Refining slag system, preparation method and high-vacuum refining method

Abstract

The invention discloses a refining slag system, a preparation method and a high-vacuum refining method, and relates to the technical field of vacuum refining, and the refining slag system comprises the following components in percentage by mass: 60%-75% of SiO2, 8%-15% of Al2O3, 8%-15% of TiO2, 3%-8% of CaO, 1%-3% of Fe2O3, 2%-5% of Na2O and 1%-3% of K2O. According to the method, by means of the acidic high-viscosity slag formed with the high SiO2 content, on one hand, high-density HfO2 inclusions can be physically captured, and the HfO2 inclusions are prevented from returning to the alloy melt; and on the other hand, the slag can form a compact covering layer on the alloy liquid level, and volatilization loss of high-volatility elements such as aluminum under high vacuum (smaller than or equal to 0.1 Pa) is effectively inhibited. Meanwhile, TiO2 and Al2O3 in a slag system can be stably fixed in a silicon-oxygen network through structural solid solution.

Description

Technical Field

[0001] This application belongs to the field of high-temperature alloy regeneration technology, and specifically relates to a refining slag system, preparation method and high vacuum refining method. Background Technology

[0002] High-temperature alloys, due to their excellent high-temperature strength, oxidation resistance, and corrosion resistance, are widely used in key components such as aero-engines and gas turbines. With the upgrading of high-end equipment, a large amount of waste high-temperature alloy powder containing elements such as hafnium, titanium, and aluminum is generated. Because these powders contain highly reactive elements, they easily form stable oxide inclusions during traditional refining processes, which are difficult to remove effectively, leading to a decline in the performance of recycled alloys. Currently, common refining slag systems are mostly designed for conventional nickel-based or cobalt-based high-temperature recycled alloys, and their purification effect on special systems such as those rich in hafnium, titanium, or aluminum is limited. Summary of the Invention

[0003] In view of this, this application provides a refining slag system, a preparation method, and a high-vacuum refining method. The refining slag system has acidic and high viscosity properties. During the high-vacuum refining process, it can effectively reduce the volatilization of metal elements and oxide inclusions in hafnium-rich, titanium-rich, and aluminum-rich high-temperature alloy waste powders, thereby obtaining high-quality recycled high-temperature alloy materials.

[0004] In a first aspect, this application provides a refining slag system whose components, by mass fraction, include the following components: 60%~75% SiO2, 8%~15% Al2O3, 8%~15% TiO2, 3%~8% CaO, 1%~3% Fe2O3, 2%~5% Na2O, 1%~3% K2O, and unavoidable impurities in total not exceeding 0.5%.

[0005] Based on the refining slag system of this application, by adjusting the content of each component, the volatilization of metal elements and the content of oxide inclusions in hafnium-rich, titanium-rich, and aluminum-rich high-temperature alloy waste powder during high-vacuum refining (≤0.1 Pa) can be effectively reduced, thereby producing high-quality recycled high-temperature alloy materials. Specifically, this application increases the mass ratio of SiO2 to 60%~75%, giving the melt formed by the refining slag system high viscosity (≥2.0 Pa·s) under high-temperature conditions. This characteristic allows the melt to physically capture and retain heavy inclusions such as HfO2, and also forms a dense, stable, and well-covering slag layer on the surface of the high-temperature alloy material. During high-vacuum refining, this slag layer can form an efficient physical barrier on the surface of the high-temperature alloy material, improving the problem of aluminum vapor volatilization from the alloy melt surface into the vacuum environment, thereby reducing the loss of aluminum elements through volatilization. By combining a specific mass ratio of TiO2 and Al2O3 with a high mass ratio of SiO2, under an acidic environment with a high SiO2 content, Ti… 4+It enters and connects to the silicon-oxygen network in the form of [TiO4] tetrahedra, and is chemically fixed in the slag phase framework as a network intermediate; Al 3+ By replacing the [SiO4] tetrahedron with the [AlO4] tetrahedron as a network forming body, the [AlO4] tetrahedron directly participates in the construction of the melt structure, thus comprehensively achieving the stable solidification of Al2O3 inclusions. Furthermore, the specific amounts of Fe2O3, CaO, Na2O, and K2O in this application act as network modifiers, collectively regulating the melting point and viscosity of the refining slag system to a suitable range. Therefore, the synergistic effect of the components in the refining slag system of this application can improve the volatilization of metal elements and remove most of the impurities in the high-temperature alloy return material, which is beneficial to improving the quality of recycled high-temperature alloy materials and reducing the production cost of high-temperature alloy materials.

[0006] In some embodiments, the components, by mass fraction, include the following components: 65%~70% SiO2, 10%~12% Al2O3, 10%~12% TiO2, 4%~6% CaO, 1.5%~2.5% Fe2O3, 3%~4% Na2O, and 1.5%~2.5% K2O.

[0007] Further optimize the content of each component in the refining slag system to achieve synergistic effects among the components, improve the quality of recycled high-temperature alloy materials, and reduce the production cost of high-temperature alloy materials.

[0008] In some embodiments, the refining slag system is granular with an average particle size of no more than 8 mm. By further optimizing the shape and particle size of the refining slag system, the contact area between the refining slag system and the alloy powder is increased during the high-vacuum refining process, resulting in more uniform mixing before melting. This helps the refining slag system to quickly form a uniform slag coating on the surface of the recycled high-temperature alloy material.

[0009] Secondly, this application also provides a method for preparing the above-mentioned refining slag system, comprising the following steps: S1. Preparation of Mixing: Weigh each raw material according to its mass fraction to obtain the mixture; S2. Ball milling: The mixture is ball milled until it is homogeneous; S3. High-temperature melting: The ball-milled mixture is placed in a melting device for melting to form a homogeneous melt; S4. Cooling and Crushing: The melt is cooled to room temperature and then crushed to obtain granular refining slag.

[0010] In some implementations, the raw materials in step S1 satisfy at least one of the following conditions: (1) The purity of SiO2 is not less than 99%, and the average particle size is not greater than 1.5 mm; (2) The purity of TiO2 is not less than 99%, and the average particle size is not greater than 1.5 mm; (3) The purity of Fe2O3 is not less than 99%.

[0011] Further limiting the purity and particle size of raw materials during the preparation of the refining slag system controls the introduction of other unavoidable impurities from the source, ensuring that the refining capacity of the slag system is not interfered with by impurities; and controlling the particle size of SiO2 and TiO2 to ≤1.5mm is beneficial to achieve faster and more uniform mixing during ball milling, forming a more uniform melt.

[0012] In some embodiments, the melting temperature in step S3 is 1450℃~1550℃, the time is 40 min~50 min, and the kinetic viscosity of the refining slag system at the temperature is not less than 2.0 Pa·s.

[0013] By employing a refining slag system with high SiO2 content, the melt formed under high temperature conditions (1450℃~1550℃) exhibits high viscosity (≥2.0 Pa·s). This characteristic allows the melt to physically capture and retain heavy inclusions such as HfO2, and also forms a dense, stable, and well-covering slag layer on the surface of the high-temperature alloy material. This improves the problem of aluminum vapor volatilizing from the surface of the alloy melt into the vacuum environment, thereby reducing the loss of aluminum element volatilization.

[0014] Thirdly, this application also provides a high-vacuum refining method, using the above-mentioned refining slag system, and including the following steps: a. Mix the high-temperature alloy waste powder with the refining slag system and place it in a heating device; b. Place the heating device inside the vacuum furnace and evacuate to a vacuum level of ≤0.1 Pa; c. Raise the temperature inside the vacuum furnace to 1520℃~1580℃ at a uniform rate and hold it for refining for 90~150 minutes.

[0015] In some embodiments, in step a, the mass ratio of the refining slag system to the high-temperature alloy waste powder is (0.5~1.5):1; the high-temperature alloy waste powder includes hafnium, titanium and aluminum; based on the mass of the high-temperature alloy waste powder, the mass content of hafnium is 0.3%~3.0%, the mass content of titanium is 1.0%~5.0%, and the mass content of aluminum is 2.0%~6.0%.

[0016] In some embodiments, the waste powder of high-temperature alloy is waste powder of FGH97 high-temperature alloy with an average particle size of 50 μm to 200 μm.

[0017] By limiting the mass ratio of refined slag to high-temperature alloy waste powder, the molten refined slag can completely cover the surface of the high-temperature alloy material after melting, forming an effective physical barrier.

[0018] In some implementations, the oxygen content in the recycled high-temperature alloy material is no more than 10 ppm, and the aluminum recovery rate is no less than 95%. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The image shows the SEM characterization of the recycled high-temperature alloy material in Example 1 of this application after purification. Figure 2 The image shows the SEM-EDS characterization of inclusions in the recycled high-temperature alloy material in Comparative Example 1 of this application after purification. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] The inventors discovered that current common refining slag systems are mostly designed for conventional nickel-based or cobalt-based high-temperature recycled alloys, and their purification effect on special systems such as hafnium-rich, titanium-rich, and aluminum-rich alloys is limited. First, traditional slag systems have low viscosity and cannot effectively retain dense HfO2 inclusions. Second, under existing vacuum refining processes (typically with a vacuum level of 0.1 Pa to 1 Pa), aluminum in the recycled alloy will significantly volatilize due to high vapor pressure, leading to uncontrolled composition and reduced yield, which severely restricts the high-quality regeneration of aluminum-rich high-temperature alloys. Therefore, developing a dedicated refining slag system that can efficiently adsorb oxides of these elements and improve the cleanliness of high-temperature alloys has significant industrial application value.

[0023] To address the aforementioned technical problems, this application provides a refining slag system, a preparation method, and a high-vacuum refining method. The viscosity of the slag system is sufficient to retain heavy inclusions such as HfO2, and a dense slag layer is formed on the high-temperature alloy material. This improves the problem of aluminum vapor volatilizing from the surface of the alloy melt into the vacuum environment and enhances the quality of the recycled high-temperature alloy material.

[0024] Firstly, this application provides a refining slag system, the components of which, by mass fraction, include the following components: 60%~75% SiO2, 8%~15% Al2O3, 8%~15% TiO2, 3%~8% CaO, 1%~3% Fe2O3, 2%~5% Na2O, 1%~3% K2O, and unavoidable impurities totaling no more than 0.5%. It should be noted that these unavoidable impurities generally refer to those derived from the raw materials and present in small amounts.

[0025] Based on the refining slag system of this application, by adjusting the content of each component, the volatilization of metal elements and the content of oxide inclusions in hafnium-rich, titanium-rich, and aluminum-rich high-temperature alloy waste powder during high-vacuum refining (≤0.1 Pa) can be effectively reduced, thereby producing high-quality recycled high-temperature alloy materials. Specifically, this application increases the mass ratio of SiO2 to 60%~75%, giving the melt formed by the refining slag system high viscosity (≥2.0 Pa·s) under high-temperature conditions. This characteristic allows the melt to physically capture and retain heavy inclusions such as HfO2, and also forms a dense, stable, and well-covering slag layer on the surface of the high-temperature alloy material. During high-vacuum refining, this slag layer can form an efficient physical barrier on the surface of the high-temperature alloy material, improving the problem of aluminum vapor volatilization from the alloy melt surface into the vacuum environment, thereby reducing the loss of aluminum elements through volatilization. By combining a specific mass ratio of TiO2 and Al2O3 with a high mass ratio of SiO2, under an acidic environment with a high SiO2 content, Ti… 4+ It enters and connects to the silicon-oxygen network in the form of [TiO4] tetrahedra, and is chemically fixed in the slag phase framework as a network intermediate; Al 3+ By replacing the [SiO4] tetrahedron with the [AlO4] tetrahedron as a network forming body, the [AlO4] tetrahedron directly participates in the construction of the melt structure, thus comprehensively achieving the stable solidification of Al2O3 inclusions. Furthermore, the specific amounts of CaO, Na2O, and K2O in this application act as network modifiers, collectively regulating the melting point and viscosity of the refining slag system to a suitable range. Therefore, the synergistic effect of the components in the refining slag system of this application can improve the volatilization of metal elements and remove most of the impurities in the FGH97 alloy recycled material, which is beneficial to improving the quality of recycled high-temperature alloy materials and reducing the production cost of high-temperature alloy materials.

[0026] In some embodiments, the components, by mass fraction, include the following: 65%~70% SiO2, 10%~12% Al2O3, 10%~12% TiO2, 4%~6% CaO, 1.5%~2.5% Fe2O3, 3%~4% Na2O, and 1.5%~2.5% K2O. Further optimization of the component content of the refining slag system is achieved to realize the synergistic effect of each component, improve the quality of the recycled high-temperature alloy material, and reduce the production cost of the high-temperature alloy material.

[0027] In some embodiments, the refining slag system is granular with an average particle size of no more than 8 mm. It should be noted that the identical components in the refining slag system of this application are not aggregated together, but rather uniformly mixed. Therefore, when the refining slag system is granular, the composition of each particle is similar or even identical, containing SiO2, Al2O3, TiO2, CaO, Fe2O3, Na2O, K2O, etc. By further optimizing the shape and particle size of the refining slag system, the contact area between the refining slag system and the alloy powder is increased during the high-vacuum refining process, resulting in more uniform mixing before melting. This helps the refining slag system quickly form a uniform slag coating layer on the surface of the recycled high-temperature alloy material.

[0028] In this application, the equivalent volume particle size is used to characterize the particle size, that is, the particle size of the particle to be tested is equal to the diameter of a spherical particle with the same volume as the particle to be tested.

[0029] Secondly, this application also provides a method for preparing the above-mentioned refining slag system, comprising the following steps: S1. Preparation of Mixing: Weigh each raw material according to its mass fraction to obtain the mixture; S2. Ball milling: The mixture is ball milled until it is homogeneous; S3. High-temperature melting: The ball-milled mixture is placed in a melting device for melting to form a homogeneous melt; S4. Cooling and Crushing: The melt is cooled to room temperature and then crushed to obtain granular refining slag.

[0030] In some embodiments, the raw materials in step S1 satisfy at least one of the following conditions: (1) The purity of SiO2 is not less than 99%, and the average particle size is not greater than 1.5 mm; (2) The purity of TiO2 is not less than 99%, and the average particle size is not greater than 1.5 mm; (3) The purity of Fe2O3 is not less than 99%.

[0031] Further limiting the purity and particle size of raw materials in the preparation of refining slag system controls the introduction of other unavoidable impurities from the source, ensuring that the refining ability of the slag system is not interfered with by impurities; and controlling the particle size of SiO2 and TiO2 to ≤1.5mm is beneficial to achieve faster and more uniform mixing during ball milling, resulting in better ball milling effect and the formation of a more uniform melt.

[0032] In some embodiments, the ball milling in step S2 is generally carried out in a ball mill, with a milling time of 2 to 4 hours and a rotation speed of 300 r / min to 400 r / min, which is beneficial for the rapid melting and mixing of materials in the next step.

[0033] From a practical production perspective, the smaller the particle size of each raw material, the better, because this ensures more uniform mixing and a more homogeneous composition of the resulting refining slag system. However, based on cost control requirements, in the embodiments of this application, the average particle size of SiO2 and TiO2 is 1.2 mm, the ball milling time is 3 hours, and the rotation speed is 300 r / min.

[0034] Furthermore, this step does not have special requirements for the purity and moisture content of the raw materials. However, in actual preparation, in order to ensure that the refined slag system obtained has fewer impurities, raw materials with the highest possible purity are generally selected while considering costs. For raw materials that are easily hygroscopic and deliquescent, their moisture content is generally reduced as much as possible. For example: SiO2 purity ≥ 99%; Al2O3 purity ≥ 99%; TiO2 purity ≥ 99%; CaO purity ≥ 99%; Fe2O3 purity ≥ 99%; Na2O is added in the form of Na2CO3 with a purity ≥ 99%; K2O is added in the form of K2CO3 with a purity ≥ 99%; moisture content ≤ 0.1%.

[0035] In some embodiments, the high-temperature melting temperature in step S3 is 1450℃~1550℃, and the time is 40 min to 50 min. The kinetic viscosity of the refining slag system at the temperature is not less than 2.0 Pa·s. By using a refining slag system with a high SiO2 content, the melt formed under high-temperature conditions (1450℃~1550℃) has high viscosity characteristics (≥2.0 Pa·s). This characteristic can both physically capture and retain heavy inclusions such as HfO2 in the melt, and form a dense, stable, and well-covering slag layer on the surface of the high-temperature alloy material. This improves the problem of aluminum vapor volatilizing from the surface of the alloy melt into the vacuum environment, thereby reducing the loss of aluminum element volatilization.

[0036] In some embodiments, step S3 generally involves loading the ball-milled mixture into a packaged heating device consisting of an inner high-purity alumina crucible (purity >99.5%) and an outer graphite heating jacket, and placing it inside a medium-frequency induction furnace. The medium-frequency induction furnace is then powered and heated to 1450°C~1550°C, and held at this temperature for 40 to 50 minutes. During this time, electromagnetic stirring is used to homogenize the melt composition, forming a uniformly mixed molten slag system. This step typically also includes component analysis of the mixture to ensure that each component is within a preset range, which is beneficial for the subsequent formation of a refining slag system that meets preset conditions.

[0037] In some embodiments, in step S4, the molten slag is rapidly poured into a pre-cooled copper mold for rapid cooling (quenching). Then, the cooled, dense glassy or crystalline slag blocks are placed in a jaw crusher for initial crushing, followed by fine crushing in a double roll crusher, and finally screened by a vibrating screener to obtain granular refined slag with an average particle size of no more than 5 mm, which is then sealed and packaged for later use.

[0038] Thirdly, this application also provides a high-vacuum refining method, using the above-mentioned refining slag system, and including the following steps: a. Mix the high-temperature alloy waste powder with the refining slag system and place it in a heating device; b. Place the heating device inside the vacuum furnace and evacuate to a vacuum level of ≤0.1 Pa; c. Raise the temperature inside the vacuum furnace to 1520℃~1580℃ at a uniform rate and hold it for refining for 90~150 minutes.

[0039] In some embodiments, in step a, the mass ratio of the refining slag system to the high-temperature alloy waste powder is (0.5~1.5):1; the high-temperature alloy waste powder includes hafnium, titanium and aluminum. Based on the mass of the high-temperature alloy waste powder, the mass content of hafnium is 0.3%~3.0%, the mass content of titanium is 1.0%~5.0%, and the mass content of aluminum is 2.0%~6.0%.

[0040] In some embodiments, the waste powder of high-temperature alloy is waste powder of FGH97 high-temperature alloy with an average particle size of 50μm~200μm.

[0041] By limiting the mass ratio of refined slag to high-temperature alloy waste powder, the molten refined slag can completely cover the surface of the high-temperature alloy material after melting, forming an effective physical barrier.

[0042] In some implementations, the oxygen content in the recycled high-temperature alloy material is no more than 10 ppm, and the aluminum recovery rate is no less than 95%.

[0043] The following examples and comparative examples illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0044] Measurement methods and equipment: The physical properties mentioned in this application can be measured using the following methods, and the physical properties in the following embodiments and comparative examples are measured using the following methods.

[0045] Slag viscosity determination: The kinetic viscosity of the slag was measured using a high-temperature rotational viscometer under argon protection at 1500℃.

[0046] Elemental content analysis: The content of elements such as Hf, Ti, and Al in the alloy was analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0047] Gas content analysis: The oxygen and nitrogen content in the alloy was determined using an oxygen and nitrogen analyzer (LECO ONH836).

[0048] Aluminum volatilization loss rate calculation: The overall recovery rate of aluminum is calculated by taking into account the total mass of the alloy ingot before and after refining and the aluminum content, in order to assess the volatilization loss.

[0049] Example 1 This embodiment 1 provides a refining slag system, whose components, by mass fraction, include the following: 68% SiO2 (99.5% purity, average particle size 1.2 mm), 10% Al2O3 (99.5% purity, average particle size 2 mm), 10% TiO2 (99% purity, average particle size 1.2 mm), 5% CaO (99% purity, average particle size 1.5 mm, baked at 900℃ for 2 hours before use to remove moisture), 2% Fe2O3 (99.5% purity), 3.5% Na2O (added as Na2CO3, 99.5% purity), and 1.5% K2O (added as K2CO3, 99% purity). Its preparation method is as follows: S1. Preparation of Mixing: Weigh each raw material according to the above mass fractions to obtain the mixture; S2. Ball milling: Place the above mixture in a planetary ball mill and ball mill at a speed of 300 r / min for 3 hours to ensure that the components are mixed evenly; S3. High-temperature smelting: The ball-milled mixture is loaded into a set-type heating device consisting of an inner high-purity alumina crucible (purity >99.5%) and an outer graphite heating jacket, and placed in a medium-frequency induction furnace. Power is supplied to raise the temperature to 1550℃, and this temperature is maintained for 40 minutes. During this period, electromagnetic stirring is used to homogenize the melt composition and form a uniformly mixed molten slag system.

[0050] S4. Cooling and Crushing: The molten slag is quickly poured into a pre-cooled copper mold for rapid cooling (quenching). The cooled, dense glassy or crystalline slag blocks are then placed in a jaw crusher for initial crushing, followed by fine crushing in a double roll crusher, and finally screened by a vibrating screener to obtain granular refined slag with an average particle size of no more than 5 mm. The slag is then sealed and packaged for later use.

[0051] The above-mentioned refined slag is used for the preparation of recycled high-temperature alloy materials, specifically including the following steps: a. Loading: Weigh 5000g of hafnium-rich, titanium-rich, and aluminum-rich high-temperature alloy waste powder (initial oxygen content is 165ppm, aluminum content is 5.8wt%), mix it evenly with 7500g (mass ratio 1.5:1) of the above-prepared refined slag particles, and load them together into the inner crucible of a set-type heating device consisting of an inner high-purity alumina crucible and an outer graphite heating jacket; b. Vacuuming and Melting: Place the entire apparatus into the vacuum induction furnace, close the furnace door, and start the vacuum system. Once the vacuum level inside the furnace reaches and stabilizes at 0.08 Pa, begin electric heating through the outer graphite heating jacket. Utilizing the excellent high-temperature radiation properties of graphite, heat is evenly radiated to the internal alumina crucible, causing the furnace temperature to rise uniformly to 1550℃ within 60 minutes. c. Heat treatment refining: Heat treatment at 1550℃ and 0.08 Pa vacuum for 120 minutes; d. Casting and Sampling: After refining, while maintaining a vacuum, the alloy melt is cast into a pre-cooled copper mold to obtain an alloy ingot. After cooling, a sample is prepared from the center of the alloy ingot for compositional analysis.

[0052] See Figure 1 , Figure 1 This is a SEM image of the recycled high-temperature alloy material after purification in Example 1 of this application.

[0053] Example 2 Compared with Example 1, the difference in Example 2 is that it provides a refining slag system, the components of which, by mass fraction, include the following components: 75% SiO2, 8% Al2O3, 8% TiO2, 5% CaO, 1% Fe2O3, 2% Na2O, and 1% K2O. Its preparation method is the same as in Example 1.

[0054] The above-mentioned refined slag is used for the preparation of recycled high-temperature alloy materials, and the preparation method of the recycled high-temperature alloy materials is the same as in Example 1.

[0055] Example 3 Compared with Example 1, the difference in Example 3 is that it provides a refining slag system, the components of which, by mass fraction, include the following components: 70% SiO2, 8% Al2O3, 8% TiO2, 6% CaO, 1.5% Fe2O3, 4% Na2O, and 2.5% K2O. Its preparation method is the same as in Example 1.

[0056] The above-mentioned refined slag is used for the preparation of recycled high-temperature alloy materials, and the preparation method of the recycled high-temperature alloy materials is the same as in Example 1.

[0057] Example 4 Compared with Example 1, the difference in Example 4 is that it provides a refining slag system, the components of which, by mass fraction, include the following components: 65% SiO2, 12% Al2O3, 12% TiO2, 4% CaO, 2% Fe2O3, 3% Na2O, and 2% K2O. Its preparation method is the same as in Example 1.

[0058] The above-mentioned refined slag is used for the preparation of recycled high-temperature alloy materials. The difference between the preparation method of recycled high-temperature alloy materials and Example 1 is that step b is to achieve and stabilize the vacuum degree in the furnace at 0.05 Pa, while the rest is the same as Example 1.

[0059] Example 5 Compared with Example 1, the difference in Example 5 is that it provides a refining slag system, the components of which, by mass fraction, include the following components: 60% SiO2, 11% Al2O3, 11% TiO2, 7% CaO, 3% Fe2O3, 5% Na2O, and 3% K2O. Its preparation method is the same as in Example 1.

[0060] The above-mentioned refined slag is used for the preparation of recycled high-temperature alloy materials, and the preparation method of the recycled high-temperature alloy materials is the same as in Example 1.

[0061] Comparative Example 1 Comparative Example 1 provides a conventional high-basicity CaO-Al2O3-SiO2 refining slag system, whose components, by mass fraction, include the following: 35% SiO2, 40% Al2O3, and 25% CaO. Its preparation method is the same as in Example 1.

[0062] The above-mentioned refined slag is used for the preparation of recycled high-temperature alloy materials, and the preparation method of the recycled high-temperature alloy materials is the same as in Example 1.

[0063] See Figure 2 , Figure 2 The image shows the SEM-EDS characterization of inclusions in the recycled high-temperature alloy material obtained in Comparative Example 1 of this application after purification.

[0064] Comparative Example 2 Comparative Example 2 uses the same refining slag system as Example 1 and the preparation method is the same. Compared with Example 1, the difference of Comparative Example 2 is that the above-mentioned refining slag system is used for the preparation of recycled high-temperature alloy materials. In the preparation method of recycled high-temperature alloy materials, step (2) achieves and stabilizes the vacuum degree in the furnace at 10 Pa, and the rest is the same as in Example 1.

[0065] Table 1

[0066] As shown in Table 1, the acidic high-viscosity slag system of the present invention (Examples 1 to 5) can reduce the oxygen content in high-temperature alloys to below 10 ppm under a high vacuum of ≤0.1 Pa, while maintaining a high recovery rate of over 92% for precious elements such as Hf, Ti, and Al, especially with an aluminum recovery rate exceeding 95.8%. This indicates that the refining slag system and preparation method of the present invention achieve excellent deoxidation and inclusion removal effects under high vacuum and effectively suppress aluminum volatilization loss.

[0067] As can be seen from Comparative Example 1, the traditional slag system has a lower viscosity and cannot effectively capture heavy inclusions and form a dense coating layer under high vacuum. Therefore, the oxygen and nitrogen purification effect and metal element recovery rate of the recycled high-temperature alloy material obtained by it are significantly worse than those of the embodiments of the present invention. Figure 1 and Figure 2 It can be seen that the recycled high-temperature alloy material obtained in Example 1 has no inclusions in the SEM characterization after purification, while the recycled high-temperature alloy material obtained in Comparative Example 1 still has inclusions after purification. Therefore, the refining slag system of this application can effectively retain heavy inclusions with high density.

[0068] As can be seen from Comparative Example 2, the refining slag system provided in this application has high viscosity and can effectively capture heavy inclusions. However, under insufficient vacuum, the vapor pressure of aluminum is high, and even with a slag layer covering, aluminum volatilization is still significant, resulting in an Al recovery rate of only 88.1%, failing to achieve efficient aluminum retention. Therefore, only when "high vacuum" and "high-viscosity covering slag" work synergistically can the goal of efficient aluminum retention be achieved.

[0069] In summary, the technical solution provided in this application successfully solves the two core challenges of inclusion removal and active element volatilization faced by waste powders of hafnium-rich, titanium-rich, and aluminum-rich high-temperature alloys during vacuum refining, providing a reliable technical path for achieving closed-loop recycling and high-quality regeneration of such high-value materials.

[0070] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the principles of this application should be included within the protection scope of this application.

Claims

1. A refining slag system, characterized in that, Its components, by mass fraction, include the following components: 60%~75% SiO2, 8%~15% Al2O3, 8%~15% TiO2, 3%~8% CaO, 1%~3% Fe2O3, 2%~5% Na2O, 1%~3% K2O, and unavoidable impurities not exceeding 0.5% in total.

2. The refining slag system according to claim 1, characterized in that, Its components, by mass fraction, include the following components: 65%~70% SiO2, 10%~12% Al2O3, 10%~12% TiO2, 4%~6% CaO, 1.5%~2.5% Fe2O3, 3%~4% Na2O, 1.5%~2.5% K2O.

3. The refining slag system according to claim 1, characterized in that, The refining slag is granular with an average particle size of no more than 8 mm.

4. A method for preparing the refining slag system as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Weigh the raw materials of the components according to their mass fractions to obtain a mixture; S2. The mixture is ball-milled until it is homogeneous; S3. The ball-milled mixture is placed in a melting device for melting to form a melt; S4. Cool the melt to room temperature and then crush it to obtain the granular refining slag system.

5. The preparation method according to claim 4, characterized in that, The raw materials in step S1 satisfy at least one of the following conditions: (1) The purity of the SiO2 is not less than 99%, and the average particle size is not greater than 1.5 mm; (2) The purity of the TiO2 is not less than 99%, and the average particle size is not greater than 1.5 mm; (3) The purity of the Fe2O3 is not less than 99%.

6. The preparation method according to claim 4, characterized in that, In step S3, the smelting temperature is 1450℃~1550℃ and the time is 40 min to 50 min. The kinetic viscosity of the refining slag system at the temperature is not less than 2.0 Pa·s.

7. A high-vacuum refining method, characterized in that, Using the refining slag system as described in any one of claims 1 to 3, and comprising the following steps: a. Mix the high-temperature alloy waste powder with the refining slag system and place it in a heating device; b. Place the heating device in a vacuum furnace and evacuate to a vacuum level of ≤0.1 Pa; c. Raise the temperature inside the vacuum furnace at a constant rate to 1520℃~1580℃ and hold it for refining for 90~150 minutes.

8. The high-vacuum refining method according to claim 7, characterized in that, In step a, the mass ratio of the refining slag system to the high-temperature alloy waste powder is (0.5~1.5):1; the high-temperature alloy waste powder includes hafnium, titanium and aluminum. Based on the mass of the high-temperature alloy waste powder, the mass content of hafnium is 0.3%~3.0%, the mass content of titanium is 1.0%~5.0%, and the mass content of aluminum is 2.0%~6.0%.

9. The high-vacuum refining method according to claim 8, characterized in that, The waste powder of the high-temperature alloy is waste powder of FGH97 high-temperature alloy, with an average particle size of 50~200 μm.

10. The high-vacuum refining method according to claim 7, characterized in that, The oxygen content in the recycled high-temperature alloy material is no more than 10 ppm, and the aluminum recovery rate is no less than 95%.

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