A method for mine ecological reconstruction using harmless phosphogypsum

Abstract

The present invention discloses a method for ecological reconstruction of mines using harmless phosphogypsum, and relates to the technical field of harmless treatment and resource utilization of phosphogypsum. The phosphogypsum that has been washed and deeply purified is further chemically treated to obtain harmlessly treated phosphogypsum; the mixture of the treated phosphogypsum and β-type building gypsum is used for ecological reconstruction of mines. By harmlessly treating the phosphogypsum and then using it together with building gypsum for ecological reconstruction, the comprehensive utilization of phosphogypsum is achieved, the risks that may be caused by stockpiling are reduced, and the ecological construction of mines is promoted at the same time, with significant environmental and economic benefits, and outstanding technical effects and application value. By further chemically treating the washed phosphogypsum, the targeted capture, fixation, and solidification of harmful substances are achieved to form insoluble and insoluble substances, thereby effectively controlling the leaching of harmful substances that may damage the environment in the ecological reconstruction material, and ensuring the safety and environmental protection of the material.

Description

Technical Field

[0001] The invention relates to the technical field of harmless treatment and resource utilization of phosphogypsum, and in particular to a method for reconstructing mine ecology by utilizing harmless phosphogypsum. Background Art

[0002] In the process of reconstructing the ecological environment of mines, the costs of various types of base materials are high and the results are minimal, resulting in few mines that have truly achieved ecological restoration.

[0003] Phosphogypsum is a by-product of the wet phosphoric acid process. Its main component is calcium sulfate dihydrate. In addition, it also contains impurities such as undecomposed phosphate rock, silicon dioxide, organic matter, phosphorus, and fluorine. Harmful components such as water-soluble phosphorus, fluorine, and heavy metals contained in phosphogypsum will leach out with natural rainfall and enter the surrounding water bodies, posing a high environmental risk. Currently, phosphogypsum is mostly used in the three major fields of agriculture, construction, and roads, mainly in primary utilization channels such as cement retarders and various building materials products.

[0004] If phosphogypsum can be used for ecological reconstruction of mine reclamation areas, on the one hand, it can increase the comprehensive utilization scope of phosphogypsum, and on the other hand, it can greatly improve the ecological environment of mines at a low cost. Summary of the invention

[0005] The purpose of the present invention is to provide a method for mine ecological reconstruction using harmless phosphogypsum, so as to solve the problems of low comprehensive utilization rate of phosphogypsum and high cost of mine ecological reconstruction.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for mine ecological reconstruction using harmless phosphogypsum, characterized by the following steps:

[0007] S1. further chemically treating the phosphogypsum after deep purification by washing to obtain harmless phosphogypsum;

[0008] S2. The mixture of the treated phosphogypsum and β-type building gypsum is used for mine ecological reconstruction.

[0009] A further technical solution is that the specific steps of step S2 are as follows:

[0010] S2-1. After harmless phosphogypsum and β-type building gypsum are mixed evenly in proportion, they are transported to the surface of the mine and flattened, piled up and rolled to make the dry density ≥96%, thereby obtaining an ecological reconstruction base;

[0011] S2-2. After harmless phosphogypsum and β-type building gypsum are mixed evenly in proportion, they are piled up at intervals on the surface of the ecological reconstruction base to form a protective layer;

[0012] S2-3. Mix harmless phosphogypsum, β-type building gypsum, grass seeds, soil and water in proportion and spread them between the protective layers to obtain a vegetation growth layer.

[0013] A further technical solution is that the specific steps of the chemical treatment in step S1 are to sequentially add an alkaline regulator, a targeted solidification stabilizer, and an activator to the washed phosphogypsum, fully stir and mix them, and then store and age them to obtain harmless phosphogypsum.

[0014] A further technical solution is that the amounts of the water-washed phosphogypsum, alkaline regulator, targeted solidification stabilizer and activator are calculated by weight as follows: 100 parts of dry phosphogypsum, 0.5-1.5 parts of alkaline regulator, 1-2 parts of targeted solidification stabilizer and 0.5-1.5 parts of activator.

[0015] A further technical solution is that the alkaline regulator is one or more of carbide slag, quicklime and caustic soda.

[0016] A further technical solution is that the targeted solidification stabilizer is one or more of polyacrylamide, polyferric sulfate, polyaluminium chloride, silicate cement, calcium chloride and alum.

[0017] A further technical solution is that the activator is one or more of fly ash and water glass.

[0018] A further technical solution is that the phosphogypsum after deep purification by water washing has a water content of 18-25%, a pH value of 5.14, a water-soluble phosphorus content of 440 mg / L, and a water-soluble fluorine content of 29.36 mg / L.

[0019] A further technical solution is that in step S2-1, the mass ratio of phosphogypsum to β-type building gypsum is 2-4:1, in step S2-2, the mass ratio of phosphogypsum to β-type building gypsum is 1-3:1, and the mass ratio of harmless phosphogypsum, β-type building gypsum, grass seeds, soil and water is 1-4:1-3:1:1:1.

[0020] A further technical solution is that the stacking thickness in step S2-1 is 30 to 60 cm, and the laying thickness in step S2-3 is 10 to 30 cm.

[0021] A further technical solution is that the specific steps of washing deeply purified phosphogypsum are as follows: adding water to the by-product phosphogypsum in the wet phosphoric acid production process to re-slurry, and controlling the solid content to 20-40%; filtering the re-slurried phosphogypsum through a filter, and then washing the gypsum filter cake through multi-stage countercurrent washing.

[0022] Working mechanism:

[0023] The dihydrate phosphogypsum produced as a byproduct of wet-process phosphoric acid production is first physically washed with water, and then targeted solidification and stabilization technology is used to react chemically with the phosphogypsum by adding additives such as alkaline regulators, targeted solidification stabilizers, and stimulants. The unwashed soluble impurities such as phosphorus and fluorine in the phosphogypsum are solidified and stabilized to form insoluble substances, thereby achieving the solidification and stabilization of toxic substances, realizing the harmless treatment of phosphogypsum, and meeting the entry requirements of general industrial solid waste as mine ecological restoration materials. The mine ecological reconstruction technology mainly uses harmless phosphogypsum as the main raw material, compounded with phosphorus building gypsum, grass seeds, water, etc., and mixed evenly as an ecological reconstruction material to achieve ecological reconstruction and prevent the occurrence of natural disasters such as landslides.

[0024] Among them, the targeted solidification stabilization technology in chemical treatment uses high molecular inorganic salts to convert soluble harmful components into insoluble salts, so that soluble phosphorus and fluorine are solidified. According to the three existing forms of soluble phosphorus in phosphogypsum: PO4 3- 、HPO4 2- 、H2PO4 3- , a form of soluble fluorine: F - , through the chemical reaction between the added additives and phosphogypsum, the main mechanism of solidification and stabilization of toxic substances is the generation of insoluble substances and the adsorption and encapsulation effect. That is, the added additives react chemically on the surface of phosphogypsum crystals to generate CaAl2Si2O8 and 3CaO·Al2O2·3CaSO4·32H2O and other substances as gel active substances, which are conducive to flocculation and aggregation, and then targeted adsorption and encapsulation of water-soluble phosphorus, fluorine and heavy metal ions contained in phosphogypsum. Targeted capture, fixation and solidification of harmful substances form insoluble and insoluble substances, thereby effectively controlling the leaching of harmful substances that may cause damage to the environment in ecological reconstruction materials, ensuring the safety and environmental protection of the materials.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Through the harmless treatment of phosphogypsum and then using it together with building gypsum for ecological reconstruction, the comprehensive utilization of phosphogypsum can be achieved, the risks that may be caused by storage can be reduced, and at the same time the ecological construction of the mine can be promoted. The environmental and economic benefits are significant, and it has outstanding technical effects and application value.

[0027] 2. Through further chemical treatment of washed phosphogypsum, the targeted capture, fixation and solidification of harmful substances can be achieved to form insoluble and insoluble substances, thereby effectively controlling the leaching of harmful substances that may cause damage to the environment in ecological reconstruction materials, and ensuring the safety and environmental protection of the materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the mine ecological reconstruction in the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] Example 1

[0031] A method for ecological reconstruction using harmless phosphogypsum, comprising the integration of two technologies: harmless treatment of phosphogypsum and mine ecological reconstruction.

[0032] (1) Harmless treatment of phosphogypsum

[0033] Specifically, according to the deep purification method of phosphogypsum disclosed in CN111892314A, the by-product phosphogypsum produced in the wet phosphoric acid production process is re-slurried with water to control the solid content to 20-40%; after the re-slurried phosphogypsum is filtered through a filter, the gypsum filter cake is washed by multi-stage countercurrent. The water-washed phosphogypsum obtained by our phosphogypsum washing device has a water content of 18%, and the main indicators of the leaching solution are shown in Table 1-1.

[0034] Table 1-1 Main indicators of water-washed phosphogypsum leachate (mg / L)

[0035]

[0036] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, 5 parts of targeted solidification stabilizer polyferric sulfate, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 1-2.

[0037] Table 1-2 Main indicators of harmless phosphogypsum leachate of Example 1 (mg / L)

[0038]

[0039] Note: “ / ” indicates not detected

[0040] (2) Ecological reconstruction

[0041] (I) Basic processing

[0042] After the harmless phosphogypsum and phosphogypsum building plaster are placed in a high-speed mixing equipment in a ratio of 4:1 and fully stirred, a small bulldozer is used to transport the mixed material to the outer slope and flatten it. The pile thickness is 30 cm. A vibrating roller is used to compact it. The dry density reaches ≥96%, and a leachate collection pipe is reserved at the bottom of the base.

[0043] (II) Protective layer treatment

[0044] On the base layer, harmless phosphogypsum and phosphogypsum building plaster are mixed in a ratio of 3:1. A protective layer is laid every 1 meter and drainage pipes are set up.

[0045] (III) Vegetation growth layer

[0046] Mix harmless phosphogypsum, phosphate building gypsum powder, grass seeds, soil and water in the ratio of 1:1:1:1:1 and lay it between the protective layers as a vegetation growth material layer with a thickness of 10 cm.

[0047] Example 2

[0048] (1) Detoxification of phosphogypsum

[0049] Specifically, the washed phosphogypsum obtained by our company's phosphogypsum washing device has a moisture content of 18%, and the main indicators of the leaching solution are shown in Table 2-1.

[0050] Table 2-1 Main indicators of water-washed phosphogypsum leachate (mg / L)

[0051]

[0052] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator carbide slag, 5 parts of targeted solidification stabilizer polyferric sulfate, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 2-2.

[0053] Table 2-2 Main indicators of harmless phosphogypsum leachate of Example 2 (mg / L)

[0054]

[0055] Note: “ / ” indicates not detected

[0056] (2) Ecological reconstruction

[0057] (I) Basic processing

[0058] After the harmless phosphogypsum and phosphogypsum building plaster are placed in a high-speed mixing equipment in a ratio of 3:1 and fully stirred, a small bulldozer is used to transport the mixed material to the outer slope and flatten it. The pile thickness is 50 cm. A vibrating roller is used to compact it. The dry density reaches ≥96%, and a leachate collection pipe is reserved at the bottom of the base.

[0059] (II) Protective layer treatment

[0060] On the base layer, harmless phosphogypsum and phosphogypsum building plaster are mixed in a ratio of 2:1, and a protective layer and drainage pipe are laid every 1 meter.

[0061] (III) Vegetation growth layer

[0062] Mix harmless phosphogypsum, phosphate building gypsum powder, grass seeds, soil and water in the ratio of 2:1:1:1:1 and lay it between the protective layers as a vegetation growth material layer with a thickness of 20 cm.

[0063] Example 3

[0064] (1) Detoxification of phosphogypsum

[0065] Specifically, the washed phosphogypsum obtained by our company's phosphogypsum washing device has a moisture content of 18%, and the main indicators of the leaching solution are shown in Table 3-1.

[0066] Table 3-1 Main indicators of water-washed phosphogypsum leachate (mg / L)

[0067]

[0068] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, 5 parts of targeted solidification stabilizer polyaluminium chloride, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 3-2.

[0069] Table 3-2 Main indicators of harmless phosphogypsum leachate of Example 3 (mg / L)

[0070]

[0071]

[0072] (2) Ecological reconstruction

[0073] (I) Basic processing

[0074] After the harmless phosphogypsum and phosphogypsum building plaster are placed in a high-speed mixing equipment in a ratio of 2:1 and fully stirred, a small bulldozer is used to transport the mixed material to the outer slope and flatten it. The pile thickness is 60 cm. A vibrating roller is used to compact it. The dry density reaches ≥96%, and a leachate collection pipe is reserved at the bottom of the base.

[0075] (II) Protective layer treatment

[0076] On the base layer, harmless phosphogypsum and phosphogypsum building gypsum are mixed in a 1:1 ratio, and a protective layer and drainage pipe are laid every 1 meter.

[0077] (III) Vegetation growth layer

[0078] Mix harmless phosphogypsum, phosphate building gypsum powder, grass seeds, soil and water in the ratio of 3:1:1:1:1 and lay it between the protective layers as a vegetation growth material layer with a thickness of 30 cm.

[0079] Example 4

[0080] (1) Detoxification of phosphogypsum

[0081] Specifically, the washed phosphogypsum obtained by our company's phosphogypsum washing device has a moisture content of 18%, and the main indicators of the leaching solution are shown in Table 4-1.

[0082] Table 4-1 Main indicators of water-washed phosphogypsum leachate (mg / L)

[0083]

[0084] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, 5 parts of targeted solidification stabilizer polyacrylamide, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 4-2.

[0085] Table 4-2 Main indicators of harmless phosphogypsum leachate of Example 4 (mg / L)

[0086]

[0087] Note: “ / ” indicates not detected

[0088] (2) Ecological reconstruction

[0089] (I) Basic processing

[0090] After the harmless phosphogypsum and phosphogypsum building plaster are placed in a high-speed mixing equipment in a ratio of 2:1 and fully stirred, a small bulldozer is used to transport the mixed material to the outer slope and flatten it. The pile thickness is 60 cm. A vibrating roller is used to compact it. The dry density reaches ≥96%, and a leachate collection pipe is reserved at the bottom of the base.

[0091] (II) Protective layer treatment

[0092] On the base layer, harmless phosphogypsum and phosphogypsum building gypsum are mixed in a 1:1 ratio, and a protective layer and drainage pipe are laid every 1 meter.

[0093] (III) Vegetation growth layer

[0094] Mix harmless phosphogypsum, phosphate building gypsum powder, grass seeds, soil and water in the ratio of 4:1:1:1:1 and evenly lay it between the protective layers as a vegetation growth material layer with a thickness of 30 cm.

[0095] Example 5

[0096] (1) Harmless treatment of phosphogypsum

[0097] Specifically, the washed phosphogypsum obtained by our company's phosphogypsum washing device has a moisture content of 18%, and the main indicators of the leaching solution are shown in Table 5-1.

[0098] Table 5-1 Main indicators of water-washed phosphogypsum leachate (mg / L)

[0099]

[0100] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, 5 parts of targeted solidification stabilizer silicate cement, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 5-2.

[0101] Table 5-2 Main indicators of harmless phosphogypsum leachate of Example 5 (mg / L)

[0102]

[0103] Note: “ / ” indicates not detected

[0104] (2) Ecological reconstruction

[0105] (I) Basic processing

[0106] After the harmless phosphogypsum and phosphogypsum building plaster are placed in a high-speed mixing equipment in a ratio of 2:1 and fully stirred, a small bulldozer is used to transport the mixed material to the outer slope and flatten it. The pile thickness is 60 cm. A vibrating roller is used to compact it. The dry density reaches ≥96%, and a leachate collection pipe is reserved at the bottom of the base.

[0107] (II) Protective layer treatment

[0108] On the base layer, harmless phosphogypsum and phosphogypsum building gypsum are mixed in a 1:1 ratio, and a protective layer and drainage pipe are laid every 1 meter.

[0109] (III) Vegetation growth layer

[0110] Mix harmless phosphogypsum, phosphate building gypsum powder, grass seeds, soil and water in the ratio of 3:2:1:1:1 and lay it between the protective layers as a vegetation growth material layer with a thickness of 30 cm.

[0111] Example 6

[0112] (1) Detoxification of phosphogypsum

[0113] Specifically, the washed phosphogypsum obtained by our company's phosphogypsum washing device has a moisture content of 18%, and the main indicators of the leaching solution are shown in Table 6-1.

[0114] Table 6-1 Main indicators of water-washed phosphogypsum leachate (mg / L)

[0115]

[0116] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, 5 parts of targeted solidification stabilizer polyferric sulfate, and 5 parts of activator water glass, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 6-2.

[0117] Table 6-2 Main indicators of harmless phosphogypsum leachate of Example 6 (mg / L)

[0118]

[0119] Note: “ / ” indicates not detected

[0120] (2) Ecological reconstruction

[0121] (I) Basic processing

[0122] After the harmless phosphogypsum and phosphogypsum building plaster are placed in a high-speed mixing equipment in a ratio of 2:1 and fully stirred, a small bulldozer is used to transport the mixed material to the outer slope and flatten it. The pile thickness is 60 cm. A vibrating roller is used to compact it. The dry density reaches ≥96%, and a leachate collection pipe is reserved at the bottom of the base.

[0123] (II) Protective layer treatment

[0124] On the base layer, harmless phosphogypsum and phosphogypsum building gypsum are mixed in a 1:1 ratio, and a protective layer and drainage pipe are laid every 1 meter.

[0125] (III) Vegetation growth layer

[0126] Mix harmless phosphogypsum, phosphate building gypsum powder, grass seeds, soil and water in the ratio of 3:3:1:1:1 and lay it between the protective layers as a vegetation growth material layer with a thickness of 30 cm.

[0127] Example 7

[0128] In order to further verify the solidification stabilization effect of targeted solidification stabilizers on phosphorus and fluorine impurities in chemical treatment, a comparative example verification was carried out.

[0129] Comparative Example 1

[0130] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 7-1.

[0131] Table 7-1 Main indicators of harmless phosphogypsum leachate of comparative example 1 (mg / L)

[0132]

[0133] Comparative Example 2

[0134] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator carbide slag, and 5 parts of activator fly ash, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 7-2.

[0135] Table 7-2 Main indicators of harmless phosphogypsum leachate of comparative example 2 (mg / L)

[0136]

[0137] Note: “ / ” indicates not detected

[0138] Comparative Example 3

[0139] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator quicklime, and 5 parts of activator water glass, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 7-3.

[0140] Table 7-3 Main indicators of harmless phosphogypsum leachate of comparative example 3 (mg / L)

[0141]

[0142] Comparative Example 4

[0143] Take 500 parts of washed phosphogypsum, 5 parts of alkaline regulator carbide slag, and 5 parts of activator water glass, mix them with the washed phosphogypsum for 30 minutes, place them in a beaker at room temperature for aging and maturation, and then determine the leachate indicators according to the "Solid Waste Leaching Toxicity Leaching Method Horizontal Oscillation Method" (HJ557-2010). The test results are shown in Table 7-4.

[0144] Table 7-4 Main indicators of harmless phosphogypsum leachate of comparative example 4 (mg / L)

[0145]

[0146] It can be seen from Tables 7-1 to 7-4 that the F and P contents of phosphogypsum that has not been treated with targeted solidification stabilizers are difficult to meet the standard limit requirements.

[0147] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise numerous other modifications and implementations that fall within the scope of the present disclosure. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and modifications may be made to the components or layout. In addition to variations and modifications to the components or layout, other uses will be apparent to those skilled in the art.

Claims

1. A method for mine ecological reconstruction using harmless phosphogypsum, characterized in that Here are the steps: S1. further chemically treating the phosphogypsum after deep purification by washing to obtain harmless phosphogypsum; S2. using the mixture of the treated phosphogypsum and β-type building gypsum for mine ecological reconstruction; The specific steps of step S2 are as follows: S2-1. After harmless phosphogypsum and β-type building gypsum are mixed evenly in proportion, they are transported to the surface of the mine and flattened, piled up and rolled to make the dry density ≥96%, thereby obtaining an ecological reconstruction base; S2-2. After harmless phosphogypsum and β-type building gypsum are mixed evenly in proportion, they are piled up on the surface of the ecological reconstruction base every 1 meter to form a protective layer; S2-3. The harmless phosphogypsum, β-type building gypsum, grass seeds, soil and water are mixed evenly in proportion and laid between the protective layers to obtain a vegetation growth layer; In the step S2-1, the mass ratio of phosphogypsum to β-type building gypsum is 3:1, in S2-2, the mass ratio of phosphogypsum to β-type building gypsum is 2:1, and the mass ratio of harmless phosphogypsum, β-type building gypsum, grass seeds, soil, and water is 2:1:1:1:1; The specific steps of the chemical treatment in step S1 are to sequentially add an alkaline regulator, a targeted solidification stabilizer, and an activator to the washed phosphogypsum, fully stir and mix them, and then store them for aging to obtain harmless phosphogypsum; The amount of the phosphogypsum, alkaline regulator, targeted solidification stabilizer and activator after water washing and deep purification is calculated as follows by weight: 100 parts of dry phosphogypsum, 0.5-1.5 parts of alkaline regulator, 1-2 parts of targeted solidification stabilizer, and 0.5-1.5 parts of activator; the alkaline regulator is carbide slag; the targeted solidification stabilizer is polyferric sulfate; the activator is fly ash; The phosphogypsum after water washing and deep purification has a water content of 18-25%, a pH value of 5.14, a water-soluble phosphorus content of 440 mg / L, and a water-soluble fluorine content of 29.36 mg / L; The stacking thickness in step S2-1 is 50 cm, and the laying thickness in step S2-3 is 20 cm.

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