Coal gasification ash-based roadway bottom plate filling material and construction method

Abstract

The invention discloses a coal gasification ash-based roadway bottom plate filling material and a construction method, and belongs to the technical field of coal-based solid waste resource utilization. According to the bottom plate filling material, coal gangue serves as coarse aggregate, natural river sand and coal gasification ash coarse slag serve as fine aggregate, the coal gasification ash fine slag is activated to serve as a cementing material, and the optimal proportion of the filling material required by bottom plate filling is determined through a design test. According to the method, firstly, the position where the roadway bottom plate is prone to instability is determined through numerical simulation, bottom plate filling construction is conducted, roadway stability can be maintained in a more targeted and emphasized mode, the setting speed of the bottom plate filling material can be increased by adding the accelerator into the filling material, the filling efficiency is improved, and the filling efficiency is improved. Meanwhile, coal gangue and coal gasification ash are selected as filling raw materials, efficient disposal and utilization of mine solid waste materials are achieved, and the material has the advantages of being low in cost, high in strength, short in setting time and the like and meets the requirement of serving as a bottom plate filling material.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization of coal-based solid waste, and more particularly relates to a coal gasification ash slag-based roadway floor filling material and a construction method thereof. Background Art

[0002] As an important basic energy source, coal will continue to play a crucial role for a considerable period of time. However, coal mining and processing generate a large amount of coal-based solid waste, with gangue and coal gasification ash being the most important. The total amount of coal-based solid waste generated is enormous, and its accumulation not only occupies a large amount of valuable land resources, but also, due to its loose structure and complex composition, can cause landslides, mudslides, soil and air pollution, and other problems, seriously damaging the ecological environment. This has become a key factor restricting the sustainable development of the coal industry. Therefore, the research and application of coal-based solid waste disposal technologies is imminent.

[0003] During coal mining, tunnels are subject to a variety of complex stresses. In particular, as mining depth increases, ground stress continues to increase, and deformation phenomena such as floor heave will occur in the tunnel floor. The stability of the tunnel floor is directly related to the stability of the entire surrounding rock. The destruction of the floor will trigger a chain reaction, leading to increased deformation and damage to the side and roof plates. If not effectively controlled, floor deformation will lead to a reduction in tunnel space, affecting the normal operation of equipment and the safe passage of personnel. As one of the key technologies to ensure safe and efficient mining of coal mines, coal mine tunnel floor filling technology has made significant progress in theoretical research and engineering practice in recent years. Through floor filling construction technology, a solid support body can be formed at the bottom of the tunnel to resist the effects of disturbances such as ground stress and mining stress, effectively suppressing the deformation and damage of the floor.

[0004] In summary, preparing a coal gasification ash slag-based tunnel floor filling material and applying it in the coal mine tunnel floor filling construction can maintain the stability of the tunnel in a targeted and focused manner, while realizing the disposal of a large amount of coal-based solid waste materials, improving the tunnel floor filling efficiency, making up for the problems of expensive and scarce filling raw materials, and reducing the damage of coal mining to the ecological environment, which is of great significance. Summary of the Invention

[0005] The purpose of the present invention is to provide a coal gasification ash slag-based tunnel floor filling material and construction method, and apply it to the coal mine tunnel floor filling construction, which can not only maintain the stability of the tunnel in a targeted and focused manner, but also dispose of a large amount of coal-based solid waste materials, improve the tunnel floor filling efficiency, make up for the problems of expensive and scarce filling raw materials, reduce the damage of coal mining to the ecological environment, and have good application prospects for underground filling.

[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 coal gasification ash slag-based roadway floor filling material, the raw materials of which include coal gangue, river sand, coal gasification ash coarse slag, coal gasification ash fine slag, accelerating agent, activator and water;

[0008] The particle size of the coarse coal gasification ash slag is 0.15 to 2 mm, excluding 0.15 mm; the particle size of the fine coal gasification ash slag is ≤ 0.15 mm; 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%;

[0009] The solid mass concentration of the coal gasification ash-based tunnel floor filling material is 60-85%, the water-binder ratio is 0.4-0.6, the coal gangue accounts for 30-70% of the total mass of the coal gangue, river sand and coal gasification ash coarse slag, and the coal gasification ash coarse slag accounts for 0-100% of the total mass of the river sand and coal gasification ash coarse slag.

[0010] Preferably, the gangue includes gangue with particle sizes of 2-5mm, 5-9.5mm and 9.5-15mm respectively in a mass ratio of 2:3:5, and 5mm is not included in 5-9.5mm, and 9.5mm is not included in 9.5-15mm; the mass content of needle-like particles in the gangue is ≤15%.

[0011] Preferably, the river sand comprises river sand having fineness moduli of 2.3 to 3 and 1.6 to 2.2 respectively at a mass ratio of 1:1. The river sand can be used as fine aggregate to fill the gaps in the coarse aggregate.

[0012] Preferably, the coal gasification ash fine slag further includes the following pretreatment step before use: mechanically activating the coal gasification ash fine slag with a particle size of ≤0.15 mm.

[0013] Preferably, the mechanical activation time is 60 to 200 minutes, and the rotation speed is 100 to 300 r / min.

[0014] Preferably, the activator includes calcium sulfate; the amount of the activator is 1.5% of the mass of the coal gasification ash fine slag; the accelerating setting agent is composed of quicklime, sodium carbonate and alumina clinker in a mass ratio of 0.5:1:1; the amount of the accelerating setting agent is 3% of the mass of the coal gasification ash fine slag.

[0015] The second technical solution of the present invention is to provide a method for preparing the above-mentioned coal gasification ash slag-based roadway floor filling material, comprising the following steps:

[0016] The coal gasification ash-based roadway floor filling material is obtained by mixing coal gangue, river sand, coarse coal gasification ash slag, gelling material, quick-setting agent, activator and water.

[0017] The third technical solution of the present invention is to provide the application of the above-mentioned coal gasification ash slag-based tunnel floor filling material in tunnel floor filling.

[0018] A fourth technical solution of the present invention provides a method for filling a roadway floor with a coal gasification ash-based roadway floor filling material, comprising the following steps:

[0019] S1. Comprehensively consider the influence of roadway mining factors and determine the roadway area where the roadway floor needs to be filled;

[0020] S2. Filling the roadway area where the floor filling is required using the coal gasification ash-based roadway floor filling material;

[0021] S3. After filling is completed and initial setting is completed, the surface is leveled and smoothed.

[0022] Furthermore, step S1 specifically includes: collecting data such as corresponding mine geological conditions, mining technology, drilling histograms, etc., using FLAC 3D to establish a numerical model of the filling working face based on actual conditions, analyzing the stress distribution law of the tunnel floor during the mining process through numerical simulation, and determining the tunnel area that requires floor filling.

[0023] Furthermore, the filling in step S2 is performed by layered pouring.

[0024] Furthermore, the ratio of each raw material in the coal gasification ash slag-based roadway floor filling material is adjusted, specifically including:

[0025] Considering different solid mass concentrations, the mass ratio of coarse aggregate (coal gangue) to fine aggregate (river sand and coal gasification ash coarse slag), water-binder ratio, and the mass fraction of coal gasification ash coarse slag replacing river sand, a single factor rotation test was designed to prepare the tunnel floor filling material. The material was loaded into a 70.7mm×70.7mm×70.7mm square mold and placed on a vibration table for 0.5min. After curing for 28 days under curing conditions, standard specimens of tunnel floor filling were obtained. The 7-day compressive strength and 28-day compressive strength of the specimens were tested to determine the optimal ratio. The fatigue strength and bonding strength under this ratio were measured to verify the effect to ensure that it meets the strength requirements of the filling material in different areas of the tunnel floor.

[0026] Preferably, the filling material strength requirements include fatigue strength requirements for frequent rolling of mine cars and periodic vibration of coal mining equipment, and bonding strength requirements for the bonding ability between the filling material and the original rock layer of the tunnel floor and adjacent filling materials.

[0027] Furthermore, before filling the roadway area requiring bottom plate filling with the coal gasification ash-based roadway bottom plate filling material, the method further includes performing bottom plate treatment on the roadway area requiring bottom plate filling;

[0028] The floor treatment includes: cleaning the floating coal, gangue and other debris on the roadway floor, and treating the floor by shoveling, compacting and leveling;

[0029] Furthermore, after the plastering in step S3, for the tunnel floor with special requirements, calendering or roughening treatment is also included.

[0030] The present invention discloses the following technical effects:

[0031] The present invention provides a coal gasification ash slag-based tunnel floor filling material and construction method. First, based on the actual situation of the mine working face, a numerical simulation is established, and the floor area that needs to be filled is analyzed in combination with the tunnel floor design requirements, so that the tunnel floor filling and construction are carried out in a targeted and focused manner. Compared with the existing tunnel floor construction method, the present invention can accurately confirm the weak positions of the tunnel floor, selectively construct the floor at different positions, improve the tunnel floor construction efficiency, and ensure the stability of the tunnel floor while processing mine solid waste to the greatest extent.

[0032] The coal gangue is used as coarse aggregate, river sand and coal gasification ash coarse slag (particle size of 0.15 to 2 mm, excluding 0.15 mm) as fine aggregate, and the coal gasification ash slag after mechanical chemical activation is used as a cementing material to prepare the coal gasification ash slag-based tunnel floor filling material. The coal gangue, river sand and coal gasification ash coarse slag (particle size of 0.15 to 2 mm, excluding 0.15 mm) as aggregate bear the external load and disperse the stress. The coal gasification ash slag-based material as a cementing material can also be water-soluble. The chemical reaction generates a cementing material that fills the voids in the aggregate and forms a cementing network to jointly bear the external load. Compared with traditional filling materials mainly composed of fly ash, gravel and cement, this material also meets the strength requirements of tunnel floor filling materials, which not only maintains the stability of the tunnel floor, but also solves the problems of coal-based solid waste treatment, high cost of filling materials and shortage of raw material sources, and realizes the large-scale green disposal and environmentally friendly utilization of coal-based solid waste such as coal gasification ash and coal gangue, reducing the damage of coal mining to the ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart for constructing a coal gasification ash-based roadway floor filling body according to the present invention;

[0034] Figure 2 Schematic diagram of numerical simulation of stress distribution in tunnel floor of the present invention. DETAILED DESCRIPTION

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] 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.

[0041] Figure 1 This is a flow chart for constructing the coal gasification ash-based roadway floor filling body of the present invention.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] Example 1

[0046] Step 1: Collect relevant mine geological conditions, mining technology, drilling histogram and other data. Based on the actual conditions, use FLAC 3D to establish a numerical model of the filling working face. Through numerical simulation, analyze the stress distribution law of the tunnel floor during the mining process, such as Figure 2 As shown, combined with the design requirements of the tunnel floor, determine the tunnel area that needs to be filled with floor;

[0047] Step 2: Collect or purchase coal gangue, coal gasification ash, natural river sand and other base filling materials, crush and activate them respectively, and keep them for future use after processing;

[0048] Specifically:

[0049] The required gangue is crushed by a crusher, and a screening machine is used to screen out the gangue with particle sizes of 2-5mm, 5-9.5mm and 9.5-15mm (5mm is not included in 5-9.5mm, and 9.5mm is not included in 9.5-15mm), with a mass ratio of 2:3:5. According to the quality and inspection method standards for sand and stone used in ordinary concrete, the mass content of needle-shaped particles is required to be ≤15%;

[0050] Natural river sand was selected as fine aggregate with fineness modulus of 2.3-3 and 1.6-2.2, respectively, and a mass ratio of 1:1, which can fill the voids in the coarse aggregate;

[0051] Select the particle size of 0.15 to 2 mm, excluding the 0.15 mm coarse coal gasification ash slag as fine aggregate;

[0052] Mechanochemically activated coal gasification ash fine slag is selected as a cementitious material. The preparation steps of the cementitious material are as follows: first, the coal gasification ash fine slag with a particle size of ≤0.15 mm is mechanically activated by a ball mill, the ball milling time is 150 minutes, the rotation speed is 250 r / min, the ball-to-material ratio is 1:1, and the ball size and proportion are 40:50:60 mm = 3:4:3 respectively. Then, the coal gasification fine slag obtained after mechanical activation is mixed with calcium sulfate for chemical activation, wherein the calcium sulfate accounts for 1.5% of the mass of the coal gasification ash fine slag to form a cementitious material, which can play a cementing role.

[0053] Step 3: Considering different solid mass concentrations, coarse aggregate proportions, water-cement ratios, and river sand replacement rates, single-factor rotation tests were designed to prepare tunnel floor filling materials. Accelerators (composed of quicklime, sodium carbonate, and alumina clinker in a mass ratio of 0.5:1:1, and alumina clinker was purchased from Henan Hongyan Refractory Materials Co., Ltd.) were added. The amount of accelerator was 3% of the mass of the coal gasification ash fine slag. The slag was then placed in a square mold of 70.7 mm × 70.7 mm × 70.7 mm and placed on a vibration table for 0.5 min. It was then cured for 28 days under curing conditions to obtain standard specimens of tunnel floor filling bodies. The compressive strength of the filling body was tested. The test results are shown in Table 1.

[0054] Table 1 Material ratio design and test results

[0055]

[0056] In Table 1, the proportion of coarse aggregate indicates the proportion of gangue coarse aggregate in the total mass of aggregate, and the river sand replacement rate indicates the total mass of fine aggregate in coal gasification ash coarse slag.

[0057] From the analysis in Table 1, it can be seen that when the solid mass concentration of the filling material is 75%, the proportion of coarse aggregate is 50%, the water-cement ratio is 0.50, and the river sand replacement rate is 0%, the compressive strength is the highest and meets the C35 concrete strength standard. According to the C35 grade design value in the concrete structure design standard, the service performance test found that its fatigue strength is 16.13MPa>13.36MPa and the bond strength is 3.3MPa>2MPa, which all meet the requirements and can be used for tunnel floor filling on site. Figure 2 As shown, the bottom plate is constructed and filled at the framed position. When filling other positions with lower stress, other river sand replacement ratios with higher ratios can be used to repeat the above service performance effect test and verification, so as to ensure the stability of the tunnel bottom plate while processing the mine solid waste to the greatest extent.

[0058] Step 4: Based on the optimal ratio of the designed filling materials and the determined tunnel floor filling position, carry out the tunnel floor filling work, clean up the floating coal, gangue and other debris on the tunnel floor at the corresponding position, and level the floor by shoveling and compacting; prepare the tunnel floor filling slurry, fill the slurry by layered pouring, vibrate the filling slurry with a vibrator to make it dense, and then level the surface; wait until the surface of the filling slurry absorbs water, use a trowel to smooth the surface, and for tunnel floors with special requirements, it can also be calendered or roughened.

[0059] The tunnel floor filling material provided by the present invention improves the raw material composition of traditional filling materials. While maintaining the stability of the tunnel floor, it solves the problems of coal-based solid waste treatment, high filling material costs, and shortage of raw material sources. It realizes large-scale green disposal and environmentally friendly utilization of coal-based solid waste such as coal gasification ash and coal gangue, and reduces the damage of coal mining to the ecological environment.

[0060] 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.

[0061] 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 coal gasification ash-based roadway floor filling material, characterized in that: The raw materials include coal gangue, river sand, coarse coal gasification ash slag, fine coal gasification ash slag, accelerating agent, activator and water; The particle size of the coarse coal gasification ash slag is 0.15 to 2 mm, excluding 0.15 mm; the particle size of the fine coal gasification ash slag is ≤ 0.15 mm; The solid mass concentration of the coal gasification ash-based tunnel floor filling material is 60-85%, the water-binder ratio is 0.4-0.6, the coal gangue accounts for 30-70% of the total mass of the coal gangue, river sand and coal gasification ash coarse slag, and the coal gasification ash coarse slag accounts for 0-100% of the total mass of the river sand and coal gasification ash coarse slag.

2. The coal gasification ash-based roadway floor filling material according to claim 1, characterized in that: The gangue includes gangue with particle sizes of 2-5mm, 5-9.5mm and 9.5-15mm respectively in a mass ratio of 2:3:5, and 5mm is not included in 5-9.5mm, and 9.5mm is not included in 9.5-15mm; the mass content of needle-like particles in the gangue is ≤15%.

3. The coal gasification ash-based roadway floor filling material according to claim 1, characterized in that: The river sand includes river sand with a mass ratio of 1:1 and fineness moduli of 2.3 to 3 and 1.6 to 2.2 respectively.

4. The coal gasification ash-based roadway floor filling material according to claim 1, characterized in that: The coal gasification ash fine slag further comprises the following pretreatment step before use: mechanically activating the coal gasification ash fine slag with a particle size of ≤0.15 mm.

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 coal gasification ash-based roadway floor filling material according to claim 1, characterized in that: The activator includes calcium sulfate; the amount of the activator is 1.5% of the mass of the coal gasification ash fine slag; the accelerating setting agent is composed of quicklime, sodium carbonate and alumina clinker with a mass ratio of 0.5:1:1; the amount of the accelerating setting agent is 3% of the mass of the coal gasification ash fine slag.

7. The method for preparing the coal gasification ash-based roadway floor filling material according to any one of claims 1 to 6, characterized in that: The steps include: The coal gasification ash-based roadway floor filling material is obtained by mixing coal gangue, river sand, coarse coal gasification ash slag, fine coal gasification ash slag, an accelerating agent, an activator and water.

8. Use of the coal gasification ash-based roadway floor filling material according to any one of claims 1 to 6 in roadway floor filling.

9. A method for filling a tunnel floor with coal gasification ash-based tunnel floor filling material, characterized in that: The steps include: S1. Comprehensively consider the influence of roadway mining factors and determine the roadway area where the roadway floor needs to be filled; S2. Filling the roadway area where the floor filling is required using the coal gasification ash-based roadway floor filling material; S3. After filling, the surface is leveled and smoothed.

Images