Modified basalt fiber YB-2400 and preparation method thereof

Abstract

The application belongs to the technical field of fiber preparation, and particularly relates to a modified basalt fiber YB-2400 and a preparation method thereof, which comprises the following steps: basalt raw material crushing and screening, blending with silicate glass, modification after removing iron oxides through high-temperature reduction and magnetic separation, high-temperature melting in a melting pool, homogenization in a homogenization pool, high-speed wire drawing, and surface infiltration treatment; the basalt particles, silicate fiber powder and modifiers are arranged in the raw material, and iron removal treatment, homogenization treatment, high-speed wire drawing, surface infiltration and other treatment steps are arranged, so that the iron oxides are effectively removed; in combination with blending modification and surface treatment, the mechanical strength, elastic modulus, toughness and corrosion resistance of the basalt fiber are significantly improved; the preparation process is simple and can be continuously produced, and the cost is controllable; the modified continuous basalt fiber prepared by the application has excellent performance, can be widely applied to high-end building materials, automobile parts, corrosion-resistant pipes, special composite materials and other fields, and has good industrialization popularization prospect.

Description

Technical Field

[0001] This invention relates to the field of fiber preparation technology, and in particular to a modified basalt fiber YB-2400 and its preparation method. Background Technology

[0002] Commonly used high-strength fibers include glass fiber, carbon fiber, basalt fiber, and aramid fiber. Glass fiber is generally obtained by drawing molten silicate glass into fibers. Glass fiber is an inorganic non-metallic material with advantages such as good insulation, strong heat resistance, good corrosion resistance, and high mechanical strength. However, it also has disadvantages such as being easily broken, not wear-resistant, and not resistant to bending. Current researchers have modified glass fiber to improve its fragility, but the results need further improvement. Carbon fiber and aramid fiber have many advantages, but their cost is very high.

[0003] Basalt fiber is an inorganic, environmentally friendly, high-performance fiber material made from natural basalt through high-temperature melting and drawing. It boasts numerous advantages, including excellent high-temperature performance, high mechanical strength, good chemical stability, and being green and non-toxic. It has broad application prospects in construction, transportation, aerospace, and military industries. However, the composition of basalt varies naturally between different batches or mining areas, directly affecting the stability of the final fiber performance. Furthermore, natural basalt raw materials often contain black iron oxides (such as ferrous oxide and ferric oxide), which affect the color and mechanical properties of basalt fibers, leading to brittleness and reduced strength. Effectively removing these black iron oxides would first provide a natural white or light-colored base for the fiber, making it easier to dye in various colors and expanding its applications in consumer goods and architectural decoration. Secondly, it might help improve the fiber's electrical insulation and high-temperature oxidation resistance (because iron ions are active sites for conductivity and catalysis under certain conditions). These technical issues require further research.

[0004] To address the aforementioned issues, existing technologies have developed several methods for modifying basalt fibers and silicate glass fibers separately, such as by adding different modifiers or blending with other materials. However, most of these methods suffer from poor modification effects, complex processes, and high costs, and fail to effectively remove the adverse effects of ferric oxide and other substances in the raw materials on fiber properties.

[0005] Chinese invention patent application CN121226811A discloses a method for preparing a composite material of basalt fiber with siloxane-benzoxazine interface modification. This method involves modifying basalt to obtain a benzene ring structure, constructing a robust cross-linked network, and building a more solid interface. However, this technical solution only modifies the basalt fiber individually, and the strengthening effect needs further improvement.

[0006] Researchers have also studied the composite of basalt fiber with other fibers. Chinese invention patent application CN121179589A discloses a method for preparing a basalt fiber hybrid woven impact-resistant high load-bearing composite material. The method involves forming a preform by premixing and combing basalt fiber with auxiliary reinforcing fiber, and then forming the composite material by hot pressing. However, since this technical solution only involves weaving with other fibers after molding, the synergistic effect between the two is not obvious.

[0007] Therefore, there is an urgent need to develop a technical solution that can eliminate the shortcomings of basalt fiber and obtain high-strength, high-toughness, and low-cost fiber. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a method for preparing modified continuous basalt fiber. The method involves crushing and screening basalt raw materials, blending them with silicate glass, adding a YB-2400 modifier, removing iron oxides, and then performing melting, homogenization, high-speed drawing, and surface wetting treatments to obtain high-performance continuous modified basalt fiber. This method solves the technical problems of poor performance and ineffective modification in existing basalt fibers. YB-2400 is the fiber grade.

[0009] The present invention adopts the following technical solution: A method for preparing modified basalt fiber includes the following steps: (1) Basalt raw material pretreatment: After the basalt raw material is crushed by a crushing device, it is graded and screened by a screening device to obtain uniform basalt particles with an average particle size of 0.2~0.8mm.

[0010] (2) Raw material blending: The basalt particles obtained in step (1) are blended with silicate glass powder and placed together in a mixing device and stirred until they are evenly mixed to obtain a mixed raw material.

[0011] (3) Iron removal treatment: For the black iron oxide contained in the mixed raw materials, a high temperature reduction-magnetic separation combined iron removal method is used to remove the black iron oxide; the high temperature reduction process is carried out under the protection of an inert atmosphere, and the black ferrous oxide is reduced to magnetic grayish-white metallic iron by the reducing agent, while some low-valence iron oxides are oxidized into easily separable forms, and then the iron is removed by magnetic separation to obtain the magnetically separated mixture; then the modifier is added to the mixture, stirred evenly and the liquid is filtered out to obtain the iron-removed mixture.

[0012] (4) Melting treatment: The iron-removed mixture obtained in step (3) is fed into the melting pool and melted under high temperature conditions to obtain a molten material with uniform composition.

[0013] (5) Homogenization treatment: The molten material obtained in step (4) is sent to the homogenization tank for constant temperature homogenization treatment to eliminate bubbles and component segregation in the molten material, so that the composition and temperature of the molten material are uniform.

[0014] (6) Fiber drawing process: The molten material after homogenization in step (5) is introduced into the fiber drawing device and drawn at high speed through the stencil to form continuous primary basalt fibers.

[0015] (7) Surface wetting treatment: The primary basalt fibers formed in step (6) are continuously immersed in the wetting agent and removed after immersion for 8~15 seconds.

[0016] (8) Drying: After drying the basalt fibers after the impregnation treatment in step (7), continuous modified basalt fibers are obtained.

[0017] As a preferred option, in step (1), after crushing, the basalt particles are screened through a 20-80 mesh screen, and the particle size is controlled to be 0.2-0.8 mm.

[0018] Preferably, in step (2), the average particle size of the silicate glass powder is 0.1~1mm.

[0019] Preferably, the modifier in step (2) is one or more of the following: hydrochloric acid with a concentration of 5~20 vol.%, sulfuric acid with a concentration of 5~15 wt.%, nitric acid with a concentration of 10~18 vol.%, phosphoric acid with a concentration of 5~10 wt.%, or oxalic acid with a concentration of 0.1~0.5 mol / L. The amount of modifier added is such that the liquid-solid ratio is (3~6) L:1 kg, and the mixture is stirred evenly at a temperature of 25~60℃ for 20~50 min.

[0020] Preferably, the modifier in step (2) is one or more of NaOH, KOH, and Na2CO3 with a concentration of 8~15wt.% or 10~18wt.% or 5~10wt.% or 10wt.% or 10wt.% or 10wt.% or 10, and the amount of modifier added is such that the liquid-solid ratio is (4~10) L:1kg, and the mixture is stirred evenly at a temperature of 70~100℃ for 30~80min.

[0021] Preferably, the wetting agent in step (7) is a polyurethane-modified epoxy resin composition, which is a composition comprising 20-60 parts by weight of bisphenol A type epoxy resin, 15-45 parts by weight of hydroxyl-terminated polyurethane prepolymer, 5-25 parts by weight of curing agent, and 0.1-8 parts by weight of additives; the hydroxyl-terminated polyurethane prepolymer is generated by reacting oligomeric polyol with excess diisocyanate, and the end is a -NCO group; the curing agent is an amine curing agent and / or an anhydride curing agent; and the additives are organotin catalysts and / or tertiary amine catalysts.

[0022] Preferably, in step (2), the mass ratio of basalt particles to silicate glass powder is (70-90):(10-30).

[0023] Preferably, in step (1), the composition of the selected basalt raw material, by mass percentage of oxides, is as follows: SiO2: 45~52wt.%, Al2O3: 14~18wt.%, FeO and Fe2O3 total: 5~14wt.%, MgO: 5~12wt.%, CaO: 10~12wt.%, Na2O: 2~4wt.%, K2O: 0.5~2wt.%, TiO2: 1~3wt.%.

[0024] Preferably, in step (2), the silicate glass powder selected is, by mass percentage of oxides, 60-69% SiO2, 2-8 wt.% Al2O3, 10-19 wt.% CaO and 0-16 wt.% B2O3.

[0025] Preferably, in step (3), the specific parameters for the high-temperature reduction-magnetic separation combined impurity removal are as follows: the high-temperature reduction temperature is 800~1000℃, the reduction time is 30~60min, the inert atmosphere is argon or nitrogen, the reducing agent is carbon powder or carbon monoxide, and the amount of reducing agent added is 2~5wt.% of the mass of the mixed raw materials; the magnetic field strength of the magnetic separation process is 0.8~1.5T, and the magnetic separation time is 10~30min; the removal rate of black iron oxides is ≥88%.

[0026] Preferably, in step (4), the melting temperature is 1450~1550℃, the melting time is 2~4h, and the melting pool is protected by inert gas.

[0027] Preferably, in step (5), the homogenization temperature is 1400~1500℃, the homogenization time is 1~2h, and the homogenization process is continuously stirred at a stirring rate of 50-100r / min.

[0028] Preferably, in step (6), the wire drawing rate is 800~1500m / min, and the wire is drawn through a platinum-rhodium alloy stencil with a pore size of 5~20μm.

[0029] Preferably, in step (7), the immersion temperature is 50~80℃ and the immersion time is 5~15min.

[0030] Preferably, the drying in step (8) is as follows: after soaking, the product is dried at a temperature of 100~150℃ for 30~60min.

[0031] A modified basalt fiber, wherein the modified basalt fiber is prepared by the above preparation method.

[0032] The chemical composition of the modified basalt fiber, by mass percentage of oxides, includes: SiO2: 48~55%, Al2O3: 12~19%, CaO: 8~16%, MgO: 3~10%, Na2O+K2O: 2~5%, TiO2: 1~2%, MnO<0.5%, FeO+Fe2O3<0.5%, and unavoidable impurities.

[0033] The beneficial effects of this invention are: 1. This invention creatively achieves precise fine-tuning of the subsequent melt composition by blending basalt particles with silicate glass powder (combined with subsequent iron removal modification, melting, and homogenization treatments). This is equivalent to establishing a new optimized formula for the raw materials, ensuring that the main chemical components of the final product (especially SiO2 and Al2O3) remain stable within the optimal range. This effectively improves the consistency of the final product, providing a foundation for subsequent high-strength and high-toughness industrial applications. Through synergistic effects, it improves the fluidity of the basalt melt, enhances the fiber drawing performance, and significantly strengthens the mechanical strength and corrosion resistance of the fiber, thus expanding the application range of the fiber.

[0034] 2. This invention, under the premise of reasonably limiting the raw materials to modified basalt particles and silicate glass powder, specifically selects the basalt and silicate glass raw materials, especially employing a high-temperature reduction-magnetic separation combined with fine iron removal modification in the subsequent preparation process. Targeting the core characteristics of basalt raw materials—rich in iron oxides and dark in color—a high-temperature reduction reaction under an inert atmosphere reduces ferrous oxide and ferric oxide to magnetic grayish-white metallic iron. Simultaneously, some low-valent iron oxides are converted into easily separable forms. Combined with magnetic separation, efficient iron removal is achieved without excessively affecting other components. This process coarsely removes iron oxides, and then a modifier for fine iron removal is added. The addition of the modifier further removes iron on top of the high-temperature reduction-magnetic separation process, and because the front-end process removes low-valent iron... The oxides are transformed into easily separable forms. By subsequently adding specific modifiers (which reduce the reaction intensity between the modifier and iron oxides, making it easier to remove the iron oxides), the modifiers and the upstream process work synergistically, mutually promoting each other and improving the efficiency of iron oxide removal. The removal rate of black iron oxides is close to 98%, solving the problem of traditional processes where single magnetic separation is insufficient to remove non-magnetic ferrous oxide. This effectively avoids the adverse effects of iron oxides on fiber color and mechanical properties, providing a natural white or light-colored appearance for fiber products, making them easier to dye in various colors and expanding their applications in consumer goods, architectural decoration, and other fields. Furthermore, this may help improve the electrical insulation properties and high-temperature oxidation resistance of the fibers (because iron ions are active sites for conduction and catalysis under certain conditions); significantly improving the purity and quality stability of the fibers. Compared to other iron removal methods such as single acid dissolution or highly toxic complexes, this invention combines raw materials and subsequent melting processes, setting up specific iron removal processes between them. This offers high safety and eliminates the need for subsequent treatment of highly toxic products, making it more suitable for industrial production.

[0035] 3. This invention ensures the production of high-quality continuous fibers by optimizing the melting and drawing processes. The invention first sets up a high-temperature melting pool, ensuring efficient mixing of all raw materials in a molten state. More importantly, it adds a crucial step of "homogenization in a homogenization pool." This homogenization step ensures that the complex melt (basalt + glass + modifier) ​​is completely uniform at the microscopic level, avoiding technical problems such as weak points or easy breakage in the fibers due to localized component inhomogeneity. This invention specifically incorporates a "high-speed drawing" technical feature. By rationally setting specific raw materials and efficient homogenization at the front end, the high-speed drawing process further enhances the fiber's strength, diameter uniformity, and other mechanical properties. This achieves synergistic unity with the raw materials and the front and rear processes, resulting in high-strength, high-modulus, and high-toughness fiber products.

[0036] 4. This invention enhances the performance of the final product by incorporating a specific impregnation process after fiber drawing and using a specific impregnating agent. Since the strength of the fiber obtained after drawing is only its intrinsic strength, the interfacial bonding strength between the fiber and the resin matrix, achieved through the impregnation process, is crucial in determining the interlaminar shear strength, fatigue resistance, and other properties of the composite material. By using a specific impregnating agent (including a specific coupling agent and film-forming agent) tailored to the specific modified fiber of this invention, optimal impregnation and bonding effects in resins such as epoxy and unsaturated polyester are ensured.

[0037] 5. This invention, through the setting of specific preparation steps and the optimization of each process parameter, enables continuous production, resulting in high production efficiency, controllable costs, and easy industrial application. Furthermore, the obtained modified continuous basalt fiber possesses technical characteristics such as high strength, high modulus, and high toughness, and can be widely used in high-end building materials, automotive parts, corrosion-resistant pipes, and special composite materials, demonstrating promising market prospects. Attached Figure Description

[0038] Figure 1 This is a schematic flowchart of a method for preparing modified basalt fibers according to one embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0040] Example 1 This embodiment is used to illustrate, as... Figure 1 The method for preparing modified continuous basalt fibers according to the process shown includes the following steps: (1) Basalt raw material pretreatment: Basalt from the mining area was selected. The composition of the basalt was selected by the mass percentage of oxides as follows: SiO2: 48wt.%, Al2O3: 15.5wt.%, FeO and Fe2O3 total: 12wt.%, MgO: 8.5wt.%, CaO: 10.5wt.%, Na2O: 3wt.%, K2O: 1wt.%, TiO2: 1.5wt.%. After removing surface impurities, the material was fed into a crusher for crushing. The crushed material was screened through a 40-mesh sieve, and basalt particles with an average particle size of 0.5mm were selected.

[0041] (2) Raw material blending modification: Silicate glass powder was selected, and the selected silicate glass powder, by mass percentage of oxides, consisted of: 65% SiO2, 6.5 wt.% Al2O3, 16 wt.% CaO, and 12.5 wt.% B2O3. Basalt particles and silicate glass powder were placed in a mixer at a mass ratio of 80:20 and stirred at a rate of 200 r / min for 30 min until uniformly mixed to obtain a mixed raw material.

[0042] (3) Iron removal treatment: Under the inert atmosphere of nitrogen, the mixed raw materials obtained in step (2) are mixed with carbon powder and added to the heating furnace. The amount of carbon powder added is 3 wt.% of the mass of the mixed raw materials. Then, the mixture is heated to 950℃, reduced for 50 min, and then cooled. Then, magnetic separation is carried out under the condition of magnetic field strength of 1.2T for 20 min to roughly remove black iron oxides and obtain the magnetically separated mixture. Then, hydrochloric acid with a concentration of 18 vol.% is added to the mixture as a modifier. The amount of modifier added is such that the liquid-solid ratio is 5:1 (i.e., 5L:1kg). The mixture is stirred evenly at 55℃ for 50 min. Then, the mixture is filtered and the liquid is removed to obtain the filter material as the iron removal mixture.

[0043] (4) Melting treatment: The iron-removed mixture after iron removal is sent into the melting pool, argon gas is introduced for protection, the melting temperature is controlled at 1500℃, and the melting time is 3h to obtain molten material.

[0044] (5) Homogenization treatment: The molten material is fed into the homogenization tank, the homogenization temperature is controlled at 1450℃, and the mixture is stirred at a rate of 80r / min for 1.5h to complete the homogenization.

[0045] (6) Fiber drawing process: The homogenized molten material is drawn into fibers at high speed through a platinum-rhodium alloy spinneret with a spinneret aperture of 10 μm and a drawing rate of 1200 m / min to form primary fibers, which are continuously drawn out.

[0046] (7) Surface impregnation treatment: The continuously pulled primary fibers are immersed in an impregnation tank during the moving operation. The impregnation tank is provided with an impregnating agent consisting of a composition of 50 parts by weight of bisphenol A epoxy resin, 35 parts by weight of hydroxyl-terminated polyurethane prepolymer, 12 parts by weight of curing agent, and 3 parts by weight of additives. The hydroxyl-terminated polyurethane prepolymer is generated by reacting oligomeric polyol with excess diisocyanate, and the end is a -NCO group; the curing agent is an amine curing agent; and the additives are tertiary amine catalysts. The temperature of the impregnating agent is set to 60°C, and the continuously moving primary fibers continue to move in the impregnation tank and are kept in the impregnation tank for about 10 seconds.

[0047] (8) Drying: The modified basalt fiber was then dried at 120°C for 45 min to obtain continuous modified basalt fiber.

[0048] Example 2 This embodiment illustrates a method for preparing modified continuous basalt fibers with altered parameters compared to Example 1, comprising the following steps: (1) Basalt raw material pretreatment: Basalt from the mining area was selected. The composition of the basalt was selected by the mass percentage of oxides as follows: SiO2: 50wt.%, Al2O3: 16.5wt.%, FeO and Fe2O3 total: 9wt.%, MgO: 7wt.%, CaO: 11wt.%, Na2O: 2.5wt.%, K2O: 1.5wt.%, TiO2: 2.5wt.%. After removing surface impurities, the material was fed into a crusher for crushing. The crushed material was screened through a 60-mesh screen, and basalt particles with an average particle size of 0.3mm were selected.

[0049] (2) Raw material blending modification: Silicate glass powder was selected, and the selected silicate glass powder, by mass percentage of oxides, consisted of: 62% SiO2, 4 wt.% Al2O3, 18 wt.% CaO, and 16 wt.% B2O3. Basalt particles and silicate glass powder were placed in a mixer at a mass ratio of 75:25 and stirred at a rate of 190 r / min for 40 min until uniformly mixed to obtain a mixed raw material.

[0050] (3) Iron removal treatment: Under an inert nitrogen atmosphere, the mixed raw materials obtained in step (2) are mixed with carbon powder reducing agent and added to a heating furnace. The amount of carbon powder added is controlled at 4 wt.% of the mass of the mixed raw materials. Then, the mixture is heated to 850℃ and reduced for 60 min before cooling. Then, magnetic separation is performed under a magnetic field strength of 1.0T for 25 min to remove black iron oxides. After coarse removal of black iron oxides, the magnetically separated mixture is obtained. Then, 8 wt.% phosphoric acid is added to the mixture as a modifier. The amount of modifier added is such that the liquid-solid ratio is 6:1 (i.e., 6L:1kg). The mixture is stirred evenly at 56℃ for 50 min. Then, the mixture is filtered and the liquid is removed to obtain the filter overlay as the iron removal mixture.

[0051] (4) Melting treatment: The mixed raw materials after iron removal are sent into the melting pool, nitrogen gas is introduced for protection, the melting temperature is controlled at 1480℃, and the melting time is 2.5h to obtain molten material.

[0052] (5) Homogenization treatment: The molten material is fed into the homogenization tank, the homogenization temperature is controlled at 1420℃, and the mixture is stirred at a rate of 65r / min for 1.8h to complete the homogenization.

[0053] (6) Fiber drawing process: The homogenized molten material is drawn into fibers at high speed through a platinum-rhodium alloy spinneret with a spinneret aperture of 8μm and a drawing rate of 1000m / min to form primary fibers, which are continuously drawn out.

[0054] (7) Surface impregnation treatment: The continuously pulled primary fiber is immersed in the impregnation tank during the moving operation. The impregnation tank is filled with a composition of 45 parts by weight of bisphenol A epoxy resin, 38 parts by weight of hydroxyl-terminated polyurethane prepolymer, 13 parts by weight of curing agent and 4 parts by weight of additives as the impregnating agent. The temperature of the impregnating agent is set to 70°C. The continuously moving primary fiber continues to move in the impregnation tank and is kept in the impregnation tank for about 12 minutes.

[0055] (8) Drying: The modified basalt fiber was then dried at 135°C for 35 minutes to obtain continuous modified basalt fiber.

[0056] Example 3 This embodiment illustrates a method for preparing modified continuous basalt fibers with altered parameters compared to Example 1, comprising the following steps: (1) Basalt raw material pretreatment: Basalt from the mining area was selected. The composition of the basalt selected in this embodiment is the same as that in Example 1. After removing surface impurities, it was fed into a crusher for crushing. The crushed material was screened through a 30-mesh screen, and basalt particles with an average particle size of 0.6 mm were selected.

[0057] (2) Raw material blending modification: Silicate glass powder was selected. The silicate glass powder selected in this embodiment is the same as that in Example 2. Basalt particles and silicate glass powder were put into a mixer at a mass ratio of 85:15 and stirred at a speed of 180 r / min for 35 min until they were mixed evenly to obtain a mixed raw material.

[0058] (3) Iron removal treatment: Under the inert atmosphere of nitrogen, the mixed raw materials obtained in step (2) are mixed with carbon powder reducing agent and added to the heating furnace. The amount of carbon powder added is 2.5 wt.% of the mass of the mixed raw materials. Then, the mixture is heated to 920℃ and reduced for 45 min before cooling. Then, magnetic separation is performed under the condition of magnetic field strength of 1.4T for 15 min to remove black iron oxides and coarsely remove black iron oxides to obtain the magnetically separated mixture. Then, hydrochloric acid with a concentration of 16 vol.% is added to the mixture as a modifier. The amount of modifier added is such that the liquid-solid ratio is 5:1 (i.e., 5L:1kg). The mixture is stirred evenly at 58℃ for 48 min. Then, the mixture is filtered and the liquid is removed to obtain the filter material as the iron removal mixture.

[0059] (4) Melting treatment: The mixed raw materials after iron removal are sent into the melting pool, argon gas is introduced for protection, the melting temperature is controlled at 1520℃, and the melting time is 3.5h to obtain molten material.

[0060] (5) Homogenization treatment: The molten material is fed into the homogenization tank, the homogenization temperature is controlled at 1480℃, and the mixture is stirred at a rate of 90r / min for 1.2h to complete the homogenization.

[0061] (6) Fiber drawing process: The homogenized molten material is drawn into fibers at high speed through a platinum-rhodium alloy spinneret with a spinneret aperture of 15μm and a drawing rate of 1300m / min to form primary fibers, which are continuously drawn out.

[0062] (7) Surface impregnation treatment: The continuously pulled primary fiber is immersed in the impregnation tank during the moving operation. The impregnation tank is filled with a composition of 46 parts by weight of bisphenol A epoxy resin, 38 parts by weight of hydroxyl-terminated polyurethane prepolymer, 12 parts by weight of curing agent and 4 parts by weight of additives as the impregnating agent. The temperature of the impregnating agent is set to 55°C. The continuously moving primary fiber continues to move in the impregnation tank and is kept in the impregnation tank for about 8 minutes.

[0063] (8) Drying: The modified basalt fiber was then dried at 110°C for 50 min to obtain continuous modified basalt fiber.

[0064] The modified continuous basalt fibers prepared in Examples 1-3 were tested for performance. The results showed that the iron oxide content in the fiber was less than 0.1%, the tensile strength could reach 4500-5000 MPa, the elastic modulus could reach 95-105 GPa, and the mass loss rate after soaking in an alkaline environment for 72 hours was less than 2%.

[0065] Comparative Example 1 This comparative example is used to show comparative test data for pure basalt fibers. In this comparative example, the basalt fiber particles from Example 1 were directly subjected to melting, homogenization, drawing, and drying processes. The parameters for each step were the same as those in Example 1, and the results are shown in Table 1.

[0066] Comparative Example 2 This comparative example is used to illustrate comparative test data for ordinary glass fibers. In this comparative example, the silicate fiber powder from Example 1 was directly subjected to melt treatment, homogenization treatment, fiber drawing treatment, and drying treatment. The parameters for each step were the same as those in Example 1, and the results are shown in Table 1. Table 1 is a comparison table of various indicators between Example 1 and Comparative Examples 1 and 2.

[0067] Table 1 Comparison Dimensions Comparative Example 1 Comparative Example 2 Example 1 Raw material costs higher lowest medium to low Performance stability lower high high Overall performance excellent good Superior-Special Grade (iron oxide content less than 0.1%, tensile strength up to 4850MPa, elastic modulus up to 102GPa, mass loss rate less than 2% after soaking in alkaline environment for 72 hours) Process adaptability middle high Medium and high Functional scalability Low middle high As shown in Table 1, the pure basalt fiber of Comparative Example 1 relies on a single high-quality ore source, resulting in large cost fluctuations and a relatively high overall cost. Its performance stability is also relatively low due to batch-to-batch ore influence. Although it possesses comprehensive properties such as temperature and corrosion resistance and a moderate elastic modulus, it requires a high drawing temperature, placing high demands on the kiln and resulting in moderate process adaptability. Furthermore, its naturally dark color makes it difficult to color, leading to poor functional expansion. In contrast, the glass fiber of Comparative Example 2 has the lowest cost due to standardized raw materials and large-scale production, achieving high performance stability. However, while it has high strength, its elastic modulus and temperature resistance are poor, resulting in the lowest overall performance among the three. Its mature process allows for high process adaptability and colorability, leading to greater functional expansion. In short, both Comparative Examples 1 and 2 have certain advantages but also disadvantages. As shown in Table 1, Example 1 of the present invention reduces costs by blending high-cost basalt with very low-cost silicate membranes. While not as cost-effective as glass fiber, standardized blending and modification result in high performance stability. Most importantly, while retaining the temperature and corrosion resistance advantages of basalt, the strength, modulus, and toughness are optimized through modification, achieving optimal overall performance. Modification optimizes melting and drawing processes, improving process adaptability. Furthermore, compared to basalt fiber, the present invention achieves easier coloring and controllable appearance through iron removal, resulting in high functional scalability.

[0068] Comparative Example 3 This comparative example is used to demonstrate a comparative test without the addition of silicate glass fiber powder. The other settings in this comparative example are the same as in Example 1, except that silicate glass powder was not added in step (2). Testing of the final fiber revealed that the performance parameters were basically the same as in Example 1. However, due to the significantly higher cost of basalt fiber compared to silicate glass fiber, the cost increased substantially despite minimal changes in performance.

[0069] Comparative Example 4 This comparative example is used to demonstrate a comparative experiment without the high-temperature reduction-magnetic separation combined iron removal method step. The other settings of this comparative example are the same as those of Example 1, except that the high-temperature reduction-magnetic separation combined iron removal method step is not set in step (3), but hydrochloric acid modifier is directly added. The other settings are exactly the same as those of Example 1. Testing of the final fiber revealed an iron oxide content of 1.9% and a tensile strength of 4520 MPa. This is because the iron oxides in the basalt raw material have complex forms, including FeO and Fe2O3, which are easily soluble in hydrochloric acid, as well as Fe3O4 (magnetic iron oxide), which is insoluble in hydrochloric acid, and iron impurities encapsulated in the aluminosilicate lattice. The core function of the high-temperature reduction-magnetic separation in Example 1 is to reduce the insoluble Fe3O4 and lattice-encapsulated iron to easily separable elemental iron or magnetic oxides under high-temperature conditions, and then efficiently separate them through magnetic separation, making subsequent fine iron removal with hydrochloric acid easier. After removing this step, under the condition of retaining the fine iron removal parameters of Example 1, it is impossible to effectively dissolve Fe3O4 and lattice-encapsulated iron, and only some easily soluble iron oxides can be removed, resulting in a significant increase in the iron oxide content in the final fiber. That is, the two-stage iron removal is closely coordinated. Meanwhile, the absence of the high-temperature reduction-magnetic separation combined iron removal step not only reduces the iron removal effect but also affects the tensile strength. This is because excessive iron oxides disrupt the amorphous network structure inside the fiber. Iron oxides (especially Fe2O3 and Fe3O4) are difficult to fully integrate into the SiO2-Al2O3 amorphous network during melting and instead disperse as tiny particles within the fiber, becoming stress concentration points. These iron oxide particles have extremely weak bonding with the fiber matrix, easily generating microcracks at the particle-matrix interface under stress, leading to fiber breakage. Furthermore, the increased iron oxide content reduces the relative proportion of core strength components such as SiO2 and Al2O3, further weakening the density of the network structure, thus causing a decrease in tensile strength compared to Example 1. This further demonstrates the strong synergistic effect between the steps of this invention.

[0070] Comparative Example 5 This comparative example is used to demonstrate a comparative test without homogenization. The other settings in this comparative example are the same as in Example 1, except that step (5) is omitted. Instead, the molten material from step (4) is directly placed into the drawing device for step (6). The other settings are identical to those in Example 1. Testing of the final fiber revealed a significant decrease in tensile strength to approximately 3200 MPa and an elastic modulus of 85 GPa, a marked decrease compared to Example 1. This is mainly due to the uneven composition and structure of the melt, resulting in numerous defects within the fiber. The core function of the homogenization step is to eliminate component segregation (such as excessively high or low concentrations of SiO2 and Al2O3) and temperature gradients in the melt through stirring and heat preservation, forming a uniformly composed amorphous melt. The modified comparative ratio, compared to Example 1, removes the basalt and silicate glass. This leaves behind tiny, incompletely fused regions of basalt and silicate glass in the melt, resulting in defects such as "compositional delamination," "microcracks," and "pores" inside the fiber after drawing. These internal defects become stress concentration points, making the fiber prone to fracture under stress, leading to a 1000-2000 MPa decrease in tensile strength compared to the original solution, and a significantly increased range of strength fluctuations. Furthermore, the unhomogenized melt may contain tiny solid particles (incompletely molten raw materials), which can form protrusions or pits on the fiber surface during drawing, further reducing the actual load-bearing capacity of the fiber. The homogenization step in Example 1 forms a uniform SiO2-Al2O3 amorphous network in the melt, which is the core guarantee for stable elastic modulus. Without a homogenization step, the fiber contains a mixed distribution of "rigid regions" (SiO2 and Al2O3 enriched regions) and "flexible regions" (Na2O and K2O enriched regions), resulting in an inability to uniformly transmit overall rigidity. Under stress, the flexible regions are prone to deformation, leading to a decrease in the fiber's overall resistance to deformation and a significant decrease in elastic modulus. At the same time, due to the large differences in rigidity among different regions, the elastic modulus fluctuates significantly at different locations, affecting the consistency of product performance.

[0071] Comparative Example 6 This comparative example is used to demonstrate a comparative test without surface wetting treatment. The other settings of this comparative example are the same as in Example 1, except that step (7) is omitted, and the fibers after high-speed drawing are used directly as the final product; the other settings are exactly the same as in Example 1. Testing of the final fiber revealed a tensile strength of 4680 MPa, and a mass loss rate of 9% after immersion in an alkaline environment for 72 hours (a significant increase in the loss rate). This is because in Example 1, the surface-wetting resin forms a continuous and dense protective film on the fiber surface. This film prevents the alkaline solution from directly contacting the fiber body, thereby significantly reducing the risk of fiber dissolution and corrosion. After removing the wetting step, the fiber body is directly exposed to the alkaline environment. The alkali metal oxides (Na2O+K2O) in the fiber will react directly with OH⁻, causing the fiber surface to dissolve. Furthermore, the alkaline solution will penetrate into the tiny defects inside the fiber (such as microcracks generated during the drawing process), accelerating the destruction of the internal network structure and causing fiber disintegration. Moreover, the specific wetting agent set in this invention can penetrate into the fine gaps, thereby achieving a certain strengthening effect. Without the wetting step, the strength will decrease to a certain extent, accompanied by "later attenuation" of fiber strength (tensile strength will decrease by 15%~25% after soaking). This proves that there is a close synergistic effect between the various steps of this invention.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing modified basalt fiber, characterized in that, Includes the following steps: (1) Basalt raw material pretreatment: After the basalt raw material is crushed by a crushing device, it is graded and screened by a screening device to obtain uniform basalt particles with an average particle size of 0.2~0.8mm. (2) Raw material blending: The basalt particles obtained in step (1) are blended with silicate glass powder and placed together in a mixing device and stirred until they are evenly mixed to obtain a mixed raw material; (3) Iron removal treatment: For the black iron oxide contained in the mixed raw materials, a high temperature reduction-magnetic separation combined iron removal method is used to remove the black iron oxide; the high temperature reduction process is carried out under the protection of an inert atmosphere, and the black ferrous oxide is reduced to magnetic grayish-white metallic iron by a reducing agent, while some low-valence iron oxides are oxidized into easily separable forms, and then the iron is removed by magnetic separation to obtain the magnetically separated mixture; then a modifier is added to the mixture, stirred evenly and the liquid is filtered out to obtain the iron-removed mixture; (4) Melting treatment: The iron-removed mixture obtained in step (3) is fed into the melting pool and melted under high temperature conditions to obtain a molten material with uniform composition; (5) Homogenization treatment: The molten material obtained in step (4) is sent to the homogenization tank for constant temperature homogenization treatment to eliminate bubbles and component segregation in the molten material, so that the composition and temperature of the molten material are uniform. (6) Fiber drawing process: The molten material after homogenization in step (5) is introduced into the fiber drawing device and subjected to high-speed fiber drawing through a stencil to form continuous primary basalt fibers; (7) Surface wetting treatment: The primary basalt fibers formed in step (6) are continuously immersed in the wetting agent and removed after immersion for 8~15 seconds; (8) Drying: After drying the basalt fibers after the impregnation treatment in step (7), continuous modified basalt fibers are obtained.

2. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (1), after crushing, the basalt particles are screened through a 20-80 mesh screen, and the particle size is controlled at 0.2-0.8 mm. In step (2), the average particle size of the silicate glass powder is 0.1~1mm; The modifier mentioned in step (3) is one or more of the following: hydrochloric acid with a concentration of 5~20 vol.%, sulfuric acid with a concentration of 5~15 wt.%, nitric acid with a concentration of 10~18 vol.%, phosphoric acid with a concentration of 5~10 wt.%, or oxalic acid with a concentration of 0.1~0.5 mol / L. The amount of modifier added is such that the liquid-solid ratio is (3~6) L: 1 kg, and the mixture is stirred evenly at a temperature of 25~60℃ for 20~50 min; or the modifier is one or more of the following: NaOH with a concentration of 8~15 wt.%, KOH with a concentration of 10~18 wt.%, or Na2CO3 with a concentration of 5~10 wt.%, and the mixture is stirred evenly at a temperature of 70~100℃ for 30~80 min. The impregnating agent in step (7) is a polyurethane modified epoxy resin composition, which is a composition comprising 20-60 parts by weight of bisphenol A type epoxy resin, 15-45 parts by weight of hydroxyl-terminated polyurethane prepolymer, 5-25 parts by weight of curing agent and 0.1-8 parts by weight of additives.

3. The method for preparing modified basalt fiber according to claim 1 or 2, characterized in that, In step (2), the mass ratio of basalt particles to silicate glass powder is (70-90):(10-30).

4. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (1), the composition of the selected basalt raw material, by mass percentage of oxides, is as follows: SiO2: 45~52 wt.%, Al2O3: 14~18 wt.%, FeO and Fe2O3 combined: 5~14 wt.%, MgO: 5~12 wt.%, CaO: 10~12 wt.%, Na2O: 2~4 wt.%, K2O: 0.5~2 wt.%, TiO2: 1~3 wt.%; In step (2), the selected silicate glass powder, by mass percentage of oxides, is: 60-69% SiO2, 2-8 wt.% Al2O3, 10-19 wt.% CaO and 0-16 wt.% B2O3.

5. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (3), the specific parameters for the high-temperature reduction-magnetic separation combined impurity removal are as follows: the high-temperature reduction temperature is 800~1000℃, the reduction time is 30~60min, the inert atmosphere is argon or nitrogen, the reducing agent is carbon powder or carbon monoxide, and the amount of reducing agent added is 2~5wt.% of the mass of the mixed raw materials; the magnetic field strength of the magnetic separation process is 0.8~1.5T, and the magnetic separation time is 10~30min.

6. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (4), the melting temperature is 1450~1550℃, the melting time is 2~4h, and inert gas is used for protection in the melting pool.

7. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (5), the homogenization temperature is 1400~1500℃, the homogenization time is 1~2h, and the homogenization process is continuously stirred at a stirring rate of 50-100r / min.

8. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (6), the wire drawing rate is 800~1500m / min, and the wire is drawn through a platinum-rhodium alloy stencil with a pore size of 5~20μm.

9. The method for preparing modified basalt fiber according to claim 1, characterized in that, In step (7), the immersion temperature is 50~80℃ and the immersion time is 5~15min; The drying in step (8) is as follows: after soaking, the product is dried at a temperature of 100~150℃ for 30~60min.

10. A modified basalt fiber, characterized in that, The modified basalt fiber is prepared by the preparation method described in any one of claims 1 to 8.

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