A landfill slurry material, its preparation method and application in filling a coal gangue layer

Abstract

The present application discloses a landfill slurry material, a preparation method thereof, and an application in filling a coal gangue layer, relating to the technical field of coal mine landfill materials. The landfill slurry material comprises the following components in parts by weight: 5-15 parts of sodium alginate, 2-5 parts of a crosslinking agent, 30-45 parts of fly ash, 2-5 parts of sodium bicarbonate, 8-15 parts of loess, 2-6 parts of hydrotalcite, 3-8 parts of bentonite, 50-70 parts of a modified lignin solution, and 120-200 parts of water; the above-mentioned modified lignin solution comprises enzymatically hydrolyzed lignin, phenol, sodium hydroxide, and water; based on the mass of the modified lignin solution being 100%, the mass fraction of the enzymatically hydrolyzed lignin is 20%-25%, the mass ratio of phenol to the enzymatically hydrolyzed lignin is (0.5-0.6):1, and the mass ratio of sodium hydroxide to the enzymatically hydrolyzed lignin is (0.4-0.6):1. The landfill slurry material prepared from the above raw materials has good water retention and flame retardant properties, and has good permeability to the coal gangue layer.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine landfill materials, and more particularly, to a landfill slurry material, a preparation method thereof, and an application in filling a coal gangue layer. Background Art

[0002] Coal gangue without harmless treatment cannot be directly landfilled, and the amount of coal gangue in many mining areas can reach tens of thousands of tons, but the utilization rate is usually only about 5%, and it costs hundreds of millions of yuan to dispose of.

[0003] In the prior art, coal gangue is usually disposed of by setting it in coal mining subsidence areas, but the problem of spontaneous combustion of the accumulated coal gangue layer is not considered. Currently, the most important methods for preventing and controlling coal spontaneous combustion are measures such as grouting, filling, spraying, etc., to reduce or isolate air leakage, thereby playing a role in preventing and controlling coal spontaneous combustion. For example, grouting generally uses yellow mud, cement or fly ash, which are inexpensive, non-toxic and have good permeability, but their water retention is poor, they are prone to cracking, and lose their fire prevention and extinguishing functions. The costs of other gangue filling and mining technologies are high and the utilization rate is low, and they cannot meet the full resource recycling of gangue.

[0004] Therefore, exploring low-cost, harmless and resource-based coal gangue disposal technologies and applying them to coal mining subsidence areas has become an urgent task for the utilization of mineral resources and ecological protection in many mining areas. Summary of the Invention

[0005] The main object of the present invention is to provide a landfill slurry material, a preparation method thereof, and an application in filling a coal gangue layer, so as to solve the problem that there is no suitable method for disposing of coal gangue and resource recycling in the prior art.

[0006] To achieve the above object, according to the first aspect of the present invention, a landfill slurry material is provided, which comprises the following components in parts by weight: 5-15 parts of sodium alginate, 2-5 parts of crosslinking agent, 30-45 parts of fly ash, 2-5 parts of sodium bicarbonate, 8-15 parts of loess, 2-6 parts of hydrotalcite, 3-8 parts of bentonite, 50-70 parts of modified lignin solution, and 120-200 parts of water;

[0007] Among them, the modified lignin solution comprises enzymatically hydrolyzed lignin, phenol, sodium hydroxide and water; based on the mass of the modified lignin solution being 100%, the mass fraction of enzymatically hydrolyzed lignin is 20%-25%, the mass ratio of phenol to enzymatically hydrolyzed lignin is (0.5-0.6):1, and the mass ratio of sodium hydroxide to enzymatically hydrolyzed lignin is (0.4-0.6):1.

[0008] Further, the preparation method of the modified lignin solution is as follows: Mix enzymatically hydrolyzed lignin, phenol, sodium hydroxide, and water according to the ratio, and react at 60 - 70°C for 2 - 3 h in a closed environment to obtain the modified lignin solution.

[0009] Further, the crosslinking agent is at least one of aluminum sulfate, calcium chloride, and barium chloride.

[0010] Further, the landfill slurry material contains the following components in parts by weight: 5 - 10 parts of sodium alginate, 3 - 4 parts of crosslinking agent, 35 - 40 parts of fly ash, 3 - 4 parts of sodium bicarbonate, 10 - 12 parts of loess, 3 - 5 parts of hydrotalcite, 5 - 7 parts of bentonite, 55 - 65 parts of modified lignin solution, and 140 - 180 parts of water.

[0011] Further, the crosslinking agent is aluminum sulfate.

[0012] According to the second aspect of the present invention, a preparation method of the above landfill slurry material is provided. The preparation method includes the following steps:

[0013] S1. Mix fly ash and the modified lignin solution, and obtain a first mixture after mixing evenly; Dissolve sodium bicarbonate in part of the water to obtain a sodium bicarbonate solution, and then add bentonite to the sodium bicarbonate solution, and obtain a second mixture after mixing evenly.

[0014] S2. Mix the first mixture and the second mixture, add the remaining raw materials except the crosslinking agent thereto after mixing evenly, add the crosslinking agent after mixing evenly again, and obtain the landfill slurry material after mixing evenly again.

[0015] Further, in the above S1, the weight of part of the water is 5% - 15% of the total weight of the water.

[0016] Further, in the above S1, the mixing time of fly ash and the modified lignin solution is 3 - 8 min; and / or

[0017] In the above S2, the mixing time of the first mixture and the second mixture is 10 - 25 min; and / or

[0018] In the above S2, the mixing time after adding the remaining raw materials except the crosslinking agent is 5 - 10 min.

[0019] Further, the method of mixing evenly is adopted by stirring, and the stirring speed is 30 - 60 r / min.

[0020] According to the third aspect of the present invention, an application of the above landfill slurry material in filling a coal gangue layer is further provided.

[0021] Applying the technical solution of the present invention, the landfill slurry material has good water retention performance and flame retardant performance, has good permeability to the gangue layer, and has good fluidity, which is suitable for filling the gangue layer and realizing efficient resource utilization. Specific Embodiments

[0022] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0023] As described in the background art of the present invention, in the prior art, there are problems such as high difficulty in disposing of gangue, flammability after landfill, poor fluidity during grouting, and difficulty in achieving full resource recycling.

[0024] To solve the above problems, in a typical embodiment of the present invention, a landfill slurry material is provided. The landfill slurry material comprises the following components in parts by weight: sodium alginate 5 - 15 parts, crosslinking agent 2 - 5 parts, fly ash 30 - 45 parts, sodium bicarbonate 2 - 5 parts, loess 8 - 15 parts, hydrotalcite 2 - 6 parts, bentonite 3 - 8 parts, modified lignin solution 50 - 70 parts, and water 120 - 200 parts;

[0025] Among them, the modified lignin solution comprises enzymatically hydrolyzed lignin, phenol, sodium hydroxide, and water; based on the mass of the modified lignin solution being 100%, the mass fraction of enzymatically hydrolyzed lignin is 20% - 25%, the mass ratio of phenol to enzymatically hydrolyzed lignin is (0.5 - 0.6):1, and the mass ratio of sodium hydroxide to enzymatically hydrolyzed lignin is (0.4 - 0.6):1.

[0026] In the landfill slurry material of this application, a triple crosslinking system is adopted. One is the crosslinking system of sodium alginate and the crosslinking agent, the second is the crosslinking system constructed by the modified lignin solution, and the third is the multi - level crosslinked network structure of fly ash under the action of alkalinity. The landfill slurry material prepared through the above triple crosslinking system has a moderate viscosity, is easy to fill, has a high water retention rate of the slurry, high mechanical strength, and its flame retardant performance can also meet the use requirements. It is an excellent landfill slurry material. Specifically:

[0027] Natural lignin is a natural polyaromatic macromolecular compound composed of hydrophobic non-polar groups with a phenylpropane skeleton and hydrophilic polar groups such as phenolic groups. However, the existing natural lignin has insufficient reactivity. Based on this, the present invention first conducts alkaline modification on lignin to increase its active sites. After modification, there are more active sites in the lignin, which can then form a certain self-crosslinking network structure. When used in combination with the sodium alginate gel system, it can greatly improve the toughness and ductility of the sodium alginate gel system, thereby significantly improving its water retention performance and further enhancing its fire prevention and extinguishing performance. In addition, alkalis such as unreacted sodium hydroxide in the modified lignin solution can also initially activate and crosslink fly ash. Then, bentonite and sodium bicarbonate are combined. Bentonite can effectively adsorb and slowly release sodium bicarbonate. When it is mixed with the two systems of the modified lignin solution and fly ash, on the one hand, sodium bicarbonate is also a weak base that can promote the further activation and crosslinking of fly ash; furthermore, sodium carbonate produced by the reaction of sodium bicarbonate and sodium hydroxide can promote the further activation and crosslinking of fly ash. Through the above-mentioned multiple activation and crosslinking effects, the formation of the self-crosslinking network of fly ash itself and the crosslinking network of fly ash and modified lignin can be better realized, further improving the mechanical properties and water retention performance of the gel system. Moreover, the divalent metal ions such as ferric ions and titanium tetravalent ions precipitated from the fully activated fly ash can also crosslink better with sodium alginate and be filled into the network skeleton structure. And after sufficient crosslinking, the adhesion between fly ash and coal is relatively strong, making it easier to fill into the coal gangue layer. The material has stable performance, good water retention, extremely high fire resistance, is not easy to break, and has good flexibility, belonging to a new generation of mine fire prevention and extinguishing materials.

[0028] The bentonite of the present invention is a good water-absorbing material that can absorb water and expand, further filling the gaps in the condensation network and improving the water retention and barrier effect. Moreover, after being modified with sodium bicarbonate, its water retention can be further improved. It is also a good flame retardant material. Furthermore, loess, hydrotalcite, etc. are also good flame retardant materials. The three are compounded to significantly improve the flame retardancy of the landfill slurry material.

[0029] As a preferred embodiment of the present invention, the preparation method of the above-mentioned modified lignin solution is: mixing enzymatic hydrolysis lignin, phenol, sodium hydroxide and water according to the ratio, and reacting at 60-70°C for 2-3h in a closed environment to obtain the modified lignin solution.

[0030] Using enzymatic hydrolysis lignin for modification can make the modified lignin have more active sites, which is more conducive to forming a stable network structure with the sodium alginate gel system and the fly ash crosslinking system, further improving the water retention and flame retardancy of the landfill slurry material.

[0031] Typically but not limited to, the above crosslinking agent is at least one of aluminum sulfate, calcium chloride, and barium chloride. The above crosslinking agents can all cause sodium alginate to form a gel; preferably aluminum sulfate, which will generate a certain amount of aluminum hydroxide under alkaline conditions. This can not only prevent the sodium alginate system from gelling too quickly, but the generated aluminum hydroxide is also a very good flame retardant material, which can improve the flame retardant effect.

[0032] As a preferred embodiment of the present invention, the above landfill slurry material comprises the following components in parts by weight: 5-10 parts of sodium alginate, 3-4 parts of crosslinking agent, 35-40 parts of fly ash, 3-4 parts of sodium bicarbonate, 10-12 parts of loess, 3-5 parts of hydrotalcite, 5-7 parts of bentonite, 55-65 parts of modified lignin solution, and 140-180 parts of water.

[0033] Making the above optimizations for the dosages of each component can improve the stability of the triple crosslinking system, better exert its flame retardant and water retention properties, and at the same time has good fluidity, improving its flame retardant stability.

[0034] The above enzymatic hydrolysis lignin is the commonly used enzymatic hydrolysis lignin in the prior art, and can be selected as the enzymatic hydrolysis lignin extracted from corn straw.

[0035] In another typical embodiment of the present invention, a preparation method of the above landfill slurry material is provided, and the preparation method comprises the following steps:

[0036] S1, mix fly ash and modified lignin solution, and obtain a first mixture after mixing evenly; dissolve sodium bicarbonate in part of the water to obtain a sodium bicarbonate solution, and then add bentonite to the sodium bicarbonate solution, and obtain a second mixture after mixing evenly;

[0037] S2; mix the first mixture and the second mixture, add the remaining raw materials except the crosslinking agent thereto after mixing evenly, add the crosslinking agent after mixing evenly again, and obtain the landfill slurry material after mixing evenly again.

[0038] By adopting the above specific feeding sequence, the prepared landfill slurry material has excellent water retention performance, good flame retardant effect, good permeability to the coal gangue layer, stable performance, and at the same time has the characteristic of low raw material cost, realizing the full resource recycling of coal gangue.

[0039] As a preferred embodiment of the present invention, in the above S1, the weight of part of the water is 5%-15% of the total weight of the water; and / or

[0040] In the above S1, the mixing time of fly ash and modified lignin solution is 3-8 min; and / or

[0041] In the above S2, the mixing time of the first mixture and the second mixture is 10-25 min; and / or

[0042] In S2 above, the mixing time after adding the remaining raw materials except the crosslinking agent is 5 - 10 min.

[0043] The above limitations on the preparation conditions are to ensure that all components can be fully mixed and improve the landfill uniformity.

[0044] As a preferred embodiment of the present invention, the method of stirring is adopted to mix evenly, and the stirring speed is 30 - 60 r / min.

[0045] In another typical embodiment of the present invention, an application of the above landfill slurry material in filling a coal gangue layer is provided. Filling the coal gangue layer with the above landfill slurry material has good water retention and flame retardant effects, and has good stability.

[0046] The following further describes the present application in detail with specific examples, and these examples should not be construed as limiting the scope claimed by the present application.

[0047] Enzymatic lignin: Extracted from corn straw, purchased from Songyuan Laihe Chemical Co., Ltd.;

[0048] Fly ash: Taken from Shangwan Thermal Power Plant of China Shenhua Energy Co., Ltd. in Ordos City, Inner Mongolia Autonomous Region;

[0049] Loess: Loess collected from the Shendong project demonstration site;

[0050] Hydrotalcite: Purchased from Jiangsu Bost Chemical Technology Co., Ltd.;

[0051] Bentonite: Taken from Zhongshun Bentonite Co., Ltd. in Inner Mongolia Autonomous Region.

[0052] Example 1

[0053] An embodiment of the landfill slurry material of the present invention. The raw materials of the landfill slurry material in this embodiment are shown in Table 1, and the preparation method is as follows:

[0054] S1, Prepare a modified lignin solution: Mix enzymatic lignin, phenol, sodium hydroxide and water under closed conditions, and react at 65 °C for 2.5 h to obtain a modified lignin solution; wherein, based on the mass of the modified lignin solution being 100%, the addition amount of enzymatic lignin is 22%, the mass ratio of phenol to enzymatic lignin is 0.5:1, the mass ratio of sodium hydroxide to enzymatic lignin is 0.5:1, and the balance is water;

[0055] S2, Add fly ash to the modified lignin solution, stir at a rate of 50 r / min for 5 min to obtain a first mixture; Mix bentonite, sodium bicarbonate and part of water, and the above part of water is 13 parts of water;

[0056] S3. Mix the first mixture and the second mixture, stir at a rate of 50 r / min for 15 min, then add the remaining raw materials except aluminum sulfate, stir at a rate of 50 r / min for 7 min, and finally add aluminum sulfate and mix evenly to obtain the landfill slurry material.

[0057] Example 2

[0058] An embodiment of the landfill slurry material of the present invention. The raw materials of the landfill slurry material in this embodiment are shown in Table 1, and the preparation method is as follows:

[0059] S1. Prepare the modified lignin solution: Mix enzymatically hydrolyzed lignin, phenol, sodium hydroxide and water under closed conditions and react at 70 °C for 2 h to obtain the modified lignin solution. Among them, based on the mass of the modified lignin solution being 100%, the addition amount of enzymatically hydrolyzed lignin is 20%, the mass ratio of phenol to enzymatically hydrolyzed lignin is 0.6:1, the mass ratio of sodium hydroxide to enzymatically hydrolyzed lignin is 0.6:1, and the balance is water.

[0060] S2. Add fly ash to the modified lignin solution and stir at a rate of 50 r / min for 8 min to obtain the first mixture; mix bentonite, sodium bicarbonate and a part of water to obtain the second mixture, and the above part of water is 11 parts of water.

[0061] S3. Mix the first mixture and the second mixture, stir at a rate of 50 r / min for 25 min, then add the remaining raw materials except aluminum sulfate, stir at a rate of 50 r / min for 5 min, and finally add aluminum sulfate and mix evenly to obtain the landfill slurry material.

[0062] Example 3

[0063] An embodiment of the landfill slurry material of the present invention. The raw materials of the landfill slurry material in this embodiment are shown in Table 1, and the preparation method is as follows:

[0064] S1. Prepare the modified lignin solution: Mix enzymatically hydrolyzed lignin, phenol, sodium hydroxide and water under closed conditions and react at 60 °C for 3 h to obtain the modified lignin solution. Among them, based on the mass of the modified lignin solution being 100%, the addition amount of enzymatically hydrolyzed lignin is 25%, the mass ratio of phenol to enzymatically hydrolyzed lignin is 0.5:1, the mass ratio of sodium hydroxide to enzymatically hydrolyzed lignin is 0.4:1, and the balance is water.

[0065] S2. Add fly ash to the modified lignin solution and stir at a rate of 50 r / min for 5 min to obtain the first mixture; mix bentonite, sodium bicarbonate and a part of water to obtain the second mixture, and the above part of water is 11 parts of water.

[0066] S3. Mix the first mixture and the second mixture, stir at a rate of 50 r / min for 20 min, then add the remaining raw materials except aluminum sulfate, stir at a rate of 50 r / min for 8 min, and finally add aluminum sulfate and mix evenly to obtain the landfill slurry material.

[0067] Example 4

[0068] An embodiment of the landfill slurry material of the present invention. The raw materials of the landfill slurry material in this embodiment are shown in Table 1, and the preparation method is as follows:

[0069] S1. Prepare the modified lignin solution: Mix enzymatic lignin, phenol, sodium hydroxide and water under closed conditions and react at 70 °C for 3 h to obtain the modified lignin solution; wherein, based on the mass of the modified lignin solution being 100%, the addition amount of enzymatic lignin is 20%, the mass ratio of phenol to enzymatic lignin is 0.5:1, the mass ratio of sodium hydroxide to enzymatic lignin is 0.6:1, and the balance is water;

[0070] S2. Add fly ash to the modified lignin solution and stir at a rate of 50 r / min for 7 min to obtain the first mixture; mix bentonite, sodium bicarbonate and a part of water to obtain the second mixture, and the above part of water is 15 parts of water;

[0071] S3. Mix the first mixture and the second mixture, stir at a rate of 50 r / min for 18 min, then add the remaining raw materials except aluminum sulfate, stir at a rate of 50 r / min for 7 min, and finally add aluminum sulfate and mix evenly to obtain the landfill slurry material.

[0072] Examples 5 - 6

[0073] Examples 5 - 6 are embodiments of the landfill slurry material of the present invention. The difference between Examples 5 - 6 and Example 1 is only that the weight parts of each component are different, as shown in Table 1 specifically.

[0074] Table 1 (weight parts)

[0075]

[0076]

[0077] Comparative Example 1

[0078] A landfill slurry material, the difference between it and Example 1 is only that in Comparative Example 1, water with the same mass is used to replace sodium hydroxide in the modified lignin solution in Example 1.

[0079] Comparative Example 2

[0080] A landfill slurry material, which is only different from that in Example 1 in that in Comparative Example 2, equal-mass fly ash and modified lignin solution are used to replace sodium alginate in Example 1, and the mass ratio of fly ash to modified lignin solution is 1:1.66.

[0081] Comparative Example 3

[0082] A landfill slurry material, which is only different from that in Example 1 in that in Comparative Example 3, equal-mass sodium alginate and modified lignin solution are used to replace fly ash in Example 1, and the mass ratio of sodium alginate to modified lignin solution is 1:7.5.

[0083] Comparative Example 4

[0084] A landfill slurry material, which is only different from that in Example 1 in that in Comparative Example 4, equal-mass water is used to replace sodium bicarbonate in Example 1.

[0085] Performance test

[0086] The landfill slurry materials described in Examples 1-6 and Comparative Examples 1-4 were subjected to performance tests. The test methods are as follows, and the test results are shown in Table 2. The test methods are as follows:

[0087] Final setting time: The final setting time of the landfill slurry material was measured by the electrical resistance method, and the inflection point of the resistivity-time curve corresponded to the final setting time.

[0088] Flame retardant property: A use scenario of a simulated coal gangue landfill site was prepared. The landfill slurry material was filled in the coal gangue layer, and the coal gangue layer filled with the landfill slurry material was heated at 50°C. Continuous counting and observation were carried out. If no fire occurred within 30 days, it was considered that the flame retardant property met the requirements.

[0089] Water loss rate of the landfill slurry material: The landfill slurry material was heated at 100°C for 1 h, and the water loss rate (%) was calculated through the weight difference before and after heating;

[0090] 7-day compressive strength: Standard test blocks of 10 cm × 10 cm × 10 cm were made with reference to GB / T50081-2019, and the compressive strength after 7 days of curing was detected.

[0091] Table 2

[0092]

[0093] As can be seen from Table 2, the final setting time of the landfill slurry material of the present invention is 10-35 min, it has good permeability, can be efficiently poured, and will not make the construction period too long, and all have good flame retardancy, water retention and compressive strength.

[0094] Comparing the performance test results of Comparative Examples 1-3 and Examples 4-6, it can be found that when the landfill slurry material contains 5-10 parts of sodium alginate, 3-4 parts of cross-linking agent, 35-40 parts of fly ash, 3-4 parts of sodium bicarbonate, 10-12 parts of loess, 3-5 parts of hydrotalcite, 5-7 parts of bentonite, 55-65 parts of modified lignin solution and 140-180 parts of water, its comprehensive performance is better, the final setting time is within 15-25 minutes, it will not set too quickly, resulting in difficult construction, nor will it set too slowly, resulting in an extended construction period. In addition, the water loss rate of the landfill slurry material can be maintained within 20%, and the 7-day compressive strength can reach above 4.5 MPa, which is more suitable for filling the coal gangue layer in the mining area.

[0095] Based on the prevention and control of spontaneous combustion of gangue and the dynamic regulation mechanism of pore structure, through reasonable raw material ratio, the prepared landfill slurry material is easy to flow and convenient for grouting. It can form a colloid after penetrating into the cracks of the coal gangue layer, isolate oxygen, etc., prevent the spontaneous combustion of the coal gangue layer, and has good water retention and mechanical strength, which is suitable for application in filling the coal gangue layer.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A landfill slurry material, characterized in that, It consists of the following components by weight: 5-15 parts of sodium alginate, 2-5 parts of cross-linking agent, 30-45 parts of fly ash, 2-5 parts of sodium bicarbonate, 8-15 parts of loess, 2-6 parts of hydrotalcite, 3-8 parts of bentonite, 50-70 parts of modified lignin solution and 120-200 parts of water; The modified lignin solution is composed of enzymatically hydrolyzed lignin, phenol, sodium hydroxide and water; the preparation method of the modified lignin solution is: mix enzymatically hydrolyzed lignin, phenol, sodium hydroxide and water according to the ratio, and react at 60-70 °C for 2-3 h in a closed environment to obtain the modified lignin solution; Calculated based on the mass of the modified lignin solution being 100%, the mass fraction of the enzymatically hydrolyzed lignin is 20%-25%, the mass ratio of the phenol to the enzymatically hydrolyzed lignin is (0.5-0.6):1, and the mass ratio of the sodium hydroxide to the enzymatically hydrolyzed lignin is (0.4-0.6):

1.

2. The landfill slurry material according to claim 1, wherein The cross-linking agent is at least one of aluminum sulfate, calcium chloride, and barium chloride.

3. The landfill slurry material according to claim 1, wherein It consists of the following components by weight: 5-10 parts of sodium alginate, 3-4 parts of cross-linking agent, 35-40 parts of fly ash, 3-4 parts of sodium bicarbonate, 10-12 parts of loess, 3-5 parts of hydrotalcite, 5-7 parts of bentonite, 55-65 parts of modified lignin solution and 140-180 parts of water.

4. The landfill slurry material according to claim 1, characterized in that, The cross-linking agent is aluminum sulfate.

5. A method for preparing a landfill slurry material according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1, mix fly ash and the modified lignin solution, and obtain the first mixture after mixing evenly; dissolve sodium bicarbonate in part of the water to obtain a sodium bicarbonate solution, and then add bentonite to the sodium bicarbonate solution, and obtain the second mixture after mixing evenly; S2; mix the first mixture and the second mixture, add the remaining raw materials except the cross-linking agent thereto after mixing evenly, add the cross-linking agent after mixing evenly again, and obtain the landfill slurry material after mixing evenly again.

6. The preparation method according to claim 5, characterized in that, In S1, the weight of the part of the water is 5%-15% of the weight of the water.

7. According to the preparation method described in claim 5 or 6, characterized in that, In S1, the mixing time of the fly ash and the modified lignin solution is 3-8 min; and / or In S2, the mixing time of the first mixture and the second mixture is 10-25 min; and / or In S2, the mixing time after adding the remaining raw materials except the cross-linking agent is 5-10 min.

8. The preparation method according to claim 5 or 6, characterized in that, The mixing is carried out evenly by stirring, and the rotation speed of the stirring is 30-60 r / min.

9. An application of the landfill slurry material according to any one of claims 1 to 4 in filling a coal gangue layer.

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