Method for preparing alkali-free glass based on low-value mineral raw materials and solid wastes

Abstract

The invention discloses a method for preparing alkali-free glass based on low-value mineral raw materials and solid wastes, and relates to the technical field of inorganic non-metallic materials and energy-saving manufacturing. According to the method, high-thermal-conductivity low-value minerals such as anorthite or anorthite-rich basic oblique feldspar, quartz or quartz-rich tailings, quick lime or carbide slag are adopted to prepare a low-energy-consumption alkali-free glass batch, and the alkali environment and mechanical force synergistic effect of the batch are utilized in the pretreatment process, so that the low-energy-consumption alkali-free glass is obtained; the fineness and crystallinity of the quartz and other raw materials are reduced, and the crystal stability of the quartz and other raw materials is destroyed to a certain extent, so that the melting temperature of the alkali-free glass is reduced, and the alkali-free glass with low cost, low energy consumption and excellent performance is prepared. The preparation method has the advantages of low raw material cost, low melting temperature and simple process, and can be applied to the fields of alkali-free glass, glass fiber preparation and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of inorganic non-metallic materials and energy-saving manufacturing technology, and specifically discloses a method for preparing alkali-free glass based on low-value mineral raw materials and solid waste, an alkali-free glass, and a fiber based on the alkali-free glass. BACKGROUND

[0002] Glass can be divided into three categories: alkali-free glass, medium-alkali glass, and high-alkali glass, according to the difference in R2O metal (alkali metal oxide) content. Among them, the R2O metal (alkali metal oxide) content of alkali-free glass (Electrical-grade glass) is below 0.8%. Alkali-free glass can be prepared into alkali-free glass fiber through a fusion drawing process due to its excellent mechanical and electrical properties, and is widely used in high resistivity electrical insulation materials, printed circuit board substrates, medical devices, aerospace composites, and other fields.

[0003] In the traditional production process of alkali-free glass, the main raw materials include acidic oxides, alkaline earth and alkali metal oxides. Acidic oxides in alkali-free glass are used as network formers and intermediate oxides, including SiO2, Al2O3, and ZrO2, etc. Currently, kaolinite or pyrophyllite is usually used as the raw material for introducing Al2O3 in the production of alkali-free glass. However, due to the expansion of application fields and the improvement of raw material requirements, kaolinite and pyrophyllite used in the alkali-free glass industry have gradually become scarce minerals. In the production of alkali-free glass, kaolinite and pyrophyllite have low tap density and low thermal conductivity characteristics, and need to absorb additional heat to drive dehydroxylation and phase transition during the melting process of alkali-free glass, which significantly increases the melting energy consumption compared to conventional high thermal conductivity minerals.

[0004] Therefore, reducing the energy consumption and cost of alkali-free glass production has become an important research direction for the industry development.

[0005] High melting temperature is the main source of production energy consumption. Due to the low content of alkali metal oxides in alkali-free glass, its melting temperature is higher than that of other glasses.

[0006] Currently, there have been some patent technology reports on reducing the energy consumption of alkali-free glass preparation.

[0007] For example, Chinese invention patent CN117417123A discloses a method for preparing alkali-free glass substrate, which reduces the energy consumption in the melting process by crushing, tabletting and preheating the batch. Chinese invention patent CN117623632A proposes a method for preparing high-strength microcrystalline glass, which reduces the particle size of the batch through wet ball milling to reduce the melting temperature. Although the above-mentioned patents propose various methods for reducing melting energy consumption, the complex pretreatment steps still require additional energy consumption, and simply relying on particle size control on the physical scale has limited effect on reducing the melting temperature.

[0008] Chinese invention patent CN119191705A discloses a low-melting-point antibacterial alkali-free glass and its preparation method, which lowers the melting point of the batch by adjusting the combination of different raw materials. Chinese invention patent CN117700098A discloses a low-carbon, low-energy-consumption soda-lime-silica glass batch, which reduces carbon emissions during glass production by changing the composition of the batch. While these patents control the melting point and carbon emissions of glass production by adjusting the raw material composition, they still use relatively expensive raw materials such as kaolinite, which have high phase change energy consumption, thus hindering energy conservation, cost reduction, and energy saving in the alkali-free glass production industry.

[0009] Based on the reliance on kaolinite in existing technologies, as well as the problems of high cost and high energy consumption, the inventors have made great strides and discovered a method for preparing alkali-free glass using existing low-value mineral raw materials and solid waste. The alkali-free glass prepared has excellent properties. Summary of the Invention

[0010] In view of the shortcomings of the prior art, the present invention uses high thermal conductivity, low-value minerals or tailings rich in such minerals as raw materials. In the pretreatment, alkaline solid waste is introduced, and the materials are ground under mechanical activation conditions to activate raw materials such as quartz and generate low-melting-point silicates, thereby lowering the melting temperature of alkali-free glass and producing low-cost, low-energy-consumption, and high-performance alkali-free glass.

[0011] The batching materials and production process adopted in this invention have the characteristics of low raw material cost, low melting temperature and simple process. Compared with the traditional alkali-free glass production process, the melting energy consumption is reduced by 20%-40%, which provides a feasible method for the glass industry to achieve carbon emission reduction.

[0012] In a first aspect, the present invention proposes a method for preparing alkali-free glass based on low-value mineral raw materials and solid waste, characterized by comprising the following steps: (1) Mix the raw materials to obtain alkali-free glass batch material; (2) The alkali-free glass batch is subjected to wet ball milling to obtain ball milling activated slurry; (3) The ball-milled activated slurry is dried to obtain ball-milled activated alkali-free glass batch material; (4) High-temperature firing ball milling activation of alkali-free glass batch to obtain alkali-free glass.

[0013] Preferably, the raw materials in step (1) include low-value mineral raw materials, solid waste, boric acid and bauxite.

[0014] Preferably, the low-value mineral raw material is plagioclase feldspar and / or plagioclase-containing rock; the solid waste is quartz and / or quartz-containing tailings, quicklime and / or carbide slag.

[0015] Preferably, the low-value mineral raw material has a room temperature thermal conductivity of not less than 3.5 W / (m·K).

[0016] Preferably, the plagioclase rock containing calcium feldspar contains at least 70% calcium feldspar.

[0017] Preferably, the quartz content of the quartz-containing tailings is not less than 80%.

[0018] Preferably, step (1) further includes crushing the raw materials and passing them through a 100-300 mesh sieve to unify the particle size of the raw materials.

[0019] Preferably, the raw materials are formulated in the following mass percentages based on oxides: 50%~54% SiO2, 14%~18% Al2O3, 20%~25% CaO, 0.1%~1% Fe2O3, 0.5%~5% MgO, 0.1%~0.8% K2O+Na2O, and 5%~9% B2O3, to obtain an alkali-free glass batch.

[0020] Preferably, the following steps are also included: In step (2), the grinding and activation conditions are: ball-to-material ratio 1:1 to 10:1, planetary ball mill speed 400 to 800 rpm, ball milling time 2 to 12 h, and liquid-to-solid mass ratio 1:1 to 5:1.

[0021] Preferably, in step (3), the ball-milled activated slurry is dried at 60~80 ℃ for 6~24 h to obtain ball-milled activated alkali-free glass batching material.

[0022] Preferably, in step (4), the high-temperature firing conditions are: firing temperature 1200~1550 ℃, holding time 30~180 min.

[0023] Preferably, after the heat preservation is completed, a mold annealing is performed, with an annealing temperature of 500~800 ℃ and an annealing time of 30~180 min.

[0024] Preferably, the alkali-free glass obtained in step (4) has a melting temperature not higher than 1380°C, more preferably not higher than 1350°C, and more preferably not higher than 1320°C.

[0025] Secondly, the present invention also provides an alkali-free glass, which is prepared according to the method for preparing alkali-free glass based on low-value mineral raw materials and solid waste as described in the first aspect.

[0026] Preferably, the melting temperature of the alkali-free glass is 1300-1380℃, more preferably not higher than 1350℃, and more preferably not higher than 1320℃.

[0027] Thirdly, the present invention also claims protection for an alkali-free glass fiber prepared using alkali-free glass as described in the second aspect.

[0028] The beneficial effects of this invention include: 1. This technical solution uses industrial solid waste (such as carbide slag and quartz tailings) and high thermal conductivity, low-value mineral raw materials (such as anorthite or anorthite-rich basic plagioclase) as the main raw materials to replace kaolinite and pyrophyllite commonly used in the alkali-free glass industry. Anorthite can provide abundant calcium, aluminum, and silicon sources for the preparation of low-cost, low-energy-consumption, and high-performance alkali-free glass. During the melting process, the dehydroxylation reaction of kaolinite has high heat absorption and generates high-melting-point phases in subsequent phase transitions, resulting in higher melting temperatures and energy consumption. In contrast, the melting process of anorthite is stable and easily reacts with silicate minerals to generate glassy, ​​low-temperature eutectic, avoiding the additional energy consumption caused by complex phase transitions. This reduces raw material costs, alleviates the supply pressure of scarce minerals such as kaolinite, and realizes the resource utilization of tailings, meeting the urgent needs of circular economy and solid waste management.

[0029] 2. This technical solution utilizes the synergistic effect of wet ball milling mechanical activation and alkaline solid waste to destroy the crystal structure of raw materials such as quartz, reduce the fineness and crystallinity of the raw materials, and generate a low-melting-point silicate phase, significantly reducing the glass melting temperature. Compared with traditional processes, the melting energy consumption is reduced by 20%-40%, meeting the core requirements for carbon emission reduction and energy consumption control.

[0030] 3. This technical solution is based on a method for preparing alkali-free glass from low-value mineral raw materials and solid waste. By improving the thermal conductivity of the alkali-free glass batch and supplementing it with an effective pretreatment method, the melting energy consumption is reduced. This pretreatment process is simple and does not require pressing, granulation, or preheating of the batch, yet it can significantly reduce the melting temperature, making it suitable for widespread application. Attached Figure Description

[0031] Figure 1 The XRD diffraction pattern of the tailings (mainly composed of quartz) from the kaolinite mine in Maoming, Guangdong, used in Example 1; Figure 2 The XRD diffraction pattern of the alkali-free glass product prepared in Example 1; Figure 3 The data provided are thermal analysis data of the melting process in Example 1, Comparative Example 2, and Comparative Example 3. Detailed Implementation

[0032] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the embodiments described in this specification are merely for explaining the invention and are not intended to limit the invention. The parameters, proportions, etc., of the embodiments can be selected according to local conditions without substantially affecting the results. Unless otherwise specified, the reagents and methods used in the embodiments are conventional in the art. Example 1

[0033] This embodiment describes a method for preparing alkali-free glass based on low-value mineral raw materials and solid waste, including the following steps: (1) The raw materials selected in this embodiment include calcium feldspar from the White Mountain calcium feldspar mine in Greenland, tailings from the kaolin mine in Maoming, Guangdong (mainly composed of quartz), quicklime, boric acid, and bauxite. The materials are crushed, dried, and screened through a 200-mesh sieve before being used as raw materials for alkali-free glass batching. (2) The oxides of the alkali-free glass batch are composed of the mass percentages shown in Table 1. Table 1 shows the oxide composition of batch #1. Table 1 shows the oxide composition of batch #1. (3) Prepare alkali-free glass batch material using the raw materials prepared in step 1 according to the mass percentage composition described in step 2. (4) Weigh 1 kg of alkali-free glass batch material, add deionized water (liquid-solid mass ratio 3:1) and ball milling beads (ball-material ratio 1:1), and ball mill in a planetary ball mill at 600 rpm for 4 h to obtain ball milled activated alkali-free glass slurry; (5) Place the slurry in an oven and dry it at 80 ℃ for 6 h to obtain ball mill activated alkali-free glass batch material; (6) Place the batch material into a muffle furnace, set the firing temperature to 1450 ℃, and the holding time to 150 min. After the holding time is over, pour the molten glass liquid into a graphite mold to fix the mold and obtain alkali-free glass semi-finished product. (7) Place the alkali-free glass semi-finished product into an annealing furnace, set the annealing temperature to 750 ℃ ​​and the annealing time to 50 min. After the annealing is completed and the furnace temperature drops to room temperature, polish and process the glass to obtain the desired alkali-free glass finished product. Example 2

[0034] This embodiment describes a method for preparing alkali-free glass based on low-value mineral raw materials and solid waste, including the following steps: (1) The raw materials selected in this embodiment include calcium feldspar from Linfen, Shanxi, and tailings from the beneficiation of kaolinite mine in Maoming, Guangdong (mainly composed of quartz), calcium carbide slag, boric acid, and bauxite. The materials are crushed, dried, and screened through a 100-mesh sieve before being used as raw materials for alkali-free glass batching. (2) The oxides of the alkali-free glass batch are composed of the mass percentages shown in Table 2. Table 2 shows the oxide composition of batch #2. Table 2 shows the oxide composition of batch #2. (3) Prepare alkali-free glass batch material using the raw materials prepared in step 1 according to the mass percentage composition described in step 2. (4) Weigh 1 kg of alkali-free glass batch material, add deionized water (liquid-solid mass ratio 5:1) and ball milling beads (ball-material ratio 7:1), and ball mill in a planetary ball mill at 400 rpm for 8 h to obtain ball milled activated alkali-free glass slurry; (5) The slurry was placed in an oven and dried at 60 ℃ for 18 h to obtain ball mill activated alkali-free glass batch material; (6) Place the batch material into a muffle furnace, set the firing temperature to 1550 ℃, and the holding time to 90 min. After the holding time is completed, pour the molten glass liquid into a graphite mold to fix the mold and obtain alkali-free glass semi-finished product. (7) Place the alkali-free glass semi-finished product into an annealing furnace, set the annealing temperature to 600 ℃ and the annealing time to 30 min. After the annealing is completed and the furnace temperature drops to room temperature, polish and process the product to obtain the desired alkali-free glass finished product. Example 3

[0035] This embodiment describes a method for preparing alkali-free glass based on low-value mineral raw materials and solid waste, including the following steps: (1) The raw materials selected in this embodiment include basic plagioclase rock samples taken from Yongchuan area of ​​Chongqing, tailings from kaolin mine in Maoming, Guangdong (mainly composed of quartz), carbide slag, boric acid and bauxite. The materials are crushed, dried and screened through a 300-mesh sieve before being used as raw materials for alkali-free glass batching. (2) The oxides of the alkali-free glass batch are composed of the mass percentages shown in Table 2, and Table 3 shows the oxide composition of batch #3; Table 3 shows the oxide composition of batch #3. (3) Prepare alkali-free glass batch material using the raw materials prepared in step 1 according to the mass percentage composition described in step 2. (4) Weigh 1 kg of alkali-free glass batch material, add deionized water (liquid-solid mass ratio 1:1) and ball milling beads (ball-material ratio 3:1), and ball mill in a planetary ball mill at 800 rpm for 2 h to obtain ball milled activated alkali-free glass slurry; (5) The slurry was placed in an oven and dried at 70 °C for 12 h to obtain ball mill activated alkali-free glass batch material; (6) Place the batch material into a muffle furnace, set the firing temperature to 1500 ℃, and the holding time to 180 min. After the holding time is over, pour the molten glass liquid into a graphite mold to fix the mold and obtain alkali-free glass semi-finished product. (7) Place the alkali-free glass semi-finished product into an annealing furnace, set the annealing temperature to 550 ℃ and the annealing time to 120 min. After the annealing is completed and the furnace temperature drops to room temperature, polish and process the glass to obtain the desired alkali-free glass finished product. Comparative Example 1

[0036] The processing steps and oxide composition of the alkali-free glass batch are the same as in Example 1, but the raw material is kaolinite from Maoming, Guangdong, which is used as the aluminum source batch instead of the white mountain calcium feldspar from Greenland. Comparative Example 2

[0037] The raw materials and oxide composition of the alkali-free glass batch are the same as those in Example 2, but steps 4 and 5 are omitted, i.e., mechanical activation treatment is not performed. Comparative Example 3

[0038] The oxide composition of the alkali-free glass batch is the same as that in Example 3. The raw material is kaolinite from Maoming, Guangdong, which is used as the aluminum source batch instead of the white mountain calcium feldspar from Greenland. In addition, steps 4 and 5 are omitted from the process, that is, mechanical activation treatment is not performed.

[0039] The performance indicators of the alkali-free glass products of Examples 1-3 and Comparative Examples 1-3 were measured, and the test results are shown in the table below. The melting temperature refers to the lowest temperature at which the alkali-free glass batch completely transforms into the glass phase after a uniform holding time of 120 min. Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal conductivity W / (m K) 6.61 6.93 6.79 5.87 6.93 6.08 Density (g / cm 3 ) 2.56 2.53 2.54 2.52 2.57 2.54 Melting temperature (°C) 1384 1326 1363 1431 1487 1536 Young's modulus (GPa) 79.2 78.5 78.8 79.3 79.1 78.6 Visible light transmittance (%) 92.4 91.8 92.0 92.1 91.6 92.2 Specifically, X-ray diffraction was used to analyze the tailings (mainly quartz) from the kaolinite mine in Maoming, Guangdong, used in Example 1, and the resulting alkali-free glass product. The analysis results are as follows: Figure 1 As shown in Figure 2. Simultaneously, the energy consumption changes during the melting process of Example 1, Comparative Example 2, and Comparative Example 3 were tested using a high-temperature synchronous thermal analyzer. The heat flow data of the samples were integrated over the target temperature range, and then divided by the sample mass to obtain the energy consumption (J / g) per unit mass of sample in that temperature range. The results are as follows: Figure 3 As shown.

[0040] From the appendix Figure 1 (XRD diffraction pattern of tailings from the beneficiation of kaolinite mine in Maoming, Guangdong in Example 1) It can be seen that the main component of the tailings from the beneficiation of kaolinite mine in Maoming, Guangdong is quartz.

[0041] From the appendix Figure 2 (XRD diffraction pattern of the alkali-free glass product prepared in Example 1) It can be seen that the alkali-free glass batch has been completely transformed into the glass phase.

[0042] From the appendix Figure 3(Thermal analysis data of the melting process of Example 1, Comparative Example 2, and Comparative Example 3) It can be seen that Comparative Example 3 has the highest heat absorption during the heating process from 25 to 1400 °C. The melting temperature of Example 1 is lower than that of Comparative Example 2, and its heat absorption is the smallest after deducting the influence of the melting temperature difference.

[0043] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A method for preparing alkali-free glass based on low-value mineral raw materials and solid waste, characterized in that, Includes the following steps: (1) Mix the raw materials to obtain alkali-free glass batch material; (2) The alkali-free glass batch is subjected to wet ball milling to obtain ball milling activated slurry; (3) The ball-milled activated slurry is dried to obtain ball-milled activated alkali-free glass batch material; (4) Firing ball mill activated alkali-free glass batch to obtain alkali-free glass; The raw materials in step (1) include low-value mineral raw materials, solid waste, boric acid and bauxite; The low-value mineral raw materials are plagioclase feldspar and / or plagioclase-containing rocks; the solid wastes are quartz and / or quartz-containing tailings, quicklime and / or carbide slag.

2. The method for preparing alkali-free glass based on low-value mineral raw materials and solid waste according to claim 1, characterized in that, Step (1) also includes crushing the raw materials and passing them through a 100-300 mesh sieve.

3. The method for preparing alkali-free glass based on low-value mineral raw materials and solid waste according to claim 1, characterized in that, The raw materials are formulated in the following mass percentages based on oxides: 50%~54% SiO2, 14%~18% Al2O3, 20%~25% CaO, 0.1%~1% Fe2O3, 0.5%~5% MgO, 0.1%~0.8% K2O+Na2O, and 5%~9% B2O3, and mixed to obtain alkali-free glass batch material.

4. A method for preparing alkali-free glass based on low-value mineral raw materials and solid waste according to any one of claims 1-3, characterized in that, Includes the following steps: In step (2), the grinding and activation conditions are: ball-to-material ratio 1:1 to 10:1, planetary ball mill speed 400 to 800 rpm, ball milling time 2 to 12 h, and liquid-to-solid mass ratio 1:1 to 5:

1.

5. A method for preparing alkali-free glass based on low-value mineral raw materials and solid waste according to any one of claims 1-3, characterized in that, In step (3), the ball-milled activated slurry is dried at 60~80 ℃ for 6~24 h to obtain ball-milled activated alkali-free glass batching material.

6. A method for preparing alkali-free glass based on low-value mineral raw materials and solid waste according to any one of claims 1-3, characterized in that, In step (4), the high-temperature firing conditions are: firing temperature 1200~1550 ℃, holding time 30~180 min.

7. A method for preparing alkali-free glass based on low-value mineral raw materials and solid waste according to any one of claims 1-3, characterized in that, After the heat preservation is completed, mold annealing is carried out. The annealing temperature is 500~800 ℃ and the annealing time is 30~180 min.

8. An alkali-free glass, characterized in that: The alkali-free glass is prepared according to any one of claims 1-7 using a method for preparing alkali-free glass based on low-value mineral raw materials and solid waste.

9. The alkali-free glass according to claim 9, characterized in that: The melting temperature of the alkali-free glass is 1300-1380℃.

10. An alkali-free glass fiber, characterized in that: It is prepared using the alkali-free glass as described in any one of claims 8-9.

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