A non-foaming dispersant for cleaning clay deposits in mud shield tunneling

Abstract

The invention discloses a non-foaming dispersant for cleaning muddy shield silt clay, and the raw materials include, by mass percentage: surfactant (mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide) 4-8wt%, ion repulsion agent (dodecylpyridinium bromide or vinylpyridinium bromide) 2-5wt%, cross-linking agent (organic photo-oxidant) 5-10wt%, oxidant 4-10wt%, stabilizer 3-5wt%, pH regulator 0.5-1wt%, preservative 0.5-1wt% and surplus water. The above components work synergistically to effectively decompose silted clay and reduce the adhesion of silted clay. The non-foaming dispersant of the present invention can disperse the silted clay when injected into the muddy water bin, and the clay can be removed by flushing with clean water or mud circulation. Compared with the traditional method of manual chiseling, the dispersant effectively reduces the labor cost and speeds up the construction efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of slurry shield construction materials, in particular to a non-foaming dispersant used for cleaning silted clay of slurry shield. Background Art

[0002] The shield method is a commonly used mechanized construction method in urban tunnel construction. It is currently developing in the direction of large cross-section, deep burial, long distance, and complex strata, and the construction difficulty is getting higher and higher. When the slurry shield is excavating in the clay strata, the strata contain a lot of clay minerals. A large amount of clay minerals form mud balls and adhere to the cutter and the inner wall of the shield mud silo, and further accumulate in the mud silo to form a hard mud cake. The clay accumulated in the slurry shield seriously affects the shield construction efficiency, hinders the migration path of mud and slag, and seriously reduces the service life of components such as the silo bottom suction port and crusher.

[0003] At present, there are three ways to clean up the silted clay in the shield tunnel. One is to remove the mud cake by manual chiseling when the shield tunnel is opened. This method consumes a lot of labor, and requires a long time of shutdown and opening, which is high-risk. The second is to use mud reverse circulation and clean water flushing to flush the silted clay at the bottom of the warehouse. This method is not very effective in removing the silted clay that has formed into mud cakes. The third is to disperse the silted clay by soaking the warehouse with hydrogen peroxide. At present, this method still has the defects of low removal rate, high cost of processing materials, and insufficient processing efficiency. The existing hydrogen peroxide treatment process produces a large amount of oxygen during decomposition, and a large amount of foam will block the sieve holes, causing the mud screening equipment to be paralyzed, affecting the treatment and reuse of the mud. Summary of the invention

[0004] The purpose of the present invention is to provide a non-foaming dispersant for cleaning clay deposited in a slurry shield, so as to solve the problems existing in the above-mentioned prior art and realize safe, economical, environmentally friendly and efficient treatment of clay deposited in the bin.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: a foam-free dispersant for cleaning mud shield silt clay, the raw materials of which include, by mass percentage: 4-8wt% of surfactant, 2-5wt% of ion repulsion agent, 5-10wt% of cross-linking agent, 4-10wt% of oxidant, 3-5wt% of stabilizer, 0.5-1wt% of pH adjuster, 0.5-1wt% of preservative and the balance of water.

[0007] Furthermore, the surfactant is a mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide; the mass ratio of cocamidopropyl betaine to tetramethyl phosphonium bromide in the surfactant is 2:1-3:1.

[0008] The surfactant composed of cocamidopropyl betaine (with hydrophilic and hydrophobic groups) and tetramethyl phosphonium bromide (with hydrophobic properties) contains hydrophilic and hydrophobic parts, which enables the surfactant to form an isolation layer between the water and clay surface, effectively reducing the surface tension of the liquid and the adhesion of the clay. The combination of cocamidopropyl betaine and tetramethyl phosphonium bromide has a synergistic effect, which can significantly enhance the isolation and viscosity reduction effects. In addition, the ratio of the two is within the range of 2:1-3:1, which can better play the role of the isolation layer of the mixture and achieve better viscosity reduction effect.

[0009] Furthermore, the ion repellent is dodecylpyridinium bromide (or dodecylpyridinium bromide, CAS No. 104-73-4) or vinylpyridinium bromide (or 3-bromo-5-vinylpyridine, CAS No. 191104-26-4).

[0010] After ionization, the ionic repellent is adsorbed on the surface of clay particles, forming a double electric layer structure, which increases the surface charge density. Under the repulsive force of the same charges on the surface, the clay particles overcome the van der Waals force between the particles and achieve a dispersion effect.

[0011] Furthermore, the cross-linking agent is an organic peroxide.

[0012] Organic peroxides can promote or regulate the formation of covalent bonds or ionic bonds between surfactant molecules, converting linear or slightly branched macromolecules into three-dimensional network structures, wrapping clay particles to isolate them.

[0013] Furthermore, the organic peroxide is one of dicumyl oxide (DCP), benzoyl peroxide (BPO) and di-tert-butyl peroxide (DTBP).

[0014] Furthermore, the oxidant is at least one of hydrogen peroxide, sodium perborate, sodium percarbonate and sodium peroxide.

[0015] The active oxygen atoms in the oxidant can undergo an oxidation reaction with the organic matter in the clay, thereby changing the chemical structure of the organic matter, reducing its viscosity, and reducing the adhesion between the clay and the shield machine cutter head panel and the inner wall of the mud and water bin.

[0016] Furthermore, the stabilizer is a mixture of fatty acid methyl ester sulfonate and alkyl glycoside; the mass ratio of fatty acid methyl ester sulfonate to alkyl glycoside in the stabilizer is 1:1-1:2.

[0017] As mentioned above, organic peroxides can promote or regulate the formation of covalent or ionic bonds between surfactant molecules, converting linear or slightly branched macromolecules into three-dimensional network structures. However, the reaction speed of this process is fast, and the stability of the covalent or ionic bonds formed is not strong, resulting in a short shelf life of the dispersant. The addition of stabilizers slows down the cross-linking reaction rate between the components, making the covalent or ionic bonds more stable, and significantly enhancing the stability and shelf life of the non-foaming dispersant.

[0018] The combined use of fatty acid methyl ester sulfonate and alkyl glucoside has a synergistic effect, and fatty acid methyl ester sulfonate easily forms mixed micelles with calcium ions in water, which is easy to form calcium scale. The combined use of fatty acid methyl ester sulfonate with alkyl glucoside can prevent fatty acid methyl ester sulfonate from precipitating in hard water and losing its function.

[0019] Furthermore, the pH regulator is soda ash; the preservative is at least one of sodium diacetate, calcium propionate and dehydroacetic acid, and the preservative can effectively extend the shelf life of the foam-free dispersant.

[0020] The above components in the non-foaming dispersant of the present invention are all environmentally friendly materials with no chemical corrosion, and the impact of the non-foaming dispersant on the cutter head, the connecting pipes and the flexible connections in the mud and water tank can be ignored. The above components work synergistically to effectively decompose the silted clay and reduce the adhesion of the silted clay.

[0021] The second technical solution of the present invention: The preparation method of the above-mentioned foam-free dispersant for cleaning mud shield silt clay comprises the following steps: mixing a surfactant and water, stirring evenly to obtain a mixture 1, adding an ion repulsion agent after standing, stirring evenly to obtain a mixture 2, adding a stabilizer after standing, stirring evenly to obtain a mixture 3; adding a pH adjuster to the mixture 3 to adjust the pH to 7.5-8.5, and then adding a cross-linking agent, an oxidant and a preservative in sequence, and stirring them respectively to obtain the foam-free dispersant.

[0022] More preferably, after adding a pH adjuster to the mixture 3 to adjust the pH to 8, a cross-linking agent, an oxidant and a preservative are added in sequence.

[0023] Furthermore, the stirring speed after the surfactant and water are mixed is 60-100 rpm; the stirring speed after the ion repellent is added is 60-100 rpm; the stirring speed after the stabilizer is added is 60-100 rpm.

[0024] Furthermore, the cross-linking agent, the oxidant and the preservative are added in sequence and stirred evenly. Specifically, the cross-linking agent is added, the oxidant is added after stirring evenly, and the preservative is added after stirring evenly. The stirring speed is 30-60 rpm.

[0025] Furthermore, the mixture 1 was allowed to stand for 30 minutes, and the mixture 2 was allowed to stand for 10 minutes.

[0026] The third technical solution of the present invention: the application of the above-mentioned foam-free dispersant in the cleaning of clay deposited in a mud and water shield, the dispersant and water are mixed to obtain a dispersant solution; the dispersant solution is added to the mud and water bin of the shield to bubble for 1.5-2h; the volume ratio of the added dispersant solution to the clay deposited in the mud and water bin is 0.2-0.3:6.

[0027] Furthermore, the mass concentration of the dispersant in the dispersant solution is 1.5-3%.

[0028] The present invention discloses the following technical effects:

[0029] (1) The components of the foam-free dispersant of the present invention have good stability after dissolution, and no precipitation will occur during storage. The components are non-toxic and harmless, and can be naturally degraded, and will not affect the soil and groundwater in the construction area.

[0030] (2) Bubbles can cause inconvenience to mud treatment and affect the recycling of mud. The non-foaming dispersant of the present invention does not generate bubbles when used and will not have a significant impact on the density, viscosity and other properties of the mud.

[0031] (3) The foam-free dispersant of the present invention can disperse the silted clay when injected into the mud and water tank, and the clay can be removed by flushing with clean water or circulating the mud. Compared with the traditional manual chiseling method, the dispersant effectively reduces labor costs and speeds up construction efficiency. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The following examples take the treatment of waste mud rich in sticky particles from a slurry shield as an example to further illustrate the specific implementation of the present invention. The slurry shield passes through silty clay, weathered mudstone and other strata, and a large amount of clay is deposited in the slurry bin. It has not been cleaned for a long time, and the deposited clay has formed a hard mud cake.

[0038] The numbers referred to in the following examples and comparative examples all represent numbers by mass.

[0039] Example 1

[0040] 1. Preparation of non-foaming dispersant

[0041] Measured by mass percentage, the raw material composition of the foam-free dispersant is: surfactant (a mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide in a mass ratio of 2:1) 5wt%, ion repulsion agent (dodecylpyridinium bromide) 4wt%, cross-linking agent (benzoyl peroxide) 5wt%, oxidant (sodium percarbonate) 5wt%, stabilizer (a mixture of fatty acid methyl ester sulfonate and alkyl glycoside in a mass ratio of 1:1) 4wt%, pH adjuster (soda ash) 1wt%, preservative (sodium diacetate) 0.5wt% and balance water.

[0042] The preparation steps of the non-foaming dispersant are as follows:

[0043] 5 parts of surfactant were added to 75.5 parts of water, and the mixture was stirred and dissolved at a speed of 90 rpm to obtain a mixture 1. After standing for 30 minutes, 4 parts of ion repulsion agent were added, and the mixture was stirred and dissolved at a speed of 90 rpm to obtain a mixture 2. After standing for 10 minutes again, 4 parts of stabilizer were added to ensure the overall stability of the foam-free dispersant when the oxidant was added later, and the mixture was stirred and dissolved at a speed of 90 rpm to obtain a mixture 3. Soda ash was added to the mixture 3 to adjust the pH to 8 (the amount of soda ash added was 1 part) to enhance the stability of the foam-free dispersant, and then 5 parts of cross-linking agent were added, and the mixture was stirred and dissolved at a speed of 30 rpm (to prevent the stirring rate from being too fast to activate the foam-free dispersant) and then 5 parts of oxidant were added, and the mixture was stirred and dissolved at a speed of 60 rpm. After that, 0.5 parts of preservative were added, and the mixture was stirred and dissolved at a speed of 60 rpm to obtain a foam-free dispersant.

[0044] 2. Application of non-foaming dispersant in cleaning silted clay in mud shield

[0045] The foam-free dispersant and water were mixed at a mass ratio of 3:97 to obtain a dispersant solution with a mass concentration of 3% of the foam-free dispersant; the dispersant solution was added to the waste mud in the mud and water bin of the shield. The volume of the silted clay in the mud and water bin was about 6m 3 , inject 0.2m 3 Dispersant solution, soaking chamber for 2 hours, no foam was observed during the action of dispersant. After the soaking chamber was finished, the surface of the silted clay cake softened and was decomposed into loose soft soil, which was very easy to be washed and cleaned. Under the 3MPa water pressure, the mud cake attached to the chamber and the cutter disc fell off, and the silted clay could be removed by flushing with clean water. When flushing with clean water at 3MPa water pressure, about 95% of the clay was flushed out, and only a small amount of residual clay was attached to the cutter disc and the inner wall, which did not affect the normal operation of the shield at all.

[0046] Example 2

[0047] 1. Preparation of non-foaming dispersant

[0048] Calculated by mass percentage, the raw material composition of the foam-free dispersant is: surfactant (a mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide in a mass ratio of 2:1) 6wt%, ion repulsion agent (vinyl pyridinium bromide) 3wt%, cross-linking agent (di-tert-butyl peroxide) 6wt%, oxidant (sodium perborate) 5wt%, stabilizer (a mixture of fatty acid methyl ester sulfonate and alkyl glycoside in a mass ratio of 1:1) 6wt%, pH adjuster (soda ash) 1wt%, preservative (calcium propionate) 0.5wt% and balance water.

[0049] The preparation steps of the non-foaming dispersant are as follows:

[0050] 6 parts of surfactant were added to 72.8 parts of water, and the mixture was stirred and dissolved at a speed of 90 rpm to obtain a mixture 1. After standing for 30 minutes, 3 parts of ion repulsion agent were added, and the mixture was stirred and dissolved at a speed of 60 rpm to obtain a mixture 2. After standing for 10 minutes again, 6 parts of stabilizer were added to ensure the overall stability of the foam-free dispersant when the oxidant was added later, and the mixture was stirred and dissolved at a speed of 60 rpm to obtain a mixture 3. Soda ash was added to the mixture 3 to adjust the pH to 8 (the amount of soda ash added was 0.7 parts) to enhance the stability of the foam-free dispersant, and then 6 parts of cross-linking agent were added, and the mixture was stirred and dissolved at a speed of 30 rpm (to prevent the stirring rate from being too fast to activate the foam-free dispersant) and then 5 parts of oxidant were added, and the mixture was stirred and dissolved at a speed of 60 rpm. After that, 0.5 parts of preservative were added, and the mixture was stirred and dissolved at a speed of 60 rpm to obtain a foam-free dispersant.

[0051] 2. Application of non-foaming dispersant in cleaning silted clay in mud shield

[0052] The foam-free dispersant and water were mixed at a mass ratio of 1.5:98.5 to obtain a dispersant solution with a mass concentration of 1.5% of the foam-free dispersant; the dispersant solution was added into the mud and water bin of the shield, and the volume of the accumulated clay in the mud and water bin was about 6m 3 , inject 0.3m 3 Dispersant solution, soaking chamber for 1.5 hours, no foam was observed during this period. After the soaking, the surface of the silted clay cake softened and was decomposed into loose soft soil, which was very easy to be washed and cleaned. Under the 3MPa water pressure, the mud cake attached to the chamber and the cutter disc fell off, and the silted clay could be removed by flushing with clean water. When flushing with clean water at 3MPa water pressure, about 80% of the clay was flushed out, and only a small amount of residual clay was attached to the cutter disc and the inner wall, which did not affect the normal operation of the shield at all.

[0053] Comparative Example 1

[0054] The same as Example 1, the only difference is that the use of tetramethyl phosphonium bromide is omitted, that is, the surfactant is a cocamidopropyl betaine, and the amount of the surfactant remains unchanged. When the dispersant configured in this scheme is used for soaking, the silted clay is slightly softened within 2 hours, and is relatively loose after 4 hours. The clay is difficult to be washed out under the flushing of clean water at a water pressure of 3MPa, and about 40% of the residual clay is attached to the cutter head and the inner wall.

[0055] Comparative Example 2

[0056] The same as Example 1, except that the use of the ion repellent is omitted. When the dispersant configured in this scheme is used for soaking, the silted clay is only slightly softened within 2 hours, and the clay is relatively loose after 4 hours. The clay is difficult to be washed out under the flushing of clean water at a water pressure of 3MPa, and about 60% of the residual clay adheres to the cutter head and the inner wall.

[0057] Comparative Example 3

[0058] The same as Example 1, except that the use of the cross-linking agent is omitted. When the dispersant configured in this scheme is used for soaking, the silted clay is only slightly softened within 2 hours, and the clay is loose after 4 hours. The clay is difficult to be washed out under the flushing of clean water at a water pressure of 3MPa, and about 60% of the residual clay adheres to the cutter head and the inner wall.

[0059] Comparative Example 4

[0060] The same as Example 1, except that the use of oxidant is omitted. When the dispersant configured in this scheme is used for soaking, the silted clay is only slightly softened within 2 hours, and the clay is loose after 6 hours. The clay is difficult to be washed out under the scouring of 3MPa water pressure, and about 70% of the residual clay is attached to the cutter head and the inner wall.

[0061] Comparative Example 5

[0062] The same as Example 1, the only difference is that the use of alkyl glycoside is omitted, that is, the stabilizer is a fatty acid methyl ester sulfonate, and the amount of the stabilizer remains unchanged. The dispersant configured in this scheme is used for soaking, and a small amount of precipitated calcium scale is produced, and the clay dispersion effect is poor. The silted clay is only slightly softened within 2 hours, and the clay is loose after 6 hours. The clay is difficult to be washed out under the flushing of clean water at a water pressure of 3MPa, and about 60% of the residual clay is attached to the cutter head and the inner wall.

[0063] Comparative Example 6

[0064] The same as Example 1, the only difference is that the mixing order of the stabilizer and the cross-linking agent is interchanged, that is, the cross-linking agent is added first and then the stabilizer. The preparation steps of the non-foaming dispersant are as follows:

[0065] Add 5 parts of surfactant to 75.5 parts of water, stir and dissolve at a speed of 90 rpm to obtain mixture 1, let it stand for 30 minutes, add 4 parts of ion repulsion agent, stir and dissolve at a speed of 90 rpm to obtain mixture 2, let it stand for 10 minutes again, add 5 parts of cross-linking agent, stir and dissolve at a speed of 90 rpm to obtain mixture 3; add 1 part of soda ash to mixture 3, and then add 4 parts of stabilizer, stir and dissolve at a speed of 30 rpm, then add 5 parts of oxidant, stir and dissolve at a speed of 60 rpm, then add 0.5 parts of preservative, stir and dissolve at a speed of 60 rpm to obtain a foam-free dispersant.

[0066] When the dispersant configured in this scheme is used for soaking, the clay dispersion effect is poor, the silted clay softens within 2 hours, and the clay is loose after 4 hours. The clay is easily washed out under the flushing of clean water at a water pressure of 3MPa. About 75% of the residual clay adheres to the cutter disc and the inner wall.

[0067] In addition, the dispersants prepared in Comparative Example 6 and Example 1 were tested for shelf life. When floccules were generated in the dispersant, the dispersant lost its anti-sticking dispersion effect and was considered invalid. After testing, the dispersant prepared in Example 1 had a shelf life of 6 months. The dispersant prepared in Comparative Example 6 had visible turbid floccules in the transparent dispersant after 3 months, and the shelf life of the dispersant was reduced to 3 months.

[0068] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A non-foaming dispersant for cleaning clay deposits in a mud shield, characterized in that: The raw materials include, by mass percentage, 4-8 wt% of a mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide, 2-5 wt% of an ion repellent, 5-10 wt% of a cross-linking agent, 4-10 wt% of an oxidant, 3-5 wt% of a stabilizer, 0.5-1 wt% of a pH regulator, 0.5-1 wt% of a preservative, and the balance of water; The mass ratio of cocamidopropyl betaine and tetramethyl phosphonium bromide in the mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide is 2:1-3:1; The ion repellent is dodecylpyridinium bromide or vinylpyridinium bromide; The cross-linking agent is an organic peroxide; The stabilizer is a mixture of fatty acid methyl ester sulfonate and alkyl glucoside; the mass ratio of fatty acid methyl ester sulfonate to alkyl glucoside in the stabilizer is 1:1-1:2; The method for preparing the non-foaming dispersant for cleaning silted clay in a slurry shield comprises the following steps: A mixture of cocamidopropyl betaine and tetramethyl phosphonium bromide and water are mixed and stirred to obtain mixture 1, and an ion repellent is added after standing and stirred to obtain mixture 2, and a stabilizer is added after standing and stirred to obtain mixture 3; a pH adjuster is added to mixture 3 to adjust the pH to 7.5-8.5, and then a cross-linking agent, an oxidant and a preservative are added in sequence and stirred to obtain the non-foaming dispersant.

2. The non-foaming dispersant for cleaning muddy shield silt clay as claimed in claim 1, characterized in that: The oxidant is at least one of hydrogen peroxide, sodium perborate, sodium percarbonate and sodium peroxide.

3. The non-foaming dispersant for cleaning mud shield siltation clay as claimed in claim 1, characterized in that: The pH regulator is soda ash; the preservative is at least one of sodium diacetate, calcium propionate and dehydroacetic acid.

4. The use of the non-foaming dispersant according to any one of claims 1 to 3 in cleaning silted clay of a mud shield, characterized in that: The foam-free dispersant and water are mixed to obtain a dispersant solution; the dispersant solution is added into the mud and water bin of the shield machine for 1.5-2 hours; the volume ratio of the added dispersant solution to the silted clay in the mud and water bin is 0.2-0.3:

6.

5. The use according to claim 4, characterized in that The mass concentration of the dispersant in the dispersant solution is 1.5-3%.