High-strength phosphogypsum water permeable brick and preparation method thereof

Abstract

The invention provides a high-strength phosphogypsum water permeable brick and a preparation method thereof, and belongs to the technical field of novel building materials. The high-strength phosphogypsum water permeable brick is prepared from the following raw materials in parts by weight: 20 to 38 parts of modified phosphogypsum, 8 to 15 parts of fly ash, 10 to 12 parts of steel slag powder, 8 to 10 parts of fly ash and 6 to 10 parts of kaolin, the modified ardealite is obtained by modifying ardealite with raffinate acid, fly ash, steel slag powder, fly ash and kaolin are mixed and fused, then the modified ardealite is added for quenching and water quenching to obtain a water-quenched mixture, and the water-quenched mixture is sintered to prepare the high-strength ardealite water-permeable brick. The preparation process is simple, reduction and recycling of solid waste such as phosphogypsum are achieved, the cost is reduced, the mechanical property and quality of the water permeable brick are remarkably improved, and good environmental benefits and economic benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of new building materials, and in particular relates to a high-strength phosphogypsum permeable brick and a preparation method thereof. Background Art

[0002] Phosphogypsum is a by-product of the phosphate fertilizer industry, with a global stockpile of over 6 billion tons (China accounts for about 60%), and long-term storage poses an environmental pollution risk. As a new type of environmentally friendly building material, phosphogypsum permeable bricks have made significant progress in resource utilization in recent years. Phosphogypsum permeable bricks can not only effectively solve the problems of urban surface impermeability and rainwater resource loss, but also realize the reuse of solid waste such as phosphogypsum and reduce environmental pollution. Therefore, its application field is gradually expanding. In addition to being used as paving materials in urban roads, squares and other places, it also plays an important role in sponge city construction.

[0003] At present, the preparation technology of phosphogypsum permeable bricks is constantly maturing, and the preparation methods and formulas are diverse. For example, the patent with publication number CN117142830A proposes a phosphogypsum-based permeable brick and its preparation method, using gypsum as a gelling agent, and coating a layer of epoxy resin film on the surface of the hardened gypsum. Since the epoxy resin itself has the characteristics of waterproofness and high strength, it can overcome the water absorption characteristics of gypsum, making the permeable brick waterproof, and at the same time improving the overall strength of the permeable brick; the patent with publication number CN107512895A proposes a high-strength phosphogypsum permeable brick and its manufacturing method, the permeable brick uses phosphogypsum, active water-quenched slag, and epoxy resin as the main raw materials, and the materials are fully mixed and wet granulated to obtain a high-strength phosphogypsum permeable brick. The calcination temperature during the preparation process is 300-400°C, and the strength and hardness of the permeable brick are enhanced by calcination.

[0004] It can be seen that the strength and stability of the phosphogypsum permeable bricks prepared by the existing technology still need to be further improved. In particular, when gypsum powder is used as a gelling agent, the prepared permeable bricks have low strength and poor product stability, and mass production cannot be achieved. Some preparation methods also use high-cost raw materials such as epoxy resin, which also limits the large-scale application of phosphogypsum permeable bricks.

[0005] In order to solve the above technical problems, the present invention proposes a high-strength phosphogypsum permeable brick and a preparation method thereof. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes a high-strength phosphogypsum permeable brick and a preparation method thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] One of the technical solutions of the present invention:

[0009] A high-strength phosphogypsum permeable brick, the raw materials comprising, by weight: 20-38 parts of modified phosphogypsum, 8-15 parts of fly ash, 10-12 parts of steel slag powder, 8-10 parts of fly ash and 6-10 parts of kaolin;

[0010] The modified phosphogypsum is obtained by modifying phosphogypsum with raffinate acid.

[0011] Furthermore, the preparation method of the modified phosphogypsum comprises the following steps:

[0012] The raffinate acid and phosphogypsum are mixed in a mass ratio of (1-4):1, and the mixture is calcined at 130-185 degrees for 5-8 hours, and then the solid-liquid is separated and ground into powder and passed through a 150-180 mesh sieve to obtain the modified phosphogypsum.

[0013] Furthermore, the phosphogypsum and raffinate acid are both by-products in the production process of wet phosphoric acid.

[0014] Raffinate acid specifically refers to the acid solution containing a large amount of metal ion impurities produced during the purification of wet-process phosphoric acid by solvent extraction and other methods to produce high-purity phosphoric acid. In the solvent extraction method, metal ion impurities (such as Mg 2+ 、Al 3+ , Fe 3+ The metal ion impurities (such as metal ions) will be selectively extracted into the organic phase by the extractant, and then these metal ion impurities are separated from the organic phase by back extraction. The acid solution containing these metal ion impurities is the raffinate acid.

[0015] The metal ions in the raffinate acid can react with the components in the phosphogypsum to form stable compounds, thereby improving the performance of the phosphogypsum. 2+ It can react with Ca in phosphogypsum through ion exchange reaction 2+ Ions are exchanged to form new metal sulfate compounds. Through the metal ion exchange reaction, the chemical composition and crystal structure of phosphogypsum can be changed, thereby improving the stability and strength of phosphogypsum. The reaction can be expressed as:

[0016] Mg 2+ +CaSO4·2H2O→Ca 2+ +MgO4·2H2O.

[0017] Furthermore, the average particle size of the fly ash is 50-125 μm, and the CaO content is ≥50 wt.%.

[0018] Furthermore, the specific surface area of ​​the steel slag powder is ≥400m 2 / kg.

[0019] Further, the particle size of the fly ash is 2 - 10 μm.

[0020] Further, the particle size of the kaolin is 0.7 - 2.5 μm.

[0021] Further, the raw materials by weight include: 34 parts of modified phosphogypsum, 11 parts of fly ash, 11 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin.

[0022] The second technical solution of the present invention:

[0023] A preparation method of the high-strength phosphogypsum permeable brick as described above, comprising the following steps:

[0024] Weigh each raw material by weight, mix fly ash, steel slag powder, fly ash, and kaolin and then conduct melting treatment, and then add modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture. Sinter the water-quenched mixture to prepare the high-strength phosphogypsum permeable brick.

[0025] Further, the temperature of the melting treatment is 1000 - 1200 °C, and the time is 1.5 - 2 h.

[0026] Further, the particle size of the water-quenched mixture is 8 - 9 mm.

[0027] Further, the temperature of the sintering treatment is 800 - 1000 °C, and the time is 2 - 3 h.

[0028] Further, before the sintering treatment, it also includes the step of forming the water-quenched mixture in a mold.

[0029] Compared with the prior art, the present invention has the following advantages and technical effects:

[0030] (1) The permeable brick of the present invention uses modified phosphogypsum, fly ash, steel slag powder, fly ash, and kaolin as raw materials, realizing the comprehensive utilization of solid waste resources. The modified phosphogypsum further improves the stability and strength of the raw materials, and through mutual filling with fly ash, kaolin, etc., forms a more uniform pore structure, improving the water permeability and mechanical strength of the brick body; in addition, the active components in these raw materials can react with each other to generate more hydration products, further improving the density and strength of the brick body.

[0031] (2) In the present invention, fly ash, steel slag powder, fly ash, and kaolin are mixed and then subjected to melting treatment. Through this step, the characteristics of various raw materials can be fully integrated, and at the same time, some chemical components that are unfavorable to the sintering process can be removed. Specifically, the vitreous components in fly ash interact with the active calcium oxide and magnesium oxide in steel slag powder during the high-temperature melting process to form a more stable mineral phase, improving the activity and stability of the mixture. In addition, impurities such as unburned carbon in fly ash are effectively removed during the melting process, reducing the adverse effects on the sintering process. Subsequently, modified phosphogypsum is added and rapid water quenching treatment is carried out to obtain a water-quenched mixture. This process further optimizes the chemical and mechanical properties of the mixture. The hydration products generated by the reaction of modified phosphogypsum with water during the water quenching process can fill the pores and improve the density of the mixture. Finally, the water-quenched mixture is subjected to sintering treatment, and high-strength phosphogypsum permeable bricks are successfully prepared.

[0032] (3) The preparation process of the present invention is simple. It not only realizes the reduction and resource utilization of solid waste such as phosphogypsum, reduces costs, but also significantly improves the mechanical properties and quality of the permeable bricks, having good environmental and economic benefits. Detailed Embodiments

[0033] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation embodiments of the present invention.

[0034] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0035] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0036] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the specification of the present invention, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0037] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0038] In the embodiments of the present invention, "parts" represent "parts by weight" unless otherwise specified.

[0039] The embodiments of the present invention provide a high-strength phosphogypsum permeable brick, and the raw materials include, by weight: 20-38 parts of modified phosphogypsum, 8-15 parts of fly ash, 10-12 parts of steel slag powder, 8-10 parts of fly ash, and 6-10 parts of kaolin.

[0040] The modified phosphogypsum is obtained by modifying phosphogypsum with raffinate acid.

[0041] In the optimal embodiment of the present invention, the raw materials of the high-strength phosphogypsum permeable brick include, by weight: 34 parts of modified phosphogypsum, 11 parts of fly ash, 11 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin.

[0042] In some preferred embodiments of the present invention, the preparation method of the modified phosphogypsum includes the following steps:

[0043] Mix the raffinate acid and phosphogypsum according to a mass ratio of (1-4):1, calcine the mixture at 130-185 for 5-8 h, then perform solid-liquid separation and grind it into powder and pass through a 150-180 mesh sieve to obtain the modified phosphogypsum.

[0044] In some preferred embodiments of the present invention, both the phosphogypsum and the raffinate acid are by-products in the wet-process phosphoric acid production process. More specifically, the sources of the phosphogypsum and the raffinate acid are both Yunnan Yuntianhua Co., Ltd.

[0045] In some preferred embodiments of the present invention, the average particle size of the fly ash is 50-125 μm, and the CaO content ≥ 50 wt.%. More specifically, the fly ash is purchased from Zhejiang Zuhui Environmental Technology Co., Ltd. (pretreated by washing with water to remove impurities).

[0046] In some preferred embodiments of the present invention, the specific surface area of the steel slag powder ≥ 400 m 2 / kg. More specifically, the steel slag powder is purchased from Shanghai Baosteel New Building Materials Technology Co., Ltd., and the specific surface area of the steel slag powder is 800-1000 m 2 / kg.

[0047] In some preferred embodiments of the present invention, the particle size of fly ash is 2 - 10 μm. More specifically, the fly ash is purchased from Jining Hengzhi New Building Materials Co., Ltd.

[0048] In some preferred embodiments of the present invention, the particle size of kaolin is 0.7 - 2.5 μm. More specifically, the kaolin is purchased from Longyan Kaolin Co., Ltd.

[0049] The embodiments of the present invention also provide a method for preparing high-strength phosphogypsum permeable bricks, which includes the following steps:

[0050] Weigh each raw material by weight. Mix fly ash, steel slag powder, fly ash and kaolin and then perform melting treatment. After that, add modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture. Sinter the water-quenched mixture to prepare high-strength phosphogypsum permeable bricks.

[0051] Rapid water quenching is a rapid cooling technology, which means cooling high-temperature materials to room temperature (25 ± 2 °C) at an extremely fast speed. By rapid water quenching, the glass structure of the melt can be fixed, and the activity and stability of the material can be improved.

[0052] In some preferred embodiments of the present invention, the temperature of the melting treatment is 1000 - 1200 °C, and the time is 1.5 - 2 h.

[0053] In some preferred embodiments of the present invention, the particle size of the water-quenched mixture is 8 - 9 mm.

[0054] In some preferred embodiments of the present invention, the temperature of the sintering treatment is 800 - 1000 °C, and the time is 2 - 3 h.

[0055] In some preferred embodiments of the present invention, before the sintering treatment, it further includes the step of forming the water-quenched mixture in a mold.

[0056] In the embodiments of the present invention, the test standard for the compressive strength of the permeable brick is GB / T 25674-2010 "Permeable Bricks", and it is required that the compressive strength of the permeable brick should be not less than 30 MPa. The test standard for the flexural strength is GB / T 25993 "Test Methods for Permeable Road Panel Bricks", and it is required that the flexural strength of the permeable brick should be not less than 15 MPa. The test standard for the permeability coefficient is CJJ / T 188-2012 "Technical Specification for Permeable Brick Pavement", and it is required that the permeability coefficient should be not less than 1.0×10 -2 cm / s.

[0057] The technical solutions of the present invention are further described below through examples.

[0058] Example 1

[0059] (1) Mix the raffinate acid and phosphogypsum in a mass ratio of 2:1, calcine the mixture at 165 °C for 6 h, then add calcium hydroxide to adjust the pH to neutral, separate the solid and liquid, grind it into powder, and pass through a 150-mesh sieve to obtain modified phosphogypsum;

[0060] (2) Weigh the following raw materials by weight: 34 parts of the modified phosphogypsum prepared in step (1), 11 parts of fly ash, 11 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin;

[0061] (3) Mix fly ash, steel slag powder, fly ash, and kaolin and melt them at 1100 °C for 2 h, then add the modified phosphogypsum, and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8-9 mm. Put the water-quenched mixture into a mold to form and sinter it at 900 °C for 2 h to prepare high-strength phosphogypsum permeable bricks.

[0062] Example 2

[0063] (1) Mix the raffinate acid and phosphogypsum in a mass ratio of 3:1, calcine the mixture at 180 °C for 5 h, then add calcium hydroxide to adjust the pH to neutral, separate the solid and liquid, grind it into powder, and pass through a 150-180 mesh sieve to obtain modified phosphogypsum;

[0064] (2) Weigh the following raw materials by weight: 38 parts of the modified phosphogypsum prepared in step (1), 8 parts of fly ash, 10 parts of steel slag powder, 8 parts of fly ash, and 10 parts of kaolin;

[0065] (3) Mix fly ash, steel slag powder, fly ash, and kaolin and melt them at 1200 °C for 1.5 h, then add the modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8-9 mm. Put the water-quenched mixture into a mold to form and sinter it at 1000 °C for 2 h to prepare high-strength phosphogypsum permeable bricks.

[0066] Example 3

[0067] (1) Mix the raffinate acid and phosphogypsum in a mass ratio of 1:1, calcine the mixture at 130 °C for 8 h, then add calcium hydroxide to adjust the pH to neutral, separate the solid and liquid, grind it into powder, and pass through a 150-180 mesh sieve to obtain modified phosphogypsum;

[0068] (2) Weigh the following raw materials by weight: 20 parts of the modified phosphogypsum prepared in step (1), 15 parts of fly ash, 12 parts of steel slag powder, 10 parts of fly ash, and 6 parts of kaolin;

[0069] (3) Mix fly ash, steel slag powder, fly ash, and kaolin, then melt the mixture at 1000 °C for 1.5 h. After that, add calcium hydroxide to adjust the pH to neutral, add modified phosphogypsum, and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8-9 mm. Place the water-quenched mixture in a mold to form and sinter it at 800 °C for 3 h to prepare high-strength phosphogypsum permeable bricks.

[0070] Example 4

[0071] (1) Mix the raffinate acid and phosphogypsum in a mass ratio of 4:1, calcine the mixture at 185 °C for 6 h. After that, add calcium hydroxide to adjust the pH to neutral, perform solid-liquid separation, grind it into powder, and pass through a 150-180 mesh sieve to obtain modified phosphogypsum.

[0072] (2) Weigh the following raw materials by weight: 33 parts of the modified phosphogypsum prepared in step (1), 11 parts of fly ash, 10 parts of steel slag powder, 9 parts of fly ash, and 8 parts of kaolin.

[0073] (3) Mix fly ash, steel slag powder, fly ash, and kaolin, then melt the mixture at 1080 °C for 1.5 h. After that, add modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8-9 mm. Place the water-quenched mixture in a mold to form and sinter it at 950 °C for 2.3 h to prepare high-strength phosphogypsum permeable bricks.

[0074] Comparative Example 1

[0075] Same as Example 1, the difference is only that the step of modifying phosphogypsum is omitted, specifically including:

[0076] (1) Weigh the following raw materials by weight: 34 parts of phosphogypsum, 11 parts of fly ash, 11 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin.

[0077] (2) Mix fly ash, steel slag powder, fly ash, and kaolin, then melt the mixture at 1100 °C for 2 h. After that, add phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8-9 mm. Place the water-quenched mixture in a mold to form and sinter it at 900 °C for 2 h to prepare phosphogypsum permeable bricks.

[0078] Comparative Example 2

[0079] Same as Example 1, the difference is only that the step of modifying phosphogypsum is different, specifically including:

[0080] (1) Calcinate phosphogypsum at 165 °C for 6 h, then perform solid-liquid separation, grind it into powder, and pass through a 150-180 mesh sieve to obtain modified phosphogypsum.

[0081] (2) Weigh the following raw materials by weight parts: 34 parts of the modified phosphogypsum prepared in step (1), 11 parts of fly ash, 6 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin;

[0082] (3) Mix fly ash, steel slag powder, fly ash, and kaolin, and then conduct a melting treatment at 1100 °C for 2 h. After that, add the modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8 - 9 mm. Place the water-quenched mixture into a mold for forming and conduct a sintering treatment at 900 °C for 2 h to prepare the phosphogypsum permeable brick.

[0083] Comparative Example 3

[0084] Same as Example 1, the difference is only that the addition of fly ash is omitted, specifically including:

[0085] (1) Mix the raffinate acid and phosphogypsum according to a mass ratio of 2:1, calcine the mixture at 165 °C for 6 h. After that, add calcium hydroxide to adjust the pH to neutral, perform solid-liquid separation, grind into powder, and pass through a 150 - 180 mesh sieve to obtain the modified phosphogypsum;

[0086] (2) Weigh the following raw materials by weight parts: 34 parts of the modified phosphogypsum prepared in step (1), 11 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin;

[0087] (3) Mix steel slag powder, fly ash, and kaolin, and then conduct a melting treatment at 1100 °C for 2 h. After that, add the modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8 - 9 mm. Place the water-quenched mixture into a mold for forming and conduct a sintering treatment at 900 °C for 2 h to prepare the phosphogypsum permeable brick.

[0088] Comparative Example 4

[0089] Same as Example 1, the difference is only that the addition of kaolin is omitted, specifically including:

[0090] (1) Mix the raffinate acid and phosphogypsum according to a mass ratio of 2:1, calcine the mixture at 165 °C for 6 h. After that, add calcium hydroxide to adjust the pH to neutral, perform solid-liquid separation, grind into powder, and pass through a 150 - 180 mesh sieve to obtain the modified phosphogypsum;

[0091] (2) Weigh the following raw materials by weight parts: 34 parts of the modified phosphogypsum prepared in step (1), 11 parts of fly ash, 11 parts of steel slag powder, and 8 parts of fly ash;

[0092] (3) Mix fly ash, steel slag powder, and fly ash, and then conduct a melting treatment at 1100 °C for 2 h. After that, add the modified phosphogypsum and perform rapid water quenching to obtain a water-quenched mixture with a particle size of 8 - 9 mm. Place the water-quenched mixture into a mold for forming and conduct a sintering treatment at 900 °C for 2 h to prepare the phosphogypsum permeable brick.

[0093] Comparative Example 5

[0094] Same as Example 1, except that step (3) is different, specifically including:

[0095] (1) Mix the raffinate acid and phosphogypsum in a mass ratio of 2:1, calcine the mixture at 165 °C for 6 h, then add calcium hydroxide to adjust the pH to neutral, perform solid-liquid separation and grind into powder, and pass through a 150-180 mesh sieve to obtain modified phosphogypsum;

[0096] (2) Weigh the following raw materials by weight: 34 parts of the modified phosphogypsum prepared in step (1), 11 parts of fly ash, 11 parts of steel slag powder, 8 parts of fly ash, and 7 parts of kaolin;

[0097] (3) After mixing fly ash, steel slag powder, fly ash, kaolin, and modified phosphogypsum, put the mixture into a mold for forming and sinter at 900 °C for 2 h to prepare phosphogypsum permeable bricks.

[0098] Performance Test

[0099] Perform compressive strength, flexural strength, and water permeability coefficient tests on the permeable bricks prepared in Examples 1-4 and Comparative Examples 1-5. The results are shown in Table 1.

[0100] Table 1 Performance Test Results of Permeable Bricks in Examples 1-4 and Comparative Examples 1-5

[0101] Compressive strength (MPa) Flexural strength (MPa) Permeability coefficient (cm / s) Example 1 58 22 <![CDATA[2.53×10 -2 > Example 2 56 20 <![CDATA[2.36×10 -2 > Example 3 55 19 <![CDATA[2.47×10 -2 > Example 4 57 21 <![CDATA[2.28×10 -2 > Comparative example 1 36 10 <![CDATA[1.91×10 -2 > Comparative example 2 42 15 <![CDATA[2.04×10 -2 > Comparative example 3 40 13 <![CDATA[2.13×10 -2 > Comparative example 4 41 15 <![CDATA[2.07×10 -2 > Comparative example 5 38 17 <![CDATA[1.99×10 -2 >

[0102] As can be seen from Table 1, the compressive strength of the permeable bricks prepared in the examples of the present invention reaches a maximum of 58 MPa, the flexural strength reaches a maximum of 22 MPa, and the water permeability coefficient is up to 2.53×10 -2 cm / s. All performances are better than those of the prior art, and meet the requirements of various standards at the same time. Moreover, the permeable bricks in the examples of the present invention are made of modified phosphogypsum, fly ash, steel slag powder, fly ash, and kaolin, realizing the comprehensive utilization of solid waste resources.

[0103] Comparative Example 1 omits the step of modifying phosphogypsum. Compared with Example 1, since the phosphogypsum permeable bricks are not treated with raffinate acid, the chemical composition and crystal structure inside the phosphogypsum do not change, and its stability and strength both decrease. Therefore, the performances of the permeable bricks prepared in Comparative Example 1 decrease.

[0104] In Comparative Example 2, phosphogypsum is modified by direct calcination. Compared with Example 1, direct calcination without raffinate acid treatment will cause agglomeration of phosphogypsum particles, resulting in poor dispersibility. At the same time, the crystal form transformation of phosphogypsum is incomplete, affecting its gel performance, thus leading to a decrease in the performance of the permeable bricks.

[0105] On the basis of Example 1, in Comparative Example 3 and Comparative Example 4, the addition of fly ash and kaolin was omitted respectively. At this time, a more uniform pore structure could not be formed among the raw materials, so the performance of the permeable brick decreased.

[0106] In Comparative Example 5, the raw materials were directly mixed and sintered. In this method, the characteristics of the raw materials could not be fully integrated, and the impurity components in the raw materials could not be effectively removed, reducing the density of the material, thus resulting in a decrease in the performance of the permeable brick.

[0107] In summary, the preparation process of the invention is simple. It not only realizes the reduction and resource utilization of solid wastes such as phosphogypsum, reduces costs, but also significantly improves the mechanical properties and quality of the permeable brick, having good environmental and economic benefits.

[0108] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A high-strength phosphogypsum permeable brick, characterized in that, The raw materials include, by weight: 20-38 parts of modified phosphogypsum, 8-15 parts of fly ash, 10-12 parts of steel slag powder, 8-10 parts of fly ash and 6-10 parts of kaolin; The modified phosphogypsum is obtained by modifying phosphogypsum with raffinate acid.

2. The high-strength phosphogypsum permeable brick according to claim 1, wherein The preparation method of the modified phosphogypsum comprises the following steps: The raffinate acid and phosphogypsum are mixed in a mass ratio of (1-4):1, and the mixture is calcined at 130-185°C for 5-8h, and then the mixture is separated into solid and liquid and ground into powder and passed through a 150-180 mesh sieve to obtain the modified phosphogypsum.

3. The high-strength phosphogypsum permeable brick according to claim 2, characterized in that, The phosphogypsum and raffinate acid are both by-products in the production process of wet phosphoric acid.

4. The high-strength phosphogypsum permeable brick according to claim 1, wherein The fly ash has an average particle size of 50-125 μm and a CaO content of ≥50 wt.%; The specific surface area of the steel slag powder ≥ 400 m 2 / kg; The particle size of the fly ash is 2-10 μm; The particle size of the kaolin is 0.7-2.5 μm.

5. The high-strength phosphogypsum permeable brick according to claim 1, characterized in that The raw materials include, by weight: 34 parts of modified phosphogypsum, 11 parts of fly ash, 11 parts of steel slag powder, 8 parts of fly ash and 7 parts of kaolin.

6. A method for preparing the high-strength phosphogypsum permeable brick according to any one of claims 1-5, characterized in that, The following steps are involved: The raw materials are weighed according to their weight proportions, fly ash, steel slag powder, fly ash and kaolin are mixed and melted, and then modified phosphogypsum is added, and a water-quenched mixture is obtained by rapid cooling and water quenching. The water-quenched mixture is sintered to prepare the high-strength phosphogypsum permeable brick.

7. The preparation method of the high-strength phosphogypsum permeable brick according to claim 6, characterized in that, The temperature of the melting treatment is 1000-1200° C. and the time is 1.5-2 hours.

8. The preparation method of the high-strength phosphogypsum permeable brick according to claim 6, characterized in that, The particle size of the water-quenched mixture is 8-9 mm.

9. The preparation method of the high-strength phosphogypsum permeable brick according to claim 6, characterized in that, The sintering process is carried out at a temperature of 800-1000° C. and for a time of 2-3 hours.

10. The preparation method of the high-strength phosphogypsum permeable brick according to claim 6, characterized in that, The sintering process also includes the step of placing the water-quenched mixture into a mold for forming.