Coal mine paste filling material and preparation method thereof

Abstract

The application discloses a coal mine paste filling material and a preparation method thereof, and relates to the technical field of coal mine filling. The coal mine paste filling material comprises the following raw material components in mass fractions: 20-25 parts of slag, 12-15 parts of cinder, 8-10 parts of carbide slag, 8-10 parts of steel slag, 5-6 parts of desulfurization gypsum, 5-6 parts of polyaspartic acid, 8-12 parts of aluminum phosphate, 5 parts of sodium hydroxide and 20-45 parts of water. The application fully utilizes industrial waste slag as the main raw material, realizes the resource utilization of the industrial waste slag in the preparation process, and significantly improves the performance of the coal mine paste filling material through reasonable modification treatment and composite material design. Meanwhile, the preparation process is environment-friendly and economically feasible, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine filling, in particular to a coal mine paste filling material and a preparation method thereof. Background Art

[0002] With the continuous development of coal resources, traditional coal mining methods face numerous challenges, such as surface subsidence, water resource depletion, and environmental pollution. To address these issues, coal mine backfill mining technology has emerged. This technology injects specialized backfill materials into the goaf to support the roof, reduce ground subsidence, and prevent damage to groundwater systems. In recent years, with increasing environmental awareness and technological advancements, the research and application of backfill materials has received increasing attention.

[0003] Early filling materials commonly used were primarily slurries composed of cement, sand, and gravel. While these materials offer high strength and durability, their production is energy-intensive, generates significant carbon emissions, and is relatively expensive. Furthermore, cement-based materials are prone to segregation during transportation and pumping, resulting in uneven filling. Using industrial waste residues, such as fly ash, to prepare filling materials has become an environmentally friendly option. However, due to its inherently low reactivity, fly ash alone struggles to achieve ideal mechanical properties. Furthermore, excessive fly ash addition can reduce the fluidity and stability of the paste.

[0004] In view of the problems existing in traditional filling materials, researchers have begun to explore new filling material systems. These materials usually use natural minerals or industrial by-products as the main ingredients, and combine advanced modification technology and optimized formula design to make up for their respective defects, thereby achieving higher overall performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a coal mine paste filling material and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a coal mine paste filling material, which comprises the following raw material components in parts by mass:

[0008] 20-25 parts of slag, 12-15 parts of furnace slag, 8-10 parts of carbide slag, 8-10 parts of steel slag, 5-6 parts of desulfurized gypsum, 5-6 parts of polyaspartic acid, 8-12 parts of aluminum phosphate, 5-7 parts of sodium hydroxide and 20-45 parts of water.

[0009] The filling material with the raw material ratio of the present invention can achieve higher mechanical properties and durability requirements while ensuring good construction performance.

[0010] The application further provides a preparation method of the coal mine paste filling material.

[0011] (1) soaking slag, cinder and carbide slag in acetic acid solution to obtain modified silicate minerals; calcining steel slag at 800-1000 ℃ to obtain calcined steel slag;

[0012] (2) mixing the modified silicate minerals and the calcined steel slag, then adding a mixture of polycarbonate and polyacrylamide, and performing a blending reaction at 150-180 ℃, and then cooling to room temperature;

[0013] (3) adding a polyaspartic acid aqueous solution to the reaction system of step (2); wherein the polyaspartic acid aqueous solution is obtained by dissolving the polyaspartic acid in part of the water of the raw material ratio;

[0014] (4) adding desulfurized gypsum and aluminum phosphate to the system of step (3), and adding sodium hydroxide and the rest of the water of the raw material ratio, and stirring to obtain the coal mine paste filling material.

[0015] As a further preferred embodiment of the application, the mass ratio of the polycarbonate and the polyacrylamide is 1-2:2-3.

[0016] As a further preferred embodiment of the application, the blending reaction time is 5-8 min.

[0017] As a further preferred embodiment of the application, the temperature is lowered to room temperature at a cooling rate of 8-12 ℃ / min in step (2).

[0018] As a further preferred embodiment of the application, the total mass of the polycarbonate and the polyacrylamide is 20-25% of the total mass of the modified silicate minerals and the steel slag.

[0019] The application further provides an application of the coal mine paste filling material or the coal mine paste filling material prepared by the preparation method in backfilling of a coal mine goaf.

[0020] The preparation process of the application fully utilizes industrial waste slag (such as slag, cinder, carbide slag and steel slag) as the main raw material, realizes the resource utilization of waste, reduces environmental pollution and environmental burden, and fully plays the advantages of each component by treating and mixing different sources of waste slag (slag, cinder, carbide slag and steel slag), thereby improving the overall performance of the material.

[0021] The application soaks slag, cinder and carbide slag in acetic acid solution to obtain modified silicate minerals, enhances the activity and reactivity thereof, and facilitates the subsequent reaction.

[0022] The application adds polycarbonate and polyacrylamide for blending reaction to form a composite material with excellent mechanical properties and rheological properties, which is suitable for coal mine paste filling requirements.

[0023] The raw material component polyaspartic acid is a high-efficiency dispersant and chelating agent, which can effectively improve the fluidity and stability of the material, and enhance the environmental friendliness thereof; desulfurized gypsum can further provide good cementing performance, and aluminum phosphate can enhance the durability and compressive strength of the material, so that the filling material has better comprehensive performance.

[0024] In the whole preparation process of the filling material, the temperature is controlled within a reasonable range, the high energy consumption is avoided, the production cost is reduced, and the environmentally friendly reagents such as acetic acid solution and polyaspartic acid are used to reduce the emission of harmful substances, which meets the green environmental protection requirements.

[0025] The application has the following technical effects:

[0026] 1. The coal mine paste filling material has excellent flow characteristics, can realize smooth pumping without adding additional admixtures, can maintain good cohesion under the premise of ensuring sufficient fluidity, can avoid the occurrence of delamination, greatly facilitates the construction operation in the complex environment of the goaf, and improves the work efficiency.

[0027] 2. The filling material exhibits high compressive strength in the early stage, can effectively prevent crack propagation even when subjected to large load or deformation, thereby ensuring the safety and durability of the structure, and exhibits excellent bearing capacity.

[0028] 3. The filling material has long-term stability and does not show obvious signs of deterioration when exposed to natural environment for a long time.

[0029] 4. The application adheres to the green development concept, selects natural minerals as the main raw material, strictly controls the emission of harmful substances, meets the environmental protection requirements, and is conducive to promoting resource recycling and sustainable development.

[0030] 5. The present application realizes the maximization of economic and social benefits while ensuring the safety of mine production, and is a filling material solution with great potential. DETAILED DESCRIPTION

[0031] The detailed description set forth below is intended as a description of various example embodiments of the application and is not intended to represent the only embodiments in which the application can be practiced. It is to be understood that the description is not to be limited to the specific details of the described methods, materials, and procedures.

[0032] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. In addition, where particular ranges of values are given, understand that each intervening value, to the upper or lower limit of the ranges is also specifically included. Each smaller range that falls within the broader ranges is also specifically included. The upper and lower limits of these smaller ranges can independently be included or excluded in the range, and each range is inclusive of its end points. Obvious modifications which can be substantively, as well as

[0033] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0034] Various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application in any way.

[0035] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional elements or steps. EMBODIMENT

[0036] The present embodiment provides a coal mine filling material, and the mass ratio of raw materials is as follows:

[0037] 23 parts of slag, 14 parts of slag, 8 parts of calcium carbide slag, 9 parts of steel slag, 5 parts of desulfurization gypsum, 6 parts of polyaspartic acid, 10 parts of aluminum phosphate, 5 parts of sodium hydroxide, and 35 parts of water.

[0038] The preparation steps are as follows:

[0039] (1) The slag, the cinder and the carbide slag are soaked in an acetic acid solution with a mass concentration of 30% for 40 minutes to obtain modified silicate minerals; the steel slag is calcined at 850°C to obtain calcined steel slag;

[0040] (2) The modified silicate minerals and the calcined steel slag are mixed, and then a mixture of polycarbonate and polyacrylamide with a mass ratio of 1:2 is added, and a blending reaction is performed at 180°C for 5 minutes, and then cooled to room temperature at a cooling rate of 10°C / min; wherein the total mass of polycarbonate and polyacrylamide is 20% of the total mass of modified silicate minerals and calcined steel slag.

[0041] (3) The polyaspartic acid aqueous solution is added to the reaction system of step (2) and stirred; wherein the polyaspartic acid aqueous solution is obtained by dissolving polyaspartic acid in half of the mass ratio of water;

[0042] (4) Desulfurization gypsum and aluminum phosphate are added to the system of step (3), and sodium hydroxide and the remaining mass ratio of water are added, and stirred to obtain a coal mine paste filling material. Embodiment

[0043] The embodiment provides a coal mine filling material, and the mass ratio of raw materials is as follows:

[0044] The slag is 20 parts, the cinder is 15 parts, the carbide slag is 8 parts, the steel slag is 10 parts, the desulfurization gypsum is 5 parts, the polyaspartic acid is 5 parts, the aluminum phosphate is 10 parts, the sodium hydroxide is 6 parts, and the water is 25 parts.

[0045] The preparation steps are as follows:

[0046] (1) The slag, the cinder and the carbide slag are soaked in an acetic acid solution with a mass concentration of 35% for 45 minutes to obtain modified silicate minerals; the steel slag is calcined at 1000°C to obtain calcined steel slag;

[0047] (2) The modified silicate minerals and the calcined steel slag are mixed, and then a mixture of polycarbonate and polyacrylamide with a mass ratio of 2:3 is added, and a blending reaction is performed at 150°C for 6 minutes, and then cooled to room temperature at a cooling rate of 8°C / min; wherein the total mass of polycarbonate and polyacrylamide is 25% of the total mass of modified silicate minerals and calcined steel slag.

[0048] (3) The polyaspartic acid aqueous solution is added to the reaction system of step (2) and stirred; wherein the polyaspartic acid aqueous solution is obtained by dissolving polyaspartic acid in half of the mass ratio of water;

[0049] (4) Desulfurization gypsum and aluminum phosphate are added to the system of step (3), and sodium hydroxide and the remaining mass ratio of water are added, and stirred to obtain a coal mine paste filling material. Embodiment

[0050] The embodiment provides a coal mine filling material, and raw material mass fraction ratio is as follows:

[0051] Slag 22 parts, cinder 12 parts, carbide slag 8 parts, steel slag 10 parts, desulfurization gypsum 5 parts, polyaspartic acid 5 parts, aluminum phosphate 12 parts, sodium hydroxide 7 parts and water 35 parts.

[0052] The preparation steps are as follows:

[0053] (1) the slag, cinder and carbide slag are soaked in an acetic acid solution with a mass concentration of 28% for 30 min to obtain modified silicate minerals; the steel slag is calcined at 800 DEG C to obtain calcined steel slag;

[0054] (2) the modified silicate minerals and the calcined steel slag are mixed, then a mixture with a mass ratio of polycarbonate and polyacrylamide of 1:3 is added, and a blending reaction is carried out at 180 DEG C for 5 min, and then cooled to room temperature at a cooling rate of 8 DEG C / min; wherein the total mass of polycarbonate and polyacrylamide is 22% of the total mass of modified silicate minerals and calcined steel slag.

[0055] (3) the polyaspartic acid aqueous solution is added to the reaction system of step (2) and stirred; wherein the polyaspartic acid aqueous solution is obtained by dissolving polyaspartic acid in half of the mass fraction of water;

[0056] (4) the desulfurization gypsum and aluminum phosphate are added to the system of step (3), and the sodium hydroxide and the remaining mass fraction of water are added, and stirred to obtain a coal mine paste filling material. Embodiment

[0057] The embodiment provides a coal mine filling material, and raw material mass fraction ratio is as follows:

[0058] Slag 25 parts, cinder 12 parts, carbide slag 8 parts, steel slag 8 parts, desulfurization gypsum 6 parts, polyaspartic acid 5 parts, aluminum phosphate 10 parts, sodium hydroxide 6 parts and water 40 parts.

[0059] The preparation steps are as follows:

[0060] (1) the slag, cinder and carbide slag are soaked in an acetic acid solution with a mass concentration of 30% for 35 min to obtain modified silicate minerals; the steel slag is calcined at 900 DEG C to obtain calcined steel slag;

[0061] (2) mixing the modified silicate mineral with the calcined steel slag, then adding a mixture of polycarbonate and polyacrylamide with a mass ratio of 2:3, and carrying out a blending reaction at 150°C for 5 min, and then cooling to room temperature at a cooling rate of 8°C / min; wherein the total mass of polycarbonate and polyacrylamide is 25% of the total mass of the modified silicate mineral and the calcined steel slag.

[0062] (3) adding a polyaspartic acid aqueous solution to the reaction system of step (2) and stirring; wherein the polyaspartic acid aqueous solution is obtained by dissolving the polyaspartic acid in half of the mass ratio of water;

[0063] (4) adding desulfurized gypsum and aluminum phosphate to the system of step (3), and adding sodium hydroxide and the remaining mass ratio of water, and stirring to obtain a coal mine paste filling material.

[0064] The difference between Example 1 and Example 2 is that the polyacrylamide is replaced by an equal mass of polycarbonate.

[0065] The difference between Example 1 and Example 3 is that the mixing reaction process of step (2) is not performed.

[0066] (1) soaking the slag, the cinder and the carbide slag in an acetic acid solution with a mass concentration of 30% for 40 min to obtain a modified silicate mineral, and calcining the steel slag at 850°C to obtain a calcined steel slag;

[0067] (2) adding a polyaspartic acid aqueous solution to the reaction system of step (1) and stirring; wherein the polyaspartic acid aqueous solution is obtained by dissolving the polyaspartic acid in half of the mass ratio of water;

[0068] (3) adding desulfurized gypsum and aluminum phosphate to the system of step (2), and adding sodium hydroxide and the remaining mass ratio of water, and stirring to obtain a coal mine paste filling material.

[0069] The difference between Example 1 and Example 4 is that the polyaspartic acid is replaced by an equal mass of polyacrylic acid.

[0070] 1. Flowability test

[0071] Referring to the “GB / T 50080-2016 Standard for Testing Methods of Properties of Ordinary Concrete Mixture”, the flowability of the paste is evaluated by measuring the settlement depth of the paste under a standard cone according to the cone penetration method.

[0072] The cone penetration results of the paste filling materials prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Table 1:

[0073] Table 1

[0074] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Taper (mm) 35 37 36 35 33 32 33

[0075] 2. Density test

[0076] According to the GB / T 50123-2019 Standard for Geotechnical Test Methods, the wet density and dry density of the filling material were measured by the bulk density method to understand the mass distribution in unit volume.

[0077] The wet density and dry density data of the paste filling materials prepared in Examples 1-4 and Comparative Examples 1-3 are shown in Table 2.

[0078] Table 2

[0079] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Wet density (g / cm3) 1.81 1.86 1.79 1.85 1.70 1.63 1.66 Dry density (g / cm3) 1.52 1.55 1.53 1.56 1.41 1.38 1.44

[0080] 3. Compressive strength test

[0081] According to the GB / T 50081-2019 Standard Test Methods for Physical and Mechanical Properties of Concrete, standard specimens with a size of 100 mm x 100 mm x 100 mm were prepared, and axial load was applied on the press until failure, the maximum bearing capacity was recorded, and the compressive strength value was calculated.

[0082] The compressive strength results of the paste filling materials prepared in Examples 1-4 and Comparative Examples 1-3 under standard curing at different ages are shown in Table 3.

[0083] Table 3

[0084] 7d compressive strength (MPa) 28d compressive strength (MPa) Example 1 5.9 10.2 Example 2 5.8 10.8 Example 3 5.6 9.8 Example 4 5.8 10.7 Comparative Example 1 3.5 5.9 Comparative Example 2 3.2 6.2 Comparative Example 3 3.3 5.7

[0085] 4. Elastic modulus test

[0086] According to the GB / T 50081-2019 Standard Test Methods for Physical and Mechanical Properties of Concrete, uniaxial compression experiments were performed to obtain the elastic modulus of each material after 7 days of curing, and the results are shown in Table 4.

[0087] Table 4

[0088] 4. Acid and alkali corrosion resistance test

[0089] According to the GB / T 50082-2009 Standard Test Methods for Long-term Performance and Durability of Ordinary Concrete, the paste filling material samples were immersed in a sulfuric acid solution with pH = 2 or a sodium hydroxide solution with pH = 12, respectively. After 7 days of immersion, they were taken out, washed and dried, and the mass change and appearance damage degree before and after immersion were compared to evaluate their corrosion resistance. The results are shown in Table 5.

[0090] Table 5

[0091] Mass loss rate (%) after immersion in sulfuric acid solution of pH = 2 for 7d Swelling and disintegration after immersion in sodium hydroxide solution of pH = 12 for 7d Example 1 1.56 No significant swelling or disintegration Example 2 1.53 No significant swelling or disintegration Example 3 1.49 No significant swelling or disintegration Example 4 1.51 No significant swelling or disintegration Comparative Example 1 2.68 No significant swelling or disintegration Comparative Example 2 2.45 No significant swelling or disintegration Comparative Example 3 2.52 No significant swelling or disintegration

[0092] The mass loss rate of the coal mine filling material of the application is less than 2% after being soaked in a sulfuric acid solution with pH=2 for 7 days, and no obvious swelling or disintegration phenomenon is observed after being soaked in a sodium hydroxide solution with pH=12 for 7 days.

[0093] 5. Leaching toxicity test:

[0094] According to the standard of "Solid Waste Leaching Toxicity Leaching Method", the concentration of harmful substances released by the paste filling material in the leaching process is determined to evaluate the potential pollution risk to the surrounding water body. The results show that the leaching concentration of heavy metal ions of the filling materials of each example and the comparative example is lower than the limit value specified in GB 18598-2019, and no organic pollutants are detected.

[0095] 6. Accelerated aging test:

[0096] According to the standard of "GB / T 50082-2009 General Concrete Long-term Performance and Durability Test Method", after 1000 freeze-thaw cycles under simulated extreme climate conditions (-20℃ to +60℃ cycle), the compressive strength retention rate of each filling material is shown in Table 6.

[0097] Table 6

[0098] The preparation process of the application not only realizes the resource utilization of industrial waste residues, but also significantly improves the performance of coal mine paste filling materials through reasonable modification treatment and composite material design. At the same time, the preparation process pays attention to environmental friendliness and economic feasibility, and has wide application prospect.

[0099] The above-described examples only describe the preferred modes of the application and do not limit the scope of the application. Without departing from the design spirit of the application, various modifications and improvements to the technical solutions of the application made by those skilled in the art shall fall within the protection scope determined by the claims of the application.

Claims

1. A coal mine paste filling material, characterized in that: Calculated by mass, it includes the following raw material components: 20-25 parts of slag, 12-15 parts of furnace slag, 8-10 parts of carbide slag, 8-10 parts of steel slag, 5-6 parts of desulfurized gypsum, 5-6 parts of polyaspartic acid, 8-12 parts of aluminum phosphate, 5-7 parts of sodium hydroxide and 20-45 parts of water; The method for preparing the coal mine paste filling material comprises the following steps: (1) Soaking slag, furnace slag and carbide slag in an acetic acid solution to obtain modified silicate minerals; calcining steel slag at 800-1000°C to obtain calcined steel slag; (2) Blending reaction: mixing the modified silicate mineral with the calcined steel slag, then adding a mixture of polycarbonate and polyacrylamide, performing a blending reaction at 150-180° C., and then cooling to room temperature; (3) adding a polyaspartic acid aqueous solution to the reaction system of step (2); wherein the polyaspartic acid aqueous solution is obtained by dissolving the polyaspartic acid in water of a portion of the raw material ratio; (4) Add desulfurized gypsum and aluminum phosphate to the system of step (3), and add sodium hydroxide and water in the remaining raw material ratio, and stir to obtain the coal mine paste filling material.

2. The coal mine paste filling material according to claim 1, characterized in that: The mass ratio of the polycarbonate to the polyacrylamide is 1-2:2-3.

3. The coal mine paste filling material according to claim 1, characterized in that: The blending reaction time is 5-8 minutes.

4. The coal mine paste filling material according to claim 2, characterized in that: In step (2), the temperature is lowered to room temperature at a cooling rate of 8-12°C / min.

5. The coal mine paste filling material according to claim 1, characterized in that: The total mass of the polycarbonate and polyacrylamide is 20-25% of the total mass of the modified silicate mineral and the steel slag.

6. Use of the coal mine paste filling material according to any one of claims 1 to 5 in backfilling coal mine goaf.