A method for producing microcrystalline glass fiber using granite saw mud

Abstract

The present invention belongs to the field of microcrystalline material preparation, and in particular to a method for producing microcrystalline glass fiber from granite saw mud. The method includes: drying and grinding granite saw mud to obtain granite saw mud dry powder, mixing granite saw mud dry powder, ulexite powder, borax powder, limestone powder, borax powder and soda ash powder according to a certain proportion, sending the mixed raw material powder into the molten pool in the heating furnace to heat and melt, and rapidly cooling by centrifugal spinning to obtain glassy microcrystalline glass fiber. The method provided by the present invention constructs a Na2O‑B2O3‑SiO2 ternary system by introducing a low-valent boron raw mineral containing B2O3, thereby effectively reducing the melting point and viscosity of the glass body and increasing the fluidity of the melt. At the same time, the introduction of boron makes the glass body have the characteristics of low-alkali borosilicate glass, and the produced microcrystalline glass fiber has a small linear expansion coefficient and better thermal stability.

Description

Technical Field

[0001] The invention belongs to the field of microcrystalline material preparation, and particularly relates to a method for producing microcrystalline glass fiber by using granite saw mud. Background Art

[0002] Granite is composed of feldspar, quartz, and mica, with silica being the primary component, accounting for approximately 60%-75%. Granite sawdust is a mixture of stone dust and water produced during the granite cutting process. The chemical composition of dried granite sawdust is essentially the same as that of the original granite. For example, the composition of a particular granite sawdust is as follows: approximately 75% SiO2, approximately 12% Al2O3, approximately 1.1% CaO, approximately 0.1% MgO, approximately 4% K2O, approximately 4% Na2O, and approximately 0.3-0.5% Fe2O 3、 TiO2, etc.

[0003] The industry generally believes that building materials are the largest and final application area for solid waste. Both granite sawdust and blast furnace slag are igneous high-silicon, high-aluminum industrial solid wastes. However, their compositions differ significantly. The combined content of SiO2 and Al2O3, Lewis acids, in granite sawdust is over 85%, while in blast furnace slag it is less than 65%. The combined content of alkali and alkaline earth metal oxides, Lewis bases, in granite sawdust is only about 10%, while in blast furnace slag it reaches 30% to 40%.

[0004] As Lewis acids, SiO2 and Al2O3 have high melting points of 1723℃ and 2060℃ respectively. Even if SiO2 and Al2O3 form a eutectic compound 3Al2O3·2SiO2, its melting temperature is still as high as 1545℃. Due to the large amount of limestone (CaCO3) and dolomite (CaCO3·MgCO3) added during blast furnace smelting, the content of Lewis bases CaO and MgO in blast furnace slag is greatly increased. Although the melting temperatures of CaO and MgO themselves are also very high, 2570℃ and 2800℃ respectively, the Lewis acid SiO2, Al2O3 and Lewis base are combined in appropriate proportions to form a compound with low melting point (<1400℃), low viscosity and good fluidity. Therefore, the blast furnace slag melt can be directly used to produce microcrystalline glass fiber.

[0005] On the other hand, blast furnace slag has high content of alkali metal and alkaline earth metal oxides, so it has hydraulic properties. Therefore, after ultra-fine grinding, blast furnace slag can be directly added to cement as a hydraulic cementitious material, or directly used in concrete production. Blast furnace slag is not only not industrial waste, but can also be sold directly at a very high price, and the social stock is very small.

[0006] However, granite mud has an unbalanced acid-alkaline ratio and a melting temperature exceeding 1600°C. The direct melting of granite mud to produce microcrystalline glass fiber is difficult and uneconomical. Furthermore, granite mud has a low alkalinity (especially calcium content), making it inherently non-hydraulic and unsuitable for direct use as a hydraulic binder in building materials production.

[0007] Since granite saw mud cannot be directly used as a hydraulic cementitious material in the production of building materials, it cannot be effectively utilized in a simple and low-cost way. The process of melt-melting to produce microcrystalline glass fiber is very difficult and not very economical, resulting in the inability of existing technology to effectively absorb granite saw mud, resulting in large amounts of granite saw mud piling up, seriously affecting the environment.

[0008] Developing a simple, low-cost way to utilize granite saw mud is a practical way to solve the problem of large-scale accumulation of granite saw mud and eliminate its environmental impact. Summary of the Invention

[0009] In order to solve the above technical problems, the present invention provides a method for producing microcrystalline glass fiber using granite saw mud.

[0010] The present invention is achieved through the following technical solutions:

[0011] A method for producing microcrystalline glass fiber using granite saw mud comprises: drying and grinding the granite saw mud to obtain granite saw mud dry powder; mixing the granite saw mud dry powder, ulexite powder, magnesia borax powder, limestone powder, borax powder and soda ash powder in a certain proportion; feeding the mixed raw material powder into a molten pool in a heating furnace to heat and melt; and obtaining glassy microcrystalline glass fiber by centrifugal spinning.

[0012] Furthermore, according to the mass percentage, the addition ratio of each raw material is: granite sawdust dry powder 82-92wt%, ulexite powder 2-5wt%, borax powder 2-5wt%, limestone powder 1-3wt%, borax powder 0.5-2wt%, and soda ash powder 2-8wt%.

[0013] Furthermore, the particle sizes of the granite sawdust dry powder, the ulexite powder, the magnesite powder, the limestone powder, the borax powder and the soda ash powder are all greater than 20 meshes.

[0014] Furthermore, the melting point of the raw material powder is 900° C. to 1100° C., and the melting point of the raw material powder is adjusted between 900° C. and 1100° C. by controlling the ratio of each raw material in the raw material powder.

[0015] Furthermore, the temperature of the heating furnace molten pool is controlled at 1100°C to 1300°C.

[0016] Furthermore, the temperature of the molten pool in the heating furnace is 100 to 200° C. higher than the melting point of the raw material powder.

[0017] Furthermore, the mixed raw material powder is fed into a molten pool in a heating furnace for heating and melting, and glassy microcrystalline glass fibers are obtained by centrifugal spinning, which specifically includes:

[0018] A mixed powder of boron glass and soda glass is heated to form an initial molten pool in a heating furnace; or a finished microcrystalline glass fiber prepared from the raw material powder is ground into fine powder, and the fine powder is heated to form an initial molten pool;

[0019] The raw material powder is added to the initial molten pool of the heating furnace through the automatic feeding device. The raw material powder floats on the melt in the molten pool and melts into the melt through heat exchange with the melt.

[0020] The melt is discharged through an insulated pipe; the melt discharged from the insulated pipe drips onto a high-speed rotating horizontal disk and is thrown out into filaments by centrifugal force. The speed of the horizontal disk is controlled at 1500-3000 rpm; the filaments come into contact with the water-cooled wall or air and are quickly cooled and solidified. After collection, microcrystalline glass fibers are obtained.

[0021] Among them, regarding the rotation speed of the horizontal disc, if the rotation speed is extremely fast, the melt is thrown out as extremely fine droplets, which become ultrafine powder after rapid cooling; if the rotation speed is slow, the melt is thrown out as a thicker liquid flow, which becomes glass filaments after rapid cooling, which are easy to break and difficult to aggregate; if the suitable rotation speed (1500-3000 rpm) is slow, the melt is thrown out as a thinner liquid flow, which becomes glass fibers after rapid cooling, which are not easy to break and aggregate into cotton. Therefore, in the present invention, the rotation speed of the horizontal disc needs to be strictly controlled.

[0022] Furthermore, when a mixed powder of boron glass and soda glass is heated to form an initial molten pool in a heating furnace, the soda glass and boron glass are mixed in a ratio of 3:1 and ground to a size of more than 20 mesh, and then added to the heating furnace and heated until a molten pool is formed.

[0023] Beneficial technical effects of the present invention:

[0024] The method provided by the present invention introduces a boron-containing raw mineral containing B2O3 to construct a Na2O-B2O3-SiO2 ternary system, thereby effectively reducing the melting point and viscosity of the glass body and increasing the fluidity of the melt. At the same time, the introduction of boron makes the glass body have the characteristics of low-alkali borosilicate glass, and the produced microcrystalline glass fiber has a small linear expansion coefficient and better thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for producing microcrystalline glass fiber using granite saw mud in an embodiment of the present invention;

[0026] Figure 2 This is the phase diagram of Na2O-SiO2 system. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] On the contrary, the present invention covers any alternatives, modifications, equivalents, and solutions that fall within the spirit and scope of the present invention as defined by the claims. Furthermore, to facilitate a better understanding of the present invention, certain specific details are described in detail below in the detailed description of the present invention. Those skilled in the art will be able to fully understand the present invention without these details.

[0029] Microcrystalline glass fiber is obtained by fiberizing molten glassy material. After further processing, microcrystalline glass fiber can be made into a series of products with multiple uses, which can be widely used in the fields of construction, chemical industry, electronics, electricity, metallurgy, energy, transportation, etc. For example, it can produce lightweight and heat-insulating wall materials, and make boards, felts, etc. as heat-insulating, heat-insulating, and sound-absorbing materials. Usually, molten glassy materials are mainly silicates, which have many advantages such as being non-flammable, non-toxic, corrosion-resistant, low in bulk density, low in thermal conductivity, strong in chemical stability, and low in moisture absorption. A typical silicate is sodium silicate. From Figure 1 From the phase diagram of the Na2O-SiO2 system, it can be seen that the lowest melting point temperature is 1073℃, corresponding to the ratio of Na2O to SiO2: 27:73 (wt%).

[0030] In granite mud, the ratio of Na₂O (including K₂O) to SiO₂ is 8:75 (wt%), which after normalization is 9.8:90.2, corresponding to a melting point exceeding 1650°C. This indicates that producing glassy materials from granite mud directly through the melting process, due to its high melting temperature, not only increases production costs but also presents significant technical challenges. Lowering the melting temperature is essential for producing glassy materials from granite mud. Simply adding alkali metals and alkaline earth metals to lower the melting temperature can achieve glassy materials from granite mud. However, the binary system formed by these metals and alkaline earth metals with silica requires a high proportion of alkaline material, and the large addition of these metals inevitably increases production costs.

[0031] The present invention provides a method for producing microcrystalline glass fiber using granite saw mud, which is a simple and low-cost way to utilize granite saw mud; Figure 1As shown, the method includes: drying and grinding granite saw mud to obtain granite saw mud dry powder, mixing the granite saw mud dry powder, ulexite powder, borax powder, limestone powder, borax powder and soda ash powder in a certain proportion, sending the mixed raw material powder into a molten pool in a heating furnace for heating and melting, and obtaining glassy microcrystalline glass fiber by centrifugal spinning.

[0032] In this embodiment, the addition ratio of each raw material is as follows: granite sawdust dry powder 82-92wt%, ulexite powder 2-5wt%, magnesia borax powder 2-5wt%, limestone powder 1-3wt%, borax powder 0.5-2wt%, and soda ash powder 2-8wt%.

[0033] In the present invention, the granite saw mud used has the following components: SiO2 70-80%, Al2O3 10-14%, CaO 1-2%, MgO 0.1-0.2%, K2O 2-6%, Na2O 2-6%, and 0.3-0.5% of Fe2O3, TiO2, etc.

[0034] Ulexanite (NaCa[B3B2O7(OH)4]·6H2O) is a common borate that is produced in arid areas and is mainly distributed in salt lakes in South America and the Qinghai-Tibet Plateau in my country.

[0035] Magnesium borate (Mg2[B2O4(OH)](OH)) is also a borate mineral. It is the main mineral for extracting industrial boron. Magnesium borate is generally associated with minerals such as magnetite.

[0036] Limestone (CaCO3) is a common carbonate mineral that is widely found in the earth's crust.

[0037] Borax (Na2B4O7), a commercially available boron salt supplied in bulk.

[0038] Soda ash (Na2CO3), a commercially available sodium salt supplied in bulk.

[0039] In this embodiment, the particle sizes of the granite sawdust dry powder, the ulexite powder, the magnesite powder, the limestone powder, the borax powder and the soda ash powder are all larger than 20 meshes.

[0040] In this embodiment, the melting point of the raw material powder is 900°C to 1100°C, and the melting point of the raw material powder is adjusted between 900°C and 1100°C by controlling the ratio of the raw materials in the raw material powder. The specific method is as follows: based on the composition of granite sawdust, ulexite, and borax, the specific ratios of granite sawdust, ulexite, borax, limestone, soda ash, and borax are determined; if necessary, the raw materials can be dried, ground, and mixed in the laboratory according to the set ratios, heated to above 1600°C in a high-temperature furnace to form a melt, cooled, crushed, ground, and mixed to ensure uniformity, and the melting point of the mixture is determined to ensure consistency with the set melting point of the melt. If there is any deviation, adjustments can be made.

[0041] The present invention lowers the melting temperature to 900°C to 1100°C due to the following technical principle: by adding ulexite powder and boraxite powder, B2O3 is introduced into the Na2O-SiO2 system, creating a Na2O-B2O3-SiO2 ternary system. This effectively lowers the melting point and viscosity of the glass, increasing the fluidity of the melt. Furthermore, the introduction of boron imparts the characteristics of low-alkali borosilicate glass, resulting in a low linear expansion coefficient and improved thermal stability for the produced glass-ceramic fibers. Furthermore, due to the high price of commercially available borax (Na2B4O7), the direct addition of borax inevitably increases the cost of raw materials, reducing the economic efficiency of granite sawdust disposal. Therefore, the present invention proposes to replace borax with low-priced boron-containing raw minerals (ulexite powder and forschite powder) to construct a Na2O-B2O3-SiO2 ternary molten salt system. While effectively lowering the melting point of the melt and controlling the production process cost, the boron composition is fine-tuned by adding low-priced boron-containing raw minerals supplemented by a small amount of borax. On the premise of ensuring that the melting point, viscosity, fluidity, linear expansion coefficient of microcrystalline glass fiber and other indicators of the glass body meet the requirements of the finished product, in order to reduce costs, low-priced minerals or industrial products such as limestone and soda ash that are relatively boron-containing compounds are not added, so that the raw material cost is effectively controlled, the overall process cost is controllable, and the economic efficiency is greatly improved.

[0042] In this embodiment, the temperature of the molten pool in the heating furnace is controlled at 1100° C. to 1300° C. In this embodiment, the temperature of the molten pool in the heating furnace is 100-200° C. higher than the melting point of the raw material powder.

[0043] In this embodiment, the mixed raw material powder is fed into a molten pool in a heating furnace to be heated and melted, and a glassy microcrystalline glass fiber is obtained by centrifugal spinning, which specifically includes:

[0044] A mixed powder of boron glass and soda glass is heated to form an initial molten pool in a heating furnace; or a finished microcrystalline glass fiber prepared from the raw material powder is ground into fine powder, and the fine powder is heated to form an initial molten pool;

[0045] The raw material powder is added to the initial molten pool of the heating furnace through the automatic feeding device. The raw material powder floats on the melt in the molten pool and melts into the melt through heat exchange with the melt.

[0046] The melt is discharged through an insulated pipe; the melt discharged from the insulated pipe drips onto a high-speed rotating horizontal disc and is thrown out into filaments by centrifugal force. The filaments are quickly cooled and solidified when in contact with air, and microcrystalline glass fibers are obtained after collection.

[0047] Specifically, the added raw material powder floats on the melt, increasing the pressure of the molten pool. The bottom of the molten pool is connected to a melt discharge pipe, which is an inverted U-shaped pipe. The pressure exerted by the raw material powder causes the melt to pass over the top of the inverted U-shape and the melt is discharged from the molten pool.

[0048] Specifically, after the initial molten pool is formed, the molten pool volume is maintained, the heating power of the heating furnace and the speed of adding the mixed powder are adjusted to control the balance of the molten pool volume, the amount of mixed powder accumulated on the upper part of the molten pool, and the discharge speed of the melt.

[0049] In this embodiment, when a mixed powder of boron glass and soda glass is heated to form an initial molten pool in a heating furnace, soda glass and boron glass are mixed in a ratio of 3:1 and ground to a size of 20 mesh or larger, and then added to the heating furnace, and heating is started until a molten pool is formed.

[0050] The following is an example of preparing microcrystalline glass fiber using a granite sawdust dry powder as raw material to illustrate the preparation method: The granite sawdust dry powder is composed of the following:

[0051]

[0052] Mix the granite sawdust dry powder in the above table with ulexite powder, magnesia borax powder, limestone powder, borax powder and soda ash powder in a certain proportion. The mixing proportions are shown in the following table:

[0053]

[0054] Initial melt pool preparation: Set the melt pool depth to 500mm, the melt pool diameter to 1500mm, and the melt pool volume to 0.88 cubic meters. Crush, mix, and grind 1855kg of soda glass and 618kg of borosilicate glass to a 20-mesh size or higher. Add the materials to the melt pool, piling them approximately 1000mm high for a designed melt pool height of 1500mm. After adding the materials, flatten the surface, activate the melt pool heating system, and heat until the materials melt and the temperature reaches 1200°C. This completes the initial melt pool preparation.

[0055] Adding mixed materials: Add the proportioned raw material powder into the smelting pool and flatten the surface of the material until the total material height in the smelting pool is 1000mm. Then add the material at a uniform speed according to the set production capacity and flatten the surface of the material.

[0056] Production control: If the output of microcrystalline glass fiber is set at 3.33 tons / hour, the heating power of the heating furnace is about 1300KW. The output of microcrystalline glass fiber is controlled to be stable. When the molten pool height decreases, the heating power is increased, and when the molten pool height increases, the heating power is reduced.

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for producing microcrystalline glass fiber using granite saw mud, characterized in that: The method comprises: drying and grinding granite sawdust to obtain granite sawdust dry powder; mixing the granite sawdust dry powder, ulexite powder, magnesia borax powder, limestone powder, borax powder and soda ash powder in a certain proportion; feeding the mixed raw material powder into a molten pool in a heating furnace to heat and melt; and rapidly cooling the mixed raw material powder by centrifugal spinning to obtain glassy microcrystalline glass fibers; The melting point of the raw material powder is 900°C to 1100°C; and the melting point of the raw material powder is adjusted between 900°C and 1100°C by controlling the ratio of each raw material in the raw material powder; the temperature of the heating furnace molten pool is controlled at 1000°C to 1300°C; According to the mass percentage, the addition ratio of each raw material is: granite sawdust dry powder 82-92%wt, ulexite powder 2-5wt%, magnesia borax powder 2-5wt%, limestone powder 1-3wt%, borax powder 0.5-2wt%, soda ash powder 2-8wt%; The mixed raw material powder is fed into the molten pool in the heating furnace to be heated and melted, and then centrifugally spun and rapidly cooled to obtain glassy microcrystalline glass fiber. Specifically, the process includes: A mixed powder of boron glass and soda glass is heated to form an initial molten pool in a heating furnace; or a finished microcrystalline glass fiber prepared from the raw material powder is ground into fine powder, and the fine powder is heated to form an initial molten pool; The raw material powder is added to the initial molten pool of the heating furnace through the automatic feeding device. The raw material powder floats on the melt in the molten pool and melts into the melt through heat exchange with the melt. The melt is discharged through an insulated pipe; the melt discharged from the insulated pipe drips onto a high-speed rotating horizontal disk and is thrown out into filaments by centrifugal force. The speed of the horizontal disk is controlled at 1500-3000 rpm; the filaments come into contact with air or water-cooled walls and are quickly cooled and solidified. After collection, microcrystalline glass fibers are obtained.

2. The method for producing microcrystalline glass fiber from granite saw mud according to claim 1, characterized in that: The particle sizes of the granite sawdust dry powder, the ulexite powder, the magnesite powder, the limestone powder, the borax powder and the soda ash powder are all less than 20 meshes.

3. The method for producing microcrystalline glass fiber from granite saw mud according to claim 1, characterized in that: The temperature of the molten pool in the heating furnace is 100°C to 200°C higher than the melting point of the raw material powder.

4. The method for producing microcrystalline glass fiber using granite saw mud according to claim 3, characterized in that: When a mixed powder of boron glass and soda glass is heated to form an initial molten pool in a heating furnace, the soda glass and boron glass are mixed in a mass ratio of 3:1 and ground to a size of more than 20 mesh, and then added to the heating furnace and heated until a molten pool is formed.

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