Phosphogypsum light artificial stone and preparation method thereof

Abstract

The invention relates to a phosphogypsum light artificial stone and a preparation method thereof, and belongs to the field of solid waste resource utilization materials. The ardealite artificial stone is prepared from the following raw materials in parts by weight: 40-70 parts of modified ardealite, 17-40 parts of slag powder, 5-25 parts of ordinary Portland cement, 0-10 parts of a high-activity solid waste material and 2-4 parts of a polycarboxylate superplasticizer, the water-solid ratio is 0.18 to 0.25; the modified ardealite is obtained by adding carbide slag into ardealite, uniformly mixing, crushing, piling and aging, and the addition amount of the carbide slag is 1-11% of the weight of the ardealite. The preparation method comprises the following steps: preparing modified phosphogypsum; mixing the components to prepare slurry; and molding and curing the slurry. The apparent density of the prepared ardealite artificial stone is about 2100 kg / m, the 28d cubic compressive strength is 20-60 MPa, the softening coefficient is larger than or equal to 0.85, high-value utilization of ardealite, carbide slag and other industrial solid waste is achieved, and the ardealite artificial stone has good mechanical performance and water resistance.

Description

Technical Field

[0001] This invention relates to the field of building materials, specifically to a phosphogypsum lightweight artificial stone and its preparation method. Background Technology

[0002] Natural stone is widely used in building decoration due to its excellent physical properties and beautiful appearance. However, the mining and processing of natural stone not only consumes a large amount of energy but also causes serious damage to the ecological environment, and resources are limited, making it difficult to meet market demand. Therefore, developing and utilizing industrial solid waste to produce artificial stone has become an important way to solve resource shortages and protect the environment. Unlike natural stone, artificial stone not only has the texture and beauty of natural stone but also achieves environmentally friendly characteristics such as low energy consumption, low pollution, and recyclability in its production process. This can effectively reduce dependence on natural resources and make a positive contribution to green building and sustainable development. As a result, the application of artificial stone in the construction engineering field is becoming increasingly widespread.

[0003] Phosphogypsum is an industrial solid waste produced by treating phosphate rock with sulfuric acid to extract phosphoric acid. Its main component is calcium sulfate (CaSO4·2H2O), and approximately 5 tons of phosphogypsum are produced for every ton of phosphoric acid produced. Data shows that my country's annual phosphogypsum production is approximately 70 million tons, but the comprehensive utilization rate is only 40%–44%. Domestically, phosphogypsum is mainly used in cement retarder, road filling and cementitious materials, and gypsum and other building materials. About 30% is used to produce cement retarder, 25% is sold or supplied externally, and only 14% is used to make gypsum board. The soluble phosphorus and fluorine impurities in phosphogypsum limit its application in the building materials industry.

[0004] In the prior art, CN109574615B discloses a method for preparing high-content solid waste cementitious materials by modifying phosphogypsum with quartz slurry. This method improves the utilization rate of phosphogypsum by modifying it with artificial quartz slurry, but it requires drying and grinding the phosphogypsum before mixing it with other materials, making the process relatively complex. CN109574614B provides a method for preparing concrete using quartz slurry-modified phosphogypsum-based cementitious materials. Although this method can replace 80% of traditional silicate cement, it still requires pretreatment processes such as drying and grinding, resulting in a long production cycle and high cost.

[0005] CN116041026A discloses a phosphogypsum lightweight aggregate concrete and its preparation method. This method utilizes phosphogypsum to prepare lightweight aggregate, which can improve the utilization rate of phosphogypsum. However, it is mainly applied in the concrete field and has not been effectively applied in the artificial stone field. CN106587872B proposes an early-strength phosphogypsum-based micro-expansion grouting material. This grouting material has advantages such as good fluidity and high early and late strength. However, it is mainly used in the grouting field and is not suitable for preparing artificial stone with decorative properties. CN115403335A introduces a solid waste resource-based composite reinforcement material. This material is prepared using industrial solid waste such as slag powder, cement, and alkaline waste residue, realizing the large-scale utilization of industrial solid waste. However, it does not involve the application of phosphogypsum in the artificial stone field.

[0006] In summary, existing technologies suffer from the following problems: First, the mining and processing of natural stone involves high energy consumption and damage to the ecological environment; second, phosphogypsum, as an industrial solid waste, suffers from severe accumulation and low comprehensive utilization rate, with impurities such as soluble phosphorus and fluorine restricting its application in the building materials industry; third, existing methods for preparing artificial stone and lightweight artificial stone from solid waste materials are characterized by complex preparation processes, long reaction times, and high energy consumption; and fourth, existing technologies have failed to achieve effective utilization of phosphogypsum in the field of artificial stone. Therefore, developing a simple, efficient, and environmentally friendly method for preparing phosphogypsum artificial stone can not only improve the comprehensive utilization rate of phosphogypsum but also reduce the mining of natural stone, which is of great significance for resource conservation and environmental protection. Summary of the Invention

[0007] To address the problems of existing technologies, this invention provides a lightweight artificial stone made of phosphogypsum and its preparation method. This invention is the first to apply a large amount of phosphogypsum to the field of artificial stone, solving the technical problem of low utilization rate of phosphogypsum in the field of artificial stone, providing a new way for the high-value utilization of phosphogypsum, realizing the resource utilization of industrial solid waste, reducing the impact on the environment, and the preparation process is simple, efficient and easy to industrialize.

[0008] This invention is achieved through the following technical solution: First, the present invention provides a phosphogypsum lightweight artificial stone, which, by weight, comprises the following components in its preparation raw materials: 40-70 parts modified phosphogypsum, 17-40 parts slag powder, 5-25 parts ordinary silicate cement, 0-10 parts highly active solid waste material, and 2-4 parts polycarboxylate superplasticizer; with a water-to-solid ratio of 0.18-0.25. Preferably, the raw materials for its preparation include the following components by weight: 50-70 parts modified phosphogypsum, 17-30 parts slag powder, 5-20 parts ordinary silicate cement, 3-7 parts highly active solid waste material, and 3-4 parts polycarboxylate superplasticizer. The modified phosphogypsum is obtained by adding carbide slag to phosphogypsum, mixing and crushing it evenly, and then piling it up for aging.

[0009] Preferably, the amount of calcium carbide slag added is 1-11% of the weight of phosphogypsum, the crushing is carried out by a double-stage screenless crusher, and the aging time is ≥24h; further, the amount of calcium carbide slag added is 5-11% of the weight of phosphogypsum.

[0010] Preferably, the phosphogypsum is a product of wet phosphoric acid production, wherein the SO3 content is greater than 45%. The relevant requirements should meet the requirements of GB / T 23456 "Phosphogypsum" for use in building materials.

[0011] Preferably, the calcium carbide slag is the waste residue with calcium hydroxide as the main component after obtaining acetylene gas by calcium carbide hydrolysis, and its CaO content is not less than 90% after drying.

[0012] Preferably, the slag powder is S95 grade granulated blast furnace slag powder. The relevant requirements meet GB / T 18046 "Granulated blast furnace slag powder for use in cement, mortar and concrete".

[0013] Preferably, the ordinary Portland cement has a strength grade of 42.5 or 52.5, and the relevant requirements meet GB / T175 "General Portland Cement"; Preferably, the highly active solid waste material is a solid material mainly containing one or more of Al2O3, SiO2, and CaO, wherein the Al2O3 accounts for 0-50% by mass, the SiO2 accounts for 0-75% by mass, and the CaO accounts for 0-50% by mass, and includes one or more of metakaolin, fly ash, silica fume, red mud, lithium slag, and stone powder.

[0014] Preferably, the polycarboxylate superplasticizer is a liquid polycarboxylate superplasticizer with a solid content of 8%.

[0015] Preferably, the apparent density of the phosphogypsum lightweight artificial stone is 2020-2120 kg / m³, the 28-day cubic compressive strength is 20-60 MPa, and the softening coefficient is ≥0.85.

[0016] Secondly, the present invention provides a method for preparing the above-mentioned phosphogypsum lightweight artificial stone, comprising the following steps: (1) Preparation of modified phosphogypsum: Add carbide slag to phosphogypsum, mix and crush by a double-stage screenless crusher, and then pile up for aging treatment for ≥24h. (2) Slurry preparation: Mix modified phosphogypsum, slag powder, ordinary silicate cement and high-activity solid waste material and stir at 20-50 r / min for 1-3 min, then add water and polycarboxylate superplasticizer, and continue stirring at 20-50 r / min for 8-20 min; (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 7 to 28 days at 10 to 60°C and relative humidity > 60%.

[0017] The above preparation process flow chart is shown below. Figure 1 .

[0018] The beneficial effects of this invention are as follows: 1. This invention is the first to apply a large amount of phosphogypsum to the field of artificial stone, which solves the technical problem of low utilization rate of phosphogypsum in the field of artificial stone and provides a new way for the high-value utilization of phosphogypsum; 2. 90% of the raw materials for the phosphogypsum lightweight artificial stone of this invention come from industrial solid waste, realizing the resource utilization of industrial solid waste and reducing the impact on the environment; 3. The apparent density of the phosphogypsum lightweight artificial stone prepared by this invention is about 2100 kg / m³, which is lighter than that of ordinary limestone (2700 kg / m³), achieving lightweighting, reducing material transportation costs, and making installation more convenient; 4. The phosphogypsum lightweight artificial stone prepared by this invention has a 28-day cubic compressive strength of 20MPa to 60MPa and a softening coefficient of not less than 0.85, exhibiting excellent mechanical properties and water resistance. 5. The temperature of the preparation process of the phosphogypsum lightweight artificial stone of the present invention is controlled not to exceed 60°C, resulting in low energy consumption. Furthermore, it does not use processes such as drying, grinding, or pressure molding, making it more environmentally friendly. 6. The phosphogypsum lightweight artificial stone of the present invention is easy to process and can be quickly and easily cut, polished and other operations, which greatly improves production efficiency. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the phosphogypsum lightweight artificial stone of the present invention. Detailed Implementation

[0020] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0021] The processes, conditions, reagents, and experimental methods used in implementing this invention, except as specifically mentioned below, are all common knowledge and general knowledge in the field, and this invention does not have any particular limitations. Experimental methods in the embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.

[0022] Unless otherwise stated, all technical terms and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. However, in the event of any conflict, the specification containing the definitions shall prevail.

[0023] Example 1 A lightweight artificial stone made of phosphogypsum, the raw materials for which are prepared include the following components by weight: 55 parts modified phosphogypsum, 28 parts slag powder, 15 parts ordinary silicate cement, 5 parts highly active solid waste material, 3 parts polycarboxylate superplasticizer, and a water-to-solid ratio of 0.2.

[0024] The preparation process of modified phosphogypsum is as follows: 5% by weight of carbide slag is added to the phosphogypsum, mixed evenly, and then crushed using a double-stage screenless crusher. After aging in stock for 48 hours, the modified phosphogypsum is obtained. The phosphogypsum used is a product of wet-process phosphoric acid production, with an SO3 content of 47%; the carbide slag used has a CaO content of 92% after drying. The slag powder used is S95 grade granulated blast furnace slag powder; the ordinary silicate cement used has a strength grade of 42.5. The highly active solid waste material used is fly ash, which contains 35% Al2O3, 45% SiO2, and 10% CaO by mass percentage. The polycarboxylate superplasticizer used is a liquid polycarboxylate superplasticizer with a solid content of 8%.

[0025] The preparation method of this phosphogypsum lightweight artificial stone includes the following steps: (1) Preparation of modified phosphogypsum: 5% of the weight of carbide slag is added to the phosphogypsum, mixed and crushed by a double-stage screenless crusher, and then piled up for aging treatment for 48 hours. (2) Slurry preparation: Mix modified phosphogypsum, slag powder, ordinary silicate cement and high-activity solid waste material and stir at 30 r / min for 2 min, then add water and polycarboxylate superplasticizer, and continue stirring at 30 r / min for 15 min; (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 28 days at 25℃ and 80% relative humidity.

[0026] The prepared phosphogypsum artificial stone has an apparent density of 2080 kg / m³, a 7-day cubic compressive strength of 11.2 MPa, a 28-day cubic compressive strength of 40.3 MPa, and a softening coefficient of 0.90.

[0027] Example 2 A phosphogypsum artificial stone, the raw materials for which are prepared include the following components by weight: 40 parts modified phosphogypsum, 40 parts slag powder, 25 parts ordinary silicate cement, 0 parts high-activity solid waste material, 2 parts polycarboxylate superplasticizer, and the balance water with a water-to-solid ratio of 0.25.

[0028] The preparation process of modified phosphogypsum is as follows: 1% by weight of carbide slag is added to the phosphogypsum, mixed evenly, and then crushed using a double-stage screenless crusher. After aging in piles for 24 hours, the modified phosphogypsum is obtained. The phosphogypsum used is a product of wet-process phosphoric acid production, with an SO3 content of 46%; the carbide slag used has a CaO content of 90% after drying. The slag powder used is S95 grade granulated blast furnace slag powder; the ordinary Portland cement used has a strength grade of 52.5. The polycarboxylate superplasticizer used is a liquid polycarboxylate superplasticizer with a solid content of 8%.

[0029] The preparation method of this phosphogypsum artificial stone includes the following steps: (1) Preparation of modified phosphogypsum: 1% of carbide slag by weight of phosphogypsum is added to phosphogypsum, mixed and crushed by a double-stage screenless crusher, and then piled up for aging treatment for 24 hours. (2) Slurry preparation: Mix modified phosphogypsum, slag powder and ordinary silicate cement and stir at 20 r / min for 1 min, then add water and polycarboxylate superplasticizer, and continue stirring at 20 r / min for 8 min; (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 14 days at 60℃ and 90% relative humidity.

[0030] The prepared phosphogypsum artificial stone has an apparent density of 2120 kg / m³, a 7-day cubic compressive strength of 45.6 MPa, a 28-day cubic compressive strength of 60.4 MPa, and a softening coefficient of 0.95.

[0031] Example 3 A phosphogypsum artificial stone, the raw materials for which are prepared include the following components by weight: 70 parts modified phosphogypsum, 17 parts slag powder, 5 parts ordinary silicate cement, 10 parts highly active solid waste material, 4 parts polycarboxylate superplasticizer, and a water-to-solid ratio of 0.18.

[0032] The preparation process of modified phosphogypsum is as follows: Calcium carbide slag, accounting for 11% of the weight of the phosphogypsum, is added to the phosphogypsum and mixed evenly. After mixing, it is crushed using a double-stage screenless crusher and aged for 72 hours. The phosphogypsum used is a product of wet-process phosphoric acid production, with an SO3 content of 48%. The calcium carbide slag used has a CaO content of 95% after drying. The slag powder used is S95 grade granulated blast furnace slag powder; the ordinary silicate cement used has a strength grade of 42.5. The highly active solid waste material used is a mixture of silica fume and red mud, with a silica fume to red mud mass ratio of 3:2, containing 20% ​​Al2O3, 65% SiO2, and 15% CaO by mass percentage. The polycarboxylate superplasticizer used is a liquid polycarboxylate superplasticizer with a solid content of 8%.

[0033] The preparation method of this phosphogypsum artificial stone includes the following steps: (1) Preparation of modified phosphogypsum: 11% of the weight of carbide slag is added to the phosphogypsum, mixed and crushed by a double-stage screenless crusher, and then piled up for aging treatment for 72 hours. (2) Slurry preparation: Mix modified phosphogypsum, slag powder, ordinary silicate cement and high-activity solid waste material and stir at 50 r / min for 3 min, then add water and polycarboxylate superplasticizer, and continue stirring at 50 r / min for 20 min. (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 7 days at 10℃ and 65% relative humidity.

[0034] The prepared phosphogypsum artificial stone has an apparent density of 2020 kg / m³, a 7-day cubic compressive strength of 5.5 MPa, a 28-day cubic compressive strength of 20.6 MPa, and a softening coefficient of 0.85.

[0035] Example 4 A phosphogypsum artificial stone, the raw materials for which are prepared include the following components by weight: 60 parts modified phosphogypsum, 25 parts slag powder, 10 parts ordinary silicate cement, 7 parts highly active solid waste material, 3 parts polycarboxylate superplasticizer, and a water-to-solid ratio of 0.21.

[0036] The preparation process of modified phosphogypsum is as follows: 8% by weight of carbide slag is added to the phosphogypsum, mixed evenly, and then crushed using a double-stage screenless crusher. After aging in stock for 36 hours, the phosphogypsum is obtained. The phosphogypsum used is a product of wet-process phosphoric acid production, with an SO3 content of 47.5%; the carbide slag used has a CaO content of 93% after drying. The slag powder used is S95 grade granulated blast furnace slag powder; the ordinary silicate cement used has a strength grade of 42.5. The highly active solid waste material used is a mixture of metakaolin and stone powder, with a mass ratio of metakaolin to stone powder of 1:1, containing 30% Al2O3, 50% SiO2, and 20% CaO by mass percentage. The polycarboxylate superplasticizer used is a liquid polycarboxylate superplasticizer with a solid content of 8%.

[0037] The preparation method of this phosphogypsum artificial stone includes the following steps: (1) Preparation of modified phosphogypsum: 8% of the weight of carbide slag is added to the phosphogypsum, mixed and crushed by a double-stage screenless crusher, and then piled up for aging treatment for 36 hours. (2) Slurry preparation: Modified phosphogypsum, slag powder, ordinary silicate cement and high-activity solid waste material are mixed and stirred at 35 r / min for 2.5 min, then water and polycarboxylate superplasticizer are added, and stirring is continued at 35 r / min for 12 min. (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 21 days at 30℃ and 75% relative humidity.

[0038] The prepared phosphogypsum artificial stone has an apparent density of 2055 kg / m³, a 7-day cubic compressive strength of 12.7 MPa, a 28-day cubic compressive strength of 43.1 MPa, and a softening coefficient of 0.91.

[0039] Example 5 A type of phosphogypsum artificial stone, the raw materials for which are prepared include the following components by weight: 50 parts modified phosphogypsum, 30 parts slag powder, 20 parts ordinary silicate cement, 3 parts highly active solid waste material, 2.5 parts polycarboxylate superplasticizer, and a water-to-solid ratio of 0.2.

[0040] The preparation process of modified phosphogypsum is as follows: 3% by weight of carbide slag is added to the phosphogypsum, mixed evenly, and then crushed using a double-stage screenless crusher. After aging in stock for 30 hours, the phosphogypsum is obtained. The phosphogypsum used is a product of wet-process phosphoric acid production, with an SO3 content of 46.5%; the carbide slag used has a CaO content of 91% after drying. The slag powder used is S95 grade granulated blast furnace slag powder; the ordinary silicate cement used has a strength grade of 52.5. The highly active solid waste material used is lithium slag, containing 15% Al2O3, 40% SiO2, and 45% CaO by mass percentage. The polycarboxylate superplasticizer used is a liquid polycarboxylate superplasticizer with a solid content of 8%.

[0041] The preparation method of this phosphogypsum artificial stone includes the following steps: (1) Preparation of modified phosphogypsum: 3% of carbide slag by weight of phosphogypsum is added to phosphogypsum, mixed and crushed by a double-stage screenless crusher, and then piled up for aging treatment for 30 hours. (2) Slurry preparation: Mix modified phosphogypsum, slag powder, ordinary silicate cement and high-activity solid waste material and stir at 40 r / min for 2 min, then add water and polycarboxylate superplasticizer, and continue stirring at 40 r / min for 10 min. (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 28 days at 20℃ and 70% relative humidity.

[0042] The prepared phosphogypsum artificial stone has an apparent density of 2085 kg / m³, a 7-day cubic compressive strength of 16.3 MPa, a 28-day cubic compressive strength of 48.3 MPa, and a softening coefficient of 0.92.

[0043] The difference between Comparative Example 1 and Example 1 is that the phosphogypsum was not modified by carbide slag and was used directly in its original state; otherwise, it was the same as Example 1.

[0044] The difference between Comparative Example 2 and Example 1 is that the amount of carbide slag used is 0.5% of phosphogypsum, while the rest is the same as in Example 1.

[0045] The difference between Comparative Example 3 and Example 1 is that the amount of carbide slag used is 15% of that of phosphogypsum, while the rest is the same as in Example 1.

[0046] The difference between Comparative Example 4 and Example 1 is that an equal amount of Ca(OH)2 was used to replace the carbide slag for phosphogypsum modification, while the rest was the same as Example 1.

[0047] The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not contain slag powder, but is otherwise the same as Example 1.

[0048] The difference between Comparative Example 6 and Example 1 is that it does not contain ordinary silicate cement, but is otherwise the same as Example 1.

[0049] The difference between Comparative Example 7 and Example 1 is that the aging time in the preparation of modified phosphogypsum is 12 hours, while the rest is the same as in Example 1.

[0050] The difference between Comparative Example 8 and Example 1 is that in the preparation of the slurry, modified phosphogypsum, slag powder, ordinary silicate cement, highly active solid waste material, water and polycarboxylate superplasticizer are mixed together and stirred at 40 r / min for 12 min.

[0051] The difference between Comparative Example 9 and Example 1 is that the molding and curing temperature is 105°C, while the rest is the same as Example 1.

[0052] The apparent density was determined according to the method in GB / T 14685 "Construction Gravel and Crushed Stone", the 28-day cubic compressive strength was determined according to the method in GB / T 50081 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and the softening coefficient was determined with reference to the method in GB-T 17431.2 "Lightweight Aggregates and Their Test Methods Part 2: Test Methods for Lightweight Aggregates". The test results are shown in Table 1.

[0053] Table 1 Performance Test Results

[0054] The results of Examples 1-5 demonstrate that the apparent density of the gypsum lightweight artificial stone of this invention is approximately 2100 kg / m³, which is lighter than that of ordinary limestone (2700 kg / m³), achieving lightweighting, reducing material transportation costs, and making installation more convenient. The phosphogypsum lightweight artificial stone prepared by this invention achieves a 28-day cubic compressive strength of 20 MPa to 60 MPa and a softening coefficient of not less than 0.85, exhibiting excellent mechanical properties and water resistance.

[0055] Compared with Example 1, Comparative Examples 1-3 show that the modification of calcium carbide slag has a significant impact on the performance of phosphogypsum artificial stone. When the amount of calcium carbide slag is in the range of 1-11% of phosphogypsum, the performance improvement effect of phosphogypsum artificial stone is significant. When the amount of calcium carbide slag is less than 1% of phosphogypsum, the 7-day compressive strength of phosphogypsum artificial stone is low. When the amount of calcium carbide slag exceeds 11% of phosphogypsum, the 28-day compressive strength of phosphogypsum artificial stone decreases.

[0056] Compared with Example 1, Comparative Example 4 has similar data in apparent density, compressive strength and softening coefficient. This is because the CaO content of carbide slag is ≥90%. Although the purity of Ca(OH)2 is high when used directly, carbide slag is a type of solid waste. Using carbide slag to replace Ca(OH)2 is more economical and environmentally friendly.

[0057] Compared with Example 1, Comparative Examples 5-6 show that the combination of phosphogypsum, slag powder and cement has a significant synergistic effect. Slag powder (providing later strength) + cement (providing early strength and stimulating solid waste activity) + highly active solid waste (optimizing microstructure) can significantly improve its compressive strength and water resistance.

[0058] Compared with Example 1, Comparative Example 7 shows that the aging time in the phosphogypsum modification was insufficient, and the reaction between the carbide slag and impurities in the phosphogypsum was incomplete, resulting in a lower 7-day compressive strength and a longer setting time for the specimen.

[0059] Compared with Example 1, Comparative Example 8 and Comparative Example 7 show that adding water directly after dry mixing (without step-by-step mixing) will result in uneven mixing of the slurry and the presence of undispersed particles inside, causing increased strength fluctuations. Step-by-step mixing can ensure more uniform mixing and highlight the effectiveness of the water-reducing agent.

[0060] Comparative Example 9, compared with Example 1, demonstrates that a suitable curing temperature can ensure the good performance of phosphogypsum artificial stone. High temperature significantly reduces its apparent density and 28-day compressive strength, while the specimen cracks.

[0061] The applicant declares that the above description is only a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A lightweight artificial stone made of phosphogypsum, characterized in that, The raw materials for its preparation include the following components by weight: 40-70 parts modified phosphogypsum, 17-40 parts slag powder, 5-25 parts ordinary silicate cement, 0-10 parts highly active solid waste material, and 2-4 parts polycarboxylate superplasticizer. The water-to-solid ratio is 0.18–0.25; the modified phosphogypsum is obtained by adding carbide slag to phosphogypsum, mixing and crushing it evenly, and then piling it up for aging.

2. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that, The raw materials for its preparation include the following components by weight: 50-70 parts modified phosphogypsum, 17-30 parts slag powder, 5-20 parts ordinary silicate cement, 3-7 parts highly active solid waste material, and 3-4 parts polycarboxylate superplasticizer.

3. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that, The amount of calcium carbide slag added is 1-11% of the weight of phosphogypsum, the crushing is carried out by a double-stage screenless crusher, and the aging time is ≥24h.

4. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that, The phosphogypsum is a product of wet phosphoric acid production, wherein the SO3 content is >45%; the carbide slag has a CaO content ≥90% after drying.

5. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that, The slag powder is S95 grade granulated blast furnace slag powder; the ordinary silicate cement has a strength grade of 42.5 or 52.

5.

6. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that: The highly active solid waste material contains 0-50% Al2O3, 0-75% SiO2, and 0-50% CaO by mass percentage, and is selected from one or more of metakaolin, fly ash, silica fume, red mud, lithium slag, and stone powder.

7. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that: The polycarboxylate superplasticizer is a liquid polycarboxylate superplasticizer with a solid content of 8%.

8. The phosphogypsum lightweight artificial stone according to claim 1, characterized in that: The apparent density is 2020-2120 kg / m³, the 28-day cubic compressive strength is 20-60 MPa, and the softening coefficient is ≥0.

85.

9. A method for preparing lightweight artificial stone made of phosphogypsum according to any one of claims 1-8, characterized in that... Includes the following steps: (1) Preparation of modified phosphogypsum: Add carbide slag to phosphogypsum, mix and crush by a double-stage screenless crusher, and then pile up for aging treatment for ≥24h. (2) Slurry preparation: Mix modified phosphogypsum, slag powder, ordinary silicate cement and high-activity solid waste material and stir at 20-50 r / min for 1-3 min, then add water and polycarboxylate superplasticizer, and continue stirring at 20-50 r / min for 8-20 min; (3) Molding and curing: After the phosphogypsum artificial stone slurry is molded and finally set, it is cured for 7 to 28 days at 10 to 60°C and relative humidity > 60%.

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