A refined slag system and its preparation method and application

Abstract

This application discloses a refining slag system, its preparation method, and its application. The refining slag system comprises, by mass, 40% to 55% Al2O3, 20% to 30% SiO2, 16% to 22% K2O, 3% to 10% Na2O, and 2% to 4% CaO. This refining slag system can remove most impurities from FGH97 alloy return material, improving the quality of the recovered alloy and reducing alloy production costs.

Description

Technical Field

[0001] The present application relates to the field of vacuum refining technology, and in particular to a refined slag system and a preparation method and application thereof. Background Art

[0002] With the rapid development of my country's aerospace, gas turbine, nuclear power and other industries, the use of high-temperature alloy materials is increasing. However, high-temperature alloy finished products require high cleanliness, have many processing steps, a long manufacturing process, and low material utilization. For example, the weight of the finished high-temperature alloy is usually only 30% of the total weight of the original metal input, and some are even only about 10%. The rest exists in the form of waste such as unqualified powder, turnings, off-cuts, tails, risers, runners, and forging waste. The above waste is called high-temperature alloy return material. The content of strategic alloying elements (Ni, Co, Cr, W, Mo, etc.) in high-temperature alloys exceeds 40%, and there are more than 40 main alloying elements and trace elements, including rare and precious elements such as Nb, Ta, Hf, Re, etc. Therefore, the high-temperature alloy return material generally needs to be re-smelted for reuse.

[0003] For example, FGH97 alloy possesses excellent heat resistance, corrosion resistance, and mechanical properties. However, during the smelting process, FGH97 alloy return material contains a large amount of impurities and oxides, which are difficult to remove using current refining methods. Therefore, developing a technology to purify FGH97 alloy return material is crucial for improving alloy quality and reducing production costs. Summary of the Invention

[0004] The present application provides a refining slag system, a preparation method and an application thereof. The refining slag system of the present application can remove most impurities in the FGH97 alloy return material, thereby improving the quality of the recovered alloy and reducing the production cost of the alloy.

[0005] In a first aspect, the present application provides a refining slag system, the components of which, by mass fraction, include 40% to 55% Al2O3, 20% to 30% SiO2, 16% to 22% K2O, 3% to 10% Na2O, and 2% to 4% CaO.

[0006] The refined slag system of this application, by adjusting the content of each component, can effectively reduce the content of oxygen, nitrogen, and sulfur inclusions in the alloy return material, achieving the technical effect of purifying the alloy return material. The combination of 40% to 55% Al2O3 and 20% to 30% SiO2 can adsorb impurities such as oxygen, nitrogen, and sulfur inclusions. The specific content of K2O, Na2O, and CaO not only lowers the melting point of the refined slag system but also regulates its fluidity, ensuring that Al2O3 and SiO2 can better adsorb oxygen, nitrogen, and sulfur inclusions. The refined slag system of this application can remove most impurities from FGH97 alloy return material, which is beneficial for improving the quality of the recovered alloy and reducing the production cost of the alloy.

[0007] In some embodiments, the components of the refined slag system may include, by mass fraction, 40% to 50% Al2O3, 20% to 30% SiO2, 16% to 19% K2O, 8% to 10% Na2O, and 2% to 4% CaO.

[0008] In some of the embodiments, based on the total mass of the refined slag system, it satisfies at least one of the following conditions: (1) the total content of MgO and TiO2 is not greater than 0.5%; (2) the carbon content is not greater than 0.03%; (3) the phosphorus content is not greater than 0.01%; and (4) the sulfur content is not greater than 0.005%.

[0009] Based on the above embodiments, the above-mentioned refined slag system introduces fewer impurities when used, which is more conducive to improving the cleanliness of the recovered alloy.

[0010] In some embodiments, the refined slag is in granular form, and the average particle size of the granular refined slag is no more than 10 mm.

[0011] Based on the above embodiment, the granular refined slag with an average particle size of no more than 10 mm can be better fused with the alloy when used, and can further increase the cleanliness of the recovered alloy.

[0012] In some embodiments, in the refined slag system, based on the total mass of the refined slag system, the particle size is between 5 mm and 10 mm, accounting for 25% to 35%, the particle size is greater than 0.5 mm and less than 5 mm, accounting for 60% to 74%, and the particle size is not greater than 0.5 mm, accounting for 1% to 5%.

[0013] Based on the above embodiments, the particle size of the refined slag system is relatively uniform, which is conducive to smelting and has good fluidity, and can reduce dust pollution.

[0014] In the second aspect, the present application provides a method for preparing a refined slag system, which includes the following steps: ball milling the mixture, and then smelting, cooling and crushing in sequence; the mixture includes 40% to 55% Al2O3, 20% to 30% SiO2, 16% to 22% K2O, 3% to 10% Na2O, and 2% to 4% CaO by mass fraction.

[0015] Based on the above preparation method, the refined slag system prepared can remove most of the impurities in the FGH97 alloy return material, which is beneficial to improving the quality of the recovered alloy and reducing the production cost of the alloy.

[0016] In some embodiments, the mixture satisfies at least one of the following conditions: (1) the average particle size of Al2O3 is not greater than 3 mm; (2) the average particle size of TiO2 is not greater than 3 mm; (3) the average particle size of Na2O is not greater than 4 mm; (4) the average particle size of CaO is not greater than 3 mm.

[0017] Based on the above embodiments, the preparation time of the refined slag system is shorter, and the components of the prepared refined slag system are more uniform, and the purification effect is better.

[0018] In a third aspect, the present application provides the use of the above-mentioned refined slag system in the return material of vacuum refined FGH97 alloy.

[0019] Based on the above applications, the refining process of FGH97 alloy return material is simpler, with lower consumption and better purification effect.

[0020] In some embodiments, the mass ratio of the refined slag system to the FGH97 alloy return material during refining is 0.5:1 to 2:1.

[0021] Based on the above embodiment, controlling the mass ratio within a reasonable range can accelerate the removal of inclusions in the FGH97 alloy return material and ensure the refining effect.

[0022] In some embodiments, the vacuum refining time is 60 to 120 minutes; and / or the vacuum degree during refining is 20 to 100 Pa.

[0023] Based on the above embodiment, controlling the vacuum refining time and vacuum degree within an appropriate range is more conducive to removing dissolved oxygen and nitrogen in the FGH97 alloy return material. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0025] Figure 1 This is the EDS element distribution diagram of the refined slag system in Example 1 of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0027] In the prior art, impurities in FGH97 alloy return materials are not easily purified during vacuum refining, resulting in low recovery quality. To address this technical problem, this application proposes a refining slag system. Using the refining slag system described in this application for vacuum refining of FGH97 alloy return materials effectively removes most impurities from the FGH97 alloy return materials, thereby improving recovery quality.

[0028] First, the present application provides a refining slag system comprising, by mass, 40% to 55% Al2O3, 20% to 30% SiO2, 16% to 22% K2O, 3% to 10% Na2O, and 2% to 4% CaO. Preferably, the preferred ranges for the components in the refining slag system are 40% to 50% Al2O3, 20% to 30% SiO2, 16% to 19% K2O, 8% to 10% Na2O, and 2% to 4% CaO. The synergistic effect of the components within the specified ranges of the present application can effectively reduce the oxygen, nitrogen, and sulfur inclusions in FGH97 alloy return material, improve the cleanliness of the high-temperature alloy, and thereby enhance the quality of the recovered alloy. In the refined slag system of this application, the combination of Al2O3 and SiO2 within the aforementioned content range can adsorb impurities such as oxygen, nitrogen, and sulfur inclusions. K2O, Na2O, and CaO can lower the melting point of the refined slag system and regulate its fluidity, allowing Al2O3 and SiO2 to better adsorb oxygen, nitrogen, and sulfur inclusions. Therefore, the refined slag system of this application can remove most impurities from the FGH97 alloy return material, improving the quality of the recovered alloy and reducing the alloy's production cost.

[0029] Of course, in some other embodiments, in order to further improve the flow properties of the refined slag system, the refined slag system may also include Fe3O4 and the like, as long as the purpose of this application can be achieved, which will not be elaborated here.

[0030] In some embodiments of the present application, in order to ensure that the refined slag system introduces fewer impurities during use and further improve the cleanliness of the recovered alloy, the refined slag system generally meets at least one of the following conditions: (1) the total content of MgO and TiO2 is not greater than 0.5%; (2) the carbon content is not greater than 0.03%; (3) the phosphorus content is not greater than 0.01%; (4) the sulfur content is not greater than 0.005%. It should be noted that the above-mentioned MgO, TiO2, C, P, S, etc. are not required components, but are inevitable impurities in the process of preparing the refined slag system. These impurities are generally derived from the raw materials. Due to the low content of impurities, they are usually negligible.

[0031] In some embodiments of the present application, the refined slag system is typically granular, with an average particle size of no greater than 10 mm. This allows the refined slag system to better fuse with the alloy during use, further increasing the cleanliness of the recovered alloy. It should also be noted that the identical components of the refined slag system in this application are not aggregated together, but rather uniformly mixed. Therefore, when the refined slag system is granular, the components of each particle are similar or even identical, and will contain Al2O3, SiO2, K2O, Na2O, CaO, Fe3O4, etc.

[0032] In this application, the equivalent volume particle size is used to characterize the particle size of the particle, that is, the particle size of the particle to be measured is equal to the diameter of a spherical particle with the same volume as the particle to be measured.

[0033] In addition, in some embodiments of the present application, based on the total mass of the refined slag system, the granular refined slag system has a particle size of 5mm to 10mm accounting for 25% to 35%, a particle size greater than 0.5mm and less than 5mm accounting for 60% to 74%, and a particle size of no greater than 0.5mm accounting for 1% to 5%. This can make the particle size of the refined slag system more uniform, which is conducive to smelting and has good fluidity, and can also reduce dust pollution. As an example, in an embodiment of the present application, the particle size of 5mm to 10mm accounts for 25%, the particle size greater than 0.5mm and less than 5mm accounts for 70%, and the particle size no greater than 0.5mm accounts for 5%.

[0034] In a second aspect, the present application also provides a method for preparing the above-mentioned refined slag system, which specifically comprises the following steps:

[0035] S100, ball milling the mixed material.

[0036] In this step, the mixture comprises 40% to 55% Al2O3, 20% to 30% SiO2, 16% to 22% K2O, 3% to 10% Na2O, and 2% to 4% CaO. Ball milling is typically performed in a ball mill for 2 to 4 hours, which facilitates rapid melting of the mixture in the next step.

[0037] In addition, in order to shorten the preparation time and make the components of the refined slag system more uniform and the purification effect better, each component in the mixture should meet at least one of the following conditions: (1) the average particle size of Al2O3 is not greater than 3mm; (2) the average particle size of TiO2 is not greater than 3mm; (3) the average particle size of Na2O is not greater than 4mm; (4) the average particle size of CaO is not greater than 3mm.

[0038] In practical production, the smaller the particle size of each raw material, the better, as this allows for more uniform mixing of the raw materials and a more uniform composition of the resulting refined slag. However, to control costs, in the examples of this application, the average particle size of Al2O3, TiO2, Na2O, and CaO was 2 mm, and the ball milling time was 3 h.

[0039] In addition, this step does not have any special requirements for the purity and water content of the raw materials. However, in the actual preparation process, in order to ensure that the refined slag system has fewer impurities, raw materials with higher purity are generally selected as much as possible based on cost considerations. For raw materials that are easy to absorb water and deliquesce, their water content is generally reduced as much as possible; for example: Al2O3 purity ≥99.5%; SiO2 purity ≥98%; K2O purity ≥99%, water content ≤0.5%; Na2O purity ≥99.5%, water content ≤0.5%; CaO purity ≥99%, water content ≤0.1%.

[0040] S200, melting the mixed material.

[0041] This step typically involves placing the ball-milled mixture into an electric arc furnace. Power is supplied to the furnace, and graphite electrodes are used to heat and melt the mixture. The completely melted mixture is then evenly mixed to form a mixed system. This step also typically involves testing the mixed system to ensure that the components are within the pre-set range, facilitating the subsequent formation of a refined slag system that meets pre-set requirements.

[0042] S300, cooling and crushing.

[0043] In this step, the mixed system is poured into a copper mold for cooling, and then crushed in a crusher to produce a refined slag system. Furthermore, the average particle size of the refined slag obtained after crushing in this step is generally no larger than 10 mm. This allows the refined slag to better fuse with the alloy during use, further improving the cleanliness of the recovered alloy.

[0044] S400, screening and refining slag system.

[0045] This step usually uses screening equipment to screen the particle size of the refined slag system. After screening, based on the total mass of the refined slag system, the particle size is 5mm-10mm, accounting for 25%-35%, the particle size is greater than 0.5mm and less than 5mm, accounting for 60%-74%, and the particle size is not greater than 0.5mm, accounting for 1%-5%.

[0046] Furthermore, in actual production, the refined slag may not be used immediately. In this case, the refined slag can be dried and stored. Specifically, the refined slag can be placed in an alumina crucible and then baked in a resistance furnace to reduce moisture. The baking temperature is set at 950°C ± 20°C for 2-3 hours. After the baking is complete, the refined slag is cooled and then placed in a moisture-proof aluminum foil bag. After the air is evacuated, the bag is filled with high-purity argon (purity > 99.9%) and sealed for use.

[0047] Thirdly, this application also provides the use of a refining slag system in vacuum refining of FGH97 alloy return material. Using the refining slag system in vacuum refining of FGH97 alloy return material can simplify the refining process of the FGH97 alloy return material, not only reducing vacuum refining energy consumption but also achieving better purification results. Specifically, in some embodiments of this application, the mass ratio of the refining slag system to the FGH97 alloy return material during refining is 0.5:1 to 2:1. This accelerates the removal of inclusions from the FGH97 alloy return material and ensures effective refining. The vacuum refining time is generally 60 to 120 minutes, and the vacuum level during refining is 20 to 100 Pa. Furthermore, during vacuum refining of the FGH97 alloy return material, the FGH97 alloy return material can be added to a crucible, followed by the refining slag system, and then placed in a vacuum reactor for refining. Alternatively, the FGH97 alloy return material can be added to a crucible, heated to a temperature of 100°C in an argon atmosphere reactor, and then the refining slag system is added for vacuum refining.

[0048] Example

[0049] The following examples and comparative examples are given to illustrate the embodiments of the present application in more detail. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0050] Test methods and equipment:

[0051] Determination of uniformity of refined slag system:

[0052] Take 500 mg of refined slag and analyze its particle cross-section composition using an energy dispersive spectrometer (EDS). Figure 1 This is the EDS element distribution diagram of the refined slag system in Example 1. Figure 1It can be seen that the composition of the refined slag system is relatively uniform.

[0053] Purification effect test:

[0054] 5000g or 10000g of FGH97 alloy return material was added to a crucible, and then the refined slag was added and placed in a vacuum reactor for refining. After that, a cubic sample of about 5mm in the center of the refined alloy ingot was taken and the oxygen content, nitrogen content and sulfur content of the recovered alloy were tested using an oxygen, nitrogen and sulfur analyzer.

[0055] The mass ratio of the refined slag system to the FGH97 alloy return material was 1:1, 1:2, or 2:1, the vacuum refining time was 60 min or 120 min, and the vacuum degree during refining was 60 Pa. Specific purification conditions and purification effects can be seen in Table 1.

[0056] Example 1

[0057] This embodiment provides a refined slag system, and the preparation method thereof is as follows:

[0058] (1) 45% Al2O3, 25% SiO2, 18% K2O, 10% Na2O, and 2% CaO were mixed to form a mixture, and the mixture was ball-milled in a ball mill for 3 h.

[0059] (2) The ball-milled mixture is placed in an electric arc furnace and then smelted until the completely melted mixture is evenly mixed to form a mixed system.

[0060] (3) The mixed system is poured into a copper mold for cooling, and then the cooled mixed system is placed in a crusher for crushing to obtain a refined slag system.

[0061] Detection by an element analyzer shows that the impurities in the refined slag system include, by mass content, 0.02% C, 0.008% P, 0.003% S, and the total mass content of MgO and TiO2 is 0.42%.

[0062] Example 2

[0063] This embodiment provides a refined slag system, and its preparation method is different from that of Example 1 in that: in step (1), 40% Al2O3, 30% SiO2, 16% K2O, 10% Na2O, and 4% CaO are mixed to form a mixture, which is then ball-milled in a ball mill for 3 hours.

[0064] Detection by an element analyzer shows that the impurities in the refined slag system include, by mass content, 0.01% C, 0.006% P, 0.005% S, and the total mass content of MgO and TiO2 is 0.48%.

[0065] Example 3

[0066] This embodiment provides a refined slag system, and its preparation method is different from that of Example 1 in that: in step (1), 50% Al2O3, 20% SiO2, 19% K2O, 8% Na2O, and 3% CaO are mixed to form a mixture, which is then ball-milled in a ball mill for 3 hours.

[0067] Detection by an element analyzer shows that the impurities in the refined slag system include, by mass content, 0.03% C, 0.005% P, 0.004% S, and the total mass content of MgO and TiO2 is 0.40%.

[0068] Example 4

[0069] This embodiment provides a refined slag system, and its preparation method is different from that of Example 1 in that: in step (1), 52% Al2O3, 25% SiO2, 22% K2O, 3% Na2O, and 2% CaO are mixed to form a mixture, which is then ball-milled in a ball mill for 3 hours.

[0070] Detection by an element analyzer shows that the impurities in the refined slag system include, by mass content, 0.05% C, 0.008% P, 0.009% S, and the total mass content of MgO and TiO2 is 0.44%.

[0071] Comparative Example 1

[0072] This embodiment provides a refined slag system, and its preparation method is different from that of Example 1 in that: in step (1), 38% Al2O3, 32% SiO2, 18% K2O, 10% Na2O, and 2% CaO are mixed to form a mixture, which is then ball-milled in a ball mill for 3 hours.

[0073] Detection by an element analyzer shows that the impurities in the refined slag system include, by mass content, 0.03% C, 0.006% P, 0.006% S, and the sum of the mass content of MgO and TiO2 is 0.45%.

[0074] Comparative Example 2

[0075] This embodiment provides a refined slag system, and its preparation method is different from that of Example 1 in that: in step (1), 56% Al2O3, 14% SiO2, 18% K2O, 10% Na2O, and 2% CaO are mixed to form a mixture, which is then ball-milled in a ball mill for 3 hours.

[0076] Detection by an element analyzer shows that the impurities in the refined slag system include, by mass content, 0.02% C, 0.008% P, 0.008% S, and the total mass content of MgO and TiO2 is 0.44%.

[0077] Table 1 Purification conditions and purification effects of the refined slag systems of various embodiments and comparative examples

[0078]

[0079]

[0080] As can be seen from Table 1, the refined slag system in this application can remove most of the impurities in the FGH97 alloy return material, thereby improving the quality of the recovered alloy and reducing the production cost of the alloy.

[0081] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A refined slag system, characterized in that: Its components, by mass fraction, are 40%~55%Al2O3, 20%~30%SiO2, 16%~22%K2O, 3%~10%Na2O, and 2%~4%CaO.

2. The refined slag system according to claim 1, characterized in that: Its components, by mass fraction, are 40%~50% Al2O3, 20%~30% SiO2, 16%~19% K2O, 8%~10% Na2O, and 2%~4% CaO.

3. The refined slag system according to claim 1, characterized in that: Based on the total mass of the refined slag system, it satisfies at least one of the following conditions: (1) The total content of MgO and TiO2 is not more than 0.5%; (2) The carbon content is not more than 0.03%; (3) The phosphorus content is not more than 0.01%; (4) The sulfur content shall not exceed 0.005%.

4. The refined slag system according to claim 1, characterized in that: The refined slag is in granular form, and the average particle size of the refined slag is no more than 10 mm.

5. The refined slag system according to claim 4, characterized in that: In the refined slag system, based on the total mass of the refined slag system, the particle size is 5 mm to 10 mm, accounting for 25% to 35%, the particle size is greater than 0.5 mm and less than 5 mm, accounting for 60% to 74%, and the particle size is not greater than 0.5 mm, accounting for 1% to 5%.

6. A method for preparing the refined slag system according to claim 1, characterized in that: It includes the following steps: The mixed material is ball-milled, and then melted, cooled and crushed in sequence; the mixed material consists of 40% to 55% Al2O3, 20% to 30% SiO2, 16% to 22% K2O, 3% to 10% Na2O, and 2% to 4% CaO by mass.

7. The method for preparing a refined slag system according to claim 6, characterized in that: The mixture satisfies at least one of the following conditions: (1) The average particle size of the Al2O3 is not greater than 3 mm; (2) The average particle size of the Na2O is not greater than 4 mm; (3) The average particle size of the CaO is not greater than 3 mm.

8. Use of the refined slag according to any one of claims 1 to 5 in the return material of vacuum refining of FGH97 alloy.

9. The use according to claim 8, characterized in that During refining, the mass ratio of the refining slag system to the FGH97 alloy return material is 0.5:1-2:

1.

10. The use according to claim 8, characterized in that The vacuum refining time is 60 to 120 minutes; and / or, The vacuum degree during refining is 20~100Pa.

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