A geopolymer-modified grouting material and its preparation method

Abstract

This invention discloses a geopolymer-modified grouting material and its preparation method. The invention utilizes a composite activator and modifier to disrupt, depolymerize, and repolymerize the structure of coal gangue, fully activating it and giving it strong cementitious properties. This results in a geopolymer-modified grouting material with a three-dimensional network structure. The mass ratio of coal gangue powder: desulfurized gypsum powder: microsilica powder: composite activator: modifier = 100:8:5:5:3. The test data of the prepared geopolymer-modified grouting material for water control and foundation grouting are as follows: The grout was prepared with a water-cement ratio of 1:1, and its properties were measured as follows: fluidity 260 mm; stone formation rate 99.8%; initial setting time 990 min, final setting time 2112 min; 3-day plastic strength 1211.6 kPa; 7-day compressive strength 8.82 MPa; free expansion rate 0.3%.

Description

Technical Field

[0001] This invention relates to the field of geological grouting materials technology, specifically to a geological polymer-modified grouting material and its preparation method. Background Technology

[0002] In the mining industry, as mines are mined deeper and hydrostatic pressure increases, the threat of high-pressure water to the working face floor becomes increasingly severe. Currently, coal mining enterprises typically use clay-cement grouting for coal seam floor reinforcement. However, with rising coal and electricity costs, cement procurement costs are increasing; simultaneously, the ecological damage caused by clay mining makes clay procurement and supply increasingly difficult. Therefore, there is an urgent need to find new grouting materials to replace clay and cement slurry for grouting reinforcement of coal mining face floors.

[0003] Furthermore, coal gangue is a major industrial solid waste generated during coal mining and washing, accounting for approximately 15% to 20% of total coal production. With the continuous exploitation and utilization of coal resources, the accumulated amount of coal gangue has exceeded 6 billion tons to date, and continues to grow at an average annual rate of approximately 150 million tons. The large-scale accumulation of coal gangue not only causes serious air, water, and soil pollution, but also leads to disasters such as gangue pile collapses, landslides, and debris flows. Improper storage and landfilling of large quantities of coal gangue solid waste, exposed to sunlight and rainwater, allows harmful components in the leachate and leaching to directly enter the soil, damaging the survival conditions of soil microorganisms and thus adversely affecting soil structure and quality. Due to its stable structure and chemical inertness, gangue has a low comprehensive utilization rate. The hazards of gangue solid waste fundamentally reduce the sustainable development capacity of cities and hinder regional economic development. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a geopolymer-modified grouting material and its preparation method. To achieve the above objectives, this invention achieves them through the following technical solutions: ① Large-scale stockpiling of coal-based solid waste gangue harms the ecological environment; ② Traditional grouting materials are costly, and clay mining causes ecological damage.

[0005] This invention proposes a geopolymer-modified grouting material and its preparation method, aiming to address the shortcomings of existing coal mine floor grouting materials for water control and the threat to the ecological environment posed by large amounts of coal-based solid waste discharge. Coal gangue has a stable structure and is an inert material. This invention utilizes composite activators and modifiers to disrupt, depolymerize, and repolymerize the structure of coal gangue, fully activating it to give it strong cementitious properties. This results in a geopolymer-modified grouting material with a three-dimensional network structure. This material is low-cost, uses readily available raw materials, and possesses characteristics such as acid and corrosion resistance, micro-expansion, good fluidity, and non-dispersibility in water.

[0006] The technical solution of this invention is: a geopolymer modified grouting material, the raw materials of which include coal gangue powder, desulfurized gypsum powder, microsilica powder, composite activator and modifier, wherein the mass ratio of coal gangue powder: desulfurized gypsum powder: microsilica powder: composite activator: modifier is (80-100): (5-10): (5-10): (5-8): (3-5).

[0007] A method for preparing a geopolymer-modified grouting material, wherein the coal gangue powder is prepared by: simply drying the stockpiled coal gangue, subjecting it to primary and secondary crushing, grinding and classifying it using a Raymond mill to obtain coal gangue powder, which is then packaged into ton bags for use. The storage environment should be dry and moisture-proof.

[0008] Preferably, the coal gangue powder has a particle size of 400-600 mesh and a bulk density of 0.9-0.95 g / cm³. 3 .

[0009] The desulfurized gypsum powder is a calcined gypsum powder obtained by dehydration, drying, grinding, and calcination of a byproduct of the desulfurization unit, with a particle size ≥200 mesh.

[0010] The average particle size of the microsilica powder is 0.1-0.3μm, of which more than 80% are less than 1μm, and the specific surface area is 20-28㎡ / g.

[0011] The composite activator is a mixture of sodium sulfate and slaked lime powder, wherein the mass ratio of sodium sulfate to slaked lime powder is 10:1.

[0012] Preferably, the sodium sulfate contains ≥99% Na2SO4 and the quicklime powder contains ≥90% Ca(OH)2.

[0013] The modifier is a mixture of attapulgite powder, sepiolite powder and sodium carboxymethyl starch.

[0014] Preferably, the mass ratio of attapulgite powder, sepiolite powder, and sodium carboxymethyl starch is 4:2:1, and the average particle size of attapulgite powder, sepiolite powder, and sodium carboxymethyl starch is ≥3000 mesh.

[0015] In summary, this invention provides a geopolymer-modified grouting material and its preparation method. Compared with the prior art, this invention has the following advantages:

[0016] With good fluidity, the geopolymer-modified grouting material of the present invention, after being injected into the target point, has excellent fluidity, which can increase the grout diffusion range and reduce the number of grouting holes, thereby reducing the cost of grouting modification of the base plate.

[0017] With its slight expansion and non-shrinkage properties, the geopolymer-modified grouting material of this invention is more suitable for grouting and water plugging than cement materials, which have a slight expansion of 0.5%-3% and can bond well with the surrounding rock.

[0018] The geological polymer modified grouting material of this invention is green and environmentally friendly. The raw materials are all non-toxic and harmless, and the main raw materials, coal gangue powder, desulfurized gypsum powder and microsilica powder, are solid wastes. This will enable the resource utilization of waste and promote the green and sustainable development of enterprises.

[0019] High plastic strength: The plastic strength of the geopolymer modified grouting material of this invention can reach 1000KPa at 1-3 days, and then continues to increase steadily, indicating that it has a good water-blocking effect.

[0020] The invention is cost-effective, utilizing large quantities of solid waste materials such as coal gangue and desulfurization gypsum, resulting in low overall production costs. Furthermore, in accordance with relevant national ministries' regulations, the "coal-for-gangue" program provides a government refund of 25 yuan per ton of resource tax to enterprises for every ton of coal gangue consumed. Detailed Implementation

[0021] The present invention will be further described in conjunction with the embodiments.

[0022] This invention is a geopolymer modified grouting material, the raw materials of which include coal gangue powder, desulfurized gypsum powder, microsilica powder, composite activator and modifier, wherein the mass ratio of coal gangue powder: desulfurized gypsum powder: microsilica powder: composite activator: modifier is (80-100): (5-10): (5-10): (5-8): (3-5).

[0023] A method for preparing a geopolymer-modified grouting material, wherein the coal gangue powder is prepared by: simply drying the stockpiled coal gangue, subjecting it to primary and secondary crushing, grinding and classifying it using a Raymond mill to obtain coal gangue powder, which is then packaged into ton bags for use. The storage environment should be dry and moisture-proof.

[0024] Preferably, the coal gangue powder has a particle size of 400-600 mesh and a bulk density of 0.9-0.95 g / cm³. 3 .

[0025] The desulfurized gypsum powder is a calcined gypsum powder obtained by dehydration, drying, grinding, and calcination of a byproduct of the desulfurization unit, with a particle size ≥200 mesh.

[0026] The average particle size of the microsilica powder is 0.1-0.3μm, of which more than 80% are less than 1μm, and the specific surface area is 20-28㎡ / g.

[0027] The composite activator is a mixture of sodium sulfate and slaked lime powder, wherein the mass ratio of sodium sulfate to slaked lime powder is 10:1.

[0028] Preferably, the sodium sulfate contains ≥99% Na2SO4 and the quicklime powder contains ≥90% Ca(OH)2.

[0029] The modifier is a mixture of attapulgite powder, sepiolite powder and sodium carboxymethyl starch.

[0030] Preferably, the mass ratio of attapulgite powder, sepiolite powder, and sodium carboxymethyl starch is 4:2:1, and the average particle size of attapulgite powder, sepiolite powder, and sodium carboxymethyl starch is ≥3000 mesh.

[0031] The detailed implementation steps are as follows:

[0032] a. Coal gangue is dried, crushed, and ground using a Raymond mill to obtain coal gangue powder with a particle size of 400-600 mesh and a bulk density of 0.9-0.95 g / cm³. 3 ;

[0033] b. Add sodium sulfate and quicklime powder to a small mixer at a mass ratio of 10:1 and stir for 5 minutes to obtain the composite activator;

[0034] c. Add attapulgite powder, sepiolite powder and sodium carboxymethyl starch in a mass ratio of 4:2:1 into a small mixer and stir for 10 minutes to obtain the modifier.

[0035] d. Add coal gangue powder, desulfurized gypsum powder, microsilica powder, composite activator and modifier into a small mixer in a certain mass ratio, stir for 10 minutes, mix thoroughly and then put into a sealed bag for use in preparing grouting fluid.

[0036] The mass ratio of the coal gangue powder, desulfurized gypsum powder, microsilica powder, composite activator and modifier is 100:8:5:5:3;

[0037] Furthermore, the mass ratio of the coal gangue powder, microsilica powder, composite activator and modifier is 100:5:5:3 as a comparison ①;

[0038] Furthermore, the mass ratio of the coal gangue powder, desulfurized gypsum powder, composite activator, and modifier is 100:8:5:3 as a comparison ②;

[0039] Table 1. Preparation of modified grouting materials in the examples and comparative examples.

[0040]

[0041] The coal gangue powder has a particle size of 400-600 mesh and a bulk density of 0.9-0.95 g / cm³. 3 ;

[0042] The desulfurized gypsum powder has a particle size of 325 mesh.

[0043] The average particle size of the microsilica powder is 0.1-0.3μm, of which more than 80% are less than 1μm, and the specific surface area is 20-28㎡ / g.

[0044] The composite activator is a mixture of sodium sulfate and slaked lime powder in a mass ratio of 10:1;

[0045] The modifier is a mixture of attapulgite powder, sepiolite powder and sodium carboxymethyl starch in a mass ratio of 4:2:1.

[0046] Slurries were prepared using the materials from the examples, Comparison ①, and Comparison ②, and their properties were tested.

[0047] The water-cement ratio of the slurry in the embodiment is 1:1;

[0048] The water-cement ratio of the slurry in comparison ① is 1:1;

[0049] The water-cement ratio of the slurry in comparison ② is 1:1;

[0050] Furthermore, the performance of the slurry from the example, the slurry from control ①, and the slurry from control ② was tested, and the test data are shown in Table 2.

[0051] Table 2 shows the test data of modified grouting materials for water control and grouting modification of the base plate provided in the examples and comparative examples.

[0052]

[0053] Table 2 shows the examples and comparisons ①, indicating that adding desulfurized gypsum powder can improve the stone-forming rate and expansion properties of the material;

[0054] Table 2 illustrates that the addition of microsilica powder can improve the fluidity and gelling properties of the material.

[0055] Table 2 shows the results of the examples, comparison ①, and comparison ②. The geopolymer modified grouting material for water prevention and control in the base grouting modification of the present invention has excellent fluidity, expansion, consolidation, and water-blocking properties.

[0056] This invention relates to a geopolymer-modified grouting material that utilizes coal gangue as the main raw material, along with activators and modifiers, to achieve resource utilization of coal gangue solid waste. It replaces traditional grouting materials such as pure cement slurry, clay-cement slurry, and cement-water glass. This material fills and reinforces karst fissures within a certain range of the limestone and Ordovician limestone aquifers on the working face floor, gradually weakening the water-bearing capacity and connectivity of the aquifers, blocking the hydraulic connection between aquifers, and transforming the aquifers into relatively impermeable layers. This achieves the goal of preventing water inrush at the coal seam floor, enabling safe pressurized mining of coal resources, realizing the comprehensive utilization of coal gangue and other solid waste resources, reducing the cost of coal seam floor water hazard control, extending the service life of the mine, thereby improving the economic benefits of enterprises, promoting high-quality green development of coal mining enterprises, and organically unifying economic, social, and environmental benefits. Ultimately, this leads to the large-scale promotion and application of geopolymer-modified grouting materials, contributing to low-carbon, energy-saving, green, and environmentally friendly sustainable economic development.

[0057] The embodiments described in this invention are for illustrative purposes only and do not constitute a limitation on the scope of the claims. Other substantially equivalent substitutions that can be conceived by those skilled in the art are all within the scope of protection of this invention.

Claims

1. A geopolymer-modified grouting material, characterized in that, Its raw materials include coal gangue powder, desulfurized gypsum powder, microsilica powder, composite activator, and modifier, wherein the mass ratio of coal gangue powder: desulfurized gypsum powder: microsilica powder: composite activator: modifier is (80-100): (5-10): (5-10): (5-8): (3-5). The particle size of coal gangue powder is 400-600 mesh, and the bulk density is 0.9-0.95 g / cm³. 3 ; The composite activator is a mixture of sodium sulfate and slaked lime powder, wherein the mass ratio of sodium sulfate to slaked lime powder is 10:1; The modifier is a mixture of attapulgite powder, sepiolite powder and sodium carboxymethyl starch; wherein the mass ratio of attapulgite powder, sepiolite powder and sodium carboxymethyl starch is 4:2:1, and the average particle size of attapulgite powder, sepiolite powder and sodium carboxymethyl starch is ≥3000 mesh.

2. A method for preparing a geopolymer-modified grouting material, based on the raw materials described in claim 1, characterized in that, The coal gangue powder preparation method is as follows: the stockpiled coal gangue is simply dried, then subjected to primary and secondary crushing, and finally ground and selected by Raymond mill to obtain coal gangue powder.

3. The geopolymer-modified grouting material according to claim 1, characterized in that, The desulfurized gypsum powder is a calcined gypsum powder obtained by dehydration, drying, grinding, and calcination of a byproduct of the desulfurization unit, with a particle size ≥200 mesh.

4. The geopolymer-modified grouting material according to claim 1, characterized in that, The average particle size of the microsilica powder is 0.1-0.3μm, of which more than 80% are less than 1μm, and the specific surface area is 20-28㎡ / g.

5. The geopolymer-modified grouting material according to claim 1, characterized in that, Sodium sulfate contains ≥99% Na2SO4, and quicklime powder contains ≥90% Ca(OH)2.

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