Coal-based microbial grouting material, microbial closed carrier and grouting method of mine

Abstract

The invention provides a coal-based microbial grouting material, a microbial closed carrier and a grouting method of a mine. The coal-based microbial grouting material comprises a microbial closed carrier and a coal-based raw material, the microbial closed carrier comprises an internal structure and an external structure, and the external structure wraps the internal structure; the component of the outer layer structure comprises second cement; and the internal structure comprises the following components: water, microorganisms and microorganism nutrition auxiliary materials. The grouting material can solve the problem of lack of grouting materials capable of filling goaf and purifying mine water in the prior art, and is suitable for the technical field of coal mining and mine water treatment.

Description

Technical Field

[0001] The invention relates to the technical field of mine water treatment, and in particular to a coal-based microbial grouting material, a microbial closed carrier and a mine grouting method. Background Art

[0002] In the long-term coal resource mining process, the ground in the mine goaf often sinks to varying degrees, which may not only cause ground collapse, but also cause the coal dust trapped in the goaf to spontaneously combust or explode. In order to deal with these potential risks, grouting filling technology is usually used to reinforce the goaf to maintain ground stability. The research and development of grouting materials needs to focus on the rheological properties, coagulation characteristics and relationship with pipeline transportation resistance of the materials. In addition, the environment of the mine goaf is relatively complex, so the selection and development of grouting materials is more stringent.

[0003] At the same time, the treatment and utilization of mine water is also an important issue in the coal industry. According to statistics, on average, about two tons of mine water are produced for every ton of coal mined. If these mine waters are effectively treated and utilized, they can not only alleviate the problem of water shortage in local areas, but also reduce environmental pollution in mining areas. However, mine water contains complex water quality such as suspended matter, high mineralization and special components, which requires the use of a variety of treatment technologies to purify it, such as super magnetic separation, high-density sedimentation, reverse osmosis, etc. These technologies often have complex steps, require a large amount of infrastructure investment, and have high operating costs.

[0004] In addition, the purification of mine water also needs to take into account the particularity of the underground space, including the defective areas of the goaf and the variability of the mining face, all of which may affect the purification effect of mine water. The existing technology has not yet been able to provide an economical and efficient grouting method to simultaneously achieve effective filling of the goaf and purification of mine water. Therefore, developing a new grouting filling technology to solve these problems in the existing technology has become a technical bottleneck that needs to be broken through in the coal industry. Summary of the invention

[0005] The main purpose of the present invention is to provide a coal-based microbial grouting material, a microbial closed carrier and a mine grouting method to solve the problem in the prior art of lack of grouting materials that can take into account both goaf filling and mine water purification.

[0006] In order to achieve the above-mentioned purpose, according to the first aspect of the present invention, a coal-based microbial grouting material is provided, which includes a microbial closed carrier and a coal-based raw material; the microbial closed carrier includes an internal structure and an outer layer structure, and the outer layer structure wraps the internal structure; the components of the outer layer structure include a second cement; the components of the internal structure include water, microorganisms and microbial nutrient additives.

[0007] Furthermore, the coal-based raw materials include one or more of coal gangue, fly ash or slag; preferably, the coal-based microbial grouting material also includes auxiliary materials; preferably, the auxiliary materials include first cement, water glass and water.

[0008] Furthermore, the mass ratio of coal gangue, fly ash, slag and the first cement in the coal-based microbial grouting material is 1-10:1-10:5-20:1-5; preferably, the ratio of the mass of water in the coal-based microbial grouting material to the sum of the mass of coal gangue, fly ash, slag and the first cement is 0.2-0.6:1; preferably, the mass proportion of water glass in the coal-based microbial grouting material is 1-5%; preferably, the mass proportion of microbial closed carriers in the coal-based microbial grouting material is 5-20%; preferably, the first cement includes one or more of silicate cement, aluminate cement or ferroaluminate cement.

[0009] Furthermore, the microorganisms include any one or more of the following: Arthrobacter, Bacillus, Acinetobacter, Pseudomonas or Desulfovibrio; preferably, the mass ratio of each microorganism is equal; preferably, the concentration of the microorganism in the internal structure is 1.0×10 6 ~1.0×10 8 cells / mL; preferably, the microbial nutrient supplement includes peptone and / or beef extract; preferably, the second cement includes one or more of sulphoaluminate cement, silicate cement or phosphate cement.

[0010] Furthermore, the mass ratio of each component in the microbial closed carrier is the second cement: water: microorganism: microbial nutrient auxiliary material = 90-120: 40-55: 0.5-2: 2-5; preferably, the components of the microbial closed carrier include sulfoaluminate cement, water, microorganisms, peptone and beef extract; preferably, the mass ratio of each component in the microbial closed carrier is sulfoaluminate cement: water: microorganism: peptone: beef extract = 90-120: 40-55: 0.5-2: 1-3: 1-2.

[0011] In order to achieve the above-mentioned purpose, according to the second aspect of the present invention, a microbial closed carrier is provided, which includes an internal structure and an outer structure, and the outer structure wraps the inner structure; the components of the outer structure include a second cement; the components of the internal structure include water, microorganisms and microbial nutrient supplements.

[0012] Furthermore, the microorganisms include any one or more of the following: Arthrobacter, Bacillus, Acinetobacter, Pseudomonas or Desulfovibrio; preferably, the mass ratio of each microorganism is equal; preferably, the concentration of the microorganism in the internal structure is 1.0×10 6 ~1.0×10 8cells / mL; preferably, the microbial nutrient supplement includes peptone and / or beef extract; preferably, the second cement includes one or more of sulphoaluminate cement, silicate cement or phosphate cement.

[0013] Furthermore, the mass ratio of the components in the microbial closed carrier is: second cement: water: microorganism: microbial nutrient supplement = 90-120: 40-55: 0.5-2: 2-5; preferably, the microbial closed carrier includes sulfoaluminate cement, water, microorganisms, peptone and beef extract; preferably, the mass ratio of the components in the microbial closed carrier is sulfoaluminate cement: water: microorganism: peptone: beef extract = 90-120: 40-55: 0.5-2: 1-3: 1-2.

[0014] In order to achieve the above object, according to a third aspect of the present invention, a mine grouting method is provided, the grouting method comprising: injecting the above-mentioned coal-based microbial grouting material into a to-be-grouted area of ​​the mine.

[0015] Furthermore, the grouting method comprises: S1) drilling a borehole in the area to be filled in the mine to obtain a grouting area; S2) injecting a coal-based microbial grouting material into the area to be grouting.

[0016] Furthermore, the injection pressure is 1 MPa to 5 MPa.

[0017] By applying the technical solution of the present invention, the coal-based microbial grouting material of the present application is used for grouting in the goaf of a mine, which can fill the depressions in the goaf. The closed microbial carriers in the grouting material are ruptured after being compressed, releasing the microorganisms, thereby purifying the mine water, achieving the effect of both filling the goaf and purifying the mine water. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 A schematic diagram showing the initial rupture stage of the microbial closed carrier in Experimental Example 2 of the present invention in the goaf is shown.

[0020] Figure 2 A schematic diagram of the microbial agent release phase of the microbial closed carrier of Experimental Example 2 of the present invention in the goaf is shown.

[0021] Figure 3 A schematic diagram showing the stages of adsorption of heavy metal ions in mine water by the microbial closed carrier of Experimental Example 2 of the present invention in a goaf.

[0022] Figure 4A schematic diagram of the stratum structure of the goaf grouting filling area of ​​Test Example 2 of the present invention is shown.

[0023] Among them, the above-mentioned drawings include the following figure marks: 1 represents the gravity of the overlying rock layer; 2 represents the microbial closed carrier; 3 represents the cracks on the surface of the closed carrier; 4 represents the cracks in the goaf; 5 represents the released microbial agent; 6 represents the heavy metal ions in the mine water; 7 represents the topsoil layer; 8 represents the main key layer; 9 represents the weak layer; 10 represents the sub-key layer; 11 represents the grouting drilling hole; 12 represents the coal pillar; 13 represents the caving zone; 14 represents the fracture zone; 15 represents the goaf. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0025] As mentioned in the background technology, it is difficult for the mine grouting materials in the prior art to take into account both the filling of goaf areas and the effective purification of mine water. Therefore, in this application, the inventors attempt to develop a new coal-based microbial grouting material, and based on this, propose a series of protection schemes of this application.

[0026] In a first typical embodiment of the present application, a coal-based microbial grouting material is provided, which includes a microbial closed carrier and a coal-based raw material; the microbial closed carrier includes an internal structure and an outer layer structure, and the outer layer structure wraps the internal structure; the components of the outer layer structure include a second cement; the components of the internal structure include water, microorganisms and microbial nutrient additives.

[0027] In the long-term coal resource mining process, grouting is usually used to reinforce the goaf, repair the different degrees of depression in the ground in the goaf of the mine, prevent ground collapse, and restore ground stability. However, due to the special terrain and environmental conditions of the goaf of the mine, the requirements for grouting materials are relatively high, and it is also necessary to avoid secondary pollution to the underwater environment of the mine. At the same time, the treatment and utilization of mine water is also an important issue in the current coal industry. If mine water can be effectively treated and utilized, it can not only alleviate the problem of water shortage in local areas, but also reduce environmental pollution in mining areas.

[0028] However, the purification of mine water and the filling of goafs have encountered a series of technical challenges in actual operation. The complex water quality of mine water, such as suspended matter, high mineralization and special components, requires the use of a variety of treatment technologies. These technologies are often complicated, require a large amount of infrastructure investment, and have high operating costs, which is not conducive to the long-term treatment and improvement of mine water. Therefore, it is very difficult for current grouting materials to simultaneously achieve the filling of mine goafs and the purification of mine water.

[0029] The coal-based microbial grouting material of the present application contains coal-based raw materials and microbial closed carriers, which can repair the collapse of mine goaf areas and absorb heavy metal ions in mine water to further purify the mine water.

[0030] The coal-based raw materials in this application are all derived from coal-based solid waste, which refers to solid waste generated during the mining, washing, combustion and chemical conversion of coal. It mainly includes the following types:

[0031] Gangue: Solid waste produced during coal mining and washing that contains a certain amount of carbon but is not suitable for use as fuel. Gangue is the most common type of coal-based solid waste and usually contains high ash and impurities.

[0032] Fly ash: A fine powdery solid waste produced during the combustion of coal, mainly composed of various minerals generated by the reaction of non-carbon elements in coal at high temperatures.

[0033] Slag: During the blast furnace ironmaking process, impurities such as silica and alumina in iron ore react with lime to form a molten material with silicates and aluminosilicates as the main components, which is then quenched to form a loose, porous granular material.

[0034] If the above solid waste is not properly handled, it will not only occupy a large amount of land resources, but also cause serious pollution to the environment, including soil pollution, water pollution and air pollution. This application uses coal-based solid waste as the main component of grouting to fill the goaf depression. In addition to reducing the raw material cost of grouting materials, it also further alleviates the stacking problem of coal-based solid waste, which is more in line with the concept of green development compared with the grouting materials used to fill coal mine goaf in the prior art.

[0035] After the coal-based microbial grouting material of the present application is used to fill the goaf of the mine, when the working face near the mine is mined, the microbial closed carrier in the coal-based microbial grouting material of the present application will automatically be compressed and ruptured, and the microorganisms in the microbial closed carrier will be released into the mine water, adsorbing the heavy metal ions in the mine water, and further purifying the mine water. After the microbial closed carrier is ruptured, the microorganisms are released into the water, and the remaining part still serves as part of the grouting material, continuing to support and fill the goaf of the mine, that is, after the microbial closed carrier is ruptured, it will not affect the mechanical properties of the grouting material itself, and can further purify the mine water, so as to achieve the purification of the mine water while filling the goaf of the mine.

[0036] In a preferred embodiment, the coal-based raw material includes one or more of coal gangue, fly ash or slag; preferably, the auxiliary materials include first cement, water glass and water.

[0037] In a preferred embodiment, the mass ratio of coal gangue: fly ash, slag and the first cement in the coal-based microbial grouting material is 1-10:1-10:5-20:1-5; preferably, the ratio of the mass of water to the sum of the mass of coal gangue, fly ash, slag and the first cement is 0.2-0.6:1, including but not limited to 0.2:1, 0.3:1, 0.4:1, 0.5:1 or 0.6:1. Preferably, the mass proportion of water glass in the coal-based microbial grouting material is 1-5%, including but not limited to 1%, 2%, 3%, 4% or 5%; preferably, the mass proportion of water glass in the coal-based microbial grouting material is 2-4%, including but not limited to 2%, 3% or 4%; preferably, the mass proportion of microbial closed carrier in the coal-based microbial grouting material is 5-20%, including but not limited to 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20%; more preferably, the mass proportion of microbial closed carrier in the coal-based microbial grouting material is 8-15%; preferably, the first cement is one or more of silicate cement, aluminate cement or ferroaluminate cement.

[0038] The present application optimizes the early strength and permeability of the grouting material by controlling the ratio of coal-based raw materials (including coal gangue, fly ash and slag) to the first cement. At the same time, by adjusting the ratio of the mass of water (i.e., liquid mass) to the sum of the masses of coal gangue, fly ash, slag and the first cement (i.e., solid mass) (solid-liquid ratio, also known as water-cement ratio), the fluidity and setting time of the grouting material are improved, ensuring the smooth progress of the grouting process. In addition, by controlling the mass proportion of water glass, the stability and durability of the grouting material are further improved. The mass proportion of water glass is controlled to 1-5%, preferably 2-4%. Within this range, water glass can effectively improve the fluidity, adhesion and durability of the grouting material, and avoid the problem of pumping difficulties and long setting time caused by excessive addition.

[0039] The incorporation quality of the microbial closed carrier needs to be precisely controlled within the above range, which not only ensures that the coagulation and fluidity of the grouting material are not affected, but also ensures that the carrier can effectively release the microorganisms after rupture, thereby achieving the purpose of purifying mine water. The present application optimizes the other components in the microbial grouting material to maintain an appropriate rate of microbial release, which not only improves the ability of microorganisms to adsorb heavy metal ions, but also improves the overall effect of mine water purification. By precisely controlling the components of the coal-based microbial grouting material within the above range, the present application not only achieves effective filling of the mine goaf, but also achieves synchronous purification of mine water, thereby promoting the sustainable development of the coal mining industry.

[0040] In a preferred embodiment, the microorganisms include any one or more of the following: Arthrobacter, Bacillus, Acinetobacter, Pseudomonas or Desulfovibrio; preferably, the mass ratio of each microorganism is equal; preferably, the concentration of the microorganism in the internal structure is 1.0×10 6 ~1.0×10 8 cells / mL, including but not limited to 1×10 6 , 3×10 6 , 5×10 6 ,7×10 6 , 1×10 7 , 3×10 7 , 5×10 7 ,7×10 7 or 1×10 8 cells / mL; preferably, the microbial nutrient supplement includes peptone and / or beef extract; preferably, the second cement includes one or more of sulfoaluminate cement, silicate cement or phosphate cement; more preferably, the sulfoaluminate cement includes calcium sulfoaluminate cement.

[0041] In a preferred embodiment, the mass of each component in the microbial closed carrier is: second cement: water: microorganism: microbial nutrient supplement = 90-120: 40-55: 0.5-2: 2-5; preferably, the microbial closed carrier includes sulfoaluminate cement, water, microorganisms, peptone and beef extract; preferably, the ratio of each component in the microbial closed carrier is sulfoaluminate cement: water: microorganism: peptone: beef extract = 90-120: 40-55: 0.5-2: 1-3: 1-2; more preferably, the ratio of each component in the microbial closed carrier is sulfoaluminate cement: water: microorganism: peptone: beef extract = 100: 49: 1: 2.5: 1.5.

[0042] The microbial closed carrier of the present application is divided into two layers, the outer layer is a structure composed of cement, and the inner layer is one or more of the above-mentioned microbial agents and nutritional supplements for microorganisms. In the present application, the components of the microbial closed carrier are precisely controlled within the above-mentioned specific proportion range to ensure the synergistic effect between the components to ensure the integrity of the microbial closed carrier during the subsequent grouting process. The microbial closed carrier remains dormant in the grouting material until the grouting material breaks in the goaf, at which time the microorganisms are activated and begin to multiply. Due to the metabolic activities of these microorganisms, they can effectively degrade harmful substances in mine water, thereby achieving a purification effect on mine water.

[0043] In the preliminary research of this application, the living environment and activation conditions of microorganisms were taken into consideration in combination with the special environmental conditions of mines. Through a large amount of screening, the species of microorganisms suitable for survival in mines were selected, and the bacterial agents were mixed and cultured with the nutritional supplements of the microorganisms to improve the survival rate of the microorganisms in the closed carrier, promote the metabolic activity of the microorganisms, and enable them to multiply rapidly and play a purification role when the microbial closed carrier is broken and released into the mine water.

[0044] In a second typical embodiment of the present application, a microbial closed carrier is provided, which includes an internal structure and an outer structure, wherein the outer structure wraps the internal structure; components of the outer structure include a second cement; components of the internal structure include water, microorganisms, and microbial nutrient supplements.

[0045] In a preferred embodiment, the microorganisms include any one or more of the following: Arthrobacter, Bacillus, Acinetobacter, Pseudomonas or Desulfovibrio; preferably, the mass ratio of each microorganism is equal; preferably, the concentration of the microorganism in the internal structure is 1.0×10 6 ~1.0×10 8 cells / mL; preferably, the microbial nutrient supplement includes peptone and / or beef extract; preferably, the second cement includes one or more of sulfoaluminate cement, silicate cement or phosphate cement, more preferably sulfoaluminate cement; preferably, the sulfoaluminate cement is calcium sulfoaluminate cement.

[0046] In a preferred embodiment, the mass ratio of the components in the microbial closed carrier is: second cement: water: microorganism: microbial nutrient supplement = 90-120: 40-55: 0.5-2: 2-5; preferably, the mass ratio of the components in the microbial closed carrier is sulfoaluminate cement: water: microorganism: peptone: beef extract = 90-120: 40-55: 0.5-2: 1-3: 1-2; more preferably, the mass ratio of the components in the microbial closed carrier is sulfoaluminate cement: water: microorganism: peptone: beef extract = 100: 49: 1: 2.5: 1.5.

[0047] In a third typical embodiment of the present application, a mine grouting method is provided, which comprises grouting the above-mentioned coal-based microbial grouting material into a to-be-grouted area of ​​the mine.

[0048] In a preferred embodiment, the grouting method comprises: S1) drilling a borehole in a to-be-filled area in a mine, i.e., the to-be-grouting area; S2) injecting the above-mentioned coal-based microbial grouting material into the to-be-grouting area. When the working face of the mine is mined, the microbial closed carrier in the coal-based microbial grouting is ruptured under pressure, and the microbial agent in the microbial closed carrier enters the water in the mine.

[0049] In a preferred embodiment, the injection pressure is 1 MPa to 5 MPa.

[0050] Controlling the grouting pressure within the above range can ensure that the microbial closed carrier remains intact during the grouting process, and does not break under pressure during the grouting process, causing it to be unable to survive in the grouting material. When the working face of the mine is mined, the microbial closed carrier in the grouting material of the present application is automatically broken under pressure, releasing the microorganisms into the mine water, rapidly multiplying and taking effect, adsorbing heavy metal ions in the mine water, achieving long-term purification of the mine water quality, reducing the pressure of mine water purification, and other parts of the grouting material can also stably fill the depressed parts in the mine goaf, promoting the long-term sustainable green development of the coal industry.

[0051] The beneficial effects of the present application will be further explained in detail below in conjunction with specific embodiments.

[0052] Unless otherwise specified, the reagents used in the examples of this application are conventional commercially available products.

[0053] Example 1

[0054] The raw materials are coal gangue, fly ash, slag, first cement, water glass, microbial closed carrier and water. The particle size of coal gangue is less than 1 mm, the fly ash is secondary ash, the slag is S95 grade, the effective content of water glass is 99%, and the mass ratio of each material is coal gangue: fly ash: slag: cement = 5:5:10:3. The ratio of the mass of water to the sum of the mass of coal gangue, fly ash, slag and the first cement (water-cement ratio) is 0.4. The amount of water glass is 3wt%, and the amount of microbial closed carrier is 10wt%.

[0055] The first cement in this embodiment is silicate cement sourced from Tangshan Hongye Special Cement Co., Ltd., P.O42.5.

[0056] The outer layer material of the microbial closed carrier in this embodiment is calcium sulfoaluminate cement, and the interior includes water, microbial suspension, peptone and beef extract, and the ratio is calcium sulfoaluminate cement (Zhengzhou Xinxing Cement Plant, CA70): water: microorganism: peptone: beef extract = 100:49:1:2.5:1.5.

[0057] The microorganisms in this example are mixed by mass proportions of Arthrobacter, Bacillus, Acinetobacter, Pseudomonas, and Desulfovibrio, with a concentration of 7.0×10 7 cells / mL.

[0058] Arthrobacter was obtained from Shanghai Ruichu Biotechnology Co., Ltd. with the catalog number SHBCC D12551; Bacillus was obtained from Beina Biotechnology (BNCC) with the catalog number BNCC191581; Acinetobacter was obtained from the American Type Culture Collection (ATCC) with the collection number ATCC 19606; Pseudomonas was obtained from Shanghai Ruichu Biotechnology Co., Ltd. with the catalog number SHBCC D12510; Desulfovibrio was obtained from Wuhan Huizao Biotechnology Co., Ltd. with the catalog number HZB409697.

[0059] The preparation process of the microbial closed carrier in this embodiment is as follows:

[0060] (1) mixing calcium sulfoaluminate cement, water, microbial suspension, peptone and beef extract, and mixing the mixture in a rotary mixer at 200 rpm for 5 minutes;

[0061] (2) Casting the sample in a cubic mold of 20 mm × 20 mm × 20 mm;

[0062] (3) The sample was demoulded after 2 h and cured in a standard curing room (20 ± 2 °C, 100% RH) for 3 days;

[0063] (4) The solidified cubes were crushed, dried at 40°C, and ground until all powder particles could pass through an 80 μm sieve.

[0064] Example 2

[0065] The difference between this embodiment and embodiment 1 is only that the ratio of coal gangue: fly ash: slag: first cement is 10:10:20:5, and the water-cement ratio is 0.6.

[0066] Example 3

[0067] The difference between this embodiment and embodiment 1 is only that the ratio of coal gangue: fly ash: slag: first cement is 1:1:5:1, and the water-cement ratio is 0.2.

[0068] Example 4

[0069] The difference between this embodiment and embodiment 1 is that the dosage of the microbial closed carrier is 20%.

[0070] Example 5

[0071] The difference between this embodiment and embodiment 1 is that the dosage of the microbial closed carrier is 5%.

[0072] Example 6

[0073] The only difference between this embodiment and embodiment 1 is that the mass ratio of calcium sulfoaluminate cement: water: microbial suspension: peptone: beef extract in the microbial closed carrier of this embodiment is 120:55:2:3:2.

[0074] Example 7

[0075] The only difference between this embodiment and embodiment 1 is that the mass ratio of calcium sulfoaluminate cement: water: microbial suspension: peptone: beef extract in the microbial closed carrier of this embodiment is 90:40:0.5:1:1.

[0076] Example 8

[0077] The difference between this embodiment and embodiment 1 is only that the ratio of coal gangue: fly ash: slag: cement is 15:15:25:6, and the water-cement ratio is 0.7.

[0078] Example 9

[0079] The difference between this embodiment and embodiment 1 is only that the ratio of coal gangue: fly ash: slag: cement is 0.5:0.5:4:0.5, and the water-cement ratio is 0.1.

[0080] Example 10

[0081] The only difference between this embodiment and embodiment 1 is that the mass proportion of the closed microorganism carrier is 25%.

[0082] Embodiment 11

[0083] The only difference between this embodiment and embodiment 1 is that the mass proportion of the closed microbial carrier is 2%.

[0084] Example 12

[0085] The only difference between this embodiment and embodiment 1 is that the microorganisms in the closed microbial carrier of this embodiment are a mixture of lactic acid bacteria, yeast and actinomycetes in equal proportions.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that the microbial agent in Example 1 is directly mixed with other components of the coal-based microbial grouting material (coal gangue, fly ash, slag, cement, water glass and water) to prepare the grouting material, and no microbial closed carrier is used.

[0088] Test Example 1

[0089] The coal-based microbial grouting materials prepared in the above Examples 1 to 12 and Comparative Example 1 were subjected to a 28-day compressive strength and flexural strength test (Standard for Test Methods for Physical and Mechanical Properties of Concrete GB / T 50081-2019). The test results are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] When the compressive strength of the grouting material is greater than 20MPa and the flexural strength is greater than 4MPa, the grouting material meets the requirements for filling coal mine goaf areas.

[0094] The mining pressure of the coal mine working face was simulated, and the coal-based microbial grouting materials prepared in the above Examples 1 to 12 and Comparative Example 1 were pressurized to rupture the closed microbial carriers in the grouting materials to release microorganisms to purify water and adsorb heavy metal ions such as Pb, Cd, and Cr. The adsorption effect was detected (Determination of 65 Elements in Water Quality by Inductively Coupled Plasma Mass Spectrometry HJ700-2014). The results are shown in Table 2.

[0095] The calculation formula of heavy metal purification rate is as follows:

[0096]

[0097] Table 2

[0098] Heavy metal Pb purification rate (%) Heavy metal Cd purification rate (%) Heavy metal Cr purification rate (%) Example 1 93.20 94.10 88.50 Example 2 88.40 89.60 84.20 Example 3 86.60 87.80 82.30 Example 4 91.80 92.50 87.10 Example 5 87.10 88.90 83.40 Example 6 89.50 91.20 85.50 Example 7 87.20 89.80 83.60 Example 8 84.90 86.50 81.40 Example 9 81.20 83.20 78.10 Example 10 90.60 91.50 86.60 Embodiment 11 86.40 88.40 82.70 Example 12 78.30 80.50 74.50 Comparative Example 1 72.90 74.90 69.80

[0099] Test Example 2

[0100] The grouting material prepared in Example 1 is injected into the goaf for filling and purification of mine water.

[0101] The drilling grouting pipe in this embodiment is made of rubber hose. The grouting borehole penetrates the coal pillar between the working face and the goaf, and the length extending into the goaf is 1 / 4 to 3 / 4 of the total length of the goaf. The borehole is divided into different sections. A single drilling section is 20m long and has a hole diameter of 40mm to 50mm. The interval between each grouting borehole is 10m to 15m, and the grouting pressure is maintained between 1MPa and 5MPa.

[0102] When the working face of the goaf is mined, the grouting material is compressed, causing the microbial closed carrier to break and purify the heavy metals in the mine water in the goaf. The schematic diagram of the initial rupture stage of the microbial closed carrier in the goaf is shown in the figure. Figure 1 As shown in the figure, 1 represents the gravity of the overlying rock layer, 2 represents the microbial closed carrier, 3 represents the cracks on the surface of the closed carrier, that is, the cracks that rupture after being compressed, and 4 represents the cracks in the goaf. The schematic diagram of the microbial agent release stage of the microbial closed carrier in the goaf is shown in the figure. Figure 2 5 represents the released microbial agent. Schematic diagram of the stage of adsorption of heavy metal ions in mine water in the goaf by microbial closed carriers Figure 3As shown in Figure 6, where 6 represents the heavy metal ions in the mine water. Figure 4 As shown, 7 represents the topsoil layer, 8 represents the main key layer, 9 represents the weak layer, 10 represents the sub-key layer, 11 represents the grouting borehole, 12 represents the coal pillar, 13 represents the caving zone, 14 represents the fracture zone, and 15 represents the goaf.

[0103] The specific effects of injecting the grouting material prepared in Example 1 of the present application into the goaf for filling and purification of mine water are as follows: the material has good fluidity and adhesion, and its compressive and flexural strengths after 28 days can reach 33.52 MPa and 6.35 MPa, and the addition of microbial closed carriers improves the self-healing effect of the material. The formed consolidated body has good bearing capacity and can effectively fill the goaf; the purification rate of heavy metal ions Pb and Cd exceeds 90%, and the purification rate of heavy metal ions Cr exceeds 88%, with good heavy metal adsorption effect; at the same time, it can adjust the pH value of mine water and inhibit the migration of heavy metals.

[0104] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: the coal-based microbial grouting material of the present application can be used to stably fill the depression in the goaf of the mine. When the working face of the mine is mined, the closed carrier of the microorganisms in the grouting material breaks, and the microorganisms are released into the mine water, which adsorbs the heavy metals in the mine water and further purifies the water quality of the mine water. The coal-based microbial grouting material of the present application can take into account both the filling of the mine mining area and the purification of the mine water, and promote the sustainable green development of the coal industry.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A coal-based microbial grouting material, characterized in that: The coal-based microbial grouting material comprises a microbial closed carrier and a coal-based raw material; The microbial closed carrier comprises an inner structure and an outer structure, wherein the outer structure wraps the inner structure; components of the outer structure comprise a second cement; and components of the inner structure comprise water, microorganisms and microbial nutrient supplements.

2. The coal-based microbial grouting material according to claim 1, characterized in that: The coal-based raw materials include one or more of coal gangue, fly ash or slag; Preferably, the coal-based microbial grouting material further comprises auxiliary materials; Preferably, the auxiliary materials include first cement, water glass and water.

3. The coal-based microbial grouting material according to claim 1 or 2, characterized in that: The mass ratio of coal gangue, fly ash, slag and first cement in the coal-based microbial grouting material is 1-10:1-10:5-20:1-5; Preferably, the ratio of the mass of the water in the coal-based microbial grouting material to the sum of the mass of the coal gangue, the fly ash, the slag and the first cement is 0.2-0.6:1; Preferably, the mass proportion of the water glass in the coal-based microbial grouting material is 1-5%; Preferably, the mass proportion of the microbial closed carrier in the coal-based microbial grouting material is 5-20%; Preferably, the first cement comprises one or more of silicate cement, aluminate cement or ferroaluminate cement; The microorganisms include any one or more of the following: Arthrobacter, Bacillus, Acinetobacter, Pseudomonas or Desulfovibrio; Preferably, the mass ratios of the microorganisms are equal; Preferably, the concentration of the microorganisms in the internal structure is 1.0×10 6 ~1.0×10 8 cells / mL; Preferably, the microbial nutritional supplement comprises peptone and / or beef extract; Preferably, the second cement comprises one or more of sulphoaluminate cement, silicate cement or phosphate cement.

4. The coal-based microbial grouting material according to claim 1 or 3, characterized in that: The mass ratio of the components in the microbial closed carrier is: second cement: water: microorganism: microbial nutrient auxiliary material = 90-120: 40-55: 0.5-2: 2-5; Preferably, the components of the microbial closed carrier include sulphoaluminate cement, water, microorganisms, peptone and beef extract; Preferably, the mass ratio of the components in the microbial closed carrier is sulphoaluminate cement: water: microorganism: peptone: beef extract = 90-120: 40-55: 0.5-2: 1-3: 1-2.

5. A microbial closed carrier, characterized in that: The microbial closed carrier comprises an inner structure and an outer structure, wherein the outer structure wraps the inner structure; components of the outer structure comprise a second cement; and components of the inner structure comprise water, microorganisms and microbial nutrient supplements.

6. The closed microbial carrier according to claim 5, characterized in that: The microorganisms include any one or more of the following: Arthrobacter, Bacillus, Acinetobacter, Pseudomonas or Desulfovibrio; Preferably, the mass ratios of the microorganisms are equal; Preferably, the concentration of the microorganisms in the internal structure is 1.0×10 6 ~1.0×10 8 cells / mL; Preferably, the microbial nutritional supplement comprises peptone and / or beef extract; Preferably, the second cement comprises one or more of sulphoaluminate cement, silicate cement or phosphate cement.

7. The closed microbial carrier according to claim 5 or 6, characterized in that: The mass ratio of the components in the microbial closed carrier is: second cement: water: microorganism: microbial nutrient auxiliary material = 90-120: 40-55: 0.5-2: 2-5; Preferably, the microbial closed carrier comprises sulphoaluminate cement, water, microorganisms, peptone and beef extract; Preferably, the mass ratio of the components in the microbial closed carrier is sulphoaluminate cement: water: microorganism: peptone: beef extract = 90-120: 40-55: 0.5-2: 1-3: 1-2.

8. A grouting method for a mine, characterized in that: The grouting method comprises: injecting the coal-based microbial grouting material according to any one of claims 1 to 5 into the area to be grouting in the mine.

9. The grouting method according to claim 8, characterized in that: The grouting method comprises: S1) drilling a borehole in the area to be filled in the mine to obtain the grouting area; S2) injecting the coal-based microbial grouting material into the area to be grouting.

10. The grouting method according to claim 9, characterized in that: The injection pressure is 1 MPa to 5 MPa.

Images