A manufacturing process of a fireproof door core plate made of desulfurized gypsum

Abstract

The application discloses a kind of manufacturing processes of fireproof door core plate of desulfurization gypsum in the field of building materials, by calcining activation to desulfurization phosphorus gypsum and mixed with desulfurization building gypsum, add the base material formed by the modified composite material prepared in advance, while screening cement to remove agglomeration and coating release agent on the inner wall of mold and preheating;Gypsum blowing agent is dissolved with water, and after defoaming, it is added into the stirrer by metering pump, while cement, base material and other raw materials are put in, and the slurry is formed by using planetary stirrer at low speed first and then at high speed;After the slurry is injected into the mold, it is placed after initial setting, and the mold is removed;The interface bonding is optimized by modified composite material, the fireproof performance, mechanical strength and dimensional stability are improved, the production cost is reduced, the industrial byproduct gypsum resources are efficiently utilized, the environmental pollution is reduced, and the building fire safety requirements are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, and particularly relates to a manufacturing process of a desulfurization gypsum fireproof door core plate. BACKGROUND

[0002] As a key component of building fire protection system, the fireproof performance, mechanical strength and environmental friendliness of the core plate of the fireproof door directly affect the overall fireproof efficiency and service life. The traditional fireproof door core plate is mostly dependent on wood, plastic or inorganic cementitious materials. The wooden core plate is flammable and consumes a lot of resources, the plastic-based core plate has the risk of releasing toxic gases at high temperature, and the ordinary inorganic gypsum-based core plate has certain fireproof performance, but it is difficult to meet the stringent requirements of modern buildings for high-performance fireproof doors due to problems such as insufficient strength, easy cracking or excessive hygroscopicity. With the promotion of comprehensive utilization policy of industrial solid waste, desulfurization gypsum, as a byproduct of flue gas desulfurization in coal-fired power plants, has a huge annual output and potential cementitious activity, and gradually becomes a research hotspot for replacing natural gypsum to prepare environment-friendly building materials. However, the desulfurization gypsum itself has defects such as loose crystal structure, high water demand, high porosity of hardened body and limited fireproof performance, which leads to unstable product strength, insufficient fire resistance limit or dimensional deformation when directly used for door core plate preparation, limiting its application in the field of high-end fireproof doors.

[0003] Although the improvement research on desulfurization gypsum-based door core plate has been carried out, it still faces multiple technical challenges. On the one hand, if the activation treatment process (such as calcination and grinding) of desulfurization gypsum is not properly controlled, it is difficult to effectively stimulate its cementitious activity, resulting in weak bonding force between the matrix and the reinforcing material, and the product is prone to delamination or cracking; on the other hand, the lightweight demand of the door core plate is usually realized by relying on foaming process, but the compatibility of traditional foaming agent and gypsum system is poor, and the foaming process easily introduces large bubbles or uneven bubble distribution, which not only reduces the strength of the material, but also may cause the fireproof performance to decrease due to the rupture of the bubbles. In addition, in order to improve the comprehensive performance, the existing technology often tries to add modified materials such as fibers, polymers or inorganic fillers, but the compounding method of these materials is mostly simple blending, which is difficult to form an interface synergistic effect, resulting in limited modification effect, and the introduction of some modifiers (such as chemical synthetic products) may increase the environmental burden, which is not in line with the development trend of green building materials.

[0004] Under this background, it is urgent to develop a desulfurization gypsum fireproof door core plate manufacturing process with high fireproof performance, good mechanical strength and environmental friendliness. The present application optimizes the activation and compounding process of desulfurization gypsum, combines the directional design of modified composite materials and precise foaming technology, effectively solves the problems of insufficient strength, weak fireproof performance and poor process adaptability of the existing desulfurization gypsum-based door core plate, and provides a new technical path for the high-value utilization of industrial solid waste and the research and development of high-performance fireproof building materials. SUMMARY

[0005] The application aims to provide a desulfurization gypsum fireproof door core plate manufacturing process, which solves the problems of low strength, insufficient fire resistance, poor water resistance of traditional desulfurization gypsum fireproof door core plate and inefficient utilization of industrial solid waste.

[0006] The application achieves the above-mentioned purpose through the following technical solutions:

[0007] A desulfurization gypsum fireproof door core plate manufacturing process comprises the following steps:

[0008] S1, desulfurization phosphogypsum is calcined and activated at 150-200 DEG C, and after cooling to 20-25 DEG C, it is mixed with desulfurization building gypsum to form a base material by adding a modified composite material; cement is sieved to remove lumps; a release agent is coated on the inner wall of the mold, and the mold is preheated to 40-45 DEG C;

[0009] S2, the gypsum foaming agent is first pre-dissolved with water, and after standing and defoaming, it is added to the stirrer through a metering pump, while cement, base material, water reducing agent, retarder and cellulose are added to the stirrer, and stirring is started;

[0010] S3, a planetary stirrer is used to stir the dry materials at low speed first, and then at high speed to obtain a slurry;

[0011] S4, the slurry is injected into the mold and allowed to stand for initial setting, and after initial setting, the mold is removed.

[0012] According to the preferred embodiment of the application, the desulfurization phosphogypsum is purchased from KM-I type phosphogypsum of Guizhou Kai phosphorus group Co., Ltd.

[0013] According to the preferred embodiment of the application, the desulfurization building gypsum is purchased from BN-II type building gypsum of Beixin group building materials Co., Ltd.

[0014] According to the preferred embodiment of the application, the cement is purchased from CA-50 (calcium aluminate content > 50%, suitable for early strength and high temperature resistant scene) of Zhengzhou aluminum city special cement Co., Ltd.

[0015] According to the preferred embodiment of the application, the mold is purchased from DG-2024-FJ type fireproof door core plate special steel mold of Qingdao Degute energy saving equipment Co., Ltd.

[0016] According to the preferred embodiment of the application, the release agent is purchased from SR-2024 type silicone oil based release agent of Jiangsu Risheng Chemical Co., Ltd.

[0017] According to the preferred embodiment of the application, the gypsum foaming agent is purchased from SDS-I type octadecyl sodium sulfate of Shanghai Aladdin Biochemical Technology Co., Ltd.

[0018] According to the preferred embodiment of the present application, the stirrer is LT-800 planetary stirrer purchased from Shandong Longteng Machinery Manufacturing Co., Ltd.

[0019] According to the preferred embodiment of the present application, the water reducing agent is KZJ-PCA-II polycarboxylic high performance water reducing agent purchased from Kezhijie New Material Group Co., Ltd.

[0020] According to the preferred embodiment of the present application, the retarder is F-I sodium gluconate purchased from Chengdu Chemical Co., Ltd.

[0021] According to the preferred embodiment of the present application, the cellulose is HEDA HPMC-400 hydroxypropyl methyl cellulose purchased from Shandong Heda Group Co., Ltd.

[0022] According to the preferred embodiment of the present application, in step S1, the premixing time is 10-15 min; and the cement is passed through 80-85 mesh sieve.

[0023] In step S1 of the present application, the desulfurization phosphogypsum is calcined and activated at 150-200℃, the high temperature promotes the conversion of the dihydrate gypsum in the desulfurization phosphogypsum into hemihydrate gypsum by removing part of the crystal water, destroys the original crystal structure, increases the specific surface area and active points, and improves the reaction activity with the desulfurization building gypsum. After cooling to 20-25℃, the desulfurization building gypsum is mixed, the two interact with each other through ion exchange, lattice reconstruction and other ways at the micro level, and the microstructure of the door core plate is optimized.

[0024] According to the preferred embodiment of the present application, in step S2, the mass ratio of the gypsum foaming agent to water is 1:(5-6), the pre-dissolution temperature is 30-35℃; the standing time is 5-10 min, the gypsum foaming agent is added into the stirrer by the metering pump for 3-4 times, and the interval time is 2-3 min each time; and the stirring speed is 30-40 r / min.

[0025] In step S2 of the present application, the gypsum foaming agent and water are pre-dissolved at a mass ratio of 1:5-6 at 30-35 DEG C, which is close to the optimal dissolution temperature of the foaming agent, so that the foaming agent molecules are fully dispersed in water to form a uniform solution. Standing for 5-10 min to remove the unstable bubbles in the solution can reduce the influence of the bubbles on the performance of the door core board. The foaming agent solution is added into the stirrer through a metering pump, while the cement, base material, water reducing agent, retarder and cellulose are added, and the stirring speed is 30-40 r / min. The gypsum foaming agent forms tiny bubbles in the solution, which reduces the density of the slurry and forms a uniform pore structure. The water reducing agent molecules are adsorbed on the surface of the cement particles, which increases the surface charge density of the particles, generates electrostatic repulsion, promotes the dispersion of the cement particles, releases the wrapped water, and improves the fluidity and strength of the slurry. The retarder is adsorbed on the surface of the cement hydration product, which prevents the contact between the cement particles, delays the speed of the cement hydration reaction, and prolongs the setting time of the slurry. The hydroxyl groups on the cellulose molecular chain form hydrogen bonds with water molecules to form a spatial network structure in the slurry, which increases the viscosity of the slurry and improves its water retention and stability.

[0026] According to the preferred embodiment of the present application, in step S3, the low-speed stirring speed is 30-40 r / min, and the low-speed stirring time is 3-4 min. The high-speed stirring speed is 60-80 r / min, and the high-speed stirring time is 5-6 min.

[0027] In step S3 of the present application, the planetary stirrer is first stirred at a low speed of 30-40 r / min for 3-4 min to fully mix the dry materials at a low speed, so as to avoid excessive heat generated by high-speed stirring, which can cause local overheating of the slurry and deterioration of the material performance. At the same time, it prevents the agglomeration of dry materials and ensures the uniform distribution of each component. Then, the planetary stirrer is stirred at a high speed of 60-80 r / min for 5-6 min. High-speed stirring can further disperse and refine each component in the slurry, so that the bubbles are uniformly distributed in the slurry, and a uniform slurry is obtained, which provides a good forming basis for the door core board.

[0028] According to the preferred embodiment of the present application, in step S4, the temperature of the slurry is 25-30 DEG C, and the standing time is 15-20 min.

[0029] In step S4 of the present application, the slurry is injected into the mold and then left to stand for 15-20 min at a temperature of 25-30 DEG C for initial setting. This temperature range matches the temperature of the slurry, so that the slurry can slowly undergo hydration reaction under suitable temperature conditions, gradually form initial strength, and facilitate the subsequent removal of the mold. After initial setting, the mold is removed, and the door core board enters the subsequent curing stage.

[0030] According to the preferred embodiment of the present application, the desulfurized gypsum fireproof door core board manufacturing process further comprises: placing the door core board prepared in step S4 at a temperature of 20-30 DEG C for 72-144 h.

[0031] The application further provides a desulfurized gypsum fireproof door core plate prepared by the manufacturing process of the desulfurized gypsum fireproof door core plate, and raw materials of the desulfurized gypsum fireproof door core plate comprise, in percentage by mass, desulfurized phosphogypsum: 70-75%; cement: 3-5%; desulfurized building gypsum: 12-15%; modified composite material: 15-16%; gypsum foaming agent: 0.3-0.5%; water reducing agent: 0.2-0.5%; retarder: 0.3-0.5%; cellulose: 0.2-0.4%.

[0032] According to the preferred embodiment of the application, the preparation step of the modified composite material comprises:

[0033] A1, mixing the waste oyster shell powder with a chitosan solution, adding calcium acetate after ultrasonic dispersion, and reacting at 45-50 DEG C to form a biomimetic template solution; taking the vitrified microbeads and immersing them in an acrylate monomer containing a photoinitiator TPO, and irradiating under a UV lamp to form a pre-polymer bonding layer;

[0034] A2, transferring into a fluidized bed, spraying the template solution prepared in step A1, and synchronously starting the near-infrared laser scanning surface to trigger the local mineralization reaction; mixing the modified fly ash activated by plasma with zinc borate@ZIF-8 core-shell flame retardant, and depositing the same to the mineralization layer through an electrostatic adsorption device.

[0035] According to the preferred embodiment of the application, the waste oyster shell powder is purchased from Shandong Qingdao Blue Sea Shell Resource Comprehensive Utilization Co., Ltd.

[0036] According to the preferred embodiment of the application, the chitosan solution is a food-grade chitosan solution (model number: JKB-200, deacetylation degree ≥ 90%) produced by Zhejiang Jinshell Biological Technology Co., Ltd.

[0037] According to the preferred embodiment of the application, the calcium acetate is an industrial-grade calcium acetate (model number: CH-01, purity ≥ 99%) produced by Hebei Kelong Fine Chemical Co., Ltd.

[0038] According to the preferred embodiment of the application, the vitrified microbeads are closed-pore vitrified microbeads (model number: HW-GM-1.0, particle size 1-1.5 mm, bulk density 80-100 kg / m 3 ) produced by Hebei Huamei Energy-saving Technology Group Co., Ltd.

[0039] According to the preferred embodiment of the application, the photoinitiator TPO is a photoinitiator TPO (model number: TPO-99, purity ≥ 99%) produced by Beijing Yingli Science and Technology Development Co., Ltd.

[0040] According to the preferred embodiment of the present application, the fluidized bed is purchased from Changzhou One Step Drying Equipment Co., Ltd. (Model: FG-500, processing capacity: 50-200 kg / h).

[0041] According to the preferred embodiment of the present application, the acrylate monomer is purchased from Shanghai Aladdin Biochem Technology Co., Ltd. (Model: A102501, purity: ≥99.5%).

[0042] According to the preferred embodiment of the present application, the ultraviolet lamp is purchased from Shanghai Ke Heng Industry Development Co., Ltd. (Model: ZXW-365, wavelength: 365-370 nm, power: 100 W).

[0043] According to the preferred embodiment of the present application, the fly ash is purchased from Anhui Huainan Pingwei Power Generation Co., Ltd. (Model: F Class II, 45 μm sieve residue: ≤25%).

[0044] According to the preferred embodiment of the present application, the zinc borate@ZIF-8 core-shell flame retardant is purchased from the functional flame retardant (Model: ZB-ZIF-8-01, zinc borate content: 30-35%, ZIF-8 shell thickness: 50-80 nm) synthesized by the laboratory of Beijing University of Chemical Technology.

[0045] According to the preferred embodiment of the present application, the electrostatic adsorption device is purchased from Jiangsu Boluosi Mechanical Manufacturing Co., Ltd. (Model: BR-ESD-10, voltage range: 0-30 kV, processing air volume: 500-1500 m 3 / h).

[0046] According to the preferred embodiment of the present application, in step A1, the particle size of the waste oyster shell powder is 200-250 mesh; the mass ratio of the waste oyster shell powder to the chitosan solution is 1:(3-4); the reaction time is 30-40 min; the particle size of the vitrified microsphere is 1-1.5 mm; the wavelength of the ultraviolet lamp is 365-370 nm; and the irradiation time is 5-8 s.

[0047] In step A1 of the present application, the waste oyster shell powder (mainly composed of CaCO3 and containing a small amount of organic matter) is sieved through a 200-250 mesh sieve, mixed with a chitosan solution (containing a large amount of amino groups (-NH2) in the chitosan molecular chain, which needs to be acidified and dissolved in advance to form positively charged -NH3 + ) in a mass ratio of 1:(3-4), ultrasonically dispersed (20-40 kHz, power: 200-300 W) to uniformly disperse the oyster shell powder in the chitosan solution, and reduce particle agglomeration. Then, calcium acetate is added and reacted at 45-50°C: the -NH3 + of the chitosan reacts with Ca2+ Through electrostatic coordination, while free CO3 2- (weakly dissolved from oyster shell powder or dissociation equilibrium of calcium acetate) in the solution) and Ca 2+ are combined, the CaCO3 crystal nucleus growth is guided by the chitosan molecular chain as a template to form a “chitosan-carbonate” biomimetic mineralization composite structure (the CaCO3 loading in the template solution is 15-20% of the mass of chitosan). In this process, the ultrasonic dispersion promotes the Ca 2+ is in full contact with chitosan, and the temperature of 45-50℃ accelerates the diffusion and crystallization kinetics of Ca 2+ The simultaneously performed pre-treatment of the vitrified microbeads (particle size 1-1.5mm, surface inertness): the vitrified microbeads are immersed in an acrylate monomer (such as methyl methacrylate, MMA) containing a photoinitiator TPO (2,4,6-trimethylbenzoyl-diphenyl phosphine oxide), and are irradiated by a UV lamp (wavelength 365-370nm, power 80-100W) for 5-8s: TPO absorbs ultraviolet light to generate free radicals (such as tert-butoxy free radicals), which initiate the radical polymerization reaction of the acrylate monomer on the surface of the vitrified microbeads to form a pre-polymer bonding layer (acrylate polymer) with a thickness of 10-20μm, which enhances the interfacial bonding force between the subsequent mineralization layer and the vitrified microbeads.

[0048] According to the preferred embodiment of the present application, in step A2, the atomization pressure of the template solution prepared in step A1 is 0.15-0.2MPa; the wavelength of the near-infrared laser is 1064-1070nm, and the power is 50-55W; the mass ratio of the modified fly ash to the zinc borate@ZIF-8 core is (4-5):1; and the voltage of the electrostatic adsorption device is 15-16kV.

[0049] In step A2 of the present application, the template solution (containing chitosan-carbonate composite) prepared in step A1 is sprayed through an atomizing nozzle (pressure 0.15-0.2MPa) to the surface of the vitrified microbeads in the fluidized bed, and a near-infrared laser (wavelength 1064-1070nm, power 50-55W) is turned on at the same time: the near-infrared laser penetrates the template solution layer, is absorbed by the water molecules (or residual acetate) in the template solution and is converted into heat energy, locally heating to 50-60℃, triggering the remaining Ca 2+ in the template solution to react with CO3 -or additional carbonate (such as sodium carbonate to adjust pH) reaction, generate nanoscale calcite crystals (CaCO3), fill the pores of the chitosan template, form a "calcite crystal-chitosan" mineralization layer (thickness 5-15 μm), enhance the surface density of the material. At the same time, the modified fly ash (surface treated with silane coupling agent, containing epoxy groups on the surface) and zinc borate @ ZIF-8 core-shell flame retardant (ZIF-8 shell thickness 20-30 nm, loading rate 30-40%) are mixed in a mass ratio of (4-5):1, and the particles are negatively charged (modified fly ash) and positively charged (mineralization layer surface Ca 2+ Residual) are attracted to each other and directionally deposited on the surface of the mineralization layer. Zinc borate (ZnB2O4) is decomposed by heat to generate H3BO3 and ZnO, and ZIF-8 is converted to ZnO and releases N2 / CO2 at high temperature, which synergistically inhibits combustion; modified fly ash fills the gaps between the flame retardant, improving the interfacial bonding strength between the flame retardant layer and the substrate. Finally, through the synergistic effect of biomineralization template guidance, photo-induced polymerization adhesion, near-infrared laser-assisted mineralization, and electrostatic adsorption deposition, a multi-layer composite structure of "vitrified microsphere-prepolymer adhesion layer-mineralization layer-flame retardant deposition layer" is formed, realizing the improvement of the temperature resistance, reinforcement and flame retardance of the modified composite material.

[0050] The beneficial effects of the present application are:

[0051] The present application significantly improves the comprehensive performance of the fireproof door core board through the synergistic effect of the optimized composite process of desulfurized gypsum base material and the modified material. The calcination and activation of desulfurized phosphogypsum and building gypsum and the complex system effectively improve the problems of insufficient strength and poor water resistance of traditional gypsum products. The porous structure and inorganic flame-retardant components in the modified composite material form a three-dimensional network skeleton, which can effectively block heat transfer and inhibit smoke generation in high temperature environment. At the same time, the precise introduction of the gypsum foaming agent forms a uniform closed cell structure inside the material, which not only reduces the overall density but also enhances the compressive strength. This lightweight and high-strength characteristic not only meets the fireproof requirements but also reduces the load of the door body. In the process, the stirring rate, curing temperature and time parameters are accurately controlled to ensure that each component reacts fully and forms a stable phase structure, finally obtaining a new fireproof door core material with excellent fire resistance limit, dimensional stability and environmental adaptability.

[0052] The innovative preparation technology of modified composites realizes the high-value utilization of industrial solid waste and the precise regulation of functional components. The biomineralized layer formed by chitosan induction of waste oyster shell powder is bonded to the pre-polymer adhesive layer on the surface of vitrified microbeads through near-infrared laser triggered in-situ mineralization reaction, forming a high-strength interfacial bonding network, which effectively solves the performance degradation problem caused by uneven dispersion of fillers in traditional composites. Plasma-modified fly ash particles and zinc borate@ZIF-8 core-shell flame retardant are deposited by electrostatic adsorption, building a distributed flame retardant system in the material. The nanoscale flame retardant particles can release crystallization water and form a heat-insulating carbon layer at the initial stage of the flame, while the ZIF-8 structure decomposes to produce inert gas to dilute the oxygen concentration. This multi-mechanism synergy enables the material to maintain a low thermal conductivity while significantly extending the fire resistance time and suppressing the release of harmful gases during the combustion process.

[0053] This process realizes the high integration of green manufacturing and efficient production through equipment improvement and process innovation. Pre-heating of the mold and optimization of the release agent significantly improve the release efficiency and reduce surface defects. The dual-speed design of the planetary stirring system ensures uniform dispersion of raw materials while avoiding excessive shear-induced bubble rupture. The precise matching of the desulfurized gypsum calcination waste heat recovery system and process parameters reduces the production energy consumption by more than 30% compared to traditional processes. The near-infrared laser and plasma combined activation technology used in the preparation of modified composites enables the controlled deposition of nanoscale functional components, significantly improving the isotropic degree of the material. Intelligent regulation of the curing conditions ensures that the hydration reaction proceeds fully, resulting in a final product with stable physical properties and durability. This whole-process process optimization not only improves production efficiency but also promotes the large-scale application of industrial solid waste in green building materials. DETAILED DESCRIPTION

[0054] The following detailed description is only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0055] I. Main raw materials and equipment:

[0056] Desulfurized phosphogypsum: KM-I type phosphogypsum purchased from Guizhou Kaihua Group Co., Ltd.

[0057] Desulfurized building gypsum: BN-II type building gypsum purchased from Beixin Group Building Materials Co., Ltd.

[0058] Cement: CA-50 (calcium aluminate content ≥ 50%, suitable for early strength and high temperature resistance scenarios) purchased from Zhengzhou Aluminum City Special Cement Co., Ltd.

[0059] Mold: DG-2024-FJ type fireproof door core plate special steel mold purchased from Qingdao Deguo Special Energy Saving Equipment Co., Ltd.

[0060] Release agent: SR-2024 type silicone oil based release agent purchased from Jiangsu Risheng Chemical Co., Ltd.

[0061] Gypsum foaming agent: SDS-I type sodium octadecyl sulfate purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0062] Stirrer: LT-800 type planetary stirrer purchased from Shandong Longteng Machinery Manufacturing Co., Ltd.

[0063] Water reducing agent: KZJ-PCA-II type polycarboxylic acid high performance water reducing agent purchased from Kezhijie New Material Group Co., Ltd.

[0064] Retarder: F-I type sodium gluconate purchased from Chengdu Chemical Co., Ltd.

[0065] Cellulose: HEDA brand HPMC-400 type hydroxypropyl methyl cellulose purchased from Shandong Heda Group Co., Ltd.

[0066] Waste oyster shell powder: purchased from Shandong Qingdao Blue Sea Shell Resource Comprehensive Utilization Co., Ltd.

[0067] Chitosan solution: food grade chitosan solution (model: JKB-200, degree of deacetylation ≥90%) produced by Zhejiang Jinshell Biological Technology Co., Ltd.

[0068] Calcium acetate: industrial grade calcium acetate (model: CH-01, purity ≥99%) produced by Hebei Kelong Fine Chemical Co., Ltd.

[0069] Vitrified microbeads: closed pore vitrified microbeads (model: HW-GM-1.0, particle size 1-1.5mm, bulk density 80-100kg / m 3 ) produced by Hebei Huamei Energy Saving Technology Group Co., Ltd.

[0070] Photoinitiator TPO: photoinitiator TPO (model: TPO-99, purity ≥99%) produced by Beijing Yingli Science and Technology Development Co., Ltd.

[0071] Fluidized bed: fluidized bed (model: FG-500, processing capacity 50-200kg / h) produced by Changzhou One Step Drying Equipment Co., Ltd.

[0072] Acrylate monomer: methyl methacrylate (model: A102501, purity ≥99.5%) produced by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0073] UV lamp: mercury amalgam UV lamp (model: ZWX-365, wavelength 365-370 nm, power 100 W) purchased from Shanghai KeHeng Industry Development Co., Ltd.

[0074] Fly ash: Grade II low calcium fly ash (model: F class II, 45 μm residue ≤ 25%) purchased from Anhui Huainan Pingwei Power Generation Co., Ltd.

[0075] Zinc borate@ZIF-8 core-shell flame retardant: functional flame retardant (model: ZB-ZIF-8-01, zinc borate content 30-35%, ZIF-8 shell thickness 50-80 nm) synthesized and customized from the laboratory of School of Materials Science and Engineering, Beijing University of Chemical Technology.

[0076] Electrostatic adsorption device: plate-type electrostatic adsorption machine (model: BR-ESD-10, voltage range 0-30 kV, processing air volume 500-1500 m 3 / h) produced by Jiangsu Bolisi Mechanical Manufacturing Co., Ltd.

[0077] II. Examples

[0078] Example 1

[0079] A preparation process of a fireproof door core plate of desulfurized gypsum is as follows: 720g of desulfurized gypsum is placed in a calcining furnace and calcined and activated at 180℃ for 2h, and after natural cooling to 22℃, it is poured into a planetary mixer together with 130g of desulfurized building gypsum, 155g of modified composite material is added to the mixer, and pre-mixed at a speed of 12r / min for 12min to form a uniform base; a mold with a size of 500mm*300mm*50mm is taken synchronously, the inner wall is uniformly coated with liquid paraffin release agent (the coating thickness is accurate to cover the inner wall and not to drip), the mold is placed in a 42℃ oven for preheating for 30min to ensure uniform mold temperature; then 4g of gypsum foaming agent and 22g of water are added to a beaker, pre-dissolved in a 32℃ water bath for 10min, and after standing for 7min to defoam, they are added to a planetary mixer (the mixer and the base mixer are the same equipment) through a metering pump at a frequency of "3 times / 2.5min" (i.e. 1 time every 2.5min, a total of 3 times); at the same time, 40g of cement removed from agglomerates through an 80-mesh sieve, the above-prepared base, 3g of polycarboxylic acid water reducing agent (water reducing rate ≥ 25%), 4g of citric acid retarder (purity ≥ 99%), and 3g of hydroxypropyl methyl cellulose (viscosity ≥ 100000 mPa·s) are added to the mixer, and first stirred at a low speed of 35r / min for 3.5min to preliminarily mix the dry materials uniformly, and then stirred at a high speed of 70r / min for 5.5min, finally obtaining a slurry with a temperature of 28℃; then the slurry is poured into the preheated mold, and after standing for 18min for initial setting, the mold is removed after the slurry is preliminarily hardened; the door core plate after demolding is placed in a curing room at 25℃ for standing and curing for 72h to ensure that the hydration reaction is fully carried out;

[0080] wherein the preparation of the modified composite material is completed synchronously, specifically: 200g of discarded oyster shell powder with a particle size of 200 mesh is mixed with 1000mL of chitosan solution, ultrasonic dispersion is performed for 10min, then 50g of calcium acetate is added, the temperature is raised to 48℃ and reacted for 35min to form a biomimetic mineralization template solution; 100g of vitrified microbeads with a particle size of 1-1.5mm are immersed in an acrylic ester monomer containing a photoinitiator, and a wavelength of 368nm and a power of 100W are used to irradiate the surface of the vitrified microbeads with a UV lamp for 6s to form a pre-polymerization bonding layer; the above-prepared vitrified microbeads are transferred to a fluidized bed, the biomimetic mineralization template solution is sprayed through a nozzle with an atomizing pressure of 0.18MPa, and a wavelength of 1067nm and a power of 52W are used to scan the surface of the fluidized bed to trigger a local mineralization reaction to form a mineralization layer; 400g of plasma-activated modified fly ash is mixed with 80g of zinc borate@ZIF-8 core-shell flame retardant (zinc borate content 32%, ZIF-8 shell thickness 65nm) uniformly, and then deposited on the surface of the mineralization layer through an electrostatic adsorption device with a voltage of 15kV to make the flame retardant (zinc borate@ZIF-8) stably adhere, thereby obtaining the modified composite material.

[0081] Example 2

[0082] The specific implementation is the same as that of Example 1, except that 740 g of desulfurized phosphogypsum is calcined and activated at 160°C for 1.5 h, mixed with 125 g of desulfurized building gypsum after cooling to 24°C, and 158 g of modified composite is added and premixed for 11 min; the cement is sieved through a 82 mesh sieve, and 35 g is reserved; the mold is preheated to 43°C and coated with silicone release agent. The gypsum foaming agent (3.8 g) is pre-dissolved with 21 g of water (mass ratio 1:5.5) at 33°C for 8 min, and left to stand for 6 min. It is added to the mixer by a metering pump 3 times / 2.5 min; at the same time, 35 g of cement, the above prepared base, 2.8 g of water reducing agent, 3.8 g of retarder, and 2.8 g of cellulose are added, and stirred at low speed 32 r / min for 3 min and at high speed 65 r / min for 5 min (slurry temperature 26°C). After initial setting, the mold is removed and cured at 28°C for 96 h. In the preparation of the modified composite, the waste oyster shell powder is 250 mesh, the chitosan solution is 1200 mL, the calcium acetate is 60 g, the reaction time is 38 min; the vitrified microsphere is 120 g, the ultraviolet lamp irradiation time is 7 s; the fluidized bed spraying template liquid atomization pressure is 0.16 MPa, the near-infrared laser power is 53 W, the modified fly ash is 420 g, the zinc borate@ZIF-8 core-shell flame retardant is 90 g, and the electrostatic adsorption voltage is 15.5 kV.

[0083] Example 3

[0084] The specific implementation is the same as that of Example 1, except that 750 g of desulfurized phosphogypsum is calcined and activated at 200°C for 2 h, mixed with 150 g of desulfurized building gypsum after cooling to 20°C, and 160 g of modified composite is added and premixed for 15 min; the cement is sieved through a 85 mesh sieve, and 45 g is reserved; the mold is preheated to 44°C and coated with vaseline release agent. The gypsum foaming agent (4.5 g) is pre-dissolved with 27 g of water (mass ratio 1:6) at 34°C for 9 min, and left to stand for 9 min. It is added to the mixer by a metering pump 3 times / 3 min; at the same time, 45 g of cement, the above prepared base, 4.5 g of water reducing agent, 4.5 g of retarder, and 4 g of cellulose are added, and stirred at low speed 38 r / min for 4 min and at high speed 78 r / min for 6 min (slurry temperature 30°C). After initial setting, the mold is removed and cured at 30°C for 144 h. In the preparation of the modified composite, the waste oyster shell powder is 220 mesh, the chitosan solution is 1100 mL, the calcium acetate is 55 g, the reaction time is 32 min; the vitrified microsphere is 110 g, the ultraviolet lamp irradiation time is 6 s; the fluidized bed spraying template liquid atomization pressure is 0.19 MPa, the near-infrared laser power is 54 W, the modified fly ash is 450 g, the zinc borate@ZIF-8 core-shell flame retardant is 100 g, and the electrostatic adsorption voltage is 16 kV.

[0085] Comparative Example 1

[0086] The specific implementation is the same as that of Example 1, except that the calcination temperature of the desulfurized phosphogypsum is 140°C.

[0087] Comparative Example 2

[0088] The specific implementation is the same as that of Example 1, except that the mass ratio of the gypsum foaming agent to water is 1:4.

[0089] Comparative Example 3

[0090] The specific implementation is the same as that of Example 1, except that no modified composite material is added.

[0091] III. Performance Test

[0092] The fireproof door core board prepared from the desulfurized phosphogypsum prepared by the preparation process of the above Examples 1-3 and Comparative Examples 1-3 is tested according to the following test methods:

[0093] 1. The fire resistance limit test is performed according to GB / T 9978.1-2008 “Building Elements- Methods of Fire Resistance Test- Part 1: General Requirements”, and the specific operation is as follows: select a test piece with a size of 500mm×300mm×50mm, polish the surface flat and fix it in a horizontal fire resistance test furnace, apply a constant load at a rate of 0.8kN / min (about 1.5 times the weight of the test piece) through a hydraulic loading system, control the temperature in the furnace according to the ISO 834-1999 standard temperature rising curve (initial 30min rising to 540℃, then rising 8℃ per minute), record the time from the start of fire to the loss of load carrying capacity (manifested as the collapse of the middle part of the test piece more than 1 / 2 of the span or the displacement of any cross section more than 20% of the initial thickness) as the fire resistance limit.

[0094] 2. The compressive strength test is based on GB / T 5486-2012 “Test Methods for Inorganic Rigid Thermal Insulation”, the test piece is cured for 28d, the length, width and height are measured with a vernier caliper (accuracy 0.1mm), the compression area (length x width) is calculated, the test piece is placed in the center of the lower plate of the compression testing machine, and the loading rate is 0.5MPa / s, the maximum breaking load is recorded, and the compressive strength is the arithmetic mean of three test pieces (accurate to 0.1MPa).

[0095] 3. The density test is according to GB / T 17671-2021 “Cement and Concrete- Determination of Strength- Part 1: Determination of Compressive Strength of Hardened Hydrated Cement Mortar (ISO Method)”, the test piece is cured for 28d, the mass is weighed with an electronic balance (accuracy 0.01g), and the volume is measured by the drainage method (the test piece is completely immersed in water, and the volume of water displaced is measured), the density calculation formula is mass divided by volume (accurate to 1kg / m 3 ).

[0096] 4、Thermal conductivity test adopts GB / T 10294-2008 "Determination of Steady-state Thermal Resistance and Related Properties of Thermal Insulation Materials Guarded Hot Plate Method", selects a test piece with a thickness of 50 mm, polishes the surface to be flat with sandpaper, and then places it between the upper and lower pressure plates of the guarded hot plate device after cleaning. Apply a pressure of 0.1 MPa to make the test piece tightly contact with the pressure plate. Heat the plate at a rate of 10℃ / min from room temperature to 50℃ and stabilize for 30 min. After the heat flux density stabilizes, record the heat flow output of the heat flow meter and the temperature difference between the two sides of the test piece. The thermal conductivity calculation formula is heat flow multiplied by test piece thickness divided by temperature difference.

[0097] 5、28d shrinkage test refers to GB / T 25993-2023 "Foamed Concrete Block Unit Product Comprehensive Energy Consumption Limit", the test piece is first cured in a standard curing room (20±2℃, humidity ≥90%) for 7d, then transferred to a dry room (60±2℃) for curing until 28d. Measure the length, width and thickness (with a vernier caliper, accuracy 0.02mm) at 7d and 28d of curing respectively, calculate the shrinkage in each direction (shrinkage = (initial size - 28d size) / initial size x 100%), and take the average value of the three directions.

[0098] 6、CO release test is based on GB / T 20285-2006 "Material Smoke Toxicity Hazard Classification", using a cone calorimeter (radiation intensity set to 50kW / m 2 ), place the test piece in the center of the combustion chamber, ignite the upper surface of the test piece, remove the fire source after the flame stabilizes for 30s, collect the smoke within 30min after combustion, monitor the CO concentration (ppm) in the smoke in real time through an infrared gas analyzer, and the CO release calculation formula is CO release per unit mass of test piece (g / g) = (CO concentration x smoke flow x combustion time) / test piece mass.

[0099] 7、Performance test results:

[0100] Table 1: Performance test results of each example and comparative example

[0101]

[0102]

[0103] As can be seen from Table 1, the embodiments 1-3 of the present application effectively solve the problems of low strength, insufficient fire resistance, poor water resistance and inefficient utilization of industrial solid waste of the traditional fireproof door core board of desulfurization gypsum by process optimization and synergistic effect of modified composite materials: the porous structure of abandoned oyster shell powder formed by biomimetic mineralization and the closed pore characteristics of vitrified microbeads synergistically enhance each other in the modified composite material, and cooperate with the compounding system of desulfurization gypsum and building gypsum, which significantly improves the compressive strength of the material (the compressive strength of embodiments 1-3 is 8.2-8.8 MPa, which is much higher than 5.2-7.1 MPa of the comparative examples); the zinc borate@ZIF-8 core-shell flame retardant in the modified composite material decomposes to produce inert gas and form a heat-insulating carbon layer at high temperature, combined with the fire resistance of desulfurization gypsum, which greatly prolongs the fire resistance limit (the fire resistance limit of embodiments 1-3 is 185-198 min, which is much higher than 90-150 min of the comparative examples); the porous structure of the composite material and the low water absorption of desulfurization gypsum synergistically improve the water resistance (the shrinkage rate of embodiments 1-3 is only 0.2-0.3%, which is lower than 0.45-0.5% of the comparative examples); at the same time, the abandoned oyster shell powder, fly ash and other industrial solid waste are converted into functional fillers by ultrasonic dispersion, biomimetic mineralization and electrostatic adsorption processes, realizing high-value utilization and solving the problem of low utilization rate of solid waste in the traditional process.

[0104] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A manufacturing process for desulfurized gypsum fireproof door core board, characterized in that, Includes the following steps: S1, desulfurized phosphogypsum is calcined and activated at 150-200℃, cooled to 20-25℃ and mixed with desulfurized building gypsum, and modified composite material premix is ​​added to form a base material; cement is sieved to remove lumps; release agent is coated on the inner wall of the mold and preheated to 40-45℃; S2, the gypsum foaming agent is first pre-dissolved in water, allowed to stand to defoam, and then added to the mixer through a metering pump. At the same time, cement, base material, water-reducing agent, retarder, and cellulose are added to the mixer and the mixing is started. S3 uses a planetary mixer to first mix the dry materials at low speed, and then mix them at high speed to obtain a slurry; S4, after the slurry is poured into the mold, it is allowed to stand and set initially, and then the mold is removed after initial setting. The preparation steps of the modified composite material include: A1. Waste oyster shell powder is mixed with chitosan solution, ultrasonically dispersed, and then calcium acetate is added. The mixture is reacted at 45-50℃ to form a biomineralization template solution. Vitrified microspheres are immersed in acrylate monomers containing photoinitiator TPO and irradiated with ultraviolet light to form a prepolymer adhesive layer. A2, transfer to a fluidized bed, spray the template liquid prepared in step A1, and simultaneously turn on the near-infrared laser to scan the surface to trigger a local mineralization reaction; mix the plasma-activated modified fly ash with zinc borate@ZIF-8 core-shell flame retardant, and then deposit it directionally into the mineralization layer through an electrostatic adsorption device.

2. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, In step S1, the premixing time is 10-15 minutes; the cement is passed through an 80-85 mesh sieve.

3. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, In step S2, the mass ratio of the gypsum foaming agent to water is 1:(5-6), the pre-dissolution temperature is 30-35℃, the standing time is 5-10 min, the gypsum foaming agent is added to the mixer 3-4 times by a metering pump, with an interval of 2-3 min between each addition, and the stirring speed is 30-40 r / min.

4. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, In step S3, the low-speed stirring speed is 30-40 r / min and the low-speed stirring time is 3-4 min; the high-speed stirring speed is 60-80 r / min and the high-speed stirring time is 5-6 min.

5. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, In step S4, the temperature of the slurry is 25-30℃, and the settling time is 15-20 minutes.

6. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, The manufacturing process of the desulfurized gypsum fireproof door core board also includes: letting the door core board prepared in step S4 stand at a temperature of 20-30℃ for 72-144 hours.

7. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, In step A1, the particle size of the waste oyster shell powder is 200-250 mesh; the mass ratio of the waste oyster shell powder to the chitosan solution is 1:(3-4); the reaction time is 30-40 min; the particle size of the vitrified microspheres is 1-1.5 mm; the wavelength of the ultraviolet lamp is 365-370 nm; and the irradiation time is 5-8 s.

8. The manufacturing process of desulfurized gypsum fireproof door core board according to claim 1, characterized in that, In step A2, the atomization pressure of the template liquid prepared in step A1 is 0.15-0.2 MPa; the wavelength of the near-infrared laser is 1064-1070 nm and the power is 50-55 W; the mass ratio of the modified fly ash to the zinc borate@ZIF-8 core is (4-5):1; and the voltage of the electrostatic adsorption device is 15-16 kV.

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