Composite exciting agent based on phosphogypsum as well as preparation method and application of composite exciting agent

Abstract

The invention discloses a composite activator based on phosphogypsum as well as a preparation method and application thereof. The composite activator comprises the following raw materials in parts by weight: 50-70 parts of phosphogypsum, 5-15 parts of an alkaline activator, 10-20 parts of fly ash, 5-10 parts of slag powder, 0.5-1 part of a retarder, 0.5-1 part of a water reducer, 0.3-0.7 part of an organic silicon additive and 1-3 parts of expanded vermiculite. The preparation method has the advantage of high efficiency, and solves the problems that the automation degree is low in the preparation process of an existing phosphogypsum composite exciting agent, the steps of raw material weighing, mixing, water adding, filtering, forming and the like need to depend on manual operation, operation delay or unsmooth flow linkage is likely to occur, and the overall production period is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of material recycling, and in particular to a composite activator based on phosphogypsum, a preparation method thereof, and an application thereof. Background Art

[0002] Phosphogypsum is a solid waste generated during the wet-process phosphoric acid production process. Its primary component is calcium sulfate dihydrate, accounting for 70%-90% of the total waste. While it holds significant value in industry, agriculture, and environmental protection, improper handling can also pose environmental risks. Phosphogypsum-based composite activators are a combination of multiple activators added during the phosphogypsum preparation process to promote hydration, improve mechanical properties, and enhance durability. These activators typically include alkaline materials, slag, steel slag, lime, and stone powder. Their synergistic effect optimizes the activity of the phosphogypsum, accelerating the hydration process and forming a stable hydrated product.

[0003] The existing phosphogypsum composite activator has a low degree of automation in the preparation process. Steps such as raw material weighing, mixing, adding water, filtering, and molding require manual operation, which is prone to operational delays or poor process connections, resulting in an extension of the overall production cycle. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite activator based on phosphogypsum, and its preparation method and application, which has the advantage of high efficiency and solves the problem that the existing phosphogypsum composite activator has a low degree of automation in the preparation process, and the steps such as raw material weighing, mixing, adding water, filtering, and molding need to rely on manual operation, which is prone to operation delays or poor process connection, resulting in an extension of the overall production cycle.

[0005] To achieve the above object, the present invention provides the following technical solution: a composite activator based on phosphogypsum, comprising the following raw materials in parts by weight:

[0006] 50-70 parts of phosphogypsum, 5-15 parts of alkaline activator, 10-20 parts of fly ash, 5-10 parts of slag powder, 0.5-1 part of retarder, 0.5-1 part of water reducer, 0.3-0.7 part of organosilicon additive, and 1-3 parts of expanded vermiculite.

[0007] A method for preparing a composite activator based on phosphogypsum comprises the following steps:

[0008] S1. Raw material pretreatment: pretreatment of phosphogypsum, fly ash, slag powder and expanded vermiculite;

[0009] S2, dry material mixing, the treated phosphogypsum, fly ash, slag powder and expanded vermiculite are weighed and proportioned by weight, and the phosphogypsum is first dry-mixed with the fly ash and slag powder for 2-3 minutes using a mixing equipment, and then the expanded vermiculite is added and the mixing is continued for 3-5 minutes;

[0010] S3. Additive mixing: mixing retarder, water reducer and organosilicon additive in proportion to prepare liquid additive for standby use;

[0011] S4, wet mixing, pouring the mixed dry materials into a blender, slowly adding alkaline activator and water during the mixing process and stirring evenly to form a slurry, and then mixing additives into the slurry to improve the fluidity of the slurry and reduce its water absorption rate;

[0012] S5, filtering, pouring the prepared slurry into a filtering device, and filtering the slurry to remove agglomerated particles;

[0013] S6, forming and screening, feeding the slurry into the screw extruder, adjusting the screw speed and pressure, so that the slurry is extruded into strips from the die hole, and using a high-frequency cutting knife to cut the extruded strips into particles;

[0014] S7, drying and solidification, pouring the composite activator particles into a fluidized bed for drying, and the fluidized bed suspends and dries the particles through air flow.

[0015] As a preferred method for preparing a composite activator based on phosphogypsum of the present invention, when pre-treating the phosphogypsum, fly ash and slag powder, the phosphogypsum, fly ash and slag powder are first crushed using a crushing equipment, and then the crushed materials are dried.

[0016] As a preferred method for preparing a composite activator based on phosphogypsum of the present invention, when treating expanded vermiculite, the expanded vermiculite is calcined at 800-1000° C. for 30-60 minutes to form a porous structure, thereby improving the volume stability and water absorption rate control capability.

[0017] As a preferred preparation method of a composite activator based on phosphogypsum of the present invention, the mixing equipment is a U-shaped high-efficiency asymmetric mixer, which includes a U-shaped trough body, and an inner spiral blade and an outer spiral blade are provided inside the U-shaped trough body. The inner spiral blade and the outer spiral blade operate in an asymmetric manner, and an external driving component drives the inner spiral blade and the outer spiral blade to rotate inside the U-shaped trough body. The inner spiral blade pushes the material from the middle to the two ends, and the outer spiral blade pushes the material from the two ends to the middle, so that the material forms a complex flow pattern in the trough body, thereby promoting mutual penetration and dispersion between materials.

[0018] As a preferred method for preparing a composite activator based on phosphogypsum of the present invention, a retarder, a water reducer and an organosilicon additive are mixed in proportion to prepare a liquid additive for standby use. A predetermined amount of water is first added to a container, and then the retarder is slowly added while continuously stirring to ensure that the retarder is completely dissolved in the water. After the retarder is fully dissolved, the water reducer is continued to be added while stirring to ensure that it is evenly dispersed throughout the solution. Finally, the organosilicon additive is added and stirring is also maintained until the entire solution becomes uniform. During the stirring process, a mechanical stirrer is used to thoroughly stir the mixture. The recommended stirring speed is 300-600 rpm and the time is 5-10 minutes so that all the ingredients can be fully integrated. After the stirring is completed, an ultrasonic processor is used to further improve the homogeneity of the mixture. Finally, the pH value of the mixed liquid additive is measured.

[0019] As a preferred method for preparing a composite activator based on phosphogypsum of the present invention, the mixer is a planetary mixer, which includes a mixing container. A mixing paddle is installed inside the mixing container. The mixing paddle rotates inside the mixing container while performing an orbital motion around the inside of the mixing container. During the orbital motion, an auxiliary scraper on the surface of the mixing paddle cleans the inside of the mixing container.

[0020] As a preferred preparation method of a composite activator based on phosphogypsum of the present invention, the filtering equipment is a vibrating screen filter, which includes a stainless steel screen, a vibrating motor and an elastic support frame. The slurry enters the screen surface of the stainless steel screen through the feed inlet, and the vibrating motor drives the screen surface to vibrate at high frequency, so that the slurry is evenly spread and quickly screened. The agglomerated particles are intercepted above the screen surface and discharged through the slag outlet. The fine slurry passes through the screen and is collected from below.

[0021] As a preferred method for preparing a composite activator based on phosphogypsum of the present invention, a screw extruder includes a feeding system, a driving system, a heating and cooling system and a mold. The feeding system accommodates the slurry to be processed and ensures that the material can smoothly enter the extruder. The driving system provides a power source to drive the screw to rotate. The screw rotates inside the extruder to pressurize and convey the slurry. The heating and cooling system is coated on the surface of the screw extruder and is equipped with an electric heating ring or a water cooling system to maintain the extrusion temperature required for the slurry. The mold is located at the end of the extruder and is provided with a plurality of evenly distributed small holes. The slurry is extruded and formed from the small holes.

[0022] The invention discloses an application of a composite activator based on phosphogypsum. The composite activator based on phosphogypsum is applied to building materials, soil remediation materials and pollutant treatment materials.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention can efficiently activate the hydration reaction of calcium sulfate through the synergistic effect of phosphogypsum and alkaline activator, generating dense hydration products such as ettringite and CSH gel, significantly improving the early and late compressive strength of the material. The co-addition of fly ash and slag powder not only supplements active aluminum and silicon elements, but also further optimizes the pore structure through the alkali-activated reaction, thereby enhancing durability. The combination of retarder and water reducer can accurately control the setting time and fluidity, avoiding premature hardening or segregation problems. The organosilicon additive significantly reduces the water absorption rate through hydrophobic treatment. At the same time, the introduction of expanded vermiculite compensates for material shrinkage and improves volume stability. Ultimately, this formula achieves high-value utilization of phosphogypsum while ensuring mechanical properties and water resistance, reducing storage pollution, and achieving both economic benefits and environmental value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart of the preparation method of the present invention. DETAILED DESCRIPTION

[0026] Example 1

[0027] A composite activator based on phosphogypsum, comprising the following raw materials in parts by weight:

[0028] 50-70 parts of phosphogypsum, 5-15 parts of alkaline activator, 10-20 parts of fly ash, 5-10 parts of slag powder, 0.5-1 part of retarder, 0.5-1 part of water reducer, 0.3-0.7 part of organosilicon additive, and 1-3 parts of expanded vermiculite.

[0029] Furthermore, the alkaline activator is sodium hydroxide or calcium oxide.

[0030] Furthermore, the retarder is triethanolamine.

[0031] Further, water reducing agent calcium lignin sulfonate.

[0032] Through the synergistic effect of phosphogypsum and alkaline activators, the hydration reaction of calcium sulfate can be efficiently activated to generate dense hydration products such as calcium sulfonate and CSH gel, significantly improving the early and late compressive strength of the material. The co-addition of fly ash and slag powder not only supplements the active aluminum and silicon elements, but also further optimizes the pore structure through alkali activation reaction and enhances durability. The combination of retarder and water reducer can precisely control the setting time and fluidity to avoid premature hardening or segregation problems. The silicone additive significantly reduces the water absorption rate through hydrophobic treatment. At the same time, the introduction of expanded vermiculite compensates for material shrinkage and improves volume stability. Ultimately, this formula achieves high-value utilization of phosphogypsum while ensuring mechanical properties and water resistance, reduces storage pollution, and has both economic benefits and environmental value.

[0033] Example 2

[0034] See also Figure 1A method for preparing a composite activator based on phosphogypsum comprises the following steps:

[0035] S1. Raw material pretreatment: pretreatment of phosphogypsum, fly ash, slag powder and expanded vermiculite;

[0036] S2, dry material mixing, the treated phosphogypsum, fly ash, slag powder and expanded vermiculite are weighed and proportioned by weight, and the phosphogypsum is first dry-mixed with the fly ash and slag powder for 2-3 minutes using a mixing equipment, and then the expanded vermiculite is added and the mixing is continued for 3-5 minutes;

[0037] S3. Additive mixing: mixing retarder, water reducer and organosilicon additive in proportion to prepare liquid additive for standby use;

[0038] S4, wet mixing, pouring the mixed dry materials into a blender, slowly adding alkaline activator and water during the mixing process and stirring evenly to form a slurry, and then mixing additives into the slurry to improve the fluidity of the slurry and reduce its water absorption rate;

[0039] S5, filtering, pouring the prepared slurry into a filtering device, and filtering the slurry to remove agglomerated particles;

[0040] S6, forming and screening, feeding the slurry into the screw extruder, adjusting the screw speed and pressure, so that the slurry is extruded into strips from the die hole, and using a high-frequency cutting knife to cut the extruded strips into particles;

[0041] S7, drying and solidification, pouring the composite activator particles into a fluidized bed for drying, and the fluidized bed suspends and dries the particles through air flow.

[0042] Furthermore, when pre-treating the phosphogypsum, fly ash and slag powder, the phosphogypsum, fly ash and slag powder are firstly crushed using crushing equipment, and then the crushed materials are dried.

[0043] Furthermore, when the expanded vermiculite is processed, the expanded vermiculite is calcined at 800-1000° C. for 30-60 minutes to form a porous structure, thereby improving the volume stability and the water absorption rate control capability.

[0044] Furthermore, the mixing equipment is a U-shaped high-efficiency asymmetric mixer, which includes a U-shaped trough body. The U-shaped trough body is equipped with inner spiral blades and outer spiral blades. The inner spiral blades and outer spiral blades operate in an asymmetric manner. The external driving component drives the inner spiral blades and outer spiral blades to rotate inside the U-shaped trough body. The inner spiral blades push the material from the middle to both ends, and the outer spiral blades push the material from both ends to the middle, so that the material forms a complex flow pattern in the trough body, promoting mutual penetration and dispersion between materials.

[0045] Furthermore, the retarder, water reducer and silicone additive are mixed in proportion to prepare a liquid additive for use. A predetermined amount of water is first added to a container, and then the retarder is slowly added while continuously stirring to ensure that the retarder is completely dissolved in the water. After the retarder is fully dissolved, the water reducer is added while continuing to stir to ensure that it is evenly dispersed throughout the solution. Finally, the silicone additive is added and stirring is continued until the entire solution becomes uniform. During the stirring process, a mechanical stirrer is used to thoroughly stir the mixture. The recommended stirring speed is 300-600 rpm and the time is 5-10 minutes to allow all the ingredients to be fully integrated. After the stirring is completed, an ultrasonic processor is used to further improve the homogeneity of the mixture. Finally, the pH value of the mixed liquid additive is measured.

[0046] Furthermore, the mixer is a planetary mixer, which includes a mixing container with a stirring paddle installed inside the mixing container. The stirring paddle rotates inside the mixing container while revolving around the inside of the mixing container. During the revolving motion, the auxiliary scraper on the surface of the stirring paddle cleans the inside of the mixing container.

[0047] Furthermore, the filtering equipment is a vibrating screen filter, which includes a stainless steel screen, a vibrating motor and an elastic support frame. The slurry enters the screen surface of the stainless steel screen through the feed inlet, and the vibrating motor drives the screen surface to vibrate at high frequency, so that the slurry is evenly spread and quickly screened. The agglomerated particles are intercepted above the screen surface and discharged through the slag outlet. The fine slurry passes through the screen and is collected from below.

[0048] Furthermore, the screw extruder includes a feeding system, a driving system, a heating and cooling system and a mold. The feeding system accommodates the slurry to be processed and ensures that the material can enter the extruder smoothly. The driving system provides a power source to drive the screw to rotate. The screw rotates inside the extruder to pressurize and transport the slurry. The heating and cooling system is coated on the surface of the screw extruder and is equipped with an electric heating ring or a water cooling system to maintain the extrusion temperature required for the slurry. The mold is located at the end of the extruder and has multiple evenly distributed small holes on the mold. The slurry is extruded and formed from the small holes.

[0049] Through systematic raw material pretreatment and mixing process optimization, the performance and production efficiency of the composite activator have been significantly improved. First, in the raw material pretreatment stage, phosphogypsum, fly ash and slag powder are crushed and dried, which effectively improves the specific surface area and reaction activity of the materials. At the same time, the expanded vermiculite is calcined at high temperature to form a porous structure, which enhances its volume stability and water absorption rate control ability. In the dry material mixing link, a U-shaped high-efficiency asymmetric mixer is used. The counter-rotating design of the inner and outer spiral blades realizes three-dimensional mixing of the materials, solves the problem of mixing dead corners that are prone to occur in traditional mixing equipment, and ensures the uniformity of dry materials. In the wet mixing stage, the synergistic effect of the revolution and rotation of the planetary mixer is combined with the step-by-step water addition and alkaline activator addition strategy to significantly improve the fluidity and homogeneity of the slurry. At the same time, the water absorption rate of the slurry is further reduced through the scientific ratio of retarder, water reducer and silicone additive.

[0050] In the molding and post-processing stages, this technical solution achieves high-quality and efficient preparation of composite stimulants through innovative design of key equipment and precise control of process parameters. The screw extruder dynamically adjusts the screw speed and pressure, combined with the refined design of the mold aperture, so that the slurry is accurately formed into strips and cut into uniform particles by a high-frequency cutting knife to ensure the consistency of product particle size. The introduction of a vibrating screen filter effectively filters out agglomerated particles in the slurry, ensuring the purity of the slurry and the subsequent molding quality. In addition, the fluidized bed drying process greatly shortens the drying time and improves the stability of the particles through air flow suspension drying technology, avoiding the performance degradation that may be caused by traditional drying methods. The overall process flow is optimized through collaborative optimization between equipment, which not only reduces energy consumption and production costs, but also significantly improves the mechanical properties and durability of the composite stimulant.

[0051] Example 3

[0052] The invention discloses an application of a composite activator based on phosphogypsum. The composite activator based on phosphogypsum is applied to building materials, soil remediation materials and pollutant treatment materials.

[0053] Traditional phosphogypsum storage occupies land resources and may leak pollutants such as fluorine and phosphorus. By converting it into building materials through composite activators, high-dosage utilization can be achieved and storage pressure can be reduced. Composite activators generate calcium aluminoferrite and CSH gel through the synergistic effect of alkali activation and active admixtures, significantly improving material strength. It can partially replace cement and reduce carbon emissions.

[0054] The alkaline activator of phosphogypsum can neutralize soil acidity and improve saline-alkali land. After phosphogypsum is compounded with red mud, carbide slag, etc., it can fix heavy metals such as cadmium and lead through adsorption and precipitation to treat pollutants.

[0055] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite activator based on phosphogypsum, characterized in that: The composition comprises the following raw materials in parts by weight: 50-70 parts of phosphogypsum, 5-15 parts of alkaline activator, 10-20 parts of fly ash, 5-10 parts of slag powder, 0.5-1 part of retarder, 0.5-1 part of water reducer, 0.3-0.7 part of organosilicon additive, and 1-3 parts of expanded vermiculite.

2. A method for preparing a composite activator based on phosphogypsum, applicable to the composite activator based on phosphogypsum according to claim 1, characterized in that: The following steps are involved: S1. Raw material pretreatment: pretreatment of phosphogypsum, fly ash, slag powder and expanded vermiculite; S2, dry material mixing, the treated phosphogypsum, fly ash, slag powder and expanded vermiculite are weighed and proportioned by weight, and the phosphogypsum is first dry-mixed with the fly ash and slag powder for 2-3 minutes using a mixing equipment, and then the expanded vermiculite is added and the mixing is continued for 3-5 minutes; S3. Additive mixing: mixing retarder, water reducer and organosilicon additive in proportion to prepare liquid additive for standby use; S4, wet mixing, pouring the mixed dry materials into a blender, slowly adding alkaline activator and water during the mixing process and stirring evenly to form a slurry, and then mixing additives into the slurry to improve the fluidity of the slurry and reduce its water absorption rate; S5, filtering, pouring the prepared slurry into a filtering device, and filtering the slurry to remove agglomerated particles; S6, forming and screening, feeding the slurry into the screw extruder, adjusting the screw speed and pressure, so that the slurry is extruded into strips from the die hole, and using a high-frequency cutting knife to cut the extruded strips into particles; S7, drying and solidification, pouring the composite activator particles into a fluidized bed for drying, and the fluidized bed suspends and dries the particles through air flow.

3. The method for preparing a composite activator based on phosphogypsum according to claim 2, characterized in that: When pre-treating phosphogypsum, fly ash and slag powder, the phosphogypsum, fly ash and slag powder are first crushed using crushing equipment, and then the crushed materials are dried.

4. The method for preparing a composite activator based on phosphogypsum according to claim 1, characterized in that: When the expanded vermiculite is processed, the expanded vermiculite is calcined at 800-1000°C for 30-60 minutes to form a porous structure, thereby improving the volume stability and water absorption rate control capability.

5. The method for preparing a composite activator based on phosphogypsum according to claim 1, characterized in that: The mixing equipment is a U-shaped high-efficiency asymmetric mixer. The U-shaped high-efficiency asymmetric mixer includes a U-shaped trough body. The U-shaped trough body is equipped with inner spiral blades and outer spiral blades. The inner spiral blades and outer spiral blades operate in an asymmetric manner. The external driving component drives the inner spiral blades and outer spiral blades to rotate inside the U-shaped trough body. The inner spiral blades push the material from the middle to the two ends, and the outer spiral blades push the material from the two ends to the middle, so that the material forms a complex flow pattern in the trough body, which promotes mutual penetration and dispersion between materials.

6. The method for preparing a composite activator based on phosphogypsum according to claim 1, characterized in that: Mix the retarder, water reducer and silicone additive in proportion to make a liquid additive for use. First, add a predetermined amount of water to a container, then slowly add the retarder while stirring continuously to ensure that the retarder is completely dissolved in the water. After the retarder is fully dissolved, continue to add the water reducer while stirring to ensure that it is evenly dispersed throughout the solution. Finally, add the silicone additive and keep stirring until the entire solution becomes uniform. Use a mechanical stirrer to thoroughly stir the mixture during the stirring process. The recommended stirring speed is 300-600 rpm and the time is 5-10 minutes to allow all ingredients to be fully integrated. After stirring, use an ultrasonic processor to further improve the homogeneity of the mixture. Finally, measure the pH value of the mixed liquid additive.

7. The method for preparing a composite activator based on phosphogypsum according to claim 1, characterized in that: The mixer is a planetary mixer, which includes a mixing container with a stirring paddle installed inside the mixing container. The stirring paddle rotates inside the mixing container while revolving around the inside of the mixing container. During the revolving motion, the auxiliary scraper on the surface of the stirring paddle cleans the inside of the mixing container.

8. The method for preparing a composite activator based on phosphogypsum according to claim 1, characterized in that: The filtering equipment is a vibrating screen filter, which includes a stainless steel screen, a vibrating motor and an elastic support frame. The slurry enters the screen surface of the stainless steel screen through the feed inlet. The vibrating motor drives the screen surface to vibrate at high frequency, so that the slurry is evenly spread and quickly screened. The agglomerated particles are intercepted above the screen surface and discharged through the slag outlet. The fine slurry passes through the screen and is collected from below.

9. The method for preparing a composite activator based on phosphogypsum according to claim 1, characterized in that: The screw extruder includes a feeding system, a drive system, a heating and cooling system, and a mold. The feeding system accommodates the slurry to be processed and ensures that the material can enter the extruder smoothly. The drive system provides a power source to drive the screw to rotate. The screw rotates inside the extruder to pressurize and convey the slurry. The heating and cooling system is coated on the surface of the screw extruder and is equipped with an electric heating coil or a water cooling system to maintain the extrusion temperature required for the slurry. The mold is located at the end of the extruder and has multiple evenly distributed small holes on the mold. The slurry is extruded and formed from the small holes.

10. An application of a composite activator based on phosphogypsum, characterized in that: Composite activators based on phosphogypsum are used in building materials, soil remediation materials and pollutant treatment materials.

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