Phosphogypsum solidifying agent, phosphogypsum solidified body, and use thereof

Abstract

The application provides a phosphogypsum solidifying agent, a phosphogypsum solidifying body and application thereof, and relates to the technical field of building materials.The phosphogypsum solidifying agent provided by the application comprises the following raw materials in mass fraction: 65.02-91.23% of phosphogypsum slag cement, 5.47-16.25% of an additive, 0.55-3.84% of a modifier and 2.74-15.6% of an anti-permeation agent; the additive comprises an adsorbent, a precipitant, a coagulant and a complexing agent; and the modifier comprises a surfactant and a hydrophobic modifier.In the application, the phosphogypsum slag cement is combined with the additive, the modifier and the anti-permeation agent, so that the water resistance of the phosphogypsum solidifying body can be effectively improved, and the soluble harmful impurities in the phosphogypsum can be effectively adsorbed, thereby avoiding environmental pollution.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a phosphogypsum solidifying agent, a phosphogypsum solidified body and application thereof. BACKGROUND

[0002] Phosphogypsum is a by-product of phosphoric acid production by wet process of phosphate rock. If the generated phosphogypsum is stored and treated, not only a large amount of land will be occupied, but also the residual acid, phosphorus, fluorine, organic matter and other impurities may cause serious pollution to land and groundwater along with rainwater. In order to solve the above technical problems, the phosphogypsum is usually solidified to prevent the phosphogypsum from causing pollution to the environment. In the prior art, the raw materials usually used for solidifying the phosphogypsum include slag, fly ash, cement, lime and high molecular modification (such as resin-based cementing materials, specifically epoxy resin and polyurethane materials), and the phosphogypsum is solidified in a wrapping manner. However, due to the poor water resistance of the phosphogypsum itself, the phosphogypsum solidified by the above raw materials has defects of poor volume stability and poor water resistance under long-term periodic water erosion. SUMMARY

[0003] The present application provides a phosphogypsum solidifying agent, a phosphogypsum solidified body and application thereof. The phosphogypsum is solidified by the phosphogypsum solidifying agent provided by the present application, and the obtained phosphogypsum solidified body has excellent water stability and is environmentally friendly, meeting the requirements of building base materials and environmental protection.

[0004] In order to achieve the object of the present application, the present application provides the following technical solutions:

[0005] A phosphogypsum solidifying agent, comprising the following raw materials in terms of mass fraction: phosphogypsum slag cement 65.02-91.23%, additive 5.47-16.25%, modifier 0.55-3.84% and anti-permeation agent 2.74-15.6%

[0006] The additive comprises an adsorbent, a precipitant, a coagulant and a complexing agent; and the modifier comprises a surfactant and a hydrophobic modifier.

[0007] Preferably, the phosphogypsum slag cement comprises the following raw materials in terms of mass fraction: phosphogypsum 30-45 parts, slag 35-45 parts, clinker 2-5 parts, volcanic ash material 10-20 parts, activator 8-15 parts and fiber 1-3 parts.

[0008] Preferably, the volcanic ash material comprises one or more of metakaolin, steel slag and phosphorous slag.

[0009] The fiber comprises one or more of steel fiber, polypropylene fiber, polyvinyl alcohol fiber, glass fiber and natural fiber.

[0010] Preferably, the mass ratio of the adsorbent, the precipitant, the coagulant and the complexing agent is 1-2:1-2:1-2:1-2.

[0011] Preferably, the adsorbent comprises one or more of porous mineral material, activated carbon, activated alumina, hydrotalcite, goethite and iron oxide tailings;

[0012] The precipitant comprises one or more of calcium chloride, lime, ferric chloride and aluminum chloride;

[0013] The coagulant comprises inorganic salt coagulant and / or organic polymer coagulant;

[0014] The complexing agent comprises ethylenediamine tetramethylene phosphonic acid sodium and / or sodium nitrilotriacetate.

[0015] Preferably, the mass ratio of the surfactant and the hydrophobic modifier is 7-8:2-3.

[0016] Preferably, the surfactant is anionic surfactant; the hydrophobic modifier comprises one or more of polymethylhydrogen siloxane, acrylate and stearic acid.

[0017] The application also provides a phosphogypsum solidified body, which is obtained by mixing and molding phosphogypsum and a phosphogypsum solidifying agent in sequence; the phosphogypsum solidifying agent is the phosphogypsum solidifying agent described in the above technical solution.

[0018] Preferably, the mass ratio of the phosphogypsum and the phosphogypsum solidifying agent is 100:25-40.

[0019] The application also provides application of the phosphogypsum solidified body described in the above technical solution in a road base, a river embankment slope, a pool bottom or a roller compacted earth dam foundation.

[0020] The application provides a phosphogypsum solidifying agent, which comprises, by mass fraction, 65.02-91.23% of phosphogypsum slag cement, 5.47-16.25% of an additive, 0.55-3.84% of a modifier and 2.74-15.6% of an anti-permeation agent; the additive comprises an adsorbent, a precipitant, a coagulant and a complexing agent; the modifier comprises a surfactant and a hydrophobic modifier. In the application, the phosphogypsum slag cement cooperates with the additive, the modifier and the anti-permeation agent to effectively improve the water resistance of the phosphogypsum solidified body, and effectively adsorb soluble harmful impurities in the phosphogypsum, thereby avoiding environmental pollution.

[0021] Further, the large amount of silicon and aluminum oxides in the phosphogypsum slag cement are catalytically activated by the activator, and finally polymerize to form a three-dimensional network gel structure mainly in the form of SiO4 and AlO4 tetrahedron. The three-dimensional structure is extremely stable, and the interface between the gel and the phosphogypsum crystal structure can improve the compressive strength of the phosphogypsum solidified body. Meanwhile, the phosphogypsum slag cement has two ways of solidifying metal ions, namely physical adsorption and chemical reaction. The physical adsorption is to adsorb and wrap metal ions in the three-dimensional network structure, and the chemical linkage is to combine with metal ions through chemical reaction. The soluble phosphorus, soluble fluorine, As 2+ , Cd 2+ , Pb 2+ and Cr 6+ have good long-term solidification effect.

[0022] The application also provides a phosphogypsum solidified body, which is obtained by mixing and forming phosphogypsum and a phosphogypsum solidifying agent in sequence. In the application, the phosphogypsum is both a cementing component and a solidified object, which greatly improves the consumption amount of the phosphogypsum. The phosphogypsum solidified body has excellent water stability and is environmentally friendly. According to the results of the examples, the unconfined compressive strength of the phosphogypsum solidified body prepared by the application is 2.87-3.55 MPa, the water stability coefficient is 88.1-89.7%, the permeability coefficient is 0.58-0.89*10 -4 cm / s, the phosphogypsum solidified body has high water stability, and the content of heavy metal ions and soluble harmful impurities in the phosphogypsum solidified body meets the requirements of building base materials and environmental protection. DETAILED DESCRIPTION

[0023] The application provides a phosphogypsum solidifying agent, which comprises the following preparation raw materials in mass fraction: 65.02-91.23% of phosphogypsum slag cement, 5.47-16.25% of an additive, 0.55-3.84% of a modifier and 2.74-15.6% of a permeability inhibitor.

[0024] The additive comprises an adsorbent, a precipitant, a coagulant and a complexing agent; and the modifier comprises a surfactant and a hydrophobic modifier.

[0025] In the application, the preparation raw materials of the phosphogypsum solidifying agent comprise 65.02-91.23% of phosphogypsum slag cement in mass fraction, preferably 74.6-76.92%. In the application, the phosphogypsum slag cement preferably comprises the following preparation raw materials in mass fraction: 30-45 parts of phosphogypsum, 35-45 parts of slag, 2-5 parts of clinker, 10-20 parts of volcanic ash material, 8-15 parts of an activator and 1-3 parts of fiber.

[0026] In the present application, the preparation raw material of the phosphogypsum slag cement preferably comprises 30-45 parts of phosphogypsum, more preferably 40 parts, in terms of mass fraction. In the present application, the composition of the phosphogypsum is preferably CaSO4·2H2O. In the present application, the pH value of the phosphogypsum is preferably 3-6.5, more preferably 5.8; the water content of the phosphogypsum is preferably 5-20%, more preferably 6.4%. In the present application, the phosphogypsum is preferably a phosphogypsum slurry; the phosphogypsum slurry is preferably prepared by wet grinding of a mixture of phosphogypsum and water. In the present application, the solid content of the phosphogypsum slurry is preferably 60-75%, more preferably 70%. In the present application, the wet grinding time is preferably 20-40 min, more preferably 25 min. In the present application, the phosphogypsum does not need to be dried and ground before use, and the cementing performance of the phosphogypsum is exerted through synergistic effect with other components, which improves the consumption of phosphogypsum and saves energy consumption, and has better economic benefits.

[0027] In the present application, the preparation raw material of the phosphogypsum slag cement preferably comprises 35-45 parts of slag, more preferably 40 parts, in terms of mass fraction. In the present application, the composition of the slag is preferably CaO, SiO2 and Al2O3. In the present application, the slag is preferably S95 grade slag. In the present application, the Blaine specific surface area of the slag is preferably 400-500 m 2 / kg, more preferably 428.08 m 2 / kg; the density is preferably 2.6-3.0, more preferably 2.85 g / cm 3 ; the water content is preferably 0.08-0.15%, more preferably 0.1%. In the present application, the active silicon aluminum components (SiO2 and Al2O3) in the slag react to generate hydrated calcium silicate and hydrated calcium aluminate under alkaline conditions, part of the hydrated calcium aluminate continues to react with CaSO4·2H2O in the phosphogypsum to generate ettringite, the ettringite produced in the hydration is a difficult-to-dissolve crystal, the crystals will first cross-lap with each other to form a skeleton, and then interweave and link with the hydrated calcium silicate to form a spatial network structure, which has the effect of improving the compressive strength of the phosphogypsum.

[0028] In the present application, the preparation raw material of the phosphogypsum slag cement preferably comprises 2-5 parts of clinker, more preferably 3-4 parts, in terms of mass fraction. In the present application, the composition of the clinker is preferably cement clinker, and the Blaine specific surface area of the clinker is preferably 450-500 m 2 / kg, more preferably 442.84 m 2 / kg; the density is preferably 3.0-3.5 g / cm 3 , more preferably 3.02 g / cm 3In the present application, the clinker has the effects of increasing the system alkalinity, ensuring the smooth progress of the hydration reaction and stabilizing the hydration products (hydrated calcium silicate, hydrated calcium aluminate and ettringite).

[0029] In the present application, the preparation raw materials of the phosphogypsum slag cement preferably include 10-20 parts of the pozzolanic material by mass fraction, more preferably 15 parts. In the present application, the pozzolanic material preferably includes one or more of metakaolin, steel slag and phosphorous slag, more preferably metakaolin. In the present application, the pozzolanic material preferably includes active SiO2 and Al2O3; the particle size of the pozzolanic material is preferably 200-500 mesh, more preferably 200-300 mesh. In the present application, the pozzolanic material can increase the content of active silicon and aluminum components in the system, and has the effect of promoting the formation of hydration products.

[0030] In the present application, the preparation raw materials of the phosphogypsum slag cement preferably include 8-15 parts of the activator by mass fraction, more preferably 10-13 parts. In the present application, the activator is preferably an alkaline activator; the alkaline activator is preferably prepared from NaOH and water glass. In the present application, the mass ratio of NaOH to water glass is preferably 0.198:1. In the present application, the activator is used to catalytically activate the slag, clinker and pozzolanic material containing a large amount of silicon and aluminum oxides, and finally polymerize to form a three-dimensional network gel with SiO4 and AlO4 tetrahedron as the main existing form.

[0031] In the present application, the preparation raw materials of the phosphogypsum slag cement preferably include 1-3 parts of the fiber by mass fraction, more preferably 2 parts. In the present application, the fiber preferably includes one or more of steel fiber, polypropylene fiber, polyvinyl alcohol fiber, glass fiber and natural fiber, more preferably polyvinyl alcohol (PVA) fiber. In the present application, the fiber has the effects of improving the compressive strength, bending performance and crack resistance of the phosphogypsum solidified body.

[0032] In the present application, the preparation raw materials of the phosphogypsum solidifying agent include 5.47-16.25% of the additive by mass fraction, preferably 7.70-8.96%. In the present application, the additive includes adsorbent, precipitant, coagulant and complexing agent. In the present application, the adsorbent preferably includes one or more of porous mineral material, activated carbon, activated alumina, hydrotalcite, goethite and iron oxide tailings; the porous mineral material is more preferably one or more of bentonite, kaolin, diatomite and attapulgite, most preferably bentonite. In the present application, the adsorbent has a porous structure, and by virtue of its large specific surface area, it can remove soluble phosphorus, soluble fluorine, Cr, Cd, Pb and As impurities through physical adsorption, ion exchange or surface precipitation.

[0033] In the present application, the precipitant preferably comprises one or more of soluble calcium salt, lime, ferric chloride and aluminum chloride, the soluble calcium salt is more preferably one of calcium chloride, calcium bicarbonate, calcium citrate and calcium gluconate, and is further preferably calcium chloride. In the present application, the precipitant can react with soluble phosphorus and soluble fluorine to form insoluble phosphate and fluorine salt precipitates, avoiding phosphorus and fluorine pollution.

[0034] In the present application, the coagulant preferably comprises inorganic salt coagulant and / or organic polymer coagulant. In the present application, the inorganic salt coagulant is preferably one or more of aluminum sulfate, ferrous sulfate, potassium aluminum sulfate (alum), sodium aluminate and ferric sulfate; the organic polymer coagulant is preferably polyaluminum chloride and / or polyferric sulfate, and is more preferably polyferric sulfate. In the present application, the coagulant can bond or aggregate impurity particles (soluble phosphorus, soluble fluorine, Cr, Cd, Pb and As impurities) together, causing impurities to agglomerate and flocculate, thereby avoiding environmental pollution.

[0035] In the present application, the complexing agent preferably comprises ethylenediamine tetramethylene phosphonic acid sodium and / or sodium nitrilotriacetic acid, and is more preferably ethylenediamine tetramethylene phosphonic acid sodium. In the present application, the complexing agent can form stable complex compounds with heavy metal ions, and at the same time, the reaction between metal ions and other compounds is blocked, so that precipitation or oxidation reactions are not easy to occur, avoiding environmental pollution problems caused by arsenic, cadmium, lead and other ions.

[0036] In the present application, the mass ratio of the adsorbent, precipitant, coagulant and complexing agent is preferably 2-4:2-4:2-4:2-4, and is particularly preferably 2:3:3:2 or 2:2:2:4.

[0037] In the present application, the preparation raw materials of the phosphogypsum solidifying agent include 0.55-3.84% of a modifier, preferably 1.50-3.12% by mass fraction. In the present application, the modifier comprises a surfactant and a hydrophobic modifier. In the present application, the surfactant is preferably an anionic surfactant, which is preferably sodium lignosulfonate and / or calcium lignosulfonate, and is more preferably calcium lignosulfonate. In the present application, the surfactant can make the phosphogypsum release more free water, improve the compactness of the phosphogypsum after pressing, and at the same time, the hydrophobic group can play a role in blocking the invasion of external water sources, improving the water resistance of the phosphogypsum solidifying body.

[0038] In the present application, the hydrophobic modifier is preferably one or more of polymethyl hydrogen siloxane, acrylate and stearic acid, and is more preferably polymethyl hydrogen siloxane. In the present application, the hydrophobic modifier can form a dense waterproof layer inside the phosphogypsum solidifying body, thereby giving the phosphogypsum solidifying body good water resistance.

[0039] In the present application, the mass ratio of the surface active agent and the hydrophobic modifier is preferably 7-8:2-3, more preferably 7:3.

[0040] In the present application, the preparation raw material of the phosphogypsum solidifying agent includes 2.74-15.6% of the anti-permeation agent by mass fraction, preferably 11.53-14.92%. In the present application, the anti-permeation agent is preferably one or more of phosphate anti-permeation agent, silicate anti-permeation agent, acrylic acid anti-permeation agent, polyurethane anti-permeation agent and organic silicon anti-permeation agent, more preferably phosphate anti-permeation agent. In the present application, the main structure of the anti-permeation agent is a three-dimensional structure with linear and long branch network structure of atoms of high molecular compound, which can block the capillary channel of the phosphogypsum solidifying body, increase the compactness and anti-permeability of the phosphogypsum solidifying body, and thus ensure the stability and water resistance of the phosphogypsum solidifying body during use.

[0041] The present application does not have special limitation on the preparation method of the phosphogypsum solidifying agent, and the phosphogypsum slag cement, additive, modifier and anti-permeation agent can be mixed uniformly according to the above-mentioned proportion.

[0042] The present application also provides a phosphogypsum solidifying body, which is obtained by mixing and forming the phosphogypsum and the phosphogypsum solidifying agent in sequence; the phosphogypsum solidifying agent is the phosphogypsum solidifying agent in the above technical solution.

[0043] In the present application, the mass ratio of the phosphogypsum and the phosphogypsum solidifying agent is preferably 100:25-40, more preferably 100:26-33.5.

[0044] The present application does not have special limitation on the mixing method of the phosphogypsum and the phosphogypsum solidifying agent, and the purpose of uniform mixing can be achieved. In the present application, the forming is preferably static pressure forming or vibration pressure forming. In the present application, the pressure of the forming is preferably 10-15 MPa; the time of the forming is preferably 10-60 s, more preferably 15-30 s.

[0045] In the present application, the green body after the forming is preferably further cured to obtain the phosphogypsum solidifying agent. In the present application, the temperature of the curing is preferably 20-26℃, more preferably 22℃; the relative humidity is preferably ≥65%, more preferably 85-95%; the time is preferably 14-90 d, more preferably 28 d.

[0046] In the present application, the water content of the phosphogypsum solidifying body is preferably 9.21-9.88%. In the present application, the unconfined compressive strength of the phosphogypsum solidifying body is preferably 2.87-3.55 MPa. In the present application, the water stability coefficient of the phosphogypsum solidifying body is preferably 88.1-89.7%. In the present application, the permeability coefficient of the phosphogypsum solidifying body is preferably 0.58*10-4 ~0.89 x 10 -4 cm / s.

[0047] The application further provides application of the phosphogypsum solidified body in a river embankment slope, a pool bottom or a roller compacted earth dam base.

[0048] In the application, the phosphogypsum solidified body is preferably used as a transition layer in the roller compacted earth dam base.

[0049] In order to further illustrate the application, the phosphogypsum solidified agent and the phosphogypsum solidified body provided by the application are described in detail below in combination with examples, but they should not be understood as limiting the protection scope of the application.

[0050] Part of parameters of raw materials used in the following examples and comparative examples of the application are as follows:

[0051] Phosphogypsum: pH value is 5.8, and water content is 6.4wt%;

[0052] Slag: S95 grade, density is 2.85g / cm 3 , specific surface area is 428.08m 2 / kg, and water content is 0.1wt%;

[0053] Clinker: density is 3.02g / cm 3 , specific surface area is 442.84m 2 / kg;

[0054] Volcanic ash-like material: metakaolin, particle size is 300 mesh;

[0055] Activator: alkaline activator, which is prepared according to the mass ratio of water glass (solid content is 40wt%) to NaOH is 100:19.8.

[0056] Example 1

[0057] Phosphogypsum and water are mixed and wet ground for 25min to prepare a phosphogypsum slurry with a solid content of 70wt%; 6.43kg of the above phosphogypsum slurry, 3.5kg of slag, 0.22kg of clinker, 1kg of metakaolin, 1kg of alkaline activator and 0.3kg of polyvinyl alcohol fiber are weighed and mixed to obtain a phosphogypsum slag cement.

[0058] The 10 kg of phosphogypsum, 2.5 kg of phosphogypsum slag cement, 0.3 kg of additive (0.06 kg of bentonite, 0.09 kg of polymeric ferric sulfate, 0.09 kg of calcium chloride and 0.06 kg of ethylenediamine tetramethylene phosphonic sodium), 0.05 kg of modifier (0.035 kg of calcium lignin sulfonate and 0.015 kg of polymethyl hydrogen siloxane) and 0.5 kg of phosphate impermeability agent are mixed, and then the mixture is formed under the condition of 15 MPa, the green body obtained after the forming is cured under the condition of 22 ℃ and 95% relative humidity for 28 days, and the phosphogypsum solidified body is obtained.

[0059] Example 2

[0060] The phosphogypsum and water are mixed and wet ground for 25 min to prepare a phosphogypsum slurry with a solid content of 70%; 6.43 kg of the above phosphogypsum slurry, 4.5 kg of slag, 1 kg of clinker, 1 kg of metakaolin, 1 kg of alkaline activator and 0.3 kg of polyvinyl alcohol fiber are mixed to obtain a phosphogypsum slag cement.

[0061] The 10 kg of phosphogypsum, 2 kg of phosphogypsum slag cement, 0.2 kg of additive (0.04 kg of bentonite, 0.04 kg of polymeric ferric sulfate, 0.04 kg of calcium chloride and 0.08 kg of ethylenediamine tetramethylene phosphonic sodium), 0.1 kg of modifier (0.07 kg of calcium lignin sulfonate and 0.03 kg of polymethyl hydrogen siloxane) and 0.3 kg of phosphate impermeability agent are mixed, and then the mixture is formed under the condition of 15 MPa, the green body obtained after the forming is cured under the condition of 22 ℃ and 95% relative humidity for 28 days, and the phosphogypsum solidified body is obtained.

[0062] Comparative Example 1

[0063] The phosphogypsum and water are mixed and wet ground for 25 min to prepare a phosphogypsum slurry with a solid content of 70%; 6.43 kg of the above phosphogypsum slurry, 4.5 kg of slag and 1 kg of clinker are mixed to obtain a phosphogypsum slag cement.

[0064] The 10 kg of phosphogypsum and 2 kg of phosphogypsum slag cement are mixed, and then the mixture is formed under the condition of 10 MPa, the green body obtained after the forming is cured under the condition of 22 ℃ and 95% relative humidity for 28 days, and the phosphogypsum solidified body is obtained.

[0065] Comparative Example 2

[0066] The phosphogypsum and water are mixed and wet ground for 25 min to prepare a phosphogypsum slurry with a solid content of 70%; 6.43 kg of the above phosphogypsum slurry, 4.5 kg of slag and 1 kg of clinker are mixed to obtain a phosphogypsum slag cement.

[0067] Take 10 kg of phosphogypsum and 2 kg of phosphogypsum slag cement, 0.2 kg of phosphate impermeability agent, and then press under the condition of 10 MPa, and then the obtained body is cured at 22 DEG C, 95% relative humidity for 28 days, to obtain a phosphogypsum solidified body.

[0068] Test example

[0069] Take 628 g of phosphogypsum solidified body prepared in examples 1-2 and comparative examples 1-2 to prepare standard test pieces, and test according to "JTGE51-2009 Highway Engineering Inorganic Binder Stabilized Material Test Procedures", "T-CECSG-D45-02-2022 Roadway Phosphogypsum Cementitious Material Stabilized Base Technical Specifications", "DB42T1991-2023 Highway Phosphogypsum Composite Stabilized Base Material Application Technical Specifications", and "Code for Design of Roller Compacted Earth and Rockfill Dams", and the test results are shown in Table 1.

[0070] Table 1 Performance test results of phosphogypsum solidified body in examples 1-2 and comparative examples 1-2

[0071]

[0072] As can be seen from the results in Table 1, the phosphogypsum slag cement in the phosphogypsum solidifying agent provided by the present application plays a decisive role in the mechanical properties of the phosphogypsum solidified body, and when the alkaline activator and the fiber are added, the compressive strength of the prepared phosphogypsum solidified body is higher; the admixture can well inertize and modify the impurities in the phosphogypsum solidified body, effectively reducing the environmental risk caused by the overflow of impurities; the addition of the modifier effectively improves the water resistance of the phosphogypsum solidified body, solving the core problem of poor water resistance of phosphogypsum; the impermeability agent can further improve the compactness of the phosphogypsum solidified body, and to a certain extent, improve its mechanical properties and water resistance. The compatibility between the components in the phosphogypsum solidifying agent described in the present application is good, and has good synergistic effect, and plays its own characteristics, and the phosphogypsum solidified body after curing of the phosphogypsum solidifying agent described in the present application meets the various indicators in the standards, and has a theoretical basis for practical application.

[0073] Although the above embodiments have made a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained under the premise of no creativity according to the present embodiments, which all belong to the protection scope of the present application.

Claims

1. A phosphogypsum solidifying agent, raw materials for preparation of which include, by mass fraction, phosphogypsum slag cement 65.02-91.23%, additives 5.47-16.25%, modifiers 0.55-3.84%, and anti-permeation agents 2.74-15.6%; the additives include adsorbents, precipitants, coagulants, and complexing agents; the modifiers include surfactants and hydrophobic modifiers; the precipitants include one or more of soluble calcium salts, lime, ferric chloride, and aluminum chloride; the phosphogypsum slag cement is prepared from raw materials in the following mass fractions: phosphogypsum 30-45 parts, slag 35-45 parts, cement clinker 2-5 parts, volcanic ash-like material 10-20 parts, activator 8-15 parts, and fiber 1-3 parts. The volcanic ash-like material includes one or more of metakaolin, steel slag, and phosphorous slag.

2. The phosphogypsum solidification agent according to claim 1, characterized in that, The fiber includes one or more of steel fiber, polypropylene fiber, polyvinyl alcohol fiber, glass fiber, and natural fiber. The mass ratio of the adsorbents, precipitants, coagulants, and complexing agents is 2-4:2-4:2-4:2-4.

3. The phosphogypsum solidifying agent according to claim 1, wherein The adsorbents include one or more of bentonite, activated carbon, activated alumina, hydrotalcite, goethite, and iron oxide tailings.

4. The phosphogypsum solidifying agent according to claim 1 or 3, characterized in that, The coagulants include inorganic salt coagulants and / or organic polymer coagulants. The complexing agents include ethylenediamine tetramethylene phosphonic acid sodium and / or sodium nitrilotriacetate. The mass ratio of the surfactants and hydrophobic modifiers is 7-8:2-3.

5. The phosphogypsum solidifying agent according to claim 1, wherein The surfactants are anionic surfactants; the hydrophobic modifiers include one or more of polymethyl hydrogen siloxane, acrylate, and stearic acid.

6. The phosphogypsum solidifying agent according to claim 1 or 5, characterized in that, 7.A phosphogypsum solidified body prepared by mixing and molding phosphogypsum and a phosphogypsum solidifying agent in sequence; the phosphogypsum solidifying agent is the phosphogypsum solidifying agent of any one of claims 1-6. The mass ratio of the phosphogypsum and the phosphogypsum solidifying agent is 100:25-40.

8. The phosphogypsum solidification body according to claim 7, characterized in that 9.Use of the phosphogypsum solidified body of claim 7 or 8 in road base, river embankment slope, pool bottom, or roller compacted earth dam foundation. ​

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