastewater generated in viscose fiber production (spinning and refining processes). The resulting dilute alkali solution is directly used in the xanthation process, realizing the closed-loop recycling of the waste adhesive solution. 7) Spinning: The spinning adhesive is introduced into the spinning machine and spun to obtain viscose filaments; a static mixer is used for spinning. Alternatively, the obtained spinning adhesive can be mixed with conventional viscose (wood pulp, etc.) in a 50:50 ratio, and then spun.

[0023] Example 4 This embodiment proposes a production process for preparing viscose filaments from recycled pulp, including the following steps: 1) Impregnation: The purchased recycled pulp was impregnated for 58 minutes under the conditions of an alkaline solution concentration of 220 g / L and a temperature of 48°C, with the pulp concentration controlled at 4.1%; 2) Pressing: The soaked pulp is fed into a press to press and obtain alkali cellulose and pressing alkali liquor. The alkali cellulose is controlled to have a cellulose content of 34% and a viscosity of 6.3 mpa.s to ensure the performance of subsequent xanthation reaction and the viscosity and filtration performance of the viscose. The obtained pressing alkali solution is transported to a nanofiltration membrane system to obtain filtered alkali solution and concentrated solution. The hemicellulose content in the nanofiltration alkali solution is controlled to be ≤4g / L and is reused in the impregnation process. The nanofiltration concentrated solution is used to neutralize the acidic wastewater generated in the spinning and refining processes, realizing the closed-loop utilization of waste alkali solution (nanofiltration alkali solution). 3) Aging: The obtained alkali cellulose is fed into a bidirectional spiral aging machine for depolymerization. The temperature inside the bidirectional spiral aging machine is controlled at 38°C, the humidity at 58%, and the temperature of the alkali cellulose conveying air at 19°C. The cellulose is oxidized and degraded in the alkaline medium until the degree of polymerization meets the process requirements, which is the basis for subsequent xanthation, dissolution, and filtration. 4) Xanthation: The depolymerized alkali cellulose is metered and then fed into the xanthation machine. The initial xanthation temperature is controlled at 29℃ for 58 minutes. The xanthation reaction temperature is then controlled at 29℃. The stirring speed in the xanthation machine is controlled using the following program: From 0 to 10 minutes, control the rotation speed of the first stage to 10 r / min; 10-60 minutes, control the rotation speed of the second stage to 6 r / min; For 60-70 minutes, control the rotation speed in the third stage to 14 r / min; From 70 to 85 minutes, control the rotation speed of the fourth stage at 19 r / min. Matching different rotation speeds at different process stages can improve xanthation uniformity and viscose filtration performance, yielding cellulose xanthate. The amount of CS2 added is 30.0% of the weight of cellulose methyl ester; so that alkali cellulose and CS2 can react fully to generate cellulose xanthate. 5) Dissolution: The cellulose xanthate is introduced into the dissolution tank and coarsely ground in the coarse grinder (i.e., the first dissolution). Then, it is transported by the transfer pump to the fine grinder (pressure ≥10mpa) for fine grinding (i.e., the second dissolution). After heat exchange, it is put back into the dissolution tank for dissolution (i.e., the second dissolution). The total time for the second dissolution is controlled to be 145min to obtain the adhesive solution. 6) Curing: After curing and filtering the viscose solution, continuous degassing is performed by spraying with room temperature air to obtain the spinning adhesive; Among them, filtration removes impurities such as cellulose gel particles and dust; ambient temperature air injection, compared with the existing vacuum steam degassing technology, can not only effectively reduce energy consumption (for example, when producing 1 ton of viscose solution, it can save 42 kg of steam), but also increase the temperature difference inside the degassing machine by about ℃, which improves the stability of subsequent spinning processes. The waste adhesive solution generated during the filtration process shall be treated as follows: Add 68% demineralized water and 14% sodium hydroxide solution (45 g / L) to the waste adhesive solution to control the alkali content in the waste adhesive solution to 5%. Then, use centrifugation to separate the solid and liquid components to obtain a concentrated solution with a total solid content of less than 40%, which is directly used to neutralize the acidic wastewater generated in viscose fiber production (spinning and refining processes). The resulting dilute alkali solution is directly used in the xanthation process to achieve closed-loop recycling of the waste adhesive solution. 7) Spinning: The spinning adhesive is introduced into the spinning machine, and spinning is performed to obtain viscose filaments; a static mixer is used for spinning. Alternatively, the obtained spinning adhesive can be spun directly.

[0024] Example 5 Based on Examples 1-4, the production process for preparing viscose filaments from recycled pulp involved in this example can also be: The process includes first impregnation, first pressing, second impregnation, second pressing, aging, xanthation, dissolution, maturation and spinning. The first impregnation process generates alkali cellulose, dissolves most of the hemicellulose, and causes the cellulose to absorb alkali and swell, which is beneficial for pressing. In addition, the cellulose is depolymerized and some pigments are removed. The second impregnation process cleans the alkali cellulose containing hemicellulose, and dissolves the hemicellulose again to remove pigments.

[0025] Among them, recycled pulp refers to pulp made from waste cotton / wood cellulose products or cut scraps, which can be purchased directly. The relevant indicators are shown in Table 1 below.

[0026] Example 6 This embodiment proposes a suitable production system for preparing viscose filaments from recycled pulp, such as... Figure 1 As shown, it includes: impregnation tank 1, press 2, aging machine, xanthation machine 4, dissolving tank 5, maturation tank 6, filtration device 7, defoaming machine 8, and spinning machine. The pressing alkali outlet of the press 2 is connected to the nanofiltration membrane system 10 (nanofiltration membrane precision ≤ 2 nanometers), the alkali outlet of the nanofiltration membrane system 10 is connected to the impregnation tank 1, and the concentrated liquid outlet of the nanofiltration membrane system 10 is connected to the acidic wastewater treatment system 11. The aging machine is a bidirectional spiral aging machine 3, which includes an aging drum 31 and discharge ports 32 located on opposite sides of the aging drum 31 (e.g., Figure 4 As shown, each discharge port 32 is equipped with a screw conveyor 33 to ensure that the material is discharged in two directions to the curing drum 31, thereby improving the uniformity of material curing. A weighing hopper 19 is set behind the station of the screw conveyor 33 and in front of the station of the curing machine 4; the weighing hopper 19 measures the material entering the curing machine 4, thereby ensuring the controllability and stability of the curing process; A coarse grinder 51 is installed inside the dissolving tank 5. The outlet of the dissolving tank 5 is connected to the inlet of the maturation tank 6 via a conveying pipe. A conveying pump 21, a fine grinder 22, and a heat exchanger 23 are installed on the conveying pipe. The conveying pump 21 is located in front of the fine grinder 22, and the heat exchanger 23 is located behind the fine grinder 22. In addition, the conveying pipe is connected to the circulation port of the dissolving tank 5 via a circulation pipe 20, which is located behind the heat exchanger 23, effectively improving the dissolving efficiency and quality. The waste adhesive outlet of the filter device 7 is connected to the waste adhesive recovery tank 12, and the waste adhesive recovery tank 12 is connected to the demineralized water inlet pipe 13 and the sodium hydroxide solution inlet pipe 14; the outlet of the waste adhesive recovery tank 12 is connected to the centrifuge 15, the concentrated liquid outlet of the centrifuge 15 is connected to the acidic wastewater treatment system 11, and the dilute alkali liquid outlet of the centrifuge 15 is connected to the xanthation machine 4. The degassing machine 8 is connected to the air jet unit 16; A continuous pathway for preparing viscose filaments using recycled pulp is formed between the impregnation tank 1, the press 2, the bidirectional spiral aging machine 3, the xanthation machine 4, the dissolving tank 5, the maturation tank 6, the filtration device 7, the defoaming machine 8, and the spinning machine. The press 2, nanofiltration membrane system 10, impregnation tank 1 and acidic wastewater treatment system 11 form a continuous pathway for the recovery and reuse of press alkali liquor; The filter device 7, waste adhesive recovery tank 12, centrifuge 15, acidic wastewater treatment system 11 and xanthation machine 4 form a continuous pathway for the recycling and reuse of waste adhesive.

[0027] The acidic wastewater treatment system 11 is connected to the acidic wastewater outlet of the spinning machine, and / or the acidic wastewater treatment system 11 is connected to the acidic wastewater outlet of the refining machine. The acidic wastewater generated during the spinning and / or refining processes is discharged to the acidic wastewater treatment system 11, where it is then neutralized by nanofiltration concentrate, achieving the recovery and reuse of the pressing alkali solution.

[0028] In addition, a spinning solution storage tank is provided between the degassing machine 8 and the spinning machine. The outlet of the degassing machine 8 is connected to the inlet of the spinning solution storage tank, and the outlet of the spinning solution storage tank is connected to the inlet of the spinning machine.

[0029] Example 7 Based on Example 6, this example further specifies the requirements for the quantity and arrangement of the impregnation tank 1 and the press 2 according to the process requirements for preparing viscose using recycled slurry as raw material, so as to further explain the technical solution.

[0030] like Figure 2-3 As shown, a recovery slurry storage tank 9 is provided on the front side of the station of the impregnation tank 1. The impregnation tank 1 includes a first impregnation tank 101 and a second impregnation tank 102. The press 2 includes a first press 201 and a second press 202. The inlet of the first impregnation tank 101 is connected to the outlet of the recovery slurry storage tank 9. The outlet of the first impregnation tank 101 is connected to the inlet of the first press 201. The outlet of the first press 201 is connected to the inlet of the second impregnation tank 102. The outlet of the second impregnation tank 102 is connected to the inlet of the second press 202. The outlet of the second press 202 is connected to the inlet of the aging machine. The alkali outlet of the first press 201 is connected to the nanofiltration membrane system 10, the alkali outlet of the second press 202 is connected to the alkali filter 24 (180 mesh), and the filtrate outlet of the alkali filter 24 is connected to the first impregnation tank 101. This arrangement improves the impregnation and pressing effect of the material using recycled pulp as raw material, that is, improves the depolymerization quality and ensures the performance of subsequent xanthation reaction, viscosity of viscose and filtration performance.

[0031] Furthermore, two pulp pumps 18 are installed between the first impregnation tank 101 and the first press 201, and these pumps are connected in parallel. Similarly, two pulp pumps 18 are installed between the second impregnation tank 102 and the second press 202, and these pumps are also connected in parallel. This ensures that the pulp treated in the impregnation tank 1 is smoothly and stably transported to the first press 201 / second press 202, thereby guaranteeing the sustainability of viscose preparation using recycled pulp as raw material.

[0032] Example 8 Based on Examples 6-7, this example further defines the impregnation tank 1 to overcome the problems of clogging at the feeding port and slurry accumulation in the production process of preparing viscose filaments from recycled slurry, in order to further explain the technical solution.

[0033] The impregnation tank 1 includes an outer tank body 25, an inner tank body 26 with openings at both ends, and a stirring mechanism 27. The top of the outer tank body 25 is equipped with a pulp feeding port 251 and an alkali inlet 252. The alkali inlet 252 is connected to an alkali inlet pipe 28, which extends into the outer tank body 25 through the alkali inlet 252. The outlet of the alkali inlet pipe 28 is located directly below the pulp feeding port 251. The angle between the discharge direction of the pulp feeding port 251 and the discharge direction of the alkali inlet pipe 28 is less than 90°, allowing some of the alkali entering the outer tank body 25 to impact the pulp feeding port 251, effectively reducing blockage at the pulp feeding port 251 by 80%. To address the problem of pulp accumulation and improve the soaking effect, the inner barrel 26 is vertically positioned in the middle of the outer barrel 25. The lower part of the inner barrel 26 is equipped with stationary blades 29 for crushing the pulp, which are fixedly mounted on the inner wall. The stirring mechanism 27 includes a stirring shaft 271 and blade assemblies distributed on the stirring shaft 271, which vertically penetrates the inner barrel 26. The blade assembly is located inside the inner barrel 26 and includes a moving blade 272 for crushing the pulp and a pressing blade 273 for pushing the pulp outward from the inner barrel 26. The moving blade 272 is positioned above the pressing blade 273 and the stationary blades 29.

[0034] Furthermore, the positional and size relationships between the inner barrel 26 and the outer barrel 25 are further defined, specifically: the distance between the upper end face of the inner barrel 26 and the top end face of the outer barrel 25 is 100-150cm, which increases the spacing between the inner barrel 26 and the outer barrel 25 under the constraints of cost and effect, preventing pulp from splashing to the top and forming weathered alkali fibers; the distance between the lower end face of the inner barrel 26 and the bottom end face of the outer barrel 25 is 40-60cm, ensuring that the two end faces form a cavity, allowing the pulp to roll outward from the bottom of the inner barrel 26 to form a circulation, which effectively improves the uniformity of mixing of alkali solution and pulp, ensures complete formation of alkali cellulose, and promotes a good impregnation effect of this impregnation tank 1; The distance between the outer wall of the inner barrel 26 and the inner wall of the outer barrel 25 is 30-50cm, forming a circulation channel between the inner barrel 26 and the outer barrel 25, which facilitates the porridge to roll out from the bottom of the inner barrel 26 and then roll back into the inner barrel 26, forming a circulation. The inner diameter of the outer cylinder is 1.6-2.0 times the inner diameter of the inner cylinder 26. On the one hand, this ensures that the outer wall of the inner cylinder 26 and the inner wall of the outer cylinder 25 form a cavity, which facilitates the slurry to roll outward from the bottom of the inner cylinder 26 and then back into the inner cylinder 26, forming a circulation. On the other hand, the outer cylinder 25 is not only used to install the inner cylinder 26, but also to receive the slurry rolling outward from the bottom of the inner cylinder 26, thus improving the stability and orderliness of the impregnation process.

[0035] Furthermore, the stationary blades 29 and the pressing blades 273 are further defined, specifically including: the number of stationary blades 29 is at least two, the number of pressing blades 273 is at least two, and the stationary blades 29 and pressing blades are arranged adjacent to each other, such as: the first pressing blade is below the first stationary blade 29, the first stationary blade 29 is below the second pressing blade, the second pressing blade is below the second stationary blade 29, and so on, to improve the pulp crushing efficiency and quality in the inner barrel 26, and also to improve the material circulation between the inner barrel 26 and the outer barrel 25. The pulp is tumbling in the inner barrel 26, so that the alkali solution and pulp are mixed evenly and completely, ensuring complete formation of alkali cellulose, that is, ensuring good impregnation effect of this impregnation tank 1. Preferably, the number of stationary blades 29 is less than the number of pressing blades, further crushing the incompletely dissolved pulp and improving the impregnation effect.

[0036] For this technical solution, such as Figure 5-6 As shown, the work process involved includes: 1. The recycled pulp is fed into the pulp feeding port 251, and the alkali solution is added into the alkali solution inlet 252. The portion of the alkali solution entering the outer tank 25 impacts the pulp feeding port 251, which can effectively reduce the problems of clogging and pulp accumulation at the pulp feeding port 251 by 80% and improve the impregnation effect. 2. Inside the impregnation tank 1, the pulp comes into contact with and reacts with the alkali solution, generating a pulp porridge containing alkali cellulose. Then, through the action of the stationary blade 29 and the stirring mechanism 27, the pulp porridge is tumbled from the bottom of the inner tank 26 outwards and back into the inner tank 26, forming a cycle. This improves the efficiency of the pulp and alkali solution reaction and ensures complete alkali cellulose formation. Specifically, the moving blade 272 is mainly used to cut the pulp board paper fed into the pulp inlet 251 and to feed the pulp board paper into the inner tank 26; the downward pressing blade 273 is used to push the pulp inside the inner tank 26 downwards / outwards; and the stationary blade 29 is used to crush the pulp inside the inner tank 26, thereby achieving the impregnation effect.

[0037] Example 9 This embodiment uses 113 tons of recycled pulp as raw material to produce 1130 tons of viscose fiber as an example. The process involved is the same as in embodiment 3, in order to further illustrate this technical solution.

[0038] Among them, 1) Commissioning time: November 2022; 2) Viscose filament products: 116D; 3) Product specifications are shown in Table 2, and the products involved are as follows: Figure 7 As shown.

[0039] Example 10 This embodiment uses 0.8 tons of recycled pulp as raw material to produce 7 tons of viscose fiber. The process involved is the same as in embodiment 3, in order to further illustrate this technical solution.

[0040] Among them, 1) Commissioning time: December 2021; 2) Viscose filament product: 116D; 3) Product specifications are shown in Table 3, and the products involved are as follows: Figure 8-9 As shown.

Claims

1. A production process for preparing viscose filament from recycled pulp, comprising the steps of impregnation, pressing, aging, xanthation, dissolution, curing, filtration, defoaming, and spinning, characterized in that: In the impregnation process, recycled pulp is used as raw material, and impregnation is carried out for 45-60 minutes under the conditions of an alkaline solution concentration of 200-230 g / L and a temperature of 40-50℃, while controlling the pulp concentration to be 3.5-4.2%. The recycled slurry had a viscosity of 20 mPa·s, a fiber content of 95.3%, an ash content of 0.13%, an iron content of 15 ppm, a moisture content of 8.5%, an S10 content of 5.65%, and an S18 content of 4.87%. An impregnation tank (1) is used. The impregnation tank (1) includes an outer tank body (25), an inner tank body (26) with openings at both ends, and a stirring mechanism (27). The top of the outer tank body (25) is provided with a pulp feeding port (251) and an alkali inlet (252). The alkali inlet (252) is connected to an alkali inlet pipe (28). The alkali inlet pipe (28) extends through the alkali inlet (252) into the outer tank body (25). The outlet of the alkali inlet pipe (28) is located directly below the pulp feeding port (251). The angle between the discharge direction of the pulp feeding port (251) and the discharge direction of the alkali inlet pipe (28) is <90°. The inner tank body (26) is set vertically. In the middle of the outer barrel (25), the lower part of the inner barrel (26) is provided with stationary blades (29) for crushing pulp. The stationary blades (29) are fixedly installed on the inner wall. The stirring mechanism (27) includes a stirring shaft (271) and a blade assembly distributed on the stirring shaft (271). The stirring shaft (271) runs vertically through the inner barrel (26). The blade assembly is located inside the inner barrel (26). The blade assembly includes a moving blade (272) for crushing pulp and a pressing blade (273) for pushing the pulp in the inner barrel (26) outward. The moving blade (272) is located above the pressing blade (273) and the stationary blade (29). During the pressing process, the methyl cellulose content in the obtained alkali cellulose is controlled to be 26-36%, and the viscosity is 5.5-6.5 mPa·s; In the aging process, a bidirectional spiral aging machine (3) is used for depolymerization, and the temperature inside the bidirectional spiral aging machine (3) is controlled at 35-40℃, the humidity at 45-60%, and the temperature of the alkali cellulose conveying air at 15-20℃. In the xanthation process, the initial xanthation temperature is controlled at 27-30℃, and the duration is 50-60 min; then, the xanthation reaction temperature is controlled at 28-30℃; and the stirring speed in the xanthation machine (4) is controlled according to the following program: For the first 0-10 minutes, control the rotation speed to 7-12 r / min. 10-60 minutes, control the rotation speed of the second stage to 3-6 r / min; For 60-70 minutes, control the rotation speed in the third stage to be 10-15 r / min; 70-85 minutes, control the speed of the fourth stage to 16-20 r / min; The amount of CS2 added is calculated as 29.5-32% of the weight of methyl cellulose; In the dissolution process, the cellulose xanthate obtained by the xanthation process is introduced into the dissolution tank (5), coarsely ground by the coarse grinder (51) in the dissolution tank (5), and then transported by the transfer pump (21) to the fine grinder (22) for fine grinding. After heat exchange, it is then introduced into the dissolution tank (5) for redissolution. The total time for the second dissolution is controlled to be 100-150 min to obtain the adhesive solution. In the degassing process, room temperature air is used for degassing. In addition, the pressing alkali obtained by the pressing process is transported to the nanofiltration membrane system (10) to obtain nanofiltration alkali and nanofiltration concentrate, wherein the hemicellulose content in the nanofiltration alkali is controlled to be ≤4g / L and is directly recycled for the impregnation process; the nanofiltration concentrate is directly used to neutralize the acidic wastewater generated by the spinning process and / or refining process. The waste adhesive solution generated during the filtration process is treated as follows: Add 60-70% demineralized water and 10-15% 45g / L sodium hydroxide solution to the waste adhesive solution to control the alkali content in the waste adhesive solution to 4-6%. Then, use centrifugation to separate the solid and liquid components to obtain a concentrated solution with a total solid content of less than 40% and a dilute alkali solution. The concentrated solution is used directly to neutralize the acidic wastewater generated in the spinning and refining processes, and the dilute alkali solution is used directly in the xanthation process.

2. The production process for preparing viscose filaments from recycled pulp according to claim 1, characterized in that: The production process for preparing viscose filaments from recycled pulp includes: first impregnation, first pressing, second impregnation, second pressing, aging, xanthation, dissolution, maturation, filtration, defoaming and spinning.

3. The production process for preparing viscose filaments from recycled pulp according to claim 1, characterized in that: In the spinning process, a static mixer is used for spinning.

4. The production process for preparing viscose filaments from recycled pulp according to any one of claims 1-3, characterized in that: The production system includes the impregnation tank (1), press (2), aging machine, xanthation machine (4), dissolving tank (5), maturation tank (6), filtration device (7), defoaming machine (8) and spinning machine. The pressing alkali outlet of the press (2) is connected to the nanofiltration membrane system (10). The alkali outlet of the nanofiltration membrane system (10) is connected to the impregnation tank (1). The concentrated liquid outlet of the nanofiltration membrane system (10) is connected to the acidic wastewater treatment system (11). The aging machine is a bidirectional spiral aging machine (3). The bidirectional spiral aging machine (3) includes an aging drum (31) and discharge ports (32) located on opposite sides of the aging drum (31). Each discharge port (32) is fitted with a spiral discharge device (33). A weighing hopper (19) is located behind the station of the spiral discharge device (33). The weighing hopper (19) is located in front of the station of the yellowing machine (4). A coarse grinder (51) is installed inside the dissolving tank (5). The outlet of the dissolving tank (5) is connected to the inlet of the maturation tank (6) by a conveying pipe. A conveying pump (21), a fine grinder (22) and a heat exchanger (23) are installed on the conveying pipe. The conveying pipe is connected to the circulation port of the dissolving tank (5) through a circulation pipe (20). The waste glue outlet of the filter device (7) is connected to the waste glue recovery tank (12), and the waste glue recovery tank (12) is connected to the demineralized water inlet pipe (13) and the sodium hydroxide solution inlet pipe (14); the outlet of the waste glue recovery tank (12) is connected to the centrifuge (15), the concentrated liquid outlet of the centrifuge (15) is connected to the acidic wastewater treatment system (11), and the dilute alkali liquid outlet of the centrifuge (15) is connected to the xanthation machine (4); The degassing machine (8) is connected to an air jet unit (16); A continuous pathway for preparing viscose filaments using recycled pulp is formed between the impregnation tank (1), the press (2), the bidirectional spiral aging machine (3), the xanthation machine (4), the dissolving tank (5), the maturation tank (6), the filtration device (7), the defoaming machine (8), and the spinning machine. The press (2), nanofiltration membrane system (10), impregnation tank (1) and acid wastewater treatment system (11) form a continuous pathway for the recovery and reuse of press alkali liquor; The filter device (7), waste adhesive recovery tank (12), centrifuge (15), acidic wastewater treatment system (11) and xanthation machine (4) form a continuous pathway for the recycling and reuse of waste adhesive.

5. The production process for preparing viscose filaments from recycled pulp according to claim 4, characterized in that: The impregnation tank (1) is provided with a recovery slurry storage tank (9) at the front of the work station. The impregnation tank (1) includes a first impregnation tank (101) and a second impregnation tank (102). The press (2) includes a first press (201) and a second press (202). The inlet of the first impregnation tank (101) is connected to the outlet of the recovery slurry storage tank (9). The outlet of the first impregnation tank (101) is connected to the inlet of the first press (201). The outlet of the first press (201) is connected to the inlet of the second impregnation tank (102). The outlet of the second impregnation tank (102) is connected to the inlet of the second press (202). The outlet of the second press (202) is connected to the inlet of the aging machine. The alkali outlet of the first press (201) is connected to the nanofiltration membrane system (10), the alkali outlet of the second press (202) is connected to the alkali filter (24), and the filtrate outlet of the alkali filter (24) is connected to the first impregnation tank (101).

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