A method for preparing aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate

Abstract

The present invention relates to a method for preparing aluminum-vanadium alloy by aluminothermic reduction of sodium metavanadate, which comprises the following steps: S1, using powdered sodium metavanadate as a raw material, adding aluminum powder and calcium oxide, and mixing evenly; S2, pressing the mixed material into a columnar mass; S3, placing the mass into a tubular furnace, and performing a period of high-temperature insulation in an inert gas atmosphere, so as to obtain a mixture of an aluminum-vanadium master alloy and calcium aluminate-based slag. The method of the present invention adopts aluminothermic reduction to prepare an aluminum-vanadium master alloy, and its raw material is sodium metavanadate, an intermediate in the process of treating vanadium slag. The cost of using it as a raw material is lower, and the process of treating vanadium slag is shortened, avoiding the environmental pollution problem generated in the process of preparing V2O5 by sodium metavanadate using a traditional process, and obtaining an aluminum-vanadium master alloy in one step by a more efficient aluminothermic reduction method, thereby realizing efficient short-range green utilization of resources.

Description

Technical Field

[0001] The invention relates to a method for preparing an aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate, and belongs to the technical field of metallurgy. Background Art

[0002] Refractory metal vanadium has good physical and chemical properties such as high temperature strength, corrosion resistance, and high hardness. It is an indispensable and important raw material in my country's modernization construction. At the same time, vanadium, as an important alloying element, can significantly improve the performance of the alloy and play an irreplaceable role in the steel, aerospace and nuclear industries. For example, metal vanadium as an additive can significantly improve the comprehensive mechanical properties and corrosion resistance of steel. About 85% of vanadium is used in the processing of high-strength steel. Aluminum-vanadium alloys are also widely used in military and civilian fields due to their high working temperature, strong corrosion resistance, and high specific strength. Especially in the field of titanium alloys, aluminum-vanadium alloys are an important component of Ti-6Al-4V and Ti-8Al-Mo-V based alloys, and play a huge role in aircraft engines and high-speed vehicle frames. However, the main process for the industrial production of metal vanadium and its alloys is still the thermal reduction of its oxides, which has high energy consumption and low efficiency, resulting in the high price of metal vanadium, which limits its wider application. Therefore, the smelting of refractory metal vanadium and its alloys has become a research hotspot in the modern metallurgical industry.

[0003] At present, the main method of industrial aluminum-vanadium alloy production is aluminothermic reduction, which is a process of combining metallic aluminum and V. 2 O 5 As raw material, vanadium slag is used to produce V 2 O 5 The main process is that vanadium slag is firstly roasted by sodium to obtain vanadium oxygen acid salt intermediate, and then decomposed (such as ammonium precipitation) and calcined at high temperature to obtain its oxide V 2 O 5 The above process has many high-temperature operation steps, long process, high energy consumption, and high cost. In addition, ammonia nitrogen wastewater and harmful corrosive gases will be produced during the decomposition and high-temperature calcination of refractory metal oxygen acid salts, causing serious pollution to the ecological environment. Therefore, it is of great significance to use new raw materials to prepare aluminum-vanadium alloys through a short process. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In order to solve the shortcomings and problems of the prior art, the present invention provides a method for preparing an aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate. The method uses sodium metavanadate, an intermediate product of oxyacid salt in the process of vanadium slag treatment, as a raw material, and directly prepares the aluminum-vanadium master alloy by aluminothermic reduction, thereby avoiding complex processes such as decomposition and calcination, greatly simplifying the production process, and avoiding environmental pollution problems.

[0006] (II) Technical solution

[0007] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0008] A method for preparing aluminum-vanadium alloy by aluminothermic reduction of sodium metavanadate, comprising the following steps:

[0009] S1. Use powdered sodium metavanadate as raw material, add aluminum powder and calcium oxide, and mix well;

[0010] S2, pressing the mixed material into columnar agglomerates;

[0011] S3. Put the agglomerates into a tube furnace and keep them at high temperature in an inert gas atmosphere to obtain a mixture of aluminum-vanadium master alloy and calcium aluminate-based slag.

[0012] The method as described above preferably further comprises S4, further heating the mixture obtained in step 3 in an inert gas atmosphere for two stages of high temperature insulation, until slag-metal separation can be achieved, thereby obtaining an aluminum-vanadium master alloy.

[0013] In the method as described above, preferably, in step S1, the particle size of the aluminum powder is 15-75 um.

[0014] In the method as described above, preferably, in step S1, the sodium metavanadate, aluminum powder and calcium oxide are mixed in a mass ratio of 100:94 to 137:83 to 95.

[0015] In the method as described above, preferably, in step S2, the pressing pressure is 30-60 MPa.

[0016] In the method as described above, preferably, in step S3, the pressure in the tube furnace is 0.6-0.8 atm; and the inert gas is argon.

[0017] In the method as described above, preferably, in step S3, the temperature of the high temperature insulation stage is 950-1050° C., and the insulation time is 60-120 min.

[0018] In the method as described above, preferably, in step S4, the temperature of the second stage high temperature insulation is 1600-1700° C., and the insulation time is 60-120 min.

[0019] (III) Beneficial effects

[0020] The beneficial effects of the present invention are:

[0021] The present invention provides a method for preparing aluminum-vanadium alloy by aluminothermic reduction of sodium metavanadate. The raw material used is vanadate, mainly sodium metavanadate, which is an intermediate product in the process of vanadium slag treatment. The aluminum-vanadium intermediate alloy is directly prepared by using it as a raw material, which is cheaper and can greatly shorten the process flow. It is more efficient and energy-saving than the traditional process in terms of energy consumption, and at the same time avoids the preparation of metal oxide V by sodium metavanadate. 2 O 5 The environmental pollution problems caused in the process are more environmentally friendly; at the same time, the aluminum thermal reduction process is adopted, which is easier to operate, has high production efficiency and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A comparison diagram of the preparation process of the method of the present invention and the traditional aluminum-vanadium alloy preparation process;

[0023] Figure 2 is an X-ray diffraction pattern of the aluminum-vanadium master alloy prepared in Example 1 of the present invention;

[0024] Figure 3 This is the X-ray diffraction diagram of the slag phase in the product of Example 1 of the present invention. DETAILED DESCRIPTION

[0025] In the prior art, vanadium slag is subjected to sodiumization roasting and leaching to obtain sodium metavanadate. The traditional process is to decompose and calcine sodium metavanadate to obtain V 2 O 5 , V 2 O 5 As a raw material to prepare aluminum-vanadium alloy, the present invention uses the obtained vanadium oxygen-containing salt intermediate with aluminum powder and calcium oxide as raw materials to prepare aluminum-vanadium alloy, and its flow chart is as follows Figure 1 The present invention uses sodium metavanadate as raw material, avoiding the process of preparing V 2 O 5 The pollution problem generated during the process. The present invention adopts two-stage calcination temperature: the first temperature refers to the temperature of aluminum-vanadium alloy generation, preferably 950-1050°C; the second temperature is the temperature indicating the separation of slag and gold, preferably 1600-1700°C. The advantage of the present invention is that it uses sodium metavanadate as raw material, has a short process, and is a more environmentally friendly metallurgical process.

[0026] The present invention provides a method for preparing aluminum-vanadium alloy by aluminothermic reduction of sodium metavanadate, which comprises the following steps:

[0027] S1. Using powdered sodium metavanadate, aluminum powder and calcium oxide as raw materials, mix them evenly in a certain proportion; wherein the particle size of the Al powder is 15 to 75 μm;

[0028] S2, pressing the mixed material into columnar agglomerates;

[0029] S3, placing the agglomerate into a tube furnace, and heat-keeping it at 950-1050° C. in an argon atmosphere for 60-120 minutes to obtain a mixture of aluminum-vanadium master alloy and calcium aluminate-based slag;

[0030] S4. Further, in order to separate the aluminum-vanadium alloy from the calcium aluminate-based slag, the reduction product obtained in step 3 is further heated to 1600-1700° C. in an argon atmosphere for two-stage high-temperature insulation, and after insulation for 60-120 minutes, the slag-gold separation can be achieved to obtain the aluminum-vanadium intermediate alloy.

[0031] After a large number of experimental studies, it was found that sodium metavanadate was used as raw material, aluminum powder as reducing agent, and calcium oxide as slag-forming agent to carry out reduction reaction at high temperature. The amount of reducing agent was selected according to the amount of thermal reduction reaction and the phase diagram of aluminum-vanadium master alloy. If the amount of aluminum powder was too much, Al 3 V and Al 10 V master alloy, too little aluminum powder will also lead to incomplete reaction. The amount of calcium oxide is determined according to the theoretical amount of aluminum oxide produced by the reduction reaction; according to the phase diagram of aluminum oxide and calcium oxide, the melting point of the slag phase is reduced to reduce the slag-gold separation temperature as much as possible. Too much or too little dosage will lead to increased temperature and increased energy consumption. Therefore, it is preferred to use sodium metavanadate, aluminum powder and calcium oxide in a mass ratio of 100:94-137:83-95. The finer the aluminum powder, the larger the contact area, which is more conducive to the reaction. Therefore, the particle size of Al powder is preferably 15-75μm. Tabletting can increase the contact of the powder and increase its reaction area; the pressure is preferably 30-60MPa, which is enough to make the powder into columnar agglomerates. The reaction temperature and insulation time are determined by differential thermal analysis and verification experiments. A high-temperature insulation is preferably 950-1050℃ for 60-120min.

[0032] The second stage high temperature insulation is preferably 1600-1700°C for 60-120 minutes. In order to better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with the accompanying drawings through specific implementation methods.

[0033] Example 1

[0034] The method for preparing aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate comprises the following steps:

[0035] Step 1, mixing sodium metavanadate and aluminum powder in a mass ratio of sodium metavanadate: aluminum powder: calcium oxide powder = 100:94:83;

[0036] Step 2, using a press to press the above-mentioned mixed material into a columnar mass with a diameter of 20 mm at a pressure of 40 MPa;

[0037] Step 3, placing the columnar reaction material into a tubular furnace, keeping the temperature at 950° C. for 120 min in an argon atmosphere at a pressure of 0.6 atm, to obtain a reduction product, wherein the product composition is an aluminum-vanadium master alloy and a calcium aluminate-based slag;

[0038] Step 4, the reduction product obtained in step 3 is further heated to 1700°C in an argon atmosphere and kept warm for 120 minutes, the alloy phase and the slag phase are melted, and the aluminum-vanadium intermediate alloy and the slag phase are separated by their own density difference and fluidity. After the physical phase detection of the alloy and the slag phase, it is obtained that the physical phase composition of the aluminum-vanadium intermediate alloy is Al 8 V 5 、Al 3 V and metallic Al phase, the slag phase is mainly Ca 12 Al 14 O 33 and CaAl 2 O 4 .

[0039] Specifically, the aluminum-vanadium master alloy and the slag phase are subjected to X-ray diffraction detection respectively. The results obtained for the aluminum-vanadium master alloy are as follows: Figure 1 As shown, it shows that its phase composition is Al 8 V 5 、Al 3 V and metal Al phase. The detection results of slag phase are as follows Figure 2 As shown, its main component is Ca1 2 Al 14 O 33 and CaAl 2 O 4 The same detection method is used to obtain the composition in the following embodiments and comparative examples.

[0040] Example 2

[0041] The method for preparing aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate comprises the following steps:

[0042] Step 1, mixing sodium metavanadate and aluminum powder in a mass ratio of sodium metavanadate: aluminum powder: calcium oxide powder = 100:116:83;

[0043] Step 2, pressing the mixed material into a columnar mass with a diameter of 20 mm at a pressure of 50 MPa using a press;

[0044] Step 3, placing the columnar reaction material into a tubular furnace, the pressure in the tubular furnace is 0.6 atm, and the temperature is kept at 1000° C. for 90 minutes in an argon atmosphere, and the product composition is aluminum-vanadium master alloy and calcium aluminate-based slag;

[0045] Step 4: The reduction product obtained in step 3 is further heated to 1600°C in an argon atmosphere and kept at this temperature for 90 minutes to separate the aluminum-vanadium master alloy and the slag phase. 3 V phase, slag phase is mainly Ca 12 Al 14 O 33 and CaAl 2 O 4 .

[0046] Example 3

[0047] The method for preparing aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate comprises the following steps:

[0048] Step 1, mixing sodium metavanadate and aluminum powder in a mass ratio of sodium metavanadate: aluminum powder: calcium oxide powder = 100:137:83;

[0049] Step 2, pressing the mixed material into a columnar mass with a diameter of 20 mm at a pressure of 40 MPa using a press;

[0050] Step 3, placing the columnar reaction material into a tubular furnace, the pressure in the tubular furnace is 0.6 atm, and the temperature is kept at 950° C. for 90 minutes in an argon atmosphere, and the product composition is aluminum-vanadium master alloy and calcium aluminate-based slag;

[0051] Step 4: The reduced product obtained in step 3 is further heated to 1600°C under an argon atmosphere and kept at this temperature for 60 minutes to separate the aluminum-vanadium master alloy and the slag phase. 3 V and Al 10 V phase, slag phase is mainly Ca 12 Al 14 O 33 and CaA l2 O 4 .

[0052] Example 4

[0053] The method for preparing aluminum-vanadium master alloy by aluminothermic reduction of sodium metavanadate comprises the following steps:

[0054] Step 1, mixing sodium metavanadate, aluminum powder and calcium oxide in a mass ratio of sodium metavanadate: aluminum powder: calcium oxide powder = 100:137:95;

[0055] Step 2, pressing the mixed material into a columnar mass with a diameter of 20 mm at a pressure of 50 MPa using a press;

[0056] Step 3, placing the columnar reaction material into a tubular furnace, the pressure in the tubular furnace is 0.8 atm, and the temperature is kept at 950° C. for 120 min in an argon atmosphere, and the reduction product consists of an aluminum-vanadium master alloy and a calcium aluminate-based slag;

[0057] Step 4: The reduced product obtained in step 3 is further heated to 1650°C under an argon atmosphere and kept at this temperature for 90 minutes to separate the aluminum-vanadium master alloy and the slag phase. 3 V and Al 10 V phase, slag phase is mainly Ca 12 Al 14 O 33 .

[0058] Comparative Example 1

[0059] Aluminothermic reduction of sodium metavanadate reaction comparative experimental case, including the following steps:

[0060] Step 1, mixing sodium metavanadate, aluminum powder and calcium oxide in a mass ratio of sodium metavanadate: aluminum powder: calcium oxide powder = 100:137:83;

[0061] Step 2, pressing the mixed material into a columnar mass with a diameter of 20 mm at a pressure of 40 MPa using a press;

[0062] Step 3, placing the columnar reaction material into a tubular furnace, the pressure in the tubular furnace is 0.6 atm, and the temperature is kept at 900° C. for 90 minutes in an argon atmosphere, but the product is mainly composed of aluminum, trivalent sodium vanadate and calcium oxide;

[0063] Step 4: The reduction product obtained in step 3 is further heated to 1600°C in an argon atmosphere and kept at this temperature for 60 minutes, thereby further achieving the aluminothermic reduction reaction and the separation of the aluminum-vanadium master alloy and the slag phase after the reaction, wherein the aluminum-vanadium master alloy is mainly Al 3 V and Al 10 V phase, slag phase is mainly Ca 12 Al 14 O 33 and CaAl 2 O 4 .

[0064] Comparative Example 2

[0065] Aluminothermic reduction of sodium metavanadate reaction comparative experimental case, including the following steps:

[0066] Step 1, mixing sodium metavanadate, aluminum powder and calcium oxide in a mass ratio of sodium metavanadate: aluminum powder: calcium oxide powder = 100:137:66;

[0067] Step 2, pressing the mixed material into a columnar mass with a diameter of 20 mm at a pressure of 40 MPa using a press;

[0068] Step 3, placing the columnar reaction material into a tubular furnace, the pressure in the tubular furnace is 0.6 atm, and the temperature is kept at 950° C. for 90 minutes in an argon atmosphere, and the product composition is aluminum-vanadium master alloy and calcium aluminate-based slag;

[0069] Step 4: The reduction product obtained in step 3 is further heated to 1600° C. in an argon atmosphere and kept at this temperature for 60 min. The metallographic phase and slag phase in the product are still in an agglomerated state, and the separation of the aluminum-vanadium master alloy and the slag phase is not achieved. The product composition is Al 3 V, Al 10 V phase and CaAl 4 O 7 .

[0070] The above results show that the temperature used in step 3 in comparative example 1 causes the thermal reduction reaction to be unable to proceed completely, and low-valent vanadium oxygen-containing acid salts appear; the ratio used in step 1 in comparative example 2 causes the final slag gold to be unable to be separated.; In Example 3 and comparative example 1, the temperature selected in step 3 is different, and the obtained products are different, indicating that the formation temperature of aluminum-vanadium alloy is different, which is also the temperature of aluminum thermal reduction reaction, indicating that the temperature range of thermal reduction reaction is preferably 950°C; comparative example 2 shows that the material ratio has an impact on the thermal reduction reaction and the final product.

[0071] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art can use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing aluminum-vanadium alloy by aluminothermic reduction of sodium metavanadate, characterized in that: It includes the following steps: S1, using powdered sodium metavanadate as a raw material, adding aluminum powder and calcium oxide, and mixing them evenly; wherein the sodium metavanadate, aluminum powder and calcium oxide are mixed in a mass ratio of 100:94 to 137:83 to 95; S2, pressing the mixed material into columnar agglomerates; S3, placing the agglomerates into a tube furnace, and keeping them at high temperature in an inert gas atmosphere for a period of time, thereby obtaining a mixture of aluminum-vanadium master alloy and calcium aluminate-based slag; The method further comprises S4, further heating the mixture obtained in step 3 in an inert gas atmosphere for two-stage high-temperature insulation to achieve slag-metal separation and obtain an aluminum-vanadium master alloy; Wherein, in step S3, the temperature of the high temperature insulation is 950-1050°C, and the insulation time is 60-120 minutes; In step S4, the temperature of the second stage high temperature insulation is 1600-1700°C, and the insulation time is 60-120 minutes.

2. The method according to claim 1, characterized in that In step S1, the particle size of the aluminum powder is 15-75 μm.

3. The method according to claim 1, characterized in that In step S2, the pressing pressure is 30-60 MPa.

4. The method according to claim 1, characterized in that In step S3, the pressure in the tube furnace is 0.6-0.8 atm; and the inert gas is argon.

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