Phosphogypsum storage yard leachate impermeable material and preparation method thereof

Abstract

The invention discloses a phosphogypsum storage yard leachate anti-seepage material and a preparation method thereof, and belongs to the technical field of anti-seepage material preparation. The preparation method comprises the following steps: dissolving a polymer material in water to obtain a mixed solution A, and adding dried bentonite into the mixed solution A to obtain a turbid liquid; adding a catalyst and a cross-linking agent into the turbid liquid to obtain a mixed solution B; dissolving an initiator in water to form a mixed solution C, adding the mixed solution C into the mixed solution B, and uniformly stirring to obtain a viscous material; and drying the viscous material to constant weight, grinding, crushing, adding the semi-flexible copolymer, and uniformly mixing to obtain the phosphogypsum storage yard leachate impermeable material. The phosphogypsum storage yard leachate seepage-proofing material has the beneficial effects that the expansion performance of the prepared phosphogypsum storage yard leachate seepage-proofing material is greatly enhanced, the expansion index is about 4 times that of untreated original soil, and the unloaded expansion rate is increased by 3.5 times; the durability is remarkably improved, and the seepage-proofing function of the liner structure can be achieved under long-term complex conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of anti-seepage material preparation, and particularly relates to an anti-seepage material for phosphogypsum storage yard leachate and a preparation method thereof. Background Art

[0002] Phosphogypsum is a solid waste generated during the wet production of phosphoric acid. Its effective utilization methods are limited, and open-air storage is the main treatment method, with an annual storage volume of up to 450 million tons. The main component of phosphogypsum is calcium sulfate dihydrate. Its main body and water washing liquid are acidic. During long-term storage, it is easy to break through the anti-seepage layer at the bottom of the reservoir, penetrate into the underground soil layer and surrounding groundwater, and cause serious pollution and rock dissolution. Isolating phosphogypsum solid waste from the external environment in the phosphogypsum yard is a common protective disposal method. Its general structure is similar to that of a domestic waste landfill. Its covering system includes a green soil layer, a drainage layer, an anti-seepage layer, an exhaust layer, etc. Among them, the anti-seepage layer is an important component for blocking internal and external interference in the landfill. Its general structure is as follows: Figure 1 shown.

[0003] At present, most anti-seepage layers use geosynthetic liners (GCLs) instead of natural clay layers, with natural sodium-based bentonite as the core material. Bentonite materials have stable production, low permeability, and low cost, but they are often affected by various external factors during their service life, resulting in leakage problems. On the one hand, the anti-seepage liner structure of the phosphogypsum storage yard is subject to seasonal changes in rainfall and temperature, and the internal bentonite material often suffers from severe cracking and cracks that are difficult to heal, which is a direct manifestation of insufficient structural durability. This in turn causes a significant increase in the permeability coefficient of the anti-seepage system and leads to the failure of the anti-seepage system. On the other hand, the bentonite material in the anti-seepage liner structure of the phosphogypsum storage yard is easily affected by leachate rich in various polluting ions during its service life, resulting in a decrease in chemical compatibility. In other words, its salt resistance and durability are insufficient, and it cannot meet the anti-seepage and airtightness requirements of the landfill cover layer.

[0004] The reason natural sodium bentonite, used as an anti-seepage liner in phosphogypsum storage yards, causes these problems: sodium bentonite has excellent water absorption and expansion properties. It has a good cation exchange capacity, and the interlayer cations are primarily Na+. The negative charge generated by lattice substitution in montmorillonite requires the absorption of ions of opposite charge to balance the solution's charge. These oppositely charged ions exist in the solution as hydrated ions, and the negatively charged montmorillonite particles adsorb the hydrated cations to form an electrical double layer. The thickness of the double layer is inversely proportional to the square of the valence of the counterion. That is, high cation valence results in a thin hydration membrane and a low expansion ratio; low cation valence results in a thick hydration membrane and a high expansion ratio. However, under the action of acidic phosphogypsum leachate rich in various ions, the high-valent cations of the anti-seepage liner, on the one hand, are replaced from the high-concentration leachate to the low-concentration bentonite crystal layer structure under the action of concentration gradient. On the other hand, the high-valent cations have strong replacement ability, and under the same concentration conditions, they have a stronger binding effect with the surface of the internal structure between the bentonite layers, and are more likely to replace the Na+ in the natural bentonite structure, forming a new structure occupied by high-valent cations in the bentonite structure, thereby reducing the double layer thickness and hydration film thickness, and the expansion and anti-seepage effects become worse, making it impossible to achieve effective anti-seepage effect on phosphogypsum leachate, showing low durability and failure during service. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a phosphogypsum storage yard leachate anti-seepage material and a preparation method thereof. The invention aims to address the problem of insufficient anti-seepage durability caused by the continuous corrosion of polluted leachate during the service of traditional geosynthetic liner materials and clay materials as anti-seepage structures of phosphogypsum storage yards. The invention uses a variety of polymers to reinforce bentonite materials to enhance the erosion resistance and durability of the liner caused by the corrosion of polluted leachate, thereby solving at least one technical problem involved in the background technology.

[0006] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0007] An embodiment of the present invention provides a method for preparing an anti-seepage material for leachate from a phosphogypsum storage yard, comprising the following steps:

[0008] Step S1, dissolving 2 parts of sodium acrylate and polyacrylate polymer material in 4 parts of water by weight and stirring uniformly to obtain a mixed solution A, and then slowly adding 5 parts of dry bentonite to the mixed solution A and stirring uniformly to obtain a suspension;

[0009] Step S2, adding 1‰ of the catalyst by weight of the dry bentonite and 1-3% of the cross-linking agent by weight to the suspension and stirring uniformly to obtain a mixed solution B;

[0010] Step S3, dissolving an initiator accounting for 0.5‰ of the weight of the dry bentonite in water to form a mixed solution C, and adding the mixed solution C to the mixed solution B and stirring evenly, and after the reaction is completed, obtaining a viscous material;

[0011] Step S4: shearing and crushing the viscous material and drying it to a constant weight, grinding and crushing it, adding an appropriate amount of a semi-flexible copolymer of vinyl acetate and ethylene, and mixing them evenly to obtain a phosphogypsum storage yard leachate anti-seepage material.

[0012] Optionally, in step S1, the mass ratio of sodium acrylate to acrylate is 10:1.

[0013] Optionally, in step S2, the catalyst is selected from tetramethylethylenediamine and diethanolamine.

[0014] Optionally, in step S2, the cross-linking agent is N,N-methylenebisacrylamide.

[0015] Optionally, in step S3, the initiator is a mixture of potassium persulfate and sodium bisulfite, and the mass ratio of potassium persulfate to sodium bisulfite is 1:1.

[0016] Optionally, in step S4, an infrared tunnel oven is used for drying, the drying temperature is 220-240° C., and the drying time is 1-2 h.

[0017] Optionally, in step S4, the semi-flexible copolymer of vinyl acetate and ethylene accounts for 1‰ of the mass of the viscous material, and the mass ratio of vinyl acetate to ethylene is 1:1 to 1:3.

[0018] The invention provides a phosphogypsum storage yard leachate anti-seepage material, which is prepared by adopting the preparation method of the phosphogypsum storage yard leachate anti-seepage material.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) In order to solve the problem of insufficient anti-seepage durability of traditional geosynthetic liner materials and clay materials as anti-seepage structures of phosphogypsum storage yards caused by continuous corrosion of polluted leachate during service, the present invention uses a variety of polymers to reinforce bentonite materials to enhance the erosion resistance and durability of the liner caused by the corrosion of polluted leachate.

[0021] (2) In order to solve the problem of insufficient structural durability and cracking failure caused by seasonal changes and temperature changes during the service of traditional geosynthetic liner materials and clay materials as anti-seepage structures of phosphogypsum storage yards, the present invention uses a variety of polymers to reinforce bentonite materials to reduce the water loss shrinkage and freeze-thaw cracking of the liner structure caused by seasonal changes and temperature changes, and enhance the durability of the liner structure made of anti-seepage materials of phosphogypsum storage yard leachate.

[0022] (3) The expansion performance of the phosphogypsum storage leachate anti-seepage material prepared by the present invention is greatly enhanced, the expansion index (81 ml / 2 g) is about 4 times that of the untreated original soil (where the original soil is about 24 ml / 2 g), and the no-load expansion rate is increased by 3.5 times (where the no-load expansion rate of high-durability bentonite is 98%, while that of the original soil is only 28%).

[0023] (4) The durability of the phosphogypsum storage yard leachate anti-seepage material prepared by the present invention is significantly improved, and the anti-seepage function of the liner structure can be realized under long-term complex conditions (seasonal changes, temperature changes, leachate effects, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0025] Figure 1 A preparation flow chart of the method for preparing the anti-seepage material for phosphogypsum storage yard leachate provided by the present invention;

[0026] Figure 2 The image of the original bentonite after the dry-wet cycle provided by the present invention; wherein, Figure 2 (a) is the image of the original bentonite after one dry-wet cycle; Figure 2 (b) is the image of the original bentonite after three dry-wet cycles; Figure 2 (c) is the image of the original bentonite after 9 dry-wet cycles;

[0027] Figure 3 This is an image of the phosphogypsum storage leachate anti-seepage material provided by the present invention after 9 dry-wet cycles; wherein, Figure 3 (a) is an image of the anti-seepage material of the phosphogypsum storage yard leachate after 9 wet cycles; Figure 3 (b) is an image of the anti-seepage material of the phosphogypsum storage yard leachate after 9 dry cycles; Figure 3 (c) is the crack rate map of the anti-seepage material of the phosphogypsum storage site leachate after 9 wet cycles; Figure 3 (d) is the crack ratio diagram of the anti-seepage material of the phosphogypsum storage site leachate after 9 drying cycles;

[0028] Figure 4 This is a comparison chart of the permeability coefficients of the phosphogypsum storage leachate anti-seepage material provided by the present invention and the original swelling dry-wet cycle;

[0029] Figure 5This is a comparison chart of the permeability coefficients of the phosphogypsum storage yard leachate anti-seepage material provided by the present invention and the original swelling freeze-thaw cycle. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] The present invention provides a method for preparing an anti-seepage material for phosphogypsum storage yard leachate, comprising the following steps:

[0032] Step S1, dissolving 2 parts of sodium acrylate and polyacrylate polymer material in 4 parts of water by weight and stirring uniformly to obtain a mixed solution A, and then slowly adding 5 parts of dry bentonite to the mixed solution A and stirring uniformly to obtain a suspension;

[0033] Step S2, adding 1‰ of the catalyst by weight of the dry bentonite and 1-3% of the cross-linking agent by weight to the suspension and stirring uniformly to obtain a mixed solution B;

[0034] Step S3, dissolving an initiator accounting for 0.5‰ of the weight of the dry bentonite in water to form a mixed solution C, and adding the mixed solution C to the mixed solution B and stirring evenly, and after the reaction is completed, obtaining a viscous material;

[0035] Step S4: shearing and crushing the viscous material and drying it to a constant weight, grinding and crushing it, adding an appropriate amount of a semi-flexible copolymer of vinyl acetate and ethylene, and mixing them evenly to obtain a phosphogypsum storage yard leachate anti-seepage material.

[0036] It should be noted that, in step S1, the mass ratio of sodium acrylate to acrylate is 10:1.

[0037] In step S2, the catalyst is selected from tetramethylethylenediamine and diethanolamine, and the cross-linking agent is N,N-methylenebisacrylamide.

[0038] In step S3, the initiator is a mixture of potassium persulfate and sodium bisulfite, and the mass ratio of potassium persulfate to sodium bisulfite is 1:1.

[0039] In step S4, an infrared tunnel oven is used for drying at a temperature of 220-240° C. for 1-2 hours. The semi-flexible copolymer of vinyl acetate and ethylene accounts for 1‰ of the mass of the viscous material, and the mass ratio of vinyl acetate to ethylene is 1:1 to 1:3.

[0040] The invention provides a phosphogypsum storage yard leachate anti-seepage material, which is prepared by adopting the preparation method of the phosphogypsum storage yard leachate anti-seepage material.

[0041] The principle of the phosphogypsum storage yard leachate anti-seepage material provided by the present invention to resist the erosion of phosphogypsum leachate is that a polymer monomer material mainly composed of sodium acrylate at a specified concentration is introduced into the interlayer structure of a natural bentonite soil layer through an aqueous medium to form a uniform distribution, and an initiator material at an appropriate concentration is added to induce a polymerization reaction between the bentonite layers, forming a highly durable modified bentonite material with a soil layer structure and a polymer material tightly combined to resist the erosion of phosphogypsum leachate. During the process, the polymerization reaction process is expanded by a cross-linking agent and a catalyst that are easily hydrolyzed to form a three-dimensional spatial network structure, as shown in the following details:

[0042] (1) The strong intermolecular force provided by the polymer material mainly composed of sodium polyacrylate reduces the high-valent cation binding sites in the phosphogypsum leachate; the long polymer chain can connect with the hydroxyl (-OH) and other functional groups on the surface of the bentonite through hydrogen bonds, occupying the surface sites of the lamellar structure to form a stable bentonite structure. The strong force makes the modified bentonite structure more stable;

[0043] (2) A stable three-dimensional cross-linked network induced by a cross-linking agent; the water-soluble cross-linking agent can change the polymerization reaction process from a single chain growth reaction to a spatial cross-linked network that develops in a three-dimensional space. Under the ion exchange effect of the phosphogypsum leachate, the soil structure shrinkage effect is weak, and thus it has stronger water retention and structural stability than traditional long-chain polymer materials;

[0044] (3) Shielding effect on ions in phosphogypsum leachate; in phosphogypsum leachate, high-valent cations (Zn 2+ 、Cu 2 + , Ca 2+ etc.) will affect the original Na + The polymer network forms a composite and encapsulated structure with bentonite in the form of spatial cross-linking, and the Na + It forms an intermediate barrier with external high-valent cations to shield the direct erosion of some cations;

[0045] (4) Osmotic pressure regulation, cations in phosphogypsum leachate are directly +In addition to exchange, water molecules can also be affected by osmotic pressure balance, thereby causing erosion. Phosphogypsum leachate is rich in high-valent cations, with ion concentrations far higher than those within the soil structure. Under osmotic pressure regulation, water molecules within the soil structure continuously diffuse outward, causing the soil layer structure to shrink, leading to expansion and gradual loss of its anti-seepage effect. Polymer materials have strong water absorption and retention properties. Under the erosion of phosphogypsum leachate, they can still maintain a certain degree of water molecule content within the soil layer structure, maintaining osmotic pressure balance, and thus maintaining expansion and water-stopping effects, thereby achieving anti-erosion properties.

[0046] Among them, controlling the ratio of polymer monomers to soil and water can make the combination of bentonite and polymer most complete and the compound more compact. Through experiments, it was found that the ratio of polymer, water and soil is controlled to be 2:4:5. Too much water will cause the binding sites to migrate to the outside of the soil layer, resulting in a decrease in durability; the ratio control of cross-linking agent (N, N-methylenebisacrylamide), initiator (potassium persulfate, sodium bisulfite) and catalyst (tetramethylethylenediamine, diethanolamine) can make the polymer space network more complex, with sufficient guarantee of water absorption and retention capacity while exerting good expansion performance, mechanical strength and physical and chemical properties. In addition, the ratio and compounding effect of potassium persulfate and sodium bisulfite are as follows: potassium persulfate is the main initiator of the polymerization reaction, which can be decomposed into sulfate radicals (SO4 - ·) and potassium sulfate (K2SO4). Sulfate radicals are highly active free radicals that can generate free radicals by capturing hydrogen atoms in monomer molecules or undergoing addition reactions with monomer molecules, thereby initiating polymerization reactions. Their single use requires a relatively high ambient temperature. Sodium bisulfite is a reducing agent that can quickly lose electrons when in contact with potassium persulfate. This reduces the activation energy required for the decomposition of potassium persulfate through redox reactions, allowing the polymerization reaction to proceed effectively at lower temperatures. Experiments have shown that controlling the ratio of sodium bisulfite to 1:1 is most beneficial for inducing the composite of bentonite and polymers. Too much or too little will negatively affect the mechanical strength and water retention properties of the final polymer.

[0047] The phosphogypsum storage yard leachate anti-seepage material prepared by the present invention and the original bentonite were subjected to dry-wet cycle crack observation test, permeability test after dry-wet cycle, permeability coefficient test after freeze-thaw cycle, free expansion test, no-load expansion test and salt resistance durability test. The dry-wet cycle crack observation test adopts a high-definition camera to take pictures after each dry-wet cycle, grayscale processing and binarization processing, so that the pictures are converted into pictures with only black pixels and white pixels to calculate their surface crack rate. The permeability coefficient determination content refers to

[0048] The test was carried out according to Chapter 16 "Permeability Test" of the "Standard for Geotechnical Test Methods" (GBT 50123-2019). To make the test comparison results more significant, the permeability test was carried out using leachate from a phosphate mine in Hubei Province. The properties of the leachate are shown in Table 1.

[0049] Table 1 Chemical composition of phosphogypsum leachate

[0050]

[0051] Due to the significant expansion of phosphogypsum leachate-proofing materials, some tests were conducted using a mixture of phosphogypsum leachate-proofing materials and sand. Bentonite's expansion properties are a key indicator for evaluating its performance as an anti-seepage liner, so expansion-related indicators were used for calibration in the determination of salt resistance and durability. The no-load expansion rate was determined by referring to Chapter 4, "Specimen Preparation and Saturation," and Chapter 25, "Expansion Rate Test," of the "Standard for Geotechnical Test Methods" (GBT 50123-2019). The no-load expansion rate of bentonite-sand mixtures and bentonite-sand mixtures was determined. The free expansion test and salt resistance and durability test were conducted in accordance with the specification for sodium-bentonite waterproofing blankets (JG / T193-2006).

[0052] Comparison of crack ratios between anti-seepage materials for phosphogypsum storage site leachate and original bentonite after dry-wet cycles is shown in Table 2 and Figure 2 、 Figure 3 As shown in the figure: after 9 dry-wet cycles, the original bentonite material has a significant surface shrinkage phenomenon, and even an irreversible separation occurs between the edge of the sample and the mold. The crack rate is as high as 8.15%, which is 112% higher than the crack rate of the first dry-wet cycle. The performance after self-healing is poor. However, after 9 dry-wet cycles, the crack rate of the surface of the phosphogypsum landfill leachate anti-seepage material is only 0.08%. After rehydration and expansion, the cracks caused by drying shrinkage can still be fully healed. There is almost no change compared with the cracks after the first dry-wet cycle, and the self-healing performance is excellent. The permeability coefficients of the phosphogypsum landfill leachate anti-seepage material and the original bentonite under dry-wet cycles are shown in Tables 3 and 4. Figure 4 As shown in Table 4: The permeability coefficient under freeze-thaw cycle is shown in Table 4 and Figure 5As shown in Table 5, the permeability coefficient of the original bentonite material increases sharply with the number of dry-wet cycles and freeze-thaw cycles. After nine dry-wet cycles, the permeability coefficient increases by three orders of magnitude compared to the initial permeability coefficient, and after nine freeze-thaw cycles, the permeability coefficient increases by two orders of magnitude compared to the original permeability coefficient, indicating poor stability. In contrast, the permeability coefficient of the phosphogypsum landfill leachate anti-seepage material increases slightly with the number of dry-wet cycles and freeze-thaw cycles, with no significant order of magnitude change and strong stability. A comparison of the swelling properties and salt resistance durability of the phosphogypsum landfill leachate anti-seepage material and the original bentonite is shown. The no-load swelling rate, swelling index, and salt resistance durability of the phosphogypsum landfill leachate anti-seepage material increase by 250.0%, 237.5%, and 240.0%, respectively, compared to the original bentonite performance indicators, demonstrating significant improvements in swelling and salt resistance.

[0053] In summary, the phosphogypsum storage yard leachate anti-seepage material not only has the general anti-seepage function of general anti-seepage materials, but can also adapt to the necessary dry-wet cycle, seasonal freeze-thaw cycle and the erosion of phosphogypsum storage yard leachate rich in various ions without significant performance degradation. It is a new type of anti-seepage material that can meet the long-term anti-seepage requirements of the phosphogypsum storage yard area.

[0054] Table 2 Crack ratio of anti-seepage materials and original swelling dry-wet cycles of phosphogypsum storage yard leachate

[0055]

[0056] Table 3 Permeability coefficients of anti-seepage materials and original swelling dry-wet cycles of phosphogypsum storage leachate

[0057]

[0058] Table 4 Permeability coefficients of anti-seepage materials and original swelling materials under freeze-thaw cycles of phosphogypsum storage leachate

[0059]

[0060] Table 5 Swelling properties and durability of anti-seepage materials and original bentonite in phosphogypsum storage yard leachate

[0061]

[0062]

[0063] The phosphogypsum storage yard leachate anti-seepage material prepared by the present invention is described in detail with reference to specific Examples 1-3.

[0064] Example 1

[0065] Example 1 provides a method for preparing a phosphogypsum storage leachate anti-seepage material, comprising the following steps:

[0066] Step S1, dissolving 2 parts of sodium acrylate and polyacrylate polymer material in 4 parts of water by weight and stirring uniformly to obtain a mixed solution A, and then slowly adding 5 parts of dry bentonite to the mixed solution A and stirring uniformly to obtain a suspension;

[0067] Step S2, adding 1‰ of tetramethylethylenediamine and diethanolamine respectively to the weight of the dry bentonite and 1% of N,N-dimethylacrylamide to the suspension and stirring uniformly to obtain a mixed solution B;

[0068] Step S3, dissolving 0.5‰ of the weight of the dry bentonite in potassium sulfate and sodium bisulfite solid powder in water to form a mixed solution C, and adding the mixed solution C to the mixed solution B and stirring evenly, and after the reaction is completed, a viscous material is obtained;

[0069] Step S4: shearing and crushing the viscous material and drying it in an infrared tunnel oven at 220-240° C. for 1-2 hours to constant weight; grinding and crushing the viscous material, adding an appropriate amount of a semi-flexible copolymer of vinyl acetate and ethylene, and mixing the mixture evenly to obtain a phosphogypsum storage site leachate anti-seepage material.

[0070] The anti-seepage material for phosphogypsum storage yard leachate prepared in Example 1 was tested, and the results are shown in Table 6.

[0071] Table 6 Test results

[0072]

[0073]

[0074] Example 2

[0075] Example 2 provides a method for preparing a phosphogypsum storage leachate anti-seepage material, comprising the following steps:

[0076] Step S1, dissolving 2 parts of sodium acrylate and polyacrylate polymer material in 4 parts of water by weight and stirring uniformly to obtain a mixed solution A, and then slowly adding 5 parts of dry bentonite to the mixed solution A and stirring uniformly to obtain a suspension;

[0077] Step S2, adding 1‰ of tetramethylethylenediamine and diethanolamine respectively to the weight of the dry bentonite and 2% of N,N-dimethylacrylamide to the suspension and stirring uniformly to obtain a mixed solution B;

[0078] Step S3, dissolving 0.5‰ of the weight of the dry bentonite in potassium sulfate and sodium bisulfite solid powder in water to form a mixed solution C, and adding the mixed solution C to the mixed solution B and stirring evenly, and after the reaction is completed, a viscous material is obtained;

[0079] Step S4: shearing and crushing the viscous material and drying it in an infrared tunnel oven at 220-240° C. for 1-2 hours to constant weight; grinding and crushing the viscous material, adding an appropriate amount of a semi-flexible copolymer of vinyl acetate and ethylene, and mixing the mixture evenly to obtain a phosphogypsum storage site leachate anti-seepage material.

[0080] The anti-seepage material for phosphogypsum storage yard leachate prepared in Example 2 was tested, and the results are shown in Table 7.

[0081] Table 7 Test results

[0082]

[0083]

[0084] Example 3

[0085] Example 3 provides a method for preparing a phosphogypsum storage leachate anti-seepage material, comprising the following steps:

[0086] Step S1, dissolving 2 parts of sodium acrylate and polyacrylate polymer material in 4 parts of water by weight and stirring uniformly to obtain a mixed solution A, and then slowly adding 5 parts of dry bentonite to the mixed solution A and stirring uniformly to obtain a suspension;

[0087] Step S2, adding 1‰ of tetramethylethylenediamine and diethanolamine respectively to the weight of the dry bentonite and 3% of N,N-dimethylacrylamide to the suspension and stirring uniformly to obtain a mixed solution B;

[0088] Step S3, dissolving 0.5‰ of the weight of the dry bentonite in potassium sulfate and sodium bisulfite solid powder in water to form a mixed solution C, and adding the mixed solution C to the mixed solution B and stirring evenly, and after the reaction is completed, a viscous material is obtained;

[0089] Step S4: shearing and crushing the viscous material and drying it in an infrared tunnel oven at 220-240° C. for 1-2 hours to constant weight; grinding and crushing the viscous material, adding an appropriate amount of a semi-flexible copolymer of vinyl acetate and ethylene, and mixing the mixture evenly to obtain a phosphogypsum storage site leachate anti-seepage material.

[0090] The phosphogypsum storage yard leachate anti-seepage material prepared in Example 3 was tested, and the results are shown in Table 8.

[0091] Table 8 Test results

[0092]

[0093] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0094] Furthermore, it should be noted that the scope of the methods and systems of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in reverse order, depending on the functions involved. For example, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to certain examples may be combined in other examples.

[0095] The embodiments of the present invention are described above, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for preparing an anti-seepage material for phosphogypsum storage leachate, characterized in that: The steps include: Step S1, dissolving 2 parts of sodium acrylate and polyacrylate polymer material in 4 parts of water by weight and stirring uniformly to obtain a mixed solution A, and then slowly adding 5 parts of dry bentonite to the mixed solution A and stirring uniformly to obtain a suspension; Step S2, adding 1‰ of the catalyst by weight of the dry bentonite and 1-3% of the cross-linking agent by weight to the suspension and stirring uniformly to obtain a mixed solution B; Step S3, dissolving an initiator accounting for 0.5‰ of the weight of the dry bentonite in water to form a mixed solution C, and adding the mixed solution C to the mixed solution B and stirring evenly, and after the reaction is completed, obtaining a viscous material; Step S4: shearing and crushing the viscous material and drying it to a constant weight, grinding and crushing it, adding an appropriate amount of a semi-flexible copolymer of vinyl acetate and ethylene, and mixing them evenly to obtain a phosphogypsum storage yard leachate anti-seepage material.

2. The anti-seepage material for phosphogypsum storage yard leachate according to claim 1, characterized in that: In step S1, the mass ratio of sodium acrylate to acrylate is 10:

1.

3. The anti-seepage material for phosphogypsum storage yard leachate according to claim 1, characterized in that: In step S2, the catalyst is selected from tetramethylethylenediamine and diethanolamine.

4. The anti-seepage material for phosphogypsum storage yard leachate according to claim 1, characterized in that: In step S2, the cross-linking agent is N,N-methylenebisacrylamide.

5. The anti-seepage material for phosphogypsum storage yard leachate according to claim 1, characterized in that: In step S3, the initiator is a mixture of potassium persulfate and sodium bisulfite, and the mass ratio of potassium persulfate to sodium bisulfite is 1:

1.

6. The anti-seepage material for phosphogypsum storage yard leachate according to claim 1, characterized in that: In step S4, an infrared tunnel oven is used for drying at a temperature of 220-240° C. for 1-2 hours.

7. The anti-seepage material for phosphogypsum storage yard leachate according to claim 1, characterized in that: In step S4, the semi-flexible copolymer of vinyl acetate and ethylene accounts for 1‰ of the mass of the viscous material, and the mass ratio of vinyl acetate to ethylene is 1:1 to 1:

3.

8. A phosphogypsum storage yard leachate anti-seepage material, prepared by the preparation method of the phosphogypsum storage yard leachate anti-seepage material according to any one of claims 1 to 7.

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