Fluoride and oxide synergistically modified metallurgical solid waste-based foamed glass-ceramics and preparation method thereof

Abstract

The application discloses a kind of fluoride and oxide synergistically modified metallurgical solid waste-based foam glass-ceramics and preparation method thereof, and metallurgical solid waste material, crystallization control foam homogenizing agent, melting temperature pre-positioned melting promoter, copper-containing slag tailings in metallurgical solid waste, secondary aluminum ash, waste glass, fly ash, desulfurization gypsum are pressed into shape;Melting temperature pre-positioned melting promoter includes the mixture of one or several of magnesium fluorosilicate, sodium fluoroborate, potassium fluorozirconate, barium fluoride and lithium fluoride;Crystallization control foam homogenizing agent uses the mixture of one or several of samarium oxide, praseodymium oxide, gadolinium oxide and erbium oxide;Sintering is carried out to the shaped body, and foam glass-ceramics is obtained.The application can effectively reduce sintering temperature, reduce energy consumption, while making foam glass-ceramics have regular pore structure and excellent compressive strength, and also can realize the resource utilization of copper slag tailings, secondary aluminum ash, fly ash, waste glass and desulfurization gypsum and other solid wastes.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and green manufacturing technology, specifically relating to a fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass and its preparation method. Background Technology

[0002] Foamed microcrystalline glass is a new type of inorganic non-metallic material that integrates a porous structure and a microcrystalline matrix. It has excellent properties such as high compressive strength, sound absorption and sound insulation, and resistance to chemical corrosion. It can maintain structural integrity and functional stability for a long time in harsh environments. It has great potential for application in building energy conservation, underground protection and industrial insulation. It is a key high-performance material for green energy-saving buildings and long-life major projects.

[0003] Currently, utilizing industrial solid waste to prepare foamed microcrystalline glass has become an important way to utilize bulk solid waste resources, and various metallurgical and industrial solid wastes are also being widely tried as the main raw materials for preparation. However, due to the inherent high melting point of solid waste components, existing technologies generally face core bottlenecks such as excessively high sintering temperatures and high energy costs. Among them, Chinese patent CN113548802B uses waste incineration fly ash and magnesia ore as raw materials, and combines limestone, dolomite and other foaming agents, trisodium phosphate foam stabilizer and TiO2, ZrO2 and other component crystal nucleating agents. It still needs to be prepared in a high temperature environment of 1300~1600℃ to produce finished products. Chinese patents CN113788623B and CN115028367B use secondary aluminum ash slag and its pre-calcined products as raw materials, and introduce quicklime, borax and other viscosity modifiers and trisodium phosphate foam stabilizer to optimize the system performance. However, the preparation temperature is still maintained in the high range of 1000~1350℃. Chinese patent CN115403404B uses electrolytic manganese slag as raw material, and combines graphite, charcoal and other carbonaceous reducing agents as foaming agents. The sintering temperature is also as high as 1150~1300℃. This strong dependence on high-temperature thermal conditions not only significantly increases the preparation cost but also severely restricts the large-scale application of solid waste-based foamed microcrystalline glass. Meanwhile, to balance the preparation process and material properties, existing research has introduced functional additives into the system for modification and optimization, such as the introduction of carbon powder and iron oxide as crystal forming agents in Chinese patent CN113860748B. However, the modifying effects of existing additives generally have obvious limitations and lack synergy. While relying solely on fluxing components can lower the melting temperature, it easily leads to an excess of the glass phase, hindering the crystallization process and causing a significant decrease in the material's mechanical strength. Introducing only nucleating agents can promote microcrystalline precipitation, but if the melt viscosity cannot be precisely matched with the foaming process, it can cause defects such as uncontrolled foaming, uneven pore distribution, and structural collapse. Summary of the Invention

[0004] To address the core challenges of existing technologies, such as high sintering temperatures, high energy consumption, and the difficulty in achieving both foaming effect and mechanical strength, this invention aims to provide a method for preparing metallurgical solid waste-based foamed microcrystalline glass, which is synergistically modified with fluorides and oxides. This invention can effectively reduce sintering temperature and energy consumption, while simultaneously enabling the foamed microcrystalline glass to possess both a regular pore structure and excellent compressive strength. It can also achieve high-value conversion and resource utilization of solid wastes such as copper slag tailings, secondary aluminum ash, fly ash, waste glass, and desulfurization gypsum.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing metallurgical solid waste-based foamed microcrystalline glass synergistically modified with fluorides and oxides includes the following steps: The raw material mixture is pressed into a molded blank. The raw material mixture, by mass percentage, comprises: 85-95 parts metallurgical solid waste, 2-7 parts crystallization and foam control homogenizer, and 3-9 parts pre-melting temperature accelerator. The metallurgical solid waste contains, by mass percentage, 15%-35% copper slag tailings, 5%-15% secondary aluminum ash, 40%-55% waste glass, 10%-20% fly ash, and 0%-10% desulfurized gypsum. The pre-melting temperature accelerator comprises one or more of magnesium fluorosilicate, sodium fluoroborate, potassium fluorozirconate, barium fluoride, and lithium fluoride. The crystallization and foam control homogenizer is one or more of samarium oxide, praseodymium oxide, gadolinium oxide, and erbium oxide. The shaped preform is sintered to obtain the fluoride and oxide synergistic modified metallurgical solid waste-based foam microcrystalline glass; wherein, the sintering of the shaped preform includes the following processing stages in sequence: low-temperature pre-sintering and stabilization stage under micro-negative pressure, low-temperature directional nucleation pretreatment stage, pulse step heating-pulse step heating-melt bubble crystallization synergistic stage, rapid cooling-crystal phase and pore structure shaping stage, and slow cooling stress relief shaping stage.

[0006] Preferably, the sintering process for the formed blank is as follows: Low-temperature pre-firing and stabilization stage under slight negative pressure: Under a negative pressure of -0.02 to -0.05 MPa, the formed blank is heated to a stabilization holding temperature of 380 to 450°C at a rate of 3 to 5°C / min, and held for 20 to 35 minutes. Low-temperature directional nucleation pretreatment stage: Remove the negative pressure and heat to the directional nucleation holding temperature of 680~780℃ at a rate of 5~8℃ / min, and hold for 30~40min; The process involves a three-step pulsed step heating process followed by segmented holding. The first step involves a pulse heating rate of 4-6°C / min to the initial softening holding temperature of 950-1000°C, held for 5-10 minutes. The second step involves a pulse heating rate of 4-6°C / min to the foaming nucleation holding temperature of 1030-1080°C, held for 5-15 minutes. The third step involves a pulse heating rate of 4-6°C / min to the synergistic holding temperature of 1090-1130°C for 20-40 minutes, achieving simultaneous melting, foaming, and crystallization. Rapid cooling - crystal phase and pore structure shaping stage: Cool at a rate of 20~30℃ / min to the shaping holding temperature of 900~950℃, hold for 15~40min to fix the crystal phase and pore structure; Slow cooling stress relief and shaping stage: Cool at a rate of 2~3℃ / min to the stress relief holding temperature of 490~510℃, hold for 60~90min, and then let it cool naturally with the furnace to room temperature to eliminate internal stress.

[0007] Preferably, by mass percentage, the copper slag tailings contain: 4%~7% Al2O3, 20%~25% SiO2, 2%~6% CaO, 50%~65% Fe2O3, 1%~4% Na2O, 1%~4% MgO, with the balance being unavoidable impurities.

[0008] Preferably, by mass percentage, the secondary aluminum ash contains: 80%~90% Al2O3, 1%~5% SiO2, 2%~5% CaO, 0~2% Fe2O3, 4%~6% Na2O, with the balance being unavoidable impurities.

[0009] Preferably, by mass percentage, the waste glass contains: 1%~3% Al2O3, 70%~77% SiO2, 6%~8% CaO, 1%~3% Fe2O3, 12%~16% Na2O, 3%~5% MgO, with the balance being unavoidable impurities.

[0010] Preferably, by mass percentage, fly ash contains: 45%~60% SiO2, 20%~35% Al2O3, 2%~8% CaO, 3%~10% Fe2O3, 1%~3% Na2O, with the remainder being unavoidable impurities.

[0011] Preferably, the desulfurized gypsum contains, by mass percentage: 30%~45% CaO, 40%~55% SO3, 1%~5% SiO2, with the remainder being unavoidable impurities.

[0012] Preferably, when pressing the raw material mixture, the raw material mixture is pressed into a cylindrical blank under a pressure of 35~45KN.

[0013] Preferably, the particle size of the metallurgical solid waste is 200-300 mesh, the particle size of the crystallization and foam control homogenizer is 150-200 mesh, and the particle size of the pre-melting temperature accelerator is 150-200 mesh.

[0014] This invention also provides a fluoride and oxide synergistic modified metallurgical solid waste-based foam microcrystalline glass, which is prepared by the preparation method described above. The bulk density of the fluoride and oxide synergistic modified metallurgical solid waste-based foam microcrystalline glass is 0.45~1.15 g / cm³. 3 It has a porosity of 45.2%~77.8%, a compressive strength of 1.8~6.8MPa, and a crystallinity of 30.1%~48.5%.

[0015] The present invention has the following beneficial effects: The present invention discloses a method for preparing metallurgical solid waste-based foamed microcrystalline glass synergistically modified with fluorides and oxides. This method employs a pre-melting catalyst based on a fluoride system and a crystallization-controlling homogenizer based on a rare earth oxide system, combined with low-temperature pre-sintering stabilization under micro-negative pressure, low-temperature directional nucleation pretreatment, and pulsed stepwise heating. Synergistic effect of melt bubble crystallization and rapid cooling The five-stage gradient sintering process, which involves crystal phase and pore structure shaping, and slow cooling stress relief shaping, fundamentally solves the problems of high sintering temperature, high energy consumption, difficulty in coordinating foaming and crystallization, uneven pore structure, and low mechanical strength in the existing metallurgical solid waste-based foam microcrystalline glass preparation process. Specifically, the pre-melting temperature accelerator of this invention can effectively reduce the softening temperature of the system, improve melt fluidity, and advance the melting process, significantly reducing sintering temperature and production energy consumption. The crystallization and foam control homogenizer can promote controlled crystallization of the system, optimize pore uniformity, and inhibit over-burning. The two work synergistically. This approach avoids the drawbacks of a single fluxing component causing excess glass phase, hindering crystallization, and reducing mechanical strength. It also solves the problem of melt viscosity mismatch with the foaming process, leading to uncontrolled foaming and pore structure collapse, which can easily result from simply strengthening crystallization. Furthermore, using copper slag tailings, secondary aluminum ash, waste glass, fly ash, and desulfurized gypsum as core raw materials, it enables high-proportion resource utilization of various bulk metallurgical solid wastes. The resulting foamed microcrystalline glass possesses both a regular and stable pore structure and excellent compressive strength, with a bulk density reaching 0.45~1.15 g / cm³. 3 With a porosity of 45.2%~77.8%, a compressive strength of 1.8~6.8MPa, and a crystallinity of 30.1%~48.5%, it achieves a dual improvement in material performance and high-value utilization of solid waste while reducing costs and energy consumption. Attached Figure Description

[0016] Figure 1 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 1 of this invention. Figure 2 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 2 of this invention. Figure 3 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 3 of this invention. Figure 4 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 4 of this invention. Figure 5 This is a morphology diagram of the foamed glass prepared in Comparative Example 1 of the present invention. Figure 6 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 5 of this invention. Figure 7 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 6 of this invention. Figure 8 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 7 of this invention. Figure 9 This is a morphology diagram of the foamed glass prepared in Comparative Example 2 of the present invention. Figure 10 The image shows the surface morphology of the foamed glass-ceramic prepared in Example 8 of this invention. Figure 11 The volume density, porosity, and compressive strength of the foamed microcrystalline glass prepared in Examples 1-8 and Comparative Examples 1-2 of this invention are shown in the diagram. Figure 12 The crystallinity diagrams are for the foam microcrystalline glass prepared in Examples 1-8 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] This invention addresses the problems of high sintering temperature, poor melt flowability, uneven pore structure, and high energy consumption and cost in the existing preparation process of foamed microcrystalline glass. It provides a fluoride and oxide synergistic modification method for metallurgical solid waste-based foamed microcrystalline glass. The main raw materials used in this method are copper slag tailings, secondary aluminum ash, waste glass matrix, fly ash, and desulfurized gypsum. By introducing a crystallization-controlling homogenizer and a pre-melting temperature-inducing melt promoter for synergistic modification, the system achieves controlled crystallization, optimizes pore uniformity, inhibits over-burning, and reduces softening and sintering temperatures. This improves solid waste utilization, reduces energy consumption and cost, and provides a regular pore structure and excellent compressive strength.

[0019] By weight, the raw materials for this foamed microcrystalline glass include 85-95 parts metallurgical solid waste, 2-7 parts crystallization and foam control homogenizer, and 3-9 parts pre-melting temperature accelerator. The crystallization and foam control homogenizer is one or a mixture of several of samarium oxide, praseodymium oxide, gadolinium oxide, and erbium oxide. The pre-melting temperature accelerator includes one or a mixture of several of magnesium fluorosilicate, sodium fluoroborate, potassium fluorozirconate, barium fluoride, and lithium fluoride.

[0020] By mass percentage, the solid waste contains: 15%–35% copper slag tailings, 5%–15% secondary aluminum ash, 40%–55% waste glass, 10%–20% fly ash, and 0%–10% desulfurization gypsum. In the following embodiments of the present invention, the solid waste used consists of copper slag tailings, secondary aluminum ash, waste glass, fly ash, and desulfurization gypsum, wherein the copper slag tailings comprise 25%, secondary aluminum ash 10%, waste glass 50%, fly ash 10%, and desulfurization gypsum 5%.

[0021] The chemical composition and content of the copper slag tailings used in the above-mentioned scheme of the present invention, by mass percentage, are as follows: The copper slag tailings contain: 4%~7% Al2O3, 20%~25% SiO2, 2%~6% CaO, 50%~65% Fe2O3, 1%~4% Na2O, 1%~4% MgO, with the balance being unavoidable impurities. The copper slag tailings used in the following embodiments of the present invention contain: 5.6% Al2O3, 23.2% SiO2, 4.1% CaO, 58.7% Fe2O3, 2.0% Na2O, 2.4% MgO, with the balance being unavoidable impurities.

[0022] By mass percentage, secondary aluminum ash contains: 80%~90% Al2O3, 1%~5% SiO2, 2%~5% CaO, 0~2% Fe2O3, 4%~6% Na2O, with the balance being unavoidable impurities. The secondary aluminum ash used in the following embodiments of the present invention contains: 86.5% Al2O3, 3.2% SiO2, 3.6% CaO, 1.1% Fe2O3, 5.0% Na2O, with the balance being unavoidable impurities.

[0023] By mass percentage, waste glass contains: 1%~3% Al2O3, 70%~77% SiO2, 6%~8% CaO, 1%~3% Fe2O3, 12%~16% Na2O, 3%~5% MgO, with the balance being unavoidable impurities. The waste glass used in the following embodiments of the present invention contains: 1.9% Al2O3, 72.3% SiO2, 7.1% CaO, 1.2% Fe2O3, 13.6% Na2O, 3.8% MgO, with the balance being unavoidable impurities.

[0024] By mass percentage, fly ash contains: 45%~60% SiO2, 20%~35% Al2O3, 2%~8% CaO, 3%~10% Fe2O3, and 1%~3% Na2O, with the balance being unavoidable impurities. The fly ash used in the following embodiments of the present invention contains: 52.4% SiO2, 28.6% Al2O3, 5.3% CaO, 7.2% Fe2O3, and 1.8% Na2O, with the balance being unavoidable impurities.

[0025] By mass percentage, desulfurized gypsum contains: 30%~45% CaO, 40%~55% SO3, 1%~5% SiO2, with the balance being unavoidable impurities. The desulfurized gypsum used in the following embodiments of the present invention contains: 38.6% CaO, 48.2% SO3, 3.1% SiO2, with the balance being unavoidable impurities.

[0026] Using the above-mentioned raw materials, the specific preparation method of the foamed microcrystalline glass of the present invention includes the following steps: Step 1: Grind and dry the main raw materials, including copper slag tailings, secondary aluminum ash, waste glass, fly ash, and desulfurized gypsum, and control the particle size of metallurgical solid waste to 200-300 mesh; add crystallization and foam control homogenizing agent with a particle size of 150-200 mesh and preheating melting accelerator, and mix all raw materials and additives thoroughly to obtain a mixed powder with uniform particle size distribution (i.e., raw material mixture).

[0027] Step 2: Dry the raw material mixture obtained in Step 1 to remove moisture and obtain a dried raw material mixture; Step 3: Place the dried raw material mixture obtained in Step 2 into a mold and press it under a pressure of 35~45KN to obtain a cylindrical blank with a diameter of 30mm and a height of 20mm. Step 4: The shaped blank obtained in Step 3 (i.e., the cylindrical blank) is heat-treated according to a preset regime to finally obtain the target foamed microcrystalline glass. The heat treatment adopts a segmented temperature-controlled sintering process, which is divided into the following stages: micro-negative pressure low-temperature pre-sintering and stabilization stage, low-temperature directional nucleation pretreatment stage, pulse step heating-pulse step heating-melt bubble crystallization synergistic stage, rapid cooling-crystal phase and pore structure shaping stage, and slow cooling stress relief shaping stage. The specific details of each stage are as follows: Low-temperature pre-firing and stabilization stage under slight negative pressure: The room temperature is increased to the stabilization holding temperature of 380~450℃ at a rate of 3~5℃ / min, and the holding temperature is maintained for 20~35min. The furnace is maintained under a slight negative pressure of -0.02~-0.05MPa.

[0028] Low-temperature directional nucleation pretreatment stage: Remove the negative pressure and raise the temperature at 5~8℃ / min to the directional nucleation holding temperature of 680~780℃, and hold for 30~40min.

[0029] The process involves a three-step pulsed step heating process followed by segmented holding. The first step involves a pulsed heating rate of 4-6°C / min to the initial softening holding temperature of 950-1000°C, held for 5-10 minutes, pre-activating the fluoride melting-promoting components and forming a moderately viscous liquid phase in the billet. The second step involves a pulsed heating rate of 4-6°C / min to the foaming nucleation holding temperature of 1030-1080°C, held for 5-15 minutes, gradually releasing the gas source components from the secondary aluminum ash and copper slag tailings and forming stable bubble nuclei. The third step involves a pulsed heating rate of 4-6°C / min to the synergistic holding temperature of 1090-1130°C, held for 20-40 minutes, allowing simultaneous melting foaming, bubble wall viscosity adjustment, and rare earth-induced crystallization.

[0030] Rapid cooling - crystal phase and pore structure shaping stage: rapidly cool to a shaping holding temperature of 900~950℃ at a rate of 20~30℃ / min, hold for 15~40min to fix the crystal phase and pore structure.

[0031] Slow cooling and stress relief shaping stage: Slowly cool to the stress relief holding temperature of 490~510℃ at 2~3℃ / min, hold for 60~90min, and then let it cool naturally to room temperature with the furnace to eliminate internal stress.

[0032] The mechanism of this invention is explained below: In terms of raw material composition, the advantages of this invention can be summarized as follows: 1) This invention uses copper slag tailings, secondary aluminum ash, waste glass, fly ash, and desulfurized gypsum as core metallurgical solid waste raw materials, and adopts a segmented temperature-controlled sintering process to prepare foamed microcrystalline glass. The metallurgical solid waste contains 20%~35% copper slag tailings, 5%~12% secondary aluminum ash, 40%~55% waste glass, 10%~20% fly ash, and desulfurized gypsum at 3%~6%. This invention realizes the large-scale, high-value synergistic disposal of bulk metallurgical solid waste and waste glass, effectively reduces the ecological and environmental risks caused by solid waste stockpiling, and is in line with the solid waste resource utilization and low-carbon development strategy. 2) In the above preparation process, a crystallization and foam control homogenizer composed of at least one of samarium oxide, praseodymium oxide, gadolinium oxide, and erbium oxide was added, along with a pre-melting temperature accelerator composed of at least one of magnesium fluorosilicate, sodium fluoroborate, potassium fluorozirconate, barium fluoride, and lithium fluoride. These two types of additives work synergistically to modify the material. The core function of the pre-melting temperature accelerator is to facilitate the pre-sintering and stabilization of the billet under slight negative pressure at low temperature through the F... - Breaking the oxygen bonds in the silicon-oxygen network significantly reduces the melting temperature and melt viscosity of the system, optimizing the heating uniformity and heat transfer efficiency of the batch, and laying a good thermodynamic foundation for subsequent foaming and crystallization. During the synergistic stage of pulsed step heating-pulse step heating-crystallization, the active components generated by fluoride decomposition form a eutectic liquid phase, effectively improving high-temperature fluidity, promoting stable retention of foaming gas and uniform pore growth, while simultaneously suppressing over-foaming by controlling melt viscosity. In the bubble-forming stage, the viscous glassy phase induced by fluoride possesses suitable viscosity-temperature characteristics, providing stable support for the pore structure, preventing pore wall collapse and abnormal pore merging at high temperatures, and ensuring the integrity of the pore topology. The core role of the crystallization-controlling homogenizer is: during the low-temperature pre-sintering stabilization stage under micro-negative pressure, Gd... 3+ 、Sm 3+ Pr 4+ Er 3+Rare earth cations, with their high field strength, form high-energy bonds with bridging or non-bridging oxygen in the glass network, enhancing the network polymerization degree and crosslinking density. This strengthens the stability of the glass skeleton during the low-temperature directional nucleation pretreatment stage. In the synergistic stage of pulsed step heating-pulse step heating-molten bubble crystallization, rare earth oxides serve as efficient heterogeneous nucleation sites, reducing the Gibbs free energy barrier for crystallization and promoting uniform, high-density nucleation of the main crystalline phase. Simultaneously, following the Zener pinning effect, they suppress grain coarsening, achieving grain size refinement and optimizing the ratio and distribution of crystal and glass phases. During the bubble shaping stage, the introduction of rare earth elements increases the high-temperature viscosity and structural relaxation barrier of the glass phase, enhancing the material's resistance to temperature-induced structural disorder and maintaining microstructure uniformity and dimensional stability. Finally, rare earth cations accumulate at the crystal phase interface, strengthening interfacial bonding through strong chemical bonding, synergistically refining grains and optimizing pore structure, significantly improving the macroscopic mechanical properties and environmental stability of the foamed glass-ceramic, and compensating for the shortcomings of single-additive modification systems in achieving both low-energy sintering and high performance.

[0033] In the pulsed step heating-melting bubble crystallization synergistic stage of glass-ceramic foam, the key steps of this invention include the following aspects: 1) By precisely controlling the sintering temperature between 1100 and 1150℃, a high-temperature oxidation cascade reaction of AlN in the secondary aluminum ash is first triggered, generating Al2O3 and N2 as the core gas source. Simultaneously, Fe2O3 in the copper slag tailings undergoes a valence state transformation, releasing trace amounts of O2. These two types of gases synergistically constitute a stable foaming driving force. In the system, the silicate and aluminosilicate viscous phases formed by the reaction of copper slag tailings, secondary aluminum ash, and waste glass provide structural support for stable bubble growth by regulating the melt viscosity, preventing gas escape. During this process, the gas phase and the molten liquid phase form a dynamic equilibrium system. Driven by Marangoni convection, the bubbles diffuse uniformly in the viscoelastic matrix. Through the continuous process of bubble nucleation, growth, and stabilization, a three-dimensional interconnected pore network with uniform pore size distribution is constructed. This in-situ self-foaming mechanism based on the components of solid waste does not require the addition of external foaming agents. It avoids the defects of uneven pores and secondary pollution caused by traditional chemical foaming agents, and achieves precise control of pore structure through the micro-region synergistic effect of iron-based and aluminum-based components, thus taking into account both the lightweight characteristics and structural integrity of the material.

[0034] 2) This invention introduces at least one of magnesium fluorosilicate, sodium fluoroborate, potassium fluorozirconate, barium fluoride, and lithium fluoride as a pre-melting temperature accelerator, achieving efficient expansion of the system's melting range through the strong polarization effect of fluoride ions. -This process preferentially attacks and breaks the Si-O-Si bridging oxygen bonds in the silicate network, disrupting the network's polymerization degree and causing lattice structure distortion. Existing solid waste-based foam microcrystalline glass processes typically require sintering or melting at temperatures above 1150℃ or even 1300℃. However, this application, through the synergistic effect of a pre-melting temperature accelerator and a crystallization-controlling homogenizer, controls the synergistic holding temperature for melt-foam crystallization at 1090~1130℃. Furthermore, the sample examples still exhibit a porosity of 45.2%~77.8%, a compressive strength of 1.8~6.8MPa, and a crystallinity of 30.1%~48.5%, indicating that this process can achieve stable foaming, controlled crystallization, and pore structure shaping at a lower melt-foam crystallization temperature. This significantly improves process tolerance and energy efficiency. Meanwhile, fluorides optimize the interfacial reactivity between raw materials, promote uniform melt flow, effectively suppress local over-foaming and pore collapse, lay a uniform thermodynamic foundation for the subsequent crystallization process, and achieve synergy between low-energy sintering and pore structure optimization.

[0035] 3) In the raw material reaction and crystallization process, this invention uses copper slag tailings, secondary aluminum ash, waste glass, fly ash, and desulfurized gypsum as core raw materials. By controlling the heat treatment temperature at 1100~1130℃ and holding for 20~40min, the synergistic reaction of components such as SiO2, Al2O3, CaO, MgO, and Fe2O3 in the system is achieved. At the same time, at least one of samarium oxide, praseodymium oxide, gadolinium oxide, and erbium oxide is introduced as a crystallization-controlling homogenizing agent. Its rare earth cations, with their high field strength characteristics, form high bond energy bonds in the glass network, serving as efficient heterogeneous nucleation sites to reduce the crystallization energy barrier. This crystallization mechanism strengthens the pore wall framework through the interwoven growth of the main crystalline phase, supplemented by the grain-refining effect of rare earth elements, significantly improving the compressive strength and structural stability of the material. Meanwhile, the dense silicate network formed at high temperature can stabilize and solidify heavy metal ions in the raw materials, ensuring the environmental safety of the material.

[0036] 4) This invention employs a three-step pulsed stepped heating method instead of a one-step direct heating method. The reason is that the softening of the melt, gas release, bubble growth, and crystallization strengthening in the metallurgical solid waste system do not occur synchronously. If the temperature is increased from the nucleation temperature to the highest melting bubble crystallization temperature in one step, the temperature difference and viscosity gradient between the inside and outside of the billet will increase significantly. The gas released from AlN oxidation in secondary aluminum ash and the gas released from the valence state transformation of iron oxides in copper slag tailings are likely to occur in a short period of time, resulting in insufficient bubble nuclei, a sudden increase in local gas pressure, and rapid merging or dissipation of pores. At the same time, the heterogeneous nucleation and grain refinement process induced by rare earth oxides are delayed, which can easily lead to pore wall collapse, abnormally high porosity, and decreased compressive strength. The three-step pulse process decomposes the above process into three consecutive windows: "softening and preparation—foaming and nucleation—synergistic crystallization and shaping of melt bubbles." The first pulse holds the temperature at 950-1000℃ for 5-10 minutes, pre-activating the fluoride melting promoter, initially relaxing the silicon-oxygen network, and forming an initial liquid phase with suitable viscosity. The second pulse holds the temperature at 1030-1080℃ for 5-15 minutes, gradually releasing the gas source components and completing bubble nucleation and early growth, while avoiding large pores and cross-pores caused by instantaneous gas release. The third pulse holds the temperature at 1090-1130℃ for 20-40 minutes, matching the melt viscosity, internal pressure of the bubbles, and rare earth-induced crystallization rate, promoting stable shaping of the pore walls during the crystallization strengthening process. Therefore, the three-step pulse stepped heating improves the controllability and repeatability of the heat treatment window, and is more conducive to obtaining foamed microcrystalline glass with uniform pore size, intact pore walls, and high strength compared to a single direct heating step.

[0037] Example 1 By weight, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 90 parts metallurgical solid waste, 4 parts crystallization and foam control homogenizer, and 6 parts pre-melting temperature accelerator; the metallurgical solid waste comprises 25% copper slag tailings, 10% secondary aluminum ash, 50% waste glass, 10% fly ash, and 5% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of praseodymium oxide and samarium oxide, wherein the mass percentage of praseodymium oxide is 50% and the mass percentage of samarium oxide is 50%. The pre-melting temperature accelerator is a mixture of lithium fluoride and magnesium fluorosilicate, wherein the mass percentage of lithium fluoride is 50% and the mass percentage of magnesium fluorosilicate is 50%.

[0038] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After grinding, mixing, and pressing, the raw materials are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400℃ at a heating rate of 4℃ / min and held for 25 min. Then, the negative pressure is released, and the temperature is raised to 720℃ at a heating rate of 6℃ / min and held for 35 min for low-temperature directional nucleation pretreatment. The pulse heating stage employs a three-step pulsed stepped heating method: the first step raises the temperature to 980℃ at 5℃ / min and holds for 8 min; the second step raises the temperature to 1060℃ at 5℃ / min and holds for 10 min; the third step raises the temperature to 1120℃ at 5℃ / min and holds for 30 min, allowing melt foaming, foam wall viscosity adjustment, and rare earth-induced crystallization to occur simultaneously. The temperature was then lowered to 920℃ at a rate of 25℃ / min and held for 25 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 2.5℃ / min and held for 75 minutes. After that, it was allowed to cool naturally to room temperature in the furnace to eliminate internal stress.

[0039] The foamed glass-ceramic obtained in Example 1 has the following appearance morphology: Figure 1 It can be seen that the sample has a uniform and regular pore structure, a concentrated pore size distribution, intact pore walls without collapse or cracking, a high closed-pore rate, and a stable overall bubble structure.

[0040] The performance results and porosity of the foamed glass-ceramic prepared in Example 1 are as follows: Figure 11 and Figure 12 As shown, the bulk density of this foamed microcrystalline glass is 0.72 g / cm³. 3 It has a porosity of 65.4%, a compressive strength of 4.5 MPa, and a crystallinity of 38.5%.

[0041] Example 2 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 90 parts metallurgical solid waste, 5 parts crystallization and foam control homogenizer, and 5 parts pre-melting temperature accelerator; the metallurgical solid waste comprises 35% copper slag tailings, 8% secondary aluminum ash, 42% waste glass, 10% fly ash, and 5% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of gadolinium oxide, samarium oxide, and praseodymium oxide, with each of the three having a mass percentage of 33.3%. The pre-melting temperature accelerator is a mixture of sodium fluoroborate and barium fluoride, with sodium fluoroborate comprising 60% by mass and barium fluoride comprising 40% by mass.

[0042] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After grinding, mixing, and pressing, the raw materials are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.05 MPa, the temperature is raised to 450°C at a heating rate of 5°C / min and held for 35 min. Then, the negative pressure is released, and the temperature is raised to 780°C at a rate of 8°C / min and held for 40 min for low-temperature directional nucleation pretreatment. The pulse heating stage employs a three-step pulsed stepped heating method: the first step raises the temperature to 1000°C at 6°C / min and holds for 10 min; the second step raises the temperature to 1080°C at 6°C / min and holds for 15 min; the third step raises the temperature to 1130°C at 6°C / min and holds for 40 min, allowing melt foaming, foam wall viscosity adjustment, and rare earth-induced crystallization to occur simultaneously. The temperature was then lowered to 950℃ at a rate of 30℃ / min and held for 40 minutes to set the shape. Finally, it was slowly cooled to 510℃ at a rate of 3℃ / min and held for 90 minutes. After that, it was allowed to cool naturally to room temperature in the furnace to eliminate internal stress.

[0043] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 2 It can be seen that the sample has small and uniform pore size, dense and thick pore walls, no obvious pore wall cracks, pore merging and collapse, and the overall structure is dense and regular.

[0044] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of this foamed microcrystalline glass is 1.15 g / cm³. 3 It has a porosity of 45.2%, a compressive strength of 6.8 MPa, and a crystallinity of 46.2%.

[0045] Example 3 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 85 parts metallurgical solid waste, 6 parts crystallization and foam control homogenizer, and 9 parts pre-melting temperature accelerator; the metallurgical solid waste consists of 15% copper slag tailings, 15% secondary aluminum ash, 50% waste glass, 20% fly ash, and 0% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of erbium oxide and gadolinium oxide, with each of the two comprising 50% by mass. The pre-melting temperature accelerator is a mixture of lithium fluoride, sodium fluoroborate, and magnesium fluorosilicate, with each of the three comprising 33.3% by mass.

[0046] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After grinding, mixing, and pressing, the raw materials are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.02 MPa, the temperature is raised to 380°C at a heating rate of 3°C / min and held for 20 minutes. Then, the negative pressure is released, and the temperature is raised to 680°C at a rate of 5°C / min and held for 30 minutes for low-temperature directional nucleation pretreatment. The pulse heating stage employs a three-step pulsed stepped heating method: the first step raises the temperature to 950°C at 4°C / min and holds for 5 minutes; the second step raises the temperature to 1030°C at 4°C / min and holds for 5 minutes; the third step raises the temperature to 1090°C at 4°C / min and holds for 20 minutes, allowing melt foaming, foam wall viscosity adjustment, and rare-earth-induced crystallization to occur simultaneously. The temperature was then lowered to 900℃ at a rate of 20℃ / min and held for 15 minutes to set the shape. Finally, it was slowly cooled to 490℃ at a rate of 2℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature in the furnace to eliminate internal stress.

[0047] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 3 It can be seen that the sample exhibits a hierarchical pore structure with high porosity, uniform pore size distribution, concentrated in the range of 1.0~1.5mm, intact pore walls without large-area cracks, high proportion of closed pores, and an overall lightweight porous structure.

[0048] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of this foamed microcrystalline glass is 0.45 g / cm³. 3 It has a porosity of 77.8%, a compressive strength of 1.8 MPa, and a crystallinity of 32.7%.

[0049] Example 4 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 88 parts metallurgical solid waste, 4 parts crystallization and foam control homogenizer, and 8 parts pre-melting temperature accelerator; the metallurgical solid waste comprises 28% copper slag tailings, 8% secondary aluminum ash, 47% waste glass, 12% fly ash, and 5% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of samarium oxide and praseodymium oxide, each with a mass percentage of 50%. The pre-melting temperature accelerator is a mixture of potassium fluorozirconate and lithium fluoride, each with a mass percentage of 50%.

[0050] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400°C at a heating rate of 4°C / min and held at this temperature for 25 min. Then, the negative pressure is released, and the temperature is raised to 720°C at a heating rate of 6°C / min and held for 35 min to perform directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 950°C at 5°C / min and hold for 5 min; the second step is to raise the temperature to 1050°C at 5°C / min and hold for 10 min; and the third step is to raise the temperature to the target temperature of 1090°C at 5°C / min and hold for 25 min. The temperature was then lowered to 920℃ at a rate of 25℃ / min and held for 20 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 2℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0051] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 4 It can be seen that the sample pore walls are highly smooth, exhibiting an amorphous glassy morphology with uniform pore distribution, no obvious grain penetration structure, and good overall bubble toughness.

[0052] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of this foamed microcrystalline glass is 0.65 g / cm³. 3 It has a porosity of 71.5%, a compressive strength of 3.2 MPa, and a crystallinity of 30.1%.

[0053] Comparative Example 1 By mass percentage, the raw materials for the foamed microcrystalline glass in this comparative example include: 96 parts of metallurgical solid waste, 4 parts of crystallization and foam control homogenizer, and no pre-melting temperature accelerator added; the metallurgical solid waste consists of 25% copper slag tailings, 10% secondary aluminum ash, 50% waste glass, 10% fly ash, and 5% desulfurized gypsum (the missing mass percentage of pre-melting temperature accelerator is compensated by an equal amount of waste glass). The crystallization and foam control homogenizer is a mixture of praseodymium oxide and samarium oxide, with each of the two comprising 50% by mass.

[0054] The preparation method of this comparative example foamed microcrystalline glass includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment, and the sintering temperature curve is completely consistent with that of Example 1. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400°C at a heating rate of 4°C / min and held at that temperature for 25 min. Then, the negative pressure is released, and the temperature is raised to 720°C at a heating rate of 6°C / min and held for 35 min to carry out directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 980°C at 5°C / min and hold for 5 min; the second step is to raise the temperature to 1060°C at 5°C / min and hold for 10 min; and the third step is to raise the temperature to the target temperature of 1120°C at 5°C / min and hold for 25 min. The temperature was then lowered to 920℃ at a rate of 25℃ / min and held for 20 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 2℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0055] The morphology of the sample obtained in this comparative example is shown in the figure. Figure 5 It can be seen that the sample has no obvious pore structure and is in a dense state. After cooling, it exhibits severe macroscopic bursting and microscopic cracking, and has no complete foam structure.

[0056] The performance results and porosity of the samples prepared in this comparative example are as follows: Figure 11 and Figure 12 As shown, the bulk density of the sample is 2.40 g / cm³. 3 It has a porosity of 35.9%, a compressive strength of 0.8 MPa, and a crystallinity of 8.3%.

[0057] Example 5 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 93 parts metallurgical solid waste, 3 parts crystallization and foam control homogenizer, and 4 parts pre-melting temperature accelerator; the metallurgical solid waste consists of 30% copper slag tailings, 10% secondary aluminum ash, 45% waste glass, 15% fly ash, and 0% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of gadolinium oxide, erbium oxide, and praseodymium oxide, wherein the mass percentages of gadolinium oxide, erbium oxide, and praseodymium oxide are 37.5%, 37.5%, and 25%, respectively. The pre-melting temperature accelerator is a mixture of barium fluoride and potassium fluorozirconate, each with a mass percentage of 50%.

[0058] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400°C at a heating rate of 4°C / min and held for 25 min. Then, the negative pressure is released, and the temperature is raised to 720°C at a heating rate of 6°C / min and held for 35 min to perform directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 980°C at 5°C / min and hold for 5 min; the second step is to raise the temperature to 1060°C at 5°C / min and hold for 10 min; and the third step is to raise the temperature to the target temperature of 1120°C at 5°C / min and hold for 25 min. The temperature was then lowered to 940℃ at a rate of 25℃ / min and held for 30 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 3℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0059] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 6 It can be seen that the sample pore size is extremely fine, with most pores having a diameter of 0.2~0.5mm. There are many micropores, with uniform pore size distribution, dense pore walls, and no obvious pore merging phenomenon.

[0060] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of the sample is 0.88 g / cm³. 3 It has a porosity of 55.4%, a compressive strength of 5.5 MPa, and a crystallinity of 48.5%.

[0061] Example 6 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 87 parts metallurgical solid waste, 5 parts crystallization and foam control homogenizer, and 8 parts pre-melting temperature accelerator; the metallurgical solid waste comprises 20% copper slag tailings, 10% secondary aluminum ash, 50% waste glass, 15% fly ash, and 5% desulfurized gypsum. The crystallization and foam control homogenizer is a single component of samarium oxide. The pre-melting temperature accelerator is a mixture of magnesium fluorosilicate and barium fluoride, with each comprising 50% by mass.

[0062] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400℃ at a heating rate of 4℃ / min and held for 35 min. Then, the negative pressure is released and the temperature is raised to 720℃ at a heating rate of 6℃ / min and held for 35 min to perform directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 980℃ at 5℃ / min and hold for 5 min; the second step is to raise the temperature to 1060℃ at 5℃ / min and hold for 10 min; and the third step is to raise the temperature to the target temperature of 1125℃ at 5℃ / min and hold for 20 min. The temperature was then lowered to 920℃ at a rate of 25℃ / min and held for 20 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 2℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0063] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 7 It can be seen that the sample has a regular pore structure with pore size concentrated in the range of 0.6 to 0.9 mm. The pore walls have clear and dense grain boundaries, with no obvious pore collapse or merging. The overall structure has good stability.

[0064] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of the sample is 0.95 g / cm³. 3 It has a porosity of 52.1%, a compressive strength of 4.9 MPa, and a crystallinity of 42.3%.

[0065] Example 7 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 85 parts metallurgical solid waste, 7 parts crystallization and foam control homogenizer, and 8 parts pre-melting temperature accelerator; the metallurgical solid waste comprises 20% copper slag tailings, 5% secondary aluminum ash, 50% waste glass, 15% fly ash, and 10% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of erbium oxide, samarium oxide, and gadolinium oxide, wherein the mass percentage of erbium oxide is 50%, the mass percentage of samarium oxide is 30%, and the mass percentage of gadolinium oxide is 20%. The pre-melting temperature accelerator is a mixture of magnesium fluorosilicate and barium fluoride, wherein both are 50% by mass.

[0066] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass in this embodiment includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400°C at a heating rate of 4°C / min and held at this temperature for 25 min. Then, the negative pressure is released, and the temperature is raised to 720°C at a heating rate of 6°C / min and held for 35 min to perform directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 980°C at 5°C / min and hold for 5 min; the second step is to raise the temperature to 1080°C at 5°C / min and hold for 5 min; the third step is to rapidly raise the temperature to the target temperature of 1130°C at 5°C / min and hold for 25 min. The temperature was then lowered to 920℃ at a rate of 25℃ / min and held for 20 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 3℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0067] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 8 It can be seen that the sample exhibits a hierarchical interconnected pore feature of "large pores enveloping small pores", with a complex internal pore network. The main pore diameter is concentrated in 1.2~1.8mm, and there are no large-area cracks in the pore walls.

[0068] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of the sample is 0.58 g / cm³. 3 It has a porosity of 69.4%, a compressive strength of 2.1 MPa, and a crystallinity of 31.5%.

[0069] Comparative Example 2 The foamed microcrystalline glass of this comparative example comprises the following raw material components by weight: 91 parts metallurgical solid waste, 9 parts without crystallization-controlling and homogenizing agent, and 9 parts of pre-melting temperature accelerator; the metallurgical solid waste includes 15% copper slag tailings, 15% secondary aluminum ash, 50% waste glass, 20% fly ash, and 0% desulfurized gypsum (the missing mass percentage of crystallization-controlling and homogenizing agent is compensated by an equal amount of fly ash). The pre-melting temperature accelerator is a mixture of lithium fluoride, sodium fluoroborate, and magnesium fluorosilicate, with each of the three components accounting for 33.3% by mass.

[0070] The preparation method of this comparative example of foamed microcrystalline glass includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment, and the sintering temperature curve is completely consistent with that of Example 3. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400°C at a heating rate of 4°C / min and held at that temperature for 25 min. Then, the negative pressure is released, and the temperature is raised to 720°C at a heating rate of 6°C / min and held for 35 min to carry out directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 960°C at 5°C / min and hold for 5 min; the second step is to raise the temperature to 1040°C at 5°C / min and hold for 10 min; and the third step is to raise the temperature to the target temperature of 1110°C at 5°C / min and hold for 20 min. The temperature was then lowered to 920℃ at a rate of 30℃ / min and held for 20 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 2℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0071] The morphology of the sample obtained in this comparative example is shown in the figure. Figure 9 It can be seen that the foaming process of the sample was completely out of control, and the cross section was full of huge irregular holes with a diameter of 2-5mm. Most of the hole walls were penetrated and cracked, forming an ineffective open structure, and the overall structure collapsed severely.

[0072] The performance results and porosity of the samples prepared in this comparative example are as follows: Figure 11 and Figure 12 As shown, the bulk density of the sample is 0.38 g / cm³. 3 It has a porosity of 82.0%, a compressive strength of 0.4 MPa, and a crystallinity of 12.6%.

[0073] Example 8 By mass percentage, the raw materials for the fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass in this embodiment include: 86 parts of metallurgical solid waste, 7 parts of crystallization and foam control homogenizer, and 7 parts of pre-melting temperature accelerator; the metallurgical solid waste comprises 25% copper slag tailings, 15% secondary aluminum ash, 40% waste glass, 15% fly ash, and 5% desulfurized gypsum. The crystallization and foam control homogenizer is a mixture of gadolinium oxide, praseodymium oxide, and samarium oxide, with each of the three having a mass percentage of 33.3%. The pre-melting temperature accelerator is a mixture of magnesium fluorosilicate and lithium fluoride, with each of the two having a mass percentage of 50%.

[0074] The preparation method of fluoride and oxide synergistic modification of metallurgical solid waste-based foam microcrystalline glass includes the following steps: After the raw materials are ground, mixed, and pressed into shape, they are placed in a resistance furnace for gradient heat treatment. First, under a slight negative pressure of -0.03 MPa, the temperature is raised to 400℃ at a heating rate of 4℃ / min and held at this temperature for 25 min. Then, the negative pressure is released, and the temperature is raised to 720℃ at a heating rate of 6℃ / min and held for 35 min to carry out directional nucleation. The pulse heating stage adopts a three-step pulsed stepped heating: the first step is to raise the temperature to 980℃ at 5℃ / min and hold for 5 min; the second step is to raise the temperature to 1060℃ at 5℃ / min and hold for 10 min; and the third step is to raise the temperature to the target temperature of 1120℃ at 5℃ / min and hold for 25 min. The temperature was then lowered to 950℃ at a rate of 25℃ / min and held for 40 minutes to set the shape. Finally, it was slowly cooled to 500℃ at a rate of 3℃ / min and held for 60 minutes. After that, it was allowed to cool naturally to room temperature with the furnace to eliminate internal stress.

[0075] The surface morphology of the foamed microcrystalline glass obtained in this embodiment is shown in the figure. Figure 10 It can be seen that the sample has a uniform and regular pore structure with pore size concentrated in the range of 0.7~1.0 mm. The pore walls are dense and the grain boundary bonding is strong. There are no pore wall collapses, cracks and abnormal merging of pores, and the overall structure has excellent stability.

[0076] The performance results and porosity of the foamed microcrystalline glass prepared in this embodiment are as follows: Figure 11 and Figure 12 As shown, the bulk density of the sample is 0.70 g / cm³. 3 It has a porosity of 66.2%, a compressive strength of 5.8 MPa, and a crystallinity of 47.9%.

[0077] The foamed microcrystalline glass of this invention is prepared using copper slag tailings, secondary aluminum ash, waste glass, fly ash, and desulfurized gypsum as core raw materials, combined with a crystallization-controlling and foam-homogenizing agent and a pre-melting temperature accelerator. The crystallization-controlling and foam-homogenizing agent can promote controlled crystallization of the system, optimize pore uniformity, and inhibit over-burning. The pre-melting temperature accelerator can reduce the softening temperature of the system, improve melt fluidity, and promote early melting to reduce sintering temperature. The synergistic effect of the two agents reduces energy consumption and cost while giving the product both a regular pore structure and excellent compressive strength.

[0078] The experimental results of the comparative examples and the comparative examples show that the samples of each example, which were synergistically modified with fluoride melt catalysts and rare earth oxides, all formed foamed microcrystalline glass with uniform pore size, intact pore walls, and stable structure, with a bulk density of 0.45~1.15 g / cm³. 3The first example had a porosity of 45.2%–77.8%, a compressive strength of 1.8–6.8 MPa, and a crystallinity of 30.1%–48.5%, combining lightweight porosity with good mechanical properties. The second example, without fluoride melt-accelerators, failed to melt and foam properly, exhibiting a dense state and cracking, with a porosity of only 35.9%, a compressive strength of only 0.8 MPa, and a crystallinity as low as 8.3%. The third example, without rare earth oxide crystallization control agents, showed completely uncontrolled foaming, with pore wall rupture and severe structural collapse. Although the porosity was as high as 82.0%, the compressive strength was only 0.4 MPa, and the crystallinity was only 12.6%, with overall performance far inferior to the first example. This fully demonstrates the crucial role of the synergistic effect of the two additives in improving the material's structure and properties.

[0079] In summary, this invention activates the in-situ spontaneous foaming reaction of solid waste through temperature control during the pulsed step heating-melting and crystallization synergistic stage of foamed microcrystalline glass, achieves low-temperature energy-saving sintering with the help of fluorides, and relies on rare earth oxides to induce efficient crystallization and optimize pore wall structure. The synergistic effect of these three factors significantly improves the preparation efficiency, cost advantage, and comprehensive performance of foamed microcrystalline glass, providing an efficient technical path for the high-value utilization of metallurgical solid waste.

[0080] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0081] 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 it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing metallurgical solid waste-based foamed microcrystalline glass synergistically modified with fluorides and oxides, characterized in that, The process includes the following: The raw material mixture is pressed into a molded blank. The raw material mixture, by mass percentage, comprises: 85-95 parts metallurgical solid waste, 2-7 parts crystallization and foam control homogenizer, and 3-9 parts pre-melting temperature accelerator. The metallurgical solid waste contains, by mass percentage, 15%-35% copper slag tailings, 5%-15% secondary aluminum ash, 40%-55% waste glass, 10%-20% fly ash, and 0%-10% desulfurized gypsum. The pre-melting temperature accelerator comprises one or more of magnesium fluorosilicate, sodium fluoroborate, potassium fluorozirconate, barium fluoride, and lithium fluoride. The crystallization and foam control homogenizer is one or more of samarium oxide, praseodymium oxide, gadolinium oxide, and erbium oxide. The shaped preform is sintered to obtain the fluoride and oxide synergistic modified metallurgical solid waste-based foam microcrystalline glass; wherein, the sintering of the shaped preform includes the following processing stages in sequence: low-temperature pre-sintering and stabilization stage under micro-negative pressure, low-temperature directional nucleation pretreatment stage, pulse step heating-pulse step heating-melt bubble crystallization synergistic stage, rapid cooling-crystal phase and pore structure shaping stage, and slow cooling stress relief shaping stage.

2. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, The specific process for sintering the shaped blank is as follows: Low-temperature pre-firing and stabilization stage under slight negative pressure: Under a negative pressure of -0.02 to -0.05 MPa, the formed blank is heated to a stabilization holding temperature of 380 to 450°C at a rate of 3 to 5°C / min, and held for 20 to 35 minutes. Low-temperature directional nucleation pretreatment stage: Remove the negative pressure and heat to the directional nucleation holding temperature of 680~780℃ at a rate of 5~8℃ / min, and hold for 30~40min; The process involves a three-step pulsed step heating process followed by segmented holding. The first step involves a pulse heating rate of 4-6°C / min to the initial softening holding temperature of 950-1000°C, held for 5-10 minutes. The second step involves a pulse heating rate of 4-6°C / min to the foaming nucleation holding temperature of 1030-1080°C, held for 5-15 minutes. The third step involves a pulse heating rate of 4-6°C / min to the synergistic holding temperature of 1090-1130°C for 20-40 minutes, achieving simultaneous melting, foaming, and crystallization. Rapid cooling - crystal phase and pore structure shaping stage: Cool at a rate of 20~30℃ / min to the shaping holding temperature of 900~950℃, and hold for 15~40min; Slow cooling and stress relief shaping stage: Cool at a rate of 2~3℃ / min to the stress relief holding temperature of 490~510℃, hold for 60~90min, and then let it cool naturally to room temperature with the furnace.

3. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, By mass percentage, copper slag tailings contain: 4%~7% Al2O3, 20%~25% SiO2, 2%~6% CaO, 50%~65% Fe2O3, 1%~4% Na2O, 1%~4% MgO, with the remainder being unavoidable impurities.

4. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, By mass percentage, secondary aluminum ash contains: 80%~90% Al2O3, 1%~5% SiO2, 2%~5% CaO, 0~2% Fe2O3, 4%~6% Na2O, with the remainder being unavoidable impurities.

5. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, By mass percentage, waste glass contains: 1%~3% Al2O3, 70%~77% SiO2, 6%~8% CaO, 1%~3% Fe2O3, 12%~16% Na2O, 3%~5% MgO, with the remainder being unavoidable impurities.

6. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, By mass percentage, fly ash contains: 45%~60% SiO2, 20%~35% Al2O3, 2%~8% CaO, 3%~10% Fe2O3, 1%~3% Na2O, with the remainder being unavoidable impurities.

7. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, By mass percentage, desulfurized gypsum contains: 30%~45% CaO, 40%~55% SO3, 1%~5% SiO2, with the remainder being unavoidable impurities.

8. The method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to claim 1, characterized in that, When the raw material mixture is pressed into shape, it is pressed into a cylindrical blank under a pressure of 35~45KN.

9. A method for preparing fluoride and oxide synergistically modified metallurgical solid waste-based foamed microcrystalline glass according to any one of claims 1-8, characterized in that, The particle size of the metallurgical solid waste is 200-300 mesh, the particle size of the crystallization and foam control homogenizer is 150-200 mesh, and the particle size of the pre-melting temperature accelerator is 150-200 mesh.

10. A fluoride and oxide synergistic modification of metallurgical solid waste-based foamed microcrystalline glass, characterized in that, The fluoride and oxide synergistically modified metallurgical solid waste-based foam glass-ceramics is prepared by the preparation method of any one of claims 1-9, and has a bulk density of 0.45-1.15 g / cm 3 , a porosity of 45.2%-77.8%, a compressive strength of 1.8-6.8 MPa, and a crystallinity of 30.1%-48.5%.

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