Early-strength solid waste-based cementitious material suitable for high flow rate filling and application method thereof in mine filling

Abstract

The present application relates to solid waste treatment technical field, and disclose the application method of early strength solid waste base cementing material suitable for high flow filling in mine filling, raw material composition includes: yellow phosphorus slag, slag, stainless steel slag, fly ash, phosphogypsum, coal gangue, blast furnace water slag, composite early strength activator, polycarboxylate superplasticizer and polyamide-amine dendritic polymer, the present application technical scheme adopts mechanical activation, plasma etching, sodium silicate synergistic excitation composite modification process to treat yellow phosphorus slag, mechanical activation breaks the glass body structure of yellow phosphorus slag through ultrafine grinding, increases specific surface area and active site, plasma etching forms rough etching appearance on the surface of yellow phosphorus slag, further improves surface reactivity, sodium silicate synergistic excitation promotes the generation of hydration product through chemical action, the three together makes the activity of yellow phosphorus slag significantly improve, thereby speeds up the hydration reaction process.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment technology, and in particular to an early-strength solid waste-based cementitious material suitable for high-flow-rate backfilling and its application method in mine backfilling. Background Technology

[0002] With the increasing intensity of mineral resource mining, the number and scale of goaf areas are continuously increasing. Mine backfilling technology has become a key technical means to ensure mining safety and control surface subsidence. High-velocity backfilling is widely used in large-scale mining due to its advantages such as high backfilling efficiency, short operation cycle, and adaptability to complex goaf morphology. However, this process places stringent requirements on cementing materials: on the one hand, it must have excellent early strength properties to ensure that the backfill body quickly forms load-bearing capacity and avoid safety hazards caused by slow strength development; on the other hand, it must have good flow properties and stability to meet the technical requirements of no pipe blockage and no segregation during high-velocity transportation.

[0003] Currently, cement-based materials are commonly used in mine backfilling. However, cement production is energy-intensive, generates significant carbon emissions, and its costs continue to rise, which is inconsistent with the concept of green development. To address this issue, the industry is gradually shifting towards the research and application of solid waste-based cementitious materials. These materials utilize industrial solid wastes such as yellow phosphorus slag, slag, and stainless steel slag as primary raw materials, reducing material costs and achieving resource utilization of solid waste. However, existing solid waste-based cementitious materials generally suffer from the following technical bottlenecks: First, industrial solid waste itself has low activity, a slow hydration reaction process, and insufficient early strength, making it difficult to meet the early load-bearing capacity requirements of high-flow-rate backfilling. Second, the particle size distribution of solid waste is unreasonable, resulting in poor slurry flow properties and significant losses over time, easily leading to pipe blockage during high-flow-rate transport and affecting backfilling efficiency. Third, some solid wastes have strong surface inertness and poor compatibility with other components, resulting in insufficient overall structural density of the cementitious material and poor long-term mechanical property stability.

[0004] Therefore, developing an early-strength solid waste-based cementitious material that balances early strength performance, flowability, and long-term stability, and is compatible with high-flow-rate filling processes, has become an urgent technical problem to be solved in the industry. Summary of the Invention

[0005] To address the problems in the prior art, this invention provides an early-strength solid waste-based cementitious material suitable for high-flow-rate filling.

[0006] The technical solution adopted by this invention to solve its technical problem is: an early-strength solid waste-based cementitious material suitable for high-flow-rate filling, the raw material composition by mass percentage includes: 28-32 parts yellow phosphorus slag, 16-22 parts blast furnace slag, 12-18 parts stainless steel slag, 10-13 parts fly ash, 6-10 parts phosphogypsum, 4-7 parts coal gangue, 3-5 parts blast furnace slag, 1.5-2.5 parts composite early-strength activator, 0.9-1.2 parts polycarboxylate-based high-efficiency water-reducing agent, and 0.25-0.35 parts polyamide-amine dendritic polymer; The composite early strength activator is composed of calcium aluminate cement, silica fume, nano calcium carbonate and lithium carbonate in a mass ratio of 3:2:0.2:0.03; The water-cement ratio of the cementitious material is 0.35-0.45; The nano-calcium carbonate has a particle size of 50-100 nm and is modified with silane coupling agent KH-550.

[0007] As a further technical solution, the polyamide-amine dendritic polymer is of generation 3.0G, with a number-average molecular weight of 14,000-16,000 Da, a solid content of ≥98%, an amine value of 4.5-5.5 mmol / g, a water solubility of ≥99%, and a glass transition temperature of -15℃ to -5℃.

[0008] As a further technical solution, the yellow phosphorus slag undergoes modification treatment, the modification steps of which include: S1, the yellow phosphorus slag is mechanically activated by ultra-fine grinding using an air jet mill. The grinding pressure is 0.85-0.95MPa, the air velocity is 20-24m / s, the classification speed is 3000-3500r / min, the grinding time is 20-30min, and the particle size is 400 mesh, which initially breaks the glass structure. S2, the crushed yellow phosphorus slag is sent into a low-temperature plasma treatment device, and argon and oxygen mixed plasma with a volume ratio of 4:1 is used for etching treatment. The plasma power is 150-200W, the treatment time is 5-8min, and the treatment temperature is controlled at 80-100℃ to avoid secondary inertization caused by high temperature. The plasma etching forms a porous structure on the surface of the yellow phosphorus slag and exposes active groups. S3 involves mixing plasma-treated yellow phosphorus slag with 2%-4% (by weight) sodium silicate powder, adding deionized water to adjust the moisture content to 12%-15%, and stirring and activating at 40-50℃ and 320-380 r / min for 25-35 min to complete the synergistic activation of sodium silicate. Finally, the mixture is dried at 105-110℃ until the moisture content is ≤0.8%, yielding modified yellow phosphorus slag. This method specifically addresses the inert glassy structure on the surface of yellow phosphorus slag, increases the number of active sites, and reduces its high water demand and slow hydration rate.

[0009] As a further technical solution, the stainless steel slag undergoes a three-stage composite modification treatment, the modification steps of which include: The first step is to heat the stainless steel slag to 380-420℃ at a heating rate of 6-7℃ / min, hold it at that temperature for 30 minutes, and allow the holding time to fluctuate by ≤1.5 minutes. During the roasting process, a mixture of oxygen and nitrogen in a volume ratio of 2:3 is introduced to enhance the efficiency of free iron oxidation and removal. The second step involves immersing the roasted stainless steel slag in a Na2CO3 solution with a mass concentration of 2.2%-2.8%, adding 0.3%-0.5% sodium tripolyphosphate as an immersion aid, and immersing for 1 hour at 52-58℃ and 160-190 r / min to remove surface impurities and soluble salts and increase the exposure of active sites in the slag. The third step involves filtering and washing the alkali-leached stainless steel slag until it is neutral, then using microwave equipment for auxiliary activation. The microwave power is 300-400W, and the microwave time is 8-12 minutes. During the microwave process, the slag is stirred intermittently for 30 seconds every 2 minutes at a stirring speed of 150 r / min to avoid local overheating and further break down the inert glass structure on the surface of the stainless steel slag. Finally, the slag is dried at 106-109℃ until the moisture content is ≤0.8% to obtain the modified stainless steel slag.

[0010] As a further technical solution, the polycarboxylate-based high-efficiency water-reducing agent is a polyether-type polycarboxylate water-reducing agent with a solid content of 42%-48%.

[0011] As a further technical solution, the particle size of the slag is 360-390 mesh, the particle size of the fly ash is 310-340 mesh, and the particle size of the phosphogypsum is 310-340 mesh.

[0012] As a further technical solution, the mixing sequence of the composite early strength activator is as follows: first, calcium aluminate cement and silica fume are mixed and stirred at a speed of 400-500 r / min for 3.5-4.5 min, then modified nano calcium carbonate and lithium carbonate are added, and stirring is continued at a speed of 400-500 r / min for 2.2-2.8 min until uniform.

[0013] As a further technical solution, the modification steps of the silane coupling agent KH-550 include: first, mixing anhydrous ethanol and glycerol at a volume ratio of 8:2 to prepare a mixed solvent; then, dispersing nano-calcium carbonate in the mixed solvent, with 220-280 mL of mixed solvent for every 100 g of nano-calcium carbonate; stirring until no obvious agglomeration of nano-calcium carbonate, at a stirring speed of 220-280 r / min for 30 min; adding the silane coupling agent KH-550; stirring at 62-68℃ and 220-280 r / min for 2.0-2.5 h; centrifuging using a high-speed centrifuge at a centrifuge speed of 8000-10000 r / min for 10-15 min; and drying at 105-110℃ until the moisture content is ≤0.8% to obtain modified nano-calcium carbonate.

[0014] The application method of cementitious materials in mine backfilling includes the following steps: S1. Raw material pretreatment: Modification treatment of yellow phosphorus slag, stainless steel slag, and nano-calcium carbonate is completed respectively; crushing and screening treatment of coal gangue, blast furnace slag, slag, fly ash, and residual phosphogypsum is completed to ensure that the moisture content of each solid raw material is ≤0.8%; S2. Solid component mixing: Add each solid component into the mixing equipment in the following order: slag, fly ash, blast furnace slag, coal gangue, residual phosphogypsum, modified yellow phosphorus slag, modified stainless steel slag, and modified nano-calcium carbonate. Mix at a speed of 520-580 r / min for 8-12 minutes to obtain the basic mixture. S3. Slurry preparation: Add a composite early strength activator, a polycarboxylate-based high-efficiency water-reducing agent, a polyamide-amine dendritic polymer and water to the basic mixture. The amount of water added is such that the water-cement ratio of the cementitious material is 0.35-0.45. Continue stirring at a speed of 500-580 r / min for 16-25 min until the slurry spread is 360-400 mm to prepare the filling slurry. S4. High-velocity conveying: Steel pipeline pumps are used to deliver the filling slurry at a speed of 1.8-2.8 m / s; S5. Filling, molding and curing: The slurry is injected into the goaf of the mine to complete the filling and molding. Natural curing is adopted, with a curing temperature of 18-32℃ and a curing humidity of ≥85%.

[0015] As a further technical solution, in step S3, the composite early strength activator, polycarboxylate-based high-efficiency water-reducing agent, and polyamide-amine dendritic polymer are added in steps. First, the composite early strength activator is added and stirred for 5 minutes, then the polycarboxylate-based high-efficiency water-reducing agent and polyamide-amine dendritic polymer are added, and stirring is continued until the slurry expansion is 360-400 mm.

[0016] The beneficial effects of this invention are: This invention employs a composite modification process involving mechanical activation, plasma etching, and sodium silicate synergistic activation to treat yellow phosphorus slag. Mechanical activation breaks down the glassy structure of the yellow phosphorus slag through ultrafine grinding, increasing its specific surface area and active sites. Plasma etching creates a rough etched morphology on the surface of the yellow phosphorus slag, further enhancing its surface reactivity. Sodium silicate synergistic activation promotes the generation of hydration products through chemical action. The combined effect of these three processes significantly enhances the activity of the yellow phosphorus slag, thereby accelerating the hydration reaction process and laying the foundation for the early strength development of the cementitious material. This solves the problem of insufficient solid waste activity under traditional treatment processes. Stainless steel slag undergoes a three-stage composite modification process of "calcination-alkali leaching-microwave activation." Calcination removes surface impurities and activates internal active components; alkali leaching dissolves harmful impurities and optimizes particle surface properties; and microwave activation further strengthens active sites. This effectively improves the hydration activity and compatibility of the stainless steel slag with other components, avoiding the loose structure of the cementitious material caused by low activity and poor compatibility of unmodified stainless steel slag.

[0017] The composite early strength activator is composed of calcium aluminate cement, silica fume, modified nano-calcium carbonate, and lithium carbonate in a specific ratio. Calcium aluminate cement rapidly hydrates to form hydrated calcium aluminate, providing early strength support. Silica fume, with its high activity, participates in the hydration reaction, generating a low-calcium-to-silica hydrated calcium silicate gel, resulting in a dense internal structure. Modified nano-calcium carbonate refines capillary pores through a nano-filling effect, and after modification with the silane coupling agent KH-550, it bonds more tightly to the matrix interface, improving structural integrity. Lithium carbonate, as a coagulating agent, accelerates the hydration reaction rate. These four components synergistically form a highly efficient early strength activating system, significantly improving the early strength of cementitious materials and solving the technical problem of insufficient early strength performance in traditional solid waste-based cementitious materials. Polyamide-amine dendritic polymers, with their unique dendritic structure, adsorb onto the surface of solid particles, preventing particle agglomeration through electrostatic repulsion and steric hindrance. Simultaneously, they optimize particle size distribution and promote the uniform growth of hydration products, improving both the flow properties of the slurry and the density of the material structure, achieving a synergistic improvement in both flow properties and strength.

[0018] In this invention, the solid raw materials are scientifically proportioned. Yellow phosphorus slag, blast furnace slag, and stainless steel slag, among other main solid wastes, provide the basic framework structure. Fly ash, phosphogypsum, and coal gangue, among other auxiliary solid wastes, fill the pores of the framework. Blast furnace slag optimizes the particle size distribution, forming a composite "framework-filler" structural system. Combined with the activating effect of a composite early-strength activator, this ensures uniform distribution of hydration products and significantly improves the material's structural density. The synergistic effect of polycarboxylate-based high-efficiency water-reducing agent and polyamide-amine dendritic polymer allows the polycarboxylate-based high-efficiency water-reducing agent to reduce slurry viscosity through adsorption-dispersion, while the polyamide-amine dendritic polymer enhances dispersion stability. Together, they inhibit particle agglomeration, prolong the slurry's flow retention time, and ensure that the slurry does not clog pipes or segregate during high-flow-rate transport. Simultaneously, this synergistic dispersion effect provides ample reaction space for the hydration reaction, promoting the full generation of hydration products and further enhancing the material's mechanical strength.

[0019] The modified solid waste and functional components form a highly efficient synergistic system: the activity of modified solid waste such as yellow phosphorus slag and stainless steel slag is greatly enhanced, and the reaction efficiency with the composite early strength activator is significantly improved, accelerating the generation of early strength hydration products; modified nano calcium carbonate not only participates in early strength activation, but also optimizes the structure through the nano-filling effect, combined with the dispersion effect of polyamide-amine dendritic polymer, further improving the material's density and strength stability; the precise control of the water-binder ratio and the synergistic cooperation of each component ensure the high fluidity of the slurry while avoiding the problem of strength reduction caused by excessive water, achieving a synergistic performance of high fluidity, early strength, and high strength. Attached Figure Description

[0020] Figure 1 A comparison chart of the strength loss rate after 200 freeze-thaw cycles for an early-strength solid waste-based cementitious material suitable for high-flow-rate filling. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides an early-strength solid waste-based cementitious material suitable for high-flow-rate filling and its application method in mine filling. The cementitious material is prepared by using a variety of solid wastes as the main raw materials, combined with a specific composite early-strength activator, a polycarboxylate-based high-efficiency water-reducing agent and a polyamide-amine dendritic polymer, through a specific process. It can meet the requirements of early-strength performance and flow performance under high-flow-rate filling conditions.

[0023] Raw material composition: By mass percentage, the raw materials of the cementitious material include 28-32 parts of yellow phosphorus slag, 16-22 parts of blast furnace slag, 12-18 parts of stainless steel slag, 10-13 parts of fly ash, 6-10 parts of phosphogypsum, 4-7 parts of coal gangue, 3-5 parts of blast furnace slag, 1.5-2.5 parts of composite early strength activator, 0.9-1.2 parts of polycarboxylate-based high-efficiency water-reducing agent, and 0.25-0.35 parts of polyamide-amine dendritic polymer.

[0024] The specific requirements for each raw material are as follows: The particle size of slag is 360-390 mesh; the particle size of fly ash is 310-340 mesh; and the particle size of phosphogypsum is 310-340 mesh.

[0025] The polyamide-amine dendritic polymer is a 3.0 G generation, with a number average molecular weight of 14,000-16,000 Da, a solid content of ≥98%, an amine value of 4.5-5.5 mmol / g, a water solubility of ≥99%, and a glass transition temperature of -15℃ to -5℃.

[0026] The polycarboxylate superplasticizer is a polyether-type polycarboxylate superplasticizer with a solid content of 42%-48%.

[0027] The composite early strength activator is composed of calcium aluminate cement, silica fume, nano calcium carbonate and lithium carbonate in a mass ratio of 3:2:0.2:0.03; wherein the nano calcium carbonate has a particle size of 50-100nm and is modified by silane coupling agent KH-550.

[0028] Yellow phosphorus slag modification treatment: The first step involves using an air jet mill to perform ultra-fine pulverization and mechanical activation on the yellow phosphorus slag. The pulverization pressure is 0.85-0.95 MPa, the airflow velocity is 20-24 m / s, the grading speed is 3000-3500 r / min, and the pulverization time is 20-30 min, pulverizing to a particle size of 400 mesh, thus initially breaking down the glassy structure.

[0029] The second step involves feeding the crushed yellow phosphorus slag into a low-temperature plasma treatment device, where a mixed plasma of argon and oxygen with a volume ratio of 4:1 is used for etching. The plasma power is 150-200W, the treatment time is 5-8 minutes, and the treatment temperature is controlled at 80-100℃.

[0030] The third step involves mixing the plasma-treated yellow phosphorus slag with 2%-4% sodium silicate powder by weight of the yellow phosphorus slag, adding deionized water to adjust the moisture content of the material to 12%-15%, and stirring and activating it for 25-35 minutes at 40-50℃ and 320-380 r / min to complete the synergistic activation of sodium silicate. Finally, it is dried at 105-110℃ until the moisture content is ≤0.8% to obtain the modified yellow phosphorus slag.

[0031] Modification treatment of stainless steel slag: The first step is to heat the stainless steel slag to 380-420℃ at a heating rate of 6-7℃ / min, hold it at that temperature for 30 minutes, with a holding time fluctuation of ≤1.5 minutes, and introduce a mixture of oxygen and nitrogen in a volume ratio of 2:3 during the roasting process.

[0032] The second step involves immersing the roasted stainless steel slag in a Na2CO3 solution with a mass concentration of 2.2%-2.8%, adding 0.3%-0.5% sodium tripolyphosphate as an immersion aid, and immersing for 1 hour at 52-58℃ and 160-190 r / min.

[0033] The third step involves filtering and washing the alkali-leached stainless steel slag until it is neutral, then using microwave equipment for auxiliary activation. The microwave power is 300-400W, the microwave time is 8-12 minutes, and the slag is stirred intermittently during the microwave process, stirring for 30 seconds every 2 minutes at a stirring speed of 150 r / min. Finally, the slag is dried at 106-109℃ until the moisture content is ≤0.8%, thus obtaining the modified stainless steel slag.

[0034] The modification of nano-calcium carbonate involves first preparing a mixed solvent by mixing anhydrous ethanol and glycerol at a volume ratio of 8:2, then dispersing the nano-calcium carbonate in the mixed solvent at a ratio of 220-280 mL per 100 g of nano-calcium carbonate. The mixture is stirred until no significant agglomeration of the nano-calcium carbonate is observed, at a stirring speed of 220-280 r / min for 30 min. A silane coupling agent, KH-550, is then added, and the mixture is stirred at 62-68℃ and 220-280 r / min for 2.0-2.5 h. The mixture is then centrifuged using a high-speed centrifuge at 8000-10000 r / min for 10-15 min. Finally, the mixture is dried at 105-110℃ until the moisture content is ≤0.8%, yielding modified nano-calcium carbonate.

[0035] Preparation of composite early strength activator: The mixing sequence of the composite early strength activator is as follows: first, mix calcium aluminate cement and silica fume at a speed of 400-500 r / min for 3.5-4.5 min, then add modified nano calcium carbonate and lithium carbonate, and continue to stir at a speed of 400-500 r / min for 2.2-2.8 min until uniform, to obtain the composite early strength activator.

[0036] Preparation of cementitious materials: (1) Raw material pretreatment: The modification treatments of yellow phosphorus slag, stainless steel slag, and nano calcium carbonate were completed respectively. The crushing and screening treatments of coal gangue, blast furnace slag, slag, fly ash, and residual phosphogypsum were completed to ensure that the moisture content of each solid raw material is ≤0.8%.

[0037] (2) Mixing of solid components: Add the solid components to the mixing equipment in the following order: slag, fly ash, blast furnace slag, coal gangue, residual phosphogypsum, modified yellow phosphorus slag, modified stainless steel slag, and modified nano-calcium carbonate. Mix at 520-580 r / min for 8-12 minutes to obtain the basic mixture.

[0038] (3) Slurry preparation: Add a composite early-strength activator, a polycarboxylate superplasticizer, a polyamide-amine dendritic polymer, and water to the base mixture. The amount of water added should meet the water-cement ratio of 0.35-0.45 for the cementitious material. Continue stirring at 500-580 r / min for 16-25 min, until the slurry spread is 360-400 mm, to prepare the filling slurry. The composite early-strength activator, polycarboxylate superplasticizer, and polyamide-amine dendritic polymer are added in steps: first, add the composite early-strength activator and stir for 5 min, then add the polycarboxylate superplasticizer and polyamide-amine dendritic polymer, and continue stirring until the slurry spread is 360-400 mm.

[0039] (4) High-velocity conveying: The filling slurry is pumped through steel pipelines at a speed of 1.8-2.8 m / s.

[0040] (5) Filling, molding, and curing: The slurry is injected into the goaf of the mine to complete the filling and molding, and natural curing is adopted with a curing temperature of 18-32℃ and a curing humidity of ≥85%.

[0041] The cementitious material provided by this invention uses a variety of industrial solid wastes as main raw materials, realizing the efficient utilization of solid waste resources and reducing material costs. Through a specific modification process, the activity of solid waste is improved. Combined with the synergistic effect of composite early strength activator and polyamide-amine dendritic polymer, the early strength of the cementitious material is significantly improved. At the same time, the raw material ratio and preparation process are optimized to ensure that the slurry has good fluidity, which can meet the requirements of high flow rate transportation. After filling and molding, it has good volume stability and is suitable for high flow rate filling projects in mining goaf areas.

[0042] To further illustrate the present invention, the following detailed description is provided through the examples and comparative examples.

[0043] Example 1: Raw material pretreatment: Prepare raw materials according to the following weight parts: 28 parts yellow phosphorus slag, 16 parts blast furnace slag, 12 parts stainless steel slag, 10 parts fly ash, 6 parts phosphogypsum, 4 parts coal gangue, 3 parts blast furnace slag, 1.5 parts composite early strength activator, 0.9 parts polycarboxylate-based high-efficiency water-reducing agent, and 0.25 parts polyamide-amine dendritic polymer. The polyamide-amine dendritic polymer has a number-average molecular weight of 14000 Da, an amine value of 4.5 mmol / g, and a glass transition temperature of -15℃; the polycarboxylate-based high-efficiency water-reducing agent has a solid content of 42%; and the nano-calcium carbonate has a particle size of 50 nm.

[0044] Modification of yellow phosphorus slag: Ultrafine grinding and mechanical activation were carried out using an air jet mill with a grinding pressure of 0.85 MPa, an air velocity of 20 m / s, a classifying speed of 3000 r / min, and a grinding time of 20 min; plasma treatment was performed with a power of 150 W, a treatment time of 5 min, and a treatment temperature of 80℃; the mixture was then mixed with sodium silicate powder at 2% by weight of yellow phosphorus slag, with a material moisture content of 12%, and stirred and activated at 40℃ and a speed of 320 r / min for 25 min, and then dried at 105℃ until the moisture content was ≤0.8%.

[0045] Modification of stainless steel slag: The temperature was raised to 380℃ at 6℃ / min and calcined for 30min. A mixture of oxygen and nitrogen with a volume ratio of 2:3 was introduced. The slag was immersed in a 2.2% Na2CO3 solution and 0.3% sodium tripolyphosphate was added. The slag was then washed at 52℃ and 160r / min for 1h. The slag was microwaved for 8min at a power of 300W. The slag was dried at 106℃ until the moisture content was ≤0.8%.

[0046] Nano-calcium carbonate modification: 100g of nano-calcium carbonate corresponds to 220mL of mixed solvent, and the dispersion stirring speed is 220r / min; after adding silane coupling agent KH-550, stir at 62℃ and 220r / min for 2.0h; centrifuge at 8000r / min for 10min; dry at 105℃ until the moisture content is ≤0.8%.

[0047] Preparation of composite early strength activator: calcium aluminate cement, silica fume, modified nano calcium carbonate and lithium carbonate are mixed in a mass ratio of 3:2:0.2:0.03. First, the calcium aluminate cement and silica fume are stirred at 400 r / min for 3.5 min. Then, the modified nano calcium carbonate and lithium carbonate are added, and the mixture is stirred at 400 r / min for 2.2 min until uniform.

[0048] Solid component mixing: Add each solid component in the specified order and stir at 520 r / min for 8 min to obtain the basic mixture.

[0049] Slurry preparation: Water-to-binder ratio 0.35. First, add the composite early strength activator and stir for 5 minutes. Then, add the polycarboxylate-based high-efficiency water-reducing agent and polyamide-amine dendritic polymer. Continue stirring at 500 r / min for 16 minutes until the slurry spread reaches 360 mm.

[0050] High-velocity conveying: Steel pipeline pumping is used, with a pumping speed of 1.8 m / s.

[0051] Filling, molding, and curing: Injected into the goaf of the mine, naturally cured at a temperature of 18℃ and a humidity of 85%.

[0052] Example 2: Raw material pretreatment: Prepare raw materials according to the following weight parts: 32 parts yellow phosphorus slag, 22 parts blast furnace slag, 18 parts stainless steel slag, 13 parts fly ash, 10 parts phosphogypsum, 7 parts coal gangue, 5 parts blast furnace slag, 2.5 parts composite early strength activator, 1.2 parts polycarboxylate-based high-efficiency water-reducing agent, and 0.35 parts polyamide-amine dendritic polymer. The polyamide-amine dendritic polymer has a number-average molecular weight of 16000 Da, an amine value of 5.5 mmol / g, and a glass transition temperature of -5℃; the polycarboxylate-based high-efficiency water-reducing agent has a solid content of 48%; and the nano-calcium carbonate has a particle size of 100 nm.

[0053] Modification of yellow phosphorus slag: Ultrafine grinding and mechanical activation were carried out using an air jet mill with a grinding pressure of 0.95 MPa, an air velocity of 24 m / s, a classifying speed of 3500 r / min, and a grinding time of 30 min; plasma treatment was performed with a power of 200 W, a treatment time of 8 min, and a treatment temperature of 100℃; it was then mixed with 4% sodium silicate powder by weight of yellow phosphorus slag, with a material moisture content of 15%, and stirred and activated at 50℃ and a speed of 380 r / min for 35 min, and dried at 110℃ until the moisture content was ≤0.8%.

[0054] Modification of stainless steel slag: The temperature was raised to 420℃ at 7℃ / min and calcined for 30min. A mixture of oxygen and nitrogen with a volume ratio of 2:3 was introduced. The slag was immersed in a 2.8% Na2CO3 solution and 0.5% sodium tripolyphosphate (sodium tripolyphosphate) was added. The slag was washed at 58℃ and 190r / min for 1h. The slag was microwaved at 400W for 12min. The slag was dried at 109℃ until the moisture content was ≤0.8%.

[0055] Nano-calcium carbonate modification: 100g of nano-calcium carbonate corresponds to 280mL of mixed solvent, and the dispersion stirring speed is 280r / min; after adding silane coupling agent KH-550, stir at 68℃ and 280r / min for 2.5h; centrifuge at 10000r / min for 15min; dry at 110℃ until the moisture content is ≤0.8%.

[0056] Preparation of composite early strength activator: calcium aluminate cement, silica fume, modified nano calcium carbonate and lithium carbonate are mixed in a mass ratio of 3:2:0.2:0.03. First, the calcium aluminate cement and silica fume are stirred at 500 r / min for 4.5 min. Then, the modified nano calcium carbonate and lithium carbonate are added, and the mixture is stirred at 500 r / min for 2.8 min until uniform.

[0057] Solid component mixing: Add each solid component in the specified order and stir at 580 r / min for 12 min to obtain the basic mixture.

[0058] Slurry preparation: Water-to-binder ratio 0.45. First, add the composite early strength activator and stir for 5 minutes. Then, add the polycarboxylate-based high-efficiency water-reducing agent and polyamide-amine dendritic polymer. Continue stirring at 580 r / min for 25 minutes until the slurry spread reaches 400 mm.

[0059] High-velocity conveying: Steel pipeline pumping is used, with a pumping speed of 2.8 m / s.

[0060] Filling, molding, and curing: Injected into the goaf of the mine, naturally cured at a temperature of 32℃ and a humidity of 90%.

[0061] Example 3: Raw material pretreatment: Prepare raw materials according to the following weight parts: 30 parts yellow phosphorus slag, 19 parts blast furnace slag, 15 parts stainless steel slag, 11.5 parts fly ash, 8 parts phosphogypsum, 5.5 parts coal gangue, 4 parts blast furnace slag, 2.0 parts composite early strength activator, 1.05 parts polycarboxylate-based high-efficiency water-reducing agent, and 0.3 parts polyamide-amine dendritic polymer. The polyamide-amine dendritic polymer has a number-average molecular weight of 15000 Da, an amine value of 5.0 mmol / g, and a glass transition temperature of -10℃; the polycarboxylate-based high-efficiency water-reducing agent has a solid content of 45%; and the nano-calcium carbonate has a particle size of 75 nm.

[0062] Modification of yellow phosphorus slag: Ultrafine grinding and mechanical activation were carried out using an air jet mill with a grinding pressure of 0.9 MPa, an air velocity of 22 m / s, a classifying speed of 3250 r / min, and a grinding time of 25 min; plasma treatment was performed with a power of 175 W, a treatment time of 6.5 min, and a treatment temperature of 90℃; the mixture was then mixed with 3% sodium silicate powder by weight of yellow phosphorus slag, with a material moisture content of 13.5%, and stirred and activated at 45℃ and a speed of 350 r / min for 30 min, and dried at 108℃ until the moisture content was ≤0.8%.

[0063] Modification of stainless steel slag: The temperature was raised to 400℃ at 6.5℃ / min and calcined for 30 min. A mixture of oxygen and nitrogen with a volume ratio of 2:3 was introduced. The slag was immersed in a 2.5% Na2CO3 solution and 0.4% sodium tripolyphosphate (sodium tripolyphosphate) was added. The slag was washed at 55℃ and 175 r / min for 1 h. The slag was microwaved at 350 W for 10 min. The slag was dried at 107℃ until the moisture content was ≤0.8%.

[0064] Nano-calcium carbonate modification: 100g of nano-calcium carbonate corresponds to 250mL of mixed solvent, and the dispersion stirring speed is 250r / min; after adding silane coupling agent KH-550, stir at 65℃ and 250r / min for 2.2h; centrifuge at 9000r / min for 12min; dry at 108℃ until the moisture content is ≤0.8%.

[0065] Preparation of composite early strength activator: calcium aluminate cement, silica fume, modified nano calcium carbonate and lithium carbonate are mixed in a mass ratio of 3:2:0.2:0.03. First, the calcium aluminate cement and silica fume are stirred at 450 r / min for 4.0 min. Then, the modified nano calcium carbonate and lithium carbonate are added, and the mixture is stirred at 450 r / min for 2.5 min until uniform.

[0066] Solid component mixing: Add each solid component in the specified order and stir at 550 r / min for 10 min to obtain the basic mixture.

[0067] Slurry preparation: Water-to-binder ratio 0.40. First, add the composite early strength activator and stir for 5 minutes. Then, add the polycarboxylate-based high-efficiency water-reducing agent and polyamide-amine dendritic polymer. Continue stirring at 540 r / min for 20 minutes until the slurry spread reaches 380 mm.

[0068] High-velocity conveying: Steel pipeline pumping is used, with a pumping speed of 2.3 m / s.

[0069] Filling, molding, and curing: Injected into the goaf of the mine, naturally cured at a temperature of 25℃ and a humidity of 88%.

[0070] Comparative Example 1: The preparation and application method of Example 3 is adopted, except that no composite early strength activator is added to the raw materials, while the composition, ratio and process parameters of the other raw materials are the same as those of Example 3.

[0071] Comparative Example 2: The preparation and application method of Example 3 is adopted, except that the nano-calcium carbonate is not modified by silane coupling agent KH-550, while the composition, ratio and process parameters of the other raw materials are the same as those of Example 3.

[0072] Comparative Example 3: The preparation and application method of Example 3 is adopted, except that polyamide-amine dendritic polymer is not added to the raw materials, while the composition, ratio and process parameters of the other raw materials are the same as those of Example 3.

[0073] Comparative Example 4: The preparation and application method of Example 3 is adopted, except that the yellow phosphorus slag is not modified and is directly crushed to 400 mesh before use. The composition, ratio and process parameters of the other raw materials are the same as those of Example 3.

[0074] Performance testing experiments: Experiment 1: Early strength performance and mechanical strength test: 1.1 Experimental Objective: The early strength (1d, 3d) and later strength (28d) of the cementitious materials of Examples 1-3 and Comparative Examples 1-4 under standard curing conditions were tested to verify the effects of composite early strength activator, modified nano-calcium carbonate, polyamide-amine dendritic polymer and modified yellow phosphorus slag on the mechanical properties of cementitious materials. Among them, early strength is the core indicator of early strength cementitious materials, and later strength reflects the long-term stability of materials.

[0075] 1.2 Experimental Principle: Specimens were prepared according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T17671-2021) and cured to the specified age under standard curing conditions (temperature 20±1℃, relative humidity ≥95%). The compressive strength and flexural strength of the specimens were tested using a pressure testing machine. By comparing the strength data of different samples, the influence of each component and modification process on the strength performance of cementitious materials was evaluated.

[0076] 1.3 Experimental Instruments and Reagents: Test instruments: Compression testing machine (range 300kN, accuracy 0.1kN), flexural testing machine (range 50kN, accuracy 0.01kN), cement mortar mixer, standard constant temperature and humidity curing chamber, electronic balance (accuracy 0.001g), test mold (40mm×40mm×160mm). Test reagents: Cementitious materials prepared in Examples 1-3 and Comparative Examples 1-4, deionized water.

[0077] 1.4 Test Methods: Prepare the mortar slurry according to the water-cement ratio of each sample, mix it evenly with a cement mortar mixer, pour the slurry into the mold, vibrate to form, and scrape the surface smooth.

[0078] After molding, the specimens were left to stand for 24 hours in an environment with a temperature of 20±1℃ and a relative humidity of ≥95% before being demolded and then placed in a standard constant temperature and humidity curing chamber for curing to 1 day, 3 days, and 28 days.

[0079] Specimens were taken out at each age and their flexural strength was tested using a flexural testing machine and their compressive strength was tested using a compression testing machine. Three sets of parallel specimens were tested for each specimen at each age, and the average value was taken as the final test result.

[0080] 1.5 Experimental Data: Table 1

[0081] The data from Experiment 1 show that the cementitious materials in Examples 1-3 all exhibit excellent early strength and long-term mechanical strength. The 1-day compressive strength is above 15 MPa, the 3-day compressive strength is above 28 MPa, and the 28-day compressive strength is above 46 MPa.

[0082] Comparing Example 3 with Comparative Example 1, it can be seen that in Comparative Example 1, without the composite early strength activator, the 1-day compressive strength decreased from 17.2 MPa to 8.3 MPa, the 3-day compressive strength decreased from 30.9 MPa to 16.5 MPa, and the 28-day compressive strength decreased from 49.3 MPa to 38.5%, showing a significant decline in performance. The reason is that in the composite early strength activator, calcium aluminate cement can rapidly hydrate to form hydrated calcium aluminate, silica fume and nano-calcium carbonate synergistically fill capillary pores, and lithium carbonate accelerates the hydration process. The combination of these four components forms a synergistic activating effect, significantly improving early strength. Without this component, it is difficult to quickly form strength relying solely on the activity of the solid waste itself, resulting in a significant reduction in both early strength and long-term strength.

[0083] Comparing Example 3 and Comparative Example 2, it can be seen that in Comparative Example 2, the unmodified nano-calcium carbonate exhibited a significant decrease in performance, with its 1-day compressive strength dropping from 17.2 MPa to 12.1 MPa and its 3-day compressive strength decreasing from 30.9 MPa to 22.8 MPa. This is because the nano-calcium carbonate modified with the silane coupling agent KH-550 has a tighter interface with the cementitious material matrix, enabling it to function as a nanofiller and reinforcement. In contrast, the unmodified nano-calcium carbonate is prone to agglomeration and is difficult to disperse uniformly, thus failing to fully exert its reinforcing effect and resulting in a decrease in strength.

[0084] Comparing Example 3 and Comparative Example 3, it can be seen that in Comparative Example 3, the 1-day compressive strength decreased from 17.2 MPa to 13.5 MPa and the 3-day compressive strength decreased from 30.9 MPa to 24.3 MPa, indicating a decline in performance. This is because the polyamide-amine dendritic polymer has a unique dendritic structure that can adsorb onto the particle surface, improve particle size distribution, promote the formation of hydration products, and enhance slurry cohesion, thus improving strength development. Without this component, the hydration process slows down, the slurry structure becomes insufficiently dense, and strength development is inhibited.

[0085] Comparing Example 3 and Comparative Example 4, it can be seen that the unmodified yellow phosphorus slag in Comparative Example 4 exhibited a significant decrease in performance, with its 1-day compressive strength dropping from 17.2 MPa to 11.3 MPa and its 3-day compressive strength decreasing from 30.9 MPa to 20.5 MPa. This is because the glassy structure of the yellow phosphorus slag was destroyed after mechanical activation, plasma etching, and synergistic activation with sodium silicate, resulting in an increase in surface active sites and a significant improvement in reactivity. The unmodified yellow phosphorus slag, with its lower activity, could not fully participate in the hydration reaction and thus could not effectively exert its reinforcing effect, leading to a decrease in strength.

[0086] Experiment 2: Flow performance and adaptability to high-velocity transport: 2.1 Experimental Objective: The flow properties (spreadability, time loss) and high-flow-rate transport resistance of the cementitious slurry in Examples 1-3 and Comparative Examples 1-4 were tested to verify the effects of polycarboxylate-based high-efficiency water-reducing agents, polyamide-amine dendritic polymers and raw material grades on the flow properties and transport adaptability of the slurry. Flow properties and transport adaptability are the core indicators of high-flow-rate filling cementitious materials.

[0087] 2.2 Experimental Principle: The flow properties and stability of the slurry were evaluated by measuring its initial spread and 30-minute spread. A simulated pipeline transport test device was used to measure the transport pressure loss of the slurry at a specified flow rate, reflecting the slurry's adaptability to high-flow-rate transport. The smaller the pressure loss, the better the transport adaptability.

[0088] 2.3 Experimental Instruments and Reagents: Experimental instruments: cement mortar mixer, spreadability tester (base plate size 500mm×500mm, scale accuracy 1mm), electronic balance (accuracy 0.001g), simulated pipeline transportation test device (pipeline inner diameter 50mm, length 10m, equipped with pressure sensor and flow meter), stopwatch. Experimental reagents: cementitious materials prepared in Examples 1-3 and Comparative Examples 1-4, deionized water.

[0089] 2.4 Test Methods: Flow performance test: Prepare the slurry according to the water-cement ratio of each sample. After stirring evenly, immediately pour the slurry into the truncated conical mold (upper diameter 36mm, lower diameter 60mm, height 60mm) of the spread tester, smooth the surface, lift the mold vertically upward to allow the slurry to flow freely, and measure the maximum diameter and vertical diameter of the slurry flow spread after 30 seconds. Take the average value as the initial spread.

[0090] The remaining slurry was placed in a room temperature (20±2℃) environment and allowed to stand for 30 minutes. During this period, it was stirred for 10 seconds every 10 minutes. After 30 minutes, the spread was measured as described above and used as the spread over 30 minutes. The spread loss rate was calculated (spread loss rate = (initial spread - spread over 30 minutes) / initial spread × 100%).

[0091] High-velocity transport adaptability test: The prepared slurry was poured into the hopper of the simulated pipeline transportation test device. The pumping speed was set to 2.3 m / s (consistent with Example 3). The pumping system was started. After the slurry was transported stably, the readings of the pressure sensor in the middle section of the pipeline were recorded. The measurement was repeated 3 times and the average value was taken as the transportation pressure loss.

[0092] 2.5 Experimental Data: Table 2

[0093] The data from Experiment 2 show that the cementitious slurries of Examples 1-3 all exhibit excellent flow properties and high flow rate transport adaptability. The initial expansion is above 360 ​​mm, the expansion loss rate at 30 min is below 7%, and the transport pressure loss is below 0.085 MPa / m.

[0094] Comparing Example 3 with Comparative Example 1, it can be seen that in Comparative Example 1, without the composite early-strength activator, the initial spread decreased from 380 mm to 350 mm, the 30-minute spread loss rate increased from 5.8% to 13.7%, and the conveying pressure loss increased from 0.078 MPa / m to 0.112 MPa / m, resulting in a significant performance decline. This is because the silica fume and nano-calcium carbonate in the composite early-strength activator can optimize the particle size distribution of the slurry, reduce inter-particle frictional resistance, and improve fluidity. Without this component, the particle size distribution of the slurry is unreasonable, agglomeration is exacerbated, flow resistance increases, time-related losses accelerate, and conveying pressure loss increases.

[0095] Comparing Example 3 and Comparative Example 2, it can be seen that in Comparative Example 2, the unmodified nano-calcium carbonate resulted in a decrease in initial spread from 380 mm to 345 mm, an increase in the 30-minute spread loss rate from 5.8% to 13.6%, and an increase in conveying pressure loss from 0.078 MPa / m to 0.108 MPa / m, indicating a significant performance decline. This is because the modified nano-calcium carbonate exhibits good dispersibility and can exert a ball-bearing effect, reducing internal friction in the slurry; while the unmodified nano-calcium carbonate easily agglomerates into large particles, increasing slurry flow resistance, leading to decreased fluidity, worsened stability over time, and increased conveying pressure loss.

[0096] Comparing Example 3 and Comparative Example 3, it can be seen that in Comparative Example 3, the initial spread decreased from 380 mm to 320 mm after the polyamide-amine dendritic polymer was missing. The 30-minute spread loss rate increased from 5.8% to 17.2%, and the conveying pressure loss increased from 0.078 MPa / m to 0.125 MPa / m, indicating a significant performance decline. This is because the polyamide-amine dendritic polymer has good dispersibility and lubrication properties. It can adsorb onto the surface of solid particles, forming electrostatic repulsion and steric hindrance effects, preventing particle agglomeration and maintaining the long-term fluidity of the slurry. Without this component, the interparticle attraction increases, making agglomeration and sedimentation more likely, leading to deterioration of flow properties and a significant increase in conveying resistance.

[0097] Comparing Example 3 and Comparative Example 4, it can be seen that in Comparative Example 4, the unmodified yellow phosphorus slag exhibited a significant decrease in performance: the initial expansion decreased from 380 mm to 330 mm, the 30-minute expansion loss rate increased from 5.8% to 15.2%, and the conveying pressure loss increased from 0.078 MPa / m to 0.118 MPa / m. This is because the modified yellow phosphorus slag has increased surface activity and better compatibility with water and other components, improving the homogeneity and fluidity of the slurry. Unmodified yellow phosphorus slag, on the other hand, has a more inert surface, resulting in weaker bonding with other components, making it prone to localized agglomeration. This leads to increased slurry flow resistance, decreased stability over time, and reduced conveying adaptability.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0099] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An early-strength solid waste-based cementitious material suitable for high-flow-rate filling, characterized in that, By weight percentage, the raw material composition includes: 28-32 parts yellow phosphorus slag, 16-22 parts blast furnace slag, 12-18 parts stainless steel slag, 10-13 parts fly ash, 6-10 parts phosphogypsum, 4-7 parts coal gangue, 3-5 parts blast furnace slag, 1.5-2.5 parts composite early strength activator, 0.9-1.2 parts polycarboxylate-based high-efficiency water-reducing agent, and 0.25-0.35 parts polyamide-amine dendritic polymer; The composite early strength activator is composed of calcium aluminate cement, silica fume, nano calcium carbonate and lithium carbonate in a mass ratio of 3:2:0.2:0.03; The water-cement ratio of the cementitious material is 0.35-0.45; The nano-calcium carbonate has a particle size of 50-100 nm and is modified with silane coupling agent KH-550.

2. The cementitious material according to claim 1, characterized in that, The polyamide-amine dendritic polymer is of generation 3.0G, with a number average molecular weight of 14,000-16,000 Da, a solid content of ≥98%, an amine value of 4.5-5.5 mmol / g, a water solubility of ≥99%, and a glass transition temperature of -15℃ to -5℃.

3. The cementitious material according to claim 1, characterized in that, The yellow phosphorus slag undergoes modification treatment, and the modification steps include: S1, the yellow phosphorus slag is mechanically activated by ultra-fine grinding using an air jet mill. The grinding pressure is 0.85-0.95MPa, the air velocity is 20-24m / s, the classification speed is 3000-3500r / min, the grinding time is 20-30min, and the particle size is 400 mesh, which initially breaks the glass structure. S2, the crushed yellow phosphorus slag is sent into a low-temperature plasma treatment device, and etched by a mixed plasma of argon and oxygen with a volume ratio of 4:

1. The plasma power is 150-200W, the treatment time is 5-8min, and the treatment temperature is controlled at 80-100℃. S3. The plasma-treated yellow phosphorus slag is mixed with 2%-4% sodium silicate powder by weight of the yellow phosphorus slag. Deionized water is added to adjust the moisture content of the material to 12%-15%. The mixture is stirred and activated for 25-35 minutes at 40-50℃ and 320-380r / min to complete the synergistic activation of sodium silicate. Finally, it is dried at 105-110℃ until the moisture content is ≤0.8% to obtain the modified yellow phosphorus slag.

4. The cementitious material according to claim 1, characterized in that, The stainless steel slag undergoes a three-stage composite modification treatment, the modification steps of which include: The first step is to heat the stainless steel slag to 380-420℃ at a heating rate of 6-7℃ / min, hold it at that temperature for 30 minutes, with a holding time fluctuation of ≤1.5 minutes, and introduce a mixture of oxygen and nitrogen in a volume ratio of 2:3 during the roasting process. The second step involves immersing the calcined stainless steel slag in a Na2CO3 solution with a mass concentration of 2.2%-2.8%, adding 0.3%-0.5% sodium tripolyphosphate as an immersion aid, and immersing for 1 hour at 52-58℃ and 160-190 r / min. The third step involves filtering and washing the alkali-leached stainless steel slag until it is neutral, then using microwave equipment for auxiliary activation. The microwave power is 300-400W, the microwave time is 8-12 minutes, and the slag is stirred intermittently during the microwave process, stirring for 30 seconds every 2 minutes at a stirring speed of 150 r / min. Finally, the slag is dried at 106-109℃ until the moisture content is ≤0.8%, thus obtaining the modified stainless steel slag.

5. The cementitious material according to claim 1, characterized in that, The polycarboxylate superplasticizer is a polyether-type polycarboxylate superplasticizer with a solid content of 42%-48%.

6. The cementitious material according to claim 1, characterized in that, The slag has a particle size of 360-390 mesh, the fly ash has a particle size of 310-340 mesh, and the phosphogypsum has a particle size of 310-340 mesh.

7. The cementitious material according to claim 1, characterized in that, The mixing sequence of the composite early strength activator is as follows: first, mix calcium aluminate cement and silica fume at a speed of 400-500 r / min for 3.5-4.5 min, then add modified nano calcium carbonate and lithium carbonate, and continue to stir at a speed of 400-500 r / min for 2.2-2.8 min until uniform.

8. The cementitious material according to claim 1, characterized in that, The modification steps of the silane coupling agent KH-550 include: first, mixing anhydrous ethanol and glycerol at a volume ratio of 8:2 to prepare a mixed solvent; then, dispersing nano-calcium carbonate in the mixed solvent, with 220-280 mL of mixed solvent for every 100 g of nano-calcium carbonate; stirring until no obvious agglomeration of nano-calcium carbonate, at a stirring speed of 220-280 r / min for 30 min; adding the silane coupling agent KH-550; stirring at 62-68℃ and 220-280 r / min for 2.0-2.5 h; centrifuging using a high-speed centrifuge at a speed of 8000-10000 r / min for 10-15 min; and drying at 105-110℃ until the moisture content is ≤0.8% to obtain modified nano-calcium carbonate.

9. A method for applying the cementitious material as described in any one of claims 1-8 in mine backfilling, characterized in that, Includes the following steps: S1. Raw material pretreatment: Modification treatment of yellow phosphorus slag, stainless steel slag, and nano-calcium carbonate is completed respectively; crushing and screening treatment of coal gangue, blast furnace slag, slag, fly ash, and residual phosphogypsum is completed to ensure that the moisture content of each solid raw material is ≤0.8%; S2. Solid component mixing: Add each solid component into the mixing equipment in the following order: slag, fly ash, blast furnace slag, coal gangue, residual phosphogypsum, modified yellow phosphorus slag, modified stainless steel slag, and modified nano calcium carbonate. Mix at a speed of 520-580 r / min for 8-12 minutes to obtain the basic mixture. S3. Slurry preparation: Add a composite early strength activator, a polycarboxylate-based high-efficiency water-reducing agent, a polyamide-amine dendritic polymer and water to the basic mixture. The amount of water added is such that the water-cement ratio of the cementitious material is 0.35-0.

45. Continue stirring at a speed of 500-580 r / min for 16-25 min until the slurry spread is 360-400 mm to prepare the filling slurry. S4. High-velocity conveying: Steel pipeline pumps are used to deliver the filling slurry at a speed of 1.8-2.8 m / s; S5. Filling, molding and curing: The slurry is injected into the goaf of the mine to complete the filling and molding. Natural curing is adopted, with a curing temperature of 18-32℃ and a curing humidity of ≥85%.

10. The application method according to claim 9, characterized in that, In step S3, the composite early strength activator, polycarboxylate-based high-efficiency water-reducing agent, and polyamide-amine dendritic polymer are added in steps. First, the composite early strength activator is added and stirred for 5 minutes, then the polycarboxylate-based high-efficiency water-reducing agent and polyamide-amine dendritic polymer are added, and stirring is continued until the slurry expansion is 360-400 mm.

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