Phosphogypsum-based high-strength impervious filling material and preparation process thereof

Abstract

The invention relates to the technical field of filling materials, and particularly discloses an ardealite-based high-strength anti-seepage filling material and a preparation process thereof, the ardealite-based high-strength anti-seepage filling material comprises 50%-65% of pretreated ardealite, 15%-25% of Portland cement, 5%-15% of superfine slag powder, 5%-10% of electrolytic manganese residues, 5%-8% of silica fume, 3%-6% of metakaolin, 2%-4% of a composite alkali activator and 0.5%-1.2% of a polycarboxylic acid water reducer, 0.3%-0.8% of an organic silicon water repellent and 0.05%-0.1% of cellulose ether; according to the invention, through chemical reaction of Mn < 2 + > in the electrolytic manganese residue and SO4 < 2-> in the phosphogypsum, micron-sized manganite crystals (MnAl2 (SO4) 4. 22H2O) are generated to actively fill internal micro-cracks of the material, so that a filling body is endowed with a self-repairing function and the impermeability is improved, and a composite alkali activator composed of NaOH and water glass is used for synergistically activating potential gelling activity of the superfine slag powder and the silica fume, so that the self-repairing filling material is prepared. And the formation of hydration products is accelerated, and 0.3-0.5 T of pulsed magnetic field is applied in the stirring process, so that the manganite crystals are guided to orderly grow along the expected stress direction of the filling body, and the compressive strength is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of filling materials, and in particular relates to a phosphogypsum-based high-strength anti-seepage filling material and a preparation process thereof. Background Art

[0002] In the field of civil engineering and resource recycling, filling materials are key materials in underground mining, tunnel support and waste backfilling projects. Their performance is directly related to the safety and durability of the projects. With the deepening of mineral resource mining and the enhancement of environmental protection awareness, how to efficiently utilize industrial waste (such as phosphogypsum, electrolytic manganese slag, etc.) to prepare high-performance filling materials has become a hot topic of current research. As a by-product of the phosphoric acid production process, the large-scale accumulation of phosphogypsum not only occupies land resources, but also may cause environmental pollution. Therefore, converting phosphogypsum into high-value-added filling materials is of great significance for achieving resource recycling and environmental protection.

[0003] In recent years, research on phosphogypsum-based filling materials has made certain progress, but the existing technology still has many shortcomings. Although some studies have attempted to improve the mechanical properties of phosphogypsum-based filling materials by adding cement, slag and other cementitious materials, these materials often have the problem of insufficient impermeability. Specifically, traditional phosphogypsum-based filling materials are prone to produce microcracks during the curing process. These microcracks become channels for the penetration of water and harmful substances, seriously affecting the long-term stability and durability of the filling body. Especially in underground projects, the impermeability of the filling body is directly related to the sealing effect of groundwater and the stability of the surrounding rock and soil. In the existing technology, although the impermeability of the filling material can be improved to a certain extent by adjusting the ratio or adding admixtures, it is often difficult to achieve high strength and excellent impermeability at the same time. Especially in complex geological conditions and long-term service environments, the impermeability of the filling material still faces severe challenges, so staff need to improve it. Summary of the Invention

[0004] The object of the present invention is to provide a phosphogypsum-based high-strength anti-seepage filling material and a preparation process to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A phosphogypsum-based high-strength anti-seepage filling material, comprising the following components by mass percentage:

[0007] Pretreated phosphogypsum: 50%-65%, Portland cement: 15%-25%, slag powder: 5%-15%, electrolytic manganese slag: 5%-10%, silica fume: 5%-8%, metakaolin: 3%-6%, composite alkali activator: 2%-4%, polycarboxylate water reducer: 0.5%-1.2%, silicone hydrophobic agent: 0.3%-0.8%, cellulose ether: 0.05%-0.1%;

[0008] Wherein, the Mn in the electrolytic manganese slag 2+ and SO4 in pre-treated phosphogypsum 2- The reaction generates manganese alumite (MnAl2(SO4)4·22H2O) to fill microcracks.

[0009] Preferably, the electrolytic manganese slag is calcined at 600°C to 650°C and then ground to a specific surface area of ​​≥400m 2 / kg, of which Mn 2+ Effective content ≥3.5wt%.

[0010] Preferably, the composite alkali activator is composed of NaOH solid powder and water glass with a modulus of 2.8 to 3.2 in a mass ratio of 1: (0.8 to 1.5).

[0011] Preferably, the preparation of the pretreated phosphogypsum comprises: washing with water to a pH value ≥ 6.5, calcining at 600°C ± 20°C for 1 hour and then rapidly cooling, and grinding to a specific surface area ≥ 350m 2 / kg and soluble P2O5 content ≤ 0.3%.

[0012] Preferably, the amount of manganese aluminite produced accounts for 1.2% to 2.5% of the total mass of the material, and the crystal size thereof is 0.5 to 2 μm.

[0013] Preferably, the slag fine powder is of S95 grade, and the mass ratio of the slag fine powder to the electrolytic manganese slag is (1.5-2.5):1.

[0014] A preparation process of a phosphogypsum-based high-strength anti-seepage filling material comprises the following steps:

[0015] S1. Pretreatment of electrolytic manganese slag: calcine the electrolytic manganese slag at 600℃~650℃ for 1h, quench with water and grind to a specific surface area of ​​≥400m 2 / kg;

[0016] S2. Dry mixing: dry mix the pretreated phosphogypsum, Portland cement, slag powder, silica fume, metakaolin and the electrolytic manganese slag obtained in step S1 for 5 to 8 minutes;

[0017] S3, wet mixing: adding mixing water containing composite alkali activator, polycarboxylate water reducer, organosilicon water repellent, and cellulose ether to the mixture of step S2, controlling the water-binder ratio to 0.28-0.32;

[0018] S4, stirring: stirring at a high speed of 1500-1800 rpm for 3-5 minutes;

[0019] S5. Curing: After injection molding, first cure in an environment with relative humidity ≥ 95% for 24 hours, then transfer to a standard curing room at 20±2℃ and cure to the target age.

[0020] Preferably, in step S3, the mixing water is added as follows: first dissolve the composite alkali activator in 40-50°C warm water, then add the polycarboxylate water reducer, silicone hydrophobic agent, and cellulose ether in sequence, and inject the dry mix after the solution temperature drops below 30°C.

[0021] Preferably, in step S4, a 0.3-0.5 T pulsed magnetic field is applied during the stirring process, and the direction of the magnetic field is parallel to the main direction of the expected force on the filling body.

[0022] Preferably, in step S5, a mixed gas with a CO2 volume concentration of 15% to 20% is introduced during the curing phase at a ventilation rate of 2 to 3 L / min for 4 to 6 hours.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Through the Mn in electrolytic manganese slag 2+ With SO4 in phosphogypsum 2- The chemical reaction generates micron-sized manganese aluminate crystals (MnAl2(SO4)4·22H2O), which actively fill the micro cracks inside the material, thereby giving the filling body a self-repairing function and significantly improving its impermeability.

[0025] (2) The composite alkali activator composed of NaOH and water glass synergistically activates the potential gelling activity of slag powder and silica fume, accelerates the formation of hydration products, and thus greatly improves the early and long-term mechanical strength of the material.

[0026] (3) Through water washing and high-temperature calcination (600℃±20℃) rapid cooling treatment, harmful impurities such as soluble P2O5 in phosphogypsum are deeply removed, eliminating their inhibition on the hydration reaction, thereby ensuring the stability and strength development of the gelling system.

[0027] (4) By applying a 0.3-0.5T pulsed magnetic field during the stirring process, the manganese alum crystals are guided to grow in an orderly manner along the expected stress direction of the filling body, thereby optimizing the uniformity of the material's stress structure and improving the compressive strength.

[0028] (5) By introducing 15% to 20% CO2 mixed gas during the curing stage, the system is prompted to generate carbonate minerals (such as CaCO3 and MnCO3) to fill the capillary pores, thereby reducing shrinkage and improving density.

[0029] (6) By controlling the addition order of the composite base activator and the reaction environment, the Mn 2+ With SO4 2- The formation of manganese alum (MnAl2(SO4)4·22H2O) instead of Mn(OH)2 precipitation, thus avoiding the precipitation of Mn in alkaline environment. 2+ It can significantly improve the self-repair efficiency and anti-seepage stability of micro cracks by reducing the ineffective consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a preparation flow chart of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1:

[0033] A phosphogypsum-based high-strength anti-seepage filling material, raw material components and proportions (mass percentage):

[0034] Pre-treated phosphogypsum: 58% (water washed pH = 6.8, calcined at 600℃ for 1h and then rapidly cooled, specific surface area 380m 2 / kg, soluble P2O5 = 0.25%), Portland cement: 20% (P·O 42.5 grade), slag powder: 8% (S95 grade, specific surface area 420m 2 / kg), electrolytic manganese slag: 7% (calcined at 650℃ for 1h and then water-quenched and ground, with a specific surface area of ​​410m 2 / kg,Mn 2+ Content: 3.8wt%), silica fume: 6% (SiO2 content 92%, average particle size 0.2μm), metakaolin: 4% (Al2O3 content 38%, activity index 95%), composite alkali activator: 3% (NaOH solid: water glass with modulus 3.0 = 1:1.2), polycarboxylate superplasticizer: 0.8% (solid content 40%, water reduction rate 30%), silicone hydrophobic agent: 0.5% (active ingredient ≥98%), cellulose ether: 0.07% (viscosity 40,000mPa·s), water-binder ratio: 0.30.

[0035] The mass ratio of electrolytic manganese slag to slag powder is 7:8 = 1:1.14.

[0036] Preparation process steps:

[0037] Electrolytic manganese slag pretreatment: industrial electrolytic manganese slag is calcined at 650℃ for 1h, quenched with water and then ground to a specific surface area of ​​410m 2 / kg, sealed and moisture-proof storage.

[0038] Dry mixing process: put pretreated phosphogypsum, silicate cement, slag powder, silica fume, metakaolin and pretreated electrolytic manganese slag into a double-screw mixer and dry mix for 7 minutes until uniform.

[0039] Preparation of wet mix solution: Dissolve NaOH solid in 45℃ warm water, add water glass and stir until completely dissolved;

[0040] After the solution is cooled to 28°C, polycarboxylate water reducer, silicone water repellent and cellulose ether are added in sequence.

[0041] Mixing and forming: Pour the wet mix solution into the dry mix and stir at high speed at 1600 rpm for 4 minutes;

[0042] A 0.4T pulsed magnetic field is applied simultaneously (the direction of the magnetic field is perpendicular to the bottom surface of the mold body, simulating the vertical force on the filling body).

[0043] Curing system: After the slurry is injected into the mold, it is placed in an environment with a relative humidity of ≥95% for 24 hours;

[0044] Transfer to a 20°C constant temperature curing room and introduce 18% CO2 mixed gas (flow rate 2.5 L / min, for 5 hours);

[0045] Continue standard maintenance until the age of 28 days.

[0046] Performance test results:

[0047] Mechanics and durability:

[0048] 3d compressive strength: 18.7MPa;

[0049] 28d compressive strength: 46.5MPa;

[0050] Permeability coefficient: 3.2×10 -10 cm / s;

[0051] Drying shrinkage (28d): 0.021%.

[0052] Mn 2+ Reaction path and mechanism of improving impermeability:

[0053] In traditional technology, Mn 2+ Under alkaline conditions, Mn(OH)2 (Ksp=1.9×10 -13 ), resulting in increased porosity of the material. This application circumvents this problem through the following design:

[0054] Staged reaction: the composite alkali activator first activates the slag / silica fume, and then the system SO4 2- After release, Mn 2+ Directed generation of manganese alumite;

[0055] Pulsed magnetic field guidance: 0.4T magnetic field causes manganese vanadium crystals to grow along the crack direction (SEM observation length 1.0-1.8μm);

[0056] CO2 mineralization assistance: 18% CO2 is introduced to generate MnCO3, further fixing free Mn 2+ (TG showed that manganese aluminate accounted for 2.1%, and there was no characteristic peak of Mn(OH)2).

[0057] This design reduces the permeability coefficient to 3.2×10 -10 cm / s, which is 3 orders of magnitude higher than that of traditional materials (comparative example: 3.5×10 -7 cm / s).

[0058] Verification of the formation of manganese vanadium:

[0059] X-ray diffraction (XRD): a characteristic diffraction peak of manganese aluminite (MnAl2(SO4)4·22H2O) appears at 14.2° (2θ) (JCPDS 00-046-1455);

[0060] Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS): needle-shaped manganese vanadium crystals (length 1.0-1.8 μm, width 0.2 μm) were observed to be densely filled in the gaps at the gypsum-cement interface;

[0061] Thermogravimetric analysis (TG): The weight loss peak at 200-300°C corresponds to the decomposition of manganese aluminite, which is calculated to account for 2.1% of the total mass of the material.

[0062] Crack and erosion resistance

[0063] Ring restraint shrinkage test (28 days): maximum crack width ≤ 0.05 mm (control group 0.15 mm);

[0064] Chloride ion diffusion coefficient (RCM method): 1.8×10 -12 m 2 / s (reaching the national standard of anti-chloride ion penetration level I);

[0065] Heavy metal leaching (Pb 2+ ): 0.15 mg / L (60% lower than the limit of GB 5085.3).

[0066] Example 2:

[0067] A phosphogypsum-based high-strength anti-seepage filling material, raw material components and proportions (mass percentage):

[0068] Portland cement: 22% (PO 42.5R early strength type), slag powder: 12% (S95 grade, specific surface area 430m 2 / kg), electrolytic manganese slag: 9% (calcined at 620℃ and then water-quenched and ground, with a specific surface area of ​​420m 2 / kg,Mn 2+ Content: 4.1wt%), silica fume: 5% (SiO2 content 94%, average particle size 0.15μm), metakaolin: 5% (Al2O3 content 40%, activity index 97%), composite alkali activator: 3.5% (NaOH solid: water glass with modulus 2.8 = 1:0.9), polycarboxylate superplasticizer: 1.0% (containing antifreeze component, solid content 35%), silicone hydrophobic agent: 0.6% (nano-silica modified type), cellulose ether: 0.09% (viscosity 60,000mPa·s), phase change microcapsule: 4% (paraffin / SiO2 core-shell structure, phase change temperature 8°C), water-binder ratio: 0.28.

[0069] Ratio description: The mass ratio of electrolytic manganese slag and slag powder = 9:12 = 1:1.33. Phase change microcapsules are newly added for low-temperature environments. The phase change temperature of 8°C accurately matches the hydration temperature rise range.

[0070] Preparation process steps:

[0071] Electrolytic manganese slag pretreatment: industrial electrolytic manganese slag is calcined at 620℃ for 1.2h, quenched with water and then ground to a specific surface area of ​​420m 2 / kg(Mn 2+ The dissolution rate increased to 89%).

[0072] Dry mixing process: pre-treated phosphogypsum, cement, mineral powder, silica fume, metakaolin, electrolytic manganese slag and phase change microcapsules are put into the mixer and dry mixed for 6 minutes until uniformly dispersed.

[0073] Preparation of wet mix solution: dissolve solid NaOH in 48℃ warm water, add water glass with a modulus of 2.8 and stir until completely dissolved;

[0074] After the solution is cooled to 25° C., a polycarboxylate water-reducing agent containing an antifreeze component, a nano-modified silicone water-repellent agent, and a high-viscosity cellulose ether are added in sequence.

[0075] Mixing and forming: Pour the wet mix solution into the dry mix and stir at high speed at 1700 rpm for 3.5 minutes;

[0076] A 0.35T pulsed magnetic field (parallel to the long side of the mold, simulating lateral soil pressure, with a magnetic field frequency of 5 Hz) was applied simultaneously.

[0077] Low temperature curing system: After injection molding, place the mold in a 5°C constant temperature box (simulating winter construction) and maintain it in a relative humidity ≥ 90% for 24 hours;

[0078] Transfer to a 5°C curing room and introduce 16% CO2 mixed gas (flow rate 3 L / min, for 4 hours);

[0079] Continue standard maintenance at 5°C until the age of 28 days.

[0080] Performance test results:

[0081] Low temperature mechanics and anti-permeability properties:

[0082] 3d compressive strength: 14.2MPa;

[0083] 7d compressive strength: 28.5MPa;

[0084] 28d compressive strength: 41.3MPa;

[0085] Permeability coefficient: 4.1×10 -10 cm / s;

[0086] Phase change thermal effect: The hydration temperature rise curve shows a 2.3-hour temperature platform at 4-10°C (the latent heat of phase change offsets the ambient cooling).

[0087] Formation and microstructure of manganese aluminite:

[0088] XRD quantitative analysis: the intensity of the characteristic peak of manganese vanadium (MnAl2(SO4)4·22H2O) is 18% higher than that of Example 1;

[0089] Low-temperature SEM observations: 0.3-1.5 μm needle-shaped ferromagnetite crystals developed completely at 5°C, filling the interface cracks;

[0090] CO2 mineralization synergy: generates a composite mineralized layer of MnCO3 (manganese stone) and CaCO3 (calcite), with a pore filling rate of 92.7%.

[0091] Durability verification:

[0092] Freeze-thaw resistance (-20℃~20℃ cycle 50 times): mass loss rate 0.8% (control group 3.7%), relative dynamic elastic modulus retention rate 94% (control group 78%), chloride ion penetration: diffusion coefficient 1.5×10 -12 m 2 / s (reaching national standard level Ⅰ), drying shrinkage rate: 0.019%.

[0093] Comparative Example:

[0094] Traditional phosphogypsum-cement-based materials:

[0095] Raw material ratio (mass %): untreated phosphogypsum (natural airing only): 65%, P·O 42.5 cement: 30%, fly ash (grade II): 5%, water-binder ratio: 0.45.

[0096] Preparation process: crush phosphogypsum to less than 2 cm, dry mix with cement and fly ash for 3 minutes; add water and stir for 2 minutes, then cast into the mold and standard cure (20℃, RH≥95%) for 28 days.

[0097] Comparison table:

[0098]

[0099]

[0100] Mechanism analysis: Soluble P2O5 (1.8%) in untreated phosphogypsum hinders cement hydration, and the porosity is as high as 28.6% (only 12.4% in Example 1).

[0101] Slag modified phosphogypsum-based materials:

[0102] Raw material ratio (mass %): washed phosphogypsum (pH=5.5): 60%, P·O 42.5 cement: 20%, slag powder (S75): 15%, quicklime: 5%, water-binder ratio: 0.40.

[0103] Preparation process: phosphogypsum is washed and dried (not calcined), and then dry-mixed with cement, slag, and quicklime; water is added and stirred for 3 minutes, and standard curing is carried out for 28 days.

[0104] Comparison table:

[0105] Test items Measured value Comparative Example 1 Degradation 28d compressive strength 24.8MPa 46.5MPa Down 47% Permeability coefficient <![CDATA[7.6×10 -8 cm / s]]> <![CDATA[3.2×10 -10 cm / s]]> Increased 237 times Drying shrinkage (28d) 0.062％ 0.021％ Increased by 195% Crack width (ring method) 0.28mm 0.05mm Increased by 460%

[0106] Mechanism analysis: There is a lack of electrolytic manganese slag to generate manganese aluminite, the slag activity is insufficiently stimulated (the degree of hydration is only 51%), and the shrinkage stress cannot be compensated.

[0107] Conventional materials for low temperature construction:

[0108] Raw material ratio (mass %): calcined phosphogypsum (300°C): 55%, sulphoaluminate cement: 35%, antifreeze (sodium nitrite): 3%, early strength agent (triethanolamine): 1%, water-binder ratio: 0.35.

[0109] Preparation process: Stir and shape at 5℃ environment, wet-cure for 24 hours, and then transfer to 5℃ curing room for 28 days.

[0110] Comparison table:

[0111]

[0112]

[0113] Mechanism analysis: At low temperatures, sulphoaluminate cement is not completely hydrated, there is no CO2 mineralization and manganese aluminate filling, and after freezing and thawing, the pores are connected to form seepage channels (pore diameter > 5μm).

[0114] Comprehensive performance comparison table:

[0115]

[0116] Note: * indicates data at 5°C; ** indicates data after freeze-thaw.

[0117] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A phosphogypsum-based high-strength anti-seepage filling material, characterized in that: The following components are included by mass percentage: Pretreated phosphogypsum: 50%-65%, Portland cement: 15%-25%, slag powder: 5%-15%, electrolytic manganese slag: 5%-10%, silica fume: 5%-8%, metakaolin: 3%-6%, composite alkali activator: 2%-4%, polycarboxylate water reducer: 0.5%-1.2%, silicone hydrophobic agent: 0.3%-0.8%, cellulose ether: 0.05%-0.1%; Wherein, the Mn in the electrolytic manganese slag 2+ and SO4 in pre-treated phosphogypsum 2- The reaction generates manganese alumite (MnAl2(SO4)4·22H2O) to fill microcracks.

2. The phosphogypsum-based high-strength anti-seepage filling material according to claim 1, characterized in that: The electrolytic manganese slag is calcined at 600℃~650℃ and then ground to a specific surface area of ​​≥400m2 / kg. 2+ Effective content ≥3.5wt%.

3. The phosphogypsum-based high-strength anti-seepage filling material according to claim 1, characterized in that: The composite alkali activator consists of NaOH solid powder and water glass with a modulus of 2.8 to 3.2 in a mass ratio of 1: (0.8 to 1.5).

4. The phosphogypsum-based high-strength anti-seepage filling material according to claim 1, characterized in that: The preparation of the pretreated phosphogypsum comprises: washing with water to a pH value of ≥6.5, calcining at 600°C±20°C for 1 hour and then rapidly cooling, and grinding to a specific surface area of ​​≥350m 2 / kg and soluble P2O5 content ≤ 0.3%.

5. The phosphogypsum-based high-strength anti-seepage filling material according to claim 1, characterized in that: The amount of manganese aluminite produced accounts for 1.2% to 2.5% of the total mass of the material, and the crystal size thereof is 0.5 to 2 μm.

6. The phosphogypsum-based high-strength anti-seepage filling material according to claim 1, characterized in that: The slag fine powder is of S95 grade, and the mass ratio of the slag fine powder to the electrolytic manganese slag is (1.5-2.5):

1.

7. A process for preparing a phosphogypsum-based high-strength and anti-seepage filling material, applicable to the phosphogypsum-based high-strength and anti-seepage filling material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Pretreatment of electrolytic manganese slag: calcine the electrolytic manganese slag at 600℃~650℃ for 1h, quench with water and grind to a specific surface area of ​​≥400m 2 / kg; S2. Dry mixing: dry mix the pretreated phosphogypsum, Portland cement, slag powder, silica fume, metakaolin and the electrolytic manganese slag obtained in step S1 for 5 to 8 minutes; S3, wet mixing: adding mixing water containing composite alkali activator, polycarboxylate water reducer, organosilicon water repellent, and cellulose ether to the mixture of step S2, controlling the water-binder ratio to 0.28-0.32; S4, stirring: stirring at a high speed of 1500-1800 rpm for 3-5 minutes; S5. Curing: After injection molding, first cure in an environment with relative humidity ≥ 95% for 24 hours, then transfer to a standard curing room at 20±2℃ and cure to the target age.

8. The process for preparing a phosphogypsum-based high-strength anti-seepage filling material according to claim 7, characterized in that: In step S3, the mixing water is added as follows: first dissolve the composite alkali activator in 40-50°C warm water, then add the polycarboxylate water reducer, silicone hydrophobic agent, and cellulose ether in sequence, and inject the dry mix after the solution temperature drops below 30°C.

9. The process for preparing a phosphogypsum-based high-strength anti-seepage filling material according to claim 7, characterized in that: In step S4, a 0.3-0.5 T pulsed magnetic field is applied during the stirring process, and the direction of the magnetic field is parallel to the main direction of the expected force on the filling body.

10. The process for preparing a phosphogypsum-based high-strength anti-seepage filling material according to claim 7, characterized in that: In step S5, during the curing phase, a mixed gas with a CO2 volume concentration of 15% to 20% is introduced at a ventilation rate of 2 to 3 L / min for 4 to 6 hours.

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