Waste-utilization environment-friendly shield tail sealing grease and preparation method thereof

Abstract

The invention discloses waste-utilization environment-friendly shield tail sealing grease and a preparation method thereof, and relates to the technical field of shield tail sealing grease, the sealing grease is composed of base oil, Fischer-Tropsch wax, modified organopolysiloxane, modified xanthan gum, a fiber reinforcing agent, a filler and a modified additive; the base oil is treated waste edible vegetable oil, and the specific treatment steps comprise impurity removal, dehydration, deacidification, chemical modification and product purification; the environment-friendly shield tail sealing grease utilizing the waste materials has good stratum adaptability and can meet the requirements for shield tail sealing of different stratums, and the shield tail sealing grease does not need to be additionally replaced when the shield tail sealing grease is constructed to the different stratums; according to the environment-friendly shield tail sealing grease, the treated waste edible vegetable oil is adopted as the base oil, the reinforcing agent is prepared from agricultural plant fibers, the shield tail sealing grease does not affect soil and water in a construction section after construction, and the shield tail sealing grease can be degraded subsequently and is safe and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of shield tail sealing grease technology, specifically to an environmentally friendly shield tail sealing grease that utilizes waste materials and its preparation method. Background Technology

[0002] In shield tunnel construction, tail sealing is a crucial aspect of the project. Failure of the tail seal can disrupt construction, impact the project schedule, and in severe cases, lead to serious safety accidents such as casualties. Tail sealing grease is consumed in large quantities during shield tunnel construction, averaging approximately 300-400 kg per 2.1 meters of excavation. Furthermore, as a disposable consumable, this grease adheres to the outer wall of the tunnel segments and remains in the underground environment. Therefore, environmentally friendly tail sealing greases with excellent performance and cost-effectiveness are urgently needed in shield tunnel construction. However, existing tail sealing greases have the following problems: First, existing shield tail sealing grease products often sacrifice some performance or cost-effectiveness while ensuring environmental performance. Most environmentally friendly shield tail sealing greases are produced using vegetable oils, mineral fillers, and natural fibers. Their balance between performance such as water pressure sealing and pumping performance and cost-effectiveness is often poor, and cost control remains an urgent issue to be addressed.

[0003] Secondly, existing shield tail sealing greases lack products and corresponding processes for production using agricultural waste. Waste utilization has always been a common concern in the engineering construction field and other industries. Achieving waste reuse in engineering construction not only helps promote environmental protection but is also an important part of saving construction costs.

[0004] Third, existing shield tail sealing greases lack a sufficient balance between resistance to water flow erosion, water pressure sealing performance, and pumpability. In practical engineering, the stable and effective sealing of the grease at the shield tail is one of the key factors ensuring the safety of shield tunnel construction, and the long-distance stable pumping of the shield tail sealing grease is a prerequisite for ensuring smooth construction. Therefore, synergistically improving resistance to water flow erosion, sealing performance, and pumpability is a key challenge in the research and development of shield tail sealing grease products.

[0005] Fourth, with the continuous development of tunnel construction, complex working conditions involving traversing different geological strata have emerged in the projects. Existing shield tail sealing greases are often insufficient to handle these conditions, requiring the continuous replacement of grease types during construction to adapt to different geological environments, which affects the construction period and increases labor costs.

[0006] Therefore, there is an urgent need to develop an environmentally friendly shield tail sealing grease suitable for different geological formations, which has strong resistance to water flow erosion, pumping performance, and water pressure sealing performance, and can meet the needs of shield tail sealing. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide an environmentally friendly shield tail sealing grease that utilizes waste materials and its preparation method. This environmentally friendly shield tail sealing grease is suitable for different geological formations, does not require adjustment when changing formations, and possesses strong resistance to water flow erosion, pumping performance, and water pressure sealing performance, thus meeting the requirements of shield tail sealing.

[0008] To achieve the above objectives, the present invention employs the following technical solution: An environmentally friendly shield tail sealing grease for waste utilization, by weight, is composed of the following raw materials: 250-450 parts base oil, 10-50 parts Fischer-Tropsch wax, 60-150 parts modified organopolysiloxane, 50-100 parts modified xanthan gum, 10-90 parts fiber reinforcing agent, 350-650 parts filler, and 35-60 parts modified additive. The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 40-50℃ to remove impurities, and then heated to 80-120℃ and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mg KOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add alcohol solvent and sodium hydroxide to the deacidified waste edible vegetable oil obtained in step S12, stir and react at 60~70℃ for 1~2 hours, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:18~25:0.5~1.5; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 45~55℃ until neutral, and dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

[0009] Preferably, the modified xanthan gum is prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 20-30%; S22. Mix paraffin wax and Span 80 at a mass ratio of 8~12:1, and stir at 60~65℃ until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 60~65℃ for 20~40 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to a PVC aqueous solution at 5~10℃, and stir at 5~10℃ for 15~25 minutes after the dropwise addition is completed to obtain a mixture; The mass ratio of xanthan gum aqueous solution obtained in S21, molten wax phase obtained in S22, and PVC aqueous solution is 1:0.8~1:20~30; The mass concentration of the PVC aqueous solution is 0.8~1.2%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 25~30℃ to obtain modified xanthan gum.

[0010] Preferably, the modified additive is a mixture of polydimethylsiloxane, zinc oxide, sodium citrate and graphite.

[0011] More preferably, sodium citrate is pretreated by encapsulation with stearic acid, which allows the modified sodium citrate to be better dispersed in the base oil; the modification process is as follows: Sodium citrate, stearic acid, and Span 80 were mixed in a mass ratio of 1:1~2:0.05~0.1, heated to 75-80℃ and stirred continuously to form an emulsion. The emulsion was then added to deionized water in a mass ratio of 1:8~15, stirred at high speed for 5~10 minutes, and after cooling to room temperature, the precipitate was filtered out to obtain stearic acid-coated modified sodium citrate.

[0012] Preferably, the fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is two or more of corn cob fiber, wheat straw fiber, flax stalk fiber, peanut shell fiber, and rice husk fiber.

[0013] Preferably, the filler is a mixture of mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust.

[0014] Preferably, the alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 4 to 6:1.

[0015] Preferably, the mass ratio of polydimethylsiloxane, zinc oxide, sodium citrate and graphite in the modified additive is 5~15:20~30:5~10:5~10.

[0016] Preferably, the plant fiber after autocatalytic hydrolysis is prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 175~185℃ within 30 minutes, and the temperature is maintained at 0.8~1.2MPa for 30~90 minutes to obtain the hydrolyzed plant fiber. The mass ratio of the pretreated plant fiber and deionized water obtained in step S31 is 1:4~6; Since the pretreated plant fibers themselves contain moisture, the amount of deionized water added can be adjusted according to the moisture content of the plant fibers themselves.

[0017] S33. The hydrolyzed plant fibers obtained in step S32 are ground using a double-disc refiner at 60-70°C for 2-5 minutes to obtain autocatalytically hydrolyzed plant fibers, with a disc-to-disc gap of 0.1-0.3 mm. This step is to further separate them into finer fibers through mechanical shearing force, i.e., "fibrillation." This greatly increases the fiber aspect ratio and specific surface area, thereby forming a stronger three-dimensional network structure in the shield tail grease. Setting a temperature limit is to keep the material in a softened state, reduce the viscosity of the slurry, and prevent excessively high temperatures from damaging the fiber structure. Setting a time limit is to prevent the fibers from being over-ground and broken or insufficiently fibrillated.

[0018] Preferably, the mass ratio of mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in the filler is 3~9:3~9:10~26:8~27:6~18.

[0019] This invention also includes a method for preparing an environmentally friendly shield tail sealing grease that utilizes waste materials, comprising the following steps: ① Grind 10-50 parts of Fischer-Tropsch wax into powder by weight and set aside; ② Heat 250-450 parts of base oil to 55-65℃, add 60-150 parts of modified organic polysiloxane, stir and mix well, add 50-100 parts of modified xanthan gum and 35-60 parts of modified additives, stir and mix well, then add 350-650 parts of filler in 3-5 portions, then add 10-90 parts of fiber reinforcing agent, continue to stir and mix well, and obtain the waste-utilization environmentally friendly shield tail sealing grease.

[0020] The present invention has the following advantages over the prior art: The waste material of this invention utilizes an environmentally friendly tail seal grease, which has excellent geological adaptability and can meet the tail seal requirements of different geological formations. No additional replacement of the tail seal grease is required when working in different geological formations. It can be applied to silty fine sand formations with high sand inflow, highly permeable gravel formations, and underwater formations with high water pressure. The modified additives and fillers of this invention can reduce the friction of sand particles on the tail brush. During tunneling in silty fine sand formations, it can effectively reduce the deformation of the tail brush and avoid tail seal failure caused by wear and deformation of the tail brush. The hydrophobicity of the modified organopolysiloxane can improve the water resistance of the grease, fully enhancing its adaptability to gravel formations and underwater high water pressure formations.

[0021] The waste material of this invention utilizes environmentally friendly tail seal grease, using treated waste edible vegetable oil as the base oil and agricultural plant fibers to prepare reinforcing agents, effectively reducing costs. After construction, the tail seal grease will not affect the soil and water in the construction area, and it can be degraded subsequently, making it safe and environmentally friendly.

[0022] This invention utilizes environmentally friendly tail shield sealing grease, which possesses strong resistance to water flow erosion, pumpability, and water pressure sealing performance. Fischer-Tropsch wax, modified organopolysiloxane, and modified xanthan gum serve as thickeners. When the grease is pumped, the high shear rate environment reduces its viscosity, facilitating pumping. Once the tail shield sealing grease adheres to the tail shield brush, its viscosity recovers, ensuring tight adhesion and guaranteeing water pressure resistance and erosion resistance. This invention utilizes polydimethylsiloxane to improve the grease's surface tension and adds sodium citrate to prevent particle flocculation, ensuring uniformity during flow and preventing the filler and fiber reinforcement from agglomerating during pumping, thus affecting pumpability. Detailed Implementation

[0023] The purpose of this invention is to provide an environmentally friendly shield tail sealing grease that utilizes waste materials and its preparation method, which is achieved through the following technical solution: The Fischer-Tropsch wax used in this embodiment of the invention is Sarawax SX70, which has a melting point of about 70°C. The modified organopolysiloxane of this invention was purchased from ANDISIL Specialty Silicones (Nantong) Co., Ltd., model ANDISIL VS 65000.

[0024] In this embodiment of the invention, the heavy calcium carbonate is 400 mesh, the light calcium carbonate is 1250 mesh, the mica powder is 600-800 mesh, the talc powder is 400 mesh, the sawdust has an ash content of 3%-6% and a length of 6-12 mm; the volatile matter of polydimethylsiloxane is ≤0.1wt%, and the graphite is 200 mesh.

[0025] There are no special provisions for stirring and low-speed stirring in this invention, both are 50~300 rpm, the centrifugal separation speed is 4000~8000 rpm, and the settling time is generally 4~6 hours.

[0026] Waste edible vegetable oil can be soybean oil, rapeseed oil, peanut oil, sesame oil, or blended edible vegetable oil.

[0027] The sodium citrate modified with stearic acid used in this embodiment of the invention can be better dispersed in the base oil; it can be purchased externally or made in-house, and the in-house process is as follows: Sodium citrate, stearic acid, and Span 80 were mixed in a mass ratio of 1:1~2:0.05~0.1, heated to 75-80℃ and stirred continuously to form an emulsion. The emulsion was then added to deionized water in a mass ratio of 1:8~15, stirred at high speed for 5~10 minutes, and after cooling to room temperature, the precipitate was filtered out to obtain stearic acid-coated modified sodium citrate.

[0028] The present invention will be further described below with reference to specific embodiments. Example 1

[0029] An environmentally friendly shield tail sealing grease that utilizes waste materials is composed of the following raw materials: 250 kg base oil, 10 kg Fischer-Tropsch wax, 60 kg modified organopolysiloxane, 50 kg modified xanthan gum, 10 kg fiber reinforcing agent, 350 kg filler, and 35 kg modified additive. The modified additive is obtained by mixing polydimethylsiloxane, zinc oxide, sodium citrate and graphite in a mass ratio of 1:4:1:1; The filler is obtained by mixing mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in a mass ratio of 3:3:10:8:6; The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 40°C to remove impurities, and then heated to 80°C and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mg KOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add alcohol solvent and sodium hydroxide to the deacidified waste edible vegetable oil obtained in step S12, stir and react at 60°C for 2 hours, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:18:0.5. The alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 4:1; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 45°C until neutral, and then dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

[0030] The modified xanthan gum was prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 20%; S22. Mix paraffin wax and Span 80 at a mass ratio of 8:1, and stir at 60°C until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 60°C for 20 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to a PVC aqueous solution at 5°C, and stir at 5°C for 25 minutes after the addition is complete to obtain a mixture. The mass ratio of the xanthan gum aqueous solution obtained in S21, the molten wax phase obtained in S22, and the PVC aqueous solution is 1:0.8:20. The mass concentration of the PVC aqueous solution is 0.8%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 25°C to obtain modified xanthan gum.

[0031] The fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is composed of corn cob fiber and wheat straw fiber. The plant fiber, after autocatalytic hydrolysis, was prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 175°C within 30 minutes, and the temperature is maintained at 0.8MPa for 90 minutes to obtain the hydrolyzed plant fiber. The mass ratio of the pretreated plant fiber and deionized water obtained in step S31 is 1:4; S33. The hydrolyzed plant fiber obtained in step S32 is ground at 60°C for 2 minutes using a double-disc grinder to obtain self-catalytically hydrolyzed plant fiber, wherein the disc grinding gap is 0.1 mm. Example 2

[0032] An environmentally friendly shield tail sealing grease that utilizes waste materials is composed of the following raw materials: 450 kg base oil, 50 kg Fischer-Tropsch wax, 150 kg modified organopolysiloxane, 100 kg modified xanthan gum, 90 kg fiber reinforcing agent, 650 kg filler, and 60 kg modified additive. The modified additive is obtained by mixing polydimethylsiloxane, zinc oxide, sodium citrate and graphite in a mass ratio of 3:6:2:2; the filler is obtained by mixing mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in a mass ratio of 9:9:26:27:18. The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 50°C to remove impurities, and then heated to 120°C and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mg KOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add alcohol solvent and sodium hydroxide to the deacidified waste edible vegetable oil obtained in step S12, stir and react at 70°C for 1 hour, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:25:1.5. The alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 6:1; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 55°C until neutral, and then dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

[0033] The modified xanthan gum was prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 30%; S22. Mix paraffin wax and Span 80 at a mass ratio of 12:1 and stir at 65°C until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 65°C for 40 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to a PVC aqueous solution at 10°C, and stir at 10°C for 15 minutes after the addition is complete to obtain a mixture. The mass ratio of xanthan gum aqueous solution obtained in S21, molten wax phase obtained in S22, and PVC aqueous solution is 1:1:30; The mass concentration of the PVC aqueous solution is 0.8~1.2%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 30°C to obtain modified xanthan gum.

[0034] The fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is composed of flax stalk fiber and peanut shell fiber. The plant fiber, after autocatalytic hydrolysis, was prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 185°C within 30 minutes, and the temperature is maintained at 1.2 MPa for 30 minutes to obtain the hydrolyzed plant fiber. The mass ratio of the pretreated plant fiber and deionized water obtained in step S31 is 1:6; S33. The hydrolyzed plant fiber obtained in step S32 is ground at 70°C for 2 minutes using a double-disc grinder to obtain self-catalytically hydrolyzed plant fiber, wherein the disc grinding gap is 0.3 mm. Example 3

[0035] An environmentally friendly shield tail sealing grease that utilizes waste materials is composed of the following raw materials: 300 kg base oil, 20 kg Fischer-Tropsch wax, 70 kg modified organopolysiloxane, 90 kg modified xanthan gum, 80 kg fiber reinforcing agent, 400 kg filler, and 40 kg modified additive. The modified additive is obtained by mixing polydimethylsiloxane, zinc oxide, sodium citrate and graphite in a mass ratio of 2:5:1.5:1.5; the filler is obtained by mixing mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in a mass ratio of 5:6:22:18:14. The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 42°C to remove impurities, and then heated to 90°C and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mg KOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add the deacidified waste edible vegetable oil obtained in step S12 to alcohol solvent and sodium hydroxide, stir and react at 62°C for 1.5 hours, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:20:0.8. The alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 5:1; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 48°C until neutral, and then dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

[0036] The modified xanthan gum was prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 22%; S22. Mix paraffin wax and Span 80 at a mass ratio of 9:1 and stir at 62°C until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 62°C for 25 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to a PVC aqueous solution at 6°C, and stir at 6°C for 18 minutes after the addition is complete to obtain a mixture. The mass ratio of the xanthan gum aqueous solution obtained in S21, the molten wax phase obtained in S22, and the PVC aqueous solution is 1:0.9:22. The mass concentration of the PVC aqueous solution is 0.9%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 26°C to obtain modified xanthan gum.

[0037] The fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is composed of corn cob fiber, wheat straw fiber and rice husk fiber. The plant fiber, after autocatalytic hydrolysis, was prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 178°C within 30 minutes, and the temperature is maintained at 0.9 MPa for 50 minutes to obtain the hydrolyzed plant fiber. The mass ratio of the pretreated plant fiber and deionized water obtained in step S31 is 1:5; S33. The hydrolyzed plant fiber obtained in step S32 is ground at 62°C for 3 minutes using a double-disc grinder to obtain self-catalytically hydrolyzed plant fiber, wherein the disc grinding gap is 0.2 mm. Example 4

[0038] An environmentally friendly shield tail sealing grease that utilizes waste materials is composed of the following raw materials: 400 kg base oil, 40 kg Fischer-Tropsch wax, 140 kg modified organopolysiloxane, 60 kg modified xanthan gum, 20 kg fiber reinforcing agent, 600 kg filler, and 50 kg modified additive. The modified additive is obtained by mixing polydimethylsiloxane, zinc oxide, stearic acid-encapsulated modified sodium citrate and graphite in a mass ratio of 12:25:6:8; the filler is obtained by mixing mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in a mass ratio of 6:5:14:10:14. The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 48°C to remove impurities, and then heated to 110°C and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mg KOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add the deacidified waste edible vegetable oil obtained in step S12 to alcohol solvent and sodium hydroxide, stir and react at 66°C for 1.5 hours, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:22:1.2; The alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 5:1; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 52°C until neutral, and then dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

[0039] The modified xanthan gum was prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 28%; S22. Mix paraffin wax and Span 80 at a mass ratio of 11:1 and stir at 64°C until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 62°C for 25 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to the PVC aqueous solution at 8°C, and stir at 8°C for 22 minutes after the addition is complete to obtain a mixture. The mass ratio of the xanthan gum aqueous solution obtained in S21, the molten wax phase obtained in S22, and the PVC aqueous solution is 1:0.9:28. The mass concentration of the PVC aqueous solution is 1.1%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 26°C to obtain modified xanthan gum.

[0040] The fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is composed of corn cob fiber, peanut shell fiber and rice husk fiber. The plant fiber, after autocatalytic hydrolysis, was prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 180°C within 30 minutes, and the temperature is maintained at 1.1 MPa for 60 minutes to obtain the hydrolyzed plant fiber. The mass ratio of the pretreated plant fiber and deionized water obtained in step S31 is 1:5; S33. The hydrolyzed plant fiber obtained in step S32 is ground at 66°C for 3 minutes using a double-disc grinder to obtain self-catalytically hydrolyzed plant fiber, wherein the disc grinding gap is 0.2 mm. Example 5

[0041] An environmentally friendly shield tail sealing grease that utilizes waste materials is composed of the following raw materials: 350 kg base oil, 35 kg Fischer-Tropsch wax, 100 kg modified organopolysiloxane, 75 kg modified xanthan gum, 50 kg fiber reinforcing agent, 450 kg filler, and 45 kg modified additive. The modified additive is obtained by mixing polydimethylsiloxane, zinc oxide, stearic acid-encapsulated modified sodium citrate and graphite in a mass ratio of 8:25:8:6; the filler is obtained by mixing mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in a mass ratio of 5:4:20:20:12. The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 45°C to remove impurities, and then heated to 100°C and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mg KOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add the deacidified waste edible vegetable oil obtained in step S12 to alcohol solvent and sodium hydroxide, stir and react at 65°C for 1.5 hours, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:20:1; The alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 5:1; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 50°C until neutral, and then dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

[0042] The modified xanthan gum was prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 25%; S22. Mix paraffin wax and Span 80 at a mass ratio of 10:1, and stir at 64°C until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 64°C for 30 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to a PVC aqueous solution at 6°C, and stir at 6°C for 20 minutes after the addition is complete to obtain a mixture. The mass ratio of the xanthan gum aqueous solution obtained in S21, the molten wax phase obtained in S22, and the PVC aqueous solution is 1:0.9:25. The mass concentration of the PVC aqueous solution is 1%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 26°C to obtain modified xanthan gum.

[0043] The fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is composed of wheat straw fiber and peanut shell fiber. The plant fiber, after autocatalytic hydrolysis, was prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 180°C within 30 minutes, and the temperature is maintained at 1.0 MPa for 60 minutes to obtain the hydrolyzed plant fiber. S33. The hydrolyzed plant fiber obtained in step S32 is ground at 65°C for 3 minutes using a double-disc grinder to obtain self-catalytically hydrolyzed plant fiber, wherein the disc-grinding gap is 0.2 mm. Example 6

[0044] Example 1 describes a method for preparing an environmentally friendly shield tail sealing grease that utilizes waste materials, comprising the following steps: ① Grind 10 kg of Fischer-Tropsch wax into powder and set aside; ② Heat 250 kg of base oil to 55°C, add 60 kg of modified organic polysiloxane, stir and mix well, heat to 80°C, add the powdered Fischer-Tropsch wax obtained in step ①, stir and mix well, then cool to 25°C, add 50 kg of modified xanthan gum and 35 kg of modified additive, stir and mix well, then add a mixture of 350 kg of filler and 10 kg of fiber reinforcing agent in 3 portions, continue stirring and mixing well to obtain environmentally friendly shield tail sealing grease for waste utilization. Example 7

[0045] Example 2 describes a method for preparing an environmentally friendly shield tail sealing grease that utilizes waste materials, comprising the following steps: ① Grind 50 kg of Fischer-Tropsch wax into powder and set aside; ② Heat 450 kg of base oil to 65°C, add 150 kg of modified organic polysiloxane, stir and mix well, heat to 100°C, add the powdered Fischer-Tropsch wax obtained in step ①, stir and mix well, then cool to 35°C, add 100 kg of modified xanthan gum and 60 kg of modified additive, stir and mix well, then add a mixture of 650 kg of filler and 90 kg of fiber reinforcing agent in 5 portions, continue stirring and mixing well to obtain environmentally friendly shield tail sealing grease for waste utilization. Example 8

[0046] Example 3 describes a method for preparing an environmentally friendly shield tail sealing grease that utilizes waste materials, comprising the following steps: ① Grind 20 kg of Fischer-Tropsch wax into powder and set aside; ② Heat 300 kg of base oil to 58°C, add 70 kg of modified organic polysiloxane, stir and mix well, heat to 85°C, add the powdered Fischer-Tropsch wax obtained in step ①, stir and mix well, then cool to 28°C, add 90 kg of modified xanthan gum and 40 kg of modified additive, stir and mix well, then add a mixture of 400 kg of filler and 80 kg of fiber reinforcing agent in 4 portions, continue stirring and mixing well to obtain environmentally friendly shield tail sealing grease for waste utilization. Example 9

[0047] Example 4 describes a method for preparing an environmentally friendly shield tail sealing grease that utilizes waste materials, comprising the following steps: ① Grind 40 kg of Fischer-Tropsch wax into powder and set aside; ② Heat 400 kg of base oil to 62°C, add 140 kg of modified organic polysiloxane, stir and mix well, heat to 95°C, add the powdered Fischer-Tropsch wax obtained in step ①, stir and mix well, then cool to 32°C, add 60 kg of modified xanthan gum and 50 kg of modified additive, stir and mix well, then add a mixture of 600 kg of filler and 20 kg of fiber reinforcing agent in 4 portions, continue stirring and mixing well to obtain environmentally friendly shield tail sealing grease for waste utilization. Example 10

[0048] Example 5 describes a method for preparing an environmentally friendly shield tail sealing grease that utilizes waste materials, comprising the following steps: ① Grind 35 kg of Fischer-Tropsch wax into powder and set aside; ② Heat 350 kg of base oil to 60°C, add 100 kg of modified organic polysiloxane, stir and mix well, heat to 90°C, add the powdered Fischer-Tropsch wax obtained in step ①, stir and mix well, then cool to 30°C, add 75 kg of modified xanthan gum and 45 kg of modified additive, stir and mix well, then add a mixture of 450 kg of filler and 50 kg of fiber reinforcing agent in 4 portions, continue stirring and mixing well to obtain environmentally friendly shield tail sealing grease for waste utilization.

[0049] The waste materials obtained in Examples 6-10 were subjected to performance tests using environmentally friendly shield tail sealing grease. The breakdown water pressure, resistance to water flow loss, pumpability, and cone penetration were all tested according to the method of T / CC 8-2023. The results are shown in Table 1.

[0050] Table 1. Performance test results of the waste materials obtained in Examples 6-10 using environmentally friendly shield tail sealing grease.

[0051] As shown in Table 1, the environmentally friendly shield tail sealing grease of this invention exhibits excellent performance in terms of adhesion, pumpability, and sealing properties. Furthermore, its composition is more environmentally friendly, as all selected materials are biodegradable, thus possessing significant environmental value in protecting the surrounding ecological environment of the shield tunnel construction area. This invention processes and recycles waste edible vegetable oil and agricultural waste, transforming it into materials suitable for producing shield tail sealing grease. It boasts excellent economic and environmental benefits, saving approximately 30% in costs compared to ordinary shield tail sealing grease.

[0052] The addition of the self-made modified xanthan gum in this invention solves the problems of significantly reduced pumpability and easy blockage of the injection pipe caused by directly adding xanthan gum to the shield tail sealing grease. The modified xanthan gum can ensure that the shield tail sealing grease maintains a low viscosity during pumping, avoiding blockage of the injection pipe. The modified xanthan gum dispersed in the shield tail sealing grease can rapidly increase the viscosity of the shield tail sealing grease under the friction, compression and temperature action of the shield tail brush in the shield tail sealing cavity, improve the sedimentation and stratification and thermal stability of the shield tail sealing grease, and greatly improve the breakdown water pressure, adhesion and erosion resistance of the shield tail sealing grease.

Claims

1. An environmentally friendly shield tail sealing grease that utilizes waste materials, characterized in that: By weight, it is composed of the following raw materials: 250-450 parts base oil, 10-50 parts Fischer-Tropsch wax, 60-150 parts modified organopolysiloxane, 50-100 parts modified xanthan gum, 10-90 parts fiber reinforcing agent, 350-650 parts filler and 35-60 parts modified additive. The base oil is processed waste edible vegetable oil, and the specific processing steps are as follows: S11. Impurity removal and dehydration: The waste edible vegetable oil is filtered through a 200-mesh metal mesh at 40-50℃ to remove impurities, and then heated to 80-120℃ and dehydrated under vacuum until the moisture content is less than 0.3% to obtain dehydrated waste edible vegetable oil. S12, Deacidification: Add KOH to the dehydrated waste edible vegetable oil to neutralize the free fatty acids and reduce the acid value to <2mgKOH / g. Then, centrifuge at high speed to separate and discharge the lower soap residue to obtain the deacidified waste edible vegetable oil. S13. Chemical modification: Add alcohol solvent and sodium hydroxide to the deacidified waste edible vegetable oil obtained in step S12, stir and react at 60~70℃ for 1~2 hours, let it stand to separate into layers or centrifuge to remove the lower glycerol phase, and then remove the alcohol solvent by vacuum cleaning to obtain the chemically modified waste edible vegetable oil. The mass ratio of the deacidified waste edible vegetable oil, alcohol solvent, and sodium hydroxide obtained in step S12 is 100:18~25:0.5~1.5; S14. Product purification: The chemically modified waste edible vegetable oil obtained in step S13 is washed with warm water at 45~55℃ until neutral, and dehydrated under vacuum until the moisture content is <0.1% to obtain the treated waste edible vegetable oil.

2. The environmentally friendly shield tail sealing grease for waste utilization according to claim 1, characterized in that: The modified xanthan gum was prepared according to the following steps: S21. Prepare a xanthan gum aqueous solution with a mass concentration of 20-30%; S22. Mix paraffin wax and Span 80 at a mass ratio of 8~12:1, and stir at 60~65℃ until dissolved to obtain a molten wax phase; S23. Add the xanthan gum aqueous solution obtained in step S21 to the molten wax phase obtained in S22, and shear at high speed at 60~65℃ for 20~40 minutes to form a water-oil type primary emulsion; under low speed stirring, dropwise add the obtained water-oil type primary emulsion to a PVC aqueous solution at 5~10℃, and stir at 5~10℃ for 15~25 minutes after the dropwise addition is completed to obtain a mixture; The mass ratio of xanthan gum aqueous solution obtained in S21, molten wax phase obtained in S22, and PVC aqueous solution is 1:0.8~1:20~30; The mass concentration of the PVC aqueous solution is 0.8~1.2%; S24. Filter the mixture obtained in step S23 through a 100-mesh sieve to separate the solid particles. Dry the obtained solid particles under vacuum at 25~30℃ to obtain modified xanthan gum.

3. The environmentally friendly shield tail sealing grease for waste utilization according to claim 1, characterized in that: The modifying additive is a mixture of polydimethylsiloxane, zinc oxide, sodium citrate and graphite.

4. The environmentally friendly shield tail sealing grease for waste utilization according to claim 1, characterized in that: The fiber reinforcing agent is plant fiber that has undergone autocatalytic hydrolysis, and the plant fiber is two or more of corn cob fiber, wheat straw fiber, flax stalk fiber, peanut shell fiber, and rice husk fiber.

5. The environmentally friendly shield tail sealing grease for waste utilization according to claim 1, characterized in that: The filler is a mixture of mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust.

6. The environmentally friendly shield tail sealing grease for waste utilization according to claim 1, characterized in that: The alcohol solvent is obtained by mixing methanol and ethanol in a mass ratio of 4 to 6:

1.

7. The environmentally friendly shield tail sealing grease for waste utilization according to claim 3, characterized in that: The mass ratio of polydimethylsiloxane, zinc oxide, sodium citrate and graphite in the modified additive is 5~15:20~30:5~10:5~10.

8. The environmentally friendly shield tail sealing grease for waste utilization according to claim 4, characterized in that: The plant fiber, after autocatalytic hydrolysis, is prepared according to the following steps: S31. Impurity removal and crushing: Remove impurities from the plant fiber using a vibrating screen, and crush it into fragments <30mm using a crusher to obtain pretreated plant fiber for later use. S32, Autocatalytic hydrolysis: The pretreated plant fiber obtained in step S31 and deionized water are added to the reactor, the temperature is raised to 175~185℃ within 30 minutes, and the temperature is maintained at 0.8~1.2MPa for 30~90 minutes to obtain the hydrolyzed plant fiber. The mass ratio of the pretreated plant fiber and deionized water obtained in step S31 is 1:4~6; S33. The hydrolyzed plant fiber obtained in step S32 is ground in a double-disc grinder at 60~70℃ for 2~5 minutes to obtain autocatalytically hydrolyzed plant fiber, wherein the disc grinding gap is 0.1~0.3mm.

9. The environmentally friendly shield tail sealing grease for waste utilization according to claim 5, characterized in that: The mass ratio of mica powder, talc powder, light calcium carbonate, heavy calcium carbonate and sawdust in the filler is 3~9:3~9:10~26:8~27:6~18.

10. The method for preparing an environmentally friendly shield tail sealing grease utilizing waste materials as described in claim 1, characterized in that: Includes the following steps: ① Grind 10-50 parts of Fischer-Tropsch wax into powder by weight and set aside; ② Heat 250-450 parts of base oil to 55-65℃, add 60-150 parts of modified organopolysiloxane, stir and mix well, heat to 80-100℃, add the powdered Fischer-Tropsch wax obtained in step ①, stir and mix well, then cool to 25-35℃, add 50-100 parts of modified xanthan gum and 35-60 parts of modified additives, stir and mix well, then add a mixture of 350-650 parts of filler and 10-90 parts of fiber reinforcing agent in 3-5 portions, continue stirring and mixing well to obtain an environmentally friendly shield tail sealing grease for waste utilization.

Images