A high-efficiency flocculant for shield construction and preparation method thereof

Abstract

The invention discloses a high-efficiency flocculant for shield construction and a preparation method thereof, and belongs to the technical field of shield construction. The invention prepares the high-efficiency flocculant by mixing modified polyacrylamide and inorganic flocculant, then adding biodegradable polymer and surfactant, and stirring evenly; the invention uses modified polyacrylamide, inorganic flocculant, biodegradable polymer and surfactant as raw materials, and through the interaction between the raw materials, the prepared high-efficiency flocculant can quickly promote the suspended particles in the mud to condense into large flocs, accelerate the sedimentation speed, and improve the efficiency of mud treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of shield construction, and in particular relates to a high-efficiency flocculant used for shield construction and a preparation method thereof. Background Art

[0002] With the acceleration of urbanization, the problem of ground traffic congestion has intensified, and the construction of subways has become one of the main means to solve urban traffic problems. This has led to an increase in demand for tunnel construction technology, especially shield construction method. Shield construction method is one of the main methods for urban subway section tunnel construction, especially widely used in soft soil areas. In tunnel shield construction, a large amount of soil will be generated, which will be mixed with mud and water to form mud. The mud generated by shield construction needs to be effectively treated to facilitate mud and water separation and recycling. However, in the existing technology, mud treatment has problems such as low efficiency, high cost, and environmental pollution. With the enhancement of environmental awareness, the environmental protection requirements of engineering construction are getting higher and higher. Waste slurry must be thoroughly treated harmlessly and ensure that the treatment process is low-carbon and environmentally friendly. Traditional mud treatment methods, such as natural drying or direct discharge, have problems such as low efficiency and environmental pollution. Mechanical treatment methods such as filtration or centrifugation have problems such as small treatment volume, high equipment investment cost, and large flocculant dosage. Therefore, in order to improve the efficiency and effect of mud treatment, it is necessary to develop new high-efficiency flocculants. This flocculant should be able to improve the flocculation effect of mud, reduce environmental pollution, and promote the resource utilization of waste mud. Summary of the invention

[0003] In view of the above technical problems, the present invention proposes a high-efficiency flocculant for shield construction and a preparation method thereof. The flocculant has the characteristics of high efficiency, low cost and environmental friendliness.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 3-5 parts of modified polyacrylamide, 1-5 parts of inorganic flocculant, 1 part of biodegradable polymer and 1 part of surfactant.

[0006] Furthermore, the preparation method of the modified polyacrylamide is: mixing polyacrylamide powder and dodecyldimethylbenzyl ammonium bromide in ethanol, reacting at 60° C. for 6 hours, and obtaining the modified polyacrylamide by centrifugal separation after the reaction is completed.

[0007] Furthermore, the inorganic flocculant is polyaluminium sulfate.

[0008] Furthermore, the biodegradable polymer is polyorthoester.

[0009] Furthermore, the surfactant is lecithin.

[0010] The present invention also provides a method for preparing a high-efficiency flocculant for shield construction, comprising the following steps: mixing modified polyacrylamide and an inorganic flocculant, then adding biodegradable polymers and surfactants, and stirring to obtain the high-efficiency flocculant.

[0011] The invention also provides an application of a high-efficiency flocculant for shield construction in shield construction.

[0012] Compared with the prior art, the present invention has the following advantages and technical effects:

[0013] The present invention uses modified polyacrylamide, inorganic flocculant, biodegradable polymer and surfactant as raw materials, and a charge neutralization reaction occurs between the cationic modified polyacrylamide and the anionic inorganic flocculant to form larger flocs, so that the prepared high-efficiency flocculant can quickly promote the suspended particles in the mud to condense into large flocs, accelerate the sedimentation rate, and improve the efficiency of mud treatment. Through flocculation, the fluidity and stability of the mud are improved, and the wear of the mud on the equipment and the impact on the construction environment are reduced. The present invention improves the solid-liquid separation efficiency of the mud and reduces the discharge of waste slurry to achieve the purpose of reducing the pollution of the waste mud to the environment. Since the use amount of the high-efficiency flocculant is relatively small, the material cost can also be reduced, and the increase in processing speed also reduces energy consumption and labor costs. The treated mud can be used as a building material or filling material for resource utilization, reducing the exploitation of natural resources. The research and development and application of high-efficiency flocculants tend to be environmentally friendly, reducing the impact on the environment during the construction process, and helping to achieve green construction and sustainable development. DETAILED DESCRIPTION

[0014] 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.

[0015] It should be understood that the terms described in the present invention are only for describing special embodiments 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. Each smaller range between the intermediate value in any stated value or stated range and 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.

[0016] 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.

[0017] 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 those skilled in the art. The present invention description and examples are exemplary only.

[0018] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0019] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 3-5 parts of modified polyacrylamide, 1-5 parts of inorganic flocculant, 1 part of biodegradable polymer and 1 part of surfactant. Preferably, the mass ratio of modified polyacrylamide to inorganic flocculant is 1:1.

[0020] In the following examples of the present invention, the preparation method of the modified polyacrylamide is as follows: the polyacrylamide powder is refined to make the particle size of the refined polyacrylamide in the range of 100-400 meshes, and its surface area is increased; 10 parts of the refined polyacrylamide powder is mixed with 1 part of dodecyl dimethyl benzyl ammonium bromide in 1 part of ethanol; the reaction temperature is 60°C; the reaction time is 6 hours; after the reaction is completed, the modified polyacrylamide is obtained by centrifugal separation. The modified polyacrylamide prepared by the modification method has better flocculation effect and stability.

[0021] In the following embodiments of the present invention, the inorganic flocculant is polyaluminium sulfate. The mixture of polyaluminium sulfate and modified polyacrylamide produces a synergistic effect, thereby improving the flocculation efficiency.

[0022] In the following embodiments of the present invention, the biodegradable polymer is polyorthoester, which helps to reduce environmental pollution.

[0023] In the following embodiments of the present invention, the surfactant is lecithin, which is used to adjust the surface tension of the mud-water mixture and improve the flocculation effect.

[0024] The method for preparing the high-efficiency flocculant used for shield construction comprises the following steps: mixing modified polyacrylamide and inorganic flocculant, then adding biodegradable polymer and surfactant, and stirring well to obtain the high-efficiency flocculant.

[0025] The high-efficiency flocculant for shield construction can be used in shield construction.

[0026] The "parts" described in the present invention, unless otherwise specified, refer to parts by mass.

[0027] The raw materials used in the present invention are all purchased from the market.

[0028] The technical solution of the present invention is further illustrated by the following embodiments.

[0029] Example 1

[0030] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 5 parts of modified polyacrylamide, 5 parts of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0031] Preparation method:

[0032] S1. Preparation of modified polyacrylamide: refine polyacrylamide powder to make the particle size of the refined polyacrylamide between 100-400 meshes, mix 10 parts of the refined polyacrylamide powder with 1 part of dodecyldimethylbenzyl ammonium bromide in 1 part of ethanol, react at 60°C for 6 hours, and obtain the modified polyacrylamide by centrifugal separation after the reaction is completed.

[0033] S2. Mix and stir the modified polyacrylamide and polyaluminum sulfate for 10 minutes, then add polyorthoester and lecithin, and continue stirring for 20 minutes until they are completely dissolved, thereby obtaining a high-efficiency flocculant.

[0034] Example 2

[0035] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 5 parts of modified polyacrylamide, 4 parts of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0036] Preparation method: Same as Example 1.

[0037] Example 3

[0038] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 5 parts of modified polyacrylamide, 3 parts of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0039] Preparation method: Same as Example 1.

[0040] Example 4

[0041] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 5 parts of modified polyacrylamide, 2 parts of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0042] Preparation method: Same as Example 1.

[0043] Example 5

[0044] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 5 parts of modified polyacrylamide, 1 part of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0045] Preparation method: Same as Example 1.

[0046] Example 6

[0047] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 4 parts of modified polyacrylamide, 5 parts of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0048] Preparation method: Same as Example 1.

[0049] Example 7

[0050] A high-efficiency flocculant for shield construction comprises the following raw materials in parts by weight: 3 parts of modified polyacrylamide, 5 parts of polyaluminium sulfate, 1 part of polyorthoester and 1 part of lecithin.

[0051] Preparation method: Same as Example 1.

[0052] Comparative Example 1

[0053] Cationic polyacrylamide flocculant produced by novel polymer is selected.

[0054] Comparative Example 2

[0055] Same as Example 1, except that 5 parts of modified polyacrylamide are replaced by 5 parts of polyacrylamide.

[0056] Comparative Example 3

[0057] Same as Example 1, except that 5 parts of polyaluminium sulfate are replaced by 5 parts of aluminium chloride inorganic flocculant in the prior art.

[0058] Comparative Example 4

[0059] Same as Example 1, except that 1 part of polyorthoester is replaced by 1 part of polyamino acid biodegradable polymer in the prior art.

[0060] Comparative Example 5

[0061] Same as Example 1, except that 1 part of lecithin is replaced by 1 part of dodecyl ethoxy sulfobetaine surfactant in the prior art.

[0062] Effect verification: Taking the samples of the above embodiment and comparative example as examples, the following performance tests were carried out

[0063] (1) Turbidity removal rate test: Turbidity removal rate = (inlet turbidity - outlet turbidity) / inlet turbidity × 100%.

[0064] (2) Degradation time test: S1. Take a flocculant sample and dissolve or disperse it in water; S2. The time point when the performance deteriorates to the point where it no longer meets the application requirements is defined as the degradation time of the flocculant.

[0065] (3) Toxic substance residual concentration test: Toxic substances (nitrogen and phosphorus) are measured using liquid phase gas spectrometry.

[0066] (4) Flocculation time test:

[0067] S1. Add 5 g of flocculant to 1000 g of mud sample under rapid stirring (stirring rate of 3000 rpm) to ensure uniform distribution of flocculant;

[0068] S2. The slurry-flocculant mixture was rapidly stirred using a stirrer (stirring rate was 3000 rpm) to promote the start of the flocculation reaction;

[0069] S3. After rapid stirring, switch to slow stirring (stirring rate is 1500 rpm) or completely still to observe the formation and sedimentation of flocs;

[0070] S4. Start with slow stirring or stillness, observe the formation of flocs in the mud sample, and record the time when flocs begin to form;

[0071] S5. Continue to observe until the time required for the flocs to settle to the bottom of the container, and record this time point;

[0072] S6. Flocculation time can be determined by measuring the total time required from the addition of flocculant to the settling of flocs.

[0073] Table 1

[0074]

[0075] As can be seen from Table 1, the turbidity removal rate of the flocculant in the present invention is improved compared with that in Comparative Example 1; the residual toxic substances decrease as the dosage decreases. In general, the residual toxic substances are reduced by more than 40%, which means that the harm to the environment is reduced and it is more environmentally friendly. The reduction in degradation time helps to achieve green construction and sustainable development. The reduction in flocculation time means that the mud processing speed is accelerated, thereby improving the efficiency of shield construction and shortening the construction period. Rapid flocculation helps to reduce the stacking time of mud during the treatment process, reduce potential pollution to the surrounding environment, help improve the fluidity and stability of the mud, reduce the wear on shield equipment, and improve construction safety. The reduction in flocculation time can improve the processing capacity of the mud treatment system, that is, more mud can be processed per unit time.

[0076] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A high-efficiency flocculant for shield construction, characterized in that: The method comprises the following raw materials in parts by weight: 3-5 parts of modified polyacrylamide, 1-5 parts of inorganic flocculant, 1 part of biodegradable polymer and 1 part of surfactant; The preparation method of the modified polyacrylamide is as follows: polyacrylamide powder and dodecyl dimethyl benzyl ammonium bromide are mixed in ethanol, reacted at 60° C. for 6 hours, and after the reaction is completed, the modified polyacrylamide is obtained by centrifugal separation.

2. The high-efficiency flocculant for shield construction according to claim 1, characterized in that: The inorganic flocculant is polyaluminium sulfate.

3. The high-efficiency flocculant for shield construction according to claim 1, characterized in that: The biodegradable polymer is polyorthoester.

4. The high-efficiency flocculant for shield construction according to claim 1, characterized in that: The surfactant is lecithin.

5. A method for preparing a high-efficiency flocculant for shield construction as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: The modified polyacrylamide and the inorganic flocculant are mixed, and then the biodegradable polymer and the surfactant are added and stirred well to obtain a high-efficiency flocculant.

6. Use of the high-efficiency flocculant for shield construction as claimed in any one of claims 1 to 4 in shield construction.

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