Phosphogypsum pavement cushion material as well as preparation method and application thereof

Abstract

The invention discloses a phosphogypsum pavement cushion material as well as a preparation method and application thereof, and belongs to the technical field of road materials. The invention provides an ardealite pavement cushion material which is prepared from the following raw materials in parts by mass: 90-98 parts of pretreated ardealite, 2-10 parts of beta gypsum powder, 6 parts of a curing agent and 5-10 parts of water, the pretreated ardealite is prepared by carrying out pollution-free treatment on ardealite, and the beta gypsum powder is prepared by calcining ardealite at 130-160 DEG C; the preparation method is simple, more than 90% of the raw material is the phosphogypsum, the cost is low, the phosphogypsum pavement cushion material is easy to popularize, and meanwhile, the environmental pollution caused by wastes is reduced by reutilization of the phosphogypsum, so that the ecological environment is favorably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of road materials, and in particular relates to a phosphogypsum road surface cushion material and a preparation method and application thereof. Background Art

[0002] Phosphogypsum is a solid waste produced in the process of producing phosphoric acid. It contains certain organic phosphorus and inorganic phosphorus residues, which makes phosphogypsum acidic. In the current production process, about 4 tons of phosphogypsum are discharged for every ton of phosphoric acid produced. Phosphogypsum contains certain soluble P2O5 and F, which will produce acidic wastewater when leached with rainwater, and will leak into the ground for a long time, affecting groundwater and polluting the environment. Therefore, the main treatment method at present is to pile up the slag yard after anti-seepage treatment at a specific site, and collect the leached liquefaction for reuse. Year after year, the slag yard occupies a lot of land. At present, about 100 million tons of phosphogypsum are piled up in the phosphogypsum slag yard nationwide, occupying a lot of land. In recent years, due to the booming supply and demand of new energy lithium iron phosphate batteries, the output of phosphoric acid has continued to rise. As a result, the output of phosphogypsum has also continued to rise. According to relevant reports, the output of phosphogypsum in China in 2022 will be about 30 million tons, accounting for about 50% of the comprehensive utilization, and half of it will not be used. There are about 800 million tons of stockpiled phosphogypsum in the country. Making phosphogypsum into phosphogypsum-based road construction materials after harmless treatment is an important way to comprehensively utilize phosphogypsum. Summary of the invention

[0003] In view of the above-mentioned prior art, the present invention provides a phosphogypsum pavement cushion material and a preparation method and application thereof, which solves the problem that a large amount of phosphogypsum cannot be utilized.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: to provide a phosphogypsum pavement cushion material, comprising the following raw materials in parts by weight: 90 to 98 parts of pretreated phosphogypsum, 2 to 10 parts of beta gypsum powder, 6 parts of curing agent, and 5 to 10 parts of water;

[0005] The steps of preparing the pretreated phosphogypsum are as follows: mixing the phosphogypsum and quicklime in a mass ratio of 10:1, soaking in water for 36 hours, and then drying and sieving at 50-60° C. to obtain the pretreated phosphogypsum;

[0006] The preparation steps of β-gypsum powder are as follows: calcining phosphogypsum at 130-160° C. for 2-3 hours, and then grinding it through a 200-mesh sieve.

[0007] The beneficial effects of the present invention are as follows: the raw materials of the road surface cushion material disclosed by the present invention contain more than 90% phosphogypsum, which consumes a large amount of phosphogypsum. As an industrial by-product, the price of phosphogypsum is lower than that of traditional cushion raw materials (crushed stone, gravel, etc.), which can significantly reduce the cost of road construction and realize resource recycling, which is in line with the concept of sustainable development; and the recycling of phosphogypsum reduces the pollution of waste to the environment and helps to improve the ecological environment; the present invention first performs pollution-free pretreatment on the phosphogypsum, which can effectively reduce the pollution risk of the phosphogypsum, and the pollution-free treatment can remove most of the harmful impurities in the phosphogypsum, thereby improving the safety and stability of the product; the beta gypsum powder provides the function of a gelling agent, which bonds the raw materials together to form a cushion structure with certain strength and stability.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the moisture content of the pretreated phosphogypsum is less than 15%.

[0010] Furthermore, the particle size of the pretreated phosphogypsum is less than 30 mm.

[0011] Furthermore, the curing agent is an inorganic material curing agent.

[0012] The beneficial effect of adopting the further technical solution is that the density and strength of the road surface cushion layer can be improved.

[0013] The invention also discloses a method for preparing a phosphogypsum pavement cushion material, comprising the following steps:

[0014] S1: Mix β-gypsum powder, curing agent and water according to mass fractions to obtain a mixed solution;

[0015] S2: Stir the pretreated phosphogypsum and the mixed liquid at 30-50°C for 40-80 minutes to obtain the phosphogypsum pavement cushion material.

[0016] The beneficial effects of the present invention are as follows: the preparation method provided by the present invention has simple steps, is easy to promote, and has excellent industrial prospects.

[0017] The invention also discloses an application of the phosphogypsum pavement cushion material in the pavement structure.

[0018] Furthermore, the pavement structure is prepared by paving a 30 cm thick phosphogypsum pavement cushion material, a 20 cm thick base layer and a 20 cm thick cement concrete from bottom to top.

[0019] The beneficial effects of the present invention are as follows: compared with the traditional loose granular cushion layer, the phosphogypsum pavement cushion layer material used in the pavement structure has a higher cohesion, which can maintain the continuous and uniform load transfer function of the cushion layer, while the traditional loose granular material cushion layer has no cohesion. Under the action of external load, the cushion layer has particle movement, and the large particles are not close to the sticky particles, but are scattered, and the load transfer is uneven, so that the subbase or roadbed local stress concentration causes the roadbed to sink or the subbase to crack. The use of the phosphogypsum-based cushion layer can completely avoid the above-mentioned diseases, and the phosphogypsum pavement cushion layer material can significantly reduce the construction cost, and the phosphogypsum belongs to industrial waste residue, and a large amount of storage not only occupies land, but also pollutes the surrounding environment. Using it for the pavement cushion layer material realizes the resource utilization of solid waste, and at the same time, the research and development, production and application of the phosphogypsum pavement cushion layer material can bring positive social benefits; therefore, the application of the phosphogypsum pavement cushion layer material in the pavement structure has important practical significance and broad prospects. DETAILED DESCRIPTION

[0020] The specific implementation modes of the present invention are described in detail below with reference to the embodiments.

[0021] Example 1

[0022] A phosphogypsum pavement cushion material, the raw materials of which are calculated by weight: 95 parts of pretreated phosphogypsum, 5 parts of beta gypsum powder, 6 parts of LG-3 type phosphogypsum curing agent (inorganic curing agent), and 8 parts of water; wherein the pretreated phosphogypsum is prepared by the following steps: phosphogypsum and quicklime are mixed at a mass ratio of 10:1, and soaked in water for 36 hours, and then dried at 50°C to a water content of less than 15%, and passed through a sieve with an aperture of 30 mm to obtain the pretreated phosphogypsum.

[0023] Beta gypsum powder is prepared by the following steps:

[0024] The phosphogypsum was calcined at 150°C for 2.5 hours and then ground through a 200-mesh sieve.

[0025] The phosphogypsum pavement cushion material in this embodiment is prepared by the following steps:

[0026] S1: Mix β-gypsum powder, LG-3 type phosphogypsum curing agent and water to obtain a mixed solution;

[0027] S2: Mix the pretreated phosphogypsum with the mixed solution, and stir at 40°C for 60 minutes to obtain the phosphogypsum pavement cushion material.

[0028] Example 2

[0029] A phosphogypsum pavement cushion material, the raw materials of which are calculated by weight: 90 parts of pretreated phosphogypsum, 10 parts of beta gypsum powder, 6 parts of LG-3 type phosphogypsum curing agent (inorganic curing agent), and 5 parts of water; wherein the pretreated phosphogypsum is prepared by the following steps: phosphogypsum and quicklime are mixed in a mass ratio of 10:1, and soaked in water for 36 hours, and then dried at 60°C to a water content of less than 15%, and passed through a sieve with an aperture of 30 mm to obtain the pretreated phosphogypsum.

[0030] Beta gypsum powder is prepared by the following steps:

[0031] The phosphogypsum was calcined at 130°C for 3 hours and then ground through a 200-mesh sieve.

[0032] The phosphogypsum pavement cushion material in this embodiment is prepared by the following steps:

[0033] S1: Mix β-gypsum powder, LG-3 type phosphogypsum curing agent and water to obtain a mixed solution;

[0034] S2: Mix the pretreated phosphogypsum with the mixed solution, and stir at 30°C for 80 minutes to obtain the phosphogypsum pavement cushion material.

[0035] Example 3

[0036] A phosphogypsum pavement cushion material, the raw materials of which are calculated by weight: 98 parts of pretreated phosphogypsum, 2 parts of beta gypsum powder, 6 parts of LG-3 type phosphogypsum curing agent (inorganic curing agent), and 10 parts of water; wherein the pretreated phosphogypsum is prepared by the following steps: phosphogypsum and quicklime are mixed in a mass ratio of 10:1, and soaked in water for 36 hours, and then dried at 60°C to a water content of less than 15%, and passed through a sieve with an aperture of 30 mm to obtain the pretreated phosphogypsum.

[0037] Beta gypsum powder is prepared by the following steps:

[0038] The phosphogypsum was calcined at 160°C for 2 hours and then ground through a 200-mesh sieve.

[0039] The phosphogypsum pavement cushion material in this embodiment is prepared by the following steps:

[0040] S1: Mix β-gypsum powder, LG-3 type phosphogypsum curing agent and water to obtain a mixed solution;

[0041] S2: Stir the pretreated phosphogypsum and the mixed liquid at 50°C for 40 minutes to obtain the phosphogypsum pavement cushion material.

[0042] Comparative Example 1

[0043] A phosphogypsum pavement cushion material, the raw materials of which are calculated by weight: 95 parts of pretreated phosphogypsum, 6 parts of LG-3 type phosphogypsum curing agent (inorganic curing agent), and 8 parts of water; wherein the pretreated phosphogypsum is prepared by the following steps: phosphogypsum and quicklime are mixed in a mass ratio of 10:1, and soaked in water for 36 hours, and then dried at 60°C to a water content of less than 15%, and passed through a sieve with an aperture of 30 mm to obtain the pretreated phosphogypsum.

[0044] The phosphogypsum pavement cushion material in this comparative example is prepared by the following steps:

[0045] S1: Mix LG-3 phosphogypsum curing agent and water to obtain a mixed solution;

[0046] S2: Stir the pretreated phosphogypsum and the mixed liquid at 40°C for 60 minutes to obtain the phosphogypsum pavement cushion material.

[0047] Comparative Example 2

[0048] A phosphogypsum pavement cushion material, the raw materials of which are calculated by weight: 95 parts of pretreated phosphogypsum, 5 parts of beta gypsum powder, and 8 parts of water; wherein the pretreated phosphogypsum is prepared by the following steps: phosphogypsum and quicklime are mixed in a mass ratio of 10:1, and soaked in water for 36 hours, then dried at 50°C to a water content of less than 15%, and passed through a sieve with an aperture of 30 mm to obtain the pretreated phosphogypsum.

[0049] Beta gypsum powder is prepared by the following steps:

[0050] The phosphogypsum was calcined at 150°C for 2.5 hours and then ground through a 200-mesh sieve.

[0051] The phosphogypsum pavement cushion material in this comparative example is prepared by the following steps:

[0052] S1: Mix β-gypsum powder and water to obtain a mixed solution;

[0053] S2: Stir the pretreated phosphogypsum and the mixed liquid at 40°C for 60 minutes to obtain the phosphogypsum pavement cushion material.

[0054] Comparative Example 3

[0055] A phosphogypsum pavement cushion material, the raw materials of which are calculated by weight: 95 parts of phosphogypsum, 5 parts of beta gypsum powder, 6 parts of LG-3 type phosphogypsum curing agent (inorganic curing agent), and 8 parts of water; the beta gypsum powder is prepared by the following steps: calcining the phosphogypsum at 150° C. for 2.5 hours and grinding it through a 200-mesh sieve.

[0056] The phosphogypsum pavement cushion material in this comparative example is prepared by the following steps:

[0057] S1: Mix β-gypsum powder, LG-3 type phosphogypsum curing agent and water to obtain a mixed solution;

[0058] S2: Stir the phosphogypsum and the mixed liquid at 40°C for 60 minutes to obtain the phosphogypsum pavement cushion material.

[0059] Experimental Example 1

[0060] Performance test: The cushion materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were poured into a test mold, left to stand for 24 hours and then demolded. They were placed under standard conditions (20°C, humidity ≥ 90%) and cured to a predetermined age, and performance tests were performed. The test results are shown in Table 1.

[0061] Table 1 Performance parameters of cushion materials

[0062]

[0063] It can be seen from Table 1 that the 3d compressive strength and 7d compressive strength of the cushion materials prepared in Examples 1 to 3 are higher than those of the cushion materials prepared in Comparative Examples 1 to 3. The cushion materials prepared in Comparative Examples 1 to 2 have a much lower water stability coefficient than the cushion materials prepared in Examples 1 to 3 and Comparative Example 3 because one does not add β-gypsum powder and the other does not add a curing agent. However, the phosphogypsum in the raw material of the cushion material prepared in Comparative Example 3 has not been pretreated for pollution-free treatment, and its strength is lower than that of the cushion materials prepared in Examples 1 to 3, and it is easy to pollute the environment.

[0064] Experimental Example 2

[0065] Pavement application: 30cm thick phosphogypsum pavement cushion material, 20cm thick base and 20cm thick cement concrete were laid from bottom to top on the red clay roadbed as the experimental pavement structure type, and 30cm thick graded crushed stone cushion, 20cm thick base and 20cm thick cement concrete were laid from bottom to top on the red clay roadbed as the comparative pavement structure type; the subgrade deflection and deflection detection value of the two pavement structure types were tested, and the deflection was required to be less than 500, and the deflection detection value design requirement was 50. After testing, the subgrade deflection of the experimental pavement structure type was 260, and the deflection detection value was 39, which was qualified; the subgrade deflection of the comparative pavement structure type was 240, and the deflection detection value was 53, which was qualified. After the pavement was evaluated after one year of use, there were no cracks on the experimental pavement, but cracks occurred on the comparative pavement. The reason was that the graded crushed stone cushion layer was scattered, which was not conducive to load transfer.

[0066] Although the specific implementation of the present invention is described in detail in conjunction with the embodiments, it should not be understood as limiting the scope of protection of this patent. Within the scope described in the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A phosphogypsum pavement cushion material, characterized in that: The method comprises the following raw materials in parts by weight: 90 to 98 parts of pretreated phosphogypsum, 2 to 10 parts of beta gypsum powder, 6 parts of curing agent, and 5 to 10 parts of water; The pretreated phosphogypsum preparation step is: mixing phosphogypsum and quicklime in a mass ratio of 10:1, soaking in water for 36 hours, and then drying and sieving at 50-60° C. to obtain the pretreated phosphogypsum; The preparation steps of the beta gypsum powder are as follows: calcining phosphogypsum at 130-160° C. for 2-3 hours, and then grinding the phosphogypsum through a 200-mesh sieve.

2. The phosphogypsum pavement cushion material according to claim 1, characterized in that: The moisture content of the pretreated phosphogypsum is less than 15%.

3. The phosphogypsum pavement cushion material according to claim 1, characterized in that: The particle size of the pretreated phosphogypsum is less than 30 mm.

4. The phosphogypsum pavement cushion material according to claim 1, characterized in that: The curing agent is an inorganic curing agent.

5. The method for preparing the phosphogypsum pavement cushion material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1: Mix β-gypsum powder, curing agent and water according to mass fractions to obtain a mixed solution; S2: Mix the pretreated phosphogypsum with the mixed liquid, and stir at 30-50°C for 40-80 minutes to obtain the phosphogypsum pavement cushion material.

6. Use of the phosphogypsum pavement cushion material according to any one of claims 1 to 4 in the paving of pavement structures.

7. The use according to claim 6, characterized in that: The pavement structure is obtained by laying a 30 cm thick phosphogypsum pavement cushion material, a 20 cm thick base layer and a 20 cm thick cement concrete on the roadbed from bottom to top.

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