Coal mine filling paste material based on sulfur-resistant curing agent and preparation method thereof

Abstract

The invention relates to the technical field of paste materials, in particular to a coal mine filling paste material based on a sulfur-resistant curing agent and a preparation method thereof.The coal mine filling paste material is prepared by using industrial waste residues such as steel slag, red mud, mineral powder, carbide slag and desulfurized gypsum to partially replace cement to serve as a curing agent, using crushed and screened coal gangue as aggregate and using composite coconut fiber as a modifier. A phosphorus-containing polycarboxylic acid water reducing agent and an alkali-free accelerator are introduced for preparation; the preparation method comprises the following steps: performing sulfhydrylation on coconut shell fibers by using 3-sulfydryl propyl trimethoxy silane, and then grafting double-bond-containing branched phosphamide on the surfaces of the coconut shell fibers by using a sulfydryl-double bond light click reaction; according to the present invention, the phosphorus-containing polycarboxylic acid water reducing agent is prepared through free radical copolymerization by using the double bond-containing branched phosphamide as the phosphorus-containing group provider, such that the sulfate resistance of the filling paste material is significantly improved while the good workability and the good mechanical property of the filling paste material are maintained so as to substantially improve the durability of the filling paste material;

Description

Technical Field

[0001] The invention relates to the technical field of paste materials, in particular to a coal mine filling paste material based on a sulfur-resistant curing agent and a preparation method thereof. Background Art

[0002] The development of backfill coal mining technology is beneficial to the protection of the ecological environment. Coal mine backfill paste material refers to the backfill material transported to the coal mine goaf during the mining process in order to control surface subsidence, protect the mining environment and improve resource utilization. It is usually made of coal gangue, waste rock and other aggregates, and is mixed with cement, blast furnace slag, fly ash and other materials with water for activation.

[0003] Coal mine filling paste material is the core of filling mining technology and is closely related to the filling body quality and mining economic benefits. The accumulation of high concentrations of sulfate ions in mine water has a significant impact on the normal hydration reaction of materials such as cement and blast furnace slag in general paste materials. Under the action of sulfate, the filling body after solidification and hardening will also be severely corroded and damaged, resulting in instability and cracking of the filling body. Summary of the Invention

[0004] The object of the present invention is to provide a coal mine filling paste material based on an anti-sulfur curing agent and a preparation method thereof, so as to solve the problems in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing a coal mine filling paste material based on an anti-sulfur curing agent comprises the following steps:

[0007] S1: Mixing coal gangue, industrial waste mixture, cement and activator to obtain mixture A;

[0008] S2: mixing a phosphorus-containing polycarboxylate water reducer, composite coconut shell fiber, an accelerating setting agent, and water to obtain a mixture B;

[0009] S3: Mixing the mixture A and the mixture B to obtain a coal mine filling paste material based on an anti-sulfur curing agent.

[0010] Furthermore, the industrial waste residue mixture is obtained by compounding steel slag, red mud, mineral powder, carbide slag and desulfurization gypsum in a mass ratio of 3:3:2:1:1. The particle size of steel slag and red mud is 2-4 μm, and the particle size of mineral powder, carbide slag and desulfurization gypsum is 1-2 μm.

[0011] Furthermore, the water is one of deionized water, ultrapure water, and tap water.

[0012] Furthermore, the quick-setting agent is obtained by compounding aluminum sulfate 18hydrate, diethanolamine, 4-methylphenol, water, and lysine in a mass ratio of 58:6:0.1:35:0.1.

[0013] Furthermore, the activator is one or more of sodium silicate, sodium carbonate, and sodium hydroxide.

[0014] Furthermore, the raw material composition of the filling paste material is, by weight, 53-73 parts of coal gangue, 24-32 parts of industrial waste mixture, 5-10 parts of cement, 1-3 parts of activator, 1-2 parts of phosphorus-containing polycarboxylic acid water reducer, 3-6 parts of composite coconut shell fiber, 0.5-1 part of accelerating agent, and 58-68 parts of water.

[0015] Further, the preparation of composite coconut shell fiber comprises the following steps:

[0016] 1) coconut fiber and sodium hydroxide solution are mixed, stirred for 1-2h, washed, and dried to obtain pre-treated coconut fiber;

[0017] 2) Under a nitrogen atmosphere, anhydrous ethanol, deionized water, 3-mercaptopropyltrimethoxysilane, and aqueous ammonia were mixed, heated to 60-70° C. in a water bath for 2-3 hours, stirred for 20-30 minutes, and pretreated coconut shell fiber was added. The mixture was stirred at 18-25° C. for 5-6 hours, washed with ethanol and deionized water for 3-5 times, and dried to obtain thiol-modified coconut shell fiber;

[0018] 3) The thiolated coconut shell fiber, N, N-dimethylformamide and a photoinitiator are mixed, and double-bond branched phosphoramide and N, N-dimethylformamide are added and mixed, the mixture is heated to 50-60° C., treated with ultraviolet light, washed and dried to obtain composite coconut shell fiber.

[0019] Furthermore, the working conditions of the ultraviolet light treatment are: irradiation under 278nm ultraviolet light for 5-6h.

[0020] Furthermore, the preparation of the phosphorus-containing polycarboxylate water-reducing agent comprises the following steps:

[0021] Under a nitrogen atmosphere, methyl allyl polyoxyethylene ether and deionized water are mixed, the temperature is raised to 58-62°C, ammonium persulfate is added, a mixture of acrylic acid, double-bond branched phosphoramide, and deionized water is added, and the mixture is stirred for 2-3 hours. A mixture of ascorbic acid, 3-mercaptopropionic acid, and deionized water is added, and the mixture is stirred for 3-4 hours. The mixture is cooled and the pH is adjusted to neutral to obtain a phosphorus-containing polycarboxylate water reducer.

[0022] Furthermore, the mass ratio of methyl allyl polyoxyethylene ether, acrylic acid, and double-bond branched phosphoramide is 24:2.9:3.2.

[0023] Furthermore, the preparation of the double-bond branched phosphoramide comprises the following steps:

[0024] (1) Under a nitrogen atmosphere, diethanolamine and dioxane are mixed, a mixture of phosphorus oxychloride and dioxane is added at 0-5°C, the temperature is raised to 38-42°C and the temperature is kept warm for 22-24 hours, a mixture of triethylamine and dioxane is added, the temperature is raised to 78-82°C and the temperature is kept warm for 22-24 hours, vacuum distillation is performed, deionized water is added, sodium hydroxide is added, stirring, suction filtration, vacuum distillation is performed, methanol is added, suction filtration, vacuum distillation is performed, and drying is performed to obtain a polyhydroxy branched phosphoramide;

[0025] (2) Under a nitrogen atmosphere, polyhydroxy branched phosphoramide and N,N-dimethylformamide are mixed, anhydrous potassium carbonate is added, and a mixture of acryloyl chloride and N,N-dimethylformamide is added in an ice bath. The mixture is stirred in an ice bath for 1-2 hours, kept warm in the dark for 22-23 hours, filtered, and rotary evaporated to obtain a branched phosphoramide containing a double bond.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention provides a coal mine filling paste material based on a sulfur-resistant curing agent and a preparation method thereof. The material partially replaces cement with industrial waste residues such as steel slag, red mud, mineral powder, carbide slag, and desulfurized gypsum as a curing agent, uses crushed and screened coal gangue as aggregate, uses composite coconut shell fiber as a modifier, and introduces a phosphorus-containing polycarboxylate water reducer and an alkali-free quick-setting agent to prepare a coal mine filling paste material with high strength, strong sulfate resistance, and high stability, thereby turning waste into treasure.

[0028] Common coal mine filling paste materials are prone to internal crack expansion and increased porosity under the erosion of sulfate solutions. In the present invention, industrial waste residues such as steel slag, red mud, mineral powder, carbide slag, and desulfurization gypsum are selected. By controlling the ratio and particle size and utilizing the complementary advantages of the volcanic ash effect, micro-aggregate filling effect, and alkali excitation effect in their components, the density of the paste material is increased, the intrusion speed of the sulfate solution is slowed down, the paste acts as an anti-sulfate curing agent, and the durability of the paste material is improved.

[0029] Coconut shell fiber, which is easily available, environmentally friendly, and has excellent mechanical properties, is introduced as a modifier into the filling paste material to improve the mechanical strength of the filling paste material. In order to improve the uniformity of the dispersion of coconut shell fiber in the filling paste material, the coconut shell fiber is first thiolated with 3-mercaptopropyltrimethoxysilane, and then a double-bond branched phosphoramide is grafted onto its surface by a photoclick reaction of the mercapto group-double bond to improve the bonding strength between the coconut shell fiber and the filling paste material. The double-bond branched phosphoramide is prepared by first synthesizing polyhydroxy branched phosphoramide using trichlorophosphorus and diethanolamine as raw materials, and then introducing carbon-carbon double bonds through acryloyl chloride. The introduction of multiple phosphorus-containing groups can greatly improve the sulfate resistance of the filling paste material, further improving the durability and stability of the filling paste material.

[0030] In order to adjust the viscosity of the filling paste material and further improve the sulfate resistance of the filling paste material, the present invention uses double-bond branched phosphoramide as a phosphorus-containing group donor and prepares a phosphorus-containing polycarboxylate water reducer through free radical copolymerization. This significantly improves the sulfate resistance of the filling paste material while maintaining good workability and mechanical properties, thereby greatly improving the durability of the filling paste material. DETAILED DESCRIPTION

[0031] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] It should be noted that if the embodiments of the present invention involve directional indications such as up, down, left, right, front, and back, such directional indications are only used to explain a specific posture, such as the relative position relationship between components, the movement status, etc. If the specific posture changes, the directional indication will also change accordingly. In addition, the technical solutions between the various embodiments may be combined with each other, but they must be based on the premise that they can be implemented by ordinary technicians in this field. If the combination of technical solutions is mutually inconsistent or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0033] The technical solutions of the present invention are further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely used to explain the present invention and are not intended to limit the present invention.

[0034] Example 1: A method for preparing a coal mine filling paste material based on an anti-sulfur curing agent, comprising the following steps:

[0035] S1: Mixing coal gangue, industrial waste mixture, cement and activator to obtain mixture A;

[0036] S2: mixing a phosphorus-containing polycarboxylate water reducer, composite coconut shell fiber, an accelerating setting agent, and deionized water to obtain a mixture B;

[0037] The industrial waste residue mixture is obtained by mixing steel slag, red mud, mineral powder, carbide slag and desulfurization gypsum in a mass ratio of 3:3:2:1:1. The particle size of the steel slag and red mud is 2 μm, and the particle size of the mineral powder, carbide slag and desulfurization gypsum is 1 μm.

[0038] The accelerating agent is prepared by mixing aluminum sulfate 18hydrate, diethanolamine, 4-methylphenol, deionized water and lysine in a mass ratio of 58:6:0.1:35:0.1; the activator is sodium silicate;

[0039] The raw material composition of the filling paste material is as follows: 53 parts of coal gangue, 24 parts of industrial waste mixture, 5 parts of cement, 1 part of activator, 1 part of phosphorus-containing polycarboxylate water reducer, 3 parts of composite coconut shell fiber, 0.5 parts of accelerating agent, and 58 parts of deionized water.

[0040] The preparation of the composite coconut shell fiber comprises the following steps:

[0041] 1) 10 g of coconut shell fiber and 400 mL of a 15% sodium hydroxide solution were mixed, stirred for 1 h, washed, and dried to obtain pretreated coconut shell fiber;

[0042] 2) Under a nitrogen atmosphere, 60 mL of anhydrous ethanol, 10.5 mL of deionized water, 0.42 g of 3-mercaptopropyltrimethoxysilane, and 0.6 mL of ammonia water were mixed, heated to 60 ° C in a water bath for 3 hours, stirred for 20 minutes, and 1 g of pretreated coconut shell fiber was added. The mixture was stirred at 18 ° C for 6 hours, washed with ethanol and deionized water 3-5 times, and dried to obtain thiolated coconut shell fiber;

[0043] 3) 3.2g of mercaptolated coconut fiber, 60mL of N,N-dimethylformamide, and 46mg of photoinitiator 1173 were mixed, 1.4g of double-bond branched phosphoramide and 25mL of N,N-dimethylformamide were added, the mixture was warmed to 50°C, and the mixture was irradiated with 278nm ultraviolet light for 5h, washed, and dried to obtain composite coconut fiber;

[0044] The preparation of the phosphorus-containing polycarboxylate water-reducing agent comprises the following steps:

[0045] Under a nitrogen atmosphere, 24 g of methyl allyl polyoxyethylene ether and 200 mL of deionized water were mixed, the temperature was raised to 58 ° C, 480 mg of ammonium persulfate was added, 2.9 g of acrylic acid, 3.2 g of double-bond branched phosphoramide, and a mixture of 50 mL of deionized water were added, and the mixture was stirred for 2 h. 160 mg of ascorbic acid, 160 mg of 3-mercaptopropionic acid, and a mixture of 10 mL of deionized water were added, and the mixture was stirred for 3 h. The mixture was cooled and the pH was adjusted to neutral to obtain a phosphorus-containing polycarboxylate water reducer;

[0046] The preparation of the double-bond branched phosphoramide comprises the following steps:

[0047] (1) Under a nitrogen atmosphere, 21 g of diethanolamine and 100 mL of dioxane were mixed, and a mixture of 15.4 g of phosphorus oxychloride and 25 mL of dioxane was added at 0° C., and the mixture was heated to 38° C. and kept warm for 24 h. A mixture of 20 g of triethylamine and 25 mL of dioxane was added, and the mixture was heated to 78° C. and kept warm for 24 h. The mixture was distilled under reduced pressure, 10 mL of deionized water was added, 8 g of sodium hydroxide was added, and the mixture was stirred, filtered, and distilled under reduced pressure. 25 mL of methanol was added, filtered, distilled under reduced pressure, and dried to obtain a polyhydroxy branched phosphoramide;

[0048] (2) Under a nitrogen atmosphere, 2.4 g of polyhydroxy branched phosphoramide and 80 mL of N,N-dimethylformamide were mixed, 0.3 g of anhydrous potassium carbonate was added, and a mixture of 0.3 g of acryloyl chloride and 20 mL of N,N-dimethylformamide was added in an ice bath. The mixture was stirred in an ice bath for 1 h, kept warm in the dark for 22 h, filtered, and rotary evaporated to obtain a double-bond branched phosphoramide;

[0049] S3: Mixing the mixture A and the mixture B to obtain a coal mine filling paste material based on an anti-sulfur curing agent.

[0050] Example 2: A method for preparing a coal mine filling paste material based on an anti-sulfur curing agent, comprising the following steps:

[0051] S1: Mixing coal gangue, industrial waste mixture, cement and activator to obtain mixture A;

[0052] S2: mixing a phosphorus-containing polycarboxylate water reducer, composite coconut shell fiber, an accelerating setting agent, and deionized water to obtain a mixture B;

[0053] The industrial waste residue mixture is obtained by mixing steel slag, red mud, mineral powder, carbide slag and desulfurization gypsum in a mass ratio of 3:3:2:1:1. The particle sizes of the steel slag and red mud are 2 μm, and the particle sizes of the mineral powder, carbide slag and desulfurization gypsum are 1 μm.

[0054] The accelerating agent is prepared by mixing aluminum sulfate 18hydrate, diethanolamine, 4-methylphenol, deionized water and lysine in a mass ratio of 58:6:0.1:35:0.1; the activator is sodium silicate;

[0055] The raw material composition of the filling paste material is as follows: 63 parts of coal gangue, 28 parts of industrial waste mixture, 7 parts of cement, 2 parts of activator, 1.5 parts of phosphorus-containing polycarboxylate water reducer, 5 parts of composite coconut shell fiber, 0.8 parts of accelerating agent, and 60 parts of deionized water.

[0056] The preparation of the composite coconut shell fiber comprises the following steps:

[0057] 1) 10 g of coconut shell fiber and 400 mL of a 15% sodium hydroxide solution were mixed, stirred for 1.5 h, washed, and dried to obtain pretreated coconut shell fiber;

[0058] 2) Under a nitrogen atmosphere, 60 mL of anhydrous ethanol, 10.5 mL of deionized water, 0.42 g of 3-mercaptopropyltrimethoxysilane, and 0.6 mL of aqueous ammonia were mixed, heated to 65 ° C in a water bath for 2.5 h, stirred for 25 min, 1 g of pretreated coconut shell fiber was added, stirred at 20 ° C for 5.5 h, washed four times with ethanol and deionized water, and dried to obtain thiolated coconut shell fiber;

[0059] 3) 3.2g of mercaptolated coconut fiber, 60mL of N,N-dimethylformamide, and 46mg of photoinitiator 1173 were mixed, 1.4g of double-bond branched phosphoramide and 25mL of N,N-dimethylformamide were added, the mixture was warmed to 55°C, and the mixture was irradiated with 278nm ultraviolet light for 5-6h, washed, and dried to obtain composite coconut fiber;

[0060] The preparation of the phosphorus-containing polycarboxylate water-reducing agent comprises the following steps:

[0061] Under a nitrogen atmosphere, 24 g of methyl allyl polyoxyethylene ether and 200 mL of deionized water were mixed, the temperature was raised to 60 ° C, 480 mg of ammonium persulfate was added, 2.9 g of acrylic acid, 3.2 g of double-bond branched phosphoramide, and a mixture of 50 mL of deionized water were added, and the mixture was stirred for 2.5 h. 160 mg of ascorbic acid, 160 mg of 3-mercaptopropionic acid, and a mixture of 10 mL of deionized water were added, and the mixture was stirred for 3.5 h. The mixture was cooled and the pH was adjusted to neutral to obtain a phosphorus-containing polycarboxylate water reducer;

[0062] The preparation of the double-bond branched phosphoramide comprises the following steps:

[0063] (1) Under a nitrogen atmosphere, 21 g of diethanolamine and 100 mL of dioxane were mixed, and a mixture of 15.4 g of phosphorus oxychloride and 25 mL of dioxane was added at 3° C., and the mixture was heated to 40° C. and kept warm for 23 h. A mixture of 20 g of triethylamine and 25 mL of dioxane was added, and the mixture was heated to 80° C. and kept warm for 23 h. The mixture was distilled under reduced pressure, 10 mL of deionized water was added, 8 g of sodium hydroxide was added, and the mixture was stirred, filtered, and distilled under reduced pressure. 25 mL of methanol was added, filtered, distilled under reduced pressure, and dried to obtain a polyhydroxy branched phosphoramide;

[0064] (2) Under a nitrogen atmosphere, 2.4 g of polyhydroxy branched phosphoramide and 80 mL of N,N-dimethylformamide were mixed, 0.3 g of anhydrous potassium carbonate was added, and a mixture of 0.3 g of acryloyl chloride and 20 mL of N,N-dimethylformamide was added in an ice bath. The mixture was stirred in an ice bath for 1.5 h, kept warm in the dark for 22.5 h, filtered, and rotary evaporated to obtain a double-bond branched phosphoramide;

[0065] S3: Mixing the mixture A and the mixture B to obtain a coal mine filling paste material based on an anti-sulfur curing agent.

[0066] Example 3: A method for preparing a coal mine filling paste material based on an anti-sulfur curing agent, comprising the following steps:

[0067] S1: Mixing coal gangue, industrial waste mixture, cement and activator to obtain mixture A;

[0068] S2: mixing a phosphorus-containing polycarboxylate water reducer, composite coconut shell fiber, an accelerating setting agent, and deionized water to obtain a mixture B;

[0069] The industrial waste residue mixture is obtained by mixing steel slag, red mud, mineral powder, carbide slag and desulfurization gypsum in a mass ratio of 3:3:2:1:1. The particle sizes of the steel slag and red mud are 2 μm, and the particle sizes of the mineral powder, carbide slag and desulfurization gypsum are 1 μm.

[0070] The accelerating agent is prepared by mixing aluminum sulfate 18hydrate, diethanolamine, 4-methylphenol, deionized water and lysine in a mass ratio of 58:6:0.1:35:0.1; the activator is sodium silicate;

[0071] The raw material composition of the filling paste material is as follows: 73 parts of coal gangue, 32 parts of industrial waste mixture, 10 parts of cement, 3 parts of activator, 2 parts of phosphorus-containing polycarboxylate water reducer, 6 parts of composite coconut shell fiber, 1 part of accelerating agent, and 68 parts of deionized water.

[0072] The preparation of the composite coconut shell fiber comprises the following steps:

[0073] 1) 10 g of coconut shell fiber and 400 mL of a 15% sodium hydroxide solution were mixed, stirred for 1-2 h, washed, and dried to obtain pretreated coconut shell fiber;

[0074] 2) Under a nitrogen atmosphere, 60 mL of anhydrous ethanol, 10.5 mL of deionized water, 0.42 g of 3-mercaptopropyltrimethoxysilane, and 0.6 mL of aqueous ammonia were mixed, heated to 70 ° C. in a water bath for 2 h, stirred for 30 min, 1 g of pretreated coconut shell fiber was added, stirred at 25 ° C. for 5 h, washed with ethanol and deionized water 3-5 times in sequence, and dried to obtain thiolated coconut shell fiber;

[0075] 3) 3.2g of mercaptolated coconut fiber, 60mL of N,N-dimethylformamide, and 46mg of photoinitiator 1173 were mixed, 1.4g of double-bond branched phosphoramide and 25mL of N,N-dimethylformamide were added, the mixture was warmed to 60°C, and the mixture was irradiated with 278nm ultraviolet light for 5h, washed, and dried to obtain composite coconut fiber;

[0076] The preparation of the phosphorus-containing polycarboxylate water-reducing agent comprises the following steps:

[0077] Under a nitrogen atmosphere, 24 g of methyl allyl polyoxyethylene ether and 200 mL of deionized water were mixed, the temperature was raised to 62 ° C, 480 mg of ammonium persulfate was added, 2.9 g of acrylic acid, 3.2 g of double-bond branched phosphoramide, and a mixture of 50 mL of deionized water were added, and the mixture was stirred for 3 h. 160 mg of ascorbic acid, 160 mg of 3-mercaptopropionic acid, and 10 mL of deionized water were added, and the mixture was stirred for 4 h. The mixture was cooled and the pH was adjusted to neutral to obtain a phosphorus-containing polycarboxylate water reducer;

[0078] The preparation of the double-bond branched phosphoramide comprises the following steps:

[0079] (1) Under a nitrogen atmosphere, 21 g of diethanolamine and 100 mL of dioxane were mixed, and a mixture of 15.4 g of phosphorus oxychloride and 25 mL of dioxane was added at 5° C., and the mixture was heated to 42° C. and kept warm for 22 h. A mixture of 20 g of triethylamine and 25 mL of dioxane was added, and the mixture was heated to 82° C. and kept warm for 22 h. The mixture was distilled under reduced pressure, 10 mL of deionized water was added, 8 g of sodium hydroxide was added, and the mixture was stirred, filtered, and distilled under reduced pressure. 25 mL of methanol was added, filtered, distilled under reduced pressure, and dried to obtain a polyhydroxy branched phosphoramide;

[0080] (2) Under a nitrogen atmosphere, 2.4 g of polyhydroxy branched phosphoramide and 80 mL of N,N-dimethylformamide were mixed, 0.3 g of anhydrous potassium carbonate was added, and a mixture of 0.3 g of acryloyl chloride and 20 mL of N,N-dimethylformamide was added in an ice bath. The mixture was stirred in an ice bath for 2 h, kept warm in the dark for 23 h, filtered, and rotary evaporated to obtain a double-bond branched phosphoramide;

[0081] S3: Mixing the mixture A and the mixture B to obtain a coal mine filling paste material based on an anti-sulfur curing agent.

[0082] Comparative Example 1: Taking Example 3 as the control group, coconut shell fiber was used to replace the composite coconut shell fiber, and other processes were normal.

[0083] Comparative Example 2: Example 3 was used as the control group, and no double-bond branched phosphoramide was prepared, and the other processes were normal.

[0084] Sources of raw materials used (for demonstration purposes only):

[0085] The main chemical composition of coal gangue (particle size of 20 μm) is as follows: by mass fraction, silicon dioxide 60.2%, calcium oxide 2.6%, aluminum oxide 18.3%, iron oxide 4.6%, magnesium oxide 1.5%, potassium oxide 0.6%, sulfur trioxide 0.2%, sodium oxide 0.7%, purchased from the market;

[0086] The main chemical composition of red mud is as follows: by mass fraction, silicon dioxide 11.5%, calcium oxide 20.2%, aluminum oxide 32.2%, iron oxide 6.9%, magnesium oxide 1.1%, potassium oxide 0.5%, titanium oxide 3.3%, sodium oxide 3.8%, purchased from the market;

[0087] The main chemical composition of steel slag is as follows: by mass fraction, silicon dioxide 17.9%, calcium oxide 19.7%, aluminum oxide 8.8%, iron oxide 23.1%, magnesium oxide 13.9%, potassium oxide 0.2%, sulfur trioxide 0.6%, phosphorus pentoxide 0.7%, commercially available;

[0088] The main chemical composition of the mineral powder is as follows: by mass fraction, silicon dioxide 31.1%, calcium oxide 36.8%, aluminum oxide 13.6%, iron oxide 4.2%, magnesium oxide 7.0%, potassium oxide 0.2%, sodium oxide 0.1%, sulfur trioxide 0.5%, titanium oxide 0.7%, purchased from the market;

[0089] The main chemical composition of carbide slag is: calcium oxide 65.8%, silicon oxide 3.2%, aluminum oxide 1%, sodium oxide 0.2%, commercially available;

[0090] The main chemical composition of desulfurization gypsum is as follows: by mass fraction, silicon dioxide 4.1%, calcium oxide 33.8%, aluminum oxide 0.7%, iron oxide 0.6%, magnesium oxide 0.9%, potassium oxide 0.1%, sodium oxide 0.4%, sulfur trioxide 45.1%, commercially available;

[0091] Coconut shell fiber (2 μm, Hainan), commercially available; cement (PO42.5 ordinary Portland cement): Conch Cement; aluminum sulfate 18hydrate A489714, diethanolamine D112360, 4-methylphenol C108249, lysine L163872, 3-mercaptopropyltrimethoxysilane M100619, photoinitiator 1173H110280, methyl allyl polyoxyethylene ether A303301, acrylic acid A103526, diethanolamine D112360, phosphorus oxychloride P475214, acryloyl chloride A104614; Aladdin reagent; sodium hydroxide, ethanol, ammonia water, dioxane, ammonium persulfate, ascorbic acid, 3-mercaptopropionic acid, methanol, N,N-dimethylformamide, potassium carbonate, sodium silicate, analytical grade, commercially available.

[0092] Performance testing:

[0093] The samples prepared in the examples and comparative examples were tested;

[0094] Compressive strength: The specimen size is 40mm×40mm×40mm. After 28 days of curing, the compressive strength is tested using an electronic universal testing machine.

[0095] Durability: A 40 mm cube was immersed in a 3% anhydrous sodium sulfate aqueous solution and kept at 25°C for 7 days. The compressive strength was then tested again and compared with the compressive strength of the cube without the sodium sulfate aqueous solution. A compressive strength change of 0-1% (including 1%) was considered excellent, while a change of 0-1% was considered unqualified. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] The present invention provides a coal mine filling paste material based on a sulfur-resistant curing agent and a preparation method thereof. The material partially replaces cement with industrial waste residues such as steel slag, red mud, mineral powder, carbide slag, and desulfurized gypsum as a curing agent, uses crushed and screened coal gangue as aggregate, uses composite coconut shell fiber as a modifier, and introduces a phosphorus-containing polycarboxylate water reducer and an alkali-free quick-setting agent to prepare a coal mine filling paste material with high strength, strong sulfate resistance, and high stability, thereby turning waste into treasure.

[0099] By comparing Example 3 with Comparative Example 1, it can be seen that coconut shell fiber, which is easily available, environmentally friendly, and has excellent mechanical properties, is introduced as a modifier into the filling paste material to improve the mechanical strength of the filling paste material. In order to improve the uniformity of the dispersion of coconut shell fiber in the filling paste material, the coconut shell fiber is first thiolated with 3-mercaptopropyltrimethoxysilane, and then a double-bond-containing branched phosphoramide is grafted on its surface by a photoclick reaction of the mercapto group-double bond to improve the bonding strength between the coconut shell fiber and the filling paste material. The double-bond-containing branched phosphoramide is prepared by first synthesizing polyhydroxy branched phosphoramide using phosphorus oxychloride and diethanolamine as raw materials, and then introducing carbon-carbon double bonds by acryloyl chloride. The introduction of multiple phosphorus-containing groups can greatly improve the sulfate resistance of the filling paste material, and further improve the durability and stability of the filling paste material.

[0100] By comparing Example 3 with Comparative Example 2, it can be seen that in order to adjust the viscosity of the filling paste material and further improve the sulfate resistance of the filling paste material, the present invention uses double-bond branched phosphoramide as a phosphorus-containing group provider and prepares a phosphorus-containing polycarboxylate water-reducing agent through free radical copolymerization. While maintaining good workability and mechanical properties of the filling paste material, its clay resistance and sulfate resistance are significantly improved, thereby greatly improving the durability of the filling paste material.

[0101] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention specification under the inventive concept of the present invention, or any direct / indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a coal mine filling paste material based on an anti-sulfur curing agent, characterized in that: The following steps are involved: S1: Mixing coal gangue, industrial waste mixture, cement and activator to obtain mixture A; S2: mixing a phosphorus-containing polycarboxylate water reducer, composite coconut shell fiber, an accelerating setting agent, and water to obtain a mixture B; S3: Mixing the mixture A and the mixture B to obtain a coal mine filling paste material based on an anti-sulfur curing agent.

2. The method for preparing a coal mine filling paste material based on an anti-sulfur curing agent according to claim 1, characterized in that: The industrial waste residue mixture is obtained by compounding steel slag, red mud, mineral powder, carbide slag and desulfurization gypsum in a mass ratio of 3:3:2:1:

1. The particle size of steel slag and red mud is 2-4 μm, and the particle size of mineral powder, carbide slag and desulfurization gypsum is 1-2 μm.

3. The method for preparing a coal mine filling paste material based on an anti-sulfur curing agent according to claim 1, characterized in that: The quick-setting agent is prepared by mixing aluminum sulfate 18hydrate, diethanolamine, 4-methylphenol, water and lysine in a mass ratio of 58:6:0.1:35:0.

1.

4. The method for preparing a coal mine filling paste material based on an anti-sulfur curing agent according to claim 1, characterized in that: The activator is one or more of sodium silicate, sodium carbonate and sodium hydroxide.

5. The method for preparing a coal mine filling paste material based on a sulfur-resistant curing agent according to claim 1, wherein the raw materials of the filling paste material are composed of: 53-73 parts of coal gangue, 24-32 parts of industrial waste slag mixture, 5-10 parts of cement, 1-3 parts of an activator, 1-2 parts of a phosphorus-containing polycarboxylate water-reducing agent, 3-6 parts of composite coconut shell fiber, 0.5-1 part of an accelerating setting agent, and 58-68 parts of water.

6. The method for preparing a coal mine filling paste material based on an anti-sulfur curing agent according to claim 1, characterized in that: The preparation of the composite coconut shell fiber comprises the following steps: 1) coconut fiber and sodium hydroxide solution are mixed, stirred for 1-2h, washed, and dried to obtain pre-treated coconut fiber; 2) Under a nitrogen atmosphere, anhydrous ethanol, deionized water, 3-mercaptopropyltrimethoxysilane, and aqueous ammonia were mixed, heated to 60-70° C. in a water bath for 2-3 hours, stirred for 20-30 minutes, and pretreated coconut shell fiber was added. The mixture was stirred at 18-25° C. for 5-6 hours, washed with ethanol and deionized water for 3-5 times, and dried to obtain thiol-modified coconut shell fiber; 3) The thiolated coconut shell fiber, N, N-dimethylformamide and a photoinitiator are mixed, and double-bond branched phosphoramide and N, N-dimethylformamide are added and mixed, the mixture is heated to 50-60° C., treated with ultraviolet light, washed and dried to obtain composite coconut shell fiber.

7. The method for preparing a coal mine filling paste material based on an anti-sulfur curing agent according to claim 1, characterized in that: The preparation of the phosphorus-containing polycarboxylate water-reducing agent comprises the following steps: Under a nitrogen atmosphere, methyl allyl polyoxyethylene ether and deionized water are mixed, the temperature is raised to 58-62°C, ammonium persulfate is added, a mixture of acrylic acid, double-bond branched phosphoramide, and deionized water is added, and the mixture is stirred for 2-3 hours. A mixture of ascorbic acid, 3-mercaptopropionic acid, and deionized water is added, and the mixture is stirred for 3-4 hours. The mixture is cooled and the pH is adjusted to neutral to obtain a phosphorus-containing polycarboxylate water reducer.

8. The method for preparing a coal mine filling paste material based on an anti-sulfur curing agent according to claim 7, characterized in that: The mass ratio of methyl allyl polyoxyethylene ether, acrylic acid, and double-bond branched phosphoramide is 24:2.9:3.

2.

9. The method for preparing a coal mine filling paste material based on a sulfur-resistant curing agent according to claim 6 or 7, characterized in that: The preparation of the double-bond branched phosphoramide comprises the following steps: (1) Under a nitrogen atmosphere, diethanolamine and dioxane are mixed, a mixture of phosphorus oxychloride and dioxane is added at 0-5°C, the temperature is raised to 38-42°C and the temperature is kept warm for 22-24 hours, a mixture of triethylamine and dioxane is added, the temperature is raised to 78-82°C and the temperature is kept warm for 22-24 hours, vacuum distillation is performed, deionized water is added, sodium hydroxide is added, stirring, suction filtration, vacuum distillation is performed, methanol is added, suction filtration, vacuum distillation is performed, and drying is performed to obtain a polyhydroxy branched phosphoramide; (2) Under a nitrogen atmosphere, polyhydroxy branched phosphoramide and N,N-dimethylformamide are mixed, anhydrous potassium carbonate is added, and a mixture of acryloyl chloride and N,N-dimethylformamide is added in an ice bath. The mixture is stirred in an ice bath for 1-2 hours, kept warm in the dark for 22-23 hours, filtered, and rotary evaporated to obtain a branched phosphoramide containing a double bond.

10. A coal mine filling paste material based on an anti-sulfur curing agent, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 8.

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