Method for producing glass ceramics from ardealite, glass ceramics and ardealite-based mixed raw material

Abstract

The invention provides a method for producing glass ceramics from ardealite, glass ceramics and an ardealite-based mixed raw material.The method for producing glass ceramics from ardealite comprises the steps that the ardealite-based mixed raw material is obtained, and the ardealite-based mixed raw material comprises, by mass, 30%-45% of ardealite, 20%-40% of quartz sand, 5%-10% of sodium carbonate and 5%-10% of sodium fluosilicate; 5%-15% of feldspar; melting and molding the ardealite-based mixed raw material to obtain a glass substrate; and carrying out heat treatment on the glass substrate to obtain the microcrystalline glass. The ardealite is originally applied to preparation of the microcrystalline glass under the condition of not carrying out desulfurization treatment, the steps are remarkably simplified, the energy consumption and the cost are reduced, and the scheme is simple, efficient and worthy of popularization.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic non-metallic material preparation, and in particular relates to a method for producing microcrystalline glass from phosphogypsum, microcrystalline glass, and phosphogypsum-based mixed raw materials. Background Art

[0002] Phosphogypsum is a major industrial byproduct of wet-process phosphoric acid production, generating approximately 4.5 to 5.5 tons of phosphogypsum for every ton of phosphoric acid produced. With the rapid development of the phosphorus chemical industry, annual phosphogypsum emissions have increased dramatically, with global stockpiles reaching billions of tons and continuing to grow at a rate of hundreds of millions of tons per year. The accumulation of large amounts of phosphogypsum not only consumes significant land resources but also contains harmful substances such as soluble phosphorus and fluorine, which leach into the soil and groundwater through rainwater, causing environmental pollution and ecological damage. This has become a key bottleneck hindering the sustainable development of the phosphorus chemical industry. Phosphogypsum is primarily composed of calcium sulfate (CaSO₄·2H₂O), typically at a concentration between 70% and 90%. It also contains various impurities, including silica, aluminum oxide, iron oxide, fluoride, phosphates, and organic matter. The presence of these impurities complicates the direct utilization of phosphogypsum, resulting in a long-standing low utilization rate. Currently, the global utilization rate for phosphogypsum is generally less than 30%, and the majority of phosphogypsum is still stockpiled.

[0003] As a traditional basic materials industry, the glass industry has high requirements for the quality and purity of raw materials. The rich sulfur content in phosphogypsum has become the main obstacle to its application in glass production. In the glass production process, if phosphogypsum is directly used as raw material without effective treatment, as the temperature rises, the calcium sulfate in it will decompose and produce sulfur dioxide (SO2) gas. When the sulfur content in the glass exceeds a certain threshold (usually between 0.1% and 0.3%, depending on the type of glass and performance requirements), it will have a significant negative impact on many properties of the glass.

[0004] To address the sulfur content issue in phosphogypsum in glass production and realize its resource utilization, desulfurization of phosphogypsum is a key step. Currently, the main methods for desulfurizing calcium sulfate in phosphogypsum are pyrolysis and reduction. While these two methods can achieve desulfurization of phosphogypsum to a certain extent, they both suffer from high energy consumption, complex processes, and high costs, limiting their application in the resource utilization of phosphogypsum in the glass industry. Summary of the Invention

[0005] In order to solve the technical problems of high energy consumption, complex process and high cost in the above-mentioned conventional technologies for desulfurization of phosphogypsum, the present invention provides a method for producing microcrystalline glass from phosphogypsum, comprising the steps of:

[0006] Obtaining a phosphogypsum-based mixed raw material, wherein the phosphogypsum-based mixed raw material comprises, by mass fraction, 30% to 45% of phosphogypsum, 20% to 40% of quartz sand, 5% to 10% of soda ash, 5% to 10% of sodium fluorosilicate, and 5% to 15% of feldspar;

[0007] melting and shaping the phosphogypsum-based mixed raw material to obtain a glass substrate;

[0008] The glass substrate is subjected to heat treatment to obtain glass-ceramics.

[0009] Furthermore, the heat treatment includes a nucleation treatment and a crystallization treatment;

[0010] Nucleation treatment: heating the glass substrate to 700-850° C. and keeping the temperature for 2-3 hours at a heating rate of 3-5° C. / min;

[0011] Crystallization treatment: heating the glass substrate after the nucleation treatment to 1000-1100° C. and keeping the temperature for 1.5-2 hours; the heating rate is 1-2° C. / min.

[0012] Furthermore, the method further comprises: cooling the glass substrate after the crystallization treatment, wherein the cooling rate of the cooling treatment is 5-10° C. / min.

[0013] Furthermore, the chemical composition of the phosphogypsum includes, by mass fraction, CaSO4 70% to 95%, and S 16% to 25%.

[0014] Furthermore, the melting and shaping of the phosphogypsum-based mixed raw materials to obtain the glass substrate includes: melting the phosphogypsum-based mixed raw materials into glass liquid at a melting temperature of 1300-1600° C., and the melting time is 150-200 minutes.

[0015] Furthermore, the phosphogypsum-based mixed raw material is melted and formed to obtain a glass substrate, and the forming comprises: cooling the melted glass liquid to a viscosity of 10 4 ~10 5 After paving, the sheet is rolled into a plate at a rolling speed of 0.25 to 1 m / min.

[0016] Furthermore, the phosphogypsum-based mixed raw material also includes an additive for adjusting glass properties, and the mass percentage of the additive in the phosphogypsum-based mixed raw material is 3% to 10%.

[0017] The present invention provides a phosphogypsum-based mixed raw material, which comprises, by mass fraction, 30% to 45% of phosphogypsum, 20% to 40% of quartz sand, 5% to 10% of soda ash, 5% to 10% of sodium fluorosilicate, and 5% to 15% of feldspar.

[0018] The present invention provides a microcrystalline glass, which is prepared by the method for producing microcrystalline glass from phosphogypsum as described in any one of the above.

[0019] Furthermore, the crystal size of the glass-ceramics is 1 to 30 microns, the bending strength of the glass-ceramics is not less than 95 MPa, and the impact toughness is not less than 2.5 KJ / M 2 , the thermal expansion coefficient is 5~8×10 -6 / ℃.

[0020] Compared with the prior art, the present invention has at least the following advantages:

[0021] In commonly used technologies, when phosphogypsum is used in the process of glass preparation, due to the high sulfur content of phosphogypsum, excessive sulfur content in the glass will seriously affect the performance of the glass, so it is usually necessary to desulfurize the phosphogypsum. However, the desulfurization process has problems such as high energy consumption, complex process, and high cost.

[0022] The present invention provides a method for producing microcrystalline glass from phosphogypsum, abandoning the traditional desulfurization treatment link and innovatively applying phosphogypsum directly to the preparation process of microcrystalline glass, thereby achieving process simplification and cost reduction and efficiency improvement. The present invention accurately matches the phosphogypsum-based mixed raw materials so that the raw materials can fully exert the synergistic effect: quartz sand provides the main silicon source and is the main component of the glass network structure; soda ash acts as a flux to lower the melting point and viscosity of the glass; sodium fluorosilicate acts as a clarifier and flux, helping to remove bubbles and impurities in the glass liquid; feldspar provides elements such as aluminum, potassium, and sodium to adjust the properties of the glass; phosphogypsum mainly provides a calcium source, increases the chemical stability of the glass, reduces the high-temperature viscosity of the glass, and improves the mechanical strength of the glass. These raw materials interact with each other to jointly construct a stable glass network structure.

[0023] The present invention utilizes a process design from batching, melting, molding to heat treatment, so that phosphogypsum can be directly used in the preparation of microcrystalline glass without desulfurization treatment, taking into account both product quality and performance assurance, while eliminating the process of phosphogypsum desulfurization pretreatment, saving energy, and reducing manpower and material resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0025] Figure 1 This is a physical picture of the glass-ceramic plate prepared in Example 1 of the present invention;

[0026] Figure 2 This is a physical picture of the microcrystalline glass plate prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those in the examples of the present invention may also be used to implement the present invention.

[0030] The present invention provides a method for producing glass-ceramics from phosphogypsum, comprising the steps of:

[0031] S1. Obtain a phosphogypsum-based mixed raw material, which comprises, by mass fraction, 30% to 45% phosphogypsum, 20% to 40% quartz sand, 5% to 10% soda ash, 5% to 10% sodium fluorosilicate, and 5% to 15% feldspar.

[0032] In the present invention, the phosphogypsum-based mixed raw material may include, by mass fraction, 30% to 40% phosphogypsum, 30% to 40% quartz sand, 5% to 10% soda ash, 5% to 10% sodium fluorosilicate, and 5% to 15% feldspar.

[0033] In the present invention, the phosphogypsum-based mixed raw material may further include additives for adjusting glass properties, the specific types and contents of which are selected according to the performance requirements of the desired microcrystalline glass plate, and the mass percentage of the additives in the phosphogypsum-based mixed raw material is 3% to 10%.

[0034] In the present invention, the chemical composition of the phosphogypsum may include, by mass fraction, CaSO4 70% to 95%, S 16% to 25%; illustratively, by mass fraction, the chemical composition of the phosphogypsum may include, by mass fraction, CaSO4 70% to 90%, S 16% to 21%.

[0035] In some embodiments of the present invention, phosphogypsum may also include components such as Ca, Al, Si, P2O5 and F, among which Ca, Al and Si can be directly used as the main components of glass, and P2O5 and F can be used as nucleating agents to promote glass crystallization.

[0036] In some embodiments of the present invention, the phosphogypsum may be screened through 20-30 meshes; illustratively, the phosphogypsum may be screened through 24 meshes.

[0037] S2. Melting and shaping the phosphogypsum-based mixed raw material to obtain a glass substrate.

[0038] In the present invention, the melting and shaping of the phosphogypsum-based mixed raw materials to obtain the glass substrate comprises: melting the phosphogypsum-based mixed raw materials into glass liquid at a melting temperature of 1300-1600° C., and the melting time is 150-200 minutes.

[0039] In some embodiments of the present invention, a sulfur-containing tail gas absorption device can be added to the melting equipment. As calcium sulfate decomposes and produces large amounts of SO₂ gas, the sulfur-containing tail gas absorption device can promptly and efficiently capture and recover this gas, minimizing SO₂ gas escape and converting it into usable industrial raw materials, such as sulfuric acid. This efficient flue gas recovery not only prevents SO₂ gas from polluting the environment, but also recycles sulfur resources and reduces production costs.

[0040] In some embodiments of the present invention, the melting equipment includes a glass furnace, and the melting process can be performed in the glass furnace.

[0041] In a high-temperature melting environment of 1300-1600°C, calcium sulfate (CaSO4) in phosphogypsum will undergo a decomposition reaction, and the chemical equation is: CaSO4→CaO+SO2↑. In the present invention, by precisely controlling parameters such as the temperature and atmosphere in the glass furnace, the decomposition reaction of calcium sulfate can be kept in a relatively stable and controllable state. On the one hand, the appropriate high-temperature conditions ensure that calcium sulfate can be fully decomposed, providing the necessary calcium oxide (CaO) component for the subsequent formation of glass liquid; on the other hand, it avoids excessive or incomplete decomposition reactions caused by excessively high or low temperatures, thereby reducing the uncertainty of sulfur dioxide (SO2) gas generation.

[0042] In some embodiments of the present invention, the melting temperature may also be 1400-1500°C.

[0043] In the present invention, the forming of the glass substrate by melting and shaping the phosphogypsum-based mixed raw material includes: hydraulically rolling the glass into a plate, and the rolling speed can be 0.25-1 m / min.

[0044] S3. Heat-treating the glass substrate to obtain glass-ceramics.

[0045] In the present invention, the heat treatment includes a nucleation treatment and a crystallization treatment;

[0046] Nucleation treatment: The glass substrate is heated at a rate of 3-5°C / min to 700-850°C and held at this temperature for 2-3 hours. During the nucleation stage of the heat treatment, the glass begins to undergo structural adjustments, with atoms or molecules rearranging to form crystal nuclei. Carefully designed temperature and time conditions during the nucleation stage promote structural adjustments conducive to the formation of uniform crystal nuclei. Furthermore, the holding time during this stage is sufficiently long to allow the various components within the glass to fully diffuse and interact.

[0047] Crystallization treatment: The glass substrate after the nucleation treatment is heated to 1000-1100°C at a rate of 1-2°C / min and kept warm for 1.5-2 hours. During the crystallization stage, the crystal nuclei gradually grow to form a uniform crystal structure. The high temperature conditions promote the rapid growth of crystals and also allow the sulfur element to be better fixed in the crystal structure. The sulfur element will chemically react with other components in the glass (such as calcium, silicon, etc.) to form stable compounds, thereby preventing the sulfur element from being free and agglomerated in the glass, and reducing the potential damage of sulfur element to the glass performance.

[0048] In some embodiments of the present invention, the glass substrate after the crystallization treatment can also be cooled at a cooling rate of 5 to 10°C / min. During the cooling process, the crystal structure inside the glass gradually stabilizes, and the grain size is further refined. Because the adverse effects of sulfur on glass properties have been effectively avoided in the previous heat treatment stage, the cooled microcrystalline glass plate has the characteristics of uniform grain size and stable performance. For example, the glass substrate can be cooled to room temperature at a cooling rate of 5 to 10°C / min.

[0049] In some specific implementations of the present invention, a variable frequency fan can be used to adjust the cooling rate during the cooling process.

[0050] The present invention provides a microcrystalline glass, which is prepared by the method for producing microcrystalline glass from phosphogypsum as described in any one of the above.

[0051] Furthermore, the grain size of the glass-ceramics is 1 to 30 microns.

[0052] Furthermore, the bending strength of the glass-ceramics is not less than 95 MPa, and the impact toughness is not less than 2.5 KJ / M 2 , the thermal expansion coefficient is 5~8×10 -6 / ℃.

[0053] In order to facilitate those skilled in the art to further understand the present invention, examples are given below:

[0054] Example 1

[0055] Ingredients: Prepare phosphogypsum-based mixed raw materials, which, by mass fraction, include: phosphogypsum 40%, quartz sand 30%, soda ash 7%, sodium fluorosilicate 8%, feldspar 10%, and other (additives) 5%; among which, the main components of phosphogypsum include: CaSO4 90%, S21%.

[0056] Melting: The phosphogypsum-based mixed raw materials are placed in a glass furnace and melted at 1450°C for 150 minutes to form a uniform glass melt. During this stage, calcium sulfate decomposes to produce SO2 gas, which is recovered in a flue gas recovery unit for other industrial uses.

[0057] Molding: Cool the melted glass to a viscosity of 10 4 After paving, the glass is hydraulically rolled into a plate through a calender to obtain a glass substrate, and the rolling speed is 1m / min.

[0058] Heat treatment: The glass substrate is sent into a heat treatment kiln for microcrystallization treatment:

[0059] Nucleation treatment: heating to 800°C at 5°C / min and keeping at this temperature for 2 hours to promote the formation of glass nuclei.

[0060] The temperature was raised to 1100°C at a rate of 2°C / min and kept at that temperature for 1.5 hours to allow crystal growth.

[0061] Cooling treatment: After cooling, a microcrystalline glass plate is obtained. The cooling rate of the cooling treatment is 8°C / min. The grain size is uniform, the grain size distribution is 1 to 30 microns, and the performance is stable. The microcrystalline glass obtained in this embodiment is shown in the figure. Figure 1 As shown, the performance analysis table of the microcrystalline glass prepared in this embodiment is shown in Table 1.

[0062] Table 1 Performance analysis of glass-ceramic products

[0063]

[0064] Example 2

[0065] Ingredients: Prepare phosphogypsum-based mixed raw materials, which, by mass fraction, include: phosphogypsum 35%, quartz sand 36%, soda ash 6%, sodium fluorosilicate 8%, feldspar 10%, and other (additives) 5%; among which, the main components of phosphogypsum include: CaSO4 90%, S21%.

[0066] Melting: The phosphogypsum-based mixed raw materials are placed in a glass kiln and melted at 1480°C for 150 minutes to form a uniform glass melt. During this stage, calcium sulfate decomposes to produce SO2 gas, which is recovered in a flue gas recovery unit for other industrial uses.

[0067] Molding: Cool the melted glass to a viscosity of 10 4 After paving, the glass is hydraulically rolled into a plate through a calender to obtain a glass substrate, and the rolling speed is 1m / min.

[0068] Heat treatment: The glass substrate is sent into a heat treatment kiln for microcrystallization treatment:

[0069] Nucleation treatment: heating to 850°C at 5°C / min and keeping at this temperature for 2 hours to promote the formation of glass nuclei.

[0070] The temperature was raised to 1050°C at a rate of 2°C / min and kept at that temperature for 1.5 hours to allow crystal growth.

[0071] Cooling treatment: After cooling, the microcrystalline glass plate is obtained. The cooling rate of the cooling treatment is 8℃ / min. The grain size is uniform, the grain size distribution is 1 to 30 microns, and the performance is stable. The actual picture of the microcrystalline glass obtained in this embodiment is as follows Figure 2 As shown, the performance analysis table of the microcrystalline glass prepared in this embodiment is shown in Table 2.

[0072] Table 2 Performance analysis of glass-ceramic products

[0073]

[0074] Comparative Example 1

[0075] Compared with Example 1, this comparative example only increases the amount of phosphogypsum in the phosphogypsum-based mixed raw material, and adaptively adjusts the formula based on the change in the phosphogypsum content, while other conditions remain unchanged.

[0076] In this comparative example, the specific ratio of the phosphogypsum-based mixed raw materials is: phosphogypsum 50%, quartz sand 25%, soda ash 6%, sodium fluorosilicate 7%, feldspar 8%, and others (additives) 4%; among them, the main components of the phosphogypsum include: CaSO4 90%, S21%.

[0077] Melting: The phosphogypsum-based mixed raw materials are placed in a glass furnace and melted at 1450°C for 150 minutes to form a uniform glass melt. During this stage, calcium sulfate decomposes to produce SO2 gas, which is recovered in a flue gas recovery unit for other industrial uses.

[0078] Molding: The glass is hydraulically rolled into a plate through a calender to obtain a glass substrate. The calendering speed is 1m / min.

[0079] Heat treatment: The glass substrate is sent into a heat treatment kiln for microcrystallization treatment:

[0080] Nucleation treatment: heating to 800°C at 5°C / min and keeping at this temperature for 2 hours to promote the formation of glass nuclei.

[0081] The temperature was raised to 1100°C at a rate of 2°C / min and kept at that temperature for 1.5 hours to allow crystal growth.

[0082] Cooling treatment: After cooling, a glass plate is obtained. The cooling rate of the cooling treatment is 8°C / min. After cooling and taking out, the sample is glass-like, not microcrystalline glass.

[0083] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for producing glass-ceramics from phosphogypsum, characterized in that: Including steps: Obtaining a phosphogypsum-based mixed raw material, wherein the phosphogypsum-based mixed raw material comprises, by mass fraction, 30% to 45% of phosphogypsum, 20% to 40% of quartz sand, 5% to 10% of soda ash, 5% to 10% of sodium fluorosilicate, and 5% to 15% of feldspar; melting and shaping the phosphogypsum-based mixed raw material to obtain a glass substrate; The glass substrate is subjected to heat treatment to obtain glass-ceramics.

2. The method for producing glass-ceramics from phosphogypsum according to claim 1, characterized in that: The heat treatment includes a nucleation treatment and a crystallization treatment; Nucleation treatment: heating the glass substrate to 700-850° C. and keeping the temperature for 2-3 hours at a heating rate of 3-5° C. / min; Crystallization treatment: heating the glass substrate after the nucleation treatment to 1000-1100° C. and keeping the temperature for 1.5-2 hours; the heating rate is 1-2° C. / min.

3. The method for producing glass-ceramics from phosphogypsum according to claim 2, characterized in that: Also includes: The glass substrate after the crystallization treatment is cooled at a cooling rate of 5 to 10° C. / min.

4. The method for producing glass-ceramics from phosphogypsum according to claim 1, characterized in that: Calculated by mass fraction, the chemical composition of the phosphogypsum includes: CaSO4 70% to 95%, S16% to 25%.

5. The method for producing glass-ceramics from phosphogypsum according to claim 1, characterized in that: The melting and shaping of the phosphogypsum-based mixed raw materials to obtain the glass substrate includes: melting the phosphogypsum-based mixed raw materials into glass liquid at a melting temperature of 1300-1600° C., and the melting time is 150-200 minutes.

6. The method for producing glass-ceramics from phosphogypsum according to claim 5, characterized in that: The phosphogypsum-based mixed raw material is melted and formed to obtain a glass substrate, and the forming comprises: cooling the melted glass liquid to a viscosity of 10 4 ~10 5 After paving, the sheet is rolled into a plate at a rolling speed of 0.25 to 1 m / min.

7. The method for producing glass-ceramics from phosphogypsum according to any one of claims 1 to 6, characterized in that: The phosphogypsum-based mixed raw material further includes an additive for adjusting glass properties, and the mass percentage of the additive in the phosphogypsum-based mixed raw material is 3% to 10%.

8. A phosphogypsum-based mixed raw material, characterized in that: Calculated by mass fraction, the phosphogypsum-based mixed raw material includes: 30% to 45% of phosphogypsum, 20% to 40% of quartz sand, 5% to 10% of soda ash, 5% to 10% of sodium fluorosilicate, and 5% to 15% of feldspar.

9. A glass-ceramic prepared by the method for producing glass-ceramic from phosphogypsum according to any one of claims 1 to 7.

10. The glass-ceramics according to claim 9, characterized in that: The crystal size of the glass-ceramics is 1 to 30 microns, the bending strength of the glass-ceramics is not less than 95 MPa, and the impact toughness is not less than 2.5 KJ / M 2 , the thermal expansion coefficient is 5~8×10 -6 / ℃.

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