A method for recycling Lindqvist-type polyacid to prepare aluminum-molybdenum-vanadium intermediate alloy

Abstract

The present application relates to the technical field of metal material, and particularly relates to a method for preparing aluminum-molybdenum-vanadium intermediate alloy by recycling Lindqvist-type polyacid. The Lindqvist-type polyacid is reacted with quinoline to obtain polyacid quinoline precipitate, and the polyacid quinoline precipitate is separated and cleaned. Then, the polyacid quinoline precipitate is dried and crushed, and is subjected to oxidation roasting in a boiling roasting furnace to obtain a mixture of molybdenum trioxide and vanadium pentoxide. The mixture of molybdenum trioxide and vanadium pentoxide is mixed with aluminum powder and calcium fluoride, and vacuum aluminothermic reaction is performed to obtain the aluminum-molybdenum-vanadium intermediate alloy. The present application proposes a recycling treatment method for Lindqvist-type polyacid, and the recycling rate can reach more than 90%. The heat released by oxidation roasting of the polyacid quinoline precipitate is used to dry the obtained polyacid quinoline precipitate, aluminum powder and calcium fluoride, so that the drying process is shortened and continuous production is facilitated.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, and in particular to a method for preparing aluminum-molybdenum-vanadium master alloys by recycling Lindqvist-type polyacids. Background Technology

[0002] Lindqvist-type polyacids, as a type of metal polyacid, have found practical applications in many catalytic fields, such as esterification, alkylation, and olefin hydration, due to their excellent redox stability and strong Bronsted acidity. However, homogeneous catalytic systems based on Lindqvist-type polyacids suffer from drawbacks such as catalyst deactivation (catalyst poisoning) after a certain reaction time, difficulty in recovery, and significant environmental pollution and damage caused by heavy metal cations such as Mo and V.

[0003] The current production method for aluminum-molybdenum-vanadium master alloys mainly involves ladle ignition smelting. This method uses Al as a reducing agent and MoO3 (or MoO2) and V2O5 as oxidizing agents in an open environment, utilizing the self-generating heat of the metallothermic reduction reaction to achieve the smelting of the master alloy. For example, CN1629346A discloses an aluminum-molybdenum-vanadium master alloy and its preparation method, which involves ladle ignition smelting of Al powder with MoO3, V2O5, CaF2, and KClO3, resulting in a stable reaction and good alloying. Another example is CN116005043A, which discloses a method for preparing an aluminum-molybdenum-vanadium-iron-silicon master alloy, where the reaction rate is reduced by pelletizing the molybdenum and vanadium sources to obtain a uniformly composed alloy. Finally, CN110343929A discloses an aluminum-molybdenum-vanadium master alloy and its preparation method, which involves preparing aluminum-molybdenum and aluminum-vanadium alloys separately using Al powder with MoO3 and V2O5, and melting them in a vacuum medium-frequency furnace to obtain an alloy with uniform composition and low impurity content. However, the raw materials for aluminum, molybdenum, and vanadium are currently MoO3 (or MoO2) and V2O5, which are expensive; and the raw materials need to be dried before the reaction, resulting in a long smelting cycle and a large time span.

[0004] Therefore, the comprehensive recycling and utilization of Lindqvist-type polyacids, the broadening of the selection range of aluminum-molybdenum-vanadium alloy raw materials, and the shortening of the production cycle are urgent problems to be solved, which are also in line with the principles of green chemistry and clean chemistry. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing aluminum-molybdenum-vanadium master alloys by recovering Lindqvist-type polyacids. The focus is on the recovery and utilization of Lindqvist-type polyacids and broadening the selection range of raw materials for aluminum-molybdenum-vanadium master alloys. The method involves separating the deactivated Lindqvist-type polyacids by precipitation, oxidizing and roasting them into oxides of molybdenum and vanadium, and then using a vacuum aluminothermic furnace to prepare the aluminum-molybdenum-vanadium alloy. Simultaneously, the heat from the oxidation and roasting can be used to dry the raw materials, shortening the drying time, improving the uniformity of the master alloy composition, and reducing the impurity content in the master alloy, especially the content of gaseous impurities O and N.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing aluminum-molybdenum-vanadium master alloys by recycling Lindqvist-type polyacids includes the following steps:

[0008] (1) The Lindqvist type polyacid was reacted with quinoline to obtain polyacid quinoline precipitate, and the polyacid quinoline precipitate was separated and cleaned.

[0009] (2) The polyoxoquinoline precipitate was dried, pulverized and then oxidized and roasted in a fluidized bed roaster to obtain a mixture of molybdenum trioxide and vanadium pentoxide.

[0010] (3) The mixture of molybdenum trioxide and vanadium pentoxide is mixed with aluminum powder and calcium fluoride and subjected to vacuum aluminothermic reaction to obtain the aluminum-molybdenum-vanadium intermediate alloy.

[0011] Preferably, the aluminum-molybdenum-vanadium master alloy comprises, by mass percentage: Mo 40.0-43.0%, V 38-41%, and Al as the balance; and also includes unavoidable impurities O≤0.02%, N≤0.02%, Fe≤0.10%, Si≤0.10%, and C≤0.20%.

[0012] Preferably, the general formula of the Lindqvist type polyacid is H n [X x M y O 19 ]; where, X&M=V, Mo; x+y=6; n=2-8.

[0013] Furthermore, the Lindqvist type polyacid is H4[V2Mo4O] 19 H2Mo6O 19 H8V6O 19 The reaction involves one or more of the following: the mass ratio of the Lindqvist polyacid to quinoline is 1:(2.8–3.5), and the reaction time is 15–25 min.

[0014] Preferably, in step (2), the drying temperature of the polyacid quinoline precipitate is 70℃-80℃, and the polyacid quinoline in the precipitate after pulverization is ≥99% by mass, the particle size is 1~5mm, and the D50 is 2~3mm.

[0015] Furthermore, in the oxidation roasting process of step (2), the filler thickness is 300-400 mm, the boiling layer height is 800-1400 mm, the critical wind speed is 0.7-1.1 m / s, the wind pressure is 800-1000 mmH2O, the roasting temperature is 750-950℃, and the roasting time is 0.2-0.5 h. By controlling the kinetic factors of polyacid boiling roasting, the oxidation reaction of metal polyacids is ensured to be more thorough. At the same time, the heat of oxidation roasting is used to dry the polyacid quinoline precipitate, aluminum powder, and calcium fluoride, preventing the introduction of H elements into the matrix and shortening the drying time.

[0016] Furthermore, the gas used in the oxidative roasting is oxygen-enriched air with an oxygen content of 45% to 55%. The oxygen content in the gas can ensure that polyacids are completely converted into corresponding oxides during the boiling roasting process, and quinoline and other organic residues are also converted into gases such as carbon dioxide and nitrogen dioxide and discharged.

[0017] It should be noted that the polyacid quinoline precipitate will decompose into polyacid and quinoline at 150℃, and the polyacid will be completely converted into the corresponding metal oxide at 600℃.

[0018] Preferably, in step (3), molybdenum trioxide and vanadium pentoxide are cooled to 90-120°C, and the mixing time with aluminum powder and calcium fluoride is 0.25-1h, with a stirring speed of 15-50r / min, so that the materials are mixed evenly; and the mass ratio of molybdenum trioxide and vanadium pentoxide, aluminum powder and calcium fluoride is (0.82-0.95):1:(1.04-1.15):(0.13-0.15), controlling the heat effect value of the unit furnace charge in the aluminothermic reaction to be between 750-950kJ / kg, so as to ensure that the vacuum aluminothermic reaction is fully carried out and the slag and the main metal are separated to the greatest extent.

[0019] Furthermore, the copper crucible has a diameter of 1–1.5 m and a cooling water circulation rate of 10–15 m³ / h. 3 The cooling water pressure is 3–3.5 MPa, the inlet temperature is 20–25°C, and the outlet temperature is 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 aluminothermic reaction, it can mitigate the impact of the heat released by the copper crucible due to the aluminothermic reaction on the crucible's service life; after the aluminothermic reaction is completed, it accelerates the rate of heat conduction from the inside of the alloy to the outside, 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.

[0020] Furthermore, before the vacuum aluminothermic reaction, a mechanical vacuum pump is turned on to control the vacuum level to 180-200 Pa, which can control the entry of gaseous impurities such as O and N into the intermediate alloy; and the ignition method of the vacuum aluminothermic reaction is electric heating, which ensures that the vacuum environment is stable and does not fluctuate during the ignition process.

[0021] Furthermore, the vacuum aluminothermic reaction time is 15-40 seconds. The Roots vacuum pump is turned on and the vacuum degree is controlled at 1-5 Pa to prevent gas from escaping during the 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.

[0022] Furthermore, after the vacuum aluminothermic reaction is completed, the alloy ingot is cooled under vacuum for ≥4 hours 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.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention proposes a method for recovering Lindqvist-type polyacids, which effectively reuses the metal elements such as Mo and V to prepare pure molybdenum trioxide and vanadium pentoxide, with a recovery rate of over 90%. Furthermore, the invention utilizes vacuum aluminothermic reduction technology to reduce alloy component segregation and gaseous impurity content. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] To better understand the present invention, the following embodiments are provided for further detailed description of the present invention, but they should not be construed as limiting the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above-described invention are also considered to fall within the protection scope of the present invention.

[0030] Example 1

[0031] A method for preparing aluminum-molybdenum-vanadium master alloys by recycling Lindqvist-type polyacids includes the following steps:

[0032] I. Preparation of quinoline polyacid precipitate

[0033] The chemical reaction equation for polyacids and quinoline is:

[0034] H n [X x M y O 19 ]+3C9H7N+H2O=(C9H7N)3H n [X x M y O 19 H2O↓

[0035] 32 kg of H4[V2Mo4O 19 ] and 22kg of H8V6O 19 The polyacid waste liquid (content of 88%) was placed in a molten pool, and quinoline was added at a reaction mass ratio of 1:3. The stirrer was turned on, and the quinoline reacted with the polyacid to form polyacid quinoline precipitate. After reacting for 15 minutes, the stirring was stopped, and the mixture was allowed to stand for 30 minutes. After filtration and washing, the precipitate weighed 75 kg.

[0036] II. Boiling roasting

[0037] The corresponding calcination decomposition reaction equation is:

[0038] 4(C9H7N)3H4[V2Mo4O 19 ]·H2O+141O2=4V2O5+16MoO3+54H2O+108CO2+12NO2

[0039] 4(C9H7N)3H8V6O 19 ·H2O+141O2=12V2O5+62H2O+108CO2+12NO2

[0040] 75 kg of polyoxoquinoline precipitate was dried, pulverized, and spread evenly on the fluidized bed of a calcining furnace. The fluidized bed height was controlled at 0.8 m, the critical wind speed at 0.8 m / s, the blowing pressure at 850 mmH2O, the precipitate particle size at 1 mm, the calcination temperature at 850 ℃, the calcination time at 0.4 h, and the oxygen concentration in the oxygen-enriched air at 46%. A mixture of molybdenum trioxide and vanadium pentoxide with a mass of 40.0 kg was obtained, with a ratio of approximately 0.87:1 and a recovery rate of 91%.

[0041] III. Vacuum Aluminothermic Reaction

[0042] The mixture was combined with 23 kg of aluminum powder and 3.0 kg of calcium fluoride for 0.5 hours at a mixer speed of 30 r / min. After mixing, the material was placed into a 1 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 then turned on, with an outlet water pressure of 3.2 MPa and a circulation rate of 12 m³ / min. 3 / h. Charge is added to the furnace, the furnace lid is closed, and the mechanical vacuum pump is turned on. Vacuuming is carried out for 15 minutes, reaching a vacuum level of 200 Pa. The aluminothermic reaction is ignited by electric heating. After 30 seconds of reaction, the Roots vacuum pump is turned on to bring the furnace vacuum level down to 1-5 Pa. Cooling time begins one minute after the reaction, maintaining a vacuum environment within the furnace during the cooling process. After 5 hours, the aluminum-molybdenum-vanadium master alloy ingot is removed, weighing 29.7 kg.

[0043] Two points each from the top, middle, and bottom of the aluminum-molybdenum-vanadium intermediate alloy ingot obtained in this embodiment were selected for sampling and analysis. The numbering order was the same as the sampling order (from top to bottom).

[0044] Table 1. Chemical composition of aluminum-molybdenum-vanadium master alloy from different sampling locations in Example 1.

[0045]

[0046] As shown in the table above, aluminum-molybdenum-vanadium alloys exhibit good uniformity, minimal component segregation, and low impurity content, especially with gaseous impurities controlled at extremely low levels, resulting in high alloy purity.

[0047] Example 2

[0048] A method for preparing aluminum-molybdenum-vanadium master alloys by recycling Lindqvist-type polyacids includes the following steps:

[0049] I. Preparation of quinoline polyacid precipitate

[0050] The chemical reaction equation for the polyacid and quinoline is:

[0051] H n [X x M y O 19]+3C9H7N+H2O=(C9H7N)3H n [X x M y O 19 H2O↓

[0052] 23.6 kg of H2Mo6O 19 And 29.5kg of H8V6O 19 The polyacid waste liquid (content of 88%) was placed in a molten pool, and quinoline was added at a reaction mass ratio of 1:3. The stirrer was turned on, and the quinoline reacted with the polyacid to form polyacid quinoline precipitate. After reacting for 15 minutes, the stirring was stopped, and the mixture was allowed to stand for 30 minutes. After filtration and washing, the precipitate weighed 73.4 kg.

[0053] II. Boiling roasting

[0054] The corresponding calcination decomposition reaction equation is:

[0055] 4(C9H7N)3H8V6O 19 ·H2O+141O2=12V2O5+62H2O+108CO2+12NO2

[0056] 4*(C9H7N)3H2Mo6O 19 ·H2O+141O2=24MoO3+50H2O+108CO2+12NO2

[0057] 73.4 kg of polyoxoquinoline precipitate was dried, pulverized, and spread evenly on the fluidized bed of a calcining furnace. The fluidized bed height was controlled at 0.8 m, the critical wind speed at 0.8 m / s, the blast pressure at 850 mmH2O, the precipitate particle size at 1 mm, the calcination temperature at 850 °C, the calcination time at 0.4 h, and the oxygen concentration in the oxygen-enriched air at 46%. A mixture of molybdenum trioxide and vanadium pentoxide with a ratio of approximately 0.89:1 was obtained, with a recovery rate of 92%.

[0058] III. Vacuum Aluminothermic Reaction

[0059] The mixture was combined with 23 kg of aluminum powder and 3.0 kg of calcium fluoride for 0.5 hours at a mixer speed of 30 r / min. After mixing, the material was placed into a 1 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 then turned on, with an outlet water pressure of 3.2 MPa and a circulation rate of 12 m³ / min. 3 / h. Charge is added to the furnace, the furnace lid is closed, and the mechanical vacuum pump is turned on. Vacuuming is carried out for 15 minutes, reaching a vacuum level of 200 Pa. The aluminothermic reaction is ignited by electric heating. After 30 seconds of reaction, the Roots vacuum pump is turned on to bring the furnace vacuum level down to 1-5 Pa. Cooling time begins one minute after the reaction, maintaining a vacuum environment within the furnace during the cooling process. After 5 hours, the aluminum-molybdenum-vanadium master alloy ingot is removed, weighing 28.6 kg.

[0060] Two points each from the top, middle, and bottom of the aluminum-molybdenum-vanadium intermediate alloy ingot obtained in this embodiment were selected for sampling and analysis. The sampling order was the same as that of the ingot (from top to bottom).

[0061] Table 2 Chemical composition of aluminum-molybdenum-vanadium master alloy from different sampling locations in Example 2

[0062]

[0063] As shown in the table above, aluminum-molybdenum-vanadium alloys exhibit good uniformity, minimal component segregation, and low impurity content, especially with gaseous impurities controlled at extremely low levels, resulting in high alloy purity.

[0064] To further demonstrate the beneficial effects of the present invention and to better understand it, the technical features disclosed in the present invention are further illustrated by the following comparative examples, but these should not be construed as limiting the present invention. Other improvements made by those skilled in the art based on the above description of the invention, without inventive effort, are also considered to fall within the protection scope of the present invention.

[0065] Comparative Example 1

[0066] 79 kg of vanadium pentoxide, 80 kg of aluminum granules, 60 kg of molybdenum dioxide and 5 kg of calcium fluoride 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 seconds. After cooling for 24 hours, the aluminum-molybdenum-vanadium alloy was obtained with an ingot weight of 107.0 kg.

[0067] Two points each from the top, middle, and bottom of the aluminum-molybdenum-vanadium intermediate alloy ingot obtained in this comparative example were selected for sampling and analysis. The numbering order was the same as the sampling order (from top to bottom).

[0068] Table 3 Chemical composition of aluminum-molybdenum-vanadium master alloy from different sampling locations in Comparative Example 1

[0069]

[0070]

[0071] As shown in the table above, compared with the aluminum-molybdenum-vanadium alloy prepared by the vacuum aluminothermic method, the aluminum-molybdenum-vanadium alloy produced by furnace ignition smelting has poor uniformity, serious component segregation, and significantly increased Si impurities and gaseous impurities. This is due to the crucible and atmospheric atmosphere. From the perspective of raw materials, the vanadium pentoxide and molybdenum trioxide prepared by Lindqvist-type polyacid recovery have good purity and are less different from those sold on the market.

[0072] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing aluminum-molybdenum-vanadium master alloy by recovering Lindqvist-type polyacids, characterized in that, Includes the following steps: (1) The Lindqvist type polyacid is reacted with quinoline to obtain polyacid quinoline precipitate, and the polyacid quinoline precipitate is separated and cleaned for later use; (2) The polyoxoquinoline precipitate prepared in step (1) is dried, pulverized and then oxidized and roasted in a fluidized bed roasting furnace to obtain a mixture of molybdenum trioxide and vanadium pentoxide; (3) The mixture of molybdenum trioxide and vanadium pentoxide prepared in step (2) is mixed with aluminum powder and calcium fluoride and subjected to vacuum aluminothermic reaction to obtain the aluminum-molybdenum-vanadium intermediate alloy. The aluminum-molybdenum-vanadium master alloy, by mass percentage, comprises: Mo 40.0–43.0%, V 38–41%, with Al as the balance; and also includes unavoidable impurities of O ≤ 0.02%, N ≤ 0.02%, Fe ≤ 0.10%, Si ≤ 0.10%, and C ≤ 0.20%. The Lindqvist type polyacid is H4[V2Mo4O] 19 H2Mo6O 19 H8V6O 19 The reaction involves one or more of the following: the mass ratio of the Lindqvist polyacid to quinoline is 1:(2.8~3.5), and the reaction time is 15~25 min. In the oxidation roasting process of step (2), the filler thickness is 300~400 mm, the boiling layer height is 800~1400 mm, the critical wind speed is 0.7~1.1 m / s, the wind pressure is 800~1000 mmH2O, the roasting temperature is 750~950℃, and the roasting time is 0.2~0.5 h; and the gas used for oxidation roasting is oxygen-enriched air with an oxygen content of 45%~55%. In step (3), molybdenum trioxide and vanadium pentoxide are cooled to 90~120℃, and the mixing time with aluminum powder and calcium fluoride is 0.25~1 h, and the stirring speed is 15~50 r / min; and the mass ratio of molybdenum trioxide and vanadium pentoxide, aluminum powder and calcium fluoride is (0.82~0.95):1:(1.04~1.15):(0.13~0.15); In step (3), the vacuum aluminothermic reaction time is 15-40 s, the reaction crucible is made of copper, the crucible diameter is 1-1.5 m, and the cooling water circulation rate is 10-15 m³. 3 The cooling water pressure is 3~3.5 MPa, the inlet temperature is 20~25℃, and the outlet temperature is 45~50℃.

2. The method for preparing aluminum-molybdenum-vanadium master alloy by recovering Lindqvist-type polyacids according to claim 1, characterized in that, In step (2), the drying temperature of the polyacid quinoline precipitate is 70℃-80℃, and the polyacid quinoline in the precipitate after pulverization is ≥99% by mass, with a particle size of 1~5 mm and a D50 of 2~3 mm.

3. The method for preparing aluminum-molybdenum-vanadium master alloy by recovering Lindqvist-type polyacids according to claim 1, characterized in that, Before the vacuum aluminothermic reaction, the vacuum level inside the furnace is controlled at 180~200 Pa, and during the reaction, the vacuum level inside the furnace is controlled at 1~5 Pa.

4. The method for preparing aluminum-molybdenum-vanadium master alloy by recovering Lindqvist-type polyacids according to claim 1, characterized in that, After the vacuum aluminothermic reaction is completed, the alloy ingot is cooled under vacuum for ≥4 h.

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