Medium-expansion high-viscosity foam dust-reducing agent and preparation method thereof

Abstract

Belonging to the technical field of dust suppressants, the invention discloses a novel medium multiple high viscosity foam dust suppression agent, which is mainly used for coal mine underground dust suppression, and comprises the following raw materials by mass fraction: 7%-15% of an organosilicon surfactant, 0.5%-4% of a hydrocarbon surfactant, 0.2%-1% of a foam stabilizer, 1.7%-3% of low carbon alcohol, 0.5-2% of urea, 1%-3% of a wetting agent, and 80%-89.1% of water. The preparation method comprises the following steps: adding the surfactant, the solubilizer, the wetting agent, the low-carbon alcohol, the urea and the foam stabilizer into water one by one in an environment of 20-40 DEG C, uniformly stirring to form a suspension, and controlling the pH value of the foam liquid to be 6-8, thereby obtaining the foam dust-settling agent. The product is good in stability, strong in wettability, safe to transport and simple in preparation process, and overcomes the defects of high water consumption and poor dust falling effect of the existing spray dust falling technology.

Description

TECHNICAL FIELD

[0001] The present application relates to coal mine dust fall technology, in particular to a middle-multiple foam dust fall agent. BACKGROUND

[0002] Coal as a non-renewable resource occupies a dominant position in the energy structure. In the process of coal mining, a large amount of coal dust is produced, which not only harms the health of workers, but also may cause dust explosion, threatening the life and property safety of workers. In the high-concentration dust environment, the visibility is greatly reduced, which causes the workers' vision to be blurred and increases the probability of accidents. In this context, improving the dust fall efficiency of dust fall technology helps to reduce the dust concentration produced in the process of coal mine tunneling or mining, and is conducive to improving the working environment of mine workers. The water mist dust fall used in coal mines has the disadvantages of large water consumption and low dust fall rate, so we invented a middle-multiple foam dust fall agent.

[0003] In the 1980s, domestic and foreign scholars began to study nano-silicon dioxide. In the 21st century, scholars began to deeply study the interaction mechanism between nano-silicon dioxide and different types of foam. In the field of polyurethane foam, it was found that nano-silicon dioxide not only improves the stability of foam, but also improves the mechanical properties and thermal stability of foam.

[0004] There are a large number of hydroxyl groups on the surface of nano-silicon dioxide. In the solution, these hydroxyl groups can form hydrogen bonds between each other, so that nano-silicon dioxide particles are connected with each other or interact with other molecules in the solution, thereby increasing the viscosity of the liquid. Higher viscosity will reduce the density of surfactants arranged at the interface, and to some extent, increase the interfacial tension of the system, but the influence is not great. With the increase of the viscosity of the system, the liquid film discharge speed under the same conditions is reduced, and the gas exchange speed between bubbles is also reduced, and the stability of the foam is good. Zhang Chunpeng found that nano-silicon dioxide can increase the thickness of the foam wall and enhance the stability of the foam. Nano-silicon dioxide and xanthan gum jointly act through the organic combination of "interfacial particle stabilization (Pickering effect)" and "bulk thickening stabilization", and further form an interpenetrating reinforced composite network structure, which delays the liquid film discharge from the interface to the bulk phase, inhibits gas diffusion, and hinders bubble coalescence, thereby significantly enhancing the stability and life of the foam. This synergistic strategy is a classic and effective method for constructing ultra-stable foam systems.

[0005] The situation becomes complicated when lower alcohols and surfactants coexist in a system. In some cases, lower alcohols may interact with surfactants, altering the surfactant's critical micelle concentration (CMC). If the addition of a lower alcohol lowers the surfactant's CMC, micelles will form at lower surfactant concentrations. This can affect foam stability, as micelle formation and properties are closely related to foam generation and stabilization mechanisms. For example, in some detergent formulations, mixing small amounts of ethanol with anionic surfactants may alter the detergent's foaming properties, resulting in finer foams or changes in foam stability.

[0006] A search of relevant patents revealed that several inventors have conducted research on foam dust suppressants and their preparation methods. For example, Chinese patent CN 118652665 A, published under authorization number CN 118652665, proposes a foam dust suppressant for mining, its preparation method, and its application method. However, the foam height measured in the examples of this patent is less than 10 cm, insufficient to combat coal dust generated at the mine working face. Another example is Chinese patent CN 103694960 A, which proposes a foam dust suppressant and its preparation method. In example 5, this patent conducted a dust suppression experiment on the foam, finding that it achieved a 97.2% dust suppression rate for total dust, but only 86.1% for respirable dust, indicating insufficient efficiency in suppressing respirable dust. Yet another example is Chinese patent CN103694960A, which proposes a foam dust suppressant and its preparation method. However, this foam dust suppressant requires an environment of 50℃~60℃ to be successfully prepared, which is difficult to achieve in practical engineering applications in underground coal mines. As a new dust suppression technology in coal mines, foam dust suppression requires not only that the preparation process and viscosity meet the requirements, but also that its foaming ratio and wettability are crucial. If the foaming ratio is low or the wettability is low, the foam will spread slowly or not at all on the surface of the dust particles, causing the dust particles to remain suspended in the air for a long time and making it difficult for them to be captured by the liquid, thus reducing the dust suppression efficiency. Summary of the Invention

[0007] To overcome the above shortcomings, this invention provides a medium-expansion, high-viscosity dust-suppressing foam for use in coal mine dust suppression; the aim is to improve the foaming ratio, viscosity, and wettability of the dust-suppressing foam. Currently, most foam formulations contain PFOS components. The United Nations Environment Programme's environmental pollution risk assessment of PFOS has raised concerns, and currently widely used foam extinguishing agents pose potential environmental hazards. Therefore, the fire protection field urgently needs to develop new environmentally friendly foaming agents and foam stabilizers to replace traditional AFFF products. The foam components provided by this invention are hydrocarbon surfactants, nano-silica, and fluorine-free materials such as xanthan gum.

[0008] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0009] A medium-expansion, high-viscosity foam dust suppressant comprises the following raw materials in the indicated mass fractions: 7%–15% organosilicon surfactant, 0.5%–4% hydrocarbon surfactant, 0.2%–1% foam stabilizer, 1.7%–3% low-carbon alcohol, 0.5%–2% urea, 1%–3% wetting agent, and the remainder being water. The foam formulation of this application eliminates the bioaccumulation effect and environmentally damaging impact of existing fluorocarbon foams.

[0010] Furthermore, the nano-silica used has an average particle size of 15-20 nm and a SiO2 content of 99.99%. Nano-silica can interact with other components in the foam liquid film (such as surfactants). It can enhance the elasticity and toughness of the liquid film. When the foam is subjected to external mechanical disturbances (such as stirring or shaking), the liquid film can withstand greater deformation without breaking. This is equivalent to adding a "reinforcing agent" to the liquid film, making it more robust.

[0011] Furthermore, the foam stabilizers used are xanthan gum and hydrophilic nano-silica. Xanthan gum is a high-molecular-weight polysaccharide with a long-chain structure that can form a three-dimensional network structure in solution. Due to their nano-size and high specific surface area, nano-silica particles can be adsorbed onto the molecular chains of xanthan gum or dispersed within its network structure. When they coexist in the foam system, this composite structure enhances the stability of the foam liquid film. For example, in the foam liquid film, the xanthan gum network structure acts like a "skeleton," while the nano-silica particles act like "filler." Their interaction makes the liquid film more robust, able to withstand external factors (such as airflow and vibration) without easily breaking.

[0012] Furthermore, low-carbon alcohols were added to the foam compounding scheme. These alcohols can also reduce the surface elasticity of the foam film. The surface elasticity of the foam film is a crucial factor in foam stability, determining its resilience to external disturbances (such as vibration and airflow). The presence of low-carbon alcohols weakens the intermolecular forces on the foam film surface, reducing surface elasticity. When the foam thins locally due to external factors, the reduced surface elasticity allows liquid to more easily replenish from surrounding areas, making the foam less prone to rupture and thus enhancing its stability. Low-carbon alcohols can also affect the drainage process of the foam. Under normal circumstances, liquid in the foam gradually drains from the foam film due to gravity, causing the foam film to thin and eventually rupture. The addition of low-carbon alcohols can alter the permeability and drainage rate of the foam liquid film. It may reduce the permeability of the foam liquid film, preventing the rapid drainage of liquid from the foam interior. For example, some experiments have shown that foam with the addition of low-carbon alcohols exhibits a significantly prolonged drainage time.

[0013] A method for preparing a medium-expansion, high-viscosity foam dust suppressant includes the following steps:

[0014] The first step is to use an electronic balance to weigh the foam stabilizer xanthan gum and nano silica in a ratio of 2:1. First, add xanthan gum to water at 20℃~40℃ and stir until fully dissolved. Then, add nano silica to the solution containing xanthan gum and stir thoroughly to disperse it in the solution.

[0015] The second step is to add the weighed low-carbon alcohol to the solution prepared in the first step and stir until fully dissolved to obtain an emulsion.

[0016] The third step is to weigh out 7% to 15% of the organosilicon surfactant and 0.5% to 7% of the hydrocarbon surfactant, add them to the emulsion prepared in the second step, and stir until fully dissolved.

[0017] Fourth step: Add the weighed wetting agent to the solution prepared in the third step, stir thoroughly until completely dissolved, and then adjust the pH value to 6-8 to obtain the dust suppressant.

[0018] Compared with the prior art, the medium-expansion ratio, high-viscosity foam dust suppressant of the present invention has the following beneficial effects:

[0019] The dust-suppressing foam prepared by this invention has an adjustable foaming ratio and a long separation time of 25%. Nano-silica particles possess high specific surface area and surface energy. When present in a foam system, they can adsorb onto the gas-liquid interface. Due to their surface activity, nano-silica can reduce the surface tension of the interface, making foam formation easier. The hydroxyl and other functional groups in xanthan gum molecules can interact with water molecules, altering the molecular arrangement of the solution at the gas-liquid interface, thereby reducing surface tension. Nano-silica can make the foam pores smaller and more uniform, while the thickening effect of xanthan gum can make the foam structure more stable; the combined effect of both contributes to improving the fineness and uniformity of the foam.

[0020] This invention incorporates low-carbon alcohols as emulsifiers into dust-suppressing foams. Low-carbon alcohol molecules possess hydrophilic hydroxyl groups and relatively hydrophobic hydrocarbon groups. When added to the foam system, the molecules automatically aggregate at the gas-liquid interface. Due to this amphiphilic structure, low-carbon alcohols can reduce the surface tension of the liquid, making foam formation easier. Low-carbon alcohols can also regulate the drainage rate of the foam liquid film. Under the influence of gravity and other factors, the liquid in the foam liquid film will drain, and as the film thins, the foam is prone to rupture. Low-carbon alcohols can slow down the drainage rate by altering properties such as the viscosity of the liquid film, thereby enhancing foam stability. Low-carbon alcohols can also affect the flowability of the foam. An appropriate low-carbon alcohol content can give the foam better flowability, facilitating operation in some industrial processes.

[0021] The medium-expansion, high-viscosity foam dust suppressant prepared by this invention has a simple preparation process, low industrial cost, and features non-toxicity, high foaming ratio, high viscosity, and good wettability. It is suitable for dust suppression and removal work in coal mines. Attached Figure Description

[0022] Figure 1 The results are from a coal dust settling experiment.

[0023] Figure 2 The contact angle of the coal sample from Tashan, Shanxi;

[0024] Figure 3 The contact angle of a coal sample from Yulin, Shaanxi. Detailed Implementation

[0025] The following specific embodiments further describe the present invention. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0026] Example 1: A medium-expansion, high-viscosity foam dust suppressant, prepared as follows:

[0027] 1. First, weigh 500g of water. Then, using an electronic balance, weigh 0.5g of foam stabilizer nano-silica and 1g of xanthan gum and add them to the water, stirring thoroughly. Next, add 20g of isobutanol and stir until completely dissolved. Then, add 100g of organosilicon surfactant Silok8141 and 50g of hydrocarbon surfactant SDS and stir thoroughly to ensure that all surfactants are dissolved. Finally, weigh 10g of urea and 20g of wetting agent alkyl glycoside and add them to the remaining solution. Finally, add 300g to make up the total solution to 1000g. This foam dust suppressant is then prepared and will be referred to as Sample 1 for subsequent testing.

[0028] 2. First, weigh 500g of water. Then, using an electronic balance, weigh 0.5g of foam stabilizer nano-silica and 1g of xanthan gum and add them to the water, stirring thoroughly. Next, add 20g of isobutanol and stir until completely dissolved. Then, add 100g of organosilicon surfactant Silok8141 and 50g of hydrocarbon surfactant AES and stir thoroughly until completely dissolved. Finally, weigh 10g of urea and 20g of wetting agent alkyl glycoside and add them to the remaining solution. Finally, add 300g to make up the total solution to 1000g. This can also prepare the foam dust suppressant of this product. Subsequent tests are referred to as Sample 2.

[0029] Example 2: The foaming ratio, foaming height, and foam half-life of a medium-expansion high-viscosity foam dust suppressant are tested as follows:

[0030] 1. The foaming ratio was tested according to section 6.18 of the national standard GB20031-2024 for foam fire extinguishing equipment. First, any type of foam was prepared as described in Example 1, and foaming was performed using a self-made foaming machine. A beaker was weighed on an electronic balance and tare; the volume of the beaker was recorded as V. Then, the foam was collected using the tare beaker, and the mass of the collected foam was recorded as m1. Next, 70 ml of foam liquid was added to the pipe of a foam scanner, and the foaming ratio was measured. The foam density ρ was obtained from the instrument test, and the foaming ratio N was calculated using Formula 1. The measured foaming ratio was consistently above 30 times.

[0031]

[0032] 2. First, two different solutions were prepared according to Example 1. The foaming height was tested using a Roche foam apparatus. The following steps were all performed at room temperature. 200 ml of solution was measured using a graduated cylinder and added to a dropping funnel. 50 ml of foam solution was added to a graduated tube. The dropping funnel was fixed directly above the graduated tube, with the outlet of the dropping funnel at the 700 mm mark on the graduated tube. The piston of the dropping funnel was controlled to allow the foam solution to drip slowly. The reading was taken when the solution in the dropping funnel was completely drained, which is the foaming height. Then, a stopwatch was immediately started to time the reading at 5 minutes and the foam stability coefficient of the foam solution was calculated. The test results are shown in Table 1.

[0033] 3. The foam half-life was tested using the instrument "Foamscan". The test steps are as follows: First, different solutions were prepared in beakers according to the method in Example 1. Then, 40 ml of foam solution was drawn into the foam column using a syringe to replace any residual liquid that might have been present during the cleaning process. The entire 40 ml of liquid was then drained. Next, 60 ml of foam solution was drawn, and the instrument software was set to inject 20 ml of liquid each time. The solution was calibrated and its conductivity was tested once. After injecting all the liquid into the foam column three times, the conductivity line was calculated. The instrument was then started to dynamically observe the foam. The software automatically calculated the foam half-life. The foam half-life data is shown in Table 1, and the foam observation graph is shown below. Figure 1 As shown.

[0034] Example 3: A medium-expansion, high-viscosity foam dust suppressant, and its settling and contact angle methods for different coal types:

[0035] 1. First, prepare different types of coal. Here, coal samples from Jinjitan in Yulin, Shaanxi Province, and Tashan in Shanxi Province were selected. All samples were ground to 80-100 mesh, dried in a drying oven at 60℃, and stored in a dry wide-mouth bottle. Prepare a 200mL solution using the method described in Example 1, and take 50mL of this solution and store it in a test tube for later testing. Using an electronic balance, take 0.2g of each of the two coal samples and evenly sprinkle them onto the surface of the prepared foam solution in the test tube. Observe the coal dust settling. When the coal dust is completely wetted and falls off the liquid surface, record the settling time. Next, calculate the coal dust settling velocity based on the ratio of coal dust weight to settling time to characterize the wetting effect of the foam solution on the coal dust. The test results are shown in Table 1, and the test graph is shown below. Figure 1 As shown. The foaming height of the dust-suppressing foam developed in patent number CN120532222A is about 50cm, while this dust-suppressing foam can reach 115mm.

[0036]

[0037] 2. First, weigh a certain amount of coal powder on an electronic balance and press it into a round cake shape with a thickness of 0.5 cm and a diameter of 2 cm using a tablet press. Next, prepare a certain amount of foam solution. Test the contact angle using a KRUSS interfacial rheometer. The test steps are as follows: Draw a small amount of foam solution using a syringe, place the syringe at the measuring point of the instrument, place the coal cake directly under the syringe, and control the device to drip a drop of solution onto the surface of the coal cake. The computer software analyzes the process from solution contacting the coal cake to wetting it, and calculates the contact angle during the wetting process. Specifically... Figure 2 , Figure 3 As shown.

[0038] Example 4: A medium-expansion, high-viscosity foam dust suppressant, the foam viscosity test method is as follows:

[0039] First, two foaming liquids were prepared according to the method in Example 1. Then, foam was generated using a foaming machine and collected in a beaker. The viscosity of the foam was tested using a viscometer, with the specific operation as follows: A No. 2 rotor was mounted on the viscometer. The beaker containing the foam was placed directly below the viscometer. The knob was rotated to submerge the rotor in the foam. The test was conducted when the foam reached above the rotor's graduation mark. The tested foam viscosities were all above 6000 mPa·s.

[0040] Example 5: A medium-expansion, high-viscosity foam dust suppressant, the dust suppression efficiency is tested as follows:

[0041] Dust suppression experiments were conducted using a self-built foam dust suppression platform, and the results were recorded using a portable dust meter. First, a blower was used to simulate an air source, evenly dispersing coal dust into a transparent chamber. This was maintained for 2 minutes. The dust meter was then used to measure the total dust and respirable dust concentrations at the near and far ends of the airflow through pre-drilled test holes. Next, foam was sprayed into the transparent chamber using a foam generator. After waiting 1 minute, the dust concentration was measured, and the dust suppression rate was calculated. Based on the test results, the dust suppression foam achieved a dust suppression rate of over 97% for both respirable dust and total dust at both the near and far ends of the airflow.

Claims

1. A downhole dust suppressant of moderate multiple high viscosity foam, characterized in that, The foam dust fall agent comprises raw materials in mass fraction: 7-15% of silicone surfactant, 0.5-4% of hydrocarbon surfactant, 0.5-2% of foam stabilizer, 2-5% of low carbon alcohol, 0.5-2% of urea, 0.5-3% of solubilizer, 1-5% of wetting agent, and the rest is water.

2. The medium multiple high viscosity foam dust suppressant of claim 1, wherein, The silicone surfactant comprises any one of Sliok8141, BYK-346 and trisiloxane surfactant.

3. The medium multiple high viscosity foam dust suppressant of claim 1, wherein, The hydrocarbon surfactant comprises any one of sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS) and sodium fatty alcohol polyoxyethylene ether sulfate (AES).

4. The medium multiple high viscosity foam dust suppressant of claim 1, wherein, The foam stabilizer comprises a mixture of xanthan gum and hydrophilic nano-silicon dioxide, the mixing ratio is 2:1, the average particle size of the nano-silicon dioxide is 15-20 nm, and the SiO2 content is 99.99%.

5. The medium multiple high- viscosity foam dust depressant according to claim 1, characterized in that, The low carbon alcohol comprises one of isobutyl alcohol, diethylene glycol butyl ether and ethylene glycol or a mixture of 2-3 kinds thereof.

6. The medium multiple high- viscosity foam dust depressant according to claim 1, characterized in that, The wetting agent comprises one of alkyl glycoside, decyl glucoside, methyl glucoside and n-octyl glucoside or a mixture of 2-3 kinds thereof.

7. The medium multiple high- viscosity foam dust depressant according to claim 1, characterized in that, The preparation method is as follows: In the first step, the foam stabilizer xanthan gum and nano-silicon dioxide are weighed by using an electronic balance, the ratio is 2:1, the xanthan gum is first added into water at 20-40 DEG C, and stirred until fully dissolved, then the nano-silicon dioxide is added into the solution containing the xanthan gum and stirred to disperse in the solution; In the second step, the weighed low carbon alcohol is added into the solution prepared in the first step, and stirred until fully dissolved to obtain an emulsion; In the third step, the weighed silicone surfactant 7-15%, hydrocarbon surfactant 0.5-4% is added into the emulsion prepared in the second step, and stirred until fully dissolved; In the fourth step, the weighed wetting agent and urea are added into the solution prepared in the third step, and fully stirred until completely dissolved, then the PH value is adjusted to 6-8, and the product dust fall agent is obtained.

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