Cementing material for mine filling and preparation method thereof

Abstract

The invention discloses a cementing material for mine filling and a preparation method thereof, and relates to the technical field of building materials. Comprising the following steps: jointly grinding and activating fly ash, sodium sulfate and calcium hydroxide, and calcining in a roasting furnace to obtain deeply activated fly ash; the magnesium slag powder, calcium sulfate whiskers and wollastonite fibers are subjected to shear mixing, and fiber-reinforced magnesium slag is obtained; and mixing the deeply activated fly ash, the fiber reinforced magnesium slag, cement and the composite exciting agent, and subpackaging by adopting a full-automatic vacuum packaging machine after mixing is completed, so as to obtain the cementing material. The filling body obtained by applying the prepared cementing material to the mine filling body has excellent mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, belonging to patent classification number C04B28 / 00, specifically to a binder for mine filling and its preparation method. Background Technology

[0002] In the process of mineral resource extraction, mine filling technology has become one of the key processes to ensure the safety of underground operations, control the deformation of the surrounding rock in the goaf, and achieve efficient resource recovery. Among them, the cementitious material, as the core cementing component of the filler, directly determines the strength, stability, and service life of the filler. Its main function is to bind with aggregates (such as tailings and waste rock) through its own hydration reaction to form a filler with certain mechanical properties to support the roof of the goaf and prevent surface subsidence.

[0003] With the increasing demands for cost control and green development in the mining industry, traditional mine filling solutions using cement as the sole binder are gradually becoming unsustainable due to the high cost of cement raw materials and the high energy consumption during production. Therefore, the industry has widely adopted a technology approach that uses industrial waste to partially replace cement. Common substitute waste materials include slag, fly ash, coal gangue powder, and steel slag. This approach not only reduces the raw material cost of binders but also enables the resource utilization of industrial solid waste, reducing the environmental pressure caused by solid waste accumulation, and aligns with the concept of green mine construction.

[0004] However, current cementitious binder technologies using industrial waste as a substitute for cement still have significant shortcomings: Since most industrial wastes (such as low-activity coal gangue and unactivated fly ash) have low cementitious activity, when the replacement ratio increases to a certain level (usually exceeding 30%), the hydration reaction of the binder becomes incomplete, leading to a significant decrease in the early and later mechanical strength of the filler, making it difficult to meet the design strength requirements for mine fillers. If the waste replacement ratio is reduced to ensure strength, the cost advantage and solid waste utilization value cannot be fully utilized. This makes it difficult for existing technologies to achieve an effective balance between cost control and mechanical performance, limiting their application in medium-deep mines, high-stress goaf areas, and other scenarios with high filler strength requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a binder for mine filling and its preparation method, so as to solve the technical problem of poor mechanical strength of mine filling bodies mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a binder for mine filling includes the following steps: S1. Fly ash, sodium sulfate, and calcium hydroxide are fed into a high-energy vibration mill and ground and activated under closed conditions. The activated composite powder is then fed into a calcination furnace and calcined at a constant temperature in an air atmosphere. The calcined material is then transferred to a closed cooling chamber and cooled to room temperature under an inert gas atmosphere to obtain deeply activated fly ash. S2. Magnesium slag powder, calcium sulfate whiskers and wollastonite fibers are fed into a high-speed shear emulsifier, and a polycarboxylate-based high-efficiency dispersant is added for high-speed shear mixing to obtain fiber-reinforced magnesium slag. S3. Deeply activated fly ash, fiber-reinforced magnesium slag, cement and composite activator are put into a three-dimensional motion mixer, nitrogen is introduced to replace the air and then they are mixed. After mixing, they are packaged by a fully automatic vacuum packaging machine to obtain the binder.

[0007] In this invention, high-energy mechanical grinding not only physically refines the fly ash particle size, significantly increasing the specific surface area and reaction interface, but also forces the added sodium sulfate and calcium hydroxide to undergo a solid-phase chemical reaction with the newly formed fly ash surface under mechanical force. This pre-generates precursors such as trace amounts of hydrated calcium silicate (CSH), effectively implanting hydrated crystal nuclei within the fly ash particles. High-temperature calcination then induces topological depolymerization of the fly ash's glassy network structure, breaking stable Si-O-Si and Si-O-Al bonds, transforming it from an inert state to a metastable state of active silicon-aluminum species, while simultaneously optimizing the crystal morphology of the precursors. After this modification, the fly ash transforms from an inert filler into a highly reactive material with a surface rich in amorphous active phases and internally embedded ions and crystal nuclei. When it comes into contact with subsequent activators, the hydration reaction rate of dissolution-nucleation-precipitation is greatly accelerated, enabling the rapid early generation of large amounts of CSH gel and ettringite, thus significantly contributing to the rapid development of early strength and the sustained increase in later strength. Then, calcium sulfate whiskers and wollastonite fibers were uniformly dispersed in the magnesium slag matrix using a high-speed shearing process, forming a stable three-dimensional fiber network structure. After the binder hydrates and hardens, these high aspect ratio, high-strength fibers act as highly efficient micro-reinforcing phases. Figure 1 This is a SEM image of the surface of the mine filler prepared using the binder of this invention, which shows the fiber structure doped within the filler. When the material is subjected to external forces and microcracks are generated, the fibers bridge the cracks, creating significant pull-out resistance, effectively consuming fracture energy and preventing microcracks from propagating into macroscopic cracks. This toughening mechanism transforms the material's failure mode from brittle fracture to quasi-plastic fracture, resulting in a significant increase in flexural strength and fracture toughness. This avoids cracking of the filler caused by formation deformation or shrinkage stress, thus ensuring the stability of mechanical strength indicators and further improving the mechanical strength of the filler.

[0008] Preferably, in step S1, the mass ratio of fly ash, sodium sulfate, and calcium hydroxide is 100:4-6:2-4.

[0009] Preferably, in step S1, the calcination temperature is 600–650°C and the calcination time is 40–60 min.

[0010] Preferably, in step S2, the mass ratio of magnesium slag powder, calcium sulfate whiskers, and wollastonite fiber is 80:5:4.

[0011] Preferably, in step S2, the calcium sulfate whiskers and wollastonite fibers are pretreated before being mixed with the dried magnesium slag powder, including the following steps: Add calcium hydroxide powder to calcium sulfate whiskers and wollastonite fibers, stir and mix evenly so that the calcium hydroxide powder adheres to the surface of the fibers, and you have the product.

[0012] In the technical solution of this invention, the research team discovered that during the final hydration process of the material, the deeply activated fly ash (highly active fine powder) and fiber-reinforced magnesium slag (containing micron-sized fibers and coarse particles) are prone to microscopic heterogeneity due to differences in physical morphology. The hydration reaction rates and products of the two phases are asynchronous, resulting in insufficient interweaving of cementitious products in the interface transition zone. Insufficient bonding force between the fiber and matrix interface makes it difficult to fully utilize the fiber bridging effect, ultimately restricting further improvement of the overall mechanical properties of the material. To further solve this technical problem, this invention uses calcium hydroxide powder for dry mixing pretreatment of calcium sulfate whiskers and wollastonite fibers. This allows the calcium hydroxide powder to be uniformly anchored on the fiber surface, forming active fibers, thereby endowing the fibers with new chemical functions. After mixing with water, a local high-calcium, high-alkali environment is rapidly established at the fiber-matrix interface, strongly promoting the in-situ generation of CSH gel and ettringite from dissolved fly ash ions at the interface. These products are chemically anchored at one end to the fiber surface and interwoven with the surrounding matrix at the other end, forming a strong chemical bridge, significantly strengthening the interface transition zone, and simultaneously improving compressive / flexural strength and durability.

[0013] Preferably, the amount of calcium hydroxide powder added is 5-10% of the total weight of calcium sulfate whiskers and wollastonite fibers.

[0014] Preferably, in step S3, the mass ratio of activated fly ash, fiber-reinforced magnesium slag, and cement is 40:50-60:10-15.

[0015] Preferably, in step S3, the composite activator is composed of sodium silicate, sulfoaluminate cement clinker powder, sodium sulfate and lithium carbonate.

[0016] Preferably, the mass ratio of sodium silicate, sulfoaluminate cement clinker powder, sodium sulfate, and lithium carbonate is 6:3:0.8:0.2.

[0017] A binder for mine filling is prepared by the method described above.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. By high-energy grinding and activation of fly ash and high-temperature calcination, it is transformed from an inert filler into a highly reactive material, which can accelerate the hydration reaction and generate a large amount of CSH gel and ettringite, effectively promoting the rapid development of early strength and the continuous growth of later strength of the filler.

[0019] 2. By constructing a three-dimensional fiber network through high-speed shearing and pretreating the fibers with calcium hydroxide to strengthen the interfacial bonding, microcrack propagation can be prevented, the material failure mode can be changed, the flexural strength can be greatly improved, the cracking of the filling body caused by the downhole environment can be avoided, and the mechanical strength can be kept stable. Attached Figure Description

[0020] Figure 1 This is a SEM image of the surface of the mine filler prepared using the binder of this invention. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: A method for preparing a binder for mine filling, comprising the following steps: Step 1: Accurately weigh 100 kg of dry Grade II fly ash, 5.5 kg of sodium sulfate, and 3.5 kg of calcium hydroxide, and add them together to a high-energy vibratory mill. Use zirconia ceramic balls as the grinding medium, with a ball-to-material ratio of 12:1. Perform mechanochemical activation at a vibration frequency of 25 Hz for 60 min under sealed conditions, controlling the mill cavity temperature to not exceed 65 ℃ during the process through a jacketed cooling system. Transfer the activated composite powder to a calcining furnace, and calcine it to 630 ℃ at a rate of 10 ℃ / min in air atmosphere for 50 min. After calcination, quickly transfer the material to a sealed stainless steel cooling chamber, and circulate high-purity nitrogen to cool it to room temperature (25 ℃), obtaining deeply activated fly ash.

[0023] Step 2: Weigh 5 kg of calcium sulfate whiskers and 4 kg of wollastonite fibers, and add them together with 0.8 kg of micron-sized calcium hydroxide powder into a V-type mixer. Dry mix at 15 r / min for 20 min to ensure that the calcium hydroxide is uniformly adhered to the fiber surface, obtaining the pretreated material. Add the pretreated material together with 80 kg of dry magnesium slag powder into a high-speed shear emulsifier, add 2.5 kg of polycarboxylate-based high-efficiency dispersant (40% solid content), and shear mix at 8000 r / min for 15 min to ensure that the fibers are uniformly dispersed to form a three-dimensional network structure, obtaining the fiber-reinforced magnesium slag composite material.

[0024] Step 3: Weigh 40 kg of deeply activated fly ash, 58 kg of fiber-reinforced magnesium slag, 14 kg of P·O 42.5 cement, and 8 kg of composite activator (pre-mixed from sodium silicate: sulfoaluminate cement clinker powder: sodium sulfate: lithium carbonate in a ratio of 6:3:0.8:0.2). Add each component sequentially to a three-dimensional motion mixer, purge the air with nitrogen, and mix for 45 minutes using a combined motion of 20 r / min revolution and 35 r / min rotation. After mixing, package the mixture using a fully automatic vacuum packaging machine, 25 kg per bag, with the vacuum level controlled at -0.08 MPa, to obtain the final binder.

[0025] Example 2: A method for preparing a binder for mine filling, comprising the following steps: Step 1: Accurately weigh 100 kg of dry Grade II fly ash, 4.5 kg of sodium sulfate, and 2.5 kg of calcium hydroxide, and add them together to a high-energy vibratory mill. Zirconia ceramic balls are used as the grinding media, with a ball-to-material ratio of 12:1. Mechanical and chemical activation is performed for 60 min at a vibration frequency of 25 Hz under sealed conditions, with the mill cavity temperature controlled to not exceed 65℃ during the process using a jacketed cooling system. The activated composite powder is then fed into a calcining furnace and heated to 630℃ at a rate of 10℃ / min in air, and calcined at this temperature for 50 min. After calcination, the material is quickly transferred to a sealed stainless steel cooling chamber, where high-purity nitrogen is circulated and cooled to room temperature (25℃) to obtain deeply activated fly ash.

[0026] Step 2: Weigh 5 kg of calcium sulfate whiskers and 4 kg of wollastonite fibers, and add them together with 0.6 kg of micron-sized calcium hydroxide powder into a V-type mixer. Dry mix at 15 r / min for 20 min to ensure that the calcium hydroxide is uniformly adhered to the fiber surface, obtaining the pretreated material. Add the pretreated material together with 80 kg of dry magnesium slag powder into a high-speed shear emulsifier, add 2.5 kg of polycarboxylate-based high-efficiency dispersant (40% solid content), and shear mix at 8000 r / min for 15 min to ensure that the fibers are uniformly dispersed to form a three-dimensional network structure, obtaining the fiber-reinforced magnesium slag composite material.

[0027] Step 3: Weigh 40 kg of deeply activated fly ash, 52 kg of fiber-reinforced magnesium slag, 11 kg of P·O 42.5 cement, and 8 kg of composite activator (pre-mixed from sodium silicate: sulfoaluminate cement clinker powder: sodium sulfate: lithium carbonate in a ratio of 6:3:0.8:0.2). Add each component sequentially to a three-dimensional motion mixer, purge the air with nitrogen, and mix for 45 minutes using a combined motion of 20 r / min revolution and 35 r / min rotation. After mixing, package the mixture using a fully automatic vacuum packaging machine, 25 kg per bag, with the vacuum level controlled at -0.08 MPa, to obtain the final binder.

[0028] Example 3: A method for preparing a binder for mine filling, comprising the following steps: Step 1: Accurately weigh 100 kg of dry Grade II fly ash, 5 kg of sodium sulfate, and 3 kg of calcium hydroxide, and add them together to a high-energy vibratory mill. Use zirconia ceramic balls as the grinding medium, with a ball-to-material ratio of 12:1. Perform mechanochemical activation at a vibration frequency of 25 Hz for 60 min under sealed conditions, controlling the mill cavity temperature to not exceed 65℃ during the process using a jacketed cooling system. Transfer the activated composite powder to a calcining furnace, and calcine it to 630℃ at a rate of 10℃ / min in air atmosphere for 50 min. After calcination, quickly transfer the material to a sealed stainless steel cooling chamber, and circulate high-purity nitrogen to cool it to room temperature (25℃) to obtain deeply activated fly ash.

[0029] Step 2: Weigh 5 kg of calcium sulfate whiskers and 4 kg of wollastonite fibers, and add them together with 0.7 kg of micron-sized calcium hydroxide powder into a V-type mixer. Dry mix at 15 r / min for 20 min to ensure that the calcium hydroxide is uniformly adhered to the fiber surface, obtaining the pretreated material. Add the pretreated material together with 80 kg of dry magnesium slag powder into a high-speed shear emulsifier, add 2.5 kg of polycarboxylate-based high-efficiency dispersant (40% solid content), and shear mix at 8000 r / min for 15 min to ensure that the fibers are uniformly dispersed to form a three-dimensional network structure, obtaining the fiber-reinforced magnesium slag composite material.

[0030] Step 3: Weigh 40 kg of deeply activated fly ash, 55 kg of fiber-reinforced magnesium slag, 13 kg of P·O 42.5 cement, and 8 kg of composite activator (pre-mixed from sodium silicate: sulfoaluminate cement clinker powder: sodium sulfate: lithium carbonate in a ratio of 6:3:0.8:0.2). Add each component sequentially to a three-dimensional motion mixer, purge the air with nitrogen, and mix for 45 minutes using a combined motion of 20 r / min revolution and 35 r / min rotation. After mixing, package the mixture using a fully automatic vacuum packaging machine, 25 kg per bag, with the vacuum level controlled at -0.08 MPa, to obtain the final binder.

[0031] Example 4: A method for preparing a binder for mine filling, comprising the following steps: Step 1: Accurately weigh 100 kg of dry Grade II fly ash, 6 kg of sodium sulfate, and 4 kg of calcium hydroxide, and add them together to a high-energy vibratory mill. Zirconia ceramic balls are used as the grinding media, with a ball-to-material ratio of 12:1. Mechanical and chemical activation is performed for 60 minutes at a vibration frequency of 25 Hz under sealed conditions, with the mill cavity temperature controlled to not exceed 65℃ during the process using a jacketed cooling system. The activated composite powder is then fed into a calcining furnace and heated to 650℃ at a rate of 10℃ / min in air, and calcined at this constant temperature for 60 minutes. After calcination, the material is quickly transferred to a sealed stainless steel cooling chamber, where high-purity nitrogen is circulated and cooled to room temperature (25℃) to obtain deeply activated fly ash.

[0032] Step 2: Weigh 5 kg of calcium sulfate whiskers and 4 kg of wollastonite fibers, and add them together with 0.9 kg of micron-sized calcium hydroxide powder into a V-type mixer. Dry mix at 15 r / min for 20 min to ensure that the calcium hydroxide is uniformly adhered to the fiber surface, obtaining the pretreated material. Add the pretreated material together with 80 kg of dry magnesium slag powder into a high-speed shear emulsifier, add 2.5 kg of polycarboxylate-based high-efficiency dispersant (40% solid content), and shear mix at 8000 r / min for 15 min to ensure that the fibers are uniformly dispersed to form a three-dimensional network structure, obtaining the fiber-reinforced magnesium slag composite material.

[0033] Step 3: Weigh 40 kg of deeply activated fly ash, 60 kg of fiber-reinforced magnesium slag, 15 kg of P·O 42.5 cement, and 8 kg of composite activator (pre-mixed from sodium silicate: sulfoaluminate cement clinker powder: sodium sulfate: lithium carbonate in a ratio of 6:3:0.8:0.2). Add each component sequentially to a three-dimensional motion mixer, purge the air with nitrogen, and mix for 45 minutes using a combined motion of 20 r / min revolution and 35 r / min rotation. After mixing, package the mixture using a fully automatic vacuum packaging machine, 25 kg per bag, with the vacuum level controlled at -0.08 MPa, to obtain the final binder.

[0034] Example 5: A method for preparing a binder for mine filling, comprising the following steps: Step 1: Accurately weigh 100 kg of dry Grade II fly ash, 4 kg of sodium sulfate, and 2 kg of calcium hydroxide, and add them together to a high-energy vibratory mill. Zirconia ceramic balls are used as the grinding media, with a ball-to-material ratio of 12:1. Mechanical and chemical activation is performed for 60 min at a vibration frequency of 25 Hz under sealed conditions, with the mill cavity temperature controlled to not exceed 65℃ during the process using a jacketed cooling system. The activated composite powder is then fed into a calcining furnace and heated to 600℃ at a rate of 10℃ / min in air, and calcined at this temperature for 40 min. After calcination, the material is quickly transferred to a sealed stainless steel cooling chamber, where high-purity nitrogen is circulated and cooled to room temperature (25℃) to obtain deeply activated fly ash.

[0035] Step 2: Weigh 5 kg of calcium sulfate whiskers and 4 kg of wollastonite fibers, and add them together with 0.45 kg of micron-sized calcium hydroxide powder into a V-type mixer. Dry mix at 15 r / min for 20 min to ensure that the calcium hydroxide is uniformly adhered to the fiber surface, obtaining the pretreated material. Add the pretreated material together with 80 kg of dry magnesium slag powder into a high-speed shear emulsifier, add 2.5 kg of polycarboxylate-based high-efficiency dispersant (40% solid content), and shear mix at 8000 r / min for 15 min to ensure that the fibers are uniformly dispersed to form a three-dimensional network structure, obtaining the fiber-reinforced magnesium slag composite material.

[0036] Step 3: Weigh 40 kg of deeply activated fly ash, 50 kg of fiber-reinforced magnesium slag, 10 kg of P·O 42.5 cement, and 8 kg of composite activator (pre-mixed from sodium silicate: sulfoaluminate cement clinker powder: sodium sulfate: lithium carbonate in a ratio of 6:3:0.8:0.2). Add each component sequentially to a three-dimensional motion mixer, purge the air with nitrogen, and mix for 45 minutes using a combined motion of 20 r / min revolution and 35 r / min rotation. After mixing, package the mixture using a fully automatic vacuum packaging machine, 25 kg per bag, with the vacuum level controlled at -0.08 MPa, to obtain the final binder.

[0037] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step 1 is omitted and the deeply activated fly ash is replaced with ordinary fly ash.

[0038] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step 2 is omitted and fiber-reinforced magnesium slag is replaced with magnesium slag.

[0039] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that in step 2, the calcium sulfate whiskers and wollastonite fibers were not pretreated with micron-sized calcium hydroxide powder.

[0040] Performance testing: The raw materials for preparing coal mine backfill material include coal gangue, water, and the binder prepared above. The dosage of each component is as follows: coal gangue dosage is 1300 kg / m³.3 Water consumption is 450 kg / m³ 3 The binder dosage is 220 kg / m³. 3 .

[0041] 1. Compressive strength test: The test was conducted according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The binder, coal gangue, and water were mixed evenly according to the specified proportions, and then poured into 70.7mm×70.7mm×70.7mm cubic molds. After compaction, the mixture was cured under standard curing conditions (temperature 20±2℃, relative humidity ≥95%) for 3 days, 7 days, and 28 days. A hydraulic compression testing machine was used to test the compressive strength at a loading rate of 2.4kN / s. Three specimens were tested in each group, and the arithmetic mean was taken as the result. The test results are shown in Table 1.

[0042] 2. Flexural Strength Test: Referring to GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)," prism-shaped specimens of 40mm×40mm×160mm were prepared from the mixture and cured to standard conditions for 3 days, 7 days, and 28 days. The three-point bending method was used, with a loading rate of 50N / s on a flexural testing machine, a span of 100mm, and 3 specimens per group. The arithmetic mean was taken as the result. The test results are shown in Table 1.

[0043]

[0044] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a binder for mine filling, characterized in that, Includes the following steps: S1. Fly ash, sodium sulfate, and calcium hydroxide are fed into a high-energy vibration mill and ground and activated under closed conditions. The activated composite powder is then fed into a calcination furnace and calcined at a constant temperature in an air atmosphere. The calcined material is then transferred to a closed cooling chamber and cooled to room temperature under an inert gas atmosphere to obtain deeply activated fly ash. S2. Magnesium slag powder, calcium sulfate whiskers and wollastonite fibers are fed into a high-speed shear emulsifier, and a polycarboxylate-based high-efficiency dispersant is added for high-speed shear mixing to obtain fiber-reinforced magnesium slag. S3. Deeply activated fly ash, fiber-reinforced magnesium slag, cement and composite activator are put into a three-dimensional motion mixer, nitrogen is introduced to replace the air and then they are mixed. After mixing, they are packaged by a fully automatic vacuum packaging machine to obtain the binder.

2. The method for preparing a binder for mine filling according to claim 1, characterized in that, In step S1, the mass ratio of fly ash, sodium sulfate, and calcium hydroxide is 100:4-6:2-4.

3. The method for preparing a binder for mine filling according to claim 1, characterized in that, In step S1, the calcination temperature is 600-650℃ and the calcination time is 40-60 min.

4. The method for preparing a binder for mine filling according to claim 1, characterized in that, In step S2, the mass ratio of magnesium slag powder, calcium sulfate whiskers, and wollastonite fiber is 80:5:

4.

5. A method for preparing a binder for mine filling according to claim 1, characterized in that, In step S2, the calcium sulfate whiskers and wollastonite fibers undergo pretreatment before being mixed with the dried magnesium slag powder, including the following steps: Add calcium hydroxide powder to calcium sulfate whiskers and wollastonite fibers, stir and mix evenly so that the calcium hydroxide powder adheres to the surface of the fibers, and you have the product.

6. A method for preparing a binder for mine filling according to claim 5, characterized in that, The amount of calcium hydroxide powder added is 5-10% of the total weight of calcium sulfate whiskers and wollastonite fibers.

7. A method for preparing a binder for mine filling according to claim 1, characterized in that, In step S3, the mass ratio of activated fly ash, fiber-reinforced magnesium slag, and cement is 40:50-60:10-15.

8. A method for preparing a binder for mine filling according to claim 1, characterized in that, In step S3, the composite activator is composed of sodium silicate, sulfoaluminate cement clinker powder, sodium sulfate and lithium carbonate.

9. A method for preparing a binder for mine filling according to claim 8, characterized in that, The mass ratio of sodium silicate, sulfoaluminate cement clinker powder, sodium sulfate, and lithium carbonate is 6:3:0.8:0.

2.

10. A binder for mine filling, characterized in that, It is prepared by the method described in any one of claims 1-9 above.

Images