Coal gasification ash-based grouting filling material in mining space and preparation method thereof

Abstract

The invention discloses a coal gasification ash-based grouting filling material in a mining space and a preparation method thereof, and relates to the technical field of coal mine filling mining and environmental protection. The coal gasification ash-based grouting filling material for the mining space comprises the following raw materials: gangue, coal gasification ash coarse slag, coal gasification ash fine slag, a cementing material and water, wherein the mass ratio of the gangue to the coal gasification ash coarse slag to the coal gasification ash fine slag to the cementing material is (0.2-0.4): (1.5-2.0): (0.8-1.2): (0.3-0.4); the mass concentration of solid components in the coal gasification ash-based grouting filling material for the mining space is 60-65%. The preparation method comprises the following steps: weighing the raw materials according to the raw material composition; taking out 40-60wt% of the coal gasification ash coarse slag, and carrying out ball milling to obtain ball-milled coarse slag; and mixing the ball-milled coarse slag with the residual coal gasification ash coarse slag and other raw materials to obtain the coal gasification ash-based grouting filling material in the mining space. The fluidity, bleeding rate and uniaxial compressive strength of the grouting and filling material are adjustable and controllable, and the working requirements of grouting and filling in a mining space can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mine filling mining and environmental protection, in particular to a coal gasification ash-based grouting filling material for a mining space and a preparation method thereof. Background Art

[0002] During coal mining and other underground engineering activities, multi-layer goafs are often formed. If these goafs are not filled, they may lead to safety problems such as ground collapse and infrastructure settlement. At the same time, coal gasification ash, as a major waste in the coal gasification process, has a large stockpile and is difficult to handle. It not only occupies a large amount of land resources, but also may pollute the environment. Therefore, the development of a grouting material that can use coal gasification ash to fill goafs can not only solve the safety problems of goafs, but also realize the resource utilization of coal gasification ash, which has important practical significance. How to obtain high-performance coal gasification ash-based grouting filling materials is the focus of research for those skilled in the art. Summary of the Invention

[0003] The purpose of the present invention is to provide a mining space coal gasification ash slag-based grouting filling material and a preparation method to solve the problems of large coal-based solid waste stockpiles and difficult treatment, reduce the cost of grouting filling treatment, and improve the performance of grouting filling materials (fluidity, water bleeding rate, uniaxial compressive strength, etc.).

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is a coal gasification ash-based grouting filling material for a mining space, wherein the raw materials include gangue, coarse coal gasification ash slag, fine coal gasification ash slag, and a cementitious material in a mass ratio of 0.2-0.4:1.5-2.0:0.8-1.2:0.3-0.4, and water;

[0006] The mass concentration of the solid components in the coal gasification ash-based grouting filling material for the mining space is 60-65%.

[0007] The mass of coarse and fine coal gasification ash is calculated based on solids content. The amount of water used must be adjusted based on the moisture content of the coarse and fine coal gasification ash, as well as the mass concentration of the solid components in the desired grouting and filling material. Coarse and fine coal gasification ash contain a significant amount of water, so when determining the amount of water based on the mass concentration of the solid components in the desired grouting and filling material, the water content in the coarse and fine coal gasification ash must be subtracted.

[0008] Gangue serves as the coarse aggregate to form the material skeleton, while coarse and fine coal gasification ash slag achieve dense filling through a multi-level particle size distribution. The cementitious material generates a cementitious substance through an alkali-activated reaction to bond and solidify the aggregate. The water content precisely balances the requirements for fluidity and consolidation strength. These components work together to form a filling body with both structural stability and cementitious properties, giving the grouting filling material appropriate fluidity, water bleeding rate, and uniaxial compressive strength.

[0009] In addition, the coal gasification ash-based grouting filling material of the present invention is environmentally friendly, has a high solid waste content, and has excellent mechanical properties. It can effectively solve the problems of large coal-based solid waste stockpiles and difficult treatment, while reducing the cost of grouting filling treatment.

[0010] Furthermore, the particle size of the gangue is 2 to 5 mm, excluding 2 mm.

[0011] The particle size range of gangue is 2 to 5 mm, which can improve the pore connectivity of the filling body.

[0012] Furthermore, the particle size of the coal gasification ash coarse slag is 0.15 to 2 mm, excluding 0.15 mm.

[0013] Coal gasification ash coarse slag is formed by inorganic mineral molten slag flowing into the bottom of the gasifier and cooling to form particles. It has various shapes, a glassy surface, a low carbon content, and is mainly composed of crystalline minerals.

[0014] Furthermore, the particle size of the coal gasification ash fine slag is ≤0.15 mm.

[0015] Coal gasification ash fine slag is carried out by synthesis gas and is separated into fine particles during the subsequent gas purification process. It is mostly powdery, has a high carbon content, and is mainly amorphous glass.

[0016] That is, coarse coal gasification ash slag and fine coal gasification ash slag are two types of solid wastes with different morphologies, sizes and components produced in different parts of the gasifier during the coal gasification process.

[0017] Furthermore, the raw materials of the cementitious material include, by mass, 30-40 parts of slag, 60-70 parts of water glass, 6-8 parts of NaOH and 20-24 parts of water.

[0018] The water glass and NaOH in the cementitious material can jointly regulate the reaction rate and product structure.

[0019] Furthermore, the modulus of the water glass is 3.2-3.4.

[0020] The second technical solution of the present invention is a method for preparing the above-mentioned coal gasification ash slag-based grouting filling material for mining space, comprising the following steps:

[0021] Weigh each raw material according to its composition;

[0022] Taking out 40-60 wt% of the coarse coal gasification ash slag and ball milling it to obtain ball-milled coarse slag;

[0023] The ball-milled coarse slag is mixed with the remaining coal gasification ash coarse slag and other raw materials to obtain the coal gasification ash-based grouting filling material for the mining space.

[0024] Furthermore, the ball milling is specifically ball milling to D 90 ≤50μm, D 50 ≤20μm and D 10 ≤5μm.

[0025] Taking out part of the coarse slag of coal gasification ash and milling it, and then mixing it with the remaining coarse slag of coal gasification ash and fine slag of coal gasification ash, can further optimize the gradation of coarse slag and fine slag of coal gasification ash. The unmilled coarse slag (particle size of 0.15-2mm, excluding 0.15mm), ball-milled coarse slag (D 90 ≤50μm, D 50 ≤20μm and D 10 ≤5μm) and fine slag (particle size ≤0.15mm) can form a better multi-level particle size distribution, thereby achieving a tighter filling effect.

[0026] Moreover, the coarse coal gasification ash residue activated by ball milling can react with the slag in the cementitious material under the action of the alkaline solution composed of water glass and NaOH to generate a cementitious substance to bond and solidify the aggregate, further improving the strength of the filling body.

[0027] Optionally, the ball mill has a rotation speed of 400 r / min.

[0028] The third technical solution of the present invention: an application of the above-mentioned coal gasification ash-based grouting filling material in the filling and reinforcement of the mining space.

[0029] The present invention discloses the following technical effects:

[0030] 1. The present invention provides a coal gasification ash slag-based grouting filling material for mining space, which can effectively solve the problems of large stockpiles of coal-based solid waste and difficulty in treatment, while reducing the cost of grouting filling treatment.

[0031] 2. The fluidity, water seepage rate and uniaxial compressive strength of the coal gasification ash-based grouting filling material for the mining space of the present invention are adjustable and controllable, and can meet the working requirements of grouting filling in the mining space.

[0032] 3. The coal gasification ash-based grouting filling material for mining space of the present invention also has the advantages of saving resources, simple process, high degree of industrialization, etc., and can produce significant economic, social and ecological benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in 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 paying any creative work.

[0034] Figure 1 The flowability variation patterns of the grouting filling materials prepared with different raw material ratios in Examples 1-15 are shown.

[0035] Figure 2 The variation pattern of water bleeding rate of grouting filling materials with different raw material ratios prepared in Examples 1-15.

[0036] Figure 3 The variation pattern of uniaxial compressive strength of grouting filling materials with different raw material ratios prepared in Examples 1-15. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0043] In the following examples, comparative examples and test examples of the present invention, if room temperature is mentioned, it specifically refers to 20-30°C.

[0044] The “parts” referred to in the following embodiments, comparative examples and test examples of the present invention specifically refer to “parts by mass”.

[0045] Unless otherwise specified, the raw materials used in the following embodiments, comparative examples, and test examples of the present invention are all common commercially available products, wherein the particle size of the coarse coal gasification ash slag is 0.15 to 2 mm (excluding 0.15 mm), and the moisture content is 58%; the particle size of the fine coal gasification ash slag is ≤0.15 mm, and the moisture content is 63%; the slag is S95 grade slag; and the gangue is coal gangue.

[0046] The amount of water added in the following examples and comparative examples is adjusted according to the moisture content of the coarse coal gasification ash slag and the fine coal gasification ash slag and the mass concentration of the slurry to be obtained.

[0047] Example 1

[0048] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0049] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0050] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0051] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.3, wherein the mass of the coarse coal gasification ash slag and the fine coal gasification ash slag is calculated based on solid content, the same below.

[0052] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0053] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is calculated to make the slurry mass concentration 61%, and the moisture contained in the coal gasification ash coarse slag and coal gasification ash fine slag needs to be excluded when calculating the amount of water), and stir until it is uniform to obtain the mining space coal gasification ash based grouting filling material.

[0054] Example 2

[0055] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0056] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0057] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0058] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.3.

[0059] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0060] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 62%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0061] Example 3

[0062] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0063] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0064] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0065] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.3.

[0066] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0067] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 63%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0068] Example 4

[0069] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0070] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0071] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0072] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.3.

[0073] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0074] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 64%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0075] Example 5

[0076] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0077] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0078] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0079] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.3.

[0080] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0081] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 65%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0082] Example 6

[0083] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0084] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0085] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0086] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.35.

[0087] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0088] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 61%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0089] Example 7

[0090] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0091] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0092] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0093] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.35.

[0094] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0095] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 62%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0096] Example 8

[0097] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0098] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0099] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0100] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.35.

[0101] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0102] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 63%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0103] Example 9

[0104] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0105] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0106] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0107] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.35.

[0108] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0109] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 64%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0110] Example 10

[0111] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0112] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0113] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0114] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.35.

[0115] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0116] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 65%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0117] Example 11

[0118] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0119] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0120] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0121] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.4.

[0122] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0123] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 61%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0124] Example 12

[0125] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0126] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0127] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0128] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.4.

[0129] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0130] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 62%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0131] Example 13

[0132] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0133] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0134] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0135] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.4.

[0136] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0137] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 63%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0138] Example 14

[0139] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0140] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0141] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0142] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.4.

[0143] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0144] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 64%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0145] Example 15

[0146] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0147] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0148] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0149] S3. Weigh the gangue particles, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious materials in a mass ratio of 0.4:2.0:1.0:0.4.

[0150] S4. Take out 50 wt% of the coarse coal gasification ash and dry it to a moisture content of ≤1%, then ball mill (speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0151] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles, coal gasification ash fine slag and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 65%), and stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0152] Comparative Example 1

[0153] Same as Example 1, except that P·O 42.5 cement of equal quality is used instead of the cementitious material.

[0154] Comparative Example 2

[0155] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0156] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0157] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0158] S3. Weigh the gangue particles, coal gasification ash coarse slag and cementitious materials in a mass ratio of 0.4:3.0:0.3.

[0159] S4. Take out one-third of the coarse slag from the coal gasification ash and dry it to a moisture content of ≤1%. Then ball mill it (at a speed of 400 r / min) to D 90 =50μm, D 50 =20μm, D 10 =5μm, and ball-milled coarse slag was obtained.

[0160] S5. Mix the ball mill coarse slag with the remaining coal gasification ash coarse slag and other raw materials (gangue particles and cementitious materials), add water (the amount of water is such that the slurry mass concentration is 61%, excluding the water contained in the coal gasification ash coarse slag), and stir until it is uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0161] Comparative Example 3

[0162] A coal gasification ash slag-based grouting filling material for mining space, the preparation steps of which are as follows:

[0163] S1. Use a crusher to crush the gangue and screen out gangue particles with a particle size of 2 to 5 mm (excluding 2 mm).

[0164] S2. 40 parts of slag, 70 parts of 3.3-mol water glass, 8 parts of NaOH and 24 parts of water were mixed uniformly to obtain a cementitious material.

[0165] S3. Weigh the gangue particles, coal gasification ash fine slag and cementitious materials in a mass ratio of 0.4:3.0:0.3.

[0166] S4. Mix all the raw materials and add water (the amount of water is such that the mass concentration of the slurry is 61%, excluding the water contained in the coal gasification ash fine residue), stir until uniform to obtain the mining space coal gasification ash-based grouting filling material.

[0167] Test Example 1

[0168] The fluidity, water bleeding rate and uniaxial compressive strength of the grouting filling materials prepared in each embodiment and comparative example were tested as follows:

[0169] Pour the prepared grouting filling material into a 60mm×70mm×100mm truncated cone mold, lift the truncated cone mold vertically, and allow the slurry to flow freely onto the glass plate until it stops. Measure the maximum expansion diameter of the slurry bottom surface and its vertical diameter. The calculated average value is the initial fluidity value of the grouting filling material.

[0170] Pour the prepared grouting material into a graduated cylinder and record its initial volume. Seal the cylinder with plastic wrap and, starting from the time the liquid level reaches a flat surface, aspirate water with a rubber-tipped dropper every 10 minutes for the first 60 minutes. After 60 minutes, aspirate water every 20 minutes until no water seeps for three consecutive times. Pour the aspirated water into a sealed container and weigh the total water seepage. Calculate the water seepage rate based on the total water seepage and the initial water content of the grouting material.

[0171] The grouting material was poured into a triple mold measuring 70.7 mm x 70.7 mm x 70.7 mm, shaken on a vibrator for 30 seconds, and demolded after 24 hours. The mold was then placed in a curing chamber at 20°C and 95% humidity for 28 days, and the uniaxial compressive strength was tested. Uniaxial compressive strength was tested using a WAW-2000D microcomputer-controlled electro-hydraulic servo rock pressure testing system at a loading rate of 0.3 mm / min.

[0172] The specific test results are shown in Table 1 and Figure 1-3 shown.

[0173] Table 1

[0174]

[0175]

[0176] The change rules of fluidity of grouting filling materials with different raw material ratios prepared in Examples 1-15 are as follows: Figure 1 shown.

[0177] The variation rules of water seepage rate of grouting filling materials with different raw material ratios prepared in Examples 1-15 are as follows: Figure 1 shown.

[0178] The variation of uniaxial compressive strength of grouting filling materials with different raw material ratios prepared in Examples 1-15 is as follows: Figure 1 shown.

[0179] From Table 1 and Figure 1-Figure 3 The experimental results show that:

[0180] The grouting filling materials prepared in Examples 1-15 of the present invention all have suitable fluidity, low water bleeding rate and high compressive strength, and as the proportion of the cementitious material increases, the fluidity of the grouting filling material decreases, the water bleeding rate decreases, and the uniaxial compressive strength increases; as the slurry concentration increases, the fluidity of the grouting filling material decreases, the water bleeding rate decreases, and the uniaxial compressive strength increases.

[0181] Compared with Example 1, the fluidity, water bleeding rate and uniaxial compressive strength of the sample in Comparative Example 1 are similar, indicating that the solid waste cementitious material of the present invention can achieve performance comparable to that of cement, and the present invention is more cost-effective.

[0182] Compared with Example 1, in Comparative Example 2, after all the fine slag is replaced by coarse slag, the lubricating effect is weakened and the fluidity is reduced due to the large particle size and small specific surface area of ​​the coarse slag; because the pores become larger, water is easily precipitated and the water seepage rate increases; because the particle size of the coarse slag is large, it is difficult to form a tight interlocking structure when stacked, there are fewer contact points between the particles, and the uniaxial compressive strength decreases.

[0183] Compared with Example 1, in Comparative Example 3, after all the coarse slag is replaced by fine slag, the fine slag has a small particle size and a large specific surface area, so the lubrication effect is enhanced and the fluidity is increased; because the fine slag fills dense pores, the water bleeding rate is reduced; because the fine slag has a small particle size, the mutual embedding effect between the particles is weak, and a stable skeleton support system cannot be constructed during the hardening process, and the uniaxial compressive strength is reduced.

[0184] Under the synergistic effect of various raw materials and preparation methods, the coal gasification ash-based grouting filling material for mining space of the present invention has high performance, which is mainly reflected in appropriate fluidity, low water bleeding rate and high uniaxial compressive strength, and the three are adjustable and controllable.

[0185] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A coal gasification ash-based grouting filling material for mining space, characterized in that: The raw materials include gangue, coarse coal gasification ash slag, fine coal gasification ash slag and cementitious material in a mass ratio of 0.2-0.4:1.5-2.0:0.8-1.2:0.3-0.4, and water; The mass concentration of the solid components in the coal gasification ash-based grouting filling material for the mining space is 60-65%.

2. The coal gasification ash-based grouting filling material for mining space according to claim 1, characterized in that: The particle size of the gangue is 2 to 5 mm, excluding 2 mm.

3. The coal gasification ash-based grouting filling material for mining space according to claim 1, characterized in that: The particle size of the coal gasification ash coarse slag is 0.15 to 2 mm, excluding 0.15 mm.

4. The coal gasification ash-based grouting filling material for mining space according to claim 1, characterized in that: The particle size of the coal gasification ash fine slag is ≤0.15mm.

5. The coal gasification ash-based grouting filling material for mining space according to claim 1, characterized in that: The raw materials of the cementitious material include, by mass, 30-40 parts of slag, 60-70 parts of water glass, 6-8 parts of NaOH and 20-24 parts of water.

6. A method for preparing the coal gasification ash-based grouting filling material for mining space according to any one of claims 1 to 5, characterized in that: The following steps are involved: Weigh each raw material according to its composition; Taking out 40-60 wt% of the coarse coal gasification ash slag and ball milling it to obtain ball-milled coarse slag; The ball-milled coarse slag is mixed with the remaining coal gasification ash coarse slag and other raw materials to obtain the coal gasification ash-based grouting filling material for the mining space.

7. The preparation method according to claim 6, wherein The ball milling is specifically ball milling to D 90 ≤50μm, D 50 ≤20μm and D 10 ≤5μm.

8. Use of the coal gasification ash-based grouting filling material for mining spaces as claimed in any one of claims 1 to 5 in filling and reinforcing mining spaces.

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