Smelting niobium and preparation method thereof

Abstract

The invention provides smelting niobium and a preparation method thereof, and belongs to the technical field of metal materials. The preparation method of the smelted niobium comprises the following steps that a niobium source and an aluminum source are provided, the niobium source is niobium pentoxide powder, and the aluminum source is aluminum powder; the niobium source and the aluminum source are mixed, an aluminothermic reduction reaction is carried out, the niobium-aluminum alloy is obtained, and the content of Nb is 85-89 wt%; the niobium-aluminum alloy is sequentially subjected to first smelting and second smelting, smelted niobium is obtained, and the conditions of the first smelting comprise that the smelting pressure is smaller than or equal to 5.0 * 10 <-1 > Pa, the smelting power is 230-270 kW, and the smelting speed is 35-50 kg / h; the conditions of the second smelting are as follows: the smelting pressure is less than or equal to 5.0 * 10 <-1 > Pa, the smelting power is 230-270kW, and the smelting speed is 40-55kg / h. The smelted niobium prepared through the method is low in impurity content and high in smelted niobium yield.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and particularly relates to a smelted niobium and a preparation method thereof. Background Art

[0002] Niobium-based alloy materials have excellent high-temperature resistance, mechanical properties and processing properties, and are widely used in fields such as aerospace, electronic devices, superconducting materials, etc. Niobium-aluminum alloy can be used as an additive to prepare niobium-based alloy materials such as high-niobium titanium-aluminum alloy, and can also smelt niobium-aluminum alloy to obtain smelted niobium. However, in the current related technologies, the impurity content in the prepared smelted niobium is relatively high, and the yield is relatively low. Summary of the Invention

[0003] The purpose of the present invention is to provide a smelted niobium and a preparation method thereof. The smelted niobium prepared by the method of the present invention has a low impurity content and a relatively high yield of smelted niobium.

[0004] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a preparation method of smelted niobium, including the following steps:

[0006] Provide a niobium source and an aluminum source, wherein the niobium source is niobium pentoxide powder, and the aluminum source is aluminum powder;

[0007] Mix the niobium source and the aluminum source, and carry out an aluminothermic reduction reaction to obtain a niobium-aluminum alloy, wherein the Nb content in the niobium-aluminum alloy is 85-89 wt%;

[0008] Carry out first melting and second melting on the niobium-aluminum alloy in sequence to obtain the smelted niobium;

[0009] The conditions of the first melting include: melting pressure ≤ 5.0×10 -1 Pa, melting power is 230-270 kW, and melting speed is 35-50 kg / h;

[0010] The conditions of the second melting include: melting pressure ≤ 5.0×10 -1 Pa, melting power is 230-270 kW, and melting speed is 40-55 kg / h.

[0011] Preferably, the niobium source includes a first niobium source and a second niobium source, and the mass ratio of the first niobium source to the second niobium source is 1:2-2.3; the Ta content in the first niobium source is 1000-1800 ppm, and the Si content is 250-500 ppm; the Ta content in the second niobium source is 30-150 ppm, and the Si content is 0-50 ppm.

[0012] Preferably, the aluminum source includes a first aluminum source and a second aluminum source, and the mass ratio of the first aluminum source to the second aluminum source is 0.3-0.5:1; the Si content in the first aluminum source is 200-350 ppm; the Si content in the second aluminum source is 20-50 ppm.

[0013] Preferably, the aluminothermic reduction reaction is initiated by an ignition agent, and the ignition agent includes potassium permanganate, magnesium-aluminum powder or sodium chlorate.

[0014] Preferably, the time of the aluminothermic reduction reaction is 5-30 min.

[0015] Preferably, after the aluminothermic reduction reaction, it further includes: cooling the material obtained after the aluminothermic reduction reaction, then removing the reduction slag to collect the cake, and crushing the cake to a particle size ≤ 80 mm to obtain the niobium-aluminum alloy.

[0016] Preferably, after the first melting and the second melting, cooling is independently included. The cooling time after the first melting ≥ 0.5 h; the cooling time after the second melting ≥ 1.5 h.

[0017] Preferably, the first melting and the second melting are carried out in an EB450 kW horizontal furnace.

[0018] Preferably, the yield of the smelted niobium ≥ 93.5%.

[0019] The present invention provides the smelted niobium prepared by the preparation method described in the above technical solution. The Ta content in the smelted niobium is 800-950 ppm, and the Si content is 120-145 ppm.

[0020] The present invention provides a preparation method of smelted niobium, including the following steps: providing a niobium source and an aluminum source, the niobium source is niobium pentoxide powder, and the aluminum source is aluminum powder; mixing the niobium source and the aluminum source, and carrying out an aluminothermic reduction reaction to obtain a niobium-aluminum alloy, and the Nb content in the niobium-aluminum alloy is 85-89 wt%; melting the niobium-aluminum alloy successively by the first melting and the second melting to obtain the smelted niobium; the conditions of the first melting include: melting pressure ≤ 5.0×10 -1 Pa, melting power is 230-270 kW, and melting speed is 35-50 kg / h; the conditions of the second melting include: melting pressure ≤ 5.0×10 -1 Pa, melting power is 230-270 kW, and melting speed is 40-55 kg / h. The niobium-aluminum alloy prepared by the method of the present invention has a high niobium content. By melting the niobium-aluminum alloy twice and controlling the appropriate melting speed and melting power, the impurity content in the smelted niobium is low, the yield of the smelted niobium is high, and the production cost is low.

[0021] Furthermore, the present invention uses specific types of raw and auxiliary materials (i.e., the first niobium source, the second niobium source, the first aluminum source, and the second aluminum source) and controls the silicon content therein, which is beneficial to improving the niobium recovery rate during smelting, and can achieve precise use of raw and auxiliary materials, avoiding waste of resources. Description of the Drawings

[0022] Figure 1 It is a process flow chart for preparing smelted niobium in an embodiment of the present invention. Detailed Embodiments

[0023] The present invention provides a method for preparing smelted niobium, comprising the following steps:

[0024] Provide a niobium source and an aluminum source, wherein the niobium source is niobium pentoxide powder, and the aluminum source is aluminum powder;

[0025] Mix the niobium source and the aluminum source, and perform an aluminothermic reduction reaction to obtain a niobium-aluminum alloy, wherein the Nb content in the niobium-aluminum alloy is 85-89 wt%;

[0026] Perform first smelting and second smelting on the niobium-aluminum alloy in sequence to obtain the smelted niobium;

[0027] The conditions for the first smelting include: smelting pressure ≤ 5.0×10 -1 Pa, smelting power is 230-270 kW, and smelting speed is 35-50 kg / h;

[0028] The conditions for the second smelting include: smelting pressure ≤ 5.0×10 -1 Pa, smelting power is 230-270 kW, and smelting speed is 40-55 kg / h.

[0029] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art or prepared by methods well-known to those skilled in the art.

[0030] The present invention provides a niobium source and an aluminum source. The niobium source is niobium pentoxide powder, and the aluminum source is aluminum powder. As an embodiment of the present invention, the particle size of the niobium pentoxide powder can be -40 mesh to -60 mesh (that is, passing through a sieve with a mesh number of 40 to 60, and collecting the material under the sieve); the particle size of the aluminum powder is greater than -100 mesh (that is, passing through a sieve with a mesh number of more than 100, and collecting the material under the sieve). As an embodiment of the present invention, the niobium source can include a first niobium source and a second niobium source, and the mass ratio of the first niobium source to the second niobium source can be 1:2 to 2.3, specifically 1:2, 1:2.1, 1:2.15, 1:2.2 or 1:2.3; the Ta content in the first niobium source can be 1000 to 1800 ppm, specifically 1000 ppm, 1200 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm or 1800 ppm, and the Si content can be 250 to 500 ppm, specifically 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm or 500 ppm; the Ta content in the second niobium source can be 30 to 150 ppm, specifically 30 ppm, 50 ppm, 80 ppm, 100 ppm, 120 ppm or 150 ppm, and the Si content can be 0 to 50 ppm, specifically 10 ppm, 20 ppm, 30 ppm, 40 ppm or 50 ppm. As an embodiment of the present invention, the aluminum source can include a first aluminum source and a second aluminum source, and the mass ratio of the first aluminum source to the second aluminum source can be 0.3 to 0.5:1, specifically 0.3:1, 0.35:1, 0.4:1, 0.45:1 or 0.5:1; the Si content in the first aluminum source can be 200 to 350 ppm, specifically 200 ppm, 250 ppm, 300 ppm or 350 ppm; the Si content in the second aluminum source can be 20 to 50 ppm, specifically 20 ppm, 30 ppm, 40 ppm or 50 ppm.

[0031] After obtaining the niobium source and the aluminum source, the present invention mixes the niobium source and the aluminum source and conducts a thermite reduction reaction to obtain a niobium-aluminum alloy. Specifically, the present invention weighs the amounts of the niobium source and the aluminum source according to the niobium content in the niobium-aluminum alloy for batching to ensure that the product qualification rate and recovery rate are not affected due to batching errors, thereby causing resource loss and waste. As an embodiment of the present invention, specifically, the niobium source and the aluminum source are loaded into a mixer, the inlet and outlet sealing covers are locked for mixing for 50 to 60 minutes, then the machine is stopped and left standing for more than 20 minutes, and then the mixer sealing cover is opened to avoid spontaneous combustion caused by friction heat generation during the mixing process; the mixed powder obtained after mixing is transferred to a conical hopper and transported to a loading station to prepare for furnace loading for subsequent thermite reduction reaction.

[0032] As an embodiment of the present invention, the thermite reduction reaction can be initiated by an ignition agent, which can include potassium permanganate, magnesium-aluminum powder or sodium chlorate. Potassium permanganate is specifically used as the ignition agent in the examples; the dosage of the ignition agent can be 10-20 g, specifically 15 g, as long as it can ensure the initiation of the thermite reduction reaction. As an embodiment of the present invention, the time of the thermite reduction reaction can be 5-20 min, specifically 5 min, 10 min, 15 min or 20 min. As an embodiment of the present invention, after obtaining the mixed powder, specifically, charging into the furnace, evacuation, ignition and thermite reduction reaction are carried out in sequence to obtain the niobium-aluminum alloy. In the embodiment of the present invention, specifically, the mixed powder is put into a crucible and compacted and placed in the furnace body; connect the ignition wire (the contact point on the conductive wire is cleaned to ensure good contact), and send electricity to test the conductivity. After the conductivity is normal, wait for the conductive wire to cool, then place it at the center position on the surface of the mixed powder, and cover the spiral wire completely with the ignition agent; confirm again that the heating wire and the wire of the ignition device are in good condition, then hoist the furnace cover to seal the reactor, and check to ensure that the furnace cover and the furnace body are well sealed; turn on the cooling water (water pressure ≥ 0.1 MPa), start the mechanical pump after confirming that the waterway is unobstructed, open the micro-evacuation valve, and evacuate the furnace to below 300 Pa; after the evacuation is completed, close the micro-evacuation valve and stop the mechanical pump; connect the ignition power supply from the console to start the ignition; when the ignition ammeter indicates 0 instantaneously, that is, the ignition wire is melted, the ignition ends, and the ignition power supply is cut off; after ignition, the pressure gauge indicates that the pressure in the furnace rises, then the thermite reduction reaction starts, and at this time the temperature in the furnace starts to rise, and the reaction reaches the bottom of the crucible.

[0033] As an embodiment of the present invention, preferably after the aluminothermic reduction reaction, it further includes: cooling the material obtained after the aluminothermic reduction reaction, then removing the reduction slag and collecting the cake, and crushing the cake to a particle size of ≤80 mm to obtain the niobium-aluminum alloy. As an embodiment of the present invention, the cooling includes natural cooling and vacuum cooling in sequence; the time of natural cooling can be 40 - 60 min, specifically 50 min; the time of vacuum cooling can be 10 - 15 h, specifically 10 h, 11 h, 12 h, 13 h, 14 h or 15 h; there is also evacuation between natural cooling and vacuum cooling, and the time of evacuation can be 3 - 5 h, specifically 3 h, 4 h or 5 h; the particle size of the niobium-aluminum alloy is ≤80 mm, further ≤50 mm, and even further ≤30 mm. In the embodiment of the present invention, after the aluminothermic reduction reaction, natural cooling is carried out. After natural cooling is completed, the evacuation system is started to evacuate the furnace body. After evacuation is completed, vacuum cooling is carried out. After vacuum cooling is completed, the air release valve is opened to break the vacuum in the furnace chamber; then the furnace cover is opened, and the crucible is lifted out of the furnace body; after removing the obtained reduction slag and naturally cooling the obtained cake, the slag adhered to its surface is removed with a awl and a wire brush to ensure that there is no visible adhered slag on the surface and the fracture of the cake. The cleaned cake is crushed to a particle size of ≤30 mm to obtain the niobium-aluminum alloy. The present invention has no special limitation on the crushing method, as long as the niobium-aluminum alloy with the required particle size can be obtained; in the embodiment of the present invention, specifically, a jaw crusher is used for the crushing, and sparks are prevented from being generated during the crushing process to cause a fire. The Nb content in the niobium-aluminum alloy of the present invention is 85 - 89 wt%, specifically 85 wt%, 86 wt%, 87 wt%, 88 wt%, 88.2 wt% or 89 wt%.

[0034] After obtaining the niobium-aluminum alloy, the present invention carries out the first melting and the second melting on the niobium-aluminum alloy in sequence to obtain the molten niobium. As an embodiment of the present invention, the first melting and the second melting can be carried out in an EB450kW horizontal furnace.

[0035] As an embodiment of the present invention, the conditions of the first melting include: the melting pressure can be ≤5.0×10 - 1Pa; the smelting power can be 230-270kW, specifically 230kW, 235kW, 240kW, 245kW, 250kW, 255kW, 260kW, 265kW or 270kW; the smelting speed can be 35-50kg / h, specifically 35kg / h, 40kg / h, 45kg / h or 50kg / h. As an embodiment of the present invention, after obtaining the niobium aluminum alloy, specifically, furnace charging, evacuation, beam drawing and first smelting are carried out in sequence to obtain a smelted niobium precursor. In the embodiment of the present invention, the furnace, copper crucible and gun barrel of the EB450kW horizontal furnace are cleaned, and the niobium aluminum alloy is respectively loaded into three copper crucibles, and the niobium aluminum alloy loading amount in each copper crucible is 55-65 kg (specifically 60-65 kg in the embodiment), and then the sealing surface of the furnace door is wiped clean and the furnace door is closed; click "Evacuate on" on the "Vacuum Furnace Chamber" interface on the operation cabinet, pre-select all relevant vacuum pumps and valves, and the vacuum system will automatically evacuate the furnace chamber; then click "Evacuate on" on the vacuum "gun chamber" interface, and the vacuum system will automatically evacuate the gun chamber; when the vacuum pressure of the furnace chamber is ≤5×10 0 Pa, click the "molecular pump" icon in the "EB gun" interface to pre-select the turbo pump. When the "molecular pump" icon stops flashing, turn on the strobe power supply, turn on the deflection scanning focus power supply and the gun cooling fan, turn on the high-voltage cabinet power supply, turn on the filament, auxiliary high-voltage and main high-voltage power supplies, and when the gun chamber pressure is ≤5×10 -1 Pa, and the furnace pressure ≤5×10 -1 After Pa, the emission cathode is heated for 5 minutes; then the main high voltage is turned on, and the emission current adjustment potentiometer of the gun is manually adjusted until the electron beam reaches the surface of the niobium aluminum alloy. The position is observed by stroboscopic observation, and the position of the electron beam is adjusted by the X / Y deflection potentiometer (if the electron beam is divergent, the focus can be adjusted 1 to 2 times respectively) until the focusing effect is best; then the scanning pattern is adjusted and the emission current is increased to the process requirement value, and the electron beam position is adjusted according to the melting condition of the molten pool, and the electron beam residence time is adjusted to control the melting speed for the first melting.

[0036] As an embodiment of the present invention, the first smelting preferably further includes cooling; the cooling time after the first smelting needs to be ≥0.5h, for example, it can be 0.5-2h, specifically 1h. In the embodiment of the present invention, after the first smelting is completed, specifically the obtained material is cooled under vacuum conditions, after the cooling is completed, click "Evacuate the furnace chamber to stop", after the relevant valves are automatically closed, click "Break the air to open" to break the furnace chamber, and obtain the smelted niobium precursor.

[0037] After obtaining the smelted niobium precursor, the present invention performs a second smelting on the smelted niobium precursor to obtain the smelted niobium. As an embodiment of the present invention, the conditions of the second smelting include: smelting pressure ≤ 5.0×10 -1Pa; The melting power can be 230 - 270 kW, specifically it can be 230 kW, 235 kW, 240 kW, 245 kW, 250 kW, 255 kW, 260 kW, 265 kW or 270 kW; The melting speed can be 40 - 55 kg / h, specifically it can be 40 kg / h, 45 kg / h, 50 kg / h or 55 kg / h. In the embodiments of the present invention, specifically, the second melting is carried out with reference to the operation steps of the first melting, which will not be elaborated here. As an implementation manner of the present invention, preferably cooling is further included after the second melting; The cooling time after the second melting needs to be ≥ 1.5 h, for example, it can be 1.5 - 3 h, specifically it can be 2 h. In the embodiments of the present invention, specifically, the cooling after the second melting is carried out with reference to the operation steps of the cooling after the first melting, which will not be elaborated here.

[0038] In the embodiments of the present invention, the melting power of the first melting is specifically 250 kW, and the melting speed is specifically 50 kg / h; The melting power of the second melting is specifically 260 kW, and the melting speed is specifically 50 kg / h. As an implementation manner of the present invention, the yield of the melted niobium is ≥ 93.5%, further ≥ 96.04%, still further ≥ 96.3%, yet further ≥ 96.52%, still further ≥ 96.90%, and also further ≥ 97.85%.

[0039] The present invention provides the melted niobium prepared by the preparation method described in the above technical solution. The Ta content in the melted niobium is 800 - 950 ppm, specifically 800 - 880 ppm in the embodiments; The Si content is 120 - 145 ppm. The impurity content in the melted niobium prepared by the method of the present invention is relatively low.

[0040] Figure 1 This is the process flow diagram for preparing melted niobium in the embodiments of the present invention. Below, the technical solutions in the present invention will be clearly and completely described in combination with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

[0041] In the following experiments, the niobium source used is niobium pentoxide (Nb2O5) powder. The niobium source includes a first niobium source and a second niobium source. The Ta content in the first niobium source is 1600 ppm and the Si content is 400 ppm. The Ta content in the second niobium source is 100 ppm and the Si content is 30 ppm; The mass ratio of the first niobium source to the second niobium source is 1:2.15.

[0042] The aluminum source used in the following experiments is aluminum (Al) powder; the aluminum source includes a first aluminum source and a second aluminum source, the Si content in the first aluminum source is 300 ppm, and the Si content in the second aluminum source is 30 ppm; the mass ratio of the first aluminum source to the second aluminum source is 0.4:1.

[0043] Example 1

[0044] In this example, the method for preparing molten niobium using a niobium source and an aluminum source includes the following steps:

[0045] (1) Aluminothermic reduction reaction:

[0046] Accurately weigh the niobium source and the aluminum source according to the composition of the niobium-aluminum alloy; load the niobium source and the aluminum source into a mixer, lock the inlet and outlet seals of the mixer, after mixing for 60 min, stop the machine and let it stand for 20 min, then open the mixer seal to avoid spontaneous combustion caused by friction heating during the mixing process, transfer the obtained mixed powder into a conical hopper, and transport it to the loading station for furnace charging;

[0047] Put the mixed powder into a crucible and compact it in the furnace body; connect the ignition wire (the contact point on the conductive wire is cleaned to ensure good contact), and send electricity to test the conductivity. After the conductivity is normal, wait for the conductive wire to cool, then place it at the center position on the surface of the mixed powder, and cover the spiral wire completely with an ignition agent (specifically potassium permanganate, 15 g); confirm again that the heating wire and the conductive wire of the ignition device are in good condition, then hoist the furnace cover to seal the reactor, check to ensure that the furnace cover and the furnace body are well sealed; turn on the cooling water (water pressure ≥ 0.1 MPa), after confirming that the waterway is unobstructed, start the mechanical pump, open the micro-extraction valve, and evacuate the furnace to below 300 Pa; after the evacuation is completed, close the micro-extraction valve and stop the mechanical pump; connect the ignition power supply from the console for ignition; when the ignition ammeter indicates 0 instantaneously, that is, the ignition wire melts, then the ignition ends, and cut off the ignition power supply; after ignition, the pressure gauge indicates that the pressure in the furnace rises, then start the aluminothermic reduction reaction, at this time the temperature in the furnace begins to rise, and the reaction reaches the bottom of the crucible;

[0048] After the aluminothermic reduction reaction for 10 min, perform natural cooling for 50 min, then start the evacuation system to evacuate the furnace body, the evacuation time is 3 h, then stop the evacuation, perform vacuum cooling for 10 h, then open the air release valve to break the vacuum in the furnace chamber; open the furnace cover, and lift the crucible out of the furnace body; collect the obtained reduction slag (mainly composed of alumina), weigh it, crush it, transport it out and store it. After the obtained cake is naturally cooled, use a awl and a wire brush to remove the slag adhering to its surface, ensure that there is no visible adhering slag on the surface and the fracture of the cake, weigh, label and record the cleaned cake; then crush the cake with a jaw crusher to a particle size of ≤ 30 mm (prevent sparks from being generated during the crushing process to cause a fire) to obtain a niobium-aluminum alloy (average Nb content is 88.2 wt%);

[0049] (2) First melting:

[0050] Clean the furnace chamber, copper crucible and gun barrel of the EB 450kW horizontal furnace. Load the niobium-aluminum alloy into 3 copper crucibles respectively (the loading amount of niobium-aluminum alloy in each copper crucible is 65kg). Then wipe the sealing surface of the furnace door and close the furnace door. Click "Pump on" on the "Vacuum Furnace Chamber" interface on the operation cabinet, preselect all relevant vacuum pumps and valves, and the vacuum system will automatically evacuate the furnace chamber. Then click "Pump on" on the vacuum "Gun Chamber" interface, and the vacuum system will automatically evacuate the gun chamber. When the vacuum pressure in the furnace chamber ≤ 5×10 0 Pa, click the "Molecular Pump" icon on the "EB Gun" interface to preselect the turbo pump. After the "Molecular Pump" icon stops flashing, turn on the stroboscopic power supply, turn on the deflection scanning focusing power supply and the gun cooling fan, turn on the high-voltage cabinet power supply, turn on the filament, secondary high voltage and main high voltage power supplies. When the pressure in the gun chamber ≤ 5×10 -1 Pa and the pressure in the furnace chamber ≤ 5×10 -1 Pa, heat the emission cathode for 5 minutes. Then turn on the main high voltage, manually adjust the emission current adjustment potentiometer of the gun until the electron beam reaches the surface of the niobium-aluminum alloy. Observe the position through the stroboscope and adjust the position of the electron beam with the X / Y deflection potentiometer respectively (if the electron beam diverges, the focusing can be adjusted 1 - 2 times respectively) until the best focusing effect is achieved;

[0051] Adjust the scanning pattern and increase the emission current to the process requirement value. Adjust the position of the electron beam and the residence time of the electron beam according to the melting situation of the molten pool to control the melting speed for the first melting. After the first melting is completed, cool the obtained material under vacuum conditions. After the cooling is completed, click "Stop pumping the furnace chamber". After the relevant valves are automatically closed, click "Ventilation on" to vent the furnace chamber to obtain the niobium precursor for melting. The conditions for the first melting and cooling include: melting pressure ≤ 5.0×10 - 1 Pa, melting power is 250kW, melting speed is 50kg / h, and cooling time is 1h. During the first melting process, observe the changes in the water temperature of the crucible, vacuum, pressure table temperature and deflection value. If it exceeds the set value, an alarm will be issued and the high voltage will be blocked ultimately;

[0052] (3) Second melting:

[0053] Refer to the method in step (2) to conduct the second melting and cooling of the niobium precursor for melting to obtain the niobium for melting. The conditions for the second melting and cooling include: melting pressure ≤ 5.0×10 -1 Pa, melting power is 260kW, melting speed is 50kg / h, and cooling time is 2h.

[0054] In this example, the Ta content in the smelted niobium is 800 - 880 ppm and the Si content is 120 - 145 ppm.

[0055] Example 2 Orthogonal Test of Horizontal Furnace Melting

[0056] To verify the relationship between the melting speed, melting power and yield during the two - stage melting process in the horizontal furnace, in this example, an orthogonal test of horizontal furnace melting with three levels and four factors was carried out according to the operation steps in Example 1. Specifically, it was operated according to the method in Example 1, and the only differences were the melting speed and melting power of the first melting and the second melting. The steps are as follows:

[0057] Expected goal: The yield of the smelted niobium obtained after the niobium - aluminum alloy is melted twice in the horizontal furnace: Nb ≥ 98% × 98% = 96.04% (that is, the Nb yield is calculated as 98% after each melting).

[0058] Test raw materials: 195 kg / furnace × 9 furnaces of niobium - aluminum alloy were selected, with a total of 1755 kg.

[0059] The test plan is shown in Table 1.

[0060] Table 1 Orthogonal Test Plan of Horizontal Furnace Melting

[0061]

[0062] L9(3 4 ) The orthogonal test and test results are shown in Table 2.

[0063] Table 2 Orthogonal Test Results of Horizontal Furnace Melting

[0064]

[0065]

[0066] As can be seen from Table 2, in this example, for the orthogonal test of horizontal furnace melting, 195 kg / furnace × 9 furnaces of niobium - aluminum alloy were input, and the total output of smelted niobium was 1490.75 kg. Calculated based on the average Nb content in the niobium - aluminum alloy being 88.2 wt%, the total yield of the smelted niobium was 1490.75 / (195×9×0.882) = 96.3% > 96.04% (98% × 98% = 96.04%), that is, the total yield of the smelted niobium reached the test expectation.

[0067] At the same time, as can also be seen from Table 2, in this example, for the orthogonal test of horizontal furnace melting, the best melting conditions corresponding to the highest yield of smelted niobium are: the melting speed of the first melting is 50 kg / h and the melting power is 250 kW; the melting speed of the second melting is 50 kg / h and the melting power is 260 kW.

[0068] In addition, the test results of the smelted niobium obtained from the orthogonal test of horizontal furnace smelting in the embodiments of the present invention show that there are no obvious abnormal conditions in the chemical element indexes of the smelted niobium. Therefore, the orthogonal test of horizontal furnace smelting with three factors and four levels carried out this time has achieved the expected test results.

[0069] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of smelted niobium, comprising the following steps: Providing a niobium source and an aluminum source, wherein the niobium source is niobium pentoxide powder, and the aluminum source is aluminum powder; Mixing the niobium source and the aluminum source, and performing an aluminothermic reduction reaction to obtain a niobium-aluminum alloy, wherein the Nb content in the niobium-aluminum alloy is 85-89 wt%; Performing first smelting and second smelting on the niobium-aluminum alloy in sequence to obtain the smelted niobium; The conditions for the first smelting include: smelting pressure ≤ 5.0×10 -1 Pa, smelting power is 230 - 270 kW, and smelting speed is 35 - 50 kg / h; The conditions for the second smelting include: smelting pressure ≤ 5.0×10 -1 Pa, smelting power is 230 - 270 kW, and smelting speed is 40 - 55 kg / h.

2. The preparation method according to claim 1, characterized in that, The niobium source includes a first niobium source and a second niobium source, and the mass ratio of the first niobium source to the second niobium source is 1:2-2.3; the Ta content in the first niobium source is 1000-1800 ppm, and the Si content is 250-500 ppm; the Ta content in the second niobium source is 30-150 ppm, and the Si content is 0-50 ppm.

3. The preparation method according to claim 1, wherein The aluminum source includes a first aluminum source and a second aluminum source, and the mass ratio of the first aluminum source to the second aluminum source is 0.3-0.5:1; the Si content in the first aluminum source is 200-350 ppm; the Si content in the second aluminum source is 20-50 ppm.

4. The preparation method according to claim 1, characterized in that, The aluminothermic reduction reaction is initiated by an ignition agent, and the ignition agent includes potassium permanganate, magnesium-aluminum powder or sodium chlorate.

5. The preparation method according to claim 4, characterized in that, The time of the aluminothermic reduction reaction is 5-30 min.

6. The preparation method according to claim 4, characterized in that, After the aluminothermic reduction reaction, it further includes: cooling the material obtained after the aluminothermic reduction reaction, then removing the reduction slag and collecting the cake, and crushing the cake to a particle size ≤ 80 mm to obtain the niobium-aluminum alloy.

7. The preparation method according to claim 1, characterized in that, After the first smelting and the second smelting, it independently further includes cooling. The cooling time after the first smelting is ≥ 0.5 h; the cooling time after the second smelting is ≥ 1.5 h.

8. The preparation method according to claim 1, characterized in that, The first smelting and the second smelting are carried out in an EB450 kW horizontal furnace.

9. The preparation method according to any one of claims 1 to 8, characterized in that The yield of the smelted niobium is ≥ 93.5%.

10. The smelted niobium prepared by the preparation method according to any one of claims 1-9, wherein the Ta content in the smelted niobium is 800-950 ppm, and the Si content is 120-145 ppm.

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