Microbial dust suppressant based on infiltration-consolidation, preparation method and dust suppression method

Abstract

The invention provides a microbial dust suppressant based on infiltration-consolidation, a preparation method and a dust suppression method. The dust suppressant specifically comprises a cementing material, mineralizing bacteria, a nutrient solution and a cementing solution. The preparation method comprises the following steps: inoculating mineralized bacteria into a nutrient solution to obtain a mineralized bacteria solution, and then adding gelling materials with different concentrations to obtain a gelling material-mineralized bacteria solution; then, a calcium source-urea mixed cementing liquid is added, a gelling-microbial dust suppression material is obtained, and performance improvement of the microbial dust suppressant based on infiltration-consolidation is achieved through the coupling effect of the process of inducing calcium carbonate precipitation through microorganisms and the hydration reaction of the gelling material. According to the gelling-microorganism dust suppression material disclosed by the invention, not only can the infiltration process be remarkably enhanced by utilizing the gelling effect of the gelling material to play a role in regulating and controlling the infiltration performance, but also the synergistic dust suppression of the gelling material and the mineralizing bacteria can be realized by combining the biomineralization effect of the mineralizing bacteria, so that the dust consolidation effect is effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine dust prevention and dust suppression, and relates to an infiltration-consolidation-based microbial dust suppressant, a preparation method and a dust suppression method. Background Art

[0002] With the growth of global energy demand and the increasing mechanization of coal mining, coal mining is becoming increasingly large-scale, and coal dust pollution in mining areas is becoming increasingly serious. This coal dust not only reduces air quality and visibility in production areas, but also increases the risk of pneumoconiosis among coal miners. Furthermore, within engineering systems, coal dust in workplace air can adhere to precision instruments and meters, reducing their accuracy, accumulating measurement errors, and shortening their service life. From an ecological perspective, excessive coal dust can deposit on plant leaves, reducing photosynthesis and leading to the degradation of vegetation cover, impacting the temporal and spatial dimensions of ecosystems. Therefore, the development of long-lasting, highly effective, and eco-friendly green dust suppressants is imperative.

[0003] In recent years, microbial induced carbonate precipitation (MICP) technology has gradually become a research hotspot among scholars due to its green and environmentally friendly characteristics and strong adhesive properties. This technology mainly induces the production of CaCO3 outside the cell through the metabolic activities of microorganisms. Among them, the urea hydrolysis pathway has been widely studied by scholars due to its high efficiency and strong controllability. Under the action of urease from urease-producing microorganisms, urea is hydrolyzed into NH4 + and CO3 2- At the same time, the functional groups on the surface of microbial cell walls and secreted extracellular polymers (polysaccharides, proteins, phospholipids, etc.) continuously capture Ca 2+ , and the generated CO3 2- Mineralization occurs, forming cemented CaCO3 crystals. Because the CaCO3 produced has strong adhesive properties, it has been widely used in soil consolidation, cultural relic restoration, concrete crack repair, and heavy metal pollution remediation. This also provides theoretical guidance for the preparation and optimization of microbial dust suppressants.

[0004] However, in the application of traditional microbial dust suppressants, it was found that when the infiltration rate of microbial dust suppressants was too fast, microorganisms and mineralized products could not effectively reside on the surface of coal dust, affecting the production and distribution of CaCO3, resulting in insufficient development of the surface consolidation layer, and significantly reducing its dust suppression performance. Summary of the Invention

[0005] The present invention addresses the above-mentioned problems. The present invention intends to mediate and enhance the infiltration process by adding a cementitious material, forming a local blocking effect in the pores, forcing the mineralized bacterial liquid to penetrate into the micropores, and while effectively blocking the infiltration of the dust suppressant, realize the cementation coupling of the cementitious material and the mineralized product, improve the dust suppression effect, and achieve synergistic dust suppression between the two. Based on this, the present invention provides a microbial dust suppressant based on infiltration-consolidation, a preparation method, and a dust suppression method. The prepared cementitious-microbial dust suppression material based on infiltration-consolidation is used to solve the problems of excessive infiltration and poor consolidation effect in existing microbial dust suppressants. This cementitious-microbial dust suppression material can utilize the thickening and water-retention effects of the cementitious material itself to regulate the infiltration performance, and can also achieve synergistic dust suppression by the cementitious material and the mineralized bacteria.

[0006] To achieve the above-mentioned object, according to one aspect of the present invention, there is provided a microbial dust suppressant based on infiltration-consolidation, which specifically includes a cementitious material, mineralizing bacteria, a nutrient solution and a cementing liquid; The gelling material is one or more of gelatin, guar gum, sodium alginate and xanthan gum, and has thickening and water retention properties.

[0007] Preferably, the mineralizing bacteria are selected from a urease-producing complex bacterial group enriched in a non-sterile environment using WAS as the bacterial source, and microbial community analysis shows that the group includes Sporosarcina, Carnobacterium and Bacillus, and the bacterial concentration is 1×10 8 ~1×10 10 CFU / mL, OD value is 0.8~1.0.

[0008] Preferably, the nutrient solution comprises, by mass concentration, 20-30 g / L of yeast extract or peptone, 5-10 g / L of NH4Cl, 10-15 g / L of NaCl, and 10-20 g / L of urea.

[0009] Preferably, the binder fluid comprises a soluble calcium salt and urea. Further preferably, the soluble calcium salt is one or more of calcium formate, calcium chloride, calcium lactate, and calcium acetate; preferably, the molar concentration of the soluble calcium salt is 0.5 to 1.0 mol / L; preferably, the molar concentration ratio of the soluble calcium salt to urea is 1:1.

[0010] More preferably, the ratio of the volume of the mineralizing bacteria, cementing material, and nutrient solution to the volume of the cementing solution is 1:1, and the inoculation rate of the mineralizing bacteria relative to the nutrient solution is 1%. On this basis, the ratio of the mass of the cementing material to the sum of the volumes of the mineralizing bacteria and the nutrient solution is 0.0005~0.005g / mL.

[0011] Most preferably, the ratio of the mass of the gelling material to the volume sum of the mineralizing bacteria and the nutrient solution is 0.001 g / mL.

[0012] According to another aspect of the present invention, a method for preparing a microbial dust suppressant based on infiltration-consolidation is provided, comprising the following steps: Step S1, using sodium hydroxide to adjust the pH of the nutrient solution to 10, and then sterilizing; inoculating the activated mineralized bacteria into the sterilized nutrient solution at an inoculation rate of 1%, and culturing in an incubator to obtain a mineralized bacterial solution; Step S2, sterilizing the gelling material to obtain a sterile gelling material; adding the mineralized bacterial solution to the sterile gelling material, sealing with a sealing film, and culturing in an incubator to obtain a gelling material-mineralized bacterial solution; In step S3, the cementing liquid is sterilized to obtain a sterile cementing liquid, and the cementing material-mineralized bacterial liquid and the cementing liquid in step S2 are packaged separately and then combined to obtain the microbial dust suppressant based on infiltration-consolidation.

[0013] Preferably, the sterilization method described in step S1 and step S2 is to use a vertical high-pressure sterilizer for sterilization at 121°C for 20 minutes; the culturing method described in step S1 is to use a constant temperature shaking incubator at 150 rpm and 30°C for 48 hours; and the culturing method described in step S2 is to use a constant temperature shaking incubator at 150 rpm and 25°C for 24 hours.

[0014] In the present invention, a sterilized 0.22 μm filter is used to sterilize the cementing fluid.

[0015] According to another aspect of the present invention, a dust suppression method based on an infiltration-consolidation microbial dust suppressant is provided, comprising the following steps: Step S1: Take a certain amount of gelling material - mineralized bacterial liquid and spray it evenly on the surface of the coal dust; Step S2: 10 minutes after the initial spraying, the coal dust surface has completed the initial consolidation, and the cementing liquid is evenly sprayed onto the coal dust treated with the cementitious material-mineralized bacteria liquid to achieve consolidation and strengthening of the coal dust surface.

[0016] The microbial dust suppressant based on infiltration and consolidation of the present invention mainly utilizes the thickening properties of the cementitious material to slow down the infiltration rate of the microbial dust suppressant, prolong its residence time, promote further deep penetration of the dust suppressant in micropores, ensure sufficient cementation time, and improve consolidation performance; secondly, the water retention properties of the cementitious material are utilized to improve the anti-evaporation property of the microbial dust suppressant based on infiltration and consolidation, maintain the adhesion between dust particles, and thus improve the overall dust suppression effect.

[0017] In terms of reaction mechanism, by adding urea reagent, that is, adding the decomposition substrate of urease in urease-producing bacteria in the liquid environment, NH4 can be decomposed and produced. + and CO3 2- The addition of soluble calcium salts can provide Ca for the precipitation of carbonates. 2+, generating CaCO3 with a gelling effect. The infiltration-consolidation-based microbial dust suppressant provided by the present invention addresses the problems of excessively rapid infiltration and poor consolidation in existing microbial dust suppressants. This gelling-microbial dust suppression material utilizes the thickening and water-retention properties of the gelling material itself to regulate infiltration performance, while also achieving synergistic dust suppression between the gelling material and mineralizing bacteria. It combines environmental friendliness with engineering economics, meeting the requirements for the development of green and sustainable dust control technologies.

[0018] Compared with the prior art, the present invention has the following advantages: (1) The present invention introduces a gelling material that is non-toxic to the application environment and microorganisms into the infiltration-consolidation microbial dust suppressant, effectively blocking the rapid infiltration of the microbial dust suppressant, prolonging its effective retention time, promoting the migration of microorganisms and gelling components to the deep pores, and improving the coal dust consolidation strength; (2) Based on the urease catalytic properties of urease-producing bacteria, the CO3 produced 2- During use, the Ca in the mineralization liquid 2+ Combined to form CaCO3, the directional growth of crystal form is achieved through microbial metabolic regulation, which reduces the porosity of the consolidated layer, ensures the development time of the consolidated layer, and improves the retention rate of consolidated strength; (3) Using bacterial mineralization to solidify coal dust has no secondary pollution, low life cycle cost, and better dust suppression effect. It has good application prospects in open-pit coal mines and is worthy of large-scale promotion. (4) Compared with chemical dust suppressants and common biological dust suppressants, the microbial dust suppressant based on infiltration-consolidation of the present invention has the characteristics of convenient construction and green and pollution-free. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 The wind erosion resistance of pulverized coal at different cementitious material concentrations; Figure 2 The anti-rain erosion performance of coal powder at different cementitious material concentrations; Figure 3 Figure 2 is the variation of bacterial solution and cementing solution infiltration rate over time under different cementitious material contents, where a is the variation of bacterial solution infiltration rate over time, b and c are the variation of cementing solution infiltration rate over time; Figure 4 The microscopic morphologies of the upper, middle and lower parts of each coal dust column sample with different cementitious material contents. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, the embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but such modifications and replacements should all be included within the scope of protection of the present invention.

[0021] In a preferred embodiment, the gelling material is selected from one or more of gelatin, guar gum, sodium alginate, xanthan gum, etc.; preferably, environmentally friendly and highly adhesive xanthan gum (XG) is selected as the gelling material in the embodiment; more preferably, xanthan gum (XG) with different concentration gradients is selected.

[0022] Typically, but not limiting, the different concentration gradients of xanthan gum set during the material preparation process are 0.0005, 0.001, 0.003, and 0.005 g / mL, based on mass concentration.

[0023] Due to the needs of engineering application scope, other polymer binders can be selected to further improve the comprehensive performance of dust suppressants.

[0024] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0025] Example 1: A microbial dust suppressant based on infiltration-consolidation, preparation method and dust suppression method The preparation of microbial dust suppressant based on infiltration-consolidation is as follows: Step S1: Use granular sodium hydroxide to adjust the nutrient solution to pH = 10, place it in a vertical autoclave at 121°C, and sterilize it for 20 minutes. Use a pipette to transfer the activated mineralized bacterial community (the urease-producing complex bacterial community enriched in a non-sterile environment using WAS as the bacterial source, mainly composed of Sporosarcina, Carnobacterium, and Bacillus, with an OD value of 0.8-1.0 and a bacterial concentration of 1×10 8 ~1×10 10 CFU / mL) were inoculated into the sterilized nutrient solution with an inoculation rate of 1%, and cultured in a constant temperature shaking incubator for 48 h at 150 rpm and 30°C to obtain the mineralized bacterial solution.

[0026] In step S2, different masses of gelling material (0.01 g, 0.02 g, 0.06 g, and 0.1 g) were weighed and placed in conical flasks. The mixture was sterilized in an autoclave at 121°C for 20 min to obtain sterile gelling material. 20 mL of the mineralized bacterial solution was added to each conical flask using a pipette. The flasks were sealed with parafilm and incubated in a constant temperature shaking incubator at 25°C and 150 rpm for 24 h to obtain gelling material-mineralized bacterial solution solutions of varying concentrations.

[0027] In step S3, the cementing liquid is sterilized using a sterilized 0.22 µm filter to obtain a sterile cementing liquid, and the sterile cementing liquid is added to the cementing material-mineralized bacterial liquid of different concentrations prepared in step S2 to obtain infiltration-consolidation microbial dust suppressants of different concentrations.

[0028] Specifically, the steps in this example are as follows: 10 g / L urea, 10 g / L sodium chloride, 5 g / L ammonium chloride, and 20 g / L yeast extract were diluted to 100 mL and poured into a 100 mL conical flask. A small amount of sodium hydroxide pellets was added, and the pH was adjusted to 10 using a pH meter. The flask was then sterilized in a 121°C vertical autoclave for 20 minutes. A 1% concentration of mineralized bacteria relative to the nutrient solution was inoculated into each sterilized nutrient solution and incubated in a constant temperature shaking incubator at 150 rpm and 30°C for 48 hours to obtain a microbial culture solution. Different amounts of xanthan gum were added to achieve a xanthan gum (XG) to culture solution mass-to-volume ratio of 0.0005, 0.001, 0.003, and 0.005 g / mL, respectively, for later use. 20 g of coal dust (40-80 mesh) was evenly placed in a plastic tray, and then 20 mL of bacterial solution containing xanthan gum (XG) (0.0005, 0.001, 0.003, 0.005 g / mL) with different mass volume ratios was sprayed onto the surface of the coal dust. After waiting for about 10 minutes, when the infiltration was basically stable, 20 mL of a cementing solution made of 0.5 M urea and calcium chloride was sprayed. Finally, the coal powder treated with the infiltration-consolidation-based microbial dust suppressant was placed at room temperature to dry naturally, and the above operation was repeated on the 3rd, 7th, and 15th days. The treated coal powder was subjected to wind erosion resistance tests at a wind speed of 10 m / s on the 3rd, 7th, 15th, and 30th days. The results are as follows: Figure 1 shown. Figure 1The wind erosion resistance of coal dust at different cementitious material concentrations was investigated. The results showed that the coal dust treated with xanthan gum in combination with mineralized bacteria solution and cementing solution showed the best wind resistance, and the addition of xanthan gum improved the cementing properties of the particle structure. At any time period, the coal dust treated with a concentration of 0.001 g / mL XG in combination with mineralized bacteria solution and cementing solution showed the best consolidation effect. However, as the concentration of xanthan gum increased, the wind resistance decreased. This is because when the xanthan gum content in the sample exceeds a critical value, the xanthan gum distributed in the three-dimensional space will locally aggregate, and this effect will reduce the strength of coal dust consolidation. When the consolidation time was 15 days, its wind erosion rate was as low as 0.73 g•m 2 •min -1 At 30 days, the wind erosion rate was 6.34 and 4.30 times lower than that of the treatments with 0.001 g / mL XG + cementing solution and mineralized bacteria solution + cementing solution alone, indicating that the addition of xanthan gum significantly improved the durability of the consolidated body.

[0029] At the same time, the anti-rain erosion test was carried out under a rainfall intensity of 30 mm / h. The results are as follows: Figure 2 shown. Figure 2 The rain erosion resistance of pulverized coal at different cementitious material concentrations was investigated. The results showed that the rain erosion resistance of samples treated with xanthan gum combined with a mineralized bacterial solution and a cementing solution gradually increased with increasing xanthan gum concentration, reaching an optimal value at 15 days. However, the mass loss rates of xanthan gum at concentrations of 0.001 g / mL, 0.003 g / mL, and 0.005 g / mL were similar, indicating good rain erosion resistance. This can be attributed to the stable spatial structure formed by the xanthan gum and CaCO3 precipitation. The mineralized bacterial solution combined with a cementing solution treatment was particularly effective, with rain erosion rates at 15 days being 2.16, 2.89, 2.76, and 2.88 times those of the xanthan gum combined with a mineralized bacterial solution and a cementing solution treatment, respectively. This was primarily due to the failure of the sample treated with MICP, with the majority of the failure interface located within the CaCO3. The xanthan gum network provides an additional cementing effect, preventing CaCO3 breakage and improving erosion resistance. At 30 days, the rain erosion rate of coal dust treated with 0.005 g / mL XG, mineralizing bacteria solution, and cementing solution was much lower than that of dust suppressant alone, demonstrating excellent rain resistance and durability.

[0030] Example 2: A microbial dust suppressant based on infiltration-consolidation, preparation method and dust suppression method The preparation method of the microbial dust suppressant based on infiltration-consolidation is the same as that in Example 1.

[0031] A solution of 10 g / L urea, 10 g / L sodium chloride, 5 g / L ammonium chloride, and 20 g / L yeast extract was diluted to 100 mL and poured into a 100 mL conical flask. A small amount of sodium hydroxide pellets was added, and the pH was adjusted to 10 using a pH meter. The solution was then sterilized in a vertical autoclave at 121°C for 20 min. The sterilized nutrient solution was inoculated with 1% of the mineralizing bacteria relative to the nutrient solution and incubated in a constant temperature shaking incubator at 150 rpm and 30°C for 48 h to obtain a microbial culture solution. Different amounts of xanthan gum (XG) were added to achieve a mass-to-volume ratio of xanthan gum (XG) to the culture solution of 0.0005, 0.001, 0.003, and 0.005 g / mL, respectively, for later use. 20 g of coal dust (40-80 mesh) was evenly placed in a plastic tray. Subsequently, 20 mL of a bacterial solution containing different mass-to-volume ratios of xanthan gum (XG) (0.0005, 0.001, 0.003, and 0.005 g / mL) was sprayed onto the surface of the coal dust. After approximately 10 minutes, when infiltration had stabilized, 20 mL of a cementing solution composed of 0.5 M urea and calcium chloride was sprayed. During this period, the infiltration rate was measured. Specifically, the infiltration characteristics (infiltration level and depth) after spraying the bacterial solution and cementing solution were recorded. The recording intervals were: 30 s, 60 s, 90 s, 120 s, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, and 10 min. Subsequent readings were taken every 2 minutes until the entire solution had infiltrated and no liquid accumulated in the upper layer. This was considered the end of infiltration or seepage, and the stop time was recorded. The average infiltration rate in the first 3 minutes of infiltration was defined as the initial infiltration rate, and the infiltration rate when the infiltration amount per unit time tended to be stable was defined as the stable infiltration rate ( , where f(t) is the infiltration rate, mm / min; ∆V is the amount of liquid reduced by infiltration over a certain period of time, cm 3 ; S is the cross-sectional area of ​​the cylindrical sample, cm 2 ;∆t is the time period, min; θ is the average temperature of the liquid during the experiment, 27°C. ) Thus, we can obtain Figure 3 The variation of the infiltration rate of bacterial solution and cementing solution with time under different xanthan gum contents, among which Figure 3 a is the graph showing the variation of bacterial solution infiltration rate over time under different xanthan gum contents. Due to the difference in values ​​at different concentrations, the variation of cementing solution infiltration rate over time under different xanthan gum contents is divided into two graphs, b and c. Figure 3 b is the change of the infiltration rate of the cementing fluid with time at different xanthan gum contents (0.0005 g / mL, 0.001 g / mL), Figure 3c is a graph showing the change of the infiltration rate of the cementing fluid with different xanthan gum contents (0.003 g / mL, 0.005 g / mL) over time.

[0032] The results showed that the addition of xanthan gum significantly improved the problem of high infiltration rate caused by the large coal dust matrix force-hydraulic gradient in the early stage of infiltration. Figure 3 In a, at a xanthan gum concentration of 0.0005 g / mL, the initial infiltration rate was 0.87 mm•min in the initial stage after spraying. -1 , which decreased by 73.71% compared with that without xanthan gum. As the xanthan gum concentration increased to 0.003 g / mL, the initial infiltration rate decreased to 0.044 mm•min -1 When the concentration increased to 0.005 g / mL, the initial infiltration rate was approximately zero. It is speculated that the addition of xanthan gum increased the diffusivity and viscosity of the medium, causing pore blockage. Because the binder solution was sprayed later than the bacterial solution, the CaCO₃ produced later formed clusters under the adhesion of the xanthan gum, exacerbating pore blockage. Figure 3 b shows that when the concentration is 0.0005 g / mL and 0.001 g / mL, the initial infiltration rate of the cementing fluid is 0.22 mm•min -1 、0.08 mm•min -1 .then Figure 3 In sample c, the initial rate was zero at concentrations of 0.003 g / mL and 0.005 g / mL. As the bacterial solution and cementing fluid infiltrated deeper into the coal dust, the instantaneous infiltration rate gradually decreased over time. In the later stages of infiltration, the infiltration rates of the bacterial solution and cementing fluid into the coal dust column remained almost constant, reaching a steady state. Analysis of the infiltration rate indicates that higher xanthan gum concentrations, such as 0.003 g / mL and 0.005 g / mL, can cause pore clogging, leading to localized cementation around the injection source (in the upper portion of the coal sample), and thus compromising the consolidation effect. This suggests that a xanthan gum concentration of 0.0005 g / mL to 0.001 g / mL is the optimal range for improving sample consolidation.

[0033] Example 3: A microbial dust suppressant based on infiltration-consolidation, preparation method and dust suppression method The preparation method of the microbial dust suppressant based on infiltration-consolidation is the same as that in Example 1.

[0034] A solution of 10 g / L urea, 10 g / L sodium chloride, 5 g / L ammonium chloride, and 20 g / L yeast extract was diluted to 100 mL and poured into a 100 mL conical flask. A small amount of sodium hydroxide pellets was added, and the pH was adjusted to 10 using a pH meter. The solution was then sterilized in a vertical autoclave at 121°C for 20 min. The sterilized nutrient solution was inoculated with 1% of the mineralizing bacteria relative to the nutrient solution and incubated in a constant temperature shaking incubator at 150 rpm and 30°C for 48 h to obtain a microbial culture solution. Different amounts of xanthan gum (XG) were added to achieve a mass-to-volume ratio of xanthan gum (XG) to the culture solution of 0.0005, 0.001, 0.003, and 0.005 g / mL, respectively, for later use. 20 g of coal dust (40-80 mesh) was evenly placed in a plastic tray. Then, 20 mL of bacterial solution containing different mass-to-volume ratios of xanthan gum (XG) (0.0005, 0.001, 0.003, and 0.005 g / mL) was sprayed onto the coal dust surface. After waiting for about 10 minutes, when the infiltration was basically stable, 20 mL of a cementing solution made of 0.5 M urea and calcium chloride was sprayed. On the 30th day of consolidation, scanning electron microscopy analysis of the coal dust consolidation was performed, as shown in Figure 2. Figure 4 Microscopic morphologies of the upper, middle, and lower portions of coal dust columns at different cementitious material contents. "A" represents a sample treated with a microbial dust suppressant at a xanthan gum concentration of 0.0005 g / mL. The remaining three groups, "B," "C," and "D," correspond to concentration gradients of 0.001 g / mL, 0.003 g / mL, and 0.005 g / mL, respectively. "T," "M," and "B" represent samples taken from the upper, middle, and lower layers of the sample, respectively.

[0035] The results showed that all coal dust samples were well cemented together under treatments with varying concentrations of xanthan gum combined with a mineralizing bacterial solution and a cementing solution. Bridge structures connecting adjacent coal dust particles were also observed. This was primarily due to the thickening effect of the xanthan gum, which formed a gel that filled the intergranular spaces and provided additional nucleation sites for the growth of CaCO₃, thereby forming interparticle bridges and enhancing the effective cementation of the samples. In addition to the bridge structures, some coal dust particles were encapsulated by xanthan gum and CaCO₃ crystals, forming a thin film. As the xanthan gum concentration increased, the upper layer became increasingly dense, and the particle-xanthan gum-particle bridge structure between the coal dust particles and the xanthan gum became more pronounced. However, when the concentration increased from 0.001 g / mL to 0.005 g / mL, macropores appeared in some microscopic samples of the upper layer. This is likely due to the high xanthan gum concentration, which formed a gel layer on the coal dust surface and filled the pores between the particles, leading to stagnant cementation and localized accumulation of CaCO₃. The middle and lower layers have larger cavities, which is caused by the large viscosity coefficient of the liquid, the bacterial liquid and the cementing liquid not reaching the bottom, and no or less mineralization products being produced.

Claims

1. A microbial dust suppressant based on infiltration-consolidation, characterized in that: The invention comprises a gelling material, mineralizing bacteria, nutrient solution and cementing liquid; the gelling material is one or more of gelatin, guar gum, sodium alginate and xanthan gum.

2. The microbial dust suppressant based on infiltration-consolidation according to claim 1, characterized in that: The mineralizing bacteria are selected from a urease-producing complex bacterial group enriched in a non-sterile environment using WAS as the bacterial source, including Sporosarcina, Carnobacterium and Bacillus. The concentration of the bacteria is 1×10 8 ~1×10 10 CFU / mL, OD value is 0.8~1.

0.

3. The microbial dust suppressant based on infiltration-consolidation according to claim 1, characterized in that: Calculated by mass concentration, the nutrient solution comprises 20-30 g / L of yeast extract or peptone, 5-10 g / L of NH4Cl, 10-15 g / L of NaCl, and 10-20 g / L of urea.

4. The microbial dust suppressant based on infiltration-consolidation according to claim 1, characterized in that: The binder fluid includes a soluble calcium salt and urea; preferably, the soluble calcium salt is one or more of calcium formate, calcium chloride, calcium lactate, and calcium acetate; preferably, the molar concentration of the soluble calcium salt is 0.5~1.0 mol / L.

5. The microbial dust suppressant based on infiltration-consolidation according to claim 1, characterized in that: The molar concentration ratio of the soluble calcium salt to urea is 1:

1.

6. The microbial dust suppressant based on infiltration-consolidation according to claim 1, characterized in that: The volume ratio of the mineralizing bacteria, gelling material, and nutrient solution to the volume of the cementing solution is 1:1, the inoculation rate of the mineralizing bacteria relative to the nutrient solution is 1%, and the ratio of the mass of the gelling material to the sum of the volumes of the mineralizing bacteria and the nutrient solution is 0.0005~0.005g / mL.

7. The microbial dust suppressant based on infiltration-consolidation according to claim 6, characterized in that: The ratio of the mass of the cementitious material to the volume sum of the mineralizing bacteria and the nutrient solution was 0.001 g / mL.

8. The method for preparing a microbial dust suppressant based on infiltration-consolidation according to any one of claims 1 to 7, characterized in that: Here are the steps: Step S1, adjusting the pH of the nutrient solution to 10 using sodium hydroxide, and then sterilizing; inoculating the activated mineralized bacteria into the sterilized nutrient solution at an inoculation rate of 1%, and culturing in an incubator to obtain a mineralized bacterial solution; Step S2, sterilizing the gelling material to obtain a sterile gelling material; adding the mineralized bacterial solution to the sterile gelling material, sealing with a sealing film, and culturing in an incubator to obtain a gelling material-mineralized bacterial solution; In step S3, the cementing liquid is sterilized to obtain a sterile cementing liquid, and the cementing material-mineralized bacterial liquid and the cementing liquid in step S2 are packaged separately and then combined to obtain the microbial dust suppressant based on infiltration-consolidation.

9. The method for preparing a microbial dust suppressant based on infiltration-consolidation according to claim 8, characterized in that: The sterilization methods described in step S1 and step S2 are both to use a vertical high-pressure sterilizer for sterilization at 121°C for 20 minutes; the culturing method described in step S1 is to use a constant temperature shaking incubator at 150 rpm and 30°C for 48 hours; the culturing method described in step S2 is to use a constant temperature shaking incubator at 150 rpm and 25°C for 24 hours.

10. A dust suppression method based on an infiltration-consolidation microbial dust suppressant according to any one of claims 1 to 7, characterized in that: Here are the steps: Step S1: Take a certain amount of gelling material - mineralized bacterial liquid and spray it evenly on the surface of the coal dust; Step S2: 10 minutes after the initial spraying, the coal dust surface has completed the initial consolidation, and the cementing liquid is evenly sprayed onto the coal dust treated with the cementitious material-mineralized bacteria liquid to achieve consolidation and strengthening of the coal dust surface.

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