Method for preparing lithium feldspar tailings cemented filling body doped with basalt fiber and carbon nanotubes

Abstract

The present invention provides a method for preparing a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body, comprising: step S1, taking carboxylated carbon nanotubes and PVP, adding a first portion of water, stirring to obtain a preliminary carbon nanotube suspension, then adding a silane coupling agent, and ultrasonically obtaining a carbon nanotube suspension; step S2, taking lithium feldspar tailings and basalt fibers as aggregates and cement as a cementing material, stirring uniformly to obtain a first mixture; step S3, adding the carbon nanotube suspension to the first mixture and stirring again to obtain a second mixture; step S4, adding a second portion of water to the second mixture and stirring again to obtain a slurry with a certain solid content; step S5, pouring the slurry into a mold and curing, thereby obtaining a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body. The method of the present invention can significantly improve the flexural strength of the filling body, increase the compressive strength, and reduce the amount of fiber used.

Description

Technical Field

[0001] The present invention relates to the technical field of mine filling material preparation, in particular to a method for preparing a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Background Art

[0002] With economic development, the demand for mineral products has increased significantly, and the scale of mining development has expanded accordingly. Metal mines generate large amounts of solid waste, such as tailings and slag, during their operations. Furthermore, the grade of many usable metal ores is decreasing. To meet the growing demand for mineral products, the scale of mineral processing is increasing, and the amount of tailings generated will also increase. The large amount of stockpiled tailings poses a number of environmental challenges to the mining industry, the environment, and the economy. Tailings cementation filling technology is a solution that makes mining operations more stable and efficient while reducing solid waste. Tailings cementation filling materials are typically made primarily of tailings, a binder, and water. Sometimes, to meet the design strength requirements of the backfill structure, the mechanical properties of the fill can be enhanced by adding chemicals, cementitious materials, and fiber materials.

[0003] To ensure the compressive strength of the cementitious structure and reduce cracking caused by drying shrinkage and deformation, the expansion of small cracks, and block detachment, the method of incorporating fibers is used to improve the load-bearing capacity of the components and slow down the rapid destruction after the peak. The tensile strength of the fibers acts as a bridge within the cementitious structure, thereby reducing the early cracking of the components. To reduce the cost of cement and other related materials, researchers have enhanced the durability and strength of the cemented backfill by incorporating mixed fibers, thereby obtaining physical properties such as compressive resistance, tensile strength, and toughness. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes, wherein the flexural strength and compressive strength of the filling body are improved by using green and environmentally friendly basalt fibers, the compressive strength of the filling body is improved by adding carbon nanotubes, and the segregation and water bleeding of the filling body are improved by adding a silane coupling agent to modify the carbon nanotubes. A lithium feldspar tailings cemented filling body sample is prepared by doping a basalt fiber and carbon nanotube suspension, and a three-point bending test and a uniaxial compression test are performed on the sample to obtain the flexural strength and compressive strength values ​​of the lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. The flexural strength and compressive strength values ​​of the lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes are compared, and the optimal silane coupling agent, solid content, carbon nanotube content, fiber content and cement to tailings ratio are obtained to obtain the optimal ratio of the lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] A method for preparing a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes, comprising:

[0007] Step S1: Take carboxylated carbon nanotubes, polyvinyl pyrrolidone (PVP), and add the first portion of water, stir to obtain a preliminary carbon nanotube suspension, then add a silane coupling agent, and ultrasonicate to obtain a carbon nanotube suspension; the silane coupling agent has three functions: one is to act as a thickener for cement, the second is to act as a modifier for carbon nanotubes, and the third is to act as a finishing agent for basalt fibers to improve surface adhesion.

[0008] Step S2: lithium feldspar tailings and basalt fiber are taken as aggregates and cement is used as a cementitious material, and the mixture is stirred evenly to obtain a first mixture. Basalt fiber is a new green material. Compared with traditional composite materials such as polyethylene fiber, its production is more environmentally friendly and does not require non-renewable energy such as petroleum. At the same time, the composition of basalt fiber is similar to that of glass fiber. Silane coupling agent is used as a glass fiber finishing agent in industry and can effectively improve the adhesion and strength of glass fiber. Therefore, silane coupling agent can also be used to modify basalt fiber and carbon nanotubes.

[0009] Step S3: Add the carbon nanotube suspension to the first mixture and stir again to obtain a second mixture. Basalt fibers can increase strength, ductility, and strength at a macroscopic level, while carbon nanotubes, as nanomaterials, can reduce porosity, bridge cracks, and promote the formation of hydration products at a microscopic level, creating a synergistic effect between the two. It is worth noting that since the silane coupling agent in the suspension is a concrete additive that reacts with the OH bonds of the mineral surface and the hydration products to form a more compact structure, the carbon nanotube suspension cannot be added directly in step S2. Instead, the raw materials must be added according to the steps of the present invention.

[0010] Step S4, adding the second portion of water to the second mixture and stirring again to obtain a slurry with a certain solid content;

[0011] Step S5: pouring the slurry into a mold and curing the mold to obtain a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes.

[0012] The water in the preparation is added twice: the first time, 50% of the water is added in step S1 to prepare the carbon nanotube suspension, and the second time, the remaining 50% is added in step S4; the silane coupling agent is selected from one of KH-550, KH-560, KH-570, and KH-792; the carbon nanotubes are carboxylated multi-walled carbon nanotubes (CNTCOOH); the mass of PVP and carbon nanotubes is 1:1, and the mass of the carbon nanotubes shall not exceed 0.2% of the mass of cement; the mass of the silane coupling agent is 10 times the mass of the carbon nanotubes; compared with ordinary carbon nanotubes, the carbon nanotubes after carboxylation treatment not only have better dispersibility, but the silane coupling agent will chemically react with the COOH bonds of the carboxylated carbon nanotubes to form minerals, hydration products, and carbon nanotube interconnects, further improving the strength.

[0013] Raw material mass ratio: basalt fiber: carbon nanotube: PVP: silane coupling agent: lithium feldspar tailings: cement: water = 1: 0.04-0.5: 0.04-0.5: 0.4-5: 99.2-443.2: 11.3-99.8: 83.6-269.2;

[0014] The solid content of the slurry is 65-75%.

[0015] Optionally, in step S1, the carbon nanotubes are carboxylated carbon nanotubes with a purity of more than 95%, an inner diameter of 3-5 nm, an outer diameter of 8-15 nm, and a length of 5-15 microns. The preparation of the carbon nanotube suspension requires ultrasonic treatment at 45 degrees Celsius for 30 minutes.

[0016] Optionally, in step S2, the basalt fiber has a length of 6-12 mm, the cement is ordinary Portland cement with a strength of 42.5, and the stirring time is not less than 2 minutes.

[0017] Optionally, in step S3, the stirring time is not less than 3 minutes.

[0018] Optionally, in step S4, the stirring time is not less than 3 minutes.

[0019] Optionally, in step S5, the curing process is to place the filling body in a constant temperature and humidity curing box with a curing temperature of (20±5)°C and a relative humidity of (95±5%) for 7 days.

[0020] Optionally, the optimal silane coupling agent is KH-792, the optimal raw material ratio is 0.1% carbon nanotubes (i.e., the mass fraction of carbon nanotubes in cement), 0.4% fiber (i.e., the mass fraction of fiber in (fiber + cement)), solid content 70% (i.e., cement + tailings / water + cement + tailings), and the ratio of cement mass to tailings mass is 1 / 4.

[0021] Optionally, the application of basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body in space filling.

[0022] The lithium feldspar tailings used in the present invention are taken from a mine in Yichun. The tailings are fine in particles and are off-white in color.

[0023] Optimization of filling sample preparation conditions: Based on an orthogonal experimental design, four coupling agents were used, with a content of 10 times the mass of carbon nanotubes. The carbon nanotube mass ranged from 0.05% to 0.2% (cement mass fraction) in increments of 0.05% per group, and the basalt fiber content ranged from 2% to 8% in increments of 2% per group. Solids contents were set at 65%, 68%, 70%, and 75%, and the cement-to-tailings ratios were 1 / 4, 1 / 6, 1 / 8, and 1 / 10, resulting in 16 groups. Carboxylated carbon nanotubes, polyvinylpyrrolidone (PVP), and a silane coupling agent were weighed, added to 50% water in proportion, and placed in an ultrasonic processor at 45 degrees Celsius for 30 minutes to obtain a carbon nanotube suspension. The lithium feldspar tailings, cement, and basalt fiber were evenly mixed in a blender for 3 minutes, followed by stirring of the carbon nanotube suspension. The remaining 50% water was then added and stirred. The prepared filling slurry was then poured into a standard mold. The dimensions of the rectangular mold were 40 mm × 40 mm × 160 mm, and the cylindrical mold was 50 mm in diameter and 100 mm in height.

[0024] Curing of filling body samples: Place all prepared filling body samples in a constant temperature and humidity curing box with a curing temperature of (20±5)℃ and a relative humidity of (95±5%) for 7 days.

[0025] Three-point bend test of the filling specimens for flexural strength testing: After the predetermined curing time of 7 days, the specimens were removed and polished smooth on both the top and bottom surfaces to meet the flatness requirements of the three-point bend test. The three-point bend test was conducted using an electronic universal testing machine with an actual span of 100 mm and a loading rate of 0.1 mm / min. The displacement at the loading point was used as the bending deflection value of the specimen. A computer recorded the entire test process, ultimately yielding the specimen's displacement-load curve and flexural strength. Three filling specimens were tested for each group, and the average value was calculated as the final flexural strength value. The strength values ​​of the filling specimens in the same group remained within ±15%. The maximum load of the universal electronic press was 20,000 N, the pressure sensor had an accuracy of 0.01 N, and the displacement sensor had an accuracy of 0.001 mm.

[0026] Uniaxial compressive strength testing of filling specimens: After the predetermined 7-day curing period, the specimens were removed and polished flat on both the top and bottom surfaces to meet the flatness requirements for uniaxial compression testing. The uniaxial compression test was conducted using an electronic universal testing machine with a loading rate of 0.1 mm / min. A computer recorded the entire test process, ultimately providing the specimen's stress-strain curve and compressive strength. Three filling specimens were tested for each group, and the average value was calculated as the final compressive strength value. The strength values ​​for the same group of filling specimens remained within ±15%. The maximum load of the universal electronic press was 20,000 N, the pressure sensor had an accuracy of 0.01 N, and the displacement sensor had an accuracy of 0.001 mm.

[0027] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0028] The present invention's method for preparing a basalt fiber- and carbon nanotube-incorporated lithium feldspar tailings cemented backfill using basalt fiber, carbon nanotubes, and lithium feldspar tailings as aggregates significantly improves the backfill's flexural strength, increases its compressive strength, and reduces fiber usage. This reduces the amount of cement used in the backfill, making mine operations more consistent with green mining principles. Furthermore, the reduced fiber usage improves the performance of the cemented backfill, resulting in improved fluidity and greater suitability for on-site applications and green mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 Schematic diagram of the preparation method of the present invention;

[0031] Figure 2 This is a bar graph of the flexural strength of the lithium feldspar tailings cemented filling body doped with basalt fiber and carbon nanotubes according to the present invention;

[0032] Figure 3 This is a bar graph of the compressive strength of the filling body of the lithium feldspar tailings cemented filling body doped with basalt fiber and carbon nanotubes in the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] raw material:

[0035] Lithium feldspar tailings: taken from the flotation tailings of a mine in Yichun. The tailings are fine-grained and off-white in color.

[0036] Basalt fiber: Common commercially available basalt fiber length is 6-12mm;

[0037] Carbon nanotubes: Use carboxylated carbon nanotubes with a purity of more than 95%, an inner diameter of 3-5nm, an outer diameter of 8-15nm, and a length of 5-15 microns;

[0038] Polyvinylpyrrolidone: experimental grade powdered polyvinylpyrrolidone reagent;

[0039] Silane coupling agent: experimental grade liquid silane coupling agent;

[0040] Cement: Ordinary commercial Portland cement with a strength of 42.5. Example

[0041] 0.05 parts of carboxylated carbon nanotubes, 0.05 parts of polyvinyl pyrrolidone, and 0.5 parts of silane coupling agent KH-550 were added to 134.6 parts of water and ultrasonically treated to obtain a carbon nanotube suspension;

[0042] Take 1 part of basalt fiber, 99.8 parts of cement and 399.2 parts of lithium feldspar tailings, add them into a blender and mix them evenly to obtain a first mixture, and stir for more than 3 minutes;

[0043] Add the carbon nanotube suspension to the first mixture obtained in step (2), and mix and stir in a blender for more than 3 minutes;

[0044] 134.6 parts of water were added to the second mixture obtained in step (3), and the mixture was mixed and stirred in a blender for more than 3 minutes to obtain a slurry with a concentration of 65%;

[0045] (5) The slurry obtained in step (4) is poured into a mold and placed in a constant temperature and humidity curing box with a curing temperature of (20±5)°C and a relative humidity of (95±5%) for a curing period of 7 days to obtain a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body.

[0046] Example 2

[0047] The method and steps are the same as those in Example 1, except that 0.035 parts of carboxylated carbon nanotubes, 0.035 parts of polyvinyl pyrrolidone, 0.35 parts of silane coupling agent KH-550, 35.6 parts of cement, 213.4 parts of lithium feldspar tailings and 117.6 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0048] The method and steps are the same as those in Example 1, except that 0.028 parts of carboxylated carbon nanotubes, 0.028 parts of polyvinyl pyrrolidone, 0.28 parts of silane coupling agent KH-550, 18.4 parts of cement, 147.2 parts of lithium feldspar tailings and 71.4 parts of water are used to prepare a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body. Example

[0049] The method and steps are the same as those in Example 1, except that 0.05 parts of carboxylated carbon nanotubes, 0.023 parts of polyvinyl pyrrolidone, 0.23 parts of silane coupling agent KH-550, 11.3 parts of cement, 113 parts of lithium feldspar tailings and 41.8 parts of water are used to prepare a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body. Example

[0050] The method and steps are the same as those in Example 1, except that 0.05 parts of carboxylated carbon nanotubes, 0.05 parts of polyvinyl pyrrolidone, 0.5 parts of silane coupling agent KH-560, 55.4 parts of cement, 443.2 parts of lithium feldspar tailings and 235.1 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0051] The method and steps are the same as those in Example 5, except that 0.035 parts of carboxylated carbon nanotubes, 0.035 parts of polyvinyl pyrrolidone, 0.35 parts of silane coupling agent KH-560, 22.6 parts of cement, 226 parts of lithium feldspar tailings and 134.4 parts of water are used to prepare a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body. Example

[0052] The method and steps are the same as those in Example 5, except that 0.028 parts of carboxylated carbon nanotubes, 0.028 parts of polyvinyl pyrrolidone, 0.28 parts of silane coupling agent KH-560, 33.1 parts of cement, 132.4 parts of lithium feldspar tailings and 55.5 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0053] The method and steps are the same as those in Example 5, except that 0.023 parts of carboxylated carbon nanotubes, 0.023 parts of polyvinyl pyrrolidone, 0.23 parts of silane coupling agent KH-560, 17.7 parts of cement, 106.2 parts of lithium feldspar tailings and 53.5 parts of water are used to prepare a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body. Example

[0054] The method and steps are the same as those in Example 1, except that 0.05 parts of carboxylated carbon nanotubes, 0.05 parts of polyvinyl pyrrolidone, 0.5 parts of silane coupling agent KH-570, 49.9 parts of cement, 235.7 parts of lithium feldspar tailings and 235.7 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0055] The method and steps are the same as those in Example 9, except that 0.035 parts of carboxylated carbon nanotubes, 0.035 parts of polyvinyl pyrrolidone, 0.35 parts of silane coupling agent KH-570, 27.7 parts of cement, 221.6 parts of lithium feldspar tailings and 83.4 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0056] The method and steps are the same as those in Example 9, except that 0.028 parts of carboxylated carbon nanotubes, 0.028 parts of polyvinyl pyrrolidone, 0.28 parts of silane coupling agent KH-570, 23.7 parts of cement, 142.2 parts of lithium feldspar tailings and 89.9 parts of water are used to prepare a basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body. Example

[0057] The method and steps are the same as those in Example 9, except that 0.023 parts of carboxylated carbon nanotubes, 0.023 parts of polyvinyl pyrrolidone, 0.23 parts of silane coupling agent KH-570, 24.8 parts of cement, 99.2 parts of lithium feldspar tailings and 58.8 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0058] The method and steps are the same as those in Example 1, except that 0.05 parts of carboxylated carbon nanotubes, 0.05 parts of polyvinyl pyrrolidone, 0.5 parts of silane coupling agent KH-792, 71.3 parts of cement, 427.8 parts of lithium feldspar tailings and 166.7 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0059] The method and steps are the same as those in Example 13, except that 0.035 parts of carboxylated carbon nanotubes, 0.035 parts of polyvinyl pyrrolidone, 0.35 parts of silane coupling agent KH-792, 49.8 parts of cement, 199.2 parts of lithium feldspar tailings and 107.1 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0060] The method and steps are the same as those in Example 13, except that 0.028 parts of carboxylated carbon nanotubes, 0.028 parts of polyvinyl pyrrolidone, 0.28 parts of silane coupling agent KH-792, 15.1 parts of cement, 151 parts of lithium feldspar tailings and 78.6 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes. Example

[0061] The method and steps are the same as those in Example 13, except that 0.023 parts of carboxylated carbon nanotubes, 0.023 parts of polyvinyl pyrrolidone, 0.23 parts of silane coupling agent KH-792, 13.8 parts of cement, 110.4 parts of lithium feldspar tailings and 41.8 parts of water are used to prepare a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes.

[0062] The specific ratio of each raw material is shown in Table 1;

[0063] Result detection

[0064] The basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling body prepared in the above embodiment was subjected to a three-point bending test and uniaxial compression test at a loading rate of 0.1 mm / min in a 20 kN electronic universal testing machine. The results are shown in Table 2:

[0065] Table 1 Ratio of raw materials for the cemented filling body of lithium feldspar tailings mixed with basalt fiber and carbon nanotubes

[0066]

[0067] Table 2 Orthogonal experimental scheme and flexural and compressive strengths of basalt fiber and carbon nanotube-doped lithium feldspar tailings cemented filling

[0068]

[0069] The KH dosage is 10 times the mass of the CNTCOOH. As shown in Table 2 and Figures 2 and 3, based on the aforementioned comparative analysis of the effects of silane coupling agent type, carbon nanotube content, solids content, fiber content, and cement-to-tailings ratio on flexural strength and uniaxial compressive strength in three-point bending tests, and based on the analysis results and comprehensive economic cost considerations, it can be inferred that the optimal ratio of basalt fiber and carbon nanotube-infused lithium feldspar tailings cemented backfill, using fiber and tailings as aggregates, is: KH-792 silane coupling agent, basalt fiber content of 0.4% (solids mass fraction), carbon nanotubes of 0.1% (cement mass fraction), solids content of 70%, and cement-to-tailings mass ratio of 1 / 4. The basalt fiber and carbon nanotube lithium feldspar tailings cemented filling body prepared according to this ratio has good flexural strength and compressive strength. During the filling mining process, it can reduce the amount of cement used and reduce tailings accumulation, and can achieve the purpose of coordinated green mining and governance. To a certain extent, it can adapt to the needs of diversified filling in mines.

[0070] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes, characterized in that: include: Step S1: taking carboxylated carbon nanotubes and PVP, adding a first portion of water, stirring to obtain a preliminary carbon nanotube suspension, then adding a silane coupling agent, and ultrasonicating to obtain a carbon nanotube suspension; Step S2: taking lithium feldspar tailings and basalt fiber as aggregates and cement as a gelling material, and stirring them evenly to obtain a first mixture; Step S3, adding the carbon nanotube suspension to the first mixture and stirring again to obtain a second mixture; Step S4, adding the second portion of water to the second mixture and stirring again to obtain a slurry with a certain solid content; Step S5: pouring the slurry into a mold and curing it to obtain a lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes; The mass ratio of each material is: basalt fiber: carbon nanotube: PVP: silane coupling agent: lithium feldspar tailings: cement: water = 1: 0.04-0.5: 0.04-0.5: 0.4-5: 99.2-443.2: 11.3-99.8: 83.6-269.

2.

2. The method according to claim 1, characterized in that The amount of the first part of water and the second part of water is 50% of the total amount of water added; the silane coupling agent is selected from one of KH-550, KH-560, KH-570, and KH-792; the carbon nanotubes are carboxylated multi-walled carbon nanotubes; the mass of PVP and carbon nanotubes is 1:1, and the mass of carbon nanotubes shall not exceed 0.2% of the mass of cement; the mass of silane coupling agent is 10 times the mass of carboxylated carbon nanotubes.

3. The method according to claim 1, characterized in that The solid content of the slurry is 65-75%.

4. The method according to claim 1, wherein In step S1, the carbon nanotubes are carboxylated carbon nanotubes with a purity of more than 95%, an inner diameter of 3-5 nm, an outer diameter of 8-15 nm, and a length of 5-15 μm. The carbon nanotube suspension is prepared by ultrasonication at 45° C. for 30 min.

5. The method according to claim 1, wherein In step S2, the length of the basalt fiber is 6-12 mm, the cement is ordinary Portland cement with a strength of 42.5, and the stirring time is not less than 2 minutes.

6. The method according to claim 1, wherein In step S3 and step S4, the stirring time is no less than 3 minutes.

7. The method according to claim 1, characterized in that In step S5, the curing process is to place the filling body in a constant temperature and humidity curing box with a curing temperature of 20±5°C and a relative humidity of 95±5% for 7 days.

8. The method according to claim 1, characterized in that The silane coupling agent is KH-792, the raw material ratio is 0.1wt% carbon nanotubes, 0.4wt% fiber, 70wt% slurry solid content, and the ratio of cement mass to tailings mass is 1 / 4.

9. Use of the lithium feldspar tailings cemented filling body doped with basalt fibers and carbon nanotubes prepared by the method according to any one of claims 1 to 8 in space filling.

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