Method for preparing roadside support filling body from coal gasification ash solid waste

Abstract

The invention discloses a method for preparing a roadside support filling body from coal gasification ash solid waste, and belongs to the technical field of coal-based solid waste resource utilization. The roadside filling body is formed by mixing coal gangue, coal gasification ash coarse slag, coal gasification ash fine slag and alkaline water; coal gangue serves as coarse aggregate, coal gasification ash coarse slag serves as fine aggregate, and the coal gasification ash fine slag is activated to replace cement to serve as a cementing material. The coal gangue, the coal gasification ash coarse slag, the coal gasification ash fine slag and the alkaline water are mixed to prepare the roadside filling body cementing material, other cementing materials and aggregates do not need to be added, after curing is conducted for 28 days, solidification of filling slurry is achieved through the activation characteristic of the coal gasification ash, and the performance of the filling slurry meets the performance requirement of the roadside filling material. The method is low in material cost, large in solid waste disposal amount and good in environmental benefit, a new way is provided for disposal of solid waste such as coal gasification ash, and sustainable development of the coal industry can be promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of coal-based solid waste, and more specifically relates to a method for preparing a roadside support filling body from coal gasification ash solid waste. Background Art

[0002] In recent years, strengthening solid waste disposal, adjusting energy mix, and reducing carbon emissions have become key priorities for the energy industry. Gasification ash, a solid waste produced during the coal gasification process, not only occupies significant land resources but also causes significant pollution to water, soil, and the atmosphere. This has prompted coal-related companies and research institutions to conduct extensive research on the disposal and utilization of gasification ash. This has led to the development of diversified application technologies, primarily in backfill mining, construction material production, and soil improvement, promoting the resourceful utilization of gasification ash.

[0003] During coal mining, traditional methods result in the creation of numerous coal pillars, resulting in a waste of coal resources. Complex roadway layouts also increase the amount of roadway excavation required. Therefore, as a continuous mining technique that eliminates coal pillars between adjacent working faces, gob-side entry retaining uses roadway-side filling to support the roof and isolate the goaf. This not only reduces roadway excavation but also eliminates the need for coal pillars. Traditional roadway-side filling materials, primarily made from gangue, fly ash, and cement, are expensive and have limited availability, making them difficult to meet the requirements for gob-side entry retaining.

[0004] In summary, there is an urgent need to develop a tunnel side filling material that can dispose of and utilize coal gasification ash, solve the problems of high cost of filling raw materials, and make up for the limited source of raw materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing roadside support filling bodies from coal gasification ash solid waste, so as to solve the problems existing in the above-mentioned prior art, realize green mining, and make up for the shortage of filling raw materials. It can also make the coal gasification ash be reasonably disposed of and utilized, avoiding large-scale accumulation and occupation of land and pollution of water bodies, soil and atmosphere.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a method for preparing a roadside support filling body from coal gasification ash solid waste, comprising the following steps:

[0008] Mixing coarse coal gasification ash slag, fine coal gasification ash slag, coal gangue and alkaline water to obtain a filling slurry; then pouring and curing to obtain the roadside support filling body;

[0009] The particle size of the coarse coal gasification ash slag is 0.15-2 mm, excluding 0.15 mm; the particle size of the fine coal gasification ash slag is ≤0.15 mm; the alkaline water is composed of water glass and water; the coarse coal gasification ash slag and the fine coal gasification ash slag need to be dried before use to control the moisture content to ≤1%.

[0010] Preferably, the filling slurry has a solid mass concentration of 76-82%, an alkali equivalent of 2-8%, and a water-binder ratio of 0.46-0.52.

[0011] Preferably, the mass ratio of the coarse coal gasification ash slag, the fine coal gasification ash slag and the coal gangue is 0.267:0.407:0.326.

[0012] Preferably, the coal gasification ash fine slag further includes the following pretreatment step before use: mechanically activating the coal gasification ash fine slag.

[0013] Depending on the particle size of coal gasification ash, efficient utilization can be achieved. Coarse coal gasification ash can be used as aggregate, and fine coal gasification ash, after activation, can replace cement as a cementitious material. This invention uses coal gasification ash as a raw material for preparing roadside support backfill, which not only conforms to the concept of green backfill mining but also addresses problems such as backfill material shortages, reduces damage to the ecological environment, and has promising prospects for underground backfill applications.

[0014] Preferably, the mechanical activation time is 60 to 200 minutes, and the rotation speed is 100 to 300 r / min.

[0015] Preferably, the particle size of the coal gangue is 2 to 15 mm, excluding 2 mm.

[0016] The second technical solution of the present invention is to provide a tunnel side support filling body prepared by the above method.

[0017] The third technical solution of the present invention is to provide the above-mentioned roadside support filling body for use in filling the goaf-side roadway in coal mines.

[0018] The fourth technical solution of the present invention is to provide a method for supporting and filling the side of a gob-side entry in a coal mine, comprising the following steps:

[0019] The above-mentioned lane side support filling body is used to fill the goaf-side lanes in coal mines.

[0020] The present invention discloses the following technical effects:

[0021] The present invention provides a method for preparing a roadside support filling body from coal gasification ash solid waste, which adopts coal gangue as coarse aggregate; the coarse coal gasification ash slag is used as fine aggregate, and together with the coarse aggregate, it constitutes the skeleton of the roadside support filling body; the fine coal gasification ash slag is subjected to ball milling to increase its particle surface area and initially stimulate its activity, and replaces cement as a cementitious material, mainly by generating cementitious products connected around the aggregate particle skeleton to improve the strength of the filling body; water glass and water are mixed to prepare alkaline water, and by providing an alkaline environment, the stable structure with high polymerization degree in the ash is broken, and the formation of cementitious products is promoted, which is used for chemical activation of the coal gasification ash in the cementitious material; the coarse and fine aggregates, the cementitious material, and the alkaline water are mixed to prepare a cementitious filling material, and the performance of the material fully meets the performance requirements of the roadside filling material.

[0022] Compared with traditional cementitious filling materials whose raw materials are coal gangue, cement and other materials, the present invention innovatively proposes a method for preparing tunnel side support filling bodies using one of the coal-based solid wastes - coal gasification ash as fine aggregate and cementitious material, which reduces the amount of cement and other materials used, effectively solves the problems of high cost of filling raw materials and shortage of raw material sources, and realizes the rational disposal and utilization of coal gasification ash, avoiding the phenomenon of large-scale accumulation and occupation of land and pollution of water bodies, soil and atmosphere.

[0023] The tunnel side support filling body provided by the present invention has excellent mechanical properties and meets the performance requirements of tunnel side filling bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart for preparing the roadside support filling body of the present invention;

[0025] Figure 2 This is a broken line bar graph showing the flow performance variation of the roadside support filling material prepared under different variables described in Example 1;

[0026] Figure 3 This is a line graph showing the compressive strength variation of the roadside support filling specimens prepared under different variables described in Example 1;

[0027] Figure 4 The figure is a line graph showing the variation of tensile strength of the tunnel side support filling specimens prepared under different variables described in Example 1. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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 illustrative only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] 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.

[0034] Unless otherwise specified, the raw materials used in the following examples of the present invention are all commercially available products, and the sources of the commercially available products do not affect the technical effects of the present invention.

[0035] The coarse coal gasification ash slag used is formed by cooling inorganic mineral slag into particles at the bottom of the gasifier. It has a variety of shapes and a glassy surface. After drying in a dryer to control the moisture content to ≤1%, it is sieved through a vibrating screen to select particles with a size of 0.15-2mm, excluding the particulate matter above 0.15mm.

[0036] The fine coal gasification ash residue used is carried out by the synthesis gas and separated during the subsequent gas purification process. It is mostly powdery and has a high carbon content. After drying in a dryer to control the moisture content to ≤1%, it is screened through a vibrating screen and the fraction with a particle size of ≤0.15mm is selected.

[0037] Example 1

[0038] Step 1: Collect gangue from a local coal mine area. Use a jaw crusher to crush the gangue with a particle size greater than 15 mm to less than 15 mm. Place 2 mm and 15 mm round hole sieves on a vibrating screen to screen out the gangue with a size of 2 to 15 mm for use as coarse aggregate.

[0039] Step 2: Coal gasification ash coarse slag with a particle size of 0.15 to 2 mm, excluding 0.15 mm, is used as fine aggregate for standby; fine coal gasification ash with a particle size of ≤ 0.15 mm is ball milled in a planetary ball mill, the ball milling time is 100 min, the speed is 300 r / min, the ball-to-material ratio is 1:1, the ball size and proportion are 40:50:60 mm = 4:3:3 respectively, and the sieve residue of the 200-mesh square hole sieve is less than 5% to meet the requirements. If it does not meet the requirements, continue ball milling until it meets the requirements, and complete the mechanical activation of the coal gasification ash; and prepare water glass (modulus 1.6, density 2.35 g / cm 3 ) and water, which are mixed with the mechanically activated coal gasification ash fine residue for chemical activation to form a cementitious material.

[0040] Step 3: A single-factor rotation method was used to design a mix optimization test plan (parameter settings are shown in Table 1). The effects of different parameters on the mechanical and flow properties of the gasification ash roadway support filling material were studied by varying the solid mass concentration, alkali equivalent, and water-binder ratio. The mass ratio of coarse gasification ash slag, fine gasification ash slag, and coal gangue was 0.267:0.407:0.326. Control group 1 (DZ-1) used cement as the binder; control group 2 (DZ-2) did not add water glass (alkali equivalent was 0%). Other parameters for both control groups were the same as those for experimental group A-2.

[0041] Table 1 Optimal test plan for proportioning

[0042]

[0043] After each group of materials is configured according to the ratio, they are evenly stirred by a mixer to obtain the roadside cementitious filling material. The slump tester, Vicat tester and viscometer are used to test the slump, viscosity and initial setting time of each group of test roadside cementitious filling materials. The test results are shown in Table 2. The change rules of different test groups under different variables are shown in Table 2. Figure 2 shown.

[0044] Figure 2 This is a broken line bar graph showing the flow performance variation of the roadside support filling body prepared under different variables described in Example 1.

[0045] Table 2 Test data of various properties changing with variables

[0046] Group Slump / mm Viscosity / mPa·s Initial setting time / min A-1 99.2 1562 119 A-2 113.0 1246 163 A-3 98.4 789 183 A-4 97.8 658 202 B-1 95.5 688 216 B-2 99.2 789 186 B-3 108.9 1246 159 B-4 112.6 1634 113 C-1 97.4 467 204 C-2 108.9 798 146 C-3 98.3 1246 118 C-4 97.6 1678 108 DZ-1 101.2 1823 116 DZ-2 94.1 473 108

[0047] As shown in Table 2, as various factors varied, only groups A-2, B-3, B-4, C-2, and DZ-1 achieved slumps above 100 mm. Groups A-2 and B-3 exhibited viscosities between 1000 and 1500 mPa·s and initial setting times of 163 and 159 min, respectively, demonstrating excellent flow properties. Overall, these groups outperformed the two control groups. This is due to the fact that ball milling disrupts the dense structure of the ash, reducing particle size and achieving a more uniform gradation. This results in better dispersion in the slurry and reduced frictional resistance. Compared to the rapid formation of a rigid network structure by cement hydration to form CSH gel, the ash hydration reaction is more moderate, resulting in lower viscosity, higher slump, and longer initial setting time.

[0048] Step 4: The roadside cemented filling materials obtained in each group were respectively placed into a square mold of 70.7×70.7×70.7 mm, and placed on a vibration table for 0.5 min. After that, they were cured for 28 days under curing conditions to obtain standard specimens of roadside support filling. The standard specimens of roadside support filling were subjected to uniaxial compressive and tensile strength tests. The results are shown in Tables 3 and 4. The uniaxial compressive and tensile strength change curves of each specimen are shown in Tables 3 and 4. Figure 3 and Figure 4 shown.

[0049] Figure 3 This is a line graph showing the compressive strength variation of the roadside support filling specimens prepared under different variables described in Example 1; Figure 4 The figure is a line graph showing the variation of tensile strength of the tunnel side support filling specimens prepared under different variables described in Example 1.

[0050] Table 3 Compressive strength test results with variable changes

[0051]

[0052] Table 4 Test results of tensile strength as a function of variables

[0053]

[0054] From the analysis of Tables 3 and 4, it can be seen that after using coarse coal gasification ash slag as fine aggregate and fine coal gasification ash slag as cementitious material, the uniaxial compressive strength and tensile strength are significantly improved. The uniaxial compressive strength of groups A-1, A-2, A-3, B-3, B-4, C-1, C-2, C-3, C-4, and DZ-1 at 28 days all exceed 20 MPa, and the uniaxial tensile strength of groups A-1, A-2, B-3, B-4, C-1, C-2, and C-3 at 28 days all exceed 5 MPa. Compared with the control group using cement as cementitious material and without adding alkali activator, the mechanical properties are significantly improved. The reason is that mechanical activation destroys the inert structure of the glass in the ash, making the ash particle size distribution narrower and the gradation lower. Small-particle ash is filled between large-particle particles, which improves the density of the filling body and significantly reduces the generation of microcracks. Compared with the cement hydration products that are mainly flake-shaped, the ash will generate needle-shaped crystals and longer-chain silicon-oxygen tetrahedral structures after chemical activation, forming a multi-component reinforcement phase, which significantly improves the mechanical properties of the filling slurry.

[0055] Based on the flow and mechanical properties of the above test groups, it can be seen that the filling materials of groups A-2 and B-3 have the best performance and meet the performance requirements of roadside filling bodies.

[0056] The tunnel side support filling material provided by the present invention improves the raw material composition of traditional filling materials, optimizes mechanical properties, rationally disposes and utilizes coal gasification ash, and solves the problems of high filling raw material costs and shortage of raw material sources.

[0057] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0058] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing roadside support filling body from coal gasification ash solid waste, characterized in that: The steps include: Mixing coarse coal gasification ash slag, fine coal gasification ash slag, coal gangue and alkaline water to obtain a filling slurry; then pouring and curing to obtain the roadside support filling body; The particle size of the coarse coal gasification ash is 0.15 to 2 mm, excluding 0.15 mm; the particle size of the fine coal gasification ash is ≤ 0.15 mm; and the alkaline water is composed of water glass and water.

2. The method according to claim 1, characterized in that The filling slurry has a solid mass concentration of 76-82%, an alkali equivalent of 2-8%, and a water-binder ratio of 0.46-0.

52.

3. The method according to claim 1, characterized in that The mass ratio of the coarse coal gasification ash slag, the fine coal gasification ash slag and the coal gangue is 0.267:0.407:0.

326.

4. The method according to claim 1, wherein The coal gasification ash fine slag further comprises the following pretreatment step before use: mechanically activating the coal gasification ash fine slag.

5. The method according to claim 4, characterized in that The mechanical activation time is 60 to 200 minutes, and the rotation speed is 100 to 300 r / min.

6. The method according to claim 1, characterized in that The particle size of the coal gangue is 2 to 15 mm, excluding 2 mm.

7. The roadside support filling body prepared by the method according to any one of claims 1 to 6.

8. The lane side support filling body according to claim 7 is used in the filling of lanes along the goaf in coal mines.

9. A method for supporting and filling the side of a gob-side entry in a coal mine, characterized in that: The steps include: The lane side support filling body described in claim 7 is used to fill the lane along the goaf in coal mines.

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