Vanadium segregation control method for powder vanadium smelting vanadium-aluminum alloy

Abstract

The invention relates to the technical field of vanadium-aluminum alloy preparation, in particular to a vanadium segregation control method for powder vanadium smelting of a vanadium-aluminum alloy. The invention discloses a vanadium segregation control method for smelting a vanadium-aluminum alloy by powder vanadium. The vanadium segregation control method comprises the following steps: putting vanadium pentoxide and aluminum particles which are mixed according to a preset proportion as raw materials into a graphite crucible; ignition reduction is carried out, aluminothermic smelting is carried out, and vanadium-aluminum alloy and slag are prepared; wherein the control range of the thermit smelting heat is 3200-3300 kJ / kg, and a cooling agent is added in the thermit smelting process. The graphite crucible is adopted as a smelting furnace, heat exchange with the outside can be better achieved, alloy can be cooled and crystallized in time conveniently, meanwhile, appropriate heat parameters and coolants are adopted, elements can be evenly distributed conveniently, and the segregation degree of the obtained product is lower than that of the process before optimization.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium-aluminum alloy preparation, and in particular to a method for controlling vanadium segregation in vanadium-aluminum alloy smelting using powdered vanadium. Background Art

[0002] Vanadium aluminum alloy is a basic raw material for titanium alloys. It is currently the second largest application area after the application of vanadium in steel. Ti-6Al-4V and Ti-8Al-1Mo-1V, these two titanium alloys account for 50% of the titanium alloy market and are mainly used in the production of jet engines, high-speed aircraft frames and rocket engine casings. The vanadium used in the production of titanium alloys is added in the form of vanadium aluminum alloys. Japan, the United States, the United Kingdom and other countries are also further increasing the application research of vanadium-containing titanium alloys in civilian industries.

[0003] Thermite is a method of obtaining a single substance of a high melting point metal by utilizing the reducing property of aluminum. Thermite refers to a mixture of aluminum and metal oxides. After mixing aluminum powder with a certain amount of high melting point metal oxides (such as iron oxide, etc.), it is ignited with a magnesium bar. It can be seen that the aluminum powder reacts violently at a high temperature, releasing a large amount of heat and emitting a dazzling light. The product is a single substance of aluminum oxide and the high melting point metal. The thermite reaction is very intense, so it is difficult to extinguish after ignition, and it is difficult to control the reaction process after ignition. The reaction is to load the furnace charge and quickly generate high temperature (1700℃~3000℃) at the moment of ignition to make the furnace charge in a molten state, and then the alloy is refined. The advantage of this smelting method is that it does not require the input of electric heat, has low energy consumption, and has a lower production cost than the electric arc furnace smelting method. Since vanadium aluminum alloy is a one-time reaction of the thermite method, it is difficult to stir the molten liquid in the furnace through the outside during the smelting process. Although vanadium-aluminum alloy is an infinitely miscible solid solution, the density of aluminum is lower than that of vanadium. The molten aluminum is difficult to sink to the bottom of the furnace, and the vanadium generated by the reaction at the bottom of the furnace is not easy to float up. The molten liquid in the reaction furnace has insufficient upward and downward convection, resulting in a higher aluminum content in the upper part of the alloy cake and a higher vanadium content in the lower part, which in turn causes serious segregation of the alloy cake. Generally, the upper and lower segregation of the alloy cake reaches about 3.5%.

[0004] At present, the production process of vanadium-aluminum alloy generally uses vanadium pentoxide as raw material and adopts aluminothermic method to produce vanadium-aluminum alloy. Since vanadium pentoxide reacts with metal aluminum to release a large amount of heat, the heat is greatly excessive, making the reaction explosive, which is enough to raise the temperature of the system to more than 3000℃ under adiabatic conditions. Therefore, a certain amount of inert substances (commonly known as heat removers) are usually added to the charge to control the reaction rate and the temperature rise of the reaction products. Since the heat remover always contains a certain amount of Fe, Si, P and heavy metal elements, the impurity content in the produced vanadium-aluminum alloy is relatively high, which reduces the purity of the alloy.

[0005] The invention patent application with the publication number CN101818270A discloses a method for preparing a vanadium-aluminum alloy material. The method weighs 20% to 33.1% Al and 50% to 66.9% V2O5 in powder form, mixes them in a ball mill for 8 to 16 hours, places them in a copper mold and compacts them with a press at a pressure of 60 to 80 MPa, places the mold containing the pressed reaction material in an aluminum heat reaction vessel, places an igniter on the material, blows out the residual air with an inert gas, and heats to about 300°C under the protection of 2 to 7 MPa argon gas to react, thereby obtaining a vanadium-aluminum alloy, wherein, in terms of mass percentage, V is 75% to 95%, Al is 5.0% to 25.0%, S content is about 0.15%, and Fe content is about 0.50%. Obviously, in the above process, the obtained product has a high content of impurities such as Fe and S, which is due to the introduction of some impurities during mixing in the ball mill for 8 to 16 hours. In addition, since the thermite reaction is carried out in a closed pressure vessel, the output of vanadium-aluminum alloy is greatly limited. In addition, since the equipment is required to have strong pressure resistance, the manufacturing cost will be increased.

[0006] The invention patent application with application publication number CN111394600A proposes a method for preparing vanadium aluminum alloy based on aluminothermic reduction, wherein metal aluminum A is first spread on the bottom of the reaction furnace, and then vanadium pentoxide, coolant and metal aluminum B are evenly mixed and spread on metal aluminum A, ignited and reacted, cooled after completion, and slag is removed to obtain vanadium aluminum alloy. In the traditional method, refractory materials are often used as furnace linings. These materials are easy to react chemically with the reactants, introducing impurity elements such as silicon and iron, further reducing the purity of the alloy. In addition, due to uneven heat distribution during the aluminothermic reaction, segregation of alloy components may occur, affecting product quality. For example, the ratio of vanadium to aluminum in vanadium aluminum alloy is difficult to accurately control, which easily causes the components in some areas to not meet the requirements. Based on this, the prior art still needs to be improved. Summary of the invention

[0007] In view of this, the present invention proposes a method for controlling vanadium segregation in vanadium aluminum alloy smelting by vanadium powder, which can at least solve the technical problem of high segregation degree of the main element V in the existing aluminum alloy vanadium smelting method.

[0008] A method for controlling vanadium segregation in smelting vanadium-aluminum alloy by vanadium powder of the present invention comprises the following steps: S200, putting vanadium pentoxide and aluminum particles mixed in a preset ratio as raw materials into a graphite crucible; S300, ignition reduction, aluminum hot smelting, to produce vanadium aluminum alloy and slag; Among them, the heat control range of aluminothermic smelting is 3200-3300 kJ / kg, and coolant is added during the aluminothermic smelting process.

[0009] In some embodiments, the vanadium pentoxide is in powder form, and its particle size ranges from 100 to 300 meshes.

[0010] In some embodiments, the aluminum particles are solid aluminum particles, and the particle size of the aluminum particles ranges from 1 to 3 mm.

[0011] In some embodiments, the weight ratio of vanadium pentoxide to aluminum particles is 1.16-1.67:1.

[0012] In some embodiments, before step S200, the method further includes: S100, pouring the proportioned vanadium pentoxide and aluminum particles into a mixer for mixing.

[0013] In some embodiments, the mixing time of the mixer is 20 to 30 minutes.

[0014] In some embodiments, the added coolant is CaO.

[0015] In some embodiments, the weight ratio of CaO to vanadium pentoxide in the raw material is 1:9-11.

[0016] In some embodiments, in step S300, the ignition agent used for ignition reduction is barium peroxide, and magnesium rods are used as the ignition material.

[0017] In some embodiments, the method for controlling vanadium segregation in vanadium-aluminum alloy smelting by powder vanadium is characterized in that it also includes: S400, standing for 30 to 60 minutes after the operation is completed.

[0018] The beneficial effects of the present invention are as follows: the present application adopts an out-of-furnace method for reaction production, and the use of a graphite crucible as a smelting furnace can better exchange heat with the outside world to facilitate timely cooling and crystallization of the alloy. The graphite crucible has the characteristics of high purity and low impurity content, which can effectively reduce the introduction of impurities during the smelting process and improve the purity of the vanadium aluminum alloy. And the graphite crucible has good thermal insulation performance, which helps to maintain the temperature stability during the smelting process and reduce the impact of temperature fluctuations on the alloy composition. The present application can avoid overheating or overcooling by accurately controlling the smelting heat within the range of 3200 to 3300 kJ / kg, ensuring that the reaction is fully carried out, while reducing the occurrence of segregation. The present application adds a coolant during the aluminum hot smelting process, which can effectively adjust the chemical heat of the entire material, control the reaction speed, reduce the heat per unit charge, prevent excessive heat from causing melt splashing losses, and avoid segregation problems caused by excessive reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic flow chart of a method for controlling vanadium segregation in smelting vanadium-aluminum alloy using powder vanadium provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0022] refer to Figure 1 The present invention provides a method for controlling vanadium segregation in smelting vanadium-aluminum alloy by vanadium powder, comprising the following steps: S200, putting vanadium pentoxide and aluminum particles mixed in a preset ratio as raw materials into a graphite crucible; S300, ignition reduction, aluminum hot smelting, to produce vanadium aluminum alloy and slag; Among them, the heat control range of aluminothermic smelting is 3200-3300 kJ / kg, and coolant is added during the aluminothermic smelting process.

[0023] The present application adopts the method outside the furnace for reaction production. Using a graphite crucible as a smelting furnace can better exchange heat with the outside world to facilitate the timely cooling and crystallization of the alloy. The graphite crucible has the characteristics of high purity and low impurity content, which can effectively reduce the introduction of impurities in the smelting process and improve the purity of the vanadium aluminum alloy. And the graphite crucible has good thermal insulation performance, which helps to maintain the temperature stability during the smelting process and reduce the impact of temperature fluctuations on the alloy composition. The present application can avoid overheating or supercooling by accurately controlling the smelting heat within the range of 3200 to 3300 kJ / kg, ensuring that the reaction is fully carried out and reducing the occurrence of segregation. Specifically, if the heat is low, the raw materials will not have time to fully flow and the entire melt will solidify, causing some elements to aggregate and cause segregation. If the heat is too large, the melt will splash. Appropriate smelting heat helps to promote the uniform distribution of alloy elements and reduce the segregation caused by uneven temperature. The present application adds a coolant during the aluminum hot smelting process, which can effectively regulate the chemical heat of the entire material, control the reaction rate, reduce the heat per unit charge, prevent melt splashing loss caused by excessive heat, and avoid segregation problems caused by overly violent reactions.

[0024] In some embodiments, the vanadium pentoxide is in powder form, and its particle size range is 100-300 meshes. The powdered vanadium pentoxide has a larger specific surface area and a larger contact area with the aluminum particles, so that the aluminothermic reaction can be carried out more quickly and fully, thereby improving the reaction efficiency. Setting the particle size range of the vanadium pentoxide to 100-300 meshes helps to evenly distribute the vanadium pentoxide in the alloy and reduce the segregation phenomenon caused by uneven particle size.

[0025] In some embodiments, the aluminum particles are solid aluminum particles, and the particle size of the aluminum particles ranges from 1 to 3 mm. The reaction speed of solid aluminum particles is relatively slow, which helps to control the speed of the aluminum heat reaction and avoid component segregation caused by excessive reaction. The particle size range of aluminum particles is set to 1 to 3 mm to ensure that the aluminum particles react fully during the reaction process, improve the overall quality of the alloy, and reduce the risk of surface oxidation.

[0026] In some embodiments, the weight ratio of vanadium pentoxide to aluminum particles is 1.16 to 1.67: 1. Excess aluminum particles are used to form a vanadium aluminum alloy by fusing the aluminum particles with metallic vanadium during the reduction reaction. Specifically, under normal circumstances, the weight ratio of vanadium pentoxide to aluminum particles is 2: 1. In this application, excess aluminum is used to fuse with metallic vanadium to form a vanadium aluminum alloy.

[0027] In some embodiments, before step S200, the following steps are further included: S100, pouring the proportioned vanadium pentoxide and aluminum particles into a mixer for mixing, for example, the mixer is a vertical mixer. The uniform mixing of the mixer can ensure that the vanadium pentoxide and aluminum particles are fully in contact in the subsequent aluminothermic reaction, thereby improving the efficiency of the reaction. It can also reduce the segregation phenomenon caused by uneven particle size, thereby obtaining a vanadium aluminum alloy with more uniform composition.

[0028] In some embodiments, the mixing time of the mixer is 20 to 30 minutes to ensure uniform distribution of vanadium pentoxide and aluminum particles in the alloy and reduce segregation caused by uneven particle size.

[0029] In some embodiments, the added coolant is CaO. CaO as a coolant has the following advantages: (1) it can effectively absorb a large amount of heat generated during the aluminothermic reaction, acting as a real coolant to reduce heat; (2) CaO reacts with itself to form a binary slag system, which can also reduce the melting point and viscosity of the slag system, prolong the melting time of the slag, and improve the vanadium yield.

[0030] In some embodiments, the weight ratio of CaO to vanadium pentoxide in the raw material is 1:9-11, preferably 1:10, to fully meet the reaction requirements.

[0031] In some embodiments, the ignition reduction agent is barium peroxide, and magnesium strips are used as ignition materials. Using barium peroxide and magnesium strips as ignition agents can provide a high temperature environment, quickly ignite the aluminum heat smelting reaction, and facilitate the full reaction between vanadium pentoxide and aluminum particles, improve the purity and quality of vanadium aluminum alloy, and ensure the stability and consistency of the reaction.

[0032] In some embodiments, the method for controlling vanadium segregation in vanadium-aluminum alloy smelting by powder vanadium further includes: S400, after the operation is completed, the alloy is allowed to stand for 30 to 60 minutes. Standing for a period of time helps release the internal stress of the vanadium-aluminum alloy and prevents deformation or cracking during subsequent processing or use.

[0033] In order to better illustrate this solution, several specific embodiments and comparative examples are provided below: Example 1 Take 100kg vanadium pentoxide and 59.9kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.67:1, the particle size of vanadium pentoxide is controlled to 100 mesh; the particle size of aluminum particles is controlled to 1mm. Use graphite crucible as smelting furnace body, lime (CaO) as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 20min, and the smelting heat is controlled at 3300kJ / kg. After the operation is completed, stand for 30min to obtain 62.37kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.5%.

[0034] Comparative Example 1 Take 100kg vanadium pentoxide and 59.9kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.67:1, the particle size of vanadium pentoxide is controlled to 100 mesh; the particle size of aluminum particles is controlled to 1mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 10min, and the smelting heat is controlled at 3300kJ / kg. After the operation is completed, stand for 30min to obtain 62.1kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.9%.

[0035] Example 2 Take 100kg vanadium pentoxide and 63.68kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.58:1, the particle size of vanadium pentoxide is controlled to 200 mesh; the particle size of aluminum particles is controlled to 2mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 20min, and the smelting heat is controlled at 3250kJ / kg. After the operation is completed, let it stand for 30min to obtain 64.85kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.4%.

[0036] Comparative Example 2 Take 100kg vanadium pentoxide and 63.68kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.58:1, the particle size of vanadium pentoxide is controlled to 200 mesh; the particle size of aluminum particles is controlled to 4mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 20min, and the smelting heat is controlled at 3250kJ / kg. After the operation is completed, let it stand for 30min to obtain 64.75kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.6%.

[0037] Example 3 Take 100kg vanadium pentoxide and 83.38kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.2:1, the particle size of vanadium pentoxide is controlled to 250 mesh; the particle size of aluminum particles is controlled to 2.5mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 25min, and the smelting heat is controlled at 3230kJ / kg. After the operation is completed, stand for 30min to obtain 87.5kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.3%.

[0038] Comparative Example 3 Take 100kg vanadium pentoxide and 83.38kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.2:1, the particle size of vanadium pentoxide is controlled to 80 mesh; the particle size of aluminum particles is controlled to 2.5mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 25min, and the smelting heat is controlled at 3230kJ / kg. After the operation is completed, let it stand for 30min to obtain 87.4kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.7%.

[0039] Example 4 Take 100kg vanadium pentoxide and 85.9kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.16:1, the particle size of vanadium pentoxide is controlled to 300 mesh; the particle size of aluminum particles is controlled to 3mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 30min, and the smelting heat is controlled at 3200kJ / kg. After the operation is completed, stand for 30min to obtain 96.08kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.2%.

[0040] Comparative Example 4 Take 100kg of vanadium pentoxide and 85.9kg of aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.16:1, the particle size of vanadium pentoxide is controlled to 300 mesh; the particle size of aluminum particles is controlled to 3mm. The mixing time control range is 30min, the smelting heat is controlled to 3150kJ / kg, and the operation is completed and left to stand for 30min to obtain 95.82kg of vanadium aluminum alloy product, and the segregation degree of the main element V in the obtained alloy is 1.6%.

[0041] Comparative Example 5 Take 100kg vanadium pentoxide and 85.9kg aluminum particles as raw materials, the weight ratio of vanadium pentoxide to aluminum particles is 1.16:1, the particle size of vanadium pentoxide is controlled to 300 mesh; the particle size of aluminum particles is controlled to 3mm. Use graphite crucible as smelting furnace body, lime as coolant, and carry out aluminum thermal reduction reaction. The mixing time is controlled within the range of 10min, and the smelting heat is controlled at 3200kJ / kg. After the operation is completed, stand for 30min to obtain 96.08kg vanadium aluminum alloy product, and the segregation degree of the main element V of the obtained alloy is 1.7%.

[0042] Compared with the existing process, the vanadium aluminum alloy preparation method of the present invention adopts a graphite crucible as a smelting furnace, which can better exchange heat with the outside world and facilitate timely cooling and crystallization of the alloy. At the same time, suitable material particle size, mixing time and heat parameters are adopted to facilitate uniform distribution of elements. The obtained product has a lower degree of segregation than the process before optimization, and fully meets the requirements of large-scale industrial production.

[0043] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder, characterized in that: The following steps are involved: S200, putting vanadium pentoxide and aluminum particles mixed in a preset ratio as raw materials into a graphite crucible; S300, ignition reduction, aluminum hot smelting, to produce vanadium aluminum alloy and slag; The heat control range of the aluminothermic smelting is 3200-3300 kJ / kg, and a coolant is added during the aluminothermic smelting process.

2. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 1, characterized in that: The vanadium pentoxide is in powder form, and its particle size ranges from 100 to 300 meshes.

3. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 1, characterized in that: The aluminum particles are solid aluminum particles, and the particle size range of the aluminum particles is 1-3 mm.

4. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 1, characterized in that: The weight ratio of the vanadium pentoxide to the aluminum particles is 1.16-1.67:

1.

5. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 1, characterized in that: Before step S200, the method further includes: S100, pouring the proportioned vanadium pentoxide and aluminum particles into a mixer for mixing.

6. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by powder vanadium according to claim 5, characterized in that: The mixing time of the mixer is 20 to 30 minutes.

7. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 1, characterized in that: The added coolant is CaO.

8. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 7, characterized in that: The weight ratio of CaO to vanadium pentoxide in the raw material is 1:9-11.

9. The method for controlling vanadium segregation in vanadium-aluminum alloy smelting by vanadium powder according to claim 1, characterized in that: Step S300, the ignition agent used for ignition reduction is barium peroxide, and the magnesium strip is used as the ignition material.

10. The method for controlling vanadium segregation in smelting vanadium-aluminum alloy by vanadium powder according to claim 1, characterized in that: Also includes: S400, let stand for 30~60 minutes after the operation is completed.

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