Undisturbed phosphogypsum curing modifier as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of ardealite, and relates to an undisturbed ardealite curing modifier and a preparation method and application thereof, and the modifier comprises the following components by weight: 30.0-35.0% of calcium chloride; 2.5%-3.0% of polyaluminum chloride; 2.0 to 2.5% of dimethyl silicone oil; 0.5 to 1.0 percent of polyacrylamide; 0.5 to 1.0 percent of polyurethane resin; 57.5 to 65.5 percent of water; and lauryl alcohol polyoxyethylene ether, iso-tridecanol polyoxyethylene ether and methanol. Compared with the prior art, the preparation method has the advantages that the free phosphorus element in the phosphogypsum is effectively fixed through the synergistic effect of the polyaluminum chloride and the simethicone, and the free fluorine element is effectively fixed through the reaction of the calcium chloride and the free fluorine, so that the seepage amount of the free phosphorus and the free fluorine is remarkably reduced, and the preparation method has the outstanding environment-friendly characteristic; meanwhile, the mechanical property of the ardealite-based material is also remarkably improved, wide application of the ardealite-based material in multiple fields is ensured, and particularly, the ardealite-based material has important research and application values in research and development of high-performance and environment-friendly building materials.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial solid waste resource utilization and phosphogypsum, and relates to an original phosphogypsum curing modifier and a preparation method and application thereof. Background Art

[0002] As a byproduct of wet phosphoric acid production, phosphogypsum has high resource value, but it usually has problems such as high solubility, strong hygroscopicity, and a large amount of soluble impurities (such as phosphates and fluorides). This significantly increases the chemical activity of phosphogypsum, and its performance in mechanical properties and environmental stability is far from meeting the high requirements of engineering applications, which in turn limits the use of phosphogypsum in building materials. In particular, the leakage of free phosphorus and free fluorine in phosphogypsum seriously affects its environmental safety and causes potential pollution to soil, water sources and plant growth.

[0003] In recent years, the modification technology of phosphogypsum has been widely studied to improve its application performance in building materials. The existing technology mainly improves the performance of phosphogypsum by using modifiers such as mineral admixtures, polymers and methyl silicone oil, but these solutions usually focus on the improvement of a single aspect and lack the comprehensive improvement of the performance of phosphogypsum. For example, the phosphogypsum-based high-fluidity grouting material proposed by Chinese patent CN104628349B improves fluidity and early strength by combining phosphorus-based high-strength gypsum with fly ash, carbide slag and cement; while Chinese patent CN102173709B uses a combination of silicate cement and slag powder to enhance the water resistance and setting time control ability of phosphogypsum. Although these technologies have made breakthroughs, there are still deficiencies in long-term use and control of free phosphorus and free fluorine leakage.

[0004] The existing technology has not effectively solved the problem of free phosphorus and free fluorine leakage in phosphogypsum, especially in terms of long-term use and the impact of humid environment. Therefore, an innovative technical solution is urgently needed to significantly improve the stability, mechanical properties and durability of phosphogypsum with a small amount of addition, especially to reduce the effect of free phosphorus and free fluorine leakage, so as to improve the overall performance. Summary of the invention

[0005] The purpose of the present invention is to provide an original phosphogypsum curing modifier and its preparation method and application, which are used to solve the problem of free phosphorus and free fluorine leakage in phosphogypsum. The present invention effectively fixes the free phosphorus element in phosphogypsum through the synergistic effect of polyaluminium chloride and dimethyl silicone oil, and effectively fixes the free fluorine element through the reaction of calcium chloride and free fluorine, thereby significantly reducing the leakage of free phosphorus and free fluorine, and has outstanding environmentally friendly characteristics; at the same time, it also significantly improves the mechanical properties of phosphogypsum-based materials, ensuring its wide application in multiple fields, especially in the research and development of high-performance and environmentally friendly building materials, which has important research and application value.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The first aspect of the present invention provides an original phosphogypsum curing modifier, comprising the following components and their weight percentages:

[0008] as well as,

[0009] Lauryl alcohol polyoxyethylene ether, isomeric tridecanol polyoxyethylene ether and methanol;

[0010] The mass ratio of the lauryl alcohol polyoxyethylene ether to the isomeric tridecanol polyoxyethylene ether is 1:(2-3), and the total mass of the lauryl alcohol polyoxyethylene ether and the isomeric tridecanol polyoxyethylene ether is 8-12% of the mass of the dimethyl silicone oil.

[0011] The present invention combines anhydrous calcium chloride, polyaluminium chloride, dimethyl silicone oil, polyacrylamide and polyurethane resin to form a composite modifier, and utilizes the synergistic effect thereof to effectively improve the performance of phosphogypsum-based materials. The present invention effectively reduces the amount of free phosphorus and free fluorine in phosphogypsum-based materials through the synergistic effect of polyaluminium chloride (PAC), dimethyl silicone oil and calcium chloride, while improving the mechanical properties, water resistance and long-term stability of the materials. 3+ Phosphate (PO) is fixed by complexation 4 3- ), reducing the release of free phosphorus; dimethyl silicone oil forms a hydrophobic barrier inside the material, reducing the dissolution of phosphate complexes by water migration, and further inhibiting the leakage of phosphorus; Ca released by calcium chloride 2+ Can be used with F - Combined to form insoluble CaF 2Precipitation effectively reduces the solubility of free fluorine. At the same time, calcium chloride can also promote the formation of hydration products, and together with PAC, optimize the pore structure of the material and improve the overall density. Experiments show that when the three work together in an optimized ratio, the fixation effect of phosphorus and fluorine is significantly better than that of a single component. At the same time, the compressive strength, water resistance and durability of the material are all improved, providing an efficient modification strategy for the high-performance application of phosphogypsum.

[0012] In addition, the addition of auxiliary materials such as polyacrylamide and polyurethane resin further improves the rheological properties, crack resistance and durability of phosphogypsum, and significantly improves its stability and construction performance in a humid environment. This composite modification technology provides a new solution for the wide application of phosphogypsum in building materials, especially in the development of environmentally friendly and high-performance building materials, and has broad application prospects.

[0013] In some specific embodiments, the calcium chloride is a white powdery solid.

[0014] In some specific embodiments, the aluminum oxide (Al2O3) in the polyaluminium chloride is 2 O 3 ) has a mass content of not less than 30% and is a white powdery solid.

[0015] In some specific embodiments, the dimethyl silicone oil has a viscosity of 4500-5500 cSt and is a colorless transparent liquid; preferably, the viscosity is 5000 cSt.

[0016] In some specific embodiments, the molecular weight of the polyacrylamide is not less than 5 million and is in the form of a white powdery solid.

[0017] In some specific embodiments, the polyurethane resin is an aqueous polyurethane emulsion with a solid content of 50% to 60%.

[0018] In some specific embodiments, the lauryl alcohol polyoxyethylene ether (AEO-9) is a milky white paste with a cloud point of 70 to 95°C.

[0019] In some specific embodiments, the isomeric tridecanol polyoxyethylene ether (E1309) is a colorless liquid with a hydroxyl value of 94±5 mgKOH / g.

[0020] In some specific embodiments, the mass ratio of lauryl alcohol polyoxyethylene ether to isomeric tridecanol polyoxyethylene ether is 1:2.5, and the total mass of lauryl alcohol polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether accounts for 10% of the total mass of dimethyl silicone oil.

[0021] In some specific embodiments, the methanol is a colorless, odorless, volatile liquid with a purity greater than 99%, and the amount used is 0.3-0.8% of the mass of the dimethyl silicone oil, preferably 0.5% of the mass of the dimethyl silicone oil.

[0022] The second aspect of the present invention provides a method for preparing the original phosphogypsum curing modifier as described above, comprising: heating and stirring calcium chloride, polyaluminum chloride, dimethyl silicone oil, polyacrylamide, polyurethane resin, water, lauryl alcohol polyoxyethylene ether, isomeric tridecyl alcohol polyoxyethylene ether, and methanol at 80-85°C, and letting stand to obtain the result.

[0023] The third aspect of the present invention provides an application of the original phosphogypsum curing modifier as described above, comprising using the original phosphogypsum curing modifier to prepare a phosphogypsum-based material.

[0024] In some specific embodiments, the application method includes: stirring and mixing phosphogypsum, a cementitious material, and an original phosphogypsum curing modifier uniformly, and letting the mixture stand for a certain period of time to allow the modifier to react with the phosphogypsum.

[0025] In some specific embodiments, the application method comprises the following steps:

[0026] (1) stirring phosphogypsum and cement and other cementitious materials at a low speed, weighing a curing modifier and adding it to the mixture;

[0027] (2) stirring rapidly until the curing modifier and the phosphogypsum are fully in contact and uniformly mixed;

[0028] (3) After stirring, let it stand for a certain period of time to ensure that the modifier and phosphogypsum react fully, and finally adjust the operability and apply it to the construction site.

[0029] In some specific implementations, the added amount of the original phosphogypsum curing modifier is 1 to 3% of the mass of the phosphogypsum.

[0030] In the system of the present invention, there are complex physical and chemical interactions between the components, such as ion reaction, interface modification and gelation performance regulation. Therefore, the following key parameters are defined:

[0031] Calcium chloride content (30.0-35.0%):

[0032] Calcium chloride can promote the coagulation of phosphogypsum particles, improve early strength, and adjust the ion balance of the system through chloride ions, which helps to stabilize free phosphorus.

[0033] If the content is too low (<30%), Ca 2+ Insufficient supply, phosphate (PO 4 3-)’s fixation capacity is weakened, resulting in increased free phosphorus leakage and slower early strength development.

[0034] If the content is too high (>35%), it may cause a large amount of CaCl to precipitate. 2 , forming soluble salts, which increase the hygroscopicity and dissolution risk of the material and affect durability.

[0035] Polyaluminium chloride (PAC, 2.5-3.0%):

[0036] PAC by Al 3+ The complexation enhances the stability of the system and effectively reduces the free phosphorus content.

[0037] If the content is too low (<2.5%), Al 3+ If the amount of phosphate is insufficient, phosphate cannot be fully precipitated or fixed, resulting in increased leaching of free phosphorus.

[0038] If the content is too high (>3%), the excess Al in the system 3+ Possibly related to Ca 2+ Compete for adsorption sites, affect the formation of hydration products, and thus reduce the overall mechanical properties of the material.

[0039] Dimethyl silicone oil (2.0-2.5%) and its viscosity (5000cSt):

[0040] As a hydrophobic modifier, dimethyl silicone oil can improve the moisture resistance, durability and pore structure of phosphogypsum-based materials.

[0041] Dimethicone content is too low (<2.0%):

[0042] Phosphogypsum still has strong hygroscopicity, which causes strength degradation due to humidity changes during long-term service, affecting durability.

[0043] Too high content of dimethicone (>2.5%):

[0044] Due to the hydrophobicity of silicone oil, excessive addition may affect the molding properties of the material, making it impossible to distribute evenly in the system, resulting in increased porosity and decreased interfacial bonding strength, thereby reducing compressive strength.

[0045] In addition, too high a silicone oil content will reduce the hydrophilicity of the material, deteriorate the bonding interface between subsequent cementitious materials and phosphogypsum, and affect early strength development.

[0046] Polyurethane resin (0.5-1.0%), solid content (≥60%):

[0047] As a reinforcing agent, waterborne polyurethane can improve the toughness and crack resistance of the material and enhance the density of the gel.

[0048] If the polyurethane resin content is too low (<0.5%):

[0049] Due to insufficient modification, the material's crack resistance is poor, and microcracks may occur during long-term service, reducing durability.

[0050] If the polyurethane resin content is too high (>1.0%):

[0051] Excessive polyurethane may form a polymer-rich phase, resulting in phase separation, reducing the uniformity of the material and affecting the hydration reaction, resulting in reduced strength.

[0052] In addition, the solid content of the waterborne polyurethane emulsion is ≥ 60% to ensure sufficient modification effect. If the solid content is lower than this value, the effective ingredients are insufficient, affecting the mechanical improvement effect of the material.

[0053] Compared with the prior art, the present invention has the following characteristics:

[0054] Fixation of free phosphorus and free fluorine: The present invention effectively reduces the amount of free phosphorus and free fluorine in the phosphogypsum-based material through the synergistic effect of polyaluminium chloride, dimethyl silicone oil and calcium chloride. Experiments show that the free phosphorus leakage of the phosphogypsum-based material prepared by the curing modifier of the present invention is less than 0.09mg / L, and the free fluorine leakage is less than 0.20mg / L, which has outstanding environmentally friendly characteristics;

[0055] Significant improvement in mechanical properties: The present invention, through the synergistic effect of materials such as polyaluminium chloride and dimethyl silicone oil, not only significantly improves the mechanical properties of phosphogypsum-based materials, but also achieves a 7-day compressive strength of 3-3.8 MPa and a 28-day compressive strength of 17-22 MPa, which are significantly higher than the 7-day compressive strength of unmodified phosphogypsum-based materials, which reaches 1.5 MPa and 8.2 MPa respectively. The 28-day compressive strength is increased by 107-168% compared with that of the unmodified material, ensuring its wide application in multiple fields.

[0056] In summary, the present invention proposes a simple and economical modification method, which adopts the synergistic composite modification technology of polyaluminium chloride, dimethyl silicone oil and calcium chloride to comprehensively improve the comprehensive performance of phosphogypsum, especially in mechanical properties and environmental stability. It effectively solves the common strength attenuation, poor moisture resistance and environmental safety problems of phosphogypsum-based materials during use, thereby significantly enhancing its engineering application performance and ensuring its wide application in multiple fields. In particular, it has important research and application value in the research and development of high-performance and environmentally friendly building materials, and provides a scientific basis and strong support for the resource utilization of phosphogypsum. DETAILED DESCRIPTION

[0057] The present invention is described in detail below in conjunction with specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0058] The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

[0059] In the following examples, unless otherwise specified, raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0060] In the following embodiments, phosphogypsum was purchased from Guizhou Gaobang Building Materials Co., Ltd., ordinary silicate concrete was purchased from Anhui Conch Cement Co., Ltd., anhydrous calcium chloride was the 100043-52-4 product of Tianjin Damao Chemical Reagent Partnership (Limited Partnership), polyaluminium chloride was the PA05093 product of Haichuangsai Technology Co., Ltd., dimethyl silicone oil was the LC-200DM5000 product of Jinan Longcheng Silicone Co., Ltd., polyacrylamide was the 9003-05-8 product of Tianjin Damao Chemical Reagent Partnership (Limited Partnership), polyurethane resin was the 2099 product of Guangdong Yuemei Chemical Co., Ltd., lauryl alcohol polyoxyethylene ether AEO-9 was purchased from Hai'an Petrochemical Plant, Jiangsu Province, and isomerized tridecanol polyoxyethylene ether E-1309 was purchased from Hai'an Petrochemical Plant, Jiangsu Province.

[0061] Embodiment 1:

[0062] A raw phosphogypsum curing modifier, the preparation method of which comprises the following steps:

[0063] S1: The following components in percentage by weight are used as raw materials:

[0064] Anhydrous calcium chloride: 30%;

[0065] Polyaluminium chloride: 2.8%;

[0066] Dimethicone: 2.3%;

[0067] Water: 63.4%;

[0068] Polyacrylamide: 0.7%;

[0069] Polyurethane resin: 0.8%;

[0070] It also includes that the mass ratio of cosolvent: AEO-9 to E1309 is 1:2.5, and the total mass of AEO-9 and E1309 accounts for 10% of the total mass of dimethyl silicone oil;

[0071] Methanol: 0.5% of the mass of dimethyl silicone oil;

[0072] S2: Warm-up and preparation:

[0073] Set the thermostatic water bath to 80°C and clean and dry the reaction beaker;

[0074] S3: Adding materials and initial stirring:

[0075] Add water to the beaker and start stirring at high speed;

[0076] Add polyaluminium chloride, dimethyl silicone oil, polyacrylamide, polyurethane resin in order, then add AEO-9, E1309 and methanol;

[0077] S4: High-speed stirring and dissolving:

[0078] Stir for 20 minutes to ensure that all components are completely dissolved and form a uniform and transparent liquid. Ensure that the solution reacts stably, check for uniformity, and avoid precipitation;

[0079] S5: Cooling and post-processing:

[0080] After the stirring was completed, the mixture was cooled to room temperature and allowed to stand for 1 hour.

[0081] Embodiment 2:

[0082] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 1 in that the following components in percentage by weight are used as raw materials:

[0083] Anhydrous calcium chloride: 31.0%;

[0084] Polyaluminium chloride (PAC): 2.7%;

[0085] Dimethyl silicone oil (organic silicone): 2.2%;

[0086] Water (solvent): 62.6%;

[0087] Polyacrylamide (PAM): 0.9%;

[0088] Polyurethane resin: 0.6%;

[0089] Cosolvent: The mass ratio of AEO-9 to E1309 is 1:2.5, and the total mass of AEO-9 and E1309 accounts for 10% of the total mass of dimethyl silicone oil;

[0090] Methanol: 0.5% of the mass of dimethyl silicone oil.

[0091] The rest is the same as in Example 1.

[0092] Embodiment 3:

[0093] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 1 in that the following components in percentage by weight are used as raw materials:

[0094] Anhydrous calcium chloride: 32.0%;

[0095] Polyaluminium chloride (PAC): 2.5%;

[0096] Dimethyl silicone oil (organic silicone): 2.0%;

[0097] Water (solvent): 62.2%;

[0098] Polyacrylamide (PAM): 0.6%;

[0099] Polyurethane resin: 0.7%;

[0100] Cosolvent: The mass ratio of AEO-9 to E1309 is 1:2.5, and the total mass of AEO-9 and E1309 accounts for 10% of the total mass of dimethyl silicone oil;

[0101] Methanol: 0.5% of the mass of dimethyl silicone oil.

[0102] The rest is the same as in Example 1.

[0103] Embodiment 4:

[0104] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 1 in that the following components in percentage by weight are used as raw materials:

[0105] Anhydrous calcium chloride: 33.0%;

[0106] Polyaluminium chloride (PAC): 2.9%;

[0107] Dimethyl silicone oil (organic silicone): 2.4%;

[0108] Water (solvent): 60.4%;

[0109] Polyacrylamide (PAM): 0.8%;

[0110] Polyurethane resin: 0.5%;

[0111] Cosolvent: The mass ratio of AEO-9 to E1309 is 1:2.5, and the total mass of AEO-9 and E1309 accounts for 10% of the total mass of dimethyl silicone oil;

[0112] Methanol: 0.5% of the mass of dimethyl silicone oil.

[0113] The rest is the same as in Example 1.

[0114] Comparative Example 1:

[0115] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0116] No anhydrous calcium chloride was added, and the relative amounts of the other components remained unchanged.

[0117] The rest is the same as in Example 1.

[0118] Comparative Example 2:

[0119] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0120] No polyaluminium chloride was added and the relative amounts of the other components remained unchanged.

[0121] The rest is the same as in Example 1.

[0122] Comparative Example 3:

[0123] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0124] No dimethicone was added, and the relative amounts of the other components remained unchanged.

[0125] The rest is the same as in Example 1.

[0126] Comparative Example 4:

[0127] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0128] Anhydrous calcium chloride was added, but polyaluminium chloride and dimethyl silicone oil were not added, and the relative amounts of the other components remained unchanged.

[0129] The rest is the same as in Example 1.

[0130] Comparative Example 5:

[0131] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0132] Polyaluminium chloride was added, but anhydrous calcium chloride and dimethyl silicone oil were not added, and the relative amounts of the other components remained unchanged.

[0133] The rest is the same as in Example 1.

[0134] Comparative Example 6:

[0135] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0136] Dimethyl silicone oil was added, but anhydrous calcium chloride and polyaluminium chloride were not added, and the relative amounts of the other components remained unchanged.

[0137] The rest is the same as in Example 1.

[0138] Comparative Example 7:

[0139] A raw phosphogypsum curing modifier, the preparation method of which is different from that of Example 3, except that:

[0140] Anhydrous calcium chloride, polyaluminium chloride and dimethyl silicone oil were not added, and the relative amounts of the other components remained unchanged.

[0141] The rest is the same as in Example 1.

[0142] Application examples:

[0143] This example is used to examine the application effects of the above examples and comparative examples in phosphogypsum, and the test method includes:

[0144] A method for adding an original phosphogypsum curing modifier comprises the following steps:

[0145] 1) 5.7 g of the original phosphogypsum curing modifier, 570 g of phosphogypsum with a moisture content of 25%, and 30 g of concrete were dry-mixed to obtain a mixed soil; wherein, the amount of the modifier of Comparative Examples 1-7 was determined based on the amount of Example 3, with the amount of water in the modifier being consistent with that of the phosphogypsum;

[0146] 2) Sample preparation process: The test block was prepared using a 39.1 mm clay sampler (including three-valve membrane, compacting hammer, base, top gland, guide sleeve and other components) purchased from Anhui Hengboli Instrument Technology Co., Ltd. The test block was designed to be a cylindrical reshaped soil test block with a diameter of 39.1 mm and a height of 80 mm. The specific preparation steps are as follows:

[0147] 2-1) Sample preparation materials:

[0148] Mix the components well, ensuring that the materials are evenly distributed.

[0149] 2-2) Sample layer filling:

[0150] Use a clay sampler to divide the mixed soil into four layers, adding appropriate amount of material to each layer to ensure uniform thickness of each layer.

[0151] 2-3) Layered compaction:

[0152] Each layer of material is compacted evenly 15 times using a standard compacting hammer to ensure that the soil is dense and the gaps between layers are reduced. The relevant parameters are as follows:

[0153] Hammer mass: 2.5kg;

[0154] Hammer bottom diameter: 39.1mm (matching with three-valve diaphragm);

[0155] Free fall height: 300mm;

[0156] Test block height: 80mm;

[0157] Number of filling layers: 4 layers;

[0158] Thickness of each layer of filler (before loose laying): about 20mm;

[0159] Thickness of each layer of filler (after compaction): about 18-19mm;

[0160] 2-4) Demolding of test block:

[0161] After compaction, demould and ensure that the surface of the specimen is smooth without cracks or defects.

[0162] 2-5) Maintenance process:

[0163] After demoulding, the test block was wrapped and sealed with a plastic film and placed in a constant temperature and humidity curing box to maintain appropriate temperature and humidity conditions (20°C, 95% relative humidity) to ensure the stability of the sample.

[0164] Test standards include:

[0165] Compressive strength: The test standard is based on GB / T 17671-2021 "Test method for strength of cement mortar";

[0166] Free fluorine content: The HJ 557-2010 horizontal oscillation method is used for sample extraction to ensure that the test results meet the solid waste leaching toxicity evaluation standards; the ion selective electrode method (ISE) is used in combination with the A214 ISE host + 9609BNWP fluoride ion electrode to efficiently determine free fluorine;

[0167] Free phosphorus content: The test standard is HJ 700-2014 "Determination of phosphate in water - ammonium molybdate spectrophotometry"

[0168] Test principle: ammonium molybdate spectrophotometry, phosphate (PO 4 3- ) reacts with ammonium molybdate under acidic conditions to form phosphomolybdic acid heteropolyacid, and then forms a blue complex under the reduction of ascorbic acid (or benzidine), which can be detected by ultraviolet-visible spectrophotometer (UV-Vis) at 880nm, and the phosphate content is calculated based on the absorbance;

[0169] Softening coefficient: The test standard is GB / T 50266-2013 "Test methods for building gypsum and its products";

[0170] Number of freeze-thaw cycles: The test standard is GB / T 50082-2009 "Test method for long-term performance and durability of ordinary concrete.

[0171] The test results are shown in Table 1. The control group is a sample prepared by the above-mentioned adding method but without adding the original phosphogypsum curing modifier.

[0172] Table 1 Summary of experimental results

[0173]

[0174]

[0175] Table 2 Comparison of existing phosphogypsum modification technologies

[0176]

[0177]

[0178] Table 3 Performance indicators

[0179]

[0180] Example 4 Analysis - Optimal Formula

[0181] Highest strength: The compressive strength after 28 days reaches 22MPa, far exceeding the control group (8.2MPa), and has the highest relative improvement rate (168.3%), making it suitable for engineering applications with high strength requirements.

[0182] Best durability: The softening coefficient is the highest (0.8) and the number of freeze-thaw cycles is the highest (60 times), indicating that the material performs well in humid environments and cold regions and has strong resistance to hydrolysis and freeze-thaw damage.

[0183] Balanced comprehensive performance: The leaching amount of phosphorus and fluorine is slightly higher than that of Examples 1-3, but still much lower than that of the control group, ensuring environmental protection performance while ensuring the strength and durability of the material.

[0184] Optimization points: Higher anhydrous calcium chloride (33%) and dimethyl silicone oil (2.4%) content improves the hydration reaction efficiency and water resistance of the material, making it more stable in humid and cold environments.

[0185] Conclusion: The formula of Example 4 takes into account strength, durability and environmental adaptability, and is the most suitable solution for practical engineering applications, especially in extreme environments such as high humidity and high cold.

[0186] Comparative analysis

[0187] Comparative Example 1 (without calcium chloride)

[0188] Impact: The strength decreases significantly (14MPa), the leaching of phosphorus and fluorine increases, and the environmental stability decreases.

[0189] Problem: Loss of calcium chloride results in reduced strength and increased leached contaminants.

[0190] Comparative Example 2 (without polyaluminium chloride)

[0191] Impact: The strength decreases further (10MPa), the phosphorus and fluorine leaching increases further, and the durability deteriorates.

[0192] Problem: Lacking PAC, the material's stability and strength are reduced and cannot meet high performance requirements.

[0193] Comparative Example 3 (without dimethyl silicone oil)

[0194] Impact: Strength drops to 16MPa, durability (softening coefficient and freeze-thaw) decreases, and phosphorus and fluorine leaching increases slightly.

[0195] Problem: The lack of silicone results in poor water resistance and reduced long-term stability.

[0196] This experimental scheme is superior to traditional modification technologies and national standards in terms of compressive strength, phosphorus fixation and durability, and has excellent engineering application value.

[0197] Analysis Conclusion

[0198] Effect of Calcium Chloride (Comparative Example 7 and Comparative Example 4)

[0199] Comparative Example 4 (containing only calcium chloride) is slightly better than Comparative Example 7 (without modifier) ​​in compressive strength, softening coefficient, and freeze-thaw cycle, but its phosphorus fixation capacity is insufficient, indicating that calcium chloride has a certain contribution to strength and solidification of fluorine, but has limited effect on solidifying pollutants.

[0200] Effect of polyaluminium chloride (Comparative Example and Comparative Example 5)

[0201] Comparative Example 5 (containing only polyaluminium chloride) is significantly better than Comparative Example 7 in terms of strength and phosphorus curing, but has a general effect on fluorine curing, indicating that polyaluminium chloride mainly improves strength and significantly reduces phosphorus leaching.

[0202] Effect of dimethyl silicone oil (Comparative Example 7 and Comparative Example 6)

[0203] The softening coefficient and freeze-thaw cycle performance of Comparative Example 6 (containing only dimethyl silicone oil) are improved, but the compressive strength is limited, indicating that dimethyl silicone oil mainly improves durability and does not contribute much to strength.

[0204] Three-component synergistic effect (Example 3 and Comparative Example 1)

[0205] Example 3 (containing calcium chloride + polyaluminum chloride + dimethicone) is significantly better than Comparative Example 1 (without calcium chloride), indicating that the polyaluminum chloride + dimethicone environment can enhance the effect of calcium chloride, and the synergistic effect of the three improves the strength, durability and pollutant curing ability.

[0206] in conclusion

[0207] The effect of a single component is limited, and the synergistic effect of three components is optimal.

[0208] Calcium chloride performs better in the environment of polyaluminium chloride and dimethyl silicone oil, indicating that its effect is affected by the system environment.

[0209] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A raw phosphogypsum curing modifier, characterized in that: Includes the following components and weight percentage: Lauryl alcohol polyoxyethylene ether, isomeric tridecanol polyoxyethylene ether and methanol; The mass ratio of the lauryl alcohol polyoxyethylene ether to the isomeric tridecanol polyoxyethylene ether is 1:(2-3); The total mass of the lauryl alcohol polyoxyethylene ether and isomeric tridecanol polyoxyethylene ether is 8-12% of the mass of the dimethyl silicone oil.

2. The original phosphogypsum curing modifier according to claim 1, characterized in that: The mass content of aluminum oxide in the polyaluminum chloride is not less than 30%.

3. The original phosphogypsum curing modifier according to claim 1, characterized in that: The viscosity of the dimethyl silicone oil is 4500-5500 cSt.

4. The original phosphogypsum curing modifier according to claim 1, characterized in that: The molecular weight of the polyacrylamide is not less than 5 million.

5. The original phosphogypsum curing modifier according to claim 1, characterized in that: The polyurethane resin is an aqueous polyurethane emulsion with a solid content of 50% to 60%.

6. The original phosphogypsum curing modifier according to claim 1, characterized in that: The mass ratio of the lauryl alcohol polyoxyethylene ether to the isomeric tridecanol polyoxyethylene ether is 1:2.5, and the total mass of the lauryl alcohol polyoxyethylene ether and the isomeric tridecanol polyoxyethylene ether accounts for 10% of the total mass of the dimethyl silicone oil.

7. The original phosphogypsum curing modifier according to claim 1, characterized in that: The amount of methanol used is 0.3-0.8% of the mass of the dimethyl silicone oil.

8. A method for preparing the original phosphogypsum curing modifier according to any one of claims 1 to 7, characterized in that: include: Calcium chloride, polyaluminium chloride, dimethyl silicone oil, polyacrylamide, polyurethane resin, water, lauryl alcohol polyoxyethylene ether, isomeric tridecanol polyoxyethylene ether and methanol are heated and stirred at 80-85° C., and allowed to stand to obtain the product.

9. An application of the original phosphogypsum curing modifier according to any one of claims 1 to 7, characterized in that: The original phosphogypsum curing modifier is used to prepare phosphogypsum-based materials. The method comprises the following steps: uniformly mixing the phosphogypsum, the cementitious material and the original phosphogypsum curing modifier and allowing the mixture to stand.

10. The use of the original phosphogypsum curing modifier according to claim 9, characterized in that: The added amount of the original phosphogypsum curing modifier is 1 to 3% of the mass of the phosphogypsum.

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