Improved thermal insulation support material and use method thereof

Abstract

The invention discloses an improved thermal insulation support material and a use method thereof. The improved thermal insulation support material is prepared from the following components in parts by mass: 900 to 1250 parts of coarse aggregate, 440 to 510 parts of fine aggregate, 560 to 650 parts of cement, 190 to 220 parts of water, 2 to 8 parts of basalt fiber and 20 to 80 parts of hollow glass beads. The use method comprises the following steps: preparing raw materials, stirring, spraying, forming a thermal insulation layer, and curing. The prepared supporting material is applied to an underground deep high-temperature mine and used for blocking a surrounding rock heat source, the heat transfer amount of surrounding rock to a roadway is greatly reduced, the temperature of air flow in the roadway is reduced, the underground high-heat and high-humidity state is remarkably improved, and a thermal insulation layer formed after spraying is good in anti-cracking effect, high in strength, light in weight, good in durability, low-carbon, green and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of thermal insulation support technology for underground mining roadways, specifically relating to an improved thermal insulation support material and its application method, which is particularly suitable for promotion and application in deep mines with severe heat hazards. Background Technology

[0002] As mining depths increase, the problem of heat hazards caused by high temperature and humidity becomes increasingly apparent and prominent. The high-temperature working environment caused by mine heat hazards not only significantly reduces production efficiency and seriously affects the physical and mental health of underground workers, but also increases the failure rate of underground electrical equipment, greatly increasing the risk of safety accidents. Therefore, effective control of mine heat hazards is urgently needed.

[0003] Currently, the main approaches to controlling heat hazards in mines are as follows: First, heat removal, which generally involves changing the layout of roadways, ventilation and cooling, and optimizing ventilation paths; second, heat insulation, which reduces the transmission of heat sources from the ground into the roadways, and the most direct and effective method is to directly isolate the heat source at its source; and third, cooling, which involves artificially introducing cold sources to lower the temperature in the roadways, such as artificial ice making, chilled water, and mine air conditioning. The first two are generally referred to as non-mechanical refrigeration methods, which are active cooling measures, while the third is a mechanical refrigeration method, which is a passive cooling measure.

[0004] From a development trend perspective, mechanical refrigeration will be the primary measure for preventing and controlling high-temperature heat hazards in deep and ultra-deep mines. Currently, underground mining in my country is in a transitional phase from shallow to deep operations. The development direction for heat hazard prevention is to prioritize non-mechanical refrigeration technologies in shallow and medium-temperature mines, while deep high-temperature mines will primarily rely on mechanical refrigeration for cooling, supplemented by a comprehensive approach using non-mechanical refrigeration. Currently, most internal refrigeration equipment relies on imports, which are expensive, have low cooling efficiency, poor flexibility, huge energy consumption, and high operation and maintenance costs. Therefore, efficient heat insulation in deep mines is of great significance and value. The approach involves covering the surrounding rock of the roadway with insulating materials to construct an insulating layer, reducing heat dissipation from the surrounding rock into the roadway and achieving cooling of the roadway airflow. Summary of the Invention

[0005] The purpose of this invention is to address the technical challenges of high temperature and humidity in deep mine roadways, the low cooling efficiency and high energy consumption of existing mine heat hazard control technologies, and the high operation and maintenance costs. This invention provides an improved thermal insulation support material with excellent thermal insulation performance, low thermal conductivity, light weight, and high strength.

[0006] Another object of the present invention is to provide a method of using the above-mentioned improved thermal insulation support material.

[0007] To achieve the above-mentioned objectives of the present invention, an improved thermal insulation support material of the present invention adopts the following technical solution:

[0008] This invention discloses an improved thermal insulation support material for thermal insulation treatment of heat hazards in deep mine roadways. The improved thermal insulation support material is composed of coarse aggregate, fine aggregate, cement, basalt fiber, hollow glass microspheres, and water in the following mass ratio: 900-1250 parts coarse aggregate, 440-510 parts fine aggregate, 560-650 parts cement, 190-220 parts water, 2-8 parts basalt fiber, and 20-80 parts hollow glass microspheres.

[0009] Preferably, the coarse aggregate includes ceramsite and crushed stone, and the fine aggregate includes ceramsite sand and gravel; the cement is silicate cement with a grade of not less than 425#.

[0010] Preferably, the basalt fiber density is 2.6~2.8 g / m³. 3 The tensile strength is ≥1050MPa, the elastic modulus is ≥35GPa, the elongation at break is ≤3.5%, and the alkali resistance is ≥95%.

[0011] Preferably, the true density of the hollow glass microspheres is 0.60~0.66 g / m³. 3 80% retain compressive strength of 90~105MPa, D50 particle size is 25μm~35μm.

[0012] Preferably, the crushed stone is continuously graded melon seed flakes with a particle size distribution range of 6mm to 12mm.

[0013] To verify the performance of the improved thermal insulation support material formulated in this invention, the following steps were also performed for performance testing:

[0014] ① Place coarse and fine aggregates into a mixer and mix for 3-5 minutes. Then, add cement, basalt fiber, hollow glass microspheres, and water in sequence and mix for 6-10 minutes until homogeneous and fully combined. During mixing, maintain an ambient temperature of 18ºC-38ºC and an ambient humidity of 35%-75%, and control the mixing speed at 80-120 rpm.

[0015] ② Pour the well-mixed mixture into a 100mm*100mm*100mm cast iron mold to test the compressive strength, into a 50mm*50mm*50mm cast iron mold to test the shear strength, and into a 300mm*300mm*30mm cast iron mold to prepare a block for testing the thermal conductivity.

[0016] ③ Place each set of test blocks on the vibrating table, and fill and vibrate in layers. First layer: Fill half the concrete, turn on the vibrating table, and vibrate for 20-35 seconds until the concrete surface is smooth and no obvious air bubbles emerge. Second layer: Fill the remaining concrete, and use a trowel to gently tamp along the wall of the mold to fill the mold completely. Turn on the vibrating table again and vibrate until the surface is smooth. Smoothing and finishing: After vibration, use a trowel to scrape away excess concrete from the top of the mold. Before the concrete initially sets, carefully smooth the surface to make it flush with the edge of the mold.

[0017] ④ Place the vibrated test blocks in a standard laboratory for curing for 14 days. The curing environment temperature is 18 ºC~22 ºC and the relative humidity is ≥95%.

[0018] ⑤ The uniaxial compressive strength, shear strength and thermal conductivity of the cured test blocks were tested respectively. The performance parameters of the test blocks were as follows: uniaxial compressive strength 34.02~52.17MPa, cohesion c 2.66~5.75MPa, internal friction angle φ 38.2~41.8º, and thermal conductivity λ 0.24076~0.44173W / m*K.

[0019] This invention also discloses a method for using an improved thermal insulation support material, which is implemented by the following steps:

[0020] (1) Raw material preparation: Weigh each component according to the mass ratio of coarse aggregate, fine aggregate, cement, basalt fiber, hollow glass microspheres and water;

[0021] (2) Mixing: Place the coarse aggregate and fine aggregate into a forced mixer and mix for 3-5 minutes. Then add cement, basalt fiber, hollow glass microspheres and water in sequence and mix for 6-10 minutes until uniform and a mixture is made.

[0022] (3) Spraying and forming a heat insulation layer: Inject the mixture into the spraying trolley, turn on the spraying trolley nozzle to spray the mixture from bottom to top in sections, pieces and layers in the high temperature roadway. The thickness of one spray is 50-70mm, and the interval between re-spraying is not less than 1 hour. The total thickness of the heat insulation layer formed in the end is 100-150mm.

[0023] (4) Curing: Water curing shall begin 1 hour after the final setting of the shotcrete. The curing time shall not be less than 14 days. The rebound rate of the side wall shall not be greater than 15%, and that of the arch shall not be greater than 25%.

[0024] Furthermore, before wet spraying the high-temperature roadway, the surface of the surrounding rock of the roadway is thoroughly rinsed with high-pressure air and clean water to remove loose rock and debris. Thickness markers for the sprayed layer are installed on the roof and sides of the roadway to control the quality of the spraying.

[0025] Furthermore, for roadways with fractured or weak surrounding rock, steel arches are erected, anchor bolts or steel mesh are installed, and the mixture is sprayed only after being spliced ​​and tightened in sequence.

[0026] Furthermore, the spray nozzle of the spraying trolley is perpendicular to the sprayed surface, and the distance is maintained at 0.5~1.0m; during spraying, the nozzle moves continuously and slowly in a horizontal circular motion, with one circle overlapping half a circle to ensure uniform thickness.

[0027] After adopting the above technical solutions, the improved thermal insulation support material and its application method of the present invention have the following beneficial effects:

[0028] (1) Adding an appropriate amount of hollow glass microspheres and basalt fiber significantly improved the thermal insulation performance and compressive strength of the support material. The thermal conductivity decreased by an average of 48.7%, the uniaxial compressive strength increased by an average of 29.78%, and the cohesion increased by an average of 3.7%.

[0029] (2) The prepared support material is used in deep underground high-temperature mines to block the heat source of the surrounding rock, greatly reduce the heat transfer from the surrounding rock to the roadway, reduce the airflow temperature in the roadway, and significantly improve the high heat and high humidity conditions underground.

[0030] (3) The preparation process is simple and convenient, the cost is low, and the spraying and curing process is simple; the thermal insulation layer formed after spraying has good crack resistance, high strength and light weight, good durability, and low carbon and green environmental protection.

[0031] (4) Experimental studies show that by optimizing the raw material composition formula and synergistically adjusting the technical parameters in the preparation and use process, the technical performance of the final heat insulation support layer can reach: uniaxial compressive strength as high as 45.00~55MPa, thermal conductivity λ as low as 0.23~0.29W / m*K, with significant effect. Attached Figure Description

[0032] Figure 1 This is a comparison diagram of the uniaxial compressive strength and cohesion of an embodiment and a comparative example of an improved thermal insulation support material of the present invention.

[0033] Figure 2 This is a comparison diagram of the thermal conductivity of an embodiment and a comparative example of an improved thermal insulation support material of the present invention. Detailed Implementation

[0034] To better describe the present invention, an improved thermal insulation support material and its application method according to the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to this embodiment. Those skilled in the art will understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific conditions and parameters not specified in the embodiments are performed according to conventional conditions or conditions recommended by the actual operators at the site. Reagents, instruments, and equipment used, unless otherwise specified, are all commercially available products.

[0035] The improved thermal insulation support material of the present invention is composed of coarse aggregate, fine aggregate, cement, basalt fiber, hollow glass microspheres and water in the following mass ratio: 900-1250 parts of coarse aggregate, 440-510 parts of fine aggregate, 560-650 parts of cement, 190-220 parts of water, 2-8 parts of basalt fiber and 20-80 parts of hollow glass microspheres.

[0036] In this embodiment, the coarse aggregate includes ceramsite and crushed stone, and the fine aggregate includes ceramsite sand and gravel; the cement used is silicate cement with a grade of not less than 425#; the basalt fiber density is 2.6~2.8 g / m³. 3 The hollow glass microspheres exhibit a tensile strength ≥1050MPa, an elastic modulus ≥35GPa, an elongation at break ≤3.5%, and an alkali resistance ≥95%. These microspheres were produced by Sinosteel Maanshan Mining Institute New Materials Technology Co., Ltd., with a true density of 0.60~0.66g / m³. 3 80% retain compressive strength of 90~105 MPa, D50 particle size of 25μm~35μm; the crushed stone is continuously graded melon seed flakes with a particle size distribution range of 6mm~12mm.

[0037] The component ratios in this embodiment are as follows: The mixture consists of coarse aggregate, fine aggregate, cement, admixtures (basalt fiber, hollow glass microspheres), and water, prepared in a specific proportion. The mass ratio of coarse aggregate: fine aggregate: cement: water is 1110 parts: 476 parts: 604 parts: 210 parts. The coarse aggregate includes expanded clay and crushed stone, the fine aggregate includes expanded clay sand and gravel, and the admixtures are basalt fiber and hollow glass microspheres. The basalt fiber addition is at three levels: 2.4 parts, 4.8 parts, and 7.2 parts. The hollow glass microsphere addition is at three levels: 24 parts, 48 ​​parts, and 72 parts. Specific sample ratios are detailed in Table 1 below.

[0038] Table 1 Formulation of Examples

[0039]

[0040] In this embodiment, the improved thermal insulation support material prepared in the laboratory was processed according to the following steps:

[0041] (1) Mixing: Place coarse aggregate and fine aggregate into a mixer and mix for 3-5 minutes. Then add cement, basalt fiber, hollow glass microspheres and water in sequence and mix for 6-10 minutes until uniform.

[0042] (2) Mold pouring: The mixture is poured into a 100mm*100mm*100mm cast iron mold in sequence to test the compressive strength, into a 50mm*50mm*50mm cast iron mold to test the shear strength, and into a 300mm*300mm*30mm cast iron mold to test the thermal conductivity.

[0043] (3) Vibration: Each group of test blocks is placed on a vibrating table, and the material is loaded and vibrated in layers. After vibration, the excess concrete is scraped off along the top of the mold with a trowel. Before the concrete sets, the surface is carefully smoothed so that it is flush with the edge of the mold.

[0044] (4) Curing: The vibrated test blocks are placed in a standard laboratory for curing for 14 days.

[0045] Comparative Example

[0046] To better compare the treatment effects, traditional downhole support shotcrete was used as a comparative example to determine the uniaxial compressive strength, shear strength, and thermal conductivity. The traditional support shotcrete mix ratio was gravel:abrasive:cement:water = 727 parts:890 parts:580 parts:254 parts. The comparison results are as follows: Figure 1 The diagram shows a comparison of the uniaxial compressive strength and cohesion of an embodiment of the improved thermal insulation support material of the present invention with that of a comparative example. Figure 2 The thermal conductivity comparison diagram and Table 2 show the embodiment and comparative example of the improved thermal insulation support material of the present invention.

[0047] Table 2 Performance of Examples and Comparative Examples

[0048]

[0049] As shown in Table 2, the improved thermal insulation support material prepared in this invention exhibits a uniaxial compressive strength of 34.02–52.17 MPa, a cohesion c of 2.66–5.75 MPa, an internal friction angle φ of 38.2–41.8°, and a thermal conductivity λ of 0.24076–0.44173 W / m*K. In contrast, the comparative example shows a uniaxial compressive strength of 32.11 MPa, a cohesion c of 3.59 MPa, an internal friction angle φ of 39.2°, and a thermal conductivity λ of 0.7279 W / m*K.

[0050] In industrial applications, this invention provides a method for using an improved thermal insulation support material. Before wet spraying in high-temperature roadways, the surface of the surrounding rock is thoroughly rinsed with high-pressure air and clean water to remove loose rock and debris. Thickness markers for the sprayed layer are installed on the roadway roof and sides to control the spraying quality. For roadway surrounding rock that is broken or weak, steel arches are erected, anchor bolts or steel mesh are installed, and the mixture is sprayed only after being sequentially spliced ​​and tightened. The specific implementation steps are as follows:

[0051] (1) Raw material preparation: Weigh each component according to the mass ratio of coarse aggregate, fine aggregate, cement, basalt fiber, hollow glass microspheres and water.

[0052] (2) Mixing: Place the coarse aggregate and fine aggregate into a forced mixer and mix for 3-5 minutes. Then add cement, basalt fiber, hollow glass microspheres and water in sequence and mix for 6-10 minutes until uniform and a mixture is made.

[0053] (3) Spraying and forming a heat insulation layer: Inject the mixture into the shotcrete trolley, turn on the shotcrete trolley nozzle to spray the mixture from bottom to top in sections, pieces and layers in the high-temperature roadway. The thickness of each spray is 50-70mm, and the interval between re-sprays is not less than 1 hour. The total thickness of the heat insulation layer formed in the end is 100-150mm. The shotcrete trolley nozzle is perpendicular to the sprayed surface and the distance is maintained at 0.5-1.0m. When spraying, the nozzle keeps moving in a continuous and slow horizontal ring, one ring pressing half a ring to ensure uniform thickness.

[0054] (4) Curing: Water curing shall begin 1 hour after the final setting of the shotcrete. The curing time shall not be less than 14 days. The rebound rate of the side wall shall not be greater than 15%, and that of the arch shall not be greater than 25%.

[0055] An improved thermal insulation support material prepared by this invention has been applied in the "Ultra-deep Large-scale Intelligent Ventilation and Cooling Technology and Equipment for Metal Mines" project. Compared with traditional support shotcrete, its thermal conductivity is reduced by an average of nearly 50%, and the mine temperature at the same depth is reduced by an average of 3-5℃, achieving a very good cooling effect.

Claims

1. An improved thermal insulation support material for thermal insulation and control of heat hazards in deep mine roadways, characterized in that: It is composed of coarse aggregate, fine aggregate, cement, basalt fiber, hollow glass microspheres and water in the following mass ratio: 900~1250 parts coarse aggregate, 440~510 parts fine aggregate, 560~650 parts cement, 190~220 parts water, 2~8 parts basalt fiber and 20~80 parts hollow glass microspheres.

2. The improved thermal insulation support material as described in claim 1, characterized in that: The coarse aggregate includes expanded clay and crushed stone, and the fine aggregate includes expanded clay sand and gravel; the cement used is silicate cement with a grade of not less than 425#.

3. The improved thermal insulation support material as described in claim 1, characterized in that: The density of the basalt fibers is 2.6~2.8 g / m³. 3 The tensile strength is ≥1050MPa, the elastic modulus is ≥35GPa, the elongation at break is ≤3.5%, and the alkali resistance is ≥95%.

4. The improved thermal insulation support material as described in claim 1, characterized in that: The true density of the hollow glass microspheres is 0.60~0.66 g / m³. 3 80% retain compressive strength of 90~105 MPa, D50 particle size is 25μm~35μm.

5. An improved thermal insulation support material as described in claim 2, 3, or 4, characterized in that: The crushed stone is continuously graded melon seed flakes with a particle size distribution range of 6mm to 12mm.

6. The method of using the improved thermal insulation support material as described in claim 5, characterized in that... The following steps are adopted: (1) Raw material preparation: Weigh each component according to the mass ratio of coarse aggregate, fine aggregate, cement, basalt fiber, hollow glass microspheres and water; (2) Mixing: Place the coarse aggregate and fine aggregate into a forced mixer and mix for 3-5 minutes. Then add cement, basalt fiber, hollow glass microspheres and water in sequence and mix for 6-10 minutes until uniform and a mixture is made. (3) Spraying and forming a heat insulation layer: Inject the mixture into the spraying trolley, turn on the spraying trolley nozzle to spray the mixture from bottom to top in sections, pieces and layers in the high temperature roadway. The thickness of one spray is 50-70mm, and the interval between re-spraying is not less than 1 hour. The total thickness of the heat insulation layer formed in the end is 100-150mm. (4) Curing: Water curing shall begin 1 hour after the final setting of the shotcrete. The curing time shall not be less than 14 days. The rebound rate of the side wall shall not be greater than 15%, and that of the arch shall not be greater than 25%.

7. The method of using the improved thermal insulation support material as described in claim 6, characterized in that: Before wet spraying the high-temperature roadway, the surface of the surrounding rock of the roadway is thoroughly rinsed with high-pressure air and clean water to remove loose rock and debris. Thickness markers for the sprayed layer are installed on the roof and sides of the roadway to control the quality of the spraying.

8. The method of using the improved thermal insulation support material as described in claim 7, characterized in that: For roadways with broken or weak surrounding rock, steel arches, anchor bolts, or steel mesh are installed, and the mixture is sprayed only after being spliced ​​and tightened in sequence.

9. The method of using the improved thermal insulation support material as described in claim 7, characterized in that: The spray nozzle of the shotcrete trolley is perpendicular to the surface to be sprayed, and the distance is maintained at 0.5~1.0m. During spraying, the nozzle moves continuously and slowly in a horizontal circular motion, with one circle overlapping half a circle to ensure uniform thickness.

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