Fluorosilicate glass-ceramics, method of preparation and use

Abstract

The application discloses fluorosilicate glass, a preparation method and application thereof, and directly uses fluorine-containing sludge and lithium tailings as raw materials, and the mass ratio of the fluorine-containing sludge and the lithium tailings is 3:7-7:3; the mixed materials are high-temperature melted at 1500-1550 DEG C for 1-1.5 h, and after casting forming, annealing is carried out at 600-650 DEG C, so that the base microcrystalline glass is obtained; then, heat treatment is carried out at 10K / min to 950-1050 DEG C for 1-2 h, so that complex crystal phases of albite and calcium fluoride are precipitated. The application realizes glass solidification of the fluorine-containing sludge, and fluorine ions are solidified in CaF2 and a glass network; the obtained microcrystalline glass has a Vickers hardness of 6.3-6.7 GPa, meets the requirements of building and decoration materials, and can be widely used in floor tiles, wall decoration plates and the like. The method simultaneously disposes of two kinds of solid wastes, realizes'material preparation from waste', and has the advantages of environmental friendliness and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to a fluorosilicate microcrystalline glass prepared using fluorine-containing sludge and lithium tailings, a preparation method thereof, and the application of fluorosilicate microcrystalline glass in building decoration materials. Background Technology

[0002] Fluorine-containing sludge mainly originates from enterprises using hydrofluoric acid for chemical etching or thinning, such as those in the semiconductor, photovoltaic, specialty glass, and fluorochemical industries. Fluorine-containing wastewater is neutralized with quicklime, resulting in a large amount of fluorine-containing sludge, with a CaF2 content reaching 35%-60%. The main methods for disposing of fluorine-containing sludge are landfilling, stockpiling, or simple solidification, which not only occupy large amounts of land but also pose a risk of secondary pollution, and lack effective resource utilization pathways.

[0003] Lithium tailings are a byproduct of the spodumene flotation process, with annual emissions in my country reaching millions of tons. Their main components are feldspar and quartz, and they are rich in silicates such as SiO2 and Al2O3. Currently, lithium tailings are primarily used in cementitious materials or concrete admixtures, a limited utilization method that makes it difficult to absorb the enormous output.

[0004] Vitrification is a high-temperature solid waste treatment technology that involves rapidly cooling high-temperature melting to form a stable glassy substance. It offers advantages such as good solidification, high sludge utilization, and significant volume reduction. Microcrystalline glass, a composite material composed of a microcrystalline phase and a glassy phase, combines the excellent properties of both glass and ceramics. Microcrystalline glass containing the feldspar ((Ca,Na)(Al,Si)2Si2O8) crystalline phase exhibits high hardness and chemical stability, making it suitable for building decoration materials. The CaF2 abundant in fluorinated sludge can serve as a calcium source and nucleating agent, while lithium tailings provide abundant SiO2 and Al2O3 as aluminosilicate framework components. The two are chemically complementary, significantly reducing raw material costs.

[0005] Based on this, the present invention proposes to use fluorine-containing sludge and lithium tailings to synergistically prepare fluorosilicate microcrystalline glass, which is suitable for building decoration materials, so as to achieve improved mechanical properties and high-value utilization of solid waste. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing fluorosilicate microcrystalline glass using fluorine-containing sludge and lithium tailings, along with its application. The two solid wastes are processed through high-temperature melting and heat treatment to obtain fluorosilicate microcrystalline glass with plagioclase and calcium fluoride as composite crystalline phases. This process achieves glass solidification of fluorine-containing sludge, resulting in a glass with high hardness, suitable for the building decoration field, and realizing the high-value utilization of solid waste.

[0007] This invention discloses a fluorosilicate microcrystalline glass. The raw materials required for preparing the fluorosilicate microcrystalline glass consist only of fluorine-containing sludge and lithium tailings, and the mass ratio of fluorine-containing sludge to lithium tailings is 3:7 to 7:3.

[0008] As a further improvement of the present invention, the fluoride-containing sludge is sludge generated from the treatment of etching process wastewater in industries such as semiconductors and photovoltaics, and its main chemical composition includes: SiO2 10-12 wt%, Al2O3 4-5 wt%, CaO 50-55 wt%, F ions 22-25 wt%, and the remaining components 3-14 wt%.

[0009] As a further improvement of the present invention, the lithium tailings are tailings produced after lithium extraction from spodumene, and their main chemical composition includes: SiO2 75-79 wt%, Al2O3 12-14 wt%, Na2O 5-7 wt%, and the remaining components 4-8 wt%.

[0010] As a further improvement of the present invention, the mass ratio of the fluorine-containing sludge to the lithium tailings is 3:7 to 5:5.

[0011] As a further improvement of the present invention, the crystal phase of the fluorosilicate microcrystalline glass is a composite crystal phase of bainite ((Ca,Na)(Al,Si)2Si2O8) and calcium fluoride (CaF2).

[0012] This invention also discloses a method for preparing the above-mentioned fluorosilicate microcrystalline glass, comprising: Step 1: Dry the fluoride-containing sludge and lithium tailings; Step 2: Mix the fluoride-containing sludge and lithium tailings according to the preset mass ratio; Step 3: Place the well-mixed batch material into a covered corundum crucible and melt it at 1500-1550℃ for 1-1.5 hours to obtain molten glass; Step 4: Cast the molten glass into shape and transfer it to a muffle furnace at 600-650°C for annealing to obtain the basic microcrystalline glass material; Step 5: Heat the basic microcrystalline glass material to 950-1050℃ and keep it at that temperature for 1-2 hours, then cool it to room temperature to obtain a high-hardness microcrystalline glass material with bainite and calcium fluoride as the composite crystal phase.

[0013] As a further improvement of the present invention, in step 1, the drying process is to dry at 100~120°C for 20~30 hours, preferably at 105°C for 24 hours.

[0014] As a further improvement of the present invention, in step 4, the annealing time is 5 to 7 hours, preferably 6 hours.

[0015] As a further improvement of the present invention, in step 5, the temperature is increased to 950-1050°C at a heating rate of 8-12 K / min, preferably at a heating rate of 10 K / min.

[0016] This invention also discloses the application of fluorosilicate microcrystalline glass in building decoration materials.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention can simultaneously dispose of fluorine-containing sludge generated by industries such as semiconductors and photovoltaics, as well as lithium tailings generated by lithium mining, significantly reducing environmental risks and realizing "material production from waste".

[0018] 2. This invention achieves glass solidification of fluorine-containing sludge, where fluorine can be stably solidified in CaF2 and a glass network structure.

[0019] 3. This invention, through controlled heat treatment processes, can obtain a composite crystalline glass of bainite and CaF2. The resulting glass of crystalline glass has a Vickers hardness of 6.3-6.7 GPa, which meets the standard requirements for building decoration materials. Attached Figure Description

[0020] Figure 1 The XRD diffraction patterns of the samples obtained in Example 4 of this invention after heat treatment at different temperatures; Figure 2 The XRD patterns of the samples obtained in Examples 1-5 of this invention are shown below, before and after heat treatment at 1050℃ for 1 hour. Figure 3 The Vickers hardness diagrams are of the samples obtained in Examples 1-5 of this invention, before and after heat treatment at 1050°C for 1 hour. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings: This invention provides a fluorosilicate microcrystalline glass. The raw materials required for preparing the fluorosilicate microcrystalline glass consist only of fluorinated sludge and lithium tailings, with a mass ratio of fluorinated sludge to lithium tailings of 3:7 to 7:3, preferably 3:7 to 5:5. The fluoride-containing sludge is sludge generated from the treatment of etching process wastewater in industries such as semiconductors and photovoltaics. Its main chemical composition includes: SiO2 10-12 wt%, Al2O3 4-5 wt%, CaO 50-55 wt%, F ions 22-25 wt%, and other components 3-14 wt%. The lithium tailings are tailings generated after lithium extraction from spodumene. Its main chemical composition includes: SiO2 75-79 wt%, Al2O3 12-14 wt%, Na2O 5-7 wt%, and other components 4-8 wt%.

[0023] The crystalline phase of the prepared fluorosilicate glass-ceramic is a composite crystalline phase of bainite ((Ca,Na)(Al,Si)2Si2O8) and calcium fluoride (CaF2).

[0024] This invention provides a method for preparing the above-mentioned fluorosilicate microcrystalline glass, comprising: Step 1: Dry the fluorine-containing sludge and lithium tailings at 105℃ for 24 hours.

[0025] Step 2: Prepare the fluorine-containing sludge and lithium tailings according to the preset mass ratio. Place the weighed raw materials in a mixing bottle and mix for 10-12 hours to obtain a uniform batch. Step 3: Place the well-mixed batch material into a covered corundum crucible and melt it at 1500-1550℃ for 1-1.5 hours to obtain molten glass; Step 4: Cast the molten glass into shape and quickly transfer it to a muffle furnace at 600-650°C for annealing for 6 hours. Cool it to room temperature with the furnace to obtain the basic microcrystalline glass material. Step 5: Heat the base glass-ceramic to 950-1050℃ at a heating rate of 10K / min and hold for 1-2 hours. Then cool it to room temperature in the furnace to obtain a high-hardness glass-ceramic material with bainite and calcium fluoride as the composite crystal phase.

[0026] The advantages of this invention are: By co-melting fluorine-containing sludge and lithium tailings at high temperature, the fluorine-containing sludge was vitrified, and the fluorine element was stably solidified in the CaF2 crystal and glass network structure. Through subsequent heat treatment, the bainite phase was induced to precipitate in situ and form a composite crystalline phase with the residual CaF2. The resulting microcrystalline glass has a Vickers hardness of 6.3-6.7 GPa, which can meet the standard requirements of building decoration materials and realize the high-value utilization of solid waste.

[0027] Table 1 below shows the raw material ratios for fluorosilicate microcrystalline glass in five specific embodiments.

[0028]

[0029] The preparation methods for Examples 1-5 are as follows: S1. Pre-treat the fluorine-containing sludge and lithium tailings, and dry them at 105℃ for 24h. Accurately convert the mass fraction of the glass composition in Examples 1-5 in Table 1 into the mass of the corresponding raw materials, accurately weigh the mass of the corresponding raw materials of each composition, place them in a mixing bottle, and mix for 12h to obtain a uniform batch. S2. Place the uniformly mixed batch material in a covered corundum crucible and melt it at 1500℃ for 1.5h; cast the glass liquid into shape and quickly transfer it to a muffle furnace at 650℃ for annealing for 6h, and cool it to room temperature with the furnace to obtain the basic microcrystalline glass material. S3. The obtained basic glass-ceramic is placed in a muffle furnace and heated to 950-1050℃ at a heating rate of 10K / min and heat-treated for 1 hour. Then it is cooled down with the furnace. The high-hardness glass-ceramic material with a composite crystalline phase of bainite and calcium fluoride is obtained.

[0030] The XRD diffraction patterns of the samples obtained in Example 4 after heat treatment at different temperatures are shown below. Figure 1 As shown. The main crystalline phase of the untreated sample is CaF2; after heat treatment at 850℃, the main crystalline phase of the sample is still CaF2; when the heat treatment temperature is raised to 950℃, diffraction peaks of the bainite phase begin to appear in the sample, while the diffraction peaks of the CaF2 phase still exist; after further heating to 1050℃, the intensity of the diffraction peaks of the bainite phase is significantly enhanced, and finally a composite crystalline phase of bainite and CaF2 is formed.

[0031] The XRD patterns of the samples prepared in Examples 1-5 are as follows: (The XRD patterns are not shown in the original text.) Figure 2 As shown, the main crystalline phase of all untreated samples was CaF2; after heat treatment at 1050℃, a composite crystalline phase of bainite and CaF2 was formed. When the mass ratio of fluorine-containing sludge to lithium tailings was greater than 5:5, the diffraction peak intensity of the bainite phase decreased, while that of the CaF2 phase increased relatively. Therefore, the optimal mass ratio of fluorine-containing sludge to lithium tailings is 3:7 to 5:5.

[0032] Vickers hardness diagrams of the samples obtained in Examples 1-5 after no heat treatment and after heat treatment at 1050℃ for 1 hour are shown below. Figure 3 As shown, when the mass ratio of fluorinated sludge to lithium tailings is 3:7 to 6:4, the Vickers hardness of the heat-treated samples is significantly higher than that of the untreated samples, with the highest Vickers hardness reaching 6.7 GPa. This is due to the formation of a composite crystalline phase of bainite and CaF2, which enhances the sample hardness. However, with a further increase in the proportion of fluorinated sludge, the Vickers hardness gradually decreases. This is because the relative content of lithium tailings decreases, resulting in insufficient glass network agglomerates, while the increase in fluorine content disrupts the silicate network structure.

[0033] This invention also proposes an application of fluorosilicate microcrystalline glass prepared from fluorine-containing sludge and lithium tailings, as disclosed in any of the above embodiments, in building decoration materials. The fluorosilicate microcrystalline glass prepared by this invention has high Vickers hardness and can achieve "waste-to-material" processing while disposing of fluorine-containing sludge and lithium tailings, making it suitable for building decoration materials.

[0034] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A fluorosilicate microcrystalline glass, characterized in that, The raw materials required for preparing fluorosilicate microcrystalline glass consist only of fluorine-containing sludge and lithium tailings, and the mass ratio of fluorine-containing sludge to lithium tailings is 3:7 to 7:

3.

2. The fluorosilicate microcrystalline glass as described in claim 1, characterized in that, The main chemical composition of the fluoride-containing sludge includes: SiO2 10-12 wt%, Al2O3 4-5 wt%, CaO 50-55 wt%, F ions 22-25 wt%, and the remaining components 3-14 wt%.

3. The fluorosilicate microcrystalline glass as described in claim 1, characterized in that, The main chemical composition of the lithium tailings includes: SiO2 75-79 wt%, Al2O3 12-14 wt%, Na2O 5-7 wt%, and the remaining components 4-8 wt%.

4. The fluorosilicate microcrystalline glass as described in claim 1, characterized in that, The mass ratio of the fluorine-containing sludge to lithium tailings is 3:7 to 5:

5.

5. The fluorosilicate microcrystalline glass as described in claim 1, characterized in that, The fluorosilicate microcrystalline glass has a composite crystalline phase of bainite and calcium fluoride.

6. A method for preparing fluorosilicate microcrystalline glass according to any one of claims 1 to 5, characterized in that, include: Step 1: Dry the fluoride-containing sludge and lithium tailings; Step 2: Mix the fluoride-containing sludge and lithium tailings according to the preset mass ratio; Step 3: Melt the well-mixed batch at 1500-1550℃ for 1-1.5 hours to obtain molten glass; Step 4: Cast the molten glass into shape and transfer it to a muffle furnace at 600-650°C for annealing to obtain the basic microcrystalline glass material; Step 5: Heat the basic microcrystalline glass material to 950-1050℃ and keep it at that temperature for 1-2 hours, then cool it to room temperature to obtain a high-hardness microcrystalline glass material with bainite and calcium fluoride as the composite crystal phase.

7. The preparation method according to claim 6, characterized in that, In step 1, the drying process involves drying at 100~120℃ for 20~30 hours.

8. The preparation method according to claim 6, characterized in that, In step 4, the annealing process takes 5 to 7 hours.

9. The preparation method according to claim 6, characterized in that, In step 5, the temperature is increased to 950-1050℃ at a heating rate of 8~12K / min.

10. The application of a fluorosilicate microcrystalline glass as described in any one of claims 1 to 5 or a fluorosilicate microcrystalline glass prepared by any one of claims 6 to 9 in building decoration materials.

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