Oil shale residue / fly ash glass-ceramics, and preparation method and application thereof

Abstract

The application relates to oil shale residue / coal ash glass-ceramics and a preparation method and application thereof, relates to the technical field of glass-ceramics, and solves the problems that the post-processing of the prior art OSA has serious environmental hazards, resource utilization is low, the crystal phase structure is unstable when the OSA is applied to the preparation of glass-ceramics, process controllability is poor, and high-quality, low-cost and sustainable utilization of the glass-ceramics cannot be simultaneously realized. The oil shale residue / coal ash glass-ceramics is composed of 80 parts of industrial waste residue, 4-6 parts of a crystal nucleus agent and 14-16 parts of auxiliary components; the industrial waste residue is composed of 50-75 parts of oil shale residue and 5-30 parts of coal ash; and the preparation method comprises the following steps: mixing the oil shale residue and the coal ash, adding the crystal nucleus agent and the auxiliary components, grinding, melting, heat preservation, pouring the melt into a mold, annealing, and obtaining base glass; and polishing and heat treating the base glass to obtain the glass-ceramics. The application can be applied to the fields of building decoration and electrical insulation materials.

Description

Technical Field

[0001] This invention relates to the field of glass-ceramic technology, specifically to a shale slag / fly ash glass-ceramic, its preparation method, and its application. Background Technology

[0002] Oil shale combustion or dry distillation produces a large amount of oil shale slag (OSA) as a byproduct. Its high alkalinity and the presence of heavy metals such as Cr, Cd, Zn, Pb, and Cu have significant impacts on the environment and ecosystems. Currently, my country's disposal of OSA still mainly relies on stockpiling and landfilling. These traditional treatment methods not only occupy a large amount of land resources, but the accumulation of these heavy metals in soil and water bodies can slow down the growth rate of plants and animals, reducing their survival rate and population size. Furthermore, their accumulation in animals and humans may cause various diseases such as leukemia, cancer, and pneumonia, posing a potential threat to public health. It can also lead to the diffusion of leachate and dust, causing secondary pollution to the surrounding soil, water bodies, and atmospheric environment. Therefore, the harmless treatment and resource utilization of OSA has become a critical issue that urgently needs to be addressed, and it is also an important research direction in the field of industrial solid waste management and environmental protection.

[0003] Microcrystalline glass is a composite material composed of crystalline and glassy phases, possessing excellent physical and mechanical properties, high acid and alkali resistance, high thermal stability, low water absorption, and the ability to significantly solidify heavy metals. It is widely used in building decoration, chemical materials, and electronic components. However, the traditional preparation of microcrystalline glass relies excessively on high-purity silicate, aluminate, and oxide raw materials, requiring multiple stages of heat treatment including melting, molding, annealing, and crystallization. The process is extremely sensitive to temperature and time control, resulting in long production cycles, high energy consumption, poor repeatability, and high costs. To overcome these shortcomings, some researchers have developed microcrystalline glass preparation methods using solid waste resources as the main raw material, such as those from Ceramics International (…). Ceramics International The journal published an article entitled "Preparation and characterization of glass-ceramics via co-sintering of coal fly ash and oilshale ash-derived amorphous slag". , 45(15), 20058–20065.) This study used organic binders as auxiliary agents to press fly ash (CFA) and oil shale ash-derived amorphous slag (OSAS) into shape and then sintered them at different temperatures. Although this method can promote the forming and crystallization of microcrystalline glass to a certain extent, since it does not undergo a complete melting process, the particle bonding inside the system mainly relies on solid-phase diffusion, resulting in a limited degree of densification. This leads to weak heavy metal curing ability, low hardness, and low acid and alkali resistance of the resulting microcrystalline glass, making it difficult to meet the requirements of structural or corrosion-resistant applications, showing its obvious deficiencies in physical properties and chemical stability. In addition, due to the complex composition and large fluctuations in impurities of OSA, residual organic matter, sulfides, and unburned carbon in OSA are prone to decomposition or oxidation reactions under high temperature conditions, releasing gases or forming volatile by-products, resulting in bubbles or foaming phenomena in the system, destroying the continuity and dense structure of the material, thereby reducing the mechanical strength and chemical stability of the product.

[0004] Therefore, even though OSA-based preparation of glass-ceramics can achieve solid waste resource utilization and has high added value, its preparation route still faces the problem of difficulty in simultaneously achieving high quality, low cost, and sustainable development of glass-ceramics. Summary of the Invention

[0005] To address the serious environmental hazards and low resource utilization rate of existing OSA post-processing techniques, as well as the instability of crystal phase structure and poor process controllability when applying OSA to the preparation of glass-ceramics, making it difficult to simultaneously achieve high quality, low cost, and sustainable utilization of glass-ceramics, this invention proposes an OSA / fly ash (CFA) glass-ceramic, its preparation method, and its application. The technical solution of this invention is as follows:

[0006] An OSA / CFA microcrystalline glass comprises the following components by mass fraction: 80 parts industrial waste residue, 4-6 parts nucleating agent, and 14-16 parts auxiliary components;

[0007] The industrial waste residue is composed of 50-75 parts OSA and 5-30 parts CFA.

[0008] Furthermore, the nucleating agent is TiO2, and the auxiliary component is CaO.

[0009] A method for preparing the above-mentioned OSA / CFA glass-ceramic includes the following preparation steps:

[0010] S1: Mix the pretreated OSA with CFA, add nucleating agent and auxiliary components, and grind to ensure that the particles of each material are fully fused and evenly distributed; melt the mixture, then put it into a high-temperature lifting furnace, keep it at a high temperature, pour the melt into a preheated mold, and anneal to eliminate internal stress to obtain the base glass;

[0011] S2: Polish the base glass to remove rust from the glass surface and eliminate its influence on glass crystallization; then perform heat treatment to obtain microcrystalline glass.

[0012] Furthermore, the pretreatment step described in S1 involves crushing, grinding, screening, and drying the industrial waste residue to complete the pretreatment of the industrial waste residue.

[0013] Furthermore, the grinding speed is 200 r / min, the grinding time is 40 min, the sieve mesh size is 200 mesh, and the drying time is 24 h.

[0014] Furthermore, the grinding time described in S1 is 30 min.

[0015] Furthermore, the melting temperature in S1 is 1500°C; the holding temperature is 1500°C; and the holding time is 2 hours.

[0016] Furthermore, the annealing temperature in S1 is 500°C; the annealing time is 2 hours.

[0017] Furthermore, the heat treatment described in S2 involves performing differential thermal analysis on the base glass, heating the base glass to the temperature corresponding to the exothermic peak in the differential thermal analysis results, holding it at that temperature for 2 hours, cooling it to 500°C at a rate of 2°C / min, and then allowing it to cool naturally to room temperature; the temperature corresponding to the exothermic peak is 900~950°C.

[0018] One application of the above-mentioned OSA / CFA microcrystalline glass is in the field of electrical insulation materials.

[0019] Furthermore, it is applied to the preparation of electrical insulators.

[0020] Compared with existing technologies, this invention solves the problems of serious environmental hazards and low resource utilization rate in the post-processing of OSA, as well as the unstable crystal phase structure and poor process controllability when OSA is applied to the preparation of glass-ceramics, making it difficult to simultaneously achieve high quality, low cost and sustainable utilization of glass-ceramics. The specific beneficial effects are as follows:

[0021] 1. High-Value-Added Microcrystalline Glass: This invention uses industrial waste oil shale slag and fly ash as raw materials to prepare microcrystalline glass. Through synergistic control of the raw material ratio of oil shale slag and fly ash and heat treatment conditions, a dense crystalline-glass phase composite structure is formed. This effectively achieves controllable adjustment of the microcrystalline phase type (diopside and anorthite), grain size, and distribution morphology of the microcrystalline glass, significantly improving the microstructure and interfacial bonding of the glass matrix. This dense crystalline framework structure effectively prevents the penetration and diffusion of corrosive media, significantly improving the acid and alkali corrosion resistance, chemical inertness, and environmental durability of the microcrystalline glass. In addition, this invention introduces TiO2 as a highly efficient nucleating agent and CaO as an auxiliary component to promote uniform nucleation and directional growth of the crystalline phase, improving the viscosity characteristics and phase separation behavior of the glass melt. The microcrystalline glass provided by this invention realizes the resource utilization of solid waste, endows glass products with high added value and extends service life, and has broad application potential in green building, functional decorative panels, and electrical insulation materials.

[0022] 2. Effectively Improves Heavy Metal Solidification and Environmental Safety: This invention, by controlling the crystal phase type of oil shale slag / fly pulverized coal microcrystalline glass, utilizes the large lattice constants and open structures of anorthite and diopside to achieve efficient solidification and long-term stable fixation of heavy metal elements through the synergistic effect of vitrification and crystallization. This allows heavy metal ions (such as Cr, Zn, Cu, Pb, etc.) to enter the crystal lattice through ion substitution or intercalation mechanisms to form stable solid solutions, thereby achieving chemical fixation. Simultaneously, the glassy phase provides an encapsulating environment, effectively inhibiting the outward migration of heavy metals and significantly reducing the leaching risk. The heavy metal leaching concentration is only 0.0148~2.8148 mg / L, demonstrating excellent environmental stability and realizing the resource utilization of industrial solid waste and the control of heavy metal pollution. Furthermore, the microcrystalline glass leachate has no significant inhibitory effect on wheat seed germination and growth, exhibiting extremely low ecotoxicity. The microcrystalline glass provided by this invention possesses excellent ecological compatibility and environmental safety.

[0023] 3. Low Cost and Sustainable Development: This invention, through scientifically optimized proportions and heat treatment processes, avoids dependence on high-purity silicate minerals or expensive fluxes, significantly reducing raw material costs and energy consumption. During the preparation process, the SiO2, Al2O3, CaO, and Fe2O3 components naturally present in the waste residue participate in the formation of the glass matrix and the induced crystallization of the crystalline phase, achieving efficient resource recycling and cascaded energy utilization, thus reducing industrial solid waste accumulation and secondary pollution problems at the source. Compared with traditional microcrystalline glass preparation processes, this invention's microcrystalline glass has advantages such as a simple process flow, low equipment investment, and the ability to achieve continuous and large-scale production; it realizes the high-value transformation of typical solid waste, providing a new sustainable development path for resource regeneration and environmental governance, fully embodying the core concepts of green manufacturing and the circular economy. Attached Figure Description

[0024] Figure 1 X-ray diffraction patterns and thermogravimetric-differential thermal analysis curves of OSA and CFA waste residues are shown; among them, Figure 1 (a) is the X-ray diffraction pattern of OSA; Figure 1 (b) shows the thermogravimetric-differential thermal analysis curves of OSA; Figure 1 (c) is the X-ray diffraction pattern of CFA; Figure 1 (d) is the thermogravimetric-differential thermal analysis curve of CFA;

[0025] Figure 2 Differential thermal analysis curves of the base glass;

[0026] Figure 3 The X-ray diffraction pattern of the base glass;

[0027] Figure 4 The X-ray diffraction pattern of the glass-ceramic;

[0028] Figure 5 The image shows a scanning electron microscope image of the glass-ceramic; in which, Figure 5 (a~f) are scanning electron microscope images of the microcrystalline glass prepared in Examples 1-6, respectively;

[0029] Figure 6 The Fourier transform infrared spectra of the base glass and glass-ceramics are shown; among them, Figure 6 (a) is the Fourier transform infrared spectrum of the base glass; Figure 6 (b) is the Fourier transform infrared spectrum of the glass-ceramic;

[0030] Figure 7 These are test charts for the density, water absorption, Vickers hardness, and corrosion resistance of basic glass and microcrystalline glass; among them, Figure 7 (a) Density test charts for the base glass and glass-ceramics; Figure 7 (b) is a water absorption test diagram for the base glass and glass-ceramics; Figure 7 (c) Vickers hardness test charts for the base glass and glass-ceramics; Figure 7 (d) is a graph showing the corrosion resistance test results of the base glass and glass-ceramic in NaOH solution; Figure 7 (e) is a graph showing the corrosion resistance of the base glass and glass-ceramic in HAc solution; Figure 7 (f) is a graph showing the corrosion resistance test results of the base glass and glass-ceramic in H2SO4 solution;

[0031] Figure 8 The energy dispersive X-ray spectrum of the glass-ceramic;

[0032] Figure 9 This is a diagram of the crystal cell structure of anorthite.

[0033] Figure 10 This is a diagram of the cell structure of diopside;

[0034] Figure 11 This is a structural diagram showing the substitutional positions of Zn and Cu in anorthite crystals; where, Figure 11 (a) is a structural diagram of the substitutional positions of Zn in anorthite crystals; Figure 11 (b) is a structural diagram of the substitutional positions of Cu in anorthite crystals;

[0035] Figure 12 This is a structural diagram showing the substitutional positions of Cr, Zn, and Cu in diopside; where, Figure 12 (a) is a structural diagram showing the substitutional positions of Cr, Zn, and Cu in diopside; Figure 12 (b) is a structural diagram showing the substitutional positions of Zn and Cu in diopside;

[0036] Figure 13 The germination of wheat seeds was observed in microcrystalline glass extract, OSA extract, and water, respectively.

[0037] Figure 14 The average root length and shoot length of wheat after 3 days of germination. Detailed Implementation

[0038] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0039] Example 1.

[0040] S1: Crush OSA and CFA, grind the waste residue in a ball mill at 200 r / min for 40 min, sieve the resulting powder through a 200 mesh sieve, and then dry it in an oven for 24 h to complete the pretreatment of OSA and CFA waste residue.

[0041] X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and thermogravimetric-differential thermal analysis (TG-DTA) were performed on the obtained OSA and CFA waste residues, respectively. Table 1 below shows the XRF test results of OSA and CFA waste residues. From the chemical composition in Table 1, it can be seen that OSA is mainly composed of SiO2, Al2O3, CaO, and Fe2O3, with lower contents of P2O5, TiO2, and K2O compounds. Conversely, CFA is rich in Al2O3, SiO2, and Fe2O3, with a total content of 90.32 wt%. Figure 1 The images show XRD and TG-DTA test patterns of OSA and CFA waste residues, where... Figure 1(a) shows the XRD pattern of OSA. It can be seen from the figure that the crystal phase of OSA is quartz (PDF#46-1045, SiO2). Figure 1 (b) shows the TG-DTA curve of OSA. It can be seen from the TG curve of OSA in the figure that OSA has a continuous mass loss as the temperature increases, and the mass loss reaches 12.1%. This is mainly due to the release of structural water and volatile substances and the decomposition of crystals. The DTA curve of OSA shows that there is a prominent exothermic peak in 25~600℃ and an endothermic peak near 700℃, which corresponds to the mass loss in the TG curve. Figure 1 (c) shows the XRD pattern of CFA. As can be seen from the figure, CFA contains crystalline quartz (PDF#46-1045, SiO2) and mullite (PDF#15-0776, Al6Si2O3). 13 ); Figure 1 (d) shows the TG-DTA curve of CFA. The TG curve shows that the mass loss rate of CFA is about 3.4%, which proves that the components in CFA decompose less. In the range of 500~700℃, the weight loss of CFA shows a decreasing trend, mainly due to the release of structural water and volatile substances.

[0042] Table 1

[0043]

[0044] S2: Pretreated OSA and CFA are thoroughly mixed at a mass ratio of 50:30. Nucleating agent TiO2 and auxiliary component CaO are added, with a mass ratio of CFA to TiO2 and CaO of 6:1:3. The mixture is ground in a mortar for 30 minutes to ensure thorough fusion and uniform distribution of the materials. The mixture is placed in a crucible and transferred to a resistance furnace for melting at 1500℃ and held for 2 hours. The melt is poured into a preheated mold and quickly placed in a muffle furnace for annealing at 500℃ for 2 hours to eliminate internal stress. After cooling to room temperature in the muffle furnace, base glass 1 (PG-1) is obtained. PG-1 is coarsely polished using an MP-1B metallographic polishing machine to remove rust from the glass surface and eliminate its influence on glass crystallization.

[0045] S3: Perform heat treatment on PG-1, see reference... Figure 2 The DTA test curve of PG is shown. PG-1 was heated to the temperature corresponding to the exothermic peak of PG-1 in the DTA curve, 921℃, and held for 2 h. It was then cooled to 500℃ at a rate of 2℃ / min and then allowed to cool naturally to room temperature to obtain microcrystalline glass 1 (GC-1).

[0046] Example 2.

[0047] The difference between this embodiment and Example 1 is that in S2, the pretreated OSA and CFA are fully mixed at a mass ratio of 55:25, and the mass ratio of CFA to TiO2 and CaO is 5:1:3; in S3, the heat treatment temperature is 915℃; the remaining preparation steps and conditions are the same as in Example 1, and PG-2 and GC-2 are obtained.

[0048] Example 3.

[0049] The difference between this embodiment and Example 1 is that in S2, the pretreated OSA and CFA are fully mixed at a mass ratio of 60:20, and the mass ratio of CFA to TiO2 and CaO is 4:1:3; in S3, the heat treatment temperature is 917℃; the remaining preparation steps and conditions are the same as in Example 1, and PG-3 and GC-3 are obtained.

[0050] Example 4.

[0051] The difference between this embodiment and Example 1 is that in S2, the pretreated OSA and CFA are fully mixed at a mass ratio of 65:15, and the mass ratio of CFA to TiO2 and CaO is 3:1:3; in S3, the heat treatment temperature is 908℃; the remaining preparation steps and conditions are the same as in Example 1, and PG-4 and GC-4 are obtained.

[0052] Example 5.

[0053] The difference between this embodiment and Example 1 is that in S2, the pretreated OSA and CFA are fully mixed at a mass ratio of 70:10, and the mass ratio of CFA to TiO2 and CaO is 2:1:3; in S3, the heat treatment temperature is 932℃; the remaining preparation steps and conditions are the same as in Example 1, and PG-5 and GC-5 are obtained.

[0054] Example 6.

[0055] The difference between this embodiment and Example 1 is that in S2, the pretreated OSA and CFA are fully mixed at a mass ratio of 75:5, and the mass ratio of CFA to TiO2 and CaO is 1:1:3; in S3, the heat treatment temperature is 929℃; the remaining preparation steps and conditions are the same as in Example 1, and PG-6 and GC-6 are obtained.

[0056] like Figure 3 The XRD patterns of the base glasses PG-1~6 show that the base glass samples prepared by OSA and CFA with different mass ratios all exhibit obvious peaks. This indicates that both OSA and CFA are transformed into amorphous phases, and no obvious crystalline phase diffraction peaks were detected in the system, indicating that the obtained samples have typical glass structures. This shows that it is feasible to prepare homogeneous and stable glass matrices using OSA and CFA as the main raw materials, and that it has good glass-forming properties.

[0057] like Figure 4 The XRD patterns of glass-ceramics GC-1~6 are shown. As can be seen from the figures, the crystal phase of GC-1, GC-5, and GC-6 is diopside (CaMgSi2O6, PDF#75-1092); while the crystal phases of GC-2, GC-3, and GC-4 are anorthite (CaAl2Si2O8, PDF#41-1486) and diopside (CaMgSi2O6, PDF#75-1092). The formation of these different crystal phases in the glass-ceramics is due to O 2- and Si 4+ Combined to form [SiO4] tetrahedra, when Al in [SiO4] 3+ Replace Si 4+ When [SiO4] is present, it will carry a negative charge, and this negative charge will be converted by Ca. 2+ When positive charges are neutralized, [AlO4]Ca[AlO4] is formed. [SiO4] and [AlO4]Ca[AlO4] constitute the structural unit of the glass. During crystallization, [AlO4]Ca[AlO4] rearranges and combines with [SiO4] to form anorthite. Therefore, the main crystalline phase of the glass-ceramic changes from a single CaMgSi2O6 to a polycrystalline coexistence system of CaAl2Si2O8 and CaMgSi2O6.

[0058] like Figure 5 (a) to (f) are scanning electron microscope (SEM) images of microcrystalline glass GC-1 to GC-6, respectively. Figure (a) shows that the surface of GC-1 prepared in Example 1 contains a large number of fine granular crystalline phases. Figure 4 The XRD pattern of the sample shows that the spherical crystal phase is diopside; Figure (b) shows GC-2 prepared in Example 2, which exhibits a dense dendritic and spherical coexisting structure, indicating that the sample simultaneously precipitated anorthite and diopside crystal phases; Figure (c) shows GC-3 prepared in Example 3. With the increase of OSA content and the decrease of crystallization temperature, the amount of anorthite crystal phase decreased significantly, while the amount of diopside crystal phase gradually increased. This is mainly attributed to the fact that higher sintering temperatures are conducive to the diffusion of Ca and Mg elements and the nucleation of diopside, but not conducive to the stable formation of anorthite crystal phase; Figure (d) shows GC-4 prepared in Example 4, which exhibits a morphology of regular spherical and short rod-shaped crystals coexisting, and... Figure 4 The samples show consistent anorthite and diopside crystal phases; Figure (e) shows GC-5 prepared in Example 5, which exhibits a large number of fine diopside crystals with near-spherical particles, indicating that at this OSA / CFA ratio, the proportions of Ca, Si, and Mg in the system are coordinated, which helps to promote the orderly crystallization and grain growth of diopside; Figure (f) shows GC-6 prepared in Example 6, which exhibits a tightly packed diopside crystal network structure. Figure 4 and Figure 5The data results show that the mass ratio of OSA to CFA not only directly affects the chemical composition and structural homogeneity of the glass system, but also influences the nucleation rate and grain growth behavior by changing the melt viscosity and crystallization driving force. A higher OSA ratio and a moderate heat treatment temperature (920~940℃) help form fine, dense, and uniformly distributed diopside crystal phases, while a higher CFA ratio or a lower temperature (900~920℃) may lead to the mixed precipitation of anorthite or composite crystal phases, reducing the homogeneity and density of the crystal phases. Therefore, this invention effectively achieves controllable adjustment of crystal phase type, size, and distribution by regulating the raw material ratio and heat treatment process parameters, thus providing an important process basis for preparing solid waste-based microcrystalline glass with excellent mechanical properties and chemical stability.

[0059] like Figure 6 Figure 1 shows the Fourier transform infrared (FT-IR) spectra of the base glass PG-1~6 and the microcrystalline glass GC-1~6. Figure 2 shows the FT-IR spectra of PG-1~6. As can be seen from the figure, all PG samples exhibit six distinct absorption bands, with the largest at 457 cm⁻¹. -1 The absorption peaks observed at 600-750 cm⁻¹ are attributed to the bending vibrations of Si-O-Si or O-Si-O within the tetrahedral [SiO₄] structural units. -1 and 800-1200 cm -1 The strong absorption bands appearing in the range are mainly attributed to the stretching vibrations of the Si-O-Si(Al) bonds, in the range of 600-750 cm⁻¹. -1 Within the spectral band range, there are Si-O-Al symmetric stretching vibrations. The presence of this type of bond helps enhance the structural stability of the glass matrix and affects its crystallization behavior; while in the 800-1200 cm⁻¹ range... -1 The broad and strong absorption band observed in the region originates from the asymmetric stretching vibrations of the Si–O–Si bonds of varying numbers of bridging oxygen atoms in the [SiO4] structure. Located at 1645 cm⁻¹ -1 The absorption peak at 3443 cm⁻¹ is attributed to the HOH bending vibration caused by water molecules. -1 The absorption band at 548 cm⁻¹ is attributed to the O–H stretching vibration of water molecules or hydroxyl groups (–OH), which is the most significant high-wavenumber absorption peak in the glass system, indicating the presence of hydroxyl functional groups or physically adsorbed water on the sample surface and inside. Figure (b) shows the FT-IR spectra of GC-1~6 prepared in Examples 1-6, with the peak at 548 cm⁻¹. -1 and 766 cm -1 A new absorption band was detected nearby at 548 cm⁻¹. -1 The spectral band at 766 cm⁻¹ is caused by the [AlO₄] tetrahedral vibration. -1The spectral band at that location may be attributed to the bending vibrations of Si-O. In summary, this invention, through the synergistic control of the OSA / CFA ratio and heat treatment conditions, can effectively regulate the silicon-oxygen network structure while maintaining the stability of the glass matrix structure. This enables controllable adjustment of the crystal phase type, grain size, and distribution morphology, providing an important structural basis and theoretical support for obtaining microcrystalline glass materials with dense structure, full crystallization, and excellent performance.

[0060] (a) Physicochemical performance testing:

[0061] The density, water absorption, Vickers hardness, and acidity / alkalinity of the base glasses PG-1~6 and microcrystalline glasses GC-1~6 prepared in Examples 1-6 were tested. Figure 7 (a) shows the density test results of PG-1~6 and GC-1~6. As can be seen from the figure, the density of the PG sample is between 2.739 and 2.759 g / cm³. 3 Within the range, for GC samples, as the OSA content increases, the density of the GC sample decreases from 2.768 g / cm³. 3 Increased to 2.932 g / cm³ 3 This indicates that the densification of the system is significantly enhanced compared to the base glass. This trend is mainly attributed to the increased SiO2 and Al2O3 content in the system with the increase of OSA doping, which promotes the formation and growth of crystalline phases such as diopside, causing the amorphous phase inside the sample to be gradually replaced by the crystalline phase. The precipitation of the crystalline phase not only fills the micropores and defects in the glass matrix, but also promotes a more regular atomic arrangement, thereby improving the overall density and structural uniformity of the material. Figure 7 (b) shows the water absorption test results for PG-1~6 and GC-1~6. As can be seen from the figure, the water absorption rate of the GC sample is in the range of 0.006%~0.034%, significantly lower than that of the corresponding PG sample. This is because the PG sample, due to its amorphous structure, contains many micropores and free volume, making it prone to water adsorption; while the precipitation of diopside and anorthite crystal phases in the GC sample fills the pores, making the structure more compact and difficult for water to penetrate. This indicates that the GC sample provided by this invention has excellent water resistance, extending the service life of GC materials and laying the foundation for its application in the field of electrical insulators. Figure 7 (c) shows the Vickers hardness test results for PG-1~6 and GC-1~6. The results indicate that the Vickers hardness of the GC sample is generally higher than that of the PG sample. Furthermore, with the increase of OSA content, the Vickers hardness of the PG sample increases from 652 HV to 805 HV. This is mainly due to the higher SiO2 content in OSA, which increases the proportion of [SiO4] tetrahedra, thereby enhancing the stability of the glass network structure. This demonstrates that crystallization treatment further improves the mechanical strength of the material. The precipitated diopside and anorthite crystal phases have high hardness and can significantly enhance the compressive and deformation resistance of the matrix. Figure 7 (df) are the corrosion resistance test graphs for PG and GC samples in strong alkaline solution (NaOH), weak acid solution (HAc), and strong acid (H2SO4), respectively. Figure 7 As shown in (d), the GC sample exhibits an alkali resistance greater than 99.92%, demonstrating excellent alkali resistance; Figure 7 As shown in (e) and (f), GC also exhibits excellent acid resistance, reaching 99.14%. The acid and alkali corrosion resistance of the GC sample is significantly higher than that of the PG sample. This is because the diopside and other crystalline phases precipitated after crystallization treatment form a continuous and dense grain structure, effectively hindering the penetration and diffusion of corrosive media, thereby significantly improving the chemical inertness and surface stability of the material. The test results show that the acid and alkali resistance of the prepared OSA / CFA-based microcrystalline glass meets the requirements of the Chinese industry standard "JC / T 2097-2011 Industrial Microcrystalline Sheets", possessing excellent environmental stability and durability, and has the potential for widespread application in fields such as building decoration.

[0062] (II) Heavy metal curing performance test:

[0063] The heavy metal curing mechanism of the microcrystalline glass GC-6 prepared in Example 6 was analyzed, such as... Figure 8 The energy-dispersive X-ray spectroscopy (EDS) spectrum of GC-6 is shown. The spectrum reveals a high concentration of heavy metals, including Fe, Cu, Zn, Pb, Cr, and As, in both the glass and crystalline phases of GC-6. Heavy metal leaching experiments were conducted on GC-6, and Table 2 shows the leaching concentrations of heavy metals in GC-6. The table indicates that the leaching concentrations of Fe, Cu, Zn, Pb, Cr, and As range from 0.0148 to 2.8148 mg / L, indicating a low risk of heavy metal leaching. This concentration range is far below the limits set by the "Identification Standard for Hazardous Waste" (GB 5085.3-2007), fully complying with environmental standards. This demonstrates that OSA / CFA-based microcrystalline glass exhibits excellent solidification and long-term stabilization effects on heavy metals. This heavy metal solidification effect stems from the fact that the main crystalline phases of OSA / CFA-based microcrystalline glass are anorthite and diopside, both of which possess large lattice constants and relatively open crystal structures. When heavy metal ions enter the crystal lattice as impurity atoms, they can replace matrix cations such as Ca and Mg to form a stable solid solution structure, thereby achieving lattice fixation of the heavy metals. The adsorption and intercalation of heavy metals by the crystal phase makes them less likely to migrate to the glass phase interface or the external environment, significantly reducing the risk of leaching.

[0064] like Figure 9The diagram shows the crystal structure of anorthite. It reveals that anorthite is composed of [SiO4], [AlO4], and irregular [CaO6]. The aluminum-oxygen tetrahedra are connected by oxygen and silicon-oxygen tetrahedra at shared vertices, with a silicon-to-aluminum ratio of 1:1. When the SiO2 content in the crystal is high, this ratio is slightly greater than 1, increasing the lattice porosity and facilitating the incorporation of foreign ions. Figure 10 The diagram shows the unit cell structure of diopside. Diopside is composed of [SiO4] tetrahedra, regular [MgO6] octahedra, and irregular [CaO6] octahedra. The silicon-oxygen tetrahedra and Mg octahedra share edges and connect to form a stable chain structure. Both types of crystal structures can accommodate metal ions of different valence states through ion substitution mechanisms. During the sintering of glass-ceramics, heavy metal elements enter the crystal lattice as impurity atoms. These impurity atoms integrate into the crystal and replace the matrix cation sites. The ease of this substitution is related to the percentage difference (Dr) of the reciprocal of the ionic radius. When the (Dr) value is less than 30%, substitution can be achieved, and the smaller the radius percentage difference, the easier the substitution process. Solid solutions are formed during the sintering of glass-ceramics, with heavy metals entering the crystal lattice as impurity atoms. The formula for the radius difference (Dr) value is shown in Equation I below:

[0065] (Formula I);

[0066] Where Rm(CN) represents the radius of the ion in the matrix, and Rd(CN) represents the radius of the impurity atom. Based on the radii of heavy metal ions in the glass-ceramic, the Dr values ​​of Cr-Ca, Zn-Ca, Cu-Ca, Cr-Al, Zn-Al, Cu-Al, Cr-Mg, Zn-Mg, and Cu-Mg were calculated to be 36%, 25%, 26%, 98%, 48%, 46%, 3%, 14%, and 12%, respectively. This indicates that Ca ions can be replaced by Zn and Cu, while Mg ions can be effectively replaced by Cr, Zn, and Cu. Equations II and III below represent the impurity defect reactions of Zn and Cu in anorthite, where LM represents the L solute at the M position, such as PbCa representing Pb. 2+ Solute in Ca 2+ Position; "·" indicates effective positive charge; V X This indicates that an empty space is created at position X. For example... Figure 11 This is a structural diagram showing the substitutional positions of Zn and Cu in anorthite crystals. Since the Dr values ​​of Zn and Ca ions are smaller than those of Cu and Ca ions... Dr Value, therefore Zn 2+ Preferentially replaces Ca in anorthite 2+ Moreover, both ions carry a positive divalent charge, thus ensuring that there are no additional unpaired electrons.

[0067] (Formula II);

[0068] (Formula III);

[0069] Formulas IV, V, and VI below represent the impurity reactions of Cr, Zn, and Cu in diopside, respectively; "," indicates an effective negative charge; For example Figure 12 This is a structural diagram showing the substitutional positions of Cr, Zn, and Cu in diopside. Since Cr-Mg has the smallest Dr value, Cr... 3+ Preferentially replaces Mg in diopside 2+ During the substitution process, unequal charges create charge vacancies. Cu and Zn can substitute for Mg. 2+ and Zn 2+ With Mg 2+ Since the charges are equal, no charge vacancies will be created. Finally, according to Dr, Zn 2+ and Cu 2+ Can replace Ca 2 + No charge vacancies are generated during this process.

[0070] (Formula IV);

[0071] (Form V);

[0072] (Form VI).

[0073] In summary, the microcrystalline glass provided by this invention achieves deep solidification of heavy metals through a combination of vitrification and crystallization. The glassy phase provides an encapsulating environment, while the crystalline phase achieves chemical fixation through ion substitution and solid solution mechanisms. The synergistic effect of these two phases enables the material to maintain a low heavy metal leaching rate even under strong acid and alkali environments, further enhancing the corrosion resistance and environmental stability of the microcrystalline glass. This solidification mechanism effectively ensures the environmental safety of the material.

[0074] Table 2

[0075]

[0076] (III) Ecotoxicity assessment:

[0077] Wheat seed germination experiments were conducted using OSA / CFA-based microcrystalline glass leachate, such as... Figure 13 The images show wheat seeds after germination for 3 days in glass-ceramic leachate, OSA leachate, and water. As can be seen from the images, seeds in the OSA leachate showed almost no germination, indicating that OSA without any pretreatment is ecotoxic. However, the germination and growth of wheat seeds in the glass-ceramic leachate showed no significant difference compared to the control group (deionized water). Figure 14The figures show the average root and shoot lengths of wheat after 3 days of germination. As can be seen from the figures, compared to deionized water, the microcrystalline glass leachate did not show a significant inhibitory effect on seed germination, indicating that the leachate of the microcrystalline glass provided by this invention has no obvious toxicity to plant growth, and the material possesses high environmental compatibility and ecological safety. Even wheat grown in GC-1, GC-3, GC-4, GC-5, and GC-6 leachates had longer root lengths than those grown in deionized water. This may be because trace metals (Cu and Ni) in the microcrystalline glass promoted seed germination and growth. This demonstrates that the OSA / CFA-based microcrystalline glass provided by this invention has excellent environmental safety and ecological compatibility, proving that this material, while realizing the resource utilization of industrial solid waste, also possesses the potential functional benefits of promoting plant growth, thus providing new technical ideas and scientific basis for the development of green building materials and ecological environment restoration.

[0078] In summary, this invention prepares microcrystalline glass using industrial waste oil shale slag and fly ash as raw materials. Through the synergistic control of the raw material ratio of oil shale slag and fly ash and the heat treatment conditions, the crystal phase of the microcrystalline glass is diopside and anorthite, achieving efficient solidification of heavy metal elements and control of heavy metal pollution, exhibiting excellent ecological compatibility and environmental safety. This invention avoids dependence on high-purity silicate minerals or expensive fluxes, significantly reducing raw material costs and energy consumption, reducing industrial solid waste accumulation and secondary pollution problems at the source, realizing the high-value transformation of typical solid waste, providing a new sustainable development path for resource regeneration and environmental governance, and fully embodying the core concepts of green manufacturing and circular economy.

[0079] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0080] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A type of oil shale slag / fly ash microcrystalline glass, characterized in that, By mass fraction, it includes the following components: 80 parts industrial waste residue, 4-6 parts nucleating agent, and 14-16 parts auxiliary components; The industrial waste residue is composed of 50-75 parts oil shale slag and 5-30 parts fly ash; the auxiliary component is CaO. The preparation method of the oil shale slag / fly ash microcrystalline glass includes the following preparation steps: S1: Mix the pretreated oil shale slag with fly ash, add nucleating agent and auxiliary components, grind, melt the mixture, keep it warm, pour the melt into a preheated mold, anneal, and obtain the base glass; S2: Polish the base glass and heat treat it to obtain microcrystalline glass; The heat treatment described in S2 involves performing differential thermal analysis on the base glass, heating the base glass to the temperature corresponding to the exothermic peak in the differential thermal analysis results, holding it at that temperature for 2 hours, cooling it to 500°C at a rate of 2°C / min, and then allowing it to cool naturally to room temperature; the temperature corresponding to the exothermic peak is 900~950°C.

2. The oil shale slag / fly ash microcrystalline glass according to claim 1, characterized in that, The nucleating agent is TiO2.

3. The oil shale slag / fly ash microcrystalline glass according to claim 1, characterized in that, The pretreatment step described in S1 involves crushing the industrial waste residue. Grind, sieve, and dry.

4. The oil shale slag / fly ash microcrystalline glass according to claim 3, characterized in that, The grinding speed is 200 r / min, the grinding time is 30~40 min; the sieve mesh size is 200 mesh, and the drying time is 24 h.

5. The oil shale slag / fly ash microcrystalline glass according to claim 1, characterized in that, The grinding time described in S1 is 30-40 min.

6. The oil shale slag / fly ash microcrystalline glass according to claim 1, characterized in that, The melting temperature in S1 is 1500℃; the holding time is 2 h; the preheating temperature is 500℃; the annealing temperature is 500℃; and the annealing time is 2 h.

7. An application of oil shale slag / fly ash microcrystalline glass as described in any one of claims 1-6, characterized in that, It is used in the fields of building decoration and electrical insulation materials.

8. The application of the oil shale slag / fly ash microcrystalline glass according to claim 7, characterized in that, It is used in the preparation of electrical insulators.

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