Preparation method of mine tailing filling cementing material

Abstract

The invention relates to the technical field of building materials, and particularly discloses a preparation method of a mine tailing filling cementing material, which comprises the following steps: S1, adding tailing sand, fly ash, modified biomass fiber and an acid-base buffer agent into a stirrer, carrying out dry stirring for 10-15 minutes, adding a novel toughening agent, and continuously stirring for 10-15 minutes to obtain a premix; and S2, adding a composite water reducing agent and water into the premix, carrying out wet mixing for 15-20 min, carrying out pouring, carrying out vibration molding, and carrying out normal temperature maintenance to a specified age so as to obtain the mine tailing filling cementing material. According to the method, effective utilization of mine waste is achieved, environmental pollution is reduced, the strength, crack resistance and saline-alkaline resistance of the cementing material are enhanced by adding the additive, and the method is suitable for mine engineering scenes and has wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and more particularly to a method for preparing a mine tailings filling gelling material. Background Art

[0002] my country's mine tailings discharge is as high as hundreds of millions of tons every year, which produces a large amount of tailings and causes a large amount of tailings accumulation. It not only causes serious pollution to the environment and destroys the ecological balance, but also causes waste of land resources, huge safety hazards, and poses a serious threat to the safety of life and property of residents near the tailings pond. my country's mines produce hundreds of millions of tons of tailings solid waste every year. Most of these tailings are piled up to form tailings ponds, occupying a large amount of agricultural and forestry land resources. Therefore, the rational use and treatment of solid waste discharged by mines is of great significance to the green development of mines. At the same time, a large number of goafs formed by mining bring great hidden dangers to mine safety production. Traditional goaf filling methods, such as filling with waste rock, are not satisfactory and it is difficult to effectively ensure the stability of goafs. The use of tailings directly as filling materials, but due to the characteristics of the tailings themselves, the materials made are rigid, low in toughness, and easy to crack, which has many limitations in practical applications. In addition, the mine environment is complex, and the filling materials are often eroded by chemical substances such as acids and alkalis. Ordinary materials are not resistant to salt and alkali, which greatly shortens the service life of the filling body. With the continuous improvement of environmental awareness and the in-depth implementation of the concept of sustainable development, the development of a filling cementitious material that can not only efficiently utilize mine waste but also meet the material performance requirements of mining engineering has become an urgent need in the industry. Therefore, the present invention provides a method for preparing a mine tailings filling cementitious material to solve the above-mentioned technical problems! Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention not only realizes the effective utilization of mining waste and reduces environmental pollution, but also the addition of additives enhances the strength, crack resistance and salt-alkali resistance of the cementitious material. It is suitable for mining engineering scenarios and has broad application prospects.

[0004] A method for preparing a mine tailings filling cementitious material, adopting the following technical scheme:

[0005] S1. Add tailings sand, fly ash, modified biomass fiber and acid-base buffer into a mixer, dry mix for 10-15 minutes, then add the new toughening agent, and continue stirring for 10-15 minutes to obtain a premix;

[0006] S2. Add composite water reducing agent and water to the premix, wet mix for 15-20 minutes, pour and vibrate to form, and cure at room temperature to a specified age to obtain a mine tailings filling cementitious material.

[0007] Preferably, the preparation method of the mine tailing filling cementitious material comprises the following raw materials in parts by weight: 40-45 parts of tailing sand, 20-25 parts of fly ash, 5-8 parts of modified biomass fiber, 1-3 parts of acid-base buffer, 3-5 parts of novel toughening agent, 1-3 parts of compound water reducer and 20-25 parts of water.

[0008] Preferably, the preparation method of the modified biomass fiber is as follows: the mixture of biomass fiber and nano calcium carbonate is uniformly dispersed in a sodium hydroxide solution with a mass fraction of 3-5% according to a dosage ratio of 10-15 g / L, soaked at normal temperature for 20-24 h under stirring, filtered and washed to obtain a mixture, added with a stearic acid ethanol solution 5-8 times the mass of the mixture, ultrasonically treated at 35-40 °C for 50-60 min, filtered and dried, and the obtained product is the modified biomass fiber.

[0009] Preferably, the biomass fiber is at least one of wheat straw, rice straw and flax.

[0010] Preferably, the preparation method of the novel toughening agent is as follows:

[0011] Step 1: Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:5-8, add pyromellitic dianhydride 1-2 times the molar ratio of 4,4'-diaminodiphenyl ether, stir at normal temperature for 2-3 h, then raise the temperature to 150-160 °C, and continuously stir for 4-6 h to obtain a polyimide prepolymer solution;

[0012] Step 2: Carry out vacuum dehydration treatment on hydrogenated nitrile rubber at 100-110 °C for 1-2 h to remove the moisture in the rubber. After the reaction system cools to 50-60 °C, add hexamethylene diisocyanate 1.4-1.5 times the mass of hydrogenated nitrile rubber and 0.1-0.3% of dibutyltin dilaurate, and continuously stir at 70-80 °C for 3-4 h to obtain terminal isocyanate group hydrogenated nitrile rubber;

[0013] Step 3: Add the polyimide prepolymer solution to the terminal isocyanate group hydrogenated nitrile rubber according to a mass ratio of 1.4-1.6:1, stir at normal temperature for 40-50 min, then add 4,4'-dithiodimorpholine accounting for 4-6% of the mass of the terminal isocyanate group hydrogenated nitrile rubber, and continuously stir at 80-90 °C for 6-8 h, then filter, wash and dry to obtain the novel plasticizer.

[0014] Preferably, the tailing sand and fly ash are 150-200 mesh and 200-250 mesh respectively.

[0015] Preferably, the acid-base buffer is composed of potassium dihydrogen phosphate, borax and boric acid in a mass ratio of 2:1:1-3.

[0016] Preferably, the composite water reducing agent is composed of a lignosulfonate water reducing agent and sodium dodecylbenzenesulfonate with a mass ratio of 2-4:1.

[0017] In summary, the present invention has the following beneficial effects:

[0018] 1. The mine tailings filling cementitious material of the present invention is prepared from tailings sand, fly ash, modified biomass fiber, acid-base buffer, composite water reducing agent and water. Each component complements each other, realizing the effective utilization of mine waste and reducing environmental pollution; the modified biomass fiber can enhance the toughness and structural stability of the material, improve the internal stress distribution of the material, and effectively improve the crack resistance; the new toughening agent can significantly improve the toughness and ductility of the material, enabling the material to deform better under stress without cracking, and enhancing the comprehensive mechanical properties; the acid-base buffer is composed of potassium dihydrogen phosphate, borax and boric acid, which can adjust the internal acid-base environment of the material, maintain the stability of the reaction system, and facilitate the stable performance of the material; the composite water reducing agent is composed of a lignosulfonate water reducing agent and sodium dodecylbenzenesulfonate, which can reduce the water consumption for preparation, improve the fluidity and construction performance of the material, and at the same time enhance the density and strength of the material.

[0019] 2. The modified biomass fiber of the present invention is obtained by soaking biomass fiber and nano calcium carbonate in sodium hydroxide solution and then treating with stearic acid ethanol solution. The sodium hydroxide solution generates more active groups on the fiber surface, enhancing the binding force with other components. After treatment with stearic acid ethanol solution, an organic film is formed on the fiber surface, improving the flexibility and dispersibility. In the cementitious material, the modified biomass fiber can be evenly dispersed, forming a tight network structure with tailings sand, fly ash, etc., effectively transmitting and dispersing stress, and significantly improving the toughness and crack resistance of the material. At the same time, nano calcium carbonate can fill the tiny pores inside the material, further improving the density and strength of the material.

[0020] 3. The new toughening agent of the present invention is obtained by mixing a polyimide prepolymer and a terminal isocyanate group hydrogenated nitrile rubber and then reacting with 4,4'-dithiobis(morpholine). The new toughening agent prepared through multiple-step reactions forms an interpenetrating network structure between the polyimide prepolymer and the terminal isocyanate group hydrogenated nitrile rubber. The addition of 4,4'-dithiobis(morpholine) further crosslinks and cures, enhancing the intermolecular force. In the cementitious material, the new toughening agent is evenly dispersed and interacts with other components, improving the toughness and ductility of the material, enabling the material to withstand greater external forces without damage, and greatly enhancing the comprehensive mechanical properties of the material. Detailed implementation mode

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] The materials, reagents, etc. used in the embodiments and comparative examples of the present invention can be obtained from commercial channels without special instructions.

[0023] Example 1

[0024] This example provides a preparation method for a gelling material for filling mine tailings. By weight, it includes the following steps: S1. Add 40 parts of 150-mesh tailings sand, 20 parts of 200-mesh fly ash, 5 parts of modified biomass fiber, and 1 part of acid-base buffer to a mixer, control the stirring rate at 200 rpm, dry mix for 15 min, then add 3 parts of a new toughening agent and continue stirring for 15 min to obtain a premix; S2. Add 1 part of a composite water reducer and 20 parts of water to the premix, control the stirring rate at 250 rpm, wet mix for 20 min, pour and vibrate to form, and cure at room temperature until the specified age to obtain a gelling material for filling mine tailings. The acid-base buffer is composed of potassium dihydrogen phosphate, borax, and boric acid with a mass ratio of 2:1:1, and the composite water reducer is composed of a lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 2:1.

[0025] The preparation method of the modified biomass fiber is as follows: A mixture of wheat straw and nano-calcium carbonate with a mass ratio of 1:1 is uniformly dispersed in a 3% sodium hydroxide solution at a dosage ratio of 10 g / L, soaked at room temperature for 24 h under stirring, then filtered and washed to obtain a mixture. Add a stearic acid ethanol solution with a mass 5 times that of the mixture and a concentration of 8%, and perform ultrasonic treatment at 35°C and 40 KHz for 60 min, then filter and dry to obtain the modified biomass fiber.

[0026] The preparation method of the new toughening agent is as follows:

[0027] Step 1. Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:5, add pyromellitic dianhydride with a molar ratio 1 time that of 4,4'-diaminodiphenyl ether, control the stirring rate at 300 rpm, stir at room temperature for 3 h, then raise the temperature to 150°C and continue stirring for 6 h to obtain a polyimide prepolymer solution;

[0028] Step 2: Vacuum dehydrate hydrogenated nitrile rubber at 100 °C for 2 h to remove the moisture in the rubber. After the reaction system cools to 50 °C, add hexamethylene diisocyanate with a mass 1.4 times that of the hydrogenated nitrile rubber and 0.1% dibutyltin dilaurate, control the stirring rate at 200 rpm, and continuously stir at 70 °C for 4 h to obtain terminal isocyanate group hydrogenated nitrile rubber;

[0029] Step 3: Add the polyimide prepolymer solution to the terminal isocyanate group hydrogenated nitrile rubber according to a mass ratio of 1.4:1, stir at room temperature for 50 min, then add 4,4'-dithiodimorpholine accounting for 4% of the mass of the terminal isocyanate group hydrogenated nitrile rubber, and continuously stir at 80 °C for 8 h, then filter, wash and dry to obtain the novel plasticizer.

[0030] Example 2

[0031] This example provides a preparation method of a mine tailings filling cementitious material. By weight, it includes the following steps: S1. Add 42 parts of 160-mesh tailings sand, 22 parts of 220-mesh fly ash, 6 parts of modified biomass fiber and 2 parts of acid-base buffer agent to a mixer, control the stirring rate at 220 rpm, dry mix for 14 min, then add 4 parts of novel toughening agent, and continue to stir for 14 min to obtain a premix; S2. Add 2 parts of compound water reducer and 22 parts of water to the premix, control the stirring rate at 270 pm, wet mix for 19 min, pour and vibrate to form, and cure at room temperature to the specified age to obtain a mine tailings filling cementitious material. The acid-base buffer agent is composed of potassium dihydrogen phosphate, borax and boric acid with a mass ratio of 2:1:2, and the compound water reducer is composed of lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1. The preparation method of the modified biomass fiber is as follows: Uniformly disperse the mixture of straw and nano calcium carbonate with a mass ratio of 2:1 in a sodium hydroxide solution with a mass fraction of 4% according to a dosage ratio of 12 g / L, soak at room temperature for 23 h under stirring, then filter and wash to obtain a mixture, add a stearic acid ethanol solution with a mass 6 times that of the mixture and a concentration of 9%, carry out ultrasonic treatment at 36 °C and 42 KHz for 58 min, then filter and dry, and the obtained is the modified biomass fiber.

[0032] The preparation method of the novel toughening agent is as follows:

[0033] Step 1: Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:6, add pyromellitic dianhydride with a molar ratio 2 times that of 4,4'-diaminodiphenyl ether, control the stirring rate at 320 rpm, stir at room temperature for 2.8 h, then heat up to 152 °C, and continuously stir for 5.8 h to obtain a polyimide prepolymer solution;

[0034] Step 2: Subject the hydrogenated nitrile rubber to vacuum dehydration treatment at 102 °C for 1.5 h to remove the moisture in the rubber. After the reaction system is cooled to 52 °C, add hexamethylene diisocyanate with a mass 1.45 times that of the hydrogenated nitrile rubber and 0.2% dibutyltin dilaurate, control the stirring rate at 220 rpm, and continuously stir at 72 °C for 3.8 h to obtain terminal isocyanate group hydrogenated nitrile rubber;

[0035] Step 3: Add the polyimide prepolymer solution to the terminal isocyanate group hydrogenated nitrile rubber according to a mass ratio of 1.5:1, stir at room temperature for 42 min, then add 4,4'-dithiodimorpholine accounting for 4.5% of the mass of the terminal isocyanate group hydrogenated nitrile rubber, and continuously stir at 82 °C for 7.5 h, then filter, wash and dry to obtain the novel plasticizer.

[0036] Example 3

[0037] This example provides a preparation method of a mine tailings filling cementitious material. By weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, 8 parts of modified biomass fiber and 3 parts of acid-base buffer agent to a mixer, control the stirring rate at 300 rpm, dry mix for 10 min, then add 5 parts of novel toughening agent, and continue to stir for 10 min to obtain a premix; S2. Add 3 parts of compound water reducer and 25 parts of water to the premix, control the stirring rate at 350 rpm, wet mix for 15 min, pour and vibrate to form, and cure at room temperature to the specified age to obtain a mine tailings filling cementitious material, wherein the acid-base buffer agent is composed of potassium dihydrogen phosphate, borax and boric acid with a mass ratio of 2:1:3, and the compound water reducer is composed of lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 4:1.

[0038] The preparation method of the modified biomass fiber is as follows: Disperse the mixture of flax and nano calcium carbonate with a mass ratio of 3:1 evenly in a sodium hydroxide solution with a mass fraction of 5% according to a dosage ratio of 15 g / L, soak at room temperature for 20 h under stirring, then filter and wash to obtain a mixture, add a stearic acid ethanol solution with a mass 8 times that of the mixture and a concentration of 12%, perform ultrasonic treatment at 40 °C and 55 KHz for 50 min, then filter and dry, and the obtained product is the modified biomass fiber.

[0039] The preparation method of the novel toughening agent is as follows:

[0040] Step 1: Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:8, add pyromellitic dianhydride with a molar ratio 2 times that of 4,4'-diaminodiphenyl ether, control the stirring rate at 400 rpm, stir at room temperature for 2 h, then raise the temperature to 160 °C, and continuously stir for 4 h to obtain a polyimide prepolymer solution;

[0041] Step 2: vacuum dehydrating the hydrogenated nitrile rubber at 110° C. for 1 h to remove moisture from the rubber, and after the reaction system is cooled to 60° C., adding hexamethylene diisocyanate and 0.3% dibutyltin dilaurate in an amount 1.5 times the mass of the hydrogenated nitrile rubber, and controlling the stirring rate to 300 rpm, stirring at 80° C. for 3 h to obtain the isocyanate-terminated hydrogenated nitrile rubber;

[0042] Step 3: Add the polyimide prepolymer solution to the isocyanate-terminated hydrogenated nitrile rubber at a mass ratio of 1.6:1, stir at room temperature for 40 minutes, then add 6% of the mass of 4,4'-dithiodimorpholine of the isocyanate-terminated hydrogenated nitrile rubber, continue stirring at 90°C for 6 hours, filter, wash and dry to obtain a new plasticizer.

[0043] Example 4

[0044] The present embodiment provides a preparation method of a mine tailings filling cementitious material, which comprises the following steps by weight: S1, adding 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, 8 parts of modified biomass fiber and 3 parts of acid-base buffer into a mixer, controlling the stirring rate to 300 rpm, adding 4 parts of a new toughening agent after dry mixing for 12 minutes, and continuing to stir for 15 minutes to obtain a premix; S2, adding 2 parts of a composite water reducer and 25 parts of water to the premix, controlling the stirring rate to 350 rpm, wet mixing for 18 minutes, pouring and vibrating to form, and curing at room temperature to a specified age, so as to obtain a mine tailings filling cementitious material, wherein the acid-base buffer is composed of potassium dihydrogen phosphate, borax and boric acid in a mass ratio of 2:1:2, and the composite water reducer is composed of a lignin sulfonate water reducer and sodium dodecylbenzene sulfonate in a mass ratio of 3:1.

[0045] The preparation method of the modified biomass fiber is as follows: a mixture of flax and nano calcium carbonate in a mass ratio of 3:1 is uniformly dispersed in a sodium hydroxide solution with a mass fraction of 5% at a dosage ratio of 14 g / L, the mixture is filtered and washed after being soaked at room temperature for 24 hours under stirring, a stearic acid ethanol solution with a mass of 8 times that of the mixture and a concentration of 12% is added, and the mixture is ultrasonically treated at 40° C. and 50 kHz for 55 minutes, and then filtered and dried to obtain the modified biomass fiber.

[0046] The preparation method of the novel toughening agent is:

[0047] Step 1, dissolving 4,4'-diaminodiphenyl ether in N-methylpyrrolidone at a mass ratio of 1:8, adding pyromellitic anhydride at a molar ratio of 2 times that of 4,4'-diaminodiphenyl ether, controlling the stirring rate to 400 rpm, stirring at room temperature for 2.5 hours, then heating to 160°C, and continuing stirring for 5 hours to obtain a polyimide prepolymer solution;

[0048] Step 2: Vacuum dehydrate hydrogenated nitrile rubber at 110°C for 1.5 h to remove the moisture in the rubber. After the reaction system cools to 60°C, add hexamethylene diisocyanate with a mass 1.5 times that of hydrogenated nitrile rubber and 0.3% dibutyltin dilaurate, control the stirring rate at 300 rpm, and continuously stir at 80°C for 3 h to obtain terminal isocyanate group hydrogenated nitrile rubber;

[0049] Step 3: Add the polyimide prepolymer solution to the terminal isocyanate group hydrogenated nitrile rubber according to a mass ratio of 1.6:1, stir at room temperature for 50 min, then add 4,4'-dithiobis(morpholine) accounting for 5% of the mass of the terminal isocyanate group hydrogenated nitrile rubber, continuously stir at 85°C for 6 h, and then filter, wash, and dry to obtain the novel plasticizer.

[0050] Comparative Example 1

[0051] This example provides a preparation method of a mine tailings filling cementitious material. Calculated by weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, 8 parts of modified biomass fiber, and 3 parts of acid-base buffer agent to a mixer, control the stirring rate at 300 rpm, and dry mix for 12 min to obtain a premix; S2. Add 2 parts of a composite water reducer and 25 parts of water to the premix, control the stirring rate at 350 rpm, wet mix for 18 min, pour and vibrate to form, and cure at room temperature until the specified age to obtain a mine tailings filling cementitious material. The acid-base buffer agent is composed of potassium dihydrogen phosphate, borax, and boric acid with a mass ratio of 2:1:2, and the composite water reducer is composed of a lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1.

[0052] The preparation method of the modified biomass fiber is as follows: Uniformly disperse a mixture of flax and nano calcium carbonate with a mass ratio of 3:1 in a 5% sodium hydroxide solution according to a dosage ratio of 14 g / L, soak at room temperature for 24 h under stirring, then filter and wash to obtain a mixture, add a stearic acid ethanol solution with a mass 8 times that of the mixture and a concentration of 12%, perform ultrasonic treatment at 40°C and 50 KHz for 55 min, and then filter and dry. What is obtained is the modified biomass fiber.

[0053] Comparative Example 2

[0054] This embodiment provides a preparation method of a cementitious material for filling mine tailings. By weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, and 3 parts of an acid-base buffer to a mixer, control the stirring rate at 300 rpm, dry mix for 12 min, then add 4 parts of a novel toughening agent, and continue stirring for 15 min to obtain a premix; S2. Add 2 parts of a composite water reducer and 25 parts of water to the premix, control the stirring rate at 350 rpm, wet mix for 18 min, pour and vibrate to form, and cure at room temperature until the specified age, then a cementitious material for filling mine tailings is obtained. The acid-base buffer is composed of potassium dihydrogen phosphate, borax, and boric acid with a mass ratio of 2:1:2, and the composite water reducer is composed of a lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1.

[0055] The preparation method of the novel toughening agent is as follows:

[0056] Step 1. Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:8, add pyromellitic dianhydride with a molar ratio twice that of 4,4'-diaminodiphenyl ether, control the stirring rate at 400 rpm, stir at room temperature for 2.5 h, then heat up to 160 °C, and continue stirring for 5 h to obtain a polyimide prepolymer solution;

[0057] Step 2. Carry out vacuum dehydration treatment on hydrogenated nitrile rubber at 110 °C for 1.5 h to remove the moisture in the rubber. After the reaction system cools to 60 °C, add hexamethylene diisocyanate with a mass 1.5 times that of hydrogenated nitrile rubber and 0.3% of dibutyltin dilaurate, control the stirring rate at 300 rpm, and continue stirring at 80 °C for 3 h to obtain a hydrogenated nitrile rubber with terminal isocyanate groups;

[0058] Step 3. Add the polyimide prepolymer solution to the hydrogenated nitrile rubber with terminal isocyanate groups according to a mass ratio of 1.6:1, stir at room temperature for 50 min, then add 4,4'-dithiodimorpholine accounting for 5% of the mass of the hydrogenated nitrile rubber with terminal isocyanate groups, and continue stirring at 85 °C for 6 h, then filter, wash, and dry to obtain the novel plasticizer.

[0059] Comparative Example 3

[0060] This embodiment provides a preparation method of a gelling material for filling mine tailings. By weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, and 8 parts of modified biomass fiber into a blender. Control the stirring rate at 300 rpm. After dry mixing for 12 minutes, add 4 parts of a new toughening agent and continue stirring for 15 minutes to obtain a premix; S2. Add 2 parts of a composite water reducer and 25 parts of water to the premix. Control the stirring rate at 350 rpm. Wet mix for 18 minutes, pour and vibrate to form. Cure at normal temperature until the specified age, and then a gelling material for filling mine tailings is obtained. The composite water reducer is composed of a lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1.

[0061] The preparation method of the modified biomass fiber is as follows: Uniformly disperse a mixture of flax and nano-calcium carbonate with a mass ratio of 3:1 in a sodium hydroxide solution with a mass fraction of 5% according to a dosage ratio of 14 g / L. After soaking at normal temperature for 24 hours under stirring, filter and wash to obtain a mixture. Add a stearic acid ethanol solution with a mass 8 times that of the mixture and a concentration of 12%. After ultrasonic treatment at 40 °C and 50 KHz for 55 minutes, filter and dry. What is obtained is the modified biomass fiber.

[0062] The preparation method of the new toughening agent is as follows:

[0063] Step 1. Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:8. Add pyromellitic dianhydride with a molar ratio 2 times that of 4,4'-diaminodiphenyl ether. Control the stirring rate at 400 rpm. After stirring at normal temperature for 2.5 hours, raise the temperature to 160 °C and continue stirring for 5 hours to obtain a polyimide prepolymer solution;

[0064] Step 2. Conduct vacuum dehydration treatment on hydrogenated nitrile rubber at 110 °C for 1.5 hours to remove the moisture in the rubber. After the reaction system cools to 60 °C, add hexamethylene diisocyanate with a mass 1.5 times that of the hydrogenated nitrile rubber and 0.3% of dibutyltin dilaurate. Control the stirring rate at 300 rpm. After continuously stirring at 80 °C for 3 hours, obtain a hydrogenated nitrile rubber with an isocyanate group at the end;

[0065] Step 3. Add the polyimide prepolymer solution to the hydrogenated nitrile rubber with an isocyanate group at the end according to a mass ratio of 1.6:1. After stirring at normal temperature for 50 minutes, add 4,4'-dithiodimorpholine accounting for 5% of the mass of the hydrogenated nitrile rubber with an isocyanate group at the end. After continuously stirring at 85 °C for 6 hours, filter, wash, and dry to obtain the new plasticizer.

[0066] Comparative Example 4

[0067] This embodiment provides a preparation method of a cementitious material for filling mine tailings. By weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, 8 parts of modified biomass fiber, and 3 parts of acid-base buffer to a blender. Control the stirring rate at 300 rpm. After dry mixing for 12 min, add 4 parts of a new toughening agent and continue stirring for 15 min to obtain a premix; S2. Add 2 parts of a composite water reducer and 25 parts of water to the premix. Control the stirring rate at 350 rpm. Wet mix for 18 min, pour and vibrate to form. Cure at room temperature until the specified age, and then a cementitious material for filling mine tailings is obtained. The acid-base buffer is composed of potassium dihydrogen phosphate, borax, and boric acid with a mass ratio of 2:1:2, and the composite water reducer is composed of lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1.

[0068] The preparation method of the modified biomass fiber is as follows: Disperse flax evenly in a 5% sodium hydroxide solution according to a dosage ratio of 14 g / L. After soaking at room temperature for 24 h under stirring, filter and wash. What is obtained is the modified biomass fiber.

[0069] The preparation method of the new toughening agent is as follows:

[0070] Step 1. Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:8. Add pyromellitic dianhydride with a molar ratio twice that of 4,4'-diaminodiphenyl ether. Control the stirring rate at 400 rpm. Stir at room temperature for 2.5 h and then heat up to 160 °C. Continue stirring for 5 h to obtain a polyimide prepolymer solution;

[0071] Step 2. Perform vacuum dehydration treatment on hydrogenated nitrile rubber at 110 °C for 1.5 h to remove the moisture in the rubber. After the reaction system cools to 60 °C, add hexamethylene diisocyanate with a mass 1.5 times that of hydrogenated nitrile rubber and 0.3% of dibutyltin dilaurate. Control the stirring rate at 300 rpm. Stir continuously at 80 °C for 3 h to obtain a terminal isocyanate group hydrogenated nitrile rubber;

[0072] Step 3. Add the polyimide prepolymer solution to the terminal isocyanate group hydrogenated nitrile rubber according to a mass ratio of 1.6:1. Stir at room temperature for 50 min and then add 4,4'-dithiodimorpholine accounting for 5% of the mass of the terminal isocyanate group hydrogenated nitrile rubber. Stir continuously at 85 °C for 6 h and then filter, wash, and dry to obtain the new plasticizer.

[0073] Comparative Example 5

[0074] This embodiment provides a preparation method of a cementitious material for filling mine tailings. By weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, 8 parts of modified biomass fiber, and 3 parts of acid-base buffer agent into a mixer. Control the stirring rate at 300 rpm. After dry mixing for 12 minutes, add 4 parts of a new toughening agent and continue stirring for 15 minutes to obtain a premix; S2. Add 2 parts of a composite water reducer and 25 parts of water to the premix. Control the stirring rate at 350 rpm. Wet mix for 18 minutes, then pour and vibrate to form. Cure at room temperature until the specified age, and then a cementitious material for filling mine tailings is obtained. The acid-base buffer agent is composed of potassium dihydrogen phosphate, borax, and boric acid with a mass ratio of 2:1:2, and the composite water reducer is composed of lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1.

[0075] The preparation method of the modified biomass fiber is as follows: Uniformly disperse a mixture of flax and nano-calcium carbonate with a mass ratio of 3:1 in a 5% sodium hydroxide solution according to a dosage ratio of 14 g / L. After soaking at room temperature for 24 hours under stirring, filter and wash to obtain a mixture. Add a stearic acid ethanol solution with a mass 8 times that of the mixture and a concentration of 12%. After ultrasonic treatment at 40 °C and 50 KHz for 55 minutes, filter and dry. What is obtained is the modified biomass fiber.

[0076] The preparation method of the new toughening agent is as follows:

[0077] Step 1. Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone according to a mass ratio of 1:8. Add pyromellitic dianhydride with a molar ratio 2 times that of 4,4'-diaminodiphenyl ether. Control the stirring rate at 400 rpm. Stir at room temperature for 2.5 hours and then heat up to 160 °C. Continue stirring for 5 hours to obtain a polyimide prepolymer solution;

[0078] Step 2. Conduct vacuum dehydration treatment on hydrogenated nitrile rubber at 110 °C for 1.5 hours to remove the moisture in the rubber. Wait for the reaction system to cool to 60 °C, add hexamethylene diisocyanate with a mass 1.5 times that of hydrogenated nitrile rubber and 0.3% dibutyltin dilaurate. Control the stirring rate at 300 rpm. Stir continuously at 80 °C for 3 hours to obtain a terminal isocyanate group hydrogenated nitrile rubber;

[0079] Step 3. Add the polyimide prepolymer solution to the terminal isocyanate group hydrogenated nitrile rubber according to a mass ratio of 1.6:1. Stir at room temperature for 50 minutes to obtain a new plasticizer.

[0080] Comparative Example 6

[0081] This embodiment provides a preparation method of a cementitious material for filling mine tailings. By weight, it includes the following steps: S1. Add 45 parts of 200-mesh tailings sand, 25 parts of 250-mesh fly ash, 8 parts of modified biomass fiber, and 3 parts of acid-base buffer agent into a blender. Control the stirring rate at 300 rpm. After dry mixing for 12 minutes, add 4 parts of a new toughening agent and continue stirring for 15 minutes to obtain a premix; S2. Add 2 parts of a composite water reducer and 25 parts of water to the premix. Control the stirring rate at 350 rpm. Wet mix for 18 minutes, pour and vibrate to form. Cure at room temperature until the specified age, and then a cementitious material for filling mine tailings is obtained. The acid-base buffer agent is composed of potassium dihydrogen phosphate, borax, and boric acid with a mass ratio of 2:1:2, and the composite water reducer is composed of a lignosulfonate water reducer and sodium dodecylbenzenesulfonate with a mass ratio of 3:1.

[0082] The preparation method of the modified biomass fiber is as follows: Disperse a mixture of flax and nano-calcium carbonate with a mass ratio of 3:1 evenly in a sodium hydroxide solution with a mass fraction of 5% according to a dosage ratio of 14 g / L. After soaking at room temperature for 24 hours under stirring, filter and wash to obtain a mixture. Add a stearic acid ethanol solution with a mass 8 times that of the mixture and a concentration of 12%. After ultrasonic treatment at 40 °C and 50 KHz for 55 minutes, filter and dry. What is obtained is the modified biomass fiber.

[0083] The preparation method of the new toughening agent is as follows:

[0084] Step 1: Perform vacuum dehydration treatment on hydrogenated nitrile rubber at 110 °C for 1.5 hours to remove the moisture in the rubber. After the reaction system cools to 60 °C, add hexamethylene diisocyanate with a mass 1.5 times that of the hydrogenated nitrile rubber and 0.3% of dibutyltin dilaurate. Control the stirring rate at 300 rpm. Continuously stir at 80 °C for 3 hours to obtain a new plasticizer;

[0085] Performance test

[0086] Perform the following performance tests on the cementitious materials for filling mine tailings obtained in Examples 1-4 and Comparative Examples 1-6 respectively:

[0087] 1. Compressive strength test: Refer to the standard of GB / T 17671-1999 "Test Method for Strength of Cement Mortar (ISO Method)" to conduct a compressive strength test on the prepared cementitious material for filling mine tailings. The test results are shown in Table 1.

[0088] 2. Fluidity test: Refer to the standard of GB / T 50080-2016 "Standard Test Method for Properties of Ordinary Concrete Mixtures" to conduct a fluidity test on the prepared cementitious material for filling mine tailings. The test results are shown in Table 1.

[0089] 3. Salt and alkali resistance test: Refer to GB / T 50082-2009 "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" to conduct salt and alkali resistance tests on the prepared mine tailings filling cementitious materials. The test results are shown in Table 1.

[0090] Test items Compressive strength / MPa Flowability / mm Mass loss rate / % Example 1 113.87 327 3.10 Example 2 114.29 330 3.09 Example 3 115.01 342 3.07 Example 4 115.72 350 3.03 Comparative example 1 75.43 229 3.49 Comparative example 2 89.78 335 3.27 Comparative example 3 60.77 183 4.02 Comparative example 4 105.29 367 3.16 Comparative example 5 110.37 294 3.13 Comparative example 6 96.55 281 3.20

[0091] It can be seen from the results shown in Table 1 above that the compressive strength, fluidity and salt and alkali resistance of the mine tailings filling cementitious materials prepared in Examples 1-4 of the present invention are far superior to those of Comparative Examples 1-6 because they completely retain the reinforcing fibers, plasticizer cross-linking network and acid-base buffer system.

[0092] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A method for preparing a mine tailings filling gelling material, characterized in that: The steps include: S1. Add tailings sand, fly ash, modified biomass fiber and acid-base buffer into a mixer, dry mix for 10-15 minutes, then add the new toughening agent, and continue to stir for 10-15 minutes to obtain a premix; S2. Add composite water reducing agent and water to the premix, wet mix for 15-20 minutes, pour and vibrate to form, and cure at room temperature to a specified age to obtain a mine tailings filling cementitious material.

2. The method for preparing the mine tailings filling gelling material according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 40-45 parts of tailings sand, 20-25 parts of fly ash, 5-8 parts of modified biomass fiber, 1-3 parts of acid-base buffer, 3-5 parts of new toughening agent, 1-3 parts of composite water reducing agent and 20-25 parts of water.

3. The method for preparing the mine tailings filling gelling material according to claim 1, characterized in that: The preparation method of the modified biomass fiber is as follows: a mixture of biomass fiber and nano calcium carbonate is uniformly dispersed in a sodium hydroxide solution with a mass fraction of 3-5% at a dosage ratio of 10-15 g / L, the mixture is filtered and washed after being soaked at room temperature for 20-24 hours under stirring, a stearic acid ethanol solution with a mass 5-8 times that of the mixture is added, and the mixture is ultrasonically treated at 35-40° C. for 50-60 minutes and then filtered and dried to obtain the modified biomass fiber.

4. The method for preparing the mine tailings filling gelling material according to claim 1, characterized in that: The preparation method of the novel toughening agent is: Step 1, dissolving 4,4'-diaminodiphenyl ether in N-methylpyrrolidone at a mass ratio of 1:5-8, adding pyromellitic dianhydride at a molar ratio of 1-2 times that of 4,4'-diaminodiphenyl ether, stirring at room temperature for 2-3 hours, then heating to 150-160° C., and continuously stirring for 4-6 hours to obtain a polyimide prepolymer solution; Step 2: vacuum dehydrating the hydrogenated nitrile rubber at 100-110° C. for 1-2 hours to remove moisture from the rubber, and after the reaction system is cooled to 50-60° C., adding hexamethylene diisocyanate in an amount of 1.4-1.5 times the mass of the hydrogenated nitrile rubber and 0.1-0.3% of dibutyltin dilaurate, and continuously stirring at 70-80° C. for 3-4 hours to obtain isocyanate-terminated hydrogenated nitrile rubber; Step 3: Add the polyimide prepolymer solution to the isocyanate-terminated hydrogenated nitrile rubber in a mass ratio of 1.4-1.6:1, stir at room temperature for 40-50 minutes, then add 4,4'-dithiodimorpholine accounting for 4-6% of the mass of the isocyanate-terminated hydrogenated nitrile rubber, continue stirring at 80-90°C for 6-8 hours, filter, wash and dry to obtain a new plasticizer.

5. The method for preparing the mine tailings filling gelling material according to claim 1, characterized in that: The tailings sand and fly ash are 150-200 mesh and 200-250 mesh respectively.

6. The method for preparing the mine tailings filling gelling material according to claim 1, characterized in that: The acid-base buffer consists of potassium dihydrogen phosphate, borax and boric acid in a mass ratio of 2:1:1-3.

7. The method for preparing the mine tailings filling gelling material according to claim 1, characterized in that: The composite water reducer consists of a lignin sulfonate water reducer and sodium dodecylbenzene sulfonate in a mass ratio of 2-4:1.