Phosphogypsum modified road base material and filling forming process thereof

Abstract

The invention relates to the technical field of ardealite, in particular to an ardealite modified road base material and a filling forming process thereof, and the ardealite modified road base material comprises cement, a modifier, ardealite and a consolidation diagenetic powder curing agent. The method has the advantages that resources are effectively utilized, the overall performance of materials is improved, and stockpiling is reduced; the ardealite accounts for 85-90%, a large amount of ardealite which is an industrial waste can be consumed, land occupation and environmental pollution of ardealite are reduced, and effective utilization of resources is realized. The ardealite is soaked in an oxalic acid solution and treated in a filter reactor, so that dihydrate gypsum is converted into a semi-hydrate gypsum phase, and the performance of the ardealite is improved; the modifier realizes nanoscale dispersion through high-speed jet milling, so that the modifier can better play a role, and the overall performance of the material is improved; according to the three-stage mixing technology, all the components are fully mixed, steel fibers are added and arranged in an oriented mode, the strength and toughness of the material are enhanced, and it is ensured that no obvious caking phenomenon exists.

Description

Technical Field

[0001] This invention relates to the field of phosphogypsum technology, specifically to phosphogypsum-modified road base materials and their filling and molding process. Background Technology

[0002] Phosphogypsum is a solid waste generated during the wet process of phosphoric acid production. Large-scale accumulation not only occupies land resources but also causes serious environmental pollution. Applying phosphogypsum to road base materials can solve the problem of phosphogypsum disposal and reduce road construction costs, resulting in significant environmental and economic benefits.

[0003] Phosphogypsum is mostly disposed of through stockpiling, which occupies a large amount of land resources, forms slag heaps, seriously pollutes the environment, and poses safety hazards, such as triggering geological disasters like landslides. Traditional methods have a low comprehensive utilization rate of phosphogypsum, resulting in resource waste and failing to fully realize its potential value. Secondly, some existing technologies may produce road base materials with insufficient strength and poor durability, failing to meet the requirements for long-term use. Furthermore, existing materials may have poor adaptability to environmental factors, such as poor water resistance and frost resistance.

[0004] Therefore, there is an urgent need for phosphogypsum-modified road base materials and their filling and molding processes to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide phosphogypsum-modified road base material and its filling and molding process, which has the advantages of realizing effective resource utilization, improving the overall performance of the material, and reducing stockpiling, and solves the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: phosphogypsum modified road base material, comprising: cement, modifier, phosphogypsum, and compacted rock-forming powder curing agent.

[0007] Furthermore, as a preferred embodiment of the present invention, the cement accounts for 10-15%, the modifier accounts for 0.5%, the phosphogypsum accounts for 85-95%, and the solidified rock-forming powder curing agent accounts for 5-14%.

[0008] The filling and molding process of phosphogypsum-modified road base material in this invention includes two processes, the steps of which are as follows: Process 1: S1: Use 10-15% cement, 0.5% modifier, and 85-90% phosphogypsum; S2: Soak phosphogypsum in oxalic acid solution and stir for 30 minutes. After filtration, place it in a filter reactor to convert dihydrate gypsum into hemihydrate gypsum phase. Then, disperse 0.5% modifier at the nanoscale by high-speed airflow pulverization. S3: Three-stage hybrid Dry mixing stage: Premix the hemihydrate gypsum phase, cement and modifier in a twin-screw mixer for 2 minutes; Wet mixing stage: Spray in an aqueous solution containing 0.1% hydroxypropyl methylcellulose at a water temperature of 50°C and stir until the slurry fluidity reaches 180±5mm; Strengthening stage: Add steel fibers at a volume ratio of 1.5%, and mix them in a planetary mixer at a low speed of 30 rpm for 3 minutes to ensure that there is no obvious clumping. S4: Spread the mixed material onto the roadbed using a paver, and then compact it. S5: Compaction Initial compaction: A light roller is used to initially compact the paved mixture, with the rolling speed controlled at 1.5-2.0 km / h, and 2-3 passes are made to initially compact the mixture and make the surface smooth. Secondary compaction: Use a heavy roller for secondary compaction, with the rolling speed controlled at 2.5-3.5 km / h, and roll 4-6 times. During the compaction process, follow the principle of starting with light compaction and gradually increasing the speed, and starting from the edge and moving towards the center. Final compaction: A vibratory roller is used for final compaction, with the rolling speed controlled at 2.0-2.5 km / h, and 1-2 passes are made to eliminate wheel tracks and make the surface smoother. S6: After compaction, apply 80℃ saturated steam for 6 hours; then introduce CO2 for carbonization for 2 hours, and cover with a heat storage film for natural curing for 7 days.

[0009] Process 2: S1: Select 5-14% compacted rock-forming powder solidifier and 86-95% phosphogypsum; S2: The solidified rock powder was activated with 0.1% rare earth oxides in a vibratory mill for 30 minutes, and the particle size D50 was controlled at 8μm; phosphogypsum was ball-milled with 1% NaOH solution for 4 hours to form an amorphous silica-alumina gel coating layer. S3: The curing agent and phosphogypsum are placed into a two-stage co-rotating extruder. The temperature of the first stage is 80℃, which mainly completes the plasticization and preliminary mixing of the material. Then, the temperature of the second stage is 120℃, which promotes the interfacial reaction between the curing agent and phosphogypsum. Finally, the extrusion speed of the extruder screw is controlled at 0.5m / min to ensure that the material residence time is ≥3 minutes. A microwave source is used for 5 minutes of radiation to make the internal temperature of the material uniformly rise to 85℃. Medium-wave infrared radiation is used for 15 minutes to form a gradient curing structure at a surface temperature of 110 degrees Celsius. The molded body is impregnated in a tetraethyl orthosilicate-butyl titanate mixed sol, and after aging and drying, a SiO2-TiO2 composite film is formed. S4: Lay the composite membrane on the roadbed and then compact it. S5: Compaction Initial compaction: A pneumatic tire roller is used for initial compaction, with the rolling speed controlled at 2.0-2.5 km / h, and the roller is rolled 3-4 times to initially shape the mixture; Secondary compaction: Use a vibratory roller for secondary compaction, with the rolling speed controlled at 3.0-4.0 km / h, and roll 5-7 times; Final compaction: Use a steel wheel roller for final compaction, with the rolling speed controlled at 2.0-2.5 km / h, and roll 1-2 times to make the surface smooth and flat. S6: After compaction, cover the base layer with straw mats to keep it moist and cure for 10 days.

[0010] Furthermore, as a preferred embodiment of the present invention, in step S2 of the process, the ratio of phosphogypsum to oxalic acid solution is 3:1.

[0011] Furthermore, as a preferred embodiment of the present invention, in step S2 of the process, the 0.5% modifier is 0.3% triethanolamine + 0.2% nano-alumina.

[0012] Furthermore, as a preferred embodiment of the present invention, in step S6 of the process, the CO2 concentration is 30% and the pressure is 0.2 MPa.

[0013] Furthermore, as a preferred embodiment of the present invention, in step S2 of the second process, the ratio of phosphogypsum to NaOH solution is 1:2.

[0014] Furthermore, as a preferred embodiment of the present invention, in step S3 of the second process, after the mid-wave infrared radiation operation, the surface temperature of the material fluctuates by 2°C around 110°C.

[0015] Beneficial effects: The technical solution of this application has the following technical effects: This invention has the advantages of realizing the effective utilization of resources, improving the overall performance of materials, and reducing stockpiling.

[0016] The benefits of Process 1: With a phosphogypsum content of 85-90%, it can effectively utilize this industrial waste, reducing its land occupation and environmental pollution, thus achieving efficient resource utilization. By soaking phosphogypsum in oxalic acid solution and treating it in a filtered reactor, dihydrate gypsum is converted into hemihydrate gypsum, improving its performance. The modifier is nanoscale dispersed through high-speed airflow pulverization, allowing it to better exert its function and improve the overall material performance. The three-stage mixing process ensures thorough mixing of all components; the addition and directional arrangement of steel fibers enhances the material's strength and toughness, ensuring no significant agglomeration and improving its uniformity and stability. The use of light, heavy, and vibratory rollers for staged compaction, following the principles of starting with light rollers and gradually increasing speed, from the edges to the center, ensures good compaction of the mixture, guaranteeing the smoothness and compaction of the road base. The combination of 80℃ saturated steam curing, CO2 carbonization treatment, and natural curing with a heat-storing film helps improve the material's early strength and durability, promoting stable performance.

[0017] The beneficial effects of Process 2: With phosphogypsum comprising 86-95%, the comprehensive utilization rate of phosphogypsum is further improved, reducing the problem of phosphogypsum stockpiling; the activation of the solidified rock powder curing agent with rare earth oxides and the ball milling treatment of phosphogypsum with NaOH solution improve the performance of the curing agent and phosphogypsum respectively, forming an amorphous silica-alumina gel coating layer, which is beneficial to improving the material's reactivity and performance; the two-stage co-rotating extruder controls the temperature and screw extrusion speed in stages, combined with microwave source radiation and mid-wave infrared radiation, so that the internal temperature of the material rises uniformly and forms a gradient curing structure, improving the molding quality and performance of the material; the molded body is impregnated in a tetraethyl orthosilicate-tetrabutyl titanate mixed sol to form a SiO2-TiO2 composite film, enhancing the surface properties of the material, such as wear resistance and corrosion resistance; covering the base layer with straw mats to keep it moist for 10 days provides good conditions for the later strength growth and performance stability of the material. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of one step of the process of the present invention; Figure 2 This is a flowchart of the two-step process of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. To better understand the technical content of the present invention, specific embodiments are provided and described in conjunction with the accompanying drawings. Various aspects of the present invention are described in this disclosure with reference to the accompanying drawings, which illustrate numerous illustrative embodiments. It should be understood that the various concepts and embodiments described above, as well as those described in more detail below, can be implemented in any of many ways. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] As attached Figure 1 To be continued Figure 2 As shown: Example 1: Phosphogypsum-modified road base materials include: cement, modifier, phosphogypsum, and compacted rock-forming powder curing agent.

[0021] Specifically, the cement content is 10-15%, the modifier content is 0.5%, the phosphogypsum content is 85-95%, and the solidification agent for the compacted rock-forming powder content is 5-14%.

[0022] The filling and molding process of phosphogypsum-modified road base material in this invention includes two processes, the steps of which are as follows: Process 1: S1: 12% cement, 0.5% modifier, and 87.5% phosphogypsum are used. S2: Soak phosphogypsum in oxalic acid solution and stir for 30 minutes. After filtration, place it in a filter reactor to convert dihydrate gypsum into hemihydrate gypsum phase. Then, disperse 0.5% modifier at the nanoscale by high-speed airflow pulverization. S3: Three-stage hybrid Dry mixing stage: Premix the hemihydrate gypsum phase, cement and modifier in a twin-screw mixer for 2 minutes; Wet mixing stage: Spray in an aqueous solution containing 0.1% hydroxypropyl methylcellulose at a water temperature of 50°C and stir until the slurry fluidity reaches 180±5mm; Strengthening stage: Add steel fibers at a volume ratio of 1.5%, and mix them in a planetary mixer at a low speed of 30 rpm for 3 minutes to ensure that there is no obvious clumping. S4: Spread the mixed material onto the roadbed using a paver, and then compact it. S5: Compaction Initial compaction: A light roller is used to initially compact the paved mixture, with the rolling speed controlled at 1.5-2.0 km / h, and 2-3 passes are made to initially compact the mixture and make the surface smooth. Secondary compaction: Use a heavy roller for secondary compaction, control the rolling speed at 3km / h, and roll 4 times. During the compaction process, follow the principle of starting with light compaction and gradually increasing the speed, and starting from the edge and moving towards the center. Final compaction: A vibratory roller is used for final compaction, with the rolling speed controlled at 2 km / h and two passes to eliminate wheel tracks and make the surface smoother. S6: After compaction, apply 80℃ saturated steam for 6 hours; then introduce CO2 for carbonization for 2 hours, and cover with a heat storage film for natural curing for 7 days.

[0023] Process 2: S1: Use 8% compacted rock-forming powder solidifier and 92% phosphogypsum; S2: The solidified rock powder was activated with 0.1% rare earth oxides in a vibratory mill for 30 minutes, and the particle size D50 was controlled at 8μm; phosphogypsum was ball-milled with 1% NaOH solution for 4 hours to form an amorphous silica-alumina gel coating layer. S3: The curing agent and phosphogypsum are placed into a two-stage co-rotating extruder. The temperature of the first stage is 80℃, which mainly completes the plasticization and preliminary mixing of the material. Then, the temperature of the second stage is 120℃, which promotes the interfacial reaction between the curing agent and phosphogypsum. Finally, the extrusion speed of the extruder screw is controlled at 0.5m / min to ensure that the material residence time is ≥3 minutes. A microwave source is used for 5 minutes of radiation to make the internal temperature of the material uniformly rise to 85℃. Medium-wave infrared radiation is used for 15 minutes to form a gradient curing structure at a surface temperature of 110 degrees Celsius. The molded body is impregnated in a tetraethyl orthosilicate-butyl titanate mixed sol, and after aging and drying, a SiO2-TiO2 composite film is formed. S4: Lay the composite membrane on the roadbed and then compact it. S5: Compaction Initial compaction: A pneumatic tire roller is used for initial compaction, with the rolling speed controlled at 2.3 km / h, and the roller is rolled 3 times to initially shape the mixture; Secondary compaction: Use a vibratory roller for secondary compaction, with the rolling speed controlled at 3.5 km / h, and roll 6 times; Final compaction: A steel wheel roller is used for final compaction, with the rolling speed controlled at 2.0 km / h, and one pass is made to make the surface smooth and flat. S6: After compaction, cover the base layer with straw mats to keep it moist and cure for 10 days.

[0024] Specifically, in step S2 of the process, the ratio of phosphogypsum to oxalic acid solution is 3:1.

[0025] Specifically, in step S2 of the process, the 0.5% modifier is 0.3% triethanolamine + 0.2% nano alumina.

[0026] Specifically, in step S6 of the process, the CO2 concentration is 30% and the pressure is 0.2 MPa.

[0027] Specifically, in step S2 of the process, the ratio of phosphogypsum to NaOH solution is 1:2.

[0028] Specifically, in step S3 of the second process, after the mid-wave infrared radiation operation, the surface temperature of the material fluctuates by 2°C around 110°C.

[0029] Example 2: Phosphogypsum-modified road base materials include: cement, modifier, phosphogypsum, and compacted rock-forming powder curing agent.

[0030] Specifically, the cement content is 10-15%, the modifier content is 0.5%, the phosphogypsum content is 85-95%, and the solidification agent for the compacted rock-forming powder content is 5-14%.

[0031] The filling and molding process of phosphogypsum-modified road base material in this invention includes two processes, the steps of which are as follows: Process 1: S1: 10% cement, 0.5% modifier, and 89.5% phosphogypsum are used. S2: Soak phosphogypsum in oxalic acid solution and stir for 30 minutes. After filtration, place it in a filter reactor to convert dihydrate gypsum into hemihydrate gypsum phase. Then, disperse 0.5% modifier at the nanoscale by high-speed airflow pulverization. S3: Three-stage hybrid Dry mixing stage: Premix the hemihydrate gypsum phase, cement and modifier in a twin-screw mixer for 2 minutes; Wet mixing stage: Spray in an aqueous solution containing 0.1% hydroxypropyl methylcellulose at a water temperature of 50°C and stir until the slurry fluidity reaches 180±5mm; Strengthening stage: Add steel fibers at a volume ratio of 1.5%, and mix them in a planetary mixer at a low speed of 30 rpm for 3 minutes to ensure that there is no obvious clumping. S4: Spread the mixed material onto the roadbed using a paver, and then compact it. S5: Compaction Initial compaction: A light roller is used to initially compact the paved mixture, with the rolling speed controlled at 1.5-2.0 km / h, and 2-3 passes are made to initially compact the mixture and make the surface smooth. Secondary compaction: Use a heavy roller for secondary compaction, control the rolling speed at 3.5 km / h, and roll 3 times. During the compaction process, follow the principle of starting with light compaction and gradually increasing the speed, and starting from the edge and moving towards the center. Final compaction: A vibratory roller is used for final compaction, with the rolling speed controlled at 2.5 km / h, and one pass is made to eliminate wheel tracks and make the surface smoother. S6: After compaction, apply 80℃ saturated steam for 6 hours; then introduce CO2 for carbonization for 2 hours, and cover with a heat storage film for natural curing for 7 days.

[0032] Process 2: S1: Select 6% compacted rock-forming powder solidifier and 94% phosphogypsum; S2: The solidified rock powder was activated with 0.1% rare earth oxides in a vibratory mill for 30 minutes, and the particle size D50 was controlled at 8μm; phosphogypsum was ball-milled with 1% NaOH solution for 4 hours to form an amorphous silica-alumina gel coating layer. S3: The curing agent and phosphogypsum are placed into a two-stage co-rotating extruder. The temperature of the first stage is 80℃, which mainly completes the plasticization and preliminary mixing of the material. Then, the temperature of the second stage is 120℃, which promotes the interfacial reaction between the curing agent and phosphogypsum. Finally, the extrusion speed of the extruder screw is controlled at 0.5m / min to ensure that the material residence time is ≥3 minutes. A microwave source is used for 5 minutes of radiation to make the internal temperature of the material uniformly rise to 85℃. Medium-wave infrared radiation is used for 15 minutes to form a gradient curing structure at a surface temperature of 110 degrees Celsius. The molded body is impregnated in a tetraethyl orthosilicate-butyl titanate mixed sol, and after aging and drying, a SiO2-TiO2 composite film is formed. S4: Lay the composite membrane on the roadbed and then compact it. S5: Compaction Initial compaction: A pneumatic tire roller is used for initial compaction, with the rolling speed controlled at 2.0 km / h, and the roller is rolled 4 times to initially shape the mixture; Secondary compaction: Secondary compaction is carried out using a vibratory roller, with the rolling speed controlled at 0 km / h, and 7 passes. Final compaction: A steel wheel roller is used for final compaction, with the rolling speed controlled at 2.4 km / h, and two passes are made to make the surface smooth and flat. S6: After compaction, cover the base layer with straw mats to keep it moist and cure for 10 days.

[0033] Specifically, in step S2 of the process, the ratio of phosphogypsum to oxalic acid solution is 3:1.

[0034] Specifically, in step S2 of the process, the 0.5% modifier is 0.3% triethanolamine + 0.2% nano alumina.

[0035] Specifically, in step S6 of the process, the CO2 concentration is 30% and the pressure is 0.2 MPa.

[0036] Specifically, in step S2 of the process, the ratio of phosphogypsum to NaOH solution is 1:2.

[0037] Specifically, in step S3 of the second process, after the mid-wave infrared radiation operation, the surface temperature of the material fluctuates by 2°C around 110°C.

[0038] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0039] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A phosphogypsum-modified road base material, characterized in that: include: Cement, modifier, phosphogypsum, and solidification agent for compacted rock-forming powder.

2. The phosphogypsum-modified road base material according to claim 1, characterized in that: The cement accounts for 10-15%, the modifier accounts for 0.5%, the phosphogypsum accounts for 85-95%, and the compacted rock-forming powder curing agent accounts for 5-14%.

3. The filling and molding process for phosphogypsum-modified road base material according to any one of claims 1-2, characterized in that: It includes two processes, and the steps are as follows: Process 1: S1: Use 10-15% cement, 0.5% modifier, and 85-90% phosphogypsum; S2: Soak phosphogypsum in oxalic acid solution and stir for 30 minutes. After filtration, place it in a filter reactor to convert dihydrate gypsum into hemihydrate gypsum phase. Then, disperse 0.5% modifier at the nanoscale by high-speed airflow pulverization. S3: Three-stage hybrid Dry mixing stage: Premix the hemihydrate gypsum phase, cement and modifier in a twin-screw mixer for 2 minutes; Wet mixing stage: Spray in an aqueous solution containing 0.1% hydroxypropyl methylcellulose at a water temperature of 50°C and stir until the slurry fluidity reaches 180±5mm; Strengthening stage: Add steel fibers at a volume ratio of 1.5%, and mix them in a planetary mixer at a low speed of 30 rpm for 3 minutes to ensure that there is no obvious clumping. S4: Spread the mixed material onto the roadbed using a paver, and then compact it. S5: Compaction Initial compaction: A light roller is used to initially compact the paved mixture, with the rolling speed controlled at 1.5-2.0 km / h, and 2-3 passes are made to initially compact the mixture and make the surface smooth. Secondary compaction: Use a heavy roller for secondary compaction, with the rolling speed controlled at 2.5-3.5 km / h, and roll 4-6 times. During the compaction process, follow the principle of starting with light compaction and gradually increasing the speed, and starting from the edge and moving towards the center. Final compaction: A vibratory roller is used for final compaction, with the rolling speed controlled at 2.0-2.5 km / h, and 1-2 passes are made to eliminate wheel tracks and make the surface smoother. S6: After compaction, apply 80℃ saturated steam for 6 hours; then introduce CO2 for carbonization for 2 hours, and cover with a heat storage film for natural curing for 7 days. Process 2: S1: Select 5-14% compacted rock-forming powder solidifier and 86-95% phosphogypsum; S2: The solidified rock powder was activated with 0.1% rare earth oxides in a vibratory mill for 30 minutes, and the particle size D50 was controlled at 8μm; phosphogypsum was ball-milled with 1% NaOH solution for 4 hours to form an amorphous silica-alumina gel coating layer. S3: The curing agent and phosphogypsum are placed into a two-stage co-rotating extruder. The temperature of the first stage is 80℃, which mainly completes the plasticization and preliminary mixing of the material. Then, the temperature of the second stage is 120℃, which promotes the interfacial reaction between the curing agent and phosphogypsum. Finally, the extruder screw speed is controlled at 0.5m / min to ensure that the material residence time is ≥3 minutes. A microwave source is used for 5 minutes of radiation to make the internal temperature of the material uniformly rise to 85℃. Medium-wave infrared radiation is used for 15 minutes to form a gradient curing structure at a surface temperature of 110 degrees Celsius. The molded body is immersed in a tetraethyl orthosilicate-butyl titanate mixed sol, and after aging and drying, a SiO2-TiO2 composite film is formed. S4: Lay the composite membrane on the roadbed and then compact it; S5: Compaction Initial compaction: A pneumatic tire roller is used for initial compaction, with the rolling speed controlled at 2.0-2.5 km / h, and the roller is rolled 3-4 times to initially shape the mixture; Secondary compaction: Use a vibratory roller for secondary compaction, with the rolling speed controlled at 3.0-4.0 km / h, and roll 5-7 times; Final compaction: Use a steel wheel roller for final compaction, with the rolling speed controlled at 2.0-2.5 km / h, and roll 1-2 times to make the surface smooth and flat. S6: After compaction, cover the base layer with straw mats to keep it moist and cure for 10 days.

4. The filling and molding process of the phosphogypsum-modified road base material according to claim 3, characterized in that: In step S2 of the process, the ratio of phosphogypsum to oxalic acid solution is 3:

1.

5. The filling and molding process of the phosphogypsum-modified road base material according to claim 3, characterized in that: In step S2 of the process, the 0.5% modifier is 0.3% triethanolamine + 0.2% nano-alumina.

6. The filling and molding process of the phosphogypsum-modified road base material according to claim 3, characterized in that: In step S6 of the process, the CO2 concentration is 30% and the pressure is 0.2 MPa.

7. The filling and molding process of the phosphogypsum-modified road base material according to claim 3, characterized in that: In step S2 of the process, the ratio of phosphogypsum to NaOH solution is 1:

2.

8. The filling and molding process of the phosphogypsum-modified road base material according to claim 3, characterized in that: In step S3 of the process, after the mid-wave infrared radiation operation, the surface temperature of the material fluctuates by 2°C around 110°C.

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