Modified fluorogypsum-based fireproof coating for steel structure and preparation method thereof

Abstract

The application provides a modified fluorogypsum-based steel structure fireproof coating and a preparation method thereof, and comprises the following steps: 1) mixing and treating carbide slag and fluorogypsum raw materials to obtain a first intermediate; 2) microwave heating treatment of the first intermediate, wherein the microwave heating treatment process comprises primary heating treatment and secondary heating treatment, and a second intermediate is obtained; 3) secondary mixing treatment of the second intermediate and an excitation agent to obtain modified fluorogypsum; wherein the microwave power of the microwave heating treatment is 300W-500W, and the microwave frequency is 2450MHz-2500MHz; the excitation agent comprises at least two of a sulfate, a silicate and a water-soluble aluminum salt. The method eliminates fluorine ions and acidic impurities in fluorogypsum waste residues which are harmful to the human body and the environment, excites the hydration activity of the fluorine ions and the acidic impurities, improves the high-temperature resistance of the fluorine ions and the acidic impurities, and further makes the fluorine ions and the acidic impurities meet the performance requirements of the modified fluorogypsum-based steel structure fireproof coating, and increases the fluorogypsum waste residue consumption path.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant materials technology, and in particular to a modified fluorogypsum-based fireproof coating for steel structures and its preparation method. Background Technology

[0002] Hydrofluoric acid, as a core product of fluorochemicals, generates a large amount of fluorogypsum waste residue during its production process. This waste residue contains a large amount of free fluorine and acidic impurities, which not only cannot be directly recycled, but also pollutes the soil and groundwater if piled up for a long time, hindering the green development of the hydrofluoric acid production industry. This is also a solid waste disposal problem that the industry urgently needs to solve.

[0003] Compared to traditional building material base materials, fluorogypsum has natural advantages such as high temperature resistance, flame retardancy and heat insulation. After modification, it can be used to prepare fireproof coatings, which can not only greatly improve the utilization value of solid waste, but also broaden the source of raw materials for fireproof coatings and reduce production costs, which is in line with the green flame retardant development trend of the building materials industry.

[0004] However, the existing technology for preparing modified fluorogypsum has obvious defects. On the one hand, the existing technology only removes some acidic impurities from the fluorogypsum waste residue, and still leaves free fluorine, so the modified fluorogypsum does not meet environmental protection standards. On the other hand, the existing technology only focuses on improving basic mechanical properties. The modified fluorogypsum has low hydration activity and is not resistant to high temperatures. When used as fireproof coatings, it is prone to cracking and flame retardant failure, and does not meet the usage standards.

[0005] Therefore, the problem of how to remove free fluorine and acidic impurities from fluorogypsum while further improving the hydration activity and temperature resistance of modified fluorogypsum urgently needs to be solved. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing modified fluorogypsum. This method not only effectively removes acidic impurities and free fluorine from fluorogypsum waste residue, but also improves the hydration activity of the modified product, modified fluorogypsum, thereby enhancing its high-temperature resistance.

[0007] The present invention also provides a modified fluorogypsum, which is prepared by the above-described method for preparing modified fluorogypsum. The modified fluorogypsum has the characteristics of low acid impurities and free fluorine, high hydration activity and high temperature resistance.

[0008] This invention also provides a modified fluorogypsum-based fireproof coating for steel structures. This modified fluorogypsum-based fireproof coating for steel structures uses the above-mentioned modified fluorogypsum, which improves environmental compliance, high-temperature flame retardancy and hydration curing stability, while realizing the high-value resource utilization of fluorogypsum solid waste.

[0009] In a first aspect, the present invention provides a method for preparing modified fluorogypsum, comprising the following steps:

[0010] 1) The calcium carbide slag and fluorogypsum raw materials are mixed once to obtain the first intermediate;

[0011] 2) The first intermediate is subjected to microwave heating treatment, the microwave heating treatment process includes a first heating treatment and a second heating treatment to obtain a second intermediate;

[0012] 3) The second intermediate and the activator are mixed twice to obtain the modified fluorogypsum;

[0013] The microwave power of the microwave heating treatment is 300W~500W, and the microwave frequency is 2450MHz~2500MHz.

[0014] The activator includes at least two of sulfates, silicates, and water-soluble aluminum salts.

[0015] Furthermore, the temperature of the first heating treatment is 100℃~120℃, and the time is 20min~30min;

[0016] And / or, the temperature of the secondary heating treatment is 200℃~300℃, and the time is 30min~60min.

[0017] Furthermore, the primary mixing process also includes a grinding process using a grinding aid;

[0018] And / or, the secondary mixing process includes a stirring process;

[0019] And / or, the secondary mixing process may be followed by an aging process.

[0020] Furthermore, based on the mass of the fluorogypsum raw material, the mass content of the grinding aid is 0.05%~0.15%;

[0021] And / or, the stirring speed is 1000 rpm to 3000 rpm, and the stirring time is 3 min to 5 min;

[0022] And / or, the aging treatment time is 2h~3h, and the aging treatment temperature is 40℃~50℃.

[0023] Furthermore, based on the mass of the fluorogypsum raw material, the mass content of the carbide slag is 1% to 5%;

[0024] And / or, based on the mass of the fluorogypsum raw material, the activator has a mass content of 0.5% to 2%.

[0025] Furthermore, the activator also includes a mineral synergist;

[0026] And / or, based on the mass of the fluorogypsum raw material, the sulfate content is 0.3% to 1.0% by mass;

[0027] And / or, based on the mass of the fluorogypsum raw material, the silicate content is 0.2% to 0.8% by mass;

[0028] And / or, based on the mass of the fluorogypsum raw material, the mass content of the water-soluble aluminum salt is 0.1% to 2.0%;

[0029] And / or, based on the mass of the fluorogypsum raw material, the mass content of the mineral synergist is 1% to 3%.

[0030] In a second aspect, the present invention provides a modified fluorogypsum, which is obtained by using the preparation method of the modified fluorogypsum described in the first aspect.

[0031] Thirdly, the present invention provides a modified fluorogypsum-based fire-retardant coating for steel structures, wherein the modified fluorogypsum-based fire-retardant coating for steel structures includes the modified fluorogypsum described in the second aspect.

[0032] Furthermore, based on the mass of the modified fluorogypsum-based fire-retardant coating for steel structures, the modified fluorogypsum-based fire-retardant coating for steel structures comprises the following components in terms of mass content:

[0033] The modified fluorogypsum is 35%~45%.

[0034] fly ash 30%~35%,

[0035] Calcium carbonate 5%~10%,

[0036] Refractory aggregate 10%~16%,

[0037] Flame retardant 1%~2%,

[0038] Latex powder 2%~5%,

[0039] Fiber material 0.1%~0.3%,

[0040] Cellulose ethers 0.1%~0.2%,

[0041] Phase change capsules: 1%~2%.

[0042] Furthermore, the refractory aggregate includes at least one of perlite, vermiculite, and ceramsite;

[0043] And / or, the flame retardant includes magnesium hydroxide and / or aluminum hydroxide;

[0044] And / or, the fiber material includes a first fiber and / or a second fiber;

[0045] And / or, the phase change capsule includes a capsule wall and a capsule core; the capsule wall includes at least one of silicon dioxide, titanium dioxide, zirconium dioxide, polystyrene, polymethyl methacrylate, melamine resin, melamine resin, and urea-formaldehyde resin; the capsule core includes at least one of inorganic crystalline hydrated salt, paraffin wax, sugar alcohol, neopentyl glycol, and trimethylolpropane.

[0046] Furthermore, the refractory aggregate includes a porous structure, and the average pore size of the refractory aggregate is 550μm~830μm;

[0047] And / or, the mass ratio of the first fiber to the second fiber is 1:(1~2);

[0048] And / or, the length of the first fiber is 1mm to 3mm and the diameter is 20μm to 30μm;

[0049] And / or, the second fiber has a length of 6mm to 9mm and a diameter of 20μm to 30μm;

[0050] And / or, the mass ratio of the capsule wall to the capsule core is 1:1.2 to 1:1.5;

[0051] And / or, the average particle size of the phase change capsule is 10 μm to 30 μm.

[0052] The method for preparing modified fluorogypsum provided by this invention involves first mixing carbide slag with fluorogypsum raw materials in a single process. The strong alkalinity of the carbide slag neutralizes the acidic impurities in the fluorogypsum, solidifying free fluoride ions. Then, the mixture is heated in two stages using microwaves at a power of 300W-500W and a frequency of 2450MHz-2500MHz. This process allows for a gradient temperature increase in the reaction, preventing localized high temperatures from damaging the materials and promoting the directional growth of hemihydrate gypsum crystals, forming uniformly sized crystal nuclei that provide highly efficient active sites for subsequent hydration reactions. Furthermore, it effectively removes bound water, ensuring the formation of the second hydration reaction. The intermediate is mainly composed of anhydrous gypsum, with a small amount of hemihydrate gypsum acting as a highly efficient seed crystal, which greatly enhances its gelling activity, thus obtaining a second intermediate. The obtained second intermediate is then mixed with an activator to further enhance the hydration activity of fluorogypsum, allowing the hydration reaction to be more complete and the resulting hydration products to be more compact. This process removes free fluorine and acidic impurities from fluorogypsum, significantly improves the hydration activity of modified fluorogypsum, and optimizes its high-temperature stability, crack resistance, and coking resistance, thereby meeting the requirements of fire resistance, high temperature resistance, and structural stability, achieving a balance between environmental protection and performance.

[0053] The modified fluorogypsum provided by this invention is prepared by the above method. Its main body is the neutralization product of carbide slag and the microwave gradient activated gypsum phase. After two-stage microwave treatment, a homogeneous multiphase structure is formed with anhydrous gypsum as the main component and a small amount of hemihydrate gypsum as the active seed crystal. The anhydrous gypsum phase endows the material with excellent high-temperature stability, and the hemihydrate gypsum seed crystal provides efficient hydration active sites. With the secondary activation of the activator, the hydration reaction is more complete and the product is more dense, which significantly improves the gelling activity, high-temperature stability, crack resistance and coking resistance. The product has the characteristics of low acid impurities, low free fluorine, high hydration activity and high high temperature resistance.

[0054] The modified fluorogypsum-based fireproof coating for steel structures provided by this invention uses the modified fluorogypsum as the key inorganic cementitious substrate. Its anhydrous gypsum-based heat-resistant crystalline phase can maintain a rigid skeleton at high temperatures, and the dense microstructure achieves oxygen and heat insulation. The low acidity and low free fluorine system ensures fire safety, and the high hydration activity makes the coating film dense and structurally stable at high temperatures. Thus, it has excellent fire resistance, heat insulation, low toxicity and environmental protection effects, and improves the fire safety and fire resistance limit of the substrate. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a schematic diagram of the process flow for a specific embodiment of the present invention. Detailed Implementation

[0057] To enable those skilled in the art to better understand the solutions of the present invention, the present invention will be further described in detail below, and the technical solutions in the embodiments of the present invention will be clearly and completely described. The specific embodiments listed below are only for describing the principles and features of the present invention, and the examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] In a first aspect, the present invention provides a method for preparing modified fluorogypsum, comprising the following steps:

[0059] 1) The calcium carbide slag and fluorogypsum raw materials are mixed once to obtain the first intermediate;

[0060] 2) The first intermediate is subjected to microwave heating treatment, which includes a first heating treatment and a second heating treatment to obtain the second intermediate;

[0061] 3) The second intermediate and the activator are mixed twice to obtain modified fluorogypsum;

[0062] Among them, the microwave power of microwave heating treatment is 300W~500W, and the microwave frequency is 2450MHz~2500MHz;

[0063] The activator includes at least two of sulfates, silicates, and water-soluble aluminum salts.

[0064] For example, the microwave power of the microwave heating treatment is any value or a range of any two of the following: 300W, 320W, 340W, 360W, 380W, 400W, 420W, 440W, 460W, 480W, 500W.

[0065] For example, the microwave frequency is any value or a range of any combination of 2450MHz, 2460MHz, 2470MHz, 2480MHz, 2490MHz, 2500MHz, etc. This invention does not limit the source of the fluorogypsum raw material.

[0066] In some example embodiments, the fluorogypsum raw material is fluorogypsum waste residue from a hydrofluoric acid chemical plant, and the fluorogypsum raw material contains free fluorine, acidic impurities, and calcium sulfate.

[0067] In some preferred embodiments, the maximum particle size of the fluorogypsum raw material is 0.5 cm to 1.5 cm.

[0068] For example, the maximum particle size of the fluorogypsum raw material is any value or a range of any combination of 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1 cm, 1.1 cm, 1.2 cm, 1.3 cm, 1.4 cm, and 1.5 cm. In some preferred embodiments, acidic impurities include, but are not limited to, sulfuric acid and / or hydrofluoric acid.

[0069] In some preferred embodiments, the free fluorine content is 0.5% to 2% by mass of the fluorogypsum raw material.

[0070] For example, the mass content of free fluorine is any value or a range of any two of the following: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

[0071] In some preferred embodiments, the mass content of acidic impurities is 0.5% to 5% based on the mass of the fluorogypsum raw material.

[0072] For example, the mass content of acidic impurities is any value or a range of any two of the following: 0.5%, 1.0%, 1.5%, 2%, 2.5%, 3.0%, 3.5%, 4%, 4.5%, 5.0%. In some preferred embodiments, calcium sulfate includes, but is not limited to, anhydrous calcium sulfate.

[0073] In some preferred embodiments, the mass content of anhydrous calcium sulfate is 90% to 97% based on the mass of the fluorogypsum raw material.

[0074] For example, the mass content of anhydrous calcium sulfate is any value or a range of any two of the following: 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%.

[0075] The method for preparing modified fluorogypsum provided by this invention involves first mixing calcium carbide slag with fluorogypsum in a single process. The strong alkalinity of the calcium carbide slag neutralizes acidic impurities, removing these impurities from the fluorogypsum raw material while simultaneously converting free fluoride ions into calcium fluoride, thus removing free fluoride. Next, microwave heating at 300W-500W and 2450MHz-2500MHz is employed to achieve a gradient temperature increase, promoting the directional and uniform growth of hemihydrate gypsum crystals and providing hydration active sites. This process also removes bound water, producing a second intermediate primarily composed of anhydrous gypsum containing a small amount of hemihydrate gypsum active crystals, thereby enhancing gelling activity. The second intermediate is then mixed with an activator to further improve hydration activity, resulting in a more complete hydration reaction and a denser hydration product. This method effectively removes free fluoride and acidic impurities while improving the hydration activity, high-temperature stability, crack resistance, and anti-coking properties of the modified fluorogypsum. It further meets the requirements for fire resistance, high-temperature resistance, and structural stability, while also considering environmental friendliness and performance.

[0076] The aforementioned fluorogypsum raw material undergoes a first and second heat treatment (two-stage gradient microwave heating treatment) to form a multiphase crystal structure with anhydrous gypsum as the main component and a small amount of hemihydrate gypsum as the active seed crystal. The crystal size is uniform, with few defects and high crystallinity. The anhydrous gypsum phase endows the material with excellent high-temperature stability and heat resistance, while the small amount of hemihydrate gypsum seed crystal can significantly induce the rapid hydration reaction and provide a large number of highly active sites. After a second activation with an activator, the particle surface energy and interfacial compatibility are further optimized, promoting a more complete hydration reaction and a denser hydration product, reducing internal pores and defects, thereby improving gelling activity, high-temperature stability, crack resistance, and anti-coking performance.

[0077] The modified fluorogypsum prepared by this invention has a hydration rate of ≥40%, and the early compressive strength of the hydration product of the modified fluorogypsum is 20MPa~35MPa after 3 days.

[0078] The testing method for the hydration rate of modified fluorogypsum is understandable:

[0079] S1. Weigh a certain mass of modified fluorogypsum sample, add a quantitative amount of distilled water according to the standard water-gypsum ratio, and stir evenly in a stirrer to make a clean slurry;

[0080] S2. Quickly pour the neat pulp into the test mold and place it in a curing environment with a temperature of 20±2℃ and a relative humidity of ≥90% for curing;

[0081] S3. When the samples are cured to the specified age, they are taken out and crushed. The hydration is terminated with anhydrous ethanol. After vacuum drying, the contents of unhydrated anhydrous calcium sulfate and the hydration product calcium sulfate dihydrate in the samples are determined by differential scanning calorimetry (DSC) or thermogravimetric analysis (TG).

[0082] S4. Based on the change in phase content before and after hydration, calculate the hydration conversion ratio of anhydrous calcium sulfate per unit time, which is the hydration rate of modified fluorogypsum.

[0083] It is understandable that the test method for the 3-day early compressive strength of the hydration products of modified fluorogypsum refers to the national standard GB / T17669.3-1999.

[0084] In some implementations, the mass content of carbide slag is 1% to 5% based on the mass of the fluorogypsum raw material.

[0085] For example, the mass content of carbide slag is any value or a range of any two of 1%, 2%, 3%, 4%, 5%, etc.

[0086] This invention does not limit the source of carbide slag.

[0087] In some exemplary embodiments, calcium carbide slag is an industrial waste residue generated after the industrial production of acetylene gas. It includes calcium hydroxide, is strongly alkaline, has fine particles, a large specific surface area, and higher reactivity than ordinary lime.

[0088] In some example implementations, the calcium hydroxide content is 70% to 90% by mass of carbide slag.

[0089] For example, the mass content of carbide slag is any value or a range of any two of 70%, 75%, 80%, 85%, 90%, etc.

[0090] In step 1) above, when the calcium carbide slag and fluorogypsum raw material are mixed once, the calcium carbide slag can neutralize the acidic impurities in the fluorogypsum raw material and combine with free fluoride ions in the fluorogypsum to form a stable and insoluble calcium fluoride precipitate. This achieves the neutralization of acidic impurities and the solidification of free fluoride ions, solving the technical problem of fluorogypsum failing to meet environmental standards and polluting the environment from the source. This lays a pure material foundation for subsequent microwave activation treatment and ensures the smooth progress of subsequent modification reactions. The main reaction process in step 1) is shown below:

[0091] 2F - +Ca(OH)₂→CaF₂↓+2OH⁻ - ;

[0092] H2SO4+Ca(OH)2→CaSO4↓+2H2O.

[0093] In some implementations, the primary mixing process also includes a grinding process using a grinding aid.

[0094] In some embodiments, the grinding aid content is 0.05% to 0.15% by mass of the fluorogypsum raw material.

[0095] The mechanochemical effect generated by high-energy grinding not only significantly increases the specific surface area of ​​the material, but also results in the powder (first intermediate) with a Dv90 ≤ 20 μm after grinding, and the Dv50 particle size of some of the first intermediate is in the micrometer range. At the same time, grinding can promote the formation of defects and distortions in anhydrous calcium sulfate crystals, expose high-energy crystal faces, increase internal energy, and initially stimulate hydration activity.

[0096] For example, the mass content of the grinding aid is any value or a range of any two of the following: 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%.

[0097] In some embodiments, the grinding aid includes, but is not limited to, triethanolamine and / or polycarboxylate dispersants.

[0098] In some preferred embodiments, the polycarboxylate dispersant includes, but is not limited to, sodium polyacrylate.

[0099] In some embodiments, the mass ratio of triethanolamine to polycarboxylate dispersant is (2~3):1.

[0100] In some embodiments, the polycarboxylate dispersant has a molecular weight of 6000~12000 g / mol.

[0101] The mass content range of the triethanolamine and polycarboxylate dispersant can reduce the surface energy of particles during the grinding process, prevent fine powder agglomeration, improve material flowability, improve powder wettability, and make the dispersion more uniform when mixed with water in the subsequent process, thereby improving grinding efficiency and reducing energy consumption.

[0102] For example, the mass ratio of triethanolamine to polycarboxylate dispersant is any value or a range of any two of the following: 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, etc.

[0103] For example, the molecular weight of the polycarboxylate dispersant is any value or a range of any two of the following: 6000 g / mol, 7000 g / mol, 8000 g / mol, 9000 g / mol, 10000 g / mol, 11000 g / mol, 12000 g / mol.

[0104] In some embodiments, the abrasive also includes abrasive media.

[0105] In some preferred embodiments, the abrasive media include, but are not limited to, zirconia balls.

[0106] In some preferred embodiments, the diameter of the abrasive media is 3 to 8 mm.

[0107] For example, the diameter of the abrasive media is any value or a range of any two of the following: 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, etc.

[0108] In some preferred embodiments, the grinding energy density of the grinding process is >5 kW·h / t.

[0109] For example, the grinding energy density is any value or a range of any two of the following: 5 kW·h / t, 10 kW·h / t, 15 kW·h / t, 20 kW·h / t, 25 kW·h / t.

[0110] In some preferred embodiments, the grinding process includes the following steps:

[0111] The mixture of carbide slag, fluorogypsum raw material and grinding aid is coarsely ground for 10 to 15 minutes to obtain intermediate grinding particles;

[0112] The intermediate particles were finely ground for 5 to 10 minutes to obtain the first intermediate.

[0113] For example, the coarse grinding time is any value or a range of any two of 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.

[0114] For example, the fine grinding time is any value or a range of any two of the following: 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.

[0115] This invention does not limit the instruments used for coarse grinding. For example, instruments used for coarse grinding include, but are not limited to, ball mills.

[0116] This invention does not limit the instruments used for fine grinding. For example, instruments used for fine grinding include, but are not limited to, planetary grinders.

[0117] In some preferred embodiments, the average particle size of the first abrasive particles is 0.1 to 1 mm.

[0118] For example, the average particle size of the first abrasive particle is any value or a range of any two of the following: 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm.

[0119] In some preferred embodiments, the Dv90 particle size of the first intermediate is ≤20μm.

[0120] It is understandable that the Dv90 particle size measurement method is as follows: a laser particle size analyzer is used to test the powder sample of the first intermediate. Before the test, the sample is dispersed in anhydrous ethanol dispersion medium. After ultrasonic dispersion treatment, the particle size distribution is determined by laser diffraction. The particle size corresponding to the cumulative volume fraction reaching 90% is taken as the Dv90 particle size.

[0121] For example, the Dv90 particle size of the first intermediate is any value or a range of any two of 0.1 μm, 1 μm, 10 μm, 20 μm, etc.

[0122] In some embodiments, the first intermediate includes first particles with a particle size ≥ 200 mesh and a mass content of the first particles < 5% based on the mass of the first intermediate.

[0123] It should be noted that after the above grinding process, the particle size of the first intermediate is significantly reduced, and the maximum particle size of the first particle is <0.5cm.

[0124] In some implementations, the pH of the first intermediate is 8 to 12.

[0125] For example, the pH of the first intermediate is any value of 8, 9, 10, 11, 12, etc., or a range of any two of them.

[0126] In step 1) of the present invention, the first intermediate obtained after the above treatment includes free fluorine and calcium fluoride.

[0127] In some embodiments, the free fluorine content of the first intermediate is 0.01% to 0.03% by mass of the first intermediate.

[0128] For example, the mass content of the free fluorine mentioned above is any value or a range of any two of 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, etc.

[0129] In some embodiments, the calcium fluoride content of the first intermediate is 1% to 4% by mass, based on the mass of the first intermediate.

[0130] For example, the mass content of the calcium fluoride mentioned above is any value or a range of any two of the following: 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%.

[0131] In some embodiments, the crystallinity of calcium fluoride is 85% to 95%.

[0132] For example, the crystallinity of the calcium fluoride described above is any value or a range of any two of the following: 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%.

[0133] Step 1) of the present invention improves the specific surface area and hydration activity of the first intermediate; Step 1) neutralizes the acidity of the fluorogypsum raw material, making the pH of the first intermediate 8~12, which is weakly alkaline, laying the foundation for improving the fire resistance of the material and facilitating subsequent construction operations; at the same time, Step 1) reduces the free fluorine content in the first intermediate by generating the above-mentioned 85%~95% highly crystalline calcium fluoride.

[0134] In addition, the generated calcium fluoride (CaF2) is uniformly dispersed in the system of the first intermediate. CaF2 has excellent chemical stability at high temperature. At the same time, due to its regular crystal form, it can form a "skeleton support" structure in the subsequent preparation of modified fluorogypsum-based fireproof coatings for steel structures, which greatly improves the heat resistance temperature and structural integrity of the modified fluorogypsum-based fireproof coatings for steel structures. It can also be used as a high-temperature resistant filler as a nano-reinforcing phase in the subsequent preparation of modified fluorogypsum-based fireproof coatings for steel structures.

[0135] In step 2) above, microwave heating is performed using microwaves with a power of 300W to 500W and a frequency of 2450MHz to 2500MHz. This power and frequency range of microwaves can achieve gradient heating of the reaction system.

[0136] On the one hand, the gradient heating of this microwave heating treatment can avoid excessive dehydration of dihydrate gypsum caused by excessively high local temperatures, while further accelerating the solid-solid reaction remaining in the first intermediate system, ensuring the effect of neutralizing acidic impurities. On the other hand, this microwave heating treatment can uniformly heat the first intermediate, promoting a uniform internal temperature distribution, which not only shortens the reaction time but also promotes the directional growth of hemihydrate gypsum crystals, forming uniformly sized crystal nuclei. These crystal nuclei can provide highly efficient active sites for subsequent hydration reactions. At the same time, by precisely controlling the microwave power and time, the phase composition of gypsum in the material can be directionally regulated: after removing the bound water in the first intermediate, a second intermediate is obtained. The second intermediate is mainly composed of anhydrous gypsum, while containing a small amount of hemihydrate gypsum as highly efficient crystal seeds, which greatly improves the gelling activity of the material and solves the technical problem of low hydration activity of existing modified fluorogypsum.

[0137] Specifically, microwave gradient heating can steadily and uniformly raise the system temperature, resulting in a uniform temperature field distribution within the material. This provides a stable kinetic environment for the phase transformation of dihydrate gypsum to hemihydrate gypsum. The first heating treatment involves low temperature followed by heating, enabling a slow and uniform dehydration process. This forms a moderate number of uniformly distributed crystal nuclei, suppressing grain disorder caused by a large number of instantaneous nuclei. The second heating treatment is a constant-temperature heating process, which removes bound water from the first intermediate, further providing continuous and stable energy for crystal growth. This allows gypsum crystals to grow in an orderly manner along the preferred crystallization direction. Simultaneously, the overall microwave heating eliminates local overheating and temperature differences, inhibiting abnormal grain growth and deformed growth. This achieves directional, uniform, and regular growth of hemihydrate gypsum seed crystals, forming active seed crystals with uniform size and consistent crystal orientation.

[0138] In addition, microwave treatment saves 30% to 50% more energy than traditional kiln heating, and heats up rapidly without secondary pollution. Compared with traditional resistance heating, microwave heating has the characteristics of selectivity, integrity and instantaneity.

[0139] In some embodiments, the temperature of a single heat treatment is 100°C to 120°C, and the time is 20 min to 30 min.

[0140] For example, the temperature of the above-mentioned single heating treatment is any value or a range of any two of 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 112℃, 114℃, 116℃, 118℃, 120℃, etc., and the time is any value or a range of any two of 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min, etc.

[0141] A single heat treatment can slowly evaporate and neutralize the extra moisture produced by the reaction, preventing excessive moisture from causing anhydrous gypsum to overhydrate and form dihydrate gypsum.

[0142] In some embodiments, the temperature of the secondary heat treatment is 200℃~300℃, and the time is 30min~60min.

[0143] For example, the temperature of the above-mentioned secondary heating treatment is any value or a range of any two of 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, etc., and the time is any value or a range of any two of 30min, 35min, 40min, 45min, 50min, 55min, 60min, etc.

[0144] The secondary heating process dehydrates the dihydrate gypsum remaining after the primary heating process into hemihydrate gypsum (3%~5%) and anhydrous gypsum. This ensures the purity of the preparation (anhydrous calcium sulfate content ≥95%) and, through the directional arrangement of hemihydrate gypsum crystals, provides activation anchor points for subsequent activation, thereby improving the stability of the hydration rate of the modified fluorogypsum.

[0145] In some embodiments, the second intermediate includes anhydrous gypsum; the anhydrous gypsum spontaneously hydrates upon cooling, contact with trace amounts of residual moisture or air moisture to form a dense gypsum dihydrate passivation film.

[0146] In step 3) above, the second intermediate and the activator are mixed for a second time. The activator further activates the hydration activity of the modified fluorogypsum, making the structure of the hydration products generated by the modified fluorogypsum more compact. This optimizes the high-temperature stability, crack resistance and coking resistance of the modified fluorogypsum, enabling it to meet the high-temperature resistance and structural stability requirements of the modified fluorogypsum-based fireproof coating for steel structures. Ultimately, this achieves the resource utilization of fluorogypsum solid waste, taking into account both environmental protection and performance.

[0147] In some embodiments, the activator content is 0.5% to 6.8% by mass of the fluorogypsum raw material.

[0148] For example, the mass content of the above-mentioned activator is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3 ... The range of any value or any combination of two of the following: 0.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%.

[0149] The activator of the present invention includes at least two of sulfates, silicates, and water-soluble aluminum salts.

[0150] In some implementations, the activator also includes a mineral synergist.

[0151] In some preferred embodiments, the sulfate includes, but is not limited to, at least one of potassium sulfate, sodium sulfate, and lithium sulfate.

[0152] In some preferred embodiments, silicates include, but are not limited to, Na2SiO3·9H2O.

[0153] In some preferred embodiments, the water-soluble aluminum salts include, but are not limited to, calcined alum (KAl(SO4)2) and / or aluminum sulfate.

[0154] In some preferred embodiments, the mineral synergist includes, but is not limited to, at least one of ultrafine slag powder, silica fume, and volcanic ash.

[0155] It should be noted that the specific surface area of ​​the above ultrafine slag powder is >600 m². 2 / kg.

[0156] This mineral synergist can synergistically enhance the pore structure of the products after hydration of modified fluorogypsum, thereby improving the long-term strength and durability of the hydrated modified fluorogypsum.

[0157] In some preferred embodiments, the activator includes sulfates, silicates, water-soluble aluminum salts, and mineral synergists.

[0158] The above-mentioned compounding of activators can further stimulate the hydration activity of modified fluorogypsum, thereby optimizing the high-temperature stability, crack resistance, and anti-coking properties of modified fluorogypsum, and improving the long-term strength and durability of hydrated modified fluorogypsum; enabling it to meet the high-temperature resistance and structural stability requirements of modified fluorogypsum-based fireproof coatings for steel structures, and ultimately realizing the resource utilization of fluorogypsum solid waste, taking into account both environmental protection and performance.

[0159] In some embodiments, the sulfate content is 0.3% to 1.0% by mass of the fluorogypsum raw material.

[0160] When the mass content of sulfate is within the above range, it can further and effectively destroy the passivation film on the surface of anhydrous gypsum, accelerate hydration and dissolution, and promote the stable growth of dihydrate gypsum crystals.

[0161] For example, the mass content of the sulfate mentioned above is any value or a range of any two of the following: 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%.

[0162] In some embodiments, the silicate content is 0.2% to 0.8% by mass of the fluorogypsum raw material.

[0163] When the mass content of silicate is within the above range, it can further generate CSH gel and interlock with gypsum crystals, thereby improving the density and structural strength of the hardened body.

[0164] For example, the mass content of the silicate is any value or a range of any two of the following: 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%.

[0165] In some embodiments, the mass content of water-soluble aluminum salt is 0.1% to 2% based on the mass of the fluorogypsum raw material.

[0166] When the mass content of water-soluble aluminum salts is within the above range, it can further promote the overlapping of hydration products, optimize the microstructure, and improve the crack resistance and high-temperature stability of the system.

[0167] For example, the mass content of the above water-soluble aluminum salt is any value or a range of any two of the following: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%.

[0168] In some preferred embodiments, the mass content of calcined alum is 0.5% to 1.5% based on the mass of the fluorogypsum raw material.

[0169] Calcined alum with a mass content within the above range can further synergistically enhance the hydration activation effect, improve the intercrystalline adhesion, and improve the overall stability of the hardened body.

[0170] For example, the mass content of the calcined alum is any value or a range of any two of the following: 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%.

[0171] In some preferred embodiments, the aluminum sulfate content is 0.1% to 0.4% by mass of the fluorogypsum raw material.

[0172] When the mass content of aluminum sulfate is within the above range, the liquid phase ion composition can be further finely controlled, promoting uniform and regular crystal form and improving the uniformity of hydration products.

[0173] For example, the mass content of aluminum sulfate mentioned above is any value or a range of any two of 0.1%, 0.2%, 0.3%, 0.4%, etc.

[0174] In some implementations, the mineral synergist content is 1% to 3% based on the mass of the fluorogypsum raw material.

[0175] When the mass content of the mineral synergist is within the above range, it can further optimize the pore structure of the hydration products of modified fluorogypsum, reduce internal pore defects, and improve long-term strength and durability.

[0176] For example, the mass content of the above-mentioned mineral synergist is any value or a range of any two of 1%, 1.5%, 2%, 2.5%, 3%, etc.

[0177] For example, the activator includes potassium sulfate (K2SO4) and sodium silicate nonahydrate (Na2SiO3·9H2O); wherein, K2SO4 provides a high concentration of SO4. 2- Through the common ion effect, the dense dihydrate gypsum passivation film on the surface of anhydrous gypsum obtained in step 2) is destroyed, accelerating the dissolution of anhydrous gypsum and promoting crystal nucleation. Simultaneously, unstable complex salts are formed on the CaSO4 surface, promoting the conversion of anhydrous gypsum to dihydrate gypsum. The resulting dihydrate gypsum crystals (such as needle-like, rod-like, or plate-like crystals) are interlocked, making the hardened structure more compact. Na2SiO3 hydrolysis provides OH-. - and silicate ions [SiO4] 4- , with Ca in the system 2+ The reaction generates CSH gel, which interweaves and physically interlocks with gypsum crystals, significantly improving the structural strength and density of the hardened body.

[0178] For example, the activator includes calcined alum (KAl(SO4)2) and aluminum sulfate; wherein, the Al in the calcined alum 3+ Hydrogen ions are generated after hydrolysis, which corrode the passivation film of gypsum dihydrate formed in step 2) above, and aluminum hydroxide colloid is generated at the same time. The aluminum hydroxide colloid provides a large number of heterogeneous nucleation sites for the crystallization reaction of gypsum dihydrate, which further improves the strength of modified fluorogypsum.

[0179] In some embodiments, the secondary mixing process includes a stirring process;

[0180] In some implementations, the secondary mixing process is followed by an aging process.

[0181] In some preferred embodiments, the stirring speed is 1000 rpm to 3000 rpm, and the stirring time is 3 min to 5 min;

[0182] For example, the stirring speed is any value or a range of any two of 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, etc.; the time is any value or a range of any two of 3 min, 3.5 min, 4 min, 4.5 min, 5 min, etc.

[0183] In some preferred embodiments, the aging treatment time is 2h to 3h, and the aging treatment temperature is 40℃ to 50℃.

[0184] For example, the aging time is any value or a range of any two of the following: 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h, 3h; and the temperature is any value or a range of any two of the following: 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃.

[0185] The above aging treatment allows the activator to fully adsorb and bind with the second intermediate, ensuring uniform distribution of the activator and avoiding structural defects caused by excessive local activation.

[0186] In a second aspect, the present invention provides a modified fluorogypsum, which is obtained by using the preparation method of the modified fluorogypsum of the first aspect.

[0187] In this invention, modified fluorogypsum possesses gelling activity and high-temperature resistance, thereby providing core strength and fireproof foundation for modified fluorogypsum-based fireproof coatings for steel structures.

[0188] The modified fluorogypsum provided by this invention is obtained by the above-mentioned preparation method of modified fluorogypsum. The modified fluorogypsum has a main structure of calcium fluoride and microwave gradient activated gypsum phase (containing alkaline components such as calcium fluoride, calcium fluoride, sulfate, calcined alum and activator) with carbide slag neutralization product as the main structure. The modified fluorogypsum has the characteristics of low acid impurities and free fluorine, high hydration activity and high temperature resistance.

[0189] Modified fluorogypsum contains calcium fluoride, a fluoride salt that is extremely difficult to dissolve in water and has a melting point as high as 1400℃. It is chemically very stable at high temperatures. When fluorogypsum is added to fire-retardant coatings, it can be used as a functional filler to improve the high-temperature resistance limit of the coating.

[0190] The generated CaF2 is uniformly dispersed in the system and can be used as a high-temperature resistant filler and nano-reinforcing phase. Calcium fluoride exhibits excellent chemical stability at high temperatures, and due to its regular crystal form, it can form a "skeleton support" structure in coatings, significantly improving the coating's high-temperature resistance and structural integrity.

[0191] In some embodiments, the calcium fluoride content of the modified fluorogypsum is 1% to 4% by weight.

[0192] For example, the mass content of calcium fluoride in the modified fluorogypsum is any value or a range of any two of the following: 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%.

[0193] In this invention, the test method for calcium fluoride is in accordance with GB / T 5195.1-2017.

[0194] In some embodiments, the hydration rate of the modified fluorogypsum is ≥40%.

[0195] For example, the hydration rate of the modified fluorogypsum is any value or a range of any two of the following: 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%.

[0196] In some embodiments, the 3-day early compressive strength of the hydration product of modified fluorogypsum is 20 MPa to 35 MPa.

[0197] For example, the aforementioned early compressive strength is any value or a range of any two of the following: 20 MPa, 21 MPa, 22 MPa, 23 MPa, 24 MPa, 25 MPa, 26 MPa, 27 MPa, 28 MPa, 29 MPa, 30 MPa, 31 MPa, 32 MPa, 33 MPa, 34 MPa, 35 MPa.

[0198] Thirdly, the present invention provides a modified fluorogypsum-based fireproof coating for steel structures, the modified fluorogypsum-based fireproof coating for steel structures comprising the modified fluorogypsum as described in the second aspect.

[0199] The modified fluorogypsum-based fire-retardant coating for steel structures provided by this invention uses the modified fluorogypsum as the key inorganic cementitious substrate. Its heat-resistant crystalline structure, primarily composed of anhydrous gypsum, is not easily dehydrated, decomposed, melted, or softened at high temperatures. This allows it to maintain a complete and continuous inorganic rigid skeleton under flame conditions, preventing the coating from softening, flowing, powdering, and peeling off. The hydration products of the modified fluorogypsum possess a dense structure, resulting in a similarly dense microstructure within the modified fluorogypsum-based fire-retardant coating. This effectively blocks heat conduction, oxygen penetration, and flame erosion, forming a continuous and stable heat-insulating and oxygen-barrier protective layer, thus delaying the temperature rise of the substrate. Furthermore, modified fluorogypsum contains cured free fluorine (calcium fluoride) and a low-acid system after acid-base neutralization (removal of acidic impurities). Utilizing the aforementioned properties of modified fluorogypsum, the coating can prevent the release of toxic and harmful substances such as hydrogen fluoride and acidic fumes at high temperatures, thus improving fire safety. Its high hydration activity makes the coating film denser and more cohesive, preventing cracking, coking, and powdering at high temperatures, and maintaining the integrity of the coating structure over a long period. Therefore, modified fluorogypsum-based fireproof coatings for steel structures possess excellent fire resistance and heat insulation, structural stability, high-temperature crack resistance, low toxicity, and environmental friendliness, significantly improving the fire safety and fire resistance limit of the substrate.

[0200] In some embodiments, the modified fluorogypsum-based fire-retardant coating for steel structures comprises the following components by mass:

[0201] Modified fluorogypsum 35%~45%,

[0202] fly ash 30%~35%,

[0203] Calcium carbonate 5%~10%,

[0204] Refractory aggregate 10%~16%,

[0205] Flame retardant 1%~2%,

[0206] Latex powder 2%~5%,

[0207] Fiber material 0.1%~0.3%,

[0208] Cellulose ethers 0.1%~0.2%,

[0209] Phase change capsules: 1%~2%.

[0210] Within this mass ratio range, the components can achieve synergistic effects, and the reasonable proportion of each component makes the overall performance of the modified fluorogypsum-based fireproof coating for steel structures optimal, meeting the requirements for fireproof use.

[0211] Modified fluorogypsum, comprising 35%–45% as the core substrate, provides excellent high-temperature resistance, cementing properties, and environmental friendliness, laying the foundation for modified fluorogypsum-based fire-retardant coatings for steel structures. Fly ash, comprising 30%–35%, synergistically enhances the high-temperature resistance and mechanical strength of the modified fluorogypsum-based fire-retardant coatings for steel structures, while further realizing the resource utilization of solid waste. Calcium carbonate, comprising 5%–10%, optimizes the structural density of the composition, improving the hardness and wear resistance of the coating. Refractory aggregate, comprising 10%–16%, enhances the thermal insulation effect of the composition, further improving… High temperature resistance; 1%~2% flame retardant can enhance the flame retardant properties of the composition and inhibit the combustion reaction; 2%~5% latex powder can improve the film-forming properties and flexibility of the composition and enhance the adhesion between the coating and the substrate; 0.1%~0.3% fiber material can enhance the crack resistance of the composition and prevent the coating from cracking at high temperatures; 0.1%~0.2% cellulose ether can optimize the workability of the composition and improve the uniformity of the coating; 1%~2% phase change capsules can achieve temperature regulation, absorb heat at high temperatures, and further improve the heat insulation effect.

[0212] For example, the modified fluorogypsum can be any value or a range of any two of the following: 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%.

[0213] For example, any value or a range of any two of the following fly ash percentages: 30%, 31%, 32%, 33%, 34%, 35%.

[0214] For example, any value or a range of any two of the following: calcium carbonate 5%, 6%, 7%, 8%, 9%, 10%.

[0215] For example, any value or a range of any two of the following: refractory aggregates, such as 10%, 11%, 12%, 13%, 14%, 15%, 16%.

[0216] For example, any value or a range of any two of the following flame retardant percentages: 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

[0217] For example, any value or a range of any two of the following latex powders: 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0218] For example, the fiber material may be any value or a range of any two of the following: 0.1%, 0.15%, 0.2%, 0.25%, 0.3%.

[0219] For example, the cellulose ether is any value or a range of any two of the following: 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%.

[0220] For example, the phase change capsule may contain any value or a range of any two of the following: 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

[0221] In some embodiments of the present invention, the modified fluorogypsum-based fire-retardant coating for steel structures is prepared through the following process:

[0222] 1) Modified fluorogypsum, fly ash, calcium carbonate, refractory aggregate, flame retardant, latex powder, and cellulose ether are mixed three times to obtain the first mixture;

[0223] 2) The first mixture and the solvent are mixed four times to obtain the second mixture;

[0224] 3) The second mixture, fiber material, and phase change capsule are mixed five times to obtain a modified fluorogypsum-based fireproof coating for steel structures.

[0225] In some preferred embodiments, the time for the three mixing processes is 10 min to 15 min; the three mixing processes include stirring at a speed of 150 to 200 r / min.

[0226] For example, the mixing time for the three mixing processes is any value or a range of any two of 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.; the stirring speed is 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min, 200 r / min.

[0227] In some preferred embodiments, the time for the four mixing processes is 3 to 5 minutes.

[0228] For example, the time for the four mixing processes is any value or a range of any two of the following: 3 min, 3.5 min, 4 min, 4.5 min, 5 min, etc.

[0229] In some preferred embodiments, the solvent content is 60% to 70% by mass, based on the first mixture.

[0230] For example, the mass content of the solvent is any value or a range of any two of the following: 60%, 62%, 64%, 66%, 68%, 70%.

[0231] In some preferred embodiments, the solvent includes, but is not limited to, water.

[0232] In some preferred embodiments, the temperature of the solvent is 25°C to 35°C.

[0233] For example, the temperature of the solvent is any value of 25°C, 30°C, 35°C, etc., or a range of any combination of both.

[0234] The solvent within this temperature range facilitated the dissolution of cellulose ethers and the activation of latex powder, improving the flowability of the four mixing processes.

[0235] In some preferred embodiments, the four mixing processes include stirring at a speed of 60 r / min to 150 r / min.

[0236] For example, the four mixing processes include stirring at a speed of any value or a range of any two of the following: 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, 120 r / min, 130 r / min, 140 r / min, 150 r / min.

[0237] In some preferred embodiments, the time for the five mixing processes is 2 to 3 minutes.

[0238] For example, the time for the five mixing processes is any value or a range of any two of the following: 2 min, 2.2 min, 2.4 min, 2.6 min, 2.8 min, 3 min, etc.

[0239] In some preferred embodiments, the five mixing processes include stirring at a speed of 60 r / min to 100 r / min.

[0240] For example, the five mixing processes include stirring at a speed of any value or a range of any two of the following: 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min.

[0241] This invention does not limit the apparatus used for the three-stage mixing process. Exemplary apparatuses for the three-stage mixing process include, but are not limited to, a double-helix conical mixer. The double-helix conical mixer has a double-helix structure that can prevent localized agglomeration of raw materials, resulting in a mixing uniformity of ≥95% for the first mixture.

[0242] The present invention does not limit the apparatus used for the four-stage mixing process. Exemplary apparatuses for the four-stage mixing process include, but are not limited to, a double-helix conical mixer.

[0243] In some preferred embodiments, the refractory aggregate includes at least one of perlite, vermiculite, and ceramsite.

[0244] Perlite, vermiculite, and ceramsite all possess excellent high-temperature resistance and thermal insulation properties. As refractory aggregates, they can effectively enhance the thermal insulation effect and high-temperature stability of modified fluorogypsum-based fireproof coatings for steel structures, thus meeting fireproof application requirements.

[0245] In some preferred embodiments, the refractory aggregate includes a porous structure, and the average pore size of the refractory aggregate is 550 μm to 830 μm.

[0246] For example, the average pore size of the refractory aggregate is any value or a range of any two of the following: 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 830 μm, etc.

[0247] The aforementioned porous structure can effectively store air, further enhancing the thermal insulation performance of the modified fluorogypsum-based fireproof coating for steel structures, while ensuring the stability of the bond between the aggregate and other components.

[0248] The flame retardant of this invention, in synergy with calcium fluoride, forms a dual flame retardant system in both the gas and condensed phases, which inhibits the volatilization of combustibles, blocks oxygen contact, and further improves high-temperature resistance.

[0249] In some embodiments, the flame retardant includes magnesium hydroxide and / or aluminum hydroxide.

[0250] Magnesium hydroxide and / or aluminum hydroxide can decompose and absorb heat at high temperatures, releasing water vapor, which inhibits the combustion reaction and forms a dense flame-retardant protective layer, further improving the flame-retardant properties of the composition.

[0251] In some preferred embodiments, the mass ratio of magnesium hydroxide to aluminum hydroxide is 1:(1~2).

[0252] For example, the mass ratio of magnesium hydroxide to aluminum hydroxide is any value or a range of any two of the following: 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, etc.

[0253] The flame retardants of the present invention include modified or unmodified flame retardants; wherein, the modification method of the flame retardant is not limited, and by way of example, the modified flame retardant includes a flame retardant modified with silane coupling agent (KH-550).

[0254] The above-mentioned silane coupling agent (KH-550) modification can improve the compatibility with the base material; it can decompose and release water of crystallization at high temperature.

[0255] In some preferred embodiments, the fibrous material includes a first fiber and / or a second fiber.

[0256] In some preferred embodiments, the mass ratio of the first fiber to the second fiber is 1:(1~2).

[0257] For example, the mass ratio of the first fiber and the second fiber is any value or a range of any two of the following: 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, etc.

[0258] In some preferred embodiments, the length of the first fiber is 1 mm to 3 mm and the diameter is 20 μm to 30 μm.

[0259] For example, the length of the first fiber is any value or a combination of any two of the following: 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., and the diameter is any value or a combination of any two of the following: 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, etc.

[0260] In some preferred embodiments, the second fiber has a length of 6 mm to 9 mm and a diameter of 20 μm to 30 μm.

[0261] For example, the length of the second fiber is any value or a combination of any two of the following: 6 mm, 7 mm, 8 mm, 9 mm, etc., and the diameter is any value or a combination of any two of the following: 20 μm, 22 μm, 24 μm, 26 μm, 28 μm, 30 μm, etc.

[0262] The two types of fibers work synergistically to balance the flexibility and crack resistance of the composition. The first fiber, 1mm to 3mm in diameter, fills the internal pores, while the second fiber, 6mm to 9mm in diameter, enhances the crack resistance of the modified fluorogypsum-based fireproof coating for steel structures.

[0263] In some preferred embodiments, the first fiber includes, but is not limited to, one of polypropylene fiber, polyester fiber, and polyamide fiber.

[0264] Polypropylene fibers melt at high temperatures to form microporous channels, releasing internal stress and preventing the coating from cracking at high temperatures.

[0265] In some preferred embodiments, the second fiber includes, but is not limited to, one of polyvinyl alcohol fiber, water-soluble polyethylene glycol fiber, or hydroxypropyl methylcellulose fiber.

[0266] Polyvinyl alcohol fibers can improve the adhesion strength of coatings.

[0267] In some preferred embodiments, the phase change capsule includes a capsule wall and a capsule core; the capsule wall includes at least one of silicon dioxide, titanium dioxide, zirconium dioxide, polystyrene, polymethyl methacrylate, melamine resin, melamine resin, and urea-formaldehyde resin; the capsule core includes at least one of inorganic crystalline hydrated salt, paraffin wax, sugar alcohol, neopentyl glycol, and trimethylolpropane.

[0268] This invention does not limit the method of preparing phase change capsules. However, by way of example and not limitation, the method of preparing phase change capsules includes the following steps:

[0269] 1) Preparation of core material: Mix and melt phase change material (such as paraffin) with stabilizer, cool and then pulverize into micro powder;

[0270] 2) Preparation of capsule wall material: Dissolve a high-temperature resistant and well-sealing material (such as siloxane resin or polyvinylidene fluoride) in an organic solvent;

[0271] 3) Microencapsulation: The capsule core powder is dispersed in the capsule wall material by in-situ polymerization, and the reaction conditions are controlled to allow the capsule wall material to be deposited on the surface of the capsule core to form a film;

[0272] 4) Curing treatment: The capsule wall material is cross-linked and densified through drying or high-temperature curing;

[0273] 5) Post-processing: Remove residual solvent to obtain phase change capsules with high temperature resistance and excellent sealing performance.

[0274] This method ensures stable encapsulation of the core material and optimizes the thermal insulation performance of the modified fluorogypsum-based fireproof coating for steel structures through a phase change endothermic-exothermic cycle when the temperature changes.

[0275] The phase change capsule of this invention has a capsule wall material with good high temperature resistance and sealing properties, which can protect the core material and ensure its stable existence. The core material can undergo a phase change when the temperature changes. By adjusting the temperature gradient of the modified fluorogypsum-based steel structure fireproof coating through the heat absorption-heat release cycle, it absorbs or releases heat, further optimizes the heat insulation effect of the modified fluorogypsum-based steel structure fireproof coating, extends the fire resistance time and improves the thermal stability of the coating, and broadens the application range of the modified fluorogypsum-based steel structure fireproof coating.

[0276] In some embodiments, the mass ratio of the capsule wall to the capsule core is 1:1.2 to 1:1.5.

[0277] In some embodiments, the average particle size of the phase change capsules is 10 μm to 30 μm.

[0278] For example, the mass ratio of the capsule wall to the capsule core is any value or a range of any two of the following: 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc.

[0279] For example, the average particle size of the phase change capsule is any value or a range of any two of the following: 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, etc.

[0280] The average particle size range of the aforementioned phase change capsules allows them to be uniformly dispersed in the modified fluorogypsum-based fire-retardant coating for steel structures, ensuring consistent temperature regulation in all areas, further enhancing the heat insulation and fire resistance of the composition, and guaranteeing the stability of the fire-retardant effect.

[0281] The modified fluorogypsum-based fireproof coating for steel structures of the present invention, after being applied and molded (the method of application and molding treatment refers to GB 14907-2018 "Fireproof Coatings for Steel Structures"), yields a fire-resistant coating. When this fire-resistant coating is cured under ambient temperatures of 5℃~35℃ and relative humidity of 50%~80%, the bonding strength of the fire-resistant coating is ≥0.32 MPa, and the compressive strength of the fire-resistant coating is ≥2.5 MPa.

[0282] Figure 1 This is a schematic diagram of the process flow for a specific embodiment of the present invention.

[0283] To further understand the present invention, the technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0284] The present invention will be further described below with reference to specific embodiments.

[0285] Unless otherwise specified, all reagents involved in the embodiments of this invention are commercially available products and can be obtained through commercial channels.

[0286] The fluorogypsum raw materials used in the following examples and comparative examples are derived from fluorogypsum waste residue from Jiangxi Wofu Chemical Technology Co., Ltd.; wherein, the maximum particle size of the fluorogypsum raw materials is 0.5cm~1.5cm, the free fluorine content is 0.5%~2%, the acid content is 0.5%~5%, and the anhydrous calcium sulfate content is 90%~97%.

[0287] Example 1

[0288] A method for preparing modified fluorogypsum:

[0289] 1) The carbide slag, grinding aid and fluorogypsum raw material are ground by a segmented grinding mill. First, the material is coarsely ground in a ball mill for 10 minutes to obtain intermediate particles. Then, the intermediate particles are finely ground in a planetary grinding mill for 5 minutes to obtain the first intermediate (Dv90 particle size ≤ 20μm).

[0290] The grinding aids include triethanolamine, polycarboxylate dispersant (sodium polyacrylate, Sigma 447013), and grinding media; the mass ratio of triethanolamine to polycarboxylate is 2:1; the molecular weight of the polycarboxylate dispersant is 10000 g / mol; the grinding media are zirconia balls with a diameter of 3 mm and a grinding energy density of 5.5 ± 0.5 kW·h / t;

[0291] The mass content of carbide slag is 1% based on the mass of fluorogypsum raw material;

[0292] The grinding aid content is 0.05% based on the mass of the fluorogypsum raw material.

[0293] 2) The first intermediate was placed in a microwave heating treatment device and heated at 100°C for 20 min (first heating treatment), and then heated to 200°C and kept at that temperature for 30 min (second heating treatment) to obtain the second intermediate;

[0294] The microwave power of the microwave heating treatment device is controlled at 300W and the microwave frequency is 2450MHz.

[0295] 3) Add an activator to the second intermediate, and then mix it in a high-efficiency mixer at 3000 rpm for 3 minutes to fully homogenize it. After mixing evenly, age it at 50°C for 2 hours to obtain modified fluorogypsum G1.

[0296] Of which, based on the mass of fluorogypsum raw material, the mass content of activator is 2.1%;

[0297] Based on the mass of the fluorogypsum raw material, the activator includes the following components in the following mass contents: 0.3% K2SO4, 0.2% Na2SiO3·9H2O, 0.5% calcined alum (KAl(SO4)2), 0.1% aluminum sulfate, and 1% silica fume.

[0298] Example 2

[0299] It is basically the same as Example 1, except that the microwave power is 400W.

[0300] Example 3

[0301] It is basically the same as Example 1, except that the microwave power is 500W.

[0302] Example 4

[0303] It is basically the same as Example 1, except that the microwave frequency is 2470MHz.

[0304] Example 5

[0305] It is basically the same as Example 1, except that the microwave frequency is 2500MHz.

[0306] Example 6

[0307] It is basically the same as Example 1, except that the temperature of the secondary heating treatment is 260°C.

[0308] Example 7

[0309] It is basically the same as Example 1, except that the temperature of the secondary heating treatment is 300°C.

[0310] Example 8

[0311] It is basically the same as Example 1, except that the second heating treatment time is 45 minutes.

[0312] Example 9

[0313] It is basically the same as Example 1, except that the second heating treatment time is 60 minutes.

[0314] Example 10

[0315] A modified fluorogypsum-based fire-retardant coating for steel structures, using the modified fluorogypsum prepared in Example 1, comprises, by weight, the components shown in Table 1. The preparation of the modified fluorogypsum-based fire-retardant coating for steel structures using the components shown in Table 1 includes the following steps:

[0316] Modified fluorogypsum, fly ash, calcium carbonate, refractory aggregate, flame retardant, latex powder, and cellulose ether were added to a double-helix conical mixer and stirred at 200 r / min for 15 min to obtain the first mixture.

[0317] Add the dry mixture to the double helix cone mixer, then slowly add warm water at 35°C, the total amount of which is 70% of the mass of the dry mixture. Stir for 5 minutes at a speed of 105 r / min to form a second mixture.

[0318] At a rotation speed of 80 r / min, the phase change capsules and mixed length fibers were placed into the second mixture and stirred at 80 r / min for 3 min to ensure that they were uniformly dispersed without being damaged, thus obtaining the modified fluorogypsum-based fireproof coating for steel structures F1.

[0319] The modified fluorogypsum used was the modified fluorogypsum prepared in Example 1; the calcium carbonate used was heavy calcium carbonate powder; the refractory aggregate used was ceramsite with an average pore size of 700 μm; the flame retardant included silane coupling agent modified magnesium hydroxide and silane coupling agent modified aluminum hydroxide in a mass ratio of 1:2; the latex powder used was redispersible latex powder (purchased from Benedec, with a particle size distribution of 80-100 mesh); the cellulose ether was methylcellulose (Wengjiang Reagent PA04112); the phase change capsule included a capsule wall and a capsule core; the capsule wall included silica; the capsule core included paraffin wax; the mass ratio of the capsule wall to the capsule core was 1:1.25; the average particle size of the phase change capsule was 20 μm; the mixed length fibers included polypropylene short fibers and polypropylene long fibers in a mass ratio of 1:1.5; the polypropylene short fibers had a length of 3 mm and a diameter of 30 μm, and the polypropylene long fibers had a length of 6 mm and a diameter of 30 μm.

[0320] Example 11

[0321] The results are essentially the same as in Example 10, except for the component content as shown in Table 1. A modified fluorogypsum-based fire-retardant coating for steel structures, F2, was obtained.

[0322] Example 12

[0323] The results are essentially the same as in Example 10, except for the component content as shown in Table 1. Modified fluorogypsum-based fire-retardant coating for steel structures, F3, was obtained.

[0324] Table 1

[0325]

[0326] Comparative Example 1

[0327] 1) The carbide slag, grinding aid and fluorogypsum raw material are ground by a segmented grinding mill. First, the material is coarsely ground in a ball mill for 10 minutes to obtain intermediate particles. Then, the intermediate particles are finely ground in a planetary grinding mill for 5 minutes to obtain the first intermediate (Dv90 particle size ≤ 20μm).

[0328] The grinding aid includes triethanolamine, polycarboxylate dispersant (sodium polyacrylate, Sigma 447013), and grinding media; the mass ratio of triethanolamine to polycarboxylate dispersant is 2:1; the molecular weight of polycarboxylate dispersant is 10000 g / mol; the grinding media are zirconia balls with a diameter of 3 mm and a grinding energy density of 5.5 ± 0.5 kW·h / t;

[0329] The mass content of carbide slag is 1% based on the mass of fluorogypsum raw material;

[0330] The grinding aid content is 0.05% based on the mass of the fluorogypsum raw material.

[0331] 2) The first intermediate was placed in a microwave heating treatment device and heated at 100°C for 20 min (first heating treatment), and then heated to 200°C and kept at that temperature for 30 min (second heating treatment) to obtain the second intermediate;

[0332] The microwave power of the microwave heating treatment device is controlled at 100W and the microwave frequency is 2450MHz.

[0333] 3) Add an activator to the second intermediate, and then mix it in a high-efficiency mixer at 3000 rpm for 3 minutes to fully homogenize it. After mixing evenly, age it at 50°C for 2 hours to obtain modified fluorogypsum D1.

[0334] Of which, based on the mass of fluorogypsum raw material, the mass content of activator is 2.1%;

[0335] Based on the mass of the fluorogypsum raw material, the activator includes the following components in the following mass contents: 0.3% K2SO4, 0.2% Na2SiO3·9H2O, 0.5% calcined alum (KAl(SO4)2), 0.1% aluminum sulfate, and 1% silica fume.

[0336] Comparative Example 2

[0337] It is basically the same as Comparative Example 1, except that the microwave power is 1000W, and modified fluorogypsum D2 is obtained.

[0338] Comparative Example 3

[0339] It is basically the same as Comparative Example 1, except that the microwave frequency is 1000MHz, and modified fluorogypsum D3 is obtained.

[0340] Comparative Example 4 is basically the same as Comparative Example 1, except that the microwave frequency is 3500MHz, and modified fluorogypsum D4 is obtained.

[0341] Comparative Example 5

[0342] 1) The carbide slag, grinding aid and fluorogypsum raw material are ground by a segmented grinding mill. First, the material is coarsely ground in a ball mill for 10 minutes to obtain intermediate particles. Then, the intermediate particles are finely ground in a planetary grinding mill for 5 minutes to obtain the first intermediate (Dv90 particle size ≤ 20μm).

[0343] The grinding aid includes triethanolamine, polycarboxylate dispersant (sodium polyacrylate, Sigma 447013), and grinding media; the mass ratio of triethanolamine to polycarboxylate dispersant is 2:1; the molecular weight of polycarboxylate dispersant is 10000 g / mol; the grinding media are zirconia balls with a diameter of 3 mm and a grinding energy density of 5.5 ± 0.5 kW·h / t;

[0344] The mass content of carbide slag is 1% based on the mass of fluorogypsum raw material;

[0345] The grinding aid content is 0.05% based on the mass of the fluorogypsum raw material.

[0346] 2) Add an activator to the first intermediate, and then mix it in a high-efficiency mixer at 3000 rpm for 3 minutes to fully homogenize it. After mixing evenly, age it at 50°C for 2 hours to obtain modified fluorogypsum D5.

[0347] Of which, based on the mass of fluorogypsum raw material, the mass content of activator is 2.1%;

[0348] Based on the mass of the fluorogypsum raw material, the activator includes the following components in the following mass contents: 0.3% K2SO4, 0.2% Na2SiO3·9H2O, 0.5% calcined alum (KAl(SO4)2), 0.1% aluminum sulfate, and 1% silica fume.

[0349] Comparative Example 6

[0350] 1) The carbide slag, grinding aid and fluorogypsum raw material are ground by a segmented grinding mill. First, the material is coarsely ground in a ball mill for 10 minutes to obtain intermediate particles. Then, the intermediate particles are finely ground in a planetary grinding mill for 5 minutes to obtain the first intermediate (Dv90 particle size ≤ 20μm).

[0351] The grinding aid includes triethanolamine, polycarboxylate dispersant (sodium polyacrylate, Sigma 447013), and grinding media; the mass ratio of triethanolamine to polycarboxylate dispersant is 2:1; the molecular weight of polycarboxylate dispersant is 10000 g / mol; the grinding media are zirconia balls with a diameter of 3 mm and a grinding energy density of 5.5 ± 0.5 kW·h / t;

[0352] The mass content of carbide slag is 1% based on the mass of fluorogypsum raw material;

[0353] The grinding aid content is 0.05% based on the mass of the fluorogypsum raw material.

[0354] 2) The first intermediate was placed in a high-temperature calcining furnace and heated at 100°C for 20 minutes, then heated to 200°C and kept at that temperature for 0.5 hours to obtain the second intermediate.

[0355] 3) Add an activator to the second intermediate, and then mix it in a high-efficiency mixer at 3000 rpm for 3 minutes to fully homogenize it. After mixing evenly, age it at 50°C for 2 hours to obtain modified fluorogypsum D6.

[0356] Of which, based on the mass of fluorogypsum raw material, the mass content of activator is 2.1%;

[0357] Based on the mass of the fluorogypsum raw material, the activator includes the following components in the following mass contents: 0.3% K2SO4, 0.2% Na2SiO3·9H2O, 0.5% calcined alum (KAl(SO4)2), 0.1% aluminum sulfate, and 1% silica fume.

[0358] Comparative Example 7

[0359] The process is basically the same as in Example 10, except that fluorogypsum from Henan Zhengshun Fluorochemical Co., Ltd. was used, and the components with the mass content shown in Table 1 were used to prepare fire-retardant coating D7.

[0360] Test Example 1

[0361] The hydration rate and early 3-day compressive strength of the modified fluorogypsum in Examples 1-9 and Comparative Examples 1-6 were tested using the following methods, and the results are shown in Table 2.

[0362] 1) Test method for hydration rate of modified fluorogypsum:

[0363] S1. Weigh a certain mass of modified fluorogypsum sample, add a quantitative amount of distilled water according to the standard water-gypsum ratio, and stir evenly in a stirrer to make a clean slurry;

[0364] S2. Quickly pour the neat pulp into the test mold and place it in a curing environment with a temperature of 20±2℃ and a relative humidity of ≥90% for curing;

[0365] S3. When the samples are cured to the specified age, they are taken out and crushed. The hydration is terminated with anhydrous ethanol. After vacuum drying, the contents of unhydrated anhydrous calcium sulfate and the hydration product calcium sulfate dihydrate in the samples are determined by differential scanning calorimetry (DSC) or thermogravimetric analysis (TG).

[0366] S4. Based on the change in phase content before and after hydration, calculate the hydration conversion ratio of anhydrous calcium sulfate per unit time, which is the hydration rate of modified fluorogypsum.

[0367] 2) Test method for early compressive strength at 3 days

[0368] The test method is based on the national standard GB / T 17669.3-1999.

[0369] 3) Calcium fluoride content in modified fluorogypsum

[0370] Weigh a certain mass of modified fluorogypsum as a sample, and refer to GB / T 5195.1-2017 for specific test methods.

[0371] Table 2

[0372]

[0373] As shown in Table 2, compared with the modified fluorogypsum provided in the comparative example, the hydration rate and early compressive strength at 3 days of the modified fluorogypsum provided in the present invention are significantly better than those of the comparative example, and the calcium fluoride content in the modified fluorogypsum provided in the present invention is greater than that of the comparative example.

[0374] Test Example 2

[0375] The physical and chemical properties, such as the bonding strength, of the modified fluorogypsum-based fire-retardant coatings for steel structures in Examples 10-12 and the fire-retardant coating in Comparative Example 7 were tested according to GB 14907-2018. The initial drying crack resistance was tested according to GB / T 9779-2015. The results are shown in Table 3.

[0376] Table 3

[0377]

[0378] As shown in Table 3, compared with the fire-retardant coating provided in the comparative example, the modified fluorogypsum-based steel structure fire-retardant coating of the embodiment has significantly better drying time, bonding strength, compressive strength, dry density, heat insulation efficiency, water resistance, and resistance to thermal cycling than the comparative example. Moreover, the modified fluorogypsum-based steel structure fire-retardant coating of the embodiment has no cracks on the surface of the fire-resistant coating during the initial curing stage.

[0379] In summary, the modified fluorogypsum preparation method provided by this invention, through the neutralization reaction of carbide slag and fluorogypsum raw materials and the segmented heating process using microwave heating, not only removes acidic impurities from the fluorogypsum raw materials, but also converts the free fluorine in the fluorogypsum, which is harmful to humans and the environment, into high-purity calcium fluoride. The high-temperature chemical stability of calcium fluoride improves the high-temperature resistance limit of the coating; it also significantly enhances the hydration activity of fluorogypsum, solving the problem of low early strength and subsequent strength reduction of traditional fluorogypsum-based materials; furthermore, the modified fluorogypsum-based fireproof coating for steel structures provided by this invention has both fireproof and crack-resistant functions, and significantly improves the bonding strength and other properties of the modified fluorogypsum-based fireproof coating for steel structures.

[0380] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing modified fluorogypsum, characterized in that, Includes the following steps: 1) The calcium carbide slag and fluorogypsum raw materials are mixed once to obtain the first intermediate; 2) The first intermediate is subjected to microwave heating treatment, the microwave heating treatment process includes a first heating treatment and a second heating treatment to obtain a second intermediate; 3) The second intermediate and the activator are mixed twice to obtain the modified fluorogypsum; The microwave power of the microwave heating treatment is 300W~500W, and the microwave frequency is 2450MHz~2500MHz. The activator includes at least two of sulfates, silicates, and water-soluble aluminum salts.

2. The preparation method according to claim 1, characterized in that, The temperature of the first heating treatment is 100℃~120℃, and the time is 20min~30min; And / or, the temperature of the secondary heating treatment is 200℃~300℃, and the time is 30min~60min.

3. The preparation method according to claim 1, characterized in that, The primary mixing process also includes a grinding process using a grinding aid; And / or, the secondary mixing process includes a stirring process; And / or, the secondary mixing process may be followed by an aging process.

4. The preparation method according to claim 3, characterized in that, The grinding aid has a mass content of 0.05% to 0.15% based on the mass of the fluorogypsum raw material. And / or, the stirring speed is 1000 rpm to 3000 rpm, and the stirring time is 3 min to 5 min; And / or, the aging treatment time is 2h~3h, and the aging treatment temperature is 40℃~50℃.

5. The preparation method according to claim 1, characterized in that, The mass content of the carbide slag is 1% to 5% based on the mass of the fluorogypsum raw material. And / or, based on the mass of the fluorogypsum raw material, the activator has a mass content of 0.5% to 6.8%.

6. The preparation method according to any one of claims 1-5, characterized in that, The activator also includes mineral synergists; And / or, based on the mass of the fluorogypsum raw material, the sulfate content is 0.3% to 1.0% by mass; And / or, based on the mass of the fluorogypsum raw material, the silicate content is 0.2% to 0.8% by mass; And / or, based on the mass of the fluorogypsum raw material, the mass content of the water-soluble aluminum salt is 0.1% to 2.0%; And / or, based on the mass of the fluorogypsum raw material, the mass content of the mineral synergist is 1% to 3%.

7. A modified fluorogypsum, characterized in that, The modified fluorogypsum was obtained using the preparation method of the modified fluorogypsum as described in any one of claims 1-6.

8. A modified fluorogypsum-based fire-retardant coating for steel structures, characterized in that, The modified fluorogypsum-based fireproof coating for steel structures includes the modified fluorogypsum as described in claim 7.

9. The modified fluorogypsum-based fireproof coating for steel structures according to claim 8, characterized in that, Based on the mass of the modified fluorogypsum-based fire-retardant coating for steel structures, the modified fluorogypsum-based fire-retardant coating for steel structures comprises the following components in mass content: The modified fluorogypsum is 35%~45%. fly ash 30%~35%, Calcium carbonate 5%~10%, Refractory aggregate 10%~16%, Flame retardant 1%~2%, Latex powder 2%~5%, Fiber material 0.1%~0.3%, Cellulose ethers 0.1%~0.2%, Phase change capsules: 1%~2%.

10. The modified fluorogypsum-based fireproof coating for steel structures according to claim 9, characterized in that, The refractory aggregate includes at least one of perlite, vermiculite, and ceramsite; And / or, the flame retardant includes magnesium hydroxide and / or aluminum hydroxide; And / or, the fiber material includes a first fiber and / or a second fiber; And / or, the phase change capsule includes a capsule wall and a capsule core; the capsule wall includes at least one of silicon dioxide, titanium dioxide, zirconium dioxide, polystyrene, polymethyl methacrylate, melamine resin, melamine resin, and urea-formaldehyde resin; the capsule core includes at least one of inorganic crystalline hydrated salt, paraffin wax, sugar alcohol, neopentyl glycol, and trimethylolpropane.

11. The modified fluorogypsum-based fireproof coating for steel structures according to claim 10, characterized in that, The refractory aggregate includes a porous structure, and the average pore size of the refractory aggregate is 550μm~830μm; And / or, the mass ratio of the first fiber to the second fiber is 1:(1~2); And / or, the length of the first fiber is 1mm to 3mm and the diameter is 20μm to 30μm; And / or, the second fiber has a length of 6mm to 9mm and a diameter of 20μm to 30μm; And / or, the mass ratio of the capsule wall to the capsule core is 1:1.2 to 1:1.5; And / or, the average particle size of the phase change capsule is 10 μm to 30 μm.

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