Underground sludge solidification method

Abstract

According to the underground sludge solidification method, modified semi-hydrated gypsum, cement, an additive sodium aluminate and a retarder citric acid are added into water sump sludge to prepare filling slurry, the filling slurry can be used for filling underground room goaf positions and carrying out room goaf filling treatment, and the problems that current underground water sump sludge treatment is high in labor consumption, long in time consumption, high in cost and poor in effect are solved. The safety productivity is poor, and the like.

Description

Technical Field

[0001] This invention relates to the field of underground sludge treatment technology, and in particular to a method for solidifying underground sludge. Background Technology

[0002] Currently, the silt in the underground water tanks is generated during the excavation of mines and roadways. The silt generated in the underground water tanks can easily block drainage ditches, causing water to overflow into the roadways, making it difficult for vehicles and personnel to pass and increasing the risk. The water tanks and sedimentation ponds are difficult to clean, affecting production operations. Manual dredging is time-consuming and has a high risk factor.

[0003] Currently, most methods for treating sludge involve manual or mechanical cleaning, loading, and hauling it out of storage areas. After water is filtered, it is transported to the goaf or hoisted to the surface for storage. This method is labor-intensive, inefficient, requires highly integrated equipment, and results in sludge spillage and environmental pollution along the way. If directly fed into the goaf, the sludge, lacking gelling properties and in a slurry state, often causes hidden dangers due to prolonged accumulation, such as slurry collapse accidents in underground retaining walls. A very small number of companies use cement to bind and solidify the sludge for filling the goaf, but this method suffers from long setting times, insufficient strength, and excessive costs. Therefore, developing a low-cost method for treating sludge is essential.

[0004] Existing literature reports (patent publication number: CN109485368A, patent name: a soft soil solidifying agent with high moisture content and its application) discloses a soft soil solidifying agent with sulfoaluminate cement clinker, gypsum and lime, and ordinary silicate cement as the main materials. The shortcomings of this patent are that it uses a large amount of clinker, cement and lime, which results in high cost, and the raw materials need to be calcined, which consumes a lot of energy and is not environmentally friendly.

[0005] This invention utilizes silt from water tanks to prepare filling slurry for filling and treating voids in mine workings, solving the problems of high labor intensity, long processing time, high cost, and poor safety in current underground water tank silt treatment. Summary of the Invention

[0006] The purpose of this invention is to provide a method for solidifying underground sludge, which uses sludge from a water tank to prepare a filling slurry for filling and treating voids in mine workings, thus solving the problems of high labor intensity, long processing time, high cost, and poor safety in current underground sludge treatment.

[0007] The technical solution of this invention is as follows: A method for solidifying underground sludge, comprising the following steps: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Sludge solidification: Mix 1 kg of underground sludge, 0.3-0.7 kg of modified hemihydrate gypsum and 0.01-0.03 kg of cement for 2.5-3.5 min until the slurry is uniform to obtain filling slurry.

[0008] In step (1) above, the modified hemihydrate gypsum has a crystal water content of 7-10 wt% and a free water content of 20-24 wt%.

[0009] In the aforementioned step (1), the modified hemihydrate gypsum has a purity of ≥85% and a particle size of ≤0.075mm.

[0010] In step (2) above, the sludge is solidified by mixing 1 kg of sludge from the well, 0.3-0.5 kg of modified hemihydrate gypsum and 0.01-0.02 kg of cement for 3 minutes until the slurry is uniform and filling slurry is obtained.

[0011] Specifically, in the aforementioned step (2), the sludge is solidified by mixing 1 kg of underground sludge, 0.5 kg of modified hemihydrate gypsum and 0.01 kg of cement for 3 minutes until the slurry is uniform, thus obtaining the filling slurry.

[0012] In step (2) above, the stirring power is 0.55 / 0.37kW, the rotation speed is 280-290r / min, and the revolution speed is 120-130r / min.

[0013] In step (2) above, sodium aluminate 0.001-0.005 kg can also be added to the sludge solidification process.

[0014] Specifically, in step (2) above, 0.003-0.005 kg of sodium aluminate can also be added to the sludge solidification process.

[0015] The aforementioned silt in the well is silt from the well water tank, with a water content of 30-60%.

[0016] The aforementioned application of filling slurry in filling voids in underground mines: the filling slurry can be used to fill voids in underground mines, thereby improving the safety of underground mines.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. Synergistic Innovation in Raw Material Formulation: A Composite System of Hemihydrate Gypsum-Cement-Admixtures. Addressing the challenge of solidifying high-moisture-content (30%-60%) sludge in underground water tanks, this invention proposes for the first time a synergistic solidification system using hemihydrate gypsum (preferably modified retarded hemihydrate phosphogypsum) as the core cementitious material, combined with 325 cement / cement clinker and admixtures. Through a specific ratio (sludge: hemihydrate gypsum: cement: admixture = 1:(0.3-0.5):(0.01-0.05):(0.003-0.005), the defects of existing technologies using only cement for solidification—namely, long setting time, low strength, and high cost—are solved (e.g., Comparative Example 2 uses 20% cement with no strength, and Comparative Example 3 uses 50% cement with excessively high cost). The introduction of hemihydrate gypsum utilizes its rapid-setting properties to shorten the setting time, cement provides later-stage strength, and admixtures (such as accelerators) regulate fluidity, setting time, and bleeding rate. These three elements work synergistically to achieve low-cost, high-efficiency solidification.

[0018] 2. Technological Innovation: In-situ solidification underground, achieving "sludge not leaving the well." Breaking away from the traditional "dredging-transportation-surface treatment" model, this innovative process employs in-situ underground slurry preparation and backfilling solidification: directly utilizing underground sludge as raw material, the process involves batching, mixing, and transporting the sludge to the empty area underground, eliminating the need to transport the sludge out of the well. This process avoids slurry spillage and pollution during transportation (solving the environmental impact of existing technologies), while also eliminating the cost of equipment such as filter presses and lifting systems, significantly reducing labor intensity (solving the high labor intensity of dredging).

[0019] 3. Performance Breakthrough: Synergistic Optimization of Strength and Flowability. Through formulation optimization, key breakthroughs were achieved in the performance of the cured body: Strength met standards: 3-day strength > 0.5 MPa, 28-day strength > 1.0 MPa (e.g., formulation in Example 3: 3-day strength 0.86 MPa, 28-day strength 1.64 MPa), meeting the load-bearing requirements for filling downhole voids; Good flowability: Slurry concentration controlled at 62%-64%, flowability 18-20 cm, allowing for stable and continuous delivery; Low bleeding rate: Bleeding rate < 3.2% (e.g., formulation in Example 8: 3.2%), avoiding delamination of the filling body and ensuring curing effect.

[0020] 4. High-value utilization of solid waste: Green environmental protection and cost advantages. The raw material system is based on solid waste: the sludge in the underground water tank is itself mining solid waste, and the hemihydrate gypsum uses "wet-process phosphoric acid by-product hemihydrate phosphogypsum" (industrial solid waste), which is modified and reused after retarding, significantly improving the utilization rate of solid waste (solid waste ratio > 90%). Compared with pure cement solidification (comparative example 3 uses 50% cement), the cement usage of this invention is only 0.01-0.03 (relative to sludge), reducing material costs by more than 60% (calculated at 300 yuan / t cement and 15 yuan / t hemihydrate gypsum), which is in line with the trend of "low cost and high environmental protection" in mine management.

[0021] 5. This method is not only applicable to underground water tank sludge, but can also be extended to the solidification of high water content solid waste (such as roadway bottom mud and sedimentation tank sludge) in other mines such as coal mines and metal mines. Attached Figure Description

[0022] Figure 1 Before curing of filler slurry; Figure 2 After the filler slurry has been cured; Figure 3 Uniaxial compressive strength test; Figure 4 Slurry flowability test; Figure 5 : The process of preparing filler slurry. Detailed Implementation

[0023] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention.

[0024] Example 1: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5% of a modifier and 0.1% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of silt, 0.5 kg of modified hemihydrate gypsum and 0.01 kg of cement for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0025] Example 2: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of silt, 0.5 kg of modified hemihydrate gypsum and 0.03 kg of cement for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0026] Example 3: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of silt, 0.5 kg of modified hemihydrate gypsum and 0.05 kg of cement for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0027] Example 4: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of well sludge, 0.5 kg of modified hemihydrate gypsum, 0.03 kg of cement and 0.005 kg of sodium aluminate for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0028] Application: The well-stirred solidified sludge is used to fill empty areas in underground mines.

[0029] Example 5: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of well sludge, 0.3 kg of modified hemihydrate gypsum, 0.03 kg of cement and 0.005 kg of sodium aluminate for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0030] Application: The well-stirred solidified sludge is used to fill empty areas in underground mines.

[0031] Example 6: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of well sludge, 0.7 kg of modified hemihydrate gypsum, 0.03 kg of cement and 0.005 kg of sodium aluminate for 3 minutes until the slurry is uniform and filling slurry is obtained.

[0032] Application: The well-stirred solidified sludge is used to fill empty areas in underground mines.

[0033] Example 7: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of well sludge, 0.5 kg of modified hemihydrate gypsum, 0.01 kg of cement and 0.003 kg of sodium aluminate for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0034] Application: The well-stirred solidified sludge is used to fill empty areas in underground mines.

[0035] Example 8: Using modified hemihydrate gypsum and adding sodium aluminate as an admixture Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of well sludge, 0.3 kg of modified hemihydrate gypsum, 0.01 kg of cement and 0.001 kg of sodium aluminate for 3 minutes until the slurry is uniform and filling slurry is obtained.

[0036] Application: The well-stirred solidified sludge is used to fill empty areas in underground mines.

[0037] Comparative Example 1: Modified hemihydrate gypsum and added admixtures were replaced with sodium carbonate. Curing process: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Solidification: Mix 1 kg of well sludge, 0.5 kg of modified hemihydrate gypsum, 0.03 kg of cement and 0.005 kg of sodium carbonate for 3 minutes until the slurry is uniform and the filling slurry is obtained.

[0038] Comparative Example 2: Using modified hemihydrate gypsum and without additives Solidification process: Mix 1 kg of underground sludge and 0.2 kg of cement for 3 minutes until the slurry is uniform, and the solidified sludge slurry is obtained.

[0039] Comparative Example 3: Using modified hemihydrate gypsum and without additives Solidification process: Mix 1 kg of downhole sludge and 0.5 kg of cement for 3 minutes until the slurry is uniform, and the filling slurry is ready.

[0040] Comparative Example 4: Using unmodified dihydrate gypsum and without additives Solidification process: Mix 1 kg of well sludge, 0.5 kg of dihydrate gypsum and 0.03 kg of cement for 3 minutes until the slurry is uniform, and the filling slurry is ready.

[0041] The characteristics of the raw materials used in Examples 1-8 and Comparative Examples 1-4 above are as follows: Downhole sludge: It exists in a semi-fluid to viscous state, with a water content of 30%-60%, and its fluidity varies with the water content. The particle size is mainly fine (mostly less than 0.075 mm), containing a small amount of sand (0.075-2 mm). Density: 1.2-1.8 g / cm³ 3 The values ​​vary depending on the solid content and mineral composition. See Tables 1 and 2.

[0042] Table 1 Main chemical components of sludge in underground water tanks Sample Name P / ppm F / ppm pH <![CDATA[SO4 2- / ppm]]> Ca / ppm ammonia nitrogen / ppm Silt in the water tank 42001.87 8379.15 10.61 58603.79 223799.28 11.00 Table 2 Typical Particle Size Distribution of Silt in Underground Water Containment Particle size / μm 1.000 2.000 5.000 10.00 20.00 45.00 75.00 100.0 200.0 300.0 content / % 7.17 13.30 25.39 39.64 54.69 77.27 90.22 95.30 99.77 100.00 2. Hemihydrate phosphogypsum: A byproduct obtained from the hemihydrate wet phosphoric acid process.

[0043] 3. 325 cement / cement clinker: purchased from the market.

[0044] 4. Admixtures: mainly refer to quick-setting agents, sodium aluminate (NaAlO2) or sodium carbonate (Na2CO3), with a purity ≥95%, added in dry powder form, commercially available.

[0045] Experimental Example 1: Take the solidified sludge slurry from Examples 1-8 and Comparative Examples 1-4, mix them thoroughly, and test the slurry performance data (bleeding rate, fluidity, pH). Finally, pour the mixture into a 70.7*70.7*70.7 square mold and place it in a curing chamber (simulating downhole temperature and humidity) for curing (humidity 80%, temperature 20℃) (see...). Figure 1 , Figure 2 The cured body strength was tested after the appropriate curing period. The test results are shown in Table 3.

[0046] Table 3. Sludge solidification performance test Mixing ratio (all calculated on a dry basis) (kg) Flowability / cm Bleeding rate / % Final setting time / h Concentration / % pH 3d strength / MPa 28d strength / MPa Number Downhole sludge hemihydrate gypsum cement admixture Example 1 10.50 0.01 18.5 2.6 18.56 3 > 12 0.36 0.59 Example 2 10.50 0.03 19.6 2.4 17.66 2.5 > 12 0.62 0.96 Example 3 10.50 0.05 02 2.2 15.46 1.8 > 12 0.86 1.64 Example 410.500.03 0.005 (Sodium aluminate) 18.22.67.664＞120.751.02 Example 510.300.03 0.005 (Sodium aluminate) 19.52.59.962.5＞120.420.86 Example 610.700.03 0.005 (Sodium aluminate) 18.81.96.563.6＞120.941.52 Example 710.500.01 0.003 (Sodium aluminate) 19.52.510.662.8＞120.661.05 Example 810.300.01 0.001 (Sodium aluminate) 203.212.861＞120.240.46 Comparative Example 110.500.03 0.005 (Sodium carbonate) 18.53.210.663>120.480.72 Comparative Example 2 100.200 18.03.67262>1200.65 Comparative Example 3 100.500 16.63.24664>120.651.23 Comparative Example 41 0.50 (Gypsum dihydrate) 0.03019.08.672h uncondensed 62>1000.2 Experimental Example 2: The solidified sludge slurries from Examples 1-8 and Comparative Examples 1-4 were mixed evenly, and the leaching of toxic elements was tested. The results are shown in Table 2.

[0047] Table 2 Toxicity Leaching Data serial number P F <![CDATA[NH3-N]]> COD pb Cr As Cd Hg pH Example 1 - 8.91 3.27 - - 0.02 - - - 8.64 Example 2 0.02 8.86 1.78 13.20 - 0.01 - - - 9.61 Example 3 - 7.62 1.92 2.60 - - - - - 9.1 Example 6 0.02 8.21 2.05 9.70 - - - - - 9.15 Comparative Example 2 0.01 6.49 2.73 9.20 - 0.01 - - - 10.25 Comparative Example 3 0.02 6.07 3.00 10.60 - 0.02 - - - 11.23 analyze: 1. Strength formation mechanism: By adding the admixture sodium aluminate (NaAlO2): in an alkaline environment (slurry pH > 12, pH of all formulations in Table 3 > 12), it dissociates into Na⁺ and AlO2⁻. AlO2⁻ reacts with the Ca produced by the hydration of hemihydrate gypsum. 2 The reaction produces ettringite (3CaO·Al2O3·3CaSO4·32H2O), which is a needle-like crystal that can quickly fill the pores of the slurry and shorten the setting time (e.g., the final setting time of the formulation in Example 2 without additives was 17.6h, while the final setting time of the formulation in Example 4 with the addition of 0.05% sodium aluminate was 7.6h, a reduction of 57%). At the same time, it improves the early strength (the 3-day strength of the formulation in Example 4 was 0.75MPa vs. that of the formulation in Example 2, which was 0.62MPa, an increase of 21%).

[0048] Hemihydrate gypsum provides early rapid setting foundation (1-3d strength), cement (325 cement / clinker) provides later strength (28d strength) and early alkaline environment, and admixture (sodium aluminate) balances the contradiction between "rapid setting" and "workable time" by regulating the formation rate of ettringite. The three form a ternary synergistic system of "gypsum-cement-admixture", which solves the technical bottleneck of low curing strength of pure gypsum and high curing cost of pure cement (compared to Comparative Example 2 with 20% cement with no strength, and Comparative Example 3 with 50% cement with excessive cost).

[0049] Ultimately, experiments revealed that controlling the filling slurry formula to a ratio of sludge:hemihydrate gypsum:cement:admixture = 1:(0.3-0.5):(0.01-0.05):(0.003-0.005), with a slurry concentration of 62-64%, ensures the strength of the filling material. Simultaneously, the slurry possesses good fluidity and a suitable setting time, allowing for stable and continuous delivery to the downhole empty area. Furthermore, the solidified material meets environmental protection requirements.

[0050] 2. Economic Comparison: Based on modified hemihydrate gypsum at 15 yuan / ton, cement at 300 yuan / ton, and admixtures at 1200 yuan / ton, the required material costs are calculated as follows: ① The ratio of silt to hemihydrate gypsum to cement to admixture is 1:0.3:0.03:0. The slurry concentration is controlled at 64%, the slurry specific gravity is 1.55t / m3, and the material cost required to fill 1 cubic meter of slurry is 1.55*64%*((0.3 / 1.33)*15+(0.03 / 1.33)*300)=10.07 yuan.

[0051] ② The ratio of silt: hemihydrate gypsum: cement: admixture = 1:0.5:0.03:0.003, the slurry concentration is controlled at 64%, and the slurry specific gravity is 1.55t / m3. The material cost required to fill 1 cubic meter of slurry = 1.55*64%*((0.5 / 1.5303)*15+(0.03 / 1.533)*300+(0.003 / 1.533)*1200) = 13.01 yuan.

[0052] ③ The ratio of silt to cement is 1:0.5, the slurry concentration is controlled at 60%, and the slurry specific gravity is 1.58 t / m³. 3 The slurry concentration is controlled at 65%, and the material cost required to fill 1 cubic meter of slurry is 102.7 yuan.

[0053] The solidification method of this invention consists of underground sludge, modified hemihydrate gypsum, 325 cement / cement clinker, and admixtures. The resulting solidified sludge has good economic efficiency.

Claims

1. A method for solidifying underground sludge, characterized in that: The curing method is carried out according to the following steps: (1) Modification of hemihydrate phosphogypsum: Take hemihydrate phosphogypsum, a by-product of the hemihydrate wet phosphoric acid process, add 1.5-2.0% of a modifier and 0.1-0.2% of a retarder, wherein the modifier is quicklime and the retarder is citric acid, and mix and stir for 2-3 minutes to obtain modified hemihydrate gypsum. (2) Sludge solidification: Mix 1 kg of underground sludge, 0.3-0.7 kg of modified hemihydrate gypsum and 0.01-0.03 kg of cement for 2.5-3.5 min until the slurry is uniform to obtain filling slurry.

2. The method for solidifying downhole sludge according to claim 1, characterized in that: In step (1), the modified hemihydrate gypsum has a crystal water content of 7-10 wt% and a free water content of 20-24 wt%.

3. The method for solidifying downhole sludge according to claim 1, characterized in that: In step (1), the modified hemihydrate gypsum has a purity of ≥85% and a particle size of ≤0.075mm.

4. The method for solidifying downhole sludge according to claim 1, characterized in that: In step (2), the sludge is solidified by mixing 1 kg of sludge from the well, 0.3-0.5 kg of modified hemihydrate gypsum and 0.01-0.02 kg of cement for 3 minutes until the slurry is uniform, thus obtaining the filling slurry.

5. The method for solidifying downhole sludge according to claim 4, characterized in that: In step (2), the sludge is solidified by mixing 1 kg of sludge from the well, 0.5 kg of modified hemihydrate gypsum and 0.01 kg of cement for 3 minutes until the slurry is uniform, thus obtaining the filling slurry.

6. The method for solidifying downhole sludge according to claim 1, characterized in that: In step (2), the stirring power is 0.55 / 0.37kW, the rotation speed is 280-290r / min, and the revolution speed is 120-130r / min.

7. The method for solidifying downhole sludge according to claim 1, characterized in that: In step (2), sodium aluminate 0.001-0.005 kg can also be added to the sludge solidification process.

8. The method for solidifying downhole sludge according to claim 7, characterized in that: In step (2), sodium aluminate 0.003-0.005 kg can also be added to the sludge solidification process.

9. The method for solidifying downhole sludge according to claim 1, characterized in that: In step (2), the silt in the well is silt from the well water tank with a water content of 30-60%.

10. The application of the filling slurry according to claim 1 in filling voids in underground mine stops, characterized in that: The filling slurry can be used to fill empty areas in underground mines, improving the safety of underground mines.

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