Preparation method of high-purity vanadium

Abstract

The invention relates to the technical field of metal materials, and discloses a preparation method of high-purity vanadium, which comprises the following steps: step 1, controlling the purity, granularity and content of raw materials for preparing a vanadium-aluminum intermediate alloy; 2, carrying out an aluminothermic reaction in a vacuum aluminothermic smelting furnace; thirdly, a plate ingot is smelted in a vacuum electron beam horizontal furnace for the first time; fourthly, the plate ingot is smelted in the vacuum electron beam horizontal furnace for the second time; and 5, smelting the high-purity vanadium ingot in a vacuum electron beam ingot pulling furnace. According to the method, traditional slag formers such as CaO are not used, so that alloy components are more stable in the smelting process, component fluctuation caused by the reaction of the slag formers and main reactants is reduced, the reaction temperature and degree are controlled by controlling the addition amount of the Al2O3 cooling material, energy is saved, and the smelting cost is reduced; the beneficial effects that a CaO slag former does not need to be used, and introduction of impurities is avoided are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of metal materials, in particular to a method for preparing high-purity vanadium. Background Art

[0002] The main methods for preparing high-purity vanadium ingots are chemical vapor deposition, chemical precipitation, vacuum consumable electrode melting, and aluminothermic reduction. Chemical vapor deposition is a method of forming a thin film by chemical reaction in a vacuum environment. Although this method has versatility, its disadvantages are that the operation is complicated and the cost is high.

[0003] In order to solve the existing defects, it was found through searching that the publication number CN110923476A discloses a three-step method (aluminothermic reaction - horizontal electron beam furnace melting - electron beam ingot furnace melting) for producing high-purity metal vanadium ingots. The method uses high-purity vanadium pentoxide and high-purity aluminum powder as raw materials, adopts vacuum aluminothermic method with argon protection to produce vanadium aluminum alloy containing about 90% vanadium, melts into metal vanadium plates in a horizontal electron beam melting furnace, and then melts into ingots in an electron beam ingot furnace.

[0004] However, the carbon, nitrogen and oxygen contents of the vanadium aluminum alloy produced by the aluminothermic method in the aforementioned public patent technology reached 0.04%, 0.004% and 0.06% respectively, and the iron content reached 0.1%. After horizontal electron beam melting, the carbon and nitrogen contents increased to 0.05% and 0.008% respectively, the silicon content also increased, and the iron content only decreased to 0.08%. Moreover, after being melted into an ingot by an electron beam ingot casting furnace twice, the upper and lower ends need to be cut off twice, resulting in a lower product yield, more material waste, and higher product costs. Summary of the invention

[0005] Technical issues solved:

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing high-purity vanadium, which has the advantages of low content of impurities such as carbon, nitrogen, and oxygen in the vanadium ingot and high product yield, thus solving the problems of the above-mentioned technologies. Technical solution:

[0007] To achieve the above object, the present invention provides the following technical solution: a method for preparing high-purity vanadium, comprising the following steps:

[0008] Step 1: Control the purity, particle size and content of the raw material for preparing the vanadium-aluminum master alloy: Based on the mass of V2O5 powder, prepare the alloy raw material according to the mass ratio of V2O5 powder to Al powder of 100:(56.0-57.1), and configure the mass of Al2O3 coolant to be 0.34-0.54 times the mass of V2O5 powder;

[0009] Step 2, conducting a thermite reaction in a vacuum aluminothermic smelting furnace: after mixing the baked V2O5 powder, the newly opened Al powder and the Al2O3 cooling material for 3 to 5 hours, the mixture is spread into the reactor of the aluminothermic furnace in 3 to 5 layers and compacted, and then 10 to 25 g of a magnesium chip igniter with a diameter of 100 to 300 mm is spread on the top of the mixture, and then the furnace cover is closed, and the aluminothermic smelting furnace is evacuated to a vacuum degree of less than 10 Pa, and then the vacuum is stopped and argon is filled to a pressure of -0.08 MPa in the furnace, and the ignition agent is ignited to start the self-propagating reaction smelting of the alloy. After 30 to 60 minutes, the furnace body is evacuated, and the temperature change in the furnace is observed. After the alloy is allowed to stand until the temperature in the smelting furnace is lower than 100°C, the vacuum is stopped to complete the smelting of the alloy, and the obtained alloy cake is separated from the slag, and the slag and defects on the surface of the alloy cake are removed by manual finishing and a grinder is used to crush the alloy cake into particles ≤50 mm to complete the thermite reaction;

[0010] Step 3: First vacuum electron beam horizontal furnace smelting plate ingot: Place the vanadium-aluminum alloy particles with a particle size of ≤50 mm obtained in the second step in the copper crucible of the vacuum electron beam horizontal furnace, and then close the furnace door to evacuate the furnace body. When the vacuum degree of the furnace chamber is less than 5.0×10 -2 Pa, the vacuum degree of the gun chamber is less than 5×10 -3 Pa, start cathode heating for 5 to 10 minutes, adjust the emission current of the electron gun to 0.5 to 3A, adjust the position of the electron beam and adjust the scanning pattern, and stretch a small dot of the electron beam emitted from the center of the crucible to 10 to 20 cm horizontally, and then the vacuum degree in the furnace is better than 5×10 -3 Pa, the melting starts from the top position, and the melting is scanned to the tail end at a speed of 0.6-0.7 mm / s. During the melting process, the electron beam stays in the molten pool for 3-5 seconds to melt the raw materials through, and the melting ends at the tail end of the crucible molten pool. After cooling, the furnace is taken out, and the first vacuum electron beam horizontal furnace melting plate ingot is completed;

[0011] Step 4: Second vacuum electron beam horizontal furnace melting of plate ingot: turn over the plate ingot obtained in step 3, turn the head of the previous plate ingot into the tail after turning over, and perform secondary melting. The secondary melting will repeat the steps of the first melting; the vacuum degree in the furnace is better than 5×10 -3 When the temperature is 0.0400°C, the electron beam is drawn from 10 to 20 cm away from the head of the crucible. After the beam is drawn normally, the electron beam is widened to 10 to 20 cm from the head of the crucible molten pool, and the melting is scanned toward the tail end at a speed of 0.6 to 0.7 mm / s. The other technical parameters of the operation are the same as those of the third step. After the secondary melting is completed, the plate ingot is taken out of the furnace after cooling, and the second vacuum electron beam horizontal furnace melting of the plate ingot is completed.

[0012] Step 5: Smelting high-purity vanadium ingots in a vacuum electron beam ingot pulling furnace: Cut the plate ingot obtained in step 4 into long strips using a shearing machine, weld the long strips into electrodes using an argon arc welder, and load them into the silo of the vacuum electron beam ingot pulling furnace. Close the silo door and evacuate the silo. When the vacuum degree of the gun chamber is ≤5×10 -3 After Pa, cathode heating is started for 5 to 10 minutes, the emission current of the gun is adjusted to 0.5 to 3A, the position of the electron beam is adjusted, and the X horizontal and Y vertical directions of the scanning pattern are adjusted not to exceed 20mm from the crucible mouth. Then, smelting is started. When the molten steel level rises to 10mm from the crucible mouth, the ingot is pulled downward. The smelting power is controlled at 240 to 250kW and the ingot pulling speed is 0.8 to 1.5mm / s until the smelting is completed. After cooling for 3 to 5 hours, the high-purity vanadium ingot is smelted in the vacuum electron beam ingot pulling furnace, and the surface of the vanadium ingot is turned by 0.5 to 1.5mm to obtain a cylindrical pure vanadium ingot.

[0013] Preferably, the proportion of aluminum in the vanadium-aluminum master alloy is 10.5-12%, so as to obtain an AlV89 alloy containing about 11% Al, thereby ensuring that the thermite reaction is fully carried out while obtaining a lower aluminum content.

[0014] Preferably, for the AlV89 alloy, the mass of Al powder in the weighed raw material is 0.560 to 0.571 times the mass of V2O5 powder, and the mass of Al2O3 coolant is 0.34 to 0.54 times the mass of V2O5 powder.

[0015] Preferably, the purity of the V2O5 powder is not less than 99.9%, and the iron Fe≤0.005%, the silicon Si≤0.015%, the carbon C≤0.007%, the nitrogen N≤0.015%, and the particle size is greater than 325 mesh≤0.045mm.

[0016] Preferably, the purity of the Al powder is not less than 99.9%, and Fe≤0.001%, Si≤0.005%, O≤0.068%, C≤0.020%, N≤0.003%, and the particle size is ≤0.075 mm through 200 mesh.

[0017] Preferably, the Al2O3 cooling material is Al2O3 powder or Al2O3 return slag after the aluminum heat reaction of AlV89 alloy, with a particle size of 1 to 3 mm.

[0018] Preferably, the purity of the Al2O3 powder is not less than 99.9%, and the contents of other impurity elements are Fe≤0.01%, Si≤0.02%, N≤0.02%, and C≤0.01%.

[0019] Preferably, the purity of the Al2O3 returned slag is not less than 99.5%, and the contents of other impurity elements are Fe≤0.01%, Si≤0.03%, N≤0.05%, and C≤0.05%.

[0020] Preferably, the cooling time of the plate ingot melted in the vacuum electron beam horizontal furnace for the first time in step 3 is 1 to 3 hours.

[0021] Preferably, the cooling time of the plate ingot melted in the second vacuum electron beam horizontal furnace in step 4 is 2 to 3 hours.

[0022] Compared with the prior art, the present invention provides a method for preparing high-purity vanadium, which has the following beneficial effects:

[0023] 1. The present invention applies a vacuum environment to the smelting process, evacuates the aluminum hot smelting furnace to a vacuum degree of less than 10Pa, and in the vacuum state, oxygen and nitrogen in the air are excluded, greatly reducing their contact with reactants, thereby avoiding the formation of impurities in the alloy by oxygen and nitrogen in the reaction; argon is filled to a negative pressure of -0.08MPa in the furnace to obtain a higher internal pressure, which is equivalent to increasing the vapor pressure in the furnace and reducing the volatilization of alloy elements during the smelting process; and then the purity of the alloy is further protected by continuous vacuuming, thereby achieving the beneficial effect of avoiding the loss of reaction heat and the influence of impurities such as oxygen and nitrogen in the air on the purity of the alloy.

[0024] 2. The present invention does not use traditional slag-forming agents such as CaO, thereby making the alloy composition more stable during the smelting process, reducing the composition fluctuation caused by the reaction of the slag-forming agent with the main reactant, and controlling the temperature and degree of the reaction by controlling the addition amount of Al2O3 coolant, thereby saving energy and reducing smelting costs, achieving the beneficial effect of not needing to use CaO slag-forming agent and avoiding the introduction of impurities.

[0025] 3. The present invention emphasizes the control of the purity of raw materials before the aluminothermic reaction, especially the strict control of the content of Fe, Si, C, N, and O in the raw materials. To produce high-purity vanadium ingots, the vanadium-aluminum intermediate alloy obtained by ordinary aluminothermic reaction cannot be used, but it is necessary to carry out the aluminothermic reaction in a vacuum aluminothermic smelting furnace. At the temperature of melting AlV89 alloy (about 1910°C), theoretically, horizontal electron beam melting can remove some impurities with higher saturated vapor pressure than vanadium (0.02kPa) by evaporation, such as aluminum (>40kPa), chromium (3.0kPa), iron (>0.7 kPa), silicon (>0.1kPa), but except for the evaporation coefficient of aluminum of 679.3, the actual evaporation coefficients of chromium, iron and silicon are only 0.02, 0.02 and 0.001, which are much smaller than the evaporation coefficient of 10 required for rapid evaporation of impurity elements. It is actually difficult to effectively evaporate and remove impurity elements such as chromium, iron and silicon within the limited smelting time of a few seconds. The removal efficiency can only be improved by increasing the vacuum degree in the furnace and extending the smelting time to 3-5 seconds. By turning over and smelting twice, in addition to improving the uniformity of the composition of the plate ingot, the content of impurity elements can also be reduced.

[0026] The vacuum electron beam ingot pulling furnace has the same effect as the horizontal electron beam melting furnace in removing impurities. It also has the same effect as the density of V (5.8g / cm 3 ) is poor, such as aluminum in alloy (2.7g / cm 3 ), silicon (2.33 g / cm 3 ), carbon (2.267 g / cm 3 ), iron (7.86 g / cm 3 ), chromium (7.19 g / cm 3 ) and other impurities, so that low-density impurities float up and high-density impurities sink to remove impurity elements again. In order to improve the effect of removing impurities, the smelting power must be controlled at 240-250kW and the ingot pulling speed must be controlled at 0.8-1.5mm / s, so as to achieve the purpose of achieving high purity of vanadium ingots in one ingot pulling furnace smelting and reduce the amount of end face removal;

[0027] Oxygen removal is mainly carried out by evaporating metal oxides and reacting carbon with oxygen. However, the evaporation deoxidation coefficient of FeO, CrO, and VO is less than 10, so the deoxidation effect is not good. The evaporation deoxidation coefficient of Al2O3 and SiO is much greater than 10. 3 ; 11% Al by mass removes 9.8% by mass of oxygen, which is much higher than the impurity oxygen content in the alloy. This is one of the reasons why the AlV89 master alloy is first melted in the design of the thermite reaction. In addition, the high vacuum degree is conducive to the full reaction of carbon and oxygen and the evaporation of Al2O3 and SiO, thus improving the deoxidation effect;

[0028] Therefore, the present invention strictly controls the purity of the alloy raw materials in the aluminothermic reaction, especially the content of Fe, Si, C, N, and O, reduces the content of impurities from the source, thereby improving the purity of the final product, and at the same time reduces the amount of rejection at both ends of the cylindrical pure vanadium ingot produced by the vacuum electron beam ingot pulling furnace, thereby achieving the beneficial effect of saving costs and increasing the product yield to more than 85%.

[0029] 4. The aluminum-vanadium alloy product produced by the present invention through the design of thermite reaction is AlV89, and the aluminum content is limited to 11%, thereby ensuring the full progress of thermite reaction; at the same time, the deoxidation effect is improved, the total amount of raw material loss of Al evaporated in the electron beam melting furnace is reduced, the cost is reduced, and the yield of pure vanadium products is increased.

[0030] 5. The present invention reduces the impurity content of AlV89 alloy to 10.5≤Al≤12.0%, C≤0.015%, N≤0.004%, O≤0.07%, Fe≤0.015%, Cr≤0.005%, Si≤0.008% after thermite reaction by controlling the purity of raw materials and implementing two electron beam horizontal melting and one ingot pulling furnace melting; after two vacuum electron beam horizontal furnace melting, the impurity content of pure vanadium plate ingot is reduced to Al≤0.025 %, C≤0.008%, N≤0.002%, O≤0.030%, Fe≤0.008%, Cr≤0.001%, Si≤0.0035%; after smelting in a vacuum electron beam ingot pulling furnace, the impurity content in the columnar pure vanadium ingot is reduced to Al≤0.008%, C≤0.003%, N≤0.0015%, O≤0.025%, Fe≤0.005%, Cr≤0.001%, Si≤0.0030%, and the product yield is greater than 85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the steps of the present invention; DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] The first step is to control the purity, particle size and content of the raw materials for preparing vanadium aluminum master alloy

[0035] Weigh 100 kg of V2O5 powder, 56.0 kg of Al powder and 34 kg of Al2O3 powder (equivalent to a mass ratio of V2O5:Al:Al2O3=1:0.56:0.34) respectively, and place them in stainless steel pans for later use;

[0036] The purity of V2O5 powder is 99.91%, and Fe≤0.005%, Si≤0.015%, C≤0.007%, N≤0.015%, and the particle size is ≤0.045mm over 325 mesh; the purity of Al powder is 99.9%, and Fe≤0.001%, Si≤0.005%, O≤0.068%, C≤0.020%, N≤0.003%, and the particle size is ≤0.075mm over 200 mesh; Al2O3 coolant uses ordered Al2O3 powder with a particle size of 1 to 3mm, a purity of 99.92%, and Fe≤0.01%, Si≤0.02%, N≤0.02%, and C≤0.01%;

[0037] The second step is to carry out the aluminum heat reaction in a vacuum aluminum heat smelting furnace

[0038] After mixing the baked V2O5 powder, the newly opened Al powder and the Al2O3 cooling material for 3 hours, the mixture is spread into the reactor of the aluminothermic furnace in 3 layers and compacted, and then 10g of magnesium chips igniter with a diameter of 100mm is spread on the top of the mixture and the furnace cover is closed. The aluminothermic smelting furnace is evacuated to a vacuum degree of less than 10Pa, and then the evacuation is stopped and argon gas is filled to a pressure of -0.08MPa in the furnace, and the ignition agent is ignited to start the self-propagating reaction smelting of the alloy. After 30 minutes, the furnace body is evacuated, and the temperature change in the furnace is observed. After the alloy is left to stand until the temperature in the smelting furnace is lower than 100°C, the evacuation is stopped to complete the smelting of the alloy, and the obtained alloy cake is separated from the slag, and the slag and defects on the surface of the alloy cake are removed by manual finishing and a grinder is used to crush the cake into particles ≤50mm to complete the aluminothermic reaction;

[0039] The AlV89 alloy prepared in this embodiment was subjected to chemical composition analysis at more than three locations. An inductively coupled plasma atomic emission spectrometer was used to detect the chemical composition of Al, Fe, Cr, Si, and V. An oxygen and nitrogen analyzer was used to detect O and N. A carbon and sulfur analyzer was used to detect C (the detection method is the same in the following embodiments). The element detection data showed that the mass percentages of V and Al were 89.4409% and 10.4421% on average, and the contents of other impurity elements were C≤0.015%, N≤0.0038%, O≤0.07%, Fe≤0.0148%, Cr≤0.005%, and Si≤0.008% respectively.

[0040] The third step is to melt the plate ingot in a vacuum electron beam horizontal furnace for the first time.

[0041] The vanadium-aluminum alloy particles with a particle size of ≤50 mm prepared in the second step were placed in the copper crucible of the vacuum electron beam horizontal furnace, and then the furnace door was closed to evacuate the furnace body. When the vacuum degree of the furnace chamber was less than 5.0×10 -2 Pa, the vacuum degree of the gun chamber is less than 5×10 -3Pa, start cathode heating for 5 minutes, adjust the emission current of the electron gun to 0.5A, adjust the position of the electron beam and adjust the scanning pattern, and stretch a small dot of the electron beam emitted from the center of the crucible to 10-20cm horizontally, and then the vacuum degree in the furnace is better than 5×10 -3 The melting starts from the top position at 1.50 Pa, and the melting is scanned to the tail end at a speed of 0.6 mm / s. During the melting process, the electron beam stays in the molten pool for 3 seconds to melt the raw materials thoroughly. The melting is completed in sequence until the tail end of the crucible molten pool. After cooling for 1 hour, the furnace is taken out, completing the first vacuum electron beam horizontal furnace melting plate ingot;

[0042] Step 4: Second vacuum electron beam horizontal furnace melting of plate ingot

[0043] The plate ingot obtained in step 3 is turned over, and the head of the previous plate ingot is turned into the tail after turning over, and a second smelting is performed. The second smelting will repeat the steps of the first smelting; the vacuum degree in the furnace is better than 5×10 -3 When the temperature is 0.045°C, the electron beam is drawn from 10 to 20 cm away from the head of the crucible. After the electron beam is drawn normally, the electron beam is widened to 10 to 20 cm from the head of the crucible molten pool, and the melting is performed at a speed of 0.7 mm / s to the tail end. The other technical parameters of the operation are the same as those of the third step. After the secondary melting is completed, the plate ingot is taken out of the furnace after cooling for 2 hours, and the second vacuum electron beam horizontal furnace melting plate ingot is completed.

[0044] The size of the plate ingot obtained is 1180mm long×230mm wide×20mm thick; the plate is hoisted by a crane and placed on a clean platform, and then 5-10g of particles with a diameter of about 0.5mm are selected from the upper, middle and lower parts of the plate by hammering for chemical composition inspection. The mass percentage of V is 99.922% on average, and the contents of other impurity elements are Al≤0.025%, C≤0.008%, N≤0.0018%, O≤0.030%, Fe≤0.0079%, Cr≤0.001%, and Si≤0.0034% respectively;

[0045] Step 5: Vacuum electron beam ingot pulling furnace to melt high-purity vanadium ingots

[0046] The plate ingot obtained in step 4 is cut into strips of about 500-600 mm in length and about 100-120 mm in width by a shearing machine, and the strip ingot is welded into electrodes by an argon arc welding machine, and loaded into the silo of the vacuum electron beam ingot pulling furnace, and the silo door is closed to evacuate. When the vacuum degree of the gun chamber is ≤5×10 -3After Pa, cathode heating was started for 5 minutes, the emission current of the gun was adjusted to 0.5A, the position of the electron beam was adjusted, and the X horizontal and Y vertical directions of the scanning pattern were adjusted not to exceed 20mm from the crucible mouth. Then smelting began. When the molten steel level rose to 10mm from the crucible mouth, the ingot was pulled downward. The smelting power was controlled at 240kW and the ingot pulling speed was 1.5mm / s until the smelting was completed. After cooling for 3 hours, the high-purity vanadium ingot was smelted in the vacuum electron beam ingot pulling furnace. The surface of the vanadium ingot was turned by 0.5mm to obtain a cylindrical pure vanadium ingot.

[0047] The obtained pure vanadium ingot is a cylinder with a diameter of 175 mm and a height of 1600 mm. The chemical composition of the pure vanadium columnar ingot obtained in this embodiment is tested at more than three positions. The mass percentage of V is 99.959% on average. The contents of other impurity elements are Al≤0.0078%, C≤0.0029%, N≤0.0014%, O≤0.021%, Fe≤0.0036%, Cr≤0.001%, Si≤0.0030%, and the product yield is 85.9%;

[0048] Example 2

[0049] The first step is to control the purity, particle size and content of the raw materials for preparing vanadium aluminum master alloy

[0050] Weigh 200 kg of V2O5 powder, 114.2 kg of Al powder and 108 kg of Al2O3 return slag (equivalent to mass ratio: V2O5:Al:Al2O3=1:0.571:0.54) respectively, and place them in stainless steel pans for later use;

[0051] The purity of V2O5 powder is 99.91%, and Fe≤0.005%, Si≤0.015%, C≤0.007%, N≤0.015%, and the particle size is ≤0.045mm over 325 mesh; the purity of Al powder is 99.9%, and Fe≤0.001%, Si≤0.005%, O≤0.068%, C≤0.020%, N≤0.003%, and the particle size is ≤0.075mm over 200 mesh; Al2O3 cooling material uses the Al2O3 return slag obtained in Example 1, with a particle size of 1-3mm, a purity of 99.7%, and Fe≤0.01%, Si≤0.022%, N≤0.025%, and C≤0.018%;

[0052] The second step is to carry out the aluminum heat reaction in a vacuum aluminum heat smelting furnace

[0053] After the baked V2O5 powder, the newly opened Al powder and the Al2O3 cooling material are mixed for 5 hours, the mixture is spread into the reactor of the aluminothermic furnace in 5 layers and compacted, and then 25g of magnesium chips igniter with a diameter of 300mm is spread on the top of the mixture and the furnace cover is closed. The aluminothermic smelting furnace is evacuated to a vacuum degree of less than 10Pa, and then the evacuation is stopped and argon gas is filled to a pressure of -0.08MPa in the furnace, and the ignition agent is ignited to start the self-propagating reaction smelting of the alloy. After 60 minutes, the furnace body is evacuated, and the temperature change in the furnace is observed. After the alloy is left to stand until the temperature in the smelting furnace is lower than 100°C, the evacuation is stopped to complete the smelting of the alloy, and the obtained alloy cake is separated from the slag, and the slag and defects on the surface of the alloy cake are removed by manual finishing and a grinder is used to crush the cake into particles ≤50mm to complete the aluminothermic reaction;

[0054] The AlV89 alloy prepared in this embodiment was subjected to chemical composition analysis at more than three locations. The mass percentages of V and Al were 87.8525% and 11.8969% on average, and the contents of other impurity elements were C≤0.0146%, N≤0.004%, O≤0.068%, Fe≤0.0099%, Cr≤0.0038%, and Si≤0.0079% respectively.

[0055] The third step is to melt the plate ingot in a vacuum electron beam horizontal furnace for the first time.

[0056] The vanadium-aluminum alloy particles with a particle size of ≤50 mm prepared in the second step were placed in the copper crucible of the vacuum electron beam horizontal furnace, and then the furnace door was closed to evacuate the furnace body. When the vacuum degree of the furnace chamber was less than 5.0×10 -2 Pa, the vacuum degree of the gun chamber is less than 5×10 -3 Pa, start cathode heating for 10 minutes, adjust the emission current of the electron gun to 3A, adjust the position of the electron beam and adjust the scanning pattern, and stretch a small dot of the electron beam emitted from the center of the crucible to 10-20cm horizontally, and then the vacuum degree in the furnace is better than 5×10 -3 The melting starts from the top position at Pa, and the melting is scanned to the tail end at a speed of 0.7 mm / s. During the melting process, the electron beam stays in the molten pool for 5 seconds to melt the raw materials through, and the melting ends at the tail end of the crucible molten pool. After cooling for 3 hours, the furnace is taken out, completing the first vacuum electron beam horizontal furnace melting plate ingot;

[0057] Step 4: Second vacuum electron beam horizontal furnace melting of plate ingot

[0058] The plate ingot obtained in step 3 is turned over, and the head of the previous plate ingot is turned into the tail after turning over, and a second smelting is performed. The second smelting will repeat the steps of the first smelting; the vacuum degree in the furnace is better than 5×10 -3When the temperature is 0.045°C, the electron beam is drawn from 10 to 20 cm away from the head of the crucible. After the beam is drawn normally, the electron beam is widened to 10 to 20 cm from the head of the crucible molten pool, and the melting is scanned toward the tail end at a speed of 0.6 mm / s. The other technical parameters of the operation are the same as those of the third step. After the secondary melting is completed, the plate ingot is taken out of the furnace after cooling for 3 hours, and the second vacuum electron beam horizontal furnace melting of the plate ingot is completed.

[0059] The size of the plate ingot obtained is 1180mm long×230mm wide×22mm thick; the plate is hoisted by a crane and placed on a clean platform, and then 5-10g of particles with a diameter of about 0.5mm are selected from the upper, middle and lower parts of the plate by hammering for chemical composition inspection. The mass percentage of V is 99.925% on average, and the contents of other impurity elements are Al≤0.024%, C≤0.0079%, N≤0.002%, O≤0.028%, Fe≤0.008%, Cr≤0.001%, and Si≤0.0035% respectively;

[0060] Step 5: Vacuum electron beam ingot pulling furnace to melt high-purity vanadium ingots

[0061] The plate ingot obtained in step 4 is cut into strips of about 500-600 mm in length and about 100-120 mm in width by a shearing machine, and the strip ingot is welded into electrodes by an argon arc welding machine, and loaded into the silo of the vacuum electron beam ingot pulling furnace, and the silo door is closed to evacuate. When the vacuum degree of the gun chamber is ≤5×10 -3 After Pa, cathode heating was started for 10 minutes, the emission current of the gun was adjusted to 3A, the position of the electron beam was adjusted, and the X horizontal and Y vertical directions of the scanning pattern were adjusted not to exceed 20mm from the crucible mouth. Then smelting began. When the molten steel level rose to 10mm from the crucible mouth, the ingot was pulled downward. The smelting power was controlled at 250kW and the ingot pulling speed was 0.8mm / s until the smelting was completed. After cooling for 5 hours, the high-purity vanadium ingot was smelted in the vacuum electron beam ingot pulling furnace. The surface of the vanadium ingot was turned by 1.0mm to obtain a cylindrical pure vanadium ingot.

[0062] The obtained pure vanadium ingot is a cylinder with a diameter of 175 mm and a height of 1582 mm. The chemical composition of the pure vanadium columnar ingot obtained in this embodiment is tested at more than three locations. The mass percentage of V is 99.949% on average. The contents of other impurity elements are Al≤0.008%, C≤0.0028%, N≤0.0015%, O≤0.025%, Fe≤0.0043%, Cr≤0.001%, Si≤0.0030%, and the product yield is 85.7%.

[0063] Example 3

[0064] The first step is to control the purity, particle size and content of the raw materials for preparing vanadium aluminum master alloy

[0065] Weigh 150 kg of V2O5 powder, 84.75 kg of Al powder and 67.5 kg of Al2O3 return slag (equivalent to mass ratio: V2O5:Al:Al2O3=1:0.565:0.45) respectively, and place them in stainless steel pans for later use;

[0066] The purity of V2O5 powder is 99.91%, and Fe≤0.005%, Si≤0.015%, C≤0.007%, N≤0.015%, and the particle size is ≤0.045mm over 325 mesh; the purity of Al powder is 99.9%, and Fe≤0.001%, Si≤0.005%, O≤0.068%, C≤0.020%, N≤0.003%, and the particle size is ≤0.075mm over 200 mesh; Al2O3 cooling material uses Al2O3 returned slag obtained in Example 2, with a particle size of 1-3mm, a purity of 99.5%, and Fe≤0.01%, Si≤0.03%, N≤0.05%, and C≤0.05%;

[0067] The second step is to carry out the aluminum heat reaction in a vacuum aluminum heat smelting furnace

[0068] After mixing the baked V2O5 powder, the newly opened Al powder and the Al2O3 cooling material for 4 hours, the mixture is spread into the reactor of the aluminothermic furnace in 4 layers and compacted, and then 20g of magnesium chips igniter with a diameter of 240mm is spread on the top of the mixture and the furnace cover is closed. The aluminothermic smelting furnace is evacuated to a vacuum degree of less than 10Pa, and then the evacuation is stopped and argon gas is filled to a pressure of -0.08MPa in the furnace, and the ignition agent is ignited to start the self-propagating reaction smelting of the alloy. After 40 minutes, the furnace body is evacuated, and the temperature change in the furnace is observed. After the alloy is left to stand until the temperature in the smelting furnace is lower than 100°C, the evacuation is stopped to complete the smelting of the alloy, and the obtained alloy cake is separated from the slag, and the slag and defects on the surface of the alloy cake are removed by manual finishing and a grinder is used to crush the cake into particles ≤50mm to complete the aluminothermic reaction;

[0069] The AlV89 alloy prepared in this embodiment was subjected to chemical composition analysis at more than three locations. The mass percentages of V and Al were 88.2876% and 11.4933% on average, and the contents of other impurity elements were C≤0.0148%, N≤0.0029%, O≤0.069%, Fe≤0.0132%, Cr≤0.0045%, and Si≤0.008% respectively.

[0070] The third step is to melt the plate ingot in a vacuum electron beam horizontal furnace for the first time.

[0071] The vanadium-aluminum alloy particles with a particle size of ≤50 mm prepared in the second step were placed in the copper crucible of the vacuum electron beam horizontal furnace, and then the furnace door was closed to evacuate the furnace body. When the vacuum degree of the furnace chamber was less than 5.0×10 -2Pa, the vacuum degree of the gun chamber is less than 5×10 -3 Pa, start cathode heating for 6 minutes, adjust the emission current of the electron gun to 2A, adjust the position of the electron beam and adjust the scanning pattern, and stretch a small dot of the electron beam emitted from the center of the crucible to 10-20cm horizontally, and then the vacuum degree in the furnace is better than 5×10 -3 The melting starts from the top position at Pa, and the melting is scanned to the tail end at a speed of 0.65mm / s. During the melting process, the electron beam stays in the molten pool for 4 seconds to melt the raw materials thoroughly. The melting is completed in sequence until the tail end of the crucible molten pool. After cooling for 2 hours, the furnace is taken out, completing the first vacuum electron beam horizontal furnace melting plate ingot;

[0072] Step 4: Second vacuum electron beam horizontal furnace melting of plate ingot

[0073] The plate ingot obtained in step 3 is turned over, and the head of the previous plate ingot is turned into the tail after turning over, and a second smelting is performed. The second smelting will repeat the steps of the first smelting; the vacuum degree in the furnace is better than 5×10 -3 When the temperature is 0.045°C, the electron beam is drawn from 10 to 20 cm away from the head of the crucible. After the beam is drawn normally, the electron beam is widened to 10 to 20 cm from the head of the crucible molten pool, and the melting is scanned toward the tail end at a speed of 0.6 mm / s. The other technical parameters of the operation are the same as those of the third step. After the secondary melting is completed, the plate ingot is taken out of the furnace after cooling for 2 hours, and the second vacuum electron beam horizontal furnace melting plate ingot is completed.

[0074] The size of the plate ingot obtained is 1180mm long×230mm wide×19mm thick; the plate is hoisted by a crane and placed on a clean platform, and then 5-10g of particles with a diameter of about 0.5mm are selected from the upper, middle and lower parts of the plate by hammering for chemical composition inspection. The mass percentage of V is 99.926% on average, and the contents of other impurity elements are Al≤0.023%, C≤0.008%, N≤0.002%, O≤0.030%, Fe≤0.0078%, Cr≤0.001%, and Si≤0.0032% respectively;

[0075] Step 5: Vacuum electron beam ingot pulling furnace to melt high-purity vanadium ingots

[0076] The plate ingot obtained in step 4 is cut into strips of about 500-600 mm in length and about 100-120 mm in width by a shearing machine, and the strip ingot is welded into electrodes by an argon arc welding machine, and loaded into the silo of the vacuum electron beam ingot pulling furnace, and the silo door is closed to evacuate. When the vacuum degree of the gun chamber is ≤5×10 -3After Pa, cathode heating was started for 5 minutes, the emission current of the gun was adjusted to 2A, the position of the electron beam was adjusted, and the X horizontal and Y vertical directions of the scanning pattern were adjusted not to exceed 20mm from the crucible mouth. Then smelting began. When the molten steel level rose to 10mm from the crucible mouth, the ingot was pulled downward. The smelting power was controlled at 250kW and the ingot pulling speed was 1.0mm / s until the smelting was completed. After cooling for 4 hours, the high-purity vanadium ingot was smelted in the vacuum electron beam ingot pulling furnace. The surface of the vanadium ingot was turned by 1.5mm to obtain a cylindrical pure vanadium ingot.

[0077] The obtained pure vanadium ingot is a cylinder with a diameter of 175 mm and a height of 1580 mm. The chemical composition of the pure vanadium columnar ingot obtained in this embodiment is tested at more than three locations, and the average mass percentage of V is 99.959%, ​​and the contents of other impurity elements are Al≤0.0076%, C≤0.003%, N≤0.0014%, O≤0.024%, Fe≤0.005%, Cr≤0.001%, Si≤0.0028%, and the product yield is 85.0%.

[0078] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-purity vanadium, characterized in that: The following steps are involved: Step 1: Control the purity, particle size and content of the raw material for preparing the vanadium-aluminum master alloy: Based on the mass of V2O5 powder, prepare the alloy raw material according to the mass ratio of V2O5 powder to Al powder of 100:56.0-57.1, and configure the mass of Al2O3 coolant to be 0.34-0.54 times the mass of V2O5 powder; Step 2, conducting a thermite reaction in a vacuum aluminothermic smelting furnace: after baking the V2O5 powder, the newly opened packaged Al powder is mixed with the Al2O3 cooling material for 3 to 5 hours, and then 3 to 5 layers are layered into the reactor of the aluminothermic furnace and compacted, and then 10 to 25 g of a magnesium chip ignition agent with a diameter of 100 to 300 mm is spread on the top of the mixture, and then the furnace cover is covered, and the aluminothermic smelting furnace is evacuated to a vacuum degree of less than 10Pa, and then the vacuum is stopped and argon is filled to a pressure of -0.08MPa in the furnace, and the ignition agent is ignited to start the self-propagating reaction smelting of the alloy. After 30 to 60 minutes, the furnace body is evacuated, and the temperature change in the furnace is observed. After the alloy is allowed to stand until the temperature in the smelting furnace is lower than 100°C, the vacuum is stopped to complete the smelting of the alloy, and the obtained alloy cake is separated from the slag, and the slag and defects on the surface of the alloy cake are removed by manual finishing and a grinder is used to crush it into particles ≤50mm to complete the aluminothermic reaction; Step 3: First vacuum electron beam horizontal furnace smelting plate ingot: Place the vanadium-aluminum alloy particles with a particle size of ≤50 mm obtained in the second step in the copper crucible of the vacuum electron beam horizontal furnace, and then close the furnace door to evacuate the furnace body. When the vacuum degree of the furnace chamber is less than 5.0×10 -2 Pa, the vacuum degree of the gun chamber is less than 5×10 -3 Pa, start cathode heating for 5 to 10 minutes, adjust the emission current of the electron gun to 0.5 to 3A, adjust the position of the electron beam and adjust the scanning pattern, and stretch a small dot of the electron beam emitted from the center of the crucible to 10 to 20 cm horizontally, and then the vacuum degree in the furnace is better than 5×10 -3 Pa, the melting starts from the top position, and the melting is scanned to the tail end at a speed of 0.6-0.7 mm / s. During the melting process, the electron beam stays in the molten pool for 3-5 seconds to melt the raw materials through, and the melting ends at the tail end of the crucible molten pool. After cooling, the furnace is taken out, and the first vacuum electron beam horizontal furnace melting plate ingot is completed; Step 4: Second vacuum electron beam horizontal furnace melting of plate ingot: turn over the plate ingot obtained in step 3, turn the head of the previous plate ingot into the tail after turning over, and perform secondary melting. The secondary melting will repeat the steps of the first melting; the vacuum degree in the furnace is better than 5×10 -3 When the temperature is 0.0400°C, the electron beam is drawn from 10 to 20 cm away from the head of the crucible. After the beam is drawn normally, the electron beam is widened to 10 to 20 cm from the head of the crucible molten pool, and the melting is scanned toward the tail end at a speed of 0.6 to 0.7 mm / s. The other technical parameters of the operation are the same as those of the third step. After the secondary melting is completed, the plate ingot is taken out of the furnace after cooling, and the second vacuum electron beam horizontal furnace melting of the plate ingot is completed. Step 5: Smelting high-purity vanadium ingots in a vacuum electron beam ingot pulling furnace: Cut the plate ingot obtained in step 4 into long strips using a shearing machine, weld the long strips into electrodes using an argon arc welder, and load them into the silo of the vacuum electron beam ingot pulling furnace. Close the silo door and evacuate the silo. When the vacuum degree of the gun chamber is ≤5×10 -3 After Pa, cathode heating is started for 5 to 10 minutes, the emission current of the gun is adjusted to 0.5 to 3A, the position of the electron beam is adjusted, and the X horizontal and Y vertical directions of the scanning pattern are adjusted not to exceed 20mm from the crucible mouth. Then, smelting is started. When the molten steel level rises to 10mm from the crucible mouth, the ingot is pulled downward. The smelting power is controlled at 240 to 250kW and the ingot pulling speed is 0.8 to 1.5mm / s until the smelting is completed. After cooling for 3 to 5 hours, the high-purity vanadium ingot is smelted in the vacuum electron beam ingot pulling furnace, and the surface of the vanadium ingot is turned by 0.5 to 1.5mm to obtain a cylindrical pure vanadium ingot.

2. The method for preparing high-purity vanadium according to claim 1, characterized in that: The proportion of aluminum in the vanadium-aluminum master alloy is 10.5-12%, so as to obtain an AlV89 alloy containing about 11% Al, thereby ensuring that the thermite reaction is fully carried out and obtaining a lower aluminum content.

3. The method for preparing high-purity vanadium according to claim 1, characterized in that: The AlV89 alloy has a weight of Al powder in the raw material of 0.560 to 0.571 times the weight of V2O5 powder, and a weight of Al2O3 coolant in the raw material of 0.34 to 0.54 times the weight of V2O5 powder.

4. The method for preparing high-purity vanadium according to claim 1, characterized in that: The purity of the V2O5 powder is not less than 99.9%, and the iron Fe is ≤0.005%, the silicon Si is ≤0.015%, the carbon C is ≤0.007%, the nitrogen N is ≤0.015%, and the particle size is ≤0.045mm over 325 mesh.

5. The method for preparing high-purity vanadium according to claim 1, characterized in that: The purity of the Al powder is not less than 99.9%, and Fe≤0.001%, Si≤0.005%, O≤0.068%, C≤0.020%, N≤0.003%, and the particle size is ≤0.075mm through 200 mesh.

6. The method for preparing high-purity vanadium according to claim 1, characterized in that: The Al2O3 cooling material is Al2O3 powder or Al2O3 return slag after the AlV89 alloy aluminothermic reaction, with a particle size of 1 to 3 mm.

7. The method for preparing high-purity vanadium according to claim 1, characterized in that: The purity of the Al2O3 powder is not less than 99.9%, and the contents of other impurity elements are Fe≤0.01%, Si≤0.02%, N≤0.02%, and C≤0.01%.

8. The method for preparing high-purity vanadium according to claim 1, characterized in that: The purity of the Al2O3 returned slag is not less than 99.5%, and the contents of other impurity elements are Fe≤0.01%, Si≤0.03%, N≤0.05%, and C≤0.05%.

9. The method for preparing high-purity vanadium according to claim 1, characterized in that: The cooling time of the plate ingot melted in the first vacuum electron beam horizontal furnace in step 3 is 1 to 3 hours.

10. The method for preparing high-purity vanadium according to claim 1, characterized in that: The cooling time of the plate ingot melted in the second vacuum electron beam horizontal furnace in step 4 is 2 to 3 hours.

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