Fluidized solidified loess for coal mine filling and preparation method and application thereof

Abstract

The invention belongs to the technical field of mine goaf filling materials, and particularly discloses flow-state solidified loess for coal mine filling and a preparation method and application of the flow-state solidified loess. According to the method, rich loess resources in the loess plateau area are used for preparing the flow-state solidified loess for coal mine filling, the coal mine recovery rate can be increased, the filling material cost is reduced, the problem that stones in the loess plateau area are insufficient is solved, the toughness and dry shrinkage resistance of the solidified flow-state solidified loess can be improved, and the problem that the loess is soft and swelled when meeting water is effectively solved. The curing agent for the fluid-state cured loess is developed according to the characteristics of loess of loess plateau and the characteristics of early strength, fluidity, pumpability, crack resistance and the like required by filling of the fluid-state cured loess, the alkali excitation mechanism, the pozzolanic effect, the secondary hydration reaction and other mechanisms are utilized, and proper functional components such as early strength, water retention and crack resistance are compounded, so that the curing agent for the fluid-state cured loess is prepared. The curing agent can effectively solve the common problems of air shrinkage, easy cracking, low strength and the like when a commercially available curing agent is used for preparing flow-state cured loess.

Description

Technical Field

[0001] This invention belongs to the technical field of filling materials for mining goaf areas, specifically relating to a fluidized solidified loess for coal mine filling, its preparation method, and its application. Background Technology

[0002] Coal mining is a crucial component of my country's energy industry. The Loess Plateau region of my country boasts abundant coal reserves, but with increasing mining depth and dwindling resources, traditional mining methods are revealing their limitations and facing growing challenges. Early insufficient understanding of the importance of backfilling in coal mines, coupled with low utilization rates of coal gangue, has resulted in low recovery rates. After underground coal mining is completed, large mine pits remain, easily triggering natural disasters such as collapses and soil erosion, negatively impacting the local ecological environment and human life. Therefore, the treatment of mined-out areas is a thorny issue.

[0003] Nowadays, with the improvement of mining techniques and the enhancement of environmental awareness, backfilling mining is receiving increasing attention. Using inexpensive materials with a certain strength to fill mined-out areas can control surface subsidence caused by coal mining and fully recover coal resources. For example, Chinese patent application CN116332602A (Shaanxi Xiaobaodang Mining Co., Ltd., Shaanxi Tiandi Geological Co., Ltd.) discloses a paste material for coal mining, which is made by mixing waste road concrete, slag, fly ash, silica fume, cement, etc., in a certain proportion. Its slump is 18-22 cm, and its 28-day compressive strength can reach 7.8 MPa. Although this backfill material has high compressive strength, its paste state makes it difficult to pump. For some old mine pits, it requires advanced construction techniques, making backfilling mining difficult. Furthermore, large-scale mine pit backfilling requires a large amount of waste road concrete, and the raw materials are not readily available. Furthermore, Chinese patent CN115259778B (Xinjiang Uygur Autonomous Region Coal Science Research Institute) discloses a coal gangue-incineration ash-based cemented backfill material for mining. The process involves calcining coal gangue particles, activating them, mixing them with incineration ash, and ball milling the mixture. The resulting composite micro-powder is then hydrated to form a cementitious material, which is then mixed with a second batch of coal gangue particles. The resulting cemented backfill aggregate is then mixed with a retarder, an early-strength agent, and mine water to obtain the cemented backfill material. While this material effectively controls overburden deformation in goaf areas (28-day compressive strength exceeding 5 MPa), the high cost and energy consumption of crushing and calcining coal gangue hinder cost control for backfilling. Additionally, coal gangue from some older mines has already been transported and repurposed elsewhere, making it impossible to utilize local resources to reduce costs. Moreover, the Loess Plateau region suffers from a scarcity of stone and insufficient backfill materials, resulting in high costs for purchasing aggregates or concrete. To address this issue, Chinese patent application CN102619559A (Shaanxi Kaituo Construction Technology Co., Ltd.) discloses a fluid material for filling goaf areas in mines. Using water as a transport medium, it comprises high-water-content materials, gangue concrete, foamed concrete, and a slurry mixture of loess, sand, and water. During construction, the mixture is first stirred at a ground-based mixing plant according to a pre-designed ratio, and then pumped into a disposable, flexible, enclosed mold in the underground goaf area via a mud pump or its own weight for phased filling. This patent utilizes locally sourced loess to prepare the fluid filling material, which is beneficial for cost control. However, the specific composition of the raw materials is not provided in the patent application, making it difficult to learn from or adapt.

[0004] In summary, developing a low-cost, high-performance coal mine backfill material is of great significance for goaf treatment. Summary of the Invention

[0005] The main technical problem solved by this invention is to provide a fluidized solidified loess for coal mine backfilling and its preparation method. By utilizing the abundant loess resources in the Loess Plateau region to prepare fluidized solidified loess for coal mine backfilling, it can not only improve the coal mine recovery rate, reduce the cost of backfilling materials, and solve the problem of insufficient stone in the Loess Plateau region, but also improve the toughness and resistance to drying shrinkage of the fluidized solidified loess after solidification. It effectively solves the problems of loess swelling when exposed to water and the common problems of drying shrinkage, easy cracking, and low strength of backfilling loess prepared with other commercially available solidifying agents.

[0006] Secondly, the present invention provides a curing agent for preparing fluidized solidified loess.

[0007] Furthermore, this invention provides an application of fluidized solidified loess in coal mine backfilling.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] A solidifying agent for fluidized loess, comprising, by weight, the following raw materials:

[0010] 20-40 parts of silicate cement;

[0011] 40-70 parts of slag powder;

[0012] 0.2-5 parts calcium chloride;

[0013] Hypo 0-3 parts;

[0014] 0-1 part water-reducing agent;

[0015] 6-12 parts of fluorinated gypsum;

[0016] 2-7 parts alkali;

[0017] 0.1-0.5 parts of calcium sulfoaluminate;

[0018] 2-5 parts of redispersible latex powder;

[0019] 0.1-0.3 parts of dextrin;

[0020] Xanthan gum 0-0.2 parts.

[0021] In a preferred embodiment of the present invention, the silicate cement is commercially available ordinary silicate cement of strength grade 32.5, 42.5 or 52.5, and the corresponding technical indicators meet the requirements of standard GB 175-2023 "General Silicate Cement".

[0022] As a preferred embodiment of the present invention, the slag powder is commercially available S95 or S105 grade granulated blast furnace slag powder, and the corresponding technical indicators meet the requirements of standard GB / T 18046-2017 "Granulated Blast Furnace Slag Powder for Cement, Mortar and Concrete".

[0023] In a preferred embodiment of the present invention, the calcium chloride is calcium chloride dihydrate, which can promote the early strength and rapid setting of fluidized solidified loess.

[0024] Specifically, the sodium thiosulfate mentioned is sodium thiosulfate, which can improve the early strength of fluidized solidified loess.

[0025] Specifically, the water-reducing agent is a commercially available naphthalene-based water-reducing agent or calcium lignosulfonate water-reducing agent, both of which are in powder form and have good compatibility with other materials. At the same time, they have better compatibility with other high-performance water-reducing agents in loess solidification.

[0026] In a preferred embodiment of the present invention, the alkali is selected from one or two of calcium hydroxide and sodium hydroxide.

[0027] Specifically, the composition of the alkali is: 2-5 parts calcium hydroxide and 0-2 parts sodium hydroxide.

[0028] As a preferred embodiment of the present invention, the redispersible latex powder is a commercially available water-soluble redispersible powder. After being dissolved in water, it can effectively bind and combine other materials, improve the fluidity and toughness of the fluidized solidified loess, and has a good synergistic effect with dextrin, xanthan gum, etc.

[0029] In a preferred embodiment of the present invention, the dextrin is maltodextrin, which can effectively improve the water retention of the curing agent, reduce the bleeding rate of fluidized solidified loess, and further promote coagulation and strength improvement.

[0030] A fluidized solidified loess for coal mine backfilling, comprising, by weight, the following raw materials:

[0031] 100 portions of loess;

[0032] 5-40 parts of curing agent;

[0033] Basalt fiber 0.5-2 parts;

[0034] 30-90 parts water.

[0035] In a preferred embodiment of the present invention, the raw materials for preparing the fluidized solidified loess, by weight, include:

[0036] 100 portions of loess;

[0037] 20-25 parts of curing agent;

[0038] Basalt fiber 0.5-1.5 parts;

[0039] 50-60 parts water.

[0040] In a preferred embodiment of the present invention, the loess has a particle size of less than 5 mm, a liquid limit of 24.8-31.5%, and a plastic limit of 15.7-19.2%.

[0041] Specifically, the raw loess is screened to obtain loess with a particle size of less than 5mm while removing other impurities contained in the soil.

[0042] In a preferred embodiment of the present invention, the particle size of the curing agent is less than 50 μm.

[0043] In a preferred embodiment of the present invention, the basalt fiber is a short-cut fiber with a length of 5-12 mm. Basalt fiber is a novel inorganic non-metallic fiber with superior performance, exhibiting good water resistance, chemical corrosion resistance, and high-temperature resistance. It is also non-toxic, pollution-free, inexpensive, and cost-effective, and possesses certain moisturizing properties.

[0044] A method for preparing fluidized solidified loess for coal mine backfilling includes the following steps:

[0045] Loess, solidifying agent and basalt fiber are mixed evenly, and water is added to continue mixing to obtain fluidized solidified loess.

[0046] In a preferred embodiment of the present invention, the preparation method includes the following steps:

[0047] Accurately weigh each raw material, mix loess and solidifying agent evenly (e.g., stir at low speed), then add basalt fiber in batches and mix, and finally add water and continue mixing (stir slowly for 3-8 minutes, then stir quickly for 1-5 minutes) to obtain fluidized solidified loess.

[0048] Application of fluidized solidified loess for coal mine backfilling.

[0049] As a preferred embodiment of the present invention, the application includes the following steps:

[0050] The fluidized solidified loess is pumped to the underground mining area for filling and solidification.

[0051] Specifically, the fluidized solidified loess is pumped to the underground mining area through a conveying and feeding pipe for backfilling. After the fluidized solidified soil has solidified and hardened, it can be pumped backfilling again at an optional location.

[0052] The beneficial effects of this invention are:

[0053] This invention provides a solidifying agent for fluidized loess, specifically developed to address the characteristics of loess in the Loess Plateau and the early strength, fluidity, pumpability, and crack resistance required for fluidized loess filling. Utilizing alkali activation, pozzolanic effect, and secondary hydration mechanisms, and incorporating appropriate functional components for early strength, water retention, and crack resistance, it effectively solves common problems encountered by commercially available solidifying agents in preparing fluidized loess, such as shrinkage, easy cracking, and low strength. Under natural environmental conditions, loess contains low levels of activators and effective alkali components, while slag powder contains a large amount of amorphous glassy components with potential cementing activity. Therefore, the addition of slag powder, cement, and alkaline substances significantly increases the total amount of active substances and the alkaline environment, promoting the pozzolanic reaction of slag and cement to generate a large amount of hydraulic gel products with cementing properties, such as CASH and N, i.e., alkali activation and pozzolanic effect. After the above reaction, a large amount of Ca(OH)2 remains, some of which undergoes ionization in the pores, releasing active Ca. 2+ Simultaneously, the pH of the pore solution rises, resulting in excess OH-. - Dissolves active colloidal Al2O3 and SiO2 in loess minerals, and active Ca 2+ The mixture then reacts to generate new CSH and CAH gel products, a secondary curing reaction that gradually densifies the structure of the solidified loess, making it less susceptible to water intrusion and thus achieving sufficient water stability. This is the main reason for the increased strength of the solidified loess in the later stages. Furthermore, calcium chloride and sodium thiosulfate can improve early strength, reduce bleeding, and regulate setting time, ensuring the 3-day compressive strength. Calcium sulfoaluminate provides micro-expansion, preventing crack formation and ensuring the later-stage strength of the fluidized solidified loess. Redispersible latex powder is an important component of the curing agent; supplemented with dextrin and xanthan gum, it can effectively reduce bleeding, promote rapid setting and early strength, and improve the toughness and impermeability of the fluidized solidified loess. Dextrin and xanthan gum can bind well with water molecules and further adhere to soil particles and basalt fibers. After being dissolved in water, redispersible latex powder forms a network-like polymer structure. Through the end group structure in the molecule, it forms hydrogen bonds or other weak intermolecular forces with dextrin and xanthan gum, thereby making the whole tightly bound. This effectively strengthens the bonding between the components of fluidized solidified loess and improves its compressive strength, impermeability, and erosion resistance.

[0054] This invention also provides a fluidized solidified loess prepared using this curing agent. Loess is the main raw material, reinforced and toughened with basalt fiber. By adjusting the dosage of each raw material, the compressive strength, impermeability, and erosion resistance after solidification are ensured. Compared to existing filling materials, the advantages of this invention are that the raw materials can be sourced locally, saving transportation costs. Furthermore, it makes rational use of loess in the Loess Plateau region, effectively solving the problem of stone shortage for filling in loess areas. The leveled land can also be used to build high-standard farmland, resulting in significant economic and social benefits. Detailed Implementation

[0055] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments and comparative examples. Those skilled in the art should understand that the following embodiments and comparative examples are only used to illustrate the technical solutions and effects of the present invention and should not be considered as any limitation on the scope of protection of the present invention. Based on the following embodiments, other technical solutions obtained by those skilled in the art without creative effort, such as those obtained through modification, variation, or simple substitution, are all within the scope of protection of the present invention. Where there is no conflict, technical features in different embodiments can be combined and substituted for each other.

[0056] In the embodiments and comparative examples of this invention, PO 42.5 cement and PO 52.5 cement were both purchased from Shanxi Chuandong Cement Co., Ltd.; S95 and S105 grade slag powders were both purchased from Zhengzhou Shuangke Machinery Equipment Co., Ltd.; water-reducing agent calcium lignosulfonate powder was purchased from Tianjin Huasheng Chemical Reagent Co., Ltd.; naphthalene powder was purchased from Shandong Wanshan Chemical Co., Ltd.; fluorogypsum was purchased from Yantai Anda Environmental Protection Technology Co., Ltd.; calcium sulfoaluminate was purchased from Wuhan Oungong Manpen Building Materials Co., Ltd.; redispersible latex powder was purchased from Oulaisi Chemical Co., Ltd.; and basalt fiber was purchased from Shanghai Chenqi Chemical Technology Co., Ltd.

[0057] Example 1

[0058] This embodiment provides a solidifying agent for fluidized loess, and the raw materials prepared by weight are as follows:

[0059] 25 parts of PO 42.5 cement;

[0060] 50 parts of S95 grade slag powder;

[0061] 0.3 parts of calcium chloride dihydrate;

[0062] 0.3 parts of calcium lignosulfonate powder;

[0063] 9 parts of fluorinated gypsum;

[0064] 3 parts calcium hydroxide;

[0065] Sodium hydroxide 0.5 parts;

[0066] 0.1 parts of calcium sulfoaluminate;

[0067] 3 parts redispersible latex powder;

[0068] 0.1 part dextrin.

[0069] The preparation method of the solidifying agent for fluidized solidified loess in this embodiment includes the following steps:

[0070] Accurately weigh each raw material, mix them, and then grind them until the particle size is less than 50μm.

[0071] Examples 2-6

[0072] The raw materials and dosages of the solidifying agent for fluidized solidified loess in Examples 2-6 are shown in Table 1 below, and the preparation methods are basically the same as in Example 1.

[0073] In other embodiments of the present invention, the raw materials and dosage of the curing agent for fluidized solidified loess can be arbitrarily selected and adjusted within a given range without significantly affecting the properties and performance of the curing agent.

[0074] Table 1. Raw materials and dosages (parts by weight) for the preparation of solidifying agents for fluidized solidified loess in Examples 1-6.

[0075]

[0076]

[0077] Example 7

[0078] This embodiment provides a fluidized solidified loess for coal mine backfilling, and the raw materials prepared are as follows (by weight):

[0079] 100 portions of loess;

[0080] 10 parts of the curing agent prepared in Example 1;

[0081] 0.5 parts basalt fiber;

[0082] 50 parts water;

[0083] Loess near the mining site was excavated, and weeds, stones, and soil clods or other debris larger than 5mm were removed to obtain loess with a particle size of less than 5mm. The moisture content, liquid limit, and plastic limit of the loess were tested to determine that the loess met the requirements for use.

[0084] Basalt fibers are short-cut fibers with a length of 5-12 mm.

[0085] The method for preparing fluidized solidified loess in this embodiment includes the following steps:

[0086] 100 parts loess and 10 parts of the curing agent prepared in Example 1 were poured into a mixer and stirred at low speed until uniform. Then, 0.5 parts of basalt fiber were added in three batches during the stirring process. Finally, 50 parts of water were added and stirred slowly for 5 minutes, followed by rapid stirring for 3 minutes to obtain fluidized solidified loess for coal mine filling.

[0087] The application of fluidized solidified loess in coal mine backfilling in this embodiment includes the following steps:

[0088] The fluidized solidified loess is pumped to the underground mining area for filling and solidification.

[0089] Examples 8-16

[0090] The raw materials and dosages for the preparation of fluidized solidified loess used for coal mine backfilling in Examples 8-16 are shown in Table 2 below, and the preparation methods are basically the same as in Example 7.

[0091] In other embodiments of the present invention, the raw materials and amounts used in the preparation of fluidized solidified loess can be arbitrarily selected and adjusted within a given range without significantly affecting the properties of the fluidized solidified loess.

[0092] Comparative Example 1

[0093] This comparative example provides loess for coal mine backfilling, which differs from Example 7 in that: the curing agent used is P.O42.5 cement (i.e., ordinary Portland cement with a strength grade of 42.5); all other aspects are the same as in Example 7.

[0094] Comparative Example 2

[0095] This comparative example provides loess for coal mine backfilling, which differs from Example 7 in that: the curing agent is prepared by P.O42.5 cement, S95 grade slag powder and fluorogypsum in the weight proportions of Example 1, without adding other components; all other aspects are the same as Example 7.

[0096] Comparative Example 3

[0097] This comparative example provides loess for coal mine backfilling, which differs from Example 7 in that basalt fiber is not added; otherwise, it is the same as Example 7.

[0098] Comparative Example 4

[0099] This comparative example provides loess for coal mine backfilling, which differs from Example 13 in that: calcium chloride is not added to the curing agent, and other components are consistent with Example 3; everything else is the same as Example 13.

[0100] Comparative Example 5

[0101] This comparative example provides loess for coal mine backfilling, which differs from Example 14 in that: calcium sulfoaluminate is not added to the curing agent, and other components are consistent with Example 4; everything else is the same as Example 14.

[0102] Comparative Example 6

[0103] This comparative example provides loess for coal mine backfilling, which differs from Example 16 in that: redispersible latex powder and dextrin are not added to the curing agent, while other components remain the same as in Example 6; everything else is the same as in Example 16.

[0104] Comparative Example 7

[0105] This comparative example provides loess for coal mine backfilling, which differs from Example 15 in that: naphthalene powder is not added to the curing agent, while other components remain the same as in Example 5; everything else is the same as in Example 15.

[0106] Comparative Example 8

[0107] This comparative example provides loess for coal mine backfilling, which differs from Example 12 in that: calcium lignosulfonate powder is not added to the curing agent, while other components remain the same as in Example 2; everything else is the same as in Example 12.

[0108] Comparative Example 9

[0109] This comparative example provides loess for coal mine backfilling, which differs from Example 16 in that: no sodium thiosulfate is added to the curing agent, and other components are consistent with those in Example 6; everything else is the same as in Example 16.

[0110] Comparative Example 10

[0111] This comparative example provides loess for coal mine backfilling, which differs from Example 13 in that: xanthan gum is not added to the curing agent, and other components are consistent with Example 3; everything else is the same as Example 13.

[0112] Table 2. Raw materials and amounts (parts by weight) used in the preparation of loess for coal mine backfilling in the examples and comparative examples.

[0113]

[0114]

[0115] Experimental Example

[0116] (1) Expansion

[0117] The expansion was tested in accordance with the relevant provisions of the current national standard GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures".

[0118] (2) Condensation time

[0119] The initial and final setting times were tested in accordance with the current national standard GB / T 1346-2011, "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement".

[0120] (3) Perfusion rate

[0121] The bleeding rate was tested in accordance with the relevant provisions of the current national standard GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures".

[0122] (4) Cube compressive strength

[0123] The cube compressive strength was tested according to the "Test Methods for Basic Performance of Building Mortar" JGJ / T 70-2009.

[0124] The loess used for coal mine backfilling in the examples and comparative examples was subjected to the above-mentioned performance tests, and the test results are shown in Table 3 below.

[0125] Table 3 shows the performance test results of the loess used for coal mine backfilling in the examples and comparative examples.

[0126]

[0127]

[0128] Analysis shows that the main differences between Examples 7-11 lie in the amount of water, curing agent, and basalt fiber, with deeper differences in the water-to-solid ratio and water-to-cement ratio. The test results of these five examples demonstrate that the water-to-solid ratio significantly affects setting time and bleeding rate. While strength is also affected by the water-to-solid ratio, the influence is more pronounced by the water-to-cement ratio. Excessive water-to-cement and water-to-solid ratios result in lower compressive strength values. Therefore, preventing bleeding, adjusting setting time, and ensuring the effective bonding of the cementing material are crucial for the various properties of fluidized solidified loess. The preferred raw material amounts for fluidized solidified loess in this invention (by weight) are: 50-60 parts water, 100 parts loess, 0.5-1.5 parts basalt fiber, and 20-25 parts curing agent.

[0129] The comparison results between Comparative Examples 1-3 and Example 7 show that the fluidized solidified loess prepared using the curing agent of Example 7 has advantages in all aspects, but the curing agent that only retains cementitious materials and solid waste (such as slag powder) and lacks functional components also has poor effect.

[0130] Analysis suggests that due to the characteristics of collapsible loess and the problems of water bleeding and drying shrinkage cracking in fluidized solidified loess, the addition of functional components is essential. The comparison results between Examples 13-14 and 16 and Comparative Examples 4-6 highlight the importance of these functional components. Calcium chloride and sodium thiosulfate effectively improve early strength, reduce water bleeding, regulate setting time, and ensure 3-day compressive strength. Calcium sulfoaluminate provides micro-expansion, prevents crack formation, and ensures the later-stage strength of fluidized solidified loess. Dispersible latex powder is an important component of the curing agent in this invention; supplemented with dextrin and xanthan gum, it effectively reduces water bleeding, promotes rapid setting and early strength, and improves the toughness and impermeability of fluidized solidified loess. Dextrin and xanthan gum can bind well with water molecules and further adhere to soil particles and basalt fibers. After being dissolved in water, redispersible latex powder forms a network-like polymer structure. Through the end group structure in the molecule, it forms hydrogen bonds or other intermolecular forces with dextrin or xanthan gum, thus forming a tight overall bond. This effectively strengthens the bonding between the components of fluidized solidified loess and improves its compressive strength, impermeability, and erosion resistance.

[0131] Compared with the prior art, the advantages of the present invention are: it makes full use of the abundant loess resources in the Loess Plateau region, solves the problem of shortage of filling stone, effectively improves the toughness and anti-drying shrinkage of the solidified fluidized loess, and specifically solves the problems of loess swelling when exposed to water and the low strength and easy cracking of filling loess prepared by other types of solidifying agents.

[0132] Although the technical solutions and effects of the present invention have been described in detail above with general descriptions, specific embodiments and comparative examples, modifications, substitutions or improvements made by those skilled in the art without departing from the spirit and scope of the present invention shall all fall within the protection scope of the present invention.

Claims

1. A curing agent for fluidized solidified loess, characterized in that: The raw materials for preparation, by weight, include: 20-40 parts of silicate cement; 40-70 parts of slag powder; 0.2-5 parts calcium chloride; 0-3 parts of hypothalamic acid; 0-1 part water-reducing agent; 6-12 parts of fluorinated gypsum; 2-7 parts alkali; 0.1-0.5 parts of calcium sulfoaluminate; 2-5 parts of redispersible latex powder; 0.1-0.3 parts of dextrin; Xanthan gum 0-0.2 parts.

2. The curing agent according to claim 1, characterized in that: The silicate cement is ordinary silicate cement with a strength grade of 32.5, 42.5, or 52.5; And / or, the slag powder is S95 grade or S105 grade granulated blast furnace slag powder; And / or, the water-reducing agent is a naphthalene-based water-reducing agent or a calcium lignosulfonate water-reducing agent; And / or, the base is selected from one or two of calcium hydroxide and sodium hydroxide; And / or, the dextrin is maltodextrin.

3. The curing agent according to claim 1, characterized in that: The alkali is composed of 2-5 parts calcium hydroxide and 0-2 parts sodium hydroxide.

4. A type of fluidized solidified loess for coal mine backfilling, characterized in that: The raw materials for preparation, by weight, include: 100 portions of loess; 5-40 parts of the curing agent as described in any one of claims 1-3; Basalt fiber 0.5-2 parts; 30-90 parts water.

5. The fluidized solidified loess according to claim 4, characterized in that: The raw materials for preparation, by weight, include: 100 portions of loess; 20-25 parts of curing agent; Basalt fiber 0.5-1.5 parts; 50-60 parts water.

6. The fluidized solidified loess according to claim 4, characterized in that: The loess has a particle size of less than 5 mm, a liquid limit of 24.8-31.5%, and a plastic limit of 15.7-19.2%. And / or, the particle size of the curing agent is less than 50 μm; And / or, the basalt fiber is a short-cut fiber with a length of 5-12 mm.

7. A method for preparing fluidized solidified loess as described in any one of claims 4-6, characterized in that: Includes the following steps: Loess, solidifying agent and basalt fiber are mixed evenly, and water is added to continue mixing to obtain fluidized solidified loess.

8. The preparation method according to claim 7, characterized in that: Includes the following steps: Accurately weigh each raw material, mix loess and solidifying agent evenly, then add basalt fiber in batches and mix, and finally add water and continue mixing to obtain fluidized solidified loess.

9. The application of fluidized solidified loess as described in any one of claims 4-6 in coal mine backfilling.

10. The application according to claim 9, characterized in that: The application includes the following steps: The fluidized solidified loess is pumped to the underground mining area for filling and solidification.

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