Method for preparing mining-induced fracture grouting water-blocking material from coal gasification ash
By preparing coal gasification ash-based grouting water-blocking materials, the problem of coal mining fissure leakage is solved, resource utilization and cost reduction are achieved, and it has excellent sealing and reinforcement effects and is suitable for the field of mining engineering.
Patent Information
- Application Number
- CN202510800234.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-09
AI Technical Summary
During coal mining, cracks caused by mining stress lead to groundwater leakage. Traditional grouting materials are expensive and ineffective under complex geological conditions. At the same time, coal gasification ash is not effectively utilized, resulting in resource waste and environmental pollution.
Using coal gasification ash, fly ash, cement, bentonite and water reducer as raw materials, through mixing in specific proportions and ball milling treatment, a grouting water-blocking material with good fluidity, setting time, compressive strength and low permeability is prepared, and the mining cracks are filled by grouting.
Effectively utilize coal gasification ash to reduce costs, achieve effective sealing and reinforcement of mining fissures, have excellent water-blocking properties, significantly reduce water leakage, and improve coal mine production safety and economic benefits.
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Figure CN120607387A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of mining engineering, in particular to a method for preparing mining fissure grouting water-blocking material by utilizing coal gasification ash. Background Art
[0002] During coal mining, mining stresses can cause cracks to form in the coal seam roof. These cracks often lead to groundwater leakage, which not only affects the normal operation of coal mining but also may cause loss of surface water resources and environmental pollution. Traditional grouting materials, mainly cement, are expensive and have certain environmental impacts. Furthermore, using cement alone as a grouting material may not achieve the ideal water-blocking and reinforcement effects under certain complex geological conditions.
[0003] Coal gasification ash, a solid waste generated during the coal gasification process, has a certain degree of activity, but currently most of it is directly discarded or simply landfilled, resulting in resource waste and environmental pollution. Therefore, there is an urgent need to develop a method that can both utilize coal gasification ash and effectively solve the problem of water blocking in mining-induced fissure grouting. Summary of the Invention
[0004] The purpose of the present invention is to provide a method for preparing mining fissure grouting water-blocking material using coal gasification ash, so as to solve the grouting water-blocking problem of mining fissures during coal mining and realize the effective utilization of coal gasification ash.
[0005] To achieve the above object, the present invention provides the following solutions:
[0006] One of the technical solutions of the present invention: a mining fissure grouting water-blocking material, the raw materials of which include the following components, calculated by mass: 37 to 47 parts of coal gasification ash, 9 to 13 parts of fly ash, 5 to 8 parts of cement, 2 to 3 parts of bentonite, 0.3 to 0.7 parts of water reducer and 30 to 46 parts of water.
[0007] Coal gasification ash is the main raw material to provide the basis of cementitious material, bentonite improves the viscosity and water retention of the slurry and stabilizes the reaction process, and fly ash improves fluidity and enhances strength. They work together to achieve a balance in the performance of grouting water-blocking materials such as fluidity, setting time, compressive strength, micro-expansion rate and permeability coefficient, effectively realizing the functions of sealing and reinforcing mining cracks.
[0008] Furthermore, the moisture content of the coal gasification ash is ≤1%.
[0009] Furthermore, the particle size of the coal gasification ash is ≤45 μm, and the specific surface area is ≥400 m 2 / kg.
[0010] Furthermore, the water includes groundwater, tap water or industrial wastewater.
[0011] The second technical solution of the present invention is a method for preparing a mining fissure grouting water-blocking material using coal gasification ash, comprising the following steps:
[0012] Weigh each raw material according to the raw material composition defined above;
[0013] The raw materials are mixed to obtain the mining fissure grouting water-blocking material.
[0014] Furthermore, the process further includes drying and ball milling the coal gasification ash before weighing the raw materials.
[0015] Furthermore, the drying is specifically drying the coal gasification ash to a moisture content of ≤1%.
[0016] Furthermore, the ball milling is specifically to ball mill the coal gasification ash to a particle size of ≤45 μm and a specific surface area of ≥400 m 2 / kg.
[0017] Ball milling the coal gasification ash to the above-mentioned particle size and specific surface area can greatly improve its reactivity and uniformity. Small particle size will increase the specific surface area, allowing the ash to come into more complete contact with other raw materials such as cement, fly ash, bentonite, etc. In the hydration reaction, more active sites are exposed, which speeds up the reaction and generates more hydration products, thereby enhancing the strength of the grouting water-blocking material. At the same time, the small particle size can ensure that the slurry has good fluidity, facilitates diffusion in the mining fissures, and ensures effective filling of the fissures. If the particle size is too large, it means that the specific surface area is small, the contact area between the coal gasification ash and other raw materials is reduced, the hydration reaction is difficult to proceed fully, and the generated cementitious substances are reduced, resulting in a decrease in the strength of the grouting water-blocking material, which cannot effectively withstand the pressure of the mining fissures and easily causes the fissures to reopen. Large particle size particles will also affect the fluidity of the slurry.
[0018] Furthermore, the mixing of the raw materials comprises:
[0019] First, coal gasification ash, fly ash, cement and bentonite are mixed evenly to obtain a mixed dry material; then a water reducer is added and mixed evenly to obtain a mixed material; finally, water is added and mixed evenly to obtain the mining fissure grouting water-blocking material.
[0020] Furthermore, when the coal gasification ash, fly ash, cement and bentonite are uniformly mixed, the stirring time is not less than 3 minutes.
[0021] Furthermore, when the water reducing agent is added and mixed evenly, the stirring time is not less than 1 minute.
[0022] Furthermore, when adding water and mixing evenly, the stirring time is not less than 5 minutes.
[0023] Furthermore, the stirring speed is 200-400 r / min.
[0024] Furthermore, the fluidity of the mining fissure grouting water-blocking material is 18 to 22 seconds.
[0025] The third technical solution of the present invention: application of the above-mentioned mining fissure grouting water-blocking material in filling and reinforcing mining fissures.
[0026] Furthermore, the filling reinforcement is achieved by grouting, and the parameters of the grouting include: the grouting hole spacing is 3 to 5 meters, the grouting pressure is 2 to 3 MPa, and the grouting time per hole is 15 to 20 minutes.
[0027] The present invention discloses the following technical effects:
[0028] The present invention not only effectively utilizes coal gasification ash, but also produces a grouting water-blocking material with excellent performance. Specifically, the present invention uses coal gasification ash as the main raw material to prepare a grouting water-blocking material for mining fissures. This solves both the solid waste disposal problem of coal gasification ash and the problem of grouting water-blocking in mining fissures in mines. The prepared grouting water-blocking material is low in cost and has a certain compressive strength. It can achieve multiple functions such as water-blocking grouting, backfilling goaf, reinforcing bedrock in goafs, and preventing goaf collapse.
[0029] The method of the present invention specifically has the following advantages:
[0030] 1. Resource Utilization
[0031] This invention effectively utilizes coal gasification ash, successfully transforming it into valuable resources. As an industrial waste, coal gasification ash often poses environmental and resource challenges. However, the present invention utilizes coal gasification ash as a primary component of a grouting water-blocking material, resolving waste disposal challenges and providing it with new value.
[0032] In the present invention, there is a unique and critical synergistic mechanism between coal gasification ash, bentonite and fly ash, which is what distinguishes it from the existing technology. Coal gasification ash is rich in oxides such as silicon and aluminum, and can undergo hydration reactions in an alkaline environment to generate substances with gelling properties; bentonite has excellent water absorption and swelling properties, and forms a colloidal dispersion system when it comes into contact with water. It can not only greatly improve the viscosity and water retention of the slurry, but also, when mixed with coal gasification ash, use its colloidal dispersion system to wrap around the surface of the coal gasification ash particles, preventing them from hydrating too quickly, making the reaction more uniform and lasting, and enhancing the stability of the grouting water-blocking material. The spherical particle shape of fly ash enables it to improve the fluidity of the slurry like a ball bearing, reducing stirring and pumping resistance, and its active ingredients can undergo a secondary reaction with the calcium hydroxide produced by the hydration of coal gasification ash to generate more gel substances, further improving the strength of the grouting water-blocking material. The synergistic effect between them is not a simple physical mixing, but rather a mutual promotion and complementation at the chemical and physical levels.
[0033] 2. Economic benefits
[0034] In terms of economic benefits, this invention offers significant advantages over traditional cement slurries, reducing costs by 30-40%. Traditional cement slurries are widely used in grouting projects, but they are relatively expensive. This invention effectively reduces the cost of grouting water-blocking materials through a rational raw material ratio and process optimization.
[0035] 3. Performance advantages
[0036] (1) Setting time
[0037] The grouting water-blocking material of the present invention exhibits excellent setting time performance. The initial setting time is between 2 and 4 hours, and the final setting time is 6 to 8 hours. This setting time range allows the grouting water-blocking material sufficient time to flow and fill the cracks after injection, ensuring that it reaches all areas of the cracks. Furthermore, a reasonable setting time facilitates construction operations, allowing construction personnel to rationally schedule grouting and subsequent processes based on actual conditions, thereby improving construction efficiency.
[0038] (2) Compressive strength
[0039] Compressive strength is a key quality indicator for grouting water-blocking materials. The grouting water-blocking material of the present invention demonstrates excellent compressive strength, with a 7-day compressive strength of ≥15 MPa and a 28-day compressive strength of ≥25 MPa. This high compressive strength ensures that the grouting water-blocking material can withstand a certain pressure within mining-induced fissures, effectively preventing the fissures from reopening due to external pressure, thereby ensuring the sealing effect and long-term stability of the grouting.
[0040] (3) Micro-expansion rate
[0041] The grouting water-blocking material also has a suitable micro-expansion rate, ranging from 0.02 to 0.05%. This micro-expansion property enables the grouting water-blocking material to better bond with surrounding rock or soil during the solidification process, filling the tiny gaps in the cracks, further improving the grouting effect and the durability of the plugging, ensuring long-term and effective plugging of the cracks.
[0042] (4) Permeability coefficient
[0043] The lower the permeability coefficient, the better the water blocking performance of the grouting water blocking material. The grouting water blocking material of the present invention has excellent water blocking performance, and the permeability coefficient range is 5.9×10 -12 ~7.1×10 -12 m / s (test conditions: 24 hours under 0.5MPa water pressure). This value is much lower than that of traditional cement slurry (usually 10 -10 ~10 -9 m / s), demonstrating that the grouting water-blocking material effectively blocks groundwater infiltration. The low permeability coefficient stems from the synergistic effect of coal gasification ash and bentonite: The refined coal gasification ash forms a dense gelled network, while the bentonite expands upon contact with water, filling micropores. Together, they create a low-permeability barrier, ensuring long-term water blocking in mining-induced fractures. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0045] Figure 1 This is a comparison chart of the water leakage before and after grouting in Application Example 1. DETAILED DESCRIPTION
[0046] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0047] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.
[0048] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.
[0049] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.
[0050] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.
[0051] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.
[0052] In the following examples, comparative examples and test examples of the present invention, if room temperature is mentioned, it specifically refers to 20-30°C.
[0053] The “parts” referred to in the following embodiments, comparative examples and test examples of the present invention specifically refer to “parts by mass”.
[0054] Unless otherwise specified, all raw materials used in the following examples, comparative examples, and test examples of the present invention are common commercially available products. Among them, the cement is P·O 42.5 cement, the water reducer is PC-101 polycarboxylic acid high-efficiency water reducer, the fly ash is first-grade fly ash, the bentonite is sodium-based bentonite, and the coal gasification ash residue is coal gasification ash residue fine residue (particles carried out by synthesis gas during the coal gasification process and separated in the subsequent gas purification process), with a particle size of ≤0.15 mm.
[0055] Example 1
[0056] A method for preparing mining fissure grouting water-blocking material using coal gasification ash, comprising the following steps:
[0057] (1) Drying treatment of coal gasification ash
[0058] The coal gasification ash (fine slag) was dried for 4 hours at a temperature of 105° C. In this way, the final moisture content of the coal gasification ash was strictly controlled to be ≤1%.
[0059] (2) Grinding and refining of coal gasification ash
[0060] The dried coal gasification ash is ground in a ball mill. During the grinding process, the particle size of the ash is precisely controlled to reach a standard of ≤45μm, while ensuring that its specific surface area can reach 400m 2 / kg.
[0061] (3) Weighing of raw materials
[0062] Weigh 42 parts of dried and refined coal gasification ash particles, 11 parts of fly ash, 7 parts of cement, 2.5 parts of bentonite, 0.5 parts of water reducer and 37 parts of water (tap water, the same below).
[0063] (4) Raw material mixing
[0064] The coal gasification ash particles, fly ash, cement and bentonite were mixed and stirred using a stirring device (rotating speed of 300 r / min) for 3 minutes.
[0065] After the dry materials are evenly mixed, add a water reducer. This improves the rheological properties of the grouting water-blocking material, enhancing its fluidity and workability. After adding the water reducer, continue stirring with a stirring device (at a speed of 300 rpm) for 1 minute to ensure the water reducer is evenly dispersed throughout the mixture.
[0066] Finally, slowly add water to the mixture. This process needs to be done slowly to avoid uneven mixing caused by adding water too quickly. After adding water, continue stirring for 5 minutes (at a speed of 300 rpm) to allow the material to fully absorb the water, ultimately obtaining a uniform slurry. This uniform slurry is the prepared water-blocking material for mining-induced fissure grouting.
[0067] Example 2
[0068] The same as Example 1, except that in step (3), 40 parts of dried and refined coal gasification ash particles, 10 parts of fly ash, 6 parts of cement, 2.5 parts of bentonite, 0.5 parts of water reducer and 41 parts of water are weighed.
[0069] Example 3
[0070] The same as Example 1, except that in step (3), 45 parts of dried and refined coal gasification ash particles, 12 parts of fly ash, 7 parts of cement, 2 parts of bentonite, 0.6 parts of water reducer and 33.4 parts of water are weighed.
[0071] Comparative Example 1
[0072] The same as Example 1, except that in step (3), 11 parts of fly ash, 7 parts of cement, 2.5 parts of bentonite, 0.5 parts of water reducer and 12.3 parts of water are weighed, and the use of coal gasification ash particles is omitted in step (4).
[0073] Comparative Example 2
[0074] The same method as Example 1 is different in that, in step (3), 42 parts of dried and refined coal gasification ash particles, 11 parts of fly ash, 7 parts of cement, 0.5 parts of water reducer, and 35.5 parts of water are weighed. Bentonite is omitted in step (4).
[0075] Comparative Example 3
[0076] The same as Example 1, except that in step (3), 42 parts of dried and refined coal gasification ash particles, 7 parts of cement, 2.5 parts of bentonite, 0.5 parts of water reducer, and 30.5 parts of water were weighed. In step (4), the use of fly ash was omitted.
[0077] Comparative Example 4
[0078] A method for preparing mining fissure grouting water-blocking material using coal gasification ash, comprising the following steps:
[0079] (1) Drying treatment of coal gasification ash
[0080] The coal gasification ash (fine slag) is dried at 105°C for 4 hours. In this way, the final moisture content of the coal gasification ash is strictly controlled to be ≤1%. The particle size of the dried coal gasification ash is ≤0.15mm and the specific surface area is about 200m 2 / kg.
[0081] (2) Weighing of raw materials
[0082] Weigh 42 parts of dried coal gasification ash particles, 11 parts of fly ash, 7 parts of cement, 2.5 parts of bentonite, 0.5 parts of water reducer and 37 parts of water.
[0083] (3) Raw material mixing
[0084] The coal gasification ash particles, fly ash, cement and bentonite were mixed and stirred using a stirring device (rotating speed of 300 r / min) for 3 minutes.
[0085] After the dry materials are evenly mixed, add a water reducer. This improves the rheological properties of the grouting water-blocking material, enhancing its fluidity and workability. After adding the water reducer, continue stirring with a stirring device (at a speed of 300 rpm) for 1 minute to ensure the water reducer is evenly dispersed throughout the mixture.
[0086] Finally, slowly add water to the mixture. This process needs to be done slowly to avoid uneven mixing caused by adding water too quickly. After adding water, continue stirring for 5 minutes (at a speed of 300 rpm) to allow the material to fully absorb the water, ultimately obtaining a uniform slurry. This uniform slurry is the prepared water-blocking material for mining-induced fissure grouting.
[0087] Test Example 1
[0088] The fluidity, setting time, compressive strength, micro-expansion rate and permeability coefficient of the grouting water-blocking materials prepared in each embodiment and comparative example were tested. The results are shown in Table 1.
[0089] Fluidity test: Using the truncated cone mold method, the evenly stirred grouting water-blocking material slurry is placed into a truncated cone mold with an upper diameter of 70mm, a lower diameter of 100mm, and a height of 60mm. The mold is placed on a horizontal glass plate and tamped evenly 25 times with a tamping rod. Then, the truncated cone mold is lifted vertically. The time it takes for the slurry to stop flowing on the glass plate is taken as the fluidity.
[0090] Setting time test: Use a Vicat apparatus to load the prepared grouting water-blocking material slurry into a truncated cone mold with a height of 40 mm, an upper diameter of 65 mm, and a lower diameter of 75 mm. Start timing from the time water is added and stirred. The time when the slurry causes the test needle of the Vicat apparatus to sink into the slurry and be 6 mm ± 1 mm away from the bottom plate is the initial setting time. The time when the test needle sinks into the slurry no more than 0.5 mm is the final setting time.
[0091] Compressive strength test: 70mm x 70mm x 70mm specimens of grouting water-blocking material were prepared and cured under standard curing conditions to the specified age (7 days, 28 days). After the curing period expired, pressure was applied to the specimen using a pressure testing machine until failure. The load value at failure was recorded, and the compressive strength was calculated based on the specimen size.
[0092] Micro-expansion rate test: The test is carried out using a length ratio meter. Grouting water-blocking material slurry is placed in a special 100mm×100mm×100mm test mold. The test piece is cured under standard curing conditions. The length of the test piece at different times is measured and the micro-expansion rate is calculated by comparing it with the initial length.
[0093] Permeability coefficient test: The grouting water-blocking material is made into a standard cylindrical specimen with a diameter of 50mm and a height of 50mm. Using a professional permeameter, a water pressure of 0.5MPa is applied to the specimen and maintained for 24 hours. The amount of water that penetrates the specimen is measured according to the Darcy's law formula. Calculate the permeability coefficient (where k is the permeability coefficient, Q is the amount of water passing through the specimen per unit time, L is the specimen thickness, A is the specimen cross-sectional area, H is the applied head, and t is time). The lower the permeability coefficient, the better the water-blocking performance of the grouting water-blocking material.
[0094] Table 1
[0095]
[0096]
[0097] As can be seen from Table 1, the grouting water-blocking materials prepared in Examples 1-3 have suitable fluidity and setting time, as well as good compressive strength, large micro-expansion rate and small permeability coefficient.
[0098] The fluidity of Comparative Example 1, which lacks coal gasification ash, is 25 seconds, and its fluidity is poor, which is not conducive to diffusion in the cracks; the initial setting time is 1.5 hours, and the final setting time is 4 hours. The setting time is too short, resulting in the material being unable to fully fill the cracks before it solidifies during the grouting process, affecting the sealing effect; the 7-day compressive strength is 8 MPa, and the 28-day compressive strength is 12 MPa, which is much lower than that of Examples 1-3. It cannot effectively withstand the pressure of mining cracks and easily causes the cracks to reopen; there is almost no expansion phenomenon, and the tiny gaps in the cracks cannot be filled, resulting in poor grouting effect; the permeability coefficient is relatively high, and the water resistance is poor.
[0099] The fluidity of comparative example 2 lacking bentonite is 15 seconds, the fluidity is too large, the slurry stability is poor, and segregation is prone to occur; the initial setting time is 2.2 hours, and the final setting time is 6 hours. Although the setting time is basically normal, due to the lack of the water retention effect of bentonite, water is lost quickly during the setting process, affecting the full progress of the hydration reaction; the 7-day compressive strength is 12 MPa, and the 28-day compressive strength is 20 MPa. The compressive strength is lower than that of Examples 1-3, and cannot meet the requirements of long-term sealing of mining cracks; the micro-expansion rate is 0.010%, the expansion effect is poor, and the bonding with the surrounding medium is not tight; the permeability coefficient is also higher than that of Examples 1-3, and the missing components have an adverse effect on the water-blocking performance.
[0100] The fluidity of comparative example 3 lacking fly ash is 16 seconds, which is not ideal, and the resistance is large during stirring and pumping; the initial setting time is 2.3 hours, and the final setting time is 6.5 hours, which are basically normal. However, due to the lack of the ball bearing effect and secondary reaction of fly ash, the material performance improvement is affected; the 7-day compressive strength is 13 MPa, and the 28-day compressive strength is 22 MPa, which is lower than that of Examples 1-3, affecting the long-term stability of the grouting water-blocking material; the micro-expansion rate is 0.020%, which is slightly lower than that of Examples 1-3, and the filling effect of tiny gaps in cracks is slightly worse; the permeability coefficient is also higher than that of Examples 1-3, and the missing components have an adverse effect on the water-blocking performance.
[0101] The fluidity of comparative example 4 in which the coal gasification ash was not ball-milled was 30 seconds, which was not ideal, and the resistance was large during stirring and pumping; the initial setting time was 3.0 hours, and the final setting time was 8.0 hours, which were basically normal, but the lack of the ball bearing effect and secondary reaction of the fly ash affected the improvement of material performance; the 7-day compressive strength was 12 MPa, and the 28-day compressive strength was 20 MPa, which was lower than that of Examples 1-3, affecting the long-term stability of the grouting water-blocking material; the micro-expansion rate was 0.020%, which was slightly lower than that of Examples 1-3, and the filling effect of tiny gaps in cracks was slightly worse; the permeability coefficient was also higher than that of Examples 1-3, and the larger particle size of the coal gasification ash had an adverse effect on the water-blocking performance. The excessively large particle size resulted in uneven mixing of the coal gasification ash with other raw materials, low reaction activity, insufficient strength, and poor fluidity, which affected the comprehensive performance of the grouting water-blocking material.
[0102] Comparison of the above examples and comparative examples demonstrates the synergistic effect of the components of the present invention in addressing the technical challenges of grouting and water-blocking in mining-induced fissures. Coal gasification ash, as the primary raw material, provides the cementitious foundation, while bentonite improves slurry viscosity and water retention, stabilizing the reaction process, and fly ash enhances fluidity and strength. These components work together to achieve a balanced performance profile for the grouting and water-blocking material, including fluidity, setting time, compressive strength, micro-expansion rate, and permeability. This effectively seals and reinforces mining-induced fissures, resolving challenges encountered in the prior art.
[0103] Application Example 1
[0104] A coal mine used the grouting water-blocking material prepared in Example 1 of the present invention to treat mining fissures. The specific application process is as follows:
[0105] 1. Site Survey
[0106] Before applying the grouting water-blocking material, a detailed on-site survey was conducted. Professional technicians conducted a comprehensive inspection of the mining area, carefully determining the distribution of cracks and the extent of water seepage. This on-site survey enabled the technicians to accurately determine key information such as the specific location, direction, width, and severity of the mining cracks, providing a crucial basis for subsequent drilling layout and grouting process design.
[0107] 2. Drilling arrangement
[0108] Grouting holes are rationally arranged based on the fissure orientation information obtained from the on-site survey. During the arrangement process, the hole spacing is strictly controlled between 3 and 5 meters (4 meters is selected in this application example). This hole spacing setting is based on scientific calculations and practical experience. It ensures that the grouting water-blocking material can effectively cover the entire fissure area after injection, while avoiding the inability to fully fill some fissures due to excessive hole spacing, or the waste of resources and increased construction difficulty due to too small hole spacing.
[0109] 3. Grouting process
[0110] (1) Grouting method
[0111] Grouting is performed using a segmented grouting method. The grouting process is divided into multiple stages, with each stage targeting different crack areas or depths. Segmented grouting allows for more precise control of grouting pressure and volume, ensuring that the grouting water-blocking material is evenly filled into the cracks, improving grouting effectiveness.
[0112] (2) Grouting pressure
[0113] The grouting pressure is controlled between 2 and 3 MPa (2.5 MPa is selected in this application example). Appropriate grouting pressure is one of the key factors in ensuring grouting effectiveness. If the grouting pressure is too low, the grouting water-blocking material may not fully fill the cracks, resulting in poor sealing effect. If the grouting pressure is too high, it may damage the surrounding rock structure and affect the safe production of the coal mine.
[0114] (3) Grouting time
[0115] Each grouting period is set to 15 to 20 minutes (18 minutes in this application example). During this time, the grouting water-blocking material can fully fill the corresponding crack area under appropriate pressure. Strictly controlling the grouting time ensures the stability and consistency of the grouting process, avoiding the impact of grouting quality due to grouting time that is too long or too short.
[0116] Effect evaluation
[0117] 1. Improvement of water leakage
[0118] After grouting treatment, the water leakage in the mining crack area was monitored and evaluated. Figure 1 As shown, the water leakage after treatment was reduced by more than 95%, which shows that the grouting water-blocking material of the present invention can effectively block mining cracks, significantly reduce groundwater leakage, and improve the waterproof performance of coal mining areas.
[0119] 2. Cost-Benefit Analysis
[0120] Compared to traditional cement slurry, the grouting water-blocking material of the present invention offers significant cost advantages. Calculations show that the cost of the grouting water-blocking material is 35% lower than that of traditional cement slurry. This not only reduces the cost of treating mining-induced fissures for coal mining enterprises, but also improves their economic benefits.
[0121] 3. Long-term stable effect
[0122] A review was conducted three months after the grouting treatment. The results showed that the grouting water-blocking material maintained its stable water-blocking effect. This demonstrates that the grouting water-blocking material of the present invention has excellent long-term performance, effectively sealing mining-induced fissures over an extended period of time, and providing reliable protection for safe coal mine production.
[0123] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.
Claims
1. A mining fissure grouting water-blocking material, characterized in that: The raw materials include the following components by mass: 37-47 parts of coal gasification ash, 9-13 parts of fly ash, 5-8 parts of cement, 2-3 parts of bentonite, 0.3-0.7 parts of water reducer and 30-46 parts of water.
2. The mining fissure grouting water-blocking material according to claim 1, characterized in that: The moisture content of the coal gasification ash is ≤1%; And / or, the particle size of the coal gasification ash is ≤45 μm, and the specific surface area is ≥400 m 2 / kg.
3. A method for preparing mining fissure grouting water-blocking material using coal gasification ash, characterized in that: The following steps are involved: Weigh each raw material according to the raw material composition defined in claim 1; The raw materials are mixed to obtain the mining fissure grouting water-blocking material.
4. The method according to claim 3, wherein The method also includes drying and ball milling the coal gasification ash before weighing the raw materials.
5. The method according to claim 4, wherein The drying specifically involves drying the coal gasification ash to a moisture content of ≤1%.
6. The method according to claim 4, wherein The ball milling is to ball mill the coal gasification ash to a particle size of ≤45 μm and a specific surface area of ≥400 m 2 / kg.
7. The method according to claim 3, wherein The mixing of the raw materials comprises: First, coal gasification ash, fly ash, cement and bentonite are mixed evenly to obtain a mixed dry material; then a water reducer is added and mixed evenly to obtain a mixed material; finally, water is added and mixed evenly to obtain the mining fissure grouting water-blocking material.
8. The method according to claim 7, wherein When the coal gasification ash, fly ash, cement and bentonite are mixed evenly, the stirring time is not less than 3 minutes; And / or, when the water reducing agent is added and mixed evenly, the stirring time is not less than 1 minute; And / or, when adding water and mixing evenly, the stirring time is not less than 5 minutes.
9. Use of the mining-induced fissure grouting water-blocking material according to claim 1 in filling and reinforcing mining-induced fissures.
10. The use according to claim 9, characterized in that The filling reinforcement is achieved by grouting, and the parameters of the grouting include: the grouting hole spacing is 3 to 5 meters, the grouting pressure is 2 to 3 MPa, and the grouting time per hole is 15 to 20 minutes.