A method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride

Abstract

This invention provides a method for producing high-purity aluminum-niobium-tantalum master alloys and co-producing ammonium fluoride, belonging to the fields of metallic materials and inorganic chemicals. The invention involves mixing fluoroniobic acid, fluorotantalic acid, and ammonia water for a precipitation reaction to obtain a precipitate and an ammonium fluoride solution. The ammonium fluoride solution is then concentrated, cooled for crystallization, dehydrated, and dried sequentially to obtain ammonium fluoride. The precipitate is then dried and oxidized and calcined sequentially to obtain an oxide. The oxide, aluminum powder, potassium chlorate, and calcium fluoride are mixed and subjected to a vacuum aluminothermic reaction to obtain the high-purity aluminum-niobium-tantalum master alloy. This invention, considering both broadening the range of raw material selection and optimizing the production process, reacts fluoroniobic acid, fluorotantalic acid, and ammonia water to produce niobium hydroxide and tantalum hydroxide precipitates, which are then oxidized and calcined to form niobium and tantalum oxides. The high-purity aluminum-niobium-tantalum alloy is then prepared using a vacuum aluminothermic reaction. Simultaneously, ammonium fluoride can be co-produced, resulting in high raw material utilization.

Description

Technical Field

[0001] This invention relates to the fields of metallic materials and inorganic chemical technology, and in particular to a method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride. Background Technology

[0002] Aluminum-niobium-tantalum alloys are mainly used in alloys such as TA29 and TA12A. TA29, with the nominal grade Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb-1.5Ta-0.4Si-0.06C, is a near-alpha high-temperature titanium alloy that can operate at 600℃ for extended periods. This alloy has excellent heat resistance and good machinability, making it an ideal material for manufacturing high thrust-to-weight ratio aero engines. It can also be designed for use in the manufacture of components such as integral bladed disks for compressors.

[0003] The current production method for aluminum-niobium-tantalum master alloys mainly involves ladle ignition smelting. For example, Chinese patents CN103173662A and CN1629343A use Al as a reducing agent and Nb2O5 and Ta2O5 as oxidizing agents, utilizing the self-generating heat of the metallothermic reduction reaction to achieve the smelting of the master alloy. Chinese patents CN116397138A and CN110408806A also use Al as a reducing agent and Nb2O5 and Ta2O5 as oxidizing agents, utilizing the metallothermic reduction reaction to smelt the alloy, and subsequently improving uniformity through pelletizing and vacuum induction furnace. However, the raw materials for aluminum-niobium-tantalum alloys are currently Nb2O5 and Ta2O5, which are expensive, require pre-reaction drying, and have long smelting cycles with a large time span. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for producing high-purity aluminum-niobium-tantalum master alloys and co-producing ammonium fluoride. This invention utilizes fluoroniobic acid and fluorotantalic acid as raw materials to produce high-purity aluminum-niobium-tantalum master alloys while simultaneously producing ammonium fluoride with low silicon impurities. This not only broadens the selection range of raw materials for aluminum-niobium-tantalum alloys and shortens the production cycle, but also optimizes the production process.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride, comprising the following steps:

[0007] Fluoroniobic acid, fluorotantalic acid and ammonia water are mixed and subjected to a precipitation reaction to obtain a precipitate product and an ammonium fluoride solution. The ammonium fluoride solution is then concentrated, cooled and crystallized, dehydrated and dried sequentially to obtain the ammonium fluoride. The precipitate product includes niobium hydroxide and tantalum hydroxide.

[0008] The precipitated product was successively dried and oxidized and calcined to obtain an oxidized material;

[0009] The oxide, aluminum powder, potassium chlorate and calcium fluoride are mixed and subjected to a vacuum aluminothermic reaction to obtain the high-purity aluminum-niobium-tantalum master alloy. The composition of the high-purity aluminum-niobium-tantalum master alloy, by mass percentage, includes: Nb 30.0-40.0%, Ta 10.0-15.0%, with the balance being Al and unavoidable impurities.

[0010] Preferably, the fluoroniobic acid includes one or more of monofluoroniobic acid, difluoroniobic acid, trifluoroniobic acid, tetrafluoroniobic acid, pentafluoroniobic acid, hexafluoroniobic acid, and heptafluoroniobic acid; the fluorotantalic acid includes one or more of monofluorotantalic acid, difluorotantalic acid, trifluorotantalic acid, tetrafluorotantalic acid, pentafluorotantalic acid, hexafluorotantalic acid, and heptafluorotantalic acid.

[0011] Preferably, the mixing of fluoroniobic acid, fluorotantalic acid and ammonia water includes the following steps: adding ammonia water to the mixture of fluoroniobic acid and fluorotantalic acid, wherein the concentration of fluoroniobic acid in the mixture is 80-110 g / L and the concentration of fluorotantalic acid is 60-100 g / L, calculated as Nb2O5 and Ta2O5.

[0012] Preferably, the precipitation reaction results in a pH of 9 to 10 for the system.

[0013] Preferably, the particle size of the precipitated product is 0.1-2 mm and the D50 is 0.2-0.6 mm.

[0014] Preferably, the oxidative roasting is carried out in a fluidized bed roasting furnace, wherein the packing thickness of the fluidized bed roasting furnace is 250-350 mm, the fluidized bed height is 600-1200 mm, the critical wind speed is 0.6-0.9 m / s, and the wind pressure is 700-900 mmH2O.

[0015] Preferably, the oxidative calcination temperature is 600–800°C and the time is 0.2–0.5 h.

[0016] Preferably, the gas used in the oxidative roasting is compressed air.

[0017] Preferably, the crucible for the vacuum aluminothermic reaction is made of copper, the diameter of the crucible is 0.8–1.2 m, and the cooling water circulation rate is 9–12 m³ / h. 3 The cooling water pressure is 2.4–3.5 MPa, the inlet temperature is 22–27°C, and the outlet temperature is 45–50°C.

[0018] Preferably, the vacuum aluminothermic reaction time is 40–70 s.

[0019] This invention provides a method for producing a high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride, comprising the following steps: mixing fluoroniobic acid, fluorotantalic acid, and ammonia water for a precipitation reaction to obtain a precipitate product and an ammonium fluoride solution; sequentially concentrating, cooling and crystallizing, dehydrating, and drying the ammonium fluoride solution to obtain the ammonium fluoride; wherein the precipitate product comprises niobium hydroxide and tantalum hydroxide; sequentially drying and oxidizing the precipitate product to obtain an oxidant; mixing the oxidant, aluminum powder, potassium chlorate, and calcium fluoride, and performing a vacuum aluminothermic reaction to obtain the high-purity aluminum-niobium-tantalum master alloy; wherein, by mass percentage, the composition of the high-purity aluminum-niobium-tantalum master alloy comprises: Nb 30.0–40.0%, Ta 10.0–15.0%, with the balance being Al and unavoidable impurities.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention, considering both broadening the selection range of raw materials for high-purity aluminum-niobium-tantalum master alloys and optimizing the production process, involves reacting fluoroniobic acid, fluorotantalic acid, and ammonia to produce niobium hydroxide and tantalum hydroxide precipitates. These precipitates are then oxidized and calcined to form oxides of niobium and tantalum, which are then used in a vacuum aluminothermic reaction to prepare high-purity aluminum-niobium-tantalum alloys. Simultaneously, ammonium fluoride can be co-produced, resulting in high raw material utilization. The vacuum aluminothermic reaction improves the uniformity of the master alloy composition and reduces the impurity content, especially the content of gaseous impurities O and N. Furthermore, this invention optimizes the production process and improves production continuity. Detailed Implementation

[0022] This invention provides a method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride, comprising the following steps:

[0023] Fluoroniobic acid, fluorotantalic acid and ammonia water are mixed and subjected to a precipitation reaction to obtain a precipitate product and an ammonium fluoride solution. The ammonium fluoride solution is then concentrated, cooled and crystallized, dehydrated and dried sequentially to obtain the ammonium fluoride. The precipitate product includes niobium hydroxide and tantalum hydroxide.

[0024] The precipitated product was successively dried and oxidized and calcined to obtain an oxidized material;

[0025] The oxide, aluminum powder, potassium chlorate and calcium fluoride are mixed and subjected to a vacuum aluminothermic reaction to obtain the high-purity aluminum-niobium-tantalum master alloy. The composition of the high-purity aluminum-niobium-tantalum master alloy, by mass percentage, includes: Nb 30.0-40.0%, Ta 10.0-15.0%, with the balance being Al and unavoidable impurities.

[0026] Unless otherwise specified, all raw materials used in this invention are commercially available products in the field.

[0027] This invention involves mixing fluoroniobic acid, fluorotantalic acid, and ammonia water to perform a precipitation reaction, obtaining a precipitate product and an ammonium fluoride solution. The ammonium fluoride solution is then sequentially concentrated, cooled for crystallization, dehydrated, and dried to obtain the ammonium fluoride. The precipitate product includes niobium hydroxide and tantalum hydroxide.

[0028] In this invention, the fluoroniobic acid preferably includes one or more of monofluoroniobic acid (H2NbO3F), difluoroniobic acid (HNbO2F2), trifluoroniobic acid (H2NbO2F3), tetrafluoroniobic acid (HNbOF4), pentafluoroniobic acid (H2NbOF5), hexafluoroniobic acid (HNbF6), and heptafluoroniobic acid (H2NbF7).

[0029] In this invention, the equation for the precipitation reaction of the fluoroniobic acid with ammonia is as follows:

[0030] H2NbO3F+NH3+2H2O=Nb(OH)5↓+NH4F

[0031] HNbO2F2+2NH3+3H2O=Nb(OH)5↓+2NH4F

[0032] H2NbO2F3+3NH3+3H2O=Nb(OH)5↓+3NH4F

[0033] HNbOF4+4NH3+4H2O=Nb(OH)5↓+4NH4F

[0034] H2NbOF5+5NH3+4H2O=Nb(OH)5↓+5NH4F

[0035] HNbF6+6NH3+5H2O=Nb(OH)5↓+6NH4F

[0036] H2NbF7+7NH3+5H2O=Nb(OH)5↓+7NH4F

[0037] In this invention, the fluorotantalic acid preferably includes one or more of monofluorotantalic acid (H2TaO3F), difluorotantalic acid (HTaO2F2), trifluorotantalic acid (H2TaO2F3), tetrafluorotantalic acid (HTaOF4), pentafluorotantalic acid (H2TaOF5), hexafluorotantalic acid (HTaF6), and heptafluorotantalic acid (H2TaF7).

[0038] In this invention, the equation for the precipitation reaction of fluorotantalic acid with ammonia is as follows:

[0039] H2TaO3F+NH3+2H2O=Ta(OH)5↓+NH4F

[0040] HTaO2F2+2NH3+3H2O=Ta(OH)5↓+2NH4F

[0041] H2TaO2F3+3NH3+3H2O=Ta(OH)5↓+3NH4F

[0042] HTaOF4+4NH3+4H2O=Ta(OH)5↓+4NH4F

[0043] H2TaOF5+5NH3+4H2O=Ta(OH)5↓+5NH4F

[0044] HTaF6+6NH3+5H2O=Ta(OH)5↓+6NH4F

[0045] H2TaF7+7NH3+5H2O=Ta(OH)5↓+7NH4F

[0046] In this invention, the mixing of fluoroniobic acid, fluorotantalic acid, and ammonia preferably includes the following steps: adding ammonia to the mixture of fluoroniobic acid and fluorotantalic acid. Based on Nb2O5 and Ta2O5, the concentration of fluoroniobic acid in the mixture is preferably 80-110 g / L, more preferably 96.5-105 g / L, and the concentration of fluorotantalic acid is preferably 60-100 g / L, more preferably 62.5-87.5 g / L.

[0047] In this invention, the concentration of the ammonia water is preferably 15wt% to 25wt%.

[0048] In this invention, the precipitation reaction preferably results in a pH value of 9 to 10 for the system.

[0049] After the precipitation reaction is completed, the present invention preferably places the obtained precipitate into a filter press for filtration and washing.

[0050] In this invention, the concentration is preferably vacuum concentration, the vacuum degree of the vacuum concentration is preferably -0.07 to -0.09 MPa, more preferably -0.075 MPa, the heating temperature is preferably 30 to 50°C, more preferably 40 to 45°C, and the solution is kept at a temperature until it is supersaturated and crystals appear.

[0051] In this invention, the vacuum concentration is preferably carried out in a vacuum concentration tank.

[0052] In this invention, the preferred temperature for cooling and crystallization is 5–20°C, the preferred stirring speed is 200–250 rpm, and the preferred time is 20–25 h.

[0053] In this invention, the cooling crystallization is preferably carried out in a PP material tank equipped with cooling water pipes. After cooling crystallization, the mother liquor after centrifugation is preferably returned to the vacuum concentration tank, and the obtained ammonium fluoride solid is placed in a drying tray, with each drying tray preferably containing 20-30 kg of material.

[0054] In this invention, the drying is preferably oven drying, the temperature of the oven drying is preferably 80-120°C, more preferably 90-100°C, and the time is preferably 6-8 hours, more preferably 7 hours.

[0055] In this invention, the water content of the ammonium fluoride is preferably 0.2% to 0.6%.

[0056] After obtaining the precipitated product, the present invention sequentially dries and oxidizes the precipitated product to obtain an oxidized material.

[0057] In this invention, the particle size of the precipitated product is preferably 0.1-2 mm, and the D50 is preferably 0.2-0.6 mm. Small particle size can increase the reaction rate and allow the reaction to proceed better.

[0058] In this invention, the sum of the mass contents of niobium hydroxide and tantalum hydroxide in the precipitated product is preferably ≥99%. Preferably, the precipitated product is sequentially dried and pulverized to achieve a particle size within the aforementioned range, and the drying temperature is preferably 70–80°C.

[0059] In this invention, the drying temperature is preferably 70-80°C.

[0060] In this invention, the niobium hydroxide and tantalum hydroxide can remove all water at temperatures above 400–450°C to produce niobium pentoxide and tantalum pentoxide, respectively. The reaction equation is as follows:

[0061] 2M(OH)5=M2O5+5H2O, M=Ta&Nb.

[0062] In this invention, the oxidative roasting is preferably carried out in a fluidized bed roasting furnace. The filler thickness of the fluidized bed roasting furnace is preferably 250-350 mm, the fluidized bed height is preferably 600-1200 mm, more preferably 700-1100 mm, the critical wind speed is preferably 0.6-0.9 m / s, more preferably 0.7-0.8 m / s, and the wind pressure is preferably 700-900 mmH2O, more preferably 800 mmH2O. Through the kinetic factors of the oxidative roasting, the oxidation reaction of niobium hydroxide and tantalum hydroxide is ensured to be more thorough.

[0063] In this invention, the oxidative roasting preferably also generates residual heat, which is preferably used to dry the oxidant, aluminum powder, potassium chlorate and calcium fluoride to prevent the introduction of H element into the matrix of the vacuum aluminothermic reaction and to shorten the drying time.

[0064] In this invention, the oxidative calcination temperature is preferably 600-800℃, more preferably 700-750℃, and the time is preferably 0.2-0.5h, more preferably 0.3-0.4h.

[0065] In this invention, the gas used for the oxidative roasting is preferably compressed air, which can meet the condition of a large amount of excess air and enhance the roasting process.

[0066] After the oxidation roasting is completed, the present invention preferably further includes natural cooling to 110-120°C to obtain the oxidized material.

[0067] After obtaining the oxide material, the present invention mixes the oxide material, aluminum powder, potassium chlorate and calcium fluoride, and performs a vacuum aluminothermic reaction to obtain the high-purity aluminum-niobium-tantalum master alloy; the composition of the high-purity aluminum-niobium-tantalum master alloy by mass percentage includes: Nb 30.0-40.0%, Ta 10.0-15.0%, and the balance being Al and unavoidable impurities.

[0068] In this invention, the mixing time is preferably 0.2 to 0.5 hours, more preferably 0.3 to 0.4 hours, the mixing is preferably stirring, and the stirring speed is preferably 15 to 50 r / min, more preferably 30 to 40 r / min, so as to make the materials mix evenly.

[0069] In this invention, by mass, the mixture obtained after mixing contains Al:Nb2O5:Ta2O5:KClO3:CaF2 in a ratio of 1:(0.48~0.71):(0.13~0.22):(0.23~0.25):(0.03~0.05). This ratio of raw materials can control the thermal effect value of the unit furnace charge in the aluminothermic reaction to be within the range of 650~670kJ / kg, ensuring that the vacuum aluminothermic reaction proceeds fully, the slag and the main metal are separated to the greatest extent, and at the same time, it will not cause too much damage to the copper crucible, thus extending the service life of the copper crucible.

[0070] In this invention, the crucible for the vacuum aluminothermic reaction is preferably made of copper, the diameter of the crucible is preferably 0.8–1.2 m, and the cooling water circulation rate is preferably 9–12 m³ / h. 3 The cooling water pressure is preferably 2.4–3.5 MPa, the inlet temperature is preferably 22–27°C, and the outlet temperature is preferably 45–50°C. Copper has good thermal conductivity, and the alloy liquid in contact with the crucible wall can achieve a large degree of subcooling. At the beginning of the vacuum aluminothermic reaction, it can mitigate the heat released by the copper crucible due to the aluminothermic reaction, and has little impact on the service life of the crucible. After the vacuum aluminothermic reaction is completed, it accelerates the rate at which the internal temperature of the alloy is conducted outward, reduces casting defects, and improves the alloy recovery rate. Controlling the inlet and outlet water temperature and pressure can ensure the heat transfer efficiency of the copper crucible.

[0071] In this invention, a mechanical vacuum pump is preferably turned on before the vacuum aluminothermic reaction, and the vacuum level is preferably controlled to be 200-300 Pa to control the entry of gaseous impurities such as O and N into the intermediate alloy.

[0072] In this invention, the preferred ignition method for the vacuum aluminothermic reaction is electric heating, which ensures that the vacuum environment remains stable and does not fluctuate during the ignition process.

[0073] In this invention, the vacuum aluminothermic reaction time is preferably 40-70 seconds. The Roots vacuum pump is turned on and the vacuum degree is preferably controlled to be 5-10 Pa to prevent gas from escaping during the vacuum aluminothermic reaction as the state of matter changes, thus creating a high-pressure zone between the intermediate alloy and the slag, which would affect the separation effect of the slag and the intermediate alloy.

[0074] In this invention, after the vacuum aluminothermic reaction is completed, the alloy ingot cooling time is preferably ≥4h to ensure that the intermediate alloy is completely solidified and that the surface temperature of the intermediate alloy does not accelerate the oxidation or nitriding rate when in contact with air.

[0075] Unless otherwise stated, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; other experimental methods and technical means not specifically mentioned herein refer to experimental methods and technical means commonly used by one of ordinary skill in the art.

[0076] To better illustrate the content of this application, numerous specific details are provided in the following detailed embodiments. Those skilled in the art should understand that this application can be implemented even without certain specific details. In the embodiments, some methods, means, instruments, and devices well-known to those skilled in the art are not described in detail in order to highlight the main points of this application.

[0077] Without conflict, the technical features disclosed in the embodiments of this application can be combined arbitrarily, and the resulting technical solution belongs to the content disclosed in the embodiments of this application.

[0078] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0079] Example 1

[0080] A method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride includes the following steps:

[0081] I. Preparation of niobium hydroxide and tantalum hydroxide precipitates

[0082] Ammonia water (15wt%) was poured into 260L of H2NbF7 solution with a concentration of 96.5g Nb2O5 / L and 87.5L of H2TaF7 solution with a concentration of 80.0g Ta2O5 / L until the pH value reached 9. The mixture was stirred continuously during the reaction. After the reaction was completed, the stirring was stopped and the mixture was allowed to stand for 10 minutes. The precipitate was then filtered and washed using a filter press to obtain 33.9kg of niobium hydroxide precipitate and 8.85kg of tantalum hydroxide.

[0083] II. Preparation of Ammonium Fluoride Crystals

[0084] The filtered and precipitated liquid was placed into a vacuum concentrator for vacuum concentration. The condenser and vacuum pump were turned on to achieve a vacuum of -0.075 MPa. The heating switch was turned on to set the temperature to 45°C. After holding at this temperature for 30 minutes, the solution was transferred into a condenser. The condenser was turned on to set the condenser temperature to 5°C. During this period, the stirring speed was 200 rpm for 20 hours. After 24 hours, the solution was centrifuged and dehydrated. The solution was returned to the vacuum concentrator. The ammonium fluoride crystals were dried at 90°C for 7 hours, yielding 14.24 kg of ammonium fluoride crystals, with a first-pass yield of 25%.

[0085] III. Boiling roasting

[0086] Niobium hydroxide and tantalum hydroxide precipitates were dried, pulverized, and then spread evenly on the fluidized bed of a calcining furnace. The fluidized bed height was controlled at 700 mm, the critical wind speed at 0.7 m / s, the blowing pressure at 800 mmH2O, the precipitate particle size at 1 mm, the calcination temperature at 700 ℃, and the calcination time at 0.4 h, to obtain 32.0 kg of a mixture of niobium pentoxide and tantalum pentoxide with a mass ratio of 1:0.28.

[0087] IV. Vacuum Aluminothermic Reaction

[0088] Niobium pentoxide, tantalum pentoxide, 41.0 kg of aluminum powder, 10.2 kg of potassium chlorate, and 2 kg of calcium fluoride were mixed for 0.5 hours at a mixer speed of 30 rpm. After mixing, the material was placed into a 0.8 m diameter copper crucible. Before powering on, the water cooling system, power system, and electrical system of the vacuum aluminothermic furnace were checked to ensure they were operating normally and that the vacuum environment inside the furnace met the requirements. The cooling water circulation system was turned on, with an outlet water pressure of 2.4 MPa and a cooling water circulation rate of 9 m³ / h. 3 / h. Charge is added to the furnace, the furnace lid is closed, and the mechanical vacuum pump is turned on to evacuate for 15 minutes. When the vacuum level inside the furnace reaches 200 Pa, the aluminothermic reaction is ignited by electric heating. After the reaction reaches 45 seconds, the Roots vacuum pump is turned on to bring the vacuum level inside the furnace down to 5-10 Pa. Cooling time begins one minute after the reaction, and the vacuum environment inside the furnace is maintained during the cooling process. After 5 hours, the aluminum-niobium-tantalum master alloy is removed, with an ingot weight of 40.5 kg.

[0089] The ammonium fluoride samples obtained in this embodiment were analyzed, as shown in Table 1. Two points each from the top, middle, and bottom of the aluminum-niobium-tantalum master alloy ingot were sampled and analyzed, numbered in the same order as the sampling (from top to bottom), as shown in Table 2. Tables 1 and 2 show that the ammonium fluoride has high purity and low water content; the aluminum-niobium-tantalum alloy exhibits good uniformity, minimal component segregation, and low impurity content, especially with gaseous impurities controlled at extremely low levels, resulting in high alloy purity.

[0090] Table 1. Chemical composition (mass content) of ammonium fluoride in Example 1

[0091] Ammonium fluoride content (%) Moisture content (%) Free acid (%) Fluorosilicon (%) Other impurities (%) 98.1 0.2 0.6 0.2 0.9

[0092] Table 2 Chemical composition of aluminum-niobium-tantalum master alloy from different sampling locations in Example 1

[0093]

[0094] Example 2

[0095] A method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride includes the following steps:

[0096] I. Preparation of niobium hydroxide and tantalum hydroxide precipitates

[0097] Ammonia water (15wt%) was poured into 362.3L of HNbF6 solution with a concentration of 105g Nb2O5 / L and 131.2L of HTaF6 solution with a concentration of 62.5g Ta2O5 / L until the pH value reached 9. The mixture was stirred continuously during the reaction. After the reaction was completed, the stirring was stopped and the mixture was allowed to stand for 10 minutes. The precipitate was then filtered and washed using a filter press to obtain 51.2kg of niobium hydroxide precipitate and 10.1kg of tantalum hydroxide.

[0098] II. Preparation of Ammonium Fluoride Crystals

[0099] The filtered and precipitated liquid was placed into a vacuum concentrator for vacuum concentration. The condenser and vacuum pump were turned on to achieve a vacuum of -0.075 MPa. The heating switch was turned on to set the temperature to 45°C and maintained at this temperature for 30 minutes. The solution was then transferred to a condenser tank, and the condenser was turned on to maintain a condenser temperature of 20°C. The stirring speed was 200 rpm for 20 hours. After 24 hours, the solution was centrifuged and filtered. The solution was returned to the vacuum concentrator, and the ammonium fluoride crystals were dried at 90°C for 7 hours to obtain 16.87 kg of ammonium fluoride crystals, with a first-pass yield of 23.5%.

[0100] III. Boiling roasting

[0101] Niobium hydroxide and tantalum hydroxide precipitates were dried, pulverized, and then spread evenly on the fluidized bed of a calcining furnace. The fluidized bed height was controlled at 700 mm, the critical wind speed at 0.7 m / s, the blowing pressure at 800 mmH2O, the precipitate particle size at 1 mm, the calcination temperature at 700℃, and the calcination time at 0.4 h, yielding 38.0 kg of niobium pentoxide and 8.15 kg of tantalum pentoxide.

[0102] IV. Vacuum Aluminothermic Reaction

[0103] Niobium pentoxide, tantalum pentoxide, 57.05 kg of aluminum powder, 13.8 kg of potassium chlorate, and 2 kg of calcium fluoride were mixed for 0.5 hours at a mixer speed of 30 rpm. After mixing, the material was placed into a 0.8 m diameter copper crucible. Before powering on, the water cooling system, power system, and electrical system of the vacuum aluminothermic furnace were checked to ensure they were operating normally and that the vacuum environment inside the furnace met the requirements. The cooling water circulation system was turned on, with an outlet water pressure of 2.4 MPa and a cooling water circulation rate of 9 m³ / h. 3 / h. Charge is added to the furnace, the furnace lid is closed, and the mechanical vacuum pump is turned on to evacuate for 15 minutes. When the vacuum level inside the furnace reaches 200 Pa, the aluminothermic reaction is ignited by electric heating. After the reaction reaches 45 seconds, the Roots vacuum pump is turned on to bring the vacuum level inside the furnace down to 5-10 Pa. Cooling time begins one minute after the reaction, and the vacuum environment inside the furnace is maintained during the cooling process. After 5 hours, the aluminum-niobium-tantalum master alloy ingot is removed, weighing 58.5 kg.

[0104] The ammonium fluoride samples obtained in this embodiment were analyzed, as shown in Table 3. Two points each from the top, middle, and bottom of the aluminum-niobium-tantalum master alloy ingot were sampled and analyzed, numbered in the same order as the sampling (from top to bottom), as shown in Table 4. Tables 3 and 4 show that the ammonium fluoride has high purity and low water content; the aluminum-niobium-tantalum alloy exhibits good uniformity, minimal component segregation, and low impurity content, especially with gaseous impurities controlled at extremely low levels, resulting in high alloy purity.

[0105] Table 3 Chemical composition (mass content) of ammonium fluoride in Example 2

[0106] Ammonium fluoride content (%) Moisture content (%) Free acid (%) Fluorosilicon (%) Other impurities (%) 97.7 0.3 0.7 0.2 1.1

[0107] Table 4 Chemical composition of aluminum-niobium-tantalum master alloy from different sampling locations in Example 2

[0108]

[0109] Comparative Example 1

[0110] 21.45 kg of niobium pentoxide, 42.96 kg of aluminum granules, 5.83 kg of tantalum pentoxide, 2 kg of calcium fluoride, and 10.8 kg of potassium chlorate were mixed for 0.5 h at a mixer speed of 30 r / min. After mixing, the material was put into a smelting furnace and ignited with magnesium strips for 30 s. After cooling for 24 h, the aluminum-niobium-tantalum alloy was obtained, with an ingot weight of 44.5 kg.

[0111] Two points each from the top, middle, and bottom of the aluminum-niobium-tantalum master alloy ingot obtained in this comparative example were sampled and analyzed. The numbering order was the same as the sampling order (from top to bottom), as shown in Table 5. Table 5 shows that, compared with the aluminum-niobium-tantalum alloy prepared by the vacuum aluminothermic method, the aluminum-niobium-tantalum alloy produced by furnace ignition smelting has poor uniformity and severe compositional segregation. The Si impurity content is high due to the influence of the crucible, and the atmospheric atmosphere significantly increases gaseous impurities. Niobium pentoxide and tantalum pentoxide prepared using fluoroniobic acid and fluorotantalic acid as raw materials have high purity and can also co-produce ammonium fluoride, thus optimizing the production process.

[0112] Table 5 Chemical composition of aluminum-niobium-tantalum master alloy from different sampling locations in Comparative Example 1

[0113]

[0114] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing high-purity aluminum-niobium-tantalum master alloy and co-producing ammonium fluoride, characterized in that, Includes the following steps: Fluoroniobic acid, fluorotantalic acid, and ammonia are mixed and subjected to a precipitation reaction to obtain a precipitate and an ammonium fluoride solution. The ammonium fluoride solution is then concentrated, cooled for crystallization, dehydrated, and dried sequentially to obtain the ammonium fluoride. The precipitate includes niobium hydroxide and tantalum hydroxide. The mixing of fluoroniobic acid, fluorotantalic acid, and ammonia includes the following steps: adding ammonia to the mixture of fluoroniobic acid and fluorotantalic acid. Based on Nb₂O₅ and Ta₂O₅, the concentration of fluoroniobic acid in the mixture is 80-110 g / L, and the concentration of fluorotantalic acid is 60-100 g / L. The particle size of the precipitate is 0.1-2 mm, and the D50 is 0.2-0.6 mm. The precipitated product is dried and oxidized in sequence to obtain an oxidized material; the oxidized roasting is carried out in a fluidized bed roasting furnace, the fluidized bed roasting furnace has a packing thickness of 250~350mm, a fluidized bed height of 600~1200mm, a critical wind speed of 0.6~0.9m / s, and a wind pressure of 700~900mmH2O. The oxide, aluminum powder, potassium chlorate, and calcium fluoride are mixed and subjected to a vacuum aluminothermic reaction to obtain the high-purity aluminum-niobium-tantalum master alloy. The high-purity aluminum-niobium-tantalum master alloy comprises, by mass percentage: Nb 30.0~40.0%, Ta 10.0~15.0%, with the balance being Al and unavoidable impurities. The mixture obtained after mixing the oxide, aluminum powder, potassium chlorate, and calcium fluoride has a mass ratio of Al:Nb₂O₅:Ta₂O₅:KClO₃:CaF₂ = 1:(0.48~0.71):(0.13~0.22):(0.23~0.25):(0.03~0.05). The vacuum aluminothermic reaction takes 40~70 s and the vacuum level is 5~10 Pa. The oxidation roasting also generates residual heat, which is used to dry the oxidant, aluminum powder, potassium chlorate and calcium fluoride, preventing the introduction of hydrogen elements into the matrix of the vacuum aluminothermic reaction and shortening the drying time.

2. The method according to claim 1, characterized in that, The fluoroniobic acid includes one or more of monofluoroniobic acid, difluoroniobic acid, trifluoroniobic acid, tetrafluoroniobic acid, pentafluoroniobic acid, hexafluoroniobic acid, and heptafluoroniobic acid; the fluorotantalic acid includes one or more of monofluorotantalic acid, difluorotantalic acid, trifluorotantalic acid, tetrafluorotantalic acid, pentafluorotantalic acid, hexafluorotantalic acid, and heptafluorotantalic acid.

3. The method according to claim 1, characterized in that, The precipitation reaction brings the pH of the system to 9-10.

4. The method according to claim 1, characterized in that, The oxidation calcination temperature is 600~800℃ and the time is 0.2~0.5h.

5. The method according to claim 1, characterized in that, The gas used in the oxidative roasting is compressed air.

6. The method according to claim 1, characterized in that, The crucible for the vacuum aluminothermic reaction is made of copper, with a diameter of 0.8~1.2m and a cooling water circulation rate of 9~12m³. 3 The cooling water pressure is 2.4~3.5MPa, the inlet temperature is 22~27℃, and the outlet temperature is 45~50℃.

Images