Coal seam grouting material and application method thereof

Abstract

The application relates to the technical field of green coal mining, and particularly discloses a coal seam grouting material and an application method thereof. The coal seam grouting material comprises the following components in parts by weight: 100-120 parts of coal solid waste raw powder, 40-50 parts of solid waste-based cementitious material and 165-185 parts of water. The coal solid waste raw powder comprises coal gangue powder. The solid waste-based cementitious material is obtained by calcining a mixture at 900-1000 DEG C after grinding. The mixture comprises coal gangue and carbide slag. In the application, the solid waste-based cementitious material is used to replace part of the coal solid waste raw powder. The cohesion of the gel product is used to reduce the possibility of segregation of the coal seam grouting material in the pumping process, which helps to reduce the pipe blocking phenomenon of the grouting material, improves the pumpability of the grouting material, and helps to reduce the difficulty of grouting operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of green coal mining, and more particularly to a coal seam grouting material and an application method thereof. BACKGROUND

[0002] Coal is an important resource, and the mining and application of coal not only bring convenience to production and life, but also produce a large amount of solid waste. Taking coal gangue, the main solid waste produced in the process of coal mining, as an example, if the waste coal gangue is stored in a stacking manner, not only a large amount of land will be occupied, but also pollutants such as dust and acid wastewater will be produced, which is easy to cause damage to the ecological environment.

[0003] Regarding the reasonable disposal of coal gangue, a feasible method at present is to prepare coal gangue into slurry, and then inject the slurry into the separation space under the key layer of the coal seam roof by grouting, so as to dispose the coal gangue while reducing the subsidence of the stratum in the mining area. In the related art, there is a coal seam grouting material, which includes the following components in parts by weight: 140-170 parts of coal solid waste raw powder, 165-185 parts of water, and the coal solid waste raw powder is coal gangue powder.

[0004] In view of the related art, the inventors consider that, although the coal gangue is prepared into the coal seam grouting material in the related art, the grouting material will be separated due to the sinking of the powder particles in the pumping process, and the pipe blocking phenomenon is easy to occur, which not only affects the pumpability of the grouting material, but also increases the difficulty of grouting operation. SUMMARY

[0005] The grouting material in the related art is easy to cause the pipe blocking phenomenon due to separation in the pumping process, which affects the pumpability of the grouting material and increases the difficulty of grouting operation. In order to improve this defect, the present application provides a coal seam grouting material and an application method thereof.

[0006] In a first aspect, the present application provides a coal seam grouting material, which adopts the following technical solution:

[0007] A coal seam grouting material, which includes the following components in parts by weight: 100-120 parts of coal solid waste raw powder, 40-50 parts of solid waste-based cementitious material, and 165-185 parts of water, wherein the component of the coal solid waste raw powder includes coal gangue powder, the solid waste-based cementitious material is obtained by calcining a mixture at 900-1000℃ after grinding, and the component of the mixture includes coal gangue and carbide slag.

[0008] Compared with the related art, the coal gangue and the carbide slag are mixed, ground and calcined to obtain the solid waste-based cementitious material, and a part of the coal solid waste raw powder is replaced by the solid waste-based cementitious material. The carbide slag is a main waste produced by the calcium carbide industry, which is an important part of the coal chemical industry. Therefore, the carbide slag is easy to obtain in the place where the coal mine is located. The main component of the carbide slag is calcium hydroxide, which can produce tricalcium aluminate and dicalcium silicate with hydration activity after being calcined with the coal gangue, so as to obtain the solid waste-based cementitious material with certain cementitious activity. The solid waste-based cementitious material can produce calcium hydroxide, hydrated calcium silicate gel and hydrated calcium aluminate gel after reacting with water. The calcium hydroxide can stimulate the cementitious activity of the coal gangue powder, so that the gel product is generated on the surface of the coal gangue powder. The hydrated calcium silicate gel and the hydrated calcium aluminate gel also have certain cohesiveness, so as to reduce the possibility of segregation of the coal seam grouting material in the pumping process, help to reduce the pipe blocking phenomenon of the grouting material, improve the pumpability of the grouting material, and help to reduce the difficulty of grouting operation.

[0009] Preferably, the solid waste-based cementitious material is prepared by the following method:

[0010] (1) mixing the coal gangue and the carbide slag to obtain a mixture;

[0011] (2) crushing the mixture, mixing the crushing product with a grinding aid, and then grinding the mixture, and then calcining the ground product at 900-1000℃ for 2-3h to obtain the solid waste-based cementitious material.

[0012] By adopting the above technical scheme, the grinding aid is added in the grinding process, which helps the crushing products of the coal gangue and the carbide slag to fully contact, and is beneficial to increase the content of tricalcium aluminate and dicalcium silicate in the solid waste-based cementitious material, thereby reducing the possibility of segregation of the coal seam grouting material in the pumping process.

[0013] Preferably, the grinding aid is triethanolamine or sodium tripolyphosphate.

[0014] By adopting the above technical scheme, the triethanolamine or the sodium tripolyphosphate can play a grinding aid role, thereby improving the grinding effect. Compared with the sodium tripolyphosphate, the coordination bond formed by the triethanolamine and the calcium ion on the surface of the powder has poor stability, so that the triethanolamine is more likely to fall off from the surface of the crushing product of the coal gangue and the carbide slag. Therefore, selecting the sodium tripolyphosphate as the grinding aid is more conducive to the full contact of the crushing products of the coal gangue and the carbide slag, and is more conducive to increasing the content of tricalcium aluminate and dicalcium silicate in the solid waste-based cementitious material, thereby reducing the possibility of segregation of the coal seam grouting material in the pumping process.

[0015] Preferably, in the mixture, the weight of the carbide slag is 30-34% of the weight of the coal gangue.

[0016] By adopting the technical scheme, in the process of preparing the solid waste-based cementitious material, the carbide slag is dehydrated to form calcium oxide under calcination conditions, and the calcium oxide reacts with the crushed product of the coal gangue at high temperature to produce minerals such as tricalcium aluminate and dicalcium silicate. When the amount of the carbide slag is small, the amount of the minerals such as tricalcium aluminate and dicalcium silicate is also small, which makes it difficult to fully stimulate the activity of the coal gangue powder in the coal seam grouting material, and limits the strength performance of the coal seam grouting material after hardening. When the amount of the carbide slag is large, part of the residual calcium oxide exists in the solid waste-based cementitious material in the form of free calcium oxide, and the free calcium oxide has an adverse effect on the strength of the coal seam grouting material after hardening. When the weight of the carbide slag is 30-34% of the weight of the coal gangue, the strength performance of the coal seam grouting material after hardening is relatively good.

[0017] Preferably, in the mixture, the weight of the carbide slag is 32% of the weight of the coal gangue.

[0018] By adopting the technical scheme, the amount of the carbide slag powder is preferably selected, which helps to improve the strength performance of the coal seam grouting material after hardening.

[0019] Preferably, the components of the coal solid waste raw powder further include fly ash, and the mass fraction of the fly ash in the coal solid waste raw powder is 15-22%.

[0020] By adopting the technical scheme, although the use of the solid waste-based cementitious material can reduce the segregation phenomenon, the generation of the gel product also increases the friction between the powder particles, which is easy to affect the fluidity of the coal seam grouting material. On this basis, the present application limits that the coal solid waste raw powder contains fly ash, and the morphological effect of the fly ash reduces the friction between the powder particles, and improves the fluidity of the coal seam grouting material. In order to increase the consumption of the coal gangue powder as much as possible on the premise of improving the fluidity of the coal seam grouting material, the mass fraction of the fly ash is preferably 15-22%.

[0021] Preferably, the fly ash is F-class fly ash or C-class fly ash.

[0022] By adopting the technical scheme, the C-class fly ash usually contains more free calcium oxide than the F-class fly ash. When the amount of the carbide slag in the mixture is small, the free calcium oxide introduced by the fly ash can help the solid waste-based cementitious material to stimulate the cementitious activity of the coal gangue powder, and help to improve the strength of the grouting material after hardening. When the amount of the carbide slag in the mixture is large, increasing the total amount of the free calcium oxide is not conducive to the strength development of the grouting material, and at this time, the F-class fly ash is selected to help to reduce the influence of the free calcium oxide on the strength of the coal seam grouting material.

[0023] Preferably, the coal seam grouting material further comprises a polycarboxylate superplasticizer.

[0024] By using the above technical solution, the polycarboxylate superplasticizer can be adsorbed to the particle surface of the solid waste-based cementitious material, reducing the agglomeration of the solid waste-based cementitious material and releasing the free water wrapped by the particles of the solid waste-based cementitious material, which helps to improve the fluidity of the coal seam grouting material.

[0025] Preferably, the weight of the polycarboxylate superplasticizer is 1.5-2.5% of the weight of the solid waste-based cementitious material.

[0026] By using the above technical solution, the amount of polycarboxylate superplasticizer is optimized, which helps to sufficiently improve the fluidity of the coal seam grouting material while saving the amount of polycarboxylate superplasticizer.

[0027] In a second aspect, the application provides a method for applying a coal seam grouting material, which uses the following technical solution.

[0028] A method for applying a coal seam grouting material, comprising the following steps:

[0029] (1) preparing the coal seam grouting material as described above for standby;

[0030] (2) using a grouting device to pump the coal seam grouting material into the separation space under the key layer of the coal seam roof;

[0031] (3) after grouting, removing the grouting device and using cement slurry to seal the drill hole left by the grouting device, thereby completing the grouting operation.

[0032] By using the above technical solution, the method of the application first prepares the coal seam grouting material, and then injects the coal seam grouting material into the separation space through the grouting device, thereby realizing the filling of the separation space. Since the incorporation of the solid waste-based cementitious material helps to reduce the pipe blocking phenomenon of the grouting material, the adaptability of the coal seam grouting material to long-distance pumping is improved, and the difficulty of the grouting operation is reduced.

[0033] In summary, the application has the following beneficial effects:

[0034] 1. The application uses solid waste-based cementitious material to replace a part of the coal solid waste raw powder, which reduces the possibility of segregation of the coal seam grouting material during pumping by using the cohesiveness of the gel product, helps to reduce the pipe blocking phenomenon of the grouting material, improves the pumpability of the grouting material, and helps to reduce the difficulty of the grouting operation.

[0035] 2, The grinding aid is preferably selected from triethanolamine or sodium tripolyphosphate in the application. The use of sodium tripolyphosphate as the grinding aid is more conducive to the full contact of the broken products of coal gangue and carbide slag, thereby helping to increase the content of tricalcium aluminate and dicalcium silicate in the solid waste-based cementitious material and reduce the possibility of segregation of the coal seam grouting material during pumping.

[0036] 3, The method of the application reduces the pipe blocking phenomenon of the grouting material by incorporating the solid waste-based cementitious material, thereby improving the adaptability of the coal seam grouting material to long-distance pumping and reducing the difficulty of grouting operation. DETAILED DESCRIPTION

[0037] The application will be further described in detail below in conjunction with examples, preparation examples and comparative examples. The raw materials involved in the application can be obtained through commercial channels.

[0038] Preparation example of solid waste-based cementitious material

[0039] The following preparation example 1 is used as an example for illustration.

[0040] Preparation example 1

[0041] In this preparation example, the solid waste-based cementitious material is prepared according to the following method:

[0042] (1) Mix coal gangue and carbide slag to obtain a mixture; in this step, the weight of carbide slag is 28% of the weight of coal gangue; (2) crush the mixture, grind the broken products, and then calcine the ground products at 900℃ for 2h to obtain a solid waste-based cementitious material with an average particle size of 10μm.

[0043] Preparation example 2

[0044] The difference between this preparation example and preparation example 1 is that the solid waste-based cementitious material is prepared according to the following method:

[0045] (1) Mix coal gangue and carbide slag to obtain a mixture; in this step, the weight of carbide slag is 28% of the weight of coal gangue; (2) crush the mixture, mix the broken products with a grinding aid, and then grind them, and then calcine the ground products at 900℃ for 2h to obtain a solid waste-based cementitious material with an average particle size of 10μm; the grinding aid is triethanolamine, and the amount of the grinding aid is 0.04% of the weight of the broken products.

[0046] Preparation example 3

[0047] The difference between this preparation example and preparation example 2 is that the grinding aid is sodium tripolyphosphate.

[0048] Preparation example 4

[0049] The difference between the present preparation example and Preparation Example 3 is that, in step (2) of preparing the solid waste-based cementitious material, the calcination temperature of the ground product is 950℃, and the calcination time is 2.5h.

[0050] Preparation Example 5

[0051] The difference between the present preparation example and Preparation Example 3 is that, in step (2) of preparing the solid waste-based cementitious material, the calcination temperature of the ground product is 1000℃, and the calcination time is 3h.

[0052] As shown in Table 1, Preparation Examples 5-9 differ in that the weight percentage of carbide slag in coal gangue (hereinafter referred to as the carbide slag percentage) is different.

[0053] Table 1 Carbide slag percentage

[0054] Sample Carbide slag ratio / % Preparation Example 5 28 Preparation Example 6 30 Preparation Example 7 33 Preparation Example 8 34 Preparation Example 9 36

[0055] Example

[0056] Examples 1-5

[0057] The following is described by taking Example 1 as an example.

[0058] Example 1

[0059] The present example provides a coal seam grouting material, which comprises the following components: 100kg of coal solid waste raw powder, 40kg of solid waste-based cementitious material, and 165kg of water. The coal solid waste raw powder is coal gangue powder, and the solid waste-based cementitious material is prepared according to the method of Preparation Example 1.

[0060] In the present example, the application method of the coal seam grouting material comprises the following steps:

[0061] (1) The coal seam grouting material is prepared according to the method described in the present example, and is ready for use;

[0062] (2) The coal seam grouting material is pumped into the separation space under the key layer of the coal seam roof using a grouting device;

[0063] (3) After grouting is completed, the grouting device is removed, and the drill hole left by the grouting device is closed using cement slurry, and the grouting operation is completed.

[0064] As shown in Table 2, the main difference between Examples 1-5 is that the raw material ratio of the coal seam grouting material is different

[0065] Table 2 Raw material ratio of coal seam grouting material

[0066]

[0067]

[0068] Examples 6-13

[0069] As shown in Table 3, Examples 6-13 differ from Example 5 in that the solid waste-based cementitious material is prepared according to the method of a different preparation example.

[0070] Table 3 Preparation examples of solid waste-based cementitious material

[0071] This Preparation Example Sample Preparation Example Example 5 Preparation Example 1 Example 10 Preparation Example 6 Example 6 Preparation Example 2 Example 11 Preparation Example 7 Example 7 Preparation Example 3 Example 12 Preparation Example 8 Example 8 Preparation Example 4 Example 13 Preparation Example 9 Example 9 Preparation Example 5 / /

[0072] Example 14

[0073] This example differs from Example 9 in that the coal solid waste raw powder is a mixture of fly ash and coal gangue powder. In the coal solid waste raw powder, the mass fraction of fly ash is 12%, and the fly ash is C-type fly ash with a free calcium oxide content of 3.5%.

[0074] Example 15

[0075] This example differs from Example 11 in that the coal solid waste raw powder is a mixture of fly ash and coal gangue powder. In the coal solid waste raw powder, the mass fraction of fly ash is 12%, and the fly ash is C-type fly ash with a free calcium oxide content of 3.5%.

[0076] Example 16

[0077] This example differs from Example 15 in that the fly ash is F-type fly ash with a free calcium oxide content of 0.2%.

[0078] As shown in Table 4, Examples 16-20 differ in the mass fraction of fly ash in the coal solid waste raw powder.

[0079] Table 4

[0080] Sample Example 16 Example 17 Example 18 Example 19 Example 20 Fly ash mass fraction / % 12 15 18 22 25

[0081] Example 21

[0082] This example differs from Example 20 in that the component of the coal seam grouting material further includes a polycarboxylic acid water reducing agent, and the weight of the polycarboxylic acid water reducing agent is 1% of the weight of the solid waste-based cementitious material.

[0083] According to the method described in GB8076-2008 Concrete Admixtures, the water-reducing rate of the polycarboxylic acid water reducing agent of this example is 16% when the dosage is 1% of the weight of the reference cement.

[0084] As shown in Table 5, Examples 21-25 differ in the dosage of the polycarboxylic acid water reducing agent (in terms of percentage of the weight of the solid waste-based cementitious material).

[0085] Table 5 Dosage of polycarboxylic acid water reducing agent

[0086] Sample Example 21 Example 22 Example 23 Example 24 Example 25 Dosage / % 1 1.5 1.8 2.5 3

[0087] Comparative Example 1

[0088] Comparative Example 1

[0089] The present comparative example differs from Example 1 in that the solid waste-based cementitious material is replaced with the same weight of coal solid waste raw powder.

[0090] Comparative Example 2

[0091] The present comparative example differs from Example 2 in that the solid waste-based cementitious material is replaced with the same weight of coal solid waste raw powder.

[0092] Comparative Example 3

[0093] The present comparative example differs from Example 3 in that the solid waste-based cementitious material is replaced with the same weight of coal solid waste raw powder.

[0094] Comparative Example 4

[0095] The present comparative example differs from Example 4 in that the solid waste-based cementitious material is replaced with the same weight of coal solid waste raw powder.

[0096] Comparative Example 5

[0097] The present comparative example differs from Example 5 in that the solid waste-based cementitious material is replaced with the same weight of coal solid waste raw powder.

[0098] Performance detection test method

[0099] I. Bleeding rate detection

[0100] The prepared coal seam grouting material is added to a 1000 mL graduated cylinder, and a pipette is used to make up to the 1000 mL scale. After sealing and standing for 2 h, the scale reading corresponding to the interface between the upper clear water and the lower slurry is read again. After recording the reading, the above operation is repeated twice, and the average value of the three readings is taken as the interface height h (unit: mL), and the bleeding rate B is calculated according to the following formula:

[0101]

[0102] The calculation results of the bleeding rate are shown in Table 6.

[0103] Table 6 Bleeding rate

[0104]

[0105]

[0106] II. Strength performance detection

[0107] The 28d strength of the coal seam grouting material was detected according to the method recorded in JC / T 986-2018 Cement-based grouting material, and the ratio of the compressive strength value measured in each example to the compressive strength value of example 9 was calculated, which was recorded as the relative strength. The results are shown in Table 7.

[0108] Table 7 Relative strength

[0109] Sample Relative strength / % Example 9 100.0 Example 10 107.6 Example 11 112.9 Example 12 108.2 Example 13 105.8 Example 14 103.7 Example 15 110.4 Example 16 112.6

[0110] III. Relative fluidity

[0111] The fluidity of the coal seam grouting material was detected according to the method recorded in GB / T 1346-2011 Method for testing water requirement for standard consistency, setting time and soundness of cement, and the ratio between the fluidity measured in each example and the fluidity of example 11 was calculated, which was recorded as the relative fluidity. The results are shown in Table 8.

[0112] Table 8 Relative fluidity

[0113] Sample Relative fluidity / % Example 11 100.0 Example 15 109.4 Example 16 112.8 Example 17 115.7 Example 18 116.9 Example 19 117.3 Example 20 117.5 Example 21 124.8 Example 22 128.7 Example 23 131.9 Example 24 132.3 Example 25 132.5

[0114] It can be seen from examples 1-5 and comparative examples 1-5 in combination with Table 6 that the water separation rates of examples 1-5 are lower than those of comparative examples 1-5, which indicates that after a part of the coal solid waste raw powder is replaced by the solid waste-based cementitious material, the gel product improves the cohesion of the grouting material and reduces the degree of segregation of the coal seam grouting material, which helps to reduce the pipe blocking phenomenon of the grouting material and reduces the difficulty of grouting operation.

[0115] It can be seen from examples 5-7 in combination with Table 6 that the addition of grinding aids helps the broken products of coal gangue and carbide slag to fully contact, which is beneficial to increase the content of tricalcium aluminate and dicalcium silicate in the solid waste-based cementitious material and reduce the possibility of segregation of the coal seam grouting material during pumping. Under the same dosage conditions, the grinding effect of sodium tripolyphosphate is slightly better than that of triethanolamine, so that the tricalcium aluminate and dicalcium silicate in example 7 are more fully formed, and therefore the water separation rate of example 7 is lower than that of example 6.

[0116] It can be seen from examples 7-9 in combination with Table 6 that after increasing the calcination temperature and prolonging the calcination time of the solid waste-based cementitious material, the water separation rate of the coal seam grouting material decreases, which indicates that increasing the thoroughness of calcination helps to reduce the segregation of the coal seam grouting material.

[0117] It can be seen from examples 9-13 in combination with Table 7 that when the weight of the carbide slag is 30-34% of the weight of the coal gangue, especially around 32%, the strength performance of the hardened coal seam grouting material is better.

[0118] It can be seen from the combination of Example 9, Example 11, Example 14-16 and Table 7 that the strength performance measured in Example 14 is better than that of Example 9, the strength performance measured in Example 15 is slightly worse than that of Example 11, and the strength performance measured in Example 16 is better than that of Example 15 and close to that of Example 11, which indicates that when the content of carbide slag in the mixture is relatively small, the free calcium oxide introduced by fly ash can help to stimulate the cementitious activity of coal gangue powder in solid waste-based cementitious materials, and at this time, the selection of C-type fly ash is more helpful to improve the strength of the hardened grouting material. When the content of carbide slag in the mixture is relatively large, the residual free calcium oxide is also relatively large, and the selection of F-type fly ash with relatively low free calcium oxide content helps to reduce the impact of free calcium oxide on the strength of the coal seam grouting material.

[0119] It can be seen from the combination of Example 11, Example 15-20 and Table 8 that the selection of coal solid waste raw powder containing a certain amount of fly ash is more helpful to improve the fluidity of the coal seam grouting material. When the mass fraction of fly ash in the coal solid waste raw powder is 15-22%, the fly ash improves the fluidity of the coal seam grouting material. However, further increasing the content of fly ash not only makes it difficult to further improve the fluidity, but also is not conducive to increasing the consumption of coal gangue powder. In order to increase the consumption of coal gangue powder as much as possible under the premise of improving the fluidity, the mass fraction of fly ash in the coal solid waste raw powder should be preferably 15-22%.

[0120] It can be seen from the combination of Example 20, Example 21-25 and Table 8 that when the weight of polycarboxylic acid water reducing agent is 1.5-3.0% of the weight of solid waste-based cementitious material, the fluidity of the coal seam grouting material can be obviously improved compared with Examples 20-21. However, further increasing the amount of polycarboxylic acid water reducing agent not only makes it difficult to further improve the fluidity, but also increases the cost. In order to improve the fluidity of the coal seam grouting material under the premise of saving the package, the weight of polycarboxylic acid water reducing agent should be preferably 1.5-2.5% of the weight of solid waste-based cementitious material.

[0121] The specific embodiments are only an explanation of the present application, which is not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, but as long as the modifications are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A coal seam grouting material, characterized by, The coal seam grouting material comprises components in parts by weight: 120 parts of coal solid waste raw powder, 50 parts of solid waste-based cementitious material, and 175 parts of water, and the components of the coal seam grouting material further comprise polycarboxylic acid water reducer; The components of the coal solid waste raw powder comprise coal gangue powder and fly ash, the fly ash is F-class fly ash with free calcium oxide content of 0.2%, and the mass fraction of the fly ash is 25%; The solid waste-based cementitious material is prepared according to the following method: (1) mixing coal gangue and carbide slag to obtain a mixture, in the mixture, the weight of the carbide slag is 33% of the weight of the coal gangue; (2) crushing the mixture, mixing the crushing product with a grinding aid, and then grinding, and then calcining the grinding product at 1000 DEG C for 3h to obtain the solid waste-based cementitious material; the grinding aid is selected as sodium tripolyphosphate.

2. The coal seam grouting material according to claim 1, characterized by, The weight of the polycarboxylic acid water reducer is 1.5-2.5% of the weight of the solid waste-based cementitious material.

3. A method of using a coal seam grouting material, characterized by, The method comprises the following steps: (1) preparing the coal seam grouting material according to any one of claims 1-2 for standby use; (2) using a grouting device to pump the coal seam grouting material into a separation space under a key layer of a coal seam roof; (3) after the grouting is completed, removing the grouting device, and using cement slurry to seal a drill hole left by the grouting device, so that the grouting operation is completed.

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