Determination method for proportion of defoaming agent for resource utilization of earth pressure balance shield muck and preparation method of defoaming agent

Abstract

The invention relates to a method for determining the proportion of a defoaming agent for resource utilization of earth pressure balance shield muck and a method for preparing the defoaming agent, and belongs to the technical field of building construction. According to the defoaming agent proportion determination method, the proportion of the defoaming agent is determined through a response surface method, the optimal mixing proportion of all components in the defoaming agent can be obtained, and the requirements for defoaming and foam inhibition performance in shield muck treatment are met. According to the method disclosed by the invention, the optimal mix proportion of each component in the defoaming agent can be obtained, the requirements on defoaming and foam inhibition performance in shield muck treatment are met, the application range is wide, the number of experimental groups is reduced, a simple and convenient method is provided for preparing the defoaming agent for recycling the shield muck, and the construction cost is reduced and the engineering efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and particularly relates to a method for determining a defoaming agent ratio for resource utilization of earth pressure balance shield slag and a method for preparing the defoaming agent. Background Art

[0002] During the construction of earth pressure balance shield tunnels, a large amount of slag with high water content, poor mechanical properties and residual foaming agent will be produced during the tunneling process of the shield machine. Traditional landfill or abandonment disposal methods not only cause environmental pollution, waste of resources and safety hazards, but also with the saturation or overload of urban and suburban slag sites, the cost of slag disposal is getting higher and higher, and the difficulty is getting greater and greater. How to harmlessly treat these shield slag and recycle them as resources is still a difficult problem that needs to be solved.

[0003] In-situ resource utilization is an effective means of disposing of waste soil, which can bring significant social and economic benefits. However, the residual foaming agent produces a large amount of foam, which is easy to adsorb clay particles on the surface, causing overflow problems and reducing the flocculation and filter pressing efficiency. Defoaming agents are widely used in many fields such as construction, sewage treatment, chemical production, food and beverage, etc. They can quickly and effectively eliminate foam and inhibit foam regeneration, which can significantly improve process efficiency and reduce energy consumption and costs. The in-situ resource utilization process of shield soil includes: (1) vibration screening system: the soil generated after construction is initially separated by high-pressure spraying and vibration separation to obtain a fluid mixture of gravel particles and mud; (2) sand washing system: the sand and gravel particles separated in the previous stage are separated into finished sand and mud by sand washing machine and cyclone in turn; (3) flocculation system: the waste mud enters the flocculation tank through the slurry pump, and is finally separated into mud cake and water under the filtration action of the filter press. The specific use of defoaming agent in the process of treating earth pressure balance shield slag is as follows: add the pre-diluted and evenly stirred defoaming agent to the mud pool in stage (2), and the defoaming agent flows into the mud pool under the action of the pump to mix with the foam to defoam. After defoaming treatment, the separated mud can smoothly proceed to the subsequent mud pumping and filter pressing processes, thereby realizing the resource utilization of shield slag.

[0004] At present, most of the research on the formulation of defoaming agents is based on single-factor experiments or orthogonal experiments to seek the optimal ratio. However, when multiple factors are involved, the interaction between the factors makes the experimental workload large, and the research on the influence of each component in the defoaming agent on its defoaming and anti-foaming performance is relatively weak.

[0005] The existing defoaming agents have slow defoaming speed and poor anti-foaming performance, and the shield foaming agent is a compound of multiple surfactants, foam stabilizers and dispersants. The commonly used defoaming agents on the market are high in cost, and are difficult to defoam in shield slag treatment and have low efficiency. Summary of the invention

[0006] The purpose of the present invention is to solve the problems of low defoaming and foam suppression rates, large dosage and high cost of existing defoaming agents in the market for slag treatment, and to provide a method for determining the defoaming agent ratio and a defoaming agent preparation method for resource utilization of earth pressure balance shield slag, a method for determining the defoaming agent mix ratio and a preparation method thereof, which can obtain the optimal mix ratio of each component in the defoaming agent, meet the requirements for defoaming and foam suppression performance in shield slag treatment, have a wide range of applications, reduce the number of experimental groups, provide a simple method for the preparation of defoaming agents for shield slag recycling, and help reduce construction costs and improve engineering efficiency.

[0007] To achieve the above-mentioned purpose, the technical solution of the present invention is: a method for determining the ratio of defoaming agent for resource utilization of earth pressure balance shield slag, which determines the ratio of the defoaming agent by response surface methodology, and can obtain the optimal ratio of each component in the defoaming agent to meet the requirements of defoaming and anti-foaming performance in shield slag treatment.

[0008] In one embodiment of the present invention, the method comprises the following steps:

[0009] Based on the dynamic defoaming process of the improved flocculation tank scale model, the defoaming and foam suppression rate test of the defoamer was carried out to obtain the optimal dosage range of each component of the defoamer;

[0010] In the optimal dosage range, the dosage of each defoamer component was used as the main variable, and the 5-min defoaming rate DFR and the 25-min antifoaming rate AFR were used as the response quantities to conduct a response surface test to obtain the response value test results under different mix ratios.

[0011] Perform nonlinear fitting on the response value test results and establish a response surface model;

[0012] Based on the response surface model, combined with the defoaming and antifoaming performance requirements, the expected values ​​of each response quantity are obtained;

[0013] Based on the expected values ​​of each response quantity, the optimal mix ratio of shield defoamer is obtained.

[0014] In one embodiment of the present invention, the components of the defoaming agent include hydroxy silicone oil, hydrophobic nano-silica, glycerol polyoxypropylene ether, composite emulsifier, thickener and deionized water.

[0015] In one embodiment of the present invention, the optimal dosage range of hydroxy silicone oil is 4.7% to 23.5%, the optimal dosage range of hydrophobic nano-silica is 0.3 to 1.5%, the optimal dosage range of glycerol polyoxypropylene ether is 4.7% to 23.5%, the optimal dosage range of composite emulsifier is 1.5 to 7.5%, the dosage range of thickener is 0.7%, and the rest is deionized water.

[0016] In one embodiment of the present invention, the composite emulsifier includes Span 80 and Tween 80.

[0017] In one embodiment of the present invention, the process of obtaining the response value experimental results under different mix ratios includes: pouring 1L of foaming agent solution into a scaled model of an improved flocculation tank containing 10% dry soil, rotating at 1000 rpm for 5 minutes, standing for two minutes to record the initial foam height H0, then dropping 0.1% defoaming agent into the scaled model of the improved flocculation tank, rotating at 500 rpm for 5 minutes, standing for two minutes to record the foam height H d The soil-foaming agent-defoaming agent mixture was left to stand for 23 minutes, rotated at 1000 rpm for 5 minutes, and then left to stand for two minutes to record the foam height H. a ; Calculate the defoaming rate DFR and antifoaming rate AFR of the defoaming agent under different mixing ratios.

[0018] In one embodiment of the present invention, the defoaming rate DFR and the antifoaming rate AFR of the defoaming agent at different mixing ratios are calculated by the following formula:

[0019]

[0020]

[0021] In one embodiment of the present invention, the process of establishing a response quantity model includes: establishing a response surface model based on a quadratic polynomial equation, substituting the response value test results into the quadratic polynomial equation, obtaining the model regression equation coefficients, and then using variance to evaluate the effectiveness of the response surface model.

[0022] The present invention also provides a method for preparing a defoaming agent for resource utilization of earth pressure balance shield slag, comprising the following steps:

[0023] Step S1, adding hydrophobic nano-silica and hydroxy silicone oil into a reaction kettle, stirring magnetically at 180° C. for 6 h, discharging after cooling, and obtaining a silicone paste;

[0024] Step S2, pouring glycerol polyoxypropylene ether and composite emulsifier into the silicone paste obtained in the reaction of step S1, and mechanically stirring at 100° C. and 1000 rpm for 30 minutes;

[0025] Step S3, adding a thickener and deionized water to the primary emulsion obtained in step S2, and mechanically stirring at 100° C. and 1000 rpm for 1 h to obtain a defoaming agent primary emulsion;

[0026] Step S4, placing the defoaming agent primary emulsion in an emulsifier, and emulsifying at a speed of 10000 rpm for 20 minutes to obtain the defoaming agent.

[0027] In one embodiment of the present invention, the preparation method uses the optimal proportion of each component in the defoaming agent determined by any of the above-mentioned methods for determining the proportion of the defoaming agent for resource utilization of earth pressure balance shield slag to prepare the defoaming agent.

[0028] Compared with the prior art, the present invention has the following beneficial effects: the method of the present invention provides a method for determining the mix ratio of a defoaming agent and a corresponding method for preparing a defoaming agent, which can obtain the optimal mix ratio of each component in the defoaming agent, meet the requirements for defoaming and anti-foaming performance in shield slag treatment, have a wide range of applications, reduce the number of experimental groups, and provide a simple method for the preparation of defoaming agents for the recycling of shield slag, which helps to reduce construction costs and improve engineering efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic flow chart of a method for determining the ratio of a defoaming agent for resource utilization of earth pressure balance shield slag.

[0030] Figure 2 To improve the scale model of flocculation tank.

[0031] Figure 3 It is the defoaming rate response trajectory of the defoaming agent within 5 minutes.

[0032] Figure 4 It is the response trajectory of the defoaming agent's 25-min antifoaming rate.

[0033] Figure 5 This is the response surface diagram of the effect of the concentration of each component of the defoaming agent on the 5-min defoaming rate.

[0034] Figure 6 This is the response surface diagram of the effect of the concentration of each component of the defoaming agent on the 25min antifoaming rate.

[0035] Figure 7 Comparison between the predicted value and the experimental value of the 5-minute defoaming rate.

[0036] Figure 8 Comparison between the predicted value and the experimental value of the 25-minute foam suppression rate.

[0037] Fig. 9 It is the studentized external residual of the 5-min defoaming rate.

[0038] Fig.10 It is the studentized external residual of the foam suppression rate for 25 min. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0040] like Figure 1As shown, the present invention provides a method for determining the ratio of a defoaming agent for resource utilization of earth pressure balance shield slag, comprising the following steps:

[0041] Based on the improved scale model of flocculation tank (such as Figure 2 The dynamic defoaming process (shown) is used to test the defoaming and foam suppression rate of the defoamer to obtain the optimal dosage range of each component of the defoamer;

[0042] In the optimal dosage range, the dosage of each defoamer component was used as the main variable, and the 5-min defoaming rate (DFR) and 25-min antifoaming rate (AFR) were used as the response quantities to conduct a response surface test to obtain the response value test results under different mix ratios.

[0043] Performing nonlinear fitting on the response value test results to establish a response surface model;

[0044] Based on the response surface model, combined with the defoaming and antifoaming performance requirements, the expected value of each response amount is obtained;

[0045] Based on the expected values ​​of the various response quantities, the optimal mix ratio of the shield defoamer is obtained.

[0046] Optionally, the components of the defoamer include hydroxy silicone oil, hydrophobic nano-silica, glycerol polyoxypropylene ether, composite emulsifier (composite emulsifier includes Span 80 and Tween 80), thickener and deionized water. Among them, the optimal dosage of hydroxy silicone oil is 4.7% to 23.5%, the optimal dosage of hydrophobic nano-silica is 0.3 to 1.5%, the optimal dosage of glycerol polyoxypropylene ether is 4.7% to 23.5%, the optimal dosage of composite emulsifier is 1.5 to 7.5%, the dosage of thickener is 0.7%, and the rest is deionized water.

[0047] Optionally, the process of obtaining the response value experimental results under different mix ratios includes: pouring 1L of the foaming agent solution into a scaled model of an improved flocculation tank containing 10% dry soil (100g dry soil), rotating at 1000rpm for 5min, standing for two minutes to record the initial foam height H0, then dropping 0.1% of the defoaming agent into the scaled model of the improved flocculation tank, rotating at 500rpm for 5min, standing for two minutes to record the foam height H0. d The soil-foaming agent-defoaming agent mixture was left to stand for 23 minutes, rotated at 1000 rpm for 5 minutes, and then left to stand for two minutes to record the foam height H. a The defoaming rate (DFR) and antifoaming rate (AFR) of the defoamer under different mixing ratios can be calculated by the following formula:

[0048]

[0049] Optionally, the process of establishing the response quantity model includes: establishing a response surface model based on a quadratic polynomial equation, substituting the response value test results into the above quadratic polynomial equation to obtain the model regression equation coefficients, and then using variance to evaluate the effectiveness of the response surface model.

[0050] Based on the above-mentioned method for determining the ratio of defoaming agent, the present invention also provides a method for preparing a defoaming agent as follows:

[0051] Step S1, adding hydrophobic nano-silica and hydroxy silicone oil into a reaction kettle, stirring magnetically at 180° C. for 6 h, discharging after cooling, and obtaining a silicone paste;

[0052] Step S2, pouring glycerol polyoxypropylene ether and composite emulsifier into the silicone paste obtained in the reaction of step S1, and mechanically stirring at 100° C. and 1000 rpm for 30 minutes;

[0053] Step S3, adding a thickener and deionized water to the primary emulsion obtained in step S2, and mechanically stirring at 100° C. and 1000 rpm for 1 h to obtain a defoaming agent primary emulsion;

[0054] Step S4, placing the above defoaming agent primary emulsion in an emulsifier, and emulsifying at a speed of 10000 rpm for 20 minutes to obtain the shield defoaming agent.

[0055] The following are specific implementation examples of the present invention.

[0056] Embodiment 1:

[0057] This example provides a method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag based on response surface methodology, comprising the following steps:

[0058] Step 1: Select the 5-min defoaming rate and 25-min foam suppression rate in the improved flocculation tank scale model as the response quantity, and collect the experimental results of the response values ​​under different main variable ratios, specifically:

[0059] The central composite design (CCD) experimental design scheme in the response surface methodology was adopted, as shown in Table 1, including the CCD experimental influencing factors and levels coded as A, B, C, D, and E:

[0060] Table 1

[0061]

[0062] By changing the dosage of each component in the defoamer, multiple tests were conducted, and the response value test results under different main variable ratios were collected, as shown in Table 2:

[0063] Table 2

[0064]

[0065]

[0066] The above test results were subjected to nonlinear fitting, and a quadratic polynomial regression equation was established by selecting an appropriate quadratic polynomial regression model.

[0067] The experimental data were fitted with a quadratic polynomial regression, and the significance test and variance results of each coefficient were obtained as shown in Tables 3 and 4.

[0068] Response value 1: Defoaming rate (DFR)

[0069] Table 3

[0070]

[0071] DFR(R1)=71.73+0.76A+16.66B+0.23C+1.21D+0.57E+0.25AB+0.006AC-0.05AD

[0072] -0.01AE-0.03BC-1.02BD-1.64BE+0.04CD-0.08CE+0.06DE-0.02A 2

[0073] -4.22B 2 -0.26D 2 +0.28E 2

[0074] Response value 2: Antifoam Rate (AFR)

[0075] Table 4

[0076]

[0077] AFR(R2)=30.52+0.16A+19.22B-0.81C-20.31D+11.22E-0.34AB+0.02AC+0.06AD

[0078] +0.18AE-0.80BC-0.48BD-2.42BE-0.24CD-0.27CE+3.09DE+0.03A 2

[0079] +0.73B 2 +0.1C 2 +3.61D 2 -4.49E 2

[0080] Figure 3 and Figure 4 The response trajectory of different variables to defoaming rate and antifoaming rate is shown. Figure 2 It can be seen that with the increase of hydroxy silicone oil, hydrophobic nano-silica, and glycerol polyoxypropylene ether, the 5-min defoaming rate increased significantly. Figure 3 It can be seen that with the increase of the content of hydroxy silicone oil and glycerol polyoxypropylene ether, the anti-foaming performance of the defoamer is significantly improved. This is because the addition of hydrophobic nano-silica reduces the entry barrier and entry depth of hydroxy silicone oil in the bubble film. As the reaction of hydrophobic nano-silica and the -OH chemical grafting of the hydroxy silicone oil molecule terminal proceeds, the hydrophobic nano-silica exerts its unique needle tip effect and penetration effect. This synergistic effect significantly improves the defoaming performance of the defoamer. As a polyether-type defoamer, glycerol polyoxypropylene ether itself has a strong anti-foaming ability. Therefore, after compounding glycerol polyoxypropylene ether with hydroxy silicone oil, hydrophobic nano-silica and emulsifier, the anti-foaming performance of the defoamer is significantly improved.

[0081] Figure 5 and Figure 6 They are the response surface diagrams of the interaction of each component in the defoaming agent on the 5min defoaming rate and the 25min antifoaming rate.

[0082] Figure 7 This is a comparison chart of the predicted value and experimental value of the defoaming rate of the defoaming agent in 5 minutes. The inclined straight line in the figure is the predicted value of the defoaming rate in 5 minutes, and the experimental value of the defoaming rate in 5 minutes is always distributed around the inclined straight line.

[0083] Figure 8 This is a comparison chart of the predicted value and experimental value of the 25-minute foam suppression rate of the defoamer. The inclined straight line in the figure is the predicted value of the 25-minute foam suppression rate, and the experimental value of the 25-minute foam suppression rate is always distributed around the inclined straight line.

[0084] Fig. 9 and Fig.10 They are the studentized external residual diagrams of the defoaming rate at 5 minutes and the defoaming rate at 25 minutes. Fig. 9 and Fig.10 It can be seen that the recipe optimization model provided by this embodiment has high accuracy.

[0085] Step 2: According to the performance requirements of defoaming and foam suppression in the scaled model of the improved flocculation tank, the defoaming rate (DFR) and foam suppression rate (AFR) are expected to be maximized, and the dosage of each component in the defoamer is expected to be minimized. Based on the above expected response values, the theoretical optimal mix ratio is obtained by the response surface method, wherein the predicted optimal mix ratio is: the mass proportion of hydroxy silicone oil is 15.69%, the mass proportion of hydrophobic nano-silica is 1.09%, the mass proportion of glycerol polyoxypropylene ether is 4.70%, the mass proportion of Span 80 is 0.875%, and the mass proportion of Tween 80 is 0.63%. This ratio is the optimal mix ratio of the defoamer in this application.

[0086] Example 2: Different from Example 1, in this example, the mass proportion of hydroxy silicone oil is 14.54%, the mass proportion of hydrophobic nano-silica is 1.12%, the mass proportion of glycerol polyoxypropylene ether is 4.70%, the mass proportion of Span 80 is 0.875%, and the mass proportion of Tween 80 is 0.625%. This ratio is the optimal ratio of the defoaming agent in this application.

[0087] Example 2: Different from Example 1, in this example, the mass proportion of hydroxy silicone oil is 16.85%, the mass proportion of hydrophobic nano-silica is 1.17%, the mass proportion of glycerol polyoxypropylene ether is 4.7%, the mass proportion of Span 80 is 0.88%, and the mass proportion of Tween 80 is 0.625%. This ratio is the optimal ratio of the defoaming agent in this application.

[0088] Example 3: Different from Example 1, in this example, the mass proportion of hydroxy silicone oil is 16.68%, the mass proportion of hydrophobic nano-silica is 1.08%, the mass proportion of glycerol polyoxypropylene ether is 7.77%, the mass proportion of Span 80 is 0.88%, and the mass proportion of Tween 80 is 0.625%. This ratio is the optimal ratio of the defoaming agent in this application.

[0089] Example 3: Different from Example 1, in this example, the mass proportion of hydroxy silicone oil is 9.17%, the mass proportion of hydrophobic nano-silica is 0.83%, the mass proportion of glycerol polyoxypropylene ether is 4.70%, the mass proportion of Span 80 is 0.876%, and the mass proportion of Tween 80 is 0.81%. This ratio is the optimal ratio of the defoaming agent in this application.

[0090] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions do not exceed the scope of the technical solution of the present invention, belong to the protection scope of the present invention.

Claims

1. A method for determining the ratio of defoaming agent for resource utilization of earth pressure balance shield slag, characterized in that: The optimal ratio of each component in the defoamer can be obtained by determining the ratio of the defoamer through the response surface methodology, which can meet the requirements of defoaming and anti-foaming performance in shield slag treatment.

2. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 1 is characterized in that: The method comprises the following steps: Based on the dynamic defoaming process of the improved flocculation tank scale model, the defoaming and foam suppression rate test of the defoamer was carried out to obtain the optimal dosage range of each component of the defoamer; In the optimal dosage range, the dosage of each defoamer component was used as the main variable, and the 5-min defoaming rate DFR and the 25-min antifoaming rate AFR were used as the response quantities to conduct a response surface test to obtain the response value test results under different mix ratios. Perform nonlinear fitting on the response value test results and establish a response surface model; Based on the response surface model, combined with the defoaming and antifoaming performance requirements, the expected values ​​of each response quantity are obtained; Based on the expected values ​​of each response quantity, the optimal mix ratio of shield defoamer is obtained.

3. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 2 is characterized in that: The components of the defoaming agent include hydroxy silicone oil, hydrophobic nano-silica, glycerol polyoxypropylene ether, composite emulsifier, thickener and deionized water.

4. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 3 is characterized in that: The optimal dosage range of hydroxy silicone oil is 4.7% to 23.5%, the optimal dosage range of hydrophobic nano-silica is 0.3 to 1.5%, the optimal dosage range of glycerol polyoxypropylene ether is 4.7% to 23.5%, the optimal dosage range of composite emulsifier is 1.5 to 7.5%, the dosage range of thickener is 0.7%, and the rest is deionized water.

5. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 3 or 4, characterized in that: Compound emulsifiers include Span 80 and Tween 80.

6. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 1 is characterized in that: The process of obtaining the experimental results of the response value under different mix ratios includes: pouring 1L of the foaming agent solution into the scaled model of the improved flocculation tank containing 10% dry soil, rotating at 1000rpm for 5 minutes, standing for two minutes to record the initial foam height H0, then dropping 0.1% of the defoaming agent into the scaled model of the improved flocculation tank, rotating at 500rpm for 5 minutes, standing for two minutes to record the foam height H d The soil-foaming agent-defoaming agent mixture was left to stand for 23 minutes, rotated at 1000 rpm for 5 minutes, and then left to stand for two minutes to record the foam height H. a ; Calculate the defoaming rate DFR and antifoaming rate AFR of the defoaming agent under different mixing ratios.

7. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 6 is characterized in that: The defoaming rate DFR and antifoaming rate AFR of the defoamer under different mixing ratios are calculated by the following formula:

8. The method for determining the defoaming agent ratio for resource utilization of earth pressure balance shield slag according to claim 1 is characterized in that: The process of establishing the response quantity model includes: establishing a response surface model based on a quadratic polynomial equation, substituting the response value test results into the quadratic polynomial equation, obtaining the model regression equation coefficients, and then using variance to evaluate the effectiveness of the response surface model.

9. A method for preparing a defoaming agent for resource utilization of earth pressure balance shield slag, characterized in that: The steps include: Step S1, adding hydrophobic nano-silica and hydroxy silicone oil into a reaction kettle, stirring magnetically at 180° C. for 6 h, discharging after cooling, and obtaining a silicone paste; Step S2, pouring glycerol polyoxypropylene ether and composite emulsifier into the silicone paste obtained in the reaction of step S1, and mechanically stirring at 100° C. and 1000 rpm for 30 minutes; Step S3, adding a thickener and deionized water to the primary emulsion obtained in step S2, and mechanically stirring at 100° C. and 1000 rpm for 1 h to obtain a defoaming agent primary emulsion; Step S4, placing the defoaming agent primary emulsion in an emulsifier, and emulsifying at a speed of 10000 rpm for 20 minutes to obtain the defoaming agent.

10. The method for preparing a defoaming agent for resource utilization of earth pressure balance shield slag according to claim 9, characterized in that: The defoaming agent is prepared by using the optimal proportion of each component in the defoaming agent determined by the method for determining the proportion of the defoaming agent for resource utilization of earth pressure balance shield slag as described in any one of claims 1 to 8.

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